Chromosomal instability (CIN) is a hallmark of cancer and it results from ongoing errors in chromosome segregation during mitosis. While CIN is a major driver of tumor evolution, its role in metastasis has not been established. Here we show that CIN promotes metastasis by sustaining a tumor-cell autonomous response to cytosolic DNA. Errors in chromosome segregation create a preponderance of micronuclei whose rupture spills genomic DNA into the cytosol. This leads to the activation of the cGAS-STING cytosolic DNA-sensing pathway and downstream noncanonical NF-κB signaling. Genetic suppression of CIN significantly delays metastasis even in highly aneuploid tumor models, whereas inducing continuous chromosome segregation errors promotes cellular invasion and metastasis in a STING-dependent manner. By subverting lethal epithelial responses to cytosolic DNA, chromosomally unstable tumor cells co-opt chronic activation of innate immune pathways to spread to distant organs.

Genomic instability promotes tumorigenesis and can occur through various mechanisms, including defective segregation of chromosomes or inactivation of DNA mismatch repair. Although B-cell lymphomas are associated with chromosomal translocations that deregulate oncogene expression, a mechanism for genome-wide instability during lymphomagenesis has not been described. During B-cell development, the immunoglobulin variable (V) region genes are subject to somatic hypermutation in germinal-centre B cells. Here we report that an aberrant hypermutation activity targets multiple loci, including the proto-oncogenes PIM1, MYC, RhoH/TTF (ARHH) and PAX5, in more than 50% of diffuse large-cell lymphomas (DLCLs), which are tumours derived from germinal centres. Mutations are distributed in the 5' untranslated or coding sequences, are independent of chromosomal translocations, and share features typical of V-region-associated somatic hypermutation. In contrast to mutations in V regions, however, these mutations are not detectable in normal germinal-centre B cells or in other germinal-centre-derived lymphomas, suggesting a DLCL-associated malfunction of somatic hypermutation. Intriguingly, the four hypermutable genes are susceptible to chromosomal translocations in the same region, consistent with a role for hypermutation in generating translocations by DNA double-strand breaks. By mutating multiple genes, and possibly by favouring chromosomal translocations, aberrant hypermutation may represent the major contributor to lymphomagenesis.

SUMMARY The prognosis of patients with glioblastoma (GBM) remains dismal, with a median survival of approximately 15 months. Current preclinical GBM models are limited by the lack of a “normal” human microenvironment and the inability of many tumor cell lines to accurately reproduce GBM biology. To address these limitations, we have established a model system whereby we can retro-engineer patient-specific GBMs using patient-derived glioma stem cells (GSCs) and human embryonic stem cell (hESC)-derived cerebral organoids. Our cerebral organoid glioma (GLICO) model shows that GSCs home toward the human cerebral organoid and deeply invade and proliferate within the host tissue, forming tumors that closely phenocopy patient GBMs. Furthermore, cerebral organoid tumors form rapidly and are supported by an interconnected network of tumor micro-tubes that aids in the invasion of normal host tissue. Our GLICO model provides a system for modeling primary human GBM ex vivo and for high-throughput drug screening.

The molecular foundations of Hürthle cell carcinoma (HCC) are poorly understood. Here we describe a comprehensive genomic characterization of 56 primary HCC tumors that span the spectrum of tumor behavior. We elucidate the mutational profile and driver mutations and show that these tumors exhibit a wide range of recurrent mutations. Notably, we report a high number of disruptive mutations to both protein-coding and tRNA-encoding regions of the mitochondrial genome. We reveal unique chromosomal landscapes that involve whole-chromosomal duplications of chromosomes 5 and 7 and widespread loss of heterozygosity arising from haploidization and copy-number-neutral uniparental disomy. We also identify fusion genes and disrupted signaling pathways that may drive disease pathogenesis.