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[Promoter methylation status and protein expression of p14ARF gene in squamous cell carcinoma and adenocarcinoma of the lung].

BACKGROUND
Recently, the p14 ARF gene has emerged as a new putative tumor suppressor gene, and the alteration of p14 ARF gene is closely related to development of multiple human tumors. The aberrant promoter methylation as a mechanism of inactivation of p14 ARF gene might participate in tumorigenesis. The aim of this study is to investigate promoter methylation status and protein expression of p14 ARF gene in pulmonary squamous cell carcinoma and adenocarcinoma, and to value the role of p14 ARF promoter methylation in carcinogenesis of non-small cell lung cancer.


METHODS
Promoter methylation status and protein expression of p14 ARF gene were analyzed in 40 cases of pulmonary squamous cell carcinoma and adenocarcinoma by methylation specific polymerase chain reaction (MSP), restriction enzyme-related polymerase chain reaction (RE-PCR) and immunohistochemistry (IHC).


RESULTS
The positive rate of p14 ARF promoter methylation in tumor tissues and normal tissues adjacent to cancer was 17.5% (7/40) and 2.5% (1/40) respectively (P= 0.025 ). The results of RE-PCR were consistent with the above. The positive rate of p14 ARF protein in tumor tissues was significantly lower than that in normal tissues adjacent to cancer (P=0.003). Promoter methylation and protein expression of p14 ARF gene showed a significantly negative correlation (r=-0.56, P= 0.001 ), and both of them did not correlate statistically with the clinicopathologic characteristics of patients such as histological classification, TNM stages, differentiation grade and lymph node involvement.


CONCLUSIONS
Promoter methylation is a crucial mechanism of inactivation of p14 ARF gene. Promoter methylation of p14 ARF gene might be involved in carcinogenesis of non-small cell lung cancer, and it is an early event in development process of non-small cell lung cancer.