Potential role of poly(ADP-ribose) polymerase (PARP) activation in methotrexate-induced nephrotoxicity and tubular apoptosis

Small molecule tractable PARP inhibitors: Scaffold construction approaches, mechanistic insights and structure activity relationship

Diverse drug design strategies viz. molecular hybridization, substituent installation, scaffold hopping, isosteric replacement, high-throughput screening, induction and separation of chirality, structure modifications of phytoconstituents and use of structural templates have been exhaustively leveraged in the last decade to load the chemical toolbox of PARP inhibitors. Resultantly, numerous promising scaffolds have been pinpointed that in turn have led to the resuscitation of the credence to PARP inhibitors as cancer therapeutics. This review briefly presents the physiological functions of PARPs, the pharmacokinetics, and pharmacodynamics, and the interaction profiles of FDA-approved PARP inhibitors. Comprehensively covered is the section on the drug design strategies employed by drug discovery enthusiasts for furnishing PARP inhibitors. The impact of structural variations in the template of designed scaffolds on enzymatic and cellular activity (structure-activity relationship studies) has been discussed. The insights gained through the biological evaluation such as profiling of physicochemical properties andin vitroADME properties, PK assessments, and high-dose pharmacology are covered.

Bilayer Forming Phospholipids as Targets for Cancer Therapy

Phospholipids represent a crucial component for the structure of cell membranes. Phosphatidylcholine and phosphatidylethanolamine are two phospholipids that comprise the majority of cell membranes. De novo biosynthesis of phosphatidylcholine and phosphatidylethanolamine occurs via the Kennedy pathway, and perturbations in the regulation of this pathway are linked to a variety of human diseases, including cancer. Altered phosphatidylcholine and phosphatidylethanolamine membrane content, phospholipid metabolite levels, and fatty acid profiles are frequently identified as hallmarks of cancer development and progression. This review summarizes the research on how phospholipid metabolism changes over oncogenic transformation, and how phospholipid profiling can differentiate between human cancer and healthy tissues, with a focus on colorectal cancer, breast cancer, and non-small cell lung cancer. The potential for phospholipids to serve as biomarkers for diagnostics, or as anticancer therapy targets, is also discussed.

Additional functions of selected proteins involved in DNA repair

Protein moonlighting is a phenomenon in which a single polypeptide chain can perform a number of different unrelated functions. Here we present our analysis of moonlighting in the case of selected DNA repair proteins which include G:T mismatch-specific thymine DNA glycosylase (TDG), methyl-CpG-binding domain protein 4 (MBD4), apurinic/apyrimidinic endonuclease 1 (APE1), AlkB homologs, poly (ADP-ribose) polymerase 1 (PARP-1) and single-strand selective monofunctional uracil DNA glycosylase 1 (SMUG1). Most of their additional functions are not accidental and clear patterns are emerging. Participation in RNA metabolism is not surprising as bases occurring in RNA are the same or very similar to those in DNA. Other common additional function involves regulation of transcription. This is not unexpected as these proteins bind to specific DNA regions for DNA repair, hence they can also be recruited to regulate transcription. Participation in demethylation and replication of DNA appears logical as well. Some of the multifunctional DNA repair proteins play major roles in many diseases, including cancer. However, their moonlighting might prove a major difficulty in the development of new therapies because it will not be trivial to target a single protein function without affecting its other functions that are not related to the disease.

Toxic Effects of Methotrexate on Rat Kidney Recovered by Crocin as a Consequence of Antioxidant Activity and Lipid Peroxidation Prevention

Background

The application of methotrexate (MTX) as a chemotherapy agent and immune system suppressant has various side effects. Crocin, a xanthine derivative plant, has many therapeutic benefits. This study was planned to assess the effect of crocin on renal toxicity of MTX in a rat model.

Methods

Forty eight rats were divided randomly into eight groups (n = 6), which received normal saline, MTX, crocin, and MTX + crocin for 28 days intraperitoneally. The levels of oxidative stress in kidney and blood serum were measured, and the kidney was analyzed histologically.

