Autophagy is required for stem-cell-mediated endometrial programming and the establishment of pregnancy

Autophagy plays an important role in the normal growth and morphogenesis of a variety of tissues. Its role in uterine maturation, however, is not fully characterized. Recently, we reported that BECN1 (Beclin1)-dependent autophagy, but not apoptosis, is crucial for stem cell-mediated endometrial programming and the establishment of pregnancy in mice. Upon genetic and pharmacological inhibition of BECN1-mediated autophagy, female mice displayed severe endometrial structural and functional defects leading to infertility. Specifically, conditional loss of Becn1 in the uterus induces apoptosis and results in the gradual loss of endometrial progenitor stem cells. Importantly, the restoration of BECN1-driven autophagy, but not apoptosis in Becn1 conditionally ablated mice promoted normal uterine adenogenesis and morphogenesis. Overall, our findings emphasize the critical role of intrinsic autophagy in endometrial homeostasis and on the molecular underpinnings of uterine differentiation.

The autophagy protein, ATG14 safeguards against unscheduled pyroptosis activation to enable embryo transport during early pregnancy

Recurrent pregnancy loss (RPL), characterized by two or more failed clinical pregnancies, poses a significant challenge to reproductive health. In addition to embryo quality and endometrial function, proper oviduct function is also essential for successful pregnancy establishment. Therefore, structural abnormalities or inflammation resulting from infection in the oviduct may impede the transport of embryos to the endometrium, thereby increasing the risk of miscarriage. However, the precise cellular mechanisms that maintain the structural and functional integrity of the oviduct are not studied yet. Here, we report that autophagy is critical for maintaining the oviduct homeostasis and keeping the inflammation under check to enable embryo transport. Specifically, the loss of the autophagy-related gene, Atg14 in the oviduct causes severe structural abnormalities compromising its cellular plasticity and integrity leading to the retention of embryos. Interestingly, the selective loss of Atg14 in oviduct ciliary epithelial cells did not impact female fertility, highlighting the specificity of ATG14 function in distinct cell types within the oviduct. Mechanistically, loss of Atg14 triggered unscheduled pyroptosis leading to inappropriate embryo retention and impeded embryo transport in the oviduct. Finally, pharmacological activation of pyroptosis in pregnant mice led to an impairment in embryo transport. Together, we found that ATG14 safeguards against unscheduled pyroptosis activation to enable embryo transport from the oviduct to uterus for the successful implantation. Of clinical significance, these findings provide possible insights on the underlying mechanism(s) of early pregnancy loss and might aid in developing novel prevention strategies using autophagy modulators.

A GREB1-steroid receptor feedforward mechanism governs differential GREB1 action in endometrial function and endometriosis

Cellular responses to the steroid hormones, estrogen (E2), and progesterone (P4) are governed by their cognate receptor's transcriptional output. However, the feed-forward mechanisms that shape cell-type-specific transcriptional fulcrums for steroid receptors are unidentified. Herein, we found that a common feed-forward mechanism between GREB1 and steroid receptors regulates the differential effect of GREB1 on steroid hormones in a physiological or pathological context. In physiological (receptive) endometrium, GREB1 controls P4-responses in uterine stroma, affecting endometrial receptivity and decidualization, while not affecting E2-mediated epithelial proliferation. Of mechanism, progesterone-induced GREB1 physically interacts with the progesterone receptor, acting as a cofactor in a positive feedback mechanism to regulate P4-responsive genes. Conversely, in endometrial pathology (endometriosis), E2-induced GREB1 modulates E2-dependent gene expression to promote the growth of endometriotic lesions in mice. This differential action of GREB1 exerted by a common feed-forward mechanism with steroid receptors advances our understanding of mechanisms that underlie cell- and tissue-specific steroid hormone actions.

Beclin-1-dependent autophagy, but not apoptosis, is critical for stem-cell-mediated endometrial programming and the establishment of pregnancy

The human endometrium shows a remarkable regenerative capacity that enables cyclical regeneration and remodeling throughout a woman's reproductive life. Although early postnatal uterine developmental cues direct this regeneration, the vital factors that govern early endometrial programming are largely unknown. We report that Beclin-1, an essential autophagy-associated protein, plays an integral role in uterine morphogenesis during the early postnatal period. We show that conditional depletion of Beclin-1 in the uterus triggers apoptosis and causes progressive loss of Lgr5+/Aldh1a1+ endometrial progenitor stem cells, with concomitant loss of Wnt signaling, which is crucial for stem cell renewal and epithelial gland development. Beclin-1 knockin (Becn1 KI) mice with disabled apoptosis exhibit normal uterine development. Importantly, the restoration of Beclin-1-driven autophagy, but not apoptosis, promotes normal uterine adenogenesis and morphogenesis. Together, the data suggest that Beclin-1-mediated autophagy acts as a molecular switch that governs the early uterine morphogenetic program by maintaining the endometrial progenitor stem cells.

