Endometrial Cancer Proliferation Research Articles

17β-Estradiol promotes endometrial cancer proliferation and invasion through IL-6 pathway.

Accumulating evidence revealed that the leading risk factor of endometrial cancer is exposure to endogenous and exogenous estrogens, while the exact mechanism underlying estrogen contribution to endometrial cancer progression has not been elucidated clearly. Interleukin (IL)-6 has been verified to be critical for tumor progression in several human cancers. In this study, we provided evidence that 17β-estradiol (E2) could significantly promote endometrial cancer cells viability, migration and invasion through activation of IL-6 pathway, which involved in its downstream pathway and target genes (p-Stat3, Bcl-2, Mcl-1, cyclin D1 and MMP2). Meanwhile, utilization of IL-6-neutralizing antibody could partially attenuate the increased cancer growth and invasion abilities in Ishikawa and RL95-2 endometrial cancer cell lines and an orthotopic endometrial cancer model. We established a causative link between estrogen and IL-6 signaling activation in the development of endometrial cancer. The molecular mechanism defined in this study provided the evidence that E2 promotes endometrial carcinoma progression via activating the IL-6 pathway, indicating that interruption of IL-6 might be an essential therapeutic strategy in estrogen-dependent endometrial cancer.

Effects of Metformin on Cellular Proliferation and Steroid Hormone Receptors in Patient-Derived, Low-Grade Endometrial Cancer Cell Lines.

Endometrial cancer (EC) is the most common gynecologic malignancy and is the result of disruption of the balance between estrogen-stimulated growth and progesterone-induced growth modulation. Metformin has been shown to inhibit EC proliferation; however, its role in early-stage EC and its effects on steroid hormone receptors have not been adequately explored. Our aim was to examine the effects of metformin on cellular proliferation in patient-derived, low-grade EC cell lines and to determine whether it directly modulates steroid hormone receptor expression. Two novel EC cell lines were produced (EM2 and 3) from endometrial tumor tissue obtained from women undergoing surgery. Cellular proliferation was determined by the 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay, and in both cell lines, metformin decreased cell proliferation in a dose-dependent (10-200 µmol/L) manner and induced apoptosis as measured by cleaved PARP. Furthermore, metformin abrogated the effects of E2 on cell proliferation. Using quantitative real-time polymerase chain reaction and Western immunoblotting, metformin significantly decreased estrogen receptor (ER) α messenger RNA abundance but did not consistently affect the expression of progesterone receptor. Estrogen receptor α protein levels significantly decreased across all metformin doses tested, which resulted in a significant decrease in the expression of the ER targets genes Keratin-19 and Wnt-1 inducible signaling pathway 2. In addition, metformin increased phosphorylation of AMPK in a dose-dependent manner (10-200 µmol/L) indicating an effect on mammalian target of rapamycin (mTOR) signaling. Our data suggest that metformin therapy represents a potential fertility-sparing option for women with early-stage EC, given its capacity to inhibit EC cell proliferation, ERα expression, and the mTOR cell proliferation pathway.

Estrogen Enhances Endometrial Cancer Cells Proliferation by Upregulation of Prohibitin.

Estrogen plays an essential role in type I endometrial cancer cell proliferation. Despite great progresses in the etiology has been obtained in the past, however, the molecular mechanisms remain to be fully clarified. Prohibitin has been demonstrated involvement in multiple cancers' development. If it also contributes to estrogen-driven endometrial cancer proliferation is not clear. IHC assay result display that prohibitin overexpressed in endometrial cancer tissue and associated with the poor prognosis; Western blot assay detect that upregulated prohibitin expression with dose- and time-dependent manners. The cellular growth was monitored with SRB assay which demonstrate that knockdown prohibitin attenuated estrogen-induced proliferation. Ubiquitination assay finds estrogen increased prohibitin level through stabilizing prohibitin protein via inhibition of ubiquitination, while estrogen-induced protein expression was mediated by estrogen receptor. Our findings provide a new insight on the mechanism of estrogen-induced proliferation, implying the possibility of using prohibitin as a potential therapeutic target for the treatment of endometrial cancer.

