Succinyl-CoA ligase ADP-forming subunit beta promotes stress granule assembly to regulate redox and drive cancer metastasis.

Although recent studies demonstrate active mitochondrial metabolism in cancers, the precise mechanisms through which mitochondrial factors contribute to cancer metastasis remain elusive. Through a customized mitochondrion RNAi screen, we identified succinyl-CoA ligase ADP-forming subunit beta (SUCLA2) as a critical anoikis resistance and metastasis driver in human cancers. Mechanistically, SUCLA2, but not the alpha subunit of its enzyme complex, relocates from mitochondria to the cytosol upon cell detachment where SUCLA2 then binds to and promotes the formation of stress granules. SUCLA2-mediated stress granules facilitate the protein translation of antioxidant enzymes including catalase, which mitigates oxidative stress and renders cancer cells resistant to anoikis. We provide clinical evidence that SUCLA2 expression correlates with catalase levels as well as metastatic potential in lung and breast cancer patients. These findings not only implicate SUCLA2 as an anticancer target, but also provide insight into a unique, noncanonical function of SUCLA2 that cancer cells co-opt to metastasize.

Loss of the endocytic tumor suppressor HD-PTP phenocopies LKB1 and promotes RAS-driven oncogenesis.

Oncogenic RAS mutations drive aggressive cancers that are difficult to treat in the clinic, and while direct inhibition of the most common KRAS variant in lung adenocarcinoma (G12C) is undergoing clinical evaluation, a wide spectrum of oncogenic RAS variants together make up a large percentage of untargetable lung and GI cancers. Here we report that loss-of-function alterations (mutations and deep deletions) in the gene that encodes HD-PTP (PTPN23) occur in up to 14% of lung cancers in the ORIEN Avatar lung cancer cohort, associate with adenosquamous histology, and occur alongside an altered spectrum of KRAS alleles. Furthermore, we show that in publicly available early-stage NSCLC studies loss of HD-PTP is mutually exclusive with loss of LKB1, which suggests they restrict a common oncogenic pathway in early lung tumorigenesis. In support of this, knockdown of HD-PTP in RAS-transformed lung cancer cells is sufficient to promote FAK-dependent invasion. Lastly, knockdown of the Drosophila homolog of HD-PTP (dHD-PTP/Myopic) synergizes to promote RAS-dependent neoplastic progression. Our findings highlight a novel tumor suppressor that can restrict RAS-driven lung cancer oncogenesis and identify a targetable pathway for personalized therapeutic approaches for adenosquamous lung cancer.

EGFR-phosphorylated GDH1 harmonizes with RSK2 to drive CREB activation and tumor metastasis in EGFR-activated lung cancer.

The cancer metastasis process involves dysregulated oncogenic kinase signaling, but how this orchestrates metabolic networks and signal cascades to promote metastasis is largely unclear. Here we report that inhibition of glutamate dehydrogenase 1 (GDH1) and ribosomal S6 kinase 2 (RSK2) synergistically attenuates cell invasion, anoikis resistance, and immune escape in lung cancer and more evidently in tumors harboring epidermal growth factor receptor (EGFR)-activating or EGFR inhibitor-resistant mutations. Mechanistically, GDH1 is activated by EGFR through phosphorylation at tyrosine 135 and, together with RSK2, enhances the cAMP response element-binding protein (CREB) activity via CaMKIV signaling, thereby promoting metastasis. Co-targeting RSK2 and GDH1 leads to enhanced intratumoral CD8 T cell infiltration. Moreover, GDH1, RSK2, and CREB phosphorylation positively correlate with EGFR mutation and activation in lung cancer patient tumors. Our findings reveal a crosstalk between kinase, metabolic, and transcription machinery in metastasis and offer an alternative combinatorial therapeutic strategy to target metastatic cancers with activated EGFRs that are often EGFR therapy resistant.

Reduced dopaminergic neuron degeneration and global transcriptional changes in Parkinson's disease mouse brains engrafted with human neural stems during the early disease stage.

