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 50% of 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.
LNG resistant endometrial cancer cell lines (MFE296R and MFE319R) and cultures from three early stage endometrial cancer patients were developed. The behavioural profile of MFE296R and MFE319R were analysed using proliferation, adhesion, migration (wound healing and transwell) and invasion (spheroid) assays. LNG sensitive cell lines (MFE296S and MFE319S) were compared to LNGR cell lines (MFE296R and MFE319R). 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 MFE296R and MFE319R. mRNA expression of the top differentially expressed genes was measured using RT-qPCR in primary cultures.
LNG resistance did not affect proliferation or invasion in immortalised endometrial cancer cells, however significantly increased transwell migration in MFE319R cells (p = 0.03). LNG resistance led to a decrease in cellular adhesion in both MFE296R cells (p = 0.012) and MFE319R cells (p = 0.04) compared to LNG sensitive clones. mRNA expression of KLF4 and SATB2 was significantly amplified in MFE296R and MFE319R cells compared to their LNG sensitive clones. mRNA expression of KLF4 was significantly upregulated and mRNA expression of ER was significantly downregulated in LNG resistant primary cell lines compared to their LNG sensitive clones.
LNG resistant cells may be slightly more aggressive and therefore, have more oncogenic potential than their LNG sensitive counterparts. There were significant changes in the mRNA profile of LNG resistant cells compared to LNG sensitive cells, with relative expression of KLF4 and SATB2 significantly upregulated in resistant immortalised cell lines. This study presents promising preliminary results in biomarker discovery for guiding LNG-IUS treatment of early stage endometrial cancer.