Gene Summary

Gene:POU5F1; POU class 5 homeobox 1
Aliases: OCT3, OCT4, OTF3, OTF4, OTF-3, Oct-3, Oct-4
Summary:This gene encodes a transcription factor containing a POU homeodomain that plays a key role in embryonic development and stem cell pluripotency. Aberrant expression of this gene in adult tissues is associated with tumorigenesis. This gene can participate in a translocation with the Ewing's sarcoma gene on chromosome 21, which also leads to tumor formation. Alternative splicing, as well as usage of alternative AUG and non-AUG translation initiation codons, results in multiple isoforms. One of the AUG start codons is polymorphic in human populations. Related pseudogenes have been identified on chromosomes 1, 3, 8, 10, and 12. [provided by RefSeq, Oct 2013]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:POU domain, class 5, transcription factor 1
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (33)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Biomarkers, Tumor
  • Cell Differentiation
  • Pluripotent Stem Cells
  • Embryonic Stem Cells
  • Nanog Homeobox Protein
  • Neoplastic Cell Transformation
  • Breast Cancer
  • Epithelial-Mesenchymal Transition
  • Transduction
  • Chromosome 6
  • Gene Expression Profiling
  • Hyaluronan Receptors
  • AC133 Antigen
  • Swine
  • Germ Cell Tumours
  • Immunohistochemistry
  • Vimentin
  • Proto-Oncogene Proteins c-myc
  • Neoplasm Proteins
  • Cancer Gene Expression Regulation
  • Octamer Transcription Factor-3
  • Eye Cancer
  • Cancer Stem Cells
  • Cell Proliferation
  • DNA-Binding Proteins
  • Drug Resistance
  • POU5F1
  • RNA Interference
  • Cell Movement
  • Urothelium
  • Lung Cancer
  • Reproducibility of Results
  • MicroRNAs
  • Taiwan
  • Homeodomain Proteins
  • Promoter Regions
  • Thy-1 Antigens
  • Antineoplastic Agents
  • Kruppel-Like Transcription Factors
  • Apoptosis
  • Western Blotting
  • Down-Regulation
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: POU5F1 (cancer-related)

Zhu R, Gires O, Zhu L, et al.
TSPAN8 promotes cancer cell stemness via activation of sonic Hedgehog signaling.
Nat Commun. 2019; 10(1):2863 [PubMed] Free Access to Full Article Related Publications
Cancer stem cells (CSCs) represent a major source of treatment resistance and tumor progression. However, regulation of CSCs stemness is not entirely understood. Here, we report that TSPAN8 expression is upregulated in breast CSCs, promotes the expression of the stemness gene NANOG, OCT4, and ALDHA1, and correlates with therapeutic resistance. Mechanistically, TSPAN8 interacts with PTCH1 and inhibits the degradation of the SHH/PTCH1 complex through recruitment of deubiquitinating enzyme ATXN3. This results in the translocation of SMO to cilia, downstream gene expression, resistance of CSCs to chemotherapeutic agents, and enhances tumor formation in mice. Accordingly, expression levels of TSPAN8, PTCH1, SHH, and ATXN3 are positively correlated in human breast cancer specimens, and high TSPAN8 and ATXN3 expression levels correlate with poor prognosis. These findings reveal a molecular basis of TSPAN8-enhanced Sonic Hedgehog signaling and highlight a role for TSPAN8 in promoting cancer stemness.

Kim SL, Choi HS, Kim JH, et al.
Dihydrotanshinone-Induced NOX5 Activation Inhibits Breast Cancer Stem Cell through the ROS/Stat3 Signaling Pathway.
Oxid Med Cell Longev. 2019; 2019:9296439 [PubMed] Free Access to Full Article Related Publications
Cancer stem cells (CSCs) are known to mediate metastasis and recurrence and are therefore a promising therapeutic target. In this study, we found that dihydrotanshinone (DHTS) inhibits CSC formation. DHTS inhibited mammosphere formation in a dose-dependent manner and showed significant tumor growth inhibition in a xenograft model. This compound reduced the CD44

Musiał-Wysocka A, Kot M, Sułkowski M, et al.
Molecular and Functional Verification of Wharton's Jelly Mesenchymal Stem Cells (WJ-MSCs) Pluripotency.
Int J Mol Sci. 2019; 20(8) [PubMed] Free Access to Full Article Related Publications
The properties of mesenchymal stem cells (MSCs), especially their self-renewal and ability to differentiate into different cell lines, are widely discussed. Considering the fact that MSCs isolated from perinatal tissues reveal higher differentiation capacity than most adult MSCs, we examined mesenchymal stem cells isolated from Wharton's jelly of umbilical cord (WJ-MSCs) in terms of pluripotency markers expression. Our studies showed that WJ-MSCs express some pluripotency markers-such as NANOG, OCT-4, and SSEA-4-but in comparison to iPS cells expression level is significantly lower. The level of expression can be raised under hypoxic conditions. Despite their high proliferation potential and ability to differentiate into different cells type, WJ-MSCs do not form tumors in vivo, the major caveat of iPS cells. Owing to their biological properties, high plasticity, proliferation capacity, and ease of isolation and culture, WJ-MSCs are turning out to be a promising tool of modern regenerative medicine.

Jin X, Li Y, Guo Y, et al.
ERα is required for suppressing OCT4-induced proliferation of breast cancer cells via DNMT1/ISL1/ERK axis.
Cell Prolif. 2019; 52(4):e12612 [PubMed] Related Publications
OBJECTIVE: POU5F1 (OCT4) is implicated in cancer stem cell self-renewal. Currently, some studies have shown that OCT4 has a dual function in suppressing or promoting cancer progression. However, the precise molecular mechanism of OCT4 in breast cancer progression remains unclear.
MATERIALS AND METHODS: RT-PCR and Western blot were utilized to investigate OCT4 expression in breast cancer tissues and cells. Cell proliferation assays and mouse models were applied to determine the effects of OCT4 on breast cancer cell proliferation. DNMT1 inhibitors, ChIP, CoIP, IHC and ERα inhibitors were used to explore the molecular mechanism of OCT4 in breast cancer.
RESULTS: OCT4 was down-regulated in breast cancer tissues, and the overexpression of OCT4 promoted MDA-MB-231 cell proliferation and inhibited the proliferation of MCF-7 cells in vitro and in vivo, respectively. Two DNMT1 inhibitors (5-aza-dC and zebularine) suppressed OCT4-induced MDA-MB-231 cell proliferation through Ras/Raf1/ERK inactivation by targeting ISL1, which is the downstream of DNMT1. In contrast, OCT4 interacted with ERα, decreased DNMT1 expression and inactivated the Ras/Raf1/ERK signalling pathway in MCF-7 cells. Moreover, ERα inhibitor (AZD9496) reversed the suppression of OCT4-induced proliferation in MCF-7 cells via the activation of ERK signalling pathway.
CONCLUSIONS: OCT4 is dependent on ERα to suppress the proliferation of breast cancer cells through DNMT1/ISL1/ERK axis.

