Gender differences in gemcitabine (Gemzar) efficacy in cancer cells: effect of indole-3-carbinol.

Pancreatic cancer has a poor prognosis, mainly due to lack of effective therapies. This study demonstrated the ability of dietary agent, indole-3-carbinol (I3C), to lower the LD(50) of gemcitabine (Gemzar) in decreasing growth of both male (MiaPaca2) and female (SU86.86) pancreatic cancer cells. Female pancreatic cancer cells were more resistant to gemcitabine alone. Additionally, RT-PCR analysis of MiaPaca2 cells treated with 1, 10 or 100 μM of I3C showed that I3C reactivated the tumor suppressor gene p16INK4a in pancreatic cancer cells. Methylated-specific PCR analysis indicated that I3C demethylated the promoter region of p16 INK4a, which was methylated in the untreated cancer cells. p16INK4a inactivation through promoter hypermethylation is considered an early event in pancreatic carcinogenesis. A positive control using 5-azacytidine also reactivated p16INK4a. This study demonstrated the potential of I3C, a possible non-toxic hypomethylating agent, combined with the anticancer agent, gemcitabine, to be a powerful strategy for treating pancreatic cancer.