Subtractive proteomic approach to the endometrial carcinoma invasion front

Tumor invasion defines the transition between tissue-restricted carcinomas, related to good outcome as optimal surgery becomes possible, and metastatic tumors associated with poor prognosis and a dramatic decrease in survival. In endometrial cancer, myometrial infiltration represents a determinant parameter highly valuable in prognosis. To date, the identification of proteins involved in endometrial carcinoma invasion has been essentially conducted by immunohistochemical methods, without a global perception on the invasive front. Laser microdissection presents nowadays limitations to the profound spatiotemporal regulation from both the tumor and the surrounding stroma occurring at the invasive front. In this work, we attempted an alternative proteomic approach to characterize specific components of the tumor invasive front or its reactive stroma, by comparing the invasive area of an endometrial carcinoma with the noninvasive superficial tumor area and normal tissue from the same patients. This strategy led us to identify proteins involved in cellular morphology, assembly and movement, differentially expressed at the invasive front, as well as pathways like cell-to-cell signaling and interaction and a modulated response to oxidative stress as events related to endometrial carcinoma invasion. In conclusion, we could identify new players of myometrial infiltration by applying a subtractive proteomic approach to the endometrial carcinoma invasion front.

An orthotopic endometrial cancer mouse model demonstrates a role for RUNX1 in distant metastasis

Endometrial carcinoma is the most common malignancy of the female genital tract in industrialized countries. Metastasis is the major cause of endometrial cancer deaths. Therefore, there is a vital need for clinically relevant in vivo models allowing the elucidation of the molecular and cellular mechanisms underlying metastatic behavior. In this study, we describe an innovative experimental orthotopic model of human endometrial carcinoma. Implantation in the bifurcation of the uterine horns resulted in tumors integrated into the myometrial compartment, which can be used and further exploited for the study of in vivo angiogenesis, myometrial invasion, and the metastatic capacity of endometrial cancer cells. This orthotopic model also represents a suitable tool to analyze how tumorigenesis and distant metastasis of endometrial cancer might be influenced by gene alteration, by modulating its expression in the original cancer cell line. One of the candidate genes implicated in endometrial cancer is the transcription factor RUNX1. The over-expression of RUNX1 in the endometrial cancer cell line HEC1A and the transplantation of these cells to the uterus of nude mice were associated specifically with distant metastasis in the lung. RUNX1 plays a role in the establishment of metastases in endometrial cancer. Translated to the clinics, these models would be equivalent to an advanced undifferentiated carcinoma with node affectation (stage IIIC) and distant metastasis (stage IVB). These patients would be candidates for adjuvant therapy, not efficient until today, and therefore, our models are actually suitable for the design and evaluation of experimental therapies.

ERM/ETV5 up-regulation plays a role during myometrial infiltration through matrix metalloproteinase-2 activation in endometrial cancer

We have described recently the Ets family transcription factor, ERM/ETV5, specifically up-regulated in endometrioid endometrial carcinoma (EEC) and associated with myometrial infiltration. Ets family members have been correlated to tumor progression by up-regulating the expression of matrix-degrading proteases. In the present study, we investigated the possibility that in EEC, ERM/ETV5 may act by inducing the expression of genes involved in extracellular matrix remodeling. Unraveling the molecular events associated with the initiation of tumor invasion would represent an obvious improvement for EEC patients. The overexpression of ERM/ETV5 induced scattering in the endometrial cancer cell line Hec-1A, correlating to increased matrix metalloproteinase-2 (MMP-2) gelatinase activity. Both chromatin immunoprecipitation and reversion experiments with RNA interference and specific MMP-2 inhibitor showed a functional link between ERM/ETV5 overexpression and MMP-2 activation. The increased MMP-2 activity associated with overexpressed ERM/ETV5 in a mouse model conferred invasive capacity to endometrial tumors. Orthotopically implanted overexpressing ERM/ETV5 tumors presented a more aggressive and infiltrative pattern of myometrial invasion. Finally, the specific localization of ERM/ETV5 and MMP-2 at the invasive front of myometrial infiltrating human endometrial carcinomas further reinforced the hypothesis of a role for ERM/ETV5 in the early steps of endometrial dissemination. Taken together, these results lead us to propose that in EEC, ERM/ETV5 acts through MMP-2 gelatinolytic activity to confer invasive capabilities, associated with an initial switch to myometrial infiltration. They also postulate ERM/ETV5 as a valuable marker for patient stratification and a transcription pathway that should be evaluated for therapies specifically targeting the initial steps of EEC dissemination.

Molecular determinants of invasion in endometrial cancer

Endometrial carcinoma is the most common gynaecological malignancy in the western world and the most frequent among infiltrating tumours of the female genital tract. Despite the characterisation of molecular events associated with the development of endometrial carcinoma, those associated with the early steps of infiltration and invasion in endometrial cancer are less known. Deep myometrial invasion correlates with more undifferentiated tumours, lymph-vascular invasion, node affectation and decreased global survival. In this review we present an overview of the molecular pathology of myometrial infiltration that defines the initial steps of invasion in endometrial cancer. Down-regulation of E-cadherin as a main player of epithelial to mesenchymal transition, as well as modifications on other molecules involved in cell-cell contacts, render cells with a migratory phenotype. In addition, altered signalling pathways and transcription factors associate with myometrial invasion, histologic grade and metastasis.