Hu C, Li M, Guo T, et al.
Anti-metastasis activity of curcumin against breast cancer via the inhibition of stem cell-like properties and EMT.
Phytomedicine. 2019; 58:152740 [PubMed] Related Publications
BACKGROUND: Curcumin is a polyphenolic compound with potent chemopreventive and anti-cancer efficacy.
PURPOSE: To explore the potential anti-metastasis efficacy of curcumin in breast cancer stem-like cells (BCSCs), which are increasingly considered to be the origin of the recurrence and metastasis of breast cancer.
METHODS: A CCK8 assay was performed to evaluate cell viability, and a colony formation assay was conducted to determine cell proliferation in MCF-7 and MDA-MB-231 adherent cells. Transwell and wound healing assays were used to detect the effect of curcumin on cell migration and invasion in MDA-MB-231 cells. Mammospheres were cultured with serum free medium (SFM) for three generations and the BCSC surface marker CD44
RESULTS: Curcumin exhibited anti-proliferative and colony formation inhibiting activities in both the MCF-7 and MDA-MB-231 cell lines. It also suppressed the migration and invasion of MDA-MB-231 cells. The CD44
CONCLUSION: The results of the present study suggest that the inhibitor effects of curcumin on breast cancer cells may be related to resistance to cancer stem-like characters and the EMT process. These data indicate that curcumin could function as a type of anti-metastasis agent for breast cancer.

Wang Y, Zhong Y, Hou T, et al.
PM2.5 induces EMT and promotes CSC properties by activating Notch pathway in vivo and vitro.
Ecotoxicol Environ Saf. 2019; 178:159-167 [PubMed] Related Publications
Fine particulate matter (PM2.5) has been closely linked to increased morbidity and mortality of lung cancer worldwide. However, the role of PM2.5 in the etiology of lung cancer and the mechanism involved in PM2.5 induced lung cancer are largely unknown. In this study, we performed chronic exposure animal model to investigate the carcinogenetic mechanisms of PM2.5 by targeting the induction of epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) properties through Notch1 signal pathway. The antagonism of Notch1 signal pathway was carried out in vitro cell lines of A549 and BEAS-2B to block EMT and CSC. We found that chronic PM2.5 exposure mice lung tissue pathology showed atypical hyperplasia of bronchiolar epithelium. Then, we discovered that chronic PM2.5 exposure induced notable EMT event and obvious CSC properties indicating the developing process of cell malignant behaviors. EMT characterized with decreased protein expression of E-cadherin and increased protein expression of Vimentin. CSC properties induced by chronic PM2.5 exposure characterized with increased cell-surface markers (ABCG2 and ALDH1A1) and self-renewal genes (SOX2 and OCT4). Furthermore, PM2.5 exposure activate Notch signal pathway by increasing expression of Notch1 and Hes1. At last, we blocked Notch signal pathway by inhibitor RO4929097 in vitro to explore the underlying mechanism mediating PM2.5 induced EMT and CSC. We found that blocking Notch1 could prevent PM2.5 induced malignant behaviors including EMT and CSC in A549 and BEAS-2B. These data revealed that the induction of EMT and CSC properties were involved in the lung cancer risk of PM2.5 in vivo, and blocking-up Notch1 may negatively regulate EMT and CSC to suppress the invasion and migration in vitro, thereby putatively serving as a novel therapeutic target for PM2.5 induced lung cancer.

Ji M, Liu L, Hou Y, Li B
1α,25‑Dihydroxyvitamin D3 restrains stem cell‑like properties of ovarian cancer cells by enhancing vitamin D receptor and suppressing CD44.
Oncol Rep. 2019; 41(6):3393-3403 [PubMed] Related Publications
Scientific evidence linking vitamin D with various cancer types is growing, but the effects of vitamin D on ovarian cancer stem cell‑like cells (CSCs) are largely unknown. The present study aimed to examine whether vitamin D was able to restrain the stemness of ovarian cancer. A side population (SP) from malignant ovarian surface epithelial cells was identified as CSCs, in vitro and in vivo. Furthermore, 1α,25‑dihydroxyvitamin D3 [1α,25(OH)2D3] treatment inhibited the self‑renewal capacity of SP cells by decreasing the sphere formation rate and by suppressing the mRNA expression levels of cluster of differentiation CD44, NANOG, OCT4, SOX2, Krüppel‑like factor 4 and adenosine triphosphate binding cassette subfamily G member 2. Additionally, 1α,25(OH)2D3 treatment decreased the expression of Cyclin D1, whereas it increased the expression of β‑catenin and vitamin D receptor (VDR). Notably, immunofluorescence staining verified that 1α,25(OH)2D3 promoted the expression of β‑catenin in the cytoplasm. Furthermore, vitamin D3 delayed the onset of tumor formation derived from injection of ovarian CSCs to nude mice, by reducing CD44 and enhancing β‑catenin expressions in vivo. In conclusion, 1α,25(OH)2D3 restrains the stem cell‑like properties of ovarian cancer cells by enhancing the expression of VDR, by promoting the expression of β‑catenin in the cytoplasm, and by suppressing the expression of CD44. These findings provide a novel insight into the functions of vitamin D in diminishing the stemness of cancer CSCs.

Sherman-Samis M, Onallah H, Holth A, et al.
SOX2 and SOX9 are markers of clinically aggressive disease in metastatic high-grade serous carcinoma.
Gynecol Oncol. 2019; 153(3):651-660 [PubMed] Related Publications
OBJECTIVE: The aim of this study was to analyze the expression, biological role and clinical relevance of cancer stem cell markers in high-grade serous carcinoma (HGSC).
METHODS: mRNA expression by qRT-PCR of NANOG, OCT4, SOX2, SOX4, SOX9, LIN28A and LIN28B was analyzed in 134 HGSC specimens (84 effusions, 50 surgical specimens). Nanog, OCT3/4, SOX2 and SOX9 protein expression by immunohistochemistry was analyzed in 52 HGSC effusions. Nanog protein expression in exosomes from 80 HGSC effusions was studied by Western Blotting. OVCAR3 cells underwent CRISPR/Cas9 Nanog knockout (KO), and the effect of Nanog KO on migration, invasion, proliferation and proteolytic activity was analyzed in OVCAR3 and OVCAR8 cells.
RESULTS: OCT4 mRNA was overexpressed in effusions compared to solid specimens (p = 0.046), whereas SOX9 was overexpressed in the ovarian tumors compared to effusions and solid metastases (p = 0.003). Higher SOX2 and SOX9 expression was associated with primary (intrinsic) chemoresistance (p = 0.009 and p = 0.02, respectively). Higher SOX9 levels were associated with shorter overall survival in univariate (p = 0.04) and multivariate (p = 0.049) analysis. OCT3/4, SOX2 and SOX9 proteins were found in HGSC cells, whereas Nanog was detected only in exosomes. Higher SOX2 protein expression was associated with shorter overall survival in univariate analysis (p = 0.049). OVCAR cells exposed to OVCAR3 NANOG KO exosomes had reduced migration, invasion and MMP9 activity.
CONCLUSIONS: SOX2 and SOX9 mRNA levels in HGSC effusions may be markers of clinically aggressive disease. Nanog is secreted in HGSC exosomes in effusions and modulates tumor-promoting cellular processes in vitro.

