In Vitro Effects of Extracellular Vesicles from Adipose Tissue-Derived Stem Cells on the Growth and Metastasis of Cultured Breast Cancer Cells via Downregulation of Interleukin-6 Expression and the Microtubule Network.

Breast cancer remains the most common malignancy worldwide and the leading cause of cancer-related mortality. Recently, extracellular vesicles (EVs) derived from adipose tissue-derived stem cells (ADSCs) have attracted increasing attention for their potential to modulate inflammatory signaling and influence tumor cell behavior. This in vitro study was designed to investigate the effects of ADSC-EVs on MCF-7 breast cancer cells. EVs were isolated from ADSC culture supernatants and applied to MCF-7 cells at concentrations ranging from 0 to 80% (v/v). Cell viability, migration, and expression of IL-6/STAT3 pathway-related genes were evaluated using MTT, scratch assays, and qRT-PCR. Statistical analysis was performed using one-way ANOVA followed by Tukey's post hoc test, with significance set at p < 0.05. The results showed that 20% EV treatment markedly inhibited MCF-7 cell activity, significantly reducing viability and almost completely blocking migration, with wound closure rates of 35.4% ± 3.80 at 24 h and 47.6% ± 4.2 at 48 h, compared with 48% ± 4.6 and 67% ± 4.2 in the control group, respectively. Notably, expression levels of IL-6, IL-6RST, and STAT3 were significantly downregulated (fold changes 0.155 ± 0.02 and 0.258 ± 0.012, p < 0.01), accompanied by severe disruption of the microtubule network. Immunofluorescence imaging revealed a disorganized microtubule architecture and irregular filament distribution in EV-treated cells, corresponding with decreased expression of TubA1 and CALR genes. These findings indicate that ADSC-EVs not only suppress IL-6/STAT3 inflammatory signaling but also destabilize the intracellular microtubule system, collectively contributing to the inhibition of MCF-7 breast cancer cell migration and survival. This provides an important molecular basis for developing novel EV-based therapeutic strategies in breast cancer treatment.