INTRODUCTION: Current stem cell therapies for Parkinson's disease (PD) focus on a neurorestorative approach that aims to repair the CNS during the symptomatic phase. However, the pleiotropic and supportive effects of human neural stem cells (hNSCs) may make them effective for PD treatment during the disease's earlier stages. In the current study, we investigated the therapeutic effects of transplanting hNSCs during the early stages of PD development when most dopaminergic neurons are still present and before symptoms appear. Previous studies on hNSCs in Parkinson's disease focus on the substantia nigra and its immediate surroundings, but other brain structures are affected in PD as well. Here, we investigated the therapeutic effects of hNSCs on the entire PD-afflicted brain transcriptome using RNA sequencing (RNA-seq). METHODS: PD was induced with a single intranasal infusion of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) and hNSCs were transplanted unilaterally into the striatum one week later. The timepoint for hNSC transplantation coincided with upregulation of endogenous proinflammatory cytokines in the CNS, which play a role in stem cell migration. At 3 weeks post-transplantation (4 weeks post-MPTP), we assessed motor symptoms through behavioral tests, quantified dopaminergic neurons in the substantia nigra, and performed global transcriptional profiling to understand the mechanism underlying the effect of hNSCs on dopaminergic neuron degeneration. RESULTS: We found that early hNSC engraftment mitigated motor symptoms induced by MPTP, and also reduced MPTP-induced loss of dopaminergic neurons. In this study, we uniquely presented the first comprehensive analysis of the effect of hNSC transplantation on the transcriptional profiling of PD mouse brains showing decreased expression of 249 and increased expression of 200 genes. These include genes implicated in mitochondrial bioenergetics, proteostasis, and other signaling pathways associated with improved PD outcome following hNSC transplantation. CONCLUSION: These findings indicate that NSC transplantation during the asymptomatic phase of PD may limit or halt the progression of this neurodegenerative disorder. Transcriptional profiling of hNSC-engrafted PD mouse brains provides mechanistic insight that could lead to novel approaches to ameliorating degeneration of dopaminergic neurons and improving behavioral dysfunction in PD.

Metabolic inhibitor screening identifies dihydrofolate reductase as an inducer of the tumor immune escape mediator CD24.

Immune checkpoint inhibitors have improved the clinical management of some cancer cases, yet patients still fail to respond to immunotherapy. Dysregulated metabolism is a common feature of many cancers, and metabolites are known to modulate functions in cancer cells. To identify potential metabolic pathways involved in anti-tumor immune response, we employed a metabolic inhibitor-based drug screen in human lung cancer cell lines and examined expression changes in a panel of immune regulator genes. Notably, pharmacologic inhibition of dihydrofolate reductase (DHFR) downregulated cancer cell expression of cluster of differentiation 24 (CD24), an anti-phagocytic surface protein. Genetic modulation of DHFR resulted in decrease of CD24 expression, whereas tetrahydrofolate, the product of DHFR, enhanced CD24 expression. DHFR inhibition and the consequent CD24 decrease enhanced T cell-mediated tumor cell killing, whereas replenishment of DHFR or CD24 partially mitigated the immune-mediated tumor cell killing that resulted from methotrexate treatment in cancer cells. Moreover, publicly available clinical data analyses further revealed the link between DHFR, CD24, and the antitumor immune response in lung cancer patients. Our study highlights a novel connection between folate metabolism and the anti-tumor immune response and partially interprets how DHFR inhibitors lead to clinical benefits when combined with cancer immunotherapy agents.

Cisplatin-mediated activation of glucocorticoid receptor induces platinum resistance via MAST1.

