Cisplatin-Mediated Upregulation of APE2 Binding to MYH9 Provokes Mitochondrial Fragmentation and Acute Kidney Injury

Galloyl-oligochitosan nano-vehicles for effective and controlled propolis delivery targeting upgrading its antioxidant and antiproliferative potential

A new conjugate, galloyl-oligochitosan nanoparticles (GOCNPs), was fabricated and used as nano-vehicle for effective and controlled delivery of propolis extract (PE) in the form of PE#GOCNPs, targeting improving its pharmaceutical potential. H-bonding interactions between the carboxyl, amino, and hydroxyl groups of the GOCNPs and PE resulted in successful encapsulation, with an entrapment efficacy of 97.3 %. The PE#GOCNPs formulation also exhibited excellent physicochemical stability and time-triggered drug release characteristics under physiological conditions. Furthermore, PE#GOCNPs showed significant activity against MCF-7 and HEPG2 carcinoma cells by scavenging free oxygen radicals and upregulating antioxidant enzymes. Additionally, PE#GOCNPs displayed anti-inflammatory properties by increasing IL10 and reducing pro-inflammatory cytokines more effectively than celecoxib. Furthermore, PE#GOCNPs reduced the expression of epidermal growth factor receptor (EGFR) and survivin genes. Furthermore, the encapsulated PE demonstrated significant activity in suppressing sonic hedgehog protein (SHH). The use of GOCNPs in combination with propolis presents a promising new strategy for chemotherapy with reduced toxicity and enhanced biocompatibility. This novel approach has the potential to revolutionize the field of chemotherapy. Future studies should focus on the application of the encapsulated PE in various cancer cell lines, distinct gene expression factors, and cell cycles.

Ubiquitin-mediated regulation of APE2 protein abundance

APE2 plays important roles in the maintenance of genomic and epigenomic stability including DNA repair and DNA damage response. Accumulating evidence has suggested that APE2 is upregulated in multiple cancers at the protein and mRNA levels, and that APE2 upregulation is correlative with higher and lower overall survival of cancer patients depending on tumor type. However, it remains unknown how APE2 protein abundance is maintained and regulated in cells. Here, we provide the first evidence of APE2 regulation via the post-translational modification (PTM) Ubiquitin. APE2 is poly-ubiquitinated via K48-linked chains and degraded via the Ubiquitin-Proteasome system where K371 is the key residue within APE2 responsible for its ubiquitination and degradation. We further characterize MKRN3 as the E3 ubiquitin ligase for APE2 ubiquitination in cells and in vitro. In summary, this study offers the first definition of the APE2 proteostasis network and lays the foundation for future studies pertaining to the PTM regulation and functions of APE2 in genome integrity and cancer etiology/treatment.

An integrated view of cisplatin-induced nephrotoxicity, hepatotoxicity, and cardiotoxicity: characteristics, common molecular mechanisms, and current clinical management

Cisplatin (CP) is a chemotherapy drug widely prescribed to treat various neoplasms. Although fundamental for the therapeutic action of the drug, its cytotoxic mechanisms trigger adverse effects in several tissues, such as the kidney, liver, and heart, which limit its clinical use. In this sense, studies point to an essential role of damage to nuclear and mitochondrial DNA associated with oxidative stress, inflammation, and apoptosis in the pathophysiology of tissue injuries. Due to the limitation of effective preventive and therapeutic measures against CP-induced toxicity, new strategies with potential cytoprotective effects have been studied. Therefore, this article is timely in reviewing the characteristics and main molecular mechanisms common to renal, hepatic, and cardiac toxicity previously described, in addition to addressing the main validated strategies for the current management of these adverse events in clinical practice. We also handle the main promising antioxidant substances recently presented in the literature to encourage the development of new research that consolidates their potential preventive and therapeutic effects against CP-induced cytotoxicity.

