Assistant Professor Dartmouth College Lebanon, NH, United States
Background: Pseudohypoxia-related metabolic alterations are known to exist in clear-cell renal cell carcinoma (ccRCC). Here we characterized single-cell metabolic pathways with the 10Xmultiome assay comparing metabolic and compositional shifts in tumor vs. normal-adjacent samples.
Methods: We analyzed 57 tumors from our Biobank. 10X multiome processing, data was processed in Seurat, Azimuth, SCEVAN, and scMetabolism. Linear mixed-effects models compared cell lineages scMetabolism metabolic scores between tumor and normal cells adjusting for sex, patient age, stage and grade as fixed-effects and donor, and year of collection, as random-effects. P-values were calculated using Satterthwaite's method.
Results: The mean age at diagnosis was 61.7 yrs (SD: 12.5), and 67% were stages I/II. 85,771 cells were analyzed. KEGG metabolic pathways were prioritized based on literature. Comparing normal adjacent cell type vs. tumor cells: 1) glutamine/glutamate expression increased in lymphoid, endothelial, and stromal cells; 2) fatty acid biosynthesis increased in myeloid and reduced in lymphoid, collecting ducts-like, and nephron loop-like cells, 3) glutathione and glycolysis increased in glomeruli-like and nephron loops-like, 4) glycolysis increased in collecting ducts-like and endothelial, 5) oxidative phosphorylation and TCA cycle genes decreased in distal tubules-like, collecting ducts-like, and endothelia, 6) arachidonic acid metabolism increased in nephron loops-like and glomeruli-like, and 7) phenylalanine, tyrosine, and tryptophan biosynthesis decreased in nephron loops-like, distal tubules-like, and collecting ducts-like cells.
Conclusions: Tumor vs. normal cell-specific metabolic shifts were observed that cannot be explained only by sample heterogeneity or cell lineages. Oxidative phosphorylation and TCA cycle modifications were observed in tumor endothelia and cells resembling distal tubules and collecting ducts. Similarly, glutamate and fatty acid alterations were focused on tumor microenvironment immune cells. Further dissecting these findings will provide additional therapeutic avenues for newer targets, such as glutaminase inhibitors and combinations with current therapies.
