Long non-coding RNA (lncRNA) potentially regulates tumorigenesis. LncRNA small nucleolar RNA host gene 1 (SNHG1) expression remains high in hepatocellular carcinoma cells; however, its biological mechanism in hepatocellular carcinoma remains unknown. In this study, SNHG1 expression in hepatocellular carcinoma cells was detected by qRT-PCR. Proliferative and migratory potentials of hepatocellular carcinoma cells were determined by CCK-8 and Transwell assay, respectively. Then, the nude mice model of xenograft was employed to verify the effect of SNHG1 on tumor formation in vivo. We identified the potential target of SNHG1 through bioinformatics and dual-luciferase reporter gene. Furthermore, Western blot and RIP assay was used for clarifying their interaction and functions in regulating the development of hepatocellular carcinoma. Our results indicated a high expression of SNHG1 in hepatocellular carcinoma cells. Downregulation of SNHG1 inhibited proliferative and migratory potentials of hepatocellular carcinoma cells in vitro and in vivo. Moreover, the expression of programmed cell death 4 (PDCD4) was positively regulated by SNHG1 through competing with miR-195-5p. These results indicated that SNHG1 participated in the development of hepatocellular carcinoma as a ceRNA to competitively bind to miR-195-5p and thus mediate PDCD4 expression.

MiR-21-5p has been identified as an oncogene to enhance human tumor progression. Here, we explored the mechanism by which miR-21-5p regulated the progression and paclitaxel (PTX) resistance in drug-resistant breast cancer (BC) cell lines. qRT-PCR assays were used to assess the expression levels of miR-21-5p and PDCD4 mRNA, and western blotting was used to detect PDCD4 protein level in PTX-resistant BC cell lines. Dual-luciferase reporter assay was used to observe the interaction between miR-21-5p and PDCD4 in PTX-resistant BC cell lines. Cell proliferation ability and IC50 values of PTX were measured by CCK-8 assay, cell cycle progression and apoptosis were determined with flow cytometry analysis, and cell migration and invasion capacities were analyzed using Transwell assay. Xenograft mice assay was used to validate the important role of miR-21-5p as a regulator on PTX-resistance BC cells growth in vivo. Then, we found that miR-21-5p was upregulated and PDCD4 was downregulated in BC tissues and PTX-resistant BC cell lines. MiR-21-5p silencing or PDCD4 overexpression ameliorated PTX resistance and inhibited the progression in PTX-resistant BC cell lines. Moreover, PDCD4 was demonstrated to be a direct target of miR-21-5p. MiR-21-5p exerted its regulatory effect by PDCD4 in PTX-resistant BC cell lines. Additionally, miR-21-5p silencing inhibited tumor growth in vivo. Therefore, our study demonstrated that miR-21-5p silencing ameliorated PTX resistance and inhibited the progression in PTX-resistant BC cell lines at least partly by targeting PDCD4, providing miR-21-5p as an effective therapeutic target for PTX-resistant BC treatment.

We evaluated microsatellite instability (MSI) in selected mismatch repair (MMR) and tumor suppressor (TS) genes with a view to exploring genetic changes associated with the occurrence of gastric cancer (GC). Moreover, expression of MSI positive genes was measured to get insights into molecular events operating in the tumor microenvironment. We anticipated discovering new molecular targets with potential as molecular biomarkers of gastric cancer. Of the 13 genes screened, we observed 15% to 52.5% MSI at eight microsatellite loci located in 3' UTR and coding regions of six genes (TGFBR2, PDCD4, MLH3, DLC1, MSH6, and MSH3). The union probability of different combinations of unstable microsatellite loci unveiled a set of four MSI markers from TGFBR2, PDCD4, MLH3, and MSH3 genes that allows detection of up to 85% incidences of GC. Significant downregulation of MLH3, PDCD4, TGFBR2, and DLC1 genes was observed in tumor tissues. Protein structure analyses of two unexplored targets, MSH3 (TG

Long noncoding RNA, long intergenic non-protein-coding RNA p53-induced transcript (LINC-PINT) was showed to be involved in cancer development. However, the biological effect of LINC-PINT on non-small cell lung cancer (NSCLC) remains unknown. Here, we aimed to investigate the role and underlying mechanism of LINC-PINT in NSCLC. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the level of LINC-PINT in NSCLC tissues and cell lines. Cell counting kit-8 (CCK-8), flow cytometry, migration and transwell invasion assays were used to investigate cell proliferation, cell cycle, cell migration and invasion, respectively. The targets of LINC-PINT were verified by both luciferase reporter assay and RNA immunoprecipitation assay. Tumour xenografts were used to reveal the effect of LINC-PINT on tumourigenesis in vivo. We observed that LINC-PINT expression increased in both NSCLC tissues and cell lines. Function assays exhibited that LINC-PINT reduced NSCLC cell proliferation, cell cycle, cell migration and invasion in vitro. We also indicated that LINC-PINT mediated inhibitory effect on cell proliferation, cell cycle, cell migration and invasion by miR-208a-3p/programmed cell death 4 (PDCD4) in NSCLC cells. These findings indicated that LINC-PINT functions as a tumour-suppressor that exerts important regulatory roles in NSCLC progression by sponging miR-208a-3p/PDCD4.