MiR-142 Suppresses Endometrial Cancer Proliferation In Vitro and In Vivo by Targeting Cyclin D1.

Endometrial cancer (EC), a prevalent gynecologic tumor, is a great threat to women. We aimed to explore miR-142's effects on EC and the relevant mechanisms. Cell proliferation was evaluated with MTT, cell counting, and colony formation assay. MRNA abundances of miR-142 and cyclin D1 (CCND1) were examined with quantitative real-time PCR. CCND1 protein level in cells was analyzed with Western blot. miR-142's downstream target was identified with targetscan and luciferase reporter assay. Nude mice were injected subcutaneously with Ishikawa (ISK) cells transfected with or without miR-142 mimics. Ki-67 and CCND1 expressions in tumors of xenograft mice were analyzed with immunohistochemical assay. miR-142 was expressed at a lower level in human EC tumor samples than matched normal tissues, and its mRNA level in EC patients without metastasis was higher than that in patients with metastatic EC. Additionally, low-level miR-142 was closely linked with the poor prognosis of EC patients. miR-142 restricted ISK and HEC-1A cell proliferation. Targetscan and luciferase reporter assay proved the target relationship between miR-142 and CCND1. Moreover, high-level CCND1 was positively correlated with the poor prognosis of EC patients. Besides, miR-142 mimics restricted tumor growth in ISK xenografted mice, as well as inhibited the expression of Ki67 and CCND1 in excised tumors. miR-142 restricted EC proliferation by targeting CCND1.

The impact of 27-hydroxycholesterol on endometrial cancer proliferation

The impact of 27-hydroxycholesterol on endometrial cancer proliferation

The impact of 27-hydroxycholesterol on endometrial cancer proliferation.

Endometrial cancer (EC) is the most common gynaecological malignancy. Obesity is a major risk factor for EC and is associated with elevated cholesterol. 27-hydroxycholesterol (27HC) is a cholesterol metabolite that functions as an endogenous agonist for Liver X receptor (LXR) and a selective oestrogen receptor modulator (SERM). Exposure to oestrogenic ligands increases risk of developing EC; however, the impact of 27HC on EC is unknown. Samples of stage 1 EC (n = 126) were collected from postmenopausal women undergoing hysterectomy. Expression of LXRs (NR1H3, LXRα; NR1H2, LXRβ) and enzymes required for the synthesis (CYP27A1) or breakdown (CYP7B1) of 27HC were detected in all grades of EC. Cell lines originating from well-, moderate- and poorly-differentiated ECs (Ishikawa, RL95, MFE 280 respectively) were used to assess the impact of 27HC or the LXR agonist GW3965 on proliferation or expression of a luciferase reporter gene under the control of LXR- or ER-dependent promoters (LXRE, ERE). Incubation with 27HC or GW3965 increased transcription via LXRE in Ishikawa, RL95 and MFE 280 cells (P < 0.01). 27HC selectively activated ER-dependent transcription (P < 0.001) in Ishikawa cells and promoted proliferation of both Ishikawa and RL95 cells (P < 0.001). In MFE 280 cells, 27HC did not alter proliferation but selective targeting of LXR with GW3965 significantly reduced cell proliferation (P < 0.0001). These novel results suggest that 27HC can contribute to risk of EC by promoting proliferation of endometrial cancer epithelial cells and highlight LXR as a potential therapeutic target in the treatment of advanced disease.

ATX‑LPA axis facilitates estrogen‑induced endometrial cancer cell proliferation via MAPK/ERK signaling pathway.

