Vosaroxin induces mitochondrial dysfunction and apoptosis in cervical cancer HeLa cells: Involvement of AMPK/Sirt3/HIF-1 pathway

Sirtuin insights: bridging the gap between cellular processes and therapeutic applications

The greatest challenges that organisms face today are effective responses or detection of life-threatening environmental changes due to an obvious semblance of stress and metabolic fluctuations. These are associated with different pathological conditions among which cancer is most important. Sirtuins (SIRTs; NAD+-dependent enzymes) are versatile enzymes with diverse substrate preferences, cellular locations, crucial for cellular processes and pathological conditions. This article describes in detail the distinct roles of SIRT isoforms, unveiling their potential as either cancer promoters or suppressors and also explores how both natural and synthetic compounds influence the SIRT function, indicating promise for therapeutic applications. We also discussed the inhibitors/activators tailored to specific SIRTs, holding potential for diseases lacking effective treatments. It may uncover the lesser-studied SIRT isoforms (e.g., SIRT6, SIRT7) and their unique functions. This article also offers a comprehensive overview of SIRTs, linking them to a spectrum of diseases and highlighting their potential for targeted therapies, combination approaches, disease management, and personalized medicine. We aim to contribute to a transformative era in healthcare and innovative treatments by unraveling the intricate functions of SIRTs.

Antineoplastic agents associated with neutropenic enterocolitis in patients with malignancy: A quantitative safety signal analysis

BACKGROUND

The use of certain chemotherapy agents is associated with the development of a condition called "chemotherapy-associated neutropenic enterocolitis" (CANE).

OBJECTIVE

To determine the risk of CANE associated with the use of each antineoplastic agent.

METHODS

The FDA FAERS database of spontaneous adverse reactions was searched for the occurrence of the MedDRA preferred term "neutropenic colitis."

RESULTS

The search resulted in 1134 records of patients (535 [47.3%] females, 479 [42.2%] males, sex not specified in 120 [10.6%]) with neutropenic colitis receiving immunosuppressive chemotherapy. The mean age of patients was 47 (SD 22). 22 antineoplastic agents were found to have a strong association (reported odds ratio [ROR] > 100) with the occurrence of CANE; 9 had ROR < 2.

CONCLUSION

Drug databases have several limitations in providing updated information about newly approved pharmaceutical adverse events. Signal detection is a diagnostic method recognized as practical in pharmacovigilance. It may be utilized in the FDA's adverse event reporting database and has demonstrated a reasonable predictive performance in signaling adverse events. Our study emphasized the substantial knowledge gap between what we know about the potential risk of CANE caused by antineoplastic agents and the reports of the FDA on their new approved products.

Effect of miR-182-5p on apoptosis in myocardial infarction

Objective

This study aimed to delineate the diagnostic significance of miR-182-5p by investigating its influence on myocardial apoptosis and function, employing both in vivo and in vitro myocardial infarction models.

Methods

A rat myocardial infarction model was established. Myocardial infarction area was detected using the 2,3,5-chlorotriphenyltetrazolium (TTC) method, myocardial enzyme spectrums were measured using enzyme-linked immunosorbent assay (ELISA), myocardial structure was detected by hematoxylin and eosin (HE) staining, myocardial apoptosis was detected using the TUNEL method, and expression levels of miR-182-5p and apoptosis-related molecules were detected using real-time fluorescence quantitative PCR (qPCR) and Western blot. miR-182-5p mimics and inhibitor were transfected into rat H9C2 cardiomyocytes and mouse HL-1 cardiomyocytes to establish a hypoxia model. Cardiomyocyte viability was detected using the CCK-8 method, expression levels of apoptosis-related indicators were detected using Western blot, and caspase-3/7 activity was detected using a caspase-3/7 activity detection kit. AAV9 adeno-associated virus was used to construct an miR-182-5p overexpression virus, which was injected into mice through the tail vein to create a mouse myocardial infarction model. TTC, ELISA, HE staining, echocardiography, real-time fluorescence qPCR, and Western blot methods were used to detect the effects of AAV9-miR-182-5p on myocardial injury, myocardial function, and myocardial apoptosis levels in myocardial infarction.

