The PDGF-PDGFR Signaling Pathway Regulates AKT Cell Survival and NF-kB anti-apoptotic effects in Retinoblastoma

Abstract

Purpose : Purpose: Vitreous seeding remains the greatest challenge in treatment of retinoblastoma (Rb). In part due to poor understanding of the interactions between Rb and vitreous microenvironment. Previously, we identified the PDGF-PDGFR signaling as a signaling pathway that sustains angiogenesis in both an autocrine and paracrine fashion. Here, we investigated how the PDGF-PDGFR signaling pathway regulates cell proliferation and cell survival in Rb.

Methods : Methods: We performed in vitro cell culture assays of Y79 Rb cells, considered the metastatic model of the disease. Cells were cultured in different conditions, which include stimulatory (recombinant human PDGF) and inhibitory (imatinib mesylate) conditions of the PDGF-PDGFR signaling pathway. Assessment of cell survival included measurement of members of the AKT signaling pathway and protein levels of the anti-apoptotic molecule BCL-2 by Western blot analyses. Nuclear translocation of the p65 subunit of NF-kB was measured by imaging flow cytometry using FlowSight^®.

Results : Results: Our results suggest that PDGF-PDGFR signaling regulates Rb cell survival through AKT. Additionally, we found a significant reduction in BCL-2, concomitant with an increase in caspase-3 activity. We also found a significant decrease in the nuclear translocation of the p65 subunit of NF-kB

Conclusions : Conclusions: The outcomes of this study reveal that PDGF-PDGFR signaling regulates cell survival in addition to the previously described sustainment of angiogenesis. We found PDGF-PDGFR signaling is involved in the activation of the AKT survival pathway. Inhibition of PDGF-PDFGR signaling decreases NF-kB nuclear translocation, ultimately resulting in increased susceptibility to apoptosis.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.