SBIR-STTR Award

The primary objective is to discover and develop anti-cancer drugs that target the DNA methylation process. DNA methylation changes and abnormal epigenetic gene silencing correlate perfectly with the advancement of many types of cancer. An increased DNA methyltransferase activity during the progression of many cancers leads to the loss of expression of "tumor suppressor", DNA repair and cell- cell adhesion genes. The DNA methylation process is a validated target for drug intervention, because aberrantly methylated genes can be demethylated by specific drugs that reactivate genes and restore a healthy condition. We recently discovered over 50 small molecule inhibitors of Dnmt-1, the major DNA cytosine methyltransferase, using a high throughput screen with purified enzyme. In this Phase I proposal, two methods are described that utilize a unique and innovative cell-based assay. The cells have an epigenetically silenced gene encoding the green fluorescent protein (GFP). We aim to reactivate expression by interfering with the silencing mechanism. A `secondary screen' will be done with small molecules already identified as inhibitors of Dnmt-1. A `primary screen' will broaden the search to drugs that interfere anywhere in the silencing mechanism. Drugs that prove capable of stimulating re-expression of GFP will be applied to well characterized cancer cell model systems to provide further proof of concept before entering the compounds into small animal studies. PROPOSED COMMERCIAL APPLICATIONS: DNA methylation pathway inhibitors hold great promise for the treatment and reversal of many forms of cancer. We estimate that 5 million of the 8 million non-skin cancers cases in the US involve methylation abnormalities. Because the aims of this proposal are to develop novel anti-cancer compounds, human applications will not come to fruition for a several of years after this proposal is funded

There is now considerable evidence that DNA methylation, by silencing tumor suppressor and mis-match repair genes, has a major role in the causation and progression of cancer and is also involved in abnormal DNA methylation events following HIV (Human Immunodeficiency Virus) infection. In the past year, two primary mechanisms in epigenetic gene silencing, DNA methylation and chromatin remodeling have merged as an important new approach to cancer therapy and diagnostics. Unlike mutated genes, epigenetically silenced genes are intact and can be reactivated by drugs that target the methylation process. There is a great need for reversible, less toxic methylation inhibitors. The primary objective of this proposal is to develop lead compounds identified in a unique cell-based screen designed to identify inhibitors of the methylation process. The screening of two chemical diversity libraries totaling more than 50,000 compounds, conducted during the Phase I program, identified more than eight chemically distinct classes of methylation inhibitors. For the proposed Phase II work, we will undertake a comprehensive development program and pre-clinical evaluation of the most promising compound class(es). Lead candidates from this evaluation will be tested in animal tumor models and a cellular model of HIV infection. We will also evaluate the ability of our lead drug candidate(s) to reverse drug resistant properties of several important anticancer drugs in clinical use, including cisplatin in non-small cell lung cancer and colorectal cancer.

Thesaurus Terms:
DNA methylation, antineoplastic, drug discovery /isolation, drug screening /evaluation, inhibitor /antagonist AIDS related neoplasm /cancer, HIV infection, chemical registry /resource, cisplatin, combinatorial chemistry, drug resistance, neoplasm /cancer pharmacology, pharmacokinetics, toxicology 3T3 cell, laboratory mouse, microarray technology