Identification and Characterization of a Selective Inhibitor of the PIM-1 Kinase

<p>The PIM-1 kinase is a serine/threonine kinase that has been implicated in the development of many human cancers, including leukemias, lymphomas, and prostate cancer. We have endeavored to identify and characterize a selective inhibitor of the PIM- 1 kinase. Such an inhibitor would have utility as a laboratory tool for the study of PIM-1 kinase function and as a template for the design of molecular therapeutics for diseases in which PIM-1 kinase activity is dysregulated.</p> <p>Using phage display techniques we identified the peptide, HGVKKRPHNPYG, as a probable pseudosubstrate of the PIM-1 kinase with inhibitory activity in the low micromolar range in <em>in vitro</em> kinase assays. However, the peptide lacked sufficient potency for our objectives; hence we employed a second approach - the computational design of a novel PIM-1 kinase antagonist.</p> <p>We created a homology model of the PIM-1 kinase that was subsequently determined to be structurally similar to a recently published crystal structure of the PIM-1 kinase. Docking studies using the PIM-1 kinase model demonstrated that the AFFINITY module of Insightll, under the parameters employed, was unable to accurately predict the potency of known PIM-1 kinase inhibitors. Consequently, we utilized comparative molecular field analysis, which resulted in a strong correlation of predicted IC₅₀vs. experimental IC₅₀ values for known flavonoid inhibitors of the PIM-1 kinase. Thus we have created the first predictive model that may be used for the rational design of small molecule inhibitors of the PIM-1 kinase.</p> <p>We have also performed an extensive screen of small molecules with structures similar to known kinase inhibitors and identified quercetagetin as a potent inhibitor of the PIM-1 kinase, with an<em> in vitro</em> IC₅₀ of 0.34 pM. Lineweaver-burk analyses of the reaction kinetics demonstrated that quercetagetin is an ATP competitive inhibitor the PIM-1 kinase. We have also determined that quercetagetin is selective for the PIM-1 kinase over many other kinases and that quercetagetin successfully inhibits PIM-1 kinase activity in mammalian cells. Therefore quercetagetin may be an effective tool for the laboratory study of the PIM-1 kinase, and may serve as a template for the design of molecular therapeutics directed against the PIM-1 kinase.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Microbiology

Year

2005

Author dc:creator

• Holder, Sheldon Levon

Contributors dc:contributor

• Michael B. Lilly
• Carlos Casiano
• Penelope Duerken-Hughes
• Mark Johnson
• Jonathan Neidigh
• Lawrence Sowers

• Microbiology
• Protein Kinases; Proto-Oncogene Proteins c-pim-1 -- antagonists and inhibitors; Neoplasms -- genetics.

Statement dc:rights

• This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Language dc:language

English

Repository record dc:identifier

https://scholarsrepository.llu.edu/etd/597

OAI identifier oai:identifier

oai:scholarsrepository.llu.edu:etd-1750