Agonists of glucocorticoid receptor (GR) are frequently given to cancer patients with platinum-containing chemotherapy to reduce inflammation, but how GR influences tumor growth in response to platinum-based chemotherapy such as cisplatin through inflammation-independent signaling remains largely unclear. Combined genomics and transcription factor profiling reveal that MAST1, a critical platinum resistance factor that reprograms the MAPK pathway, is upregulated upon cisplatin exposure through activated transcription factor GR. Mechanistically, cisplatin binds to C622 in GR and recruits GR to the nucleus for its activation, which induces MAST1 expression and consequently reactivates MEK signaling. GR nuclear translocation and MAST1 upregulation coordinately occur in patient tumors collected after platinum treatment, and align with patient treatment resistance. Co-treatment with dexamethasone and cisplatin restores cisplatin-resistant tumor growth, whereas addition of the MAST1 inhibitor lestaurtinib abrogates tumor growth while preserving the inhibitory effect of dexamethasone on inflammation in vivo. These findings not only provide insights into the underlying mechanism of GR in cisplatin resistance but also offer an effective alternative therapeutic strategy to improve the clinical outcome of patients receiving platinum-based chemotherapy with GR agonists.

Mitochondrial metabolism-mediated redox regulation in cancer progression.

Cancer cells display abnormal metabolic activity as a result of activated oncogenes and loss of tumor suppressor genes. The Warburg Effect is a common metabolic feature of cancer that involves a preference for aerobic glycolysis over oxidative phosphorylation to generate ATP and building blocks for biosynthesis. However, emerging evidence indicates that mitochondrial metabolic pathways are also reprogrammed in cancer and play vital roles in bioenergetics, biosynthesis, and managing redox homeostasis. The mitochondria act a central hub for metabolic pathways that generate ATP and building blocks for lipid, nucleic acid and protein biosynthesis. However, mitochondrial respiration is also a leading source of reactive oxygen species that can damage cellular organelles and trigger cell death if levels become too high. In general, cancer cells are reported to have higher levels of reactive oxygen species than their non-cancerous cells of origin, and therefore must employ diverse metabolic strategies to prevent oxidative stress. However, mounting evidence indicates that the metabolic profiles between proliferative and disseminated cancer cells are not the same. In this review, we will examine mitochondrial metabolic pathways, such as glutaminolysis, that proliferative and disseminated cancer cells utilize to control their redox status.

DGKA Provides Platinum Resistance in Ovarian Cancer Through Activation of c-JUN-WEE1 Signaling.

PURPOSE: Although platinum compounds are the first-line treatment for ovarian cancer, the majority of patients relapse and develop resistance to treatment. However, the mechanism underlying resistance is unclear. The goal of our study is to decipher the mechanism by which a metabolic kinase, diacylglycerol kinase alpha (DGKA), confers platinum resistance in ovarian cancer. EXPERIMENTAL DESIGN: Metabolic kinase RNAi synthetic lethal screening was used to identify a cisplatin resistance driver in ovarian cancer. DGKA variants were used to demonstrate the need for DGKA activity in cisplatin resistance. Phospho-proteomic and genomic screens were performed to identify downstream effectors of DGKA. Therapeutic efficacy of targeting DGKA was confirmed and clinical relevance of DGKA signaling was validated using ovarian cancer patient-derived tumors that had different responses to platinum-based therapy. RESULTS: We found that platinum resistance was mediated by DGKA and its product, phosphatidic acid (PA), in ovarian cancer. Proteomic and genomic screens revealed that DGKA activates the transcription factor c-JUN and consequently enhances expression of a cell-cycle regulator, WEE1. Mechanistically, PA facilitates c-JUN N-terminal kinase recruitment to c-JUN and its nuclear localization, leading to c-JUN activation upon cisplatin exposure. Pharmacologic inhibition of DGKA sensitized ovarian cancer cells to cisplatin treatment and DGKA-c-JUN-WEE1 signaling positively correlated with platinum resistance in tumors derived from patients with ovarian cancer. CONCLUSIONS: Our study demonstrates how the DGKA-derived lipid messenger, PA, contributes to cisplatin resistance by intertwining with kinase and transcription networks, and provides preclinical evidence for targeting DGKA as a new strategy in ovarian cancer treatment to battle cisplatin resistance.

