Correlation between methylation of the p16 promoter and cervical cancer incidence

F.-L. Wang, Y. Yang, Z.-Y. Liu, Y. Qin, T. Jin

Department of Obstetrics, the Affiliated Hospital of Jining Medical University, Jining, Shandong Province, P.R. China. js22ie@163.com

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• Oncology

OBJECTIVE: To study the methylation of the promoter of the p16 gene in cervical cancer patients and explore the correlation between methylation and the incidence of cervical cancer.

PATIENTS AND METHODS: We recruited 78 patients with cervical cancer and 48 healthy individuals. The methylation-specific PCR was used to detect the methylation status in the promoter of the p16 gene. The mRNA expression of p16 was studied by quantitative fluorescence PCR. The protein expression of p16 was monitored by Enzyme-linked immunosorbent assay (ELISA) and Western blot. Immunohistochemistry was applied to detect the expression and distribution of p16 in cervical tissues.

RESULTS: The methylation sequencing results showed that samples from cervical cancer patients had a methylation rate of 78.52% in the p16 gene promoter region compared with a much lower rate of 9.8% in the control group (9.8%). Quantitative fluorescence PCR indicated that the p16 mRNA expression was significantly reduced in cervical cancer patients compared with controls. ELISA and Western blot results showed that expression of the p16 protein in cancer tissue was 0.81 ± 0.12 µg/l, whereas in the healthy controls it was 3.21 ± 0.24 µg/l. Immunohistochemical results showed that the p16 protein was mainly present in the cytoplasm. The rate of p16 positive cells in the healthy cervical tissue 83.29% was higher than in cervical cancer 10.18%.

^{CONCLUSIONS: The methylation of the p16 gene promoter could significantly reduce p16 expression, losing its tumor suppressor activity and promoting the development of cervical cancer.}

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