Koh SY, Moon JY, Unno T, Cho SK
Baicalein Suppresses Stem Cell-Like Characteristics in Radio- and Chemoresistant MDA-MB-231 Human Breast Cancer Cells through Up-Regulation of IFIT2.
Nutrients. 2019; 11(3) [PubMed] Free Access to Full Article Related Publications
Resistance to both chemotherapy and radiation therapy is frequent in triple-negative breast cancer (TNBC) patients. We established treatment-resistant TNBC MDA-MB-231/IR cells by irradiating the parental MDA-MB-231 cells 25 times with 2 Gy irradiation and investigated the molecular mechanisms of acquired resistance. The resistant MDA-MB-231/IR cells were enhanced in migration, invasion, and stem cell-like characteristics. Pathway analysis by the Database for Annotation, Visualization and Integrated Discovery revealed that the NF-κB pathway, TNF signaling pathway, and Toll-like receptor pathway were enriched in MDA-MB-231/IR cells. Among 77 differentially expressed genes revealed by transcriptome analysis, 12 genes involved in drug and radiation resistance, including interferon-induced protein with tetratricopeptide repeats 2 (IFIT2), were identified. We found that baicalein effectively reversed the expression of IFIT2, which is reported to be associated with metastasis, recurrence, and poor prognosis in TNBC patients. Baicalein sensitized radio- and chemoresistant cells and induced apoptosis, while suppressing stem cell-like characteristics, such as mammosphere formation, side population, expression of Oct3/4 and ABCG2, and CD44

Albamonte MI, Albamonte MS, Bou-Khair RM, et al.
The ovarian germinal reserve and apoptosis-related proteins in the infant and adolescent human ovary.
J Ovarian Res. 2019; 12(1):22 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Normal pubertal ovary displays all stages of follicular development and a biased BAX/BCL2 protein ratio in favor of pro-apoptotic BAX protein comparable to the adult ovary. However, adolescents suffering malignant extra-gonadal disease show a limited follicle development after cytotoxic drug treatment and a reduced capacity of in vitro follicle growth. We evaluated the expression of pro- and anti-apoptotic members of the BCL2 gene family, the FAS/FAS-L proteins from the extrinsic apoptosis pathway, the germ-cell-specific marker VASA, the pluripotency marker OCT3/4, and markers of early and late apoptosis in the ovary of pubertal patients with malignant extra-gonadal disease, which received or not pre-surgery chemotherapy, entering a cryopreservation program.
RESULTS: Ovarian biopsies from 12 adolescent girls were screened for follicle count and expression of VASA, OCT3/4, BAX, BCL2, MCL1L and S, cleaved-BID, FAS/FAS-L and CASPASE 3 through immunohistochemistry, western blot and RT-PCR. All stages of folliculogenesis, from primordial to antral follicle, were present in all 12 patients analyzed. VASA and most of the screened apoptosis-related genes showed a pattern of immune-expression comparable to that previously reported. OCT3/4 showed a cytoplasmic localization in the great majority of the primordial follicles; however, in some cases the localization was nuclear. In addition, OCT3/4B showed a significant reduction compared to OCT3/4A. Unexpectedly, BCL2 was detected at all stages of folliculogenesis, associated to the Balbiani's body in the primordial follicles, regardless of whether patients had or had not received chemotherapy, ruling out the possibility that its expression is a protective response to chemotherapy.
CONCLUSIONS: These findings reveal new information on the morphological status of the follicular reserve and the expression of apoptosis-related genes in histologically normal adolescent ovary from patients undergoing extragonadal cancer. The unexpected expression of apoptosis-inhibiting BCL2 protein, both in patients that had or had not received chemotherapy, opens a new avenue for thorough investigations. Moreover, the nuclear localization of OCT3/4 protein in primordial follicle-enclosed oocytes suggests a possible increased activity of ovarian stem cells in response to chemotherapy and/or extragonadal cancer. This new information can be essential for a better managing of in vitro culture of follicles that can be removed by filtration from preserved ovarian tissue, especially in girls that entered a cryopreservation program.

Wazir U, Orakzai MMAW, Martin TA, et al.
Correlation of
Cancer Genomics Proteomics. 2019 Mar-Apr; 16(2):121-127 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Telomerase reverse transcriptase (TERT) has a well-known role in carcinogenesis due to its functions in inducing cell immortality and preventing senescence. In this study, the relationships between TERT and a panel of known stem cell markers was examined in order to direct future enquiries into the role of 'stem-ness' in human breast cancer.
MATERIALS AND METHODS: Breast cancer tissues (n=124) and adjacent normal tissues (n=30) underwent reverse transcription and quantitative polymerase chain reaction. Transcript levels were analyzed for the correlation with that of TERT.
RESULTS: A significant direct correlation was found in cancerous tissue between TERT and BMI1 proto-oncogene polycomb ring finger 4 (BMI1; n=88, p<0.001), nestin (NES; n=88, p<0.001), POU domain, class 5, transcription factor 1 (POU5F1; n=88, p<0.001), aldehyde dehydrogenase 1 family member A2 (ALDH1A2; n=87, p=0.0298), cyclin-dependent kinase inhibitor 1A (CDKN1A; n=88, p<0.001), integrin subunit beta 1 (ITGNB1; n=88, p<0.001), integrin subunit alpha 6 (ITGA6; n=88, p<0.001), cluster of differentiation antigen 24 (CD24; n=88, p=0.0114), MET proto-oncogene (MET; n=78, p<0.001) and noggin (NOG; n=88, p<0.001).
CONCLUSION: The evidence presented in this article of possible interactions between TERT and a discrete subset of known stem cell markers would significantly contribute to further enquiries regarding clonal dynamics in the context of human breast cancer.