SF3B1-dependent alternative splicing is critical for maintaining endometrial homeostasis and the establishment of pregnancy

The remarkable potential of human endometrium to undergo spontaneous remodeling is shaped by controlled spatiotemporal gene expression patterns. Although hormone-driven transcription shown to govern these patterns, the post-transcriptional processing of these mRNA transcripts, including the mRNA splicing in the endometrium is not studied yet. Here, we report that the splicing factor, SF3B1 is central in driving alternative splicing (AS) events that are vital for physiological responses of the endometrium. We show that loss of SF3B1 splicing activity impairs stromal cell decidualization as well as embryo implantation. Transcriptomic analysis revealed that SF3B1 depletion decidualizing stromal cells led to differential mRNA splicing. Specifically, a significant upregulation in mutually exclusive AS events (MXEs) with SF3B1 loss resulted in the generation of aberrant transcripts. Further, we found that some of these candidate genes phenocopy SF3B1 function in decidualization. Importantly, we identify progesterone as a potential upstream regulator of SF3B1-mediated functions in endometrium possibly via maintaining its persistently high levels, in coordination with deubiquitinating enzymes. Collectively, our data suggest that SF3B1-driven alternative splicing plays a critical role in mediating the endometrial-specific transcriptional paradigms. Thus, the identification of novel mRNA variants associated with successful pregnancy establishment may help to develop new strategies to diagnose or prevent early pregnancy loss.

Abstract 4877: Mutant or overexpressed SF3B1 facilitates endometrial cancer tumorigenesis

Aberrant expression or mutations in core splicing factors including U2AF1, SRSF2, ZRSR2, and SF3B1 found to drive tumorigenesis of various malignant tumors e.g., myelodysplastic syndromes, chronic lymphocytic leukemia, uveal melanoma, and breast cancer. Importantly, the amplifications and mutations in SF3B1, the pioneer splicing factor, are reportedly far more common than those in other splicing factors. However, the functional relevance and underlying mechanisms of dysregulated SF3B1 in endometrial cancer are not investigated. Endometrial cancer is the fourth most common cancer in women in the United States and there will be about 65,950 new endometrial cancer cases in the current year alone with 12,550 estimated cancer deaths in the United States. In this study, we thus investigated the role of SF3B1 in endometrial adenocarcinoma. We found SF3B1 is one of the most frequently amplified or mutated splicing factors in endometrial cancer. Specifically, analysis of The Cancer Genome Atlas (TCGA) uterine pan-cancer dataset revealed that up to 9% of endometrial cancers have SF3B1 mutations or amplification. Additionally, we showed that the SF3B1 protein is overexpressed in human as well as mouse endometrial tumor samples. Further analysis found elevated SF3B1 protein in multiple endometrial cancer cell lines even in the absence of SF3B1 mutations. However, we did not observe any altered expression at the transcript level. Further, we identified a correlation between the over-expressed SF3B1 levels and the tumorigenicity/invasive potential of cancer cell lines. For instance, endometrial cancer cell lines (Ishikawa, AN3CA, KLE) with over-expressed SF3B1 levels were much more tumorigenic and invasive than those with low endogenous SF3B1 levels (normal human endometrial epithelial cells, RL-95-2 cells). Moreover, cell viability assays revealed that Ishikawa, AN3CA, and KLE cells were more susceptible to the loss of SF3B1 or treatment with the SF3B1 inhibitor Pladienolide-B (PLAD-B) than RL-95-2 cells. To further ensure that overexpressed or mutated SF3B1 drives endometrial tumorigenesis, we transiently transfected an empty vector or a vector expressing FLAG-tagged wild-type SF3B1 or vector with mutated SF3B1 construct R957Q into RL-95-2 cells which have minimal endogenous SF3B1. Analysis of proliferation assays revealed that cells overexpressing SF3B1 proliferated significantly more than cells expressing empty vector. Intriguingly, we observed that RL-95-2 cells over-expressing R957Q mutants were even more proliferative than the cells expressing wild-type SF3B1. Together, this data suggest that SF3B1 over-expression and mutation play a crucial oncogenic role in endometrial cancer, and these findings may support the development of SF3B1 inhibitors to treat this disease.

Citation Format: Pooja Popli, Xinchao Deng, Premal Thaker, Ramakrishna Kommagani. Mutant or overexpressed SF3B1 facilitates endometrial cancer tumorigenesis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4877.

