Pan-cancer analysis of CDKN2A alterations identifies a subset of gastric cancer with a cold tumor immune microenvironment.

BACKGROUND: Although CDKN2A alteration has been explored as a favorable factor for tumorigenesis in pan-cancers, the association between CDKN2A point mutation (MUT) and intragenic deletion (DEL) and response to immune checkpoint inhibitors (ICIs) is still disputed. This study aims to determine the associations of CDKN2A MUT and DEL with overall survival (OS) and response to immune checkpoint inhibitors treatment (ICIs) among pan-cancers and the clinical features of CDKN2A-altered gastric cancer. METHODS: This study included 45,000 tumor patients that underwent tumor sequencing across 33 cancer types from four cohorts, the MSK-MetTropism, MSK-IMPACT, OrigiMed2020 and TCGA cohorts. Clinical outcomes and genomic factors associated with response to ICIs, including tumor mutational burden, copy number alteration, neoantigen load, microsatellite instability, tumor immune microenvironment and immune-related gene signatures, were collected in pan-cancer. Clinicopathologic features and outcomes were assessed in gastric cancer. Patients were grouped based on the presence of CDKN2A wild type (WT), CDKN2A MUT, CDKN2A DEL and CDKN2A other alteration (ALT). RESULTS: Our research showed that CDKN2A-MUT patients had shorter survival times than CDKN2A-WT patients in the MSK MetTropism and TCGA cohorts, but longer OS in the MSK-IMPACT cohort with ICIs treatment, particularly in patients having metastatic disease. Similar results were observed among pan-cancer patients with CDKN2A DEL and other ALT. Notably, CDKN2A ALT frequency was positively related to tumor-specific objective response rates to ICIs in MSK MetTropism and OrigiMed 2020. Additionally, individuals with esophageal carcinoma or stomach adenocarcinoma who had CDKN2A MUT had poorer OS than patients from the MSK-IMPACT group, but not those with adenocarcinoma. We also found reduced levels of activated NK cells, T cells CD8 and M2 macrophages in tumor tissue from CDKN2A-MUT or DEL pan-cancer patients compared to CDKN2A-WT patients in TCGA cohort. Gastric cancer scRNA-seq data also showed that CDKN2A-ALT cancer contained less CD8 T cells but more exhausted T cells than CDKN2A-WT cancer. A crucial finding of the pathway analysis was the inhibition of three immune-related pathways in the CDKN2A ALT gastric cancer patients, including the interferon alpha response, inflammatory response, and interferon gamma response. CONCLUSIONS: This study illustrates the CDKN2A MUT and DEL were associated with a poor outcome across cancers. CDKN2A ALT, on the other hand, have the potential to be used as a biomarker for choosing patients for ICI treatment, notably in esophageal carcinoma and stomach adenocarcinoma.

Systematic analysis of the cuprotosis in tumor microenvironment and prognosis of gastric cancer.

Cuprotosis is a new programmed cell death related to cancer. However, the characteristics of cuprotosis in gastric cancer (GC) remain unknown. Ten cuprotosis molecules from 1544 GC patients were used to identify three GC molecular genotypes. Cluster A was characterized by the best clinical outcome and was significantly enriched in metabolic signaling pathways. Cluster B exhibited elevated immune activation, high immune stroma scores and was significantly enriched in tumor immune signaling pathways. Cluster C was characterized by severe immunosuppression and poor response to immunotherapy. Notably, the citrate cycle, cell cycle, and p53 signaling pathways were enriched in the differentially expressed genes among the three subtypes, which were critical signaling pathways for cell death. We also developed a cuprotosis signature risk score that could accurately predict the survival, immunity, and subtype of GC. This study presents a systematic analysis of cuprotosis molecules and provides new immunotherapeutic targets for GC patients.

An antigen processing and presentation signature for prognostic evaluation and immunotherapy selection in advanced gastric cancer.

