Preclinical evaluation of combined antineoplastic effect of DLC1 tumor suppressor protein and suberoylanilide hydroxamic acid on prostate cancer cells

Abstract

Deleted in liver cancer (DLC1), a tumor suppressor gene in multiple cancers, is recurrently down regulated or inactivated by epigenetic mechanisms in primary prostate carcinomas (PCAs). In this study the methylation and acetylation profile of the DLC1 promoter region was examined in three PCA cell lines with low or undetectable DLC1 expression: LNCaP, its derivative C4-2B-2, and 22Rv1. Two histone deacetylase inhibitors (HDAC), suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA) induced histone acetylation of the DLC1 promoter in all three lines. DLC1 promoter methylation and deacetylation were detected in LNCaP and C4-2B-2 cells while in 22Rv1cells DLC1 is silenced by deacetylation. Treatment with SAHA or TSA efficiently increased DLC1 expression in all lines, particularly in 22Rv1 cells, and activated the DLC1 promoter through the same Sp1 sites. The 22Rv1 cell line was selected to evaluate the efficacy of combined DLC1 transduction and SAHA treatment on tumor growth in athymic mice. Individually, DLC1 transduction and SAHA exposure reduced the tumor size by 75–80% compared to controls and in combination almost completely inhibited tumor growth. The antitumor effect was associated with the induction of apoptosis and inhibition of RhoA activity. SAHA alone significantly reduced RhoA activity, showing that this RhoGTPase is a target for SAHA. These results, obtained with a reliable preclinical in vivo test, predict that combined therapeutic agents targeting the pathways governing DLC1 function and HDAC inhibitors may be beneficial in management of prostate cancer.

Hybrid Enzalutamide Derivatives with Histone Deacetylase Inhibitor Activity Decrease Heat Shock Protein 90 and Androgen Receptor Levels and Inhibit Viability in Enzalutamide-Resistant C4-2 Prostate Cancer Cells

“…SAHA induces histone acetylation at the DLC1 promoter and effectively increases DLC1 mRNA expression in PCa cells (Zhou et al, 2012). Accordingly, DLC1 mRNA was strongly upregulated by SAHA in both LNCaP cells (Fig.…”

“…The relative potencies of HDACI inhibition of 2-75 and 1005 were clearly reflected in their relatively poor ability to induce DLC1, an established nuclear target gene of HDACIs (Guan et al, 2006;Zhou et al, 2010Zhou et al, , 2012, which is strongly induced by SAHA. Compounds 2-75 and 1005 were also poor modulators of histone acetylation in situ compared with SAHA.…”

Deleted in Liver Cancer-1 (DLC1): An Emerging Metastasis Suppressor Gene

“…SAHA alone significantly inhibited on RhoA activity. This combinatorial regimen almost completely inhibited xenograft tumor growth in nude mice, suggesting that this protocol has potential as a therapeutic option in metastatic prostate cancer 84][84]. Among a variety of DNA methylation inhibitors, zebularine that preferentially targets cancer cells, is considered one of the most effective compounds.…”

Cancer Epigenetics: Mechanisms and Crosstalk of a HDAC Inhibitor, Vorinostat

“…On a similar note, in prostate cancer, the expression of a tumor suppressor gene named “deleted in liver cancer” ( DLC1 was efficiently increased upon vorinostat treatment. In primary prostate carcinomas (PCAs), DLC1 is recurrently down-regulated [54]. However, vorinostat treatment resulted in an increased level of methylation in the promoter region of DLC1 , inducing the activation of the DLC1 [54].…”

“…In primary prostate carcinomas (PCAs), DLC1 is recurrently down-regulated [54]. However, vorinostat treatment resulted in an increased level of methylation in the promoter region of DLC1 , inducing the activation of the DLC1 [54]. …”