Gut microbiota and microbiota-derived metabolites promotes endometriosis

Endometriosis is a pathological condition of the female reproductive tract characterized by the existence of endometrium-like tissue at ectopic sites, affecting 10% of women between the age 15 and 49 in the USA. However, currently there is no reliable non-invasive method to detect the presence of endometriosis without surgery and many women find hormonal therapy and surgery as ineffective in avoiding the recurrences. There is a lack of knowledge on the etiology and the factors that contribute to the development of endometriosis. A growing body of recent evidence suggests an association between gut microbiota and endometriosis pathophysiology. However, the direct impact of microbiota and microbiota-derived metabolites on the endometriosis disease progression is largely unknown. To understand the causal role of gut microbiota and endometriosis, we have implemented a novel model using antibiotic-induced microbiota-depleted (MD) mice to investigate the endometriosis disease progression. Interestingly, we found that MD mice showed reduced endometriotic lesion growth and, the transplantation of gut microbiota by oral gavage of feces from mice with endometriosis rescued the endometriotic lesion growth. Additionally, using germ-free donor mice, we indicated that the uterine microbiota is dispensable for endometriotic lesion growth in mice. Furthermore, we showed that gut microbiota modulates immune cell populations in the peritoneum of lesions-bearing mice. Finally, we found a novel signature of microbiota-derived metabolites that were significantly altered in feces of mice with endometriosis. Finally, we found one the altered metabolite, quinic acid promoted the survival of endometriotic epithelial cells in vitro and lesion growth in vivo, suggesting the disease-promoting potential of microbiota-derived metabolites. In summary, these data suggest that gut microbiota and microbiota-derived metabolome contribute to lesion growth in mice, possibly through immune cell adaptations. Of translational significance, these findings will aid in designing non-invasive diagnostics using stool metabolites for endometriosis.

A genome-wide CRISPR-Cas9 knockout screen identifies essential and growth-restricting genes in human trophoblast stem cells

The recent derivation of human trophoblast stem cells (hTSCs) provides a scalable in vitro model system of human placental development, but the molecular regulators of hTSC identity have not been systematically explored thus far. Here, we utilize a genome-wide CRISPR-Cas9 knockout screen to comprehensively identify essential and growth-restricting genes in hTSCs. By cross-referencing our data to those from similar genetic screens performed in other cell types, as well as gene expression data from early human embryos, we define hTSC-specific and -enriched regulators. These include both well-established and previously uncharacterized trophoblast regulators, such as ARID3A, GATA2, and TEAD1 (essential), and GCM1, PTPN14, and TET2 (growth-restricting). Integrated analysis of chromatin accessibility, gene expression, and genome-wide location data reveals that the transcription factor TEAD1 regulates the expression of many trophoblast regulators in hTSCs. In the absence of TEAD1, hTSCs fail to complete faithful differentiation into extravillous trophoblast (EVT) cells and instead show a bias towards syncytiotrophoblast (STB) differentiation, thus indicating that this transcription factor safeguards the bipotent lineage potential of hTSCs. Overall, our study provides a valuable resource for dissecting the molecular regulation of human placental development and diseases.

Real-world application of tumor mutational burden-high (TMB-high) and microsatellite instability (MSI) confirms their utility as immunotherapy biomarkers

Introduction

Microsatellite instability (MSI) testing and tumor mutational burden (TMB) are genomic biomarkers used to identify patients who are likely to benefit from immune checkpoint inhibitors. Pembrolizumab was recently approved by the Food and Drug Administration for use in TMB-high (TMB-H) tumors, regardless of histology, based on KEYNOTE-158. The primary objective of this retrospective study was real-world applicability and use of immunotherapy in TMB/MSI-high patients to lend credence to and refine this biomarker.

Methods

Charts of patients with advanced solid tumors who had MSI/TMB status determined by next generation sequencing (NGS) (FoundationOne CDx) were reviewed. Demographics, diagnosis, treatment history, and overall response rate (ORR) were abstracted. Progression-free survival (PFS) was determined from Kaplan–Meier curves. PFS1 (chemotherapy PFS) and PFS2 (immunotherapy PFS) were determined for patients who received immunotherapy after progressing on chemotherapy. The median PFS2/PFS1 ratio was recorded.

Results

MSI-high or TMB-H [≥20 mutations per megabase (mut/MB)] was detected in 157 adults with a total of 27 distinct tumor histologies. Median turnaround time for NGS was 73 days. ORR for most recent chemotherapy was 34.4%. ORR for immunotherapy was 55.9%. Median PFS for patients who received chemotherapy versus immunotherapy was 6.75 months (95% confidence interval, 3.9-10.9 months) and 24.2 months (95% confidence interval, 9.6 months to not reached), respectively (P = 0.042). Median PFS2/PFS1 ratio was 4.7 in favor of immunotherapy.

Conclusion

This real-world study reinforces the use of TMB as a predictive biomarker. Barriers exist to the timely implementation of NGS-based biomarkers and more data are needed to raise awareness about the clinical utility of TMB. Clinicians should consider treating TMB-H patients with immunotherapy regardless of their histology.

