Cell

Ribosome ADP-ribosylation inhibits translation and maintains proteostasis in cancers

Defects in translation lead to changes in the expression of proteins that can serve as drivers of cancer formation. Here, we show that cytosolic NAD

Proteogenomic Characterization of Endometrial Carcinoma

We undertook a comprehensive proteogenomic characterization of 95 prospectively collected endometrial carcinomas, comprising 83 endometrioid and 12 serous tumors. This analysis revealed possible new consequences of perturbations to the p53 and Wnt/β-catenin pathways, identified a potential role for circRNAs in the epithelial-mesenchymal transition, and provided new information about proteomic markers of clinical and genomic tumor subgroups, including relationships to known druggable pathways. An extensive genome-wide acetylation survey yielded insights into regulatory mechanisms linking Wnt signaling and histone acetylation. We also characterized aspects of the tumor immune landscape, including immunogenic alterations, neoantigens, common cancer/testis antigens, and the immune microenvironment, all of which can inform immunotherapy decisions. Collectively, our multi-omic analyses provide a valuable resource for researchers and clinicians, identify new molecular associations of potential mechanistic significance in the development of endometrial cancers, and suggest novel approaches for identifying potential therapeutic targets.

ACSL4 and polyunsaturated lipids support metastatic extravasation and colonization

Metastatic dissemination to distant organs demands that cancer cells possess high morphological and metabolic adaptability. However, contributions of the cellular lipidome to metastasis remain elusive. Here, we uncover a correlation between metastasis potential and ferroptosis susceptibility in multiple cancers. Metastases-derived cancer cells exhibited higher ferroptosis sensitivity and polyunsaturated fatty acyl (PUFA)-lipid contents than primary-tumor-derived cells from ovarian cancer patients. Metabolism-focused CRISPR screens in a mouse model for ovarian cancer distant metastasis established via two rounds of in vivo selection revealed the PUFA-lipid biosynthesis enzyme acyl-coenzyme A (CoA) synthetase long-chain family member 4 (ACSL4) as a pro-hematogenous metastasis factor. ACSL4 promotes metastatic extravasation by enhancing membrane fluidity and cellular invasiveness. While promoting metastasis, the high PUFA-lipid state creates dependencies on abhydrolase-domain-containing 6, acylglycerol lipase (ABHD6), enoyl-CoA delta isomerase 1 (ECI1), and enoyl-CoA hydratase 1 (ECH1)-rate-limiting enzymes preparing unsaturated fatty acids (UFAs) for β-oxidation. ACSL4/ECH1 co-inhibition achieved potent suppression of metastasis. Our work establishes the dual functions of PUFA-lipids in tumor progression and metastasis that may be exploitable for therapeutic development.

Ovarian cancer-derived IL-4 promotes immunotherapy resistance

Ovarian cancer is resistant to immunotherapy, and this is influenced by the immunosuppressed tumor microenvironment (TME) dominated by macrophages. Resistance is also affected by intratumoral heterogeneity, whose development is poorly understood. To identify regulators of ovarian cancer immunity, we employed a spatial functional genomics screen (Perturb-map), focused on receptor/ligands hypothesized to be involved in tumor-macrophage communication. Perturb-map recapitulated tumor heterogeneity and revealed that interleukin-4 (IL-4) promotes resistance to anti-PD-1. We find ovarian cancer cells are the key source of IL-4, which directs the formation of an immunosuppressive TME via macrophage control. IL-4 loss was not compensated by nearby IL-4-expressing clones, revealing short-range regulation of TME composition dictating tumor evolution. Our studies show heterogeneous TMEs can emerge from localized altered expression of cancer-derived cytokines/chemokines that establish immune-rich and immune-excluded neighborhoods, which drive clone selection and immunotherapy resistance. They also demonstrate the potential of targeting IL-4 signaling to enhance ovarian cancer response to immunotherapy.

Transforming lives through genetics

Mary-Claire King's approach to genetics has had a major impact on breast and ovarian cancer and, more recently, mental illnesses including schizophrenia. Science writer Kendall Morgan talked with Mary-Claire, recipient of a 2021 Canada Gairdner International Award, about her life, her lengthy quest to discover the genetic basis of susceptibility to breast cancer, the struggles for women in science, and much more. An edited version of this conversation is presented below.

Locally produced autoantibodies in cancer

The function and antigen-specificities of tumor-infiltrating B cells are mostly unknown. In a new study by Mazor et al., matrix metalloproteinase 14 (MMP14), a self-antigen that is overexpressed by ovarian cancers, is shown to drive B cell activation and autoantibody production in tertiary lymphoid structures (Mazor et al., 2022).

Neoadjuvant PARPi or chemotherapy in ovarian cancer informs targeting effector Treg cells for homologous-recombination-deficient tumors

Homologous recombination deficiency (HRD) is prevalent in cancer, sensitizing tumor cells to poly (ADP-ribose) polymerase (PARP) inhibition. However, the impact of HRD and related therapies on the tumor microenvironment (TME) remains elusive. Our study generates single-cell gene expression and T cell receptor profiles, along with validatory multimodal datasets from >100 high-grade serous ovarian cancer (HGSOC) samples, primarily from a phase II clinical trial (NCT04507841). Neoadjuvant monotherapy with the PARP inhibitor (PARPi) niraparib achieves impressive 62.5% and 73.6% response rates per RECIST v.1.1 and GCIG CA125, respectively. We identify effector regulatory T cells (eTregs) as key responders to HRD and neoadjuvant therapies, co-occurring with other tumor-reactive T cells, particularly terminally exhausted CD8

High-resolution functional mapping of RAD51C by saturation genome editing

Pathogenic variants in RAD51C confer an elevated risk of breast and ovarian cancer, while individuals homozygous for specific RAD51C alleles may develop Fanconi anemia. Using saturation genome editing (SGE), we functionally assess 9,188 unique variants, including >99.5% of all possible coding sequence single-nucleotide alterations. By computing changes in variant abundance and Gaussian mixture modeling (GMM), we functionally classify 3,094 variants to be disruptive and use clinical truth sets to reveal an accuracy/concordance of variant classification >99.9%. Cell fitness was the primary assay readout allowing us to observe a phenomenon where specific missense variants exhibit distinct depletion kinetics potentially suggesting that they represent hypomorphic alleles. We further explored our exhaustive functional map, revealing critical residues on the RAD51C structure and resolving variants found in cancer-segregating kindred. Furthermore, through interrogation of UK Biobank and a large multi-center ovarian cancer cohort, we find significant associations between SGE-depleted variants and cancer diagnoses.

Genomic characterization of metastatic patterns from prospective clinical sequencing of 25,000 patients.

Metastatic progression is the main cause of death in cancer patients, whereas the underlying genomic mechanisms driving metastasis remain largely unknown. Here, we assembled MSK-MET, a pan-cancer cohort of over 25,000 patients with metastatic diseases. By analyzing genomic and clinical data from this cohort, we identified associations between genomic alterations and patterns of metastatic dissemination across 50 tumor types. We found that chromosomal instability is strongly correlated with metastatic burden in some tumor types, including prostate adenocarcinoma, lung adenocarcinoma, and HR+/HER2+ breast ductal carcinoma, but not in others, including colorectal cancer and high-grade serous ovarian cancer, where copy-number alteration patterns may be established early in tumor development. We also identified somatic alterations associated with metastatic burden and specific target organs. Our data offer a valuable resource for the investigation of the biological basis for metastatic spread and highlight the complex role of chromosomal instability in cancer progression.