DIRAS3 induces autophagy and enhances sensitivity to anti-autophagic therapy in KRAS-driven pancreatic and ovarian carcinomas

Pancreatic ductal adenocarcinoma (PDAC) and low-grade ovarian cancer (LGSOC) are characterized by the prevalence of KRAS oncogene mutations. DIRAS3 is the first endogenous non-RAS protein that heterodimerizes with RAS, disrupts RAS clustering, blocks RAS signaling, and inhibits cancer cell growth. Here, we found that DIRAS3-mediated KRAS inhibition induces ROS-mediated apoptosis in PDAC and LGSOC cells with KRAS mutations, but not in cells with wild-type KRAS, by downregulating NFE2L2/Nrf2 transcription, reducing antioxidants, and inducing oxidative stress. DIRAS3 also induces cytoprotective macroautophagy/autophagy that may protect mutant KRAS cancer cells from oxidative stress, by inhibiting mutant KRAS, activating the STK11/LKB1-PRKAA/AMPK pathway, increasing lysosomal CDKN1B/p27 localization, and inducing autophagic gene expression. Treatment with chloroquine or the novel dimeric chloroquine analog DC661 significantly enhances DIRAS3-mediated inhibition of mutant KRAS tumor cell growth in vitro and in vivo. Taken together, our study demonstrates that DIRAS3 plays a critical role in regulating mutant KRAS-driven oncogenesis in PDAC and LGSOC.Abbreviations: AFR: autophagic flux reporter; ATG: autophagy related; CQ: chloroquine; DCFDA: 2'-7'-dichlorodihydrofluorescein diacetate; DIRAS3: DIRAS family GTPase 3; DOX: doxycycline; KRAS: KRAS proto-oncogene, LGSOC: low-grade serous ovarian cancer; MiT/TFE: microphthalmia family of transcription factors; NAC: N-acetylcysteine; PDAC: pancreatic ductal adenocarcinoma; ROS: reactive oxygen species; TFEB: transcription factor EB.

Visualizing Lipophagy as a New Mechanism of the Synthesis of Sex Steroids in Human Ovary and Testis Using Immunofluorescence Staining Method

Immunofluorescence, a transformative tool in cellular biology, is employed to dissect the intricate mechanisms of cholesterol trafficking in human reproductive tissues. Autophagy, a key player in cellular homeostasis, particularly lipophagy, emerges as a free cholesterol source for steroidogenesis. In this chapter, we describe a comprehensive immunofluorescence staining protocol, with details provided for the precise visualization of subcellular dynamics of mitochondria, lysosomes, and lipid droplets in ex vivo testicular tissue and primary luteal granulosa cell culture models, pivotal components in sex steroid biosynthesis. Here, we detail the culture, treatment, and immunofluorescence protocols, providing a comprehensive guide for researchers. The provided immunofluorescence toolkit serves as a valuable resource for researchers, paving way for advancements in human reproductive health to investigate the intricate interplay between autophagy, lipophagy, and cholesterol trafficking.

Evaluation of the test-retest and inter-mode comparability of the Impact of Vision Impairment questionnaire in people with chronic eye diseases

PURPOSE

The main objective of this study is to assess the test-retest and inter-administration mode reliability of the Impact of Vision Impairment profile (IVI), a common patient-reported outcome measure (PROM) for people with chronic eye diseases.

METHODS

The IVI was administered to adult patients with stable, chronic eye diseases two to four times per participant (average intervals between administrations 12 to 20 days; maximum two phone interviews, paper administration, electronic administration) by two trained interviewers. Rasch models were fit to the data. Intra-class correlation coefficients (ICCs), mean differences and Cronbach's alpha between test-retest administrations (two phone interviews) and inter-mode comparisons were calculated.

RESULTS

Two hundred-sixteen patients (mean age 67 ± 12 years, 40% male) were included in the study. The IVI met all psychometric requirements of the Rasch model, and the division into the domains of functional items (IVI_F) and emotional items (IVI_E) corresponded to the German validation study. ICCs (all for IVI_F and IVI_E, respectively) for the retest administrations were 0.938 and 0.912, and 0.853 and 0.893 for inter-mode comparisons phone/paper, 0.939 and 0.930 for phone/electronic, and 0.937 and 0.920 for paper/electronic (all p < 0.01). Mean differences (all for IVI_F and IVI_E, respectively) for the retest administrations were 2.8% and 0.7% and ranged from 2.0% to 6.2% and from 0.4 % to 4.9% between administration modes. Cronbach's alpha ranged from 0.886 to 0.944 for retest and inter-mode comparisons.

CONCLUSION

Due to the high test-retest reliability and the almost equally high comparability of different modes of administration of the IVI, the study endorses its use as a robust PROM to capture vision-related quality of life. Our results further support the use of the IVI as an endpoint in clinical trials and may simplify implementing it in both clinical trials or real-world evidence generation by offering multiple administration modes with high reliability.

Membrane anchoring of the DIRAS3 N-terminal extension permits tumor suppressor function

DIRAS3 is an imprinted tumor suppressor gene encoding a GTPase that has a distinctive N-terminal extension (NTE) not found in other RAS proteins. This NTE and the prenylated C-terminus are required for DIRAS3-mediated inhibition of RAS/MAP signaling and PI3K activity at the plasma membrane. In this study, we applied biochemical, biophysical, and computational methods to characterize the structure and function of the NTE. The NTE peptide recognizes phosphoinositides PI(3,4,5)P3 and PI(4,5)P2 with rapid kinetics and strong affinity. Lipid binding induces NTE structural change from disorder to amphipathic helix. Mass spectrometry identified N-myristoylation of DIRAS3. All-atom molecular dynamic simulations predict DIRAS3 could adhere to the membrane through both termini, suggesting the NTE is involved in targeting and stabilizing DIRAS3 on the membrane by double anchoring. Overall, our results are consistent with DIRAS3's function as a tumor suppressor, whereby the membrane-bound DIRAS3 can effectively target PI3K and KRAS at the membrane.

Autophagy regulates sex steroid hormone synthesis through lysosomal degradation of lipid droplets in human ovary and testis

Autophagy is an evolutionarily conserved process that aims to maintain the energy homeostasis of the cell by recycling long-lived proteins and organelles. Previous studies documented the role of autophagy in sex steroid hormone biosynthesis in different animal models and human testis. Here we demonstrate in this study that sex steroid hormones estrogen and progesterone are produced through the same autophagy-mediated mechanism in the human ovary in addition to the human testis. In brief, pharmacological inhibition and genetic interruption of autophagy through silencing of autophagy genes (Beclin1 and ATG5) via siRNA and shRNA technologies significantly reduced basal and gonadotropin-stimulated estradiol (E₂), progesterone (P₄) and testosterone (T) production in the ex vivo explant tissue culture of ovary and testis and primary and immortalized granulosa cells. Consistent with the findings of the previous works, we observed that lipophagy, a special form of autophagy, mediates the association of the lipid droplets (LD)s with lysosome to deliver the lipid cargo within the LDs to lysosomes for degradation in order to release free cholesterol required for steroid synthesis. Gonadotropin hormones are likely to augment the production of sex steroid hormones by upregulating the expression of autophagy genes, accelerating autophagic flux and promoting the association of LDs with autophagosome and lysosome. Moreover, we detected some aberrations at different steps of lipophagy-mediated P₄ production in the luteinized GCs of women with defective ovarian luteal function. The progression of autophagy and the fusion of the LDs with lysosome are markedly defective, along with reduced P₄ production in these patients. Our data, together with the findings of the previous works, may have significant clinical implications by opening a new avenue in understanding and treatment of a wide range of diseases, from reproductive disorders to sex steroid-producing neoplasms, sex steroid-dependent malignancies (breast, endometrium, prostate) and benign disorders (endometriosis).

