RESUMO
A number of carcinogens like polycyclic hydrocarbons and aromatic amines have been incriminated to induce mammary carcinomas in vitro and in vivo. Studies have supported an inter-relationship between tobacco consumption and breast cancer. Because nicotine is the major alkaloid present in tobacco this study was conducted to find the direct in vitro effect of nicotine on normal mammary ductal epithelial cells. It was seen in the present work that nicotine causes a statistically significant increase in the proliferative rate and ER (estrogen receptor) expression as compared to the control group. This change was more pronounced with a lower concentration of nicotine (650 microg/ml). Colony efficiency also showed a similar trend. Beta carotene was added in the present work to study its anti oxidant effect on nicotine induced changes. Beta carotene significantly decreased the proliferation rate induced by 650 microg/ml nicotine. It also prevented the cytotoxic effect of higher dose of nicotine, however, it failed to alter significantly the ER expression induced by lower concentration of nicotine though it showed decreasing trend.