The Quigley Laboratory

Research

Identification of Molecules that Function in Human Tumor Metastasis and Angiogenesis for Possible Therapeutic Application 

My laboratory is conducting studies on the mechanism of human tumor metastasis using an in vivo model system that employs human tumor cells disseminating to specific organs in the developing chick embryo. A technique known as subtractive immunization is employed to generate in an unbiased manner unique antibodies directed against antigens on the surface of metastatic human tumor cells which are then tested for their ability to modulate metastatic spread. Tumor cell surface antigens that are functionally involved in metastasis are being identified by these methods. The quantitation of metastasis, using real time PCR with human specific primers, also has allowed for the in vivo selection and isolation of unique tumor cell variants from human fibrosarcomas and prostate and pancreatic carcinomas. Comparative analyses of the variants’ gene and protein expression levels are providing distinct information about metastasis-specific molecules.

Also under way in the laboratory is an investigation of a specific step in metastasis, namely, the process of intravasation, which is the entry of primary tumor cells into the vasculature and is likely a rate-limiting step in tumor dissemination. Two isogenic variants of a human fibrosarcoma cell line (HT-hi/diss and HT-lo/diss) have been recently isolated and shown to have a 100 fold differential in their respective ability to enter the vasculature in vivo. The cellular and molecular analysis of these two variants using array technology, proteomic approaches, and intravital microscopy has allowed us to identify specific contributory molecules that are functionally important in tumor cell/vascular interactions. 

Our laboratory is also examining the differential expression of specific proteolytic enzymes and how these enzymes may mediate angiogenesis and tumor cell migration and invasion. The experimental approach is to employ chemical-based assays to detect those enzymes which are distinctly activated in angiogenic tissue, or around invading tumor cells. We then isolate and purify the enzymes, obtain the cDNAs encoding them and generate specific mutant constructs, inhibitors or neutralizing antibodies to the enzymes, all of which are then tested in various in vivo model systems that manifest the angiogenic or invasive phenotype. This approach allows for the identification of specific proteolytic enzymes that are functionally involved in distinct physiological and pathological processes. Two enzyme families presently under study include the matrix metallo proteases (e.g. MMP-9, MMP-1) and the serine proteases, (e.g. uPA and plasmin).