Results

MTX caused an enhancement in the levels of thiobarbituric acid reactive substances and biochemical marker (creatinine and BUN). Besides, a significant decrease was observed in tissue parameters and antioxidant capacity compared to the normal control group (p < 0.001). The crocin and crocin + MTX decreased the biochemical markers, the levels of thiobarbituric acid reactive species, and tissue parameters considerably at entire dose (12.5, 25, and 50 mg/kg) and enhanced the antioxidant capacity levels compared to the MTX group (p < 0.001).

Conclusion

Administration of crocin improves the damage caused by MTX in rats. The crocin by the establishment of balance in the levels of antioxidant prevents the damage to the renal cell membrane, and subsequently the renal damage repairs.

Lycopene improves methotrexate-induced functional alterations of the Madin-Darby kidney cells in a concentration-dependent manner

Lycopene is one of the most potent antioxidants among carotenoids due to its ability to quench singlet oxygen and react with free radicals to reduce DNA damage. Methotrexate is widely used in the treatment of several types of cancers and autoimmune diseases. One of the most common side effects of a high-dose of methotrexate is kidney injury. In this study, we evaluated effects of lycopene on the Madin-Darby canine kidney cells (MDCK) treated with methotrexate through the estimation of their mitochondrial and lysosomal functions ((4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide reduction assay and neutral red uptake assay) and changes in cell oxidative status (determination of advanced oxidized proteins concentrations and reduced glutathione levels) and lysosomal enzymes activity (β-N-acetyl glucosaminidase activity). Results of our study showed that lycopene applied in high concentration caused significant impairment of the MDCK function leading to cell death. Contrarily, in relatively low concentrations lycopene moderately ameliorated methotrexate-induced MDCK cell death estimated by both biochemical and microscopic analyses. It also prevented a significant decline in the MDCK cell lysosomal function estimated by neutral red accumulation ability and activity of the lysosomal enzyme β-N-acetyl glucosaminidase.

Deoxyuracil in DNA and disease: Genomic signal or managed situation?

Genomic instability is implicated in the etiology of several deleterious health outcomes including megaloblastic anemia, neural tube defects, and neurodegeneration. Uracil misincorporation and its repair are known to cause genomic instability by inducing DNA strand breaks leading to apoptosis, but there is emerging evidence that uracil incorporation may also result in broader modifications of gene expression, including: changes in transcriptional stalling, strand break-mediated transcriptional upregulation, and direct promoter inhibition. The factors that influence uracil levels in DNA are cytosine deamination, de novo thymidylate (dTMP) biosynthesis, salvage dTMP biosynthesis, dUTPase, and DNA repair. There is evidence that the nuclear localization of the enzymes in these pathways in mammalian cells may modify and/or control the levels of uracil accumulation into nuclear DNA. Uracil sequencing technologies demonstrate that uracil in DNA is not distributed stochastically across the genome, but instead shows patterns of enrichment. Nuclear localization of the enzymes that modify uracil in DNA may serve to change these patterns of enrichment in a tissue-specific manner, and thereby signal the genome in response to metabolic and/or nutritional state of the cell.

In vivo pharmacological evaluation and efficacy study of methotrexate-encapsulated polymer-coated layered double hydroxide nanoparticles for possible application in the treatment of osteosarcoma

Considering the existing drawbacks of methotrexate (MTX) with respect to its solubility and toxicity, we incorporated it in a nanoceramic matrix, Mg-Al-layered double hydroxide (LDH) to form LDH-MTX nanoparticles, and the same was in turn encapsulated in a nontoxic and biodegradable polymer, poly (D,L-lactide-co-glycolide) (PLGA), to arrest the initial burst release and dose-dumping-related toxicity, already reported by our group. Our present study was designed to evaluate the pharmacokinetics, tissue distribution, survival rate of the test animals, and antitumor efficacy of the PLGA-LDH-MTX nanoparticles and its counterpart without LDH, PLGA-MTX nanoparticles compared with bare MTX. The median lethal dose (LD₅₀) of the former was higher, compared with bare MTX, using Balb/c nude mice, indicating it to be completely safe for use. Also, a comparative pharmacokinetic and antitumour efficacy study using MTX, PLGA-MTX, and PLGA-LDH-MTX nanoparticles in osteosarcoma-induced Balb/c nude mice in vivo demonstrated superiority of PLGA-LDH-MTX as compared to PLGA-MTX and bare MTX. The results suggest that PLGA-LDH-MTX nanoparticles might exhibit potential advantages over the present-day chemotherapy over bare MTX, for the possibility of treatment of osteosarcoma.