Autotaxin (ATX) is a key enzyme that converts lysophosphatidylcholine to lysophosphatidic acid (LPA). ATX is a crucial factor that facilitates cancer progression; however, the effect of ATX on endometrial cancer has not been explored. The aim of the present study was to investigate the role of ATX in the progression of endometrial cancer. The immunohistochemical results revealed higher protein expression levels of ATX and LPA receptors (LPA 1, 2 and 3) in human endometrial cancer tissue than in non-carcinoma tissue. In addition, reverse transcription-quantitative polymerase chain reaction and western blotting analysis demonstrated that ATX and LPA receptor mRNA and protein expression was greater in Ishikawa cells, which are positive for estrogen receptor (ER), than in Hec-1A cells that exhibit low ER expression. Short interfering RNA knockdown of ATX in Ishikawa cells led to decreased cell proliferation and cell colony number, as determined by Cell Counting kit-8 and colony formation assays. Estrogen stimulated ATX mRNA expression. Inhibition of ATX decreased estrogen and LPA-induced cell proliferation. High LPA levels markedly elevated the phosphorylation levels of extracellular signal-regulated kinase (ERK). ATX downregulation moderately decreased estrogen- and LPA-induced phosphorylation of ERK. In addition, the ERK inhibitor, PD98059, reduced cell proliferation with estrogen, ATX and LPA treatment. The present study suggested that the ATX-LPA axis may facilitate estrogen-induced cell proliferation in endometrial cancer via the mitogen-activated protein kinase/ERK signaling pathway. The present study may provide ideas and an experimental basis for clinicians to identify new molecular targeted drugs for the treatment of endometrial cancer.

Pre-Surgical Metformin in Uterine Malignancy (Premium): A Multi-Centre, Randomised Double-Blind, Placebo-Controlled Phase 3 Trial

Background: Endometrial cancer is strongly associated with obesity and insulin resistance. Metformin, an insulin sensitizer, reduces endometrial tumour growth in vitro. Pre-surgical window studies allow rapid in vivo assessment of anti-tumour activity. Previous window studies found short-term metformin treatment reduced endometrial cancer proliferation but these lacked methodological rigor, particularly control arms for comparison. PREMIUM was designed to definitively determine the anti-proliferative effect of metformin in vivo using a robust window study design. Methods: A randomised, double-blind, placebo-controlled phase 3 trial was conducted in five hospitals in England. Eligible women had biopsy-proven atypical endometrial hyperplasia or endometrioid endometrial cancer and were not receiving anti-diabetic medication. Women were computer-randomised (1:1) using the permuted block method (block size 30) to metformin (850mg daily for three days, increased to twice daily thereafter) or placebo for 1-5 weeks, until the evening before surgery. Participants and researchers were blinded to treatment group allocation. The primary outcome was post-treatment immunohistochemical expression of Ki-67 in the hysterectomy specimen; a modified intention-to-treat analysis included all women taking at least one dose of study drug and undergoing tumour biopsy within 72 hours of treatment discontinuation. Safety analysis included all women receiving at least one dose of drug. Findings: Between February 2015-2017, 93 women were randomised to metformin (n=47) or placebo (n=46), with five withdrawals (four without taking any drug and one because of no post-treatment biopsy). Eighty-eight women were included in the final analysis (metformin n=45, placebo n=43). There was no overall difference in post-treatment Ki-67 between the metformin and placebo arms, in an ANCOVA analysis adjusting for baseline Ki-67 expression (mean difference -0·57%, 95% CI -7·57% to 6·42%, p=0·87). Women receiving metformin reported significantly more adverse events than those receiving placebo (37 [82·2%] vs. 25 [58·1%], p=0·001), especially nausea and vomiting (17 [37·8%] vs. 6 [13·6%], p=0·015), diarrhoea (23 [51·1%] vs. 6 [13·6%], p=0·0003) and anorexia (9 [20·0%] vs. 0 [0·0%], p=0·003), but did not discontinue treatment.. Interpretation: Short term treatment with standard diabetic doses of metformin does not reduce tumour proliferation in women with endometrial cancer awaiting hysterectomy. This study does not support a biological effect of metformin in endometrial cancer and casts doubt on its potential application in the primary and adjuvant treatment settings. Future studies should focus on primary and secondary prevention of endometrial cancer and pursue longer treatment windows. Clinical Trial Number: The study was registered on UK and European clinical trials databases (ISRCTN 88589234, EudraCT number 2014-000991-25) and is closed to recruitment. Funding Statement: National Institute for Health Research Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: All participants provided written, informed consent. The trial was approved by the North West Research Ethics Committee (14/NW/1236), Medicine and Healthcare Products Regulatory Authority (MHRA, reference 21387/0232/001-0001) and local Research and Development departments.

