Metabolic Landscape Study Of Prostate Cancer Based On Single-cell RNA Sequencing

Background: Cancer cells and normal cells differ in cellular metabolism,where cancer cells undergo metabolic reprogramming to promote their growth and survival.However,tumors are composed not only of cancer cells but also of surrounding components such as stromal cells,immune cells,and extracellular matrix.Each cellular subpopulation collaborates with others through intricate signaling networks,forming the tumor microenvironment that maintains dynamic homeostasis for optimal tumor growth.Therefore,understanding the metabolic characteristics of different cellular subgroups within the tumor microenvironment may enhance our understanding of tumor development,drug resistance,and tumor treatment.Materials and Methods: To elucidate the metabolic characteristics of prostate cancer,especially hormone-resistant prostate cancer,we integrated techniques and methods from computational biology,bioinformatics,and metabolomics.By utilizing single-cell RNA sequencing,we obtained publicly available datasets of prostate cancer single-cell transcriptomes along with clinical data.We identified heterogeneous metabolic genes within each cell subpopulation and calculated the average expression of these genes within each cell type.After normalizing gene expression and weighting based on the frequency of metabolic genes in metabolic pathways,we determined the metabolic activity of relevant pathways and compared metabolic heterogeneity among different cell subtypes.Moreover,we compared the differences in metabolic activity of tumor cells using single-cell sequencing and bulk sequencing approaches.Finally,to further validate our computational findings,we selected primary prostate cancer cell lines,neuroendocrine prostate cancer cell lines,and small cell prostate cancer cell lines.We employed metabolite profiling and stable isotope tracing analysis to validate our discoveries and track the conversion process of metabolites.Results: Through bioinformatic analysis,we have discovered that prostate cancer cells exhibit greater metabolic activity and plasticity compared to other stromal components within the tumor microenvironment.During the progression of prostate cancer from hormone-dependent to castration-resistant states,individualized tumor cell metabolic programs are formed through genomic metabolic reprogramming.In particular,hormone-resistant prostate cancer exhibits significant inter-patient heterogeneity in terms of metabolism.Further investigation reveals that the overall metabolic activity of epithelial cells,which are the source of cancer cells in prostate cancer,is significantly higher than that of other cell subtypes.The upregulated metabolic pathways include amino acid metabolism,fatty acid synthesis,tricarboxylic acid cycle,and oxidative phosphorylation.These metabolic differences cannot be detected in normal prostate tissue.Additionally,we found that the true metabolic levels of non-malignant cells can only be detected at the single-cell resolution.Subsequently,we identified oxidative phosphorylation as the highest metabolic pathway in all hormone-resistant prostate cancer patients.Changes in mitochondrial activity serve as crucial regulatory factors contributing to metabolic heterogeneity among PCa patients.Furthermore,nucleotide synthesis,including purine and pyrimidine synthesis,is also one of the most important metabolic pathways.These two metabolic pathways can be linked through the biological function of glutamine.We then analyzed the differences in metabolic activity among different cell types within the epithelial cells of hormone-resistant prostate cancer.We found that most metabolic pathways,including carbon,sugar,nucleotide,and amino acid-related metabolism,were upregulated in neuroendocrine cells.The overall metabolic activity of neuroendocrine cells was significantly higher than that of other epithelial cell components,and they possessed inherent metabolic characteristics.Isotope tracing experiments further confirmed the metabolic heterogeneity in epithelial cells of hormone-resistant prostate cancer,and it was discovered that the origin cells of neuroendocrine prostate cancer,with high oxidative phosphorylation activity,may not arise from the luminal or basal cells of normal prostate epithelium through lineage plasticity.Finally,we conducted a study on the metabolic activity of non-tumor cells in prostate cancer and found that the oxidative phosphorylation pathway remains the main metabolic pathway in all non-tumor cells.Mitochondrial function is a major factor contributing to metabolic heterogeneity in both epithelial and non-epithelial cells of prostate tumors.Conclusions: Tumor metabolic reprogramming is a characteristic of cancer development.Through the use of single-cell RNA sequencing,we have discovered that epithelial cells derived from prostate cancer demonstrate higher metabolic activity and flexibility compared to the surrounding stromal components.Additionally,our analysis of epithelial cell subpopulations in the prostate cancer tumor microenvironment has revealed a natural inclination towards higher metabolic rates in neuroendocrine cells.This finding may explain the substantial nutritional and energy requirements observed in neuroendocrine prostate cancer.Accordingly,targeting the metabolic vulnerabilities of this cancer subtype could prove to be an effective therapeutic strategy.Furthermore,our research supports the "clonal expansion" theory of neuroendocrine tumor development from a metabolic perspective.Moreover,our study has confirmed that changes in mitochondrial activity are the primary determinant of metabolic heterogeneity between tumor and non-tumor cells in prostate cancer.These findings provide a comprehensive understanding of the metabolic landscape in prostate cancer,shedding light on potential mechanisms underlying disease progression,and emphasizing the importance of investigating tumor heterogeneity and the tumor microenvironment from a metabolic standpoint.