Long non-coding RNA MLLT4 antisense RNA 1 induces autophagy to inhibit tumorigenesis of cervical cancer through modulating the myosin-9/ATG14 axis

The regulatory mechanism of long non-coding RNAs (lncRNAs) in autophagy is as yet not well established. In this research, we show that the long non-coding RNA MLLT4 antisense RNA 1 (lncRNA MLLT4-AS1) is induced by the MTORC inhibitor PP242 and rapamycin in cervical cells. Overexpression of MLLT4-AS1 promotes autophagy and inhibits tumorigenesis and the migration of cervical cancer cells, whereas knockdown of MLLT4-AS1 attenuates PP242-induced autophagy. Mass spectrometry, RNA fluorescence in situ hybridization (RNA-FISH), and immunoprecipitation assays were performed to identify the direct interactions between MLLT4-AS1 and other associated targets, such as myosin-9 and autophagy-related 14(ATG14). MLLT4-AS1 was upregulated by H3K27ac modification with PP242 treatment, and knockdown of MLLT4-AS1 reversed autophagy by modulating ATG14 expression. Mechanically, MLLT4-AS1 was associated with the myosin-9 protein, which further promoted the transcription activity of the ATG14 gene. In conclusion, we demonstrated that MLLT4-AS1 acts as a potential tumor suppressor in cervical cancer by inducing autophagy, and H3K27ac modification-induced upregulation of MLLT4-AS1 could cause autophagy by associating with myosin-9 and promoting ATG14 transcription.

MYH9: A key protein involved in tumor progression and virus-related diseases

The myosin heavy chain 9 (MYH9) gene encodes the heavy chain of non-muscle myosin IIA (NMIIA), which belongs to the myosin II subfamily of actin-based molecular motors. Previous studies have demonstrated that abnormal expression and mutations of MYH9 were correlated with MYH9-related diseases and tumors. Furthermore, earlier investigations identified MYH9 as a tumor suppressor. However, subsequent research revealed that MYH9 promoted tumorigenesis, progression and chemoradiotherapy resistance. Note-worthily, MYH9 has also been linked to viral infections, like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Epstein-Barr virus, and hepatitis B virus, as a receptor or co-receptor. In addition, MYH9 promotes the development of hepatocellular carcinoma by interacting with the hepatitis B virus-encoding X protein. Finally, various findings highlighted the role of MYH9 in the development of these illnesses, especially in tumors. This review summarizes the involvement of the MYH9-regulated signaling network in tumors and virus-related diseases and presents possible drug interventions on MYH9, providing insights for the use of MYH9 as a therapeutic target for tumors and virus-mediated diseases.

PIM1 attenuates cisplatin-induced AKI by inhibiting Drp1 activation

Cisplatin, an effective anti-cancer drug, always causes acute kidney injury (AKI) by inducing mitochondrial damage. PIM1 is a serine/threonine kinase, which has been shown to regulate mitochondrial function. However, the role and mechanisms of PIM1 in cisplatin-induced AKI remain unexplored. This study aimed to investigate the effects of PIM1 in cisplatin-induced AKI and its underlying mechanisms. To established Cisplatin-induced AKI model, mice were given a single intraperitoneal injection(20 mg/kg) and BUMPT cells were treated with cisplatin(20 μM). PIM1 inhibitor AZD1208 was used to inhibit PIM1 and PIM1-experssing adenovirus was used to overexpress PIM1. Drp1 inhibitor P110 and pcDNA3-Drp1K38A were used to inhibit the activation of Drp1 and mitochondrial fission. The indicators of renal function, renal morphology, apoptosis and mitochondrial dysfunction were assessed to evaluate cisplatin-induced nephrotoxicity. We observed that PIM1 was activated in cisplatin-induced AKI in vivo and cisplatin-induced tubular cells injury in vitro. PIM1 inhibition aggravated cisplatin-induced AKI in vivo, while PIM1 overexpression attenuated cisplatin-induced kidney injury in vivo and in vitro. Moreover, inhibiting PIM1 exacerbated mitochondrial damage in mice, but overexpressing PIM1 relieved mitochondrial damage in mice and BUMPT cells. In mice and BUMPT cells, inhibiting PIM1 deregulated the expression of p-Drp1S637, overexpressing PIM1 upregulated the ex-pression of p-Drp1S637. And inhibiting Drp1 activity alleviated cell damage in BUMPT cells with PIM1 knockdown or inhibition. This study demonstrated the protective effect of PIM1 in cisplatin-induced AKI, and regulation of Drp1 activation might be the underlying mechanism. Altogether, PIM1 may be a potential therapeutic target for cisplatin-induced AKI.

