STX140 is an estrogen sulfamate with anticancer activities. It inhibits steroid sulfatase with IC50 values of 39 and 0.5 nM in placental microsomes and MCF-7 cancer cells, respectively. STX140 also binds to carbonic anhydrase IX and II (Kis = 70 and 270 nM, respectively). It inhibits bovine brain tubulin assembly in a cell-free assay (IC50 = 2.2 μM) and tubule formation in human umbilical vein epithelial cells (HUVECs) when used at concentrations of 50 and 100 nM. STX140 inhibits proliferation of LNCaP, PC3, and MDA-MB-231 cancer cells, as well as wild-type A2780 cancer cells and adriamycin- and cisplatin-resistant A2780 cancer cells (IC50s = 530, 400, 618, 330, 870, and 380 nM, respectively). It reduces angiogenesis in a Matrigel™ plug assay in mice and tumor growth in MCF-7 and MDA-MB-231 mouse xenograft models when used at a dose of 20 mg/kg.
