Promising novel therapies for the treatment of endometrial cancer

Treatment patterns and real-world clinical outcomes in patients with advanced endometrial cancer that are non-microsatellite instability high (non-MSI-high) or mismatch repair proficient (pMMR) in the United States

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First study to describe real-world outcomes in non-MSI-H/pMMR aEC patients who progressed following prior systemic therapy.

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MSI/MMR testing was near universal in aEC patients in the US, reflecting the increased awareness of biomarker status.

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Patients on second-line chemo or hormonal therapy had poor clinical outcomes: median OS of 10 months and rwPFS of 5 months.

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Data suggest an unmet medical need in this population between 2016 and 2019.

Objective

Microsatellite instability (MSI) due to defective DNA mismatch repair has emerged as an actionable biomarker in advanced endometrial cancer (aEC). Currently, there are no treatment patterns and outcomes data in non-MSI-high (non-MSI-H) or mismatch repair proficient (pMMR) aEC patients following prior systemic therapy (FPST). Our goal was to describe real-world data in this population in the US in 2019 and prior years.

Methods

Endometrial Cancer Health Outcomes (ECHO) is a retrospective patient chart review study conducted in the US. Patients with non-MSI-H/pMMR aEC and progression between 06/01/2016–06/30/2019 FPST were eligible. Data collected included patient demographics, clinical and treatment characteristics, and clinical outcomes. Kaplan-Meier analyses were performed to estimate time to treatment discontinuation, real-world progression-free survival (rwPFS), and overall survival (OS), separately by treatment category.

Results

A total of 165 eligible patients initiated second-line therapy with chemotherapy ± bevacizumab (n = 140) or hormonal therapy (n = 25). Median age was 66.0 years at aEC diagnosis, 70.2% were Stage IIIB-IV, 40.0% had ECOG ≥ 2 at second-line therapy initiation. Median rwPFS was 5.0 months (95% CI: 4.0–6.0) for patients receiving chemotherapy ± bevacizumab and 5.5 months (95% CI: 3.0–29.0) for those receiving hormonal therapy. Median OS was 10.0 months (95% CI: 8.0–13.0) and 9.0 months (95% CI: 6.0-NA) in these groups, respectively.

Conclusions

Non-MSI-H/pMMR patients who initiated second-line therapy with chemotherapy ± bevacizumab or hormonal therapy had poor clinical outcomes with a median survival less than 1 year and rwPFS less than 6 months. This was the first study to define the clinical unmet need in patients with non-MSI-H/pMMR aEC with conventional therapy.

The Effects of NT-1044, a Novel AMPK Activator, on Endometrial Cancer Cell Proliferation, Apoptosis, Cell Stress and In Vivo Tumor Growth

Objectives

Anti-diabetic biguanide drugs such as metformin may have anti-tumorigenic effects by behaving as AMPK activators and mTOR inhibitors. Metformin requires organic cation transporters (OCTs) for entry into cells, and NT-1044 is an AMPK activator designed to have greater affinity for two of these transporters, OCT1 and OCT3. We sought to compare the effects of NT-1044 on cell proliferation in human endometrial cancer (EC) cell lines and on tumor growth in an endometrioid EC mouse model.

Methods

Cell proliferation was assessed in two EC cell lines, ECC-1 and Ishikawa, by MTT assay after exposure to NT-1044 for 72 hours of treatment. Apoptosis was analyzed by Annexin V-FITC and cleaved caspase 3 assays. Cell cycle progression was evaluated by Cellometer. Reactive oxygen species (ROS) were measured using DCFH-DA and JC-1 assays. For the in vivo studies, we utilized the LKB1^fl/flp53^fl/fl mouse model of endometrioid endometrial cancer. The mice were treated with placebo or NT-1044 or metformin following tumor onset for 4 weeks.

Results

NT-1044 and metformin significantly inhibited cell proliferation in a dose-dependent manner in both EC cell lines after 72 hours of exposure (IC50 218 μM for Ishikawa; 87 μM for ECC-1 cells). Treatment with NT-1044 resulted in G1 cell cycle arrest, induced apoptosis and increased ROS production in both cell lines. NT-1044 increased phosphorylation of AMPK and decreased phosphorylation of S6, a key downstream target of the mTOR pathway. Expression of the cell cycle proteins CDK4, CDK6 and cyclin D1 decreased in a dose-dependent fashion while cellular stress protein expression was induced in both cell lines. As compared to placebo, NT-1044 and metformin inhibited endometrial tumor growth in obese and lean LKB1^fl/flp53^fl/fl mice.

Conclusions

NT-1044 suppressed EC cell growth through G1 cell cycle arrest, induction of apoptosis and cellular stress, activation of AMPK and inhibition of the mTOR pathway. In addition, NT-1044 inhibited EC tumor growth in vivo under obese and lean conditions. More work is needed to determine if this novel biguanide will be beneficial in the treatment of women with EC, a disease strongly impacted by obesity and diabetes.

Development and validation of m6A regulators' prognostic significance for endometrial cancer

BACKGROUND

Endometrial cancer (EC) is the sixth most common cancer in women globally. It has been found that the expression levels of m6A regulators can be potentially used for prognostic stratification in some cancers, but the role of m6A regulators in EC prognosis remains unclear.

