Notoginsenoside R1 induces DNA damage via PHF6 protein to inhibit cervical carcinoma cell proliferation

Notoginsenoside R1 (NGR1), a monomer of Traditional Chinese medicine, is from the Panax notoginsenoside complex, and has been reported to inhibit the proliferation of various types of cancer. However the mechanism underlying NGR1-mediated inhibition of cervical carcinoma cell proliferation remains unclear. Therefore, the current study aimed to investigate the antitumor effects of NGR1 on cervical carcinoma cell lines (CaSki and HeLa cells) in vitro. The Cell Counting Kit-8 and soft agar cell colony formation assay results revealed that NGR1 suppressed the viability and the number colonies of CaSki and HeLa cells, respectively. Furthermore, the DAPI staining, flow cytometry and western blotting results revealed that NGR1 induced cervical carcinoma cell apoptosis, cell cycle arrest in the S phase, upregulation of cyclin A2 and CDK2 expression levels, and downregulation of cyclin D1 expression levels. To further investigate the mechanisms of NGR1, DNA-damage-related proteins, including H2A.X variant histone (H2AX), ATR serine/threonine kinase (ATR) and p53, and the nucleolus protein, plant homeodomain finger protein 6 (PHF6) were analyzed. The results indicated that NGR1 triggered the phosphorylation of H2AX and ATR in a dose- and time-dependent manner, and downregulated the expression level of PHF6 and upregulated the expression level of p53 in a dose- and time-dependent manner. In conclusion, the findings of the present indicated that NGR1 may inhibit the viability of cervical carcinoma cells and induce cell apoptosis via DNA damage, which may be activated by the downregulation of PHF6 expression levels, and the subsequent triggering of the phosphorylation of H2AX and ATR. In addition, NGR1 may exert an ability to arrest cervical carcinoma cells in the S phase and upregulate the expression levels of cyclin A2 and CDK2. Therefore, NGR1 may serve as a novel chemotherapeutic agent for cervical carcinoma.