Tumor Progression of Breast Cancer during Hyperinsulinemic Obesity.

Factors of metabolic syndrome including hyperinsulinemia and obesity are well known to increase the risk of cancer incidence and progression. In a recent iScience article, Ramos et al. demonstrate a novel tumor-suppressor role of the circadian transcription factor BMAL1 in triple-negative breast cancer (TNBC) specifically under conditions of hyperinsulinemia.

Human neural stem cells improve early stage stroke outcome in delayed tissue plasminogen activator-treated aged stroke brains.

INTRODUCTION: Clinically, significant stroke injury results from ischemia-reperfusion (IR), which induces a deleterious biphasic opening of the blood-brain barrier (BBB). Tissue plasminogen activator (tPA) remains the sole pharmacological agent to treat ischemic stroke. However, major limitations of tPA treatment include a narrow effective therapeutic window of 4.5 h in most patients after initial stroke onset and off-target non-thrombolytic effects (e.g., the risk of increased IR injury). We hypothesized that ameliorating BBB damage with exogenous human neural stem cells (hNSCs) would improve stroke outcome to a greater extent than treatment with delayed tPA alone in aged stroke mice. METHODS: We employed middle cerebral artery occlusion to produce focal ischemia with subsequent reperfusion (MCAO/R) in aged mice and administered tPA at a delayed time point (6 h post-stroke) via tail vein. We transplanted hNSCs intracranially in the subacute phase of stroke (24 h post-stroke). We assessed the outcomes of hNSC transplantation on pathophysiological markers of stroke 48 h post-stroke (24 h post-transplant). RESULTS: Delayed tPA treatment resulted in more extensive BBB damage and inflammation relative to MCAO controls. Notably, transplantation of hNSCs ameliorated delayed tPA-induced escalated stroke damage; decreased expression of proinflammatory factors (tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6), decreased the level of matrix metalloprotease-9 (MMP-9), increased the level of brain-derived neurotrophic factor (BDNF), and reduced BBB damage. CONCLUSIONS: Aged stroke mice that received delayed tPA treatment in combination with hNSC transplantation exhibited reduced stroke pathophysiology in comparison to non-transplanted stroke mice with delayed tPA. This suggests that hNSC transplantation may synergize with already existing stroke therapies to benefit a larger stroke patient population.

Neural stem cell therapy for neurovascular injury in Alzheimer's disease.

Alzheimer's disease (AD), the most common form of dementia, is characterized by progressive neurodegeneration leading to severe cognitive decline and eventual death. AD pathophysiology is complex, but neurotoxic accumulation of amyloid-ß (Aß) and hyperphosphorylation of Tau are believed to be main drivers of neurodegeneration in AD. The formation and deposition of Aß plaques occurs in the brain parenchyma as well as in the cerebral vasculature. Thus, proper blood-brain barrier (BBB) and cerebrovascular functioning are crucial for clearance of Aß from the brain, and neurovascular dysfunction may be a critical component of AD development. Further, neuroinflammation and dysfunction of angiogenesis, neurogenesis, and neurorestorative capabilities play a role in AD pathophysiology. Currently, there is no effective treatment to prevent or restore loss of brain tissue and cognitive decline in patients with AD. Based on multifactorial and complex pathophysiological cascades in multiple Alzheimer's disease stages, effective AD therapies need to focus on targeting early AD pathology and preserving cerebrovascular function. Neural stem cells (NSCs) participate extensively in mammalian brain homeostasis and repair and exhibit pleiotropic intrinsic properties that likely make them attractive candidates for the treatment of AD. In the review, we summarize the current advances in knowledge regarding neurovascular aspects of AD-related neurodegeneration and discuss multiple actions of NSCs from preclinical studies of AD to evaluate their potential for future clinical treatment of AD.

Hsp90B enhances MAST1-mediated cisplatin resistance by protecting MAST1 from proteosomal degradation.