Results

The rat model displayed reduced miR-182-5p expression concurrent with an increase in apoptosis. The in vitro H9C2 and HL-1 hypoxia models revealed that miR-182-5p augmented the hypoxia-induced decrease in myocardial cell viability, suppressed Bcl-2 expression, and increased Bax, Bnip3, and caspase-3/7 activity levels. The injection of AAV9-miR-182-5p significantly exacerbated myocardial tissue damage, impaired myocardial function, and enhanced apoptosis.

Conclusion

miR-182-5p escalates myocardial injury during myocardial infarction by fostering apoptosis. Interventions that aim to reduce miR-182-5p levels might be crucial in halting the progression of myocardial infarction.

Double C-2 like domain beta (DOC2B) induces calcium dependent oxidative stress to promote lipotoxicity and mitochondrial dysfunction for its tumor suppressive function

Mitochondria are biosynthetic and bioenergetic organelles that regulate many biological processes, including metabolism, oxidative stress, and cell death. Cervical cancer (CC) cells show impairments in mitochondrial structure and function and are linked with cancer progression. DOC2B is a tumor suppressor with anti-proliferative, anti-migratory, anti-invasive, and anti-metastatic function in CC. For the first time, we demonstrated the role of the DOC2B-mitochondrial axis with tumor growth regulatory functions in CC. We used DOC2B overexpression and knockdown model systems to show that DOC2B is localized to mitochondria and induces Ca²⁺-mediated lipotoxicity. DOC2B expression induced mitochondrial morphological changes with the subsequent reduction in mitochondrial DNA copy number, mitochondrial mass, and mitochondrial membrane potential. Intracellular and mitochondrial Ca²⁺, intracellular O^.-₂, and ATP levels were substantially elevated in the presence of DOC2B. DOC2B manipulation reduced glucose uptake, lactate production, and mitochondrial complex-IV activity. The presence of DOC2B significantly reduced the proteins associated with mitochondrial structure and biogenesis with the concomitant activation of AMPK signaling. Augmented lipid peroxidation (LPO) in the presence of DOC2B was a Ca²⁺-dependent process. Our findings demonstrated that DOC2B promotes lipid accumulation, oxidative stress, and LPO through intracellular Ca²⁺ overload, which may contribute to mitochondrial dysfunction and tumor-suppressive properties of DOC2B. We propose that the DOC2B-Ca²⁺-oxidative stress-LPO-mitochondrial axis could be targeted for confining CC. Further, the induction of lipotoxicity in tumor cells by activating DOC2B could serve as a novel therapeutic approach in CC.

TRPM7 silencing modulates glucose metabolic reprogramming to inhibit the growth of ovarian cancer by enhancing AMPK activation to promote HIF-1α degradation

BACKGROUND

Tumor cell metabolic reprogramming is crucial for the malignant behavior of cancer cells by promoting their proliferation. However, little is known on how transient receptor potential 7 (TRPM7) modulates metabolic reprogramming in ovarian cancer.

METHODS

The effects of TRPM7 silencing on transcriptome profile, glucose uptake, lactic acid production, extracellular acidification rate (ECAR), oxygen consumption rate (OCR), intracellular ROS and ATP levels, and NAD+/NADH ratios in ovarian cancer cells were examined. The impacts of TRPM7 silencing on the levels of glycolysis-related HK2, PDK1 and oxidative phosphorylation (OXPHOS)-related IDH3B and UQCRC1, HIF-1α expression and AMPK phosphorylation were determined in ovarian cancer. The effect of AMPK activity on HIF-1α ubiquitination degradation was investigated in ovarian cancer cells.

