Xiaoai Jiedu Prescription-containing Serum Enhances Lethal Effect of NK Cells on Colon Cancer Cells / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the influence of Xiaoai Jiedu prescription （XJP）-containing serum on natural killer （NK） cells′ lethal effect on colon cancer cells and the molecular mechanism. MethodXJP-containing serum （0.1%， 0.5%， 1%， 5%， 10%） was used to treat HCT-116 cells and NK-92MI cells respectively for 24 h， and methyl thiazolyl tetrazolium （MTT） assay was employed to detect cell proliferation. Then， low-concentration （0.1%， 0.5%， 1%） XJP-containing serum was selected to treat co-cultured HCT-116 cells and NK-92MI cells for 24 h and calcein acetoxymethyl ester/propidium iodide （Calcein-AM/PI） was applied to detect the killing effect of NK cells on colon cancer cells. Flow cytometry was used to detect apoptosis of colon cancer cells， Western blot the expression of apoptosis-related proteins and signal transducer and activator of transcription 4 （STAT4） pathway-related proteins， and enzyme-linked immunosorbent assay （ELISA） the secretion of interferon （IFN）-γ. ResultHigh-concentration （5%， 10%） XJP-containing serum inhibited the proliferation of HCT-116 and NK-92MI cells （P<0.01）， while low-concentration （0.1%， 0.5%， 1%） XJP-containing serum had no obvious influence on cell proliferation compared with the blank group. As compared with the blank group， low-concentration XJP-containing serum enhanced the killing activity of NK cells against colon cancer cells in a concentration-dependent manner （P<0.01）， and induced apoptosis of colon cancer cells （P<0.01）. Moreover， XJP-containing serum （0.1%， 0.5%， 1%） down-regulated the expression of B-cell lymphoma 2 （Bcl-2） and B-cell lymphoma-extra large （Bcl-xl）， and up-regulated the expression of Bcl-2-associated X （Bax） compared with the blank group （P<0.05， P<0.01）. Compared with the co-culture group， XJP-containing serum （0.1%， 0.5%， 1%） increased the expression of p-STAT4 and IFN-γ （P<0.05）. ELISA result showed that XJP-containing serum （0.1%， 0.5%， 1%） raised IFN-γ secretion （P<0.01）. ConclusionXJP-containing serum can enhance the activity of NK cells to kill colon cancer cells. The mechanism is the likelihood that it activates STAT4 pathway， increases IFN-γ secretion by NK cells， down-regulates the expression of Bcl-xl and Bcl-2， and up-regulates the expression of Bax， thereby promoting the apoptosis of colon cancer cells.