Objective: The aim of the study was to propose a signature based on genes associated with antigen processing and presentation (APscore) to predict prognosis and response to immune checkpoint inhibitors (ICIs) in advanced gastric cancer (aGC). Background: How antigen presentation-related genes affected the immunotherapy response and whether they could predict the clinical outcomes of the immune checkpoint inhibitor (ICI) in aGC remain largely unknown. Methods: In this study, an aGC cohort (Kim cohort, RNAseq, N=45) treated by ICIs, and 467 aGC patients from seven cohorts were conducted to investigate the value of the APscore predicting the prognosis and response to ICIs. Subsequently, the associations of the APscore with the tumor microenvironment (TME), molecular characteristics, clinical features, and somatic mutation variants in aGC were assessed. The area under the receiver operating characteristic curve (AUROC) of the APscore was analyzed to estimate response to ICIs. Cox regression or Log-rank test was used to estimate the prognosis of aGC patients. Results: The APscore constructed by principal component analysis algorithms was an effective predictive biomarker of the response to ICIs in the Kim cohort and 467 aGC patients (Kim: AUC =0.85, 95% CI: 0.69-1.00; 467 aGC: AUC =0.69, 95% CI: 0.63-0.74). The APscore also was a prognostic biomarker in 467 aGC patients (HR=1.73, 95% CI: 1.21-2.46). Inhibitory immunity, decreased TMB and low stromal scores were observed in the high APscore group, while activation of immunity, increased TMB, and high stromal scores were observed in the low APscore group. Next, we evaluated the value of several central genes in predicting the prognosis and response to ICIs in aGC patients, and verified them using immunogenic, transcriptomic, genomic, and multi-omics methods. Lastly, a predictive model built successfully discriminated patients with vs. without immunotherapy response and predicted the survival of aGC patients. Conclusions: The APscore was a new biomarker for identifying high-risk aGC patients and patients with responses to ICIs. Exploration of the APscore and hub genes in multi-omics GC data may guide treatment decisions.

CD137 agonist induces gastric cancer cell apoptosis by enhancing the functions of CD8+ T cells via NF-κB signaling.

BACKGROUND: CD137 is a target for tumor immunotherapy. However, the role of CD137 in gastric cancer (GC), especially in inducing GC cell apoptosis, has not been studied. METHODS: Foxp3+ and CD8+ T cells in GCs were investigated using immunohistochemistry (IHC). CD137 expression in GCs was detected using flow cytometry, IHC and immunofluorescence (IF). Peripheral blood mononuclear cells (PBMCs) and CD8+ T cells isolated from peripheral blood were stimulated with a CD137 agonist in vitro. CD8+ T cell proliferation and p65 expression was examined using flow cytometry. P65 nuclear translocation was analyzed using IF. IL-10, TGF-ß, IFN-γ, perforin and granzyme B were detected using real-time quantitative PCR (real-time PCR). PBMCs and primary GC cells were cocultured and stimulated with a CD137 agonist in vitro. Apoptosis of primary GC cells was detected using flow cytometry. RESULTS: Our data demonstrated that GC tumors showed characteristics of an immunosuppressive microenvironment. CD137 was predominantly expressed in CD8+ T cells in GCs and had a positive correlation with tumor cell differentiation. The CD137 agonist promoted CD8+ T cell proliferation and increased the secretion of IFN-γ, perforin and granzyme B, which induced primary GC cell apoptosis. Mechanistically, this study found that the CD137 agonist induced NF-κB nuclear translocation in CD8+ T cells. CONCLUSION: Our results demonstrated that a CD137 agonist induced primary GC cell apoptosis by enhancing CD8+ T cells via activation of NF-κB signaling.

Downregulation of SLC5A8 inhibits hepatocellular carcinoma progression through regulation of Wnt/ß-catenin signaling.

