Metadherin with Stromal-Immune Cues Drives CD36-Dependent Lipid Reprogramming and Metastasis in Triple-Negative Breast Cancer: Insights from a Hetero-Spheroid Model.

Abstract

Triple-negative breast cancer (TNBC) exhibits altered lipid metabolism, driven by the tumor microenvironment's cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). CD36, a fatty acid translocase, is crucial in this metabolic adaptation of cancer cells. Despite its importance, what controls CD36-mediated lipid flow is still unclear. This study identifies metadherin (MTDH), an oncogene, as a critical regulator of CD36-dependent lipid exchange and TNBC progression. Using engineered spheroid models that mimic tumor microenvironment with MTDH-Wt and MTDHΔ7 overexpressing TNBC cells co-cultured with CAFs and TAMs, we observed increased lipid uptake, enhanced EMT, and aggressive metastatic features driven by MTDH-CD36 signaling. Further analyses, including advanced microscopy and transcriptomics, revealed that MTDHΔ7 overexpression in TNBC cells in the presence of stromal-immune cells, amplifies lipid metabolic pathways, promotes stemness, and pro-metastatic signaling. Intriguingly, increased formation of tunnelling nanotube-like structures, indicative of metabolic rewiring, was observed in Lv.MTDHΔ7-MDA-MB-231^CAF-TAM heterotypic spheroids. These changes were reversed by sulfosuccinimidyl oleate (SSO; CD-36 inhibitor) treatment. Moreover, SCID mice bearing Lv.MTDH-Wt/Δ7-MDA-MB-231cells^CAF-TAM heterotypic spheroids led to accelerated breast tumor growth and lipid-driven metastasis. Importantly, SSO administration significantly reduced lipid accumulation and tumor aggressiveness, confirming CD36 as a functional mediator of MTDH-driven lipid reprogramming. Our findings establish MTDH as a master regulator of lipid reprogramming through CD36, a process further amplified by CAF-TAM interactions, which creates a lipid-rich tumor microenvironment fuelling TNBC aggressiveness. This study reveals crucial mechanistic insights into how stromal-immune cells induce lipid symbiosis and highlights the MTDH-CD36 axis as a promising therapeutic target for future combination therapies in aggressive, metabolically reprogrammed TNBC.