Preclinical investigations of the efficacy of the glutaminase inhibitor CB-839 alone and in combinations in chronic lymphocytic leukemia

Introduction

Chronic lymphocytic leukemia (CLL) cells are metabolically flexible and adapt to modern anticancer treatments. Bruton tyrosine kinase (BTK) and B-cell lymphoma-2 (BCL-2) inhibitors have been widely used to treat CLL, but CLL cells become resistant to these treatments over time. CB-839 is a small-molecule glutaminase-1 (GLS-1) inhibitor that impairs glutamine use, disrupts downstream energy metabolism, and impedes the elimination of reactive oxygen species.

Methods

To investigate the in vitro effects of CB-839 on CLL cells, we tested CB-839 alone and in combination with ibrutinib, venetoclax, or AZD-5991 on the HG-3 and MEC-1 CLL cell lines and on primary CLL lymphocytes.

Results

We found that CB-839 caused dose-dependent decreases in GLS-1 activity and glutathione synthesis. CB-839-treated cells also showed increased mitochondrial superoxide metabolism and impaired energy metabolism, which were reflected in decreases in the oxygen consumption rate and depletion of the adenosine triphosphate pool and led to the inhibition of cell proliferation. In the cell lines, CB-839 combined with venetoclax or AZD-5991, but not with ibrutinib, demonstrated synergism with an increased apoptosis rate and cell proliferation inhibition. In the primary lymphocytes, no significant effects of CB-839 alone or in combination with venetoclax, ibrutinib, or AZD-5991 were observed.

Discussion

Our findings suggest that CB-839 has limited efficacy in CLL treatment and shows limited synergy in combination with widely used CLL drugs.

Breast cancer treatment and ovarian function

The aim of this study was to provide an update on ovarian function and the mechanisms of gonadal damage after exposure to chemotherapy in breast cancer survivors. The alkylating agents are toxic to both primordial and growing follicles. However, anti-metabolite drugs are more likely to destroy preantral and antral follicles. Younger patients are more likely to have a higher ovarian reserve, and therefore, more likely to retain some residual ovarian function after exposure to gonadotoxic regimens. However, there can be significant variability in ovarian reserve among patients of the same age. Furthermore, patients with critically diminished ovarian reserve may continue to menstruate regularly. Therefore age and menstrual status are not reliable indicators of good ovarian reserve and might give a false sense of security and result in an adverse outcome if the patient is consulted without considering more reliable quantitative markers of ovarian reserve (antral follicle count and anti-Müllerian hormone) and fertility preservation is not pursued. In contrast to well-documented ovarian toxicity of older chemotherapy regimens, data for newer taxane-containing protocols have only accumulated in the last decade and data are still very limited regarding the impact of targeted therapies on ovarian function.

IVF characteristics and the molecular luteal features of random start IVF cycles are not different from conventional cycles in cancer patients

STUDY QUESTION

Are the IVF parameters and the steroidogenic luteal characteristics of random-start IVF cycles different from conventional cycles in cancer patients?

SUMMARY ANSWER

No; controlled ovarian stimulation cycles randomly started at late follicular phase (LFP) and luteal phase (LP) are totally comparable to those conventional IVF cycles started at early follicular phase (EFP) in terms of the expression of the enzymes involved in cholesterol utilization and steroid hormone biosynthesis pathways, gonadotropin receptor expression and, estradiol (E2) and progesterone (P4) production in addition to the similarities in ovarian response to gonadotropin stimulation, oocyte yield, fertilization rate and embryo development competency in cancer patients.

WHAT IS KNOWN ALREADY

Random start ovarian stimulation protocols are commonly employed for oocyte and embryo freezing for fertility preservation in cancer patients with time constraints who do not have sufficient time to undergo ovarian stimulation initiated conventionally at EFP of the next cycle. No data is available regarding the molecular steroidogenic features of these cycles analyzed together with the clinical IVF characteristics in cancer patients. We aimed to address this question in this study to help understand how similar the random start cycles are to the conventional start ones.

STUDY DESIGN, SIZE, DURATION

A clinical translational research study conducted in 62 cancer patients undergoing IVF for fertility preservation between the years 2017 and 2022.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sixty-two patients who were diagnosed with different types of cancer and underwent ovarian stimulation for oocyte (n = 41) and embryo (n = 21) cryopreservation using GnRH antagonist protocol and human menopausal gonadotropins before receiving cancer treatment/surgery were enrolled in the study. For patients with breast cancer and endometrial cancer the aromatase inhibitor letrozole was used with gonadotropin stimulation. Ovarian stimulation was initiated conventionally at EFP in 22 patients and served as control while it was started at LFP in 20, and mid-LP in the other 20 patients. The luteinized granulosa cells (GCs) were recovered from follicular aspirates during oocyte retrieval procedure and used for the experiments separately for each individual patient. The expression of the enzymes involved in sex steroid biosynthesis (StAR, 3β-HSD, Aromatase) and cholesterol synthesis (3-hydroxy 3-methylglutaryl Co-A reductase (HMG-Co-A reductase)), utilization (hormone sensitive lipase (HSL)), and storage (Acetyl-Coenzyme A acetyltransferase 1 (ACAT-1)), and gonadotropin receptor expression status were analyzed using immunoblotting and RT-PCR methods. Laser confocal immunofluorescence imaging was applied to analyze and compare the expression patterns of the steroidogenic enzymes and their relation with mitochondria. In vitro E2 and P4 production by the cells were compared among the groups.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline demographic and IVF characteristics of the patients undergoing the conventional start and random start IVF cycles were similar. Duration of gonadotropin stimulation was significantly longer in LFP and LP start cycles in comparison to the conventional ones. Ovarian response to gonadotropin stimulation, mature and total oocyte yield, fertilization and Day 5 blastulation rates of the embryos were comparable between the conventional versus random start cycles. When the luteal GCs of these random start cycles were analyzed we could not find any gross differences between these cycles in terms of the viability index and gross light microscopic morphologic features. More detailed analysis of the molecular luteal characteristics of the cells using RT-PCR, immunoblotting methods revealed that the expression profiles of the gonadotropin receptors, and the enzymes involved in sex steroid biosynthesis and cholesterol synthesis/utilization, and the steroidogenic activity of the luteal GCs of the random start cycles are almost identical to those of the conventional start cycles. Confocal image analysis demonstrated similar patterns in the signal expression profiles of the steroidogenic enzymes and their co-localization within mitochondria.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Caution should be exercised when interpreting our data and counseling cancer patients seeking fertility preservation because it is still unclear if previous exposure to cancer drugs, different ovarian pathologies or infertility etiologies, previous ovarian surgery and/or any other underlying diseases that are concomitantly present with cancer may cause a difference between conventional and random start stimulation protocols in terms of IVF parameters, luteal function and reproductive outcome. Relatively low number of patients in each stimulation protocol and pooling of luteal GCs for each patient rather than individual analysis of each follicle and oocyte are additional limitations of our study.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide reassurance that random start protocol offers cancer patients an equally good prospect of fertility preservation as conventional IVF.