RG108 induces the apoptosis of endometrial cancer Ishikawa cell lines by inhibiting the expression of DNMT3B and demethylation of HMLH1.

The effects of DNA methyltransferase (DNMT) inhibitor RG108 on the proliferation and apoptosis of endometrial cancer was investigated, and whether its mechanism was related to the inhibition of DNMT3B, thereby affecting the human mutL homolog 1 (hMLH1) methylation status and its expression, was further studied. Culture of human endometrial cancer Ishikawa cell lines: cells grew adhering to the wall in Roswell Park Memorial Institute-1640 (RPMI-1640) medium (supplemented with 10% fetal bovine serum (FBS) and 2 mM L-glutamic acid). After the cells were treated with RG108, the changes in cell viability were detected via methyl thiazolyl tetrazolium (MTT) assay. The effect of RG108 on cell cycle was detected via flow cytometry, and its effect on cell apoptosis was detected via flow cytometry and TUNEL. Moreover, the methylation status of hMLH1gene in endometrial cancer cells was detected via methylation specific-PCR (MSP), and the changes in DNMT3Band hMLH1 expressions were detected via RT-PCR and Western blotting, respectively. MTT results showed that RG108 inhibited the cell viability in a dose-dependent and time-dependent manner. Flow cytometry revealed that RG108 blocked the cell cycle in G2/M phase and promoted the apoptosis, and TUNEL assay further proved that RG108 promoted the apoptosis. It was found in the detection via MSP that the methylated hMLH1 gene was significantly reduced after 72 h of treatment with RG108. Besides, RT-PCR and Western blotting showed that RG108 inhibited the DNMT3B expression and activated the hMLH1 expression. The demethylation drug RG108 can significantly inhibit the proliferation of endometrial cancer cells, block the cell cycle in the G2/M phase and induce the cell apoptosis, which is a new candidate drug in the treatment of endometrial cancer. RG108 realizes the hMLH1 demethylation and increases the hMLH1 expression through inhibiting the expression of DNMT3B.

Carfilzomib induces G2/M cell cycle arrest in human endometrial cancer cells via upregulation of p21Waf1/Cip1 and p27Kip1

ObjectiveCarfilzomib is a second-generation tetrapeptide epoxyketone proteasome inhibitor used in current clinical therapy of hematologic malignancies. The mechanism of proteasome inhibition in endometrial cancer is not very clear. Carfilzomib inhibition of type I endometrial carcinoma cell proliferation by inducing cell cycle arrest at the G2/M phase was investigated in our study. Materials and methodsHEC-1-A and Ishikawa endometrial carcinoma cell lines and three tumor cell lines were treated by different concentrations of carfilzomib. Methyl thiazolyl tetrazolium (MTT) assay was used to detect cell viability. Flow cytometry was used to analyze the cell cycle. Western blot was used to detect proteins involved in cell cycle progression. ResultsCarfilzomib impaired viability of myelogenous leukemia cell line K562, cervical cancer cell line HeLa, hepatocellular carcinoma cell line SMCC-7721, and endometrial carcinoma cell lines HEC-1-A and Ishikawa. The cell cycle was arrested at the G2/M phase in carfilzomib-treated HEC-1-A endometrial carcinoma cells, while it was arrested at both S and G2/M phases in carfilzomib-treated Ishikawa cells. Carfilzomib treatment significantly induced p21Waf1/ Cip1 and p27, while substantially reduced cyclin D3 and cyclin-dependent kinase 1. ConclusionThis study showed that carfilzomib inhibited endometrial cancer proliferation by upregulating cyclin-dependent kinase inhibitors p21Waf1/Cip1 and p27Kip1, and reducing cyclin-dependent kinase 1 to arrest the cell cycle at the G2/M phase.

