New insights into molecular chaperone TRAP1 as a feasible target for future cancer treatments

Small molecule inhibitors targeting heat shock protein 90: An updated review

As a molecular chaperone, heat shock protein 90 (HSP90) plays important roles in the folding, stabilization, activation, and degradation of over 500 client proteins, and is extensively involved in cell signaling, proliferation, and survival. Thus, it has emerged as an important target in a variety of diseases, including cancer, neurodegenerative diseases, and viral infections. Therefore, targeted inhibition of HSP90 provides a valuable and promising therapeutic strategy for the treatment of HSP90-related diseases. This review aims to systematically summarize the progress of research on HSP90 inhibitors in the last five years, focusing on their structural features, design strategies, and biological activities. It will refer to the natural products and their derivatives (including novobiocin derivatives, deguelin derivatives, quinone derivatives, and terpenoid derivatives), and to synthetic small molecules (including resorcinol derivatives, pyrazoles derivatives, triazole derivatives, pyrimidine derivatives, benzamide derivatives, benzothiazole derivatives, and benzofuran derivatives). In addition, the major HSP90 small-molecule inhibitors that have moved into clinical trials to date are also presented here.

Impact of climate factors and climate-gene interaction on systemic lupus erythematosus patients' response to glucocorticoids therapy

BACKGROUND

Glucocorticoids (GCs) were the essential drugs for systemic lupus erythematosus (SLE). However, different patients differ substantially in their response to GCs treatment. Our current study aims at investigating whether climate variability and climate-gene interaction influence SLE patients' response to the therapy of GCs.

METHODS

In total, 778 SLE patients received therapy of GCs for a study of 12-week follow-up. The efficacy of GCs treatment was evaluated using the Systemic Lupus Erythematosus Disease Activity Index. The climatic data were provided by China Meteorological Data Service Center. Additive and multiplicative interactions were examined.

RESULTS

Compared with patients with autumn onset, the efficacy of GCs in patients with winter onset is relatively poor (ORadj  = 1.805, 95%CIadj : 1.181-3.014, padj  = 0.020). High mean relative humidity during treatment decreased the efficacy of GCs (ORadj  = 1.033, 95%CIadj : 1.008-1.058, padj  = 0.011), especially in female (ORadj  = 1.039, 95%CIadj : 1.012-1.067, padj  = 0.004). There was a significant interaction between sunshine during treatment and TRAP1 gene rs12597773 on GCs efficacy (Recessive model: AP = 0.770). No evidence of significant interaction was found between climate factors and the GR gene polymorphism on the improved GCs efficacy in the additive model. Multiplicative interaction was found between humidity in the month prior to treatment and GR gene rs4912905 on GCs efficacy (Dominant model: OR = 0.470, 95%CI: 0.244-0.905, p = 0.024).

CONCLUSIONS

Our findings suggest that climate variability influences SLE patients' response to the therapy of GCs. Interactions between climate and TRAP1/GR gene polymorphisms were related to GCs efficacy. The results guide the individualized treatment of SLE patients.

Proteomic analysis of epicardial adipose tissue from heart disease patients with concomitant heart failure with preserved ejection fraction

BACKGROUND

Although epicardial adipose tissue (EAT) is known to be a major contributor to the pathogenesis of heart failure with preserved ejection fraction (HFpEF), the underlying mechanisms remain incompletely understood. This study aimed to compare the proteomic profiles of EAT from HFpEF patients and patients without HF (non-HF) and to explore candidate molecules characteristic of EAT in HFpEF.

METHODS

EAT samples were collected from patients who underwent cardiac surgery. Proteins were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and protein-protein interaction network analysis were conducted. The gene expression of one significant differentially expressed protein was examined by quantitative reverse transcription polymerase chain reaction.

RESULTS

A total of 2416 proteins were detected by LC-MS/MS experiments, and expression levels were quantified for 2349 proteins. Among them, 96 proteins (including 71 upregulated proteins and 25 downregulated proteins) were significantly differentially expressed between the HFpEF (n = 5) and non-HF groups (n = 5). GO enrichment and KEGG pathway analyses revealed that these differentially expressed proteins were predominantly involved in HFpEF-related processes, including lipid metabolic disorder, inflammation, and mitochondrial dysfunction.

CONCLUSIONS

The results of this comprehensive analysis of the EAT proteome in HFpEF patients offer new insights into the pathogenesis of HFpEF and potential molecular targets in EAT.