METHODS

The data of 584 EC samples were downloaded from The Cancer Genome Atlas and the mRNA expression profiles of 20 m6A regulators were analyzed, followed by functional enrichment analysis, immune infiltration analysis, and least absolute shrinkage and selection operator method-COX regression analysis.

RESULTS

The mRNA expression levels of 20 m6A regulators were significantly different between cancer samples across different grades. The 548 EC samples could be clearly divided into 2 clusters. Kaplan-Meier survival analysis proved that these two groups had highly different overall survival probabilities. Besides, the univariate regression analysis further reserved eight genes related to overall survival from the 20 m6A regulators. We established a prognostic signature including two genes, that is, IGF2BP1 and YTHDF3, that showed a strong ability for stratifying prognostically different EC patients. We identified 3239 differentially expressed genes between the high- and low-risk groups, involving in multiple biological processes and signaling pathways. Meanwhile, 6 differentially infiltrated immune cell types between the high- and low-risk groups could effectively distinguish the high- and low-risk EC groups. The expressions of immune checkpoints were different between high- and low-risk EC patients.

CONCLUSION

We first report the prognostic role of m6A regulators in EC, which should contribute to a better understanding of the underlying mechanisms of EC pathogenesis and progression.

Methoxyeugenol regulates the p53/p21 pathway and suppresses human endometrial cancer cell proliferation

ETHNOPHARMACOLOGICAL RELEVANCE

Plant-derived compounds are a reservoir of natural chemicals and can act as drug precursors or prototypes and pharmacological probes. Methoxyeugenol is a natural compound found in plant extracts, such as nutmeg (Myristica fragrans), and it presents anthelmintic, antimicrobial, anti-inflammatory activities. Recently, interest in the anticancer activity of plant extracts is increasing and the therapeutic activity of methoxyeugenol against cancer has not yet been explored.

AIM OF THE STUDY

The present study aimed to evaluate the cancer-suppressive role and the molecular signaling pathways of methoxyeugenol in human endometrial cancer (Ishikawa) cell line.

MATERIALS AND METHODS

Proliferation, viability, and cell toxicity were assessed by direct counting, MTT assay, and LDH enzyme release assay, respectively. Antiproliferative effect were evaluated by nuclear morphological changes along with the cellular mechanisms of apoptosis and senescence by flow cytometry. The underlying molecular and cellular mechanisms were investigated by RT-qPCR, reactive oxygen species (ROS) levels, mitochondrial dysfunction, and proliferative capacity.

RESULTS AND CONCLUSIONS

Methoxyeugenol treatment significantly inhibited the proliferation and viability of Ishikawa cells. Probably triggered by the higher ROS levels and mitochondrial dysfunction, the gene expression of p53 and p21 increased and the gene expression of CDK4/6 decreased in response to the methoxyeugenol treatment. The rise in nuclear size and acidic vesicular organelles corroborate with the initial senescence-inducing signals in Ishikawa cells treated with methoxyeugenol. The antiproliferative effect was not related to cytotoxicity and proved to effectively reduce the proliferative capacity of endometrial cancer cells even after treatment withdrawal. These results demonstrated that methoxyeugenol has a promising anticancer effect against endometrial cancer by rising ROS levels, triggering mitochondrial instability, and modulating cell signaling pathways leading to an inhibition of cell proliferation.

Effect of Metformin For Decreasing Proliferative Marker in Women with Endometrial Cancer: A Randomized Double-blind Placebo-Controlled Trial

Objective:

To compare the Ki-67 index of endometrial cancer cells before and after treatment between the metformin and placebo group in women with endometrial cancer (EC).

Methods:

This study was a randomized, double-blind, placebo-controlled trial conducting in non-diabetic women who diagnosed with endometrioid EC and had a schedule for elective surgical staging at Rajavithi Hospital between August 2018 and June 2019. Tissue specimens were obtained via endometrial curettage at the time of initial diagnosis (pre-treatment) and hysterectomy (post-treatment) to assess the value of the Ki-67 index by immunochemistry. Patients were randomly assigned into 2 groups: metformin and placebo group. Metformin 850 mg or placebo 1 tab were administered once daily for at least 7 days, starting on the first morning after recruitment until one day before surgery. Baseline characteristics (e.g., age, body mass index, co-morbidities) including surgical and pathological characteristics were recorded. The metabolic effect of metformin was also evaluated by a recording of fasting blood sugar, HbA1C and potential adverse events including nausea, vomiting, dizziness, and hypoglycemic symptom.

Results:

A total of 49 EC patients were included in this study. Twenty-five patients were assigned to the metformin group and 24 patients were assigned to the placebo group. Baseline demographic, surgical, and pathological characteristics between the 2 groups were similar. Metformin significantly changed the Ki-67 index relative to placebo, with a mean decrease of 23.3% (p=0.001) and a mean proportional decrease of 39.1% (p=0.006) before and after treatment. Additionally, no significant differences were detected in metabolic effects and adverse events between the metformin and the placebo groups.

Conclusion:

Short-term treatment with an oral metformin significantly reduced a proliferative marker Ki-67 index in women with endometrioid EC awaiting surgical staging. This study supports the biological effect of metformin in EC and potential applications in the adjuvant treatment in EC patients.

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.

