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Doral Cavallo-Medved, Ph.D.
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RESEARCH INTERESTS:
Proteases are involved in normal biological and developmental processes such as cell growth and death, blood clotting, angiogenesis and immune defense as well as in the pathogenicity of diseases including cancer, arthritis, HIV, and Alzheimer’s. Interactions among proteases are supported by their localization into cellular compartments. For example, compartmentalization of proteases adjacent to or on the cell surface facilitates pericellular proteolysis. Proteases of at least three classes (serine, cysteine and metallo) have been shown to localize in cell surface lipid rafts termed caveolae. Furthermore, these proteases have all been shown to play a role in cancer progression and metastasis and angiogenesis. Caveolae are found in many different cell types and are involved in transcellular transport of molecules and in cellular signaling cascades. Our main research interests are to investigate the mechanisms by which proteases are transported to caveolae, regulated within these microdomains and the effects of these caveolae-associated proteases on tumor cell invasion and on tumor-stromal interactions. Our scientific approach is to develop in vitro and in vivo cell-based, 3D co-culture systems and to apply molecular imaging techniques to evaluate these caveolar protease-mediated processes in both cancer and non-cancer models.
Current Research Projects:
1. Caveolae-Associated Proteases and Inflammatory Breast Cancer (IBC)
IBC is the most aggressive and lethal form of breast cancer. It is clinically different from other forms of breast cancer in that it mimics an acute inflammation of the breast. In addition, the highly angiogenic phenotype and the propensity of IBC to invade dermal lymphatics and infiltrate lymph nodes characterize IBC as a highly metastatic disease. Tumor cells within the lymphatic emboli are highly adherent to one another. E-cadherin, a cell surface adhesion protein, has been found to be highly expressed in IBC. Although the molecular changes that dictate invasion in IBC remain to be elucidated, in IBC cell lines and human samples, overexpression of caveolin-1 (cav-1) and -2 (cav-2), major structural proteins of specialized lipid rafts known as caveolae, is observed. Recent studies have classified cav-1 and -2 as biomarkers for the basal-like phenotype in the breast carcinoma subgroup that includes IBC. Our previous studies show that down-regulation of cav-1 in colon cancer cells alters the expression, localization and activity of proteases and decreases extracellular matrix (ECM) degradation and invasion by these cells. Thus, the association of cell surface proteases to caveolae and the overexpression of cav-1 in basal-like breast carcinomas such as IBC suggest that cav-1 mediates proteolytic events that contribute to the metastatic phenotype of IBC. Furthermore, caveolin-1 has been shown to interact indirectly with E-cadherin in ovarian carcinoma cells such that expression of both proteins stabilizes adherens junctions, Thus, our working hypotheses are that: 1) intercellular adhesion of IBC cells within lymphatic emboli is mediated by E-cadherin as regulated by proteolytic pathways associated with caveolae and their structural protein caveolin-1; and 2) invasion and metastasis of IBC cells (i.e., migration out of lymphatic emboli) is enhanced by upregulation of proteases in the IBC cells as a result of interactions with leukocytes resident in the lymphatics.
2. Caveolae-Associated Proteases and Trophoblast Invasion
During normal placental development, trophoblasts invade into the uterus, and then surround and remodel the spiral arteries. This endovascular invasion involves the interactions between the trophoblast and the endothelium and is crucial to support the blood flow to the fetus. The mechanism of trophoblast interaction and remodeling of the endometrium remain unclear. Cav-1 is expressed in human villous cytotrophoblasts of the placenta and this expression is reduced during cytotrophoblast differentiation. We have shown that during differentiation of endothelial cells, proteases are distributed to caveolae and ECM collagen IV degradation products colocalize with cav-1. Thus, establishing an in vitro 3D co-culture system that mimics the microenvironment in which trophoblasts interact with endothelial cells is relevant to unraveling the mechanisms of trophoblast invasion and spiral artery remodeling during placental development. Our current research aims are to: 1) establish an in vitro co-culture system of trophoblast cells with EC that recapitulates invasion of trophoblasts into spiral arteries, and 2) use the in vitro co-culture system to determine the effects of modulating cav-1 expression on proteolysis, and invasion of trophoblast cells grown with EC.
Selected Recent Publications:
- Cavallo-Medved, D., Dosescu, J., Linbaugh, B.E., Sameni, M., and Sloane, B.F. (2003). Mutant K-ras regulates cathepsin B localization on the surface of human colorectal carcinoma cells. Neoplasia 5: 507-519.
- Cavallo-Medved, D. and Sloane, B.F. (2003) Cell-surface cathepsin B: understanding its functional significance. Curr. Top. Dev. Biol. 54: 313-341.
- Cavallo-Medved, D., Mai, X., Dosescu, J., Sameni, M., and Sloane, B.F. (2005). Caveolin-1 mediates the expression and localization of cathepsin B, pro-urokinase plasminogen activator and their cell-surface receptors in human colorectal carcinoma cells. J. Cell Sci. 118: 1493-1503.
- Cavallo-Medved, D. and Sloane, B. F. (2006) Proteases and inhibitors. In D. Ganten and K. Ruckpaul (eds) Encyclopedic Reference of Genomics and Proteomics in Molecular Medicine. Springer International, Germany.
- Mostafa, M., Cavallo-Medved, D., and Sloane, B.F. (2008) Interactions between human monocytic cells and human inflammatory breast cancer cells modulate expression of E-cadherin, caveolin-1 and a caveolae-associated protease, cathepsin B. (In Press Biological Chemistry Journal).