BACKGROUND: S-phase kinase-associated protein 2 (SKP2) is an oncogene and cell cycle regulator that specifically recognizes phosphorylated cell cycle regulator proteins and mediates their ubiquitination. Programmed cell death protein 4 (PDCD4) is a tumor suppressor gene that plays a role in cell apoptosis and DNA-damage response via interacting with eukaryotic initiation factor-4A (eIF4A) and P53. Previous research showed SKP2 may interact with PDCD4, however the relationship between SKP2 and PDCD4 is unclear.
METHODS: To validate the interaction between SKP2 and PDCD4, mass spectrometric analysis and reciprocal co-immunoprecipitation (Co-IP) experiments were performed. SKP2 stably overexpressed or knockdown breast cancer cell lines were established and western blot was used to detect proteins changes before and after radiation. In vitro and in vivo experiments were performed to verify whether SKP2 inhibits cell apoptosis and promotes DNA-damage response via PDCD4 suppression. SMIP004 was used to test the effect of radiotherapy combined with SKP2 inhibitor.
RESULTS: We found that SKP2 remarkably promoted PDCD4 phosphorylation, ubiquitination and degradation. SKP2 promoted cell proliferation, inhibited cell apoptosis and enhanced the response to DNA-damage via PDCD4 suppression in breast cancer. SKP2 and PDCD4 showed negative correlation in human breast cancer tissues. Radiotherapy combine with SKP2 inhibitor SMIP004 showed significant inhibitory effects on breast cancer cells in vitro and in vivo.
CONCLUSIONS: We identify PDCD4 as an important ubiquitination substrate of SKP2. SKP2 promotes breast cancer tumorigenesis and radiation tolerance via PDCD4 degradation. Radiotherapy combine with SKP2-targeted adjuvant therapy may improve breast cancer patient survival in clinical medicine.

OBJECTIVE: To investigate the lung cancer-promoting mechanism of mesenchymal stem cell-secreted extracellular vesicles (MSC-EV).
METHODS: EV were isolated from culture media of human bone marrow-derived MSCs that were pre-challenged with or without hypoxia (referred to as H-EV and N-EV, respectively). After treatment with N-EV or H-EV, A549 and H23 cell proliferation, apoptosis, trans-well invasion and epithelial-to-mesenchymal transition (EMT) were examined. Polarization of human primary monocytes-derived macrophages with or without N-EV or H-EV induction were analyzed by flow cytometry and ELISA. PTEN, PDCD4 or RECK gene was overexpressed in A549 cells, while miR-21-5p was knocked down in MSCs, A549 or H23 lung cancer cells or primary monocytes by miR-21-5p inhibitor transfection. Protein level of PTEN, PDCD4, RECK, AKT or STAT3 as well as phosphorylation level of AKT or STAT3 protein were assayed by western blot. Tumorigenicity of A549 and H23 cells with or without MSC-EV co-injection was assayed on immunocompromised mice. The xenograft tumor were examined for cell proliferation, angiogenesis, apoptosis and intra-tumoral M1/M2 macrophage polarization.
RESULTS: Comparing to N-EV, H-EV treatment significantly increased A549 and H23 cell proliferation, survival, invasiveness and EMT as well as macrophage M2 polarization. MiR-21-5p knocked down significantly abrogated the cancer-promoting and macrophage M2 polarizing effects of H-EV treatment. H-EV treatment downregulated PTEN, PDCD4 and RECK gene expression largely through miR-21-5p. Overexpressing PTEN, PDCD4 and RECK in A549 cells significantly reduced the miR-21-5p-mediated anti-apoptotic and pro-metastatic effect of H-EV, while overexpressing PTEN in monocytes significantly reduced macrophage M2 polarization after induction with the presence of H-EV. H-EV co-injection significantly increased tumor growth, cancer cell proliferation, intra-tumoral angiogenesis and M2 polarization of macrophages in vivo partially through miR-21-5p.
CONCLUSIONS: Increased miR-21-5p delivery by MSC-EV after hypoxia pre-challenge can promote lung cancer development by reducing apoptosis and promoting macrophage M2 polarization.

The human genome encodes thousands of long noncoding RNA (lncRNA) genes; the function of majority of them is poorly understood. Aberrant expression of a significant number of lncRNAs is observed in various diseases, including cancer. To gain insights into the role of lncRNAs in breast cancer progression, we performed genome-wide transcriptome analyses in an isogenic, triple negative breast cancer (TNBC/basal-like) progression cell lines using a 3D cell culture model. We identified significantly altered expression of 1853 lncRNAs, including ~500 natural antisense transcript (NATs) lncRNAs. A significant number of breast cancer-deregulated NATs displayed co-regulated expression with oncogenic and tumor suppressor protein-coding genes in cis. Further studies on one such NAT, PDCD4-AS1 lncRNA reveal that it positively regulates the expression and activity of the tumor suppressor PDCD4 in mammary epithelial cells. Both PDCD4-AS1 and PDCD4 show reduced expression in TNBC cell lines and in patients, and depletion of PDCD4-AS1 compromised the cellular levels and activity of PDCD4. Further, tumorigenic properties of PDCD4-AS1-depleted TNBC cells were rescued by exogenous expression of PDCD4, implying that PDCD4-AS1 acts upstream of PDCD4. Mechanistically, PDCD4-AS1 stabilizes PDCD4 RNA by forming RNA duplex and controls the interaction between PDCD4 RNA and RNA decay promoting factors such as HuR. Our studies demonstrate crucial roles played by NAT lncRNAs in regulating post-transcriptional gene expression of key oncogenic or tumor suppressor genes, thereby contributing to TNBC progression.