RESULTS

Compared with the control, TRPM7 silencing suppressed the proliferation of ovarian cancer cells by shifting preferable glycolysis to OXPHOS. In parallel, TRPM7 silencing decreased the glucose uptake of tumor-bearing mice and TRPM7 levels were negatively correlated with IDH3B and UQCRC1, but positively with HK2 and PDK1 expression in ovarian cancer tissues. Mechanistically, TRPM7 silencing significantly increased AMPK phosphorylation and decreased HIF-1α protein levels in ovarian cancer, particularly in HIF-1α silencing cells. The shifting from glycolysis to OXPHOS by TRPM7 silencing was abrogated by HIF-1α over-expression and impaired by inhibiting AMPK activity in ovarian cancer cells. Moreover, enhanced AMPK activation inhibited glycolysis, which was abrogated by HIF-1α over-expression in ovarian cancer cells. Moreover, the enhanced AMPK activation promoted HIF-1α ubiquitination degradation.

CONCLUSIONS

TRPM7 silencing enhanced AMPK activation to shift glycolysis to oxidative phosphorylation by promoting HIF-1α ubiquitination degradation in ovarian cancer. Hence, TRPM7 may be a therapeutic target for intervention of ovarian cancer.

Bioinformatic Analysis of the Effect of the Sirtuin Family on Differentiated Thyroid Carcinoma

A growing body of experimental evidence suggests that sirtuins (SIRTs) are associated with tumorigenesis in differentiated thyroid cancer (DTC). Nevertheless, the involvement of SIRTs in the pathogenesis of DTC and their clinical value remain ill-defined and should be thoroughly examined. We explored the transcription of SIRTs and survival data of patients with DTC by the systematic utilization of bioinformatics to analyze data of publicly accessible databases including Oncomine, cBioPortal, Kaplan-Meier Plotter, Gene Expression Profiling Interactive Analysis (GEPIA), Protein Atlas, LinkedOmics, and GSCALite. The examination of gene expression profiles showed that SIRT2, SIRT3, SIRT4, SIRT5, and SIRT6 were downregulated in DTC tissues compared with the normal thyroid tissues. The decreased expression levels of SIRT2, SIRT4, and SIRT5 were correlated with advanced tumor stages. The survival results showed that the increased SIRT4 mRNA expression level was associated with improved overall survival (OS) in the DTC patients. In addition, patients with DTC with high SIRT2, SIRT3, SIRT4, and SIRT5 mRNA levels had higher disease-free survival (DFS). These results showed that SIRT2, SIRT3, SIRT4, SIRT5, and SIRT6 are potential targets for precise treatment of DTC patients and that SIRT2, SIRT3, SIRT4, and SIRT5 are novel potential biomarkers for the prognosis of DTC.

The Biochemical and Molecular Analysis of Changes in Melanogenesis Induced by UVA-Activated Fluoroquinolones-In Vitro Study on Human Normal Melanocytes

Fluoroquinolones cause phototoxic reactions, manifested as different types of skin lesions, including hyperpigmentation. The disturbances of melanogenesis indicate that fluoroquinolones may affect cellular processes in melanocytes. It has been reported that these antibiotics may bind with melanin and accumulate in pigmented cells. The study aimed to examine the changes in melanogenesis in human normal melanocytes exposed to UVA radiation and treated with lomefloxacin and moxifloxacin, the most and the least fluoroquinolone, respectively. The obtained results demonstrated that both tested fluoroquinolones inhibited melanogenesis through a decrease in tyrosinase activity and down-regulation of tyrosinase and microphthalmia-associated transcription factor production. Only lomefloxacin potentiated UVA-induced melanogenesis. Under UVA irradiation lomefloxacin significantly enhanced melanin content and tyrosinase activity in melanocytes, although the drug did not cause an increased expression of tyrosinase or microphthalmia-associated transcription factor. The current studies revealed that phototoxic activity of fluoroquinolones is associated with alterations in the melanogenesis process. The difference in phototoxic potential of fluoroquinolones derivatives may be connected with various effects on UVA-induced events at a cellular level.

