Multidrug Resistance Protein 1 Deficiency Promotes Doxorubicin-Induced Ovarian Toxicity in Female Mice

Effects of Cyanobacterial Harmful Algal Bloom Toxin Microcystin-LR on Gonadotropin-Dependent Ovarian Follicle Maturation and Ovulation in Mice

BACKGROUND

Cyanobacterial harmful algal blooms (CyanoHABs) originate from the excessive growth or bloom of cyanobacteria often referred to as blue-green algae. They have been on the rise globally in both marine and freshwaters in recently years with increasing frequency and severity owing to the rising temperature associated with climate change and increasing anthropogenic eutrophication from agricultural runoff and urbanization. Humans are at a great risk of exposure to toxins released from CyanoHABs through drinking water, food, and recreational activities, making CyanoHAB toxins a new class of contaminants of emerging concern.

OBJECTIVES

We investigated the toxic effects and mechanisms of microcystin-LR (MC-LR), the most prevalent CyanoHAB toxin, on the ovary and associated reproductive functions.

METHODS

Mouse models with either chronic daily oral or acute intraperitoneal exposure, an engineered three-dimensional ovarian follicle culture system, and human primary ovarian granulosa cells were tested with MC-LR of various dose levels. Single-follicle RNA sequencing, reverse transcription-quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, immunohistochemistry (IHC), and benchmark dose modeling were used to examine the effects of MC-LR on follicle maturation, hormone secretion, ovulation, and luteinization.

RESULTS

Mice exposed long term to low-dose MC-LR did not exhibit any differences in the kinetics of folliculogenesis, but they had significantly fewer corpora lutea compared with control mice. Superovulation models further showed that mice exposed to MC-LR during the follicle maturation window had significantly fewer ovulated oocytes. IHC results revealed ovarian distribution of MC-LR, and mice exposed to MC-LR had significantly lower expression of key follicle maturation mediators. Mechanistically, in both murine and human granulosa cells exposed to MC-LR, there was reduced protein phosphatase 1 (PP1) activity, disrupted PP1-mediated PI3K/AKT/FOXO1 signaling, and less expression of follicle maturation-related genes.

DISCUSSION

Using both in vivo and in vitro murine and human model systems, we provide data suggesting that environmentally relevant exposure to the CyanoHAB toxin MC-LR interfered with gonadotropin-dependent follicle maturation and ovulation. We conclude that MC-LR may pose a nonnegligible risk to women's reproductive health by heightening the probability of irregular menstrual cycles and infertility related to ovulatory disorders. https://doi.org/10.1289/EHP12034.

Recapitulating folliculogenesis and oogenesis outside the body: encapsulated in vitro follicle growth†

Folliculogenesis is a tightly coordinated process essential for generating a fertilization-competent gamete while also producing gonadal hormones that sustain endocrine function. In vitro follicle growth systems have been critical to our understanding of key events in folliculogenesis, such as gonadotropin-independent and dependent growth, steroid hormone production, and oocyte growth and maturation (cytoplasmic and meiotic). Although there are several successful follicle culture strategies, the following protocol details an encapsulated in vitro follicle growth (eIVFG) system for use with mouse ovarian follicles. Encapsulated IVFG is performed with alginate hydrogels, which are biologically inert, maintains cell-to-cell interactions between granulosa cells and the oocyte, and preserves follicle architecture as found in the ovary. The system supports follicle growth, development, and differentiation from the early primary follicle to the antral follicle stage. Moreover, post-folliculogenesis events including meiotic maturation, ovulation, and luteinization are also supported. Importantly, the culture of secondary follicles has successfully resulted in viable pups after blastocyst transfer. This alginate-based eIVFG system is versatile and has broad applications as a tool for interrogating the fundamental biology of the ovarian follicle in a controlled manner, a screening platform for toxicity and bioactivity, and a potential fertility preservation method for endangered species as well as humans.

Gene/environment interaction in the susceptibility of Crohn's disease patients to aluminum

BACKGROUND & AIM

The key role of environmental factors in the pathogenesis of Inflammatory Bowel Diseases (IBD) is recognized. Aluminum is suspected to be a risk factor for IBD. However, mechanisms linking aluminum exposure to disease development are unknown. We examined the role of aluminum transport and subcellular localisation on human colon susceptibility to aluminum-induced inflammation.

