Kinase-independent inhibition of cyclophosphamide-induced pathways protects the ovarian reserve and prolongs fertility

The role of declining ataxia-telangiectasia-mutated (ATM) function in oocyte aging

Despite the advances in the understanding of reproductive physiology, the mechanisms underlying ovarian aging are still not deciphered. Recent research found an association between impaired ATM-mediated DNA double-strand break (DSB) repair mechanisms and oocyte aging. However, direct evidence connecting ATM-mediated pathway function decline and impaired oocyte quality is lacking. The objective of this study was to determine the role of ATM-mediated DNA DSB repair in the maintenance of oocyte quality in a mouse oocyte knockdown model. Gene interference, in vitro culture, parthenogenesis coupled with genotoxicity assay approaches, as well as molecular cytogenetic analyses based upon next-generation sequencing, were used to test the hypothesis that intact ATM function is critical in the maintenance of oocyte quality. We found that ATM knockdown impaired oocyte quality, resulting in poor embryo development. ATM knockdown significantly lowered or blocked the progression of meiosis in vitro, as well as retarding and reducing embryo cleavage after parthenogenesis. After ATM knockdown, all embryos were of poor quality, and none reached the blastocyst stage. ATM knockdown was also associated with an increased aneuploidy rate compared to controls. Finally, ATM knockdown increased the sensitivity of the oocytes to a genotoxic active metabolite of cyclophosphamide, with increased formation of DNA DSBs, reduced survival, and earlier apoptotic death compared to controls. These findings suggest a key role for ATM in maintaining oocyte quality and resistance to genotoxic stress, and that the previously observed age-induced decline in oocyte ATM function may be a prime factor contributing to oocyte aging.

Gynotoxic Effects of Chemotherapy and Potential Protective Mechanisms

Chemotherapy is one of the leading cancer treatments. Unfortunately, its use can contribute to several side effects, including gynotoxic effects in women. Ovarian reserve suppression and estrogen deficiency result in reduced quality of life for cancer patients and are frequently the cause of infertility and early menopause. Classic alkylating cytostatics are among the most toxic chemotherapeutics in this regard. They cause DNA damage in ovarian follicles and the cells they contain, and they can also induce oxidative stress or affect numerous signaling pathways. In vitro tests, animal models, and a few studies among women have investigated the effects of various agents on the protection of the ovarian reserve during classic chemotherapy. In this review article, we focused on the possible beneficial effects of selected hormones (anti-Müllerian hormone, ghrelin, luteinizing hormone, melatonin), agents affecting the activity of apoptotic pathways and modulating gene expression (C1P, S1P, microRNA), and several natural (quercetin, rapamycin, resveratrol) and synthetic compounds (bortezomib, dexrazoxane, goserelin, gonadoliberin analogs, imatinib, metformin, tamoxifen) in preventing gynotoxic effects induced by commonly used cytostatics. The presented line of research appears to provide a promising strategy for protecting and/or improving the ovarian reserve in the studied group of cancer patients. However, well-designed clinical trials are needed to unequivocally assess the effects of these agents on improving hormonal function and fertility in women treated with ovotoxic anticancer drugs.

Rapamycin prevents cyclophosphamide-induced ovarian follicular loss and potentially inhibits tumour proliferation in a breast cancer xenograft mouse model

STUDY QUESTION

To what extent and via what mechanism does the concomitant administration of rapamycin (a follicle activation pathway inhibitor and antitumour agent) and cyclophosphamide (a highly toxic ovarian anticancer agent) prevent cyclophosphamide-induced ovarian reserve loss and inhibit tumour proliferation in a breast cancer xenograft mouse model?

SUMMARY ANSWER

Daily concomitant administration of rapamycin and a cyclic regimen of cyclophosphamide, which has sufficient antitumour effects as a single agent, suppressed cyclophosphamide-induced primordial follicle loss by inhibiting primordial follicle activation in a breast cancer xenograft mouse model, suggesting the potential of an additive inhibitory effect against tumour proliferation.

WHAT IS KNOWN ALREADY

Cyclophosphamide stimulates primordial follicles by activating the mammalian target of the rapamycin (mTOR) pathway, resulting in the accumulation of primary follicles, most of which undergo apoptosis. Rapamycin, an mTOR inhibitor, regulates primordial follicle activation and exhibits potential inhibitory effects against breast cancer cell proliferation.

STUDY DESIGN, SIZE, DURATION

To assess ovarian follicular apoptosis, 3 weeks after administering breast cancer cells, 8-week-old mice were randomized into three treatment groups: control, cyclophosphamide, and cyclophosphamide + rapamycin (Cy + Rap) (n = 5 or 6 mice/group). Mice were treated with rapamycin or vehicle control for 1 week, followed by a single dose of cyclophosphamide or vehicle control. Subsequently, the ovaries were resected 24 h after cyclophosphamide administration (short-term treatment groups). To evaluate follicle abundance and the mTOR pathway in ovaries, as well as the antitumour effects and impact on the mTOR pathway in tumours, 8-week-old xenograft breast cancer transplanted mice were randomized into three treatment groups: vehicle control, Cy, and Cy + Rap (n = 6 or 7 mice/group). Rapamycin (5 mg/kg) or the vehicle was administered daily for 29 days. Cyclophosphamide (120 mg/kg) or the vehicle was administered thrice weekly (long-term treatment groups). The tumour diameter was measured weekly. Seven days after the last cyclophosphamide treatment, the ovaries were harvested, fixed, and sectioned (for follicle counting) or frozen (for further analysis). Similarly, the tumours were resected and fixed or frozen.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) was performed to examine ovarian follicular apoptosis in the short-term treatment groups. All subsequent experiments were conducted in the long-term treatment groups. Tumour growth was evaluated using the tumour volume index. The tumour volume index indicates the relative volume, compared to the volume 3 weeks after tumour cell injection (at treatment initiation) set to 100%. Tumour cell proliferation was evaluated by Ki-67 immunostaining. Activation of the mTOR pathway in tumours was assessed using the protein extracts from tumours and analysed by western blotting. Haematoxylin and eosin staining of ovaries was used to perform differential follicle counts for primordial, primary, secondary, antral, and atretic follicles. Activation of the mTOR pathway in ovaries was assessed using protein extracts from whole ovaries and analysed by western blotting. Localization of mTOR pathway activation within ovaries was assessed by performing anti-phospho-S6 kinase (downstream of mTOR pathway) immunohistochemistry.

