Proapoptotic and proautophagic activity of 20-hydroxyecdysone in breast cancer cells in vitro

Abstract

The present study was designed to identify the biological activity of three ecdysones, i.e., 20-hydroxyecdysone (20-HE), ajugasterone C, and polypodine B isolated from Serratula coronata. The main objective was to investigate the molecular mechanism of the biological activity of those compounds and to assess their impact on breast cancer cell survival and cell cycle. Cell lines were selected according to their hormone receptor status since this factor is perceived as a crucial one in the cancer prognosis as well as cancer cell response to therapy. Consequently, MCF7 (ER/PR+, HER2-), T-47D (ER/PR+, HER2−/+), and MDA-MB-231 (ER/PR-, HER2-) were enrolled in the study. Additionally, a non-tumorigenic, MCF10A cells were selected to verify any potential specificity to cancer cells. Interestingly, none of the studied compounds affected the viability of MCF10A cells while cancer cells were altered, albeit in different ways. Polypodine B did not affect the viability or cell cycle distribution of studied breast cancer cells. By contrast, 20-HE and ajugasterone C significantly inhibited the viability of triple-negative cell line, MDA-MB-231. Interestingly, 20-HE revealed proapoptotic activity in MDA-MB-231 and T-47D cells that was manifested by alterations in PARP, Bax, and Bcl-2 levels as well as caspase-3 activation. Moreover, 20-HE induced autophagy that was mediated by modification of autophagy-associated proteins, i.e., LC3, p62, and mTOR, but only in MDA-MB-231 cells. This study is the first to report diverse biological activity of phytoecdysones in different breast cancer cells, that suggests association with molecular characteristics including receptor status but also other biological properties and genetic markers.