Selective CDK7 inhibition with BS-181 suppresses cell proliferation and induces cell cycle arrest and apoptosis in gastric cancer

Abstract

Cyclin-dependent kinase (CDK) family members have been considered as attractive therapeutic targets for cancer. In this study, we aim to investigate the anticancer effects of a selective CDK7 inhibitor, BS-181, in gastric cancer (GC) cell line. Human GC cells (BGC823) were cultured with or without BS-181 at different concentrations for 24-72 hours. BS-181 significantly reduced the activity of CDK7 with downregulation of cyclin D1 and XIAP in GC cells. Treatment with BS-181 induced cell cycle arrest and apoptosis. The expression of Bax and caspase-3 was significantly increased, while Bcl-2 expression was decreased in cells treated with BS-181. In addition, the inhibition of CDK7 with BS-181 resulted in reduced rates of proliferation, migration, and invasion of gastric cells. Those results demonstrated the anticancer activities of selective CDK7 inhibitor BS-181 in BGC823 cells, suggesting that CDK7 may serve as a novel therapeutic target or the treatment of GC.

Keywords: BS-181; anticancer activities; gastric cancer; selective CDK7 inhibitor.

Figure 1

BS-181 decreased the migration and invasion ability of BGC823 cells. Notes: BGC823 cells were treated with BS-181 for 24 hours at indicated concentrations. Migration and invasion assay of BGC823 cells (A). BS-181 significantly decreased the number of migrated (B) and invaded (C) cells. Compared with control group ^*P<0.05 and ^**P<0.01; compared to other groups ^##P<0.01.

Figure 2

BS-181 induced cell apoptosis (A) and regulated apoptosis-related protein expressions (B and C). Notes: BS-181-induced BGC823 cell apoptosis in a dose- and time-dependent manner. Additionally, BS-181 increased expression of proapoptotic proteins and decreased expression of antiapoptotic proteins. Compared with control group ^*P<0.05 and ^**P<0.01; compared to other groups ^#P<0.05 and ^##P<0.01.

Figure 3

BS-181-impaired cell cycle progression in BGC823 cells. Notes: Cell cycle distribution was analyzed by flow cytometry (A). Data are presented as the mean of triplicate experiments (B). Administration of BS-181 significantly increased the percentage of cells in the G0/G1 phase, and significantly decreased the S and G2/M phase fractions.

Figure 4

BS-181-inhibited phosphorylation of CDK7 substrates. Notes: Whole cell lysates were prepared from BGC823 cells treated with BS-181 for 4 hours at indicated concentrations. Immunoblotting was carried out using antibodies for RNA polymerase II or Pol II phosphorylated at Ser5 in the C-terminal domain (A). Data are presented as mean ± SD of three independent experiments (B). Compared to other groups ^#P<0.05 and ^##P<0.01.

Figure 5

BS-181-inhibited gastric cancer growth in vivo and increased survival rate. Notes: The change in tumor volume (A) was determined for each animal, as tumor volume relative to the tumor volume of each animal at day 1; mice body weights (B) were similar between groups for a 14-day observation; treatment with BS-181 significantly increased survival rate in an additional 30-day observation (C); roscovitine was used as a positive control. Compared to control group ^*P<0.05, ^**P<0.01, and ^***P<0.001. Compared to other groups ^#P<0.05.