Transfection with SV40 LT promotes oxidative damage in primary cultures of California sea lion muscle cells.

Developing immortalized cell lines could significantly accelerate studies on marine mammal adaptations to breath-hold diving, ischemia/reperfusion cycles and oxidative stress. In this study, skeletal muscle-derived cells from California sea lions (Zalophus californianus) were transfected with simian virus 40 large T antigen (SV40 LT), a viral oncoprotein known to inactivate cell cycle regulators such as p53 and retinoblastoma (pRB). Although transfection and puromycin selection were successful, transfected cells exhibited morphological abnormalities and reduced viability, suggesting altered cellular proliferation pathways. Significantly higher superoxide dismutase (SOD) and glutathione S-transferase (GST) activities (2- and 6.1-fold, respectively), higher protein oxidative damage (3.9-fold), and lower catalase (CAT) activity (6.9-fold) were observed in transfected cells relative to control (untransfected) cells. These findings suggest that peroxide (H₂O₂) accumulation, likely triggered by genotoxic stress, disrupted cellular proliferation and/or cell death pathways in SV40 LT-transfected skeletal muscle-derived cells from California sea lions. Future studies should consider co-transfection with human telomerase reverse transcriptase (hTERT) and the use of lentiviral delivery systems to enhance transfection efficiency, reduce genotoxic effects, and improve culture stability. This study highlights current challenges and offers potential solutions for generating immortalized marine mammal cell lines.