Identification and characterization of a small molecule inhibitor of IMP-1 that decreases expression of IMP-1 target mRNAs and inhibits proliferation of IMP-1 positive cancer cells

RNA-binding proteins control a variety of biological processes ranging from messenger RNA splicing to transport and translation. These post-transcriptional events are critical for proper cell function. One emerging class of proteins functions in several of these capacities. The VICKZ family of RNA-binding proteins is involved in translation control, mRNA localization and mRNA stability. I have studied the Insulin-like Growth Factor-2 mRNA-Binding Protein 1 (IGF2BP1/IMP-1/CRD-BP). IMP-1 exhibits an oncofetal pattern of expression, where it is expressed in embryonic development and its expression is repressed shortly after birth. However, the IMP-1 gene is reactivated in many different human cancers. Overexpression of IMP-1 leads to increased levels of proteins that promote tumor growth, metastasis, and resistance to anticancer drugs and is associated with a poor prognosis. IMP-1 enhances proliferation and migration of cancer cells by binding to and stabilizing mRNAs important in cancer, such as c-Myc. Although the role of c-Myc in cancer has been well established, it has remained an elusive therapeutic target because of its role as a transcription factor in non-neoplastic proliferating cells. Given its oncofetal pattern of expression, targeting IMP-1 presents a novel approach to targeting c-Myc. To identify new chemical entities with therapeutic potential in IMP-1 positive cancer, we carried out a pilot screen using an in vitro fluorescence anisotropy microplate assay (FAMA) and found that this approach was robust and appropriate for high throughput screening. We then carried out a high throughput screen of approximately 150,000 small molecules. Reported here is BTYNB, the first small molecule inhibitor of IMP-1, BTYNB decreases levels of IMP-1 target mRNAs, inhibits proliferation of IMP-1 positive cancer cells, and functions through the unique mechanism of decreasing oncogene mRNA stability. We believe that BTYNB not only can be developed as a potential therapeutic agent, but also serves as a useful molecular tool, with which we can probe the actions of IMP-1 in cancer cells. In addition to identifying and characterizing the first small molecule inhibitor of IMP-1, we were also interested in identifying novel molecular targets of IMP-1. Using in silico analysis of publicly available microarrays where IMP-1 was knocked down, we identified a panel of candidate target genes. Using qRTPCR and Western blot analysis, we then confirmed whether or not the mRNAs of candidate genes were decreased with IMP-1 knockdown and identified Protein Kinase C a (PKCa) as a new molecular target of IMP-1. Overall, this work has led to the identification and characterization of the first small molecule inhibitor of IMP-1 and has demonstrated that despite the fact that studies of the role of IMP-1 in cancer are rapidly expanding, there still remain novel molecular targets, such as PKCa, which may play critical roles in IMP-1 action in cancer cells.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Molecular & Integrative Physi

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2016

Author dc:creator

• Mahapatra, Lily

Contributors dc:contributor

• Shapiro, David J.
• Kemper, Jongsook Kim
• Bolton, Eric
• Anakk, Sayeepriyadarshini

• IM-1
• Small Molecule Inhibitor

Statement dc:rights

• Copyright 2016 Lily Mahapatra

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/90460

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/90460