MicroRNA-365 targets multiple oncogenes to inhibit proliferation, invasion, and self-renewal of aggressive endometrial cancer cells

Background

MicroRNA-365 (miR-365) has been reported to be a tumor suppressor miRNA. However, the role of miR-365 in progression of endometrial cancer (EC) has not been explored, in this study, we have found that re-expression of miRNA-365 inhibits cell proliferation, causes apoptosis and senescence.

Materials and methods

Overexpression of miR-365 attenuated cell migration and invasion, inhibited sphere-forming capacity, and enhanced the chemosensitivity to paclitaxel. In silico prediction tools identified the potential targets of miR-365.

Results

We identified EZH2 and FOS as targets of miR-365 and found that downregulating these genes imitated the tumor suppressive effect of miR-365. The outcomes of the study suggested that a reverse correlation existed between low miR-365 and overexpression of FOS and EZH2 in EC tissue specimens.

Conclusion

The study concludes that miR-365 acts as an important tumor suppressor and contributes by suppressing cell invasiveness, proliferation, and self-renewal in cancer cell lines by regulating multiple oncogenes. We establish that miR-365-EZH2/FOS pathway is an important target for treating EC.

Expression and prognostic value of miRNA-29b in peripheral blood for endometrial cancer

AIM

We explored the role of miR-29b expression in endometrial cancer (EC) progression and patient prognosis.

MATERIALS & METHODS

Patients with primary or metastatic EC (n = 356), patients with endometrial benign tumors (n = 149) and healthy female subjects (n = 155) were collected. We assessed the diagnostic value of miR-29b expression for EC using a receiver operating characteristic curve.

RESULTS

The miR-29b expressions were lower in patients with primary or metastatic EC. Using miR-29b expression to diagnose EC produced 0.976 area under the curve, 96.1% sensitivity and 97.9% specificity. Cox proportional hazard regression model verified a low miR-29b expression and is an unfavorable prognostic indicator for EC.

CONCLUSION

We conclude that downregulated miR-29b expression correlates with poor EC prognosis and is helpful to evaluate the EC prognosis.

miR-148b Functions as a Tumor Suppressor by Targeting Endoplasmic Reticulum Metallo Protease 1 in Human Endometrial Cancer Cells

This study investigated the tumor-suppressive role of miR-148b in regulating endoplasmic reticulum metalloprotease 1 (ERMP1) expression and the oxidative stress response in endometrial cancer cells. Human endometrial cancer RL95-2 cells were used and transfected with miR-148b mimic, miR-148b inhibitor, or their scrambled negative control. Thereafter, the transfection efficiency was determined by RT-qPCR, and cell proliferation was assessed by MTT assay. The dual-luciferase reporter assay, Western blot, and RT-qPCR were conducted to determine the target gene of miR-148b. ERMP1 is a putative target of miR-148b, and thereby the overexpression and downregulation of ERMP1 on the proliferation of RL95-2 cells were assessed. Next, the expressions of hypoxia-inducible factor 1 (HIF-1) and nuclear factor erythroid 2-related factor 2 (Nrf2) were analyzed by Western blot. Intracellular reactive oxygen species (ROS) was determined using dichlorofluorescin diacetate (DCFDA). Results showed that differential expression of miR-148b or ERMP1 was observed in normal endometrial tissues and endometrial cancerous tissues. Enhanced expression of miR-148b effectively inhibited proliferation of RL95-2 cells. ERMP1 was the target of miR-148b. ERMP1 silencing obviously suppressed proliferation of RL95-2 cells. Thus, miR-148b repressed cell proliferation, likely through downregulating ERMP1. Furthermore, it was observed that miR-148b significantly decreased expression of HIF-1 and Nrf2 by downregulating ERMP1. The intracellular ROS level was enhanced by miR-148b via downregulating ERMP1. To conclude, our results suggested that miR-148b suppressed cell proliferation and regulated the oxidative stress response in human endometrial cancer RL95-2 cells by inhibiting ERMP1.

Autophagy plays an important role in stemness mediation and the novel dual function of EIG121 in both autophagy and stemness regulation of endometrial carcinoma JEC cells

Endometrial cancer (EC) is the third most common gynecologic malignancy in the world, and is considered a chemotherapy poor responding cancer. There are two underlying mechanisms on chemoresistance: the stemness of cancer stem cells (CSCs) and activation of pro-survival autophagy. It was found that autophagy is one of the main factors of cancer stem cell survival, multidrug resistance and maintenance of the homeostasis of cancer stem cells and normal cancer cells. However, the relationship between CSCs and autophagy of EC cells is still unknown. In this study, higher autophagy level was found in endometrial cancer stem cells (ECSCs) and stemness kept in line with autophagy in successive cultured JEC spheres. Autophagy inhibition decreased the properties of CSCs in JEC spheres and enhanced sensitivity of ECSCs to paclitaxel. Besides, it was found that EIG121 exerted dual functions in the regulation of autophagy and stemness not only in normal JEC cells but also JEC obtained CSCs. These findings could be useful for developing targeted therapies for endometrial carcinoma.

