[Methylation and aberrant expression of the p16 gene in cervical carcinoma].

To detect hypermethylation and aberrant expression of the p16 gene in cervical carcinoma (CC), methylation-specific PCR (MSP) was used to determine the methylation status of 5'CpG islands of the p16 gene, loss or decrease of p16 expression was analyzed by immunohistochemistry (IHC), and homozygous deletion of exon 1 (E(1)) and/or exon 2 (E(2)) was determined by PCR. in 60 cases of CC at different pathological grades and clinical stages. The results showed absence of methylation and presence of normal expression of the p16 gene in the control and adjacent tissues of CC. Hypermethylation, loss or decrease of expression and deletion of the p16 gene were detected in 21.67%(13/60), 51.67%(31/60) and 15.00%(9/60) of the tumor tissues, respectively. The rate of p16 expression markedly reduced with the increase of clinical stages. Our data suggested that inactivation of the p16 gene was a frequent event and positively correlated with pathological grades in CC, and that methylation of the p16 gene was an important event in carcinogenesis of CC.

[Significance of methylation and abnormal expression of p16 gene in endometrial carcinoma].

The tumor suppressor gene p16, located on chromosome 9p21, encodes the cell cycle regulatory protein, p16. Inactivation of the p16 gene could lead to uncontrolled cell growth. It was examined that methylation of the p16 gene 5'CpG island of the tumor suppressor gene may be an important mechanism for transcriptional inactivation. In order to determine the role of methylation status of the 5'CpG island and abnormal expression of incarcinogenesis of endometrial carcinoma (EC), Methylation-Specific PCR (MSP) was used to determine the methylation status of p16 gene 5'CpG islands of 62 cases of EC. Loss or decrease of p16 expression was analyzed by immunohistochemistry (IHC) and homozygous deletion of exon1 (E1) and exon2 (E2) was determined by complex PCR. Ten specimens of normal tissues and adjacent tissues of tumor displayed no methylation and showed normal expression of p16. In E1 and E2 of the 62 EC, we found that 24.2% (15/62) were methylated, 54.8% (33/62) lost or reduced p16 expression, 16.1% (10/62) and 30.6% (19/62) had deletions of E1 and E2 respectively. There were 9.68% (6/62) and 46.6% (29/62) deletions of both or either of E1 and E2 respectively. Inactivation of p16 gene is a frequent event and positively correlated with pathological grades and clinical stages in EC. p16 gene methylation was an important event in the development of EC. MSP is an accurate and relatively simple method for evaluating the methylation status of a related gene.