Neoplasia最新文献

Betel quid (BQ) chewing is a profound risk for oral squamous cell carcinoma (OSCC) in Southeast Asia. Yet, the detailed mechanisms by which BQ chewing damages the genome and creates a unique tumor niche that ultimately cause OSCC are still not fully understood. To address this, we conducted a multi-omics survey, including exome sequencing of tumor-normal pairs from 261 male patients with OSCC (129 habitual BQ chewers and 132 non-BQ users), alone with integrated single-cell and spatial transcriptomics of a set of tumors. Comparative analyses of the mutational catalog identified enrichment of significantly altered genes (e.g. mutations of TP53 and CHUK, copy gains of MAP3K13 and FADD, copy losses of CDKN2A) associated with BQ chewing. Assessment of oncogenic and co-occurring actionable alterations demonstrated frequently altered oncogenic pathways (Hippo and p53 signaling) and potential combination therapy opportunities linked to BQ use. In addition, evaluation of epithelial, immune, stromal expression programs in the corresponding tissue compartments revealed a shift of tumor microenvironment in BQ-related OSCC, characterized by induced hypoxia of tumor epithelium, altered immunosuppression of dendritic cells, and raised sprouting angiogenesis of tumor endothelium. Quantitative predictions of intercellular communications inferred a more heterogeneous cell-cell crosstalk among BQ-related OSCC, highlighted by extensive interactions of fibroblasts and dendritic cells with other non-epithelial cell types via mostly extracellular matrix-receptor signaling pathways. Collectively, these differences in genomic landscape and tumor niche suggest that OSCC caused by BQ chewing could be an etiological subtype different from their BQ-negative counterparts.

DFMO has been studied as a cancer therapeutic at doses ranging from 500 to 9,000 mg/m2/day. Lower doses are favored for cancer prevention studies while higher doses, often with chemotherapy, are studied in refractory cancers. DFMO inhibits the rate-limiting enzyme in polyamine synthesis, ornithine decarboxylase (ODC), an oncogene transcriptionally regulated by MYC. MYC genes are the principal oncogenic drivers of neuroblastoma, and ODC1 is co-amplified in a subset with dismal outcome, so DFMO is a rational therapeutic candidate. Low-dose DFMO has now been FDA-approved for high-risk patients though the mechanisms for its anti-tumor activity, and the exposures required to elicit them, remain obscure. We sought to define biomarkers of activity across exposures achieved in the clinic with low through high-dose DFMO. Polyamines support protein translation by providing spermidine, which is essential to hypusinate (and activate) the elongation factor, eIF5A. Selective binding of polyamines with tRNA and rRNA provide eIF5A-independent mechanisms of translation support. We show that low-dose DFMO does not extend survival in mouse models in vivo nor alter translation biomarkers in vitro. High-dose DFMO consistently extends survival in neuroblastoma models, and, in a subset of neuroblastoma cell lines, inhibits eIF5A hypusination and global translation at achievable concentrations. However, the concentration required to engage these changes across many cell lines exceeded that achievable even with high-dose DFMO. No correlation was seen among MYCN and/or ODC1 copy number and sensitivity to DFMO. Combining high-dose DFMO with additional agents to further deplete tumor polyamines may be necessary to fully engage polyamine-depletion effects on tumors, and more granular measures of translation, including codon-resolution ribosome profiling, may be required to define these effects.