Phosphoramide mustard exposure induces DNA adduct formation and the DNA damage repair response in rat ovarian granulosa cells

TP63 truncating mutation causes increased cell apoptosis and premature ovarian insufficiency by enhanced transcriptional activation of CLCA2

BACKGROUND

Premature ovarian insufficiency (POI) is a severe disorder leading to female infertility. Genetic mutations are important factors causing POI. TP63-truncating mutation has been reported to cause POI by increasing germ cell apoptosis, however what factors mediate this apoptosis remains unclear.

METHODS

Ninety-three patients with POI were recruited from Beijing Obstetrics and Gynecology Hospital, Capital Medical University. Whole-exome sequencing (WES) was performed for each patient. Sanger sequencing was used to confirm potential causative genetic variants. A minigene assay was performed to determine splicing effects of TP63 variants. A TP63-truncating plasmid was constructed. Real-time quantitative PCR, western blot analyses, dual luciferase reporter assays, immunofluorescence staining, and cell apoptosis assays were used to study the underlying mechanism of a TP63-truncating mutation causing POI.

RESULTS

By WES of 93 sporadic patients with POI, we found a 14-bp deletion covering the splice site in the TP63 gene. A minigene assay demonstrated that the 14-bp deletion variant led to exon 13 skipping during TP63 mRNA splicing, resulting in the generation of a truncated TP63 protein (TP63-mut). Overexpression of TP63-mut accelerated cell apoptosis. Mechanistically, the TP63-mut protein could bind to the promoter region of CLCA2 and activate the transcription of CLCA2 several times compared to that of the TP63 wild-type protein. Silencing CLCA2 using a specific small interfering RNA (siRNA) or inhibiting the Ataxia Telangiectasia Mutated (ATM) pathway using the KU55933 inhibitor attenuated cell apoptosis caused by TP63-mut protein expression.

CONCLUSION

Our findings revealed a crucial role for CLCA2 in mediating apoptosis in POI pathogenesis, and suggested that CLCA2 is a potential therapeutic target for POI.

Research progress on mitochondrial damage and repairing in oocytes: A review

Oocytes are the female germ cells, which are susceptible to stress stimuli. The development of oocytes in the ovary is affected by many environmental and metabolic factors, food toxins, aging, and pathological factors. Mitochondria are the main target organelles of these factors, and the damage to mitochondrial structure and function can affect the production of ATP, the regulation of redox reactions, and apoptosis in oocytes. Mitochondrial damage is closely related to the decrease in oocyte quality and is the main factor leading to female infertility. Antioxidant foods or drugs have been used to prevent mitochondrial damage from some stressors or to repair damaged mitochondria, thereby improving oocyte development and female reproductive outcomes. In this paper, the damage of mitochondria during oocyte development by the above factors has been reviewed, and the relevant measures to alleviate the damage of mitochondria in oocytes have been discussed. Our findings may provide a theoretical basis and experimental basis for improving female fertility.

Premature ovarian insufficiency: a review on the role of oxidative stress and the application of antioxidants

Normal levels of reactive oxygen species (ROS) play an important role in regulating follicular growth, angiogenesis and sex hormone synthesis in ovarian tissue. When the balance between ROS and antioxidants is disrupted, however, it can cause serious consequences of oxidative stress (OS), and the quantity and quality of oocytes will decline. Therefore, this review discusses the interrelationship between OS and premature ovarian insufficiency (POI), the potential mechanisms and the methods by which antioxidants can improve POI through controlling the level of OS. We found that OS can mediate changes in genetic materials, signal pathways, transcription factors and ovarian microenvironment, resulting in abnormal apoptosis of ovarian granulosa cells (GCs) and abnormal meiosis as well as decreased mitochondrial Deoxyribonucleic Acid(mtDNA) and other changes, thus accelerating the process of ovarian aging. However, antioxidants, mesenchymal stem cells (MSCs), biological enzymes and other antioxidants can delay the disease process of POI by reducing the ROS level in vivo.

Altered hallmarks of DNA double-strand breaks, oxidative DNA damage and cytogenotoxicity by piperlongumine in hippocampus and hepatocytes of rats intoxicated with cyclophosphamide

AIM

Cyclophosphamide is an effective anti-tumor agent, however, it induces genomic instability and tissue toxicity in clinical application. This study aims to evaluate the action of piperlongumine against cyclophosphamide-induced toxicity.

MAIN METHODS

The action was investigated in rodent model of genomic instability, where piperlongumine (50 mg/kg) was orally co-administered with cyclophosphamide (5 mg/kg) for 28 days to Wistar albino rats. Further, piperlongumine was also examined for acute and sub-acute toxicity.

KEY FINDINGS

Piperlongumine significantly reversed genotoxicity in high-proliferation tissue (bone marrow: p < 0.05) as well as in vital tissues (hippocampus: p < 0.01 and hepatocytes: p < 0.05), calculated as micronuclei formation and %DNA fragmentation. It also restored the redox homeostasis, counteracted the formation of oxidative DNA damage product and DNA double-strand break in vital tissues, indicated by reduction of 8-OHdG and γH2AX. TUNEL assay revealed that piperlongumine diminished the cyclophosphamide-associated apoptotic cell death in hippocampus as well as in liver tissue and conferred cytoprotection to the host. These findings were finally corroborated with the histopathological findings, where piperlongumine treatment restored the cellular viability of liver and hippocampus. Further, piperlongumine did not produce any toxic effects to rats in systemic toxicity studies.

