An immune competent orthotopic model of endometrial cancer with metastasis

Mitochondrial defects and metabolic vulnerabilities in Lynch syndrome-associated MSH2-deficient endometrial cancer

Lynch syndrome (LS), caused by inherited mutations in DNA mismatch repair genes, including MSH2, carries a 60% lifetime risk of developing endometrial cancer (EC). Beyond hypermutability, mechanisms driving LS-associated EC (LS-EC) remain unclear. We investigated MSH2 loss in EC pathogenesis using a mouse model (PR-Cre Msh2LoxP/LoxP, abbreviated Msh2KO), primary cell lines, human tissues, and human EC cells with isogenic MSH2 knockdown. By 8 months, 58% of Msh2KO mice developed endometrial atypical hyperplasia (AH), a precancerous lesion. At 12-16 months, 50% of Msh2KO mice exhibited either AH or ECs with histologic similarities to human LS-ECs. Transcriptomic profiling of EC from Msh2KO mice revealed mitochondrial dysfunction-related pathway changes. Subsequent studies in vitro and in vivo revealed mitochondrial dysfunction based on 2 mechanisms: mitochondrial content reduction and structural disruptions in retained mitochondria. Human LS-ECs also exhibited mitochondrial content reduction compared with non-LS-ECs. Functional studies demonstrated metabolic reprogramming of MSH2-deficient EC, including reduced oxidative phosphorylation and increased susceptibility to glycolysis suppression. These findings identified mitochondrial dysfunction and metabolic disruption as consequences of MSH2 deficiency in EC. Mitochondrial and metabolic aberrations should be evaluated as biomarkers for endometrial carcinogenesis or risk stratification and represent potential targets for cancer interception in women with LS.

Bridging the Gap from Bench to Bedside: A Call for In Vivo Preclinical Models to Advance Endometrial Cancer and Cervical Cancer Immuno-oncology Research

Advanced-stage endometrial and cervical cancers are associated with poor outcomes despite contemporary advances in surgical techniques and therapeutics. Recent clinical trial results have led to a shift in the treatment paradigm for both malignancies, in which immunotherapy is now incorporated as the standard of care up front for most patients with advanced endometrial and cervical cancers as the standard of care. Impressive response rates have been observed, but unfortunately, a subset of patients do not benefit from immunotherapy, and survival remains poor. Continued preclinical research and clinical trial development are crucial for our understanding of resistance mechanisms to immunotherapy and maximization of therapeutic efficacy. In this setting, syngeneic models are preferred over xenograft models as they allow for the evaluation of the tumor-immune interaction in an immunocompetent host, most closely mimicking the tumor-immune interaction in patients with cancer. Unfortunately, significant disparities exist about syngeneic models in gynecologic malignancy, in which queries from multiple large bioscience companies confirm no commercial availability of endometrial or cervical cancer syngeneic cell lines. Published data exist about the recent development of several endometrial and cervical cancer syngeneic cell lines, warranting further investigation. Closing the disparity gap for preclinical models in endometrial and cervical cancers will support physician scientists, basic and translational researchers, and clinical trialists who are dedicated to improving outcomes for our patients with advanced disease and poor prognosis.

Mitochondrial defects and metabolic vulnerabilities in Lynch syndrome-associated MSH2-deficient endometrial cancer

Lynch syndrome (LS) is defined by inherited mutations in DNA mismatch repair genes, including MSH2, and carries 60% lifetime risk of developing endometrial cancer (EC). Beyond hypermutability, specific mechanisms for LS-associated endometrial carcinogenesis are not well understood. Here, we assessed the effects of MSH2 loss on EC pathogenesis using a novel mouse model (PR-Cre Msh2 flox/flox , abbreviated Msh2KO), primary cell lines established from this model, human tissues, and human EC cell lines with isogenic MSH2 knockdown. Beginning at eight months of age, 30% of Msh2KO mice exhibited endometrial atypical hyperplasia (AH), a precancerous lesion. At 12 to 16 months of age, 47% of Msh2KO mice exhibited either AH or ECs with histologic features similar to human LS-related ECs. Transcriptomic profiling of EC from Msh2KO mice revealed a transcriptomic signature for mitochondrial dysfunction. Studies in vitro and in vivo revealed mitochondrial dysfunction based upon two mechanisms: marked mitochondrial content reduction, along with pronounced disruptions to the integrity of retained mitochondria. Human LS-related ECs also exhibited mitochondrial content reduction compared with non-LS-related ECs. Functional studies revealed metabolic reprogramming of MSH2-deficient EC cells in vitro , including reduced oxidative phosphorylation and increased susceptibility to glycolysis suppression. We are the first to identify mitochondrial dysfunction and metabolic disruption as a consequence of MSH2 deficiency-related EC. Mitochondrial and metabolic aberrations should be evaluated as novel biomarkers for endometrial carcinogenesis or risk stratification and could serve as targets for cancer interception in women with LS.