STUDY FUNDING/COMPETING INTEREST(S)

Funded by the School of Medicine, the Graduate School of Health Sciences of Koc University and Koç University Research Center for Translational Medicine (KUTTAM), equally funded by the Republic of Turkey Ministry of Development Research Infrastructure Support Program. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Interviewer Administration Corresponds to Self-Administration of the Vision Impairment in Low Luminance (VILL) Questionnaire

Purpose

To quantify the impact of the mode of administration (MOA) on scores of the Vision Impairment in Low Luminance (VILL) questionnaire.

Methods

The VILL questionnaire was implemented using different MOAs (paper, interview, electronic), in addition to a demographical survey of adult participants recruited at an outpatient eye clinic, with the initial MOA being either paper or interview. Polytomous Rasch models were used to generate person measure scores for the three subscales of the VILL questionnaire (reading, VILL_R; mobility, VILL_M; and emotional, VILL_E). Measures of agreement among the different MOAs were calculated (self-administered paper/interview, self-administered paper/self-administered electronic, and interview/self-administered electronic). An age-matched analysis was performed to control for the impact of the initial MOA, administration interval, visual acuity, and self-reported hearing difficulties.

Results

We included 309 participants (mean age, 63 ± 14 years; 61% female). Intra-class correlation coefficients were 0.930, 0.919, and 0.799 for paper versus interview assessment; 0.951, 0.959, and 0.916 for paper versus electronic; and 0.967, 0.955, and 0.907 for interview versus electronic assessment (VILL_R, VILL_M, and VILL_E, respectively). Mean differences were 0.35, 0.41, and 1.74 logits; 0.32, 0.18, and 0.68 logits; and 0.08, 0.22, and 0.63 logits, respectively. None of the mentioned factors significantly affected the results (corrected P ≥ 0.11).

Conclusions

Paper, interview, and electronic MOAs of the VILL can be considered equivalent. Reporting across the main MOAs of self-administration (paper) and interviewer-administration was unaffected by better eye visual acuity and self-reported hearing difficulties.

Translational Relevance

The results support use of the VILL questionnaire with flexible modes of administration.

DIRAS3: An Imprinted Tumor Suppressor Gene that Regulates RAS and PI3K-driven Cancer Growth, Motility, Autophagy, and Tumor Dormancy

DIRAS3 is an imprinted tumor suppressor gene that encodes a 26 kDa GTPase with 60% amino acid homology to RAS, but with a distinctive 34 amino acid N-terminal extension required to block RAS function. DIRAS3 is maternally imprinted and expressed only from the paternal allele in normal cells. Loss of expression can occur in a single "hit" through multiple mechanisms. Downregulation of DIRAS3 occurs in cancers of the ovary, breast, lung, prostate, colon, brain, and thyroid. Reexpression of DIRAS3 inhibits signaling through PI3 kinase/AKT, JAK/STAT, and RAS/MAPK, blocking malignant transformation, inhibiting cancer cell growth and motility, and preventing angiogenesis. DIRAS3 is a unique endogenous RAS inhibitor that binds directly to RAS, disrupting RAS dimers and clusters, and preventing RAS-induced transformation. DIRAS3 is essential for autophagy and triggers this process through multiple mechanisms. Reexpression of DIRAS3 induces dormancy in a nu/nu mouse xenograft model of ovarian cancer, inhibiting cancer cell growth and angiogenesis. DIRAS3-mediated induction of autophagy facilitates the survival of dormant cancer cells in a nutrient-poor environment. DIRAS3 expression in dormant, drug-resistant autophagic cancer cells can serve as a biomarker and as a target for novel therapy to eliminate the residual disease that remains after conventional therapy.

Abstract 83: Structural and biochemical properties of DIRAS3 N-terminal extension that permit its function as a tumor suppressor of oncogenic K-RAS

DIRAS3 is an imprinted tumor suppressor gene that encodes a small GTPase of the RAS superfamily. In contrast to oncogenic RAS proteins, DIRAS3 inhibits tumor growth and migration, while inducing autophagy and tumor dormancy. DIRAS3 inhibits PI3K/AKT/mTOR and RAS/MAP signaling. DIRAS3 inhibits oncogenic, mutant K-RAS signaling by binding directly to mutant K-RAS and disrupting K-RAS dimers and clusters on the inner leaflet of the plasma membrane. DIRAS3 bears 60% amino acid homology to K-RAS, differing by the addition of a distinctive 34 amino acid N-terminal extension (NTE). Both the NTE and an intact C-terminal CAAX box are required for the suppressor function of DIRAS3 in breast and ovarian cancers. While prenylation of the CAAX box is thought to facilitate binding of DIRAS3 to the inner leaflet of the cell surface membrane through a lipid tail, how the NTE influences membrane association is not well understood. In this study, we apply biochemical and biophysical methods to investigate NTE structure and ligand binding activities using synthetic wild type and mutated NTE peptides. Using a lipid overlay assay and surface plasmon resonance (SPR) analysis, we found that the DIRAS3 NTE has affinity for phosphatidylinositol phosphate lipids, especially PI(3,4,5)P3 and PI(4,5)P2. SPR demonstrated a strong interaction between NTE and PIP3 (dissociation constant of ~36 nM) with a cooperative self-association of NTE on the PIP3 sensor surface. Isothermal titration calorimetry revealed that NTE-PIP3 binding is complex, involving multiple sites and cooperativity, that appeared dominated by entropic interaction. Structural analysis of NTE mutants with circular dichroism spectroscopy indicated that the NTE is mainly unstructured in solution, however PIP3-binding induces a conformational rearrangement of the NTE that involves a hydrophobic surface of an amphipathic helix region. Furthermore, mass spectrometry identified N-myrisoylation of glycine in the NTE region of DIRAS3, which is unique among RAS family proteins. In addition, SPR screening of a K-RAS peptide library and kinetic analysis of the interaction between DIRAS3 NTE and K-RAS revealed engagement of the NTE with the effector lobe of K-RAS and a conformational change in the NTE•K-RAS complex. Together, our study suggests that DIRAS3 NTE may play an important role in inhibiting K-RAS and AKT signaling by facilitating specific protein-lipid interactions at the plasma membrane. The affinity of the NTE for PIP3 could contribute to the known regulation of PI3K by DIRAS3. Moreover, functional DIRAS3 may be tethered to the inner leaflet of the cell membrane at two points, by prenylation of the CAAX box at the C-terminal and by myristoylation of the NTE.

