The Effect of Metformin on Triple-Negative Breast Cancer Cells and Nude Mice.

Triple-negative breast cancer (TNBC) presents the most adverse prognosis due to its pronounced invasive and metastatic features. Existing research has highlighted that metformin, a prevalent diabetes medication, possesses strong anti-tumor properties, particularly in inhibiting tumor invasion and metastasis. This study delves deeper into the impact of metformin on TNBC by examining changes in proliferation, apoptosis, invasion, migration, and adhesion of TNBC cells, specifically MDA-MB-231, post-metformin exposure. The treatment of MDA-MB-231 with metformin in immunodeficient nude mice led to discernible changes in tumor metrics such as size, weight, lymph node engagement, and angiogenesis. Post-treatment, MDA-MB-231 cells exhibited a marked decline in proliferation, invasion, migration, and adhesion, alongside a significant rise in apoptosis. In the in vivo model with nude mice, tumors displayed notable reductions in size and weight post-metformin exposure. Furthermore, there was a pronounced decline in lymph node plasma cell proliferation and tumor angiogenesis. Through the use of both Enzyme-Linked Immunosorbent Assay and Real-Time Fluorescence Quantification, it was ascertained that the expression of Signal Transducer and Activator of Transcription 3 (STAT3) saw significant augmentation, while expressions of Matrix Metallopeptidase-2 (MMP-2), Matrix Metallopeptidase-9 (MMP-9), Interleukin-6 (IL-6), and Interleukin-7 (IL-7) decreased markedly. This suggests metformin's potential efficacy against TNBC, potentially mediated via the STAT3 signaling pathway and interleukins 6 and 7.