The formation of lung tumors by these chemicals involved mutations in the K-ras cancer gene and loss of heterozygosity in the region of K-ras on distal chromosome 6, while alterations in p53 and p16 were implicated in brain tumorigenesis.
In order to explore the possibility of a selective deregulation of p15(INK4b) in human lung carcinogenesis, we studied p15(INK4b) status in neuroendocrine (NE) lung tumours where homozygous deletions of the p16(INK4a)/p14(ARF) locus are rarely observed.
To further explore the molecular mechanisms between altered TSGs promoter methylation and overexpression of DNMTs protein, we performed a tissue chromatin-immunoprecipitation polymerase chain reaction assay for lung tumors and showed that the methylated FHIT, p16(INK4a) and RARbeta promoters were bound by both DNMT protein and methyl-CpG-binding protein 2.
Methylation of the p16 and ER genes was very common (80 and 50%, respectively) in beryllium-induced lung tumors; both genes were methylated in 40% of the tumors.
Secondly, genetic resistance to lung tumor formation appears to segregate with one particular haplotype, which also is deleted preferentially in lung adenocarcinomas of Cdkn2a heterozygous mice.
Aberrant methylation of the CDKN2a/p16INK4a gene promoter region in preinvasive bronchial lesions: a prospective study in high-risk patients without invasive cancer.
The p14ARF transcript, which is an alternative spliced form of this locus, is also altered or deleted in a proportion of human lung cancers and has been shown to inhibit cell cycle progression as an endogenous cellular regulator of the p53 protein, raising the possibility that it might constitute an additional lung tumor suppressor gene at the 9p21 locus.
Here, we applied methylation-specific polymerase chain reaction to compare the frequencies of the methylated promoter of p16 and O6-methylguanine-DNA methyltransferase (MGMT) genes in lung tumors from 122 patients with non-small cell lung cancer, including 81 smokers and 41 never-smokers.
To conclude, systemic p16 peptide administration decreased lung tumor development in a mouse metastatic BT model without severe adverse events, as assessed by blood analyses and histological evaluation.
Our analyses revealed a high frequency of aberrant hypermethylation of MTHFR, RASSF1A, and CDKN2A in lung tumors as compared with control blood samples, whereas no significant increase in methylation levels of GSTP1 and CDH1 was observed, consistent with the notion that aberrant DNA methylation occurs in a tumor-specific and gene-specific manner.
<b>Patients & methods:</b> Lung tumor tissue microarray (n = 163), immunohistochemical study of p16 and p53, and HPV <i>in-situ</i> hybridization were analyzed.
The Contrasting Role of p16Ink4A Patterns of Expression in Neuroendocrine and Non-Neuroendocrine Lung Tumors: A Comprehensive Analysis with Clinicopathologic and Molecular Correlations.
We examined the tumor and the matched BAL DNA for aberrant methylation of eight gene promoters (CDH1, APC, MGMT, RASSF1A, GSTP1, p16, RAR-beta 2, and ARF) from 31 patients with primary lung tumors by quantitative fluorogenic real-time PCR.
Based on the concordance of biomarkers in lung tumours and corresponding sputum, and the low prevalence in cancer-free individuals, we selected seven markers for a nested case-control study: microsatellite instability of D9S942; loss of heterozygosity of D9S286, D9S942, GATA49D12, and D13S170; and methylation of p16INK4a and RARbeta.
Methylation of the p16 and ER genes was very common (80 and 50%, respectively) in beryllium-induced lung tumors; both genes were methylated in 40% of the tumors.