MAIN RESULTS AND THE ROLE OF CHANCE

Ovaries of the short-term treatment groups were resected 24 h after cyclophosphamide administration and subjected to TUNEL staining of apoptotic cells. No TUNEL-positive primordial follicles were detected in the control, Cy, and Cy + Rap groups. Conversely, many granulosa cells of growing follicles were TUNEL positive in the Cy group but negative in the control and Cy + Rap groups. All subsequent experimental results were obtained from the long-term treatment groups. The tumour volume index stabilized at a mean of 160-200% in the Cy group and 130% in the Cy + Rap group throughout the treatment period. In contrast, tumours in the vehicle control group grew continuously with a mean tumour volume index of 600%, significantly greater than that of the two treatment groups. Based on the western blot analysis of tumours, the mTOR pathway was activated in the vehicle control group and downregulated in the Cy + Rap group when compared with the control and Cy groups. Ki-67 immunostaining of tumours showed significant inhibition of cell proliferation in the Cy + Rap group when compared with that in the control and Cy groups. The ovarian follicle count revealed that the Cy group had significantly fewer primordial follicles (P < 0.001) than the control group, whereas the Cy + Rap group had significantly higher number of primordial follicles (P < 0.001, 2.5 times) than the Cy group. The ratio of primary to primordial follicles was twice as high in the Cy group than in the control group; however, no significant difference was observed between the control group and the Cy + Rap group. Western blot analysis of ovaries revealed that the mTOR pathway was activated by cyclophosphamide and inhibited by rapamycin. The phospho-S6 kinase (pS6K)-positive primordial follicle rate was 2.7 times higher in the Cy group than in the control group. However, this effect was suppressed to a level similar to the control group in the Cy + Rap group.

LARGE SCALE DATA

None.

LIMITATIONS, REASONS FOR CAUTION

The combinatorial treatment of breast cancer tumours with rapamycin and cyclophosphamide elicited inhibitory effects on cell proliferative potential compared to cyclophosphamide monotherapy. However, no statistically significant additive effect was observed on tumour volume. Thus, the beneficial antitumour effect afforded by rapamycin administration on breast cancer could not be definitively proven. Although rapamycin has ovarian-protective effects, it does not fully counteract the ovarian toxicity of cyclophosphamide. Nevertheless, rapamycin is advantageous as an ovarian protective agent as it can be used in combination with other ovarian protective agents, such as hormonal therapy. Hence, in combination with other agents, mTOR inhibitors may be sufficiently ovario-protective against high-dose and cyclic cyclophosphamide regimens.

WIDER IMPLICATIONS OF THE FINDINGS

Compared with a cyclic cyclophosphamide regimen that replicates human clinical practice under breast cancer-bearing conditions, the combination with rapamycin mitigates the ovarian follicle loss of cyclophosphamide without interfering with the anticipated antitumour effects. Hence, rapamycin may represent a new non-invasive treatment option for cyclophosphamide-induced ovarian dysfunction in breast cancer patients.

STUDY FUNDING/COMPETING INTEREST(S)

This work was not financially supported. The authors declare that they have no conflict of interest.

Research progress on the prevention and treatment of chemotherapy-induced ovarian damage

Chemotherapy is a main treatment option for malignant tumors, but it may cause various adverse effects, including dysfunction of female endocrine system and fertility. Chemotherapy-induced ovarian damage has been concerned with ovarian preservation but also the prevention and treatment of ovarian dysfunction. In this article, the mechanisms of ovarian injury caused by chemotherapy, including apoptosis of the follicle and supporting cells, follicle "burn out", ovarian stromal and microvascular damage; and influencing factors, including age at diagnosis, initial low pre-treatment anti-Müllerian hormone levels, toxicity, dose and regimen of chemotherapy drugs are reviewed based on the latest research results and clinical practice. The article also discusses measures and frontier therapies for the prevention and treatment of ovarian injury, including the application of gonadotropin releasing hormone agonists or antagonists, tyrosine kinase inhibitors, antioxidants, sphingosine-1-phosphate, ceramide-1-phosphate, mammalian target of rapamycin inhibitors, granulocyte-colony stimulating factor, stem cell therapy and artificial ovaries.

Anti-Mullerian hormone attenuates both cyclophosphamide-induced damage and PI3K signalling activation, while rapamycin attenuates only PI3K signalling activation, in human ovarian cortex in vitro

STUDY QUESTION

What are the effects of cyclophosphamide exposure on the human ovary and can anti-Mullerian hormone (AMH) and rapamycin protect against these?

SUMMARY ANSWER

Exposure to cyclophosphamide compromises the health of primordial and transitional follicles in the human ovarian cortex and upregulates PI3K signalling, indicating both direct damage and increased follicular activation; AMH attenuates both of these chemotherapy-induced effects, while rapamycin attenuates only PI3K signalling upregulation.

WHAT IS KNOWN ALREADY

Studies primarily in rodents demonstrate that cyclophosphamide causes direct damage to primordial follicles or that the primordial follicle pool is depleted primarily through excessive initiation of follicle growth. This increased follicular activation is mediated via upregulated PI3K signalling and/or reduced local levels of AMH production due to lost growing follicles. Furthermore, while rodent data show promise regarding the potential benefits of inhibitors/protectants alongside chemotherapy treatment to preserve female fertility, there is no information about the potential for this in humans.

STUDY DESIGN, SIZE, DURATION

Fresh ovarian cortical biopsies were obtained from 17 healthy women aged 21-41 years (mean ± SD: 31.8 ± 4.9 years) at elective caesarean section. Biopsies were cut into small fragments and cultured for 24 h with either vehicle alone (DMSO), the active cyclophosphamide metabolite 4-hydroperoxycyclophosphamide (4-HC) alone, 4-HC + rapamycin or 4-HC+AMH. Two doses of 4-HC were investigated, 0.2 and 2 μM in separate experiments, using biopsies from seven women (aged 27-41) and six women (aged 21-34), respectively. Biopsies from four women (aged 28-38) were used to investigate the effect of rapamycin or AMH only.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Histological analysis of ovarian tissue was undertaken for follicle staging and health assessment. Western blotting and immunostaining were used to assess activation of PI3K signalling by measuring phosphorylation of AKT and phosphorylated FOXO3A staining intensity, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

Exposure to either dose of 4-HC caused an increase in the proportion of unhealthy primordial (P < 0.0001, both doses) and transitional follicles (P < 0.01 for low dose and P < 0.01 for high dose) compared to vehicle. AMH significantly reduced follicle damage by approximately half in both of the investigated doses of 4-HC (P < 0.0001), while rapamycin had no protective effect on the health of the follicles. Culture with AMH or rapamycin alone had no effect on follicle health. Activation of PI3K signalling following 4-HC exposure was demonstrated by both Western blotting data showing that 4-HC increased in AKT phosphorylation and immunostaining showing increased phosphorylated FOXO3A staining of non-growing oocytes. Treatment with rapamycin reduced the activation of PI3K signalling in experiments with low doses of 4-HC while culture with AMH reduced PI3K activation (both AKT phosphorylation and phosphorylated FOXO3A staining intensity) across both doses investigated.

LIMITATIONS, REASONS FOR CAUTION

These in vitro studies may not replicate in vivo exposures. Furthermore, longer experiment durations are needed to determine whether the effects observed translate into irreparable deficits of ovarian follicles.

WIDER IMPLICATIONS OF THE FINDINGS

These data provide a solid foundation on which to explore the efficacy of AMH in protecting non-growing ovarian follicles from gonadotoxic chemotherapies. Future work will require consideration of the sustained effects of chemotherapy treatment and potential protectants to ensure these agents do not impair the developmental competence of oocytes or lead to the survival of oocytes with accumulated DNA damage, which could have adverse consequences for potential offspring.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from TENOVUS Scotland, the Academy of Medical Sciences (to R.R.), the Medical Research Council (G1100357 to R.A.A., MR/N022556/1 to the MRC Centre for Reproductive Health), and Merck Serono UK (to R.A.A.). R.R., H.L.S., N.S., and E.E.T. declare no conflicts of interest. R.A.A. reports grants and personal fees from Roche Diagnostics and Ferring Pharmaceuticals, and personal fees from IBSA and Merck outside the submitted work.

