The effect of stannous and stannic (tin) chloride on DNA in Chinese hamster ovary cells.

Tin(II) at concentrations up to 500 microM stannous chloride (SnCl2), produced extensive DNA damage, as detected by alkaline sucrose gradient (ASG) analysis in Chinese hamster ovary (CHO) cells treated for 1 h at 37 degrees C in serum-free minimal essential medium (MEM). However treatment of cells with tin(IV), as stannic chloride (SnCl4), produced no such DNA damage. There was no loss in colony formation 6 days after either treatment suggesting that the DNA damage induced by the tin(II) was rapidly repaired and/or that DNA synthesis proceeded on the damaged templates permitting cell division to occur. Alternatively, the type of DNA damage caused by tin(II) may not lead to a reduction in colony-forming ability. Tin(II) produced about 200 times more ASG detectable DNA damage on an equi-molar basis than did Cr(VI), a known human carcinogen. This study indicates that tin(II) may be potentially genotoxic.