Abstract 3139: Nurr1, a novel target of 1,1-bis(3’-indolyl)-1-(p-chlorophenyl) methane for inhibition of the initiation and progression of skin cancer tumorigenesis

Abstract

Abstract The objective of this study was to demonstrate the chemopreventive potential of 1,1-bis(3′-indolyl)-1-(p-chlorophenyl methane) (DIM-D) in skin cancer using an in vitro and in vivo models. In vitro cell cytotoxicity and viability assays were carried out in A431 human epidermoid carcinoma cell line (A431) and normal human epidermal keratinocytes (NHEK) respectively. Apoptosis induction and accumulation of ROS following UVB exposure in DIM-D pretreated NHEK cells (2 hr prior) was also evaluated. Immunocytochemistry and western blot analysis were performed to determine proapoptotic and proinflammatory markers expressions in DIM-D treated A431 cells and in UVB irradiated NHEK cells. For in vivo experiments, DIM-D was encapsulated within nanocarriers by hot melt homogenization using Nano DeBEE. Nanocarriers were surface modified with oleic acid and incorporated into a gel using established procedures (G-NOD) and characterized for particle size, zeta potential, entrapment efficiency, rheology, skin permeation and drug release. The chemo-preventive efficiency of G-NOD was evaluated using UVB-induced skin cancer model in SKH hairless mice and skin samples were collected and investigated for lipid peroxidation, protein carbonyls, and molecular markers by western blot. The IC50 values of DIM-D were 24.5±2.6, 17.2±3.6and 4.1±1.1 whilst for EGCG were 192.1±3.8, 85.3±2.4 and 26.0 ±1.4 for 24, 48 and 72 hr treatments respectively. DIM-D induced higher expression in A431 cells compared to EGCG of cleaved caspase 3 (3.0-fold vs. 2.4-fold changes), Nurr1 (2.7-fold vs. 1.7-fold changes) and NFκB (1.3-fold vs. 1.1-fold changes). Nanocarriers containing DIM-D were 188.00±8.00 nm in size with polydispersity of 0.59±0.01. The zeta potential and entrapment efficiency were 37.17±0.90mV and 89±0.50%, respectively. There was significant (p<0.05) reduction in tumor size/number for G-NOD pretreated group (2 tumors/mouse, average diameter, 2±0.50 mm) compared to DIM-PG (4 tumors/mouse, average diameter, 4±0.45mm) and EGCG PEG-gel (EGCG-PG; 6 tumors/mouse, average diameter, 5±0.25mm). IHC and western blot results indicated significant increase (p<0.05) in expression of Nurr1 in G-NOD pretreated group compared to EGCG-PG. There was however pronounced reduction in expression of STAT3, NFkB, cleaved Caspase-3, BCl2 and 8-OHdG for G-NOD pretreated group compared to DIM-PG and EGCG-PG. Lipid peroxidation assay revealed decrease in amount of Malondialehyde (MDA) produced in G-NOD pretreated group prior to UV exposure by 2 fold compared to DIM-PG and 1.3 fold compared to EGCG-PG treatments. Therefore, findings in both in vitro and in vivo studies suggest that the enhanced percutaneous delivery of DIM-D reduces UVB-induced damage to skin lipids and protein and inhibits initiation and progression of skin photocarcinogenesis in SKH mice via the transactivation of Nurr1. Citation Format: Ravi Doddapaneni, Cedar Boakye, Punit Shah, Apurva R. Patel, Chandraiah Godugu, Stephen Safe, Santosh Katiyar, Mandip Sachdeva. Nurr1, a novel target of 1,1-bis(3’-indolyl)-1-(p-chlorophenyl) methane for inhibition of the initiation and progression of skin cancer tumorigenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3139. doi:10.1158/1538-7445.AM2014-3139