Abstract 4403: FDG uptake in human lung adenocarcinoma associated with invasion through the hexosamine biosynthesis pathway

Introduction Metabolic reprogramming is a cancer hallmark that is not fully understood. Moreover, increasing evidence suggests that metabolic dysregulation is histology-specific, particularly in the case of non-small cell lung cancer (NSCLC). In this study, we investigated the differences in glucose metabolism between the two major histology subtypes of NSCLC, namely adenocarcinoma (AD) and squamous cell carcinoma (SQ). We explored transcriptomics in association with FDG-PET SUVmax (maximum standardized uptake value), a common clinical marker of glucose uptake in cancer. Methods We identified metabolically-associated differentially expressed genes (DEGs) by histology subtypes using RNAseq data from resected tumors in our study cohort of 127 NSCLC patients (96 AD and 31 SQ) and validated the DEGs on The Cancer Genome Atlas. We also identified gene-enriched cellular processes correlated with SUVmax separately for AD and SQ. We validated our findings in public domain cell line microarray data. In a separate cohort of 40 NSCLC patients (20 patients overlap with study cohort) whose tumors were sorted by cell type (cancer, endothelial, fibroblast and immune cells), we identified specific cell types where the genes of interest were expressed. Results Metabolically-associated DEGs in AD were enriched in the hexosamine biosynthesis pathway (HBP), which is involved in glycosylating proteins related to invasion. SUVmax correlated genes in AD were enriched for epithelial-mesenchymal transition (EMT) and extracellular matrix remodeling. In particular, GFPT2 (the rate-limiting gene in HBP) and 4 EMT-related glycoprotein genes were highly correlated with SUVmax, suggesting potency of HBP for EMT related glucose metabolic reprogramming. We validated the findings on cell line microarray data (GSE49644) before and after TGF-β induced EMT, showing that many genes in HBP increased after induced EMT, while genes in the glycolysis pathway and the pentose phosphate pathway (PPP) were unchanged or reduced. HBP genes and many SUVmax correlated EMT genes were most highly expressed in tumor-associated fibroblasts compared to other cells in the tumor microenvironment. In SQ, metabolically-associated DEGs were enriched in the glycolysis pathway and PPP. SUVmax correlated genes were enriched for cell development. Conclusion An integrative analysis of PET-RNAseq showed that in AD glucose uptake was related to invasion through metabolic reprogramming of HBP. In SQ, glucose uptake was ass