Citation Format: Xiaowen Liang, Kwangkook Lee, Sung Y. Jung, Gamze Bildik, Weiqun Mao, Joshua P. Gray, Steven W. Millward, Zhen Lu, Robert C. Bast. Structural and biochemical properties of DIRAS3 N-terminal extension that permit its function as a tumor suppressor of oncogenic K-RAS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 83.

Abstract 1999: DIRAS3 induces autophagy and enhances sensitivity to anti-autophagic therapy in KRAS-driven pancreatic and ovarian carcinomas

Mutant KRAS drives human cancers from several sites, including pancreatic ductal adenocarcinoma (PDAC) and low-grade serous ovarian cancer (LGSOC). Despite the prevalence of RAS mutations in many different cancers, effective RAS-targeted treatment remains a challenge. More than 90% of PDACs are driven by mutant KRAS. Genetic suppression of KRAS or pharmacological inhibition of its effectors, ERK/MAPK, enhances the reliance of PDAC on autophagy that can provide a target for treatment. DIRAS3 (ARHI) is an imprinted tumor suppressor gene that is downregulated in pancreatic and ovarian cancers. When re-expressed, DIRAS3 blocks cancer cell proliferation, inhibits motility, and induces autophagy by multiple mechanisms. DIRAS3 inhibits RAS signaling by heterodimerizing directly with KRAS, inhibiting homodimerization of KRAS and disrupting KRAS nanoclustering. In this study, we tested whether inhibiting RAS signaling by re-expressing DIRAS3 would sensitize RAS-driven cancers to autophagy inhibition. Re-expression of DIRAS3 decreased phosphorylation of Erk1/2 (pThr202/Tyr204), inhibiting the RAF-MEK-ERK signaling pathway. Re-expression of DIRAS3 induced autophagic flux indicated by an increased LC3-mCherry/eGFP ratio. DIRAS3 re-expression decreased LKB1 (pS428) and increased AMPK (pT172) and ULK1 (pS555), suggesting that induction of autophagic flux may be partly mediated by the activation of the energy-sensing LKB1-AMPK1-ULK1 axis following suppression of upstream RAF-MEK-ERK signaling. In addition, we confirmed that DIRAS3-induced autophagy enhanced the sensitivity of cancer cells to autophagy inhibition as evidenced by decreasing the IC50 of both chloroquine (CQ) and di-chloroquine (DC661) in human KRAS-driven PDAC and LGSOC. The greater potency of DC661, blocking autophagy with an IC50 in the low nanomolar range, should prove more effective for combinatorial therapies in vivo.

Citation Format: Gamze Bildik, Joshua P. Gray, Weiqun Mao, Robert C. Bast, Zhen Lu. DIRAS3 induces autophagy and enhances sensitivity to anti-autophagic therapy in KRAS-driven pancreatic and ovarian carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1999.

In-vitro AMH production of ovarian tissue samples in culture correlates with their primordial follicle pool

OBJECTIVE

We aimed to investigate if there is a correlation between in-vitro AMH production and primordial follicle reserve of the ovarian cortical samples in culture.

METHODS

Seven patients undergoing laparoscopic excision of ovarian dermoid cysts were included in the study. 0.5 × 0.5 cm of ovarian cortical samples embedded within the cyst wall were removed and cultured for one day. Then, the cultured cortical pieces were fixed, paraffin-embedded and serially sectioned for histormorphometric analysis. AMH and estradiol (E₂) production of the samples after one-day culture period were measured in the spent culture media. Primordial follicle density was expressed as the number of primordial follicles per mm². Pearson correlation and linear regression analyses were applied.

RESULTS

The mean age of the patients was 29.2 ± 6.8 (ranging from 18 to 36). There was a negative correlation between age and PF density (r=-0.92, %95CI: -0.99 to -0.76, p < 0.001). In-vitro AMH level of the cortical samples was significantly associated with age (R² = 0.67, p = 0.023), primordial follicle density (R² = 0.71, p = 0.015). There was a borderline significance between in-vitro levels of AMH and E₂ level (R² = 0.55, p = 0.058). A similar comparison could not be made for secondary follicles (preantral and small antral follicles) because of their rarity in the histological sections analyzed.

CONCLUSIONS

This histomorphometric study provides evidence that in-vitro AMH production of the ovarian cortical samples reflects primordial follicle pool of the samples.

Terminal differentiation of human granulosa cells as luteinization is reversed by activin-A through silencing of Jnk pathway

Molecular mechanisms underlying luteinization (terminal differentiation of granulosa and theca cells after ovulation) and luteolysis (demise of corpus luteum) are poorly understood in human ovary. Here we report that activin-A, after binding to its cognate receptors induces a functional luteolytic state and reverses luteinization phenotype by downregulating the expression of the steroidogenic enzymes, LH receptor and VEGF and reducing estradiol (E2) progesterone (P4) production and upregulating FSH receptor and cyclin D1 expression in human primary luteinized granulosa cells. Further, this action of activin-A involves downregulation of JNK signaling pathway and is opposite to that of human chorionic gonadotropin (hCG), which acts as a luteotropic hormone and improves luteal function through the activation of JNK pathway in the same cell type. Reversal of luteinization phenotype in luteal granulosa cells by activin-A potentially makes this hormone an attractive candidate for use under certain clinical situations, where induction of luteolysis and rapid reduction of endogenous sex steroid levels are beneficial such as ovarian hyperstimulation syndrome (OHSS), in which the ovaries hyper-respond to gonadotropin stimulation by producing too many growing follicles along with development of ascites, pleural effusion, and hemo-concentrations as a result of increased vascular permeability and leakage of intravascular volume into third spaces. Our work unveils a previously undefined role for activin-A and JNK signaling pathway in human corpus luteum biology, that might have a direct clinical impact in assisted reproductive technologies.

Luteal granulosa cells from natural cycles are more capable of maintaining their viability, steroidogenic activity and LH receptor expression than those of stimulated IVF cycles

STUDY QUESTION

Are there any differences in the molecular characteristics of the luteal granulosa cells (GC) obtained from stimulated versus non-stimulated (natural) IVF cycles that may help explain the defective luteal phase in the former?

SUMMARY ANSWER

Luteal GC of stimulated IVF cycles, particularly those of agonist-triggered antagonist cycles, are less viable ex vivo, express LH receptor and anti-apoptotic genes at lower levels, undergo apoptosis earlier and fail to maintain their estradiol (E2) and progesterone (P4) production in comparison to natural cycle GC.

