p38 and p42/44 MAPKs differentially regulate progesterone receptor A and B isoform stabilization

Progesterone receptor (PR) isoforms (PRA and PRB) are implicated in the progression of breast cancers frequently associated with imbalanced PRA/PRB expression ratio. Antiprogestins represent potential antitumorigenic agents for such hormone-dependent cancers. To investigate the mechanism(s) controlling PR isoforms degradation/stability in the context of agonist and antagonist ligands, we used endometrial and mammary cancer cells stably expressing PRA and/or PRB. We found that the antiprogestin RU486 inhibited the agonist-induced turnover of PR isoforms through active mechanism(s) involving distinct MAPK-dependent phosphorylations. p42/44 MAPK activity inhibited proteasome-mediated degradation of RU486-bound PRB but not PRA in both cell lines. Ligand-induced PRB turnover required neosynthesis of a mandatory down-regulating partner whose interaction/function is negatively controlled by p42/44 MAPK. Such regulation strongly influenced expression of various endogenous PRB target genes in a selective manner, supporting functional relevance of the mechanism. Interestingly, in contrast to PRB, PRA stability was specifically increased by MAPK kinase kinase 1-induced p38 MAPK activation. Selective inhibition of p42/p44 or p38 activity resulted in opposite variations of the PRA/PRB expression ratio. Moreover, MAPK-dependent PR isoforms stability was independent of PR serine-294 phosphorylation previously proposed as a major sensor of PR down-regulation. In sum, we demonstrate that MAPK-mediated cell signaling differentially controls PRA/PRB expression ratio at posttranslational level through ligand-sensitive processes. Imbalance in PRA/PRB ratio frequently associated with carcinogenesis might be a direct consequence of disorders in MAPK signaling that might switch cellular responses to hormonal stimuli and contribute towards pathogenesis.     

TFCP2L1在子宫内膜癌细胞增殖及侵袭中的作用

摘要 目的：研究人子宫内膜癌中TFCP2L1的表达情况以及分析TFCP2L1对子宫内膜癌细胞增殖及迁移能力的影响。方法：（1）通过TCGA 及GTEx数据库分析子宫内膜癌中TFCP2L1的表达水平及患者生存期。采用Western blot验证正常子宫内膜上皮细胞与多种子宫内膜癌细胞系中TFCP2L1的表达情况。（2）使用CRISPR-Cas9技术敲除Ishikawa细胞系的TFCP2L1,并用流式分选技术筛选单个细胞进行培养,形成单克隆细胞系,以此来研究TFCP2L1对子宫内膜癌的细胞周期和细胞增殖的影响。通过 Western blot 及细胞免疫荧光检测细胞周期相关蛋白的表达,检测细胞增殖情况,采用平板克隆实验及CCK8实验。（3）通过Transwell小室及划痕实验对侵袭和转移能力进行检测。结果：TCGA 及GTEx数据库分析发现TFCP2L1在子宫内膜癌中高表达且与肿瘤患者预后不良相关。敲除TFCP2L1后,Ki67、Cyclin D1 和 Cyclin D2的蛋白水平显著下调,CCK8及平板克隆实验结果表明,敲除TFCP2L1能够显著降低子宫内膜癌细胞的增殖能力。划痕实验及Transwell侵袭实验结果表明敲除TFCP2L1的子宫内膜癌细胞侵袭迁移能力均减弱。结论：本研究证明了TFCP21L1是子宫内膜癌的促癌因子。TFCP2L1的高表达可能与子宫内膜癌预后不良相关。敲除TFCP2L1可以抑制子宫内膜癌的侵袭和转移。     

Establishment of a Non-Invasive Semi-Quantitative Bioluminescent Imaging Method for Monitoring of an Orthotopic Esophageal Cancer Mouse Model

