Inhibition Of DNA Synthesis Research Articles

In Vivo Cytotoxic, Genotoxic and Radiosensitizing Effects of Clofarabine.

ClFdA is a second-generation antineoplastic agent that has demonstrated significant anticancer activity, particularly against acute lymphoblastic leukemia and has been shown to have radiosensitizing activity. The aim of the study was to explore the genotoxic, cytotoxic and radiosensitizing effects of clofarabine (ClFdA) on bone marrow cells (BMCs), normoblasts and leukocytes of mice in vivo. Cytotoxicity was determined by the reduction in reticulocytes (RET), and genotoxicity was determined by the induction of micronucleated reticulocytes (MN-RET) in the peripheral blood and by DNA break induction in leukocytes determined by single-cell gel electrophoresis (SCGE). The radiosensitizing capacity of ClFdA was determined in leukocytes and BMCs by SCGE. Two mechanisms of MN-RET induction were identified according to the antecedents, that could be due to inhibition of DNA synthesis and demethylation of G-C regions, and subsequent chromosome fragility. ClFdA cytotoxicity causes two contiguous peaks, an early peak that seems to inhibit MN-RET induction and a second peak that seems to be caused by ribonucleotide reductase (RR) and/or DNA synthesis inhibitions. ClFdA induced early DNA damage in noncycling leukocytes, and also radiosensitizes leukocytes immediately after treatment. ClFdA-ionizing radiation (IR) causes two time-dependent episodes of DNA damage, the latest after 80 min triggers a major breakage of DNA. In terms of the number of damaged cells, leukocytes and BMCs are similarly sensitive to ionizing radiation; BMCs are slightly more sensitive than leukocytes to ClFdA, but BMCs are doubly sensitive to combined treatment. ClFdA causes early DNA damage and radiosensitivity in non-proliferating leukocytes, which rules out the most favored hypotheses of the participation of RR and DNA polymerase inhibition.

Pyrimidine derivatives: Their significance in the battle against malaria, cancer and viral infections

Pyrimidine derivatives play a significant role in combating viral infections, malaria, and cancer due to their diverse pharmacological properties. Pyrimidine derivatives, particularly nucleoside analogs, have been widely used as antiviral agents. They interfere with viral replication by inhibiting DNA or RNA synthesis.Examples include drugs like acyclovir (used against herpes viruses), lamivudine (for HIV and hepatitis B), and remdesivir (for COVID-19). These compounds help to manage and treat various viral infections, reducing their severity and spread. Pyrimidine derivatives are key components of antimalarial drugs like pyrimethamine and proguanil. They target the parasite Plasmodium falciparum's dihydrofolate reductase enzyme, essential for its survival. These drugs have been instrumental in combating malaria, a major global health concern, by inhibiting the growth of the malaria parasite within the human body. Pyrimidine analogs are used in chemotherapy to target rapidly dividing cancer cells. Drugs like 5-fluorouracil (5-FU) and cytarabine inhibit DNA synthesis in cancer cells, leading to cell death. These derivatives have been crucial in the treatment of various cancers, helping to slow down tumor growth and improve patient outcomes. Overall, this article aims to consolidate existing knowledge on the topic, synthesize relevant information, and contribute to a better understanding of the potential applications of pyrimidine derivatives in the fields of oncology, virology, and tropical medicine.

Cinobufagin Induces Apoptosis of DLBCL Cells By Targeting the Inhibition of G6PD Activity

