Faculty Type: Emeritus Faculty

Chemotherapy effectiveness is often limited by drug toxicity in healthy tissues, although methods that spare normal cells by delivering drugs specifically to tumors may help to overcome this constraint. We have identified a promising tumor-targeted drug delivery vehicle known as the IF7 peptide. Using in vitro assays, we found that the IF7 peptide bound to the protein annexin 1 (Anxa1), which is known from previous studies by others to be enriched on the surface of tumor vasculature in several tumor types. When we injected a fluorescently labeled IF7 peptide into mice with tumors, fluorescent signals appeared in the tumors within one minute of injection. By contrast the tumors showed no fluorescence when mice were pre-injected with anti-Anxa1 antibodies that inhibits IF7-Anxa1 binding, suggesting that the peptide targets tumor by homing to Anxa1.

Invasion of the trophoblast into the endometrium, an essential element of embryo implantation, resembles invasion of malignant tumors. At the initial phase of implantation, the trophoblast and the uterine epithelium establish their first contact via their respective apical cell membranes. We have identified new molecules, trophinin, tastin, and bystin that mediate cell adhesion between trophoblastic cells and endometrial epithelial cells at the respective apical cell membranes. Trophinin is an intrinsic membrane protein, and tastin and bystin are cytoplasmic proteins. All of these molecules are strongly expressed in cells involved in embryo implantation in humans. However, trophinin is not expressed in human endometrial epithelia throughout the hormonal cycle, except only those cells located close to the implanting blastocyst. Trophinin expression by endometrial epithelia is induced by human chorionic gonadotrophin (hCG) derived from the implanting embryo (Sugihara et al, 2008). While embryos invade maternal cells (Sugihara et al, 2007), maternal tissue accepts embryos. We asked what happens in the maternal epithelia when trophinin-mediated adhesion takes place, and found that trophinin-mediated cell adhesion triggers an apoptotic signal in maternal epithelial cells (Tamura et al, 2011).