Lkb1 inactivation is sufficient to drive endometrial cancers that are aggressive yet highly responsive to mTOR inhibitor monotherapy

In Vivo Intra-Uterine Delivery of TAT-Fused Cre Recombinase and CRISPR/Cas9 Editing System in Mice Unveil Histopathology of Pten/p53-Deficient Endometrial Cancers

Phosphatase and TENsin homolog (Pten) and p53 are two of the most frequently mutated tumor suppressor genes in endometrial cancer. However, the functional consequences and histopathological manifestation of concomitant p53 and Pten loss of function alterations in the development of endometrial cancer is still controversial. Here, it is demonstrated that simultaneous Pten and p53 deletion is sufficient to cause epithelial to mesenchymal transition phenotype in endometrial organoids. By a novel intravaginal delivery method using HIV1 trans-activator of transcription cell penetrating peptide fused with a Cre recombinase protein (TAT-Cre), local ablation of both p53 and Pten is achieved specifically in the uterus. These mice developed high-grade endometrial carcinomas and a high percentage of uterine carcinosarcomas resembling those found in humans. To further demonstrate that carcinosarcomas arise from epithelium, double Pten/p53 deficient epithelial cells are mixed with wild type stromal and myometrial cells and subcutaneously transplanted to Scid mice. All xenotransplants resulted in the development of uterine carcinosarcomas displaying high nuclear pleomorphism and metastatic potential. Accordingly, in vivo CRISPR/Cas9 disruption of Pten and p53 also triggered the development of metastatic carcinosarcomas. The results unfadingly demonstrate that simultaneous deletion of p53 and Pten in endometrial epithelial cells is enough to trigger epithelial to mesenchymal transition that is consistently translated to the formation of uterine carcinosarcomas in vivo.

Histone modifications in embryo implantation and placentation: insights from mouse models

Embryo implantation and placentation play pivotal roles in pregnancy by facilitating crucial maternal-fetal interactions. These dynamic processes involve significant alterations in gene expression profiles within the endometrium and trophoblast lineages. Epigenetics regulatory mechanisms, such as DNA methylation, histone modification, chromatin remodeling, and microRNA expression, act as regulatory switches to modulate gene activity, and have been implicated in establishing a successful pregnancy. Exploring the alterations in these epigenetic modifications can provide valuable insights for the development of therapeutic strategies targeting complications related to pregnancy. However, our current understanding of these mechanisms during key gestational stages remains incomplete. This review focuses on recent advancements in the study of histone modifications during embryo implantation and placentation, while also highlighting future research directions in this field.

A New Type of Endometrial Cancer Models in Mice Revealing the Functional Roles of Genetic Drivers and Exploring their Susceptibilities

Endometrial cancer (EC) is the most common female reproductive tract cancer and its incidence has been continuously increasing in recent years. The underlying mechanisms of EC tumorigenesis remain unclear, and efficient target therapies are lacking, for both of which feasible endometrial cancer animal models are essential but currently limited. Here, an organoid and genome editing-based strategy to generate primary, orthotopic, and driver-defined ECs in mice is reported. These models faithfully recapitulate the molecular and pathohistological characteristics of human diseases. The authors names these models and similar models for other cancers as organoid-initiated precision cancer models (OPCMs). Importantly, this approach can conveniently introduce any driver mutation or a combination of driver mutations. Using these models,it is shown that the mutations in Pik3ca and Pik3r1 cooperate with Pten loss to promote endometrial adenocarcinoma in mice. In contrast, the Kras G12D mutati led to endometrial squamous cell carcinoma. Then, tumor organoids are derived from these mouse EC models and performed high-throughput drug screening and validation. The results reveal distinct vulnerabilities of ECs with different mutations. Taken together, this study develops a multiplexing approach to model EC in mice and demonstrates its value for understanding the pathology of and exploring the potential treatments for this malignancy.

Development of adverse outcome pathways relevant for the identification of substances having endocrine disruption properties Uterine adenocarcinoma as adverse outcome

Development of adverse outcome pathways (AOPs) for uterine adenocarcinoma can provide a practical tool to implement the EFSA-ECHA Guidance (2018) for the identification of endocrine disruptors in the context of Regulations (EU) No 528/2012 and (EC) No 1107/2009. AOPs can give indications about the strength of the relationship between an adverse outcome (intended as a human health outcome) and chemicals (pesticides but not only) affecting the pathways. In this scientific opinion, the PPR Panel explored the development of AOPs for uterine adenocarcinoma. An evidence-based approach methodology was applied, and literature reviews were produced using a structured framework assuring transparency, objectivity, and comprehensiveness. Several AOPs were developed; these converged to a common critical node, that is increased estradiol availability in the uterus followed by estrogen receptor activation in the endometrium; therefore, a putative AOP network was considered. An uncertainty analysis and a probabilistic quantification of the weight of evidence have been carried out via expert knowledge elicitation for each set of MIEs/KEs/KERs included in individual AOPs. The collected data on the AOP network were evaluated qualitatively, whereas a quantitative uncertainty analysis for weight of the AOP network certainty has not been performed. Recommendations are provided, including exploring further the uncertainties identified in the AOPs and putative AOP network; further methodological developments for quantifying the certainty of the KERs and of the overall AOPs and AOP network; and investigating of NAMs applications in the context of some of the MIEs/KEs currently part of the putative AOP network developed.

Prss29 Cre recombinase mice are useful to study adult uterine gland function

All mammalian uteri contain glands in their endometrium that develop only or primarily after birth. In mice, those endometrial glands govern post implantation pregnancy establishment via regulation of blastocyst implantation, stromal cell decidualization, and placental development. Here, we describe a new uterine glandular epithelium (GE) specific Cre recombinase mouse line that is useful for the study of uterine gland function during pregnancy. Utilizing CRISPR-Cas9 genome editing, Cre recombinase was inserted into the endogenous serine protease 29 precursor (Prss29) gene. Both Prss29 mRNA and Cre recombinase activity was specific to the GE of the mouse uterus following implantation, but was absent from other areas of the female reproductive tract. Next, Prss29-Cre mice were crossed with floxed forkhead box A2 (Foxa2) mice to conditionally delete Foxa2 specifically in the endometrial glands. Foxa2 was absent in the glands of the post-implantation uterus, and Foxa2 deleted mice exhibited complete infertility after their first pregnancy. These results establish that Prss29-Cre mice are a valuable resource to elucidate and explore the functions of glands in the adult uterus.

Metabolic collateral lethal target identification reveals MTHFD2 paralogue dependency in ovarian cancer

Recurrent loss-of-function deletions cause frequent inactivation of tumour suppressor genes but often also involve the collateral deletion of essential genes in chromosomal proximity, engendering dependence on paralogues that maintain similar function. Although these paralogues are attractive anticancer targets, no methodology exists to uncover such collateral lethal genes. Here we report a framework for collateral lethal gene identification via metabolic fluxes, CLIM, and use it to reveal MTHFD2 as a collateral lethal gene in UQCR11-deleted ovarian tumours. We show that MTHFD2 has a non-canonical oxidative function to provide mitochondrial NAD+, and demonstrate the regulation of systemic metabolic activity by the paralogue metabolic pathway maintaining metabolic flux compensation. This UQCR11-MTHFD2 collateral lethality is confirmed in vivo, with MTHFD2 inhibition leading to complete remission of UQCR11-deleted ovarian tumours. Using CLIM's machine learning and genome-scale metabolic flux analysis, we elucidate the broad efficacy of targeting MTHFD2 despite distinct cancer genetic profiles co-occurring with UQCR11 deletion and irrespective of stromal compositions of tumours.

Clinical impact of STK11 mutation in advanced-stage non-small cell lung cancer

BACKGROUND

Mutations in STK11/LKB1 gene present a negative impact on tumour immune microenvironment, especially with concomitant activating KRAS mutation. These recent data may explain a decreased response to immunotherapy treatment in STK11 mutant non-small cell lung cancer (NSCLC).

OBJECTIVE

The primary objective is to evaluate, in a real-life setting, overall survival (OS) in patients with NSCLC according to the presence of STK11 mutation. The secondary objective is to assess time to treatment failure (TTF) for the first-line chemotherapy or immunotherapy.

METHODS

This observational multicentric study was conducted in Nouvelle-Aquitaine (France), for 24 months. Clinical, histopathological and imagery data were collected in each centre while the next-generation sequencing analysis was performed in Bordeaux Hospital University. Patient's data were longitudinally followed from NSCLC diagnosis date to the occurrence of censoring events (therapeutic failure or death, as applicable) or until the study end date.

