Low-dose curcumin leads to the inhibition of tumor growth via enhancing CTL-mediated antitumor immunity.

Curcumin, a yellow pigment extracted from turmeric, is widely used to inhibit tumor progression. Since it can either promote or suppress the immune system, how curcumin affects the immune system in tumor-bearing bodies is not yet clear. Our study found that tumor-bearing mice treated consecutively once a day with low-dose curcumin for ten days led to a retarded tumor growth and a longer survival, which might be contributed to T cell-mediated adaptive immune response. The in vitro study also showed that a high-dose curcumin decreases T cells whereas a low-dose increases T cells derived from 3LL tumor-bearing mice, especially CD8+ T cells. Accordingly, these increased CD8+ T cells exhibited the enhancement of IFN-γ secretion, proliferation and cytotoxicity specifically against 3LL tumor cells, which may result in the success of antitumor immunity. Our research demonstrated a beneficial effect of curcumin on CD8+ T cells derived from tumor-bearing mice, which can provide a potential application in anti-tumor therapy.