Copper (Cu) is an essential micronutrient required for the activity of redox-active enzymes involved in critical metabolic reactions, signaling pathways, and biological functions. Transporters and chaperones control Cu ion levels and bioavailability to ensure proper subcellular and systemic Cu distribution. Intensive research has focused on understanding how mammalian cells maintain Cu homeostasis, and how molecular signals coordinate Cu acquisition and storage within organs. In humans, mutations of genes that regulate Cu homeostasis or facilitate interactions with Cu ions lead to numerous pathologic conditions. Malfunctions of the Cu + -transporting ATPases ATP7A and ATP7B cause Menkes disease and Wilson disease, respectively. Additionally, defects in the mitochondrial and cellular distributions and homeostasis of Cu lead to severe neurodegenerative conditions, mitochondrial myopathies, and metabolic diseases. Cu has a dual nature in K E Y W O R D S cancer, copper, copper-dependent diseases, cuproproteins, Menkes disease, mitochondrial myopathies, Wilson disease

Background Mitochondrial nucleoside diphosphate kinase (NDPK-D, NME4, NM23-H4) is a multifunctional enzyme mainly localized in the intermembrane space, bound to the inner membrane. Results We constructed loss-of-function mutants of NDPK-D, lacking either NDP kinase activity or membrane interaction and expressed mutants or wild-type protein in cancer cells. In a complementary approach, we performed depletion of NDPK-D by RNA interference. Both loss-of-function mutations and NDPK-D depletion promoted epithelial-mesenchymal transition and increased migratory and invasive potential. Immunocompromised mice developed more metastases when injected with cells expressing mutant NDPK-D as compared to wild-type. This metastatic reprogramming is a consequence of mitochondrial alterations, including fragmentation and loss of mitochondria, a metabolic switch from respiration to glycolysis, increased ROS generation, and further metabolic changes in mitochondria, all of which can trigger pro-metastatic protein expression and signaling cascades. In human cancer, NME4 expression is negatively associated with markers of epithelial-mesenchymal transition and tumor aggressiveness and a good prognosis factor for beneficial clinical outcome. Conclusions These data demonstrate NME4 as a novel metastasis suppressor gene, the first localizing to mitochondria, pointing to a role of mitochondria in metastatic dissemination.

Zinc (Zn) is an essential trace element that plays a key role in several biological processes, including transcription, signaling, and catalysis. A subcellular network of transporters ensures adequate distribution of Zn to facilitate homeostasis. Among these are a family of importers, the Zrt/Irt-like proteins (ZIP), which consists of 14 members (ZIP1-ZIP14) that mobilize Zn from the extracellular domain and organelles into the cytosol. Expression of these transporters varies among tissues and during developmental stages, and their distribution at various cellular locations is essential for defining the net cellular Zn transport. Normally, the ion is bound to proteins or sequestered in organelles and vesicles. However, though research has focused on Zn internalization in mammalian cells, little is known about Zn mobilization within organelles, including within the nuclei under both normal and pathological conditions. Analyses from stomach and colon tissues isolated from mouse suggested that ZIP11 is the only ZIP transporter localized to the nucleus of mammalian cells, yet no clear cellular role has been attributed to this protein. We hypothesized that ZIP11 is essential to maintaining nuclear Zn homeostasis in mammalian cells. To test this, we utilized HeLa cells, as research in humans correlated elevated expression of ZIP11 with poor prognosis in cervical cancer patients. We stably knocked down ZIP11 in HeLa cancer cells and investigated the effect of Zn dysregulation in vitro. Our data show that ZIP11 knockdown (KD) reduced HeLa cells proliferation due to nuclear accumulation of Zn. RNA-seq analyses revealed that genes related to angiogenesis, apoptosis, mRNA metabolism, and signaling pathways are dysregulated. Although the KD cells undergoing nuclear Zn stress can activate the homeostasis response by MTF1 and MT1, the RNA-seq analyses showed that only ZIP14 (an importer expressed on the plasma membrane and endocytic vesicles) is mildly induced, which may explain the sensitivity to elevated levels of extracellular Zn. Consequently, ZIP11 KD HeLa cells have impaired migration, invasive properties and decreased mitochondrial potential. Furthermore, KD of ZIP11 delayed cell cycle progression and rendered an enhanced senescent state in HeLa cells, pointing to a novel mechanism whereby maintenance of nuclear Zn homeostasis is essential for cancer progression.

