| Summary: | 碩士 === 國立中興大學 === 生命科學系 === 93 === The cadherins are a family of cell surface glycoproteins respon- sible for cell adhesion, play an important role in cell morphology, contact inhibition and signal transduction during tumorgenesis. In our previous study, the PCDH21 hypermethylation was first found and identified in sporadic breast tumorsby using CpG islands microarray and methylation tissue amplicon array. In this study, we examined the methylation status of the PCDH21 promoter in breast cancers and breast cancer cell lines using methylation-specific PCR. Hypermethyl-
ation of the PCDH21 in promoter and exon1 regions were high frequentl
-y detected inTaiwan sporadic breast cancers with 92%(67/73) and 86(63/73),respectively. PCDH21 promoter aberrant methylation was dete-
cted in 3 breast cancer cell lines, incliding MCF7, T47D,MDA468 and
MDA231, with 100%.The highly aberrant methylation of PCDH21 in the breast cancer cells may imply its association with tumorigenesis. Thus, we further analyzed the function of PCDH21 in breaset cancer cell lines. Firstly, we evaluated the mRNA levels of PCDH21 in 3 breast cancer cell lines, including MCF7, T47D and MDA231, which represent different grade of malignancy. The lowest PCDH21 mRNA expression was observed in high metastasis MDA231, but the highest PCDH21 mRNA expression in low metastasis MCF7. The transcription regulation of the PCDH21 was demonstrated that directly controlled by DNA methylation modification using 5-Aza-dC demethylation agent treatment in MDA231 breast cancer cell line. In addition, overexp-
ression of PCDH21 in MDA231 caused morphological changes that cells was switched from fibroblast into epithelial-like cells. The results of wound healing assay and cell growth rates assay both indicated that metastasis and proliferation of MDA231 were suppressed in the PCDH21-overexpression MDA231. Overexpression of PCDH21 in highly
metastasis MDA231 would inducer morphologicalchanges, decrease cell migration ability and growth rate suggested that PCDH21 function as a potential tumor suppressor gene in breast cancer cell lines.
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