Ribosomal protein s15a (RPS15A) plays a promotive role in the mRNA/ribosome interactions during early translation. Our previous study has found that inhibiting RPS15A expression can decrease proliferation and induce cell cycle arrest in hepatocellular carcinoma (HCC) cell lines. However, the mechanism underlying the involvement of RPS15A in HCC pathogenesis and the clinical significance of RPS15A expression remain unclear. In this study, an evaluation of RPS15A expression in 110 surgically resected HCCs and matched tumor-adjacent normal tissues revealed an overexpression of RPS15A in HCC, which was correlated with worse survival. In addition, tumor tissue with higher RPS15A expression demonstrated a higher microvascular density (MVD). Subsequently, two HCC cell lines, Huh7 (low-level constitutive RPS15A expression) and HepG2 (high RPS15A expression) were used to further evaluate the role of RPS15A in angiogenesis. The co-culture experiment of HCC cells with endothelial cells revealed that the induced overexpression of RPS15A in Huh7 cells increased the angiogenic potential of HUVEC in a paracrine fashion; conversely, knockdown of RPS15A in HepG2 cells showed an opposite effect. Further analysis indicated that RPS15A modulated FGF signaling by enhancing Wnt/beta-catenin-mediated FGF18 expression in HCC cells. FGF18, in turn, through binding to its FGFR3 receptor on endothelial cells, can activate the AKT and ERK pathway and promotes angiogenesis in a tumor microenvironment. Our in vivo experiment further confirmed that inhibition of RPS15A expression in HCC xenografts dramatically hindered tumor growth and inhibited tumor angiogenesis. Together, our findings suggest that RPS15A promotes angiogenesis in HCCs by enhancing Wnt/beta-catenin induced FGF18 expression. The RPS15A/FGF18 pathway may be a rational target for anti-angiogenic therapy of HCC.

Glypican-3 (GPC3) is a widely used immunohistochemical marker for hepatocellular carcinoma (HCC); however, its prognostic value is unclear. Immunohistochemical evaluation of GPC3 expression was performed on 300 postoperative HCC tissue samples with paired adjacent non-tumor tissues on tissue microarray sections. The integral optic density, representing the expression level of GPC3 in each HCC sample, was calculated using Image-Pro Plus. The outcome-based cut-point optimization was performed using X-tile software. GPC3 was highly expressed in HCC tissues compared with adjacent non-tumor tissues. The expression level of GPC3 was significantly correlated with overall survival (OS) and time to recurrence (TTR). The lower the level of GPC3 expression in HCC tissue, the poorer the observed prognosis. Univariate and multivariate analyses showed that the expression level of GPC3 in HCC was an independent prognostic factor for both OS and TTR. In conclusion, GPC3 expression is an independent prognostic factor for postoperative HCC, and low expression levels of GPC3 in HCC may indicate poor outcome.

BackgroundEndothelial progenitor cells (EPCs) can migrate to the tumor tissue and enhance the angiogenesis of hepatocellular carcinoma (HCC); thus, they are associated with a poor prognosis. However, the specific molecular mechanism underlying the homing of EPCs to the HCC neovasculature remains unrevealed.MethodsCo-culture experiments of endothelial progenitor cells with HCC cells with modulation of EphA1 were performed in vitro. Using EPCs as angiogenic promoters by injecting them into HCC xenograft-bearing nude mice via their tail veins to test homing ability of EPCs changed according to different EphA1 level in HCC xenograft.ResultsIn this study, we found that the up-regulation of EphA1 expression in HCC cells could affect not only the chemotaxis of EPCs to tumor cells and endothelial cells (ECs) but also the tube formation ability of EPCs in a paracrine fashion. Further, we revealed that the increased expression of EphA1 in HCC cells led to an increased SDF-1 concentration in the tumor microenvironment, which in turn activated the SDF-1/CXCR4 axis and enhanced the recruitment of EPCs to HCC. In addition, the EphA1-activated SDF-1 expression and secretion was partially mediated by the PI3K and mTOR pathways. In vivo experiments demonstrated that blocking EphA1/SDF-1/CXCR4 signaling significantly inhibited the growth of HCC xenografts. Using immunohistochemistry and immunofluorescence assays, we verified that the inhibition of tumor angiogenesis was at least partially caused by the decreased number of EPCs homing to tumor tissue.ConclusionsOur findings indicate that targeting the EphA1/SDF-1 signaling pathway might be a therapeutic anti-angiogenesis approach for treating HCC.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-016-0339-6) contains supplementary material, which is available to authorized users.

Kruppel-like factor 8 (KLF8) is a transcription factor which has been identified to play a critical role in oncogenic transformation, epithelial-mesenchymal transition and invasion. Higher expression level of KLF8 has been observed in ovarian, renal and breast cancer cells. This study focused on investigating the knockdown effects of KLF8 through lentivirus mediated targeted disruption of KLF8 in gastric cancer cell lines. The expression level of KLF8 is much higher in gastric cancer cells than that in normal cell via Western blot analysis. The decreased expression level of KLF8 after repression was confirmed by real-time PCR and Western blot in SGC-7901, a gastric cancer cell line. The effects of KLF8 deletion on cell proliferation and cell cycle were analyzed by MTT assay and flow cytometry, respectively. Finally, the effects of KLF8 deletion on cell apoptosis and invasion of gastric cancer cells were analyzed by Annexin staining and transwell assay, respectively. It was observed that knockdown of KLF8 reduced the cellular proliferation of SGC-7901 gastric cancer cells, a phenotype at least partially due to cell cycle arrest at G1 phase and increased apoptosis. Furthermore, the inhibition of KLF8 reduces the invasion rates of the cancer cells. Therefore, KLF8 is necessary for cell survival and invasion in gastric cancer cells. The absence of KLF8 may lead to cancer cell death. These results demonstrated that the lentivirus mediated targeted disruption of KLF8 would be an promising therapeutic method for treatment of gastric cancer.

The antidiabetic drug metformin has been shown to possess antitumor functions in many types of cancers. Although studies have revealed its beneficial effects on the prognosis of hepatocellular carcinoma (HCC), the detailed molecular mechanism underlying this event remains largely unknown. In this work, we showed that miR-23a was significantly induced upon metformin treatment; inhibition of miR-23a abrogated the proapoptotic effect of metformin in HepG2 cells. We next established forkhead box protein A1 (FOXA1) as the functional target of miR-23a, and silencing FOXA1 mimicked the effect of metformin. Moreover, the phosphorylation of AMP-activated protein kinase (AMPK) and the expression of p53 were increased upon metformin treatment, and the inhibition of p53 abrogated the induction of miR-23a by metformin, suggesting that AMPK/p53 signaling axis is responsible for the induction of miR-23a by metformin. In summary, we unraveled a novel AMPK/p53/miR-23a/FOXA1 axis in the regulation of apoptosis in HCC, and the application of metformin could, therefore, be effective in the treatment of HCC.