The role of the SDF-1/ CXCR7 axis on the growth and invasion ability of endometrial cancer cells

PURPOSE

Stroma-derived factor-1 (SDF-1) and its receptor C-X-C chemokine receptor-4 (CXCR4) are involved in human endometrial carcinoma (EC) progression. CXCR7 is another important receptor of SDF-1 and has a higher affinity with SDF-1 compared with that of CXCR4. This paper aims to study the effects of the SDF-1/CXCR7 axis on the growth and invasion ability of EC cells.

METHODS

CXCR7 expression was evaluated by quantitative RT-PCR, immunohistochemistry, immunocytochemistry and Western blotting in EC cell lines and 30 cases of primary EC tissue from patients. EC cell line proliferation and migration were assessed following knockdown of CXCR7 by MTT and transwell assays.

RESULTS

The results showed that CXCR7 was highly expressed at both mRNA and protein levels in the EC cells and tissue. siCXCR7 effectively silenced CXCR7 in Ishikawa and AN3CA cells. Treatment with 17β-oestradiol (17β-E2) significantly increased the levels of CXCR7 and SDF-1 in Con, siCon and siCXCR7 treated Ishikawa. siCXCR7 persistently inhibited CXCR7 expression, even in cells treated with 17β-E2. Moreover, in vitro functional analyses, silencing CXCR7 resulted in decreased proliferation in Ishikawa and AN3CA cells. Treatment with 17β-E2 and SDF-1 significantly promoted the growth and migration in siCon treated Ishikawa and AN3CA. Interestingly, in response to 17β-E2 and SDF-1 stimulation, siCXCR7 continuously inhibited the growth and invasion of Ishikawa and AN3CA cells.

CONCLUSION

Our results indicate that SDF-1/CXCR7 plays a positive role in the proliferation and invasion of EC cells. CXCR7 inhibition treatment may provide a promising strategy for anti-tumour therapy for EC.

Mutant p53 induces EZH2 expression and promotes epithelial-mesenchymal transition by disrupting p68-Drosha complex assembly and attenuating miR-26a processing

The tumor suppressor p53 and the transcriptional repressor Enhancer of Zeste Homolog 2 (EZH2) have both been implicated in the regulation of epithelial-mesenchymal transition (EMT) and tumor metastasis via their impacts on microRNA expression. Here, we report that mutant p53 (mutp53) promotes EMT in endometrial carcinoma (EC) by disrupting p68-Drosha complex assembly. Overexpression of mutp53 has the opposite effect of wild-type p53 (WTp53), repressing miR-26a expression by reducing pri-miR-26a-1 processing in p53-null EC cells. Re-expression of miR-26a in mutp53 EC cells decreases cell invasion and promotes mesenchymal-epithelial transition (MET). Rescuing miR-26a expression also inhibits EZH2, N-cadherin, Vimentin, and Snail expression and induces E-cadherin expression both in vitro and in vivo. Moreover, patients with higher serum miR-26a levels have a better survival rate. These results suggest that p53 gain-of-function mutations accelerate EC tumor progression and metastasis by interfering with Drosha and p68 binding and pri-miR-26a-1 processing, resulting in reduced miR-26a expression and EZH2 overexpression.

Integrative Protein-Based Prognostic Model for Early-Stage Endometrioid Endometrial Cancer

PURPOSE

Endometrioid endometrial carcinoma (EEC) is the major histologic type of endometrial cancer, the most prevalent gynecologic malignancy in the United States. EEC recurrence or metastasis is associated with a poor prognosis. Early-stage EEC is generally curable, but a subset has high risk of recurrence or metastasis. Prognosis estimation for early-stage EEC mainly relies on clinicopathologic characteristics, but is unreliable. We aimed to identify patients with high-risk early-stage EEC who are most likely to benefit from more extensive surgery and adjuvant therapy by building a prognostic model that integrates clinical variables and protein markers.

EXPERIMENTAL DESIGN

We used two large, independent early-stage EEC datasets as training (n = 183) and validation cohorts (n = 333), and generated the levels of 186 proteins and phosphoproteins using reverse-phase protein arrays. By applying an initial filtering and the elastic net to the training samples, we developed a prognostic model for overall survival containing two clinical variables and 18 protein markers and optimized the risk group classification.

RESULTS

The Kaplan-Meier survival analyses in the validation cohort confirmed an improved discriminating power of our prognostic model for patients with early-stage EEC over key clinical variables (log-rank test, P = 0.565 for disease stage, 0.567 for tumor grade, and 1.3 × 10(-4) for the integrative model). Compared with clinical variables (stage, grade, and patient age), only the risk groups defined by the integrative model were consistently significant in both univariate and multivariate analyses across both cohorts.

CONCLUSIONS

Our prognostic model is potentially of high clinical value for stratifying patients with early-stage EEC and improving their treatment strategies.

Metformin and gynecologic cancers

IMPORTANCE

The obese population in the United States is reaching epic proportions, and obesity is linked to an increased risk for several cancers including gynecologic cancers. Obesity is not only a risk factor but also a marker of poor prognosis. It is crucial to develop novel treatment strategies to target this population. Metformin is a biguanide drug, typically used for diabetes treatment, currently being studied to evaluate its role in the treatment and prevention of gynecologic cancers.

OBJECTIVE

The aim of this study was to review the underlying biologic mechanisms of metformin's antitumorigenic effects. We assessed the epidemiologic and preclinical data that support the use of metformin in patients with endometrial and ovarian cancer. Finally, we reviewed current clinical trials that incorporate metformin as a prevention or treatment strategy for gynecologic cancers.

