Adhesion G protein-coupled receptors (ADGRs) encompass 33 human transmembrane proteins with long N termini involved in cell-cell and cell-matrix interactions. We show the ADGRB1 gene, which encodes Brain-specific angiogenesis inhibitor 1 (BAI1), is epigenetically silenced in medulloblastomas (MBs) through a methyl-CpG binding protein MBD2-dependent mechanism. Knockout of Adgrb1 in mice augments proliferation of cerebellar granule neuron precursors, and leads to accelerated tumor growth in the Ptch1

BACKGROUND & AIMS: Dietary exposure to aflatoxin is an important risk factor for hepatocellular carcinoma (HCC). However, little is known about the genomic features and mutations of aflatoxin-associated HCCs compared with HCCs not associated with aflatoxin exposure. We investigated the genetic features of aflatoxin-associated HCC that can be used to differentiate them from HCCs not associated with this carcinogen.
METHODS: We obtained HCC tumor tissues and matched non-tumor liver tissues from 49 patients, collected from 1990 through 2016, at the Qidong Liver Cancer Hospital Institute in China-a high-risk region for aflatoxin exposure (38.2% of food samples test positive for aflatoxin contamination). Somatic variants were identified using GATK Best Practices Pipeline. We validated part of the mutations from whole-genome sequencing and whole-exome sequencing by Sanger sequencing. We also analyzed genomes of 1072 HCCs, obtained from 5 datasets from China, the United States, France, and Japan. Mutations in 49 aflatoxin-associated HCCs and 1072 HCCs from other regions were analyzed using the Wellcome Trust Sanger Institute mutational signatures framework with non-negative matrix factorization. The mutation landscape and mutational signatures from the aflatoxin-associated HCC and HCC samples from general population were compared. We identified genetic features of aflatoxin-associated HCC, and used these to identify aflatoxin-associated HCCs in datasets from other regions. Tumor samples were analyzed by immunohistochemistry to determine microvessel density and levels of CD34 and CD274 (PD-L1).
RESULTS: Aflatoxin-associated HCCs frequently contained C>A transversions, the sequence motif GCN, and strand bias. In addition to previously reported mutations in TP53, we found frequent mutations in the adhesion G protein-coupled receptor B1 gene (ADGRB1), which were associated with increased capillary density of tumor tissue. Aflatoxin-associated HCC tissues contained high-level potential mutation-associated neoantigens, and many infiltrating lymphocytes and tumors cells that expressed PD-L1, compared to HCCs not associated with aflatoxin. Of the HCCs from China, 9.8% contained the aflatoxin-associated genetic features, whereas 0.4%-3.5% of HCCs from other regions contained these genetic features.
CONCLUSIONS: We identified specific genetic and mutation features of HCCs associated with aflatoxin exposure, including mutations in ADGRB1, compared to HCCs from general populations. We associated these mutations with increased vascularization and expression of PD-L1 in HCC tissues. These findings might be used to identify patients with HCC due to aflatoxin exposure, and select therapies.

The aim of the current study was to investigate the biological effect on T24 cells and human umbilical vein endothelial cells (HUVECs) of transfection with brain-specific angiogenesis inhibitor-1 (BAI-1). The recombinant plasmid pReceiver-M61-BAI-1 was transfected into human superficial bladder tumor cells (T24) and HUVECs, in parallel with the vector control. mRNA and protein expression levels of BAI‑1 were then detected by quantitative polymerase chain reaction (qPCR) and western blotting, respectively. Cell apoptosis of T24 cells and HUVECs prior and subsequent to transfection with BAI‑1 was analyzed by flow cytometric analysis. Proliferation of T24 cells and HUVECs prior and subsequent to transfection of BAI-1 was assessed by the MTT method. T24 cells and HUVECs transfected with pReceiver‑M61‑BA1‑1 were classed as the experimental group; T24 cells and HUVECs transfected with p‑Receiver‑M61 were the control group. qPCR and western blotting methods confirmed that there was positive expression of BAI‑1 in T24 cells and HUVECs transfected with pReceiver‑M61‑BAI‑1, however BAI‑1 was not expressed in T24 cells and HUVECs transfected with pReceiver‑M61. The results of the MTT assay demonstrated that absorbance was markedly reduced in HUVECs at 12, 48 and 72 h subsequent to transfection with pReceiver-M61-BAI-1 when compared with that of the control group and in T24 cells transfected with p‑Receiver-M61-BAI-1. Furthermore, flow cytometry results also indicated that the apoptotic rate of HUVECs transfected with p‑Receiver‑M61‑BAI‑1 was significantly increased compared with that of the control group and T24 cells transfected with p‑Receiver‑M61‑BAI‑1. BAI‑1 was observed to markedly inhibit the proliferation of vascular endothelial cells in vitro, however, no direct inhibition by BAI‑1 was observed in T24 cells. In conclusion, BAI-1 is suggested to be a potential novel therapautic target for the inhibition of tumor neovascularization.

