Intersectin 1 is required for neuroblastoma tumorigenesis.

Intersectin 1 (ITSN1) is a scaffold protein that regulates diverse cellular pathways, including endocytosis and several signal transduction pathways, including phosphatidylinositol 3-kinase, Class IIβ (PI3K-C2β). ITSN1's transforming potential in vitro suggests that this scaffold protein may be involved in human tumorigenesis. Herein, we demonstrate that ITSN1 is expressed in primary human neuroblastoma tumors and tumor cell lines and is necessary for their in vitro and in vivo tumorigenic properties. Silencing ITSN1 significantly inhibits the anchorage independent growth of tumor cells in vitro and tumor formation in xenograft assays independent of MYCN status. Overexpression of the ITSN1 target, PI3K-C2β, rescues the soft agar growth of ITSN1-silenced cells demonstrating the importance of the ITSN1-PI3K-C2β pathway in neuroblastoma tumorigenesis. These findings represent the first demonstration that the ITSN1-PI3K-C2β pathway has a requisite role in human cancer, specifically neuroblastomas.