TRIAL REGISTRATION NUMBER

N/A.

Brca2(p.T1942fs/+) dissipates ovarian reserve in rats through oxidative stress in follicular granulosa cells

Pathogenic variants of BRCA1/2 constitute hereditary breast and ovarian cancer (HBOC) syndrome, and BRCA1/2 mutant is a risk for various cancers. Whereas the clinical guideline for HBOC patients has been organized for the therapy and prevention of cancer, there is no recommendation on the female reproductive discipline. Indeed, the role of BRCA1/2 pathogenic variants in ovarian reserve has not been established due to the deficiency of appropriate animal models. Here, we used a rat model of Brca2(p.T1942fs/+) mutant of Sprague-Dawley strain with CRISPR-Cas9 editing to evaluate ovarian reserve in females. Fertility and ovarian follicles were evaluated and anti-Müllerian hormone (AMH) was measured at 8-32 weeks of age with a comparison between the wild-type and the mutant rats (MUT). MUT revealed a significantly smaller number of deliveries with fewer total pups. Furthermore, MUT showed a significant decrease in primordial follicles at 20 weeks and a low AMH level at 28 weeks. RNA-sequencing of the ovary at 10 weeks detected acceleration of the DNA damage repair pathway, which was accompanied by oxidative stress-induced DNA double-strand breaks, a decrease in PTEN, and an increase in mTOR in follicular granulosa cells. In conclusion, Brca2(p.T1942fs/+) dissipates primordial follicles via early activation of granulosa cells through oxidative stress, leading to earlier termination of fertility.

Protective Effect of Glutathione Administration on Ovarian Function in Female Rats with Cyclophosphamide-Induced Ovarian Damage

OBJECTIVES

We investigated the potential of glutathione to protect ovarian function in rats exposed to cyclophosphamide by measuring serum anti-Mullerian hormone (AMH) levels, follicle counts, and related parameters.

DESIGN

Forty-two adult female Sprague-Dawley rats were randomly divided into six groups and treated with various combinations of cyclophosphamide, glutathione, and sodium chloride. On day 21, the rats were anesthetized, and their ovaries were removed for examination.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Histopathological examination, serum AMH concentrations, follicle counts, AMH-positive staining of follicle percentages were analyzed. Statistical analysis was performed using a one-way analysis of variance and Tukey's test, with significance set at p < 0.05. Secondary measures encompassed histopathological examination and percentages of AMH-positive staining of follicles.

RESULTS

Significant differences were observed in follicle counts, AMH-positive follicle parameters, and serum AMH concentrations among the six groups. Group 2 (treated with cyclophosphamide) had the lowest primordial, primary, secondary, and antral follicle counts and the highest atretic count. Group 6, treated with cyclophosphamide and 200 mg/kg glutathione, showed improved follicle counts compared to those in group 2. Reducing the glutathione dose to 100 mg/kg was ineffective.

LIMITATIONS

This was an experimental animal investigation with a comparatively modest sample size. Experimental studies should be conducted to determine the optimal dosage and duration of glutathione therapy. Information gathered from an experimental animal model may not yield precisely similar outcomes in humans; therefore, additional investigations are necessary to examine the impact of glutathione on women experiencing POI.

CONCLUSIONS

The anti-oxidative protective effect of directly administered glutathione was demonstrated for the first time. Low-dose glutathione was ineffective, whereas a high dose yielded significant ovarian protection against cyclophosphamide. Our findings provide valuable insights for supplementing clinical trials on the protective effects of glutathione against ovarian damage.

Investigation of crocin's protective effect on cyclophosphamide-induced hypothalamic-pituitary-gonadal axis defects in adult female rats

Cyclophosphamide is a drug used in chemotherapy. However, it has side effects, including changes in reproductive system functioning. Some herbal compounds can reduce the harmful effects of cyclophosphamide. This study aims to investigate the protective role of crocin against changes caused by Cyclophosphamide in ovarian tissue through changes in the expression of genes involved in the hypothalamic-pituitary-gonadal axis. This experimental study was performed on 24 adult female Wistar rats. Mice were divided into four groups (normal saline, 30 mg/kg cyclophosphamide, 100 mg/kg crocin and 30 mg/kg cyclophosphamide, and 200 mg/kg crocin and 30 mg/kg cyclophosphamide). At the end of the treatment period, the hypothalamus and ovaries were also removed to evaluate ob-Rb, ob-Ra, and NPY genes expression using real-time PCR and histological changes in the ovaries. Data were analyzed by SPSS statistical software. The expression of genes, number of follicles, and follicle diameter significantly decreased in the cyclophosphamide-treated groups compared with the control group. In the crocin and cyclophosphamide-treated groups, drug-induced reproductive complications were mitigated. The current findings indicate that by increasing the expression of genes ob-Rb, ob-Ra, and NPY, crocin could modulate the harmful effects of cyclophosphamide.

The Dominant Mechanism of Cyclophosphamide-Induced Damage to Ovarian Reserve: Premature Activation or Apoptosis of Primordial Follicles?

Cyclophosphamide (CPM), a part of most cancer treatment regimens, has demonstrated high gonadal toxicity in females. Initially, CPM is believed to damage the ovarian reserve by premature activation of primordial follicles, for the fact that facing CPM damage, primordial oocytes show the activation of PTEN/PI3K/AKT pathways, accompanied by accelerated activation of follicle developmental waves. Meanwhile, primordial follicles are dormant and not considered the target of CPM. However, many researchers have found DNA DSBs and apoptosis within primordial oocytes under CPM-induced ovarian damage instead of premature accelerated activation. A stricter surveillance system of DNA damage is also thought to be in primordial oocytes. So far, the apoptotic death mechanism is considered well-proved, but the premature activation theory is controversial and unacceptable. The connection between the upregulation of PTEN/PI3K/AKT pathways and DNA DSBs and apoptosis within primordial oocytes is also unclear. This review aims to highlight the flaw and/or support of the disputed premature activation theory and the apoptosis mechanism to identify the underlying mechanism of CPM's injury on ovarian reserve, which is crucial to facilitate the discovery and development of effective ovarian protectants. Ultimately, this review finds no good evidence for follicle activation and strong consistent evidence for apoptosis.

A Journey to Reach the Ovary Using Next-Generation Technologies

Although effective in terms of the chances of future live birth, the current methods for fertility preservation, such as oocyte, embryo, or ovarian tissue cryopreservation, cannot be offered to all cancer patients in all clinical contexts. Expanding options for fertility preservation is crucial to addressing the need to encompass all situations. One emerging strategy is pharmacoprotection, a non-invasive approach that has the potential to fill existing gaps in fertility preservation. In addition to the identification of the most effective therapeutic agents, the potential for off-target effects remains one of the main limitations of this strategy for clinical application, particularly when healthy ovarian tissue is targeted. This review focuses on the advances in pharmacoprotective approaches and the challenge of targeting the ovaries to deliver these agents. The unique properties of gold nanoparticles (AuNPs) make them an attractive candidate for this purpose. We discuss how AuNPs meet many of the requirements for an ideal drug delivery system, as well as the existing limitations that have hindered the progression of AuNP research into more clinical trials. Additionally, the review highlights microRNA (miRNA) therapy as a next-generation approach to address the issues of fertility preservation and discusses the obstacles that currently impede its clinical availability.

