Characterisation of Levonorgestrel-Resistant Endometrial Cancer Cells

BACKGROUND: Endometrial cancer (EC) is the most common gynaecologic malignancy in the developed world, and incidence is increasing in premenopausal women. The levonorgestrel intrauterine system (LNG-IUS) is gaining traction as an alternative treatment for hyperplasia and early-stage EC for women who are unable to undergo surgery. Thirty to 60% of the women do not respond to this treatment, making the unknown mechanisms of levonorgestrel (LNG) resistance a critical obstacle for the conservative management of EC. This study aimed to characterise LNG-IUS treatment resistance in early-stage endometrial cancer in cell-line models. METHODS: LNG-resistant endometrial cancer cell lines (MFE296(R) and MFE319(R)) and cultures from three early stage endometrial cancer patients were developed. The behavioural profile of MFE296(R) and MFE319(R) was analysed using proliferation, adhesion, migration (wound healing and transwell) and invasion (spheroid) assays. LNG-sensitive cell lines (MFE296(S) and MFE319(S)) were compared to LNG(R) cell lines (MFE296(R) and MFE319(R)). A literature search was conducted to identify possible candidate biomarkers of LNG resistance. RT-qPCR was used to analyse the mRNA expression of 17 candidate biomarkers in MFE296(R) and MFE319(R). mRNA expression of the top differentially expressed genes was measured using RT-qPCR in primary cultures. RESULTS: LNG resistance did not affect proliferation or invasion in immortalised endometrial cancer cells. Transwell migration was significantly increased in MFE319(R) cells (p=0.03). Cellular adhesion significantly decreased in both MFE296(R) cells (p=0.012) and MFE319(R) cells (p=0.04). mRNA expression of KLF4 and SATB2 was significantly amplified in MFE296(R) and MFE319(R) cells. mRNA expression of KLF4 was significantly upregulated LNG-resistant primary cell lines. CONCLUSION: LNG-resistant cells may have more oncogenic potential than their LNG-sensitive counterparts. Significant changes in the mRNA expression of KLF4 and SATB2 of LNG-resistant cells is a promising preliminary result in biomarker discovery for guiding LNG-IUS treatment of early stage endometrial cancer.