Mcl-1 protects prostate cancer cells from cell death mediated by chemotherapy-induced DNA damage

Teresita Reiner1, Alicia de las Pozas1,2, Ricardo Parrondo1, Deanna Palenzuela1, William Cayuso2, Priyamvada Rai1,2,3, Carlos Perez-Stable1,2,3

1 Geriatric Research, Education, and Clinical Center and Research Service, Bruce W. Carter Veterans Affairs Medical Center, Miami, FL, USA

2 Division of Gerontology & Geriatric Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami FL, USA

3 Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami FL, USA


Carlos Perez-Stable, email:

Keywords: DNA damage, apoptosis, necrosis, antimitotic, proteotoxic stress

Received: August 03, 2015 Accepted: August 30, 2015 Published: September 01, 2015


The anti-apoptotic protein Mcl-1 is highly expressed in castration-resistant prostate cancer (CRPC), resulting in resistance to apoptosis and association with poor prognosis. Although predominantly localized in the cytoplasm, there is evidence that Mcl-1 exhibits nuclear localization where it is thought to protect against DNA damage-induced cell death. The role of Mcl-1 in mediating resistance to chemotherapy-induced DNA damage in prostate cancer (PCa) is not known. We show in human PCa cell lines and in TRAMP, a transgenic mouse model of PCa, that the combination of the antimitotic agent ENMD-1198 (analog of 2-methoxyestradiol) with betulinic acid (BA, increases proteotoxic stress) targets Mcl-1 by increasing its proteasomal degradation, resulting in increased γH2AX (DNA damage) and apoptotic/necrotic cell death. Knockdown of Mcl-1 in CRPC cells leads to elevated γH2AX, DNA strand breaks, and cell death after treatment with 1198 + BA- or doxorubicin. Additional knockdowns in PC3 cells suggests that cytoplasmic Mcl-1 protects against DNA damage by blocking the mitochondrial release of apoptosis-inducing factor and thereby preventing its nuclear translocation and subsequent interaction with the cyclophilin A endonuclease. Overall, our results suggest that chemotherapeutic agents that target Mcl-1 will promote cell death in response to DNA damage, particularly in CRPC.

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