SRF Potentiates Colon Cancer Metastasis and Progression in a microRNA-214/PTK6-Dependent Manner

OBJECTIVE: Serum response factor (SRF), a sequence-specific transcription factor, is closely related to metastasis of gastric cancer, a digestive tract cancer. Herein, we probed the effect of SRF on metastasis and progression of colon cancer (CC), another digestive tract disorder, and the detailed mechanism. METHODS: Microarray analysis was conducted on tumor and adjacent tissues to filter differentially expressed miRNA, followed by RT-qPCR validation in CC cell lines. The transcription factor and the target gene of microRNA-214 (miR-214) were predicted, and their binding relationships were tested by luciferase reporter assays and ChIP assays. Subsequently, SRF and protein tyrosine kinase 6 (PTK6) expression in CC patients and cells was evaluated by RT-qPCR, while JAK2 and STAT3 expression in cells by Western blot analysis. To further explore functions of miR-214, PTK6 and SRF on CC, CC cells were delivered with si-PTK6, miR-214 mimic and/or SRF overexpression. RESULTS: miR-214 expressed poorly in CC tissues and cell lines, which related to advanced TNM staging and survival. miR-214 mimic inhibited proliferation, migration, invasion, xenograft tumor growth and metastasis of CC cells. SRF, overexpressed in CC samples and cells, suppressed the transcription of miR-214. Meanwhile, SRF upregulation counteracted the inhibitory role of miR-214 mimic in CC cell growth. miR-214 negatively regulated PTK6 expression to impair the JAK2/STAT3 pathway activation, thereby halting CC cell proliferation, migration, invasion, xenograft tumor growth and metastasis. CONCLUSION: Altogether, miR-214 may perform as a tumor suppressor in CC, and the SRF/miR-214/PTK6/JAK2/STAT3 axis could be applied as a biomarker and potential therapeutic target.