srgap1, a co-target of mir-340 and mir-124, functions as a potential oncogene with amplification and recurrent mutation in gastric tumorigenesis
Refereed conference paper presented and published in conference proceedings

摘要Introduction: SRGAP1 (Slit-Robo GTPase-activating protein 1) functions as a GAP for Rho-family GTPases and downstream of Slit-Robo signaling. However, the involvement of SRGAP1 activation and functional role in gastric carcinogenesis has not been investigated. Aims & Methods: We aim to investigate the biological functions of SRGAP1 and comprehensively reveal its regulation by deregulated miRNAs in gastric carcinogenesis. The mRNA and protein expression of SRGAP1 were examined by qRT-PCR and Western blot. The biological role of SRGAP1 in GC was demonstrated by MTT proliferation, monolayer colony formation, cell invasion and migration assays through siRNA-mediated knockdown. The prediction of miRNAs which potentially target SRGAP1 was performed by TargetScan ( and miRDB ( miR-340 and miR-124 were screened out for further validation. The regulation of SRGAP1 by miRNAs was confirmed by qRT-PCR, Western blot and dual luciferase activity assays by ectopic expression of miR-340 and miR-124. Results: SRGAP1 is over-expressed in 9 out of 12 (75.0%) GC cell lines both from the mRNA and protein level. In clinical samples form TCGA cohort, SRGAP1 shows gene amplification in 5/258 (1.9%) cases and its mRNA upregulation shows positive correlation with the copy number change. The mutation rate of SRGAP1 in primary GC is 8/258 (3.1%) Knockdown of SRGAP1 in MKN28, MGC-803 and SGC-7901 cells exhibited significant anti-oncogenic effect in vitro. SRGAP1 downregulation suppressed cell proliferation, reduced monolayer colony formation, and inhibited at least 50% of the cell invasion and migration ability. Moreover, luciferase activity experiments revealed SRGAP1 knockdown significantly inhibited Wnt/β-catenin pathway, which was further confirmed by the inactivation of β-catenin and downregulation of CCND1 and c-Myc. In addition, SRGAP1 was confirmed to be a direct target of miR-340 and miR-124 in GC. These two miRNAs showed decreased expression compared with adjacent normal epithelium cells and the downregulation of miR-340 and miR-124 were associated with poor survival. Enforced overexpression of miR-340 and miR-124 in GC cells also exerted tumor-suppressive function by inhibiting cell proliferation and inducing G1 phase cell cycle arrest. In 28 paired GC samples, the expression of SRGAP1 protein showed negative correlation with the expression of miR-340 and miR-124. Conclusion: SRGAP1 is over-expressed and plays an oncogenic role in GC through activating Wnt/β-catenin pathway. Apart from gene amplification and mutation, the activation of SRGAP1 in GC is partly due to the downregulation of tumor suppressor miRNAs, miR-340 and miR-124. These findings provided clinical implications that targeting SRGAP1 might have therapeutic potential for GC.
著者W. Kang, T. Huang, Y. Zhou, Y. Dong, J.H.M. Tong, K.F.
會議名稱United European Gastroenterology (UEG) Week 2016
會議論文集題名United European Gastroenterology Journal
期次Suppl. 1

上次更新時間 2018-18-01 於 08:22