Significance

This is the first study to report mitochondrial dysfunction contributing to MSH2-deficient endometrial cancer development, identifying a noncanonical pathway for MSH2 deficient carcinogenesis, which also imparts vulnerability to metabolic targeting.

ARG1 Is a Potential Prognostic Marker in Metastatic Endometrial Cancer

Endometrial cancer (EC) is the most common gynecologic malignancy. While the majority of patients present with early-stage and low-grade EC and have an excellent prognosis, a subset has metastatic disease at presentation or develops distant recurrence after initial treatment of the primary. However, the lack of prognostic biomarkers for metastatic EC is a critical barrier. Arginase 1 (ARG1) regulates the last step of the urea cycle, and an increase in ARG1 has been correlated as a poor prognostic factor in a variety of cancers. In the present study, ARG1 expression was evaluated as a potential prognostic marker for metastatic EC in endometrial hyperplasia and cancer of mice with Pten mutation as well as Pten and Mig-6 double mutations. While Pten mutation in the uterus is not sufficient for distant metastasis, mice with concurrent ablation of Mig-6 and Pten develop distant metastasis. Our immunostaining and RT-qPCR analysis revealed that the expression of ARG1 in early stage of EC as well as endometrial hyperplasia from mice deficient in Mig-6 and Pten mutations significantly increased compared to Pten mutation in the uterus. The results suggest that a high level of ARG1 is associated with poor prognosis in association with EC of mouse.

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.

Novel Endometrial Cancer Models Using Sensitive Metastasis Tracing for CXCR4-Targeted Therapy in Advanced Disease

Advanced endometrial cancer (EC) lacks therapy, thus, there is a need for novel treatment targets. CXCR4 overexpression is associated with a poor prognosis in several cancers, whereas its inhibition prevents metastases. We assessed CXCR4 expression in EC in women by using IHC. Orthotopic models were generated with transendometrial implantation of CXCR4-transduced EC cells. After in vitro evaluation of the CXCR4-targeted T22-GFP-H6 nanocarrier, subcutaneous EC models were used to study its uptake in tumor and normal organs. Of the women, 91% overexpressed CXCR4, making them candidates for CXCR4-targeted therapies. Thus, we developed CXCR4⁺ EC mouse models to improve metastagenesis compared to current models and to use them to develop novel CXCR4-targeted therapies for unresponsive EC. It showed enhanced dissemination, especially in the lungs and liver, and displayed 100% metastasis penetrance at all clinically relevant sites with anti-hVimentin IHC, improving detection sensitivity. Regarding the CXCR4-targeted nanocarrier, 60% accumulated in the SC tumor; therefore, selectively targeting CXCR4⁺ cancer cells, without toxicity in non-tumor organs. Our CXCR4⁺ EC models will allow testing of novel CXCR4-targeted drugs and development of nanomedicines derived from T22-GFP-H6 to deliver drugs to CXCR4⁺ cells in advanced EC. This novel approach provides a therapeutic option for women with metastatic, high risk or recurrent EC that have a dismal prognosis and lack effective therapies.

Immunosuppressive tumor microenvironment in Uterine Serous Carcinoma via CCL7 signal with myeloid-derived suppressor cells

Serous carcinoma of the uterus (USC) is a pathological subtype of high-grade endometrial cancers, with no effective treatment for advanced cases. Since such refractory tumors frequently harbor anti-tumor immune tolerance, many immunotherapies have been investigated for various malignant tumors using immuno-competent animal models mimicking their local immunities. In this study, we established an orthotopic mouse model of high-grade endometrial cancer and evaluated the local tumor immunity to explore the efficacy of immunotherapies against USC. A multivariate analysis of 62 human USC cases revealed that the tumor infiltrating cell status, few CD8+ cells and abundant myeloid-derived suppressor cells (MDSCs), was an independent prognostic factor (p<0.005). A murine endometrial cancer cell (mECC) was obtained from C57BL/6 mice via endometrium-specific deletion of Pten and Tp53, and another high-grade cell (HPmECC) was established by further overexpressing Myc in mECCs. HPmECCs exhibited higher capacities of migration and anchorage-independent proliferation than mECCs (p<0.01, p<0.0001), and when both types of cells were inoculated into the uterus of C57BL/6 mice, the prognosis of mice bearing HPmECC-derived tumors was significantly poorer (p<0.001). Histopathological analysis of HPmECC orthotopic tumors showed serous carcinoma-like features with prominent tumor infiltration of MDSCs (p<0.05), and anti Gr-1 antibody treatment significantly prolonged the prognosis of HPmECC-derived tumor-bearing mice (p<0.05). High CCL7 expression was observed in human USC and HPmECC, and MDSCs migration was promoted in a CCL7 concentration-dependent manner. These results indicate that anti-tumor immunity is suppressed in USC due to increased number of tumor-infiltrating MDSCs via CCL signal.

