Abstract 2225: Green tea polyphenols suppress tumor growth and invasion by targeting matrix metalloproteinases, RECK and TIMP-3, in a mouse model implanted with prostate tumors

Abstract

Abstract Green tea polyphenols (GTP) and its major constituent, epigallocatechin-3-gallate (EGCG) reactivate epigenetically silenced genes in cancer cells that reduces invasiveness and migration capabilities; however, the mechanisms whereby these effects occur are not well understood. RECK, a novel tumor suppressor and the tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) genes negatively regulates matrix metalloproteinases (MMPs) and inhibits tumor invasion, angiogenesis and metastasis. In the present study, we demonstrate that GTP mediate epigenetic induction of RECK and TIMP-3 thereby playing a key role in suppressing invasiveness and gelatinolytic activity of MMP-2 and MMP-9 in vivo in an orthotopic implantation model of human prostate cancer. Athymic nude mice were implanted with human prostate cancer LNCaP tumor in the ventral prostate for 2 weeks and later treated DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (AZA), histone deacetylase inhibitor, trichostatin A (TSA) and histone methyltransferase inhibitor, 3-Deazaneplanocin A (DZNep) individually at 0.1 mg/kg body weight intraperitoneally at alternate days/week; and combination of AZA+TSA and DZNep+TSA at similar doses and times; whereas GTP was provided peroral by gavage at 7.5 and 15.0 mg/kg body weight freshly prepared in 100µl PBS. Treatment of mice with GTP resulted in marked decrease in tumor growth and its local invasion in dose dependent manner, compared to treatment with epigenetic inhibitors and their combination after 8 weeks of intervention. GTP treatment significantly reduced serum levels of MMP-2, MMP-9 and VEGF, compared to treatment with epigenetic inhibitors alone. Combination of AZA+TSA exhibited similar effect which was equivalent to the lower dose of GTP treatment. Furthermore, GTP treatment significantly reduced EZH2 and H3K27me3 and class I HDAC protein levels in tumors. GTP partially reversed the hypermethylation status of RECK and TIMP3 gene and significantly enhanced their protein expression in the tumor tissue. Inhibition of VEGF, MMP-2 and MMP-9 levels were also noted after GTP treatment in tumor tissue in dose-dependent manner. Our findings suggest that induction of RECK and TIMP-3 are key epigenetic events modulated by GTP that results in suppression of matrix degradation and angiogenesis to delay prostate cancer invasion and its subsequent progression. Citation Format: Eswar Shankar, Natarajan Bhaskaran, Rajnee Kanwal, Sanjay Gupta. Green tea polyphenols suppress tumor growth and invasion by targeting matrix metalloproteinases, RECK and TIMP-3, in a mouse model implanted with prostate tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2225. doi:10.1158/1538-7445.AM2017-2225