WHAT IS KNOWN ALREADY

Luteal function is defective in stimulated IVF cycles, which necessitates P4 and/or hCG administration (known as luteal phase support) in order to improve clinical pregnancy rates and prevent miscarriage. The luteal phase becomes shorter and menstruation begins earlier than a natural cycle if a pregnancy cannot be achieved, indicative of early demise of corpus luteum (premature luteolysis). Supra-physiological levels of steroids produced by multiple corpora luteae in the stimulated IVF cycles are believed to inhibit LH release directly via negative feedback actions on the hypothalamic-pituitary-ovarian axis resulting in low circulating levels of LH and a defective luteal phase. We hypothesized that some defects in the viability and steroidogenic activity of the luteal GC of the stimulated IVF cycles might contribute to this defective luteal phase in comparison to natural cycle GC. This issue has not been studied in human before.

STUDY DESIGN, SIZE, DURATION

A comparative translational research study of ex vivo and in vitro models of luteal GC recovered from IVF patients undergoing natural versus stimulated IVF cycles was carried out. Luteinized GC were obtained from 154 IVF patients undergoing either natural (n = 22) or stimulated IVF cycles with recombinant FSH and GnRH agonist (long) (n = 44), or antagonist protocol triggered conventionally either with recombinant hCG (n = 46) or with a GnRH agonist (n = 42). GC were maintained in vitro for up to 6 days.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cellular viability (YO-PRO-1 staining), the expression of the steroidogenic enzymes, pro-apoptotic genes [Bcl-2-associated death promoter (BAD), Bcl-2-associated X protein (BAX) and Caspase-3 (CASP3)], anti-apoptotic genes [RAC-alpha serine/threonine-protein kinase (AKT-1) and Bcl-2-like protein 2 (BCL2-L2)], LH receptor, vascular endothelial growth factor (VEGF) (using real-time quantitative PCR at mRNA level and western blot immunoprecipitation assay at protein level) and in vitro E2 and P4 production (electrochemiluminescence immunoassay) were compared in GC among the groups.

MAIN RESULTS AND THE ROLE OF CHANCE

Natural cycle GC were significantly more viable ex vivo (88%) compared to their counterparts of the stimulated IVF cycles (66, 64 and 37% for agonist and antagonist cycles triggered with hCG and GnRH agonist respectively, P < 0.01). They were also more capable of maintaining their vitality in culture compared to their counterparts from the stimulated IVF cycles: at the end of the 6-day culture period, 74% of the cells were still viable whereas only 48, 43 and 22% of the cells from the agonist and antagonist cycles triggered with hCG and agonist respectively, were viable (P < 0.01). The mRNA expression of anti-apoptotic genes (AKT-1 and BCL2-L2) was significantly lower, while that of pro-apoptotic genes (BAD, BAX and CASP3) was significantly higher in the stimulated cycles, particularly in the agonist-triggered antagonist cycles, compared to natural cycle GC (P < 0.01 for long protocol and antagonist hCG trigger, P < 0.001 for agonist trigger). The expression of steroidogenic enzymes (stAR, SCC, 3β-HSD and aromatase) and VEGF was significantly higher in the agonist and hCG-triggered antagonist cycles compared to natural cycle GC. Therefore, in vitro E2 and P4 production in cells from the stimulated IVF cycles was significantly higher than their counterparts obtained from the natural cycles in the first 2 days of culture. However, after Day 2, their viability and hormone production began to decline very rapidly with the most drastic decrease being observed in the agonist-triggered cycles. By contrast, natural cycle GC maintained their viability and produced E2 and P4 in increasing amounts in culture up to 6 days. In vitro P production and the mRNA and protein expression of LH receptor, VEGF and 3β-HSD were most defective in the agonist-triggered antagonist cycles compared to natural and agonist and hCG-triggered antagonist cycles. In vitro hCG treatment of a subset of the cells from the agonist-triggered cycles improved their viability, increased E2 and P4 production in vitro and up-regulated the mRNA expression of anti-apoptotic gene BCL-L2 together with steroidogenic enzymes stAR, SCC, 3B-HSD, LH receptor and VEGF.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

The limitations include analysis of luteinized GC only might not reflect the in vivo mechanisms involved in survival and function of the whole corpus luteum; GC recovered during oocyte retrieval belong to a very early stage of the luteal phase and might not be representative; effects of ovulation triggered with hCG may not equate to the endogenous LH trigger; the clinical characteristics of the patients may vary among the different groups and it was not possible to correlate stimulation-related molecular alterations in luteal GC with the clinical outcome, as no oocytes have been utilized yet. Therefore, our findings do not conclusively rule out the possibility that some other mechanisms in vivo may also account for defective luteal function observed in stimulated IVF cycles.

WIDER IMPLICATIONS OF THE FINDINGS

Ovarian stimulation is associated with significant alterations in the viability and steroidogenic activity of luteal GC depending on the stimulation protocol and mode of ovulation trigger. Reduced survival and down-regulated expression of 3B-HSD, LH receptor and VEGF leading to compromised steroid production in stimulated cycles, and particularly in the agonist-triggered cycles, may at least in part help explain why the luteal phase is defective and requires exogenous support in these cycles.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the School of Medicine, the Graduate School of Health Sciences of Koc University and Koç University Research Center for Translational Medicine (KUTTAM), equally funded by the Republic of Turkey Ministry of Development Research Infrastructure Support Program. All authors declare no conflict of interest.

hCG Improves Luteal Function and Promotes Progesterone Output through the Activation of JNK Pathway in the Luteal Granulosa Cells of the Stimulated IVF Cycles†

Human chorionic gonadotropin (hCG) is a luteotropic hormone that promotes the survival and steroidogenic activity of corpus luteum (CL) by acting through luteinizing hormone receptors (LHRs) expressed on luteinized theca and granulosa cells (GCs). Therefore, it is used to support luteal phase in in vitro fertilization (IVF) cycles to improve clinical pregnancy rates and prevent miscarriage. However, the molecular mechanism underlying this action of hCG is not well characterized. To address this question, we designed an in vitro translational research study on the luteal GCs obtained from 58 IVF patients. hCG treatment at different concentrations and time points activated c-Jun N-terminal kinase (JNK) pathway and significantly increased its endogenous kinase activity along with upregulated expression of steroidogenic enzymes (steroidogenic acute regulatory protein (stAR), 3β-Hydroxysteroid dehydrogenase (3β-HSD)) in a dose-dependent manner in the luteal GCs. As a result, in vitro P production of the cells was significantly enhanced after hCG. When JNK pathway was inhibited pharmacologically or knocked-down with small interfering RNA luteal function was compromised, P4 production was declined along with the expression of stAR and 3β-HSD in the cells. Further, hCG treatment after JNK inhibition failed to correct the luteal defect and promote P4 output. Similar to hCG, luteinizing hormone (LH) treatment improved luteal function as well and this action of LH was associated with JNK activation in the luteal GCs. These findings could be important from the perspective of CL biology and luteal phase in human because we for the first time identify a critical role for JNK signaling pathway downstream LHR activation by hCG/LH in luteal GCs.