Toxicokinetics of Arenobufagin and its Cardiotoxicity Mechanism Exploration Based on Lipidomics and Proteomics Approaches in Rats

Arenobufagin (ArBu), one of the main active bufadienolides of toad venom with cardiotonic effect, analgesic effect, and outstanding anti-tumor potentiality, is also a potential cardiotoxic component. In the present study, the cardiac effect of ArBu and its underlying mechanism were explored by integrating data such as heart rates, toxicokinetics, myocardial enzyme and brain natriuretic peptide (BNP) activity, pathological sections, lipidomics and proteomics. Under different doses, the cardiac effects turned out to be different. The oral dose of 60 mg/kg of ArBu sped up the heart rate. However, 120 mg/kg ArBu mainly reduced the heart rate. Over time, they all returned to normal, consisting of the trend of ArBu concentration-time curve. High concentrations of myocardial enzymes and BNP indicated that ArBu inhibited or impaired the cardiac function of rats. Pathological sections of hearts also showed that ArBu caused myocardial fiber disorder and rupture, in which the high-dose group was more serious. At the same time, serum and heart tissue lipidomics were used to explore the changes in body lipid metabolism under different doses. The data indicated a larger difference in the high-dose ArBu group. There were likewise many significant differences in the proteomics of the heart. Furthermore, a multi-layered network was used to integrate the above information to explore the potential mechanism. Finally, 4 proteins that were shown to be significantly and differentially expressed were validated by targeted proteomics using parallel reaction monitoring (PRM) analysis. Our findings indicated that ArBu behaved as a bidirectional regulation of the heart. The potential mechanism of cardiac action was revealed with the increased dose, which provided a useful reference for the safety of clinical application of ArBu.

Luteolin potentiates low-dose oxaliplatin-induced inhibitory effects on cell proliferation in gastric cancer by inducing G2/M cell cycle arrest and apoptosis

Although the reduction of oxaliplatin doses may alleviate deleterious side effects of gastrointestinal and gynecological cancer treatment, it also limits the anticancer therapeutic effects. As a high-efficient and low-priced herbal medicine ingredient, luteolin is an agent with a broad spectrum of anticancer activities and acts as a potential enhancer of therapeutic effects of chemotherapy agents in cancer treatment. This study focused on the antitumor effects and mechanism of combined treatment with luteolin and oxaliplatin on a mouse forestomach carcinoma (MFC) cell line. The study used CCK-8 assay, flow cytometry, Annexin V-FITC/PI double staining assay, reactive oxygen species testing assay, mitochondrial membrane potential testing assay, and western blot assay. The results showed that luteolin and oxaliplatin exerted synergistic effects on inhibiting MFC cell proliferation by inducing G₂/M cell cycle arrest and apoptosis. Inhibiting the tumor necrosis factor receptor-associated protein 1/phosphorylated-extracellular-regulated protein kinases1/2/cell division cycle 25 homolog C/cyclin-dependent kinase-1/cyclin B1 pathway was indispensable to the combined treatment with luteolin and oxaliplatin to induce G₂/M cell cycle arrest. In addition, luteolin increased oxidative stress in MFC cells treated with a low dose of oxaliplatin. The combined therapy damaged mitochondrial membrane potential and regulated BCL-2-associated X protein and B-cell lymphoma 2 protein expression, leading to apoptosis. Findings of the present study suggest that luteolin may be a qualified chemotherapy enhancer to potentiate the anticancer effects of low-dose oxaliplatin in MFC cells. This work provides a theoretical foundation for future research on applications of luteolin in clinical chemotherapy.

TRAP1 in Oxidative Stress and Neurodegeneration

Tumor necrosis factor receptor-associated protein 1 (TRAP1), also known as heat shock protein 75 (HSP75), is a member of the heat shock protein 90 (HSP90) chaperone family that resides mainly in the mitochondria. As a mitochondrial molecular chaperone, TRAP1 supports protein folding and contributes to the maintenance of mitochondrial integrity even under cellular stress. TRAP1 is a cellular regulator of mitochondrial bioenergetics, redox homeostasis, oxidative stress-induced cell death, apoptosis, and unfolded protein response (UPR) in the endoplasmic reticulum (ER). TRAP1 has attracted increasing interest as a therapeutical target, with a special focus on the design of TRAP1 specific inhibitors. Although TRAP1 was extensively studied in the oncology field, its role in central nervous system cells, under physiological and pathological conditions, remains largely unknown. In this review, we will start by summarizing the biology of TRAP1, including its structure and related pathways. Thereafter, we will continue by debating the role of TRAP1 in the maintenance of redox homeostasis and protection against oxidative stress and apoptosis. The role of TRAP1 in neurodegenerative disorders will also be discussed. Finally, we will review the potential of TRAP1 inhibitors as neuroprotective drugs.

Mitochondrial Metabolism in Melanoma

Melanoma and its associated alterations in cellular pathways have been growing areas of interest in research, especially as specific biological pathways are being elucidated. Some of these alterations include changes in the mitochondrial metabolism in melanoma. Many mitochondrial metabolic changes lead to differences in the survivability of cancer cells and confer resistance to targeted therapies. While extensive work has gone into characterizing mechanisms of resistance, the role of mitochondrial adaptation as a mode of resistance is not completely understood. In this review, we wish to explore mitochondrial metabolism in melanoma and how it impacts modes of resistance. There are several genes that play a major role in melanoma mitochondrial metabolism which require a full understanding to optimally target melanoma. These include BRAF, CRAF, SOX2, MCL1, TRAP1, RHOA, SRF, SIRT3, PTEN, and AKT1. We will be discussing the role of these genes in melanoma in greater detail. An enhanced understanding of mitochondrial metabolism and these modes of resistance may result in novel combinatorial and sequential therapies that may lead to greater therapeutic benefit.

