Dual regulation of cell cycles by Shuanghuang Shengbai Granule in Lewis-bearing mice with chemotherapy-induced myelosuppression and its mechanism

OBJECTIVE To explore the dual regulatory effects of Shuanghuang Shengbai Granule, a compound traditional Chinese herbal medicine, on cell cycle in Lewis-bearing mice with chemotherapy-induced myelosuppression. METHODS Thrity Lewis-bearing mice were randomly divided into control group, untreated group and treated group. A model of myelosuppression was established by peritoneal injection of cyclophosphamide to Lewis-bearing mice. Mice in the treated group were treated with Shuanghaung Shengbai Granule for 6 days. Cell cycle progressions of cells collected from bone marrow and tumor tissues were assayed by flow cytometry, and proliferation index (PI) was also calculated. Expressions of cyclin-dependent kinase 4 (CDK4), cyclin-dependent kinase 6 (CDK6) and cyclin D1 in bone marrow and tumor tissues were detected by Western blotting and immunohistochemical method. RESULTS Percentages of bone marrow and tumor cells in G0/G1 phase in the untreated group were lower than those in the control group; however, the PI of untreated group was higher than that of the control group. The expressions of CDK4, CDK6 and cyclin D1 in bone marrow and tumor tissues in the untreated group were increased as compared with the control group. Compared with the untreated group and the control group, the percentage of bone marrow cells in G0/G1 phase was decreased, and the PI of bone marrow cells and the expressions of CDK4, CDK6 and cyclin D1 were increased in bone marrow in the treated group. However, the percentage of tumor cells in G0/G1 phase in the treated group was increased, and the PI of tumor cells and the expressions of CDK4, CDK6 and cyclin D1 in tumor tissues were decreased as compared with the untreated and control groups. CONCLUSION Shuanghuang Shengbai Granule may have a function of cell cycle dual regulation in Lewis-bearing mice with chemotherapy-induced myelosuppression by regulating the expressions of CDK4, CDK6 and cyclin D1 in bone marrow and tumor tissues.