WNT pathway in oral cancer: epigenetic inactivation of WNT-inhibitors.
Epigenetic DNA methylations plays an important role in oral carcinogenesis. The soluble frizzled receptor protein (SFRP) family together with WIF-1 and DKK-3 encodes antagonists of the WNT pathway. Silencing of these genes leads to constitutive WNT signalling. Because aberrant expression of beta-catenin might be associated with the epigenetic inactivation of WNT inhibitors, we analyzed, in a collection of primary OSCC with matched normal oral mucosa, the methylation status of a complete panel of genes, SFRP-1, SFRP-2, SFRP-4, SFRP-5, WIF-1, DKK-3, that are involved directly and indirectly in WNT pathway, in order to demonstrate WNT-pathway activation in the absence of beta-catenin and/or APC/Axin mutations during oral carcinogenesis. Methylation-specific PCR (MSP) was performed to study inactivation of SFRP-1, SFRP-2, SFRP-4, SFRP-5, WIF-1, DKK-3 genes in 37 cases of paraffin embedded oral cancer. This study showed that the methylation is an important epigenetic alteration in oral cancer. In particular, SFRP-2, SFRP-4, SFRP-5, WIF-1, DKK-3 revealed methylation status of their promoter in OSCC, whereas SFRP-1 showed demethylation in cancer. Fisher's exact test revealed statistically significant results (p<0.05) for all genes. The Wald test confirmed the statistically significant association between SFRP2-4-5 gene methylation and OSCC (p<0.05). SFRP-1 was also characterized by a different statistically significant epigenetic behaviour, because of it was demethylated in cancer (p<0.05). Statistical regression test showed high levels of sensitivity, specificity and accuracy for SFRP genes, while WIF-1 and DKK-3 have reportedly high specificity, moderate accuracy but low sensitivity. This study suggests that a cause of catenin delocalization in oral cancer could be due to WNT pathway activation, by epigenetic alterations of SFRP, WIF-1 and DKK-3 genes.
Pannone
G
G
Department of Surgical Sciences, Section of Anatomic Pathology and Cytopathology, University of Foggia, Foggia, Italy.
Bufo
P
P
Santoro
A
A
Franco
R
R
Aquino
G
G
Longo
F
F
Botti
G
G
Serpico
R
R
Cafarelli
B
B
Abbruzzese
A
A
Caraglia
M
M
Papagerakis
S
S
Lo Muzio
L
L
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism; D018925:Chemokines; D019175:DNA Methylation / Q000235:genetics*; D044127:Epigenesis, Genetic; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D012372:ROC Curve; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity; D015398:Signal Transduction / Q000235:genetics*; D051153:Wnt Proteins / Q000235:genetics* / Q000378:metabolism; D000094742:Secreted Frizzled-Related Proteins
D048868:Adaptor Proteins, Signal Transducing; D014408:Biomarkers, Tumor; D018925:Chemokines; D005136:Eye Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D051153:Wnt Proteins; C498624:DKK3 protein, human; C117636:SFRP1 protein, human; D000094742:Secreted Frizzled-Related Proteins; C109618:SFRP2 protein, human; C118723:SFRP4 protein, human; C118511:SFRP5 protein, human; C485569:WIF1 protein, human