743 Midkine and pleiotrophin are expressed in keloids

Abstract

Midkine (MDK) is a 15.5kDa heparin-binding growth factor induced by retinoids and inhibited by corticosteroids. It is closely related in structure to another low molecular weight protein, Pleiotrophin (PTN, 18.9kDa). Both MDK and PTN are involved in many important biological pathways including embryogenesis, tumorigenesis, and wound healing. They bind to a number of different receptors, including Protein-Tyrosine Phosphatase, Receptor-Type Zeta-1 (PTZPRZ1), which is known to play a key role in regulating cell growth, differentiation and transformation. MDK has been reported to stimulate collagen production (both Type I and Type III) and glycosaminoglycan synthesis in primary dermal fibroblasts. However, the roles of MDK, PTN and PTPRZ1 in the development of keloids have been largely unexplored. To further investigate whether MDK, PTN and PTPRZ1 play a significant role in keloid formation we have studied their expression in keloid and normal whole tissue. Results from both whole transcriptome sequencing and real-time PCR indicate that MDK, PTN and PTPRZ1 are upregulated in keloid tissue. Western blots have further identified their expression in keloid tissue. Our results suggest that MDK, PTN and PTPRZ1 could play an important role in the pathogenesis of keloids.