Tuberc Respir Dis.  2012 Jul;73(1):11-21. 10.4046/trd.2012.73.1.11.

Promoter Methylation of CDKN2A, RARbeta, and RASSF1A in Non-Small Cell Lung Carcinoma: Quantitative Evaluation Using Pyrosequencing

• Lee JU
• Sul HJ
• Son JW

• KMID: 2050670
• DOI: http://doi.org/10.4046/trd.2012.73.1.11

Abstract

BACKGROUND
While qualitative analysis of methylation has been reviewed, the quantitative analysis of methylation has rarely been studied. We evaluated the methylation status of CDKN2A, RARbeta, and RASSF1A promoter regions in non-small cell lung carcinomas (NSCLCs) by using pyrosequencing. Then, we evaluated the association between methylation at the promoter regions of these tumor suppressor genes and the clinicopathological parameters of the NSCLCs.
METHODS
We collected tumor tissues from a total of 53 patients with NSCLCs and analyzed the methylation level of the CDKN2A, RARbeta, and RASSF1A promoter regions by using pyrosequencing. In addition, we investigated the correlation between the hypermethylation of CDKN2A and the loss of p16INK4A immunoexpression.
RESULTS
Hypermethylation of CDKN2A, RARbeta, and RASSF1A promoter regions were 16 (30.2%), 22 (41.5%), and 21 tumors (39.6%), respectively. The incidence of hypermethylation at the CDKN2A promoter in the tumors was higher in undifferentiated large cell carcinomas than in other subtypes (p=0.002). Hyperrmethylation of CDKN2A was significantly associated with p16INK4A immunoexpression loss (p=0.045). With regard to the clinicopathological characteristics of NSCLC, certain histopathological subtypes were found to be strongly associated with the loss of p16INK4A immunoexpression (p=0.016). Squamous cell carcinoma and undifferentiated large cell carcinoma showed p16INK4A immunoexpression loss more frequently. The Kaplan-Meier survival curves analysis showed that methylation level and patient survival were barely related to one another.
CONCLUSION
We quantitatively analyzed the promoter methylation status by using pyrosequencing. We showed a significant correlation between CDKN2A hypermethylation and p16INK4A immunoexpression loss.

Keyword

DNA Methylation; Genes, p16; RASSF1 Protein, Human; Receptors, Retinoic Acid; Sequence Analysis, DNA; Carcinoma, Non-Small Cell Lung

MeSH Terms

Carcinoma, Large Cell
Carcinoma, Non-Small-Cell Lung
Carcinoma, Squamous Cell
DNA Methylation
Evaluation Studies as Topic
Genes, p16
Genes, Tumor Suppressor
Humans
Incidence
Kaplan-Meier Estimate
Lung
Methylation
Promoter Regions, Genetic
Receptors, Retinoic Acid
Sequence Analysis, DNA
Tumor Suppressor Proteins
Receptors, Retinoic Acid
Tumor Suppressor Proteins