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This retrospective study examined the real-world use of immune checkpoint inhibitors (ICIs) in TMB/MSI-high patients with a diverse set of cancer types.

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TMB is an emerging tumor-agnostic biomarker for response to treatment with ICIs that may expand personalized cancer care.

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ICIs remain underutilized as a first-line therapy for TMB/MSI-H patients without specific histologic approval for ICIs.

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The PFS2 to PFS1 ratio was 4.7, favoring immunotherapy over chemotherapy even as a second-line therapy.

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Our study reinforces the real-world evidence that TMB is a valid surrogate marker for MSI and can predict response to ICIs.

Gut microbiota-derived short-chain fatty acids protect against the progression of endometriosis

Worldwide, ∼196 million are afflicted with endometriosis, a painful disease in which endometrial tissue implants and proliferates on abdominal peritoneal surfaces. Theories on the origin of endometriosis remained inconclusive. Whereas up to 90% of women experience retrograde menstruation, only 10% develop endometriosis, suggesting that factors that alter peritoneal environment might contribute to endometriosis. Herein, we report that whereas some gut bacteria promote endometriosis, others protect against endometriosis by fermenting fiber to produce short-chain fatty acids. Specifically, we found that altered gut microbiota drives endometriotic lesion growth and feces from mice with endometriosis contained less of short-chain fatty acid and n-butyrate than feces from mice without endometriosis. Treatment with n-butyrate reduced growth of both mouse endometriotic lesions and human endometriotic lesions in a pre-clinical mouse model. Mechanistic studies revealed that n-butyrate inhibited human endometriotic cell survival and lesion growth through G-protein-coupled receptors, histone deacetylases, and a GTPase activating protein, RAP1GAP. Our findings will enable future studies aimed at developing diagnostic tests, gut bacteria metabolites and treatment strategies, dietary supplements, n-butyrate analogs, or probiotics for endometriosis.

The SARS-CoV-2 receptor, angiotensin-converting enzyme 2, is required for human endometrial stromal cell decidualization†

The coronavirus disease 2019 (COVID-19) first appeared in December 2019 and rapidly spread throughout the world. The SARS-CoV-2 virus enters the host cells by binding to the angiotensin-converting enzyme 2 (ACE2). Although much of the focus is on respiratory symptoms, recent reports suggest that SARS-CoV-2 can cause pregnancy complications such as pre-term birth and miscarriages; and women with COVID-19 have had maternal vascular malperfusion and decidual arteriopathy in their placentas. Here, we report that the ACE2 protein is expressed in both endometrial epithelial and stromal cells in the proliferative phase of the menstrual cycle, and the expression increases in stromal cells in the secretory phase. It was observed that the ACE2 mRNA and protein abundance increased during primary human endometrial stromal cell (HESC) decidualization. Furthermore, HESCs transfected with ACE2-targeting siRNA impaired the full decidualization response, as evidenced by a lack of morphology change and lower expression of the decidualization markers PRL and IGFBP1. Additionally, in mice during pregnancy, the ACE2 protein was expressed in the uterine epithelial cells, and stromal cells increased through day 6 of pregnancy. Finally, progesterone induced Ace2 mRNA expression in mouse uteri more than vehicle or estrogen. These data establish a role for ACE2 in endometrial physiology, suggesting that SARS-CoV-2 may be able to enter endometrial stromal cells and elicit pathological manifestations in women with COVID-19, including an increased risk of early pregnancy loss.

Splicing factor SF3B1 promotes endometrial cancer progression via regulating KSR2 RNA maturation

Although endometrial cancer is the most common cancer of the female reproductive tract, we have little understanding of what controls endometrial cancer beyond the transcriptional effects of steroid hormones such as estrogen. As a result, we have limited therapeutic options for the ~62,000 women diagnosed with endometrial cancer each year in the United States. Here, in an attempt to identify new prognostic and therapeutic targets, we focused on a new area for this cancer—alternative mRNA splicing—and investigated whether splicing factor, SF3B1, plays an important role in endometrial cancer pathogenesis. Using a tissue microarray, we found that human endometrial tumors expressed more SF3B1 protein than non-cancerous tissues. Furthermore, SF3B1 knockdown reduced in vitro proliferation, migration, and invasion of the endometrial cancer cell lines Ishikawa and AN3CA. Similarly, the SF3B1 inhibitor, Pladienolide-B (PLAD-B), reduced the Ishikawa and AN3CA cell proliferation and invasion in vitro. Moreover, PLAD-B reduced tumor growth in an orthotopic endometrial cancer mouse model. Using RNA-Seq approach, we identified ~2000 differentially expressed genes (DEGs) with SF3B1 knockdown in endometrial cancer cells. Additionally, alternative splicing (AS) events analysis revealed that SF3B1 depletion led to alteration in multiple categories of AS events including alternative exon skipping (ES), transcript start site usage (TSS), and transcript termination site (TTS) usage. Subsequently, bioinformatics analysis showed KSR2 as a potential candidate for SF3B1-mediated functions in endometrial cancer. Specifically, loss of SF3B1 led to decrease in KSR2 expression, owing to reduced maturation of KSR2 pre-mRNA to a mature RNA. Importantly, we found rescuing the KSR2 expression with SF3B1 knockdown partially restored the cell growth of endometrial cancer cells. Taken together, our data suggest that SF3B1 plays a crucial oncogenic role in the tumorigenesis of endometrial cancer and hence may support the development of SF3B1 inhibitors to treat this disease.