Overactivation or Apoptosis: Which Mechanisms Affect Chemotherapy-Induced Ovarian Reserve Depletion?

Dormant primordial follicles (PMF), which constitute the ovarian reserve, are recruited continuously into the cohort of growing follicles in the ovary throughout female reproductive life. Gonadotoxic chemotherapy was shown to diminish the ovarian reserve pool, to destroy growing follicle population, and to cause premature ovarian insufficiency (POI). Three primary mechanisms have been proposed to account for this chemotherapy-induced PMF depletion: either indirectly via over-recruitment of PMF, by stromal damage, or through direct toxicity effects on PMF. Preventative pharmacological agents intervening in these ovotoxic mechanisms may be ideal candidates for fertility preservation (FP). This manuscript reviews the mechanisms that disrupt follicle dormancy causing depletion of the ovarian reserve. It describes the most widely studied experimental inhibitors that have been deployed in attempts to counteract these affects and prevent follicle depletion.

Alpha-lipoic acid supplementation reverses the declining quality of oocytes exposed to cyclophosphamide

Cyclophosphamide (CY) is a chemotherapeutic drug that is commonly used to treat malignancies of the ovary, breast, and hematology, as well as autoimmune disorders. As a cofactor of mitochondrial multienzyme complexes, alpha lipoic acid (ALA) is well known for its antioxidant characteristics, which operate directly on the scavenging of reactive oxygen species (ROS) and indirectly on the intracellular recycling of other antioxidants. However, the underlying mechanisms through which CY exerts its toxic effects on meiosis and oocyte quality, as well as a viable approach for protecting oocyte quality and preserving fertility, remain unknown. In present study, immunostaining and fluorescence intensity quantification were applied to assess the effects of CY and ALA supplementation on the key processes during the oocyte meiotic maturation. Our results show that supplementing oocytes with ALA, a well-known antioxidant and free radical scavenger, can reverse CY-induced oocyte meiotic maturation failure. Specifically, we found that CY exposure caused oocyte meiotic failure by disrupting meiotic organelle dynamics and arrangement, as well as a prominently impaired cytoskeleton assembly. In addition, CY caused an abnormal distribution of mitochondrion and cortical granules, two indicators of oocyte cytoplasmic maturation. More importantly, we show that ALA supplementation effectively reverses CY-induced meiotic failure and oocyte quality decline by suppressing oxidative stress-induced DNA damage and apoptosis in oocytes. Collectively, our data reveal that ALA supplementation is a feasible approach to protect oocytes from CY-exposed deterioration, providing a better understanding of the mechanisms involved in chemotherapy-induced meiotic failure.

CHEK2 signaling is the key regulator of oocyte survival after chemotherapy

Cancer treatments can damage the ovarian follicle reserve, leading to primary ovarian insufficiency and infertility among survivors. Checkpoint kinase 2 (CHEK2) deficiency prevents elimination of oocytes in primordial follicles in female mice exposed to radiation and preserves their ovarian function and fertility. Here, we demonstrate that CHEK2 also coordinates the elimination of oocytes after exposure to standard-of-care chemotherapy drugs. CHEK2 activates two downstream targets-TAp63 and p53-which direct oocyte elimination. CHEK2 knockout or pharmacological inhibition preserved ovarian follicle reserve after radiation and chemotherapy. However, the lack of specificity for CHEK2 among available inhibitors limits their potential for clinical development. These findings demonstrate that CHEK2 is a master regulator of the ovarian cellular response to damage caused by radiation and chemotherapy and warrant the development of selective inhibitors specific to CHEK2 as a potential avenue for ovario-protective treatments.

Inhibition of checkpoint kinase prevents human oocyte apoptosis induced by chemotherapy and allows enhanced tumour chemotherapeutic efficacy

STUDY QUESTION

Could inhibition of the checkpoint kinase (CHEK) pathway protect human oocytes and even enhance the anti-tumour effects, during chemotherapy?

SUMMARY ANSWER

CHEK inhibitors prevented apoptosis of human oocytes induced by chemotherapy and even enhanced the anti-tumour effects.

WHAT IS KNOWN ALREADY

CHEK inhibitors showed ovarian protective effects in mice during chemotherapy, while their role in human oocytes is unclear.

STUDY DESIGN, SIZE, DURATION

This experimental study evaluated the ovarian reserve of young patients (120 patients) with cancer, exposed or not exposed to taxane and platinum (TP)-combined chemotherapy. Single RNA-sequencing analysis of human primordial oocytes from 10 patients was performed to explore the mechanism of oocyte apoptosis induced by TP chemotherapy. The damaging effects of paclitaxel (PTX) and cisplatin on human oocytes were also evaluated by culturing human ovaries in vitro. A new mouse model that combines human ovarian xenotransplantation and patient-derived tumour xenografts was developed to explore adjuvant therapies for ovarian protection. The mice were randomly allocated to four groups (10 mice for each group): control, cisplatin, cisplatin + CK1 (CHEK1 inhibitor, SCH 900776), and cisplatin + CK2 (CHEK2 inhibitor, BML277).

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the prospective cohort study, human ovarian follicles were counted and serum AMH levels were evaluated. RNA-sequencing analysis was conducted, and staining for follicular damage (phosphorylated H2AX histone; γH2AX), terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) assays and assessments of apoptotic biomarkers (western blot and immunofluorescence) were conducted in human ovaries. After the treatments, histological analysis was performed on human ovarian samples to investigate follicular populations, and oocyte damage was measured by γH2AX staining, BAX staining, and TUNEL assays. At the same time, the tumours were evaluated for volume, weight, and apoptosis levels.

MAIN RESULTS AND THE ROLE OF CHANCE

Patients who received TP chemotherapy showed decreased ovarian reserves. Single RNA-sequencing analysis of human primordial oocytes indicated that TP chemotherapy induced apoptosis of human primordial oocytes by causing CHEK-mediated TAp63α phosphorylation. In vitro culture of human ovaries showed greater damaging effects on oocytes after cisplatin treatment compared with that after PTX treatment. Using the new animal model, CHEK1/2 inhibitors prevented the apoptosis of human oocytes induced by cisplatin and even enhanced its anti-tumour effects. This protective effect appeared to be mediated by inhibiting DNA damage via the CHEK-TAp63α pathway and by generation of anti-apoptotic signals in the oocytes.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This was a preclinical study performed with human ovarian samples, and clinical research is required for validation.

WIDER IMPLICATIONS OF THE FINDINGS

These findings highlight the therapeutic potential of CHEK1/2 inhibitors as a complementary strategy for preserving fertility in female cancer patients.