RESULTS

median OS from the first drug administration was significantly longer for STK11^wt patients than STK11^mut patients (16.2 months [11 - nr] versus 4.7 months [2.5-9.4]; Log-rank test P < 0.001). The Presence of STK11 mutation was significantly associated with shortened OS (RR = 2.26 [1.35-3.79], P = 0.002). First-line TTF was significantly shorter in STK11^mut population and the presence of the mutation was significantly associated with an increase in treatment failures (RR = 1.87 [1.21-2.89], P = 0.005). The type of treatment (chemotherapy, immunotherapy) does not influence the amplitude of reduced TTF in patients with STK11^mut.

CONCLUSION

The presence of STK11 mutation is associated with poor prognosis in NSCLC.

Differences in the Active Endometrial Microbiota across Body Weight and Cancer in Humans and Mice

Simple Summary

Of all cancers, endometrial cancer has the greatest association with obesity. Obesity causes dysbiosis of intestinal microbiota, but little is known about whether obesity is associated with dysbiosis of the female genital tract. Therefore, the aim of this study was to determine whether obesity and cancer were associated with altered microbiota profiles in the endometrium. 16S rRNA transcript amplicon sequencing (which captures actively replicating bacteria) of endometrial tissues showed that obesity and cancer were associated with the prevalence of microbial community types in the human endometrium. However, obesity was not associated with microbial community types in the mouse endometrium. The presence of endometrial cancer (but not obesity) was associated with decreased abundance of the Lactobacillus genus in the human endometrium. In mice, an enrichment of Lactobacillus was associated with lower prevalence of disease (normal uterine histology). These results suggest that obesity and cancer may influence microbiota community types in the endometrium (at least in humans) and Lactobacillus may be protective in the endometrium. This study therefore supports further research into the role of microbiota in endometrial cancer development.

Abstract

Obesity is a risk factor for endometrial cancer. The aim of this study was to determine whether actively replicating microbiota in the endometrium differ between obese vs. lean and cancer vs. benign states. We performed 16S rRNA amplicon sequencing on endometrial tissues from lean and obese women with and without endometrial cancer, and lean and obese mice. Results displayed human endometrial microbiota clustered into three community types (R = 0.363, p = 0.001). Lactobacillus was dominant in community type 1 (C1) while community type 2 (C2) had high levels of Proteobacteria and more cancer samples when compared to C1 (p = 0.007) and C3 (p = 0.0002). A significant increase in the prevalence of the C2 community type was observed across body mass index and cancer (χ² = 14.24, p = 0.0002). The relative abundance of Lactobacillus was lower in cancer samples (p = 0.0043), and an OTU with 100% similarity to Lactobacillus iners was enriched in control samples (p = 0.0029). Mouse endometrial microbiota also clustered into three community types (R = 0.419, p = 0.001) which were not influenced by obesity. In conclusion, obesity and cancer are associated with community type prevalence in the human endometrium, and Lactobacillus abundance is associated with normal uterine histologies in humans and mice.

Non-phosphorylatable cyclin D1 mutant potentiates endometrial hyperplasia and drives carcinoma with Pten loss

Cyclin D1 is a regulatory subunit of -Cyclin Dependent Kinases 4 and 6 (CDK4/6) and regulates progression from G1 to S phase of the cell cycle. Dysregulated cyclin D1-CDK4/6 contributes to abnormal cell proliferation and tumor development. Phosphorylation of threonine 286 of cyclin D1 is necessary for ubiquitin-dependent degradation. Non-phosphorylatable cyclin D1 mutants are stabilized and concentrated in the nucleus, contributing to genomic instability and tumor development. Studies investigating the tumor-promoting functions of cyclin D1 mutants have focused on the use of artificial promoters to drive the expression which unfortunately may not accurately reflect tumorigenic functions of mutant cyclin D1 in cancer development. We have generated a conditional knock-in mouse model where cyclin D1T286A is expressed under the control of its endogenous promoter following Cre-dependent excision of a lox-stop-lox sequence. Acute expression of cyclin D1T286A following tamoxifen-inducible Cre recombinase triggers inflammation, lymphocyte abnormality and ultimately mesenteric tumors in the intestine. Tissue-specific expression of cyclin D1T286A in the uterus and endometrium cooperates with Pten loss to drive endometrial hyperplasia and cancer. Mechanistically, cyclin D1T286A mutant activates NF-κB signaling, augments inflammation, and contributes to tumor development. These results indicate that mutation of cyclin D1 at threonine 286 has a critical role in regulating inflammation and tumor development.

Two-Way Development of the Genetic Model for Endometrial Tumorigenesis in Mice: Current and Future Perspectives

Endometrial cancer (EC) is the most common malignancy of the female reproductive tract worldwide. Although comprehensive genomic analyses of EC have already uncovered many recurrent genetic alterations and deregulated signaling pathways, its disease model has been limited in quantity and quality. Here, we review the current status of genetic models for EC in mice, which have been developed in two distinct ways at the level of organisms and cells. Accordingly, we first describe the in vivo model using genetic engineering. This approach has been applied to only a subset of genes, with a primary focus on Pten inactivation, given that PTEN is the most frequently altered gene in human EC. In these models, the tissue specificity in genetic engineering determined by the Cre transgenic line has been insufficient. Consequently, the molecular mechanisms underlying EC development remain poorly understood, and preclinical models are still limited in number. Recently, refined Cre transgenic mice have been created to address this issue. With highly specific gene recombination in the endometrial cell lineage, acceptable in vivo modeling of EC development is warranted using these Cre lines. Second, we illustrate an emerging cell-based model. This hybrid approach comprises ex vivo genetic engineering of organoids and in vivo tumor development in immunocompromised mice. Although only a few successful cases have been reported as proof of concept, this approach allows quick and comprehensive analysis, ensuring a high potential for reconstituting carcinogenesis. Hence, ex vivo/in vivo hybrid modeling of EC development and its comparison with corresponding in vivo models may dramatically accelerate EC research. Finally, we provide perspectives on future directions of EC modeling.

Uterine kisspeptin receptor critically regulates epithelial estrogen receptor α transcriptional activity at the time of embryo implantation in a mouse model

Embryo implantation failure is a major cause of infertility in women of reproductive age and a better understanding of uterine factors that regulate implantation is required for developing effective treatments for female infertility. This study investigated the role of the uterine kisspeptin receptor (KISS1R) in the molecular regulation of implantation in a mouse model. To conduct this study, a conditional uterine knockout (KO) of Kiss1r was created using the Pgr-Cre (progesterone receptor-CRE recombinase) driver. Reproductive profiling revealed that while KO females exhibited normal ovarian function and mated successfully to stud males, they exhibited significantly fewer implantation sites, reduced litter size and increased neonatal mortality demonstrating that uterine KISS1R is required for embryo implantation and a healthy pregnancy. Strikingly, in the uterus of Kiss1r KO mice on day 4 (D4) of pregnancy, the day of embryo implantation, KO females exhibited aberrantly elevated epithelial ERα (estrogen receptor α) transcriptional activity. This led to the temporal misexpression of several epithelial genes [Cftr (Cystic fibrosis transmembrane conductance regulator), Aqp5 (aquaporin 5), Aqp8 (aquaporin 8) and Cldn7 (claudin 7)] that mediate luminal fluid secretion and luminal opening. As a result, on D4 of pregnancy, the lumen remained open disrupting the final acquisition of endometrial receptivity and likely accounting for the reduction in implantation events. Our data clearly show that uterine KISS1R negatively regulates ERα signaling at the time of implantation, in part by inhibiting ERα overexpression and preventing detrimentally high ERα activity. To date, there are no reports on the regulation of ERα by KISS1R; therefore, this study has uncovered an important and powerful regulator of uterine ERα during early pregnancy.

Feasibility and utility of MRI and dynamic 18F-FDG-PET in an orthotopic organoid-based patient-derived mouse model of endometrial cancer

BACKGROUND

Pelvic magnetic resonance imaging (MRI) and whole-body positron emission tomography-computed tomography (PET-CT) play an important role at primary diagnostic work-up and in detecting recurrent disease in endometrial cancer (EC) patients, however the preclinical use of these imaging methods is currently limited. We demonstrate the feasibility and utility of MRI and dynamic 18F-fluorodeoxyglucose (FDG)-PET imaging for monitoring tumor progression and assessing chemotherapy response in an orthotopic organoid-based patient-derived xenograft (O-PDX) mouse model of EC.

METHODS

18 O-PDX mice (grade 3 endometrioid EC, stage IIIC1), selectively underwent weekly T2-weighted MRI (total scans = 32), diffusion-weighted MRI (DWI) (total scans = 9) and dynamic 18F-FDG-PET (total scans = 26) during tumor progression. MRI tumor volumes (vMRI), tumor apparent diffusion coefficient values (ADCmean) and metabolic tumor parameters from 18F-FDG-PET including maximum and mean standard uptake values (SUVmax/SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG) and metabolic rate of 18F-FDG (MRFDG) were calculated. Further, nine mice were included in a chemotherapy treatment study (treatment; n = 5, controls; n = 4) and tumor ADCmean-values were compared to changes in vMRI and cellular density from histology at endpoint. A Mann-Whitney test was used to evaluate differences between groups.

