SMP30 Regulates HCC Cell Migration via Affecting the Expression of MMPs and Binding to ROCK1

Abstract Background: SMP30, as a calmodulin, is differentially expressed in hepatocellular carcinoma（HCC） tissues and adjacent tissues. Previous studies have indicated that the expression of SMP30 is closely related to the prognosis of patients with HCC. However, little is known about the detailed role of SMP30 on HCC. Methods: The SMP30 overexpression and silenced cell lines were constructed through lentivirus transfection，the effects of SMP30 on migration and invasion of HCC were observed by Transwell assay. Then subcloned cell line with different migration abilities were undergone four rounds of screening from SMP30 overexpressing cell lines, and the transcriptome and proteome were detected and analyzed. The interactions of proteins with SMP30 were validated by AP-MS and COIP-WB techniques. Results: High expression of SMP30 can effectively inhibit the migration and invasion of HCC, but has no significant effect on cell proliferation and cell cycle. The cell lines with higher metastatic abilities have significantly higher calcium ion concentrations than those with lower metastatic abilities and higher expression of MMP9, MMP14 and MMP15 proteins. There is an interaction between SMP30 and tumor metastasis-related protein ROCK1, which reduces the phosphorylation level of cytoskeleton-related MLC protein. The SMP30 regulatesthe downstream molecule MLC protein phosphorylation and affects the formation of cytoskeletal structure. Conclusion: On the one hand, SMP30 regulates the expression of MMPs protein by regulating the Ca2 + concentration; on the other hand, SMP30 affects the phosphorylation level of MLC protein by interacting with ROCK1 protein. The combined effect of the two aspects inhibits the metastatic ability of HCC.