An Overview of Novel Agents for Cervical Cancer Treatment by Inducing Apoptosis: Emerging Drugs Ongoing Clinical Trials and Preclinical Studies

As the leading cause of cancer death, cervical cancer ranks fourth for both incidence and mortality. Cervical cancer incidence and mortality rates have reportedly decreased over the last decades thanks to extensive screening and widespread vaccination against human papilloma virus. However, there have been no major improvements concerning platinum-based chemotherapy on the survival of advanced cervical cancer. Thus, novel agents are urgently needed for the improvement of therapeutic effect. With the development of molecular biology and genomics, targeted therapy research has achieved a breakthrough development, including anti-angiogenesis, immune checkpoint inhibitors, and other treatments that are efficient for treatment of cervical cancer. Apoptosis is a crucial process for tumor progression. Drugs directed at inducing tumor-cell apoptosis are regarded as important treatment modalities. Besides, a number of novel compounds synthesized or derived from plants or microorganisms exhibited prominent anti-cancer activity by changing the apoptotic balance in cervical cancer. In this review, we summarized new target therapy drugs ongoing clinical trials that are used for treatment of cervical cancer. Further, we classified novel agents with a focus on improvement of therapeutic effect pre-clinically. To summarize, we also discussed application prospects of the new uses of old drugs and drug combinations, to provide researchers with new ideas for cervical cancer treatment.

The crosstalk between HIFs and mitochondrial dysfunctions in cancer development

Mitochondria are essential cellular organelles that are involved in regulating cellular energy, metabolism, survival, and proliferation. To some extent, cancer is a genetic and metabolic disease that is closely associated with mitochondrial dysfunction. Hypoxia-inducible factors (HIFs), which are major molecules that respond to hypoxia, play important roles in cancer development by participating in multiple processes, such as metabolism, proliferation, and angiogenesis. The Warburg phenomenon reflects a pseudo-hypoxic state that activates HIF-1α. In addition, a product of the Warburg effect, lactate, also induces HIF-1α. However, Warburg proposed that aerobic glycolysis occurs due to a defect in mitochondria. Moreover, both HIFs and mitochondrial dysfunction can lead to complex reprogramming of energy metabolism, including reduced mitochondrial oxidative metabolism, increased glucose uptake, and enhanced anaerobic glycolysis. Thus, there may be a connection between HIFs and mitochondrial dysfunction. In this review, we systematically discuss the crosstalk between HIFs and mitochondrial dysfunctions in cancer development. Above all, the stability and activity of HIFs are closely influenced by mitochondrial dysfunction related to tricarboxylic acid cycle, electron transport chain components, mitochondrial respiration, and mitochondrial-related proteins. Furthermore, activation of HIFs can lead to mitochondrial dysfunction by affecting multiple mitochondrial functions, including mitochondrial oxidative capacity, biogenesis, apoptosis, fission, and autophagy. In general, the regulation of tumorigenesis and development by HIFs and mitochondrial dysfunction are part of an extensive and cooperative network.

Design, synthesis and biological evaluation of 7H-pyrrolo[2,3-d]pyrimidine derivatives containing 1,8-naphthyridine-4-one fragment

In this study, a series of pyrrolo [2,3-d]pyrimidine derivatives containing 1,8-naphthyridine-4-one fragment were synthesized and their biological activity were tested. Most of the target compounds displayed moderate to excellent activity against one or more cancer cell lines and low activity against human normal cell LO2 in vitro. The most promising compound 51, of which the IC₅₀ values were 0.66 μM, 0.38 μM and 0.44 μM against cell lines A549, Hela and MCF-7, shown more remarkable activity and better apoptosis effect than the positive control Cabozantinib. The structure-activity relationships (SARs) indicated that double-EWGs (such as R₃ = 2-Cl-4-CF₃) on the terminal phenyl rings was a key factor in improving the biological activity. In addition, the further research on compound 51 mainly included c-Met kinase activity and selectivity, concentration dependence, and molecular docking.

