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Enormous efforts have been made to target metabolic dependencies of cancer cells for developing new therapies. However, the therapeutic efficacy of glycolysis inhibitors is limited due to their inability to elicit cell death. Hexokinase 2 (HK2), via its mitochondrial localization, functions as a central nexus integrating glycolysis activation and apoptosis resilience. Here we identify that K63-linked ubiquitination by HectH9 regulates the mitochondrial localization and function of HK2. Through stable isotope tracer approach and functional metabolic analyses, we show that HectH9 deficiency impedes tumor glucose metabolism and growth by HK2 inhibition. The HectH9/HK2 pathway regulates cancer stem cell (CSC) expansion and CSC-associated chemoresistance. Histological analyses show that HectH9 expression is upregulated and correlated with disease progression in prostate cancer. This work uncovers that HectH9 is a novel regulator of HK2 and cancer metabolism. Targeting HectH9 represents an effective strategy to achieve long-term tumor remission by concomitantly disrupting glycolysis and inducing apoptosis. Cancer cells develop specific metabolic adaptations. Here, the authors show that in prostate cancer models, the ubiquitin ligase Hect9 promotes tumor growth by accelerating glucose metabolism via ubiquitination of Hexokinase 2, a central regulator of glycolysis.

PI3K/Akt signaling is activated in cancers and governs tumor initiation and progression, but how Akt is activated under diverse stresses is poorly understood. Here we identify AMPK as an essential regulator for Akt activation by various stresses. Surprisingly, AMPK is also activated by growth factor EGF through Ca2+/Calmodulin-dependent kinase and is essential for EGF-mediated Akt activation and biological functions. AMPK phosphorylates Skp2 at S256 and promotes the integrity and E3 ligase activity of Skp2 SCF complex leading to K63-linked ubiquitination and activation of Akt and subsequent oncogenic processes. Importantly, AMPK-mediated Skp2 S256 phosphorylation promotes breast cancer progression in mouse tumor models, correlates with Akt and AMPK activation in breast cancer patients, and predicts poor survival outcomes. Finally, targeting AMPK-mediated Skp2 S256 phosphorylation sensitizes cells to anti-EGF receptor targeted therapy. Our study sheds light on how stress and EGF induce Akt activation and new mechanisms for AMPK-mediated oncogenesis and drug resistance. How Akt pathway is activated under stress is poorly understood. Here, the authors demonstrate the crucial role of AMPK for cellular stresses and growth factors- mediated Akt activation through a mechanism involving the E3 ubiquitin ligase Skp2 and Cullin-1.

As tumor mutational burden (TMB) has been approved as a predictive biomarker for immune checkpoint inhibitors (ICIs), next-generation sequencing (NGS) TMB panels are being increasingly used clinically. However, only a few of them have been validated in clinical trials or authorized by administration. The harmonization and standardization of TMB panels are thus essential for clinical implementation. In this review, preanalytic, sequencing, bioinformatics and interpretative factors are summarized to provide a comprehensive picture of how the different factors affect the estimation of panel-based TMB. Among the factors, poor DNA quality, improper formalin fixation and residual germline variants after filtration may overestimate TMB, while low tumor purity may decrease the sensitivity of the TMB panel. In addition, a small panel size leads to more variability when comparing with true TMB values detected by whole-exome sequencing (WES). A panel covering a genomic region of more than 1Mb is more stable for harmonization and standardization. Because the TMB estimate reflects the sum of effects from multiple factors, deliberation based on laboratory and specimen quality, as well as clinical information, is essential for decision making.