SIGNIFICANCE

Piperlongumine possesses genome stabilizing effect and reduces cyclophosphamide-associated DNA damage, oxidative stress, hepato-, and neurotoxicity, diminishes the DNA damage response pathway in the rat model, at the same time, conserves the micro-architectural details of liver and hippocampus. The findings are significant in terms of reducing genotoxic impact of chemotherapy-receiving patients.

Therapeutic potential of bone marrow mesenchymal stem cells in cyclophosphamide-induced infertility

Cancer is a deadly disease characterized by abnormal cell proliferation. Chemotherapy is one technique of cancer treatment. Cyclophosphamide (CYP) is the most powerful chemotherapy medication, yet it has serious adverse effects. It is an antimitotic medicine that regulates cell proliferation and primarily targets quickly dividing cells, and it has been related to varying levels of infertility in humans. In the current study, we assessed the biochemical, histological, and microscopic evaluations of testicular damage following cyclophosphamide administration. Further, we have explored the potential protective impact of mesenchymal stem cell (MSCs) transplantation. The biochemical results revealed that administration of cyclophosphamide increased serum concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), while it decreased serum concentrations of free testosterone hormone (TH), testicular follicle-stimulating hormone, luteinizing hormone, and free testosterone hormone concentrations, testicular total antioxidant capacity (TAC), and testicular activity of superoxide dismutase (SOD) enzyme. The histology and sperm examinations revealed that cyclophosphamide induced destruction to the architectures of several tissues in the testes, which drastically reduced the Johnsen score as well as the spermatogenesis process. Surprisingly, transplantation of mesenchymal stem cell after cyclophosphamide administration altered the deterioration effect of cyclophosphamide injury on the testicular tissues, as demonstrated by biochemical and histological analysis. Our results indicated alleviation of serum and testicular sex hormones, as well as testicular oxidative stress markers (total antioxidant capacity and superoxide dismutase activity), and nearly restored the normal appearance of the testicular tissues, Johnsen score, and spermatogenesis process. In conclusion, our work emphasizes the protective pharmacological use of mesenchymal stem cell to mitigate the effects of cyclophosphamide on testicular tissues that impair the spermatogenesis process following chemotherapy. These findings indicate that transferring mesenchymal stem cell to chemotherapy patients could significantly improve spermatogenesis.

Protective Effects of Antioxidants on Cyclophosphamide-Induced Ovarian Toxicity

The most common limitation of anticancer chemotherapy is the injury to normal cells. Cyclophosphamide, which is one of the most widely used alkylating agents, can cause premature ovarian insufficiency and infertility since the ovarian follicles are extremely sensitive to their effects. Although little information is available about the pathogenic mechanism of cyclophosphamide-induced ovarian damage, its toxicity is attributed to oxidative stress, inflammation, and apoptosis. The use of compounds with antioxidant and cytoprotective properties to protect ovarian function from deleterious effects during chemotherapy would be a significant advantage. Thus, this article reviews the mechanism by which cyclophosphamide exerts its toxic effects on the different cellular components of the ovary, and describes 24 cytoprotective compounds used to ameliorate cyclophosphamide-induced ovarian injury and their possible mechanisms of action. Understanding these mechanisms is essential for the development of efficient and targeted pharmacological complementary therapies that could protect and prolong female fertility.

Protective effects of a SIRT1 inhibitor on primordial follicle activation and growth induced by cyclophosphamide: insights from a bovine in vitro folliculogenesis system

Purpose

Although oncological advances have improved survival rates of female cancer patients, they often suffer a reduced fertility due to treatment side effects. In the present study, we evaluated the potential fertoprotective effects of the specific inhibitor of SIRT1, EX-527, on the gonadotoxic action exerted by cyclophosphamide (CPM) on loss of primordial follicles (PFs).

Methods

The effects of the CPM metabolite phosphoramide mustard (PM) on follicle activation, growth and viability and the protective action of EX-527 against PM effects were evaluated on bovine ovarian cortical strips in vitro cultured for 1 or 6 days. To understand whether PFs exposed to PM plus EX-527 were able to activate and grow to the secondary stage after suspension of the treatment, strips cultured for 3 days in PM plus EX-527 for 3 days were transferred to plain medium until day 6. Follicle growth and health were evaluated through histology and viability assay at a confocal microscope. In order to investigate the molecular pathways underlying the ovarian response to PM in the presence of EX-527, we analysed the protein level of SIRT1, HuR, PARP1 and SOD2 after 1 day of in vitro culture.

Results

We found that (1) PM, the main CPM active metabolite, promotes PF activation; (2) the ovarian stress response induced by PM includes a SIRT1-dependent pathway; and (3) EX-527 reduces PF activation and growth induced by PM.

Conclusion

SIRT1 can represent a candidate molecule to be targeted to protect ovarian follicles from alkylating agents and EX-527 could represent a potential fertoprotective agent for cancer patients.

Low dosage use of cyclophosphamide improves the survival of patients with systemic lupus erythematosus

OBJECTIVE

To investigate the effect of cyclophosphamide (CYC) on organ involvement and SLE patients' overall and cause-specific mortality.

METHODS

Information about CYC prescription was taken from the Jiangsu Lupus database, which was set up to collect medical records from SLE patients since their first admission during 1999-2009 in Jiangsu province, China. Follow-up studies were carried out in 2010 and 2015 to check the survival status of the patients. Cox regression models were used to estimate the hazard ratio (HR) and 95% CI. Kaplan-Meier model was used to assess the effect of CYC on mortality between organ involvement and non-involvement.