OBJECTIVE: Arsenic is a metalloid environmental carcinogen involved in the occurrence and development of many cancers. miRNA-21 plays a crucial role in arsenic-induced carcinogenesis. We aimed to elucidate the mechanism by which miRNA-21 influences arsenic-induced cancer.
METHODS: We used meta-analysis of published studies to determine how arsenic induces cancerous cells through miRNA-21.
RESULTS: Low-dose arsenic exposure (⪕ 5 μmol/L) can increase miRNA-21 and phosphorylated signal transducter and activator of transcription 3 (pSTAT3) expression, and decrease programmed cell death protein 4 (PDCD4) and protein sprouty homolog 1 (Spry1) expression. High-dose arsenic exposure (> 5 μmol/L), can increase miRNA-21 expression, and decrease Spry1 and E-cadherin expression. Short-term arsenic exposure (⪕ 24 h) can increase miRNA-21 and pSTAT3 expression, and decrease PDCD4 expression. Moreover, long-term arsenic exposure (> 24 h) can increase the miRNA-21, STAT3, and pSTAT3 expression, and decrease PDCD4 expression. We found that activation of miRNA-21 and pSTAT3 were most pronounced following long-term arsenic exposure at low doses, and the effects on PDCD4 expression were most pronounced following short-term arsenic exposure at low doses. miRNA-21 inhibitors increased the expression of tumor suppressor genes PDCD4, PTEN, and Spry1 and miRNA-21-mimics suppressed the expression of these tumor suppressor genes.
CONCLUSION: Arsenic can cause cancer by activating miRNA-21 and inhibiting the expression of PDCD4, PTEN, and Spry1.

MicroRNAs (miRNAs) are expressed aberrantly in various types of cancer, and negatively regulate the expression of target genes which may be useful in therapeutic strategies in several biological processes. In the present study, the expression levels and the effects of miRNA (miR)‑421 in breast cancer tissues and MCF‑7 and MDA‑MB‑231 cells were evaluated to elucidate therapeutic targets in breast cancer cells. The putative targets of miR‑421 were predicted by bioinformatics approaches, and the expression levels of miR‑421 were measured in MCF‑7 and MDA‑MB‑231 cells by reverse transcription‑quantitative polymerase chain reaction analysis following miR‑421 knockdown. The rates of cell proliferation, migration capacity, invasiveness and apoptosis were determined in miR‑421 inhibitor‑transfected MCF‑7 and MDA‑MB‑231 cells. The expression levels of target proteins regulated by miR‑421 in MCF‑7 and MDA‑MB‑231 cells were analyzed by western blot analysis. miR‑421 was increased significantly in breast cancer tissues and cells, and was regulated by miR‑421 antisense oligonucleotides. The knockdown of miR‑421 in MCF‑7 and MDA‑MB‑231 cells decreased cell proliferation, migration capacity and invasiveness, and promoted apoptosis compared with control groups. The expression of target protein programmed cell death 4 (PDCD4) were decreased in MCF‑7 and MDA‑MB‑231 cells transfected with miR‑421 inhibitors. These results suggested a correlation between miR‑421 and PDCD4, and physiological functions of breast cancer cells, suggesting that miR‑421 may be a potential strategy in the therapy of breast cancer.

In recent years, the incidence and mortality of colorectal cancer (CRC) have been on a global upward trend. There is an urgent need for effective tools to prevent and treat CRC and reduce morbidity and mortality of CRC patients. Recent evidence suggests that programmed cell death 4 (PDCD4), a novel tumor suppressor gene, inhibits tumor progression at transcriptional and translational levels and regulates multiple signal transduction pathways. However, little is known about the precise mechanisms regulating PDCD4 expression in CRC. In addition, several studies have demonstrated that the expression of in CRC is down-regulated or even absent. PDCD4 is therefore considered to be an independent prognostic factor in CRC and may be a potential support diagnostic tool for distinguishing in normal colon tissue, benign adenoma and CRC. This review will focus on the expression of PDCD4 in CRC and the relevant molecular mechanisms.

The existence of drug resistance is the main reason for chemotherapeutic failure in malignancies. Long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) is implicated with tumorigenesis and chemoresistance. In the present study, we aimed to identify the role of MEG3 in oxaliplatin-resistant colorectal cancer (CRC) and its potential mechanisms. MEG3 was down-regulated in oxaliplatin-resistant CRC tissues and cell lines. Low MEG3 expression was correlated with poor prognosis of CRC patients. Overexpression of MEG3 improved oxaliplatin sensitivity of HT29/OXA and HCT116/OXA cells. MEG3 suppressed miR-141 expression in HCT116/OXA cells. Moreover, MEG3 elevated PDCD4 expression through targeting miR-141, acting as a competing endogenous RNA (ceRNA). miR-141 inhibition or PDCD4 up-regulation could mimic the functional role in oxaliplatin resistance, which was counteracted by overexpression of MEG3. Collectively, MEG3 facilitated the sensitivity of CRC cells to oxaliplatin by regulating miR-141/PDCD4 axis, providing a novel therapeutic strategy for CRC.