RESULTS

Tumors with large tumor volumes (vMRI) had higher metabolic activity (MTV and TLG) in a clear linear relationship (r2 = 0.92 and 0.89, respectively). Non-invasive calculation of MRFDG from dynamic 18F-FDG-PET (mean MRFDG = 0.39 μmol/min) was feasible using an image-derived input function. Treated mice had higher tumor ADCmean (p = 0.03), lower vMRI (p = 0.03) and tumor cellular density (p = 0.02) than non-treated mice, all indicating treatment response.

CONCLUSION

Preclinical imaging mirroring clinical imaging methods in EC is highly feasible for monitoring tumor progression and treatment response in the present orthotopic organoid mouse model.

Different Cre systems induce differential microRNA landscapes and abnormalities in the female reproductive tracts of Dgcr8 conditional knockout mice

OBJECTIVES

The female reproductive tract comprises several different cell types. Using three representative Cre systems, we comparatively analysed the phenotypes of Dgcr8 conditional knockout (cKO) mice to understand the function of Dgcr8, involved in canonical microRNA biogenesis, in the female reproductive tract.

MATERIALS AND METHODS

Dgcr8f/f mice were crossed with Ltficre/+ , Amhr2cre/+ or PRcre/+ mice to produce mice deficient in Dgcr8 in epithelial (Dgcr8ed/ed ), mesenchymal (Dgcr8md/md ) and all the compartments (Dgcr8td/td ) in the female reproductive tract. Reproductive phenotypes were evaluated in Dgcr8 cKO mice. Uteri and/or oviducts were used for small RNA-seq, mRNA-seq, real-time RT-PCR, and/or morphologic and histological analyses.

RESULT

Dgcr8ed/ed mice did not exhibit any distinct defects, whereas Dgcr8md/md mice showed sub-fertility and oviductal smooth muscle deformities. Dgcr8td/td mice were infertile due to anovulation and acute inflammation in the female reproductive tract and suffered from an atrophic uterus with myometrial defects. The microRNAs and mRNAs related to immune modulation and/or smooth muscle growth were systemically altered in the Dgcr8td/td uterus. Expression profiles of dysregulated microRNAs and mRNAs in the Dgcr8td/td uterus were different from those in other genotypes in a Cre-dependent manner.

CONCLUSIONS

Dgcr8 deficiency with different Cre systems induces overlapping but distinct phenotypes as well as the profiles of microRNAs and their target mRNAs in the female reproductive tract, suggesting the importance of selecting the appropriate Cre driver to investigate the genes of interest.

Detecting survival-associated biomarkers from heterogeneous populations

Detection of prognostic factors associated with patients' survival outcome helps gain insights into a disease and guide treatment decisions. The rapid advancement of high-throughput technologies has yielded plentiful genomic biomarkers as candidate prognostic factors, but most are of limited use in clinical application. As the price of the technology drops over time, many genomic studies are conducted to explore a common scientific question in different cohorts to identify more reproducible and credible biomarkers. However, new challenges arise from heterogeneity in study populations and designs when jointly analyzing the multiple studies. For example, patients from different cohorts show different demographic characteristics and risk profiles. Existing high-dimensional variable selection methods for survival analysis, however, are restricted to single study analysis. We propose a novel Cox model based two-stage variable selection method called "Cox-TOTEM" to detect survival-associated biomarkers common in multiple genomic studies. Simulations showed our method greatly improved the sensitivity of variable selection as compared to the separate applications of existing methods to each study, especially when the signals are weak or when the studies are heterogeneous. An application of our method to TCGA transcriptomic data identified essential survival associated genes related to the common disease mechanism of five Pan-Gynecologic cancers.

LKB1 and cancer: The dual role of metabolic regulation

Liver kinase B1 (LKB1) is an essential serine/threonine kinase frequently associated with Peutz-Jeghers syndrome (PJS). In this review, we provide an overview of the role of LKB1 in conferring protection to cancer cells against metabolic stress and promoting cancer cell survival and invasion. This carcinogenic effect contradicts the previous conclusion that LKB1 is a tumor suppressor gene. Here we try to explain the contradictory effect of LKB1 on cancer from a metabolic perspective. Upon deletion of LKB1, cancer cells experience increased energy as well as oxidative stress, thereby causing genomic instability. Meanwhile, mutated LKB1 cooperates with other metabolic regulatory genes to promote metabolic reprogramming that subsequently facilitates adaptation to strong metabolic stress, resulting in development of a more aggressive malignant phenotype. We aim to specifically discuss the contradictory role of LKB1 in cancer by reviewing the mechanism of LKB1 with an emphasis on metabolic stress and metabolic reprogramming.

Sprr2f protects against renal injury by decreasing the level of reactive oxygen species in female mice

Renal injury leads to chronic kidney disease, with which women are not only more likely to be diagnosed than men but have poorer outcomes as well. We have previously shown that expression of small proline-rich region 2f (Sprr2f), a member of the small proline-rich region (Sprr) gene family, is increased several hundredfold after renal injury using a unilateral ureteral obstruction (UUO) mouse model. To better understand the role of Sprr2f in renal injury, we generated a Sprr2f knockout (Sprr2f-KO) mouse model using CRISPR-Cas9 technology. Sprr2f-KO female mice showed greater renal damage after UUO compared with wild-type (Sprr2f-WT) animals, as evidenced by higher hydroxyproline levels and denser collagen staining, indicating a protective role of Sprr2f during renal injury. Gene expression profiling by RNA sequencing identified 162 genes whose expression levels were significantly different between day 0 and day 5 after UUO in Sprr2f-KO mice. Of the 162 genes, 121 genes were upregulated after UUO and enriched with those involved in oxidation-reduction, a phenomenon not observed in Sprr2f-WT animals, suggesting a protective role of Sprr2f in UUO through defense against oxidative damage. Consistently, bilateral ischemia-reperfusion injury resulted in higher serum blood urea nitrogen levels and higher tissue reactive oxygen species in Sprr2f-KO compared with Sprr2f-WT female mice. Moreover, cultured renal epithelial cells from Sprr2f-KO female mice showed lower viability after oxidative damage induced by menadione compared with Sprr2f-WT cells that could be rescued by supplementation with reduced glutathione, suggesting that Sprr2f induction after renal damage acts as a defense against reactive oxygen species.

Evaluating the efficacy of enzalutamide and the development of resistance in a preclinical mouse model of type-I endometrial carcinoma

Androgen Receptor (AR) signaling is a critical driver of hormone-dependent prostate cancer and has also been proposed to have biological activity in female hormone-dependent cancers, including type I endometrial carcinoma (EMC). In this study, we evaluated the preclinical efficacy of a third-generation AR antagonist, enzalutamide, in a genetic mouse model of EMC, Sprr2f-Cre;Pten^fl/fl. In this model, ablation of Pten in the uterine epithelium leads to localized and distant malignant disease as observed in human EMC. We hypothesized that administering enzalutamide through the diet would temporarily decrease the incidence of invasive and metastatic carcinoma, while prolonged administration would result in development of resistance and loss of efficacy. Short-term treatment with enzalutamide reduced overall tumor burden through increased apoptosis but failed to prevent progression of invasive and metastatic disease. These results suggest that AR signaling may have biphasic, oncogenic and tumor suppressive roles in EMC that are dependent on disease stage. Enzalutamide treatment increased Progesterone Receptor (PR) expression within both stromal and tumor cell compartments. Prolonged administration of enzalutamide decreased apoptosis, increased tumor burden and resulted in the clonal expansion of tumor cells expressing high levels of p53 protein, suggestive of acquired Trp53 mutations. In conclusion, we show that enzalutamide induces apoptosis in EMC but has limited efficacy overall as a single agent. Induction of PR, a negative regulator of endometrial proliferation, suggests that adding progestin therapy to enzalutamide administration may further decrease tumor burden and result in a prolonged response.