RESULTS

There were 221 deaths observed out of 2446 SLE patients. CYC users decreased overall mortality of SLE (8.4%) with adjusted HR (95% CI) of 0.74 (0.56-0.97), as compared to non-users. A decrease in overall mortality of SLE was found in the low dosage (< 600 mg) of CYC users, with adjusted HR (95% CI) of 0.54 (0.36-0.81). The protection of CYC on mortality of SLE was further observed in subgroups, such as female; SLEDAI score ≥ 15 group; and those with neuropsychiatric, renal, and hematological involvements, and low serum C3. In addition, CYC could eliminate the differences in mortality between organ involvement and non-involvement, including renal, neuropsychiatric, cardiopulmonary, gastrointestinal, and hematological involvement, but not for mucocutaneous and musculoskeletal involvement.

CONCLUSION

Low dosage use of CYC decreased the risk of overall mortality of SLE. CYC might improve the survival of SLE patients with renal, neuropsychiatric, cardiopulmonary, gastrointestinal, and hematological involvements. Key Points • Cyclophosphamide decreases overall mortality of SLE patients. • Decreased mortality is mainly observed from low dosage use of cyclophosphamide. • Cyclophosphamide improves the survival of SLE patients when major systems such as renal, neuropsychiatric, cardiopulmonary, gastrointestinal, and hematological are involved.

The Role of Mutant p63 in Female Fertility

The transcription factor p63, one of the p53 family members, plays an essential role in regulating maternal reproduction and genomic integrity as well as epidermal development. TP63 (human)/Trp63 (mouse) produces multiple isoforms: TAp63 and ΔNp63, which possess a different N-terminus depending on two different promoters, and p63a, p63b, p63g, p63δ, and p63ε as products of alternative splicing at the C-terminus. TAp63 expression turns on in the nuclei of primordial germ cells in females and is maintained mainly in the oocyte nuclei of immature follicles. It has been established that TAp63 is the genomic guardian in oocytes of the female ovaries and plays a central role in determining the oocyte fate upon oocyte damage. Lately, there is increasing evidence that TP63 mutations are connected with female infertility, including isolated premature ovarian insufficiency (POI) and syndromic POI. Here, we review the biological functions of p63 in females and discuss the consequences of p63 mutations, which result in infertility in human patients.

Determination of O6-Methylguanine in dried blood spot of breast cancer patients after cyclophosphamide administration

Cyclophosphamide is a nitrogen mustard class of drugs that are often used in cancer chemotherapy. However, the use of Cyclophosphamide in high doses over a long period has been shown to increase the risk of developing secondary cancer. This can be indicated by the formation of mutagenic DNA adducts, such as O⁶-Methylguanine. Therefore, this adduct can be used as a biomarker for secondary cancer in patients receiving Cyclophosphamide. Bio sampling was carried out by using the Dried Blood Spot (DBS) method, followed by DNA extraction by using QIAamp DNA mini kit, and acid hydrolysis to obtain O⁶-Methylguanine. Analysis of O⁶-Methylguanine was performed by using the UPLC-MS/MS instrument with the conditions developed by Vianney, Harahap, & Suryadi (2021). Partial validation was carried out before the analysis. The results obtained from the calibration curve, accuracy, and precision validation test met the FDA requirements. The analysis method was then implemented in 16 breast cancer patients who received the Cyclophosphamide regimen. The O⁶-Methylguanine was successfully detected and quantified in all of the samples in the range of 0.55–6.66 ng/mL. It shows that the O⁶-Methylguanine accumulation in cancer patients receiving Cyclophosphamide is very likely to occur and the analysis method proposed by Vianney, Harahap, & Suryadi (2021) is potential to be used for Therapeutic Drug Monitoring in this group of patients.

TRDMT1 participates in the DNA damage repair of granulosa cells in premature ovarian failure

The molecular mechanisms underlying premature ovarian failure, which seriously impacts the physical and psychological health of patients, are not fully understood. Here, we present the role of TRDMT1 in reactive oxygen species-induced granulosa cells death, which is considered an important cause of premature ovarian failure. We found that reactive oxygen species were increased in a H2O2 dose-dependent manner and accompanied by the nuclear shuttling of TRDMT1, increased DNA damage and increased apoptosis of granulosa cells. In addition, reactive oxygen species-induced granulosa cells apoptosis could be prevented by the antioxidant N-acetylcysteine or overexpression of TRDMT1. Furthermore, DNA repair following reactive oxygen species induction was severely impaired/enhanced in TRDMT1 mutants, which exhibited reduced/increased RNA m5C methylation activity. Altogether, our results reveal a novel role of TRDMT1 in the regulation of premature ovarian failure through the repair of reactive oxygen species-triggered DNA damage in granulosa cells and provide an improved understanding of the mechanisms underlying granulosa cells apoptosis, which could potentially be useful for future clinical treatments of premature ovarian failure.