EVIDENCE ACQUISITION

A thorough search of PubMed for all current literature was performed. All preclinical, clinical, and epidemiologic reviews were evaluated across all cancers, with a focus on gynecologic cancer.

RESULTS

The preclinical, epidemiologic, and clinical data evaluated in this review are strongly supportive of the use of metformin for the prevention and treatment of gynecologic cancer. On the basis of these data, centers are currently enrolling for clinical trials using metformin in patients diagnosed with gynecologic malignancies.

CONCLUSIONS AND RELEVANCE

The data supporting the use of metformin in the prevention and treatment of cancers are building, including that of endometrial and ovarian cancer. The association between obesity, insulin resistance, as well as increased risk and poor outcomes in endometrial and ovarian cancer patients makes metformin an attractive agent for the prevention and treatment of these diseases.

MicroRNA-134 suppresses endometrial cancer stem cells by targeting POGLUT1 and Notch pathway proteins

We aimed to ascertain the role of microRNAs (miRNAs) in regulating human endometrial cancer stem cells (HuECSCs). The expression level of miRNA-134 (miR-134), a member of the DLK1-DIO3 genomic imprinted miRNA cluster, differed significantly between HuECSCs and human endometrial cancer cells (HuECCs). miR-134 inhibited HuECSCs proliferation and migration by targeting protein O-glucosyltransferase 1 (POGLUT1) expression. Exogenous miR-134 overexpression downregulated POGLUT1 and Notch pathway proteins in HuECSCs in vitro. miR-134 overexpression affected the G2/M phase of HuECSCs and suppressed the growth of xenograft tumours formed. Thus, endogenous miR-134 regulation in HuECSCs may suppress tumourigenesis in human endometrial carcinoma.

Anticancer agent icaritin induces apoptosis through caspase-dependent pathways in human hepatocellular carcinoma cells

Icaritin is an active ingredient derived from the plant Herba epimedium, which exhibits various pharmacological and biological activities. However, the function, and the underlying mechanisms of icaritin on the growth of SMMC‑7721 human hepatoma cells have yet to be elucidated. The present study aimed to investigate the function and underlying mechanisms of icaritin in the growth of SMMC‑7721 cells. The cells were treated with varying concentrations of icaritin for 12, 24 and 48 h, respectively, prior to cytotoxic analysis. Apoptosis of SMMC‑7721 cells following treatment with icaritin was measured using flow cytometry. The gene expression of mitochondria‑ and Fas‑mediated caspase‑dependent pathways was detected by reverse transcription‑quantitative polymerase chain reaction and western blotting. Statistical analysis was performed by Student's t‑test and one‑way analysis or variance. The present study demonstrated that treatment with icaritin significantly inhibited growth, and induced apoptosis of SMMC‑7721 cells, in a time‑ and dose‑dependent manner. In addition, icaritin triggered the mitochondrial/caspase apoptotic pathway, by decreasing the Bcl‑2/Bax protein ratio and increasing activation of caspase‑3. Icaritin also activated the Fas‑mediated apoptosis pathway, as was evident by the increased expression levels of Fas and activation of caspase‑8. These data suggest that icaritin may be a potent growth inhibitor and induce apoptosis of SMMC‑7721 cells through the mitochondria‑ and Fas‑mediated caspase‑dependent pathways. The present study may provide experimental evidence for preclinical and clinical evaluations of icaritin for HCC therapy.

Antiproliferative and metabolic effects of metformin in a preoperative window clinical trial for endometrial cancer

We conducted a preoperative window study of metformin in endometrial cancer (EC) patients and evaluated its antiproliferative, molecular and metabolic effects. Twenty obese women with endometrioid EC were treated with metformin (850 mg) daily for up to 4 weeks prior to surgical staging. Expression of the proliferation marker Ki-67, estrogen receptor (ER), progesterone receptor (PR), adenosine monophosphate-activated protein kinase (AMPK), and downstream targets of the mammalian target of rapamycin (mTOR) pathway were measured by immunohistochemistry. Global, untargeted metabolomics analysis of serum pre- and postmetformin treatment, and matched tumor, was performed. Metformin reduced proliferation by 11.75% (P = 0.008) based on the comparison of pre- and posttreatment endometrial tumors. A total of 65% of patients responded to metformin as defined by a decrease in Ki-67 staining in their endometrial tumors post-treatment. Metformin decreased expression of phosphorylated (p)-AMPK (P = 0.00001), p-Akt (P = 0.0002), p-S6 (51.2%, P = 0.0002), p-4E-BP-1 (P = 0.001), and ER (P = 0.0002) but not PR expression. Metabolomic profiling of serum indicated that responders versus nonresponders to treatment were more sensitive to metformin's effects on induction of lipolysis, which correlated with increased fatty acid oxidation and glycogen metabolism in matched tumors. In conclusion, metformin reduced tumor proliferation in a pre-operative window study in obese EC patients, with dramatic effects on inhibition of the mTOR pathway. Metformin induced a shift in lipid and glycogen metabolism that was more pronounced in the serum and tumors of responders versus nonresponders to treatment.This study provides support for therapeutic clinical trials of metformin in obese patients with EC.