A PoleP286R mouse model of endometrial cancer recapitulates high mutational burden and immunotherapy response

Cancer is instigated by mutator phenotypes, including deficient mismatch repair and p53-associated chromosomal instability. More recently, a distinct class of cancers was identified with unusually high mutational loads due to heterozygous amino acid substitutions (most commonly P286R) in the proofreading domain of DNA polymerase ε, the leading strand replicase encoded by POLE. Immunotherapy has revolutionized cancer treatment, but new model systems are needed to recapitulate high mutational burdens characterizing human cancers and permit study of mechanisms underlying clinical responses. Here, we show that activation of a conditional LSL-PoleP286R allele in endometrium is sufficient to elicit in all animals endometrial cancers closely resembling their human counterparts, including very high mutational burden. Diverse investigations uncovered potentially novel aspects of Pole-driven tumorigenesis, including secondary p53 mutations associated with tetraploidy, and cooperation with defective mismatch repair through inactivation of Msh2. Most significantly, there were robust antitumor immune responses with increased T cell infiltrates, accelerated tumor growth following T cell depletion, and unfailing clinical regression following immune checkpoint therapy. This model predicts that human POLE-driven cancers will prove consistently responsive to immune checkpoint blockade. Furthermore, this is a robust and efficient approach to recapitulate in mice the high mutational burdens and immune responses characterizing human cancers.

An immune competent orthotopic model of endometrial cancer with metastasis

Endometrial cancer is the most common gynecologic malignancy in the U.S. with metastatic disease remaining the major cause of patient death. Therapeutic strategies have remained essentially unchanged for decades. A significant barrier to progression in treatment modalities stems from a lack of clinically applicable in vivo models to accurately mimic endometrial cancer; specifically, ones that form distant metastases and maintain an intact immune system. To address this problem, we have established the first immune competent murine orthotopic tumor model for metastatic endometrial cancer by creating a green fluorescent protein labeled cell line from an endometrial cancer that developed in a Pgr ^cre/+ Pten ^f/f Kras ^G12D genetically engineered mouse. These cancer cells were grafted into the abraded uterine lumen of ovariectomized recipient mice treated with estrogen and subsequently developed local and metastatic endometrial tumors. We noted primary tumor formation in 59% mixed background and 86% of C57BL/6 animals at 4 weeks and distant lung metastases in 78% of mice after 2 months. This immunocompetent orthotopic tumor model closely resembles some human metastatic endometrial cancer, modeling both local metastasis and hematogenous spread to lung and has significant potential to advance the study of endometrial cancer and its metastasis.

PI3K Pathway Effectors pAKT and FOXO1 as Novel Markers of Endometrioid Intraepithelial Neoplasia

The diagnosis of endometrioid intraepithelial neoplasia (EIN) is challenging owing to limited sampling, hormonal status, and other confounding histologic variables. Markers such as PTEN or PAX2 can delineate EIN in some cases, but are not wholly reliable. Clearly, new markers of EIN are needed. We explored several potential markers of EIN based rationally on molecular pathways most frequently misregulated in endometrial cancer: the 3-phosphoinositide kinase (PI3K)/AKT, β-catenin, and mismatch repair pathways. We studied PTEN, PAX2, β-catenin, and MLH1, in conjunction with 2 new markers-FOXO1 and phosphorylated AKT (pAKT)-not previously investigated in EIN. Benign (n=14) and EIN (n=35) endometria were analyzed by immunohistochemistry. Staining patterns were interpreted, tabulated, and scored by "clonal distinctiveness" in neoplastic lesions; that is, pattern alterations relative to normal glands. In normal endometria, FOXO1 was cytoplasmic in proliferative phase, but nuclear in secretory phase, showing that PI3K/FOXO1 participates in endometrial cycling and that FOXO1 is a readout of PI3K status. pAKT expression was low across normal endometria. FOXO1 or pAKT expression was altered in the majority of EINs (27/35, 77%), with FOXO1 and pAKT being co-altered only in some (20/35, 57%). β-catenin or MLH1 also exhibited clonal distinctiveness in EINs, showing that these are also useful markers in some cases. This is the first study to demonstrate the potential of pAKT and FOXO1 as biomarkers in the histopathologic evaluation of EIN. However, variability in expression poses challenges in interpretation.

Imaging of Preclinical Endometrial Cancer Models for Monitoring Tumor Progression and Response to Targeted Therapy

Endometrial cancer is the most common gynecologic malignancy in industrialized countries. Most patients are cured by surgery; however, about 15% of the patients develop recurrence with limited treatment options. Patient-derived tumor xenograft (PDX) mouse models represent useful tools for preclinical evaluation of new therapies and biomarker identification. Preclinical imaging by magnetic resonance imaging (MRI), positron emission tomography-computed tomography (PET-CT), single-photon emission computed tomography (SPECT) and optical imaging during disease progression enables visualization and quantification of functional tumor characteristics, which may serve as imaging biomarkers guiding targeted therapies. A critical question, however, is whether the in vivo model systems mimic the disease setting in patients to such an extent that the imaging biomarkers may be translatable to the clinic. The primary objective of this review is to give an overview of current and novel preclinical imaging methods relevant for endometrial cancer animal models. Furthermore, we highlight how these advanced imaging methods depict pathogenic mechanisms important for tumor progression that represent potential targets for treatment in endometrial cancer.

Fbxw7 is a driver of uterine carcinosarcoma by promoting epithelial-mesenchymal transition

Uterine carcinosarcoma (UCS) is an aggressive endometrial cancer variant distinguished from endometrial adenocarcinoma (EC) by admixed malignant epithelial and mesenchymal components (carcinoma and sarcoma). The molecular events underlying UCS are enigmatic, as cancer gene mutations are generally shared among UCS/EC. We take advantage of genetic approaches in mice to show that inactivation of Fbxw7 and Pten results in UCS through spontaneous acquisition of mutations in a third gene (Tp53), arguing for strong biological selection and synergism in UCS. We used this UCS model including tumor-derived cell lines to show that Fbxw7 loss drives epithelial–mesenchymal transition, explaining Fbxw7’s role in UCS. This model system argues that simultaneous genetic defects in 3 distinct pathways (Fbxw7, Pten/PI3K, Tp53) converge in UCS genesis.

Uterine carcinosarcoma is an aggressive variant of endometrial carcinoma characterized by unusual histologic features including discrete malignant epithelial and mesenchymal components (carcinoma and sarcoma). Recent studies have confirmed a monoclonal origin, and comprehensive genomic characterizations have identified mutations such as Tp53 and Pten. However, the biological origins and specific combination of driver events underpinning uterine carcinosarcoma have remained mysterious. Here, we explored the role of the tumor suppressor Fbxw7 in endometrial cancer through defined genetic model systems. Inactivation of Fbxw7 and Pten resulted in the formation of precancerous lesions (endometrioid intraepithelial neoplasia) and well-differentiated endometrioid adenocarcinomas. Surprisingly, all adenocarcinomas eventually developed into definitive uterine carcinosarcomas with carcinomatous and sarcomatous elements including heterologous differentiation, yielding a faithful genetically engineered model of this cancer type. Genomic analysis showed that most tumors spontaneously acquired Trp53 mutations, pointing to a triad of pathways (p53, PI3K, and Fbxw7) as the critical combination underpinning uterine carcinosarcoma, and to Fbxw7 as a key driver of this enigmatic endometrial cancer type. Lineage tracing provided formal genetic proof that the uterine carcinosarcoma cell of origin is an endometrial epithelial cell that subsequently undergoes a prominent epithelial–mesenchymal transition underlying the attainment of a highly invasive phenotype specifically driven by Fbxw7.

LKB1/AMPK Pathway and Drug Response in Cancer: A Therapeutic Perspective

Inactivating mutations of the tumor suppressor gene Liver Kinase B1 (LKB1) are frequently detected in non-small-cell lung cancer (NSCLC) and cervical carcinoma. Moreover, LKB1 expression is epigenetically regulated in several tumor types. LKB1 has an established function in the control of cell metabolism and oxidative stress. Clinical and preclinical studies support a role of LKB1 as a central modifier of cellular response to different stress-inducing drugs, suggesting LKB1 pathway as a highly promising therapeutic target. Loss of LKB1-AMPK signaling confers sensitivity to energy depletion and to redox homeostasis impairment and has been associated with an improved outcome in advanced NSCLC patients treated with chemotherapy. In this review, we provide an overview of the interplay between LKB1 and its downstream targets in cancer and focus on potential therapeutic strategies whose outcome could depend from LKB1.

Efficacy of molecularly targeted agents given in the randomised trial SHIVA01 according to the ESMO Scale for Clinical Actionability of molecular Targets

BACKGROUND

A randomised trial SHIVA01 compared the efficacy of matched molecularly targeted therapy outside their indications based on a prespecified treatment algorithm versus conventional chemotherapy in patients with metastatic solid tumours who had failed standard of care. No statistical difference was reported between the two groups in terms of progression-free survival (PFS), challenging treatment algorithm. The European Society for Medical Oncology (ESMO) Scale for Clinical Actionability of molecular Targets (ESCAT) recently defined criteria to prioritise molecular alterations (MAs) to select anticancer drugs. We aimed to retrospectively evaluate the efficacy of matched molecularly targeted agents (MTAs) given in SHIVA01 according to ESCAT tiers.