Inhibition of TMEM16A improves cisplatin-induced acute kidney injury via preventing DRP1-mediated mitochondrial fission

Acute kidney injury (AKI) is associated with high morbidity and mortality. Our previous study has demonstrated that TMEM16A, a Ca2+-activated chloride channel, contributes to renal fibrosis progression in chronic kidney disease. However, whether TMEM16A is involved in AKI is still unknown. In this study, we established cisplatin AKI mice model and found that TMEM16A expression was upregulated in the injured kidney. In vivo knockdown of TMEM16A effectively prevented cisplatin-induced tubular cell apoptosis, inflammation and kidney function loss. Western blot and transmission electron microscopy (TEM) revealed that TMEM16A knockdown inhibited Drp1 translocation from the cytoplasm to mitochondria and prevented mitochondrial fission in tubular cells. Consistently, in cultured HK2 cells, knockdown or inhibition of TMEM16A by shRNA or its specific inhibitor suppressed cisplatin-induced mitochondrial fission and its associated energy dysfunction, ROS accumulation, and cell apoptosis via inhibiting Drp1 activation. Further investigation showed that genetic knockdown or pharmacological inhibition of TMEM16A inhibited cisplatin-induced Drp1 Ser-616 site phosphorylation through ERK1/2 signaling pathway, whereas overexpression of TMEM16A promoted this effect. Treatment with Drp1 or ERK1/2 inhibitor could efficiently prevent cisplatin-induced mitochondrial fission. Collectively, our data suggest that TMEM16A inhibition alleviated cisplatin-induced AKI by preventing tubular cell mitochondrial fission through the ERK1/2 / Drp1 pathway. Inhibition of TMEM16A may be a novel therapeutic strategy for AKI.

Pyruvate kinase M2 regulates mitochondrial homeostasis in cisplatin-induced acute kidney injury

An important pathophysiological process of acute kidney injury (AKI) is mitochondrial fragmentation in renal tubular epithelial cells, which leads to cell death. Pyruvate kinase M2 (PKM2) is an active protein with various biological functions that participates in regulating glycolysis and plays a key role in regulating cell survival. However, the role and mechanism of PKM2 in regulating cell survival during AKI remain unclear. Here, we found that the phosphorylation of PKM2 contributed to the formation of the PKM2 dimer and translocation of PKM2 into the mitochondria after treatment with staurosporine or cisplatin. Mitochondrial PKM2 binds myosin heavy chain 9 (MYH9) to promote dynamin-related protein 1 (DRP1)-mediated mitochondrial fragmentation. Both in vivo and in vitro, PKM2-specific loss or regulation PKM2 activity partially limits mitochondrial fragmentation, alleviating renal tubular injury and cell death, including apoptosis, necroptosis, and ferroptosis. Moreover, staurosporine or cisplatin-induced mitochondrial fragmentation and cell death were reversed in cultured cells by inhibiting MYH9 activity. Taken together, our results indicate that the regulation of PKM2 abundance and activity to inhibit mitochondrial translocation may maintain mitochondrial integrity and provide a new therapeutic strategy for treating AKI.

Compound-42 alleviates acute kidney injury by targeting RIPK3-mediated necroptosis

BACKGROUND AND PURPOSE

Necroptosis plays an essential role in acute kidney injury and is mediated by receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3), and mixed lineage kinase domain-like pseudokinase (MLKL). A novel RIPK3 inhibitor, compound 42 (Cpd-42) alleviates the systemic inflammatory response. The current study was designed to investigate whether Cpd-42 exhibits protective effects on acute kidney injury and reveal the underlying mechanisms.

