FW-04-806, A Macrolide Dilactone Compound, Shows Potent Efficacy Against HER2-positive Gastric Cancer Cell Lines

Objective: To investigate the efficacy of FW-04-806against HER2-positive gastric cancer cell lines in vivo and in vitro, and the combination effect of FW-04-806with Lapatinib.Methods:(1) MTT assay was used to assess cell proliferous inhibition of FW-04-806in vitro.(2) The inhibitory effect of colony formation in HER2-positive gastric cancer cells was tested by colony formation. The apoptotic induction of FW-04-806in HER2-positive gastric cancer cells was detected by FITC-PI double staining.(4) Cell cycle was analyzed by PI staining.(5) Western blot was applied to reveal the expression of related protein level.(6) Co-immunoprecipitation was used to investigate protein-protein interactions.(7) The expression of Hsp90client proteins was showed by Immunohistochemistry.(8) The tumor growth inhibition of FW-04-806was evaluated in tumor xenograft model.Results:(1) FW-04-806inhibited the cell proliferation of gastric cancer cell lines NCI-N87、OE19、AGS and SGC-7901in dose-dependent manner with IC50of24.17、29.61、58.13、60.59μmol·L-1, respectively, showing more sensitivity in HER2-positive gastric cancer cell lines.(2) FW-04-806significantly suppressed the colony formation of HER2-positive gastric cancer cells NCI-N87and OE19.(3) With the increase of drug concentration, the apoptosis rate increased, after the treatment of FW-04-806in NCI-N87and OE19cells.(4) FW-04-806blocked HER2-positive gastric cancer cells in the G2-M phase of the cell cycle.(5) FW-04-806blocked HER2downstream signaling pathway, inhibiting the phosphorylation of HER2、Akt and ERK and increasing the expression of apoptotic proteins, such as cleaved caspase3and cleaved parp.(6) FW-04-806dissociated Hsp90/CDC37complex, interrupting the binding of Hsp90and CDC37.(7) FW-04-806obviously degraded the expression of Hsp90client proteins HER2and Akt.(8)FW-04-806significantly inhibited tumor growth in vivo with inhibition of tumor growth of48.0%, P<0.01, the difference of which has statistically significance.Conclusion:(1) FW-04-806shows potent efficacy against HER2-positive gastric cancer in vitro and in vivo.(2) FW-04-806may be a potential Hsp90inhibitor, inhibiting the Hsp90function by interrupting the binding of Hsp90and CDC37, resulting in the degradation of Hsp90client proteins HER2、Akt, and the blockage of HER2downstream signaling pathways.(3) FW-04-806is synergistic with Lapatinib, the mechanism of which may be based on the enhancement of proliferous inhibition and apoptotic induction.