Background:Globally, there are 150,000 new cases of diffuse large B-cell lymphoma (DLBCL) each year, accounting for approximately 30% of all non-Hodgkin lymphoma cases. Although most patients can be cured with R-CHOP immunochemotherapy, 30-40% of patients progress or relapse after treatment. Therefore, there is an urgent need to find new treatments to improve the survival rate of this group of patients. Natural small molecule drugs have unique advantages as anticancer agents due to their low toxicity and multiple targets. This project aims to explore potentially effective natural compounds as new therapeutic strategies for DLBCL. Methods:Search for suitable natural compounds through GEO database, CMAP server and bioinformatics analysis. The effects of natural compounds on the biological function of DLBCL cells were studied by IC50 assay, apoptosis assay, cell cycle assay and subcutaneous transplanted tumor model. RNA sequencing, metabolomics detection, SEA server and 3D molecular simulation docking analysis were used to explore the drug target. The drug mechanism was verified by G6PD activity assay, EdU incorporation assay, NADPH assay and ROS assay. Results:We used GEO and CMAP databases to identify 20 natural compounds that target DLBCL prognostic genes. Cinobufagin, a natural bufodienol isolated from toad venom, became the main object of this study because of its low IC50 value. Flow cytometry analysis showed that cinobufagin can effectively induce G2 arrest and apoptosis of DLBCL cells. In addition, cinobufagin significantly inhibited the growth of tumor tissue in a mouse model of heterotopic subcutaneous tumor transplantation. The results of transcriptome sequencing suggested that cinobufagin treatment inhibited multiple metabolism-related pathways. Metabolomic analysis showed a decrease in nucleoside metabolite content and inhibition of niacinamide synthesis. Through SEA server and 3D molecular docking simulation analysis, it was found that glucose-6-phosphate dehydrogenase (G6PD) may be a potential target of cinobufagin. G6PD activity assay showed that cinobufagin could inhibit the catalytic ability of G6PD. EdU incorporation experiments showed that cinobufagin inhibited DNA synthesis in DLBCL cells. In addition, cinobufagin also promoted the up-regulation of NADP+/NADPH ratio and the increase of ROS. The addition of ROS scavengers and nucleotides partially reversed the apoptosis-inducing ability of cinobufagin. Conclusion:G6PD is a target of cinobufagin. By inhibiting the enzyme activity of G6PD, cinobufagin can inhibit DNA synthesis and the production of reducing NADPH, thereby inducing apoptosis of DLBCL cells. This suggests that Cinobufagin has potential application as a new drug for the treatment of DLBCL.

Is there any robust evidence showing that SGLT2 inhibitor predisposes to cancer?

The exact pathophysiological mechanisms of SGLT-2 inhibitors in the development, progression or treatment of malignancies are not fully understood, but multiple hypotheses have been proposed. SGLT-2 inhibitors have potential anti-proliferative roles due to several underlying pathophysiological mechanisms, such as inhibition of ATP production, activation of AMPK signalling, induction of apoptosis and ferroptosis, inhibition of glutamate dehydrogenase activity and inhibition of DNA and RNA synthesis. However, heterogeneity among tumour cells and SGLT-2 inhibitor drugs limit the generalizability of pre-clinical studies. This is a narrative review discussing the potential anti-cancer effects of SGLT-2 inhibitors, an oral glucose-lowering medication used in patients with type II diabetes mellitus. This review discusses underlying mechanisms, pre-clinical and clinical trial data, epidemiological data and future perspectives on the use of SGLT-2 inhibitors in cancer treatment. Type II diabetes is linked to various comorbidities and malignancies, but some glucose-slowering medications may have a preventive role in cancer. The use of SGLT-2 inhibitors was associated with bladder cancer based on mice studies. However, meta-analyses showed no significant increase in overall malignancy incidence of any specific type, except for empagliflozin and bladder cancer association. SGLT-2 inhibitors can potentially reduce the heart damage caused by doxorubicin and sunitinib, while enhancing the anti-cancer effects of doxorubicin. Combining SGLT-2 inhibitors with doxorubicin may allow higher doses of chemotherapy use. Multiple ongoing clinical trials are investigating the potential therapeutic potential of SGLT-2 inhibitors in various types of cancer. More large-scale pre-clinical and clinical studies are needed to explore their potential preventive and therapeutic roles of SGLT-2 inhibitors in cancer treatment. In this narrative review, our aim is to explore the pre-clinical and clinical data regarding the potential anti-cancer effects of SGLT-2 inhibitors including the hypothetical pathophysiological mechanisms.

