Cell experiment:

Islets are placed into 96-well plates and subjected to a 8-point dose of KU-32 in either low (5 mM) or high (17.5 mM) glucose in DMEM : F12 media and incubated overnight at 37℃ and 5% CO2. Twenty-four hours later, alamarBlue is added directly to each well to achieve a final concentration of 10% alamarBlue. Readings on a microplate reader are collected 4, 24, and 48 hours later[1].

Animal experiment:

Male and female lepr mice are used. At 10 weeks of age, animals are given once per week intraperitoneal injection of 5% Captisol or 20 mg/kg KU-32 in 5% Captisol. At termination of the study, blood from each animal is collected[1].

KU-32 is a novel, novobiocin-based Hsp90 inhibitor that can protect against neuronal cell death.

Treating human islets with KU-32 for 24 hours shows no toxicity. With a minimum of 2-day exposure, KU-32 improves cellular viability by blocking apoptosis. Functionally, isolated human islets release more glucose-stimulated insulin when preincubate in KU-32[1]. KU-32 protects against glucose-induced death of embryonic DRG (dorsal root ganglia) neurons cultured for 3 days in vitro[2].

Diabetic BKS-db/db mice, a model for type 2 diabetes, administered KU-32 for 10 weeks do not show any significant changes in blood glucose and insulin levels, despite having greater insulin staining/beta cell in the pancreas compared to untreated BKS db/db mice[1].

[1]. Farmer K, et al. KU-32, a novel drug for diabetic neuropathy, is safe for human islets and improves in vitro insulin secretion and viability. Exp Diabetes Res. 2012;2012:671673. [2]. Urban MJ, et al. Inhibiting heat-shock protein 90 reverses sensory hypoalgesia in diabetic mice. ASN Neuro. 2010 Aug 11;2(4):e00040.