Differential expression profiles of long noncoding RNAs and mRNAs in human bone marrow mesenchymal stem cells after exposure to a high dosage of dexamethasone

Background

Abnormalities in apoptosis, cell cycle, proliferation, and differentiation of human bone marrow mesenchymal stem cells (hBMSCs) significantly impact bone metabolism and remodeling, resulting in various skeletal disorders. Long-term exposure to a high dosage of dexamethasone (Dex) induces apoptosis and inhibits the proliferation of mesenchymal stromal cells (MSCs), which are probable primary causes of various skeletal disorders. However, to date, the exact mechanisms of action of Dex on hBMSCs have not been fully elucidated.

Methods

To explore the effects of Dex on apoptosis, cell cycle, proliferation, senescence, osteogenic and adipogenic differentiation of hBMSCs at the various exposure times and concentrations, Hoechst 33342/PI staining, flow cytometry, crystal violet assay, β-galactosidase (β-GAL) activity assay, alizarin red S (ARS) staining assay, and Oil Red O (ORO) staining assay were performed. A microarray assay was used to identify differentially expressed lncRNAs and mRNAs in 10^− 6 mol/L Dex-treated hBMSCs, and a bioinformatics analysis was conducted to further explore the role of these differentially expressed lncRNAs and mRNAs in the coding and noncoding (CNC) network. Furthermore, the microarray results were validated using quantitative real-time PCR (qRT-PCR) analysis.

Results

Over the range of 10⁻⁸, 10⁻⁷, and 10⁻⁶ mol/L, Dex induced apoptosis, arrest of the cell cycle, inhibition of osteogenic differentiation, and promotion adipogenic differentiation of the hBMSCs in a dose-dependent manner. In addition, 10⁻⁶ mol/L Dex significantly induced apoptosis, suppressed proliferation, and increased the senescence of hBMSCs in a time-dependent manner. Interestingly, this time-dependent effect of Dex on the apoptosis of hBMSCs plateaued at the 7th day and decreased from the 8th day to the 10th day, while Dex treatment increased senescence of the hBMSCs on the 6th day. Furthermore, the microarray analysis identified a total of 137 differentially expressed mRNAs (90 upregulated and 47 downregulated) and 90 differentially expressed lncRNAs (61 upregulated and 29 downregulated) in hBMSCs after exposure to 10⁻⁶ mol/L Dex. The differentially expressed mRNAs and lncRNAs were associated with the regulation of cell apoptosis, proliferation, and cell cycle. Meanwhile, several signaling pathways involved in these processes, including the mTOR signaling pathway, Ras signaling pathway, HIF-1 signaling pathway, NF-kappa B signaling pathway, and TGF-beta signaling pathway, also were identified through the interaction net in the significant pathways (Path-Net) analysis. Furthermore, the CNC network further identified 78 core regulatory genes involved in the regulation of apoptosis. Additionally, qRT-PCR was used to confirm the identity of the key differentially expressed mRNAs and lncRNAs found to be closely associated with cell apoptosis to confirm the reliability of the microarray dataset.

Conclusions

In summary, the effect of Dex on apoptosis, cell cycle, proliferation, and osteogenic differentiation and adipogenic differentiation of the hBMSCs depended on exposure time and concentration. Continuous exposure to 10⁻⁶ mol/L of Dex for 7 days may be a suitable protocol for inducing the apoptosis of hBMSCs. Under this protocol, differentially expressed lncRNAs and mRNAs associated with apoptosis, cell cycle, and proliferation were identified, providing a new research direction for further studies.

Supplementary information

The online version contains supplementary material available at 10.1186/s13287-020-02040-8.

Malvidin induces hepatic stellate cell apoptosis via the endoplasmic reticulum stress pathway and mitochondrial pathway

Blueberries have great beneficial effects due to high level of anthocyanins, especially malvidin. Hepatic stellate cells (HSCs) can be activated and increase excessive extracellular matrix (ECM) components, which play a central role in liver fibrogenesis. Therefore, activated HSC's apoptosis can be induced to recover liver fibrosis. Malvidin's effects on apoptosis in rat activated hepatic stellate T6 cells (HSC-T6) in vitro were investigated here. High concentration of malvidin was found to significantly induce apoptosis, activate caspase-3, increase malondialdehyde, upregulate Bax, but downregulate Bcl-2. Moreover, malvidin upregulated the protein levels of some endoplasmic reticulum stress (ERS)-typical markers, including caspase-12, glucose-regulated protein 78 (GRP78), and CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), suggesting that malvidin induced HSC apoptosis by the ERS apoptosis pathway as well as the mitochondrial-dependent pathway. These findings indicated that blueberry anthocyanins, especially malvidin, could induce activated hepatic stellate cell apoptosis and might act as one kind of functional food ingredient or a novel nutraceutical beneficial for liver health.

