NBDHEX re‐sensitizes adriamycin‐resistant breast cancer by inhibiting glutathione S‐transferase pi

PURPOSE: Adriamycin is a novel chemotherapeutic agent of great benefit for treating breast cancer. However, adriamycin ‐resistance remains a major obstacle. The vital Glutathione transferase P1 (GSTPi) inhibitor 6‐(7‐nitro‐2,1,3‐benzoxadiazol‐4‐ylthio) hexanol (NBDHEX) has recently shown antitumor activity in various cancers. In this study, we analyzed the effect of NBDHEX and adriamycin combination against breast cancer in vitro and in vivo. METHODS: CCK‐8 assay was performed to test cell viability. The location and expression level of GSTpi was determined by immunofluorescence and Western blot in cells and immunohistochemistry staining in tissues. The enzyme activity test was applied to detect the effect of NBDHEX on the activity of GSTpi. The apoptosis related proteins' expression was tested using Western blot. The phosphorylation sites of GSTpi were detected by mass spectrometry. Antitumor effects of single treatment or co‐administration of adriamycin and NBDHEX were evaluated in nude mice. RESULTS: NBDHEX treatment inhibited GSTpi enzyme activity and co‐administration of adriamycin and NBDHEX promoted apoptosis of adriamycin‐resistance breast cancer cell. Moreover, drug combination of NBDHEX and adriamycin significantly enhanced tumor growth inhibition compared with single agent. CONCLUSION: NBDHEX serves as a good candidate for combination with adriamycin, offering new insights for breast cancer treatment.