Urolithin A suppresses the proliferation of endometrial cancer cells by mediating estrogen receptor‐α‐dependent gene expression

Obese and overweight women are at high risk of developing endometrial cancer; indeed, many of endometrial cancer patients are obese. The increased number and size of adipocytes due to obesity elevate levels of circulating estrogens that stimulate cell proliferation in the endometrium. However, black raspberries are a promising approach to preventing endometrial cancer. We examined 17 black raspberry constituents and metabolites (10 μM or 10 μg/mL, 48 h) for their ability to prevent endometrial cancer cells from proliferating. Urolithin A (UA) was most able to suppress proliferation in a time- and dose-dependent manner (p < 0.05). It arrested the G2/M phase of the cell cycle by upregulating cyclin-B1, cyclin-E2, p21, phospho-cdc2, and CDC25B. UA also acted as an estrogen agonist by modulating estrogen receptor-α (ERα) dependent gene expression in ER-positive endometrial cancer cells. UA enhanced the expression of ERβ, PGR, pS2, GREB1 while inhibiting the expression of ERα and GRIP1. Coincubating UA-treated cells with the estrogen antagonist ICI182,780 abolished UA's estrogenic effects. Knocking down ERα suppressed PGR, pS2, and GREB gene expression but increased GRIP1 expression. Thus, UA's actions appear to be mediated through ERα. This study suggests that UA modulates ERα-dependent gene expression, thereby inhibiting endometrial cancer proliferation.

Reactivation of epigenetically silenced miR-124 reverses the epithelial-to-mesenchymal transition and inhibits invasion in endometrial cancer cells via the direct repression of IQGAP1 expression.

Overexpression of IQGAP1 and microRNA (miRNA) dysregulation are frequent in human tumors, but little is known about the role of IQGAP1 and its relationship to miRNA in endometrial carcinogenesis. We demonstrate that IQGAP1 activates the epithelial–mesenchymal transition (EMT) program and that miR-124 directly represses IQGAP1 expression in endometrial cancer (EC) cells. The overexpression of IQGAP1 stimulates EMT features and enhances migration, invasion and proliferation of EC cells, whereas knocking down IQGAP1 expression reverses EMT and inhibits these malignant properties. Using miRNA microarray profiling, we identified 29 miRNAs (let-7b, let-7f, miR-10b, miR-15b, miR-23a, miR-24, miR-25, miR-27a, miR-29b, miR-30a-5p, miR-34a, miR-124, miR-127, miR-130b, miR-148a, miR-155, miR-191*, miR-194, miR-224, miR-362, miR-409-3p, miR-422b, miR-424, miR-453, miR-497, miR-518d, miR-518f*, miR-526a and miR-656) that are significantly down-regulated in an in vitro-selected highly invasive derivative cell line (HEC-50-HI) relative to the parental HEC-50 cells. We further identified miR-124 as a direct regulator of IQGAP1 in EC cells. Enforced expression of miR-124 suppresses EC cell invasion and proliferation. The expression of IQGAP1 mRNA was significantly elevated in EC tissues, while the expression of miR-124 was decreased. The downregulation of miR-124 correlates with a poor survival outcome for patients with EC. Treating EC cells with the demethylating agent 5-aza-2′-deoxycytidine increased miR-124 expression and down-regulated IQGAP1 levels. Our data suggest that IQGAP1 promotes EMT, migration and invasion of EC cells. MiR-124, a novel tumor suppressor miRNA that is epigenetically silenced in EC, can reverse EMT and the invasive properties, by attenuating the expression of the IQGAP1 oncogene.

Effects of receptor for advanced glycation endproducts on microvessel formation in endometrial cancer.

BackgroundThe receptor for advanced glycation endproducts (RAGE) and microvascular status both play a critical role in cancer progression. However, the crosstalk between RAGE and microvascular formation in endometrial cancer remains largely unknown.MethodsRAGE expression and microvessel density were examined in 20 cases of normal endometrial tissue, 37 cases of well-differentiated endometrial cancer tissue, and 35 cases of poorly-differentiated endometrial cancer tissue. Regression analysis was used to examine the relationship between RAGE and microvessel density. The knockdown of RAGE was achieved using a small interfering RNA in HEC-1A endometrial cancer cells. A xenografted tumour model was used to evaluate RAGE-mediated microvascular formation and proliferation of endometrial cancer cells.ResultsIt was shown that (i) RAGE expression gradually increased in normal endometrium, well-differentiated endometrial cancer, and poorly-differentiated endometrial cancer, respectively; (ii) a positive correlation existed between RAGE and microvessel density in human endometrial cancer samples; (iii) RAGE knockdown was effective in decreasing microvessel formation in xenografted tumour models; and (iv) RAGE knockdown can significantly inhibit the proliferation of endometrial cancer cells in vivo.ConclusionsThese results indicate that RAGE may be a potential trigger in microvascular formation and proliferation in the development of endometrial cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2126-3) contains supplementary material, which is available to authorized users.

