Targeting Triple-Negative Breast Cancer with Momordicine-I for Therapeutic Gain in Preclinical Models.

Background: TNBC patients respond poorly to chemotherapy, leading to high mortality rates and a worsening prognosis. Here, we investigated the effect of M-I on TNBC tumor growth suppression and its potential mechanisms. Methods: Signaling pathways were analyzed to study the effect of M-I on TNBC cells (human MDA-MB-231 and mouse 4T1). We used orthotopic mouse models to examine the anti-tumor efficacy of M-I. Tumor volume and the status of tumor-associated macrophages (TAMs) were assessed by qRT-PCR or FACS analysis. Results: We found a significant dose- and time-dependent inhibition of TNBC cell proliferation following treatment with M-I. Cell cycle analysis revealed a shortened S phase in M-I-treated cells and downregulation of AURKA, PLK1, CDC25c, CDK1, and cyclinB1. Furthermore, M-I treatment reduced the expression of pSTAT3, cyclinD1, and c-Myc in TNBC cells. To evaluate the anti-tumor efficacy of M-I, we employed orthotopic TNBC mouse models and observed a significant reduction in tumor growth without measurable toxicity. Next, we analyzed RNA from control and M-I-treated tumors to further assess the status of TAMs and observed a significant decrease in M2-like macrophages in the M-I-treated group. Immortalized bone marrow-derived mouse macrophages (iMacs) exposed to conditioned media (CM) of TNBC cells with or without M-I treatment indicated that the M-I treated CM of TNBC cells significantly reduce the M2phenotype in iMacs. Mechanistically, we found that M-I specifically targets the IL-4/MAPK signaling axis to reduce immunosuppressive M2 macrophage polarization. Conclusions: Our study reveals a novel mechanism by which M-I inhibits TNBC cell proliferation by regulating intracellular signaling and altering TAMs in the tumor microenvironment and highlights its potential as a promising candidate for TNBC therapy.