Orthotopic models of various types of tumors are widely used in anti-tumor therapeutic experiments in preclinical studies. However, there are few ways to appropriately monitor therapeutic effect in orthotopic tumor models, especially for tumors invisible from the outside. In this study we aimed to establish a non-invasive semi-quantitative bioluminescent imaging method of monitoring an orthotopic esophageal cancer mouse model. We confirmed that the TE8 esophageal cancer cell line implanted orthotopically into the abdominal esophagus of nu/nu mice (n = 5) developed not only a main tumor at the implanted site, but also local lymph node metastases and peritoneal disseminations within 6 weeks after inoculation. We established a TE8 cell line that stably expressed the firefly luciferase gene (TE8-Luc). We showed that TE8-Luc cells implanted subcutaneously into nu/nu mice (n = 5) grew over time until 5 weeks after inoculation. Tumor volume was strongly correlated with luminescent intensity emitted from the tumor, which was quantified using the IVIS imaging system. We then showed that TE8-Luc cells implanted orthotopically into the mouse abdominal esophagus (n = 8) also formed a tumor and that the luminescent intensity of such a tumor, as detected by IVIS, increased over time until 7 weeks after inoculation and was therefore likely to reflect tumor progression. We therefore propose that this orthotopic esophageal cancer model, monitored using the non-invasive semi-quantitative IVIS imaging system, will be useful for in vivo therapeutic experiments against esophageal cancer. This experimental setting is expected to contribute to the development of novel therapeutic technologies for esophageal cancer in preclinical studies.     

Progesterone inhibits epithelial-to-mesenchymal transition in endometrial cancer

Background

Every year approximately 74,000 women die of endometrial cancer, mainly due to recurrent or metastatic disease. The presence of tumor infiltrating lymphocytes (TILs) as well as progesterone receptor (PR) positivity has been correlated with improved prognosis. This study describes two mechanisms by which progesterone inhibits metastatic spread of endometrial cancer: by stimulating T-cell infiltration and by inhibiting epithelial-to-mesenchymal cell transition (EMT).

Methodology and Principal Findings

Paraffin sections from patients with (n = 9) or without (n = 9) progressive endometrial cancer (recurrent or metastatic disease) were assessed for the presence of CD4+ (helper), CD8+ (cytotoxic) and Foxp3+ (regulatory) T-lymphocytes and PR expression. Progressive disease was observed to be associated with significant loss of TILs and loss of PR expression. Frozen tumor samples, used for genome-wide expression analysis, showed significant regulation of pathways involved in immunesurveillance, EMT and metastasis. For a number of genes, such as CXCL14, DKK1, DKK4, PEG10 and WIF1, quantitive RT-PCR was performed to verify up- or downregulation in progressive disease. To corroborate the role of progesterone in regulating invasion, Ishikawa(IK) endometrial cancer cell lines stably transfected with PRA (IKPRA), PRB(IKPRB) and PRA+PRB (IKPRAB) were cultured in presence/absence of progesterone (MPA) and used for genome-wide expression analysis, Boyden- and wound healing migration assays, and IHC for known EMT markers. IKPRB and IKPRAB cell lines showed MPA induced inhibition of migration and loss of the mesenchymal marker vimentin at the invasive front of the wound healing assay. Furthermore, pathway analysis of significantly MPA regulated genes showed significant down regulation of important pathways involved in EMT, immunesuppression and metastasis: such as IL6-, TGF-β and Wnt/β-catenin signaling.

Conclusion

Intact progesterone signaling in non-progressive endometrial cancer seems to be an important factor stimulating immunosurveilance and inhibiting transition from an epithelial to a more mesenchymal, more invasive phenotype.     

Growth inhibition by danazol in a human endometrial cancer cell line with estrogen-independent progesterone receptors

Since we recently found that danazol, an isoxazol derivative of ethinyltestosterone, has a growth-inhibitory effect on human endometrial cancer cells in primary culture, the effects of danazol on a human endometrial cancer cell line (IK-90 cells), which contains estrogen-independent progesterone receptors (PR), were investigated in the present study. The addition of danazol (1 nM-1 microM) in culture medium caused a decrease in the growth of IK-90 cells in a dose-dependent manner. Competitive binding studies showed that danazol effectively binds to PR in IK-90 cells, and the binding affinity for PR was estimated to be 6.0% of that of R5020. The addition of 1 microM danazol in culture medium resulted in a rapid and significant increase in nuclear PR with a concomitant decrease in cytoplasmic PR in the cells. These findings suggest that danazol has a growth-inhibitory effect on human endometrial adenocarcinoma cells directly through PR system in the cells.     