MiR-449a functions as a tumor suppressor in endometrial cancer by targeting CDC25A

Accumulating evidence has demonstrated that microRNAs (miRNAs) play critical roles in cancer initiation and development by functioning either as oncogenes or as tumor suppressors. The role of microRNA-449a (miR-449a) in endometrial cancer remains unclear. We examined the levels of miR-449a and miR-449b in benign endometrium, type I and type II endometrial cancer tissues by quantitative real-time polymerase chain reaction. To further investigate the roles of miR-449a in regulating the behavior of endometrial cancer cells, we overexpressed miR-449a in the endometrial cancer cell line HEC-1B, which had low endogenous miR-449a expression. We analyzed the effects of miR-449a overexpression on CDC25 expression, proliferation, invasion and apoptosis of HEC-1B cells. We found that miR-449a and miR-449b levels were markedly reduced in type II endometrial cancer tissues but not in type I endometrial cancer tissues compared with normal endometrium. Overexpression of miR-449a significantly inhibited the proliferation, invasion and clonogenic survival of HEC-1B cells. MiR-449a overexpression also induced apoptosis in HEC-1B cells. In addition, real-time RT-PCR and western blot analysis showed that CDC25A expression was suppressed by miR-449a overexpression. Our results suggest that miR-449a may act as a tumor suppressor by targeting CDC25A in endometrial cancer.

LAPTM4B gene polymorphism and endometrial carcinoma risk and prognosis

A novel gene called LAPTM4B (lysosome-associated protein transmembrane 4 beta) plays several crucial roles in carcinogenesis. In this case-control study, we investigated the relationship between LAPTM4B gene polymorphism and susceptibility to endometrial carcinoma (EC). In an adjusted multivariate logistic regression analyses, subjects with the LAPTM4B*1/2 and *2/2 genotypes respectively exhibited 1.572-fold (95% confidence interval (CI) = 1.041-2.375) and 2.335-fold (95% CI = 1.365-3.995) increases in the risk of developing EC relative to those carrying LAPTM4B*1/1. Patients with LAPTM4B *2 had both significantly shorter overall survival (OS) and shorter disease-free survival (DFS) (both p < 0.001). Multivariate analysis showed that LAPTM4B genotype is an independent prognostic factor for OS and DFS (both p < 0.001). These results suggest that LAPTM4B polymorphisms might play an important role in the aetiology of EC.

Terpenoids from Zingiber officinale (Ginger) induce apoptosis in endometrial cancer cells through the activation of p53

Novel strategies are necessary to improve chemotherapy response in advanced and recurrent endometrial cancer. Here, we demonstrate that terpenoids present in the Steam Distilled Extract of Ginger (SDGE) are potent inhibitors of proliferation of endometrial cancer cells. SDGE, isolated from six different batches of ginger rhizomes, consistently inhibited proliferation of the endometrial cancer cell lines Ishikawa and ECC-1 at IC(50) of 1.25 µg/ml. SDGE also enhanced the anti-proliferative effect of radiation and cisplatin. Decreased proliferation of Ishikawa and ECC-1 cells was a direct result of SDGE-induced apoptosis as demonstrated by FITC-Annexin V staining and expression of cleaved caspase 3. GC/MS analysis identified a total of 22 different terpenoid compounds in SDGE, with the isomers neral and geranial constituting 30-40%. Citral, a mixture of neral and geranial inhibited the proliferation of Ishikawa and ECC-1 cells at an IC(50) 10 µM (2.3 µg/ml). Phenolic compounds such as gingerol and shogaol were not detected in SDGE and 6-gingerol was a weaker inhibitor of the proliferation of the endometrial cancer cells. SDGE was more effective in inducing cancer cell death than citral, suggesting that other terpenes present in SDGE were also contributing to endometrial cancer cell death. SDGE treatment resulted in a rapid and strong increase in intracellular calcium and a 20-40% decrease in the mitochondrial membrane potential. Ser-15 of p53 was phosphorylated after 15 min treatment of the cancer cells with SDGE. This increase in p53 was associated with 90% decrease in Bcl2 whereas no effect was observed on Bax. Inhibitor of p53, pifithrin-α, attenuated the anti-cancer effects of SDGE and apoptosis was also not observed in the p53(neg) SKOV-3 cells. Our studies demonstrate that terpenoids from SDGE mediate apoptosis by activating p53 and should be therefore be investigated as agents for the treatment of endometrial cancer.

Predicting everolimus treatment efficacy in patients with advanced endometrial carcinoma: a GINECO group study

