Notch signaling activation suppresses v-src-induced transformation of neural cells by restoring TGF-β-mediated differentiation

Abstract

Background: We have been investigating how interruption of differentiation contributes to the oncogenic process and the possibility to reverse the transformed phenotype by restoring differentiation. In a previous report, we correlated the capacity of intracellular Notch (ICN) to suppress v-Src-mediated transformation of quail neuroretina (QNR/v-srcts) cells with the acquisition by these undifferentiated cells of glial differentiation markers. Methodology/Principal Findings: In this work, we have identified autocrine TGF-b3 signaling activation as a major effector of Notch-induced phenotypic changes, sufficient to induce transition in differentiation markers expression, suppress morphological transformation and significantly inhibit anchorage-independent growth. We also show that this signaling is constitutive of and contributes to ex-vivo autonomous QNR cell differentiation and that its down-regulation is essential to achieve v-Src-induced transformation. Conclusions/Significance: These results support the possibility that Notch signaling induces differentiation and suppresses transformation by a novel mechanism, involving secreted proteins. They also underline the importance of extracellular signals in controlling the balance between normal and transformed phenotypes. © 2010 Amarir et al.