METHODS

Human colon biopsies isolated from Crohn's disease (CD) or control patients and Caco-2 cells were incubated with aluminum. The effects of aluminum were evaluated on cytokine secretion and transporter expression. The role of aluminum kinetics parameters was studied in Caco-2 using transport inhibitors and in human colon biopsies by assessing genetic polymorphisms of transporters.

RESULTS

Aluminum exposure was shown to induce cytokine secretion in colon of CD but not healthy patients. In Caco-2 cells, aluminum internalisation was correlated with inflammatory status. In human colon, analysis of genetic polymorphisms and expression of ABCB1 and SLC26A3 transporters showed that their decreased activity was involved in aluminum-induced inflammation.

CONCLUSIONS

We hypothesize that alteration in detoxifying response would lead to a deregulation of intestinal homeostasis and to the expression of IBD. Our study emphasizes the complexity of gene/environment interaction for aluminum adverse health effect, highlighting at risk populations or subtypes of patients. A better understanding of correlations between gene expression or SNP and xenobiotic kinetics parameters would shift the medical paradigm to more personalized disease management and treatment.

Development of protective agents against ovarian injury caused by chemotherapeutic drugs

BACKGROUND

Chemotherapy is one of the causes of ovarian injury and infertility. Although assisted reproductive technology helps young female patients with cancer become pregnant, preventing chemotherapy-induced ovarian injury will often possess even more significant benefits.

OBJECTIVE

We aimed at demonstrating the hazardous effects and mechanisms of ovarian injury by chemotherapeutic agents, as well as demonstrating agents that protect the ovary from chemotherapy-induced injury.

RESULTS

Chemotherapeutic agents cause death or accelerate activation of follicles and damage to the blood vessels in the ovary, resulting in inflammation. These often require drug development to protect the ovaries from injury.

CONCLUSIONS

Our findings provide a basis for the development of drugs to protect the ovaries from injury. Although there are many preclinical studies on potential protective drugs, there is still an urgent need for a large number of clinical experiments to verify their potential use.

A synopsis of global frontiers in fertility preservation

Since 2007, the Oncofertility Consortium Annual Conference has brought together a diverse network of individuals from a wide range of backgrounds and professional levels to disseminate emerging basic and clinical research findings in fertility preservation. This network also developed enduring educational materials to accelerate the pace and quality of field-wide scientific communication. Between 2007 and 2019, the Oncofertility Consortium Annual Conference was held as an in-person event in Chicago, IL. The conference attracted approximately 250 attendees each year representing 20 countries around the world. In 2020, however, the COVID-19 pandemic disrupted this paradigm and precluded an in-person meeting. Nevertheless, there remained an undeniable demand for the oncofertility community to convene. To maintain the momentum of the field, the Oncofertility Consortium hosted a day-long virtual meeting on March 5, 2021, with the theme of "Oncofertility Around the Globe" to highlight the diversity of clinical care and translational research that is ongoing around the world in this discipline. This virtual meeting was hosted using the vFairs ® conference platform and allowed over 700 people to participate, many of whom were first-time conference attendees. The agenda featured concurrent sessions from presenters in six continents which provided attendees a complete overview of the field and furthered our mission to create a global community of oncofertility practice. This paper provides a synopsis of talks delivered at this event and highlights the new advances and frontiers in the fields of oncofertility and fertility preservation around the globe from clinical practice and patient-centered efforts to translational research.

Transporters and Toxicity: Insights from the International Transporter Consortium Workshop 4

Over the last decade, significant progress been made in elucidating the role of membrane transporters in altering drug disposition, with important toxicological consequences due to changes in localized concentrations of compounds. The topic of "Transporters and Toxicity" was recently highlighted as a scientific session at the International Transporter Consortium (ITC) Workshop 4 in 2021. The current white paper is not intended to be an extensive review on the topic of transporters and toxicity but an opportunity to highlight aspects of the role of transporters in various toxicities with clinically relevant implications as covered during the session. This includes a review of the role of solute carrier transporters in anticancer drug-induced organ injury, transporters as key players in organ barrier function, and the role of transporters in metal/metalloid toxicity.