Inhibitory effects of danazol and medroxyprogesterone acetate on [3H]thymidine incorporation in human endometrial cancer cells

Effects of medroxyprogesterone acetate (MPA) and danazol (1 nM-10 microM) on cultured cancer cells from human endometrial adenocarcinomas obtained by hysterectomy were simultaneously investigated. Of twenty-four endometrial adenocarcinomas examined, five tumors were successfully maintained in primary cell culture. The addition of MPA as well as danazol in culture of cells from the five tumors resulted in a significant inhibition of [3H]thymidine incorporation in cancer cells from three tumors having progesterone receptors (PR). The minimum effective concentrations of MPA and danazol for the inhibition of [3H]thymidine incorporation were found to be 10 and 100 nM, respectively. The difference in effective concentration could be explained by a higher affinity of MPA to PR than that of danazol in cancer cells. On the other hand, neither danazol nor MPA affected [3H]thymidine incorporation in cultured cells from the remaining two tumors, in which PR was absent in one but present in the other. These findings, together with our previous findings that danazol inhibited the growth of a human endometrial cancer cell line with PR, suggest that a growth-inhibitory effect of danazol on human endometrial cancer cells is mediated through PR in the cells.     

褪黑素联合MPA抑制子宫内膜异常增生的作用及机制研究

摘要 目的：探索褪黑素联合MPA（醋酸甲羟孕酮）对子宫内膜异常增生细胞增殖活性的抑制作用及其机制。方法：取分化良好的子宫内膜增生细胞株Ishikawa和内膜癌细胞株ECC1于适宜条件培养,加入褪黑素、MPA单独或者联合处理48 h后,检测子宫内膜细胞株的增殖活性。收集褪黑素、MPA单独或者联合处理48 h后的子宫内膜增生细胞株Ishikawa细胞,提取细胞内的蛋白,检测人20α-羟基类固醇脱氢酶（AKR1C1）的表达情况。结果：褪黑素和MPA联合使用后对子宫内膜异常增生细胞的抑制作用明显高于褪黑素或MPA单独使用。褪黑素和MPA可抑制AKR1C1的表达,二者联合使用对AKR1C1的抑制高于两者单独使用。结论：褪黑素可提高子宫内膜异常增生细胞对MPA的敏感性,降低MPA的使用剂量,同时抑制AKR1C1的表达,使孕酮的代谢速率降低。褪黑素与MPA联合使用给子宫内膜增生和内膜癌的治疗策略带来新的思路。     

CXCR4/Akt信号通路对食管癌细胞侵袭和肿瘤转移的调控作用

多项研究发现CXCR4在各种类型的癌症中高表达,然而尚不清楚CXCR4在食管癌细胞生长和转移中的作用。本研究检测了CXCR4在食管癌组织和细胞系(TE-1)中的表达,并通过转染CXCR4-短发夹RNA(CXCR4-sh RNA)慢病毒来敲低TE-1细胞中CXCR4的表达。应用PI3K/AKT抑制剂LY294002(50μmol/L)处理TE-1细胞12 h来考察AKT信号在食管癌细胞生长和转移中的作用;应用蛋白质印迹分析检测AKT和Rho家族蛋白(RhoA,Rac-1和Cdc42)的表达;应用CCK-8实验检测细胞增殖;Transwell实验检测细胞侵袭;对雄性BALB/c-nu/nu裸鼠皮下注射转染CXCR4-shRNA的TE-1细胞建立肿瘤异种移植模型。研究显示,CXCR4在食管癌组织中的表达水平明显高于癌旁组织,并且与TNM分期和淋巴结转移有关。CXCR4在人食管鳞状细胞癌细胞系(TE-1)中的表达水平明显高于人正常食管上皮细胞系(human normal esophageal epithelial cell line,HEEC)。敲低CXCR4能抑制食管鳞状细胞癌细胞的增殖和侵袭能力,并抑制肿瘤异种移植裸鼠的肿瘤形成。敲低CXCR4抑制了AKT的磷酸化及RhoA、Rac-1和Cdc42的表达。此外,PI3K/AKT抑制剂LY294002处理显著降低了TE-1细胞中AKT的磷酸化,并降低了RhoA、Rac-1和Cdc42的表达。本研究表明,CXCR4在食管癌患者中上调,与不良预后相关。下调CXCR4的表达可在体内和体外抑制食管癌肿瘤的生长和转移。下调CXCR4可通过抑制AKT信号的激活来抑制Rho家族粘附/侵袭相关蛋白的表达,从而抑制肿瘤转移。     

Inhibition of AKT with the Orally Active Allosteric AKT Inhibitor, MK-2206, Sensitizes Endometrial Cancer Cells to Progestin