Anoikis is a form of apoptosis induced upon cell detachment from extracellular matrix. It has been determined that acquisition of resistance to anoikis is a critical step for tumor cell metastasis. MiR-21, the most prominent oncomiR, plays an important role in tumor progression. In this study, we revealed that up-regulation of miR-21 in human esophageal adenocarcinoma (EA) is associated with lymph node metastasis and poor survival rate. Because of the established anti-apoptosis effect of miR-21, it is tempting to speculate that miR-21 might contribute to tumor metastasis by regulating anoikis. qRT-PCR analysis demonstrated that miR-21 expression in OE33/AR cells (subpopulation of human EA OE33 cells that acquired resistance to anoikis) was significantly increased. Also, transfection of miR-21 mimics provided OE33 cells resisting to anoikis. By luciferase assays, we verified that PDCD4 and PTEN were the functional targets of miR-21. In mouse model, via tail vein injection experiment, we showed that the metastasis formation of OE33 cells in vivo could be mediated by changing the miR-21 expression pattern. Taken together, our findings suggested that miR-21 was involved in the regulation of anoikis in human EA cells. Targeting miR-21 may provide a novel strategy to prevent metastasis.

Glioblastoma multiforme (GBM) is the most deadly brain tumor, and it is characterized by extremely poor therapeutic response and overall survival. Adjuvant radiotherapy remains the standard of care following surgical resection. Thus, elucidating the mechanisms conferring radioresistance in GBM is extremely urgent. In the present study, miR-96 was demonstrated to be significantly upregulated in radioresistant GBM cells. Knockdown of miR-96 in the radioresistant GBM cells T98G elevated the % of apoptotic cells and reduced their clonogenic formation ability following radiotherapy. By contrast, overexpression of miR-96 in the radiosensitive GBM cells U87-MG reduced the % of apoptotic cells and increased their clonogenic formation ability following radiotherapy. Results from phosphorylated-H2A histone family member X (γH2AX) foci staining and comet assays revealed that miR-96 enhanced the DNA repair processes. Furthermore, miR-96 overexpression conferred radioresistance by downregulating programmed cell death protein 4 (PDCD4). Luciferase assay results revealed that miR-96 bound to the 3'UTR of PDCD4 mRNA. Finally, U87-MG cells regained radiosensitivity following PDCD4 overexpression. Taken together, the present is the first study to establish that upregulation of miR-96 in GBM cells confers radioresistance via targeting PDCD4, which might be a potential therapeutic target for GBM.

BACKGROUND/AIMS: Several miRNAs have been reported to be involved in the pathogenesis of polycystic ovarian syndrome (PCOS). However, the biological roles of miR-16 and its molecular mechanisms in PCOS development remain to be elucidated.
METHODS: qRT-PCR was performed to detect the expression levels of miR-16 and programmed cell death protein 4 (PDCD4). GCs proliferation, cell cycle distribution and apoptosis were examined by MTT assay and flow cytometry analysis. Luciferase reporter assay and RIP assay were applied to confirm the regulatory relationship between miR-16 and PDCD4. Western blot was applied to measure the protein levels of PDCD4, PCNA and caspase-3. ELISA kits were used to determine the serum levels of steroids.
RESULTS: miR-16 expression was down-regulated in ovarian cortex tissues and serums of PCOS patients. PDCD4 expression was up-regulated in ovarian cortex tissues of PCOS patients. miR-16 overexpression facilitated cell proliferation, induced cell cycle progression, and inhibited apoptosis in GCs. Moreover, PDCD4 was a direct target of miR-16. Also, enforced expression of PDCD4 abated the effects of miR-16 on GCs growth and apoptosis. Additionally, testosterone resulted in a decrease of miR-16 expression and an increase of PDCD4 expression, thus blocking cell growth and enhanced apoptosis in GCs. Furthermore, miR-16 overexpression alleviated PCOS in vivo by regulating PDCD4.
CONCLUSIONS: miR-16 promoted ovarian GCs proliferation and inhibited apoptosis through directly targeting PDCD4 in PCOS, contributing to a better understanding of the molecular mechanism of GCs dysregulation and providing a promising target in PCOS.

Glioma is the most common malignant tumor of the brain, which is difficult to be completely resected. The recurrence and mortality rates are high and the prognosis is poor. The aim of this study was to investigate the expression of anti-oncogene programmed cell death 4 (PDCD4) and programmed cell death 5 (PDCD5) in glioma and their influence on the progression of the disease in order to provide new therapeutic approaches. Reverse transcription polymerase chain reaction (RT-PCR) analysis was used to investigate PDCD4 mRNA and PDCD5 mRNA expression in 66 glioma patients who served as the study group and 22 patients who suffered from craniocerebral injuries or hematencephalon who were used as controls. The experimental group was divided into a low malignant group (tumors grade I - II) and a high malignant group (tumor grades III-IV). The PDCD4 mRNA and PDCD5 mRNA expression in the experimental group was 0.545±0.202 and 0.687±0.174 and in the control group was 0.942±0.131 and 0.868 ± 0.190, respectively (P less than 0.05). The PDCD4 mRNA and PDCD5 mRNA expressions in the low malignant group were 0.628±0.240 and 0.750±0.198, respectively, and in the high malignant group were 0.464±0.185 and 0.553±0.170, respectively (P less than 0.05). The results showed a downregulation of PDCD4 mRNA and PDCD5 mRNA expression in the experimental group compared with the control group. This downregulation was correlated with the pathological grade of glioma. In the high malignant group the PDCD4 mRNA and PDCD5 mRNA expressions were significantly decreased compared with the low malignant group and the control group. PDCD4 mRNA and PDCD5 mRNA expressions are promising targets for the diagnosis and treatment of glioma.