Measuring the biological effect of presurgical metformin treatment in endometrial cancer

Background:Preclinical studies in endometrial cancer (EC) show that metformin reduces cellular proliferation by PI3K-AKT-mTOR inhibition. We tested the hypothesis that short-term presurgical metformin reduces cellular proliferation in atypical endometrial hyperplasia (AEH) and endometrioid EC, and assessed the feasibility of using phosphorylated PI3K-AKT-mTOR proteins as tissue end points.Methods:Women with AEH or EC received metformin 850 mg twice a day or no drug in the presurgical window between diagnosis and hysterectomy. Before and after the window, tissue samples were obtained; serum markers of insulin resistance (e.g. homeostasis model of assessment of insulin resistance index) were determined; and anthropometrics measured (e.g. BMI). Cell proliferation (Ki-67) and PI3K-AKT-mTOR phosphostatus were assessed by immunohistochemistry and scored blinded to treatment.Results:Twenty-eight metformin-treated and 12 untreated patients, well matched for age and BMI, completed the study. Metformin treatment (median 20 days, range 7–34) was associated with a 17.2% reduction in tumour Ki-67 (95% CI −27.4, −7.0, P=0.002), in a dose-dependent manner. Tumour PI3K-AKT-mTOR protein phosphostatus varied but the effects were not significant after adjusting for changes in controls.Conclusions:Short-term metformin was associated with reduced Ki-67 expression in EC. Changes in tumour PI3K-AKT-mTOR protein phosphostatus were seen in both groups. Future studies should address the variability attributed to different sampling techniques including devascularisation of the uterus at hysterectomy.

Glucose promotes cell proliferation, glucose uptake and invasion in endometrial cancer cells via AMPK/mTOR/S6 and MAPK signaling

ObjectivesObesity and diabetes are well-known risk factors for the development of endometrial cancer. A high rate of aerobic glycolysis represents a key mechanism by which endometrial cancer cells consume glucose as its primary energy source. The up-regulated glycolytic pathway is a common therapeutic target whose inhibition has implications for anti-tumor activity in cancer cells. This study aimed to investigate the effect of various concentrations of glucose on cell proliferation in endometrial cancer. MethodsECC-1 and Ishikawa cells were treated with low glucose (1mM), normal glucose (5mM) and high glucose (25mM), and cytotoxicity, apoptosis, cell cycle, adhesion/invasion, and changes of AMPK/mTOR/S6 and MAPK pathways were evaluated. ResultsOur results revealed that high glucose increased cell growth and clonogenicity in two endometrial cancer cell lines in a dose dependent manner. Low glucose induced the activity of cleaved caspase 3 and caused cell cycle G1 arrest. High glucose increased the ability of adhesion and invasion by decreasing E-cadherin and increasing Snail expression. In addition, high glucose increased glucose uptake and glycolytic activity through modulating the AMPK/mTOR/S6 and MAPK pathways. ConclusionsOur findings suggest that glucose stimulated cell proliferation through multiple complex signaling pathways. Targeting glucose metabolism may be a promising therapeutic strategy in the treatment of endometrial cancer.

Increased angiogenesis is associated with a 32-gene expression signature and 6p21 amplification in aggressive endometrial cancer.

Angiogenesis is a hallmark of cancer. The aim of this study was to explore whether microvessel proliferation is associated with gene expression profiles or copy number alterations in endometrial cancer. A prospective series of endometrial carcinomas was studied for angiogenesis markers, gene expression profiles, and gene copy number data. For validation, an independent series of endometrial carcinomas as well as an external cohort of endometrial cancer patients were examined by gene expression microarrays. Increased microvessel proliferation (MVP) was associated with aggressive tumor features and reduced survival, and a 32-gene expression signature was found to separate tumors with high versus low MVP. An increased 32-gene signature score was confirmed to associate with high-grade tumor features and reduced survival by independent cohorts. Copy number studies revealed that amplification of the 6p21 region was significantly associated with MVP, a high 32-gene score, as well as reduced survival. Increased MVP was significantly associated with aggressive endometrial cancer and reduced survival. Integrated analyses demonstrated significant associations between increased vascular proliferation, amplification of the 6p21 region, VEGF-A mRNA expression, and the 32-gene angiogenesis signature. Our findings indicate amplification of 6p21 as a possible driver of tumor vascular proliferation in endometrial cancer.

