Biology subjects

Nassar, A.

Publications and source records attributed to Nassar, A..

3 recordsLinked to original sources

bioRxiv2025

Tumor-Derived Polyamines Initiate Fat Wasting in Cancer Cachexia

Cancer-associated cachexia (CC) is a fatal metabolic condition characterized by progressive loss of fat and muscle mass, yet its early molecular drivers remain poorly defined. Here, we identify a polyamine-dependent tumor-adipose crosstalk that triggers adipocyte lipolysis and fat wasting during the pre-cachexia stage, preceding systemic inflammation and muscle atrophy. Cancer-derived polyamines are enriched in extracellular vesicles and promote lipid mobilization via eIF5A hypusination, independent of adrenergic signaling. In preclinical models, polyamine accumulation associates with early fat loss and elevated circulating fatty acids. Clinically, automated CT imaging of newly diagnosed pancreatic cancer patients reveals increased adipose density, reflecting lipolysis, that correlates with circulating polyamine levels and predicts poor survival. These findings support polyamine metabolism as a mechanistic driver and candidate biomarker of early cachexia, providing a framework for early detection and targeted intervention.

cancer biology↗

bioRxiv2025

Age-dependent tumor-immune interactions underlie immunotherapy response in pediatric cancer

Pediatric cancers originate in rapidly growing tissues within the context of a developing host. However, the interactions between cancer cells and the developing immune system are incompletely understood. Here, we established a suite of pediatric syngeneic mouse cancer models across diverse anatomical sites and compared their tumor immune microenvironment with that in adult mice. Tumors in pediatric mice exhibited significantly accelerated growth and diminished leukocyte infiltration, dominated by naive-like PD-1low/CD8+ T cells, and proliferative MHCIIlow/PD-L1hi/CD86low macrophages. Tumor-infiltrating leukocytes in pediatric mice were enriched for MYC targets, which was also observed in pediatric patient samples. Furthermore, pediatric mice displayed poor responses to anti-PD-1/PD-L1 or bispecific T cell engager antibodies, which could be reversed by inducing a proinflammatory microenvironment via MYC inhibition or inducing macrophage polarization to an MHCIIhi phenotype. These findings underscore the significant influence of young age on cancer immune responses and reveal potential new therapeutic opportunities for pediatric cancers. HIGHLIGHTSO_LIAllograft tumors exhibit markedly accelerated growth in pediatric hosts compared to adults. C_LIO_LITumors growing in pediatric mice have reduced leukocyte infiltration, dominated by naive-like PD-1low/CD8+ T cells, and MHCIIlow/M2-like macrophages. C_LIO_LIEnrichment of MYC target genes is observed in pediatric mouse tumors and confirmed in primary patient tumor samples. C_LIO_LIPediatric mice display reduced response to anti-PD-1/PD-L1 and BiTE immunotherapy, which can be reversed by remodeling the TIME, using either MYC inhibition or macrophage polarization. C_LI

cancer biology↗

bioRxiv2020

Reprogramming of the FOXA1 cistrome in treatment-emergent neuroendocrine prostate cancer

Lineage plasticity, the ability of a cell to alter its identity, is an increasingly common mechanism of adaptive resistance to targeted therapy in cancer1,2. An archetypal example is the development of neuroendocrine prostate cancer (NEPC) after treatment of prostate adenocarcinoma (PRAD) with inhibitors of androgen signaling. NEPC is an aggressive variant of prostate cancer that aberrantly expresses genes characteristic of neuroendocrine (NE) tissues and no longer depends on androgens. To investigate the epigenomic basis of this resistance mechanism, we profiled histone modifications in NEPC and PRAD patient-derived xenografts (PDXs) using chromatin immunoprecipitation and sequencing (ChIP-seq). We identified a vast network of cis-regulatory elements (N~15,000) that are recurrently activated in NEPC. The FOXA1 transcription factor (TF), which pioneers androgen receptor (AR) chromatin binding in the prostate epithelium3,4, is reprogrammed to NE-specific regulatory elements in NEPC. Despite loss of dependence upon AR, NEPC maintains FOXA1 expression and requires FOXA1 for proliferation and expression of NE lineage-defining genes. Ectopic expression of the NE lineage TFs ASCL1 and NKX2-1 in PRAD cells reprograms FOXA1 to bind to NE regulatory elements and induces enhancer activity as evidenced by histone modifications at these sites. Our data establish the importance of FOXA1 in NEPC and provide a principled approach to identifying novel cancer dependencies through epigenomic profiling.

cancer biology↗