Expression of DNA methylation-related proteins in invasive lobular carcinoma of breast: comparison to invasive ductal carcinoma.

PURPOSE

We aimed to compare the expression of DNA methylation-related proteins in invasive lobular carcinoma (ILC) of breast with those of invasive ductal carcinoma (IDC) of breast and to assess its potential clinical application.

METHODS

Immunohistochemical staining of DNS methylation-related proteins (5-meC, DNMT1, DNMT3B and ISL-1) was applied to tissue microarrays generated from 108 ILCs and 203 IDCs. Protein expression and its correlation with clinicopatholgic variables were statistically analyzed.

RESULTS

ISL-1 and DNMT3B were highly expressed in ILC (p<0.001) and tumoral 5-meC was highly expressed in IDC (p=0.006). DNMT1 (p<0.001) showed higher expression rate in luminal A type ILC. ISL-1 and DNMT3B showed higher expression rate in both luminal A type and luminal B type of ILC (p<0.05). In IDC, tumoral 5-meC commonly showed high positive (p=0.039). On univariate analysis, shorter disease free survival of ILC was associated with DNMT1 high positivity (p=0.001) and ISL-1 positivity (p=0.018).

CONCLUSION

DNA methylation-related proteins are differentially expressed in ILC and IDC, and DNMT1, DNMT3B and ISL-1 show high expression rate in ILC.