Nattokinase enhances the sensitivity of cancer cells to oxaliplatin through mitochondrial pathway and induction of apoptosis

Combination therapy consisting of anticancer drugs has been used to decrease the adverse effects and increase the effectiveness of the drugs. The present study aimed to examine the synergistic effect and potential mechanisms of oxaliplatin and nattokinase (NK) combined treatment for BGC-823, HepG-2, HeLa, and NCI-H460 cells. NK was isolated and purified from black soybean natto by dialysis and gel filtration chromatography, which had a nattokinase activity of 600,391 U/g. MTT experiment, clone formation assay, Hoechst 33,342 staining, DCFH-DA staining, and JC-1 staining showed that NK had no cytotoxicity and oxaliplatin could inhibit cell proliferation. Oxaliplatin combined with NK could enhance its anticancer effect and lead to mitochondrial dysfunction by causing the increase of intracellular ROS, which eventually induced apoptosis. Compared to oxaliplatin alone, nattokinase in combination with oxaliplatin can effectively inhibit DNA synthesis and increase cell uptake, ultimately inhibiting cell proliferation. Transwell and angiogenesis experiments proved that the combination of NK and oxaliplatin could more effectively inhibit cell migration, invasion, and in vitro angiogenesis, thereby preventing the spread and metastasis of tumors. RT-qPCR showed that the mechanism of inhibition of cell proliferation and thus induction of apoptosis by the combination of NK and oxaliplatin may be achieved through the upregulation of BAD, BAX, and Caspase-3 genes. Molecular docking results show that NK could act as the carrier of oxaliplatin. In conclusion, the above results suggested that NK could play a synergistic anticancer role with oxaliplatin by inducing apoptosis through the mitochondrial pathway, enhance the sensitivity of cancer cells to oxaliplatin, and provide a new strategy for cancer treatment.

NCMP-22. FLUDARABINE NEUROTOXICITY IN PATIENTS UNDERGOING CAR T-CELL THERAPY - A REPORT OF 2 CASES

Abstract Fludarabine is a purine analog used in the treatment of chronic lymphocytic leukemia (CLL) and as part of immunosuppressive/lymphodepleting regimens in allogeneic stem cell transplant and chimeric antigen receptor (CAR) T-cell therapy. It induces cellular cytotoxicity through multiple mechanisms, ultimately leading to the inhibition of DNA synthesis. Although myelosuppression is the primary dose-limiting side effect of fludarabine, there have been reported cases of delayed-onset neurological symptoms, such as progressive visual impairments, dementia, ataxia, hemiparesis, quadriparesis, and blindness. These symptoms have been observed in patients receiving fludarabine alone or as part of preconditioning treatments for CAR T-cell therapy. The neurological abnormalities are characterized by leukoencephalopathies and can manifest as posterior reversible encephalopathy (PRES), acute toxic leukoencephalopathy (ATL), or other leukoencephalopathy (OLE). We present two cases of patients who underwent fludarabine conditioning before CAR T-cell therapy, exhibiting late-onset and progressive changes in vision and encephalopathy. These symptoms differ in timing and pattern from the neurotoxicities commonly associated with CAR T-cell therapy. Nonetheless, given the overlapping neurological toxicities seen with both CAR-T cell therapy and fludarabine, it is important to consider implementing thorough screening measures to modify preconditioning fludarabine dose intensity, particularly for patients with advanced disease, renal insufficiency, or other risk factors to limit fludarabine-associated adverse effects.

Quantitative transcriptomic and proteomic analysis reveals corosolic acid inhibiting bladder cancer via suppressing cell cycle and inducing mitophagy in vitro and in vivo

