Effects of ginger extract and its major component 6-gingerol on anti-tumor property through mitochondrial biogenesis in CD8+ T cells

Ginger extract (GE) and its major component 6-gingerol (6G) have been reported to exert anti-tumor effects in various cancers. The underlying mechanism, however, has not been well demonstrated. Here, we have focused on the relationship between promotion of mitochondrial biogenesis in tumor infiltrating CD8(+) T cells induced by GE and 6G and their cytotoxic effect. The results showed that GE induced 56% inhibition of tumor growth in Lewis lung carcinoma (LLC) xenograft mouse model and 6G induced 33% (25 mg/kg) and 37% (50 mg/kg) inhibition. GE increased mitochondrial mass of CD8(+) T cells in tumor and draining lymph nodes (DLNs) significantly, while 6G had no significant effect. GE and 6G both had no significant influence on histopathological changes of liver and kidney in mice. In the co-culture system of CTLL-2 cells and LLC cells, GE enhanced the cytotoxicity of CTLL-2 cells against LLC cells by 14% and 19% at concentrations of 2.5 and 5 mg/ml, respectively. 6G did not promote cytotoxicity of CTLL-2 cells. GE increased mitochondrial mass at 5 and 10 mg/ml and mtDNA copy number and ATP production at 2.5, 5, 10 mg/ml in CTLL-2 cells. 6G promoted mtDNA copy number at 50, 100, 150 mu M and mitochondrial mass and ATP production at 25, 50, 100, 150 mu M in CTLL-2 cells. These results suggest that promotion of mitochondrial biogenesis and function in tumor infiltrating CD8(+) T cells may play an essential role in GE-induced inhibition of tumor growth. The current results perfect the mechanism of anti-tumor effect of ginger, which is beneficial for further application in cancer management. Practical Application Ginger, as a worldwide food seasoning and herbal medicine in traditional Chinese medicine, has been reported to possess anti-tumor efficacy. To our knowledge, it is the first time to focus on ginger's ability of promoting mitochondrial biogenesis in tumor infiltrating CD8(+) T cells to explore the mechanism of its anti-tumor effect. Our observations demonstrate that ginger inhibits tumor growth via promoting mitochondrial biogenesis and function of T cells. The present study links food to anti-tumor immunity and provides impetus to investigate and design dietary supplements for cancer management.