Transcripts of cytokeratins as predictors of breast cancer

Cytokeratins (CK) belong to a large family of intermediate filaments that are primarily expressed in epithelial cells and whose members are expressed in various combinations in normal and malignant entities. In breast cancer (BC), keratin typing is a major tool in tumor histodiagnosis, providing molecular parameters to assess its differentiation status. In our study, we evaluated CK5, CK6, CK8, CK14 and CK18 mRNA levels by qPCR, and CK18, CK5 and CK14 transcripts were effective to differentiate breast tumors from benign diseases. Relative quantification of CK18 mRNA levels was 2.08-fold higher in benign breast disease than in BC. The same expression pattern was observed for CK5 and CK14, which were 2.4 and 4.8-fold higher in nonmalignant tissues, and CK18 correlated with CK5, CK6, CK8 and CK14 mRNA expression. Cytokeratins 8/18 and 5/14 presented the same pattern according to molecular subtypes. However, CK18 itself correlated to clinical outcome in tumor phenotyping. We suggest that the mechanisms underlying the increased expression of cytokeratins in breast tumors may be similar, and CK18, CK5 and CK14 transcripts may be important in the tumorigenic process, distinguishing normal from tumor cells.