Varied effects of doxorubicin (DOX) on the corpus luteum of C57BL/6 mice during early pregnancy

Certain chemotherapeutic drugs are toxic to ovarian follicles. The corpus luteum (CL) is normally developed from an ovulated follicle for producing progesterone (P4) to support early pregnancy. To fill in the knowledge gap about effects of chemotherapy on the CL, we tested the hypothesis that chemotherapy may target endothelial cells and/or luteal cells in the CL to impair CL function in P4 steroidogenesis using doxorubicin (DOX) as a representative chemotherapeutic drug in mice. In both mixed background mice and C57BL/6 mice, a single intraperitoneal injection of DOX (10 mg/kg) on 0.5 days post coitum (D0.5, post-ovulation) led to ~58% D3.5 mice with serum P4 levels lower than the serum P4 range in the PBS-treated control mice. Further studies in the C57BL/6 ovaries revealed that CLs from DOX-treated mice with low P4 levels had less defined luteal cords and disrupted collagen IV expression pattern, indicating disrupted capillary, accompanied with less differentiated luteal cells that had smaller cytoplasm and reduced StAR expression. DOX-treated ovaries had increased granulosa cell death in the growing follicles, reduced PCNA-positive endothelial cells in the CLs, enlarged lipid droplets and disrupted F-actin in the luteal cells. These novel data suggest that the proliferating endothelial cells in the developing CL may be the primary target of DOX to impair the vascular support for luteal cell differentiation and subsequently P4 steroidogenesis. This study fills in the knowledge gap about the toxic effects of chemotherapy on the CL and provides critical information for risk assessment of chemotherapy in premenopausal patients.

A Tiered Female Ovarian Toxicity Screening Identifies Toxic Effects of Checkpoint Kinase 1 Inhibitors on Murine Growing Follicles

Ovarian toxicity (ovotoxicity) is one of the major side effects of pharmaceutical compounds for women at or before reproductive age. The current gold standard for screening of compounds' ovotoxicity largely relies on preclinical investigations using whole animals. However, in vivo models are time-consuming, costly, and harmful to animals. Here, we developed a 3-tiered ovotoxicity screening approach starting from encapsulated in vitro follicle growth (eIVFG) and screened for the potential ovotoxicity of 8 preclinical compounds from AstraZeneca (AZ). Results from Tiers 1 to 2 screenings using eIVFG showed that the first 7 tested AZ compounds, AZ-A, -B, -C, -D, -E, -F, and -G, had no effect on examined mouse follicle and oocyte reproductive outcomes, including follicle survival and development, 17β-estradiol secretion, ovulation, and oocyte meiotic maturation. However, AZ-H, a preclinical compound targeting the checkpoint kinase 1 inhibitor to potentiate the anticancer effects of DNA-damaging agents, significantly promoted granulosa cell apoptosis and the entire growing follicle atresia at clinically relevant concentrations of 1 and 10 μM. The more targeted explorations in Tier 2 revealed that the ovotoxic effect of AZ-H primarily resulted from checkpoint kinase 1 inhibition in granulosa cells. Using in vivo mouse model, the Tier 3 screening confirmed the in vitro ovotoxicities of AZ-H discovered in Tiers 1 and 2. Also, although AZ-H at 0.1 μM alone was not ovotoxic, it significantly exacerbated gemcitabine-induced ovotoxicities on growing follicles. Taken together, our study demonstrates that the tiered ovotoxicity screening approach starting from eIVFG identifies and prioritizes pharmaceutical compounds of high ovotoxicity concern.

A comprehensive review on time-tested anticancer drug doxorubicin

Doxorubicin or Adriamycin, is one of the most widely used chemotherapeutic drug for treating a myriad of cancers. It induces cell death through multiple intracellular targets: reactive oxygen species generation, DNA-adduct formation, topoisomerase II inhibition, histone eviction, Ca²⁺ and iron hemostasis regulation, and ceramide overproduction. Moreover, doxorubicin-treated dying cells undergo cellular modifications that enable neighboring dendritic cell activation and enhanced presentation of tumor antigen. In addition, doxorubicin also aids in the immune-mediated clearance of tumor cells. However, the development of chemoresistance and cardiotoxicity side effect has undermined its widespread applicability. Several formulations of doxorubicin and co-treatments with inhibitors, miRNAs, natural compounds and other chemotherapeutic drugs have been essential in reducing its dosage-dependent toxicity and combating the development of resistance. Further, more advanced research into the molecular mechanism of chemoresistance development would be vital in improving the overall survivability of clinical patients and in preventing cancer relapse.