The SARS-CoV-2 receptor, Angiotensin converting enzyme 2 (ACE2) is required for human endometrial stromal cell decidualization

STUDY QUESTION

Is SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE 2) expressed in the human endometrium during the menstrual cycle, and does it participate in endometrial decidualization?

SUMMARY ANSWER

ACE2 protein is highly expressed in human endometrial stromal cells during the secretory phase and is essential for human endometrial stromal cell decidualization.

WHAT IS KNOWN ALREADY

ACE2 is expressed in numerous human tissues including the lungs, heart, intestine, kidneys and placenta. ACE2 is also the receptor by which SARS-CoV-2 enters human cells.

STUDY DESIGN SIZE DURATION

Proliferative (n = 9) and secretory (n = 6) phase endometrium biopsies from healthy reproductive-age women and primary human endometrial stromal cells from proliferative phase endometrium were used in the study.

PARTICIPANTS/MATERIALS SETTING METHODS

ACE2 expression and localization were examined by qRT-PCR, Western blot, and immunofluorescence in both human endometrial samples and mouse uterine tissue. The effect of ACE2 knockdown on morphological and molecular changes of human endometrial stromal cell decidualization were assessed. Ovariectomized mice were treated with estrogen or progesterone to determine the effects of these hormones on ACE2 expression.

MAIN RESULTS AND THE ROLE OF CHANCE

In human tissue, ACE2 protein is expressed in both endometrial epithelial and stromal cells in the proliferative phase of the menstrual cycle, and expression increases in stromal cells in the secretory phase. The ACE2 mRNA ( P < 0.0001) and protein abundance increased during primary human endometrial stromal cell (HESC) decidualization. HESCs transfected with ACE2 -targeting siRNA were less able to decidualize than controls, as evidenced by a lack of morphology change and lower expression of the decidualization markers PRL and IGFBP1 ( P < 0.05). In mice during pregnancy, ACE2 protein was expressed in uterine epithelial and stromal cells increased through day six of pregnancy. Finally, progesterone induced expression of Ace2 mRNA in mouse uteri more than vehicle or estrogen ( P < 0.05).

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

Experiments assessing the function of ACE2 in human endometrial stromal cell decidualization were in vitro . Whether SARS-CoV-2 can enter human endometrial stromal cells and affect decidualization have not been assessed.

WIDER IMPLICATIONS OF THE FINDINGS

Expression of ACE2 in the endometrium allow SARS-CoV-2 to enter endometrial epithelial and stromal cells, which could impair in vivo decidualization, embryo implantation, and placentation. If so, women with COVID-19 may be at increased risk of early pregnancy loss.

STUDY FUNDINGS/COMPETING INTERESTS

This study was supported by National Institutes of Health / National Institute of Child Health and Human Development grants R01HD065435 and R00HD080742 to RK and Washington University School of Medicine start-up funds to RK. The authors declare that they have no conflicts of interest.

Derivation of trophoblast stem cells from naïve human pluripotent stem cells

Naïve human pluripotent stem cells (hPSCs) provide a unique experimental platform of cell fate decisions during pre-implantation development, but their lineage potential remains incompletely characterized. As naïve hPSCs share transcriptional and epigenomic signatures with trophoblast cells, it has been proposed that the naïve state may have enhanced predisposition for differentiation along this extraembryonic lineage. Here we examined the trophoblast potential of isogenic naïve and primed hPSCs. We found that naïve hPSCs can directly give rise to human trophoblast stem cells (hTSCs) and undergo further differentiation into both extravillous and syncytiotrophoblast. In contrast, primed hPSCs do not support hTSC derivation, but give rise to non-self-renewing cytotrophoblasts in response to BMP4. Global transcriptome and chromatin accessibility analyses indicate that hTSCs derived from naïve hPSCs are similar to blastocyst-derived hTSCs and acquire features of post-implantation trophectoderm. The derivation of hTSCs from naïve hPSCs will enable elucidation of early mechanisms that govern normal human trophoblast development and associated pathologies.

