Evaluating the Efficacy of Polyphenol‐Enriched Plant Extracts and Pathway Modulators in the Bone Marrow to Suppress Breast Cancer Progression

Disseminated tumor cells (DTCs) in the bone marrow can survive in a dormant state and later reawaken to drive metastatic relapse. Hypoxia-driven angiogenic signaling (HIF-1α → VEGF), matrix remodeling (MMP-2), and inflammation (COX-2, TNF-α) are central determinants of niche permissiveness for colonization. We investigated whether rational combinations of selected plant extracts with pathway-targeting small molecules can reprogram the bone marrow microenvironment, suppress pro-metastatic signaling, and limit tumor progression by promoting dormancy-like states. Complementary in vitro and in vivo experiments were performed. Human breast cancer cell lines (MDA-MB-231, MCF-7) were exposed to defined plant extracts and to modulators of nitric-oxide/arginase signaling; endpoints included HIF-1α, COX-2, and MMP-2 expression (Western blot, immunocytochemistry), and migration/invasion (real-time assays). LC-HRMS profiled extract composition. In vivo efficacy was tested in a DMBA-induced rat breast cancer model with systemic administration of extracts alone and in combination with small-molecule modulators; bone-marrow biomarkers (VEGF-α, TNF-α, IL-2, MMP-2, COX-2) were quantified by ELISA, bone-marrow cells by histology, and tumor burden and survival were recorded. Plant extract treatments attenuated HIF-1α, COX-2, and MMP-2 in cancer cells and markedly reduced TNF-α-driven migration and invasion in vitro. LC-HRMS identified a reproducible polyphenol-rich fingerprint across active fractions. In vivo, combined therapies produced consistent decreases in bone-marrow VEGF-α, MMP-2, and COX-2 and a concomitant increase in IL-2; these biochemical changes correlated with substantially reduced tumor size, lower incidence of progressive disease, and improved survival compared with controls. Differential responses were observed depending on the small-molecule companion (e.g., L-NAME versus arginase inhibition), indicating pathway-specific modulation of the niche. Histopathology confirmed reduced marrow atypia and diminished tumor infiltration in responding groups. Our integrated dataset supports a model in which coordinated suppression of hypoxia/angiogenesis, matrix remodeling, and inflammatory signaling in the bone-marrow niche-achieved by combining plant extracts with targeted modulators-constrains metastatic progression, plausibly by enforcing or sustaining dormancy of disseminated tumor cells. These findings identify testable mechanistic nodes (HIF-1α, VEGF, MMP-2, COX-2) for follow-up causal studies and support further fractionation and translational evaluation of active phytochemicals as adjuncts to niche-targeted anti-metastatic strategies.