Mechanisms of doxorubicin-mediated reproductive toxicity - A review

The anticancer drug doxorubicin has been associated with several adverse side-effects including reproductive toxicity in both genders. The current review has complied the mechanisms of doxorubicin induced reproductive toxicity. The articles cited in the review were searched using Google Scholar, PubMed, Scopus, Science Direct. Doxorubicin treatment has been found to cause a decrease in testicular mass along with histopathological deformities, oligospermia and abnormalities in sperm morphology. Apart from severely affecting the normal physiological role of both Leydig cells and Sertoli cells, doxorubicin also causes chromosome abnormalities and affects DNA methylase enzyme. Testicular lipid metabolism has been found to be negatively affected by doxorubicin treatment resulting in altered profile of sphingolipids glycerophospholipids and neutral lipids. Dysregulation of 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β- hydroxysteroid dehydrogenase (17β-HSD) are strongly linked to testicular exposure to doxorubicin. Further, oxidative stress along with endoplasmic reticulum stress are also found to aggravate the male reproductive functioning in doxorubicin treated conditions. Several antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase (GPx) are downregulated by doxorubicin. It also disturbs the hormones of the hypothalamic-pituitary-gonadal (HPG)-axis including testosterone, luteinizing hormone, follicle stimulating hormone etc. In females, the drug disturbs folliculogenesis and oogenesis leading to failure of ovulation and uterine cycle. In rodent model the drug shortens pro-estrous and estrous phases. It was also found that doxorubicin causes mitochondrial dysfunction in oocytes with impaired calcium signaling along with ER stress. The goal of the present review is to comprehends various pathways due to which doxorubicin treatment promotes toxicity in male and female reproductive system.

FutureTox IV Workshop Summary: Predictive Toxicology for Healthy Children

FutureTox IV, a Society of Toxicology Contemporary Concepts in Toxicology workshop, was held in November 2018. Building upon FutureTox I, II, and III, this conference focused on the latest science and technology for in vitro profiling and in silico modeling as it relates to predictive developmental and reproductive toxicity (DART). Publicly available high-throughput screening data sets are now available for broad in vitro profiling of bioactivities across large inventories of chemicals. Coupling this vast amount of mechanistic data with a deeper understanding of molecular embryology and post-natal development lays the groundwork for using new approach methodologies (NAMs) to evaluate chemical toxicity, drug efficacy, and safety assessment for embryo-fetal development. NAM is a term recently adopted in reference to any technology, methodology, approach, or combination thereof that can be used to provide information on chemical hazard and risk assessment to avoid the use of intact animals (U.S. Environmental Protection Agency [EPA], Strategic plan to promote the development and implementation of alternative test methods within the tsca program, 2018, https://www.epa.gov/sites/production/files/2018-06/documents/epa_alt_strat_plan_6-20-18_clean_final.pdf). There are challenges to implementing NAMs to evaluate chemicals for developmental toxicity compared with adult toxicity. This forum article reviews the 2018 workshop activities, highlighting challenges and opportunities for applying NAMs for adverse pregnancy outcomes (eg, preterm labor, malformations, low birth weight) as well as disorders manifesting postnatally (eg, neurodevelopmental impairment, breast cancer, cardiovascular disease, fertility). DART is an important concern for different regulatory statutes and test guidelines. Leveraging advancements in such approaches and the accompanying efficiencies to detecting potential hazards to human development are the unifying concepts toward implementing NAMs in DART testing. Although use of NAMs for higher level regulatory decision making is still on the horizon, the conference highlighted novel testing platforms and computational models that cover multiple levels of biological organization, with the unique temporal dynamics of embryonic development, and novel approaches for estimating toxicokinetic parameters essential in supporting in vitro to in vivo extrapolation.