Morroniside suppresses hydrogen peroxide-stimulated autophagy and apoptosis in rat ovarian granulosa cells through the PI3K/AKT/mTOR pathway

Previous evidences have indicated that granulosa cells play a critical role in follicular growth. Hydrogen peroxide (H2O2)-induced oxidative stress has been associated with ovarian granulosa cell apoptosis and ovarian function. Recently, a study highlighted the protective role of morroniside against H2O2-induced damage. In this study, we aimed to investigate the effects of morroniside on H2O2-stimulated rat ovarian granulosa cells and its underlying molecular mechanisms. Our results showed that H2O2 treatment suppressed cell survival and increased apoptosis in rat granulosa cells, while treatment with morroniside markedly increased H2O2-induced granulosa cell survival in a dose-dependent manner (0, 10, 50 and 100 µM). Moreover, treatment with 50 µM morroniside impeded H2O2-induced cell apoptosis. An elevation in intracellular ROS, MDA, SOD, GSH-Px, and CAT level was observed in H2O2-induced granulosa cells; however, this effect was abrogated by morroniside treatment. Further studies suggested that administration of morroniside inhibited H2O2-induced granulosa cell apoptosis and caspase-3 activity. In addition, after morroniside treatment of H2O2-stimulated granulosa cells, autophagy-related protein (LC3-II/LC3-I ratio) and beclin-1 expression was decreased and p62 level was increased. Interestingly, we found that morroniside treatment activated the PI3K/AKT/mTOR pathway in H2O2-stimulated granulosa cells. Finally, we showed that treatment with PI3K and mTOR inhibitors reversed the protective effects of morroniside on H2O2-induced granulosa cells. Taken together, our data suggest that treatment with morroniside decreased apoptosis, autophagy, and oxidative stress in rat granulosa cells through the PI3K/AKT/mTOR pathway.

The cytotoxicity and genotoxicity of single and combined fenthion and terbufos treatments in human liver cells and zebrafish embryos

The mechanism of genotoxicity of the individual and combined pesticides of terbufos and fenthion were evaluated using HepG2 cells and zebrafish embryos. We determined genotoxicity by neutral comet assay and phosphorylation of H₂AX (γH₂AX), which indicated that cells treated with terbufos and/or fenthion caused DNA double-strand breaks (DSBs). The combination of these pesticides at the equimolar concentration (40 μM) exhibited less toxicity, genotoxicity, and did not impact DNA homologous recombination (HR) repair activity compare to terbufos or fenthion alone treatment. In HepG2 cells, terbufos, fenthion and their combination decreased only Xrcc2 expression (one of DNA HR repair genes). Moreover, the combined pesticides decreased Xrcc6 expression (one of DNA non-homologous end joining (NHEJ) repair genes). In addition, only terbufos or fenthion decreased XRCC2 protein expression, while Ku70 was impacted in all of the treated cells irrespective of up or down regulation. In zebrafish embryos, only fenthion impaired HR genes (Rad51 and Rad18) expression at 24 h. After 48 h exposure to pesticides, the combined pesticides elevated HR genes (Rad51 and Xrcc2) expression while terbufos or fenthion inhibited the expression of these four genes (Rad51, Rad18, Xrcc2, Xrcc6). In addition, the hatching rate of zebrafish embryos with fenthion or the combined pesticide at 72 hpf was significantly impaired. Collectively, terbufos and/or fenthion in combining caused DSBs in HepG2 cells and zebrafish embryos. Moreover, the specific mechanism of combined pesticide both HepG2 and zebrafish embryos revealed antagonism interaction.

Human umbilical cord mesenchymal stem cells improve morphometric and histopathologic changes of cyclophosphamide-injured ovarian follicles in mouse model of premature ovarian failure

BACKGROUND

Mesenchymal stem cells have restorative effects on premature ovarian failure (POF). The aim of this study was to investigate the effects of human umbilical cord vein MSCs (hUCV-MSCs) on follicular quantitative parameters and histological changes of ovaries in the cyclophosphamide (CTX)-induced POF in mice.

MATERIALS AND METHODS

C57BL/6 mice were divided into three groups (10 mice in each group). In the control group, phosphate-buffered saline (PBS) was injected via tail vein following 15 days injection of PBS intraperitoneally (IP). In the CTX group, CTX was administered IP for 15 days and then PBS was injected via tail vein. In the CTX + hUCV-MSCs group, following CTX administration, single dose of the 1 × 10⁶ of hUCV-MSCs were injected into tail vein. H&E, trichrome and PAS staining as well as TUNEL assay were performed on the ovaries tissue sections. The number of follicles, follicular quantitative parameters and apoptotic index were obtained. The serum levels of estradiol and FSH were measured in the mice.

RESULTS

In the CTX + hUCV-MSCs group, degenerative changes were decreased and follicular quantitative parameters increased in the ovarian follicles compared to the CTX group. In this group number of follicles was increased, apoptotic index was decreased, estradiol and FSH levels were decreased and increased, respectively, all of them improved compared to the CTX group. The mean percentage areas of collagen fibers content were decreased compared to the CTX group.

CONCLUSION

Results showed that, hUCV-MSCs administration increases follicular quantitative parameters and improve degenerative changes in the follicles following CTX injury.