The aim of the present study was to investigate the expression levels of brain‑specific angiogenesis inhibitor‑1 (BAI‑1) in bladder transitional cell carcinoma (BTCC) at different stages and the mechanism by which it inhibits tumor endothelial cell proliferation. Normal bladder mucosa biopsy specimens were obtained as the control group, and human BTCC biopsy specimens were used as the study group. Immunohistochemical assays were used to detect the expression levels of BAI‑1, vascular endothelial growth factor (VEGF) and mutant p53, in addition to microvessel density (MVD) in the tissues. Western blotting was used to analyze the differential expression of BAI‑1 in the two samples. Statistical analysis was performed, which indicated that BAI‑1 expression levels in the normal bladder mucosa group were significantly higher than those in the BTCC group and were associated with clinical staging. BAI‑1 levels in the T1 stage BTCC tissues were higher than those in the T2‑4 stage BTCC tissues (P<0.05). BAI‑1 expression levels were negatively correlated with those of VEGF (r=‑0.661, P<0.001), mutant p53 (r=‑0.406, P=0.002) and with the MVD (r=‑0.675, P<0.001). BAI‑1 may be involved in the negative regulation of BTCC microvascular proliferation, and its expression may be associated with a reduction in p53 mutations.

The 2-year survival rate of patients with breast cancer brain metastases is less than 2%. Treatment options for breast cancer brain metastases are limited, and there is an unmet need to identify novel therapies for this disease. Brain angiogenesis inhibitor 1 (BAI1) is a GPCR involved in tumor angiogenesis, invasion, phagocytosis, and synaptogenesis. For the first time, we identify that BAI1 expression is significantly reduced in breast cancer and higher expression is associated with better patient survival. Nestin is an intermediate filament whose expression is upregulated in several cancers. We found that higher Nestin expression significantly correlated with breast cancer lung and brain metastases, suggesting both BAI1 and Nestin can be therapeutic targets for this disease. Here, we demonstrate the ability of an oncolytic virus, 34.5ENVE, to target and kill high Nestin-expressing cells and deliver Vstat120 (extracellular fragment of BAI1). Finally, we created two orthotopic immune-competent murine models of breast cancer brain metastases and demonstrated 34.5ENVE extended the survival of immune-competent mice bearing intracranial breast cancer tumors.

Oncolytic viral (OV) therapy has been considered as a promising treatment modality for brain tumors. Vasculostatin, the fragment of brain-specific angiogenesis inhibitor-1, shows anti-angiogenic activity against malignant gliomas. Previously, a vasculostatin-expressing oncolytic herpes simplex virus-1, Rapid Antiangiogenesis Mediated By Oncolytic virus (RAMBO), was reported to have a potent antitumor effect. Here, we investigated the therapeutic efficacy of RAMBO and cilengitide, an integrin inhibitor, combination therapy for malignant glioma. In vitro, tube formation was significantly decreased in RAMBO and cilengitide combination treatment compared with RAMBO or cilengitide monotherapy. Moreover, combination treatment induced a synergistic suppressive effect on endothelial cell migration compared with the control virus. RAMBO, combined with cilengitide, induced synergistic cytotoxicity on glioma cells. In the caspase-8 and -9 assays, the relative absorption of U87ΔEGFR cell clusters treated with cilengitide and with RAMBO was significantly higher than that of those treated with control. In addition, the activity of caspase 3/7 was significantly increased with combination therapy. In vivo, there was a significant increase in the survival of mice treated with combination therapy compared with RAMBO or cilengitide monotherapy. These results indicate that cilengitide enhanced vasculostatin-expressing OV therapy for malignant glioma and provide a rationale for designing future clinical trials combining these two agents.