Microtubule-associated serine/threonine kinase 1 (MAST1) is a central driver of cisplatin resistance in human cancers. However, the molecular mechanism regulating MAST1 levels in cisplatin-resistant tumors is unknown. Through a proteomics screen, we identified the heat shock protein 90 B (hsp90B) chaperone as a direct MAST1 binding partner essential for its stabilization. Targeting hsp90B sensitized cancer cells to cisplatin predominantly through MAST1 destabilization. Mechanistically, interaction of hsp90B with MAST1 blocked ubiquitination of MAST1 at lysines 317 and 545 by the E3 ubiquitin ligase CHIP and prevented proteasomal degradation. The hsp90B-MAST1-CHIP signaling axis and its relationship with cisplatin response were clinically validated in cancer patients. Furthermore, combined treatment with a hsp90 inhibitor and the MAST1 inhibitor lestaurtinib further abrogated MAST1 activity and consequently enhanced cisplatin-induced tumor growth arrest in a patient-derived xenograft model. Our study not only uncovers the regulatory mechanism of MAST1 in tumors but also suggests a promising combinatorial therapy to overcome cisplatin resistance in human cancers.

Inositol-triphosphate 3-kinase B confers cisplatin resistance by regulating NOX4-dependent redox balance.

How altered metabolism contributes to chemotherapy resistance in cancer cells remains unclear. Through a metabolism-related kinome RNAi screen, we identified inositol-trisphosphate 3-kinase B (ITPKB) as a critical enzyme that contributes to cisplatin-resistant tumor growth. We demonstrated that inositol 1,3,4,5-tetrakisphosphate (IP4), the product of ITPKB, plays a critical role in redox homeostasis upon cisplatin exposure by reducing cisplatin-induced ROS through inhibition of a ROS-generating enzyme, NADPH oxidase 4 (NOX4), which promotes cisplatin-resistant tumor growth. Mechanistically, we identified that IP4 competes with the NOX4 cofactor NADPH for binding and consequently inhibits NOX4. Targeting ITPKB with shRNA or its small-molecule inhibitor resulted in attenuation of NOX4 activity, imbalanced redox status, and sensitized cancer cells to cisplatin treatment in patient-derived xenografts. Our findings provide insight into the crosstalk between kinase-mediated metabolic regulation and platinum-based chemotherapy resistance in human cancers. Our study also suggests a distinctive signaling function of IP4 that regulates NOX4. Furthermore, pharmaceutical inhibition of ITPKB displayed synergistic attenuation of tumor growth with cisplatin, suggesting ITPKB as a promising synthetic lethal target for cancer therapeutic intervention to overcome cisplatin resistance.

Neural stem cell therapy for subacute and chronic ischemic stroke.

Neural stem cells (NSCs) play vital roles in brain homeostasis and exhibit a broad repertoire of potentially therapeutic actions following neurovascular injury. One such injury is stroke, a worldwide leading cause of death and disability. Clinically, extensive injury from ischemic stroke results from ischemia-reperfusion (IR), which is accompanied by inflammation, blood-brain barrier (BBB) damage, neural cell death, and extensive tissue loss. Tissue plasminogen activator (tPA) is still the only US Food and Drug Administration-approved clot-lysing agent. Whereas the thrombolytic role of tPA within the vasculature is beneficial, the effects of tPA (in a non-thrombolytic role) within the brain parenchyma have been reported as harmful. Thus, new therapies are needed to reduce the deleterious side effects of tPA and quickly facilitate vascular repair following stroke. The Stroke Treatment Academic Industry Roundtable (STAIR) recommends that stroke therapies "focus on drugs/devices/treatments with multiple mechanisms of action and that target multiple pathways". Thus, based on multifactorial ischemic cascades in various stroke stages, effective stroke therapies need to focus on targeting and ameliorating early IR injury as well as facilitating angiogenesis, neurogenesis, and neurorestorative mechanisms following stroke. This review will discuss the preclinical perspectives of NSC transplantation as a promising treatment for neurovascular injury and will emphasize both the subacute and chronic phase of ischemic stroke.