Corosolic acid (CA) is a plant-derived terpenoid compound with many health benefits. However, the anti-tumor effects of CA in bladder cancer remain unexplored. Here, we found that CA inhibited bladder tumor both in vitro and in vivo, and had no significant toxicity in mice. With the aid of transcriptomics and proteomics, we elucidated the regulatory network mechanism of CA inhibiting bladder cancer. Through cell viability detection, cell fluorescence staining and flow cytometry, we discovered that CA inhibited bladder cancer mainly through blocking cell cycle. Interestingly, CA played anticancer roles by distinct mechanisms at different concentrations: low concentrations (<7.0 μg/ml) of CA mainly inhibited DNA synthesis by downregulating TOP2A and LIG1, and diminished mitosis by downregulating CCNA2, CCNB1, CDC20, and RRM2; high concentrations (≥7.0 μg/ml) of CA induced cell death through triggering mitophagy via upregulating NBR1, TAXBP1, SQSTM1/P62, and UBB. CA, as a natural molecule of homology of medicine and food, is of great significance for the prevention and treatment of cancer patients following clarifying its anti-cancer mechanism. This study provides a comprehensive understanding of the pharmacological mechanism of CA inhibition in bladder cancer, which is helpful for the development of new anti-tumor drugs based on CA.

Replisome loading reduces chromatin motion independent of DNA synthesis

Chromatin has been shown to undergo diffusional motion, which is affected during gene transcription by RNA polymerase activity. However, the relationship between chromatin mobility and other genomic processes remains unclear. Hence, we set out to label the DNA directly in a sequence unbiased manner and followed labeled chromatin dynamics in interphase human cells expressing GFP-tagged proliferating cell nuclear antigen (PCNA), a cell cycle marker and core component of the DNA replication machinery. We detected decreased chromatin mobility during the S-phase compared to G1 and G2 phases in tumor as well as normal diploid cells using automated particle tracking. To gain insight into the dynamical organization of the genome during DNA replication, we determined labeled chromatin domain sizes and analyzed their motion in replicating cells. By correlating chromatin mobility proximal to the active sites of DNA synthesis, we showed that chromatin motion was locally constrained at the sites of DNA replication. Furthermore, inhibiting DNA synthesis led to increased loading of DNA polymerases. This was accompanied by accumulation of the single-stranded DNA binding protein on the chromatin and activation of DNA helicases further restricting local chromatin motion. We, therefore, propose that it is the loading of replisomes but not their catalytic activity that reduces the dynamics of replicating chromatin segments in the S-phase as well as their accessibility and probability of interactions with other genomic regions.

Replisome loading reduces chromatin motion independent of DNA synthesis.

Chromatin has been shown to undergo diffusional motion, which is affected during gene transcription by RNA polymerase activity. However, the relationship between chromatin mobility and other genomic processes remains unclear. Hence, we set out to label the DNA directly in a sequence unbiased manner and followed labeled chromatin dynamics in interphase human cells expressing GFP-tagged proliferating cell nuclear antigen (PCNA), a cell cycle marker and core component of the DNA replication machinery. We detected decreased chromatin mobility during the S-phase compared to G1 and G2 phases in tumor as well as normal diploid cells using automated particle tracking. To gain insight into the dynamical organization of the genome during DNA replication, we determined labeled chromatin domain sizes and analyzed their motion in replicating cells. By correlating chromatin mobility proximal to the active sites of DNA synthesis, we showed that chromatin motion was locally constrained at the sites of DNA replication. Furthermore, inhibiting DNA synthesis led to increased loading of DNA polymerases. This was accompanied by accumulation of the single-stranded DNA binding protein on the chromatin and activation of DNA helicases further restricting local chromatin motion. We, therefore, propose that it is the loading of replisomes but not their catalytic activity that reduces the dynamics of replicating chromatin segments in the S-phase as well as their accessibility and probability of interactions with other genomic regions.

Caffeine-folic acid-loaded-chitosan nanoparticles combined with methotrexate as a novel HepG2 immunotherapy targeting adenosine A2A receptor downstream cascade

