The International Journal of Biochemistry & Cell Biology 78 (2016) 194–205 Contents lists available at ScienceDirect The International Journal of Biochemistry & Cell Biology jo u r n al homep ag e: www.elsevier.com/locate/biocel Increased expression of platelet-derived growth factor associated protein-1 is associated with PDGF-B mediated glioma progression Vinay Kumar Sharma a , Anand Singh b , Sandeep Kumar Srivastava c , Vignesh Kumar d , Nilesh Laxman Gardi e , Aasma Nalwa c , Amit Kumar Dinda c , Parthaprasad Chattopadhyay b , Savita Yadav a,∗ a Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India b Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India c Department of Pathology, All India Institute of Medical Sciences, New Delhi 110029, India d Proteomics and Structural Biology Unit, Institute of genomics and Integrative Biology, New Delhi 110025, India e Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Mumbai, India a r t i c l e i n f o Article history: Received 6 February 2016 Received in revised form 16 July 2016 Accepted 18 July 2016 Available online 19 July 2016 Keywords: PDGF PDAP-1 Apoptosis Glioma Signaling Interaction a b s t r a c t The current treatment therapies available for malignant gliomas are inadequate. There is an urgent need to develop more effective therapies by characterizing the molecular pathogenesis of the disease. Over expression of platelet-derived growth factor (PDGF) ligands and receptors have been reported in malignant gliomas. Platelet-derived growth factor associated protein-1 (PDAP-1) is reported to modu- late the mitogenic activity of PDGF ligands, but to date, there is no information concerning its role in PDGF-mediated glioma cell proliferation. This study aimed to characterize the role of PDAP-1 in PDGF- mediated glioma proliferation. The expression of PDAP-1 was observed to be significantly increased (p< 0.05) in grade IV glioma tissue and cell lines compared to grade III. siRNA-mediated knockdown of PDAP-1 reduced the expression of PDGF-B and its downstream genes (Akt1/Protein kinase B (PKB) and phosphoinositide-dependent kinase-1 (PDK1) by up to 50%. In PDAP-1 knockdown glioma cells, more than a twofold reduction was also observed in the level of phosphorylated Akt. Interestingly, knockdown of PDAP-1 in combination with PDGF-B antibody inhibited glioma cell proliferation through activation of Caspase 3/7 and 9. We also demonstrate that PDAP-1 co-localizes with PDGF-B in the cytoplasm of glioma cells, and an interaction between both of the proteins was established. Collectively, these findings suggest that the expression of PDAP-1 is associated with disease malignancy, and its inhibition reduced the proliferation of malignant glioma cells through down-regulation of PDGF-B/Akt/PDK1 signaling. Thus, this study establishes PDAP-1 as an effecter of PDGF signaling in glioma cells and suggests that it could also be a promising therapeutic target. © 2016 Elsevier Ltd. All rights reserved. Abbreviations: GBM, glioblastoma multiforme; PDGF, platelet-derived growth factor; PDAP-1, platelet-derived growth factor associated protein-1; PDK1, 3- phosphoinositide-dependent protein kinase 1; WHO, world Health Organization; TCGA, the cancer genome atlas; PI, propidium iodide; ECL, enhanced chemilumi- nescence; IHC, immunohistochemistry; MMP, mitochondrial membrane potential; siRNA, small interfering RNA; FACS, fluorescence activated cell sorter; VEGF, vascular endothelial growth factor; HRP, horseradish peroxidase; DAB, 3,3 ′ - diaminobenzidine. ∗ Corresponding author. E-mail address: savita11@gmail.com (S. Yadav). 1. Introduction Despite recent advancements made by intensive efforts, the cure rate in malignant gliomas is still poor (Nagasawa et al., 2012). The high rate of recurrence and very low survival rate for these patients (Desjardins et al., 2016; Lemée et al., 2015; Stupp et al., 2009) reflect an urgent need for a better understanding of the disease. Glioblastoma multiforme (GBM, WHO grade IV), which exhibits the highest mortality rate among all grades, is almost incurable (Codrici et al., 2016). The biology of GBM tumors at both the cellu- lar and molecular level is not fully understood, which limits clinical improvements. Growth factors tend to play crucial roles in human malignancies, including GBM (Liu et al., 2011; Stupp et al., 2009; Cao et al., 2008). Major efforts in current cancer research are focused on http://dx.doi.org/10.1016/j.biocel.2016.07.016 1357-2725/© 2016 Elsevier Ltd. All rights reserved.