Modulation of Cell Cycle Progression in the Spermatocyte Cell Line [GC-2spd(ts) Cell-Line] by Cigarette Smoke Condensate (CSC) via Arylhydrocarbon Receptor-Nuclear Factor Erythroid 2-Related Factor 2 (Ahr-Nrf2) Pathway. Issue 1 (1st January 2014) - Esakky, Prabagaran
Abstract: Prior studies in our laboratory have demonstrated that cigarette smoke condensate (CSC) activates arylhydrocarbon receptor ( Ahr ) leading to upregulation of several antioxidant enzymes in murine spermatocytes. In this study, we show that exposure of the spermatocyte cell line GC-2spd(ts) to CSC induces an increase in Cyp1a1, demonstrating AHR activation, and simultaneous expression and nuclear translocation of nuclear factor erythroid 2-related factor 2 (NRF2), where it is believed to modulate Ahr expression by a feedback mechanism. Pharmacological inhibition by the AHR-antagonist CH223191 and interference by Ahr - and Nrf2 -small interfering RNA followed by quantitative real-time PCR implicate the Ahr-Nrf2 pathway in the modulation of DNA damage and growth suppression genes such as Gadd45a and P21 and oxidative stress-related genes Cyp1a1, Nrf2, and Ahrr . Flow cytometry accompanied with cell proliferation assay indicate the CSC induces accumulation of spermatocytes at the S-G2/M phase of the cell cycle. Thus, the data obtained suggest that CSC contains several AHR-agonists that are capable of altering the growth pattern of spermatocytes in vitro through the Ahr-Nrf2 signaling mechanism.