Genomic instability is a hallmark of most cancers that enables tumor cells to adapt and evolve, but also creates vulnerabilities that can be therapeutically exploited. Cancer therapies that target the DNA Damage Response (DDR) have proven to be efficacious across a broad range of cancer types, but often present a narrow therapeutic window and limited duration of response due to the development of resistance. Through mining our proprietary CRISPRomics® Oncology dataset we identified the ubiquitin protease, USP1, as an attractive target with activity in ovarian and triple negative breast cancers (TNBC). USP1 facilitates DNA repair via its role regulating the Fanconi anemia complex and translesion synthesis. We developed a series of potent, selective USP1 inhibitors to investigate the therapeutic potential of targeting USP1 in tumor settings dependent on those DNA repair processes. When profiled across a broad range of cancer cell line models, the USP1-inhibitor KSQ-4279 showed anti-proliferative effects in a subset of cell lines, often characterized by the presence of homologous recombination deficiencies (HRD), including mutations in BRCA1/2. To better understand the mechanism of action of KSQ-4279, we employed large scale functional genomic screens using KSQ-4279, olaparib, and cisplatin, in combination with a DNA-repair focused CRISPR library, to identify genetic determinants of sensitivity and anticipate modes of drug resistance. In addition to recovering genetic associations between KSQ-4279 and genes that modify USP1's direct substrates, our screens identified genetic interactions of KSQ-4279 with multiple DNA repair pathways, including genes involved in ubiquitin-mediated signaling events that regulate the response to DNA damage and replication stress. These studies revealed that the profile of resistance to KSQ-4279 is distinct from, and in some cases complementary to, other DNA damaging agents, and provide a mechanistic rationale for the use of KSQ-4279 in combination with other agents that target DNA repair. Consistent with the largely non-overlapping resistance profile of USP1 and PARP inhibitors, we found that the combination of KSQ-4279 with olaparib was able to induce strong and durable regressions across a number of ovarian and TNBC PDX models. Citation Format: Sol Shenker, Hugh Gannon, Alyssa Carlson, Paula Grasberger, Pamela Sullivan, Chris Middleton, Anne Dodson, Caroline Bullock, Michael McGuire, Erica Tobin, Kerstin Sinkevicius, Mike Schlabach, Frank Stegmeier, Louise Cadzow, Andrew Wylie. Functional genomic characterization of the USP1 inhibitor KSQ-4279 reveals a distinct mechanism of action and resistance profile relative to other DDR targeting drugs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1337.

Background: Mesenchymal stem cell-derived neural progenitor cell (MSC-NP) therapy is an experimental approach to treat multiple sclerosis. The influence of MSC-NPs on microglial activation was investigated. Methods: Microglia were stimulated in the presence of MSC-NP-conditioned media, and proinflammatory or proregenerative marker expression was assessed by quantitative PCR and ELISA. Results: Microglia stimulated in the presence of MSC-NP-conditioned media displayed reduced expression of proinflammatory markers including CCL2, increased expression of proregenerative markers and reduced phagocytic activity. The paracrine effects of MSC-NPs from multiple donors correlated with TGF-β3 gene expression and was reversed by TGF-β signaling inhibition. Conclusion: MSC-NPs promote beneficial microglial polarization through secreted factors. This study suggests that microglia are a potential therapeutic target of MSC-NP cell therapy.