Muraki Y, Hasegawa T, Takeda D, et al.
Induced Pluripotent Stem Cell-related Genes Correlate With Poor Prognoses of Oral Squamous Cell Carcinoma.
Anticancer Res. 2019; 39(3):1205-1216 [PubMed] Related Publications
BACKGROUND/AIM: We recently investigated the contribution of the iPS-related genes SOX2, OCT4, and Nanog to de-differentiation by assaying for their mRNA levels. Given that mRNA expression does not always correlate with the protein levels, the aim of this study was to retrospectively determine the expression of these four iPS-related factors in human OSCC specimens by immunohistochemistry and examine their association with patient prognosis.
MATERIALS AND METHODS: iPS cell-related gene expression in 89 OSCC patients by tissue microarray, and its correlation with clinicopathological factors, differentiation, metastasis, and poor prognoses were investigated.
RESULTS: No evidence of statistically significant relationships was found between the expression of iPS cell-related genes and clinicopathological parameters. However, our data indicated that KLF4 expression was associated with survival, and poor tumor differentiation. In addition, high expression of KLF4 was an independent poor prognostic factor (p=0.004) for OSCC patients.
CONCLUSION: In preoperative biopsies, higher KLF4 and poor differentiation may be clinically effective predictors for the prognosis of oral cancer.

Siebenthall KT, Miller CP, Vierstra JD, et al.
Integrated epigenomic profiling reveals endogenous retrovirus reactivation in renal cell carcinoma.
EBioMedicine. 2019; 41:427-442 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Transcriptional dysregulation drives cancer formation but the underlying mechanisms are still poorly understood. Renal cell carcinoma (RCC) is the most common malignant kidney tumor which canonically activates the hypoxia-inducible transcription factor (HIF) pathway. Despite intensive study, novel therapeutic strategies to target RCC have been difficult to develop. Since the RCC epigenome is relatively understudied, we sought to elucidate key mechanisms underpinning the tumor phenotype and its clinical behavior.
METHODS: We performed genome-wide chromatin accessibility (DNase-seq) and transcriptome profiling (RNA-seq) on paired tumor/normal samples from 3 patients undergoing nephrectomy for removal of RCC. We incorporated publicly available data on HIF binding (ChIP-seq) in a RCC cell line. We performed integrated analyses of these high-resolution, genome-scale datasets together with larger transcriptomic data available through The Cancer Genome Atlas (TCGA).
FINDINGS: Though HIF transcription factors play a cardinal role in RCC oncogenesis, we found that numerous transcription factors with a RCC-selective expression pattern also demonstrated evidence of HIF binding near their gene body. Examination of chromatin accessibility profiles revealed that some of these transcription factors influenced the tumor's regulatory landscape, notably the stem cell transcription factor POU5F1 (OCT4). Elevated POU5F1 transcript levels were correlated with advanced tumor stage and poorer overall survival in RCC patients. Unexpectedly, we discovered a HIF-pathway-responsive promoter embedded within a endogenous retroviral long terminal repeat (LTR) element at the transcriptional start site of the PSOR1C3 long non-coding RNA gene upstream of POU5F1. RNA transcripts are induced from this promoter and read through PSOR1C3 into POU5F1 producing a novel POU5F1 transcript isoform. Rather than being unique to the POU5F1 locus, we found that HIF binds to several other transcriptionally active LTR elements genome-wide correlating with broad gene expression changes in RCC.
INTERPRETATION: Integrated transcriptomic and epigenomic analysis of matched tumor and normal tissues from even a small number of primary patient samples revealed remarkably convergent shared regulatory landscapes. Several transcription factors appear to act downstream of HIF including the potent stem cell transcription factor POU5F1. Dysregulated expression of POU5F1 is part of a larger pattern of gene expression changes in RCC that may be induced by HIF-dependent reactivation of dormant promoters embedded within endogenous retroviral LTRs.

Gao L, Guo Q, Li X, et al.
MiR-873/PD-L1 axis regulates the stemness of breast cancer cells.
EBioMedicine. 2019; 41:395-407 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Breast cancer stem cells have self-renewal capability and are resistant to conventional chemotherapy. PD-L1 could promote the expression of stemness markers (OCT4 and Nanog) in breast cancer stem cells. However, the mechanisms by which PD-L1 regulates the stemness of breast cancer cells and PD-L1 is regulated in breast cancer cells are still unclear.
METHODS: Lentivirus infection was used to construct stable cell lines. The correlation between PD-L1 and stemness markers expression was evaluated in clinical samples. Additionally, luciferase reporter assay combined with RNA-Fluorescence in situ hybridization (RNA-FISH) and RNA-binding protein immunoprecipitation (RIP) assays were used to verify the direct binding of miR-873 on PD-L1. Furthermore, flow cytometry, mammosphere formation combined with nude mouse tumor xenograft model were carried out to examine the effects of miR-873/PD-L1 axis on the stemness of breast cancer cells. Finally, MTT assay was performed to determine the effects of miR-873/PD-L1 axis on drug resistance.
FINDINGS: PD-L1 expression was positively correlated with the expression of stemness markers, and overexpression of PD-L1 contributed to chemoresistance and stemness-like properties in breast cancer cells via activating PI3K/Akt and ERK1/2 pathways. Mechanistically, miR-873 inhibited PD-L1 expression through directly binding to its 3'-untranslated region (UTR), and miR-873 attenuated the stemness and chemoresistance of breast cancer cells which was dependent on PD-L1 and the downstream PI3K/Akt and ERK1/2 signaling. Notably, the promotion of PD-L1 on the stemness and chemoresistance was enhanced by recombinant PD-1 (rPD-1), this effect was attenuated by PD-1/PD-L1 inhibitor.
INTERPRETATION: miR-873/PD-L1 regulatory axis might serve as a therapeutic target to enhance the chemo-sensitivity and eliminate the stemness of breast cancer cells. FUND: This work was supported by the National Nature Science Foundation of China, No. 81702957, China Postdoctoral Science Foundation, No. 2017M620230, the Postdoctoral Research Funding Scheme of Jiangsu Province (2017), No. 1701197B, and the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions.

Mamoori A, Wahab R, Vider J, et al.
The tumour suppressor effects and regulation of cancer stem cells by macrophage migration inhibitory factor targeted miR-451 in colon cancer.
Gene. 2019; 697:165-174 [PubMed] Related Publications
BACKGROUND: This study aimed to investigate the impact of miR-451 on the biological behaviours of colon cancer cells along with its targets interactions.
METHOD: The levels of miR-451 were tested in colon cancer cell lines (SW480 and SW48). Multiple functional and immunological assays were performed to analyse miR-451 induced growth changes in-vitro and downstream effects on target proteins.
RESULTS: Overexpression of miR-451 in colon cancer cells led to reduced cell proliferation, increased apoptosis and decrease accumulation of the cells at the G0/G1 phase of the cell cycle. In addition, a significant increase in the number of the cells was noted in the G2-M phase of cell cycle. Moreover, miR-451 reduced the expression of Oct-4, Sox-2 and Snail indicating its role in stem cell and epithelial-mesenchymal transition (EMT) regulation. An inverse correlation between miR-451 and macrophage migration inhibitory protein (MIF) protein expression occurred in colon cancer cells. Furthermore, restoration the level of miR-451 in colon cancer cells inhibits tumour spheres formation.
CONCLUSION: miR-451 has tumour suppressor effects in vitro, which can inhibit the cancer-related signalling pathways in colon cancer.

