Health behavior associated CCL20 ligand variation contributes to the disparity in non-small cell lung cancer

Background: Lung cancer exhibits disparities in incidence, disease prevalence, and treatment outcomes. Chemokines and their corresponding receptors have been shown to be associated with these observed disparities within different ethnic groups. In this study, we have demonstrated that the differential signaling of chemokine receptor CCR6 and its natural ligand is associated with the observed disparity, and this differential CCR6 signaling is primarily due to the diversity in CCL20. Methods: Bulk RNA-seq data (BioProject ID: PRJNA1039495) from lung cancer cell lines derived from African American (AA) and European American (EA) individuals were analyzed to identify and quantify different isoforms of CCL20. MD simulations were performed to evaluate the binding affinity of CCL20, hydrogen-bond stability, and conformational behavior upon interaction with the CCR6 receptor. Downstream pathway activation potential was inferred by comparing the expression of signaling molecules that support oncogenic pathways and are associated with poor therapeutic outcomes. Furthermore, smoking habits, including higher nicotine intake, distinct metabolite patterns, and alterations in basic cytokine levels, were incorporated into the model as external factors that may influence CCL20 isoforms and CCR6 signaling. Results: Out of 5 CCL20 isoforms, Isoform-1 (24 TPM) and Isoform-2 (36 TPM) showed stronger interactions with CCR6 compared to EA cells (Isoform-1: 7.5 TPM; Isoform-2: 11.2 TPM). Across smoking groups, AA cells showed higher Isoform-2 levels than EA cells, increasing from non-smokers (Isoform-1: 18 TPM; Isoform-2: 18 TPM) to smokers (Isoform-1: 24 TPM; Isoform-2: 40 TPM), while EA cells showed lower increases from non-smokers (Isoform-1: 18 TPM; Isoform-2: 19 TPM) to smokers (Isoform-1: 24 TPM; Isoform-2: 30 TPM). MD simulations revealed that lung-cancer-cell CCR6 binds both CCL20 Isoform-1 & 2 from AA-derived cell lines with significantly stronger affinity compared to EA-derived cells, reflected by lower binding free energies, more stable hydrogen-bonds, and longer ligand-receptor contact durations. Isoform-2 showed the strongest overall binding affinity, indicating that it may be the dominant activator of CCR6 signaling. Population-level behavioral data, including All of Us cohort metrics, showed that AA smokers tend to use cigarettes with higher nicotine content, inhale more deeply, and exhibit slower nicotine and cotinine clearance, which corresponded with increased Isoform-2 expression. Conclusion: Lung cancer cells derived from AA exhibit a ligand-rich and affinity-enhanced CCL20-CCR6 signaling axis driven primarily by Isoform-2. Isoform-specific expression, receptor affinity, and smoking-associated inflammation together highlight the significance of Isoform-2 in disparity observation in Lung cancer, as a key player in contributing to disparity.