EZH2 and Endometrial Cancer Development: Insights from a Mouse Model

Enhancer of zeste homolog 2 (EZH2), a core component of polycomb repressive complex 2, plays an important role in cancer development. As both oncogenic and tumor suppressive functions of EZH2 have been documented in the literature, the objective of this study is to determine the impact of Ezh2 deletion on the development and progression of endometrial cancer induced by inactivation of phosphatase and tensin homolog (PTEN), a tumor suppressor gene frequently dysregulated in endometrial cancer patients. To this end, we created mice harboring uterine deletion of both Ezh2 and Pten using Cre recombinase driven by the progesterone receptor (Pgr) promoter. Our results showed reduced tumor burden in Pten^d/d; Ezh2^d/d mice compared with that of Pten^d/d mice during early carcinogenesis. The decreased Ki67 index in EZH2 and PTEN-depleted uteri versus that in PTEN-depleted uteri indicated an oncogenic role of EZH2 during early tumor development. However, mice harboring uterine deletion of both Ezh2 and Pten developed unfavorable disease outcome, accompanied by exacerbated epithelial stratification and heightened inflammatory response. The observed effect was non-cell autonomous and mediated by altered immune response evidenced by massive accumulation of intraluminal neutrophils, a hallmark of endometrial carcinoma in Pten^d/d; Ezh2^d/d mice during disease progression. Hence, these results reveal dual roles of EZH2 in endometrial cancer development.

Pharmacological targeting of polyamine and hypusine biosynthesis reduces tumor activity of endometrial cancer

Endometrial cancer (EC) is a common and deadly cancer in women and novel therapeutic approaches are urgently needed. Polyamines (putrescine, spermidine, spermine) are critical for mammalian cell proliferation and MYC coordinately regulates polyamine metabolism through ornithine decarboxylase (ODC). ODC is a MYC target gene and rate-limiting enzyme of polyamine biosynthesis and the FDA-approved anti-protozoan drug α-difluoromethylornithine (DFMO) inhibits ODC activity and induces polyamine depletion that leads to tumor growth arrest. Spermidine is required for the hypusine-dependent activation of eukaryotic translation initiation factors 5A1 (eIF5A1) and 5A2 (eIF5A2) and connects the MYC/ODC-induced deregulation of spermidine to eIF5A1/2 protein translation, which is increased during cancer cell proliferation. We show that the eIF5A1 is significantly upregulated in EC cells compared to control cells (p = 0.000038) and that combined pharmacological targeting of ODC and eIF5A hypusination with cytostatic drugs DFMO and N1-guanyl-1,7-diaminoheptane (GC7), respectively, reduces eIF5A1 activation and synergistically induces apoptosis in EC cells. In vivo, DFMO/GC7 suppressed xenografted EC tumor growth in mice more potently than each drug alone compared to control (p = 0.002) and decreased putrescine (p = 0.045) and spermidine levels in tumor tissues. Our data suggest DFMO and GC7 combination therapy may be useful in the treatment or prevention of EC.

Effects of Induced Exosomes from Endometrial Cancer Cells on Tumor Activity in the Presence of Aurea helianthus Extract

Endometrial cancer (EC) cells metastasize to various regions, including the ovaries, fallopian tubes, cervix, blood, liver, bone, and brain. Various carcinogens are known to cause EC. Exosomes are released from several types of cells and contain various cellular components. In this study, flow cytometry and quantitative PCR were used to evaluate marker levels, cell migration, cell invasion, and mitochondrial membrane potential, and cellular senescence tests were used to estimate cancer activity. The microRNAs were profiled using next-generation sequencing. Although tocopherol-α and rutin content in Aurea helianthus is high, A. helianthus extract was more useful in modulating tumor activity compared to the two aforementioned substances. Notably, we established that the extract induced bioactive exosomes in EC cells, and profiling of miRNAs in the extract-inducing exosomes (EIE) indicated their potency to be developed as a biological drug. The extract and EIE contributed to the following five biological process categories for EC cells: (1) cell migration and invasion suppression, (2) cellular senescence activation by attenuating mitochondrial membrane potential and enhancing autophagy, (3) reproductive cancer activity attenuation, (4) drug susceptibility activation, and (5) EIE containing miRNAs associated with decreasing inflammation.