STUDY FUNDING/COMPETING INTEREST(S)

This work was financially supported by the National Natural Science Foundation of China (nos. 82001514 and 81902669) and the Fundamental Research Funds for the Central Universities (2021yjsCXCY087). The authors declare no conflict of interest.

The effect and mechanism of Zigui-Yichong-Fang on improving ovarian reserve in premature ovarian insufficiency by activating SIRT1/Foxo3a pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zigui-Yichong-Fang (ZGYCF) is a traditional Chinese medicine prescription for the treatment of infertility. It is clinically used to regulate the hormone level of patients, improve ovarian reserve function and increase pregnancy rate. However, the exact mechanism of action is not yet clear.

AIMS OF THE STUDY

This study aims to explore the potential impact of ZGYCF on POI and its mechanism.

MATERIALS AND METHODS

Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to identify the main compounds of ZGYCF. After confirming the therapeutic effect of ZGYCF on cyclophosphamide-induced POI mice, RNA sequencing (RNA-seq) analysis was carried out to explore the mechanism. Then, the effects of ZGYCF on SIRT1 deacetylated Foxo3a and apoptosis were verified from multiple perspectives by serum hormone level, mRNA validation, histomorphology and protein expression, acetylation modification and other experiments.

RESULTS

ZGYCF can improve the morphological changes of ovarian tissue in POI model mice, reduce the damage of primordial follicles and other follicles at all stages, and protect ovarian reserve. The results of transcriptome sequencing showed that the genes expression of PI3K signal and apoptosis signal pathway were increased in POI model mice; ZGYCF can up-regulate the expression of SIRT1 gene and the expression of estradiol, apoptosis inhibition and other signal pathway genes. In addition, ZGYCF can reduce follicular damage and ovarian cell apoptosis in POI model mice through activating the deacetylation of Foxo3a by SIRT1, and improve ovarian reserve function.

CONCLUSIONS

ZGYCF may improve ovarian reserve function of CTX-induced POI mice by activating SIRT1-mediated deacetylation of Foxo3a, and play a role in the treatment of POI.

The future of fertility preservation for women treated with chemotherapy

Cytotoxic chemotherapies have been a mainstay of cancer treatment, but are associated with numerous systemic adverse effects, including impacts to fertility and endocrine health. Irreversible ovarian damage and follicle depletion are side-effects of chemotherapy that can lead to infertility and premature menopause, both being major concerns of young cancer patients. Notably, many women will proceed with fertility preservation, but unfortunately existing strategies don't entirely solve the problem. Most significantly, oocyte and embryo freezing do not prevent cancer treatment-induced ovarian damage from occurring, which may result in the impairment of long-term hormone production. Unfortunately, loss of endogenous endocrine function is not fully restored by hormone replacement therapy. Additionally, while GnRH agonists are standard care for patients receiving alkylating chemotherapy to lessen the risk of premature menopause, their efficacy is incomplete. The lack of more broadly effective options stems, in part, from our poor understanding of how different treatments damage the ovary. Here, we summarise the impacts of two commonly utilised chemotherapies - cyclophosphamide and cisplatin - on ovarian function and fertility, and discuss the mechanisms underpinning this damage. Additionally, we critically analyse current research avenues in the development of novel fertility preservation strategies, with a focus on fertoprotective agents.

TAp63 determines the fate of oocytes against DNA damage

Cyclophosphamide and doxorubicin lead to premature ovarian insufficiency as an off-target effect. However, their oocyte death pathway has been debated. Here, we clarified the precise mechanism of ovarian depletion induced by cyclophosphamide and doxorubicin. Dormant oocytes instead of activated oocytes with high PI3K activity were more sensitive to cyclophosphamide. Checkpoint kinase 2 (CHK2) inhibitor rather than GNF2 protected oocytes from cyclophosphamide and doxorubicin, as cyclophosphamide up-regulated p-CHK2 and depleted primordial follicles in Abl1 knockout mice. Contrary to previous reports, TAp63 is pivotal in cyclophosphamide and doxorubicin-induced oocyte death. Oocyte-specific Trp63 knockout mice prevented primordial follicle loss and maintained reproductive function from cyclophosphamide and doxorubicin, indicated by undetectable levels of BAX and cPARP. Here, we demonstrated that TAp63 is fundamental in determining the signaling of oocyte death against DNA damage. This study establishes the role of TAp63 as a target molecule of adjuvant therapies to protect the ovarian reserve from different classes of chemotherapy.

DNA Damage Stress Response and Follicle Activation: Signaling Routes of Mammalian Ovarian Reserve

Chemotherapy regimens and radiotherapy are common strategies to fight cancer. In women, these therapies may cause side effects such as premature ovarian insufficiency (POI) and infertility. Clinical strategies to protect the ovarian reserve from the lethal effect of cancer therapies needs better understanding of the mechanisms underlying iatrogenic loss of follicle reserve. Recent reports demonstrate a critical role for p53 and CHK2 in the oocyte response to different DNA stressors, which are commonly used to treat cancer. Here we review the molecular mechanisms underlying the DNA damage stress response (DDR) and discuss crosstalk between DDR and signaling pathways implicated in primordial follicle activation.

Royal Jelly: Beneficial Properties and Synergistic Effects with Chemotherapeutic Drugs with Particular Emphasis in Anticancer Strategies

Cancer is one of the major causes of death globally. Currently, various methods are used to treat cancer, including radiotherapy, surgery, and chemotherapy, all of which have serious adverse effects. A healthy lifestyle, especially a nutritional diet, plays a critical role in the treatment and prevention of many disorders, including cancer. The above notion, plus the trend in going back to nature, encourages consumers and the food industry to invest more in food products and to find potential candidates that can maintain human health. One of these agents, and a very notable food agent, is royal jelly (RJ), known to be produced by the hypopharyngeal and mandibular salivary glands of young nurse honeybees. RJ contains bioactive substances, such as carbohydrates, protein, lipids, peptides, mineral salts and polyphenols which contribute to the appreciated biological and pharmacological activities. Antioxidant, anticancer, anti-inflammatory, antidiabetic, and antibacterial impacts are among the well-recognized benefits. The combination of RJ or its constituents with anticancer drugs has synergistic effects on cancer disorders, enhancing the drug’s effectiveness or reducing its side effects. The purpose of the present review is to emphasize the possible interactions between chemotherapy and RJ, or its components, in treating cancer illnesses.

