Chen Guan-di, Qian De-Ying, Li Zhi-Gang, Fan Ge-Ying, You Ke-Li, Wu Yi-Long
Southern Medical University, Guangzhou, Guangdong, China.
Department of Gynecology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China.
Cell Biochem Funct. 2017 Dec;35(8):488-496. doi: 10.1002/cbf.3282. Epub 2017 Nov 15.
Cervical cancer is one of the most common malignancies of the female reproductive system. Therefore, it is critical to investigate the molecular mechanisms involved in the development and progression of cervical cancer. In this study, we stimulated cervical cancer cells with 5-aza-2'-deoxycytidine (5-Aza-dC) and found that this treatment inhibited cell proliferation and induced apoptosis; additionally, methylation of p16 and O-6-methylguanine-DNA methyltransferase (MGMT) was reversed, although their expression was suppressed. 5-Aza-dC inhibited E6 and E7 expression and up-regulated p53, p21, and Rb expression. Cells transfected with siRNAs targeting p16 and MGMT as well as cells stimulated with 5-Aza-dC were arrested in S phase, and the expression of p53, p21, and Rb was up-regulated more significantly. However, when cells were stimulated with 5-Aza-dC after transfection with siRNAs targeting p16 and MGMT, proliferation decreased significantly, and the percentage of cells in the sub-G1 peak and in S phase was significantly increased, suggesting a marked increase in apoptosis. But E6 and E7 overexpression could rescue the observed effects in proliferation. Furthermore, X-ray radiation caused cells to arrest in G2/M phase, but cells transfected with p16- and MGMT-targeted siRNAs followed by X-ray radiation exhibited a significant decrease in proliferation and were shifted toward the sub-G1 peak, also indicating enhanced apoptosis. In addition, the effects of 5-Aza-dC and X-ray radiation were most pronounced when MGMT expression was down-regulated. Therefore, down-regulation of p16 and MGMT expression enhances the anti-proliferative effects of 5-Aza-dC and X-ray radiation. This discovery may provide novel ideas for the treatment of cervical cancer.
宫颈癌是女性生殖系统最常见的恶性肿瘤之一。因此，研究宫颈癌发生发展的分子机制至关重要。在本研究中，我们用5-氮杂-2'-脱氧胞苷（5-Aza-dC）刺激宫颈癌细胞，发现该处理抑制细胞增殖并诱导凋亡；此外，p16和O-6-甲基鸟嘌呤-DNA甲基转移酶（MGMT）的甲基化被逆转，尽管它们的表达受到抑制。5-Aza-dC抑制E6和E7表达，并上调p53、p21和Rb表达。用靶向p16和MGMT的小干扰RNA（siRNA）转染的细胞以及用5-Aza-dC刺激的细胞停滞在S期，p53、p21和Rb的表达上调更显著。然而，在用靶向p16和MGMT的siRNA转染后用5-Aza-dC刺激细胞时，增殖显著降低，亚G1峰和S期细胞百分比显著增加，表明凋亡明显增加。但E6和E7过表达可挽救观察到的增殖效应。此外，X射线辐射使细胞停滞在G2/M期，但用靶向p16和MGMT的siRNA转染后再进行X射线辐射的细胞增殖显著降低，并向亚G1峰偏移，也表明凋亡增强。此外，当MGMT表达下调时，5-Aza-dC和X射线辐射的作用最为明显。因此，p16和MGMT表达下调增强了5-Aza-dC和X射线辐射的抗增殖作用。这一发现可能为宫颈癌的治疗提供新思路。