Brain-specific angiogenesis inhibitor 1 (BAI1), an orphan G protein-coupled receptor-type seven transmembrane protein, was recently found mutated or silenced in multiple human cancers and can interfere with tumor growth when overexpressed. Yet, little is known about its regulation and the molecular mechanisms through which this novel tumor suppressor exerts its anti-cancer effects. Here, we demonstrate that the N terminus of BAI1 is cleaved extracellularly to generate a truncated receptor and a 40-kDa fragment (Vasculostatin-40) that inhibits angiogenesis. We demonstrate that this novel proteolytic processing event depends on a two-step cascade of protease activation: proprotein convertases, primarily furin, activate latent matrix metalloproteinase-14, which then directly cleaves BAI1 to release the bioactive fragment. These findings significantly augment our knowledge of BAI1 by showing a novel post-translational mechanism regulating BAI1 activity through cancer-associated proteases, have important implications for BAI1 function and regulation, and present novel opportunities for therapy of cancer and other vascular diseases.

Brain angiogenesis inhibitor 1 (BAI1) is a putative G protein-coupled receptor with potent antiangiogenic and antitumorigenic properties that is mutated in certain cancers. BAI1 is expressed in normal human brain, but it is frequently silenced in glioblastoma multiforme. In this study, we show that this silencing event is regulated by overexpression of methyl-CpG-binding domain protein 2 (MBD2), a key mediator of epigenetic gene regulation, which binds to the hypermethylated BAI1 gene promoter. In glioma cells, treatment with the DNA demethylating agent 5-aza-2'-deoxycytidine (5-Aza-dC) was sufficient to reactivate BAI1 expression. Chromatin immunoprecipitation showed that MBD2 was enriched at the promoter of silenced BAI1 in glioma cells and that MBD2 binding was released by 5-Aza-dC treatment. RNA interference-mediated knockdown of MBD2 expression led to reactivation of BAI1 gene expression and restoration of BAI1 functional activity, as indicated by increased antiangiogenic activity in vitro and in vivo. Taken together, our results suggest that MBD2 overexpression during gliomagenesis may drive tumor growth by suppressing the antiangiogenic activity of a key tumor suppressor. These findings have therapeutic implications because inhibiting MBD2 could offer a strategy to reactivate BAI1 and suppress glioma pathobiology.

PURPOSE: Renal cell carcinoma is a typical hypervascular tumor in which neovascularization may have a large part in progression. We examined expression of the cancer regulating, p53 targeted angiogenesis inhibitor brain-specific angiogenesis inhibitor 1 in renal cell carcinoma tissue to elucidate the clinical significance of its expression.
MATERIALS AND METHODS: We examined brain-specific angiogenesis inhibitor 1 mRNA and protein expression in 47 renal cell carcinoma and 10 normal kidney tissues using real-time quantitative polymerase chain reaction and immunohistochemistry, respectively. Levels of VEGF and bFGF mRNA, and immunohistochemical expression of p53 protein were also investigated in the same renal cell carcinoma tissues.
RESULTS: A significant decrease in BAI1 mRNA was noted in renal cell carcinoma tissue compared with that in normal kidney tissue (p <0.001). Immunostaining for brain-specific angiogenesis inhibitor 1 was also decreased in carcinoma tissue compared with normal kidney tissue. BAI1 mRNA and protein expression were lower in advanced renal cell carcinoma (pT3-4) than in localized renal cell carcinoma (pT1-2) tissues (p <0.03 and 0.003, respectively). A significant negative correlation was observed between microvessel density and brain-specific angiogenesis inhibitor 1 protein expression (r = -0.4056, p = 0.002). No significant correlation was noted between BAI1 and VEGF or bFGF mRNA levels. Brain-specific angiogenesis inhibitor 1 protein expression did not correlate with p53 protein expression.
CONCLUSIONS: These observations suggest that down-regulation of brain-specific angiogenesis inhibitor 1 expression may be a critical factor in renal cell carcinoma development and BAI1 may be a promising candidate for gene therapy of renal cell carcinoma.

