Association between inflammation and cancer stem cell phenotype in breast cancer

Inflammation and cancer stem cells (CSCs) are becoming increasingly recognized as components of tumorigenesis in breast cancer. In the present study, the association between inflammation and BCSC phenotype was evaluated in human breast cancer tissue. Immunohistochemical staining for cluster of differentiation (CD)24, 44, 4, 8 and 68 was performed using tissue microarray blocks containing 47 consecutive cases of invasive breast carcinoma and 10 normal breast tissue samples. The levels of inflammatory modulators and cytokines, and intratumoral or peritumoral lymphocyte infiltration, were assessed. BCSCs were defined as CD44⁺/CD24^- tumor cells. In total, 21.3% of samples exhibited the CD44⁺/CD24^- phenotype. This phenotype was identified to be significantly inversely associated with lymph node metastasis. In addition, the CD44⁺/CD24^- phenotype was significantly associated with the molecular subtype of breast cancer, and was particularly increased in the basal-like subtype. Furthermore, the CD44⁺/CD24^- phenotype was significantly associated with intratumoral inflammation and tumor-infiltrating CD4⁺ T cell counts. Notably, tumor-infiltrating CD4⁺ T cells were significantly increased in patients with the basal-like molecular subtype of breast cancer. In conclusion, the present study identified a significant association between inflammation and the CD44⁺/CD24^- phenotype in breast cancer. These results suggest that the interaction between inflammation and CSCs may affect the tumorigenesis and progression of breast cancer. Further studies are required to clarify the role of inflammation and CSCs in breast cancer.