Sirt3 promotes hepatocellular carcinoma cells sensitivity to regorafenib through the acceleration of mitochondrial dysfunction

Regorafenib, a multiple kinase inhibitor, is recently approved for treatment of patients with advanced hepatocellular carcinoma (HCC). Previous studies demonstrated that regorafenib was a mitochondrial toxicant, which associated with the impairment of mitochondria. Sirt3 is involved in the regulation of mitochondrial function in cancers. This study aimed to investigate the mechanism of Sirt3 involved in the mitochondrial dysfunction which associated with regorafenib treatment in liver cancer cells. We found regorafenib inhibited Sirt3 and p-ERK expression in HCC cells in a dose-dependent manner. Bioinformatics analysis showed that Sirt3 expression was down-regulated in liver cancer tissues and its low expression was correlated with worse overall survival (OS) in liver cancer patients. After transfected with Sirt3 overexpression plasmid, we found that Sirt3 sensitized liver cancer cells to regorafenib and resulted in much more apoptosis with a significant increase of ROS level. However, exogenous antioxidant could not weaken the apoptosis. Mitochondrial membrane potential assay indicated that Sirt3 overexpression accelerated the mitochondrial depolarization process induced by regorafenib and aggravated mitochondrial injury. Cellular oxygen consumption assay showed that mitochondrial dysfunction was caused by the damage of the electron transport chain. The results demonstrated that Sirt3 overexpression promoted the increase of ROS and apoptosis induced by regorafenib through the acceleration of mitochondrial dysfunction by impairing function of the electron transport chain in liver cancer cells. Our studies verified the functional role of Sirt3 in regorafenib treatment and suggested that regorafenib accompanied with Sirt3 activator as a novel treatment strategy for HCC.

Hypoxia-induced NAD+ interventions promote tumor survival and metastasis by regulating mitochondrial dynamics

Hypoxia, an important feature of the tumor microenvironment, is responsible for the chemo-resistance and metastasis of malignant solid tumors. Recent studies indicated that mitochondria undergo morphological transitions as an adaptive response to maintain self-stability and connectivity under hypoxic conditions. NAD⁺ may not only provide reducing equivalents for biosynthetic reactions and in determining energy production, but also functions as a signaling molecule in mitochondrial dynamics regulation. In this review, we describe the upregulated KDAC deacetylase expression in the mitochondria and cytoplasm of tumor cells that results from sensing the changes in NAD⁺ to control mitochondrial dynamics and distribution, which is responsible for survival and metastasis in hypoxia.

Pro- and antitumor effects of mitochondrial reactive oxygen species

In cancer, mitochondrial functions are commonly altered. Directly involved in metabolic reprogramming, mitochondrial plasticity confers to cancer cells a high degree of adaptability to a wide range of stresses and to the harsh tumor microenvironment. Lack of nutrients or oxygen caused by altered perfusion, metabolic needs of proliferating cells, co-option of the microenvironment, control of the immune system, cell migration and metastasis, and evasion of exogenous stress (e.g., chemotherapy) are all, at least in part, influenced by mitochondria. Mitochondria are undoubtedly one of the key contributors to cancer development and progression. Understanding their protumoral (dys)functions may pave the way to therapeutic strategies capable of turning them into innocent entities. Here, we will focus on the production and detoxification of mitochondrial reactive oxygen species (mtROS), on their impact on tumorigenesis (genetic, prosurvival, and microenvironmental effects and their involvement in autophagy), and on tumor metastasis. We will also summarize the latest therapeutic approaches involving mtROS.