Intrinsic OXPHOS limitations underlie cellular bioenergetics in leukemia

Currently there is great interest in targeting mitochondrial oxidative phosphorylation (OXPHOS) in cancer. However, notwithstanding the targeting of mutant dehydrogenases, nearly all hopeful 'mito-therapeutics' cannot discriminate cancerous from non-cancerous OXPHOS and thus suffer from a limited therapeutic index. Using acute myeloid leukemia (AML) as a model, herein, we leveraged an in-house diagnostic biochemical workflow to identify 'actionable' bioenergetic vulnerabilities intrinsic to cancerous mitochondria. Consistent with prior reports, AML growth and proliferation was associated with a hyper-metabolic phenotype which included increases in basal and maximal respiration. However, despite having nearly 2-fold more mitochondria per cell, clonally expanding hematopoietic stem cells, leukemic blasts, as well as chemoresistant AML were all consistently hallmarked by intrinsic OXPHOS limitations. Remarkably, by performing experiments across a physiological span of ATP free energy, we provide direct evidence that leukemic mitochondria are particularly poised to consume ATP. Relevant to AML biology, acute restoration of oxidative ATP synthesis proved highly cytotoxic to leukemic blasts, suggesting that active OXPHOS repression supports aggressive disease dissemination in AML. Together, these findings argue against ATP being the primary output of leukemic mitochondria and provide proof-of-principle that restoring, rather than disrupting, OXPHOS may represent an untapped therapeutic avenue for combatting hematological malignancy and chemoresistance.

Hypoxia-Induced Cancer Cell Responses Driving Radioresistance of Hypoxic Tumors: Approaches to Targeting and Radiosensitizing

Simple Summary

Some regions of aggressive malignancies experience hypoxia due to inadequate blood supply. Cancer cells adapting to hypoxic conditions somehow become more resistant to radiation exposure and this decreases the efficacy of radiotherapy toward hypoxic tumors. The present review article helps clarify two intriguing points: why hypoxia-adapted cancer cells turn out radioresistant and how they can be rendered more radiosensitive. The critical molecular targets associated with intratumoral hypoxia and various approaches are here discussed which may be used for sensitizing hypoxic tumors to radiotherapy.

Abstract

Within aggressive malignancies, there usually are the “hypoxic zones”—poorly vascularized regions where tumor cells undergo oxygen deficiency through inadequate blood supply. Besides, hypoxia may arise in tumors as a result of antiangiogenic therapy or transarterial embolization. Adapting to hypoxia, tumor cells acquire a hypoxia-resistant phenotype with the characteristic alterations in signaling, gene expression and metabolism. Both the lack of oxygen by itself and the hypoxia-responsive phenotypic modulations render tumor cells more radioresistant, so that hypoxic tumors are a serious challenge for radiotherapy. An understanding of causes of the radioresistance of hypoxic tumors would help to develop novel ways for overcoming this challenge. Molecular targets for and various approaches to radiosensitizing hypoxic tumors are considered in the present review. It is here analyzed how the hypoxia-induced cellular responses involving hypoxia-inducible factor-1, heat shock transcription factor 1, heat shock proteins, glucose-regulated proteins, epigenetic regulators, autophagy, energy metabolism reprogramming, epithelial–mesenchymal transition and exosome generation contribute to the radioresistance of hypoxic tumors or may be inhibited for attenuating this radioresistance. The pretreatments with a multitarget inhibition of the cancer cell adaptation to hypoxia seem to be a promising approach to sensitizing hypoxic carcinomas, gliomas, lymphomas, sarcomas to radiotherapy and, also, liver tumors to radioembolization.

Heat Diffusion Kernel Algorithm-Based Interpretation of the Disease Intervention Mechanism for DHA

Docosahexaenoic acid (DHA) is effective in the prevention and treatment of cancer, congenital disorders, and various chronic diseases. According to the omnigenic hypothesis, these complex diseases are caused by disordered gene regulatory networks comprising dozens to hundreds of core genes and a mass of peripheral genes. However, conventional research on the disease intervention mechanism of DHA only focused on specific types of genes or pathways instead of examining genes at the network level, resulting in conflicting conclusions. In this study, we used HotNet2, a heat diffusion kernel algorithm, to calculate the gene regulatory networks of connectivity map (cMap)-derived agents (including DHA) based on gene expression profiles, aiming to interpret the disease intervention mechanism of DHA at the network level. As a result, significant gene regulatory networks for DHA and 676 cMap-derived agents were identified respectively. The biological functions of the DHA-regulated gene network provide preliminary insights into the mechanism by which DHA intervenes in disease. In addition, we compared the gene regulatory networks of DHA with those of cMap-derived agents, which allowed us to predict the pharmacological effects and disease intervention mechanism of DHA by analogy with similar agents with clear indications and mechanisms. Some of our analysis results were supported by experimental observations. Therefore, this study makes a significant contribution to research on the disease intervention mechanism of DHA at the regulatory network level, demonstrating the potential application value of this methodology in clarifying the mechanisms about nutrients influencing health.