Epigallocatechin-3-gallate attenuates cyclophosphamide-induced damage in mouse ovarian tissue via suppressing inflammation, apoptosis, and expression of phosphorylated Akt, FOXO3a and rpS6

This study was conducted to evaluate the protective effects of epigallocatechin-3-gallate (EGCG) against ovarian toxicity in cyclophosphamide-treated mice and to verify the possible involvement of phosphorylated Akt, FOXO3a and rpS6 in the EGCG actions. Mice received saline solution (i.p.; control) or a single dose of cyclophosphamide (200 mg/kg body weight, i.p.) or mice were pretreated with N-acetylcysteine (150 mg/kg body weight, i.p.; positive control) or with EGCG (5, 25 or 50 mg/kg body weight, i.p.) once daily for three days followed by injection with single dose of cyclophosphamide (200 mg/kg body weight, i.p.). Thereafter, the mice were euthanized, and the ovaries were harvested and destined to histological (follicular morphology and activation), immunohistochemistry (cleaved caspase-3 and TNF-α) and fluorescence (mitochondrial activity and GSH concentrations) analyses. Furthermore, we examined the participation of p-Akt, p-FOXO3a and p-rpS6 in the protective effects of EGCG in cyclophosphamide-induced ovarian damage by immunohistochemical staining. The results showed that pretreatment with N-acetylcysteine or EGCG at 25 and 50 mg/kg before cyclophosphamide administration preserved the normal follicular morphology, prevented primordial follicle loss, reduced atresia, inflammation, and mitochondrial damage, and increased GSH concentrations compared to the only cyclophosphamide treatment. Additionally, pretreatment with 25 mg/kg EGCG regulated phosphorylated Akt, FOXO3a and rpS6 after cyclophosphamide treatment. In conclusion, short-time pretreatment with 25 mg/kg EGCG can prevent follicle loss in cyclophosphamide-treated mice by reducing oxidative damage, inflammation, and apoptosis, and regulating of p-Akt, p-FOXO3a and p-rpS6.

Rapamycin maintains the primordial follicle pool and protects ovarian reserve against cyclophosphamide-induced damage

Any abnormal activation of primordial follicles and subsequent depletion can irreversibly diminish the ovarian reserve, which is one of the major chemotherapy-induced adverse effects in young patients with cancer. Herein, we investigated the effects of rapamycin on the activation and development of ovarian follicles to evaluate its fertility-sparing therapeutic value in a cyclophosphamide (CTX)-treated mouse model. Based on ovarian histomorphological changes and follicle counting in 50 SPF female C57BL/6 mice, daily administration of 5 mg/kg rapamycin for 30 days was deemed an ideal dosage and duration for administration in subsequent experiments. Compared with the control group, rapamycin treatment inhibited the activation of quiescent primordial follicles, with no obvious side effects observed. Finally, 48 mice were randomly divided into four groups: control, rapamycin-treated, cyclophosphamide-treated, and rapamycin intervention. Body weight, ovarian histomorphological changes, number of primordial follicles, DDX4/MVH expression, apoptosis of follicular cells, and expression of apoptosis protease-activating factor (APAF)-1, cleaved caspase 3, and caspase 3 were monitored. Co-administration of rapamycin reduced primordial follicle loss and the development of follicular cell apoptosis, thereby rescuing the ovarian reserve after CTX treatment. On analyzing the mTOR signaling pathway, we observed that rapamycin significantly decreased CTX-mediated overactivation of mTOR and its downstream molecules. These findings suggest that rapamycin exhibits potential as an ovarian-protective agent that could maintain the ovarian primordial follicle pool and preserve fertility in young female patients with cancer undergoing chemotherapy.

Network Pharmacology-Based Prediction and Verification of the Potential Mechanisms of He's Yangchao Formula against Diminished Ovarian Reserve

Background

He's Yangchao formula (HSYC) has been clinically proven to be effective in treating diminished ovarian reserve (DOR). However, the underlying molecular mechanisms of HSYC in DOR are unclear.

Objective

This study aims to predict the underlying mechanisms of He's Yangchao formula (HSYC) against DOR through network pharmacology strategies and verify in vivo.

Methods

Systematic network pharmacology was used to speculate the bioactive components, potential targets, and the underlying mechanism of HSYC in the treatment of DOR. Then, the CTX-induced DOR mouse model was established to verify the effect of HSYC against DOR and the possible molecular mechanisms as predicted in the network pharmacology approach.

Results

A total of 44 active components and 423 potential targets were obtained in HSYC. In addition, 91 targets of DOR were also screened. The identified hub genes were AKT1, ESR1, IL6, and P53. Further molecular docking showed that the four hub targets were well-bound with their corresponding compounds. In vivo experiments showed that HSYC could promote the recovery of the estrous cycle and increase the number of primordial, growing follicles and corpora lutea. Besides, The results of qRT-PCR showed HSYC could regulate the expression of AKT1, ESR1, P53, and IL6 in DOR mice.

Conclusion

It was demonstrated that HSYC could increase ovarian reserves, and AKT1, ESR1, IL6, and P53 may play an essential role in this effect, which provided a new reference for the current lack of active interventions of DOR.

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.

Potential use of bacterial pigments as anticancer drugs and female reproductive toxicity: a review

Abstract Natural bioactive compounds obtained from microorganisms, have awakened particular interest in the industry nowadays. This attention comes when natural resources depletion is pronounced, and the acquisition of both new plant origin resources and bioactive products, represents a challenge for the next generations. In this sense, prospecting for large-scale production and use of bacterial pigments is a necessary strategy for the development of novel products. A wide variety of properties have been attributed to these substances and, among them, their therapeutic potential against important diseases, such as cancer. There is consensus that available chemotherapy protocols are known to detrimentally affect cancer patients fertility. Hence, considerable part of the deleterious effects of chemotherapy is related to the drugs cytotoxicity, which, in addition to cancer cells, also affect normal cells. Therefore, the intrinsic properties of bacterial pigments associated with low cytotoxicity and relevant cell selectivity, certified them as potential anticancer drugs. However, little information is available about reproductive toxicity of these new and promising compounds. Thus, the present review aims to address the main bacterial pigments, their potential uses as anticancer drugs and their possible toxic effects, especially on the female gonad.

Uso potencial de pigmentos bacterianos como drogas anticâncer e toxicidade reprodutiva feminina: uma revisão

Resumo Os compostos bioativos naturais obtidos de microrganismos têm despertado especial interesse da indústria nos últimos anos. Esta atenção ocorre em um momento em que o esgotamento de recursos naturais é pronunciado, e a aquisição de novos insumos e produtos bioativos de origem vegetal representa um desafio para as próximas gerações. Neste sentido, a prospecção para a produção e uso em larga escala dos pigmentos bacterianos tem representado uma importante estratégia para o desenvolvimento de novos produtos. Uma grande variedade de propriedades foi atribuída a estas substâncias, entre elas, o potencial terapêutico contra doenças importantes, como o câncer. Existe um consenso de que os protocolos quimioterápicos disponíveis são conhecidos por afetarem negativamente a fertilidade de pacientes com câncer. Grande parte dos efeitos deletérios da quimioterapia está relacionado à citotoxicidade das drogas usadas para este fim, que além das células cancerosas, afetam as células normais. Nesse sentido, as propriedades naturais atribuídas aos pigmentos bacterianos associadas à baixa citotoxicidade e relevante seletividade, os qualificaram como potenciais drogas anticâncer. No entanto, pouco se tem de informação a respeito da toxicidade reprodutiva destes novos e promissores compostos. Dessa forma, a presente revisão tem o objetivo de abordar os principais pigmentos bacterianos, suas utilizações potenciais como drogas anticâncer, bem como os seus possíveis efeitos tóxicos, sobretudo, sobre a gônada feminina.

