Many primary-tumor subregions have low levels of molecular oxygen, termed hypoxia. Hypoxic tumors are at elevated risk for local failure and distant metastasis, but the molecular hallmarks of tumor hypoxia remain poorly defined. To fill this gap, we quantified hypoxia in 8,006 tumors across 19 tumor types. In ten tumor types, hypoxia was associated with elevated genomic instability. In all 19 tumor types, hypoxic tumors exhibited characteristic driver-mutation signatures. We observed widespread hypoxia-associated dysregulation of microRNAs (miRNAs) across cancers and functionally validated miR-133a-3p as a hypoxia-modulated miRNA. In localized prostate cancer, hypoxia was associated with elevated rates of chromothripsis, allelic loss of PTEN and shorter telomeres. These associations are particularly enriched in polyclonal tumors, representing a constellation of features resembling tumor nimbosus, an aggressive cellular phenotype. Overall, this work establishes that tumor hypoxia may drive aggressive molecular features across cancers and shape the clinical trajectory of individual tumors.

Molecular landmarks of tumor hypoxia across cancer types.

Cancer is driven by multiple types of genetic alterations, which range in size from point mutations to whole-chromosome gains and losses, known as aneuploidy. Chromosome instability, the process that gives rise to aneuploidy, can promote tumorigenesis by increasing genetic heterogeneity and promoting tumour evolution. However, much less is known about how aneuploidy itself contributes to tumour formation and progression. Unlike some pan-cancer oncogenes and tumour suppressor genes that drive transformation in virtually all cell types and cellular contexts, aneuploidy is not a universal promoter of tumorigenesis. Instead, recent studies suggest that aneuploidy is a context-dependent, cancer-type-specific oncogenic event that may have clinical relevance as a prognostic marker and as a potential therapeutic target. Aneuploidy contributes to tumorigenesis, but the underlying processes are not well understood. This Review explains the context dependency of aneuploidy in cancer and discusses its clinical potential as a prognostic marker and a therapeutic target.

/pdf/context-is-everything-aneuploidy-in-cancer-284j9pjng9.pdf

Context is everything: aneuploidy in cancer

https://www.research.manchester.ac.uk/portal/files/170856250/PIIS0092867419301618.pdf

Characterizing Mutational Signatures in Human Cancer Cell Lines Reveals Episodic APOBEC Mutagenesis.

PI3Ks are a family of lipid kinases that phosphorylate intracellular inositol lipids to regulate signalling and intracellular vesicular traffic. Mammals have eight isoforms of PI3K, divided into three classes. The class I PI3Ks generate 3-phosphoinositide lipids, which directly activate signal transduction pathways. In addition to being frequently genetically activated in cancer, similar mutations in class I PI3Ks have now also been found in a human non-malignant overgrowth syndrome and a primary immune disorder that predisposes to lymphoma. The class II and class III PI3Ks are regulators of membrane traffic along the endocytic route, in endosomal recycling and autophagy, with an often indirect effect on cell signalling. Here, we summarize current knowledge of the different PI3K classes and isoforms, focusing on recently uncovered biological functions and the mechanisms by which these kinases are activated. Deeper insight into the PI3K isoforms will undoubtedly continue to contribute to a better understanding of fundamental cell biological processes and, ultimately, of human disease.

/pdf/pi3k-isoforms-in-cell-signalling-and-vesicle-trafficking-1l6d3tm1z6.pdf

PI3K isoforms in cell signalling and vesicle trafficking.

Aberrant chromosomal architecture, ranging from small insertions or deletions to large chromosomal alterations, is one of the most common characteristics of cancer genomes. Chromosomal instability (CIN) underpins much of the intratumoural heterogeneity observed in cancers and drives phenotypic adaptation during tumour evolution. Thus, an urgent need exists to increase our efforts to target CIN as if it were a molecular entity. Indeed, CIN accelerates the development of anticancer drug resistance, often leading to treatment failure and disease recurrence, which limit the effectiveness of most current therapies. Identifying novel strategies to modulate CIN and to exploit the fitness cost associated with aneuploidy in cancer is, therefore, of paramount importance for the successful treatment of cancer. Modern sequencing and analytical methods greatly facilitate the identification and cataloguing of somatic copy-number alterations and offer new possibilities to better exploit the dynamic process of CIN. In this Review, we describe the principles governing CIN propagation in cancer and how CIN might influence sensitivity to immune-checkpoint inhibition, and survey the vulnerabilities associated with CIN that offer potential therapeutic opportunities.

/pdf/determinants-and-clinical-implications-of-chromosomal-8zpcenjiv0.pdf

Determinants and clinical implications of chromosomal instability in cancer

Cancer develops through a process of somatic evolution. Here, we reconstruct the evolutionary history of 2,778 tumour samples from 2,658 donors spanning 39 cancer types. Characteristic copy number gains, such as trisomy 7 in glioblastoma or isochromosome 17q in medulloblastoma, are found amongst the earliest events in tumour evolution. The early phases of oncogenesis are driven by point mutations in a restricted set of cancer genes, often including biallelic inactivation of tumour suppressors. By contrast, increased genomic instability, a more than three-fold diversification of driver genes, and an acceleration of mutational processes are features of later stages. Clock-like mutations yield estimates for whole genome duplications and subclonal diversification in chronological time. Our results suggest that driver mutations often precede diagnosis by many years, and in some cases decades. Taken together, these data reveal common and divergent trajectories of cancer evolution, pivotal for understanding tumour biology and guiding early cancer detection.

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Kaixan Yu

Papers

The evolutionary history of 2,658 cancers