After cyclophosphamide exposure, granulosa cells recover their anti-müllerian hormone-producing ability but not their numbers

Anti‐müllerian hormone (AMH) produced by granulosa cells (GCs), reserves the ovarian follicle pool for future recruitment and ovulation. However, women who have undergone cyclophosphamide (Cy) treatment have decreased AMH levels due to damaged GCs. This study establishes flow cytometry protocols for identification of GCs and investigates the cause of the Cy‐induced AMH decrease by analyzing the number of GCs and their AMH production at the single cell level. Over 2 weeks, C57BL/6 mice were intraperitoneally injected 6 times with 100 mg/kg Cy and sacrificed either immediately or 4 weeks after Cy treatment. Twenty‐four hours post‐Cy exposure, a decrease in serum AMH levels was seen due to a reduction in the number of follicle‐stimulating hormone receptor (FSHR)⁺AMH⁺ GCs and their ability to produce AMH. However, 4 weeks after Cy treatment, serum AMH levels were still decreased due to the decreased number of FSHR⁺AMH⁺ GCs, however, their AMH‐producing ability was unaltered. Consistently, in vitro, Cy‐induced low AMH production in FSHR⁺AMH⁺ hGL5 cells (immortalized human GCs) was restored 24 h after Cy treatment, although their numbers remained decreased. Thus, the surviving GCs after Cy exposure had intact AMH‐producing ability. In future, an effort to minimize GC death by Cy treatment is required, while maintaining its therapeutic effects.

MDR-1 function protects oocyte mitochondria against the transgenerational effects of nitrogen mustard exposure

Oocytes are vulnerable to alkylating agents like nitrogen mustard (NM), which can cause mitochondrial dysfunction associated with increased oxidative stress. Because mitochondria are maternally inherited, NM exposure affects oocyte mitochondrial physiology and compromises future progeny. Multidrug resistance transporters (MDRs) are transmembrane proteins that efflux such cytotoxic substances; MDR-1 is expressed in oocyte plasma and mitochondrial membranes and protects against oxidative stress. Our objective was to investigate how loss of MDR-1 can modulate oocyte response to NM transgenerationally. Wild Type (WT) and Mdr1a mutant female mice were injected intraperitoneally with sterile saline (control) or 0.1 mg/kg NM. 48 h post-injection, females were either sacrificed for F0 studies or mated with control males to yield F1 pups. After weaning, F1 females were sacrificed or mated to yield F2 pups. Germinal vesicle oocytes were assessed for mitochondrial membrane potential and reactive oxygen species (ROS) levels. NM exposed oocytes of both genotypes exhibited significantly higher ROS than controls in F0 and F1. NM F2 oocytes of neither genotype exhibited significantly higher ROS, though variation in Mdr1a mutants led to an upward trend. NM oocytes of both genotypes exhibited significantly disrupted mitochondrial membrane potential in F0. WT regained normalcy by F1 whereas Mdr1a mutants were unable to by F2. Our data suggest that Mdr1a mutants exhibit transgenerational mitochondrial dysfunction following toxic challenge that persists, implying that MDR-1 protects against toxicant-induced mitochondrial stress. Women without functional MDR-1 exposed to environmental toxicants could therefore be at risk for passing on compromised mitochondria to future offspring.

Synthesis of cyclophosphamide metabolites by a peroxygenase from Marasmius rotula for toxicological studies on human cancer cells

Cyclophosphamide (CPA) represents a widely used anti-cancer prodrug that is converted by liver cytochrome P450 (CYP) enzymes into the primary metabolite 4-hydroxycyclophosphamide (4-OH-CPA), followed by non-enzymatic generation of the bioactive metabolites phosphoramide mustard and acrolein. The use of human drug metabolites as authentic standards to evaluate their toxicity is essential for drug development. However, the chemical synthesis of 4-OH-CPA is complex and leads to only low yields and undesired side products. In past years, fungal unspecific peroxygenases (UPOs) have raised to powerful biocatalysts. They can exert the identical selective oxyfunctionalization of organic compounds and drugs as known for CYP enzymes with hydrogen peroxide being used as sole cosubstrate. Herein, we report the efficient enzymatic hydroxylation of CPA using the unspecific peroxygenase from Marasmius rotula (MroUPO) in a simple reaction design. Depending on the conditions used the primary liver metabolite 4-OH-CPA, its tautomer aldophosphamide (APA) and the overoxidized product 4-ketocyclophosphamide (4-keto-CPA) could be obtained. Using a kinetically controlled approach 4-OH-CPA was isolated with a yield of 32% (purity > 97.6%). Two human cancer cell lines (HepG2 and MCF-7) were treated with purified 4-OH-CPA produced by MroUPO (4-OH-CPA^UPO). 4-OH-CPA^UPO–induced cytotoxicity as measured by a luminescent cell viability assay and its genotoxicity as measured by γH2AX foci formation was not significantly different to the commercially available standard. The high yield of 4-OH-CPA^UPO and its biological activity demonstrate that UPOs can be efficiently used to produce CYP-specific drug metabolites for pharmacological assessment.

Ataxia-telangiectasia mutated coordinates the ovarian DNA repair and atresia-initiating response to phosphoramide mustard

Ataxia-telangiectasia-mutated (ATM) protein recognizes and repairs DNA double strand breaks through activation of cell cycle checkpoints and DNA repair proteins. Atm gene mutations increase female reproductive cancer risk. Phosphoramide mustard (PM) induces ovarian DNA damage and destroys primordial follicles, and pharmacological ATM inhibition prevents PM-induced follicular depletion. Wild-type (WT) C57BL/6 or Atm+/- mice were dosed once intraperitoneally with sesame oil (95%) or PM (25 mg/kg) in the proestrus phase of the estrous cycle and ovaries harvested 3 days thereafter. Atm+/- mice spent ~25% more time in diestrus phase than WT. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) on ovarian protein was performed and bioinformatically analyzed. Relative to WT, Atm+/- mice had 64 and 243 proteins increased or decreased in abundance, respectively. In WT mice, PM increased 162 and decreased 20 proteins. In Atm+/- mice, 173 and 37 proteins were increased and decreased, respectively, by PM. Exportin-2 (XPO2) was localized to granulosa cells of all follicle stages and was 7.2-fold greater in Atm+/- than WT mice. Cytoplasmic FMR1-interacting protein 1 was 6.8-fold lower in Atm+/- mice and was located in the surface epithelium with apparent translocation to the ovarian medulla post-PM exposure. PM induced γH2AX, but fewer γH2AX-positive foci were identified in Atm+/- ovaries. Similarly, cleaved caspase-3 was lower in the Atm+/- PM-treated, relative to WT mice. These findings support ATM involvement in ovarian DNA repair and suggest that ATM functions to regulate ovarian atresia.