PATIENTS AND METHODS

MAs used in SHIVA01 were retrospectively classified into ESCAT tiers, and PFS and overall survival (OS) were compared using log-rank tests.

RESULTS

One hundred fifty-three patients were treated with matched MTAs in SHIVA01. MAs used to allocate MTAs were classified into tiers II, IIIA, IIIB and IVA according to the ESCAT. Median PFS was 2.0 months in tier II, 3.1 in tier IIIA, 1.7 in tier IIIB and 3.2 in tier IVA (p = 0.13). Median OS in tier IIIB was worse than that in tiers II, IIIA and IVA (6.3 months versus 11.7, 11.2 and 12.1, p = 0.002).

CONCLUSIONS

Most MAs used to allocate therapy in SHIVA01 were shown to improve outcomes in other tumour types (tier IIIA). Worst outcome was observed in patients treated based on another type of alteration than the one reported to improve outcomes (tier IIIB), highlighting the crucial impact of the type of the alterations beyond the gene and the signalling pathway.

Reversal of obesity-driven aggressiveness of endometrial cancer by metformin

BACKGROUND

Obesity and diabetes are associated with increased risk and worse outcomes for endometrial cancer. Metformin is a widely prescribed generic drug for the treatment of type II diabetes and metabolic syndrome and may also have anti-tumorigenic effects. Thus, we assessed the metabolic anti-tumorigenic effects of metformin in (1) human endometrial cancer cell lines under varying glucose concentrations, and (2) a novel genetically engineered mouse model of endometrioid endometrial cancer under obese and lean conditions.

METHODS

The effects of metformin on cytotoxicity, apoptosis, cell cycle progression, and the AMPK/mTOR/S6 and MAPK pathways were assessed in ECC-1 and Ishikawa cells under low, normal and high glucose conditions. The impact of metformin treatment on tumor growth under obese and lean conditions was evaluated using a novel LKB1^fl/fl p53^fl/fl mouse model of endometrial cancer. Global, untargeted metabolomics was used to identify (1) obesity-associated differences between endometrial tumors and (2) the obesity-dependent effects of metformin in the endometrial tumors.

RESULTS

Hypoglycemic conditions significantly enhanced the sensitivity of the cells to metformin in regards to its anti-proliferative and apoptotic effects, as compared to hyperglycemic and normal glucose conditions. Metformin inhibited tumor growth in both the obese and lean mice, which metformin-induced inhibition of tumor progression in obese mice was significantly greater than in lean mice. Metabolomic profiling in endometrial cancer tissues revealed significant differences between obese- and lean-mice. Enhanced energy metabolism was seen in obese- versus lean-mice as evidenced by increases in glycolytic and oxidative phosphorylation intermediates. In addition, dramatic increases in lipid biosynthesis and lipid peroxidation were found in the obese- versus lean-mice, whereas metformin obviously reversed the obesity-driven upregulation of lipid and protein biosynthesis in the obese mice.

CONCLUSIONS

The obese state promoted tumor aggressiveness in the LKB1^fl/fl p53^fl/fl mouse model, accompanied by increases in energy metabolism, lipid biosynthesis, and markers of lipid peroxidation. Metformin had increased efficacy against endometrial cancer in obese versus lean mice and reversed the detrimental metabolic effects of obesity in the endometrial tumors. Taken together, it is likely that the unique metabolic milieu underlies metformin's improved efficacy in treating endometrial cancer which develop in an obese host environment.

Patient-derived organoids from endometrial disease capture clinical heterogeneity and are amenable to drug screening

Endometrial disorders represent a major gynaecological burden. Current research models fail to recapitulate the nature and heterogeneity of these diseases, thereby hampering scientific and clinical progress. Here we developed long-term expandable organoids from a broad spectrum of endometrial pathologies. Organoids from endometriosis show disease-associated traits and cancer-linked mutations. Endometrial cancer-derived organoids accurately capture cancer subtypes, replicate the mutational landscape of the tumours and display patient-specific drug responses. Organoids were also established from precancerous pathologies encompassing endometrial hyperplasia and Lynch syndrome, and inherited gene mutations were maintained. Endometrial disease organoids reproduced the original lesion when transplanted in vivo. In summary, we developed multiple organoid models that capture endometrial disease diversity and will provide powerful research models and drug screening and discovery tools.

Loss of FGL1 induces epithelial‑mesenchymal transition and angiogenesis in LKB1 mutant lung adenocarcinoma

Liver kinase b1 (LKB1) is a tumor suppressor, and the inactivated mutation frequency of LKB1 in lung adenocarcinoma is ~20%. The present study aimed to explore potential novel biomarkers in LKB1 mutant lung adenocarcinoma. Gene expression data from lung adenocarcinoma patients were downloaded from The Cancer Genome Atlas and the Gene Expression Omnibus databases. R software was used to analyze the gene expression profiles. Reverse transcription‑quantitative PCR (RT‑qPCR), western blot and immunohistochemistry (IHC) analyses were used to examine gene expression and function. Gene function was further explored via gene set enrichment analysis. A colony formation assay was used to evaluate cell proliferation. A wound‑healing assay and immunofluorescence analysis were used to evaluate cell migration and epithelial‑mesenchymal transition (EMT), respectively. Wound healing assay, immunofluorescence, western blot, RT‑qPCR and IHC results for EMT‑associated markers demonstrated that a loss of fibrinogen‑like 1 (FGL1) induced EMT in LKB1 mutant lung adenocarcinoma. RT‑qPCR and IHC analyses of angiogenesis‑related markers revealed that loss of FGL1 promoted angiogenesis in LKB1 mutant lung adenocarcinoma. Overall, the present results demonstrated that loss of FGL1 induced EMT and angiogenesis in LKB1 mutant lung adenocarcinoma. FGL1 may be a novel biomarker to indicate EMT and angiogenesis in patients with LKB1 mutant lung adenocarcinoma.

The Effect of LKB1 Activity on the Sensitivity to PI3K/mTOR Inhibition in Non-Small Cell Lung Cancer

INTRODUCTION

Liver kinase B1 (LKB1), also called serine/threonine kinase 11 (STK11), is a tumor suppressor that functions as master regulator of cell growth, metabolism, survival, and polarity. Approximately 30% to 35% of patients with NSCLC possess inactivated liver kinase B1 gene (LKB1), and these patients respond poorly to anti-programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) immunotherapy. Therefore, novel therapies targeting NSCLC with LKB1 loss are needed.

METHODS

We used a new in silico signaling analysis method to identify the potential therapeutic targets and reposition drugs by integrating gene expression data with the Kyoto Encyclopedia of Genes and Genomes signaling pathways. LKB1 wild-type and LKB1-deficient NSCLC cell lines, including knockout clones generated by clustered regularly interspaced short pallindromic repeats-Cas9, were treated with inhibitors of mechanistic target of rapamycin kinase (mTOR) and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and a dual inhibitor.

RESULTS

In silico experiments showed that inhibition of both mTOR and PI3K can be synergistically effective in LKB1-deficient NSCLC. In vitro and in vivo experiments showed the synergistic effect of mTOR inhibition and PI3K inhibition in LKB1-mutant NSCLC cell lines. The sensitivity to dual inhibition of mTOR and PI3K is higher in LKB1-mutant cell lines than in wild-type cell lines. A higher compensatory increase in Akt phosphorylation after rapamycin treatment of LKB1-deficient cells than after rapamycin treatment of LKB1 wild-type cells is responsible for the synergistic effect of mTOR and PI3K inhibition. Dual inhibition of mTOR and PI3K resulted in a greater decrease in protein expression of cell cycle-regulating proteins in LKB1 knockout cells than in LKB1 wild-type cells.

CONCLUSION

Dual molecular targeted therapy for mTOR and PI3K may be a promising therapeutic strategy in the specific population of patients with lung cancer with LKB1 loss.

The benefits of adding metformin to tamoxifen to protect the endometrium-A randomized placebo-controlled trial

BACKGROUND

We investigated whether metformin prevents tamoxifen-induced endometrial changes and insulin resistance (IR) after a diagnosis of breast cancer.

METHODS

This was a single-centre, randomized, double-blind, placebo-controlled, parallel group trial. Postmenopausal women with hormone receptor-positive breast cancer taking tamoxifen were randomly allocated to metformin 850 mg or identical placebo, twice daily, for 52 weeks. Outcome measures included double endometrial thickness (ET) measured by transvaginal ultrasound, fasting insulin, glucose and IR estimated by the homeostasis model of assessment (HOMA-IR).