EXPERIMENTAL APPROACH

The effects of Cpd-42 were determined in vivo through cisplatin- and ischaemia/reperfusion (I/R)-induced acute kidney injury and in vitro through cisplatin- and hypoxia/re-oxygenation (H/R)-induced cell damage. Transmission electron microscopy and periodic acid-Schiff staining were used to identify renal pathology. Cellular thermal shift assay and RIPK3-knockout mouse renal tubule epithelial cells were used to explore the relationship between Cpd-42 and RIPK3. Molecular docking and site-directed mutagenesis were used to determine the binding site of RIPK3 with Cpd-42.

KEY RESULTS

Cpd-42 reduced human proximal tubule epithelial cell line (HK-2) cell damage, necroptosis and inflammatory responses in vitro. Furthermore, in vivo, cisplatin- and I/R-induced acute kidney injury was alleviated by Cpd-42 treatment. Cpd-42 inhibited necroptosis by interacting with two key hydrogen bonds of RIPK3 at Thr94 and Ser146, which further blocked the phosphorylation of RIPK3 and mitigated acute kidney injury.

CONCLUSION AND IMPLICATIONS

Acting as a novel RIPK3 inhibitor, Cpd-42 reduced kidney damage, inflammatory response and necroptosis in acute kidney injury by binding to sites Thr94 and Ser146 on RIPK3. Cpd-42 could be a promising treatment for acute kidney injury.

Gut Microbiota Combined with Metabolomics Reveal the Mechanisms of Sika Deer Antler Protein on Cisplatin-Induced Hepatorenal Injury in Mice

Cisplatin is a widely used antineoplastic drug, though its adverse effects, particularly its hepatorenal toxicity, limit its long-term application. Sika deer antler is a valuable traditional Chinese medicine (TCM) documented to possess the capacity for tonifying the kidney and regulating the liver, of which the sika deer antler protein is an important active ingredient. In this study, two protein fractions, SVPr1 and SVPr2, of sika deer antler were purified and administered to mice treated with cisplatin, and serum metabolome and fecal microbiota were measured using ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and 16S rRNA gene sequencing. SVPr1 and SVPr2 significantly ameliorated cisplatin-induced liver and kidney injury and reduced mitochondrial dysfunction, oxidative stress, inflammatory response, and apoptosis. In addition, SVPr1 and SVPr2 impacted the gut microbiota structure of mice, significantly increasing the relative abundances of Lactobacillus, which deserves to be scrutinized. Moreover, SVPr1 and SVPr2 antagonism of cisplatin-induced hepatorenal injury may be related to the regulation of lysine degradation, tryptophan metabolism, and riboflavin metabolism pathways, significantly altering the levels of L-saccharopine, L-lysine, L-kynurenine, 3-methylindole, xanthurenic acid, riboflavin, and D-ribulose-5-phosphate. A correlation between the differential metabolites and Lactobacillus was identified. These findings increased the knowledge of the gut microbiota-metabolites axis mediated by SVPr1 and SVPr2, and may be able to contribute to the development of new therapeutic strategies for the simultaneous prevention and treatment of liver and kidney injury from cisplatin treatment.

Ruscogenin Alleviates Myocardial Ischemia via Myosin IIA-Dependent Mitochondrial Fusion and Fission Balance

Ruscogenin (RUS), a major effective steroidal sapogenin derived from Ophiopogon japonicas, has been reported to alleviate myocardial ischemia (MI), but its cardioprotective mechanism is still not completely clear. In this study, we observed that RUS markedly reduced MI-induced myocardial injury, as evidenced by notable reductions in infarct size, improvement in biochemical markers, alleviation of cardiac pathology, amelioration of mitochondrial damage, and inhibition of myocardial apoptosis. Moreover, RUS notably suppressed oxygen-glucose deprivation (OGD)-triggered cell injury and apoptosis. Notably, RUS demonstrated a considerable decrease of the interaction between myosin IIA and F-actin, along with the restoration of mitochondrial fusion and fission balance. We further confirmed that the effects of RUS on MI were mediated by myosin IIA using siRNA and overexpression techniques. The inhibition of myosin IIA resulted in a significant improvement of mitochondrial fusion and fission imbalance, while simultaneously counteracting the beneficial effects of RUS. By contrast, overexpression of myosin IIA aggravated the imbalance between mitochondrial fusion and fission and partially weakened the protection of RUS. These findings suggest that myosin IIA is essential or even a key functional protein in the cardioprotection of RUS. Overall, our results have elucidated an undiscovered mechanism involving myosin IIA-dependent mitochondrial fusion and fission balance for treating MI. Furthermore, our study has uncovered a novel mechanism underlying the protective effects of RUS.

