Inhibitory action of (-)-epigallocatechin gallate on radiation-induced mouse oncogenic transformation.

The anticarcinogenic activity of a major component of green tea, (-) epigallocatechin gallate (EGCg) was examined by using the radiation-induced oncogenic transformation in C3H10T1/2 cells. EGCg substantially suppressed the radiation-induced transformation so that the transformation frequency with 15 microM of EGCg was reduced nearly to spontaneous levels. This effect of EGCg was in a dose-dependent manner and significant suppression of transformation was observed even in treatment of cells with 5 microM of EGCg concentration where the cytotoxicity was mild. The inhibitory effect of EGCg was maximal when it was present during the entire incubation period. However, neither treatment prior to nor concurrent with radiation was effective, suggesting that EGCg action is mainly involved in the promotional stage of C3H10T1/2 cell transformation.

[Effect of sunlight on the skin--what have we learned?]. / Ljuseffekter på huden--vad har vi lãart oss?

Ultraviolet radiation (UVR) exerts a variety of effects on the skin, most of which are inimical. Best known is the effect of UVB radiation which readily burns unprotected skin, but we now know that even UVA radiation may exert penetrating effects on the skin, as well as causing DNA damage and increased risk of cancer. The markedly increased incidence of basal cell and squamous cell carcinoma and malignant melanoma among fair-skinned Caucasians in industrialised countries is attributed to increased exposure to UVR. Sunscreen creams may have exacerbated the situation. Effective phototherapy is a useful product of photomedical research, and it can be further improved. Recently new perspectives were opened up in basic research into UVR, when it was found that repair of DNA lesions via different pathways orchestrates a series of cellular phenomena such as oncogene expression, acid radical defence, immunomodulation, apoptosis and pigmentation induction.