Lung Cancer Cells Secrete Glutamine to Accumulate Tumor-Associated Macrophages.

Tumor-associated macrophages (TAMs) are critical contributors to cancer progression and are often recruited by cancer cells to support a pro-tumorigenic microenvironment. Integrin αvβ3 is a known driver and marker of cancer stem-like properties, including tumor initiation, in various epithelial cancers. We have previously shown a positive correlation between αvβ3 expression and TAM infiltration across multiple tumor types; however, the mechanistic link remains undefined. Here, we demonstrated that integrin αvβ3 expression in non-small cell lung cancer (NSCLC) cells is both necessary and sufficient to drive TAM accumulation. In orthotopic murine and human NSCLC models, ectopic integrin αvβ3 expression increased TAM infiltration independently of T cells, whereas genetic deletion of integrin β3 significantly reduced TAM numbers and tumor burden. Mechanistically, integrin αvβ3 promotes glutamine secretion from NSCLC cells, which enhances the survival and/or differentiation of bone marrow-derived macrophages. Functionally, TAMs are essential for the elevated tumor-initiating capacity of αvβ3+ cancer cells, as macrophage depletion abolished this effect. Together, our findings uncover a novel mechanism by which NSCLC cells remodel the tumor microenvironment via αvβ3-mediated glutamine secretion, promoting TAM enrichment and tumor initiation. Targeting this axis may offer therapeutic benefits in αvβ3-expressing cancers.