The intrinsic mechanisms sensing the imbalance of energy in cells are pivotal for cell survival under various environmental insults. AMP-activated protein kinase (AMPK) serves as a central guardian ...maintaining energy homeostasis by orchestrating diverse cellular processes, such as lipogenesis, glycolysis, TCA cycle, cell cycle progression and mitochondrial dynamics. Given that AMPK plays an essential role in the maintenance of energy balance and metabolism, managing AMPK activation is considered as a promising strategy for the treatment of metabolic disorders such as type 2 diabetes and obesity. Since AMPK has been attributed to aberrant activation of metabolic pathways, mitochondrial dynamics and functions, and epigenetic regulation, which are hallmarks of cancer, targeting AMPK may open up a new avenue for cancer therapies. Although AMPK is previously thought to be involved in tumor suppression, several recent studies have unraveled its tumor promoting activity. The double-edged sword characteristics for AMPK as a tumor suppressor or an oncogene are determined by distinct cellular contexts. In this review, we will summarize recent progress in dissecting the upstream regulators and downstream effectors for AMPK, discuss the distinct roles of AMPK in cancer regulation and finally offer potential strategies with AMPK targeting in cancer therapy.
RLR-mediated type I IFN production plays a pivotal role in elevating host immunity for viral clearance and cancer immune surveillance. Here, we report that glycolysis, which is inactivated during RLR ...activation, serves as a barrier to impede type I IFN production upon RLR activation. RLR-triggered MAVS-RIG-I recognition hijacks hexokinase binding to MAVS, leading to the impairment of hexokinase mitochondria localization and activation. Lactate serves as a key metabolite responsible for glycolysis-mediated RLR signaling inhibition by directly binding to MAVS transmembrane (TM) domain and preventing MAVS aggregation. Notably, lactate restoration reverses increased IFN production caused by lactate deficiency. Using pharmacological and genetic approaches, we show that lactate reduction by lactate dehydrogenase A (LDHA) inactivation heightens type I IFN production to protect mice from viral infection. Our study establishes a critical role of glycolysis-derived lactate in limiting RLR signaling and identifies MAVS as a direct sensor of lactate, which functions to connect energy metabolism and innate immunity.
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•Lactate inhibits RLR-mediated interferon production•This regulation occurs through direct sensing of lactate by MAVS•MAVS associates with hexokinase, but this association is disrupted by RIG-I•Targeting LDHA enhances type I IFN production and viral clearance
Lactate acts as a regulator of the adaptor MAVS, allowing a cross-regulation between antiviral signaling and energy metabolism
Strictly regulated protein degradation by ubiquitin-proteasome system (UPS) is essential for various cellular processes whose dysregulation is linked to serious diseases including cancer. Skp2, a ...well characterized component of Skp2-SCF E3 ligase complex, is able to conjugate both K48-linked ubiquitin chains and K63-linked ubiquitin chains on its diverse substrates, inducing proteasome mediated proteolysis or modulating the function of tagged substrates respectively. Overexpression of Skp2 is observed in various human cancers associated with poor survival and adverse therapeutic outcomes, which in turn suggests that Skp2 engages in tumorigenic activity. To that end, the oncogenic properties of Skp2 are demonstrated by various genetic mouse models, highlighting the potential of Skp2 as a target for tackling cancer. In this article, we will describe the downstream substrates of Skp2 as well as upstream regulators for Skp2-SCF complex activity. We will further summarize the comprehensive oncogenic functions of Skp2 while describing diverse strategies and therapeutic platforms currently available for developing Skp2 inhibitors.
Cancer metastasis accounts for the major cause of cancer-related deaths. How disseminated cancer cells cope with hostile microenvironments in secondary site for full-blown metastasis is largely ...unknown. Here, we show that AMPK (AMP-activated protein kinase), activated in mouse metastasis models, drives pyruvate dehydrogenase complex (PDHc) activation to maintain TCA cycle (tricarboxylic acid cycle) and promotes cancer metastasis by adapting cancer cells to metabolic and oxidative stresses. This AMPK-PDHc axis is activated in advanced breast cancer and predicts poor metastasis-free survival. Mechanistically, AMPK localizes in the mitochondrial matrix and phosphorylates the catalytic alpha subunit of PDHc (PDHA) on two residues S295 and S314, which activates the enzymatic activity of PDHc and alleviates an inhibitory phosphorylation by PDHKs, respectively. Importantly, these phosphorylation events mediate PDHc function in cancer metastasis. Our study reveals that AMPK-mediated PDHA phosphorylation drives PDHc activation and TCA cycle to empower cancer cells adaptation to metastatic microenvironments for metastasis.