RESULTS

A total of 112 women were screened and 102 randomized. Results are presented as median (range). The 101 women who took at least one dose of medication were aged 56 (43-72) years, with 5(0.5-28) years postmenopause, and had taken tamoxifen for 28.9 (0-367.4) weeks. The baseline ET was 2.9 mm (1.4-21.9) for the placebo group (n = 52) and 2.5 mm (1.3-14.8) for the metformin group (n = 50). At 52 weeks, the median ET was statistically significantly lower for the metformin (n = 36) than for the placebo group (n = 45) (2.3 mm (1.4-7.8) vs 3.0 (1.2-11.3); P = 0.05). 13.3% allocated to placebo had an ET greater than 4 mm vs 5.7% for metformin (P = 0.26). There was no endometrial atypia or cancer. Compared with placebo, metformin resulted in significantly greater baseline-adjusted reductions in weight (P < 0.001), waist circumference (0.03) and HOMA-IR (P < 0.001).

CONCLUSIONS

Metformin appears to inhibit tamoxifen-induced endometrial changes and has favourable metabolic effects. Further research into the adjuvant use of metformin after breast cancer and to prevent EH and cancer is warranted.

SOX17 regulates uterine epithelial-stromal cross-talk acting via a distal enhancer upstream of Ihh

Mammalian pregnancy depends on the ability of the uterus to support embryo implantation. Previous studies reveal the Sox17 gene as a downstream target of the Pgr-Gata2-dependent transcription network that directs genomic actions in the uterine endometrium receptive for embryo implantation. Here, we report that ablating Sox17 in the uterine epithelium impairs leukemia inhibitory factor (LIF) and Indian hedgehog homolog (IHH) signaling, leading to failure of embryo implantation. In vivo deletion of the SOX17-binding region 19 kb upstream of the Ihh locus by CRISPR-Cas technology reduces Ihh expression specifically in the uterus and alters proper endometrial epithelial-stromal interactions, thereby impairing pregnancy. This SOX17-binding interval is also bound by GATA2, FOXA2, and PGR. This cluster of transcription factor binding is common in 737 uterine genes and may represent a key regulatory element essential for uterine epithelial gene expression.

Molecular Genetics of Endometrial Carcinoma

Endometrial cancer is the most commonly diagnosed gynecologic malignancy in the United States. Endometrioid endometrial carcinomas constitute approximately 85% of newly diagnosed cases; serous carcinomas represent approximately 3-10% of diagnoses; clear cell carcinoma accounts for <5% of diagnoses; and uterine carcinosarcomas are rare, biphasic tumors. Longstanding molecular observations implicate PTEN inactivation as a major driver of endometrioid carcinomas; TP53 inactivation as a major driver of most serous carcinomas, some high-grade endometrioid carcinomas, and many uterine carcinosarcomas; and inactivation of either gene as drivers of some clear cell carcinomas. In the past decade, targeted gene and exome sequencing have uncovered additional pathogenic aberrations in each histotype. Moreover, an integrated genomic analysis by The Cancer Genome Atlas (TCGA) resulted in the molecular classification of endometrioid and serous carcinomas into four distinct subgroups, POLE (ultramutated), microsatellite instability (hypermutated), copy number low (endometrioid), and copy number high (serous-like). In this review, we provide an overview of the major molecular features of the aforementioned histopathological subtypes and TCGA subgroups and discuss potential prognostic and therapeutic implications for endometrial carcinoma.

The uterine epithelial loss of Pten is inefficient to induce endometrial cancer with intact stromal Pten

Mutation of the tumor suppressor Pten often leads to tumorigenesis in various organs including the uterus. We previously showed that Pten deletion in the mouse uterus using a Pgr-Cre driver (Ptenf/fPgrCre/+) results in rapid development of endometrial carcinoma (EMC) with full penetration. We also reported that Pten deletion in the stroma and myometrium using Amhr2-Cre failed to initiate EMC. Since the Ptenf/fPgrCre/+ uterine epithelium was primarily affected by tumorigenesis despite its loss in both the epithelium and stroma, we wanted to know if Pten deletion in epithelia alone will induce tumorigenesis. We found that mice with uterine epithelial loss of Pten under a Ltf-iCre driver (Ptenf/f/LtfCre/+) develop uterine complex atypical hyperplasia (CAH), but rarely EMC even at 6 months of age. We observed that Ptenf/fPgrCre/+ uteri exhibit a unique population of cytokeratin 5 (CK5) and transformation related protein 63 (p63)-positive epithelial cells; these cells mark stratified epithelia and squamous differentiation. In contrast, Ptenf/fLtfCre/+ hyperplastic epithelia do not undergo stratification, but extensive epithelial cell apoptosis. This increased apoptosis is associated with elevation of TGFβ levels and activation of downstream effectors, SMAD2/3 in the uterine stroma. Our results suggest that stromal PTEN via TGFβ signaling restrains epithelial cell transformation from hyperplasia to carcinoma. In conclusion, this study, using tissue-specific deletion of Pten, highlights the epithelial-mesenchymal cross-talk in the genesis of endometrial carcinoma.

Modeling Endometrial Cancer: Past, Present, and Future

Endometrial cancer is the most common type of cancer of the female reproductive tract. Although prognosis is generally good for patients with low-grade and early-stage diseases, the outcomes for high-grade and metastatic/recurrent cases remain poor, since traditional chemotherapy regimens based on platinum and taxanes have limited effects. No targeted agents have been approved so far, although several new drugs have been tested without striking results in clinical trials. Over the last decades, many efforts have been made towards the establishment and development of preclinical models, aiming at recapitulating the structural and molecular determinants of the disease. Here, we present an overview of the most commonly used in vitro and in vivo models and discuss their peculiar features, describing their main applications and the value in the advancement of both fundamental and translational endometrial cancer research.

MIG-6 suppresses endometrial epithelial cell proliferation by inhibiting phospho-AKT

Background

Aberrant hyperactivation of epithelial proliferation, AKT signaling, and association with unopposed estrogen (E2) exposure is the most common endometrial cancer dysfunction. In the normal uterus, progesterone (P4) inhibits proliferation by coordinating stromal-epithelial cross-talk, which we previously showed is mediated by the function of Mitogen-inducible gene 6 (Mig-6). Despite their attractive characteristics, non-surgical conservative therapies based on progesterone alone have not been universally successful. One barrier to this success has been the lack of understanding of the P4 effect on endometrial cells.

Method

To further understand the role of Mig-6 and P4 in controlling uterine proliferation, we developed a Sprr2f-cre driven mouse model where Mig-6 is specifically ablated only in the epithelial cells of the uterus (Sprr2f^cre+Mig-6^f/f). We examined P4 effect and regulation of AKT signaling in the endometrium of mutant mice.

Results

Sprr2f^cre+Mig-6^f/f mice developed endometrial hyperplasia. P4 treatment abated the development of endometrial hyperplasia and restored morphological and histological characteristics of the uterus. P4 treatment reduced cell proliferation which was accompanied by decreased AKT signaling and the restoration of stromal PGR and ESR1 expression. Furthermore, our in vitro studies revealed an inhibitory effect of MIG-6 on AKT phosphorylation as well as MIG-6 and AKT protein interactions.

Conclusions

These data suggest that endometrial epithelial cell proliferation is regulated by P4 mediated Mig-6 inhibition of AKT phosphorylation, uncovering new mechanisms of P4 action. This information may help guide more effective non-surgical interventions in the future.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4502-7) contains supplementary material, which is available to authorized users.

MIG-6 negatively regulates STAT3 phosphorylation in uterine epithelial cells

Endometrial cancer is the most common malignancy of the female genital tract. Progesterone (P4) has been used for several decades in endometrial cancer treatment, especially in women who wish to retain fertility. However, it is unpredictable which patients will respond to P4 treatment and which may have a P4 resistant cancer. Therefore, identifying the mechanism of P4 resistance is essential to improve the therapies for endometrial cancer. Mitogen-inducible gene 6 (Mig-6) is a critical mediator of progesterone receptor (PGR) action in the uterus. In order to study the function of Mig-6 in P4 resistance, we generated a mouse model in which we specifically ablated Mig-6 in uterine epithelial cells using Sprr2f-cre mice (Sprr2f^cre+Mig-6^f/f). Female mutant mice develop endometrial hyperplasia due to aberrant phosphorylation of STAT3 and proliferation of the endometrial epithelial cells. The results from our immunoprecipitation and cell culture experiments showed that MIG-6 inhibited phosphorylation of STAT3 via protein interactions. Our previous study showed P4 resistance in mice with Mig-6 ablation in Pgr positive cells (Pgr^cre/+Mig-6^f/f). However, Sprr2f^cre+Mig-6^f/f mice were P4 responsive. P4 treatment significantly decreased STAT3 phosphorylation and epithelial proliferation in the uterus of mutant mice. We showed that Mig-6 has an important function of tumor suppressor via inhibition of STAT3 phosphorylation in uterine epithelial cells and the anti-tumor effects of P4 are mediated by the endometrial stroma. This data helps to develop a new signaling pathway in the regulation of steroid hormones in the uterus, and to overcome P4 resistance in human reproductive diseases, such as endometrial cancer.