Histochemical and histomorphological evidence of the modulating role of 1-isothiocyanate-4-methyl sulfonyl butane on cisplatin-induced testicular-pituitary axis degeneration and cholesterol homeostasis in male Sprague-Dawley rats

BACKGROUND

This study examine the histochemical and histomorphological effect of 1-isothiocyanato-4-methyl sulfonyl butane (SFN) on cisplatin (CP) induced testicular alteration and cholesterol homeostasis.

MATERIALS AND METHODS

Ninety adult-male Sprague-Dawley rats were randomized into nine groups of ten (n=10) rats each. Group A (control) received normal saline, group B received a single dose of 10mg/Kg body weight (bwt) CP (i.p.), group C received 50mg/Kg bwt of SFN, group D received 100mg/Kg bwt of SFN, group E received 10mg/Kg bwt CP and 50mg/Kg bwt of SFN, group F received 10mg/Kg bwt CP and 100mg/Kg bwt of SFN, group G received 10mg/Kg bwt CP and 50mg/Kg bwt vitamin C, group H received 50mg/Kg bwt of SFN and 10mg/Kg bwt CP, group I received 100mg/Kg bwt of SFN and 10mg/Kg bwt CP. The procedure lasted for 56 days. Testicular histomorphology and histochemistry, testicular testosterone, sperm parameters, total antioxidant status (TSA), total oxidant status (TOS), oxidative stress index (OSI), and serum lipid profile were examined.

RESULTS

Cisplatin decrease intra-testicular testosterone, sperm quality, and expression of glycogen and increases testicular TOS and OSI, serum lipid profile, collagen, and disruption of germinal epithelium. However, the intervention of SFN reversed the effect of CP on testes' weight and volume, DSP, ESP, testosterone production, TAS, TOS, and OSI. Histoarchitectecture showing normal seminiferous tubules and even distribution of glycogen and collagen fibers.

CONCLUSION

Treatment with SFN ameliorate CP-induced testicular toxicity by reversing the cytotoxic mechanisms of CP.

APE2: catalytic function and synthetic lethality draw attention as a cancer therapy target

AP endonuclease 2 (APE2, APEX2 or APN2) is an emerging critical protein involved in genome and epigenome integrity. Whereas its catalytic function as a nuclease in DNA repair is widely accepted, recent studies have elucidated the function and mechanism of APE2 in the immune response and DNA damage response. Several genome-wide screens have identified APE2 as a synthetic lethal target for deficiencies of BRCA1, BRCA2 or TDP1 in cancer cells. Due to its overexpression in several cancer types, APE2 is proposed as an oncogene and could serve as prognostic marker of overall survival of cancer treatment. However, it remains to be discovered whether and how APE2 catalytic function and synthetic lethality can be modulated and manipulated as a cancer therapy target. In this review, we provide a current understanding of alterations and expression of APE2 in cancer, the function of APE2 in the immune response, and mechanisms of APE2 in ATR/Chk1 DNA damage response. We also summarize the role of APE2 in DNA repair pathways in the removal of heterogenous and complexed 3'-termini and MMEJ. Finally, we provide an updated perspective on how APE2 may be targeted for cancer therapy and future directions of APE2 studies in cancer biology.