Doxorubicin induces cytotoxicity and miR-132 expression in granulosa cells

Doxorubicin (DOX) is one of the most commonly used drugs for the treatment of childhood cancers, including leukemia and lymphomas. Despite the high survival rate, female leukemia survivors are at higher risk of ovarian failure and infertility later in life. Treatment with chemotherapeutic drugs like DOX is associated with damage in ovarian follicles, but the affectation grade of granulosa cells remains unclear. To assess and avoid the possible side-effects of DOX, early biomarkers of ovarian injury and chemotherapy-induced ovarian toxicity should be identified. MicroRNAs (miRNAs) have emerged in recent years as a promising new class of biomarkers for drug-induced tissue toxicity. In this study, the effects of DOX on cell viability, steroidogenesis, and miRNA expression were studied in primary granulosa cells (GCs) and in two cellular models (COV434 and KGN cells). We report that compared to other chemotherapeutic drugs, DOX treatment is more detrimental to granulosa cells as observed by decrease of cell viability. Treatment with DOX changes the expression of the aromatase gene (CYP19A1) and the secretion of 17β-estradiol (E2) in a cell-specific manner. miR-132-3p is dose-dependently increased by DOX in all cellular models. In absence of DOX, miR-132-3p overexpression in COV434 cells has no effect on E2 secretion or CYP19A1 expression. Altogether, these findings contribute to understanding the hormonal disbalance caused by DOX in human ovarian cells and suggest miR-132 as a putative sensor to predict DOX-induced ovarian toxicity.

Ovarian damage from chemotherapy and current approaches to its protection

BACKGROUND

Anti-cancer therapy is often a cause of premature ovarian insufficiency and infertility since the ovarian follicle reserve is extremely sensitive to the effects of chemotherapy and radiotherapy. While oocyte, embryo and ovarian cortex cryopreservation can help some women with cancer-induced infertility achieve pregnancy, the development of effective methods to protect ovarian function during chemotherapy would be a significant advantage.

OBJECTIVE AND RATIONALE

This paper critically discusses the different damaging effects of the most common chemotherapeutic compounds on the ovary, in particular, the ovarian follicles and the molecular pathways that lead to that damage. The mechanisms through which fertility-protective agents might prevent chemotherapy drug-induced follicle loss are then reviewed.

SEARCH METHODS

Articles published in English were searched on PubMed up to March 2019 using the following terms: ovary, fertility preservation, chemotherapy, follicle death, adjuvant therapy, cyclophosphamide, cisplatin, doxorubicin. Inclusion and exclusion criteria were applied to the analysis of the protective agents.

OUTCOMES

Recent studies reveal how chemotherapeutic drugs can affect the different cellular components of the ovary, causing rapid depletion of the ovarian follicular reserve. The three most commonly used drugs, cyclophosphamide, cisplatin and doxorubicin, cause premature ovarian insufficiency by inducing death and/or accelerated activation of primordial follicles and increased atresia of growing follicles. They also cause an increase in damage to blood vessels and the stromal compartment and increment inflammation. In the past 20 years, many compounds have been investigated as potential protective agents to counteract these adverse effects. The interactions of recently described fertility-protective agents with these damage pathways are discussed.

WIDER IMPLICATIONS

Understanding the mechanisms underlying the action of chemotherapy compounds on the various components of the ovary is essential for the development of efficient and targeted pharmacological therapies that could protect and prolong female fertility. While there are increasing preclinical investigations of potential fertility preserving adjuvants, there remains a lack of approaches that are being developed and tested clinically.

