Curcumin, an active component of the spice turmeric, can exert cytotoxic effects on cancer cells without harming normal tissues. The objectives of this investigation were to a) determine the effects of different doses and durations of curcumin exposure on Lewis lung carcinoma (LLC) cells; b) characterize any curcumin-resistant LLC subpopulation, which may include cancer stem cells (CSCs); and c) demonstrate whether curcumin's cytotoxic effects are enhanced by visible light. Cultured LLC cells were exposed to 10-60 μM curcumin for 2, 4, 8, 16 and 30 hrs at 37°C. After incubation, the cell density was measured by the absorbance of crystal violet staining. The results confirmed that curcumin eliminates LLC cells in a dose and time-dependent manner. We then chose 60 μM curcumin, which caused the highest cell loss (>99%), to select for a curcumin-surviving subpopulation. A cell line established from the survivors was found to have slower growth rate, expressed lower levels of NFκB and aldehyde dehydrogenase (two CSC markers). Tumors developed when syngeneic mice were injected with either LLC cells or the surviving line, although tumor growth appeared slower for the surviving line. The results indicate that curcumin exerts damaging effects not only on cancer cells but also on CSCs. The efficacy of curcumin is hampered outside the digestive tract because of its low bioavailability. To test enhancement of curcumin effects by light, we exposed LLC cells to curcumin and visible light simultaneously. This combination caused greater damage to LLC cells than curcumin or light alone. Our results support a role for curcumin as an anti-cancer agent, especially when combined with visible light or other radiation sources.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2341. doi:1538-7445.AM2012-2341