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•AMPKα facilitates TCA cycle by maintaining PDH complex activity•AMPKα phosphorylates PDHA subunit on Ser295 and Ser314 to activate PDH complex•Activation of AMPKα-PDHA axis promotes tumor lung metastasis•AMPKα-PDHA axis predicts poor metastasis-free survival in breast cancer patients
Cai et al. demonstrate that phosphorylation of the catalytic subunit PDHA on Ser295 and S314 by AMPKα is essential for the maintenance of pyruvate dehydrogenase complex activity and TCA cycle. Activation of AMPKα-PDHA axis predicts poor metastasis-free survival in breast cancer patients and facilitates tumor lung metastasis.
Sentinel lymph node biopsy (SLNB) provides important prognostic information for early‐stage melanomas. However, statistics regarding the survival comparison between SLNB and nodal observation in ...Asia, where acral lentiginous melanoma (ALM) predominates, are limited. This study aimed to identify if SLNB offered survival benefits over nodal observation in early‐stage melanomas in Taiwan. The retrospective study included 227 patients who met the SLNB criteria according to the National Comprehensive Cancer Network guidelines and were treated at National Taiwan University Hospital from June 1997 to June 2021. Survival analysis was performed using Kaplan–Meier curves and Cox proportional hazards regression models. Of the study population, ALM accounted for 73.1%; 161 patients (70.9%) underwent SLNB and 66 patients (29.1%) were under nodal observation. Multivariate analysis showed significantly improved melanoma‐specific survival (hazard ratio HR, 0.6; p = .02) in the SLNB group. Among those who underwent completion lymph node dissection (CLND), the non‐sentinel node positivity rate was 44.4%. Immediate CLND resulted in significantly longer melanoma‐specific survival and distant‐metastasis‐free survival (DMFS) compared to nodal observation. (HR, 0.2; p = .01 for melanoma‐specific survival. HR, 0.3; p = .046 for DMFS). In conclusion, SLNB may provide survival benefits of cutaneous melanoma over nodal observation in the Taiwanese population.
Research Highlights
The sentinel lymph node biopsy group demonstrated a superior melanoma‐specific survival compared to the nodal observation group. This observation may be related to the higher prevalence of acral lentiginous melanomas in the Asian population.
The serine/threonine kinase Akt plays a central role in cell proliferation, survival and metabolism, and its hyperactivation is linked to cancer progression. Here we report that Akt undergoes K64 ...methylation by SETDB1, which is crucial for cell membrane recruitment, phosphorylation and activation of Akt following growth factor stimulation. Furthermore, we reveal an adaptor function of histone demethylase JMJD2A, which is important for recognizing Akt K64 methylation and recruits E3 ligase TRAF6 and Skp2-SCF to the Akt complex, independently of its demethylase activity, thereby initiating K63-linked ubiquitination, cell membrane recruitment and activation of Akt. Notably, the cancer-associated Akt mutant E17K displays enhanced K64 methylation, leading to its hyper-phosphorylation and activation. SETDB1-mediated Akt K64 methylation is upregulated and correlated with Akt hyperactivation in non-small-cell lung carcinoma (NSCLC), promotes tumour development and predicts poor outcome. Collectively, these findings reveal complicated layers of Akt activation regulation coordinated by SETDB1-mediated Akt K64 methylation to drive tumorigenesis.
