HOTAIR in relation to epithelial-mesenchymal transition and cancer stem cells in molecular subtypes of endometrial cancer.

BACKGROUND: Endometrial cancer (EC) is a hormone-related disease, showing highly diverse features of ER/PR/HER2 status-based molecular subtypes. Long noncoding RNA (lncRNA) HOX antisense intergenic RNA (HOTAIR) has recently emerged as a key molecule in many cancers, triggering epithelial-mesenchymal transition (EMT)-mediated cancer stem cell (CSC) formation, but little is known about its significance in EC. Thus, we aimed to investigate the clinical significance of HOTAIR itself in different molecular subtypes of EC and possible links between HOTAIR, EMT and CSC-related markers. METHODS: The study group included 156 consecutive, stage I-IV EC patients treated between 2000 and 2010. ER, PR and HER2 protein expression were examined by immunohistochemistry (IHC) on tissue microarrays. RT-qPCR was used to analyze the expression levels of HOTAIR, EMT-related genes - SNAIL and SLUG - and the CSCs marker CD133. RESULTS: Molecular subtypes, defined as ER/PR+HER2+, ER/PR+HER2-, ER-PR-HER2+ and ER-PR-HER2-, occurred in 40.2%, 52.3%, 4.7% and 1.9% of cases, respectively. The expression of HOTAIR did not differ between the subtypes, but high HOTAIR expression correlated with shorter overall survival (p = 0.04) in the entire group. The expression levels of HOTAIR, SNAIL, SLUG and CD133 were similar in defined EC molecular subtypes. CONCLUSIONS: Our data do not confirm the role of HOTAIR in EMT-mediated CSC formation in EC. Neither does the diversity of EC molecular subtypes influence these processes. But HOTAIR expression could serve as an independent prognostic factor in EC. The clinical importance of the above discoveries requires further studies.

HER2-positive endometrial cancer subtype carries poor prognosis.

Endometrial cancer (EC) is a hormone-dependent, most frequent malignancy of the female genital tract, yet no molecular subtype classification based receptor status (estrogen receptor [ER], progesterone receptor [PR], human epidermal growth factor receptor 2 [HER2]) has been established so far. Assuming that molecular subtypes might differ fundamentally in EC, we analyzed expression levels of ER, PR, and HER2 with immunohistochemistry and aimed to determine clinical significance of four molecular subtypes: ER+/PR+/HER2+; ER+/PR+/HER2-, ER-/PR-/HER2+, and ER-/PR-/HER2-. The study included 400 formalin-fixed paraffin-embedded primary tumor EC samples which covered all stages of endometrial carcinoma, from IA to IVB. ER-/PR-/HER2+ subtype correlated with the poorest outcome, ER+/PR+/HER2- subtype was associated with the most favorable prognosis (p = 0.002). Molecular subtype division remained an independent prognostic factor in multivariate analysis, accompanying parameters such as diabetes, hypertension, stage, myometrial infiltration, and metastases, all of which yielded hazard ratios between 1.39 and 2.23. ER+/PR+/HER2+ and ER+/PR+/HER2- subtypes had low average TP53 and TOP2A expression levels when compared with ER-/PR-/HER2+ and ER-/PR-/HER2- (both p < 0.00001). Molecular subtypes in EC do show diversity in terms of prognosis, clinicopathological, and molecular characteristics. ER-/PR-/HER2+ subtype exhibit is exceptionally aggressive tumor characteristics. Subtype differentiation might aid prediction of treatment response in EC.