The Autophagy Gene Atg16L1 is Necessary for Endometrial Decidualization

Uterine receptivity is critical for establishing and maintaining pregnancy. For the endometrium to become receptive, stromal cells must differentiate into decidual cells capable of secreting factors necessary for embryo survival and placental development. Although there are multiple reports of autophagy induction correlated with endometrial stromal cell (ESC) decidualization, the role of autophagy in decidualization has remained elusive. To determine the role of autophagy in decidualization, we utilized 2 genetic models carrying mutations to the autophagy gene Atg16L1. Although the hypomorphic Atg16L1 mouse was fertile and displayed proper decidualization, conditional knockout in the reproductive tract of female mice reduced fertility by decreasing the implantation rate. In the absence of Atg16L1, ESCs failed to properly decidualize and fewer blastocysts were able to implant. Additionally, small interfering RNA knock down of Atg16L1 was detrimental to the decidualization response of human ESCs. We conclude that Atg16L1 is necessary for decidualization, implantation, and overall fertility in mice. Furthermore, considering its requirement for human endometrial decidualization, these data suggest Atg16L1 may be a potential mediator of implantation success in women.

Microtubule depolymerization attenuates WNT4/CaMKIIα signaling in mouse uterus and leads to implantation failure

Microtubule (MT) dynamics plays a crucial role in fertilization and early embryonic development; however its involvement in uterus during embryo implantation remains unclear. Herein, we report the effect of microtubule depolymerization during embryo implantation in BALB/c mice. Intrauterine treatment with depolymerizing agent nocodazole at pre-implantation phase (D4, 07:00 h) in mice resulted into mitigation in receptivity markers viz. LIF, HoxA10, Integrin-β3, IHH, WNT4 and led to pregnancy failure. MT depolymerization in endometrial epithelial cells (EECs) also inhibited the blastocyst attachment and the adhesion. The decreased expression of MT polymerization-related proteins TPPP and α/β-tubulin in luminal and glandular epithelial cells along with the alteration in morphology of pinopodes in the luminal epithelium was observed in nocodazole receiving uteri. Nocodazole treatment also led to increased intracellular Ca+2levels in EECs, which indicated that altered Ca+2homeostasis might be responsible for implantation failure. Microtubule depolymerization inhibited WNT4 and Fz-2 interaction, thereby suppressing the downstream WNT4/CaMKIIα signaling cascades calmodulin and calcineurin which led to attenuation of NF-κB transcriptional promoter activity in EECs. MT depolymerization or CaMKIIα knockdown inhibited the transcription factor NFAT and NF-κB expression along with reduced secretion of prostaglandins PGE2 and PGF2α in mouse EECs. Overall, MT depolymerization impaired the WNT4/CaMKIIα signaling and suppressed the secretion of PGE2 and PGF2α in EECs which may be responsible for implantation failure in mice.

Sonic hedgehog protects endometrial hyperplasial cells against oxidative stress via suppressing mitochondrial fission protein dynamin-like GTPase (Drp1)

Hh/Gli1 cascade as well as Gsk3β-Gli1 crosstalk play crucial role in estrogen-dependent progression of endometrial hyperplasia (EH). However, the underlying mechanisms involved in progression of disease still remain unclear. In the present study, we explored the role of Hh signaling in protection of endometrial hyperplasial cells against oxidative stress and the underlying mechanism involved therein. EH cells were found to be more resistant towards H₂O₂-induced oxidative stress (IC₅₀: ~ 3×) as compared with normal endometrial cells. Estrogen (E2) pre-treatment followed by cytotoxic dose of H₂O_2, almost rescued the EH cells from apoptosis and caused the increased expression of downstream Shh signaling molecules i.e., Smo, Ptch and Gli1. Whereas pretreatment with cyclopamine was not able to curtail H₂O₂-induced effects indicating that estrogen protects these cells via activation of Shh pathway. Further, H₂O₂-induced ROS and lipid peroxidation alongwith decreased activities of antioxidant enzymes glutathione peroxidase and superoxide dismutase were found to be reversed in EH cells pre-exposed to E2 or rShh. The rShh suppressed H₂O₂-induced cell death and caused attenuation of mitochondrial apoptotic mediators and prevented disruption in mitochondrial morphology and mitochondrial membrane potential in EH cells. The functional blockage of signaling by Shh siRNA or Gli1siRNA led to significantly increased expression of mitochondrial fission protein dynamin-like GTPase (Drp1). The H₂O₂-treated EH cells showed diminished Gli1 and increased Drp1 expression, concurrent with reduced p-Drp1-(serine637). Whereas rShh pre-treated EH cells presented normal mitochondrial dynamics with dense, long networks of mitochondria alongwith nuclear accumulation of Gli1 and the decreased expression of Drp1. Overall, our results implicated that Shh signaling modulates antioxidant defense system and stabilizes mitochondrial dynamics by suppressing Drp1 protein which maintains survival of EH cells against oxidative stress.