Background Our previous study demonstrated that lysine demethylase 2A (KDM2A) enhances stemness in breast cancer cells. This demethylase is also highly expressed in cancer-associated fibroblasts (CAFs). However, its clinical significance is unclear. Methods The expression of KDM2A in CAFs was studied using immunohistochemical staining and its association with clinicopathological features and patient’s survival was tested. Overexpression and knockdown strategies were used to investigate KDM2A-regulated genes in fibroblasts. Senescent cells were detected by using β-galactosidase staining. The in vivo tumour-promoting activity of stromal KDM2A was confirmed by animal study. Results Increase of stromal KDM2A is associated with advanced tumour stage and poor clinical outcome in breast cancer patients. Cancer-derived cytokines stimulated KDM2A expression in normal fibroblasts and transformed them into CAFs. Upregulation of KDM2A induced p53-dependent senescence in fibroblasts and enhanced the release of cytokines, which reciprocally promoted cancer cell proliferation. Additionally, KDM2A upregulated programmed death-ligand 1 (PD-L1) expression via transcriptional activation in fibroblasts. Knockdown of KDM2A completely abolished the tumour-promoting activity of CAFs on breast tumour growth in vivo and diminished PD-L1 expression in the stroma of tumour tissues. Conclusions Stromal KDM2A plays an oncogenic role in breast cancer and inhibition of KDM2A reduces fibroblast senescence and suppresses tumour growth.

During the evolution into castration or therapy resistance, prostate cancer cells reprogram the androgen responses to cope with the diminishing level of androgens, and undergo metabolic adaption to the nutritionally deprived and hypoxia conditions. AR (androgen receptor) and PKM2 (pyruvate kinase M2) have key roles in these processes. We report in this study, KDM8/JMJD5, a histone lysine demethylase/dioxygnase, exhibits a novel property as a dual coactivator of AR and PKM2 and as such, it is a potent inducer of castration and therapy resistance. Previously, we showed that KDM8 is involved in the regulation of cell cycle and tumor metabolism in breast cancer cells. Its role in prostate cancer has not been explored. Here, we show that KDM8’s oncogenic properties in prostate cancer come from its direct interaction (1) with AR to affect androgen response and (2) with PKM2 to regulate tumor metabolism. The interaction with AR leads to the elevated expression of androgen response genes in androgen-deprived conditions. They include ANCCA/ATAD2 and EZH2, which are directly targeted by KDM8 and involved in sustaining the survival of the cells under hormone-deprived conditions. Notably, in enzalutamide-resistant cells, the expressions of both KDM8 and EZH2 are further elevated, so are neuroendocrine markers. Consequently, EZH2 inhibitors or KDM8 knockdown both resensitize the cells toward enzalutamide. In the cytosol, KDM8 associates with PKM2, the gatekeeper of pyruvate flux and translocates PKM2 into the nucleus, where the KDM8/PKM2 complex serves as a coactivator of HIF-1α to upregulate glycolytic genes. Using shRNA knockdown, we validate KDM8’s functions as a regulator for both androgen-responsive and metabolic genes. KDM8 thus presents itself as an ideal therapeutic target for metabolic adaptation and castration-resistance of prostate cancer cells.

The understanding of how hypoxia stabilizes and activates HIF1α in the nucleus with related oncogenic signals could revolutionize targeted therapy for cancers. Here, we find that histone H2AX displays oncogenic activity by serving as a crucial regulator of HIF1α signalling. H2AX interacts with HIF1α to prevent its degradation and nuclear export in order to allow successful VHL-independent HIF1α transcriptional activation. We show that mono-ubiquitylation and phosphorylation of H2AX, which are strictly mediated by hypoxia-induced E3 ligase activity of TRAF6 and ATM, critically regulate HIF1α-driven tumorigenesis. Importantly, TRAF6 and γH2AX are overexpressed in human breast cancer, correlate with activation of HIF1α signalling, and predict metastatic outcome. Thus, TRAF6 and H2AX overexpression and γH2AX-mediated HIF1α enrichment in the nucleus of cancer cells lead to overactivation of HIF1α-driven tumorigenesis, glycolysis and metastasis. Our findings suggest that TRAF6-mediated mono-ubiquitylation and subsequent phosphorylation of H2AX may serve as potential means for cancer diagnosis and therapy. Lin and colleagues report that hypoxia induces TRAF6-dependent mono-ubiquitylation of histone H2AX, which promotes binding and stabilization of HIF1α. Activated HIF1α signalling in turn promotes tumorigenesis and metastasis.