BackgroundMethotrexate (MTX) is a common chemotherapeutic drug that inhibits DNA synthesis and induces apoptosis. Treatment with MTX increased CD73 expression, which leads to higher levels of extracellular adenosine. Adenosine levels are also high in the tumor microenvironment through Cancer cells metabolism. That promotes the survival of cancer cells and contributes to tumor immune evasion through the Adenosine 2a Receptor. A2A receptor antagonists are an emerging class of agents that treat cancers by enhancing immunotherapy, both as monotherapy and in combination with other therapeutic agents. Caffeine is an adenosine receptor antagonist. Herein, we demonstrate the ability of a novel well prepared and characterized nano formula CAF-FA-CS-NPs (D4) for A2aR blockade when combination with MTX to improve its antitumor efficacy by enhancing the immune system and eliminating immune suppression.MethodsCAF-FA-CS-NPs (D4) were prepared and characterized for particle size, loading efficiency, and release profile. Molecular docking was used to validate the binding affinity of caffeine and folic acid to A2A receptor. The effects of the nano formula were evaluated on human liver cancer cells (HepG2), breast cancer cells (MCF-7), and MDA-MB-231, as well as normal human cells (WI-38). Different combination ratios of MTX and D4 were studied to identify the optimal combination for further genetic studies.ResultsMolecular docking results validated that caffeine and folic acid have binding affinity to A2A receptor. The CS-NPs were successfully prepared using ionic gelation method, with caffeine and folic acid being loaded and conjugated to the nanoparticles through electrostatic interactions. The CAF loading capacity in D4 was 77.9 ± 4.37% with an encapsulation efficiency of 98.5 ± 0.37. The particle size was optimized through ratio variations. The resulting nanoparticles were fully characterized. The results showed that (D4) had antioxidant activity and cytotoxicity against different cancer cells. The combination of D4 with MTX (IC50 D4 + 0.5 IC50 MTX) resulted in the downregulation of Bcl-2, FOXP3, CD39, and CD73 gene expression levels and upregulation of Bax and A2AR gene expression levels in HepG2 cells.ConclusionsThis study suggests that CAF-FA-CS-NPs (D4) in combination with MTX may be a promising candidate for cancer immunotherapy, by inhibiting A2aR signaling and leading to improved immune activation and anti-tumor activity of MTX.

Synthetic Matching of Complex Monoterpene Indole Alkaloid Chemical Space.

Monoterpene indole alkaloids (MIAs) are endowed with high structural and spatial complexity and characterized by diverse biological activities. Given this complexity-activity combination in MIAs, rapid and efficient access to chemical matter related to and with complexity similar to these alkaloids would be highly desirable, since such compound classes might display novel bioactivity. We describe the design and synthesis of a pseudo-natural product (pseudo-NP) collection obtained by the unprecedented combination of MIA fragments through complexity-generating transformations, resulting in arrangements not currently accessible by biosynthetic pathways. Cheminformatic analyses revealed that both the pseudo-NPs and the MIAs reside in a unique and common area of chemical space with high spatial complexity-density that is only sparsely populated by other natural products and drugs. Investigation of bioactivity guided by morphological profiling identified pseudo-NPs that inhibit DNA synthesis and modulate tubulin. These results demonstrate that the pseudo-NP collection occupies similar biologically relevant chemical space that Nature has endowed MIAs with.

Synthetic Matching of Complex Monoterpene Indole Alkaloid Chemical Space

AbstractMonoterpene indole alkaloids (MIAs) are endowed with high structural and spatial complexity and characterized by diverse biological activities. Given this complexity‐activity combination in MIAs, rapid and efficient access to chemical matter related to and with complexity similar to these alkaloids would be highly desirable, since such compound classes might display novel bioactivity. We describe the design and synthesis of a pseudo‐natural product (pseudo‐NP) collection obtained by the unprecedented combination of MIA fragments through complexity‐generating transformations, resulting in arrangements not currently accessible by biosynthetic pathways. Cheminformatic analyses revealed that both the pseudo‐NPs and the MIAs reside in a unique and common area of chemical space with high spatial complexity‐density that is only sparsely populated by other natural products and drugs. Investigation of bioactivity guided by morphological profiling identified pseudo‐NPs that inhibit DNA synthesis and modulate tubulin. These results demonstrate that the pseudo‐NP collection occupies similar biologically relevant chemical space that Nature has endowed MIAs with.

Screening of the novel antimicrobial drug, XF-73, against 2,527 Staphylococcus species clinical isolates.

