PX-478 is a HIF-1α inhibitor with selectivity, oral activity, and blood-brain barrier permeability. PX-478 has antitumor activity and also protects pancreatic β-cell function in diabetes mellitus and is used in type 2 diabetes mellitus research.

MCF-7 cells (anoxia):25.1 µM, HT29 cells (normoxia):23.9 µM, MCF-7 cells (normoxia):20.0 µM, HT29 cells (anoxia):29.5 µM, DU-145 cells inhibit HIF1α:40-50 µM, PC3 cells (normoxia):11.1 µM, PC3 cells inhibit HIF-1α:20-25 µM, PC3 cells (anoxia):16.2 µM

METHODS: Tumor cells MCF-7, HT-29 and PC-3 were treated with PX-478 under normoxic or hypoxic conditions for 16 h, and then grown under normoxic conditions for another 56 h. Cell viability was detected by MTT assay.
RESULTS: PX-478 produced a smaller but significantly greater inhibition of cell growth under hypoxic conditions compared to normoxic conditions. the hypoxic/normoxic IC50 of MCF-7 cells was 25.1/20.0 µM, with a ratio of 1.25. the hypoxic/normoxic IC50 of HT-29 cells was 29.5/23.9 µM, with a ratio of 1.20, and that of PC-3 cells was 16.2/11.9 µM, with a ratio of 16.2/11.0 µM. IC50 for PC-3 cells was 16.2/11.1 µM with a ratio of 1.45. [1]
METHODS: Human prostate cancer cells PC3 and DU 145 were treated with PX-478 (10-40 µM) under normoxic conditions for 20 h. The expression levels of target proteins were detected by Western Blot.
RESULTS: Under normoxic conditions, the IC50 of PX-478 for HIF-1α inhibition in PC3 cells was 20-25 µM (ΔHIF:0.56±0.08), while the IC50 of HIF1α inhibition in DU 145 cells was 40-50 µM (ΔHIF:0.47±0.08). [2]

METHODS: To study the activity on metabolism in vivo, PX-478 (5 mg/kg) was administered by gavage to C57BL/6 mice on a high-fat diet (HFD) every two days for seven weeks.
RESULTS: PX-478 treatment effectively inhibited HFD-induced HIF1α activation in adipose tissue. Inhibition of HIF1α in adipocytes significantly improved metabolism. [3]
METHODS: In order to detect the anti-tumor activity in vivo, PX-478 (75-100 mg/kg) was intraperitoneally injected into scid mice carrying tumors OvCar-3, SHP-77, MCF-7, or PC-3 once a day for five days.
RESULTS: PX-478 showed antitumor activity against established human tumor xenografts. [4]

PX-478 is prepared as a 10 mM stock in distilled water and used immediately[1]. To determine the effect of PX-478 in combination with radiation, cells are treated with PX-478 for 24 hr under normoxic condition, irradiated and plated after 1 hr. Colonies are stained with crystal violet after 12 days and the colonies of >50 cells are counted. For combination treatments, net survival is calculated by correcting the toxicity of PX-478 alone. Enhancement factor (EF) is calculated by dividing the dose of radiation required to reduce plating efficiency to 10% when cells are treated with radiation alone by the dose of radiation required to reduce plating efficiency to 10% when cells are treated with PX-478 and radiation[1].