Sipi soup (SPS), the aqueous extract derived from the root bark of Sophora japonical L, Salix babylonica L., Morus alba L., as well as Amygdalus davidiana (Carr.) C. de Vos, is a traditional Chinese medicine frequently used to prevent and treat infection and inflammation. However, the role of SPS in cancer‑associated fibroblasts (CAFs) require further investigation. In the present study, the effects of SPS on fibroblast inactivation and the underlying mechanism were investigated. Reverse transcription‑quantitative polymerase chain reaction was used to analyze the mRNA expression levels of fibroblast activation protein (FAP), interleukin (IL)‑6, α‑smooth muscle actin (α‑SMA) and programmed cell death 4 (PDCD4). Flow cytometry was used to evaluate cell apoptosis. Immunofluorescence was used to determine the number of activated fibroblasts. The present study reported that SPS treatment did not affect the proliferative apoptotic potential of fibroblasts. Treatment with HeLa cell culture medium (CM) induced a significant increase in the expression levels of FAP, IL‑6 and α‑SMA, but reduced the expression of PDCD4. SPS reversed the effects of HeLa CM on the expression of these genes. Analysis with a long non‑coding (lnc)RNA array of numerous differentially expressed lncRNAs revealed that the expression levels of the lncRNA homeodomain‑interacting protein kinase 1 antisense RNA (HIPK1‑AS) were increased in cervicitis tissues and cervical squamous cell carcinoma tissues compared with in normal cervical tissues. HIPK1‑AS expression levels were upregulated in response to HeLa CM, but were decreased under SPS treatment. The downregulation of HIPK1‑AS expression via short hairpin RNA abolished the effects of HeLa CM on the expression of inflammation‑associated genes. The findings of the present study suggested that SPS may prevent the progression of cervical cancer by inhibiting the activation of CAF and the inflammatory process by reducing HIPK1‑AS expression.

BACKGROUND: This study was designed to explore the anticancer potential of isoalantolactone, a sesquiterpene lactone, on esophageal squamous cell carcinoma (ESCC) cells and associated molecular mechanisms.
METHODS: ESCC cell lines were treated with isoalantolactone or vehicle and tested for viability, proliferation, cell cycle distribution, and apoptosis. Xenograft tumor studies in nude mice were done to examine the in vivo anticancer effect of isoalantolactone.
RESULTS: Isoalantolactone treatment reduced ESCC cell viability and proliferation in vitro, which was coupled with induction of G0/G1 cell cycle arrest and apoptosis. In vivo studies confirmed the growth-suppressive effect of isoalantolactone on ESCC cells. Mechanistically, isoalantolactone reversed microRNA-21-mediated repression of programmed cell death 4 (PDCD4). Overexpression of microRNA-21 and knockdown of PDCD4 blocked the growth suppression and apoptosis induction by isoalantolactone in ESCC cells.
CONCLUSIONS: Isoalantolactone shows growth-suppressive activity against ESCC cells, which is ascribed to upregulation of PDCD4 via downregulation of microRNA-21.

Osteoclastogenesis is the rate-limiting step in tumor osteolytic metastasis. MicroRNAs play crucial roles in tumor progression and osteoclastogenesis regulation. Recent studies have demonstrated that exosomes are able to function as messengers that deliver microRNAs between cells. However, the effects of lung adenocarcinoma cell-derived exosomal miRNAs in osteoclastogenesis remain poorly understood. In this study, we found that exosomes derived from A549 cells facilitate osteoclastogenesis. As miR-21 was involved in tumorigenesis and osteoclastogenesis, we further proved the existence of miR-21 in A549 cell-derived exosomes and investigated its function. MiR-21 overexpression in A549 cells led to increased levels of miR-21 in exosomes and facilitated osteoclastogenesis. Conversely, miR-21 depletion in A549 cells down-regulated miR-21 in exosomes and alleviated osteoclastogenesis. Mechanical experiments demonstrated that exosomal miR-21 exerted its promoting effects on osteoclastogenesis via targeting Pdcd4, which is a known target of miR-21 and a regulator of osteoclastogenesis. Finally, clinical data showed that higher miR-21 levels were associated with a worse overall survival in lung adenocarcinoma patients. In conclusion, we found that lung adenocarcinoma derived exosomal miR-21 may facilitate osteoclastogenesis, which suggests that it is a potential therapeutic target of bone metastasis.

Programmed cell death 4 (PDCD4) is decreased in many different kinds of malignant tumors. EMT endows tumor cells invasive and metastatic properties. However, few studies have determined the role of PDCD4 in the regulation of EMT in the context of laryngeal carcinoma. We examined the relationship between PDCD4 and EMT-associated proteins E-cadherin and N-cadherin using laryngeal carcinoma tissues. Gene manipulation was used to define the regulatory capacity of PDCD4. We report that PDCD4 and E-cadherin/N-cadherin expression were significantly changed in the carcinoma tissues, and their expression was associated with pathological grade, metastatic state, and clinical stage. The suppression of PDCD4 (and consequently, E-cadherin) was concomitant with increased proliferation and G2-phase arrest, decreased apoptosis, and increased cell invasion. PDCD4 upregulation reversed the above-mentioned results. In nude mice, PDCD4 knockdown increased tumor growth and pathological features, confirming the tumorigenic role of PDCD4. Finally, PDCD4 silencing was associated with dysregulation of the carcinogenic Wnt-β-catenin and the STAT3-miR-21 signaling pathways. This study revealed a dynamic regulatory relationship between PDCD4 and critical factors for EMT, establishing a broad, functional role for PDCD4 in laryngeal carcinoma, which may be propagated by the STAT3-miR-21 pathway. These findings provide new information on an EMT-associated target that may lead to a novel therapy.

