Abstract Gastric mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are aggressive malignancies that exhibit complex cellular heterogeneity driven by the dual lineages. The dismal patient survival rates highlight the need to elucidate the cellular origin of gastric MiNENs and the key regulatory mechanisms to develop improved treatment strategies. Here, we identified a gastric POU2F3+epithelial population as a potential cell of origin for gastric MiNENs. Lineage tracing and single-cell RNA sequencing further identified that POU2F3+ cells include three distinct subpopulations with divergent differentiation trajectories: progenitor cells (SOX2+SOX9+), tuft cells (POU2F3+DCLK1+), and neuroendocrine cells (SYP+CHGA+). Combined Rb1/Trp53 deletion and MYC overexpression in POU2F3+ epithelial cells (Pou2f3-CreERT; Rb1fl/fl; Trp53fl/fl; LSL-MycT58A) led to the rapid development of gastric MiNENs containing both neuroendocrine and non-neuroendocrine lesions, recapitulating human gastric MiNENs pathology. Transcription factor activity analysis and spatial transcriptomics revealed SOX2 and SOX9 as critical regulators driving subpopulation specification, with SOX2 and SOX9 being enriched in dysplasia and adenocarcinoma, respectively. Bulk RNA sequencing further showed increased expression of CXCL5 in gastric MiNENs, and inhibition of CXCL5 reduced the growth of tumor organoids and xenografts in mouse models. Together these findings offer a physiologically relevant model for studying gastric MiNENs and identify CXCL5 as a potential therapeutic target for this heterogeneous cancer.
Abstract Mutations in isocitrate dehydrogenase (IDHm) define a distinct molecular class of gliomas. IDHm converts α-ketoglutarate (α-KG) to the oncometabolite D-2-hydroxyglutarate (D-2HG), which drives tumorigenesis. The IDHm inhibitor vorasidenib suppresses D-2HG production and prolongs progression-free survival in some, but not all, patients. Here, using patient-derived models, genetically engineered glioma cells, orthotopic xenografts, and patient tissue, we showed that phosphoglycerate dehydrogenase (PHGDH) mediates intrinsic resistance to vorasidenib by sustaining D-2HG production despite IDHm inhibition. Silencing PHGDH suppressed residual D-2HG synthesis and restored vorasidenib sensitivity in resistant models, whereas PHGDH overexpression restored D-2HG production and induced resistance in sensitive models. Importantly, restoration of intracellular D-2HG rescued growth despite continued vorasidenib treatment, demonstrating a causal role for residual D-2HG production in the resistant phenotype. Mechanistically, a permissive chromatin state characterized by increased H3K4me3, reduced H3K27me3, and enhanced ATF4 occupancy at the PHGDH promoter facilitated PHGDH upregulation in resistant models. Pharmacologic induction of this chromatin state induced PHGDH expression, restored D-2HG production, and conferred resistance to vorasidenib in sensitive models. Consistently, tumor tissue from patients with poor response to IDHm inhibitor treatment exhibited higher PHGDH expression, coupled with the ATF4-enriched permissive chromatin state observed in resistant models. Finally, deuterium metabolic imaging of D-2HG production from diethyl-[3,3′-2H]-α-KG provided an early, non-invasive readout of response and resistance to vorasidenib in vivo. Collectively, this study identifies a chromatin-regulated ATF4-PHGDH-D-2HG axis as a mechanism of intrinsic resistance to IDHm inhibition and establishes diethyl-[3,3′-2H]-α-KG as a metabolic imaging probe for interrogating treatment response in IDHm gliomas.
Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy 20% more likely to develop in Black African Americans (BAA) compared to Non-African Americans (NAA). Large-scale gene expression analysis of tumor subtypes and cellular microenvironments in a diverse PDAC cohort could help provide insights into cell and molecular differences in BAA cancer cells. Here, we conducted a multi-omics interrogation of BAA versus NAA PDAC using whole exome sequencing, spatial transcriptomics (ST), and spatial proteomics. Whole exome sequencing confirmed patient ancestry and showed no significant differences in driver mutations between race groups. BAA PDAC tumors had significantly fewer classical molecular subtype cells with no change in more aggressive basal-like cells. Instead, BAA patients showed a significant enrichment of the intermediate/hybrid subtype compared to NAA patients. BAA tumors also displayed increased B cell and reduced myeloid cell interactions compared to NAA tumors. Analysis of tertiary lymphoid structures in a validation cohort revealed that tumors in BAA patients displayed larger TLS size and number compared to NAA. In conclusion, these findings identify an increased intermediate molecular subtype signature in BAA tumors at the expense of cells with a classical subtype, accompanied by a distinct immune cell composition and spatial distribution. This study highlights that health disparities in patients of different ancestries may have a molecular basis that influences tumor aggressiveness and the immune response, which may inform therapeutic strategies.
Growth-induced solid stress and fluid pressure contribute to tumor progression and drug resistance. Beyond tumor endogenous physical forces, cells in the tumor microenvironment may also experience external macroscopic mechanical stress, and some tumors preferentially develop in weight-bearing regions with higher focal pressure. Characterization of the impact of macroscopic mechanical stress on the tumor microenvironment could help uncover the mechanistic links between external mechanical forces and increased tumor incidence. Here, we showed that recurrent macroscopic mechanical stress disrupts nuclear envelope integrity, leading to spatial reorganization and fibroblast subtype changes at the tumor-stromal interface. In mouse models of plantar melanoma, exogenous mechanical stress induced nuclear envelope rupture in melanoma cells and increased LRRC15-positive myofibroblasts. Reduction of nuclear envelope integrity through inducible deletion of Lmna likewise increased LRRC15-positive myofibroblast generation. Co-culture with myofibroblasts promoted nuclear envelope rupture in melanoma cells in 3D culture, suggesting a positive feedback loop. In addition, mechanical stress-driven transcriptomic changes in tumor and stromal cells were observed alongside enhanced lymph node metastasis and immunotherapy resistance. Analysis of human melanoma samples revealed mechanical stress-associated stromal remodeling and a higher incidence of lymph node metastasis in tumors arising in mechanically stressed regions, although these features were not significantly associated with overall survival. Together, these findings suggest that macroscopic mechanical stress may influence cancer progression by inducing nuclear envelope damage and reshaping tumor-stromal interactions.
Abstract The mevalonate (MVA) pathway generates sterols and isoprenoids essential for membrane biosynthesis and signaling. Increased activity of the MVA pathway is a common feature of cancer and has emerged as a potential therapeutic vulnerability. In this study, we showed that the MVA pathway sustains de novo serine biosynthesis and aspartate production by maintaining NAD+ regeneration through ubiquinone-dependent electron transport. Statin-mediated inhibition of the MVA pathway impaired oxidative phosphorylation, lowered the NAD+/NADH ratio, suppressed serine and aspartate biosynthesis, and activated the GCN2–eIF2α–ATF4 amino acid deprivation response. The resulting depletion of serine-derived glycine and one-carbon units, together with reduced aspartate availability, limited purine and pyrimidine biosynthesis. Genetic and pharmacologic disruption of ubiquinone synthesis recapitulated the metabolic defects, whereas expression of the bacterial NADH oxidase Lactobacillus brevis NADH oxidase restored the NAD+/NADH ratio and reversed the metabolic and growth defects induced by statin treatment. Importantly, impairment of NAD+ regeneration reduced phosphoglycerate dehydrogenase (PHGDH)–dependent de novo serine synthesis, thereby sensitizing neuroblastoma cells to PHGDH inhibition. Accordingly, simvastatin enhanced the antiproliferative effects of the PHGDH inhibitor NCT-503 in vitro and exhibited elevated antitumor activity in combination with NCT-503 in neuroblastoma xenograft models. Together, these findings establish ubiquinone-dependent NAD+ regeneration as a key mechanism linking the MVA pathway to amino acid and nucleotide biosynthesis and provide a mechanistic rationale for combined targeting of the MVA pathway and serine biosynthesis in cancer. Significance: The mevalonate pathway functions as a regulator of amino acid and nucleotide biosynthesis through mitochondrial NAD+ regeneration, providing a rationale for targeting mevalonate metabolism and serine biosynthesis in cancer.
