CD44(+)/CD24(-) cells are transit progenitors and do not determine the molecular subtypes and clinical parameters in breast carcinomas

CD44(+)/CD24(-) cells have been associated with breast cancer stem/progenitor cell features. However, the status of this phenotype cells in normal, benign and malignant breast tissues has not been studied, and the clinical correlation of this subpopulation in breast cancer is not fully understood. The present study sought to identify these cells in a series of normal, benign, and malignant breast tissues and explore their correlation to the molecular subtypes of breast carcinoma and conventional pathological features. Double-staining immunohistochemistry (DIHC) of CD44 and CD24 was performed on 30 normal breast tissues, 30 breast fibroadenomas (FA), 60 breast invasive ductal carcinomas (IDC), and 3 breast cancer cell lines (MCF-7, MDA-MB-468, and MDA-MB-231). In the normal breast tissues and FAs, three phenotypes were observed including CD44(+)/CD24(+), CD44(+)/CD24(-), and CD44(-)/CD24(-) cells. In the IDCs, CD44(-)/CD24(+) cells were detected, in addition to the three aforementioned phenotypes. The strong positive rate (+++, incidence >60%) of CD44(+)/CD24(-) was significantly increased from normal breast tissue, FAs to IDCs (0.0%-->6.7%-->21.7%). However, the CD44(+)/CD24(-) cells didn't correlate with ages of patients, lymph node metastasis, tumor size, molecular subtypes, and the expression of ER, PR, HER-2, PS2, Bcl-2, nm23. The proportion of CD44(+)/CD24(-) cells in MCF-7, MDA-MB-468, and MDA-MB-231 was about 1, 5, and 80%, respectively. The results indicate that the CD44(+)/CD24(-) cells are transit progenitors and have no association with the molecular subtypes and clinicopathological parameters in the IDCs.