Neutralization of the induced VEGF-A potentiates the therapeutic effect of an anti-VEGFR2 antibody on gastric cancer in vivo

The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis is an essential regulator of angiogenesis and important therapeutic target in cancer. Ramucirumab is an anti-VEGFR2 monoclonal antibody used for the treatment of several cancers. Increased circulating VEGF-A levels after ramucirumab administration are associated with a worse prognosis, suggesting that excess VEGF-A induced by ramucirumab negatively affects treatment efficacy and that neutralizing VEGF-A may improve treatment outcomes. Here, we evaluated the effect of combination treatment with an anti-VEGFR2 antibody and anti-VEGF-A antibody on gastric tumor progression and normal tissues using a preclinical BALB/c-nu/nu mouse xenograft model. After anti-VEGFR2 antibody treatment in mice, a significant increase in plasma VEGF-A levels was observed, mirroring the clinical response. The elevated VEGF-A was host-derived. Anti-VEGF-A antibody co-administration enhanced the anti-tumor effect of the anti-VEGFR2-antibody without exacerbating the toxicity. Mechanistically, the combination treatment induced intra-tumor molecular changes closely related to angiogenesis inhibition and abolished the gene expression changes specifically induced by anti-VEGFR2 antibody treatment alone. We particularly identified the dual treatment-selective downregulation of ZEB1 expression, which was critical for gastric cancer cell proliferation. These data indicate that the dual blockade of VEGF-A and VEGFR2 is a rational strategy to ensure the anti-tumor effect of angiogenesis-targeting therapy.

lncRNA MALAT1 overexpression promotes proliferation, migration and invasion of gastric cancer by activating the PI3K/AKT pathway

Long non-coding RNA (lncRNA) has been implicated in various types of human cancer. However, the role of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in gastric cancer remains unclear. In the present study, MALAT1 expression was significantly upregulated in gastric tumors compared with adjacent healthy tissue in patients with gastric cancer. Furthermore, MALAT1 plasma expression was higher in patients with gastric cancer compared with healthy controls and was found to have prognostic and diagnostic value independent of patients' lifestyle choices. Cell proliferation assay and Transwell migration and invasion results indicated that the overexpression of MALAT1 resulted in increased proliferation, migration and invasion of gastric cancer cells in vitro, possibly through activation of the phosphoinositide 3-kinase/protein kinase B pathway.