XF-73 (exeporfinium chloride) is a synthetic, di-cationic porphyrin derivative with rapid, potent bactericidal properties and a low propensity for engendering bacterial resistance. It is being developed clinically for the decolonization of Staphylococcus aureus in the nasal cavity to prevent post-operative staphylococcal infections. This study reports the minimum inhibitory concentration (MIC) of XF-73 in comparison to 22 antibiotics against a panel of >2,500 clinical isolates composed of 16 different Coagulase-positive and -negative Staphylococcus species from 33 countries. XF-73 was found to be effective against all isolates tested, with MICs ranging between ≤0.12 - 4 µg/ml (MIC50 and MIC90 values of 0.5 and 1 µg/ml respectively). XF-73 was found to be equally effective against antibiotic resistant isolates as antibiotic sensitive isolates, with no impact of pre-existing antibiotic resistance mechanisms to cell wall synthesis inhibitors (β-lactams, carbapenems, glycopeptides and cephalosporins), protein synthesis inhibitors (oxazolidinones, macrolides and tetracyclines), DNA synthesis inhibitors (fluoroquinolones) and a folate synthesis inhibitor. The panel selected also included examples of multidrug-resistant S. aureus isolates and, in all cases, the XF-73 MIC ranges were found to be similar against each of these groups. This dataset expands the knowledge of the breadth of activity of this novel antibacterial against a wide range of global S. aureus isolates and supports the potential utility of XF-73 for the treatment of patients who are S. aureus nasal carriers. Similar results were also obtained for multidrug-resistant isolates of other Staphylococcus species included in the study and collectively support the continued clinical development of XF-73 as an effective anti-staphylococcal drug.

Escherichia coli cytosine deaminase: Structural and biotechnological aspects.

Suicide gene therapy involves introducing viral or bacterial genes into tumor cells, which enables the conversion of a nontoxic prodrug into a toxic-lethal drug. The application of the bacterial cytosine deaminase (bCD)/5-fluorocytosine (5-FC) approach has been beneficial and progressive within the current field of cancer therapy because of the enhanced bystander effect. The basis of this method is the preferential deamination of 5-FC to 5-fluorouracil by cancer cells expressing cytosine deaminase (CD), which strongly inhibits DNA synthesis and RNA function, effectively targeting tumor cells. However, the poor binding affinity of toward 5-FC compared to the natural substrate cytosine and/or inappropriate thermostability limits the clinical applications of this gene therapy approach. Nowadays, many genetic engineering studies have been carried out to solve and improve the activity of this enzyme. In the current review, we intend to discuss the biotechnological aspects of Escherichia coli CD, including its structure, functions, molecular cloning, and protein engineering. We will also explore its relevance in cancer clinical trials. By examining these aspects, we hope to provide a thorough understanding of E. coli CD and its potential applications in cancer therapy.

A Review on the Antimutagenic and Anticancer Effects of Cysteamine.

Cancer is one of the leading causes of death worldwide. First-line treatments usually include surgery, radiotherapy, and/or systemic therapy. These methods can be associated with serious adverse events and can be toxic to healthy cells. Despite the new advances in cancer therapies, there is still a continuous need for safe and effective therapeutic agents. Cysteamine is an aminothiol endogenously synthetized by human cells during the degradation of coenzyme-A. It has been safely used in humans for the treatment of several pathologies including cystinosis and neurodegenerative diseases. Cysteamine has been shown to be a potent antimutagenic, anticarcinogenic, and antimelanoma in various in vitro and in vivo studies, but a review on these aspects of cysteamine's use in medicine is lacking in the current literature. The efficacy of cysteamine has been shown in vitro and in vivo for the treatment of different types of cancer, such as gastrointestinal cancer, pancreatic cancer, sarcomas, hepatocellular carcinoma, and melanoma, leading to the significant reduction of lesions and/or the increase of survival time. Although the mechanisms of action are not fully understood, possible explanations are (i) free radical scavenging, (ii) alteration of the tumor cell proliferation by affecting nucleic acid and protein synthesis or inhibition of DNA synthesis, and (iii) hormone regulation. In conclusion, regarding the high safety profile of cysteamine and the current literature data presented in this article, cysteamine might be considered as an interesting molecule for the prevention and the treatment of cancer. Further clinical studies should be performed to support these data in humans.

