A66 (Synonyms: A 66; A-66)

Kinase experiment:

IC50 values are evaluated using the PI3K (human) HTRF Assay. p85α/p110δ is obtained from Invitrogen. All other isoforms are produced in-house by co-expressing full-length human p85α with the indicated human full-length catalytic subunit containing a histidine tag at the N-terminus to allow purification. The PI3Ks are titrated and used at a concentration between their EC65-EC80 values. PI3K activity in immunoprecipitates is assayed using an antibody to the N-SH2 (N-Src homology 2) domain of p85α. Assays for other lipid kinases and protein kinases are performed by the National Centre for Protein Kinase Profiling and Invitrogen Drug Discovery Services[1].

Animal experiment:

Mice[1] Age-matched specific pathogen-free Rag1-/- or NIH-III mice are subcutaneously inoculated on the right flank with 5×106 U87MG, SK-OV-3 or HCT-116 cells in PBS. Tumour diameter as measured by electronic calipers is used to calculate tumour volume (mm3) based on the formula (L×w2)×π/6 (where L=longest tumour diameter and w=perpendicular diameter). A66 is administered in 20% 2-hydroxypropyl-β-cyclodextrin in water, whereas BEZ-235 is administered in 10% ethanol. Control mice are administered the A66 dosing vehicle alone. The drugs are dosed by intraperitoneal injection as the free base equivalent at a dosing volume of 10 mL/kg of body weight. For tumour pharmacodynamic studies, mice are administered a single dose of A66 or the control vehicle when tumors reached approximately 8-9 mm in diameter. Animals are killed 1 or 6 h after dosing and the tumors are removed, biopulverized and assayed for protein concentration. For antitumor efficacy studies, dosing began when tumors are well established, averaging approximately 7 mm in diameter. Doses are administered once daily (QD) or twice daily (BID) with injections separated by a minimum of approximately 8 h. Different dosing schedules are used for the three xenograft models depending on the rate of tumor growth and the body weight tolerance of control mice. Animals are dosed daily for 21 days or twice daily for 16 days (SK-OV-3), daily for 14 days (U87MG) and daily for 7 days (HCT-116). Animals are monitored daily for any signs of emerging toxicity and body weight is recorded. Mice are killed if they developed moderate signs of toxicity or if body weight loss exceeded 20% of starting weight. TGI (tumour growth inhibition) is calculated on the final day of dosing by determining the relative tumour size of drug-treated mice as a percentage of the average relative tumour size of control mice. The statistical significance of TGI values is determined by one-way ANOVA with Bonferroni multiple comparison analysis using GraphPad Prism 5.02.

References:

[1]. Jamieson S, et al. A drug targeting only p110α can block phosphoinositide 3-kinase signalling and tumour growth in certain cell types. Biochem J, 2011, 438(1), 53-62.
[2]. Sun M, et al. Cancer-derived mutations in the regulatory subunit p85alpha of phosphoinositide 3-kinase function through the catalytic subunit p110alpha. Proc Natl Acad Sci U S A, 2010, 107(35), 15547-15552.