BRCA1 Promoter Methylation Status in 1031 Primary Breast Cancers Predicts Favorable Outcomes Following Chemotherapy

Background

Breast Cancer 1 gene (BRCA1) is known to be inactivated in breast tumors by promoter methylation. Tumor cells in patients carrying a germline mutation in BRCA1 are sensitive to cytotoxic drugs that cause DNA double strand breaks. However, very little is known on whether patients with BRCA1 promoter methylated tumors are similarly sensitive to cytotoxic drugs. In this study, we address this by making use of extensive follow-up data on patients treated with cyclophosphamide, methotrexate, and fluorouracil in Iceland between 1976 and 2007.

Methods

We analyzed BRCA1 promoter methylation by pyrosequencing DNA from tumor samples from 1031 patients with primary breast cancer. Of those, 965 were sporadic cases, 61 were BRCA2, and five were BRCA1 germline mutation carriers. All cases were examined with respect to clinicopathological parameters and breast cancer–specific survival in patients treated with cytotoxic drugs. Information on chemotherapy treatment in noncarriers was available for 26 BRCA1 methylated tumors and 857 unmethylated tumors.

Results

BRCA1 was promoter methylated in 29 sporadic tumors or in 3.0% of cases (29 of 965), whereas none of the tumors derived from BRCA germline mutation carriers were promoter methylated. Important to note, patients with BRCA1 promoter methylation receiving chemotherapeutic drug treatment show highly improved breast cancer–specific survival compared with unmethylated controls (hazard ratio = 0.10, 95% confidence interval = 0.01 to 0.75, two-sided P = .02).

Conclusions

BRCA1 promoter methylation is predictive of improved disease outcome in patients receiving cyclophosphamide, methotrexate, and fluorouracil drug treatment. Our results support the use of markers indicative of “BRCAness” in sporadic breast cancers to identify patients that are likely to benefit from the use of DNA-damaging agents.

Introduction of the α-ketoamide structure: en route to develop hydrogen peroxide responsive prodrugs

New light on H₂O₂-activated prodrugs: the first α-ketoamide based prodrug opens up new alternatives for designing non-boron based H₂O₂-responsive promoieties.

Leveraging the elevated levels of hydrogen peroxide (H₂O₂) in cancer, inflammatory diseases and cardiovascular disorders, H₂O₂-activated promoieties have been widely used in drugs and biomaterials design. However, the overwhelming majority of the promoieties only share the common structure of a H₂O₂-responsive arylboronic acid/ester moiety with low diversity. We report here an unprecedented strategy to construct novel H₂O₂-responsive prodrugs based on an α-ketoamide structure. As a proof of concept, we designed and synthesized a panel of α-ketoamide based nitrogen mustard prodrugs, among which KAM-2 showed potent growth inhibitory activity and high selectivity toward cancer cells. The H₂O₂-trigged decomposition of KAM-2 was validated, and the DNA damaging and apoptosis promoting activity attributed to the released nitrogen mustard were demonstrated. Our work unveils α-ketoamide as a new scaffold for prodrug design and may quickly inspire future developments.

Inhibitors of apoptosis protect the ovarian reserve from cyclophosphamide

Cancer therapy can cause off-target effects including ovarian damage, which may result in primary ovarian insufficiency in girls and premenopausal women. Loss of ovarian follicles within the ovarian reserve leads to ovarian endocrine dysfunction and impaired fertility. Cyclophosphamide (CPA), a commonly used chemotherapeutic and immunosuppressant agent, is a gonadotoxic agent that destroys ovarian cells by crosslinking DNA. To protect the ovary against CPA damage, we sought to precisely map the mechanism by which the ovarian reserve is depleted by CPA. We found that CPA specifically depletes primordial follicles without affecting primary and secondary follicles in three independent murine strains (CD-1, C57BL/6J and BALB/cJ) in vivo. We directly tested the effect of the active metabolite of CPA, 1 μM 4-hydroxyperoxycyclophophamide (4-HC), in vitro and confirmed the loss of primordial oocytes but no change in the number of primary and secondary follicles. We demonstrated that phospho-AKT (p-AKT) and cleaved PARP (cPARP) are present in primordial oocytes 3 days after CPA injection, consistent with the role of these markers as part of the apoptotic cascade. Interestingly, p-AKT positive primordial oocytes co-expressed cPARP. Treatment of animals with specific inhibitors of apoptotic pathway components, ETP46464 and CHK2, blocked 4-HC‒induced DNA damage in vitro. These data suggest that CPA targets primordial germ cells in the ovarian reserve by stimulating apoptosis pathways. Adjuvant therapies to protect primordial germ cells from the off-target effects of CPA may reduce the risk of POI.