Background: Chronic lung diseases such as chronic obstructive pulmonary disease (COPD) and epigenetic events underlie lung cancer (LC) development. The study objective was that lung tumor expression levels of specific microRNAs and their downstream biomarkers may be differentially regulated in patients with and without COPD.
Methods: In lung specimens (tumor and non-tumor), microRNAs known to be involved in lung tumorigenesis (miR-21, miR-200b, miR-126, miR-451, miR-210, miR-let7c, miR-30a-30p, miR-155 and miR-let7a, qRT-PCR), DNA methylation, and downstream biomarkers were determined (qRT-PCR and immunoblotting) in 40 patients with LC (prospective study, subdivided into LC-COPD and LC,
Results: Expression of miR-21, miR-200b, miR-210, and miR-let7c and DNA methylation were greater in lung tumor specimens of LC-COPD than of LC patients. Expression of downstream markers
Conclusions: Biomarkers of mechanisms involved in tumor growth, angiogenesis, migration, and apoptosis were differentially expressed in tumors of patients with underlying respiratory disease. These findings shed light into the underlying biology of the reported greater risk to develop LC seen in patients with chronic respiratory conditions. The presence of an underlying respiratory disease should be identified in all patients with LC as the differential biological profile may help determine tumor progression and the therapeutic response. Additionally, epigenetic events offer a niche for pharmacological therapeutic targets.

A glioblastoma is a common primary brain tumor that expresses microRNA-21 (miR-21), which inhibits the expression of pro-apoptotic genes such as phosphatase and tensin homologue (PTEN) and programmed cell death 4 (PDCD4). Therefore, an antisense-oligonucleotide against miR-21 (miR21ASO) could have therapeutic effects for glioblastomas. In this study, curcumin was loaded into deoxycholic acid-conjugated polyethylenimine (DP) micelles. The curcumin-loaded DP micelle (DP-Cur) was evaluated as a carrier for the combined delivery of curcumin and miR21ASO. Gel retardation and heparin competition assays showed that DP-Cur formed stable complexes with miR21ASO. The anti-tumor effects of the combined delivery of curcumin and miR21ASO were evaluated in C6 glioblastoma cells. In vitro transfection showed that DP-Cur had an miR21ASO delivery efficiency similar to that of polyethylenimine (25 kDa, PEI25k) and DP. In the C6 cells, the delivery of miR21ASO using DP-Cur effectively reduced the miR21 level. The miR21ASO/DP-Cur complex induced apoptosis more effectively than the single delivery of curcumin or miR21ASO. The therapeutic effect of the miR21ASO/DP-Cur complex was also evaluated in an intracranial glioblastoma animal model. The miR21ASO/DP-Cur complex reduced the tumor volume more effectively than single therapy of curcumin or miR21ASO. Immunohistochemistry showed that PDCD4 and PTEN were induced in the miR21ASO/DP and miR21ASO/DP-Cur complex groups. Therefore, DP-Cur is an efficient carrier of miR21ASO and the combined delivery of miR21ASO and curcumin may be useful in the development of combination therapy for glioblastoma.

Many studies have shown that randomized clinical trial with long-term follow-up found no improvement in stage II esophageal carcinoma (EC) patients receiving preoperative neoadjuvant chemoradiotherapy or chemotherapy treatment, this limitation underscored the urgent need for novel and reliable biomarkers for prognosis and prediction in stage II EC. miR-21 is frequently over-expressed while programmed cell death 4 (PDCD4) is often down-regulated in solid tumors. This study aimed to investigate the clinicopathological and prognostic significance of miR-21 and PDCD4 expression and to elucidate any correlation between miR-21 and PDCD4 expression in stage II EC patients. The expression level of miR-21 was up-regulated while the PDCD4 protein was down-regulated in stage II EC tissues compared with the adjacent non-cancerous tissues. Analyses of the clinicopathological parameters indicated that miR-21 expression was associated with differentiation grade, T stage, and N stage. PDCD4 protein expression was associated with T stage, N stage, and tumor size. The univariate linear regression analysis suggested a significant negative correlation between miR-21 and PDCD4 expression. The Kaplan-Meier curve showed that high miR-21 expression or low PDCD4 expression predicted poor progression-free survival (PFS) and overall survival (OS) of patients with stag II EC. In conclusion, both up-regulated miR-21 and down-regulated PDCD4 expression were associated with the aggressive progression and poor prognosis of stage II EC. miR-21 and PDCD4 might be potential biomarkers of tumor progression and indicators of prognosis of stag II EC.

Aberrant microRNA (miRNA/miR) expression has been reported in various cancer types. miR‑21, which is considered to be a proto-oncogene and is frequently overexpressed in certain cancer types, has been implicated in tumorigenesis. The aim of the present study was to investigate the effect of miR‑21 degradation on tumor progression and its potential mechanisms in human salivary adenoid cystic carcinoma (SACC) development. Results of reverse transcription‑quantitative polymerase chain reaction analysis indicated that SACC cells with high metastatic potential (SACC‑LM cells) exhibited a significantly higher expression of miR‑21 compared with SACC cells with a lower metastatic potential (SACC‑83 cells). In addition, following transfection of SACC‑LM cells with miR‑21 inhibitor, cell viability was reduced, which may be a result of reduced cell proliferation and metastasis, and the induction of apoptosis, as determined by Cell Counting Kit‑8, wound healing, Matrigel invasion and flow cytometry assays. Furthermore, bioinformatics analysis indicated that programmed cell death 4 (PDCD4), phosphatase and tensin homolog deleted on chromosome ten (PTEN) and B‑cell lymphoma (Bcl)‑2 are potential target genes of miR‑21. Therefore, western blotting was performed to investigate the expression of these proteins, and the results demonstrated that miR‑21 expression level was negatively associated with PDCD4 and PTEN protein expression, and positively associated with Bcl‑2 protein expression, in SACC‑LM cells, indicating that miR‑21 may promote SACC progression via PDCD4, PTEN and Bcl‑2. In conclusion, the present study indicates that miR‑21 may be a novel target for SACC therapy and provide a novel basis for the clinical treatment of SACC.