Progestin resistance is a major obstacle to treating early stage, well-differentiated endometrial cancer as well as recurrent endometrial cancer. The mechanism behind the suboptimal response to progestin is not well understood. The PTEN tumor suppressor gene is frequently mutated in type I endometrial cancers and this mutation results in hyperactivation of the PI3K/AKT pathway. We hypothesized that increased activation of AKT promotes an inadequate response to progestins in endometrial cancer cells. Ishikawa cells stably transfected with progesterone receptor B (PRB23 cells) were treated with the AKT inhibitor, MK-2206, which effectively decreased levels of p(Ser473)-AKT in a dose-dependent (10 nM to 1 uM) and time-dependent manner (0.5 h to 24 h). MK-2206 inhibited levels of p(Thr308)-AKT and a downstream target, p(Thr246)-PRAS40, but did not change levels of p(Thr202/Tyr204)ERK or p(Thr13/Tyr185)SAPK/JNK, demonstrating specificity of MK-2206 for AKT. Additionally, MK-2206 treatment of PRB23 cells resulted in a significant increase in levels of progesterone receptor B (PRB) protein. Microarray analysis of PRB23 cells identified PDK4 as the most highly upregulated gene among 70 upregulated genes in response to R5020. Inhibition of AKT further upregulated progestin-mediated expression of PDK4 but did not affect another progestin-responsive gene, SGK1. Treatment of PRB23 cells with R5020 and MK-2206 independently decreased viability of cells while the combination of R5020 and MK-2206 caused the greatest decrease in cell viability. Furthermore, mice with xenografted tumors treated with MK-2206 alone or with progesterone alone exhibited modest reductions in their tumor volume. The largest decrease in tumor size was observed in the mice treated with both MK-2206 and progesterone; these tumors exhibited the least proliferation (Ki67) and the most apoptosis (cleaved caspase-3) of all the treatment groups. In summary, inhibition of AKT stabilizes the Progesterone Receptor B and augments progesterone response in endometrial cancer cells that have hyperactivated AKT.     

Induction of nonspecific killer cells by delayed-type hypersensitivity against soluble protein antigens in murine peritoneal cavities

Summary We induced nonspecific killer cells in the local site of delayed-type hypersensitivity against keyhole limpet hemocyanin or ovalbumin. Delayed-type hypersensitivity was induced in the peritoneal cavities of mice, and peritoneal exudate cells (PEC) were collected. These PEC were found to have killer activity toward SP2 and YAC-1 cells (target cells susceptible to natural killer cells) by 4-h ⁵¹Cr-release assays. The induction of killer activity in PEC was observed in parallel with the eliciting of delayed-type hypersensitivity in the peritoneal cavity, in which the killer activity was maximum 24–48 h after the antigen challenge, but was not induced in nu/nu mice and was induced in an antigen-specific way. These killer cells did not adhere to nylon wool and had Thy1 and asialo-GM1 antigens on their surfaces. Their precursor cells were also asialo-GM1-positive. These findings indicate that the killer cells probably belong to the NK cell lineage. Results of tumor challenge experiments showed that these killer cells had an antitumor effect in vivo as well as in vitro.     

Tumor-suppressive effects of CDK8 in endometrial cancer cells

CDK8 is either amplified or mutated in a variety of human cancers, and CDK8 functions as an oncoprotein in melanoma and colorectal cancers. Previously, we reported that loss or reduction of CDK8 results in aberrant fat accumulation in Drosophila and mammals, suggesting that CDK8 plays an important role in inhibiting lipogenesis. Epidemiological studies have identified obesity and overweight as the major risk factors of endometrial cancer, thus we examined whether CDK8 regulates endometrial cancer cell growth by using several endometrial cancer cell lines, including KLE, which express low levels of CDK8, as well as AN3 CA and HEC-1A cells, which have high levels of endogenous CDK8. We observed that ectopic expression of CDK8 in KLE cells inhibited cell proliferation and potently blocked tumor growth in an in vivo mouse model. In addition, gain of CDK8 in KLE cells blocked cell migration and invasion in transwell, wound healing and persistence of migratory directionality assays. Conversely, we observed the opposite effects in all of the aforementioned assays when CDK8 was depleted in AN3 CA cells. Similar to AN3 CA cells, depletion of CDK8 in HEC-1A cells strongly enhanced cell migration in transwell assays, while overexpression of CDK8 in HEC-1A cells blocked cell migration. Furthermore, gene profiling of KLE cells overexpressing CDK8 revealed genes whose protein products are involved in lipid metabolism, cell cycle and cell movement pathways. Finally, depletion of CDK8 increased the expression of lipogenic genes in endometrial cancer cells. Taken together, these results show a reverse correlation between CDK8 levels and several key features of the endometrial cancer cells, including cell proliferation, migration and invasion as well as tumor formation in vivo. Therefore, in contrast to the oncogenic effects of CDK8 in melanoma and colorectal cancers, our results suggest that CDK8 plays a tumor-suppressive role in endometrial cancers.     