PARP1 in Carcinomas and PARP1 Inhibitors as Antineoplastic Drugs

Poly (ADP-ribose) polymerase 1 (PARP1), the best-studied isoform of the nuclear enzyme PARP family, plays a pivotal role in cellular biological processes, such as DNA repair, gene transcription, and so on. PARP1 has been found to be overexpressed in various carcinomas. These all indicate the clinical potential of PARP1 as a therapeutic target of human malignancies. Additionally, multiple preclinical research studies and clinical trials demonstrate that inhibition of PARP1 can repress tumor growth and metastasis. Up until now, PARP1 inhibitors are clinically used not only for monotherapy to suppress various tumors, but also for adjuvant therapy, to maintain or enhance therapeutic effects of mature antineoplastic drugs, as well as protect patients from chemotherapy and surgery-induced injury. To supply a framework for understanding recent research progress of PARP1 in carcinomas, we review the structure, expression, functions, and mechanisms of PARP1, and summarize the clinically mature PARP1-related anticancer agents, to provide some ideas for the development of other promising PARP1 inhibitors in antineoplastic therapy.

Evaluation of The Protective Effect of Hydro-Alcoholic Extract of Raspberry Fruit on Aquaporin1 Expression in Rats Kidney Treated by Methotrexate

OBJECTIVE

Methotrexate (MTX) is an antimetabolite drug commonly prescribed for the various cancers and autoimmune diseases. Despite its considerable therapeutic effects, nephrotoxicity is the most important side-effect of treatment with MTX. Aquaporin1 (AQP1) is a water channel proteins which is present in mammalian kidney. Raspberry fruit with antioxidant properties is able to protect biological systems from the harmful effects of free radicals. The purpose of this study was to investigate the effect of raspberry extract on expression of AQP1 and the MTX-induced nephrotoxicity in rats.

MATERIALS AND METHODS

In this experimental study, 60 adult male Wistar rats were divided into nine groups including control, sham, MTX treated group [single dose of 20 mg/kg of body weight (BW) MTX at the third day], raspberry treated groups [intraperitoneal (I.P) injection of 100, 200, 400 mg/kg of BW raspberry extract for ten consecutive days], MTX and raspberry treated groups. At day 11, rats were sacrificed via chloroform inhalation and kidney tissues were fixed in formalin solution for histological and immunohistochemistry analysis. The serological assays for urea, creatinine, uric acid and interleukin-6 (IL-6) levels were also performed.

RESULTS

MTX elevated serum level of the urea, creatinine, uric acid, IL-6, renal tissue damage and decreased the AQP1 expression level. Raspberry fruit extract improved the kidney function and reduced side effects of MTX in treated rats. Expression of AQP1, in a dose dependent manner was also ameliorated, as compared to control group.

CONCLUSION

According to the findings of this study, it can be concluded that biological activity of compounds presented in raspberry fruit extract especially anthocyanins may have chemo-protective effect on kidney function and AQP1 expression in rats treated by MTX.

Nicotinamide Phosphoribosyltransferase Attenuates Methotrexate Response in Juvenile Idiopathic Arthritis and In Vitro

Variability in response to methotrexate (MTX) in the treatment of juvenile idiopathic arthritis (JIA) remains unpredictable and poorly understood. Based on previous studies implicating an interaction between nicotinamide phosphoribosyltransferase (NAMPT) expression and MTX therapy in inflammatory arthritis, we hypothesized that increased NAMPT expression would be associated with reduced therapeutic response to MTX in patients with JIA. A significant association was found between increased plasma concentrations of NAMPT and reduced therapeutic response in patients with JIA treated with MTX. Inhibition of NAMPT in cell culture by either siRNA‐based gene silencing or pharmacological inhibition with FK‐866 was found to result in a fourfold increase in the pharmacological activity of MTX. Collectively, these findings provide evidence that NAMPT inhibits the pharmacological activity of MTX and may represent a predictive biomarker of response, as well as a therapeutic target, in the treatment of JIA with MTX.

