PARENT SESSION
TOXICOLOGY

Monday, August 2, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(83) CADMIUM (Cd²⁺) STIMULATES TRANSCRIPTIONAL ACTIVITY OF THE P450scc GENE PROMOTER AND INHIBITS APOPTOSIS INDUCED BY ESTRADIOL-17 (E₂) IN CULTURED JC-410 STABLE PORCINE GRANULOSA CELLS.

Furlan, Michel¹, Carver-Ward, Julie¹, Clark, Rena², Urban, Randall³, Chedrese, Jorge¹, ¹ University of Saskatchewan, Saskatoon, SK, Canada² University of Saskatchewan, Saskatoon, SK, Canada³ University of Texas Medical Branch, Galveston, TX

ABSTRACT- Studies were conducted to examine the effects of Cd²⁺ on E₂-induced apoptosis and on transcriptional activity of the P450scc gene promoter in the JC-410 granulosa cells. Cells were genetically modified to express a luciferase genomic construct driven by 2320 bp of the P450scc gene promoter. Cells were exposed to E₂ in the presence or absence of CdCl₂ and examined for morphological changes and for transcriptional activity of the P450scc gene promoter. Morphological changes were assessed by light microscopy and confirmed by the apoptosis-specific stain YOPRO-1. Transcriptional activity of the P450scc gene promoter was assessed by luciferase activity as measured by a luminometric assay. We observed that exposure of JC-410 cells to high concentrations of E₂ (30 M) for 48h induced morphological changes characteristic of apoptosis, including nuclear fragmentation and vacuolation. Moreover, when the same group of cells were co-incubated with CdCl₂ (0.6 M), no evidence of apoptotic changes were observed as compared to the control. E₂ stimulated transcriptional activity of the P450scc gene promoter at concentrations of 0.3, 1, 10 & 30 M. CdCl₂, also stimulated transcription of the P450scc gene promoter, at concentrations between 0.3 to 2 M, and these effects were additive with E₂. We conclude that Cd²⁺ inhibits apoptosis induced by high concentrations of E₂ in the JC-410 stable granulosa cells. We also conclude that apoptosis and stimulation of transcriptional activity of the P450scc gene promoter are two independent events, since high promoter activity was still observed at E₂ concentrations that caused nuclear fragmentation and vacuolation. Studies were funded by NSERC Canada and Agri-Food Innovation Fund (Saskatchewan) grants awarded to JC.

KEY WORDS: estradiol, P450scc gene transcription, cadmium, granulosa cell apoptosis