Morphologic analysis correlates with gene expression changes in cultured F344 rat mesothelial cells

The gene expression pattern of mesothelial cells in vitro was determined af ter 4 or 12 h exposure to the rat mesothelial, kidney, and thyroid carcinog en and oxidative stressor potassium bromate (KBrO3). Gene expression change s observed using cDNA arrays indicated oxidative stress, mitotic arrest, an d apoptosis in treated immortalized rat peritoneal mesothelial cells. Incre ases occurred in oxidative stress responsive genes HO-1, QR, HSP70, GADD45, GADD153, p21(WAF1/CIP16), GST's, GAPDH, TPX, and GPX-1 degrees; transcript ional regulators c-jun, c-fos, jun B, c-myc, and I kappaB; protein repair c omponents R delta, RC10-II, C3, RC-7, HR6B ubiquitin-conjugating enzyme and ubiquitin; DNA repair components PCNA, msh2, and O-6 methylguanine DNA met hyltransferase; lipid peroxide excision enzyme PLA2; and apoptogenic compon ents TNF alpha, iNOS1 and FasL. Decreases occurred in bcl-2 (antiapoptotic) , bar alpha, bad, and bok (proapoptotic) and cell cycle control elements (c yclins). Cyclin G and p14ink4b (which inhibit entry into cell cycle) were i ncreased. Numerous signal transduction, cell membrane transport, membrane-a ssociated receptor, and fatty acid biosynthesis and repair components were altered. Morphologic endpoints examined were number of mitotic figures, num ber of apoptotic cells, and antibody-specific localization of HO-1 (which d emonstrated increased HO-1 protein expression). PCR analysis confirmed HO-1 , p21(waf1/cip1), HSP70, GPX1, GADD45, QR, mdr1, PGHS, and cyclin D1 change s. A model for KBrO3-induced carcinogenicity in the F344 rat mesothelium is proposed, whereby KBrO3 generates a redox signal that activates p53 and re sults in transcriptional activation of oxidative stress and repair genes, d ysregulation of growth control, and imperfect DNA repair leading to carcino genesis, (C) 2000 Academic Press.