Background: Endometrial cancer (EC) is the most common malignancy of the female genital tract in developed countries. The majority of cases could be divided into two different subtypes. Type I oestrogen-dependent tumours are mostly associated with hyperestrogenism. Tumours with this type usually sustain the expression of oestrogen (ERs) and progesterone (PRs) receptors as found in normal endometrium and therefore generally have a good prognosis. In contrast, type II oestrogen-independent tumours are less common, however more aggressive and lethal¹. While oestrogen is believed to be a major promoter of tumour growth in the initial stages of EC, little is known of its role in the progression to malignant and metastatic disease. In this study, we reconstructed different phenotypes of EC in a three-dimensional (3D) cell culture system to interrogate the molecular basis underpinning oestrogen-relative modulations during endometrial tumorigenesis.

Methods: Two human endometrial adenocarcinoma cell lines, Ishikawa (type I-oestrogen-dependent) and KLE (type II-oestrogen-independent) were studied. First, an in vitro 3D monotypic culture system was established by culturing endometrial epithelial cells on top of a reconstituted basement membrane (rBM). Subsequently, cell morphology, cell polarity and quantification of cell proliferation and cell death in these 3D structures were analyzed by immunofluorescence/confocal microscopy. Expression profiles of ERs and PRs in these two cell lines were further characterized through RT-PCR and immunoblot analysis. 2D monolayer cultures served as controls.

Results: Our preliminary data showed that the well-differentiated Ishikawa cells and the poorly-differentiated KLE cells manifested distinguished phenotypes that mimic the parental tumours in vivo. The two cell lines exhibited differential expression patterns of ERs and PRs as well as strikingly distinctive hormonal responses when cultured in 3D compared to in 2D. Detailed analysis is still under investigation.

Conclusion: Our in vitro 3D rBM cultures well recapitulate the native tissue organisation and cellular functions of endometrial epithelia in tumours, which provide a more physiologically relevant model system for studying oestrogenic roles in endometrial neoplastic evolution, and potentially translate experimental results into patient cares.

Acknowledgement: This work was supported by the University of Queensland and NHMRC. Chao Lin is a recipient of UQ postgraduate scholarship.