Abstract: Obective To investigate the effect of valproate acid sodium (VPA) on gap junction intercellular communication in
breast cancer Hs578T cells and explore the mechanism. Methods MTT assay was used to detect the cytotoxicity of VPA on
Hs578T cells, and parachute assay was used to detect the effect of VPA on dye spread of the cells. Western blotting was
employed to detect the expression changes of Cx43 total protein in VPA-treated Hs578T cells. The effect of VPA on the
expression of Cx43 on the surface of Hs578T cells was examined with immunofluorescence assay. Results MTT assay showed
no obvious cytotoxicity of VPA on Hs578T cells at the concentrations below 10 mmol/L. VPA below 5 mmol/L obviously
increased the gap junction function in Hs578T cells (P<0.01), and significantly enhanced the expression of Cx43 total protein (P<
0.01) and Cx43 expression on the surface of Hs578T cells (P<0.01). Conclusion VPA can obviously increase the gap junction
function in Hs578T cells possibly by enhancing Cx43 total protein expression and Cx43 protein expression on the surface of
Hs578T cells.