Molecular mechanisms of tamoxifen-associated endometrial cancer (Review).

Tamoxifen has been prescribed to millions of females for breast cancer prevention or treatment. However, tamoxifen is known to significantly enhance the risk of developing endometrial lesions, including hyperplasia, polyps, carcinomas, and sarcoma. Notably, tamoxifen-associated endometrial cancer often has a poor clinical outcome. Understanding the molecular mechanism of tamoxifen-induced endometrial cancer is essential for developing strategies that minimize tamoxifen’s effects on the endometrium without jeopardizing its breast cancer treatment effects. However, this understanding remains limited. Tamoxifen appears to mediate its effect on endometrial cells through estrogenic and non-genomic pathways, rather than introducing a genomic alteration as a carcinogen. Although tamoxifen functions as an agonist and promotes cell proliferation in endometrial cancer, it also displays antagonist activity towards some estrogen targets. Alterations in estrogen receptor-α and its isoforms, as well as the membrane associated estrogen receptor G protein-coupled receptor 30, have been observed with tamoxifen-exposed endometrial cells, and likely mediate the effects of tamoxifen on endometrial cancer cell proliferation and invasion. In addition, gene profile studies of short-term exposure to tamoxifen indicate that the majority of tamoxifen targets are tamoxifen-specific. However, the tamoxifen regulated gene targets that are involved in mediating the effects of long-term exposure to tamoxifen are not yet fully understood. Recent progress has indicated a potential role of unfolded protein response and mammalian target of rapamycin signaling in tamoxifen-associated endometrial cancer. In the future, studies focusing on long-term effects of tamoxifen exposure are required to understand the molecular mechanisms of tamoxifen-associated endometrial cancer.

Abstract 1078: Cancer-associated fibroblasts promote endometrial cancer cell proliferation in vitro and in vivo

Abstract Cancer-associated fibroblasts (CAFs) recently demonstrated tumor-promoting roles in various cancer types, yet their implication in endometrial cancer (EC) has not been fully explored. We isolated fibroblasts (CAFs) and its epithelial counterpart from human EC tissues using CD90- and CD326-antibodies conjugated magnetic beads, respectively. We collected CAFs secretion by concentrating spent supernatants from cells growing in media containing 2% fetal bovine serum. Both human EC cell lines and primary EC epithelial cells showed increased cell proliferation in a dose-dependent manner, following treatment with CAFs secretion. This was in contrast to the growth inhibitory effects shown with secretions from normal endometrial fibroblasts. EC cells also demonstrated increased cell motility and invasiveness in response to CAFs secretion. Using cytokine array and ELISA, we further identified several cytokines which were overexpressed in CAFs compared to normal endometrial fibroblasts: macrophage chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), growth regulated oncogene (GRO), regulated on activation, normal T cell expressed and secreted (RANTES) and vascular endothelial growth factor (VEGF). These cytokines may activate MAPK/Erk and/or PI3K/Akt pathways to promote EC cell proliferation, as shown by immunoblotting and ELISA. Indeed, CAFs-mediated EC proliferation was suppressed independently by specific inhibitors for PI3K/Akt (LY294002) and MAPK/Erk (U0126). To determine if CAFs promote EC tumor proliferation in vivo, we inoculated fluorescently labeled-epithelial cell and CAFs subcutaneously at the flank of nude mice in the ratio of 1:2 and 1:4. Tumor sizes were measured twice a week using calipers and monitored weekly using in vivo imaging. Inoculation of CAFs and normal fibroblasts alone did not induce any tumor growth; however, co-injection of EC with CAFs (1:4) showed approximately 3 times higher growth rate when compared to EC alone. More interestingly, there was no sign of tumor growth in mice inoculated with combination of EC and normal fibroblasts (1:4) at the end of experiment. Taken together, our data suggests that CAFs exert tumor-promoting effects both in vitro and in vivo partly via specific cytokines-mediated activation of MAPK/Erk and PI3K/Akt pathways. Delineating the roles of CAFs in EC tumor microenvironment may provide potential therapeutic targets for the treatment of EC. Citation Format: Ivy Chung, Kavita S. Subramaniam, Seng Tian Tham, Zahurin Mohamed, Noor Azmi Mat Adenan, Yin Ling Woo. Cancer-associated fibroblasts promote endometrial cancer cell proliferation in vitro and in vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1078. doi:10.1158/1538-7445.AM2014-1078