Hepatic miR-122 can serve as a pro-apoptotic factor to suppress tumorigenesis. The underlying mechanism, however, remains incompletely understood. Here we present the first evidence that miR-122 promotes hepatocellular carcinoma cell apoptosis through directly silencing the biogenesis of cell survival oncomiR miR-21 at posttranscriptional level. We find that miR-122 is strongly expressed in primary liver cell nucleus but its nuclear localization is markedly decreased in transformed cells particularly in chemoresistant tumor cells. MiRNA profiling and RT-qPCR confirm an inverse correlation between miR-122 and miR-21 in hepatocellular carcinoma tissues/cells, and increasing or decreasing nuclear level of miR-122 respectively reduces or increases miR-21 expression. Mechanistically, nuclear miR-122 suppresses miR-21 maturation via binding to a 19-nt UG-containing recognition element in the basal region of pri-miR-21 and preventing the Drosha-DGCR8 microprocessor's conversion of pri-miR-21 into pre-miR-21. Furthermore, both in vitro and in vivo studies demonstrate that nuclear miR-122 participates in the regulation of HCC cell apoptosis through modulating the miR-21-targeted programmed cell death 4 (PDCD4) signal pathway.

The role of microRNAs in brain cancer is still naive. Some act as oncogene and others as tumor suppressors. Discovery of efficient biomarkers is mandatory to debate that aggressive disease. Bioinformatically selected microRNAs and their targets were investigated to evaluate their putative signature as diagnostic and prognostic biomarkers in primary glioblastoma multiforme. Expression of a panel of seven microRNAs (hsa-miR-34a, hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, hsa-miR-326, and hsa-miR-375) and seven target genes ( E2F3, PI3KCA, TOM34, WNT5A, PDCD4, DFFA, and EGFR) in 43 glioblastoma multiforme specimens were profiled compared to non-cancer tissues via quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry staining for three proteins (VEGFA, BAX, and BCL2) was performed. Gene enrichment analysis identified the biological regulatory functions of the gene panel in glioma pathway. MGMT ( O-6-methylguanine-DNA methyltransferase) promoter methylation was analyzed for molecular subtyping of tumor specimens. Our data demonstrated a significant upregulation of five microRNAs (hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, and hsa-miR-375), three genes ( E2F3, PI3KCA, and Wnt5a), two proteins (VEGFA and BCL2), and downregulation of hsa-miR-34a and three other genes ( DFFA, PDCD4, and EGFR) in brain cancer tissues. Receiver operating characteristic analysis revealed that miR-34a (area under the curve = 0.927) and miR-17 (area under the curve = 0.900) had the highest diagnostic performance, followed by miR-221 (area under the curve = 0.845), miR-21 (area under the curve = 0.836), WNT5A (area under the curve = 0.809), PDCD4 (area under the curve = 0.809), and PI3KCA (area under the curve = 0.800). MGMT promoter methylation status was associated with high miR-221 levels. Moreover, patients with VEGFA overexpression and downregulation of TOM34 and BAX had poor overall survival. Nevertheless, miR-17, miR-221, and miR-326 downregulation were significantly associated with high recurrence rate. Multivariate analysis by hierarchical clustering classified patients into four distinct groups based on gene panel signature. In conclusion, the explored microRNA-target dysregulation could pave the road toward developing potential therapeutic strategies for glioblastoma multiforme. Future translational and functional studies are highly recommended to better understand the complex bio-molecular signature of this difficult-to-treat tumor.

Previous reports have suggested the significant association of miRNAs aberrant expression with tumor initiation, progression and metastasis in cancer, including gastrointestinal (GI) cancers. The current preliminary study aimed to evaluate the relative expression levels of miR-196a2 and three of its selected apoptosis-related targets; ANXA1, DFFA and PDCD4 in a sample of GI cancer patients. Quantitative real-time PCR for miR-196a2 and its selected mRNA targets, as well as immunohistochemical assay for annexin A1 protein expression were detected in 58 tissues with different GI cancer samples. In addition, correlation with the clinicopathological features and in silico network analysis of the selected molecular markers were analyzed. Stratified analyses by cancer site revealed elevated levels of miR-196a2 and low expression of the selected target genes. Annexin protein expression was positively correlated with its gene expression profile. In colorectal cancer, miR-196a over-expression was negatively correlated with annexin A1 protein expression (r = -0.738, p < 0.001), and both were indicators of unfavorable prognosis in terms of poor differentiation, larger tumor size, and advanced clinical stage. Taken together, aberrant expression of miR-196a2 and the selected apoptosis-related biomarkers might be involved in GI cancer development and progression and could have potential diagnostic and prognostic roles in these types of cancer; particularly colorectal cancer, provided the results experimentally validated and confirmed in larger multi-center studies.