Chen X, Yang F, Zhang T, et al.
MiR-9 promotes tumorigenesis and angiogenesis and is activated by MYC and OCT4 in human glioma.
J Exp Clin Cancer Res. 2019; 38(1):99 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Glioma, characterized by its undesirable prognosis and poor survival rate, is a serious threat to human health and lives. MicroRNA-9 (miR-9) is implicated in the regulation of multiple tumors, while the mechanisms underlying its aberrant expression and functional alterations in human glioma are still controversial.
METHODS: Expressions of miR-9 were measured in GEO database, patient specimens and glioma cell lines. Gain- and loss-of-function assays were applied to identify the effects of miR-9 on glioma cells and HUVECs in vitro and in vivo. Potential targets of miR-9 were predicted by bioinformatics and further verified via in vitro experiments. Transcriptional regulation of miR-9 by MYC and OCT4 was determined in glioma cells.
RESULTS: MiR-9 was frequently up-regulated in glioma specimens and cells, and could significantly enhance proliferation, migration and invasion of glioma cells. In addition, miR-9 could be secreted from glioma cells via exosomes and was then absorbed by vascular endothelial cells, leading to an increase in angiogenesis. COL18A1, THBS2, PTCH1 and PHD3 were verified as the direct targets of miR-9, which could elucidate the miR-9-induced malignant phenotypes in glioma cells. MYC and OCT4 were able to bind to the promoter region of miR-9 to trigger its transcription.
CONCLUSIONS: Our results highlight that miR-9 is pivotal for glioma pathogenesis and can be treated as a potential therapeutic target for glioma.

Yu J, Zhang J, Zhou L, et al.
The Octamer-Binding Transcription Factor 4 (OCT4) Pseudogene, POU Domain Class 5 Transcription Factor 1B (POU5F1B), is Upregulated in Cervical Cancer and Down-Regulation Inhibits Cell Proliferation and Migration and Induces Apoptosis in Cervical Cancer Cell Lines.
Med Sci Monit. 2019; 25:1204-1213 [PubMed] Free Access to Full Article Related Publications
BACKGROUND The POU domain class 5 transcription factor 1B (POU5F1B), is a pseudogene that is homologous to octamer-binding transcription factor 4 (OCT4), and is located adjacent to the MYC gene on human chromosome 8q24. POU5F1B has been reported to be transcribed in several types of cancer, but its role in cervical cancer remains unclear. This study aimed to investigate the expression and function of POU5F1B in tissue samples of human cervical cancer and in cervical cancer cell lines in vitro. MATERIAL AND METHODS Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to quantify POU5F1B expression in cervical cancer tissues and in SiHa, HeLa, CaSki, and C33A human cervical cancer cell lines. Functional in vitro studies included analysis of the effects of POU5F1B expression on cervical cancer cell proliferation, migration, and apoptosis using a Cell Counting Kit-8 (CCK-8) assay, cell migration assays, and flow cytometry. Luciferase activity assays, qRT-PCR, and Western blot were performed to confirm the expression of POU5F1B. RESULTS POU5F1B was significantly upregulated in cervical cancer tissues and cell lines. Interference with the expression of POU5F1B significantly inhibited cell proliferation, apoptosis, migration and invasion, and induced apoptosis in vitro. Western blot demonstrated that POU5F1B could modulate the expression of the OCT4 protein. CONCLUSIONS POU5F1B was upregulated in cervical cancer and down-regulation inhibited cell proliferation and migration and induced apoptosis in cervical cancer cell lines by modulating OCT4. Further studies are required to determine whether POU5F1B might be a diagnostic or prognostic biomarker or therapeutic target in cervical cancer.

Wang Y, Liang Z, Li H, et al.
NSPc1 polycomb protein complex binds and cross‑talks to lncRNAs in glioma H4 cells.
Oncol Rep. 2019; 41(4):2575-2584 [PubMed] Related Publications
Recently, emerging evidence shows that a number of long non‑coding RNAs (lncRNAs) recruit polycomb group (PcG) proteins to specific chromatin loci to silence relevant gene expression. In the present study, we provided evidence that lncRNA candidates, selected by bioinformatic analysis and nervous system polycomb 1 (NSPc1), a key polycomb repressive complex 1 (PRC1) member, were highly expressed in glioma H4 cells in contrast to that noted in non‑cancerous cells. RNA binding protein immunoprecipitation (RIP) assays demonstrated that metastasis associated lung adenocarcinoma transcript 1 (MALAT1), SOX2 overlapping transcript (SOX2OT) and maternally expressed 3 (MEG3) among the 8 candidates bound to the NSPc1 protein complex in glioma H4 cells. Furthermore, overexpression of NSPc1 caused a decrease in the expression of MALAT1 and MEG3 and increased expression of SOX2OT, while NSPc1 downregulation caused the levels of all three genes to increase. Meanwhile, suppression of the expression of MALAT1 increased the expression levels of mRNA and protein of NSPc1, whereas downregulation of the expression of SOX2OT decreased NSPc1 expression. Moreover, a significant decrease in cell growth and increased cell apoptosis were observed in the transfected H4 cells by MTT assay and flow cytometric analysis. The results showed that the reduced co‑expression between NSPc1 and MALAT1/SOX2OT decreased the proliferation and promoted the death of H4 cells more obviously than the respectively decrease in expression of NSPc1, MALAT1 and SOX2OT. Remarkably, the influence of a simultaneously decreased expression of NSPc1 and SOX2OT on promoting cell apoptosis was more obvious than the total effect of the separate downregulation of NSPc1 and SOX2OT on accelerating cell death. However, that impact was partially counteracted in the silencing of the co‑expression of MALAT1 and NSPc1. Furthermore, they cooperated to affect transcription of p21 and OCT4.Briefly, these data suggest NSPc1 polycomb protein complex binding and cross‑talk to lncRNAs in glioma H4 cells, offering new insight into the important function of polycomb protein complex and lncRNA interactions in glioma cells and provide a novel view of potential biomarkers and targets for the diagnosis and therapy of glioma.