Multi-photon Imaging of Tumor Cell Invasion in an Orthotopic Mouse Model of Oral Squamous Cell Carcinoma

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient management strategies. Orthotopic mouse models of oral cancer have been developed to facilitate the study of factors that impact invasion and serve as model system for evaluating anti-tumor therapeutics. In these systems, visualization of disseminated tumor cells within oral cavity tissues has typically been conducted by either conventional histology or with in vivo bioluminescent methods. A primary drawback of these techniques is the inherent inability to accurately visualize and quantify early tumor cell invasion arising from the primary site in three dimensions. Here we describe a protocol that combines an established model for squamous cell carcinoma of the tongue (SCOT) with two-photon imaging to allow multi-vectorial visualization of lingual tumor spread. The OSC-19 head and neck tumor cell line was stably engineered to express the F-actin binding peptide LifeAct fused to the mCherry fluorescent protein (LifeAct-mCherry). Fox1^nu/nu mice injected with these cells reliably form tumors that allow the tongue to be visualized by ex-vivo application of two-photon microscopy. This technique allows for the orthotopic visualization of the tumor mass and locally invading cells in excised tongues without disruption of the regional tumor microenvironment. In addition, this system allows for the quantification of tumor cell invasion by calculating distances that invaded cells move from the primary tumor site. Overall this procedure provides an enhanced model system for analyzing factors that contribute to SCOT invasion and therapeutic treatments tailored to prevent local invasion and distant metastatic spread. This method also has the potential to be ultimately combined with other imaging modalities in an in vivo setting.     

食管癌细胞诱导肥大细胞迁移的小鼠模型

目的建立小鼠肥大细胞（mast cell,MC）迁移模型,探讨化疗药物三氧化二砷对人食管癌EC109细胞株生长的杀伤机理。方法利用肥大细胞的特征性蛋白酶抗体及其免疫荧光标记MC和PI标记EC109细胞内DNA;以流式细胞术分析小鼠腹腔液中肥大细胞各亚型的百分率及肿瘤细胞周期变化;使用激光扫描共聚焦显微镜显示肥大细胞内分泌颗粒的分布。并通过组织化学方法,观察各种诱导处理后小鼠肠组织肥大细胞由肠道向腹腔移动的变化。结果①根据流式细胞仪点图分布分析,将小鼠肥大细胞分为：类胰蛋白酶阳性、类糜蛋白酶阴性（MC T）;类糜蛋白酶阳性、类胰蛋白酶阴性（MC C）和类胰蛋白酶阳性、类糜蛋白酶阳性（MC TC）三种亚型,且T型MC明显多余TC型和C型（P〈0.05）;以共聚焦显微镜显示三种亚型的MC均含有丰富的分泌颗粒并分布于细胞膜内侧,为其出芽突起形成储备的状态。②经组织切片观察到诱导处理后小鼠肠组织MC由肠道向腹腔移动,且胰酶对MC的诱导作用大于食管癌细胞和As2O3。③经诱导迁移入腹腔的MC可能与癌细胞周期由S期向G2/M期跨越相关;As2O3能延迟食管癌细胞的G0/G1期,阻碍细胞向S期跨越,从而抑制食管癌细胞的生长。结论食管癌细胞移入小鼠腹腔,主要诱导T型MC参与免疫反应。在生物机体内环境（这里指MC影响）的条件下,As2O3对肿瘤细胞生长的作用主要表现为促使癌细胞周期的G0/G1期向S期跨越延迟,或G2/M期进入细胞分裂的延迟。     

Transforming growth factor-beta1 produced by ovarian cancer cell line HRA stimulates attachment and invasion through an up-regulation of plasminogen activator inhibitor type-1 in human peritoneal mesothelial cells