ОЦЕНКА ГЕНОТОКСИЧЕСКОГО ВОЗДЕЙСТВИЯ МИТОМИЦИНА С НА ПРИМЕРЕ APOE НОКАУТНЫХ МЫШЕЙ

BACKGROUND Mitomycin C (MMC) has a wide spectrum of genotoxicity, including inhibition of DNA synthesis, clastogenesis and mutagenesis. As an immediate-action clastogen requiring exclusively intracellular reductive activation, MMC initiates efficient DNA cross-linking. Most studies are aimed at studying single-stage acute effects, which are caused by high doses of mutagen. In turn, there are no or very few studies aimed at studying the chronic effects of MMC. Polychrome red blood cells have been accepted as a suitable target for the evaluation of micronuclei in both acute and cumulative injury. The in vivo micronucleus test is well established as a standard assay for assessing genotoxicity at the chromosomal level of mouse erythrocytes. THE AIM OF THE STUDY To create a chronic genotoxic effect of mitomycin C without lethal outcome in ApoE knockout mice while selecting the optimal dose of MMC. MATERIALS AND METHODS The study design included 6 groups of ApoE-/- mice, two doses of MMC with a concentration of 0.1 and 0.5 mg/kg, one-time and three-time administration. To assess genotoxicity, 1000 polychrome erythrocytes (PCEs) extracted from the bone marrow of a mousefemur were counted on each sample, and PCEs with micronuclei were identified. RESULTS This study aimed to find the optimal dose of MMC that has a clear genotoxic effect and does not lead to death in an ApoE knockout mouse model. With a single injection, PCEs with chromosomal damage were more common (more than 2 times; p &lt; 0.05) in groups of mice with MMC administration (0.1 and 0.5 mg/kg; 0.39 % and 0.26 %, respectively) compared to the control group (0.15 %). We also found that the frequency of occurrence of PCEs with micronuclei in groups of mice with MMC dose of 0.1 and 0.5 mg/kg (0.36 % and 0.47 %, respectively) and three-time administration exceeded this indicator in mice from the control group (0.2 %). CONCLUSION The present study on the determination of the optimal dose of mitomycin C provides further evidence that 0.1 mg/kg is the threshold value for genotoxic effects caused by MMC. An increase in the frequency of micronucleated immature red blood cells in animals exposed to a mutagen is an indicator of induced structural or numerical chromosomal aberrations. Our results further suggest that careful selection of MMC dose is critical. Dose-response studies in rodents can provide useful information on mechanisms and dose selection for long-term toxicity studies.

DHODH: a promising target in the treatment of T-cell acute lymphoblastic leukemia

AbstractPatients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL) have a poor prognosis with few therapeutic options. With the goal of identifying novel therapeutic targets, we used data from the Dependency Map project to identify dihydroorotate dehydrogenase (DHODH) as one of the top metabolic dependencies in T-ALL. DHODH catalyzes the fourth step of de novo pyrimidine nucleotide synthesis. Small molecule inhibition of DHODH rapidly leads to the depletion of intracellular pyrimidine pools and forces cells to rely on extracellular salvage. In the absence of sufficient salvage, this intracellular nucleotide starvation results in the inhibition of DNA and RNA synthesis, cell cycle arrest, and, ultimately, death. T lymphoblasts appear to be specifically and exquisitely sensitive to nucleotide starvation after DHODH inhibition. We have confirmed this sensitivity in vitro and in vivo in 3 murine models of T-ALL. We identified that certain subsets of T-ALL seem to have an increased reliance on oxidative phosphorylation when treated with DHODH inhibitors. Through a series of metabolic assays, we show that leukemia cells, in the setting of nucleotide starvation, undergo changes in their mitochondrial membrane potential and may be more highly dependent on alternative fuel sources. The effect on normal T-cell development in young mice was also examined to show that DHODH inhibition does not permanently damage the developing thymus. These changes suggest a new metabolic vulnerability that may distinguish these cells from normal T cells and other normal hematopoietic cells and offer an exploitable therapeutic opportunity. The availability of clinical-grade DHODH inhibitors currently in human clinical trials suggests a potential for rapidly advancing this work into the clinic.