New piperidine derivative DTPEP acts as dual-acting anti-breast cancer agent by targeting ERα and downregulating PI3K/Akt-PKCα leading to caspase-dependent apoptosis

OBJECTIVES

In our ongoing studies to develop ER targeting agents, we screened for dual-acting molecules with a hypothesis that a single molecule can also target both ER positive and negative groups of breast cancer.

MATERIALS AND METHODS

1-(2-(4-(Dibenzo[b,f]thiepin-10-yl)phenoxy)ethyl)piperidine (DTPEP) was synthesized and screened in both MCF-7 (ER+ve) and MDA-MB-231 (ER-ve) cells. Assays for analysis of cell cycle, ROS, apoptosis and MMP loss were carried out using flow cytometry. Its target was investigated using western blot, transactivation assay and RT-PCR. In vivo efficacy of DTPEP was validated in LA-7 syngeneic rat mammary tumour model.

RESULTS

Here, we report identification of dual-acting molecule DTPEP that downregualtes PI3K/Akt and PKCα expression, induces ROS and ROS-dependent apoptosis, loss of mitochondrial membrane potential, induces expression of caspase indicative of both intrinsic and extrinsic apoptosis in MCF-7 and MDA-MB-231 cells. In MCF-7 cells, DTPEP downregulates ERα expression and activation. In MDA-MB-231 cells, primary cellular target of DTPEP is not clearly known, but it downregualtes PI3K/Akt and PKCα expression. In vivo study showed regression of LA-7 syngeneic mammary tumour in SD rat.

CONCLUSIONS

We identified a new dual-acting anti-breast cancer molecules as a proof of concept which is capable of targeting both ER-positive and ER-negative breast cancer.

Sorcin is involved during embryo implantation via activating VEGF/PI3K/Akt pathway in mice

Our earlier studies have demonstrated the cyclic variation and also the altered expression of sorcin in endometrium during early-to-mid-secretory phase transition in women with unexplained infertility. The current study was undertaken to establish the functional role of sorcin in endometrial receptivity in mice. Results indicated that sorcin was highly expressed during the window of implantation in mice and functional blockage of sorcin caused significant reduction in number of implanted blastocyst. The receptivity markers (i.e.Integrin β3, HBEGF, IGFBP1, WNT4 and Cyclin E)) were found to be downregulated in sorcin knocked down uterine horn on day 5 as compared to untreated horn. The reduced attachment and expansion of BeWo spheroids on RL95-2 endometrial cells with sorcin knock down, in in vitro model of endometrium-trophoblast interaction further supported these findings. Uterine sorcin expression pattern during estrous cycle and in delayed implantation mice model suggested the upregulation of sorcin by estrogen. The functional blockade of sorcin induced the intracellular Ca⁺² levels in endometrial epithelial cells (EECs), which indicated that altered Ca⁺² homeostasis might be responsible for implantation failure. Sorcin silencing led to significant reduction in the expression of angiogenic factor VEGF and its downstream effector molecules i.e. PI3K, Akt and NOS. The migratory and invasive properties of HUVECs were abrogated by anti-VEGF or by adding culture media from sorcin blocked EECs, which indicated that sorcin might mediate angiogenesis during implantation. Taken together, sorcin is involved in the regulation of Ca⁺²-mediated angiogenesis via VEGF/PI3K/Akt pathway in endometrial cells and plays a crucial role in preparing the endometrium for implantation.

Curcumin exhibits anti-tumor effect and attenuates cellular migration via Slit-2 mediated down-regulation of SDF-1 and CXCR4 in endometrial adenocarcinoma cells

Although curcumin shows anti-proliferative and anti-inflammatory activities in various cancers, the effect of curcumin on cellular migration in endometrial adenocarcinoma cells remains to be understood. The current investigation was aimed to explore the anti-proliferative and anti-migratory effects of curcumin and its mechanism of action in endometrial cancer cells. Our in-vitro and in-vivo experimental studies showed that curcumin inhibited the proliferation of endometrial cancer cells and suppressed the tumor growth in Ishikawa xenograft mouse model. Curcumin induced ROS-mediated apoptosis in endometrial cancer cells. Curcumin suppressed the migration rate of Ishikawa and Hec-1B cells as analyzed by scratch wound assay. In transwell migration studies, knock down of Slit-2 reversed the anti-migratory effect of curcumin in these cell lines. Curcumin significantly up-regulated the expression of Slit-2 in Ishikawa, Hec-1B and primary endometrial cancer cells while it down-regulated the expression of stromal cell-derived factor-1 (SDF-1) and CXCR4 which in turn, suppressed the expression of matrix metallopeptidases (MMP) 2 and 9, thus attenuating the migration of endometrial cancer cells. In summary, we have demonstrated that curcumin has inhibitory effect on cellular migration via Slit-2 mediated down-regulation of CXCR4, SDF-1, and MMP2/MMP9 in endometrial carcinoma cells. These findings helped explore the role of Slit-2 in endometrial cancer cells.

