Promoter methylation-mediated silencing of β-catenin enhances invasiveness of non-small cell lung cancer and predicts adverse prognosis.
β-Catenin plays dual role in adhesion complex formation and the Wnt signaling pathway. Although β-catenin expression appears to be upregulated and Wnt signaling pathway is activated in the majority of cancers, its expression level seems to be lost in non-small cell lung cancer (NSCLC). We previously reported that the promoter of β-catenin was hypermethylated in two NSCLC cell lines. In the current study, we expanded our analysis for the methylation status of β-catenin promoter region and its protein expression in seven NSCLC cell lines and a series of 143 cases of primary human lung cancer with adjacent non-neoplastic tissues. Quantitative methylation specific PCR (qMSP) analysis showed methylation of β-catenin promoter region in five NSCLC cell lines, with increased β-catenin protein levels upon 5'-Aza-2'-deoxycytidine (5-aza-dC) treatment. The methylation status in SPC (methylated) and A549 (unmethylated) was confirmed by bisulfite sequencing PCR. 5-Aza-dC treatment inhibited invasiveness of SPC but not A549. Immunofluorescence analysis showed membranous β-catenin expression was lost in SPC and could be re-established by 5-aza-dC, while Wnt3a treatment led to nuclear translocation of β-catenin in both SPC and A549. Dual-luciferase assays indicated that 5-aza-dC treatment caused no significant increase in Wnt signaling activity compared with Wnt3a treatment. The effect of demethylation agent in SPC can be reversed by β-catenin depletion but not E-cadherin depletion which indicated that the methylation mediated β-catenin silencing might enhance NSCLC invasion and metastasis in an E-cadherin independent manner. Subsequent immunohistochemistry results further confirmed that β-catenin promoter hypermethylation correlated with loss of immunoreactive protein expression, positive lymph node metastasis, high TNM stage and poor prognosis. The present study implicates β-catenin promoter hypermethylation in the mechanism of epigenetic changes underlying NSCLC metastasis and progression, thus indicating the potential of β-catenin as a novel epigenetic target for the treatment of NSCLC patients.
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Yuan
Y
Miao
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Liang
L
Wang
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Xiupeng
X
Zhang
96K Seven-year Program of Medicine, China Medical University, Shenyang, China.
Xiaohan
X
Xu
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Guiyang
G
Jiang
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Chuifeng
C
Fan
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Yang
Y
Liu
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Xuyong
X
Lin
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Juanhan
J
Yu
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Yong
Y
Zhang
Department of Pathology, The First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China.
Enhua
E
Wang
D000368:Aged; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D015820:Cadherins / Q000378:metabolism; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics*; D000077209:Decitabine; D005260:Female; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011379:Prognosis; D011401:Promoter Regions, Genetic; D060449:Wnt Signaling Pathway / Q000187:drug effects / Q000235:genetics; D051176:beta Catenin / Q000235:genetics* / Q000378:metabolism
D015820:Cadherins; D051176:beta Catenin; D000077209:Decitabine; D001374:Azacitidine