N-acetylcysteine renoprotection in methotrexate induced nephrotoxicity and its effects on B-cell lymphoma

Background:

Nephrotoxicity is one of the known side effects of methotrexate (MTX) therapy despite the use of conventional protective measures. Our objectives were to evaluate the effects of N-acetylcysteine (NAC) on MTX-induced toxicity in renal tubular cells and to evaluate whether adjunctive use of NAC interferes with MTX antitumor activity in the B-cell lymphoma.

Methods:

Kidney Epithelial (Madin-Darby canine kidney [MDCK]) cells were exposed to MTX (10 μM or 100 μM) alone and with NAC (0.2 mM or 0.4 mM). Reactive oxygen species (ROS) generation at 1, 2, 4, and 24 h was measured by flow cytometer. Quantification of total glutathione (GSH) was performed by using GSH assay kit. To measure the impact of NAC on the antitumor activity of MTX, B lymphoma cells were exposed to MTX alone and with NAC. A percentage of apoptosis was measured using fluorescein isothiocyanate in both cell lines. Quantitative data was presented as a means ± standard deviation, and P values were analyzed using the Student's t-test.

Results:

Apoptosis in MDCK cells were observed after 24 h of incubation with both 10 μM and 100 μM MTX. Maximum ROS generation was observed at 4 h and corresponded to GSH production. Treatment with 0.2 and 0.4 mM of NAC led to decrease percentages of apoptotic MDCK cells. NAC did not change either proliferation or apoptosis of B-cell lymphoma.

Conclusion:

Using NAC for kidney protection may not interfere with the antitumor activity of MTX. Further in vivo studies are warranted to confirm noninterference between MTX and NAC and assess synergistic antitumor effects.

Ascidian Tunicate Extracts Attenuate Rheumatoid Arthritis in a Collagen-induced Murine Model

Murine rheumatoid arthritis models are often used to investigate the potential therapeutic effects of candidate drugs. The present study has been conducted in order to investigate the therapeutic efficacy of ascidian tunicate extracts in a collagen-induced arthritis DBA1/J mice model. Four types of formulas, ascidian tunicate extracts (ATE), crude ascidian tunicate glycans (ATEC), ascidian tunicate extracts with licorice extracts (ATEL), and crude ascidian tunicate glycans with licorice extracts (ATECL) were orally administered into DBA/1J mice for 3 weeks and paw edema and thickness were evaluated. Changes in inflammatory proteins and cytokines levels were monitored in hind leg tissues by Western blot and quantitative PCR analysis. The oral administration of ascidian tunicate extracts alleviated paw edema and improved the histological hind leg cartilage status. The extracts also reduced the matrix metalloproteinase-9 (MMP-9) protein and prostaglandin E synthase (PGES) levels. In addition, the extracts-treated groups showed increased interleukin-10 (IL-10) levels compared with the non-treated group. These findings suggest that orally administered ascidian tunicate extracts might have potential therapeutic effects for the treatment of rheumatoid arthritis.

Beyond DNA Repair: Additional Functions of PARP-1 in Cancer

Poly(ADP-ribose) polymerases (PARPs) are DNA-dependent nuclear enzymes that transfer negatively charged ADP-ribose moieties from cellular nicotinamide-adenine-dinucleotide (NAD(+)) to a variety of protein substrates, altering protein-protein and protein-DNA interactions. The most studied of these enzymes is poly(ADP-ribose) polymerase-1 (PARP-1), which is an excellent therapeutic target in cancer due to its pivotal role in the DNA damage response. Clinical studies have shown susceptibility to PARP inhibitors in DNA repair defective cancers with only mild adverse side effects. Interestingly, additional studies are emerging which demonstrate a role for this therapy in DNA repair proficient tumors through a variety of mechanisms. In this review, we will discuss additional functions of PARP-1 - including regulation of inflammatory mediators, cellular energetics and death pathways, gene transcription, sex hormone- and ERK-mediated signaling, and mitosis - and the role these PARP-1-mediated processes play in oncogenesis, cancer progression, and the development of therapeutic resistance. As PARP-1 can act in both a pro- and anti-tumor manner depending on the context, it is important to consider the global effects of this protein in determining when, and how, to best use PARP inhibitors in anticancer therapy.