SLC5A8 has been shown to be associated with a large number of cancer progressions. However, the biological functions of SLC5A8 in hepatocellular carcinoma (HCC) remain largely unclear. Therefore, we performed this research to explore the functions of SLC5A8 in HCC progression. In this study, SLC5A8 protein and mRNA expression were examined by immunohistochemistry and quantitative real-time PCR, respectively, and we found significantly lower expression levels in HCCs than in the corresponding normal liver tissues. Low SLC5A8 expression was significantly correlated with the clinicopathological features of HCC patients. Patients with low SLC5A8 expression have a shorter overall survival time. This interpretation is confirmed by the results obtained from our in vitro experiments; functional assays indicated that overexpression of SLC5A8, by infection with a recombinant plasmid containing SLC5A8, significantly suppressed HCC cell growth, invasion, and migration and induced HCC cell apoptosis. Moreover, the expression levels of beta-catenin, cyclin D1, c-Myc, MMP-2, and FAK detected by western blotting were downregulated in SLC5A8-transfected HCC cells compared with control-transfected cells, indicating that SLC5A8 has a tumor-suppressive function that acts by interfering with Wnt/ß-catenin signaling in HCC.

Hydrogen-rich saline attenuates postoperative liver failure after major hepatectomy in rats.

BACKGROUND/AIMS: A major hepatectomy occasionally lead to acute liver failure and death. We demonstrated the anti-oxidative and anti-inflammatory effects and functional mechanisms of hydrogen-rich saline (HS), a novel antioxidant, on an experimental model of rats after a partial hepatectomy (PH). METHODS: The rats underwent a 90% hepatectomy. HS was given intraperitoneally after the operation and every 8hours after. RESULTS: HS markedly improved the survival rate of two experimental groups after the massive hepatectomy and inhibited increases in serum levels of TBIL, DBIL, ALT and AST. The histopathological analysis demonstrated that HS attenuated inflammatory changes in the liver. HS administration markedly lowered the massive hepatectomy induced elevation of the serum hyaluronic acid (HA) concentrations. HS inhibited the formation of one of the markers of oxidative damage, malondialdehyde (MDA), and increased the activities of superoxide dismutase (SOD) in liver tissue. In the HS-treated group, increases in inflammatory cytokines, such as TNF-α, IL-6 and HMGB-1, were inhibited in the liver tissue. The NF-κB p65 staining revealed that HS inhibited the activation of the transcription factor nuclear factor kappa B (NF-kB). CONCLUSIONS: HS attenuates the massive hepatectomy induced liver injury not only by attenuating oxidative damage, but also by reducing the production of inflammatory cytokines, such as TNF-α, IL-6 and HMGB-1, in part through the inhibition of NF-kB activation.

The preliminary experience in simultaneous treatment of rectal cancer and synchronous liver metastases with laparoscopy.

BACKGROUND/AIMS: There is no consensus for laparoscopy first in patients with rectal cancer and synchronous liver metastases, whose metastases are confined to the liver. This study aimed to evaluate its indications for one-stage surgery in laparoscopy. MATERIALS AND METHODS: Eighteen patients with rectal cancer and synchronous liver metastases, who had undergone laparoscopic colorectal resection and simultaneous treatment for liver metastases, were retrospectively reviewed. RESULTS: Concomitant with laparoscopic colorectal resection, eight patients received liver resection simultaneously; 10 patients underwent a variety of down-staging management including local ablation, right hepatic portal vein ligation, and implantation of chemotherapy pumps into the hepatic artery. The colo-anal/rectal anastomoses were performed with a stapler or "pull-though" mode though the anus. Three patients underwent two-stage liver resection following tumor down-staging. Median survival time was 22.3 months. CONCLUSIONS: Laparoscopy approach for rectal cancer and synchronous liver metastases is feasible in selected patients. Colon pull-through anastomosis was a potential method to avoid abdominal incision and decrease the risk of anastomotic leakage. It is worth further investigation regarding its advantages over traditional modalities with a prospective randomized controlled study.

