Cd26/Dipeptidyl Peptidase IV in Context: The Different Roles of a Multifunctional Ectoenzyme in Malignant Transformation

CD26, the T cell activation molecule, is a 110-kD glycoprotein that is also present on epithelial cells of various tissues, including the liver, kidney, and intestine. CD26 possesses a known dipeptidyl peptidase (DPP)IV activity in its extracellular domain 1. A paper by Wesley et al. in this issue indicates a possible role for CD26/DPPIV in suppressing malignant transformation of melanocytes to melanoma 2. The series of work by Houghton and colleagues, focusing on melanoma and melanocytes, has shown that loss of expression and its enzymatic activity of CD26/DPPIV occurs during malignant transformation of melanocytes into melanoma 3. The exact pathological role of its disappearance however, has been unclear. Wesley et al. now elegantly demonstrate that the inducible gene transduction of CD26 into melanoma cells reverses the malignant phenotype of the cells toward “benign” melanocyte-like phenotype, characterized...