The Mitochondrion: A Promising Target for Kidney Disease

Mitochondrial dysfunction is important in the pathogenesis of various kidney diseases and the mitochondria potentially serve as therapeutic targets necessitating further investigation. Alterations in mitochondrial biogenesis, imbalance between fusion and fission processes leading to mitochondrial fragmentation, oxidative stress, release of cytochrome c and mitochondrial DNA resulting in apoptosis, mitophagy, and defects in energy metabolism are the key pathophysiological mechanisms underlying the role of mitochondrial dysfunction in kidney diseases. Currently, various strategies target the mitochondria to improve kidney function and kidney treatment. The agents used in these strategies can be classified as biogenesis activators, fission inhibitors, antioxidants, mPTP inhibitors, and agents which enhance mitophagy and cardiolipin-protective drugs. Several glucose-lowering drugs, such as glucagon-like peptide-1 receptor agonists (GLP-1-RA) and sodium glucose co-transporter-2 (SGLT-2) inhibitors are also known to have influences on these mechanisms. In this review, we delineate the role of mitochondrial dysfunction in kidney disease, the current mitochondria-targeting treatment options affecting the kidneys and the future role of mitochondria in kidney pathology.

Cisplatin nephrotoxicity: new insights and therapeutic implications

Cisplatin is an effective chemotherapeutic agent for various solid tumours, but its use is limited by adverse effects in normal tissues. In particular, cisplatin is nephrotoxic and can cause acute kidney injury and chronic kidney disease. Preclinical studies have provided insights into the cellular and molecular mechanisms of cisplatin nephrotoxicity, which involve intracellular stresses including DNA damage, mitochondrial pathology, oxidative stress and endoplasmic reticulum stress. Stress responses, including autophagy, cell-cycle arrest, senescence, apoptosis, programmed necrosis and inflammation have key roles in the pathogenesis of cisplatin nephrotoxicity. In addition, emerging evidence suggests a contribution of epigenetic changes to cisplatin-induced acute kidney injury and chronic kidney disease. Further research is needed to determine how these pathways are integrated and to identify the cell type-specific roles of critical molecules involved in regulated necrosis, inflammation and epigenetic modifications in cisplatin nephrotoxicity. A number of potential therapeutic targets for cisplatin nephrotoxicity have been identified. However, the effects of renoprotective strategies on the efficacy of cisplatin chemotherapy needs to be thoroughly evaluated. Further research using tumour-bearing animals, multi-omics and genome-wide association studies will enable a comprehensive understanding of the complex cellular and molecular mechanisms of cisplatin nephrotoxicity and potentially lead to the identification of specific targets to protect the kidney without compromising the chemotherapeutic efficacy of cisplatin.

Cisplatin-Induced Kidney Toxicity: Potential Roles of Major NAD+-Dependent Enzymes and Plant-Derived Natural Products

Cisplatin is an FDA approved anti-cancer drug that is widely used for the treatment of a variety of solid tumors. However, the severe adverse effects of cisplatin, particularly kidney toxicity, restrict its clinical and medication applications. The major mechanisms of cisplatin-induced renal toxicity involve oxidative stress, inflammation, and renal fibrosis, which are covered in this short review. In particular, we review the underlying mechanisms of cisplatin kidney injury in the context of NAD⁺-dependent redox enzymes including mitochondrial complex I, NAD kinase, CD38, sirtuins, poly-ADP ribosylase polymerase, and nicotinamide nucleotide transhydrogenase (NNT) and their potential contributing roles in the amelioration of cisplatin-induced kidney injury conferred by natural products derived from plants. We also cover general procedures used to create animal models of cisplatin-induced kidney injury involving mice and rats. We highlight the fact that more studies will be needed to dissect the role of each NAD⁺-dependent redox enzyme and its involvement in modulating cisplatin-induced kidney injury, in conjunction with intensive research in NAD⁺ redox biology and the protective effects of natural products against cisplatin-induced kidney injury.

miR-125b Disrupts Mitochondrial Dynamics via Targeting Mitofusin 1 in Cisplatin-Induced Acute Kidney Injury

Background

Mitochondria are dynamic organelles whose structure are maintained by continuous fusion and fission. During acute kidney injury (AKI) progression, mitochondrial fission in renal tubular cells was elevated, characterized by mitochondrial fragmentation. It is tightly associated with mitochondrial dysfunction, which has been proven as a critical mechanism responsible for AKI. However, the initiating factor for the disruption of mitochondrial dynamics in AKI was not well understood.

Objectives

To explore the molecular mechanisms of mitochondrial disorders and kidney damage.

