Antioxidant therapy alleviates oxidative stress by androgen deprivation and prevents conversion from androgen dependent to castration resistant prostate cancer

Abstract

Purpose: Prostate cancer progression from androgen dependence to castration resistance results at least in part from oxidative stress induced by androgen deprivation therapy. We elucidated the state and the role of oxidative stress induced by androgen deprivation therapy and the possibility of antioxidant therapy in human prostate cancer.

Materials and methods: We investigated 4-HNE (4-hydroxy-2-nonenal histidine adduct) staining, and Twist1, YB-1 and androgen receptor expression by immunohistochemistry in prostate cancer samples treated with or without neoadjuvant androgen deprivation therapy. Intracellular reactive oxygen species and protein expression were examined by CM-H(2)DCFDA and Western blot analysis, respectively. A cell proliferation assay and a mouse xenograft model were used to assess tumor growth.

Results: Androgen deprivation therapy increased oxidative stress, as shown by 4-HNE staining in human prostate cancer tissue. Twist1 and YB-1 expression was up-regulated by androgen deprivation, resulting in androgen receptor over expression. In LNCaP and 22Rv1 cells androgen deprivation increased intracellular reactive oxygen species and evoked Twist1, YB-1 and androgen receptor over expression, resulting in cell growth in a castration resistant manner. Growth was alleviated by N-acetyl-cysteine, an electrophile that supports glutathione production. N-acetyl-cysteine also decreased LNCaP and 22Rv1 tumor growth in castrated and noncastrated mice.

Conclusions: Androgen deprivation therapy induced oxidative stress in in vitro and human prostate cancer. Antioxidant therapy using N-acetyl-cysteine appears to be a promising therapeutic modality for prostate cancer.