Methylation of p16 CpG Island And Malignant Transformation of Oral Epithelial Dysplasia

A Cohort Study on Prediction of Malignant Transformation of Oral Epithelial Dysplasia by p16 Methylation

Oral epithelial dysplasia (OED) is one of the common precancerous lesions among Chinese adults. Biomarker is not available for detection of malignant potential of OED till now. p16 is an important tumor suppressor gene, which is inactivated frequently by methylation of CpG island in early stage of carcinogenesis. The present cohort study is to investigate whether p16 methylation is correlated with malignant transformation of OED.

• Background: Identification of malignant potential of oral epithelial dysplasia (OED) is virtually impossible on histopathological grounds alone. Inactivation of p16 gene by CpG methylation is an early frequent event during oral carcinogenesis. To investigate the predictive value of p16 methylation on malignant potential in OED, we carried out the prospective cohort study.
• Methods: 101 patients with histologically confirmed mild or moderate OED were included in the present study. Baseline information of p16 methylation status of the OED lesions from 93 cases was obtained by methylation-specific PCR. Progression of the OEDs lesions was examined in 78 cases histologically during the 45.8 months double-blind followup survey (78/93). The association between p16 methylation and progression of OED was analyzed with SPSS13.0 software. All P-values were two-sided.

Inclusion Criteria:

• histological diagnosis of mild or moderate grade OED; and
• enough amount of tissue sample from OED lesion for genomic DNA extraction; and
• available of methylation status of p16 CpG island in the extracted DNA sample.

Exclusion Criteria:

• histological diagnosis of severe grade OED or malignant disease; or
• amount of tissue sample is not enough for preparation of genomic DNA (20ng); or
• quality of the prepared DNA is not good enough for detection of p16 methylation; or
• OED treatment history by LASER, radiotherapy, or chemotherapy