Methods

We established cisplatin-induced AKI model in C57BL/6 mice and proximal tubular cells, and detected the expression of miR-125b by qPCR. Then we delivered miR-125b antagomir after cisplatin treatment in mice via hydrodynamic-based gene transfer technique. Subsequently, we performed luciferase reporter and immunoblotting -assays to prove miR-125b could directly modulate mitofusin1 (MFN1) expression. We also tested the role of miR-125b in mitochondrial and renal injury through immunofluorescent staining, qPCR, and immunoblotting assays.

Results

miR-125b levels were induced in cisplatin-challenged mice and cultured tubular cells. Anti-miR-125b could effectively alleviate cisplatin-induced mitochondrial fragmentation and kidney injury both in vitro and in vivo. Furthermore, miR-125b could directly regulate MFN1, which is a key regulator of mitochondrial fusion. Our study indicated that miR-125b is upregulated during cisplatin-induced AKI. Inhibition of miR-125b may suppress mitochondrial and renal damage through upregulating MFN1. This study suggests that miR-125b could be a potential therapeutic target in AKI.

APE2 Is a General Regulator of the ATR-Chk1 DNA Damage Response Pathway to Maintain Genome Integrity in Pancreatic Cancer Cells

The maintenance of genome integrity and fidelity is vital for the proper function and survival of all organisms. Recent studies have revealed that APE2 is required to activate an ATR-Chk1 DNA damage response (DDR) pathway in response to oxidative stress and a defined DNA single-strand break (SSB) in Xenopus laevis egg extracts. However, it remains unclear whether APE2 is a general regulator of the DDR pathway in mammalian cells. Here, we provide evidence using human pancreatic cancer cells that APE2 is essential for ATR DDR pathway activation in response to different stressful conditions including oxidative stress, DNA replication stress, and DNA double-strand breaks. Fluorescence microscopy analysis shows that APE2-knockdown (KD) leads to enhanced γH2AX foci and increased micronuclei formation. In addition, we identified a small molecule compound Celastrol as an APE2 inhibitor that specifically compromises the binding of APE2 but not RPA to ssDNA and 3′-5′ exonuclease activity of APE2 but not APE1. The impairment of ATR-Chk1 DDR pathway by Celastrol in Xenopus egg extracts and human pancreatic cancer cells highlights the physiological significance of Celastrol in the regulation of APE2 functionalities in genome integrity. Notably, cell viability assays demonstrate that APE2-KD or Celastrol sensitizes pancreatic cancer cells to chemotherapy drugs. Overall, we propose APE2 as a general regulator for the DDR pathway in genome integrity maintenance.

Cisplatin Mouse Models: Treatment, Toxicity and Translatability

Cisplatin is one of the most widely used chemotherapeutic drugs in the treatment of a wide range of pediatric and adult malignances. However, it has various side effects which limit its use. Cisplatin mouse models are widely used in studies investigating cisplatin therapeutic and toxic effects. However, despite numerous promising results, no significant improvement in treatment outcome has been achieved in humans. There are many drawbacks in the currently used cisplatin protocols in mice. In the paper, the most characterized cisplatin protocols are summarized together with weaknesses that need to be improved in future studies, including hydration and supportive care. As demonstrated, mice respond to cisplatin treatment in similar ways to humans. The paper thus aims to illustrate the complexity of cisplatin side effects (nephrotoxicity, gastrointestinal toxicity, neurotoxicity, ototoxicity and myelotoxicity) and the interconnectedness and interdependence of pathomechanisms among tissues and organs in a dose- and time-dependent manner. The paper offers knowledge that can help design future studies more efficiently and interpret study outcomes more critically. If we want to understand molecular mechanisms and find therapeutic agents that would have a potential benefit in clinics, we need to change our approach and start to treat animals as patients and not as tools.

