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Defective autophagy in multidrug resistant cells may lead to growth inhibition by BH3‐mimetic gossypol
Author(s) -
Ahn JunHo,
Jang GunHee,
Lee Michael
Publication year - 2013
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.24305
Subject(s) - gossypol , 3t3 cells , apoptosis , flow cytometry , autophagy , cell culture , programmed cell death , cytotoxic t cell , biology , chemistry , microbiology and biotechnology , cancer research , biochemistry , transfection , in vitro , genetics
The clinical efficacy of many chemotherapeutic agents has been reduced due to the development of drug resistance. In this article, we aimed to validate gossypol, a natural BH3 mimetic found in cottonseeds, as a potential therapeutic to overcome multidrug resistance (MDR). Gossypol was found to retain its efficacy in v‐Ha‐ ras ‐transformed NIH 3T3 cells that overexpressed P‐glycoprotein (Ras‐NIH 3T3/Mdr), which was similar to the efficacy observed in their parental counterparts (Ras‐NIH 3T3). A rhodamine assay revealed that the alteration of MDR activity did not contribute to the cytotoxic effect of gossypol. Gossypol caused a G 2 /M arrest by the induction of p21 Cip1 and the down‐regulation of p27 Kip1 expression in Ras‐NIH 3T3 cells, whereas no significant G 2 /M arrest was exhibited in Ras‐NIH 3T3/Mdr cells. Surprisingly, a 48‐h treatment with gossypol induced apoptotic cell death in Ras‐NIH 3T3 cells; however, gossypol induced both apoptosis and necrosis in Ras‐NIH 3T3/Mdr cells, as determined with flow cytometry analysis. More notably, gossypol preferentially induced autophagy in Ras‐NIH 3T3 cells but not in Ras‐NIH 3T3/Mdr cells. Coimmunoprecipitation and flow cytometric analysis revealed that gossypol‐induced autophagy is independent of the dissociation of Beclin 1 from Bcl‐2 in Ras‐NIH 3T3 cells. Taken together, these results suggest that the antiproliferative activity of gossypol appears to be due to cell‐cycle arrest at the G 2 /M phase, with the induction of apoptosis in Ras‐NIH 3T3 cells. In addition, defective autophagy might contribute to apoptotic and necrotic cell death in response to gossypol in Ras‐NIH 3T3/Mdr cells. J. Cell. Physiol. 228: 1496–1505, 2013. © 2012 Wiley Periodicals, Inc.