Background: Mapping disease rates is an important aspect of epidemiological research because it helps inform public health policy. Disease maps are often drawn according to local administrative areas ...(LAAs), such as counties, cities, or towns. In LAAs with small populations, disease rates are unstable and are prone to appear extremely high or low. The empirical Bayes methods consider variance differences among different LAAs, thereby stabilizing the disease rates. The methods of kriging break the constraints of geopolitical boundaries and produce a smooth curved surface in the form of contour lines, but the methods lack the stabilizing effect of the empirical Bayes methods.Methods: An easy-to-implement stabilized kriging method is proposed to map disease rates, which allows different errors in different LAAs.Results: Monte Carlo simulations revealed that the stabilized kriging method had smaller symmetric mean absolute percentage error than three other types of methods (original LAA-based method, empirical Bayes methods, and traditional kriging methods) in nearly all scenarios considered. Real-world data analysis of oral cancer incidence rates in men from Taiwan demonstrated that the age-standardized rates in the central mountainous sparsely-populated region of Taiwan were stabilized using our proposed method, with no more large differences in numerical values, whereas the rates in other populous regions were not over smoothed. Additionally, the stabilized kriging map had improved resolution and helped locate several hot and cold spots in the incidence rates of oral cancer.Conclusions: We recommend the use of the stabilized kriging method for mapping disease rates.
Bladder cancer is the leading urinary tract malignancy. Epidemiological evidence has linked lower cancer incidence in schizophrenia patients to long-term medication, highlighting the anticancer ...potential of antipsychotics. Sertindole is an atypical antipsychotic agent with reported anticancer action on breast and gastric cancers. Yet, sertindole's effect on bladder cancer remains unaddressed. We herein present the first evidence of sertindole's antiproliferative effect and mechanisms of action on human bladder cancer cells. Sertindole was cytotoxic against bladder cancer cells while less cytotoxic to normal urothelial cells. Apoptosis was a primary cause of sertindole's cytotoxicity, as the pan-caspase inhibitor z-VAD-fmk rescued cells from sertindole-induced killing. Mechanistically, sertindole inhibited the activation of signal transducer and activator of transcription 3 (STAT3), an oncogenic driver of bladder cancer, as sertindole lowered the levels of tyrosine 705-phosphorylated STAT3 along with that of STAT3's target gene BCL-xL. Notably, ectopic expression of the dominant-active STAT3 mutant impaired sertindole-induced apoptosis in addition to restoring BCL-xL expression. Moreover, bladder cancer cells overexpressing BCL-xL were refractory to sertindole's proapoptotic action, arguing that sertindole represses STAT3 to downregulate BCL-xL, culminating in the induction of apoptosis. Overall, the current study indicated sertindole exerts bladder cancer cytotoxicity by provoking apoptosis through targeted inhibition of the antiapoptotic STAT3/BCL-xL signaling axis. These findings implicate the potential to repurpose sertindole as a therapeutic strategy for bladder cancer.
Abstract
Background
Glioblastoma is associated with poor prognosis and high mortality. Although the use of first-line temozolomide can reduce tumor growth, therapy-induced stress drives stem cells ...out of quiescence, leading to chemoresistance and glioblastoma recurrence. The specificity protein 1 (Sp1) transcription factor is known to protect glioblastoma cells against temozolomide; however, how tumor cells hijack this factor to gain resistance to therapy is not known.
Methods
Sp1 acetylation in temozolomide-resistant cells and stemlike tumorspheres was analyzed by immunoprecipitation and immunoblotting experiments. Effects of the histone deacetylase (HDAC)/Sp1 axis on malignant growth were examined using cell proliferation–related assays and in vivo experiments. Furthermore, integrative analysis of gene expression with chromatin immunoprecipitation sequencing and the recurrent glioblastoma omics data were also used to further determine the target genes of the HDAC/Sp1 axis.
Results
We identified Sp1 as a novel substrate of HDAC6, and observed that the HDAC1/2/6/Sp1 pathway promotes self-renewal of malignancy by upregulating B cell-specific Mo-MLV integration site 1 (BMI1) and human telomerase reverse transcriptase (hTERT), as well as by regulating G2/M progression and DNA repair via alteration of the transcription of various genes. Importantly, HDAC1/2/6/Sp1 activation is associated with poor clinical outcome in both glioblastoma and low-grade gliomas. However, treatment with azaindolyl sulfonamide, a potent HDAC6 inhibitor with partial efficacy against HDAC1/2, induced G2/M arrest and senescence in both temozolomide-resistant cells and stemlike tumorspheres.
Conclusion
Our study uncovers a previously unknown regulatory mechanism in which the HDAC6/Sp1 axis induces cell division and maintains the stem cell population to fuel tumor growth and therapeutic resistance.
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