Olaparib (AZD2281) is a single digit nanomolar inhibitor of both PARP-1 and PARP-2 that shows standalone activity against BRCA1-deficient breast cancer cell lines. Olaparib is applied to SW620 cell lysates, and identified the IC50 for PARP-1 inhibition to be around 6 nM and the total ablation of PARP-1 activity to be at concentrations of 30−100 nM.
Animals bearing SW620 xenografted tumors are treated with Olaparib (10 mg/kg, p.o.) in combination with Temozolomide (TMZ) (50 mg/kg, p.o.) once daily for 5 consecutive days, after which the tumors are left to grow out[1]. Olaparib increases vascular perfusion in Calu-6 tumors established in a DWC model. Administration of olaparib(50 mg/kg, p.o.) as a single agent (top panel) or in combination with radiation (bottom panel) results in an increase in fluorescence intensity in the Calu-6 tumors.
This assay determined the ability of Olaparib to inhibit PARP-1 enzyme activity. PARP-2 activity inhibition is measured by using a variation of the PARP-1 assay in which PARP-2 protein (recombinant) is bound down by a PARP-2 specific antibody in a 96-well white-walled plate. PARP-2 activity is measured following 3H-NAD+ DNA additions. After washing, scintillant is added to measure 3H-incorporated ribosylations. For tankyrase-1, an AlphaScreen assay is developed in which HIS-tagged recombinant TANK-1 protein is incubated with biotinylated NAD+ in a 384-well ProxiPlate assay. Alpha beads are added to bind the HIS and biotin tags to create a proximity signal, whereas the inhibition of TANK-1 activity is directly proportional to the loss of this signal. All experiments are repeated at least three times.
MCE has not independently confirmed the accuracy of these methods. They are for reference only.
