Decoding tumor metabolic and immunologic interactions driving different biological subtypes in patients with bladder cancer.

Bladder cancer (BLCA) patients exhibit variable survival and oncologic outcomes that may be influenced by tumor-specific biological activities. We have identified through mass spectrometry, genome-wide transcriptomics, and functional biology in cell lines and BLCA patient tumors a pattern of mitochondrial dysregulation and immune activation present disproportionately in different subsets of BLCA patients. Based on this insight, we first characterized downstream metabolic changes and discovered that various degrees of mitochondrial complex 1 dysregulation were observed in different subsets of BLCA patients and proportionally correlated with aggressiveness of BLCA. In addition, targeted inhibition of complex 1 resulted in improved cancer outcomes in a preclinical model. Tumors with increased complex I activity demonstrated higher glutamine flux into the TCA cycle via activation of GLS1, leading to accumulation of fatty acids through reductive carboxylation. Furthermore, a subset of tumors with increased mitochondrial complex 1 activity showed enhanced expression of the key complex 1 gene NDUFB8. Knockdown (KD) of NDUFB8 resulted in reduced mitochondrial complex 1 activity, glutamine metabolism, ATP production, and regression of BLCA growth. Lastly, we found these tumors with increased mitochondrial complex 1 activity also demonstrated concurrent activation of key immune signaling pathways, including IFN signaling pathways, suggesting a potential interaction between tumor metabolic activities and immune signaling. At the level of basic science, this project aims to identify the metabolic and immunologic basis of BLCA patients by metabolomic analysis of the OXPHOS-GLS1 metabolic axis and by using cutting-edge single-cell RNA sequencing and imaging mass cytometry to profile the tumor immune microenvironment and analyze tumor cell-immune cell interactions. At the translational level, this work will lay the foundation to test therapeutic strategies targeting complex 1 alone or in combination with GLS1 inhibition. If successful, these metabolic therapeutic strategies may be further combined with immunotherapeutic interventions for different biological subsets of BLCA patients.