Nitrogen mustard exposure perturbs oocyte mitochondrial physiology and alters reproductive outcomes

Nitrogen mustard (NM) is an alkylating chemical warfare agent, and its derivatives are used in chemotherapy. Alkylating agents can cause mitochondrial damage, so exposed females may transmit damaged genomes to their children, since mitochondria are maternally inherited and oocytes are not thought to undergo mitophagy (Boudoures et al. [1]). The objective of this study is to investigate NM's effects on oocyte mitochondria to understand risks facing female soldiers, cancer patients, and their children. Mice were injected intraperitoneally with NM, monitored for reproductive outcomes, and ovaries and oocytes were isolated for analysis. Escalating doses of NM increased oxidative stress in parental and F1 generation oocytes, suggesting that mitochondrial damage by NM is enhanced by mitochondrial superoxide. NM-treated ovaries in vitro exhibited smaller mitochondrial volume, more electron-dense and multivesicular structures, and lower birth weight litters. These results demonstrate that females must be protected from alkylating agents for their health, and the health of their offspring.

Obesity alters phosphoramide mustard-induced ovarian DNA repair in mice

Phosphoramide mustard (PM) destroys rapidly dividing cells and activates the DNA double strand break marker, γH2AX, and DNA repair in rat granulosa cells and neonatal ovaries. The effects of PM exposure on DNA damage and activation of DNA damage repair in lean and obese female mice were investigated. Wild type (lean) non agouti (a/a) and KK.Cg-Ay/J heterozygote (obese) mice received sesame oil or PM (95%; 25 mg/kg; intraperitoneal injection). Obesity increased (P < 0.05) hepatic and spleen but decreased (P < 0.05) uterine weight. PM exposure reduced (P < 0.05) spleen weight regardless of body composition, however, decreased (P < 0.05) ovarian and hepatic weight were observed in the obese PM-exposed females. PM decreased (P < 0.05) primordial and primary follicle number in lean females. Obesity and PM increased (P < 0.05) γH2AX protein. DNA damage repair genes Prkdc, Parp1, and Rad51 mRNA were unaltered by obesity, however, Atm and Xrcc6 mRNA were increased (P < 0.05) while Brca1 was reduced (P < 0.05). Obesity reduced (P < 0.05) PRKDC, XRCC6 and but increased (P < 0.05) ATM protein. ATM, BRCA1 and RAD51 protein levels were increased (P < 0.05) by PM exposure in both lean and obese mice, while PM-induced increased (P < 0.05) XRCC6 and PARP1 were observed only in lean mice. Thus, PM induces ovarian DNA damage in vivo; obesity alters DNA repair response gene mRNA and protein level; the ovary activates DNA repair proteins in response to PM; but obesity compromises the ovarian PM response.

Silica nanoparticle exposure inducing granulosa cell apoptosis and follicular atresia in female Balb/c mice

Given that the effects of ultrafine fractions (< 0.1 μm) on reproductive diseases are gaining attention, this study aimed to explore the influence of silica nanoparticle (SiNP)-induced female reproductive dysfunction. In this study, 80 female mice were randomly divided into four groups including a control group and three concentrations of SiNP groups (7, 21, 35 mg/kg). Mice were exposed to the vehicle control and silica nanoparticles by tracheal perfusion every 3 days a total of five times in 15 days. Then, half of the mice in each group were sacrificed on 15 and 30 days after the first dose, respectively. Our findings indicated that SiNPs can result in ovarian damage, cause an imbalance of sex hormones, increase the number of atretic and primary follicles, and induce oxidative stress and DNA strand breaks in ovary by day 15. The protein expressions of ATM, CHK-2, P53, E2F1, P73, BAX, Caspase-9, and Caspase-3 were significantly increased, while expressions of RAD51 were down-regulated after SiNP exposure by days 15. Estradiol increased, while progesterone increased in low dose and decreased in high dose after SiNP exposure by 15 days. However, these changes were recovered by 30 days. The results suggest that SiNPs can cause reversible damage to follicles in mice. SiNPs could primarily cause DNA damage and DNA damage response through oxidative stress, while DNA damage repair failure because of severe DNA damage activated the mitochondrial apoptosis pathway and therefore resulted in apoptosis of granulosa cell. In addition, the disorder of reproductive endocrine function caused by SiNPs could be another reason for SiNP-induced reproductive dysfunction in mice. These events in turn induce the follicles to undergo atresia.

The Natural Carotenoid Crocetin and the Synthetic Tellurium Compound AS101 Protect the Ovary against Cyclophosphamide by Modulating SIRT1 and Mitochondrial Markers

Cancer therapies are associated with increased infertility risk due to accelerated reproductive aging. Oxidative stress (OS) is a potential mechanism behind ovarian toxicity by cyclophosphamide (CPM), the most ovotoxic anticancer drug. An important sensor of OS is SIRT1, a NAD⁺-dependent deacetylase which regulates cellular defence and cell fate. This study investigated whether the natural carotenoid crocetin and the synthetic compound AS101 protect the ovary against CPM by modulating SIRT1 and mitochondrial markers. We found that the number of primordial follicles of female CD1 mice receiving crocetin plus CPM increased when compared with CPM alone and similar to AS101, whose protective effects are known. SIRT1 increased in CPM mouse ovaries revealing the occurrence of OS. Similarly, mitochondrial SIRT3 rose, whilst SOD2 and the mitochondrial biogenesis activator PGC1-α decreased, suggesting the occurrence of mitochondrial damage. Crocetin and AS101 administration prevented SIRT1 burst suggesting that preservation of redox balance can help the ovary to counteract ovarian damage by CPM. Decreased SIRT3 and increased SOD2 and PGC1-α in mice receiving crocetin or AS101 prior to CPM provide evidence for mitochondrial protection. Present results improve the knowledge of ovarian damage by CPM and may help to develop interventions for preserving fertility in cancer patients.