LKB1 as a Tumor Suppressor in Uterine Cancer: Mouse Models and Translational Studies

The LKB1 tumor suppressor was identified in 1998 as the gene mutated in the Peutz-Jeghers Syndrome (PJS), a hereditary cancer predisposition characterized by gastrointestinal polyposis and a high incidence of cancers, particularly carcinomas, at a variety of anatomic sites including the gastrointestinal tract, lung, and female reproductive tract. Women with PJS have a high incidence of carcinomas of the uterine corpus (endometrium) and cervix. The LKB1 gene is also somatically mutated in human cancers arising at these sites. Work in mouse models has highlighted the potency of LKB1 as an endometrial tumor suppressor and its distinctive roles in driving invasive and metastatic growth. These in vivo models represent tractable experimental systems for the discovery of underlying biological principles and molecular processes regulated by LKB1 in the context of tumorigenesis and also serve as useful preclinical model systems for experimental therapeutics. Here we review LKB1's known roles in mTOR signaling, metabolism, and cell polarity, with an emphasis on human pathology and mouse models relevant to uterine carcinogenesis, including cancers of the uterine corpus and cervix.

Tissue-Specific Ablation of the LIF Receptor in the Murine Uterine Epithelium Results in Implantation Failure

The cytokine leukemia inhibitory factor (LIF) is essential for rendering the uterus receptive for blastocyst implantation. In mice, LIF receptor expression (LIFR) is largely restricted to the uterine luminal epithelium (LE). LIF, secreted from the endometrial glands (GEs), binds to the LIFR, activating the Janus kinase-signal transducer and activation of transcription (STAT) 3 (Jak-Stat3) signaling pathway in the LE. JAK-STAT activation converts the LE to a receptive state so that juxtaposed blastocysts begin to implant. To specifically delete the LIFR in the LE, we derived a line of mice in which Cre recombinase was inserted into the endogenous lactoferrin gene (Ltf-Cre). Lactoferrin expression in the LE is induced by E2, and we demonstrate that Cre recombinase activity is restricted to the LE and GE. To determine the requirement of the LIFR in implantation, we derived an additional mouse line carrying a conditional (floxed) Lifrflx/flx gene. Crossing Ltf-Cre mice with Lifrflx/flx mice generated Lifrflx/Δ:LtfCre/+ females that were overtly normal but infertile. Many of these females, despite repeated matings, did not become pregnant. Unimplanted blastocysts were recovered from the Lifrflx/Δ:LtfCre/+ uteri and, when transferred to wild-type recipients, implanted normally, indicating that uterine receptivity rather than the embryo's competency is compromised. The loss of Lifr results in both the failure for STAT3 to translocate to the LE nuclei and a reduction in the expression of the LIF regulated gene Msx1 that regulates uterine receptivity. These results reveal that uterine expression of the LIFR is essential for embryo implantation and further define the components of the LIF signaling pathway necessary for effective implantation.

Development of organoids from mouse and human endometrium showing endometrial epithelium physiology and long-term expandability

The endometrium, which is of crucial importance for reproduction, undergoes dynamic cyclic tissue remodeling. Knowledge of its molecular and cellular regulation is poor, primarily owing to a lack of study models. Here, we have established a novel and promising organoid model from both mouse and human endometrium. Dissociated endometrial tissue, embedded in Matrigel under WNT-activating conditions, swiftly formed organoid structures that showed long-term expansion capacity, and reproduced the molecular and histological phenotype of the tissue's epithelium. The supplemented WNT level determined the type of mouse endometrial organoids obtained: high WNT yielded cystic organoids displaying a more differentiated phenotype than the dense organoids obtained in low WNT. The organoids phenocopied physiological responses of endometrial epithelium to hormones, including increased cell proliferation under estrogen and maturation upon progesterone. Moreover, the human endometrial organoids replicated the menstrual cycle under hormonal treatment at both the morpho-histological and molecular levels. Together, we established an organoid culture system for endometrium, reproducing tissue epithelium physiology and allowing long-term expansion. This novel model provides a powerful tool for studying mechanisms underlying the biology as well as the pathology of this key reproductive organ.

Judicious Toggling of mTOR Activity to Combat Insulin Resistance and Cancer: Current Evidence and Perspectives

The mechanistic target of rapamycin (mTOR), via its two distinct multiprotein complexes, mTORC1, and mTORC2, plays a central role in the regulation of cellular growth, metabolism, and migration. A dysregulation of the mTOR pathway has in turn been implicated in several pathological conditions including insulin resistance and cancer. Overactivation of mTORC1 and disruption of mTORC2 function have been reported to induce insulin resistance. On the other hand, aberrant mTORC1 and mTORC2 signaling via either genetic alterations or increased expression of proteins regulating mTOR and its downstream targets have contributed to cancer development. These underlined the attractiveness of mTOR as a therapeutic target to overcome both insulin resistance and cancer. This review summarizes the evidence supporting the notion of intermittent, low dose rapamycin for treating insulin resistance. It further highlights recent data on the continuous use of high dose rapamycin analogs and related second generation mTOR inhibitors for cancer eradication, for overcoming chemoresistance and for tumor stem cell suppression. Within these contexts, the potential challenges associated with the use of mTOR inhibitors are also discussed.

Conditional deletion of Sox17 reveals complex effects on uterine adenogenesis and function

The importance of canonical Wnt signaling to murine uterine development is well established. Mouse models in which uterine-specific Wnt ligands, β-catenin, or Lef1 are disrupted result in failure of postnatal endometrial gland development. Sox17 is a transcription factor characterized in numerous tissues as an antagonist of Wnt signaling. Thus, we hypothesized that conditional ablation of Sox17 would lead to hyperproliferation of endometrial glands in mice. Contrary to our prediction, disruption of Sox17 in epithelial and stromal compartments led to inhibition of endometrial adenogenesis and a loss of reproductive capacity. Epithelium-specific Sox17 disruption resulted in normal adenogenesis although reproductive capacity remained impaired. These findings suggest that non-epithelial, Sox17-positive cells are necessary for adenogenesis and that glands require Sox17 to properly function. To our knowledge, these findings are the first to implicate Sox17 in endometrial gland formation and reproductive success. The data presented herein underscore the importance of studying Sox17 in uterine homeostasis and function.

Somatic PIK3CA mutations as a driver of sporadic venous malformations

Venous malformations (VM) are vascular malformations characterized by enlarged and distorted blood vessel channels. VM grow over time and cause substantial morbidity because of disfigurement, bleeding, and pain, representing a clinical challenge in the absence of effective treatments (Nguyenet al, 2014; Uebelhoeret al, 2012). Somatic mutations may act as drivers of these lesions, as suggested by the identification of TEK mutations in a proportion of VM (Limayeet al, 2009). We report that activating PIK3CA mutations gives rise to sporadic VM in mice, which closely resemble the histology of the human disease. Furthermore, we identified mutations in PIK3CA and related genes of the PI3K (phosphatidylinositol 3-kinase)/AKT pathway in about 30% of human VM that lack TEK alterations. PIK3CA mutations promote downstream signaling and proliferation in endothelial cells and impair normal vasculogenesis in embryonic development. We successfully treated VM in mouse models using pharmacological inhibitors of PI3Kα administered either systemically or topically. This study elucidates the etiology of a proportion of VM and proposes a therapeutic approach for this disease.

Energy sensing and cancer: LKB1 function and lessons learnt from Peutz-Jeghers syndrome

We describe in this review increasing evidence that loss of LKB1 kinase in Peutz-Jeghers syndrome (PJS) derails the existing natural balance between cell survival and tumour growth suppression. LKB1 deletion can plunge cells into an energy/oxidative stress-induced crisis which leads to the activation of alternative and often carcinogenic pathways to maintain cellular energy levels. It therefore appears that although LKB1 deficiency can suppress oncogenic transformation in the short term, it can ultimately lead to more progressed and malignant phenotypes by driving abnormal cell differentiation, genomic instability and increased tumour heterogeneity.

