Abstract
BackgroundPleiotrophin (PTN) is a heparin-binding growth factor with significant role(s) in tumour growth and angiogenesis. Although implication of endogenous PTN has been studied in several in vivo models of tumour angiogenesis, its role in physiological angiogenesis has not been addressed. In the present work, we studied expression and functional significance of endogenous PTN during angiogenesis in the chicken embryo chorioallantoic membrane (CAM).MethodsUsing molecular, cellular and biochemical assays, we studied the expression pattern of PTN in CAM and human endothelial cells and its possible interaction with nucleolin (NCL). CAM cells were transfected with a pCDNA3.1 vector, empty (PC) or containing full length cDNA for PTN in antisense orientation (AS-PTN). Angiogenesis was estimated by measuring total vessel length. In vitro, human endothelial cells migration was studied by using a transwell assay, and down-regulation of NCL was performed by using a proper siRNA.ResultsEndogenous PTN mRNA and protein levels, as well as protein levels of its receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ) were maximal at early stages, when CAM angiogenesis is active. Application of AS-PTN onto CAM at days of active angiogenesis was not toxic to the tissue and led to dose-dependent decreased expression of endogenous PTN, ERK1/2 activity and angiogenesis. Interestingly, endogenous PTN was also immunolocalized at the endothelial cell nucleus, possibly through interaction with NCL, a protein that has a significant role in the nuclear translocation of many proteins. Down-regulation of NCL by siRNA in human endothelial cells significantly decreased nuclear PTN, verifying this hypothesis. Moreover, it led to abolishment of PTN-induced endothelial cell migration, suggesting, for the first time, that PTN-NCL interaction has a functional significance.ConclusionsExpression of endogenous PTN correlates with and seems to be involved in angiogenesis of the chicken embryo CAM. Our data suggest that NCL may have a role, increasing the number of growth factors whose angiogenic/tumorigenic activities are mediated by NCL.
Highlights
Pleiotrophin (PTN) is a heparin-binding growth factor with significant role(s) in tumour growth and angiogenesis
Besides a role in tumour angiogenesis, we have previously shown that exogenously administered PTN induces angiogenesis in several in vitro models of angiogenesis [3,4,5] and in vivo, in the chicken embryo chorioallantoic membrane (CAM) [3]
PTN is expressed by chicken embryo CAM cells and interacts with RPTPb/ζ Initially, we investigated whether PTN is physiologically expressed by CAM cells
Summary
Pleiotrophin (PTN) is a heparin-binding growth factor with significant role(s) in tumour growth and angiogenesis. The best characterized functions of PTN up to date are those concerning its role(s) in the nervous system, as well as its involvement in tumour growth The latter was initially supported by the fact that PTN has been detected in various human carcinomas, such as meningiomas, neuroblastomas, diffuse astrocytomas, glioblastomas, melanomas, multiple myeloma, prostate cancer, cancer of the pancreas, breast cancer, small cell lung cancer, malignant tumor of the testis, solid paediatric tumours, uterine cervical cancer and leiomyomas, while it has been detected in serum of patients with breast, colon, pancreas, lung cancers and multiple myeloma. The role of PTN has been studied in several in vivo models of tumour growth, there are no in vivo studies on the role of endogenous PTN in physiological angiogenesis
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
