Regulation of carcinogenesis and mediation through Wnt/\u03b2-catenin signaling by 3,3\u2032-diindolylmethane in an enzalutamide-resistant prostate cancer cell line

Chih-Wei Tsao,Sheng-Tang Wu,Tai-Lung Cha,Jia-Sin Li,Chin-Yu Liu,Ya-Wen Lin

doi:10.1038/s41598-020-80519-3

Chih-Wei Tsao, Sheng-Tang Wu + Show 4 more

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https://doi.org/10.1038/s41598-020-80519-3

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Abstract

Enzalutamide (ENZ) is an important drug used to treat castration-resistant prostate cancer (CRPC), which inhibits androgen receptor (AR) signaling. Previous study showed that 3,3′-diindolylmethane (DIM) is an AR antagonist that also inhibits Wnt signaling and epithelial-mesenchymal transition (EMT). To investigate whether combined treatment with ENZ and DIM can overcome ENZ resistance by regulating Wnt signaling to inhibit AR signaling and EMT in ENZ-resistant prostate cancer cells, 22Rv1 cells were cultured in normal medium and treated with ENZ, DIM, and DIM with ENZ. Exposure of ENZ-resistant cells to both DIM and ENZ significantly inhibited cell proliferation without cytotoxicity and invasion in comparison with the control. DIM significantly increased the E-cadherin expression and inhibited the expressions of Vimentin and Fibronectin, subsequently inhibiting EMT. Co-treatment with ENZ and DIM significantly increased the expressions of GSK3β and APC and decreased the β-catenin protein expression, causing inhibition of Wnt signaling and AR expression, it also significantly decreased the AR-v7 expression and down-regulated AR signaling. Via suppression of Wnt and AR signaling, co-treatment increased the E-cadherin and decreased the Vimentin and Fibronectin RNA and protein expressions, then inhibited EMT. Co-treatment with DIM and ENZ regulated Wnt signaling to reduce not only the AR expression, but also the AR-v7 expression, indicating suppression of EMT that inhibits cancer cell proliferation, invasion and migration to ameliorate ENZ resistance.

Highlights

Prostate cancer (PCa) is the second most common cancer in men; it is the fifth leading cause of cancer mortality among men worldwide[1]
In the current study, we focused on androgen receptor (AR), AR-v7 and Wnt signaling to investigate whether combined treatment with ENZ and DIM could overcome ENZ resistance by regulating Wnt signaling to inhibit AR signaling and epithelial-mesenchymal transition (EMT) in ENZ-resistant PCa cells
We found that co-treatment with DIM and ENZ inhibited prostate cancer cell proliferation, invasion and migration through regulating Wnt signaling to reduce the expressions of AR and AR-v7

Summary

Introduction

Prostate cancer (PCa) is the second most common cancer in men; it is the fifth leading cause of cancer mortality among men worldwide[1]. Recent evidence has shown that several mechanisms are involved in ENZ resistance, including AR mutation, the existence of AR splice variants (AR-Vs), AR and glucocorticoid receptor (GR) overexpression, autophagy, intracrine androgen biosynthesis, and epithelial-mesenchymal transition (EMT)[11,12,13]. The stabilization and nuclear translocation of β-catenin play crucial roles while Wnt signaling is engaged. Of several mechanisms involved in ENZ-resistant CRPC, aberrant AR signaling is a crucial one. AR-Vs may be associated with the initiation and progression of PCa. Evidence has shown that AR-V expressions are involved in EMT, which plays important roles in cancer progression and drug resistance[23,24,25]. Among approximately 20 different variants, increased AR-v7 expression has been identified in CRPC patients, and is related to ENZ resistance[26,27]. A new adjuvant therapy might be helpful in improving the treatment of ENZresistant CRPC

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