Regulation of cyclooxygenase-2 expression in rat oviductal epithelial cells: Evidence for involvement of GPR30/Src kinase-mediated EGFR signaling

The oviduct plays a crucial role in female reproduction by regulating gamete transport, providing a specific microenvironment for fertilization and early embryonic development. Cyclooxygenase (COX)-derived prostaglandins play essential role in carrying out these oviduct-specific functions. Estrogen upregulates COX-2 expression in rat oviduct; however, the mechanisms responsible for regulation of COX-2 expression in rat oviductal epithelial cells (OECs) remain unclear. In the present study, we proposed that estrogen induces COX-2 expression via G-protein coupled receptor i.e., GPR30 in OECs. To investigate this hypothesis, we examined the effects of E2-BSA, ICI 182,780, GPR30 agonist and GPR30 antagonist on COX-2 expression and explored potential signaling pathway leading to COX-2 expression. Co-localization experiments revealed GPR30 to be primarily located in the peri-nuclear space, which was also the site of E2-BSA-fluorescein isothiocyanate (E2-BSA-FITC) binding. The E2-BSA induced-COX-2 and prostaglandin release were subjected to regulation by both EGFR and PI3K signaling as inhibitors of c-Src kinase (PP2), EGFR (EGFR inhibitor) and PI-3 kinase (LY294002) attenuated E2-BSA mediated effect. These results suggest that EGFR transactivation leading to activation of PI-3K/Akt pathway participates in COX-2 expression in rat OECs. Interestingly, E2-BSA induced COX-2 expression and subsequent prostaglandin release were abolished by NF-κB inhibitor. In addition, E2-BSA induced the nuclear translocation of p65-NF-κB and up-regulated the NF-κB promoter activity in rat OECs. Taken together, results demonstrated that E2-BSA induced the COX-2 expression and consequent PGE2 and PGF2α release in rat OECs. These effects are mediated through GPR30-derived EGFR transactivation and PI-3K/Akt cascade leading to NF-κB activation.

Phytoestrogen genistein inhibits EGFR/PI3K/NF-kB activation and induces apoptosis in human endometrial hyperplasial cells

Endometrial hyperplasia is an estrogen-dependent disease and is the most frequent precursor of endometrial cancer, diagnosed in pre- and peri-menopausal women.

Inhibitory effect of 2-(piperidinoethoxyphenyl)-3-(4-hydroxyphenyl)-2H-benzo(b)pyran (K-1) on human primary endometrial hyperplasial cells mediated via combined suppression of Wnt/β-catenin signaling and PI3K/Akt survival pathway

Endometrial hyperplasia is a precursor to the most common gynecologic cancer diagnosed in women. Apart from estrogenic induction, aberrant activation of the Wnt/β-catenin signal is well known to correlate with endometrial hyperplasia and its carcinoma. The benzopyran compound 2-(piperidinoethoxyphenyl)-3-(4-hydroxyphenyl)-2H-benzo (b) pyran(K-1), a potent antiestrogenic agent, has been shown to have apoptosis-inducing activity in rat uterine hyperplasia. The current study was undertaken to explore the effect of the benzopyran compound K-1 on growth and Wnt signaling in human endometrial hyperplasial cells. Primary culture of atypical endometrial hyperplasial cells was characterized by the epithelial cell marker cytokeratin-7. Results revealed that compound K-1 reduced the viability of primary endometrial hyperplasial cells and expression of ERα, PR, PCNA, Wnt7a, FZD6, pGsk3β and β-catenin without affecting the growth of the primary culture of normal endometrial cells. The β-catenin target genes CyclinD1 and c-myc were also found to be reduced, whereas the expression of axin2 and Wnt/β-catenin signaling inhibitor Dkk-1 was found to be upregulated, which caused the reduced interaction of Wnt7a and FZD6. Nuclear accumulation of β-catenin was found to be decreased by compound K-1. K-1 also suppressed the pPI3K/pAkt survival pathway and induced the cleavage of caspases and PARP, thus subsequently causing the apoptosis of endometrial hyperplasial cells. In conclusion, compound K-1 suppressed the growth of human primary endometrial hyperplasial cells through discontinued Wnt/β-catenin signaling and induced apoptosis via inhibiting the PI3K/Akt survival pathway.