MORC family CW-type zinc finger 2 (MORC2) is an oncogenic chromatin-remodeling enzyme with an emerging role in DNA repair. Here, we report a novel function for MORC2 in cell-cycle checkpoint control through an acetylation-dependent mechanism. MORC2 is acetylated by the acetyltransferase NAT10 at lysine 767 (K767Ac) and this process is counteracted by the deacetylase SIRT2 under unperturbed conditions. DNA-damaging chemotherapeutic agents and ionizing radiation stimulate MORC2 K767Ac through enhancing the interaction between MORC2 and NAT10. Notably, acetylated MORC2 binds to histone H3 phosphorylation at threonine 11 (H3T11P) and is essential for DNA damage-induced reduction of H3T11P and transcriptional repression of its downstream target genes CDK1 and Cyclin B1, thus contributing to DNA damage-induced G2 checkpoint activation. Chemical inhibition or depletion of NAT10 or expression of an acetylation-defective MORC2 (K767R) forces cells to pass through G2 checkpoint, resulting in hypersensitivity to DNA-damaging agents. Moreover, MORC2 acetylation levels are associated with elevated NAT10 expression in clinical breast tumor samples. Together, these findings uncover a previously unrecognized role for MORC2 in regulating DNA damage-induced G2 checkpoint through NAT10-mediated acetylation and provide a potential therapeutic strategy to sensitize breast cancer cells to DNA-damaging chemotherapy and radiotherapy by targeting NAT10.

The molecular underpinnings behind malignant progression of breast cancer from a localized lesion to an invasive and ultimately metastatic disease are incompletely understood. Here, we report that F-box only protein 22 (FBXO22) plays a dual role in mammary tumorigenesis and metastasis. FBXO22 was upregulated in primary breast tumors and promoted cell proliferation and colony formation and xenograft tumorigenicity Surprisingly, FBXO22 suppressed epithelial-mesenchymal transition (EMT), cell motility, and invasiveness and metastatic lung colonization Clinical data showed that expression levels of FBXO22 were associated with favorable clinical outcomes, supporting the notion that metastasis, rather than primary cancer, is the major determinant of the mortality of patients with breast cancer. Mechanistic investigations further revealed that FBXO22 elicits its antimetastatic effects by targeting SNAIL, a master regulator of EMT and breast cancer metastasis, for ubiquitin-mediated proteasomal degradation in a glycogen synthase kinase 3β phosphorylation-dependent manner. Importantly, expression of SNAIL rescued FBXO22-mediated suppression of EMT, cell migration, and invasion. A patient-derived tryptophan-to-arginine mutation at residue 52 (W52R) within the F-box domain impaired FBXO22 binding to the SKP1-Cullin1 complex and blocked FBXO22-mediated SNAIL degradation, thus abrogating the ability of FBXO22 to suppress cell migration, invasion, and metastasis. Collectively, these findings uncover an unexpected dual role for FBXO22 in mammary tumorigenesis and metastatic progression and delineate the mechanism of an oncogenic mutation of FBXO22 in breast cancer progression. These findings highlight the paradoxical roles of FBXO22 in breast cancer, as it promotes breast tumor cell proliferation but prevents EMT and metastasis. .

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Metabolic reprogramming is a hallmark of cancer. However, systematic characterizations of metabolites in triple-negative breast cancer (TNBC) are still lacking. Our study profiled the polar metabolome and lipidome in 330 TNBC samples and 149 paired normal breast tissues to construct a large metabolomic atlas of TNBC. Combining with previously established transcriptomic and genomic data of the same cohort, we conducted a comprehensive analysis linking TNBC metabolome to genomics. Our study classified TNBCs into three distinct metabolomic subgroups: C1, characterized by the enrichment of ceramides and fatty acids; C2, featured with the upregulation of metabolites related to oxidation reaction and glycosyl transfer; and C3, having the lowest level of metabolic dysregulation. Based on this newly developed metabolomic dataset, we refined previous TNBC transcriptomic subtypes and identified some crucial subtype-specific metabolites as potential therapeutic targets. The transcriptomic luminal androgen receptor (LAR) subtype overlapped with metabolomic C1 subtype. Experiments on patient-derived organoid and xenograft models indicate that targeting sphingosine-1-phosphate (S1P), an intermediate of the ceramide pathway, is a promising therapy for LAR tumors. Moreover, the transcriptomic basal-like immune-suppressed (BLIS) subtype contained two prognostic metabolomic subgroups (C2 and C3), which could be distinguished through machine-learning methods. We show that N-acetyl-aspartyl-glutamate is a crucial tumor-promoting metabolite and potential therapeutic target for high-risk BLIS tumors. Together, our study reveals the clinical significance of TNBC metabolomics, which can not only optimize the transcriptomic subtyping system, but also suggest novel therapeutic targets. This metabolomic dataset can serve as a useful public resource to promote precision treatment of TNBC.