RBM5 suppresses proliferation, metastasis and glycolysis of colorectal cancer cells via stabilizing phosphatase and tensin homolog mRNA.

Abstract

RNA binding motif 5 (RBM5) has emerged as crucial regulators in many cancers. To explore more functional and mechanistic exploration of RBM5 since the lack of research on RBM5 in colorectal cancer (CRC) dictates that is essential. Through Gene Expression Profiling Interactive Analysis, we analyzed RBM5 expression in colon adenocarcinoma and rectum adenocarcinoma tissues. For detecting the mRNA expression of RBM5, quantitative real time-polymerase chain reaction was performed. Protein expression levels of RBM5, hexokinase 2, lactate dehydrogenase A, phosphatase and tensin homolog (PTEN), phosphoinositide 3-kinase (PI3K), phosphorylated-protein kinase B (p-AKT), and AKT were determined via Western blot. Functionally, cell counting kit-8 and 5-ethynyl-2'-deoxyuridine (EDU) assay were performed to evaluate proliferation of CRC cells. Invasiveness and migration of CRC cells were evaluated through conducting transwell assays. Glucose consumption, lactate production and adenosine-triphosphate (ATP) production were measured through a glucose assay kit, a lactate assay kit and an ATP production assay kit, respectively. Besides, RNA immunoprecipitation assay, half-life RT-PCR and dual-luciferase reporter assay were applied to detect interaction between RBM5 and PTEN. To establish a xenotypic tumor mice, CRC cells were subcutaneously injected into the right flank of each mouse. Protein expression of RBM5, Ki67, and PTEN in tumor tissues was examined using immunohistochemistry staining. Haematoxylin and eosin staining was used to evaluate tumor liver metastasis in mice. We discovered down-regulation of RBM5 expression in CRC tissues and cells. RBM5 overexpression repressed proliferation, migration and invasion of CRC cells. Meantime, RBM5 impaired glycolysis in CRC cells, presenting as decreased glucose consumption, decreased lactate production and decreased ATP production. Besides, RBM5 bound to PTEN mRNA to stabilize its expression. PTEN expression was positively regulated by RBM5 in CRC cells. The protein levels of PI3K and p-AKT were significantly decreased after RBM5 overexpression. The suppressive influences of RBM5 on glycolysis, proliferation and metastasis of CRC cells were partially counteracted by PTEN knockdown. RBM5 suppressed tumor growth and liver metastasis in vivo. This investigation provided new evidence that RBM5 was involved in CRC by binding to PTEN, expanding the importance of RBM5 in the treatment of CRC.