Abstract:
Background and purpose: DNA methylation is a common epigenetic alteration in cervical carcinogenesis. The aim of this study was to measure the levels of LMX1A and PAX1 gene methylation in cervical cancer and precursors and to identify their potential in clinical application. Methods: Cervical specimens were collected from 121 female patients including 27 cases with invasive cervical cancers (ICC), 34 cases with high-grade cervical intraepithelial neoplasia (HG-CIN), 32 cases with low-grade cervical intraepithelial neoplasia (LG-CIN) and 28 cases with chronic cervicitis as normal controls (NLM). DNA methylations of the LMX1A and PAX1 gene were quantified using the techniques of nest PCR and pyrosequencing. The mean methylation values of the 6 gene loci on the LMX1A gene and the 9 gene loci on the PAX1 gene were respectively calculated for a given sample. Receiver operating characteristic (ROC) curve was used to evaluate the accuracy of gene methylation analysis to discriminate the cervical diseases. Results: The mean methylation value of the LMX1A gene in ICC was 14.36%, which was significantly higher than those in HG-CIN (4.70%), LG-CIN (5.05%) and NLM (4.53%) (P<0.01). The mean methylation value of the PAX1 gene in ICC was 41.97%, which was significantly higher than those in HG-CIN (10.21%), LG-CIN (5.55%) and NLM (4.92%) (P<0.01). The area under the ROC curve (AUC) was 0.603 for LMX1A gene methylation, and was 0.883 for PAX1 gene methylation, to discriminate ICC from HG-CIN, LGCIN, and NLM (P=0.104 and <0.001, respectively). The optimal cut-off value for PAX1 gene methylation was set at 20.50% with the sensitivity of 81% and with the specificity of 93%. If the cut-off value was set at 9.58%, the sensitivity and the specificity of PAX1 gene methylation were 89% and 84% respectively. Conclusion: Quantitative analysis of the PAX1 gene methylation in cervical tissue might be helpful to differentiate invasive cancers from precursors, while the clinical application of the LMX1A gene methylation was limited.

Key words: Cervical cancer, Cervical intraepithelial neoplasia, DNA methylation, LMX1A gene, PAX1 gene