Sex differences in abdominal aortic aneurysms.

Abdominal aortic aneurysm (AAA) is a vascular disorder with a high case fatality rate in the instance of rupture. AAA is a multifactorial disease, and the etiology is still not fully understood. AAA is more likely to occur in men, but women have a greater risk of rupture and worse prognosis. Women are reportedly protected against AAA possibly by premenopausal levels of estrogen and are, on average, diagnosed at older ages than men. Here, we review the present body of research on AAA pathophysiology in humans, animal models, and cultured cells, with an emphasis on sex differences and sex steroid hormone signaling.

Rapid estrogen receptor-α signaling mediated by ERK activation regulates vascular tone in male and ovary-intact female mice.

Estrogen has been shown to affect vascular reactivity. Here, we assessed the estrogen receptor-α (ERα) dependency of estrogenic effects on vasorelaxation via a rapid nongenomic pathway in both male and ovary-intact female mice. We compared the effect of a primary estrogen, 17ß-estradiol (E2) or 4,4',4″-(4-propyl-[1H]pyrazole-1,3,5-triyl)tris-phenol (PPT; selective ERα agonist). We found that E2 and PPT induced greater aortic relaxation in female mice than in male mice, indicating ERα mediation, which was further validated by using ERα antagonism. Treatment with 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP dihydrochloride; ERα antagonist) attenuated PPT-mediated vessel relaxation in both sexes. ERα-mediated vessel relaxation was further validated by the absence of significant PPT-mediated relaxation in aortas isolated from ERα knockout mice. Treatment with a specific ERK inhibitor, PD-98059, reduced E2-induced vessel relaxation in both sexes but to a lesser extent in female mice. Furthermore, PD-98059 prevented PPT-induced vessel relaxation in both sexes. Both E2 and PPT treatment activated ERK as early as 5-10 min, which was attenuated by PD-98059 in aortic tissue, cultured primary vascular smooth muscle cells (VSMCs), and endothelial cells (ECs). Aortic rings denuded of endothelium showed no differences in vessel relaxation after E2 or PPT treatment, implicating a role of ECs in the observed sex differences. Here, our results are unique to show estrogen-stimulated rapid ERα signaling mediated by ERK activation in aortic tissue, as well as VSMCs and ECs in vitro, in regulating vascular function by using side-by-side comparisons in male and ovary-intact female mice in response to E2 or PPT. NEW & NOTEWORTHY Here, we assessed the estrogen receptor-α dependency of estrogenic effects in vasorelaxation of both male and ovary-intact female mice by performing side-by-side comparisons. Also, we describe the connection between estrogen-stimulated rapid estrogen receptor-α signaling and downstream ERK activation in regulating vascular function in male and ovary-intact female mice.

Sex differences in vascular physiology and pathophysiology: estrogen and androgen signaling in health and disease.

Sex differences between women and men are often overlooked and underappreciated when studying the cardiovascular system. It has been long assumed that men and women are physiologically similar, and this notion has resulted in women being clinically evaluated and treated for cardiovascular pathophysiological complications as men. Currently, there is increased recognition of fundamental sex differences in cardiovascular function, anatomy, cell signaling, and pathophysiology. The National Institutes of Health have enacted guidelines expressly to gain knowledge about ways the sexes differ in both normal function and diseases at the various research levels (molecular, cellular, tissue, and organ system). Greater understanding of these sex differences will be used to steer future directions in the biomedical sciences and translational and clinical research. This review describes sex-based differences in the physiology and pathophysiology of the vasculature, with a special emphasis on sex steroid receptor (estrogen and androgen receptor) signaling and their potential impact on vascular function in health and diseases (e.g., atherosclerosis, hypertension, peripheral artery disease, abdominal aortic aneurysms, cerebral aneurysms, and stroke).