Abstract
Background. Breast cancer progression is influenced not only by malignant cells but also by the tumor microenvironment. Fibroblasts, as important stromal components, regulate cancer cell behavior through paracrine signaling. Although cancer-associated fibroblasts are generally linked to tumor progression, the role of normal fibroblasts remains unclear. This study investigated the effects of conditioned medium derived from human normal fibroblasts on stemness characteristics in luminal and basal breast cancer cell lines.
Methods. MCF-7 (luminal) and MDA-MB-231 (basal) breast cancer cells were cultured for 7 days in conditioned medium obtained from human foreskin fibroblasts (HFF2). Stemness-related markers, including OCT4, SOX2, NANOG, ALDH1, and CD44+/CD24−, were evaluated using real-time PCR, Western blotting, and flow cytometry. Additionally, mammosphere formation, morphological analysis, and scratch wound-healing assays were performed to assess self-renewal ability and invasive potential.
Results. Treatment with fibroblast-conditioned medium significantly reduced the expression of OCT4, SOX2, NANOG, and ALDH1 in both cell lines, especially in the basal subtype. The size and number of mammospheres decreased in MCF-7 cells, while MDA-MB-231 cells formed smaller but more numerous mammospheres. Morphological analysis showed a shift toward a more epithelial phenotype, and scratch assays demonstrated reduced migration and invasion. The CD44+/CD24− population increased, which is likely related to selective survival under stress conditions.
Conclusion. The findings suggest that normal fibroblasts can suppress stemness and invasive properties of breast cancer cells through paracrine mechanisms. These results highlight the potential therapeutic importance of targeting stromal interactions and fibroblast-mediated pathways in the treatment of breast cancer.
Practical Implications. These findings highlight the potential of targeting the tumor microenvironment, particularly fibroblasts, as a novel therapeutic strategy in breast cancer.