This study aimed to determine whether the expression of various tumor biomarkers of the mTOR pathway predicts tumor response to everolimus in metastatic recurrent endometrial cancer. Tumor blocks from 44 patients of a phase II clinical trial receiving everolimus until progression or toxicity were collected and evaluated at 3 and 6 months for response. Thirty-six blocks were available for analysis of ER, PR, HER2, LKB1, PI3K, PTEN, pAKT, 4E-BP1, p4E-BP1, and S6RP expression by immunohistochemistry, PTEN deletion by FISH, and mutational status of K-RAS, PIK3CA, PTEN, and AKT1 genes. Twelve of 34 evaluable patients had partial response or stable disease (PR, SD) and 22 had progressive disease (PD). Immunohistochemistry showed that no protein expression could predict response to everolimus. Neither could loss of PTEN expression or PTEN deletion or PTEN mutation predict patient outcome. Thirty-one samples were assessable for K-RAS mutations (ten for PR+SD and 21 for PD). There are only four patients with K-RAS mutations and none of them responded to treatment. Median progression-free survival (PFS) and overall survival (OS) were longer in patients without K-RAS mutations (PFS 3.12 ± 1.7 months versus 1.05 ± 0.4 months, p < 0.001; OS 9.28 ± 2.0 months versus 2.30 ± 1.4 months, p = 0.034). In conclusion, the level of expression of proteins of the PI3K/mTOR pathway tested in this study cannot predict response to everolimus. However, endometrial cancer patients with K-RAS mutations do not seem to derive benefit from everolimus treatment.

Molecular bases of endometrial cancer: new roles for new actors in the diagnosis and the therapy of the disease

Endometrial carcinoma (EC) is the most commonly diagnosed gynecologic malignancy in the western world. The majority of these cancers are curable, but a subset about 15-20% of endometrial tumors exhibits an aggressive phenotype. Based on clinic-pathological and molecular characteristics, EC has been classified into two groups: Type I estrogen-dependent adenocarcinomas, which have a good prognosis and an endometrioid histology, and Type II or non-estrogen-dependent EC associated with poor prognosis and non-endometrioid histology. EC develops as a result of a stepwise accumulation of alterations that seem to be specific of each histological type. However, more knowledge is needed to better understand the differences in the biology and the clinical outcome of EC. We would like to highlight the need to explore new potential biomarkers of EC as a tool for the detection and monitoring of aggressive endometrial tumors that, at the same time, will allow us to develop novel and more selective molecular targeted therapies against EC.

Generation and characterization of orthotopic murine models for endometrial cancer

We describe the generation of two orthotopic murine models for endometrial cancer (EC).The first model is generated from endometrial Hec-1A cancer cells transfected with luciferase and injected directly into the uterus of female mice. This model allows a follow-up with bioluminescence imaging (BLI) along the experiment and generates abdominal dissemination and lymphatic and hematogenous metastases in high percentages, also detectables with BLI. The dissemination pattern of this model imitates the advanced stages of EC in patients, and its molecular profile corresponds to aggressive type 2 EC (p53 positive, hormone receptors negative, high percentage of Ki67 positive cells). The second model is derived from endometrioid human tissue collected from surgical pieces. By injecting this tissue inside the uterine cavity of a mouse we obtain orthotopic growth with pelvic dissemination and lymph node metastasis. The molecular pattern observed in human type 1 endometrioid EC (p53 negative, low Ki67 index, presence of hormone receptors) is conserved after the murine growth in orthotopic tumor and metastases. This model supposes a singular pre-clinical tool to study therapeutic agents, though it mimics clinical and molecular behavior of endometrioid EC, which is the most common histology in the patient.

MiR-125b promotes proliferation and migration of type II endometrial carcinoma cells through targeting TP53INP1 tumor suppressor in vitro and in vivo

BACKGROUND

Our previous studies have identified that miR-125b was overexpressed in type II endometrial carcinoma (EC) cells compared with type I using microRNAs microarray. Although recent studies have shown the important role of miR-125b in several tumors and overexpression of miR-125b in advanced EC, its function in this disease has not yet been defined. In the present study, we tried to confirm the result of microRNAs microarray and further investigated the functions of miR-125b in EC, and tried to find new downstream targets of miR-125b.

METHODS

Differential expression of miR-125b was detected between type II EC cells (KLE, AN3CA) with ER negative and type I EC cells (ishikawa, RL95-2) with ER positive by qRT-PCR and northern blotting. The effects of miR-125b of on proliferation, migration, and target protein expression were evaluated by CCK8 assay, wound healing assay, transwell migration assay, western blotting, and Tumorigenicity assays in nude mice. In addition, luciferase reporter plasmid was constructed to demonstrate the direct target of miR-125b.

RESULTS

MiR-125b was overexpressed in type II EC cells compared with type I. Exogenous miR-125b expression increased proliferation and migration of ishikawa cells and abrogating expression of miR-125b suppressed proliferation, and migration of AN3CA cells in vitro. In addition, in vivo tumor formation assay confirmed that forced miR-125b expression promoted proliferation potential of ishikawa cells, and tumor suppressor gene Tumor Protein 53-Induced Nuclear Protein 1 (TP53INP1) was identified to be the direct target of miR-125b.

CONCLUSIONS

TP53INP1 was newly identified to be the direct downstream target of miR-125b. MiR-125b, which was overexpressed in type II EC cells compared with type I, contributes to malignancy of type II EC possibly through down-regulating TP53INP1.

Aromatase inhibition: a potential target for the management of recurrent or metastatic endometrial cancer by letrozole: more questions than answers?

INTRODUCTION

Endometrial cancer generally presents as early and resectable disease, but about 20% of patients present with either incurable or recurrent/metastatic disease. Patients with good performance status will be treated with hormonal agents, including progestins and tamoxifen, followed by cytotoxic chemotherapy. The options are restricted to hormonal agents for those with multiple comorbidities and older age. Therefore, there is a need to identify novel hormonal agents and other targeted therapeutics with improved therapeutic window in this setting.