One-stage resection for Bismuth type IV hilar cholangiocarcinoma with high hilar resection and parenchyma-preserving strategies: a cohort study.

BACKGROUND: Bismuth type IV hilar cholangiocarcinoma (HC) tumors are usually considered unresectable. The strategies of high hilar resection while preserving liver parenchyma can achieve potentially one-stage curative resection for this condition. The aim of the present study was to investigate the feasibility and safety of available strategies. METHODS: Fifty-one consecutive patients with bismuth type IV HC who underwent one-stage resection were retrospectively reviewed with regard to curative resection rate, remnant liver volume, morbidity, mortality, and survival time. RESULTS: The total median survival time was 29 months. The R(0) (curative resection) rate was 57.8%. The ratio of the remnant liver volume (RLV) to the standard liver volume (SLV) ranged from 35.0 to 60.6%, with a mean of 44.5%. The in-hospital mortality and morbidity rates were 3.9 and 37.2%, respectively. In the R0 patients' survival, there was not a significant difference between bilioenteric anastomosis and hepatoenteric anastomosis (P = 0.714). CONCLUSIONS: Combined caudate lobe and high hilar resection (CCHR) is technically safe and oncologically justifiable and could be adopted with a high cure rate as a one-stage resection procedure for most patients with Bismuth type IV HC whose total bilirubin level is less than 20 mg/L and whose direct bilirubin is more than 60% of total bilirubin.

High expression of AP-4 predicts poor prognosis for hepatocellular carcinoma after curative hepatectomy.

The aim of this study was to evaluate the association between activating enhancer binding protein 4 (AP-4) tissue expression and patient prognosis in hepatocellular carcinoma (HCC). The levels of AP-4 mRNA and protein in tumor and para-tumor tissue were evaluated in 30 HCC cases by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Additionally, AP-4 protein expression in 112 HCC was analyzed by immunohistochemistry. The correlation of AP-4 expression and patients' clinicopathological parameters was evaluated. Survival analysis was performed using the Kaplan-Meier method and Cox's proportional hazards model. By RT-PCR and Western blot, the levels of AP-4 mRNA and protein were significantly higher in HCC, compared to that in para-tumor tissue (p < 0.001). Immunohistochemical staining revealed that AP-4 was highly expressed in 53.6 % of the HCC patients. The AP-4 expression level was closely associated with serum alpha fetoprotein elevation, tumor size, histological differentiation, tumor recurrence, tumor metastasis, and tumor stage. Kaplan-Meier survival analysis showed that a high expression level of AP-4 resulted in a significantly poor prognosis of HCC patients. Multivariate analysis revealed that AP-4 expression level was an independent prognostic parameter for the overall survival rate of HCC patients. These findings provide evidence that a high expression level of AP-4 serves as a biomarker for poor prognosis for HCC. Thus, we speculate that AP-4 may be a potential target of antiangiogenic therapy for HCC.

High expression of ADAM8 correlates with poor prognosis in hepatocellular carcinoma.

OBJECTIVES: To evaluate the association between ADAM8 tissue expression and patient prognosis in hepatocellular carcinoma (HCC). METHODS: ADAM8 expression was analyzed using immunohistochemical staining methods on tissue samples from a consecutive series of 105 HCC patients who underwent resections between 2000 and 2006. The correlation of ADAM8 expression and patients' clinicopathological parameters was evaluated. Survival analysis was performed using the Kaplan-Meier method and Cox's proportional hazards model. RESULTS: ADAM8 was highly expressed in 54.3% of the HCC patients. The ADAM8 expression level was closely associated with serum AFP elevation, tumor size, histological differentiation, tumor recurrence, tumor metastasis, and tumor stage. Kaplan-Meier survival analysis showed that a high expression level of ADAM8 resulted in a significantly poor prognosis of HCC patients. Multivariate analysis revealed that ADAM8 expression level was an independent prognostic parameter for the overall survival rate of HCC patients. CONCLUSIONS: These findings provide evidence that a high expression level of ADAM8 serves as a biomarker for poor prognosis for HCC. Thus, we speculate that ADAM8 may be a potential target of antiangiogenic therapy for HCC.

