Silencing of Girdin suppresses the malignant behavior of colorectal carcinoma cells.

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.