SUMMARY SENTENCE

JNK signaling pathway plays a central role in the upregulated expression of the steroidogenic enzymes StAR and 3b-HSD and augmented progesterone production by hCG/LH in human luteal granulosa cells.

The mammalian target of rapamycin protein expression in human granulosa cell tumors

Objective:

To investigate the role of mammalian target of rapamycin (mTOR) in human granulosa cell ovarian tumors and the therapeutic effect of rapamycin in COV434 mitotic granulosa cell lines.

Material and Methods:

A retrospective evaluation of the medical records and pathologic sections of patients with granulosa cell ovarian carcinoma was performed. mTOR and p-mTOR expression was immunohistochemically investigated. A COV434 cell culture were treated with 0.5, 1, 2, and 5 μM rapamycin. Real-time growth curve analysis via xCELLigence system and apoptotic cell analysis via YO-PRO™-1 Iodide were performed to assess the therapeutic effect of rapamycin on cancer cells.

Results:

A total of twenty patients were evaluated. mTOR staining was detected in 18 (90%) patients. Mild, moderate, intense, and very intense staining was observed in three (15%), eight (40%), six (30%), and one (5%) sample, respectively. The mean mTOR staining ratio was 59±41%. P-mTOR staining was observed in two (10%) patients. One (5%) patient had 5% staining, and one (5%) patient had 100% staining for p-mTOR. Both of the latter patients had very intense staining. Rapamycin caused a dose-dependent growth arrest and induced apoptosis in COV434 mitotic granulosa cells. The real-time growth curves of the cells treated with these drugs were distinguished by a marked reduced slope after exposure for several hours, indicating a rapid onset of apoptosis. Live/dead cell analysis with YO-PRO-1 staining showed that rapamycin induced apoptosis in 24% of the cells when used at 1 μM concentration, whereas the rate increased to 61% and 72% when the cells were treated with 2 μM and 5 μM rapamycin, respectively.

Conclusion:

mTOR expression is observed in various degrees in 90%, and p-mTOR expression is observed in only 10% of patients with granulosa cell ovarian carcinoma. Rapamycin caused a dose-dependent growth arrest and apoptosis in COV434 mitotic granulosa cells.

C-Abl is not actıvated in DNA damage-induced and Tap63-mediated oocyte apoptosıs in human ovary

There is a controversy in literature as to whether c-Abl is crucial for the induction of TAp63-mediated apoptosis and whether that inhibition of c-Abl with imatinib, which was designed to inhibit the oncogenic kinase BCR-ABL and c-kit, protects oocytes from chemotherapy-induced apoptosis in mice. No human data are available on this issue. We therefore aimed to explore whether genomic damage induced by chemotherapy drug cisplatin activates c-Abl along with TAp63 and the inhibition of c-Abl with imatinib prevents cisplatin-induced oocyte death and follicle loss in human ovary. Exposure to cisplatin induced DNA damage, activated TAp63 and SAPK/JNK pathway, and triggered apoptosis in the oocytes and granulosa cells. However, TAp63 activation after cisplatin was not associated with any increase in the expression of c-Abl. Imatinib did not prevent cisplatin-induced apoptosis of the granulosa cells or oocytes. Moreover, treatment with this drug resulted in the formation of bizarre shaped follicles lacking oocytes and increased follicular atresia by inducing apoptosis of granulosa cells and oocytes. Similar toxic effects were observed when ovarian tissue samples were incubated with a c-kit antagonist drug anti-CD117, but not with another c-Abl tyrosine kinase inhibitor GNF-2, which lacks an inhibitory action on c-kit. Intraperitoneal administration of imatinib to the xenografted animals produced similar histomorphological abnormalities in the follicles in human ovarian grafts and did not prevent cisplatin-induced follicle loss when co-administered with cisplatin. Our findings provide, for the first time, a molecular evidence for ovarian toxicity of this drug in human. Furthermore, this study together with two previous case reports of a severely compromised ovarian response to gonadotropin stimulation and premature ovarian failure in patients, while receiving imatinib, further heighten the concerns about its potential gonadotoxicity on human ovary and urge caution in its use in young female patients.

Sphingosine-1-phosphate reduces atresia of primordial follicles occurring during slow-freezing and thawing of human ovarian cortical strips

We aimed in this study to explore if sphingosine-1-phosphate (S1P) reduces apoptosis of primordial follicles during cryopreservation of human ovarian cortical samples. Ovarian cortical tissue fragments obtained from young patients who underwent laparoscopic excision of benign ovarian cysts were used for the experiments. The samples were slow-frozen and thawed with and without S1P at 200 and 400 μM, cultured for 1 day, and then were fixed and processed for both histomorphological assessment and detection of apoptosis with immunohistochemistry using apoptosis marker cleaved caspase-3. Follicle counts were expressed as the mean number of follicles per mm² . The mean number of primordial follicles and in vitro estradiol (E2) and anti-mullerian hormone (AMH) production of the slow-frozen and thawed samples were significantly reduced compared with fresh unfrozen samples. S1P treatment at 400 μM but not 200 μM concentration resulted in a significant increase in the number of surviving primordial follicles and in vitro E2 and AMH productions of the samples compared with their counterparts slow-frozen without S1P. We found that that there was a significant decrease in the number of primordial follicles with their oocytes stained positive for cleaved caspase-3 in the slow-frozen samples S1P 400 μM in comparison with the samples slow-frozen without S1P. These results suggest that S1P may ameliorate follicle atresia occurring in human ovarian cortical samples during cryopreservation.

Endogenous c-Jun N-terminal kinase (JNK) activity marks the boundary between normal and malignant granulosa cells

Granulosa cell tumor of the ovary (GCT) is a very rare tumor, accounting for only 2% of all ovarian tumors. It originates from sex cords in the ovary and can be divided into adult (95%) and juvenile (5%) types based on histologic findings. To date, no clear etiologic process has been identified other than a missense point mutation in the FOXL2 gene. Our previous works showed that c-Jun N-terminal kinase (JNK) pathway plays critical role in cell cycle progression and mitosis of normal and immortalized granulosa cells and follicle growth in rodent ovaries. These findings led us to investigate the role of JNK pathway in the granulosa cell tumor of the ovary. We used two different GCT cell lines (COV434 and KGN) and fresh GCT samples of adult and juvenile types obtained from the patients during surgery. We have discovered that endogenous kinase activity of JNK is markedly enhanced in the GCT samples and cell lines, whereas it was almost undetectable in mitotic non-malignant human granulosa cells. The inhibition of JNK pathway in GCT cell lines with two different pharmacologic inhibitors (SP600125 and AS601245) or siRNA resulted in a dose-dependent reduction in in vitro cell growth, increased apoptosis and diminished estradiol and AMH productions. JNK inhibition was also associated with a decrease in the number of cells positive for mitosis marker phospho-histone H3^{Ser 10} in the asynchronous cells; and diminished EdU uptake during S phase and cell cycle arrest at G2/M-phase transition in the synchronized cells. Ex vivo treatment of patient-derived GCT samples with JNK inhibitors for 24 h significantly decreased their in vitro growth and estradiol and AMH productions. Furthermore, in human GCT xenograft model, in vivo tumor growth was significantly reduced and plasma AMH levels were significantly decreased in SCID mice after administration of JNK inhibitors and siRNA. These findings suggest that targeting JNK pathway may provide therapeutic benefit in the treatment of granulosa cell tumors for which currently no curative therapy exists beyond surgery.

