Objective: To observe the methylation status of p16 tumor suppressor gene in human soft tissue leiomyosarcoma (LMS) and its relationship with p16 protein expression.
Methods: Methylation-specific PCR (MSP) assay was used to analyze the methylation status of 5' CpG island promoter/exon I region of p16 tumor suppressor gene in 38 LMS, 10 leiomyomas and 5 normal smooth muscle tissues. p16 expression in these tissues were examined by immunohistochemical assay.
Results: Hypermethylation of p16 was observed in 23.7% (9/38) of cases, of which 7 with negative pl6 staining and 2 with faint positive staining. In the cases without protein expression, hypermethylation rate of p16 was 50% (7/14).
Conclusions: Epigenetic change due to 5' CpG methylation is the main cause of inactivation of p16 (INK4) gene which may be involved in tumor pathogenesis.