AREA COVERED

Clinical trials of letrozole in localized and metastatic settings are reviewed. In the localized setting, limited by the small sample size, preliminary and conflicting clinical activities were observed. Despite the selection of Type I endometrial cancer, which is more estrogen-dependent for its growth, modest clinical activity was observed in the metastatic setting. Thus far, no biomarkers for efficacy have been identified.

EXPERT OPINION

Further understanding of the relevance of aromatase and estrogen receptor and their interplay with other growth pathways will be necessary to guide further development of letrozole. It is premature to declare letrozole a therapeutic option in recurrent/metastatic endometrial cancer.

Icaritin causes sustained ERK1/2 activation and induces apoptosis in human endometrial cancer cells

Icaritin, a compound from Epimedium Genus, has selective estrogen receptor (ER) modulating activities, and posses anti-tumor activity. Here, we examined icaritin effect on cell growth of human endometrial cancer Hec1A cells and found that icaritin potently inhibited proliferation of Hec1A cells. Icaritin-inhibited cell growth was associated with increased levels of p21 and p27 expression and reduced cyclinD1 and cdk 4 expression. Icaritin also induced cell apoptosis accompanied by activation of caspases as evidenced by the cleavage of endogenous substrate Poly (ADP-ribose) polymerase (PARP) and cytochrome c release, which was abrogated by pretreatment with the pan-caspase inhibitor z-VAD-fmk. Icaritin treatment also induced expression of pro-apoptotic protein Bax with a concomitant decrease of Bcl-2 expression. Furthermore, icaritin induced sustained phosphorylation of extracellular signal-regulated kinase1/2 (the MAPK/ ERK1/2) in Hec1A cells and U0126, a specific MAP kinase kinase (MEK1/2) inhibitor, blocked the ERK1/2 activation by icaritin and abolished the icaritin-induced growth inhibition and apoptosis. Our results demonstrated that icaritin induced sustained ERK 1/2 activation and inhibited growth of endometrial cancer Hec1A cells, and provided a rational for preclinical and clinical evaluation of icaritin for endometrial cancer therapy.

Poly(ADP-ribose) polymerase (PARP) inhibitors: Exploiting a synthetic lethal strategy in the clinic

Poly(ADP-ribose) polymerase (PARP) is an attractive antitumor target because of its vital role in DNA repair. The homologous recombination (HR) DNA repair pathway is critical for the repair of DNA double-strand breaks and HR deficiency leads to a dependency on error-prone DNA repair mechanisms, with consequent genomic instability and oncogenesis. Tumor-specific HR defects may be exploited through a synthetic lethal approach for the application of anticancer therapeutics, including PARP inhibitors. This theory proposes that targeting genetically defective tumor cells with a specific molecular therapy that inhibits its synthetic lethal gene partner should result in selective tumor cell killing. The demonstration of single-agent antitumor activity and the wide therapeutic index of PARP inhibitors in BRCA1 and BRCA2 mutation carriers with advanced cancers provide strong evidence for the clinical application of this approach. Emerging data also indicate that PARP inhibitors may be effective in sporadic cancers bearing HR defects, supporting a substantially wider role for PARP inhibitors. Drugs targeting this enzyme are now in pivotal clinical trials in patients with sporadic cancers. In this article, the evidence supporting this antitumor synthetic lethal strategy with PARP inhibitors is reviewed, evolving resistance mechanisms and potential molecular predictive biomarker assays are discussed, and the future development of these agents is envisioned.

Rapamycin inhibits cell proliferation in type I and type II endometrial carcinomas: a search for biomarkers of sensitivity to treatment

OBJECTIVES

Our goal was to evaluate the effect of rapamycin, an mTOR inhibitor, in type I and II human endometrial cancer tumor explants.

METHODS

Short-term tissue culture with fresh endometrial cancer tumor explants was performed. Cell proliferation was assessed by MTS assay after treatment with rapamycin. Akt and PTEN status were documented by Western blotting. The effect of rapamycin on phosphorylated-S6 and 4E-BP-1 was also assessed by Western blotting. Real-time RT-PCR was used to quantify hTERT mRNA expression. Telomere length was determined by terminal restriction fragment Southern blotting.

RESULTS

Thirteen fresh endometrial cancer tumor explants (nine Type I, four Type II) were placed in short-term culture and treated with rapamycin. Nine of the endometrial cancer tumors responded to rapamycin, with a median IC₅₀ of 11.4 nM. Sensitivity to rapamycin was independent of PTEN and Akt status. Tumors (13/13) had a reduction in phosphorylated-S6 and 10/13 had a reduction in phosphorylated 4E-BP-1. Rapamycin decreased hTERT mRNA expression in all of the endometrial cancer tumors. Telomere length did not correspond with responsiveness to this drug.

CONCLUSIONS

Rapamycin demonstrated activity in fresh endometrial tumor explants independent of PTEN and Akt status. Some tumors demonstrated a reduction in phosphorylated-S6 and 4E-BP-1 without a significant change in cellular proliferation, suggesting that additional pathways may modulate cellular proliferation. Thus, mTOR inhibitors may be a useful targeted therapy for both type I and type II endometrial cancers, but the search remains for a predictive biomarker of sensitivity to this therapy.