Sphingosine-1-phosphate protects human ovarian follicles from apoptosis in vitro

OBJECTIVE(S)

We aimed to analyze if anti-apoptotic agent sphingosine-1-phosphate offers protection against in vitro follicle atresia during culture of human ovarian cortical samples.

STUDY DESIGN

A translational research study of ex-vivo and in-vitro models of human ovarian tissue.

MATERIAL AND METHODS

Ovarian cortical tissue fragments (1 × 0.5 cm) were obtained from young patients (n = 15 mean age ± SD: 29.4 ± 2.5) undergoing laparoscopic excision of benign ovarian cysts. The samples were cultured for 4 days in 24-well format culture plate using conventional culture techniques. S1P was added to culture media at 200 and 400 μM concentrations. At the end of culture period the samples were processed for both histomorphological assessment and detection of apoptosis with immunohistochemistry and western blot methods using apoptosis marker cleaved caspase-3. In vitro estradiol (E₂) and AMH productions of the samples were measured with ELISA. Follicle counts were expressed as the mean number of follicles per mm².

RESULTS

The mean numbers of primordial and secondary follicles were 3.2 ± 0.4 and 0.7 ± 0.2 respectively, in the fresh fixed uncultured samples. After four days of culture their numbers were significantly decreased to 0.8 ± 0.2 (p < 0.01) and 0.1 ± 0.05 (p < 0.05) respectively, in the control samples cultured without S1P compared to fresh fixed samples. S1P treatment decreased follicle atresia and significantly higher number of primordials (2.3 ± 0.3, p < 0.01) and secondary follicles (0.5 ± 0.1, p < 0.05) survived in the samples after 4 day culture period compared to those cultured without S1P. In line with this there was dose-dependent decrease in the protein expression of cleaved caspase-3 on western blot and in the number of apoptotic follicles stained positive for cleaved caspase-3 on immunohistochemistry in the samples incubated with S1P at 200 and 400 μM concentrations. Furthermore, those samples incubated with S1P produced significantly higher amounts of E₂ (2339 ± 321 vs. 1156 ± 125 pg/mL respectively, p < 0.01) compared to control samples.

CONCLUSIONS

These results suggest that S1P promotes follicle survival in human ovarian cortical samples in vitro.

FSH Stimulation promotes progesterone synthesis and output from human granulosa cells without luteinization

STUDY QUESTION

Can granulosa cells produce progesterone (P) in response to FSH stimulation?

SUMMARY ANSWER

FSH actively promotes P synthesis and output from granulosa cells without luteinization by up-regulating the expression and increasing enzymatic activity of 3β-hydroxysteriod dehydrogenoase (3β-HSD), which converts pregnenolone to P.

WHAT IS KNOWN ALREADY

Serum P level may rise prematurely prior to ovulation trigger in stimulated IVF cycles and adversely affect implantation and clinical pregnancy rates by impairing endometrial receptivity.

STUDY DESIGN, SIZE, DURATION

A translational research study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human ovarian cortical samples (n = 15) and non-luteinizing FSH-responsive human mitotic granulosa cell line (HGrC1) were stimulated with rec-FSH at 12.5, 25 and 50 mIU/ml concentrations for 24 and 48 h. FSH receptor expression was knocked-down and up-regulated in the granulosa cells using short hairpin RNA (shRNA) technology and activin-A administration, respectively. The expressions of the steroidogenic enzymes were analyzed at mRNA level by real-time quantitative RT-PCR, and protein level by western blot and immunoprecipitation assay. The enzymatic activity of 3β-HSD was measured using a spectrophotometric method. In vitro estradiol (E2) and P productions of the cells before and after FSH stimulation were measured by electro-chemiluminescence immunoassay method.

MAIN RESULTS AND THE ROLE OF CHANCE

Stimulation of the HGrC1 cells with FSH resulted in a dose-dependent increase in the mRNA and protein level of 3β-HSD. Overall, when all time points and FSH doses were analyzed collectively, FSH significantly up-regulated the mRNA expression of its own receptor (3.73 ± 0.06-fold, P < 0.001), steroidogenic acute regulatory protein (stAR, 1.7 ± 0.03-fold, P < 0.01), side-chain cleavage enzyme (SCC, 1.75 ± 0.03-fold, P < 0.01), aromatase (4.49 ± 0.08-fold, P < 0.001), 3β-HSD (1.68 ± 0.02-fold, P < 0.01) and 17β-hydroxy steroid dehydrogenase (17β-HSD, 2.16 ± 0.02-fold, P < 0.01) in the granulosa cells. Expression of 17α-hydroxylase (17α-OH, 1.03 ± 0.01-fold P > 0.05) did not significantly change. Similar changes were observed in the protein expression analysis of these enzymes on western blotting after FSH stimulation. FSH significantly increased 3β-HSD, 17β-HSD and aromatase in a dose-dependent manner but did not affect 17α-OH. Protein expression of P was increased along with 3β-HSD after FSH stimulation, which was further evidenced by immunoprecipitation assay. Enzymatic activity of 3β-HSD was significantly enhanced by FSH administration in the HGrC1 cells in a dose-dependent manner. In line with these findings P output (1.05 ± 0.3 vs. 0.2 ± 0.1 ng/ml, respectively, P < 0.001) from the samples stimulated with FSH were significantly increased along with E2 (1918 ± 203 vs. 932 ± 102 pg/ml, respectively, P < 0.001) compared to unstimulated controls. FSH-induced increase in 3β-HSD expression was amplified and reversed in the HGrC1 cells when FSH receptor expression was up-regulated by activin-A and down-regulated with shRNA, respectively.

LIMITATIONS AND REASONS FOR CAUTION

As only the effect of FSH was studied we cannot extrapolate our findings to the potential effects of HMG and recombinant LH.

WIDER IMPLICATIONS OF THE FINDINGS

This data provides a molecular explanation for the largely unexplained phenomenon of P rise during the follicular phase of gonadotropin stimulated IVF cycles. Our findings may progress the research to uncover potential mechanisms for preventing premature P rise that appears to be associated with inferior outcomes in women undergoing IVF.

