Effect and action mechanism of luteolin on cell growth of colon cancer

Objective To investigate the effect of luteolin on the growth of colon cancer cells, and to further clarify whether luteolin inhibits tumor growth or not by regulating the activity of immune cells.

Methods Mouse colon cancer cell lines (MC-38, CT-26, CMT-93) and human colon cancer cell lines (Caco-2) were cultured in vitro, the effects of luteolin on proliferation, apoptosis and migration of colon cancer cells at different concentrations (0, 1, 5, 10, 20 μmol/L)were observed. The tumor bearing model of mouse colon cancer cell MC-38 was constructed to observe the effects of luteolin on tumor growth, apoptosis and migration of cancer cells. The effect of luteolin on activity of mouse spleen immune cells and human peripheral blood lymphocytes was detected in vitro.

Results Luteolin at concentration of 5 μmol/L significantly inhibited the proliferation of mouse colon cancer cell line CT-26; luteolin at concentration of 10 μmol/L significantly inhibited the proliferation of mouse colon cancer cell line MC-38 and CMT-93; luteolin at concentration of 20 μmol/L significantly inhibited the proliferation of human colon cancer cell line Caco-2. Luteolin significantly inhibited the division and apoptosis of mouse colon cancer cell line CT-26, and significantly inhibited the migration of mouse colon cancer cell line MC-38. Treatment with luteolin at 20 mg/kg body weight significantly inhibited tumor growth and prolonged survival of colon cancer MC-38 bearing mice in vivo. In vitro different concentrations of luteolin stimulation did not affect the proliferation of mouse spleen immune cells, but significantly upregulated the expression of NKG2D on mouse CD8⁺T cells and natural killer (NK) cells. Luteolin at concentration of 10 μmol/L (effect target ratio of 3 to 1) could significantly up-regulate the killing activity of CD8⁺ T cells and NK cells against target cells. Luteolin stimulation up-regulated expressions of CD69 and NKG2D in human peripheral blood CD8⁺T cells in vitro.

Conclusion Luteolin inhibits the growth of colorectal cancer cells, promotes the activity of immune cells and inhibits tumor growth.