Effect and Mechanism of Xianlian Jiedu Prescription Against Proliferation of Colorectal Cancer Cells in Hypoxic Microenvironment / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo study the effect of Xianlian Jiedu prescription （XLJDP） on the activation of nuclear transcription factor-κB （NF-κB） signaling pathway induced by bromodomain-containing protein 4 （Brd4） in hypoxic microenvironment and to explore its mechanism in inhibiting the proliferation of colorectal cancer HT-29 cells. MethodThe human colorectal cancer HT-29 cells were cultured in a hypoxic incubator or normoxia incubator and treated with XLJDP at 0.8，1，1.2，1.6，3.2，6.4，and 12.8 g·L-1 for 48 h， respectively. Following the detection of cell vitality using methyl thiazolyl tetrazolium （MTT） colorimetry， the effects of XLJDP （1.25，2.5，and 5 g·L-1） on the cell mitochondrial membrane potential were determined using a fluorescent probe （JC-1）， and the apoptosis of colorectal cancer HT-29 cells was detected by flow cytometry. The cell colony formation assay and 5-ethynyl-2'-deoxyuridine （EDU） staining were conducted to test the proliferation of colorectal cancer HT-29 cells. The Western blot was carried out to measure the expression levels of Brd4 and its downstream relevant proteins such as c-Myc and hexamethylene bisacetamide-inducible protein 1 （HEXIM1）， as well as the effects of XLJDP on related proteins in the NF-κB signaling pathway. ResultCompared with the blank control group， XLJDP at 0.8，1，1.2，1.6，3.2，6.4，and 12.8 g·L-1 inhibited the vitality of colorectal cancer HT-29 cells （P<0.05 ， P<0.01）， with the median inhibitory concentration （IC50） under the hypoxic condition higher than that under the normoxia condition. Compared with the blank control group， XLJDP at 1.25，2.5，and 5 g·L-1 significantly decreased the mitochondria membrane potential， enhanced the apoptosis （P<0.05，P<0.01）， and lowered the number of cell colonies and also the EDU-positive cells （P<0.05， P<0.01）. The results of Western blot showed that compared with the blank control group， XLJDP at 1.25，2.5，and 5 g·L-1 down-regulated Brd4， c-Myc， p-NF-κB p65， and p-IκBα protein expression to varying degrees and up-regulated the expression of HEXIM1 （P<0.05， P<0.01）. ConclusionIn the hypoxic microenvironment， XLJDP inhibits the proliferation of colorectal cancer HT-29 cells regulated by Brd4， which may be related to its inhibition of the activation of NF-κB signaling pathway.