Brain angiogenesis inhibitor 1 (BAI1) is a transmembrane protein expressed on glial cells within the brain. Its expression is dramatically down-regulated in many glioblastomas, consistent with its functional ability to inhibit angiogenesis and tumor growth in vivo. We have shown that the soluble anti-angiogenic domain of BAI1 (termed Vstat120) requires CD36, a cell surface glycoprotein expressed on microvascular endothelial cells (MVECs), for it to elicit an anti-angiogenic response. We now report that Vstat120 binding to CD36 on MVECs activates a caspase-mediated pro-apoptotic pathway, and this effect is abrogated by histidine-rich glycoprotein (HRGP). HRGP is a circulating glycoprotein previously shown to function as a CD36 decoy to promote angiogenesis in the presence of thrombospondin-1 or -2. Data here show that Vstat120 specifically binds HRGP. Under favorable MVEC growth conditions this interaction allows chemotactic-directed migration as well as endothelial tube formation to persist in in vitro cellular systems, and increased tumor growth in vivo as demonstrated in both subcutaneous and orthotopic brain tumor models, concomitant with an increase in tumor vascularity. Finally, we show that HRGP expression is increased in human brain cancers, with the protein heavily localized to the basement membrane of the tumors. These data help define a novel angiogenic axis that could be exploited for the treatment of human cancers and other diseases where excess angiogenesis occurs.

This study was designed to elucidate the therapeutic effect of transfering the brain-specific angiogenesis inhibitor 1 (BAI1) gene to a mouse renal cell carcinoma cell line (Renca). Female BALB/c mice were inoculated subcutaneously with wild-type Renca (Renca/Wild) cells or Renca cells transfected with the BAI-1 (Renca/BAI-1) or LacZ (Renca/LacZ) gene. Tumor growth was observed every other day from 3 to 35 days after implantation. Moreover, the intratumoral injection of the adenovirus vector containing the gene encoding BAI1 was conducted at two-day intervals from 11 to 31 days after implantation of the Renca/Wild or Renca/BAI1 tumor. Tumor blood flow was measured by colorimetric angiogenesis assay (CAA). The concentration of the vascular endothelial growth factor (VEGF) in the cell culture supernatants was determined by enzyme-linked immunoassay. The size of the Renca/BAI1 tumor was significantly (p<0.01) suppressed compared to the Renca/Wild and Renca/LacZ tumors 21 days after tumor implantation. The injection of the BAI1 viral vector at 2-day intervals significantly inhibited the growth of both the Renca/Wild and Renca/BAI1 tumors. The blood volume measured by CAA and microvessel density was significantly lower in the Renca/BAI1 than in the Renca/Wild and Renca/LacZ tumors (p<0.01 and p<0.05, respectively). A significant (p<0.01) reduction in VEGF concentration in the supernatant was demonstrated in the Renca/BAI1 compared with the Renca/Wild and Renca/LacZ cell cultures. These observations suggest that the transfer of the BAI1 gene to Renca can suppress the tumor growth via the inhibition of angiogenesis. The down-regulation of VEGF production in tumor cells contributes to this anti-tumor effect.

Gastric cancers with and those without high-frequency microsatellite instability (MSI-H) represent distinctive pathways of carcinogenesis. The aim of this study was to clarify if expression of p53 related genes involved in angiogenesis is differentially regulated between these cancers. We systematically analyzed the expression of vascular endothelial growth factor A (VEGFA), fibroblast growth factor 2 (FGF2), thrombospondin 1 (THBS1), and brain-specific angiogenesis inhibitor 1 (BAI1), and we correlated the results with microvessel count (MVC), MSI status, p53 mutations, and prostaglandin-endoperoxide synthase 2 (PTGS2) expression in gastric cancers. Expression of VEGFA in carcinoma cells was immunohistochemically seen in 46% of 200 cases. VEGFA positivity was significantly associated with higher MVC, vascular invasion, lymph node and distant metastasis, and advanced tumor stage. FGF2 positivity was significantly associated with poor differentiation, depth of invasion, and higher MVC. VEGFA and FGF2 positivities and MVC were lower in MSI-H cancers than in MSI-L or MSS cancers. VEGFA expression was associated with both p53 mutations and PTGS2 expression. Methylation of the THBS1 gene was detected in 6 of 11 cancer cell lines and in 44% of 200 cases. THBS1 methylation was significantly associated with distal location, vascular invasion, distant metastasis, MSI-H, wild-type p53, and higher MVC. The prognosis was worst in patients with cancers that were VEGFA-positive and THBS1 methylation-positive. Gastric cancers with MSI-H were characterized by lower MVC, low frequency of VEGFA, FGF2, and PTGS2 overexpression, and high frequency of THBS1 methylation. Our results suggest that gastric cancers with and those without MSI-H represent distinctive pathways of carcinogenesis, including aberrant expression of factors regulating angiogenesis. The difference may be associated with less aggressive phenotype of these cancers with MSI-H and affect future molecular targeted therapeutics.

