Pharmacological inhibition of 17β-hydroxysteroid dehydrogenase inhibits endometrial cancer growth in an orthotopic xenograft mouse model. Pharmacological inhibition of 17β-hydroxysteroid dehydrogenase inhibits endometrial cancer growth in an orthotopic xenograft mouse model

Experimental design: Endometrial tumours were induced orthotopically (in one uterine horn) in 8-week-old female athymic nude mice (Crl:NU(NCr)-Foxn1nu), using an Ishikawa-derived cell line (clones Ishi-M3-HSDA, described in Konings et al 2018). This cell line maintains the characteristics of the parental line (i.e., gives rise to well differentiated-estrogen sensitive adenocarcinomas) and further bears the luciferase gene for in vivo measurement of tumour growth by bioluminescence and expresses the enzyme 17β-hydroxysteroid dehydrogenase (HSD17B1). After tumour engraftment (approximately two weeks), baseline was defined, mice were ovariectomised (to remove the natural source of estrogens) and estrone was supplemented via subcutaneous pellets at a dose of 0.02 g/day. Mice were further assigned to one arm, receiving only estrone, and a second arm, receiving estrone plus the HSD17B1 inhibitor FP4643 at a dose of 25mg/Kg. At humane endpoint (approximately 10 weeks), mice were sacrificed, primary tumours were excised and snap-frozen. Tumours were divided on their largest diameter plane and slices for RNA isolation were prepared from such largest surface area of the primary tumours. Histology on mirror slices confirmed the present of tumour tissue and the absence of necrosis, inflammation and mouse endometrium.