STUDY FUNDING/COMPETING INTEREST(S)

Funded by the School of Medicine and the Graduate School of Health Sciences of Koc University. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

None.

GnRH agonist leuprolide acetate does not confer any protection against ovarian damage induced by chemotherapy and radiation in vitro

STUDY QUESTION

Is there any in vitro evidence for or against ovarian protection by co-administration of a GnRH agonist with chemotherapy in human?

SUMMARY ANSWER

The co-administration of GnRH agonist leuprolide acetate with cytotoxic chemotherapy agents does not preserve ovarian reserve in vitro.

WHAT IS KNOWN ALREADY

Randomized controlled trials of the co-administration of gonadotrophin-releasing hormone (GnRH) agonists with adjuvant chemotherapy to preserve ovarian function have shown contradictory results. This fact, together with the lack of a proven molecular mechanism of action for ovarian protection with GnRH agonist (GnRHa) places this approach as a fertility preservation strategy under scrutiny. We therefore aimed in this study to provide in vitro evidence for or against the role of GnRHa in the prevention of chemotherapy-induced damage in human ovary.

STUDY DESIGN, SETTINGS, SIZE AND DURATION

This translational research study of ex vivo and in vitro models of human ovary and granulosa cells was conducted in a university hospital between 2013 and 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovarian cortical pieces (n = 15, age 14-37) and mitotic non-luteinized (COV434 and HGrC1) and non-mitotic luteinized human granulosa cells (HLGC) expressing GnRH receptor were used for the experiments. The samples were treated with cyclophosphamide, cisplatin, paclitaxel, 5-FU, or TAC combination regimen (docetaxel, adriamycin and cyclophosphamide) with and without GnRHa leuprolide acetate for 24 h. DNA damage, apoptosis, follicle reserve, hormone markers of ovarian function and reserve (estradiol (E2), progesterone (P) and anti-mullerian hormone (AMH)) and the expression of anti-apoptotic genes (bcl-2, bcl-xL, bcl-2L2, Mcl-1, BIRC-2 and XIAP) were compared among control, chemotherapy and chemotherapy + GnRHa groups.

MAIN RESULTS AND THE ROLE OF CHANCE

The greatest magnitude of cytotoxicity was observed in the samples treated with cyclophosphamide, cisplatin and TAC regimen. Exposure to these drugs resulted in DNA damage, apoptosis and massive follicle loss along with a concurrent decline in the steroidogenic activity of the samples. GnRHa co-administered with chemotherapy agents stimulated its receptors and raised intracellular cAMP levels. But it neither activated anti-apoptotic pathways nor prevented follicle loss, DNA damage and apoptosis induced by these drugs.

LIMITATIONS, REASONS FOR CAUTION

Our findings do not conclusively rule out the possibility that GnRHa may offer protection, if any, through some other mechanisms in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

GnRH agonist treatment with chemotherapy does not prevent or ameliorate ovarian damage and follicle loss in vitro. These data can be useful when consulting a young patient who may wish to receive GnRH treatment with chemotherapy to protect her ovaries from chemotherapy-induced damage.

The magnitude of gonadotoxicity of chemotherapy drugs on ovarian follicles and granulosa cells varies depending upon the category of the drugs and the type of granulosa cells

STUDY QUESTION

Do different chemotherapy drugs exert the same magnitude of cytotoxicity on dormant primordial follicles and the growing follicle fraction in the ovary in vivo and on mitotic non-luteinized and non-mitotic luteinized granulosa cells in vitro?

SUMMARY ANSWER

Cyclophosphamide (alkylating agent) and cisplatin (alkylating like) impacted both primordial and pre-antral/antral follicles and both mitotic and non-mitotic granulosa cells, whereas the anti-metabolite cancer drug gemcitabine was detrimental only to pre-antral/antral follicles and mitotic non-luteinized granulosa cells.

WHAT IS KNOWN ALREADY

It is already known that anti-metabolite cancer drugs are less detrimental to the ovary than alkylating and alkylating like agents, such as cyclophosphamide and cisplatin. This assumption is largely based on the results of clinical reports showing lower rates of amenorrhea in women receiving anti-metabolite agent-based regimens compared with those treated with the protocols containing an alkylating drug or a platinum compound. But a quantitative comparison of gonadotoxicity with a histomorphometric proof of evidence has not been available for many chemotherapy drugs. Therefore, we combined in this study in vivo and in vitro models of human and rat origin that allows a comparative analysis of the impact of different chemotherapy agents on the ovary and granulosa cells using real-time quantitative cell indices, histomorphometry, steroidogenesis assays, and DNA damage and cell death/viability markers. We also aimed to investigate if there is a difference between mitotic and non-mitotic granulosa cells in terms of their sensitivity to the cytotoxic actions of chemotherapy drugs with different mechanisms of action. This issue has not been addressed previously.

STUDY DESIGN, SIZE, DURATION

This translational research study involved in vivo analyses of ovaries in rats and in vitro analyses of granulosa cells of human and rat origin.

PARTICIPANTS/MATERIALS, SETTING, METHODS

For the in vivo assays, 54 4- to 6-week old Sprague-Dawley young female rats were randomly allocated into four groups of 13 to receive a single IP injection of: saline (control), gemcitabine (200 mg/kg), cisplatin (50 mg/kg) or cyclophosphamide (200 mg/kg). The animals were euthanized 72 h later. Follicle counts and serum AMH levels were compared between the groups. In vitro cytotoxicity studies were performed using mitotic non-luteinized rat (SIGC) and human (COV434, HGrC1) granulosa cells, and non-mitotic luteinized human (HLGC) granulosa cells. The cells were plated at a density of 5000 cells/well using DMEM-F12 culture media supplemented with 10% FBS. Chemotherapy agents were used at their therapeutic blood concentrations. The growth of mitotic granulosa cells was monitored real-time using xCelligence system. Live/dead cell and apoptosis assays were also carried out using intravital Yo-Pro-1 staining and cleaved caspase-3 expression, respectively. Estradiol (E2), progesterone (P) and anti-Mullerian hormone (AMH) levels were assayed with ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Cyclophosphamide and cisplatin caused massive atresia of both primordials and growing follicles in the rat ovary whereas gemcitabine impacted pre-antral/antral follicles only. Cyclophosphamide and cisplatin induced apoptosis of both mitotic non-luteinized and non-mitotic luteinized granulosa cells in vitro. By contrast, cytotoxicity of gemcitabine was confined to mitotic non-luteinized granulosa cells.

LIMITATIONS, REASONS FOR CAUTION

This study tested only three chemotherapeutic agents. The experimental methodology described here could be applied to other drugs for detailed analysis of their ovarian cytotoxicity.

WIDER IMPLICATIONS OF THE FINDINGS

These findings indicate that in vivo and in vitro cytotoxic actions of chemotherapy drugs on the ovarian follicles and granulosa cells vary depending upon the their mechanism of action and the nature of the granulosa cells.