Stimulation of Na+/K+-ATPase with an Antibody against Its 4th Extracellular Region Attenuates Angiotensin II-Induced H9c2 Cardiomyocyte Hypertrophy via an AMPK/SIRT3/PPARγ Signaling Pathway

Activation of the renin-angiotensin system (RAS) contributes to the pathogenesis of cardiovascular diseases. Sodium potassium ATPase (NKA) expression and activity are often regulated by angiotensin II (Ang II). This study is aimed at investigating whether DR-Ab, an antibody against 4^th extracellular region of NKA, can protect Ang II-induced cardiomyocyte hypertrophy. Our results showed that Ang II treatment significantly reduced NKA activity and membrane expression. Pretreatment with DR-Ab preserved cell size in Ang II-induced cardiomyopathy by stabilizing the plasma membrane expression of NKA and restoring its activity. DR-Ab reduced intracellular ROS generation through inhibition of NADPH oxidase activity and protection of mitochondrial functions in Ang II-treated H9c2 cardiomyocytes. Pharmacological manipulation and Western blotting analysis demonstrated the cardioprotective effects were mediated by the activation of the AMPK/Sirt-3/PPARγ signaling pathway. Taken together, our results suggest that dysfunction of NKA is an important mechanism for Ang II-induced cardiomyopathy and DR-Ab may be a novel and promising therapeutic approach to treat cardiomyocyte hypertrophy.

A complex suite of loci and elements in eukaryotic type II topoisomerases determine selective sensitivity to distinct poisoning agents

Type II topoisomerases catalyze essential DNA transactions and are proven drug targets. Drug discrimination by prokaryotic and eukaryotic topoisomerases is vital to therapeutic utility, but is poorly understood. We developed a next-generation sequencing (NGS) approach to identify drug-resistance mutations in eukaryotic topoisomerases. We show that alterations conferring resistance to poisons of human and yeast topoisomerase II derive from a rich mutational 'landscape' of amino acid substitutions broadly distributed throughout the entire enzyme. Both general and discriminatory drug-resistant behaviors are found to arise from different point mutations found at the same amino acid position and to occur far outside known drug-binding sites. Studies of selected resistant enzymes confirm the NGS data and further show that the anti-cancer quinolone vosaroxin acts solely as an intercalating poison, and that the antibacterial ciprofloxacin can poison yeast topoisomerase II. The innate drug-sensitivity of the DNA binding and cleavage region of human and yeast topoisomerases (particularly hTOP2β) is additionally revealed to be significantly regulated by the enzymes' adenosine triphosphatase regions. Collectively, these studies highlight the utility of using NGS-based methods to rapidly map drug resistance landscapes and reveal that the nucleotide turnover elements of type II topoisomerases impact drug specificity.

Probucol ameliorates EMT and lung fibrosis through restoration of SIRT3 expression

Pulmonary fibrosis is a progressive fibrotic lung disease with a paucity of therapeutic options. Here we investigated the potential roles of probucol, a cholesterol-lowering drug with potent anti-oxidation properties, on pulmonary epithelial-mesenchymal transition (EMT) and fibrosis. We found that bleomycin-induced lung fibrosis was associated with increased transforming growth factor (TGF)-β1, α-smooth muscle actin (α-SMA) and decreased E-cadherin expression in lung tissues, indicating EMT formation. Bleomycin treatment resulted in an induction of oxidative stress in lung tissues. Probucol treatment attenuated bleomycin-induced TGF-β1 production, EMT and pulmonary fibrosis, meanwhile it suppressed bleomycin-induced oxidative stress. Bleomycin treatment resulted in decreases in protein expressions of Sirtuin 3 (SIRT3) in the lung, which were restored by ROS scavenger NAC and probucol treatment, suggesting that probucol might restore SIRT3 expression by suppressing bleomycin-induced oxidative stress. In the mouse alveolar type II epithelial cell line MLE-12, probucol treatment leads to an increase in SIRT3 expression in bleomycin-treated AT-II cells, which might contribute to the inhibitory effect of probucol on EMT through suppressing hypoxia inducible factor (HIF)-1α/TGF-β1 pathway. In addition, probucol inhibited bleomycin-induced macrophage infiltration in the lung. Bleomycin decreased SIRT3 protein expression, whereas increased HIF-1α activation and TGF-β1 release in the mouse macrophage cell line RAW264.7, which were attenuated by probucol treatment. Taken together, the present study suggests that probucol may ameliorate EMT and lung fibrosis through restoration of SIRT3 expression. The data obtained in this study provides proof for the idea that probucol may be a potential therapeutic option for the treatment of pulmonary fibrosis.

