OKADAIC ACID TREATMENT INDUCES DNA ADDUCT FORMATION IN BHK-21 C-13 FIBROBLASTS AND HESV KERATINOCYTES

Okadaic acid (OA), a toxin involved in diarrhetic shellfish poisoning (DSP), has been shown to be a potent tumor promoter in mouse skin and glandular stomach. However, more recent studies tended to show that: O A can also act as a genotoxic. In this study, using the P-32-postlabel ling method, DNA adduct formation was obtained in two cell lines (BHK2 1 C13 fibroblasts and HESV keratinocytes) after treatment by OA for 24 h with a dose range between 0.01 and 5 nM. Nineteen adducts were obse rved with BHK21 C13 cells and 15 with HESV ones. Low doses did not sho w adduct formation. Intermediate doses have given the most important n umber of adducts and with higher doses, the number of adducts decrease d dose dependently. Ten adducts were similar in the two strains while 9 were specific of BHK21 C13 cell line and 5 of HESV one. The highest total DNA adduct level from origin parts was estimated at 95.6 adducts /10(9) nucleotides for BHK21 C13 fibroblasts (1 nM OA treatment) and 3 1.1 adducts/10(9) nucleotides for HESV keratinocytes (0.5 nM OA treatm ent). In this case, the major adduct (number 3) represented 20% for th e fibroblastic cell line and 30% for the keratinocytic strain. The gen otoxic effect of OA showed in this study should lead to a more careful survey of DSP outbreaks.