Glioblastomas are the most common primary brain tumors in adults. These tumors exhibit a high degree of vascularization, and malignant progression from astrocytoma to glioblastoma is often accompanied by increased angiogenesis and the upregulation of vascular endothelial growth factor and its receptors. In this study, we investigated the in vivo antiangiogenic and antitumor effects of brain-specific angiogenesis inhibitor 1 (BAI1) using human glioblastoma cell lines. Glioblastoma cells were transduced with an adenoviral vector encoding BAI1 (AdBAI1), and Northern and Western blot analyses, respectively, demonstrated BAI1 mRNA and protein expression in the transduced tumor cells. Using an in vivo neovascularization assay, we found that angiogenesis surrounding AdBAI1-transduced glioblastoma cells transplanted into transparent skinfold chambers of SCID mice was significantly impaired compared to control treated cells. Additionally, in vivo inoculation with AdBAI1 of established subcutaneous or intracerebral transplanted tumors significantly impaired tumor growth and promoted increased mouse survival. Morphologically, the tumors exhibited signs of impaired angiogenesis, such as extensive necrosis and reduced intratumoral vascular density. Taken together, these data strongly indicate that BAI1 may be an excellent gene therapy candidate for the treatment of brain tumors, especially human glioblastomas.

Brain specific angiogenesis inhibitor (BAI)-1 is a novel p53-inducible anti-angiogenic molecule. We examined the expression of BAI-1 in glial tumors and its association with patient survival. The expression of BAI-1 was evaluated in 20 brain tumors (meningiomas, pituitary adenomas, hemangiopericytomas, hemangioblastomas), 2 normal brain samples, 5 benign gliomas, and 26 glioblastomas. In the 26 glioblastoma tumors, we also evaluated the expression of VEGF, p53, p53 mutations, and MIB-1 to determine their association with survival. BAI-1 mRNA was expressed in all benign gliomas, normal brain, and 9 out of 26 glioblastomas, but not in the other tumors. Low VEGF and aberrant high expression of p53 were associated with a favorable outcome in univariate survival analysis, but they were not independent factors in multivariate analysis. For the treatment response, BAI-1 expression was associated with better response to radiation therapy (p=0.014). When we divided the patients into groups according to the expression patterns of BAI-1 and VEGF mRNA, the median survival of 9 patients with high VEGF expression and no expression of BAI-1 was just 6 months, while the median survival of the other 17 patients was 14 months (p=0.013). Glioblastomas with no BAI-1 and high VEGF mRNA expression are more often associated with poor clinical outcome. These findings suggest that the balance between the angiogenic and anti-angiogenic factors is important in the progression of glioblastoma and its response to treatment.

Brain angiogenesis inhibitors (BAI) are putative transmembrane proteins containing an extracellular domain with thrombospondin type-1 repeats which can exhibit anti-angiogenic activity. BAI1 mRNA is expressed mainly in the brain, while BAI2 and BAI3 mRNAs are more widely expressed. We hypothesized that the BAI family might have anti-tumoral properties and studied the expression of BAI1 protein in normal human brain and in glioblastoma multiforme. We generated an anti-BAI1 antibody and showed that BAI1 was widely expressed in normal brain but was absent in 28 glioma cell lines and in the majority of human glioblastoma investigated. BAI1 expression did not correlate with TP53 status and we did not confirm previous findings that p53 regulates BAI1 mRNA expression in glioma cells. The finding that expression of BAI proteins may be lost during tumor formation is of special interest as restoration of their function in tumors may be of therapeutic benefit.