Gallic acid for cancer therapy: Molecular mechanisms and boosting efficacy by nanoscopical delivery

Cancer is the second leading cause of death worldwide. Majority of recent research efforts in the field aim to address why cancer resistance to therapy develops and how to overcome or prevent it. In line with this, novel anti-cancer compounds are desperately needed for chemoresistant cancer cells. Phytochemicals, in view of their pharmacological activities and capacity to target various molecular pathways, are of great interest in the development of therapeutics against cancer. Plant-derived-natural products have poor bioavailability which restricts their anti-tumor activity. Gallic acid (GA) is a phenolic acid exclusively found in natural sources such as gallnut, sumac, tea leaves, and oak bark. In this review, we report on the most recent research related to anti-tumor activities of GA in various cancers with a focus on its underlying molecular mechanisms and cellular pathwaysthat that lead to apoptosis and migration of cancer cells. GA down-regulates the expression of molecular pathways involved in cancer progression such as PI3K/Akt. The co-administration of GA with chemotherapeutic agents shows improvements in suppressing cancer malignancy. Various nano-vehicles such as organic- and inorganic nano-materials have been developed for targeted delivery of GA at the tumor site. Here, we suggest that nano-vehicles improve GA bioavailability and its ability for tumor suppression.

Apurinic/Apyrimidinic Endonuclease 2 (APE2): An ancillary enzyme for contextual base excision repair mechanisms to preserve genome stability

The genome of living organisms frequently undergoes various types of modifications which are recognized and repaired by the relevant repair mechanisms. These repair pathways are increasingly being deciphered to understand the mechanisms. Base excision repair (BER) is indispensable to maintain genome stability. One of the enigmatic repair proteins of BER, Apurinic/Apyrimidinic Endonuclease 2 (APE2), like APE1, is truly multifunctional and demonstrates the independent and non-redundant function in maintaining the genome integrity. APE2 is involved in ATR-Chk1 mediated DNA damage response. It also resolves topoisomerase1 mediated cleavage complex intermediate which is formed while repairing misincorporated ribonucleotides in the absence of functional RNase H2 mediated excision repair pathway. BER participates in the demethylation pathway and the role of Arabidopsis thaliana APE2 is demonstrated in this process. Moreover, APE2 is synthetically lethal to BRCA1, BRCA2, and RNase H2, and its homolog, APE1 fails to complement the function. Hence, the role of APE2 is not just an alternate to the repair mechanisms but has implications in diverse functional pathways related to the maintenance of genome integrity. This review analyses genomic features of APE2 and delineates its enzyme function as error-prone as well as efficient and accurate repair protein based on the studies on mammalian or its homolog proteins from model systems such as Arabidopsis thaliana, Schizosaccharomyces pombe, Trypanosoma curzi, Xenopus laevis, Danio rerio, Mus musculus, and Homo sapiens.

Mesenchymal stem cell-derived extracellular vesicles prevent the development of osteoarthritis via the circHIPK3/miR-124-3p/MYH9 axis

Background

Extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs) may play a vital role in a variety of biological processes, including cartilage regeneration. However, few studies reported their potential in the development of osteoarthritis (OA) previously. In this study, we explored the biological roles and underlying mechanism of MSCs-EVs in OA.

Results

Co-culture experiments revealed that MSCs-EVs could promote the expression of collagen type II alpha 1 chain (COL2A1), SRY-box transcription factor 9 (SOX9) and Aggrecan while negatively regulate the expression of chondrocyte hypertrophy markers matrix metallopeptidase 13 (MMP-13) and RUNX family transcription factor 2 (Runx2) in mouse chondrocytes in the OA model. Besides, the results of cell experiments indicated that MSCs-EVs could notably weaken the suppression of chondrocyte proliferation, migration and the promotion of chondrocyte apoptosis via interleukin1β (IL-1β) induction. In addition, MSCs-circHIPK3-EVs (EVs derived from MSCs overexpressing circHIPK3) considerably improved IL-1β-induced chondrocyte injury. Mechanistically, we elucidated that circHIPK3 could directly bind to miR-124-3p and subsequently elevate the expression of the target gene MYH9.

Conclusion

The findings in our study demonstrated that EVs-circHIPK3 participated in MSCs-EVs-mediated chondrocyte proliferation and migration induction and in chondrocyte apoptosis inhibition via the miR-124-3p/MYH9 axis. This offers a promising novel cell-free therapy for treating OA.

Graphic abstract