lncRNA-X-inactive specific transcript (lncRNA XIST) has been demonstrated to be a tumor suppressor involved in the pathogenesis and development of various cancers. However, the function of XIST and its working mechanism in osteosarcoma (OS) remain enigmatic. Firstly, we determined the expression of XIST in OS tissues and cell lines by quantitative reverse transcription-PCR (qRT-PCR) and explored whether aberrant XIST expression was associated with recurrence and short overall survival. Furthermore, the effects of XIST on osteosarcoma cells were studied by lentivirus mediated overexpression approach in vitro and in vivo. Detection of a set of epithelial-mesenchymal transition (EMT) markers was performed to explore whether XIST is involved in EMT. Finally, we investigated the regulatory mechanism of XIST acting as a competitive endogenous RNA (ceRNA) of miR-21-5p in OS progression and metastasis. lncRNA XIST was significantly downregulated in osteosarcoma tissues and osteosarcoma cells, and associated with recurrence and short overall survival in OS patients. XIST overexpression remarkably inhibited the proliferation of OS cells as well as the xenograft tumor formation in vivo. Both cell invasion and migration were inhibited by XIST overexpression via suppressing the EMT process. These results indicated that XIST functioned as a tumor suppressor in OS. Moreover, we found that miR-21-5p interacted with XIST by directly targeting the miRNA-binding site in the XIST sequence, and qRT-PCR results showed XIST and miR-21-5p could affect each other's expression, respectively. The following assays verified that the tumor suppressor, PDCD4 was a functional target of miR-21-5p in OS cells. Finally, we affirmed that XIST regulated PDCD4 expression by competitively binding to miR-21-5p. XIST inhibited cell proliferation and cell mobility by competitively binding to miR-21-5p and upregulating PDCD4 in OS. Our study demonstrated that lncRNA-XIST, which acts as a miRNA sponge, impedes miR-21-5p to maintain the expression of PDCD4, which contributes to the progression of OS. Our findings suggest that the newly identified XIST/miR-21-5p/PDCD4 axis could be a potential biomarker or therapeutic target for OS.

MicroRNAs (miRNAs) are short non-coding RNAs of 21-23 nucleotides that play important roles in virtually all biological pathways in mammals and in other multicellular organisms. miR-23a and miR-23b (miR-23a/b) are critical oncomiRs (miRNAs that are associated with human cancers) of gastric cancer, but their detailed roles in the initiation and progression of gastric cancer remain to be elucidated. In this study, we found that miR-23a/b were consistently upregulated in gastric cancer tissues. We then investigated the molecular mechanisms through which miR-23a/b contribute to gastric cancer and identified programmed cell death 4 (PDCD4) as a direct target gene of miR-23a/b. In contrast to the upregulated expression levels of miR-23a/b, PDCD4 protein levels were dramatically downregulated and inversely correlated with miR-23a/b in gastric cancer tissues. Moreover, we observed that cell apoptosis was increased by miR-23a/b inhibitors and decreased by miR-23a/b mimics in gastric cancer cells and that the restoration of PDCD4 expression attenuated the anti-apoptotic effects of miR-23a/b in gastric cancer cells, indicating that PDCD4 is a direct mediator of miR-23a/b functions. Finally, we showed that miR-23a/b significantly suppressed PDCD4 expression and enhanced tumor growth in a gastric cancer xenograft mouse model. Taken together, this study highlights an important role for miR-23a/b as oncomiRs in gastric cancer through the inhibition of PDCD4 translation. These findings may shed new light on the molecular mechanism of gastric carcinogenesis and provide a new avenue for gastric cancer treatment.

Chronic lymphocytic leukemia (CLL) cells are highly dependent on microenvironment, being the BCR pathway one key player in this crosstalk. Among proteins participating, ZAP-70 enhances response to microenvironmental stimuli. MicroRNA-21 (miR-21) is overexpressed in diverse neoplasias including CLL, where it has been associated to refractoriness to fludarabine and to shorter time to progression and survival. To further elucidate the role of ZAP-70 in the biology of CLL, we studied its involvement in miR-21 regulation. MiR-21 expression was higher in CLL cells with high ZAP-70. Ectopic expression of ZAP-70 induced transcription of miR-21 via MAPK and STAT3, which subsequently induced downregulation of tumor suppressors targeted by miR-21. The co-culture of primary CLL cells mimicking the microenvironment induced ZAP-70 and miR-21 expression, as well as downregulation of miR-21 targets. Interestingly, the increase in miR-21 after co-culture was significantly impaired by ibrutinib, indicating that the BCR signaling pathway is involved in its regulation. Finally, survival of CLL cells induced by the co-culture correlated with miR-21 upregulation. In conclusion, stimuli from the microenvironment regulate miR-21 and its targeted tumor suppressor genes via a signaling pathway involving ZAP-70, thus contributing to the cytoprotection offered by the microenvironment particularly observed in CLL cells expressing ZAP-70.

Aberrant expression of microRNAs hae been shown to be closely associated with glioblastoma cell proliferation, apoptosis and drug resistance. However, mechanisms underlying the role of mcroRNAs in glioblastoma cell growth and apoptosis are not fully understood. In this study, we report that miR-503 is overexpressed in glioblastoma tissue compared with normal human brain tissue. Mechanistically, miR-503 can be induced by TGF-â1 at the transcriptional level by binding the smad2/3 binding elements in the promoter. Ectopic overexpression of miR-503 promotes cell growth and inhibits apoptosis by targeting PDCD4. In contrast, inhibition of miR-503 reduces cell growth. Furthermore, miR-503 inhibitor augments the growth inhibitory effect of temozolomide in glioblastoma cells. These results establish miR-503 as a promising molecular target for glioblastoma therapy.