Jo JH, Park SB, Park S, et al.
Novel Gastric Cancer Stem Cell-Related Marker LINGO2 Is Associated with Cancer Cell Phenotype and Patient Outcome.
Int J Mol Sci. 2019; 20(3) [PubMed] Free Access to Full Article Related Publications
The expression of leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein 2 (LINGO2) has been reported in Parkinson's disease; however, its role in other diseases is unknown. Gastric cancer is the second leading cause of cancer death. Cancer stem cells (CSC) are a subpopulation of cancer cells that contribute to the initiation and invasion of cancer. We identified LINGO2 as a CSC-associated protein in gastric cancers both in vitro and in patient-derived tissues. We studied the effect of LINGO2 on cell motility, stemness, tumorigenicity, and angiogenic capacity using cells sorted based on LINGO2 expression and LINGO2-silenced cells. Tissue microarray analysis showed that LINGO2 expression was significantly elevated in advanced gastric cancers. The overall survival of patients expressing high LINGO2 was significantly shorter than that of patients with low LINGO2. Cells expressing high LINGO2 showed elevated cell motility, angiogenic capacity, and tumorigenicity, while LINGO2 silencing reversed these properties. Silencing LINGO2 reduced kinase B (AKT)/extracellular signal-regulated kinase (ERK)/ERK kinase (MEK) phosphorylation and decreased epithelial-mesenchymal transition (EMT)-associated markers-N-Cadherin and Vimentin and stemness-associated markers- POU class 5 homeobox 1 (OCT4) and Indian hedgehog (IHH), and markedly decreased the CD44⁺ population. These indicate the involvement of LINGO2 in gastric cancer initiation and progression by altering cell motility, stemness, and tumorigenicity, suggesting LINGO2 as a putative target for gastric cancer treatment.

Musah-Eroje A, Watson S
A novel 3D in vitro model of glioblastoma reveals resistance to temozolomide which was potentiated by hypoxia.
J Neurooncol. 2019; 142(2):231-240 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Glioblastoma (GBM) is the most common invasive malignant brain tumour in adults. It is traditionally investigated in vitro by culturing cells as a monolayer (2D culture) or as neurospheres (clusters enriched in cancer stem cells) but neither system accurately reflects the complexity of the three-dimensional (3D) chemoresistant microenvironment of GBM.
MATERIALS AND METHODS: Using three GBM cell-lines (U87, U251, and SNB19), the effect of culturing cells in a Cultrex-based basement membrane extract (BME) [3D Tumour Growth Assay (TGA)] on morphology, gene expression, metabolism, and temozolomide chemoresistance was investigated.
RESULTS: Cells were easily harvested from the 3D model and cultured as a monolayer (2D) and neurospheres. Indeed, the SNB19 cells formed neurospheres only after they were first cultured in the 3D model. The expression of CD133 and OCT4 was upregulated in the neurosphere and 3D assays respectively. Compared with cells cultured in the 2D model, cells were more resistant to temozolomide in the 3D model and this resistance was potentiated by hypoxia.
CONCLUSION: Taken together, these results suggest that micro-environmental factors influence GBM sensitivity to temozolomide. Knowledge of the mechanisms involved in temozolomide resistance in this 3D model might lead to the identification of new strategies that enable the more effective use of the current standard of care agents.

Zhai Y, Wei R, Sha S, et al.
Effect of NELL1 on lung cancer stem‑like cell differentiation.
Oncol Rep. 2019; 41(3):1817-1826 [PubMed] Related Publications
The cancer stem cell theory recently has received enormous attention in cancer biology. Lung cancer stem‑like cells are a subpopulation of undifferentiated lung tumor cells critical for lung cancer tumorigenesis, metastasis and resistance to therapy and disease relapse. The neural EGFL like 1 (NELL1) is a potent growth factor believed to preferentially target cells committed to the osteochondral lineage; yet, its expression and function in lung cancer are largely unknown. In the present study, we used specific medium to accumulate lung cancer stem‑like cells of 95‑D cells in spheres and obtained these highly expressed CD133 cells through flow cytometric cell sorting of CD133‑stained cells which were termed 95‑D lung cancer stem‑like cells (95‑D LCSCs). These 95‑D LCSCs highly expressed stemness genes CD133, Oct4 and Sox2 determined by western blot analysis and quantitative real‑time polymerase chain reaction (qPCR) analysis. Notably, we found that overexpression of NELL1 significantly reduced colony formation and invasion of 95‑D LCSCs tested by soft agar colony formation and cell invasion assay. In addition, as determined by cell proliferation assay, overexpression of NELL1 increased the chemotherapeutic sensitivity of 95‑D LCSCs to carboplatin and cisplatin. NELL1 also reduced the expression of phospho‑MET (p‑MET), Notch3 and HES1, which suggests that NELL1 may induce 95‑D LCSC differentiation by inhibiting the expression of c‑MET‑Notch signaling. Our results suggest that NELL1 induces lung cancer stem‑like cell differentiation, which provides a new potential therapeutic target for cancer stem cells.

Jiang M, Qiu N, Xia H, et al.
Long non‑coding RNA FOXD2‑AS1/miR‑150‑5p/PFN2 axis regulates breast cancer malignancy and tumorigenesis.
Int J Oncol. 2019; 54(3):1043-1052 [PubMed] Related Publications
Breast cancer (BC) is a common cancer and leading cause of cancer‑associated mortality in women. Abnormal expression of long non‑coding RNA FOXD2 adjacent opposite strand RNA 1 (FOXD2‑AS1) was associated with the development of a number of tumors. However, whether FOXD2‑AS1 is dysregulated in BC and its underlying mechanisms remain unclear. In the present study, it was identified that FOXD2‑AS1 expression was upregulated in BC tissue, cell lines and sphere subpopulation. Additionally, the abnormal upregulation of FOXD2‑AS1 predicted poor prognosis in patients with BC. Furthermore, downregulation of FOXD2‑AS1 decreased cell proliferation, and migratory and invasive abilities in BC cells, and decreased the growth of transplanted tumors in vivo. Downregulation of FOXD2‑AS1 decreased the percentage of CD44 antigen+/signal transducer CD24- in breast cancer stem cell (BCSC) cells, and decreased the expression of numerous stem factors, including Nanog, octamer‑binding transcription factor 4 (Oct4), and sex determining region Y‑box 2 (SOX2), and inhibited the epithelial‑mesenchymal transition process. FOXD2‑AS1 was identified to be primarily located in the cytoplasm. Using bioinformatics analysis, a reporter gene assay and reverse transcription‑polymerase chain reaction assays, it was demonstrated that microRNA (miR)‑150‑5p was able to bind directly with the 3'‑untranslated region of FOXD2‑AS1 and PFN2 mRNA. miR‑150‑5p mimics decreased the cell proliferation, migration and invasion of BC cells. FOXD2‑AS1 knockdown significantly inhibited the miR‑150‑5p inhibitor‑induced increase in Nanog, Oct4 and SOX2 expression. The miR‑150‑5p inhibitor‑induced increase in N‑cadherin, and decrease in E‑cadherin and vimentin was inhibited by FOXD2‑AS1 knockdown. Profilin 2 (PFN2) expression was significantly upregulated in BC tissues. Additionally, the abnormal upregulation of PFN2 was associated with poor prognosis in patients with BC. FOXD2‑AS1 and PFN2 expression was positively correlated. Collectively, the present results demonstrated the role of the FOXD2‑AS1/miR‑150‑5p/PFN2 axis in the development of BC, and provides novel targets for the treatment of BC, and potential biomarkers for diagnosis and prognosis of BC.