Tumor progression, metastasis, and modulators of epithelial-mesenchymal transition in endometrioid endometrial carcinoma: an update

Endometrioid endometrial carcinoma (EEC), also known as type 1 endometrial cancer (EC), accounts for over 70-80% of all cases that are usually associated with estrogen stimulation and often develops in a background of atypical endometrial hyperplasia. The increased incidence of EC is mainly confined to this type of cancer. Most EEC patients present at an early stage and generally have a favorable prognosis; however, up to 30% of EEC present as high risk tumors, which have invaded deep into the myometrium at diagnosis and progressively lead to local or extra pelvic metastasis. The poor survival of advanced EC is related to the lack of effective therapies, which can be attributed to poor understanding of the molecular mechanisms underlying the progression of disease toward invasion and metastasis. Multiple lines of evidence illustrate that epithelial-mesenchymal transition (EMT)-like events are central to tumor progression and malignant transformation, endowing the incipient cancer cell with invasive and metastatic properties. The aim of this review is to summarize the current knowledge on molecular events associated with EMT in progression, invasion, and metastasis of EEC. Further, the role of epigenetic modifications and microRNA regulation, tumor microenvironment, and microcystic elongated and fragmented glands like invasion pattern have been discussed. We believe this article may perhaps stimulate further research in this field that may aid in identifying high risk patients within this clinically challenging patient group and also lead to the recognition of novel targets for the prevention of metastasis - the most fatal consequence of endometrial carcinogenesis.

Noncatalytic PTEN missense mutation predisposes to organ-selective cancer development in vivo

Caserta et al. generated and analyzed Pten knock-in mice harboring a C2 domain missense mutation at phenylalanine 341 (PtenFV), found in human cancer. This PTEN noncatalytic missense mutation exposes a core tumor suppressor function distinct from inhibition of canonical AKT signaling that predisposes to organ-selective cancer development in vivo.

Inactivation of phosphatase and tensin homology deleted on chromosome 10 (PTEN) is linked to increased PI3K–AKT signaling, enhanced organismal growth, and cancer development. Here we generated and analyzed Pten knock-in mice harboring a C2 domain missense mutation at phenylalanine 341 (Pten^FV), found in human cancer. Despite having reduced levels of PTEN protein, homozygous Pten^FV/FV embryos have intact AKT signaling, develop normally, and are carried to term. Heterozygous Pten^FV/+ mice develop carcinoma in the thymus, stomach, adrenal medulla, and mammary gland but not in other organs typically sensitive to Pten deficiency, including the thyroid, prostate, and uterus. Progression to carcinoma in sensitive organs ensues in the absence of overt AKT activation. Carcinoma in the uterus, a cancer-resistant organ, requires a second clonal event associated with the spontaneous activation of AKT and downstream signaling. In summary, this PTEN noncatalytic missense mutation exposes a core tumor suppressor function distinct from inhibition of canonical AKT signaling that predisposes to organ-selective cancer development in vivo.

LKB1 loss promotes endometrial cancer progression via CCL2-dependent macrophage recruitment

Endometrial cancer is the most common gynecologic malignancy and the fourth most common malignancy in women. For most patients in whom the disease is confined to the uterus, treatment results in successful remission; however, there are no curative treatments for tumors that have progressed beyond the uterus. The serine/threonine kinase LKB1 has been identified as a potent suppressor of uterine cancer, but the biological modes of action of LKB1 in this context remain incompletely understood. Here, we have shown that LKB1 suppresses tumor progression by altering gene expression in the tumor microenvironment. We determined that LKB1 inactivation results in abnormal, cell-autonomous production of the inflammatory cytokine chemokine (C-C motif) ligand 2 (CCL2) within tumors, which leads to increased recruitment of macrophages with prominent tumor-promoting activities. Inactivation of Ccl2 in an Lkb1-driven mouse model of endometrial cancer slowed tumor progression and increased survival. In human primary endometrial cancers, loss of LKB1 protein was strongly associated with increased CCL2 expression by tumor cells as well as increased macrophage density in the tumor microenvironment. These data demonstrate that CCL2 is a potent effector of LKB1 loss in endometrial cancer, creating potential avenues for therapeutic opportunities.

ARID1A Is Essential for Endometrial Function during Early Pregnancy

AT-rich interactive domain 1A gene (ARID1A) loss is a frequent event in endometriosis-associated ovarian carcinomas. Endometriosis is a disease in which tissue that normally grows inside the uterus grows outside the uterus, and 50% of women with endometriosis are infertile. ARID1A protein levels were significantly lower in the eutopic endometrium of women with endometriosis compared to women without endometriosis. However, an understanding of the physiological effects of ARID1A loss remains quite poor, and the function of Arid1a in the female reproductive tract has remained elusive. In order to understand the role of Arid1a in the uterus, we have generated mice with conditional ablation of Arid1a in the PGR positive cells (Pgrcre/+Arid1af/f; Arid1ad/d). Ovarian function and uterine development of Arid1ad/d mice were normal. However, Arid1ad/d mice were sterile due to defective embryo implantation and decidualization. The epithelial proliferation was significantly increased in Arid1ad/d mice compared to control mice. Enhanced epithelial estrogen activity and reduced epithelial PGR expression, which impedes maturation of the receptive uterus, was observed in Arid1ad/d mice at the peri-implantation period. The microarray analysis revealed that ARID1A represses the genes related to cell cycle and DNA replication. We showed that ARID1A positively regulates Klf15 expression with PGR to inhibit epithelial proliferation at peri-implantation. Our results suggest that Arid1a has a critical role in modulating epithelial proliferation which is a critical requisite for fertility. This finding provides a new signaling pathway for steroid hormone regulation in female reproductive biology and furthers our understanding of the molecular mechanisms that underlie dysregulation of hormonal signaling in human reproductive disorders such as endometriosis.

LKB1 gene inactivation does not sensitize non-small cell lung cancer cells to mTOR inhibitors in vitro

AIM

Previous study has shown that endometrial cancers with LKB1 inactivation are highly responsive to mTOR inhibitors. In this study we examined the effect of LKB1 gene status on mTOR inhibitor responses in non-small cell lung cancer (NSCLC) cells.

METHODS

Lung cancer cell lines Calu-1, H460, H1299, H1792, and A549 were treated with the mTOR inhibitors rapamycin or everolimus (RAD001). The mTOR activity was evaluated by measuring the phosphorylation of 4EBP1 and S6K, the two primary mTOR substrates. Cells proliferation was measured by MTS or sulforhodamine B assays.

RESULTS

The basal level of mTOR activity in LKB1 mutant A549 and H460 cells was significantly higher than that in LKB1 wild-type Calu-1 and H1792 cells. However, the LKB1 mutant A549 and H460 cells were not more sensitive to the mTOR inhibitors than the LKB1 wild-type Calu-1 and H1792 cells. Moreover, knockdown of LKB1 gene in H1299 cells did not increase the sensitivity to the mTOR inhibitors. Treatment with rapamycin or RAD001 significantly increased the phosphorylation of AKT in both LKB1 wild-type and LKB1 mutant NSCLC cells, which was attenuated by the PI3K inhibitor LY294002. Furthermore, RAD001 combined with LY294002 markedly enhanced the growth inhibition on LKB1 wild-type H1792 cells and LKB1 mutant A549 cells.

CONCLUSION

LKB1 gene inactivation in NSCLC cells does not increase the sensitivity to the mTOR inhibitors. The negative feedback activation of AKT by mTOR inhibition may contribute to the resistance of NSCLC cells to mTOR inhibitors.

Targeting LKB1 in cancer - exposing and exploiting vulnerabilities

The LKB1 tumour suppressor is a serine/threonine kinase that functions as master regulator of cell growth, metabolism, survival and polarity. LKB1 is frequently mutated in human cancers and research spanning the last two decades have begun decoding the cellular pathways deregulated following LKB1 inactivation. This work has led to the identification of vulnerabilities present in LKB1-deficient tumour cells. Pre-clinical studies have now identified therapeutic strategies targeting this subset of tumours that promise to benefit this large patient population harbouring LKB1 mutations. Here, we review the current efforts that are underway to translate pre-clinical discovery of therapeutic strategies targeting LKB1 mutant cancers into clinical practice.

Update on the roles of liver kinase B1 in pancreatic cancer

Germline mutations of the liver kinase B1 (STK11/LKB1) gene which encodes a serine/threonine kinase is responsible for Peutz-Jeghers syndrome. There are 14 AMP-activated protein kinase (AMPK)-related kinases in pathways downstream of LKB1, which are involved in many physiological and pathological processes such as regulation of energy metabolism, cell polarity and apoptosis in cells. LKB1 gene mutation has been investigated extensively in a variety of cancers, including pancreatic cancer. Pancreatic cancer is commonly recognized as a disease with extremely poor prognosis. Therefore, a full understanding of its molecular pathology is critical. This review aims to elucidate the structure, distribution, and function of LKB1, and the relationship with pancreatic cancer. In addition, we also point out that in some scenarios, LKB1 may play a role as a tumor protector.