The processes of ovarian cancer dissemination are characterized by altered local proteolysis, cellular proliferation, cell attachment, and invasion, suggesting that the urokinase-type plasminogen activator (uPA) and its specific inhibitor (plasminogen activator inhibitor type-1 (PAI-1)) could be involved in the pathogenesis of peritoneal dissemination. We showed previously that expression of uPA and PAI-1 in the human ovarian cancer cell line HRA can be down-regulated by exogenous bikunin (bik), a Kunitz-type protease inhibitor, via suppression of transforming growth factor-beta1 (TGF-beta1) up-regulation and that overexpression of the bik gene can specifically suppress the in vivo growth and peritoneal dissemination of HRA cells in an animal model. We hypothesize that the plasminogen activator system in mesothelial cells can be modulated by HRA cells. To test this hypothesis, we used complementary techniques in mesothelial cells to determine whether uPA and PAI-1 expression are altered by exposure to culture media conditioned by HRA cells. Here we show the following: 1) that expression of PAI-1, but not uPA, was markedly induced by culture media conditioned by wild-type HRA cells but not by bik transfected clones; 2) that by antibody neutralization the effect appeared to be mediated by HRA cell-derived TGF-beta1; 3) that exogenous TGF-beta1 specifically enhanced PAI-1 up-regulation at the mRNA and protein level in mesothelial cells in a time- and concentration-dependent manner, mainly through MAPK-dependent activation mechanism; and 4) that mesothelial cell-derived PAI-1 may promote tumor invasion possibly by enhancing cell-cell interaction. This represents a novel pathway by which tumor cells can regulate the plasminogen activator system-dependent cellular responses in mesothelial cells that may contribute to formation of peritoneal dissemination of ovarian cancer.     

Anandamide inhibits adhesion and migration of breast cancer cells

The endocannabinoid system regulates cell proliferation in human breast cancer cells. We reasoned that stimulation of cannabinoid CB1 receptors could induce a non-invasive phenotype in breast metastatic cells. In a model of metastatic spreading in vivo, the metabolically stable anandamide analogue, 2-methyl-2'-F-anandamide (Met-F-AEA), significantly reduced the number and dimension of metastatic nodes, this effect being antagonized by the selective CB1 antagonist SR141716A. In MDA-MB-231 cells, a highly invasive human breast cancer cell line, and in TSA-E1 cells, a murine breast cancer cell line, Met-F-AEA inhibited adhesion and migration on type IV collagen in vitro without modifying integrin expression: both these effects were antagonized by SR141716A. In order to understand the molecular mechanism involved in these processes, we analyzed the phosphorylation of FAK and Src, two tyrosine kinases involved in migration and adhesion. In Met-F-AEA-treated cells, we observed a decreased tyrosine phosphorylation of both FAK and Src, this effect being attenuated by SR141716A. We propose that CB1 receptor agonists inhibit tumor cell invasion and metastasis by modulating FAK phosphorylation, and that CB1 receptor activation might represent a novel therapeutic strategy to slow down the growth of breast carcinoma and to inhibit its metastatic diffusion in vivo.     

Oxytocin increases invasive properties of endometrial cancer cells through phosphatidylinositol 3-kinase/AKT-dependent up-regulation of cyclooxygenase-1, -2, and X-linked inhibitor of apoptosis protein

Traditionally, oxytocin (OT) is well known to play a crucial role in the regulation of cyclic changes in the uterus, implantation of the embryo, and parturition. Recently, an additional role for OT has been identified in several types of cancer cells in which OT acts as a growth regulator. In endometrial cancer cells, OT is known to efficiently inhibit cellular proliferation. In the present study, we show that OT increases invasiveness of human endometrial carcinoma (HEC) cells, which are otherwise resistant to the growth-inhibiting effects of OT. Using pharmacological inhibitors, invasion assay, RNA interference, and immunofluorescence, we found that OT enhances the invasive properties of HEC cells through up-regulation of X-linked inhibitor of apoptosis protein (XIAP), matrix-metalloproteinase 2 (MMP2), and matrix-metalloproteinase 14 (MMP14). In addition, we show that OT-mediated invasion is both cyclooxygenase 1 (PTGS1) and cyclooxygenase-2 (PTGS2) dependent via the phosphatidylinositol 3-kinase/AKT (PIK3/AKT) pathway. PTGS2 knockdown by shRNA resulted in XIAP down-regulation. We also show that OT receptor is overexpressed in grade I to III endometrial cancer. Taken together, our results describe for the first time a novel role for OT in endometrial cancer cell invasion.