Choi SH, Kim JK, Jeon HY, et al.
OCT4B Isoform Promotes Anchorage-Independent Growth of Glioblastoma Cells.
Mol Cells. 2019; 42(2):135-142 [PubMed] Free Access to Full Article Related Publications
OCT4, also known as POU5F1 (POU domain class 5 transcription factor 1), is a transcription factor that acts as a master regulator of pluripotency in embryonic stem cells and is one of the reprogramming factors required for generating induced pluripotent stem cells. The human OCT4 encodes three isoforms, OCT4A, OCT4B, and OCT4B1, which are generated by alternative splicing. Currently, the functions and expression patterns of OCT4B remain largely unknown in malignancies, especially in human glioblastomas. Here, we demonstrated the function of OCT4B in human glioblastomas. Among the isoform of OCT4B, OCT4B-190 (OCT4B

Kuo SZ, Honda CO, Li WT, et al.
Metformin Results in Diametrically Opposed Effects by Targeting Non-Stem Cancer Cells but Protecting Cancer Stem Cells in Head and Neck Squamous Cell Carcinoma.
Int J Mol Sci. 2019; 20(1) [PubMed] Free Access to Full Article Related Publications
Cancer stem cells (CSCs) have been shown as a distinct population of cancer cells strongly implicated with resistance to conventional chemotherapy. Metformin, the most widely prescribed drug for diabetes, was reported to target cancer stem cells in various cancers. In this study, we sought to determine the effects of metformin on head and neck squamous cell carcinoma (HNSCC). CSCs and non-stem HNSCC cells were treated with metformin and cisplatin alone, and in combination, and cell proliferation levels were measured through MTS assays. Next, potential targets of metformin were explored through computational small molecule binding analysis. In contrast to the reported effects of metformin on CSCs in other cancers, our data suggests that metformin protects HNSCC CSCs against cisplatin in vitro. Treatment with metformin resulted in a dose-dependent induction of the stem cell genes CD44, BMI-1, OCT-4, and NANOG. On the other hand, we observed that metformin successfully decreased the proliferation of non-stem HNSCC cells. Computational drug⁻protein interaction analysis revealed mitochondrial complex III to be a likely target of metformin. Based on our results, we present the novel hypothesis that metformin targets complex III to reduce reactive oxygen species (ROS) levels, leading to the differential effects observed on non-stem cancer cells and CSCs.

Lazarevic M, Milosevic M, Trisic D, et al.
Putative cancer stem cells are present in surgical margins of oral squamous cell carcinoma.
J BUON. 2018 Nov-Dec; 23(6):1686-1692 [PubMed] Related Publications
PURPOSE: Recent evidence suggests that small subpopulations of stem-like cells are accountable for tumour initiation, progression and metastasis. Until now, studies were focused exclusively on the characterization of these cell populations within the tumour itself, while tumour margins were neglected, although it is known that the histological and molecular status of tumour margins may play a significant role in the course of the disease. Therefore, the aims of the study were to isolate cells from oral squamous cell carcinomas and their respective margins, to characterize these cells using specific markers, to assess their self-renewal potential and determine their chemoresistance.
METHODS: Cell cultures were obtained from 12 tissue specimens (6 tumours and 6 margins). Total RNA was extracted and gene expression analysis was done by real-time PCR (RT-PCR). Flow cytometry, immunocytometry, sphere formation and MTT assays were also applied.
RESULTS: With minor differences, cells originating from both tumours and tumour margins showed the presence of stem cell markers CD133, Nanog, Sox2, CD44, and Oct4, had the capacity to form spheroids and showed chemoresistance.
CONCLUSIONS: Subpopulations of margin cells appeared to have stemness properties which might raise the question of re-evaluation of optimal surgical management.

Monferrer E, Burgos-Panadero R, Blanquer-Maceiras M, et al.
High Oct4 expression: implications in the pathogenesis of neuroblastic tumours.
BMC Cancer. 2019; 19(1):1 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Neuroblastic tumours (NBTs) are paediatric solid tumours derived from embryonic neural crest cells which harbour their own cancer stem cells (CSC). There is evidence indicating that CSC may be responsible for tumour progression, chemotherapy resistance and recurrence in NBTs. Oct4 is a transcription factor which plays a key role in mammal embryonic development and stem cell fate regulation. The aim of the study is to elucidate the clinical significance of Oct4 in NBTs.
METHODS: We studied Oct4 expression in 563 primary NBTs using digital image quantification. Chi-square test was applied to analyse the correlation between histopathology and the Oct4
RESULTS: We found that tumours with a high proportion of cells expressing Oct4 correlated statistically with undifferentiated and poorly differentiated neuroblastoma / nodular ganglioneuroblastoma, and that Oct4 expression was not present in ganglioneuroma (p < 0.05). Statistical analysis also indicated a relationship between high Oct4 expression levels, high-risk patients according to the International Neuroblastoma Risk Group pre-treatment classification parameters, larger blood vessels and low survival rates.
CONCLUSIONS: These results suggest that the Oct4 gene may regulate NBT pathogenic differentiation pathways, and should thus be considered as a target for knockdown when developing novel therapies for high-risk NBT patients.