Changes in TCA cycle enzymes or respiratory activity are possible mechanisms of aerobic glycolysis that contributes to tumor progression. To clarify whether the decrease of succinate dehydrogenase B (SDHB) alters energy metabolism, induces the Warburg effect and results in tumor malignancy, SDHB expression was examined and modulated in hepatocellular carcinoma (HCC) tissues and cells, respectively. SDHB level was often decreased in malignant HCC cells and tissues. Furthermore, the reduced SDHB expression was associated with advanced tumor stage and poor survival rate. Moreover, silencing of SDHB altered energy metabolism switched from aerobic respiration to glycolysis, resulted in the Warburg effect, and enhanced cell proliferation and motility. In contrast, the SDHB overexpression deregulated bioenergetic metabolism and decreased cell growth and migration. In mouse xenograft models, subcutaneous implantation and tail vein injection with SDHB knockdown cells resulted in a larger tumor volume and accelerated cancer metastasis, respectively. A mutation or decrease in SDHB induced the switch from aerobic respiration to glycolysis. This metabolic alteration was associated with tumor cell dedifferentiation, proliferation, motility and overall patient survival in HCC.

Phosphaturic mesenchymal tumors typically cause paraneoplastic osteomalacia, chiefly as a result of FGF23 secretion. In a prior study, we identified FN1–FGFR1 fusion in 9 of 15 phosphaturic mesenchymal tumors. In this study, a total of 66 phosphaturic mesenchymal tumors and 7 tumors resembling phosphaturic mesenchymal tumor but without known phosphaturia were studied. A novel FN1–FGF1 fusion gene was identified in two cases without FN1–FGFR1 fusion by RNA sequencing and cross-validated with direct sequencing and western blot. Fluorescence in situ hybridization analyses revealed FN1–FGFR1 fusion in 16 of 39 (41%) phosphaturic mesenchymal tumors and identified an additional case with FN1–FGF1 fusion. The two fusion genes were mutually exclusive. Combined with previous data, the overall prevalence of FN1–FGFR1 and FN1–FGF1 fusions was 42% (21/50) and 6% (3/50), respectively. FGFR1 immunohistochemistry was positive in 82% (45/55) of phosphaturic mesenchymal tumors regardless of fusion status. By contrast, 121 cases of potential morphologic mimics (belonging to 13 tumor types) rarely expressed FGFR1, the main exceptions being solitary fibrous tumors (positive in 40%), chondroblastomas (40%), and giant cell tumors of bone (38%), suggesting a possible role for FGFR1 immunohistochemistry in the diagnosis of phosphaturic mesenchymal tumor. With the exception of one case reported in our prior study, none of the remaining tumors resembling phosphaturic mesenchymal tumor had either fusion type or expressed significant FGFR1. Our findings provide insight into possible mechanisms underlying the pathogenesis of phosphaturic mesenchymal tumor and imply a central role of the FGF1-FGFR1 signaling pathway. The novel FN1–FGF1 protein is expected to be secreted and serves as a ligand that binds and activates FGFR1 to achieve an autocrine loop. Further study is required to determine the functions of these fusion proteins.

SMARCA4-deficient non-small cell carcinoma is an aggressive neoplasm with poor outcome. Several studies have highlighted its immunochemistry, pathophysiology, and underlying mechanisms, but studies of its definite treatment are few. Here, we report on a 69-year-old male with heterogenous pathological presentations of SMARCA4-deficient non-small cell carcinoma. He initially presented with neck lymphadenopathies. Immunohistochemistry staining and genomic profiling confirmed the diagnosis of SMARCA4-deficient non-small cell carcinoma. The patient responded well to immune checkpoint inhibitors with nivolumab. However, new lesions with various pathological presentations and various responses to nivolumab appeared during the treatment course. The patient survived more than 3 years from the initial diagnosis. This case shows the efficacy of nivolumab to treat SMARCA4-deficient non-small cell lung carcinoma.