Dose-Response of the Mitomycin C Genotoxic Effect on the ApoE Knockout Mice

Polychromic erythrocytes have been accepted as a suitable target for micronucleus (MN) evaluation in both acute and cumulative injury. Mitomycin C (MMC) also has a wide range of genotoxicity, including inhibition of DNA synthesis, clastogenesis and mutagenesis. As an immediate clastogen requiring exclusively intracellular reductive activation, MMS initiates efficient DNA crosslinking. The in vivo micronucleus assay has established itself as a standard assay for evaluating chromosomal genotoxicity in mouse erythrocytes. Most of the studies are focused on the study of acute acute effects, which is caused by high doses of the mutagen. In turn, there are no or very few studies aimed at studying the chronic effects of MMS. The aim of the study is to create a chronic genotoxic effect of MMS without lethal outcome in ApoE–/– mice when selecting the optimal dose of MMS. The design of the study included 6 groups of ApoE–/– mice, two doses of MMC at a concentration of 0.1 and 0.5 mg/kg, single and three doses. Each group consisted of four females and one male. To assess genotoxicity, 1000 polychromic erythrocytes (PChE) extracted from the femoral bone marrow were counted on each sample, PChE with micronuclei were detected, and the proportion of reticulocytes was counted. A dose of 0.5 mg/kg showed a clear cytotoxic effect, expressed in a violation of erythropoiesis, and more precisely in a decrease in the proportion of reticulocytes. In our study, the concentration of the mutagen, namely 0.1 mg/kg, was shown to cause a clear genotoxic effect without reaching the threshold of cytotoxicity. Dose-response studies in rodents can provide useful information on the mechanisms of toxicity and dose selection for long-term toxicity studies.

Rh(III) and Ru(II) complexes with phosphanyl-alkylamines: inhibition of DNA synthesis induced by anticancer Rh complex.

Aim: This investigation was designed to synthesize half-sandwich Rh(III) and Ru(II) complexes and study their antiproliferative activity in human cancer cell lines. Materials & methods: Nine compounds were prepared and tested by various assays for their anticancer activity and mechanism of action. Results: Hit Rh(III) complex 6 showed low-micromolar potency in cisplatin-sensitive (A2780) and -resistant (A2780cis) ovarian carcinoma cell lines, promising selectivity toward these cancer cells over normal lung fibroblasts and anunprecedented mechanism of action in the treated cells. DNA synthesis was decreased andCDKN1A expression was upregulated, but p21 expression was not induced. Conclusion: Rh complex 6 showed high antiproliferative activity, which is induced through a p21-independent mechanism of action.

Sulfated Polysaccharides from Seaweeds: A Promising Strategy for Combatting Viral Diseases-A Review.

The limited availability of treatments for many infectious diseases highlights the need for new treatments, particularly for viral infections. Natural compounds from seaweed are attracting increasing attention for the treatment of various viral diseases, and thousands of novel compounds have been isolated for the development of pharmaceutical products. Seaweed is a rich source of natural bioactive compounds, including polysaccharides. The discovery of algal polysaccharides with antiviral activity has significantly increased in the past few decades. Furthermore, unique polysaccharides isolated from seaweeds, such as carrageenan, alginates, fucoidans, galactans, laminarians, and ulvans, have been shown to act against viral infections. The antiviral mechanisms of these agents are based on their inhibition of DNA or RNA synthesis, viral entry, and viral replication. In this article, we review and provide an inclusive description of the antiviral activities of algal polysaccharides. Additionally, we discuss the challenges and opportunities for developing polysaccharide-based antiviral therapies, including issues related to drug delivery and formulation. Finally, this review highlights the need for further research for fully understanding the potential of seaweed polysaccharides as a source of antiviral agents and for developing effective treatments for viral diseases.