Curcumin increases exosomal TCF21 thus suppressing exosome-induced lung cancer

Curcumin is a novel drug for lung cancer treatment. However, the mechanism underlying the anti-tumor effect of curcumin remains elusive. Previous evidences indicated that, the methylating transferase DNMT1 is downregulated by curcumin, and the transcription factor 21 (TCF21) is suppressed by DNMT1. We hereby attempt to elucidate the correlation between curcumin treatment and TCF21 expression. Exosomes derived from curcumin-pretreated H1299 cells were used to treat BEAS-2B cells, which induced proliferation, colony formation and migration of BEAS-2B cells. An increase in TCF21 expression in response to curcumin was also seen, as revealed by real-time PCR (RT-PCR) and western blot. Analysis using the GEO database (access #GSE21210) indicated that a positive correlation existed between TCF21 levels and lung cancer patient survival. TCF21 overexpression and knockdown was introduced to H1299 cells through lentiviral system, which led to suppression and promotion of tumor growth, respectively. We also demonstrated that DNMT1 expression was downregulated by curcumin. Therefore, curcumin exerts its anti-cancer function by downregulating DNMT1, thereby upregulating TCF21.