Lu H, Ju DD, Yang GD, et al.
Targeting cancer stem cell signature gene SMOC-2 Overcomes chemoresistance and inhibits cell proliferation of endometrial carcinoma.
EBioMedicine. 2019; 40:276-289 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Endometrial cancer is one of the most common gynecological malignancies and has exhibited an increasing incidence rate in recent years. Cancer stem cells (CSCs), which are responsible for tumor growth and chemoresistance, have been confirmed in endometrial cancer. However, it is still challenging to identify endometrial cancer stem cells to then target for therapy.
METHODS: Flow cytometry was used to identify the endometrial cancer stem cells. Sphere formation assay, western blotting, qRT-PCR assay, cell viability assay, xenograft assay and immunohistochemistry staining analysis were utilized to evaluate the effect of SPARC-related modular calcium binding 2 (SMOC-2) on the cells proliferation and drug resistance. Cell viability assay, qRT-PCR assay, immunofluorescence staining, Co-IP assay and luciferase reporter gene assay were performed to explore the possible molecular mechanism by which SMOC-2 activates WNT/β-catenin pathway.
FINDINGS: We found the expression of SPARC-related modular calcium binding 2 (SMOC-2), a member of SPARC family, was higher in endometrial CSCs than that in non-CSCs. SMOC-2 was also more highly expressed in spheres than in monolayer cultures. The silencing of SMOC-2 suppressed cell sphere ability; reduced the expression of the stemness-associated genes SOX2, OCT4 and NANOG; and enhanced chemosensitivity in endometrial cancer cells. By co-culture IP assay, we demonstrated that SMOC-2 directly interacted with WNT receptors (Fzd6 and LRP6), enhanced ligand-receptor interaction with canonical WNT ligands (Wnt3a and Wnt10b), and finally, activated the WNT/β-catenin pathway in endometrial cancer. SMOC-2 expression was closely correlated with CSC markers CD133 and CD44 expression in endometrial cancer tissue.
INTERPRETATION: Taken together, we conclude that SMOC-2 might be a novel endometrial cancer stem cell signature gene and therapeutic target for endometrial cancer. FUND: National Natural Science Foundation of China, Scientific and Technological Innovation Act Program of Shanghai Science and Technology Commission, Scientific and Technological Innovation Act Program of Fengxian Science and Technology Commission, Natural Science Foundation of Shanghai.

He L, Meng Y, Zhang Z, et al.
Downregulation of basic fibroblast growth factor increases cisplatin sensitivity in A549 non-small cell lung cancer cells.
J Cancer Res Ther. 2018; 14(7):1519-1524 [PubMed] Related Publications
Objectives: The objective of the study is to investigate the role of basic fibroblast growth factor (bFGF) in sensitivity to cisplatin in non-small cell lung cancer (NSCLC) A549 cells and its effect on the stemness characteristics of NSCLC cells, revealing possible mechanisms of cisplatin resistance.
Materials and Methods: After A549 cells were treated with cisplatin, bFGF protein expression was analyzed by Western blot. A549 cells were transfected with bFGF small interfering RNAs (siRNAs), and the knockdown efficiency was confirmed by quantitative reverse transcription polymerase chain reaction and Western blot. After bFGF downregulation, A549 cell proliferation was assessed by Cell Counting Kit-8 assay. The effect of bFGF siRNA on the sensitivity to cisplatin was evaluated by cell viability assays and flow cytometry for cell apoptosis. Colony formation assay was performed to explore whether bFGF affected the stemness characteristics of A549 cells, and OCT-4 protein expression was analyzed by Western blot after bFGF siRNA treatment.
Results: Cisplatin treatment enhanced bFGF expression in A549 cells. After A549 cells were transfected with bFGF siRNAs, bFGF expression was significantly decreased compared to that in the negative control siRNA group. In addition, bFGF knockdown inhibited A549 cell proliferation. bFGF siRNA treatment enhanced the inhibitory effect of different concentrations of cisplatin on cell viability and promoted cisplatin-induced apoptosis in A549 cells. Further analyses showed that bFGF siRNA treatment not only significantly decreased colony formation in A549 cells but also downregulated OCT-4 protein expression.
Conclusion: bFGF decreased NSCLC sensitivity to cisplatin in vitro, while it enhanced colony formation ability and increased OCT-4 expression of A549 cells, which might account for its involved mechanisms of cisplatin resistance.

Yadav P, Shankar BS
Radio resistance in breast cancer cells is mediated through TGF-β signalling, hybrid epithelial-mesenchymal phenotype and cancer stem cells.
Biomed Pharmacother. 2019; 111:119-130 [PubMed] Related Publications
AIMS: A major obstacle for effective cancer treatment by radiation therapy is the development of radio-resistance and identification of underlying mechanisms and activated pathways will lead to better combination therapies.
MAIN METHODS: Irradiated MCF-7 and MDA-MB-231 breast cancer cell lines were characterised following different recovery periods. Proliferation was assessed by MTT, BrdU and clonogenic assays and apoptosis by Annexin V/ propidium iodide staining and flow cytometry. Gene expression was monitored by real time PCR/ELISA/antibody labelling and migration using transwell inserts.
KEY FINDINGS: Breast cancer cell lines exposed to 6 Gy followed by recovery period for 7 days (D7-6 G) had increased ability for proliferation as well as apoptosis. D7-6 G from both cell lines had increased expression of transforming growth factor isoforms (TGF)-β1, β2 and β3, their receptors TGF-βR1 and TGF-βR2 which are known for such dual effects. The expression of downstream transcription factors Snail, Zeb-1 and HMGA2 also showed a differential pattern in D7-6 G cells with upregulation of at least two of these transcription factors. D7-6 G cells from both cell lines displayed hybrid epithelial-mesenchymal (E/M) phenotype with increased expression of E/M markers and migration. D7-6 G cells had increased expression of cancer stem cells markers Oct4, Sox2, and Nanog; aldehyde dehydrogenase expression and activity; proportion of CD44
SIGNIFICANCE: Blocking of TGF-β signalling may therefore be an effective strategy for overcoming radio resistance induced by radiation exposure.

Ogasawara S, Chuman Y, Michiba T, et al.
Inhibition of protein phosphatase PPM1D enhances retinoic acid-induced differentiation in human embryonic carcinoma cell line.
J Biochem. 2019; 165(6):471-477 [PubMed] Related Publications
The protein phosphatase PPM1D (Wip1) was originally identified as a p53 target product. Activation of PPM1D through various mechanism promotes the tumorigenic potential of various cancers by suppressing p53 and other DNA damage response proteins. New functions of PPM1D have recently been revealed in physiological processes such as cell differentiation. However, the regulatory mechanisms of signalling pathway to maintain stemness and induce cell differentiation are still unclear. Here we report that PPM1D modulates retinoic acid (RA) signalling. PPM1D knockdown resulted in decreased alkaline phosphatase activity of the human teratocarcinoma cell line NT2/D1. Inhibition of PPM1D-induced cell differentiation and decreased gene expression of the stem cell marker Oct-4 (POU5F1). RA-induced cell differentiation was promoted by reducing PPM1D activity. RA treatment elicited activation of the MEK-ERK pathway and induced rapid and transient activation of the extracellular signal-regulated kinase 1/2 (ERK-1/2). PPM1D dephosphorylated a phosphopeptide with the TEY motif in ERK-1/2 in vitro. Moreover, phosphorylation of ERK-1/2 was facilitated by PPM1D inhibition. Our study shows that PPM1D plays an important role in maintaining the undifferentiation state and a new function in RA-induced ERK regulation and cell differentiation.

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