Bone-targeted Pyk2 inhibitor for prevention of bone fragility
Glucocorticoids (GC) in excess, either due to disease or administered as anti-inflammatory agents, are a leading cause of osteoporosis and bone fractures in the United States. Our earlier research identified activation of the kinase Pyk2 (a member of the family of the focal adhesion kinases FAK) as a new mechanism by which GC exert deleterious actions on bone cells. Pyk2 activation prolongs the lifetime of osteoclasts, increasing bone destruction; and it induces early apoptosis of osteoblasts and osteocytes, decreasing bone formation and increasing bone fragility. We also found that administration of a pharmacologic Pyk2 inhibitor prevents bone loss in a murine model of GC excess. However, systemic administration of this inhibitor induces adverse effects in other tissues and has some off-target effects on related kinases.
The goal of this project is to generate a novel bone-targeted (BT) Pyk2 inhibitor to attain kinase inhibition mainly in bone cells to assure specific, low-dose, non-toxic inhibition of Pyk2 without off-target effects.
The project seizes the complementary expertise of 3 investigators at UAMS: Dr. Teresita Bellido, Principal Investigator, Professor and Chair of Physiology and Cell Biology, College of Medicine (COM), a bone biologist and pathophysiologist with expertise in hormonal effects in bone cells and state-of-the-art models of GC skeletal actions. Dr. Hong-yu Li, Professor in the College of Pharmacy, a translational medicinal chemist and expert in the development of pharmacological kinase inhibitors and drug delivery technologies. Dr. Alexei Basnakian, Professor of Toxicology and Pharmacology, COM, expert-toxicologist and Director of the DNA Damage and Toxicology Core.
Aim 1 (Li team). Develop a BT-Pyk2 inhibitor by conjugating Pyk2 inhibitor PF562271 with a bisphosphonate with high affinity for bone tissue, but otherwise inactive. We have a well-established technology to link PF562271 to bisphosphonate. The cleavage of the conjugating linker in the bone tissue releases two drugs the Pyk2 inhibitor and the bisphosphonate.
Aim 2 (Bellido team). Compare the effectiveness of the BT-Pyk2 inhibitor (at 1x and 1/10x doses) and the parent Pyk2 inhibitor (at 1x dose) to prevent GC effects using in vitro and ex vivo models, and GC-induced bone disease in a mouse model of GC excess; and quantify kinase activity (Pyk2 and related FAK).
Aim 3 (Basnakian team). BT-Pyk2 inhibitor will be compared with the prototype by pharmacokinetics (PK) and multi-organ toxicity in mice. Plasma concentration/time data will be used to determine the PK profiles including: area under the curve to predict the total body exposure, volume of distribution, half-life, bioavailability, clearance rate, maximum plasma concentration (Cmax), and time to Cmax. Toxicity will be measured by 14 plasma markers of organ function, and structural organ toxicity will be assessed by quantitative TUNEL assay.
Two trainees will work in the project: Dr. Amy Sato, postdoctoral fellow from the Bellido laboratory, and Xiuqi Wang, graduate student from the Li laboratory.
Our transdisciplinary team is uniquely poised to develop and test the novel BT-Pyk2 inhibitor-bisphosphonate conjugate for GC-induced bone disease. Results of the study will be used as preliminary findings for an extramural proposal to fully develop the novel compound for the treatment of patients suffering from the devastating effects of GC excess.
- kinase inhibition
- bone fragility