Triple-negative breast cancer is an aggressive subtype of breast cancer that lacks expression of estrogen receptor, progesterone receptor and HER2, which limits the availability of targeted therapies and contributes to poor clinical outcomes. Palbociclib, a cyclin-dependent kinase 4 and 6 inhibitor, has shown clinical efficacy in hormone receptor-positive breast cancer, but remains less effective in triple-negative breast cancer, where resistance frequently develops. Increasing evidence suggests that interactions within the tumor microenvironment contribute to therapeutic resistance. The present study investigated tumor-stromal communication in triple-negative breast cancer, focusing on the CD44/hyaluronan signaling axis, cancer-associated fibroblasts, and potential mechanisms associated with palbociclib resistance. Human MDA-MB-231 breast cancer cells and BJ-hTERT fibroblasts were used to model tumor–stromal interactions in vitro. Cancer-associated fibroblasts were generated by stimulation with transforming growth factor beta stimulation, and conditioned medium experiments were performed to evaluate paracrine signaling effects between fibroblasts and tumor cells. Protein expression was analyzed by Western blotting. Fibroblasts exposed to conditioned medium derived from tumor cells exhibited altered alpha-smooth muscle actin expression, indicating activation-associated changes. In addition, conditioned medium derived from fibroblasts increased CD44 expression in MDA-MB-231 cells, with differences depending on the source of conditioned medium and duration of exposure. Conditioned medium derived from palbociclib treated cancer cells also induced changes in fibroblast activation-associated protein expression, suggesting altered tumor-stromal communication under therapeutic stress.These findings suggest that stromal cell interactions may contribute to the regulation of CD44-associated signaling pathways in triple-negative breast cancer and potentially influence adaptive responses linked to therapeutic resistance. Further studies are required to clarify the molecular mechanisms underlying these interactions and their clinical relevance.