Silencing of Girdin suppresses the malignant behavior of colorectal carcinoma cells

Abstract

The aim of the present study was to investigate the effect of the actin-binding protein Girdin on the proliferation, invasion and migration of colorectal cancer (CRC) cells. Cultured CRC cells (LoVo cell line) were transfected by Girdin-specific and control shRNA constructs and analyzed for proliferation, invasion and migration by the MTT, Transwell and wound-healing assays, respectively. The activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway and expression of proinflammatory cytokines was examined by western blotting and ELISA assay, respectively. The effect of Girdin silencing on CRC growth was also evaluated in a xenograft model using nude mice, which were subcutaneously injected with Girdin-deficient and negative control LoVo cells and analyzed for tumor volume and weight. Transfection of LoVo cells with Girdin-specific shRNA inhibited Girdin mRNA expression to 27.5% and protein expression to 36.7% when compared with expression levels in the control cells (P<0.001) and significantly demonstrated suppression of LoVo cell proliferation (P<0.05), invasion (P<0.01) and migration (P<0.01). Furthermore, Girdin silencing downregulated the phosphorylation of the signaling proteins JAK (by 42%, P<0.001) and STAT3 (by 34%, P<0.01) and the content of IFN (by 28%, P<0.001) and IL-6 (by 44%, P<0.001) compared to the control. Notably, inhibition of Girdin expression effectively suppressed tumorigenicity of LoVo cells in vivo as evidenced by the reduced volume (P<0.05) and weight (P<0.05) of the tumors derived from Girdin shRNA-transfected LoVo cells compared to those from the control cells. In conclusion, the silencing of Girdin expression inhibited the malignant behavior of CRC cells via the downregulation of the JAK/STAT signaling pathway, indicating Girdin as a potential therapeutic target in CRC. In the present study, we revealed, for the first time, that the malignant behavior of CRC cells depended on the expression of an actin-binding protein, Girdin. Silencing of Girdin expression by specific shRNA suppressed the proliferation, invasion, and migration of CRC cells through the decrease in proinflammatory cytokines IFN and IL-6 and the downregulation of the JAK/STAT signaling pathway. Our findings indicated that Girdin expression may be a potential novel therapeutic target in CRC.