DNA methylation and carcinogenesis of PRDM5 in cervical cancer

Abstract

Objective: PR (PRDI-BF1 and RIZ) domain proteins (PRDM) are a subfamily of the kruppel-like zinc finger gene products and play key roles during cell differentiation and malignant transformation. PRDM5 (PR domain containing 5 PFM2) is a new PR-domain-containing gene. The purpose of the present study was to examine the expression of PRDM5 and evaluate its carcinogenesis in cervical cancer. The relationship between DNA methylation and transcriptional silencing of PRDM5 was investigated in cervical cancer.

Methods: PRDM5 expression was examined in cervical cancer cell lines and cervical tissues (12 normal and 42 cancerous) by using RT polymerase chain reaction (PCR). Methylation status of the PRDM5 promoter was studied using methylation-specific PCR (MSP).

Results: PRDM5 expression is reduced or lost in cervical cancers, compared with normal cervical tissues (P < 0.05). The current study results also showed that loss of PRDM5 is mediated by aberrant cytosine methylation of the PRDM5 promoter. There were 40.5% of carcinomas methylated, while none of normal tissues were methylated. PRDM5 mRNA expression was significantly higher (P = 0.000) in unmethylated (0.2634 ± 0.0674, mean ± SD), compared with methylated tissues (0.1007 ± 0.0993, mean ± SD). Last, treatment with a DNA methyltransferase inhibitor led to reactivation of PRDM5 expression in cell lines that had negligible PRDM5 expression at baseline.

Conclusions: Reduced expression of PRDM5 may play an important role in the pathogenesis and/or development of cervical cancer, and is considered to be caused in part by aberrant DNA methylation.

Fig. 1

a PRDM5 mRNA in cervical cancer cell lines relative to normal tissues (n = 12). PRDM5 mRNA expression was absent in two of four cervical cancer cell lines. b PRDM5 mRNA expression in normal tissues (N) and match tumor tissues (T). PRDM5 mRNA expression in cervical cancer tissues was reduced or lost. c Reactivation of PRDM5 expression by inhibitor of DNA methylation in SiHa cells

Fig. 2

a Methylation-specific PCR analysis of various cervical cancer cell lines and all of primary tumors and normal tissues. Bisulfite-treated DNA was used as a template for methylation-specific PCR by using previously described primers. M primers specific to methylated template DNA, U primers specific to unmethylated template DNA, T tumor, N normal. b Methylation status of SiHa cell line before and after treatment with the DNA methyltransferase-inhibiting agent, 5-aza-dC