MMP-Directed Synthesis of Invasive Breast Cancer Blockers

Institution: Scripps Research Institute
Investigator(s): Vito Quaranta, M.D. -
Award Cycle: 2002 (Cycle VIII) Grant #: 8IB-0037 Award: $135,298
Award Type: IDEA
Research Priorities
Detection, Prognosis and Treatment>Innovative Treatment Modalities: search for a cure

Initial Award Abstract (2002)
Extracellular matrix metalloproteinases (MMP) are key proteins secreted by cancer cells that allow invasion of surrounding tissue. Considerable effort has been directed at inhibiting MMPs, particularly MMP-2, stromelysin-1 (MMP-3) and MT1-MMP, with the aim of interfering with cancer invasion. However, this approach has been hampered by the lack of specificity of available MMP inhibitors towards other members of the MMP family that are involved in normal physiological processes. A lack of specificity is the underlying reason for unwanted side-effects in human trials of current generation MMP inhibitors. New methods for developing highly specific MMP blockers may circumvent this problem and provide novel lead compounds for breast cancer invasion blockers.

We hypothesize that MMPs themselves can be interrogated to direct the synthesis of their own highly specific inhibitors, by using the newly developed approach of in situ "click chemistry"- The feasibility of this approach is strengthened by the recent discovery, via in situ "click chemistry", of the best inhibitor thus far for the enzyme acetylcholinesterase (an important nerve junction enzyme involved in regulating transmission of nerve impulses).

Using BCRP funding, we plan to: (1) generate "triazole" small-molecule derivatives as MMP inhibitors by incubating azide and acetylene building blocks with MMP, followed by mass spectrometry screening, (2) test these newly generated molecules for their ability to selectively inhibit specific MMPs, and (3) determine whether these lead compounds interfere with cellular invasion assays.

We anticipate that this novel in situ "click chemistry" approach will generate useful MMP inhibitor drug candidates. This will open new avenues for evaluating drugs that specifically inhibit breast cancer invasion with minimal unwanted side effects.

Final Report (2003)
Note: The PI, Dr. Vito Quaranta, relocated from Scripps to Vanderbilt University in June 2003. The original grant application from the PI was reduced to one year of funding to allow the research group to test the concept.

Invasion and metastasis are life-threatening properties of breast cancer (BC) cells. Recently, it has become clear that invasion largely depends upon the ability of BC cells to migrate into the surrounding tissue. BC cell migration is highly correlated with the presence of Matrix Metallo-Proteinases (MMP), enzymes that digest structural elements of tissue, such as collagen, creating passages for BC cells. Clinical use of available MMP inhibitors in cancer patients caused unbearable side effects, due to their lack of selectivity and interference with normal processes. To produce highly selective inhibitors, we proposed structure-based, computer-aided design of small molecule MMP inhibitors, and the novel method of “click chemistry”, in which assembly of inhibitors is directed by the MMP molecule itself.

Using CBCRP funding, we chose MMP-13 as our preferred “target” MMP to initiate this project. We produced a library of compounds from building blocks ("appended azide and alkyne fragments") that lend themselves to the “click chemistry” approach. We tested about 50 of these compounds and found that six inhibited the action of MMP-13, an enzyme implicated in BC invasion. We performed these studies using a Western blot approach. The novel compounds were tested by their ability to inhibit purified MMP-13 cleavage of a substrate, and the validation of activity was measured vs. Batimastat (BB94) and Prinomastat (AG3340). These six anti-MMP-13 compounds are important “leads” that, through iteration, can be refined and produce more active and selective molecules. We had planned to study and develop inhibitors for MMP-2, but technical issues prevented us from purifying sufficient amounts of this MMP for “click chemistry” and testing.

Our future direction is to enlarge the MMP-13 interacting chemical library, refine compounds that inhibit MMP-13. In addition, we plan to begin studying the related enzyme, MMP-2, our original “target” that is also highly associated with BC invasion. We will then perform the “click chemistry” approach using the “building blocks” of these refined inhibitor compounds, which will hopefully result in novel molecules with highest selectivity.