Melatonin Attenuates Cyclophosphamide-Induced Primordial Follicle Loss by Interaction with MT1 Receptor and Modulation of PTEN/Akt/FOXO3a Proteins in the Mouse Ovary

This study evaluated the protective effect of melatonin before cyclophosphamide administration on ovarian function and its potential mechanism in a mouse model. Two studies were performed. In the first, mice were pretreated with melatonin (10, 20, or 30 mg/kg body weight, i.p.) once daily for 3 days, followed by injection with a single dose of cyclophosphamide (200 mg/kg body weight, i.p.) 30 min after the last melatonin injection. The second study analyzed whether melatonin type 1 and/or 2 receptors mediate the effects of melatonin on the ovary through administration of non-selective MT₁/MT₂ antagonist (luzindole) or selective MT₂ antagonist (4-PPDOT) before the treatment with melatonin plus cyclophosphamide. After treatment groups, the ovaries were harvested and destined to histology, immunohistochemistry, and fluorescence analyses. Lastly, we examined the p-PTEN, p-Akt, and p-FOXO3a participation in the protective effect of melatonin in cyclophosphamide-induced ovarian damage. Results demonstrated that pretreatment with 20 mg/kg melatonin before cyclophosphamide administration showed more morphologically normal follicles, attenuated primordial follicle loss, decreased growing follicle atresia and mitochondrial damage, and increased GSH concentrations. Furthermore, treatment with luzindole blocked the protective effects of melatonin against the damage caused by cyclophosphamide. Additionally, pretreatment with 20 mg/kg melatonin regulated the PTEN/Akt/FOXO3a signaling pathway components after cyclophosphamide treatment. In conclusion, pretreatment with 20 mg/kg melatonin prevented primordial follicle loss and reduced apoptosis and oxidative damage in the mouse ovary during experimental chemotherapy with cyclophosphamide. Furthermore, the MT₁ receptor and PTEN/Akt/FOXO3a proteins mediated these cytoprotective effects.

Unraveling the mechanisms of chemotherapy-induced damage to human primordial follicle reserve: road to developing therapeutics for fertility preservation and reversing ovarian aging

Among the investigated mechanisms of chemotherapy-induced damage to human primordial follicle reserve are induction of DNA double-strand breaks (DSBs) and resultant apoptotic death, stromal-microvascular damage and follicle activation. Accumulating basic and translational evidence suggests that acute exposure to gonadotoxic chemotherapeutics, such as cyclophosphamide or doxorubicin, induces DNA DSBs and triggers apoptotic death of primordial follicle oocytes within 12-24 h, resulting in the massive loss of ovarian reserve. Evidence also indicates that chemotherapeutic agents can cause microvascular and stromal damage, induce hypoxia and indirectly affect ovarian reserve. While it is possible that the acute reduction of the primordial follicle reserve by massive apoptotic losses may result in delayed activation of some primordial follicles, this is unlikely to be a predominant mechanism of loss in humans. Here, we review these mechanisms of chemotherapy-induced ovarian reserve depletion and the potential reasons for the discrepancies among the studies. Based on the current literature, we propose an integrated hypothesis that explains both the acute and delayed chemotherapy-induced loss of primordial follicle reserve in the human ovary.

Quercetin prevents primordial follicle loss via suppression of PI3K/Akt/Foxo3a pathway activation in cyclophosphamide-treated mice

BACKGROUND

Chemotherapy improves the survival rates of patients with various cancers but often causes some adverse effects, including ovarian damage, characterised by a decrease in primordial follicle stockpiles. Recent studies have revealed that chemotherapy may stimulate the PI3K signalling pathway, thereby resulting in accelerated primordial follicle activation and a decreased ovarian reserve. Quercetin is an inhibitor of the PI3K pathway; however, its protective effects against chemotherapy-induced follicle loss in mice have not been established. In this study, the effects of quercetin in a mouse model of cyclophosphamide-induced ovarian dysfunction were investigated.

METHODS

C57BL/6 female mice were used for the study. Paraffin sections of mouse ovaries (n = 30 mice) were stained with haematoxylin and eosin for differential follicle counts. Apoptosis (n = 5 mice per group) was evaluated by TUNEL assay. Immunohistochemical staining for ki67 and Foxo3a (n = 5 mice per group) was performed to evaluate the activation of primordial follicles. The role of the PI3K signalling pathway in the ovaries (n = 45 mice) was assessed by western blotting.

RESULTS

Quercetin attenuated the cyclophosphamide-induced reduction in dormant primordial follicles. Analysis of the PI3K/Akt/Foxo3a pathway showed that quercetin decreased the phosphorylation of proteins that stimulate follicle activation in cyclophosphamide-induced ovaries. Furthermore, quercetin prevented cyclophosphamide-induced apoptosis in early growing follicles and early antral follicles, maintained anti-Müllerian hormone levels secreted by these follicles, and preserved the quiescence of the primordial follicle pool, as determined by intranuclear Foxo3a staining.

CONCLUSIONS

Quercetin attenuates cyclophosphamide-induced follicle loss by preventing the phosphorylation of PI3K/Akt/Foxo3a pathway members and maintaining the anti-Müllerian hormone level through reduced apoptosis in growing follicles. Accordingly, quercetin is expected to improve fertility preservation and the prevention of endocrine-related side effects of chemotherapy.

Asciminib Mitigates DNA Damage Stress Signaling Induced by Cyclophosphamide in the Ovary

Cancer treatments can often adversely affect the quality of life of young women. One of the most relevant negative impacts is the loss of fertility. Cyclophosphamide is one of the most detrimental chemotherapeutic drugs for the ovary. Cyclophosphamide may induce the destruction of dormant follicles while promoting follicle activation and growth. Herein, we demonstrate the in vivo protective effect of the allosteric Bcr-Abl tyrosine kinase inhibitor Asciminib on signaling pathways activated by cyclophosphamide in mouse ovaries. We also provide evidence that Asciminib does not interfere with the cytotoxic effect of cyclophosphamide in Michigan Cancer Foundation (MCF)7 breast cancer cells. Our data indicate that concomitant administration of Asciminib mitigates the cyclophosphamide-induced ovarian reserve loss without affecting the anticancer potential of cyclophosphamide. Taken together, these observations are relevant for the development of effective ferto-protective adjuvants to preserve the ovarian reserve from the damaging effects of cancer therapies.

Metformin: a novel promising option for fertility preservation during cyclophosphamide-based chemotherapy

Cyclophosphamide (CP) could cause severe gonadotoxicity via imbalanced activation of primordial follicles through PI3K/AKT/mTOR activation. Whether metformin, a widely prescribed anti-diabetes agent with mTOR inhibitory effect, could preserve ovarian function against CP toxicity is unknown. Female C57BL/6 mice were randomized into seven groups (n = 11), including control, CP-alone, CP + metformin, CP + sirolimus or everolimus, metformin-alone and sirolimus-alone groups. The duration of pharmaceutical treatment was 4 weeks. CP treatment significantly impaired ovarian function and fertility in mice. CP + metformin treatment significantly attenuated the gonadotoxicity comparing to CP-alone treatment (primordial follicle count: 17.6 ± 4.2 versus 10.3 ± 2.7 follicles/high-power field; P = 0.027). CP + metformin treatment also tended to increase antral follicular count (5.4 ± 1.1 versus 2.5 ± 1.6 follicles/section), serum AMH levels (4.6 ± 1.2 versus 2.0 ± 0.8 ng/ml) and the litter size (4.2 ± 1.3 versus 1.5 ± 1.0 mice per pregnancy), compared with CP-alone group. Expression of phospho-mTOR and the number of TUNEL-positive granulosa cells increased after CP treatment and decreased in the CP + metformin groups, suggesting the mTOR inhibitory and anti-apoptotic effects of metformin. In in-vitro granulosa cell experiments, the anti-apoptotic effect of metformin was blocked after inhibiting p53 or p21 function, and the expression of p53 mRNA was blocked with AMPK inhibitor, suggesting that the anti-apoptotic effect was AMPK/p53/p21-mediated. In conclusion, concurrent metformin treatment during CP therapy could significantly preserve ovarian function and fertility and could be a promising novel fertility preserving agent during chemotherapy. The relatively acceptable cost and well-established long-term safety profiles of this old drug might prompt its further clinical application at a faster pace.

