Update on the molecular profile of the MDA-MB-453 cell line as a model for apocrine breast carcinoma studies.

Apocrine carcinoma of the breast has recently been refined through gene expression profiling. Due to various pathological studies, we compared the results with the MDA-MB-453 breast cancer cell line, a proposed model for apocrine breast carcinoma. The MDA-MB-453 cell line is androgen receptor-positive and `triple-negative' in respect to estrogen receptor-α, progesterone receptor and the Her-2/neu protein expression. Cytogenetic analysis of the cell line revealed a hypertriploid clone characterized by extensive numerical and structural abnormalities including loss of the 9p.21 locus (P16-INK4a gene), also evidenced by the lack of p16(INK4A) protein expression in Western blot analysis and immunocytochemistry assays. Gains of chromosomes 7 and 17 without underlying EGFR, HER-2/neu, and TOP2A gene amplification were also observed. A mutation in the K-RAS gene (Gly13Asp GGC>GAC) was identified in the cell line, which was not observed in the six patient samples of apocrine breast carcinomas examined. Similarly, constitutive activation of the MAPK/ERK signaling pathway and deregulation of cell cycle proteins (p16-/pRb-/cyclin D1+ phenotype) with exceedingly high proliferation observed in the MDA-MB-453 cell line were not found in the tissue samples. In conclusion, the MDA-MB-453 cell line shares certain features with apocrine breast carcinoma but differs from patient tissues with regard to various significant characteristics, limiting the value of this cell line as a model for human apocrine breast carcinoma investigations. In contrast to the cell line, EGFR-positive apocrine carcinomas do not harbor K-RAS gene mutations, rendering these tumors amenable to targeted therapy with EGFR inhibitors.