Effect Of The Na_v1.5 Expression On Migration And Invasion Of Human Colorectal Cancer Multi-drug Resistant Cells

Objective: The purpose of this study was to determine the interaction between the invasion and migration in colorectal cancer multi-drug-resistant cell and the level of Na_v1.5 protein expression and Na+ current level. Also we have explored the possible molecular mechanism of Na_v1.5 function on the migration and invasion in colorectal cancer multi drug-resistant cell. Methods: Our research chose colorectal cancer cell(CRC) line(SW620) and Oxaliplatin-resistant CRC cell line(SW620/Ox R) as study objects. CCK8 assay and Transwell technique were used to compare with the function of proliferation, migration and invasion of SW620 and SW620/Ox R cells; Western blot technique was used to detect the protein expression of Na_v1.5, P-gp(P-glycoprotein), and the marker of EMT(Epithelial-mesenchymal transition, E-cadherin and N-cadherin) in two kinds of CRC cell lines; The inward Na+ current level in two kinds of CRC cell lines was detected by whole cell patch clamp technique. Observed the effect of TTX(Tetrodotoxin), a specific inhibitor on before-mentioned indicator in two kinds of cancer cell lines. Results: Compared with SW620 cells, the capacity of proliferation in SW620/Ox R cells has no significant change(P>0.05); however, the abilities of invasion and migration in SW620/Ox R cells have significantly increased than SW620 cells(P<0.01, P<0.01); The result of Western blot analysis showed that the protein level of P-glycoprotein, Na_v1.5 and N-cadherin have higher increased than SW620 cells(P<0.01), however, the level of E-cadherin proteinof SW620/Ox R cells has significance declined compared with SW620 cells(P<0.01); The result of electrophysiology showed that compared with SW620 cells,the expression level of inward Na+ current level of SW620/Ox R cells has significantly increased(P<0.05); Western blot result showed that TTX have significantly declined the level of Na_v1.5 protein expression in SW620 and SW620/Ox R cells(P<0.05, P<0.05), and increased the level of E-cad protein expression in SW620 cells, and declined the level of N-cad protein expression in SW620/Ox R cells(P<0.05, P<0.05); However, TTX have no effect on the proliferation capability of SW620 and SW620/Ox R cells(P>0.05). Conclusion:(1) The higher expression of Na_v1.5 α subunit can significantly increase intracellular Na+ current level in Ox R-resistant CRC cell line, and it maybe also involve in CRC multi-drugresistant process.(2) Enhancing the function of Na_v1.5 can promote EMT in Ox R-resistant CRC cell lines.(3) TTX significantly decrease the capability of invasion and migration in CRC cell lines, it may relates to inhibition or reversalof EMT in CRC cells...