Ovaries of patients recently treated with alkylating agent chemotherapy indicate the presence of acute follicle activation, elucidating its role among other proposed mechanisms of follicle loss

OBJECTIVE

To investigate mechanisms of primordial follicle (PMF) loss in vivo in human ovaries shortly after alkylating agent (AA) chemotherapy.

DESIGN

Cohort study.

SETTING

Tertiary university medical center.

PATIENT(S)

Ninety-six women aged 15-39 years who underwent ovarian tissue cryopreservation for fertility preservation.

INTERVENTION(S)

Fresh ovarian tissue samples were harvested from women treated with AA (n = 24) or non-AA (n = 24) chemotherapy <6 months after treatment and age-matched untreated women (n = 48).

MAIN OUTCOME MEASURE(S)

Differential follicle counts, time from chemotherapy exposure, immunostaining for apoptosis (cleaved caspase-3) and FOXO3A on tissue harvested within ultrashort time intervals (4-12 days), collagen (Sirius red) and neovascularization (CD34).

RESULT(S)

AA-treated ovaries had significant loss of PMFs, and significant increase in absolute numbers of growing follicles compared with untreated control ovaries. The number of growing follicles was inversely correlated with time from chemotherapy. Representative staining for FOXO3A observed decreased nuclear localization in PMF oocytes in AA-treated ovaries removed within the ultrashort time interval compared with untreated ovaries. Neither significant loss of PMFs, increase in growing follicles, nor decrease in nuclear FOXO3A were observed in non-AA-treated ovaries. No increased expression of cleaved caspase-3 was seen in PMFs within the ultrashort time interval after AA or non-AA chemotherapy. Significant stromal fibrosis and neovascularization were observed in AA-treated ovaries only after follicle loss had already occurred (4-6 months).

CONCLUSION(S)

Follicle activation occurs in vivo in ovaries of patients treated with AA, indicating a pathologic mechanism which may contribute to chemotherapy-induced follicle loss.

Chemoprotective effects of plasma derived from mice of different ages and genders on ovarian failure after cyclophosphamide treatment

Background

Premature ovarian failure is one of the major side effects of chemotherapy drugs. Blood plasma contains several factors that might lead to the repair of different tissues.

Objective

The chemoprotective effects of plasma derived from mice with different ages and genders were assessed on ovarian tissue in cyclophosphamide-treated mice.

Methods

Forty-two adult female mice were divided into six groups as follows: (A) control; (B) 0.9% sodium chloride as vehicle; (C) cyclophosphamide; (D) cyclophosphamide + young male blood plasma; (E) cyclophosphamide + old male blood plasma; (F) cyclophosphamide + young female blood plasma. Ovarian failure was induced by injecting cyclophosphamide. On the 1st day, three groups received simultaneous injections of 150 μL intraperitoneal and 70 μL intravenous plasma derived from mice of different ages and genders. Each plasma type (150 μL) was then injected intraperitoneally every other 3 days for 19 days. On day 21, the dissected ovaries were stained for stereological analysis. Also, estrogen and progesterone levels were measured.

Results

Cyclophosphamide had damaging effects on ovarian parameters and led to reduced hormone levels in comparison with the control group. However, treating with young female and, old male blood plasma, to a lesser degree, showed beneficial effects on the number of primordial follicles, pre-antral follicles, and granulosa cells. Also, these two treatments had protective effects on the volume of ovarian parameters as well as estrogen and progesterone levels in comparison with the cyclophosphamide group (P < 0.05).

Conclusion

Plasma derived from mice of different ages and genders can ameliorate premature ovarian failure against the adverse effects of cyclophosphamide.

Protective Effects and Possible Mechanisms of Actions of Bushen Cuyun Recipe on Diminished Ovarian Reserve Induced by Cyclophosphamide in Rats

Backgrounds

Diminished ovarian reserve (DOR) contributes significantly to female infertility. Bushen Cuyun Recipe (BCR, Tradename Yueliang Yin), a product marketed in China, has shown effects in the treatment of female infertility in clinical practices of traditional Chinese medicine (TCM). In this study, we aimed to investigate the chemical compositions of BCR and its efficacy based on scientific evidence and pharmacological mechanisms in DOR treatments.

Methods

The chemical compositions of BCR were determined by the UHPLC-LTQ-Orbitrap MS method. DOR was induced in a rat model by intraperitoneal injection of cyclophosphamide (CTX) 90 mg/kg once. After the CTX treatment for 14 days, rats were intragastrically administrated deionized water, dehydroepiandrosterone (DHEA), or BCR in low, middle, and high doses for 30 days. Ovarian index, ovarian morphology, follicle number, and anti-Müllerian hormone (AMH) in serum were determined to assess the effects of BCR. To investigate possible action mechanisms, network pharmacological analysis was used to predict possible pathways in the effects of BCR on female infertility. In experimental studies, the contents of hormones in the hypothalamic-pituitary-ovarian axis (HPOA, including estradiol (E₂), follicle-stimulating hormone (FSH), and gonadotropin-releasing hormone (GnRH)) and pyroptosis-related proteins, including gasdermin D (GSDMD), caspase-1, and interleukin-18 (IL-18), in ovarian were detected by ELISA, immunofluorescence and Western blot.

Results

Chemical studies revealed a total 84 components in BCR, which included 43 flavonoids, 13 triterpenoids, 11 phenolic acids, 8 alkaloids, 1 coumarin, 1 anthraquinone, and 7 other components. After treatments with BCR, the ovarian morphology, ovarian index, estrous cycle, growing follicles and corpus luteum from last ovulation, and serum AMH in DOR rats were significantly improved. Network pharmacological analysis suggested that the NOD-like receptor signaling pathway ranked No. 1 among the mechanisms by which BCR affects female infertility. Experimental results demonstrated that the content of serum FSH in DOR rats was significantly decreased and the contents of serum GnRH and E₂ were significantly elevated after BCR treatment and that the elevated level of GSDMD, caspase-1, and IL-18 was significantly reversed in BCR-treated rats.

Conclusions

The chemical compositions of BCR were first identified in the present study. BCR was demonstrated to show protective effects on DOR. The possible mechanisms of BCR on DOR might be mediated by regulating gonadal hormones of the HPOA and protecting granulosa cells in ovary against pyroptosis.