Overexpression of GOLPH3 is associated with poor clinical outcome in gastric cancer.

This study aims to investigate the expression and significance of GOLPH3 in human gastric cancer progression and prognosis. Using immunohistochemistry (IHC) and real-time reverse transcriptase polymerase chain reaction assay, we identified abnormally elevated expression of GOLPH3 in gastric cancer tissues compared to paired normal stomach mucosa tissues in 40 patients. In addition, the enzyme-linked immunosorbent assay (ELISA) was used to quantify serum GOLPH3 concentrations in the same 40 gastric cancer patients and 40 healthy individuals. ELISA revealed significantly higher serum concentrations of GOLPH3 in gastric cancer patients compared to healthy individuals (p = 0.002). In order to investigate the correlations between GOLPH3 and the clinicopathological features of gastric cancer, the expression of GOLPH3 in 123 gastric cancer patients were detected by IHC, and the results showed that overexpression of GOLPH3 was associated with the size of the tumor (p = 0.013), histological grade (p = 0.002), depth of invasion (p < 0.001), lymph node metastasis (p < 0.001), distant metastasis (p = 0.018), and TNM stage (p < 0.001). Kaplan-Meier survival analysis showed that high GOLPH3 expression exhibited a significant correlation with poor prognosis for gastric cancer patients. Further, Cox multivariate analysis indicated that GOLPH3 expression level was an independent prognostic factor for patients after radical resection. In conclusion, the overexpression of GOLPH3 is closely related to the progression of gastric cancer and might be regarded as an independent predictor of poor prognosis for gastric cancer.

Simultaneous resection of abdominal cancer and synchronous pancreaticoduodenal metastasis: indications and literature review.

OBJECTIVE: This study was aimed to identify the potential indications for simultaneous resection of abdominal cancer and synchronous pancreaticoduodenal metastasis (SRAPM) and improve the efficacy of SRAPM. METHODS: The data of 34 patients who underwent SRAPM were retrospectively reviewed. The intraoperative findings, morbidity and mortality, patterns of tumor invasion in the pancreas and duodenum, lymph node metastases, long-term outcomes and causes of death were evaluated. RESULTS: Fourteen patients (41.2%) developed complications, and 2 died of pancreatic fistulas with abdominal bleeding. The in-hospital mortality was 5.9%. The overall 1-year, 2-year and 3-year survival rates were 52.9%, 32.3% and 21.8%, respectively. The survival rates depended on the primary tumor, the invasion pattern, the presence of metastatic lymph nodes at the paraaortic site and the presence of residual tumor. The follow-up outcomes revealed that the main causes of death were as follows: systemic metastasis (n = 7), peritoneal metastasis (n = 6) and intrahepatic metastasis (n = 6). CONCLUSIONS: SRAPM is indicated for low-grade malignant tumors and in cases with direct invasion of the pancreaticoduodenum. The presence of metastatic lymph nodes at the paraaortic site, intrahepatic metastasis, micro-peritoneal metastasis, and distinct metastasis should be contraindications for the surgical procedure.

High RSF-1 expression correlates with poor prognosis in patients with gastric adenocarcinoma.

