An approach to enhancing the phototoxicity of a novel hypocrellin congener to MGC803 cells

A novel photosensitizer, 2-butylamino-2-demethoxy-hypocrellin A (2-BA-2-DMHA) has been found to cause high phototoxicity to MGC803 cells mainly via apoptosis. To increase the efficiency of 2-BA-2-DMHA-mediated photodynamic therapy (PDT) to MGC803 cells, we transferred the retrovirus-mediated wild-type p53 gene to MGC803 cells. As a result, we found that wild-type p53 infected MGC803 cells expressed exogenous p53 mRNA and a high level of p53 protein. Overexpression of the gene made the cells more sensitive to 2-BA-2-DMHA-mediated PDT. At a concentration of 0.25 muM 2-BA-2-DMHA with a red light of 10 J cm-2 (lambda=600¯700 nm), the wild-type p53 infected MGC803 cell survival was 4 times lower than that associated with the parent and the empty vector infected MGC 803 cell survival. In addition, apoptosis appeared earlier in wild-type p53 infected MGC803 cells.