Emerging evidence points to several fundamental contributions that copper (Cu) has to promote the development of human pathologies such as cancer. These recent and increasing identification of the roles of Cu in cancer biology highlights a promising field in the development of novel strategies against cancer. Cu and its network of regulatory proteins are involved in many different contextual aspects of cancer from driving cell signaling, modulating cell cycle progression, establishing the epithelial-mesenchymal transition, and promoting tumor growth and metastasis. Human cancer research in general requires refined models to bridge the gap between basic science research and meaningful clinical trials. Classic studies in cultured cancer cell lines and animal models such as mice and rats often present caveats when extended to humans due to inherent genetic and physiological differences. However, larger animal models such as pigs are emerging as more appropriate tools for translational research as they present more similarities with humans in terms of genetics, anatomical structures, organ sizes, and pathological manifestations of diseases like cancer. These similarities make porcine models well-suited for addressing long standing questions in cancer biology as well as in the arena of novel drug and therapeutic development against human cancers. With the emergent roles of Cu in human health and pathology, the pig presents an emerging and valuable model to further investigate the contributions of this metal to human cancers. The Oncopig Cancer Model is a transgenic swine model that recapitulates human cancer through development of site and cell specific tumors. In this review, we briefly outline the relationship between Cu and cancer, and how the novel Oncopig Cancer Model may be used to provide a better understanding of the mechanisms and causal relationships between Cu and molecular targets involved in cancer.

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Tumors with BRCA1/2 mutations and other homologous repair deficiencies (HRD) are vulnerable to agents that target the remaining DNA repair pathways, including platinum-containing chemotherapy agents and molecules targeting poly (ADP-ribose) polymerase-1 (PARP1). Despite the clinical benefit achieved with these drugs, many patients achieve incomplete disease control and resistance often emerges. With the goal of addressing this clinical need, we applied our proprietary CRISPRomics technology to identify novel targets in cancer indications characterized by defects in DNA repair pathways. One of the top ranked targets was the deubiquitinating enzyme USP1. USP1 has established roles in DNA damage repair processes including Translesion Synthesis and the Fanconi Anemia pathway. We developed KSQ-4279, a potent, highly selective inhibitor of USP1. KSQ-4279 was active in cells, leading to the accumulation of mono-ubiquitinated substrates of USP1 and inhibited the proliferation of cancer cell lines with BRCA mutations or other HRD alterations. Studies investigating the effect of combining KSQ-4279 with PARP inhibitors revealed clear evidence of synergy in cell lines with partial or no sensitivity to each agent alone. To investigate how the distinct mechanisms of action of KSQ-4279 and PARP inhibitors would be reflected in their resistance profiles, we used our CRISPRomics technology to perform functional genomic resistance screens. The top scoring resistance genes for KSQ-4279 were distinct from those identified for PARP inhibitors, which raised the possibility that combining PARP and USP1 inhibitors may provide more durable disease control by reducing the emergence of resistance. Evaluation of KSQ-4279 in patient-derived ovarian and triple-negative breast cancer xenograft models demonstrated dose-dependent tumor growth inhibition as a single agent and in combination with PARP inhibitors. In xenograft models that were insensitive or only partially sensitive to PARP inhibitors, the combination of KSQ-4279 and Olaparib led to tumor regressions and durable tumor control. This data supports the ongoing clinical trial of KSQ-4279 in patients with tumors harboring BRCA1/2 or other HRD mutations, both as a single agent and in combination with PARP inhibitors. Citation Format: Louise Cadzow, Erica Tobin, Pamela Sullivan, Sol Shenker, Sumeet Nayak, Janid Ali, Hugh Gannon, Anne Dodson, Paula Grasberger, Alyssa Carlson, Michael McGuire, Jehrod Brenneman, Hanlan Liu, Andrew Olaharski, Kerstin Sinkevicius, Jeff Hixon, Elsa Krall, Mike Schlabach, Matt Goulet, Jeremy Wilt, Patricia Harris, Frank Stegmeier, Andrew Wylie. KSQ-4279: A first-in-class USP1 inhibitor for the treatment of cancers with homologous recombination deficiencies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr ND01.