Stearic acid-macrophage crosstalk identifies MIF-CD44 signaling as a therapeutic target in lung cancer initiation

Background: Lung cancer (LC) is the leading cause of cancer-related mortality, yet the process of tumor initiation is poorly understood. Prior work from our group indicated that biomolecules like stearic acid (SA) and proinflammatory cytokines like MIP1alpha and MIP1beta were selectively elevated in the tumor bearing lung lobes of early-stage LC patients. Hence, we hypothesized that a SA-macrophage (MΦ) inflammatory axis contributes to neoplastic transformation in lung epithelium. Method: Plasma cytokine profiles were compared between early-stage LC patients (n=5) and healthy controls (n=6). Cytokine production following SA exposure at transcriptional and translational level were assessed in PBMC-derived MΦs and human monocytic cell lines (U937) to establish synchrony between two systems. Conditioned media (CM) from SA-treated MΦs (SA-CM) was applied to BEAS2B epithelial cells (non-transformed lung epithelial cells), with transformation measured by soft agar and spheroid assays. Receptor expression for MIP1alpha (CCR5) and MIF (CD44) was quantified by mRNA/protein analyses. Functional blockades of CCR5 and CD44 were performed using small-molecule antagonists (Maraviroc and Verbascoside respectively) to identify critical cytokine driving transformation. Results: Elevated MIP1alpha were observed in plasma samples from early-stage LC patients compared to healthy individuals. SA treatment augmented MIP1alpha and MIF expression from both PBMC and U937 derived MΦs. Simultaneously, SA-CM from both PBMC and U937 derived MΦs induced significantly greater colony formation in soft agar matrix and robust spheroid growth under low-attachment conditions, indicating neoplastic transformation. Receptor analysis revealed abundant CD44 but limited CCR5 expression on BEAS2B cells. Blockade of CD44 with Verbascoside abrogated SA-CM-induced spheroid formation, whereas CCR5 inhibition had no effect. Conclusion: Based on these observations we conclude that SA reprograms MΦ transcriptional states promoting a MΦ driven proinflammatory environment that induces MIF-CD44-dependent neoplastic transformation of lung epithelial cells. These findings implicate a novel immunometabolic axis involved in the early oncogenic events of LC initiation and support therapeutic targeting of SA-MIF-CD44 signaling as a potential preventive strategy.