The role of adipose-derived stem cells in endometrial cancer proliferation

Background. Obesity has been identified as a key risk factor for the development of endometrial cancer (EC), the most common gynecologic malignancy in the US. We hypothesized that adipose tissue from EC patients secretes higher levels of cancer-promoting factors than healthy adipose tissue and promotes tumor cell growth. Methods. In this study, we generated conditioned media from adipose-derived stem cells (ASCs), an important regenerative cell population within adipose tissue. ASCs were isolated from adipose tissue from two EC patients undergoing hysterectomies and four cancer free control patients undergoing elective abdominoplasties. Ishikawa cells were then cultured for 48 hours in ASC-conditioned media (ASC-CM). Study outcomes included cancer cell proliferation rates and angiogenic factor secretion from cancer cells. Results. Our results indicate that ASC-conditioned media significantly increased Ishikawa cell proliferation rate when compared to control Ishikawa culture conditions (p = 0.002). Though not significant, Ishikawa proliferation with conditioned media from EC ASCs was higher than proliferation in conditioned media from control ASCs. Additionally, we found that Ishikawa cells secreted almost 10 % more vascular endothelial growth factor (VEGF) when cultured in EC ASC-CM as compared to Ishikawa cells cultured in healthy (cancer free control) ASC-CM. These results indicate that ASC paracrine factors may positively increase cancer cell growth rate and potentially enhance tumor angiogenesis. Conclusions. Our findings support the hypothesis that adipose tissue is an important source of secreted factors, which increase the rate of EC cell growth. This study provided preliminary evidence that ASCs may be an important parameter to evaluate in relation to EC development.

Correlation of TNFAIP8 overexpression with the proliferation, metastasis, and disease-free survival in endometrial cancer

Tumor necrosis factor alpha-induced protein 8 (TNFAIP8) is an apoptosis regulator proven to have an important function in the proliferation, invasion, metastasis, and progression of malignancies. In this study, we investigated the clinical role of TNFAIP8 overexpression in endometrial cancer (EC) and determined the relationship of TNFAIP8 with the proliferative antigen Ki-67 and metastasis-related gene matrix metallopeptidase 9 (MMP9) in 225 tumor specimens by immunohistochemistry and western blot, in order to elucidate more information on the role of TNFAIP8 protein with regard to the pathogenesis of EC. An association was observed between TNFAIP8 overexpression and clinicopathologic factors, such as advanced International Federation of Gynecology and Obstetrics stage (P<0.001), higher histologic grade (P=0.017), deep myometrial invasion (P=0.030), lymphovascular space invasion (P=0.011), lymph node metastasis (P<0.001), and recurrence. Furthermore, TNFAIP8 overexpression was strongly correlated with MMP9 and Ki-67 expression in the progression of ECs. Patients with high expression of TNFAIP8 (P<0.001 for both) and Ki-67 (P=0.007 and P=0.008) had poor overall survival and disease-free survival (DFS) rates. MMP9 overexpression did not affect survival outcomes (P>0.05). Multivariate Cox regression analysis revealed that TNFAIP8 (P=0.029) and lymph node metastasis (P=0.022) were independent factors of DFS in patients with EC. These findings suggested that TNFAIP8 may be used as a prognostic marker for the recurrence of EC, and its promotion of the proliferation and metastasis in EC may be due to its mediation of Ki-67 and MMP9.