curcumin and Cocarcinogenesis

Topics: Administration, Oral; Administration, Topical; Allyl Compounds; Animals; Anticarcinogenic Agents; Antioxidants; Carcinogens; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; Cocarcinogenesis; Curcumin; Female; Flavonoids; Humans; Male; Mice; Mice, Inbred SENCAR; Neoplasms, Radiation-Induced; Papilloma; Phenols; Phytotherapy; Plants, Medicinal; Polymers; Reactive Oxygen Species; Resveratrol; Silymarin; Skin Neoplasms; Stilbenes; Sulfides; Tea; Ultraviolet Rays; Zingiber officinale

Expression of c-jun protein (c-Jun) was observed in normally proliferating JB6 cells but not in confluent cells. Reduction of the serum concentration from 5% to 2% in the cell culture medium caused JB6 cells to enter a quiescent non-proliferating state and down-regulated the expression of c-Jun. Treatment of quiescent JB6 cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) (10 ng/ml) for 24 h markedly stimulated the formation of c-Jun and caused morphological changes. Treatment of JB6 cells with TPA for 48 h resulted in transformed foci with mixed cell populations. Although some cells in these foci expressed high levels of c-Jun, many other cells did not. The increased expression of c-Jun and morphological changes observed at 24 h after treatment of JB6 cells with TPA (10 ng/ml) was inhibited by curcumin (10 nmol/ml). Treatment of JB6 cells with 2.5, 5 or 10 nmol curcumin/ml inhibited the formation of TPA-induced anchorage-independent colonies that grow in soft agar by 31%, 43% and 77%, respectively. Although inhibition of cell proliferation was not observed with 2.5 nmol curcumin/ml, higher concentrations did inhibit cell proliferation. Topical application of 5 nmol TPA to the backs of CD-1 mice once a day for 5 days caused epidermal hyperplasia and the levels of c-Jun were increased in the suprabasal layer of the epidermis and in the muscle layer of the dermis. This treatment also increased c-fos protein (c-Fos) expression in the muscle layer, but there was little or no increase in the expression of c-Fos in the basal or suprabasal layer of the epidermis. Topical application of 10 mumol curcumin together with 5 nmol TPA once a day for 5 days strongly inhibited TPA-induced epidermal hyperplasia and c-Jun and c-Fos expression. A single application of 180 mJ/cm2 of ultraviolet B light (UVB) to the backs of SKH-1 mice caused epidermal hyperplasia and expression of c-Fos and c-Jun in the muscle layer of the dermis and of c-Fos in the suprabasal layer of the epidermis. Maximum effects were observed at 6 days after UVB exposure. Application of 10 mumol curcumin to mouse skin twice a day for 5 days immediately after UVB exposure had only a small/variable inhibitory effect on UVB-induced increases in the expression of c-Fos and c-Jun and on epidermal hyperplasia.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Animals; Cell Division; Cell Transformation, Neoplastic; Cells, Cultured; Cocarcinogenesis; Curcumin; Drug Interactions; Female; Gene Expression Regulation; Hyperplasia; Mice; Mice, Hairless; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-jun; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Ultraviolet Rays