AIM: To investigate the expression and prognostic significance of RSF-1 in gastric adenocarcinoma. METHODS: RSF-1 expression was analyzed using immunohistochemical staining on tissue samples from a consecutive series of 287 gastric adenocarcinoma patients who underwent tumor resections between 2003 and 2006.The relationship between RSF-1 expression, clinicopathological factors, and patient survival was investigated. RESULTS: Immunohistochemical staining indicated that RSF-1 is highly expressed in 52.6% of gastric adenocarcinomas. RSF-1 expression levels were closely associated with tumor size, histological differentiation, tumor stage, and lymph node involvement. Kaplan-Meier survival analysis showed that high RSF-1 expression exhibited a significant correlation with poor prognosis for gastric adenocarcinoma patients. Multivariate analysis revealed that RSF-1 expression is an independent prognostic parameter for the overall survival rate of gastric adenocarcinoma patients. CONCLUSION: Our data suggest that RSF-1 plays an important role in gastric adenocarcinoma progression and that high RSF-1 expression predicts an unfavorable prognosis in gastric adenocarcinoma patients.

Overexpression of HOXA1 correlates with poor prognosis in patients with hepatocellular carcinoma.

HOXA1 overexpression is sufficient for malignant transformation of nontumorigenic epithelial cells. It is known that HOXA1, which was upregulated in squamous cell carcinomas, affects both cell growth and death. The forced expression of HOXA1 in human breast cancer cells results in increased cell growth activity. However, it has not been reported in hepatocellular carcinoma (HCC). In this study, we used immunohistochemistry to compare HOXA1 protein expression in HCC and normal liver tissues and further analyzed HOXA1 protein expression in 156 clinicopathologically characterized HCC cases. We stably knocked down the endogenous expression level of HOXA1 in HepG2 cells with specific shRNA-expressing lentiviral vector. Following the successful establishment of stable cells, we examined in vitro cell growth by the MTT assay, anchorage-independent growth through a soft agar colony formation assay and cell migration/invasion by transwell and Boyden chamber assay. In addition, we also investigated in vivo tumor growth by xenograft transplantation of HepG2 cells into nude mice. Our results showed that the protein expression level of HOXA1 was markedly higher in HCC tissues than that in normal liver tissue (P = 0.019). In addition, a high expression level of HOXA1 protein was positively correlated with the T classification (P < 0.001), the N classification (P < 0.001), distant metastasis (P = 0.004), and the clinical stage (P < 0.001) of HCC patients. Patients with higher HOXA1 expression showed a significantly shorter overall survival time compared with patients with low HOXA1 expression. Multivariate analysis suggested that HOXA1 expression might be an independent prognostic indicator (P < 0.001) for the survival of patients with HCC. HOXA1-specific shRNA (shHOXA1) successfully knocked down HOXA1 endogenous expression in HepG2 cells. Compared to the parental and control shRNA-transfected (shCtrl) HepG2 cells, the shHOXA1 cells exhibited significantly reduced in vitro cell growth, anchorage-independent growth, and cell migration and invasion (P < 0.05). In vivo, the xenograft transplants from shHOXA1 cells gave rise to much smaller tumors compared with those from shCtrl cells. Collectively, high HOXA1 expression is associated with poor overall survival in patients with HCC. The downregulation of HOXA1 inhibits growth, anchorage-independent growth, and migration and invasion of HepG2 cells.

WWOX induces apoptosis and inhibits proliferation of human hepatoma cell line SMMC-7721.

AIM: To investigate the effects of the WWOX gene on the human hepatic carcinoma cell line SMMC-7721. METHODS: Full-length WWOX cDNA was amplified from normal human liver tissues. Full-length cDNA was subcloned into pEGFP-N1, a eukaryotic expression vector. After introduction of the WWOX gene into cancer cells using liposomes, the WWOX protein level in the cells was detected through Western blotting. Cell growth rates were assessed by methyl thiazolyl tetrazolium (MTT) and colony formation assays. Cell cycle progression and cell apoptosis were measured by flow cytometry. The phosphorylated protein kinase B (AKT) and activated fragments of caspase-9 and caspase-3 were examined by Western blotting analysis. RESULTS: WWOX significantly inhibited cell proliferation, as evaluated by the MTT and colony formation assays. Cells transfected with WWOX showed significantly higher apoptosis ratios when compared with cells transfected with a mock plasmid, and overexpression of WWOX delayed cell cycle progression from G1 to S phase, as measured by flow cytometry. An increase in apoptosis was also indicated by a remarkable activation of caspase-9 and caspase-3 and a dephosphorylation of AKT (Thr308 and Ser473) measured with Western blotting analysis. CONCLUSION: Overexpression of WWOX induces apoptosis and inhibits proliferation of the human hepatic carcinoma cell line SMMC-7721.