H2S inhalation-induced energy metabolism disturbance is involved in LPS mediated hepatocyte apoptosis through mitochondrial pathway

Hydrogen sulfide (H₂S) is a toxic gas and one of the air pollutants of great concern. High-concentrated H₂S can induce energy metabolism disturbance and apoptosis. However, the mechanism of H₂S-induced liver injuries is unknown. Lipopolysaccharide (LPS), the main component of endotoxin, can cause fulminant hepatitis. Here, we evaluated the effects of H₂S combined with LPS on the energy metabolism and apoptosis pathway in the liver using a one-day-old chicken as a model. Our results showed that the expression levels of energy metabolism-related genes (AMP-activated protein kinase (AMPK), Hypoxia-inducible factor-1 (HIF-1), aconitase 2 (ACO2), hexokinase1 (HK1), hexokinase 2 (HK2), lactate dehydrogenase A (LDHA), lactate dehydrogenase B (LDHB), phosphofructokinase (PFK), pyruvate kinase (PK) and succinate dehydrogenase B (SDHB)) tended to decrease, that the status of apoptosis increased, and that the expression levels of apoptosis-related genes (caspase3, BCL2, and bax) increased in H₂S group, suggesting that H₂S exposure disturbed the energy metabolism in the liver and induced hepatocyte apoptosis through the mitochondrial pathway. In addition, H₂S combined with the LPS aggravated the level of energy metabolism disorders and apoptosis, indicating that H₂S inhalation-induced energy metabolism disturbance is involved in LPS-mediated hepatocyte apoptosis through the mitochondrial pathway.

Mechanical stress protects against osteoarthritis via regulation of the AMPK/NF-κB signaling pathway

Mechanical stress plays a key role in regulating cartilage degradation in osteoarthritis (OA). The aim of this study was to evaluate the effects and mechanisms of mechanical stress on articular cartilage. A total of 80 male Sprague‐Dawley rats were randomly divided into eight groups (n = 10 for each group): control group (CG), OA group (OAG), and CG or OAG subjected to low‐, moderate‐, or high‐intensity treadmill exercise (CL, CM, CH, OAL, OAM, and OAH, respectively). Chondrocytes were obtained from the knee joints of rats; they were cultured on Bioflex 6‐well culture plates and subjected to different durations of cyclic tensile strain (CTS) with or without exposure to interleukin‐1β (IL‐1β). The results of the histological score, immunohistochemistry, enzyme‐linked immunosorbent assay, and western‐blot analyses indicated that there were no differences between CM and CG, but OAM showed therapeutic effects compared with OAG. However, CH and OAH experienced more cartilage damage than CG and OAG, respectively. CTS had no therapeutic effects on collagen II of normal chondrocytes, which is consistent with findings after treadmill exercise. However, CTS for 4 hr could alleviate the chondrocyte damage induced by IL‐1β by activating AMP‐activated protein kinase (AMPK) phosphorylation and suppressing nuclear translocation of nuclear factor (NF)‐κB p65. Our findings indicate that mechanical stress had no therapeutic effects on normal articular cartilage and chondrocytes; mechanical stress only caused damage with excessive stimulation. Still, moderate biomechanical stress could reduce sensitization to the inflammatory response of articular cartilage and chondrocytes through the AMPK/NF‐κB signaling pathway.