The brain-specific angiogenesis inhibitor 1 gene has been isolated in an attempt to find fragments with p53 "functional" binding sites. As reported herein and by others, brain-specific angiogenesis inhibitor 1 expression is present in some normal tissues, but is reduced or lost in tumour tissues. Such data and its particular structure prompted the hypothesis that brain-specific angiogenesis inhibitor 1 may act as a mediator in the local angiogenesis balance. We herein demonstrate that brain-specific angiogenesis inhibitor 1 over-expression suppresses tumour angiogenesis, delaying significantly the human tumour growth in immunodeficient mice. The inhibitory effect of brain-specific angiogenesis inhibitor 1 was documented using our intravital microscopy system, strongly implicating brain-specific angiogenesis inhibitor 1 as a mediator in the control of tumour angiogenesis. In contrast, in vitro tumour cell proliferation was not inhibited by brain-specific angiogenesis inhibitor 1 transfection, whereas some level of cytotoxicity was assessed for endothelial cells. Immunohistochemical analysis of tumour samples confirmed a reduction in the microvessel density index in brain-specific angiogenesis inhibitor 1-overexpressing tumours. At messenger level, moderate changes could be detected, involving the down-regulation of vascular endothelial growth factor and collagenase-1 expression. Furthermore, brain-specific angiogenesis inhibitor 1 expression that was lost in a selection of human cancer cell lines could be restored by wild-type p53 adenoviral transfection. Brain-specific angiogenesis inhibitor 1 should be considered for gene therapy and development of efficient drugs based on endogenous antiangiogenic molecules.

The expression of interleukin 10 (IL-10) is correlated with clinical prognosis in non-small cell lung cancer [NSCLC (H. Hatanaka et al., ANN: ONCOL:, 11: 815--819, 2000)]. However, the effects of IL-10 expression on vascularization in NSCLC are not apparent. We examined the gene expression of IL-10/IL-10 receptor and various angiogenic/angioinhibitory factors in 95 NSCLC samples to determine the correlation between IL-10 production and vascularization. Vascular endothelial growth factor, angiopoietin [Ang (Ang-1 and Ang-2)], thrombospondin, brain-specific angiogenesis inhibitor 1, vascular endothelial growth factor receptors (KDR and flt-1), and Ang receptor (TIE2) gene expression were evaluated by reverse transcription-PCR. The cellular localization of these factors and vascularity in the cancer stroma were examined immunohistochemically. Seventy-eight (82.1%) and 93 (97.9%) of these 95 NSCLCs were positive for IL-10 and IL-10 receptor, respectively. Ang-1, Ang-2, and TIE2 gene expression was seen in 76 (97.4%), 73 (93.6%), and 78 (100%) of 78 IL-10-positive NSCLCs, respectively, and was significantly correlated with IL-10 gene expression (P < 0.0088, <0.0008, and 0.0305, respectively; Fisher's exact method). The localizations of Ang-1, Ang-2, and TIE2 were confirmed within tumor cells immunohistochemically. Vascular number and measurement area were significantly higher in the IL-10-positive NSCLCs (33.500 +/- 9.299/microm(2) and 4.742 +/- 1.287%) as compared with IL-10-negative NSCLCs (10.611 +/- 2.839/microm(2) and 0.718 +/- 0.331%; Mann-Whitney U test, P = 0.0039). The IL-10 expression did not show any significant correlation with the expression of other factors. These results suggested that tumor-produced IL-10 promotes stromal vascularization through expression of Ang-1, Ang-2, and TIE2.