Comparison of laparoscopic vs open liver lobectomy (segmentectomy) for hepatocellular carcinoma.

AIM: To investigate the effects of laparoscopic hepatectomy for the treatment of hepatocellular carcinoma (HCC). METHODS: From 2006 to January 2011, laparoscopic hepatectomies were performed on 30 cases of HCC at Northern Jiangsu People's Hospital. During this same time period, 30 patients elected to undergo conventional open hepatectomy over laparoscopic hepatectomy at the time of informed consent. The degree of invasiveness and outcomes of laparoscopic hepatectomy compared to open hepatectomy for HCC were evaluated. RESULTS: Both groups presented with similar blood loss amounts, operating times and complications. Patients in the laparoscopic hepatectomy group started walking and eating significantly earlier than those in the open hepatectomy group, and these more rapid recoveries allowed for shorter hospitalizations. There were no significant differences between procedures in survival rate. CONCLUSION: Laparoscopic hepatectomy is beneficial for patient quality of life if the indications are appropriately based on preoperative liver function and the location and size of the HCC.

Melanoma-associated antigen family protein-D1 regulation of tumor cell migration, adhesion to endothelium, and actin structures reorganization in response to hypoxic stress.

Melanoma-associated antigen family protein-D1 (MAGE-D1) is a recently identified p75 neurotrophin receptor intracellular binding protein and functions as an adaptor that mediates multiple signaling pathways, including Dlx/Msx-mediated transcription. Here, a new regulatory function for MAGE-D1 in tumor cell motility and adhesion to endothelium is described. MAGE-D1 over-expression suppressed HeLa cell and BEL7402 cell migration, invasion, and adhesion to the monolayer of ECV304 cells. We also report that MAGE-D1 over-expression disrupted actin cytoskeleton rearrangement induced by hypoxia and down-regulated hypoxia inducible factor 1-dependent luciferase gene expression. These findings provide new insight into the ability of MAGE-D1 to suppress the motility and adhesion response of tumor cells by interfering with actin cytoskeleton reorganization and hypoxia inducible factor 1-dependent gene expression.

Inhibition of adenovirus-mediated human MAGE-D1 on angiogenesis in vitro and in vivo.

MAGE-D1 is a member of the MAGE family of proteins, and functions as an adaptor that mediates multiple signaling pathways. The current study for the first time provides evidence for a role of MAGE-D1 in the negative regulation of angiogenic activity in vitro and in vivo models. Our findings showed that MAGE-D1 over-expression significantly suppressed the angiogenic key events such as endothelial cell migration and invasion, adhesion on collagen I substrate, and in vitro differentiation into tube-like structures under both normoxic and hypoxic conditions. MAGE-D1 over-expression also inhibited in vivo angiogenesis in Matrigel plugs that were implanted subcutaneously in mice. With further experiments, we revealed that MAGE-D1 over-expression disrupted actin cytoskeleton organization and lamellipodia formation, and down-regulated HIF-1-dependent gene expression in endothelial cells under hypoxic conditions. These findings demonstrate a new function of MAGE-D1 in the regulation of angiogenesis and provide new insight into the ability of MAGE-D1 to suppress the growth and angiogenic response of endothelial cells by interfering with HIF-1-dependent gene expression, and actin cytoskeleton reorganization, suggesting that MAGE-D1 might be a novel inhibitor of angiogenesis in vitro and in vivo.