A closed vitrification system enables a murine ovarian follicle bank for high-throughput ovotoxicity screening, which identifies endocrine disrupting activity of microcystins

Increasing evidence reveals that a broad spectrum of environmental chemicals and pharmaceutical compounds cause female ovarian toxicity (ovotoxicity). The current gold standard of ovotoxicity testing largely relies on whole laboratory animals, but in vivo models are time consuming, costly, and present animal welfare concerns. We previously demonstrated that the 3D encapsulated in vitro follicle growth (eIVFG) is a robust in vitro model for ovotoxicity testing. However, the follicle preparation process is complex and highly dependent on technical skills. Here, we aimed to use vitrification method to cryopreserve murine immature follicles for a high-content eIVFG, chemical exposure, and ovotoxicity screening. Results indicated that a closed vitrification system combined with optimized vitrification protocols preserved mouse follicle viability and functionality and vitrified follicles exhibited comparable follicle and oocyte reproductive outcomes to freshly harvested follicles during eIVFG, including follicle survival and development, ovarian steroidogenesis, and oocyte maturation and ovulation. Moreover, vitrified follicles consistently responded to ovotoxic chemical, doxorubicin (DOX). We further used vitrified follicles to test the response of microcystins (MCs), an emerging category of environmental contaminants produced by cyanobacteria associated with harmful algal blooms (HABs), and found that different congeners of MCs exhibited differential ovotoxicities. In summary, our study demonstrates that vitrification enables a long-term-storage and ready-to-use ovarian follicle bank for high-throughput ovotoxicity screening, which identifies endocrine disrupting effects of MCs.

Doxorubicin obliterates mouse ovarian reserve through both primordial follicle atresia and overactivation

Ovarian toxicity and infertility are major side effects of cancer therapy in young female cancer patients. We and others have previously demonstrated that doxorubicin (DOX), one of the most widely used chemotherapeutic chemicals, has a dose-dependent toxicity on growing follicles. However, it is not fully understood if the primordial follicles are the direct or indirect target of DOX. Using both prepubertal and young adult female mouse models, we comprehensively investigated the effect of DOX on all developmental stages of follicles, determined the impact of DOX on primordial follicle survival, activation, and development, as well as compared the impact of age on DOX-induced ovarian toxicity. Twenty-one-day-old CD-1 female mice were intraperitoneally injected with PBS or clinically relevant dose of DOX at 10 mg/kg once. Results indicated that DOX primarily damaged granulosa cells in growing follicles and oocytes in primordial follicles and DOX-induced growing follicle apoptosis was associated with the primordial follicle overactivation. Using the 5-day-old female mice with a more uniform primordial follicle population, our data revealed that DOX also directly promoted primordial follicle death and the DNA damage-TAp63α-C-CASP3 pathway was involved in DOX-induced primordial follicle oocyte apoptosis. Compared to 21-day- and 8-week-old female mice that were treated with the same dose of DOX, the 5-day-old mice had the most severe primordial follicle loss as well as the least degree of primordial follicle overactivation. Taken together, these results demonstrate that DOX obliterates mouse ovarian reserve through both primordial follicle atresia and overactivation and the DOX-induced ovarian toxicity is age dependent.

Chemotherapeutic agent doxorubicin alters uterine gene expression in response to estrogen in ovariectomized CD-1 adult mice†

Chemotherapy can potentially impair fertility in premenopausal cancer patients. Female fertility preservation has been mainly focused on the ovarian aspects and benefited greatly from assisted reproductive technologies, such as in vitro fertilization (IVF). The rate-limiting step for the success of IVF is embryo implantation in the uterus. Doxorubicin (DOX) is a widely used chemotherapeutic agent with ovarian toxicity. It remains unknown if the uterus is a direct target of DOX. To circumvent the indirect uterine effect from ovarian toxicity of DOX and to investigate potential long-term impact of DOX on the uterus, young adult ovariectomized CD-1 mice were given an intraperitoneal injection once with PBS or DOX (10 mg/kg, a human relevant chemotherapeutic dose), and 30 days later, each set of mice was randomly assigned into three groups and subcutaneously injected with oil, 17β-estradiol (E2, for 6 h), and progesterone (P4, for 54 h), respectively. Uterine transcriptomic profiles were determined using RNA-seq. Principal component analysis of the uterine transcriptomes revealed four clusters from the six treatment groups: PBS-oil & DOX-oil, PBS-P4 & DOX-P4, PBS-E2, and DOX-E2, indicating that DOX treatment did not affect the overall uterine transcriptomic profiles in the oil and P4-treated mice but altered uterine responses to E2 treatment. DAVID analysis indicated that the top-affected gene cluster was "Glycoprotein". These data demonstrate that DOX can directly target the uterus and has a long-term impact on uterine responses to E2.