5' cytosine-phospho-guanine island methylation is responsible for p14ARF inactivation and inversely correlates with p53 overexpression in resected non-small cell lung cancer.
OBJECTIVE
The molecular mechanisms by which the p14ARF gene is altered in non-small cell lung cancer (NSCLC) are complex and unclear. Using genetic and epigenetic analyses, we examined various molecular alterations including the loss of protein and mRNA expression, and 5'CpG hypermethylation, allelic imbalance, and mutation of the p14ARF gene in a series of 102 NSCLC samples, in parallel with clinicopathological and prognostic analyses. To clarify the biological significance of p14ARF alterations, its relationship with p16INK4a and p53 alterations was also examined.


RESULTS
We found that 34% of NSCLC patients had aberrant P14ARF protein expression, which was more frequent in adenocarcinomas (AD; 44%) than in squamous cell carcinomas (22%; P = 0.024). A high concordance was observed between alterations in protein and mRNA expression and 5'CpG hypermethylation (P </= 0.001). The p14ARF hypermethylation inversely correlated with P53 overexpression (P = 0.001). This mutually exclusive relationship for alteration between p14ARF and p53 was also supported by a worse prognosis of AD patients with positive P14ARF expression (P = 0.01) and of AD patients with P53 overexpression (P = 0.006). Our data also indicated that hemizygous/homozygous deletion and mutation in the p14ARF gene occurred at 26%, 9%, and 0%, respectively, of microdissected NSCLCs.


CONCLUSIONS
Our data suggest that p14ARF 5'CpG hypermethylation is the predominant mechanism involved in the aberrant expression of the p14ARF gene. In addition, p14ARF 5'CpG hypermethylation occurs inversely to P53 overexpression.
Hsu
Han-Shui
HS
Division of Thoracic Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taipei.
Wang
Yu-Chien
YC
Tseng
Ruo-Chia
RC
Chang
Jer-Wei
JW
Chen
Jung-Ta
JT
Shih
Chuen-Ming
CM
Chen
Chih-Yi
CY
Wang
Yi-Ching
YC
D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D018899:CpG Islands / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006720:Homozygote; D006801:Humans; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009154:Mutation; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016019:Survival Analysis; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
D019941:Cyclin-Dependent Kinase Inhibitor p16; D012333:RNA, Messenger; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53