Phosphoramide mustard induces autophagy markers and mTOR inhibition prevents follicle loss due to phosphoramide mustard exposure

Phosphoramide mustard (PM) is an ovotoxic metabolite of cyclophosphamide. Postnatal day 4 Fisher 344 rat ovaries were exposed to vehicle control (1% DMSO) or PM (60μM)±LY294002 or rapamycin for 2 or 4 d. Transmission election microscopy revealed abnormally large golgi apparatus and electron dense mitochondria in PM-exposed ovaries prior to and at the time of follicle depletion. PM exposure increased (P<0.05) mRNA abundance of Bbc3, Cdkn1a, Ctfr, Edn1, Gstp1, Nqo1, Tlr4, Tnfrsfla, Txnrd1 and decreased (P<0.05) Casp1 and Il1b after 4d. PM exposure increased (P<0.1) BECN1 and LAMP, decreased (P<0.1) ABCB1 and did not alter ABCC1 protein. LY294002 did not impact PM-induced ovotoxicity, but decreased ABCC1 and ABCB1 protein. Rapamycin prevented PM-induced follicle loss. These data suggest that the mammalian target of rapamycin, mTOR, may be a gatekeeper of PM-induced follicle loss.

The ovarian DNA damage repair response is induced prior to phosphoramide mustard-induced follicle depletion, and ataxia telangiectasia mutated inhibition prevents PM-induced follicle depletion

Phosphoramide mustard (PM) is an ovotoxic metabolite of cyclophosphamide and destroys primordial and primary follicles potentially by DNA damage induction. The temporal pattern by which PM induces DNA damage and initiation of the ovarian response to DNA damage has not yet been well characterized. This study investigated DNA damage initiation, the DNA repair response, as well as induction of follicular demise using a neonatal rat ovarian culture system. Additionally, to delineate specific mechanisms involved in the ovarian response to PM exposure, utility was made of PKC delta (PKCδ) deficient mice as well as an ATM inhibitor (KU 55933; AI). Fisher 344 PND4 rat ovaries were cultured for 12, 24, 48 or 96h in medium containing DMSO ±60μM PM or KU 55933 (48h; 10nM). PM-induced activation of DNA damage repair genes was observed as early as 12h post-exposure. ATM, PARP1, E2F7, P73 and CASP3 abundance were increased but RAD51 and BCL2 protein decreased after 96h of PM exposure. PKCδ deficiency reduced numbers of all follicular stages, but did not have an additive impact on PM-induced ovotoxicity. ATM inhibition protected all follicle stages from PM-induced depletion. In conclusion, the ovarian DNA damage repair response is active post-PM exposure, supporting that DNA damage contributes to PM-induced ovotoxicity.

Characterization of nitrogen mustard formamidopyrimidine adduct formation of bis(2-chloroethyl)ethylamine with calf thymus DNA and a human mammary cancer cell line

A robust, quantitative ultraperformance liquid chromatography ion trap multistage scanning mass spectrometric (UPLC/MS(3)) method was established to characterize and measure five guanine adducts formed by reaction of the chemotherapeutic nitrogen mustard (NM) bis(2-chloroethyl)ethylamine with calf thymus (CT) DNA. In addition to the known N7-guanine (NM-G) adduct and its cross-link (G-NM-G), the ring-opened formamidopyrimidine (FapyG) monoadduct (NM-FapyG) and cross-links in which one (FapyG-NM-G) or both (FapyG-NM-FapyG) guanines underwent ring-opening to FapyG units were identified. Authentic standards of all adducts were synthesized and characterized by NMR and mass spectrometry. These adducts were quantified in CT DNA treated with NM (1 μM) as their deglycosylated bases. A two-stage neutral thermal hydrolysis was developed to mitigate the artifactual formation of ring-opened FapyG adducts involving hydrolysis of the cationic adduct at 37 °C, followed by hydrolysis of the FapyG adducts at 95 °C. The limit of quantification values ranged between 0.3 and 1.6 adducts per 10(7) DNA bases when the equivalent of 5 μg of DNA hydrolysate was assayed on column. The principal adduct formed was the G-NM-G cross-link, followed by the NM-G monoadduct; the FapyG-NM-G cross-link adduct; and the FapyG-NM-FapyG was below the limit of detection. The NM-FapyG adducts were formed in CT DNA at a level ∼20% that of the NM-G adduct. NM-FapyG has not been previously quanitified, and the FapyG-NM-G and FapyG-NM-FapyG adducts have not been previously characterized. Our validated analytical method was then applied to measure DNA adduct formation in the MDA-MB-231 mammary tumor cell line exposed to NM (100 μM) for 24 h. The major adduct formed was NM-G (970 adducts per 10(7) bases), followed by G-NM-G (240 adducts per 10(7) bases), NM-FapyG (180 adducts per 10(7) bases), and, last, the FapyG-NM-G cross-link adduct (6.0 adducts per 10(7) bases). These lesions are expected to contribute to NM-mediated toxicity and genotoxicity in vivo.