Genes involving angiogenesis and metastasis play an important role in the progression and infiltration of cancer. We examined the expressions of various angiostatic and potential invasion/metastasis suppressor genes through RT-PCR analyses in 32 gastric cancer specimens with or without distant metastasis. The expressions of the invasion/metastasis suppressor, nm23 and E-cadherin increased much more in the cancer tissue (CT) and metastatic lymph node (MLN) than in the extraneoplastic mucosa (EM) and non-metastatic lymph node (NLN), respectively. The expressions of the angiostatic factor, angiopoietin 2 and thrombospondin 2 increased in the CT and MLN as compared with the EM and NLN, respectively. The newly cloned angiostatic factor, brain-specific angiogenesis inhibitor 1 (BAI1) decreased much more in the CT and MLN than the EM and NLN, respectively. However, BAI1 increased in the CT compared with the EM among the patients with poor prognosis and distant metastasis, such as liver or peritoneum. The expressions of the invasive factor, matrix metalloproteinase-2 and its suppressor, tissue inhibitor metalloproteinase-2 (TIMP-2) increased in the CM as compared with the EM, but the increased expression pattern of these genes in the CT became blunted among the patients with good prognosis. Our results indicate that BAI1 and TIMP-2 expressions in the extraneoplastic mucosa and non-metastatic lymph nodes were not suppressed in the patients with good prognosis, but increased expressions of angiopoietin 2, thrombospondin 2, TIMP-2, nm23 and E-cadherin in the tumor tissue did not lead to a long survival after operation. It is suggested that the extent of BAI1 and TIMP-2 expression in the gastric mucosa may be an important prognostic factor for predicting survival in gastric cancer.

Angiogenesis plays an important role in growth and proliferation of cancer. Various angiogenic and angiostatic factors regulate angiogenesis. We examined expression of genes encoding various angiostatic factors: thrombospondin 1 (TSP1), thrombospondin 2 (TSP2), brain-specific angiogenesis inhibitor 1 (BAI1) and angiopoietin 2 (AGP2) in 62 colorectal cancers and 40 samples of extraneoplastic colon mucosa. The expression of the angiostatic factors TSP2 and AGP2 were significantly increased in the cancerous mucosa as compared to these in extraneoplastic mucosa (o2 test; p<0. 0001, and Fisher's exact test; p<0.0001), while the increase in TSP1 expression was not significant. BAI1 expression was slightly decreased in the cancer tissue. These results suggested that specific types of angiostatic factors might have protective roles against cancer cell proliferation via dormancy due to hyponutrition caused by decreased vascularity.

Angiogenesis is required for the growth and progression of malignancies. Recent studies have demonstrated that genetic alterations may accompany acquisition of the angiogenic phenotype. The tumor suppressor gene p53 is most frequently mutated in human cancers and is also known to be a transcriptional regulator of a variety of genes. Here, we investigated the antiangiogenic effect of the wild-type p53 (wt-p53) gene transfer on a human non-small cell lung cancer cell line. Mutant p53-expressing H226Br non-small cell lung cancer cells were transduced with the wt-p53 gene using a recombinant adenoviral vector (Ad5CMVp53) and applied to semiquantitative reverse transcription-PCRs for the detection of altered mRNA expression of angiogenic and/or antiangiogenic factors. In vivo neovascularization assay of Ad5CMVp53-infected cells was then performed using a membrane-diffusion chamber system s.c. transplanted in nu/nu mice. We also evaluated the effect of Ad5CMVp53-infected H226Br cells on nontransduced tumor cells in vivo by s.c. inoculating mixture of cells into nu/nu mice. Ad5CMVp53 infection markedly inhibited the expression of an angiogenic factor, vascular endothelial growth factor, and increased the expression of a novel antiangiogenic factor, brain-specific angiogenesis inhibitor 1, resulting in reduced neovascularization in vivo. Mixing experiments showed that tumor cells transduced with the wt-p53 gene inhibited the in vivo tumor growth of adjacent nontransduced cells. Our data suggest that a recombinant adenovirus expressing the wt-p53 gene is antiangiogenic, which may explain, in part, the mechanism of the bystander effect induced by the wt-p53 gene transfer on adjacent tumor cells.

Brain-specific angiogenesis inhibitor (BAI) 1 was recently isolated as a novel p53 inducible gene. BAI1 has been suggested to play a significant role in angiostasis. We studied the expression of BAI1 in 49 colorectal cancer specimens by RT-PCR. BAI1 expression was significantly reduced in colorectal cancers as compared to the extraneoplastic tissues (X(2) test, p=0.041). BAI1 expression was inversely correlated with vascular invasion and metastasis (Fisher's exact test, p 0.045). Moreover, vascularity in the colorectal cancer was inversely correlated with BAI1 gene expression (Mann-Whitney U-test, p=0.0003). These observations suggested that BAI1 expression might inhibit angiogenesis and metastasis of colorectal cancer.