Oncogenic ERG Represses PI3K Signaling through Downregulation of IRS2.

Publication Type	Academic Article
Authors	Mao N, Gao D, Hu W, Gadal S, Hieronymus H, Wang S, Lee Y, Sullivan P, Zhang Z, Choi D, Rosen N, Sawyers C, Gopalan A, Chen Y, Carver B
Journal	Cancer Res
Volume	80
Issue	7
Pagination	1428-1437
Date Published	02/03/2020
ISSN	1538-7445
Keywords	Insulin Receptor Substrate Proteins, Oncogene Proteins, Prostatic Neoplasms, Transcriptional Regulator ERG
Abstract	Genomic rearrangements leading to the aberrant expression of ERG are the most common early events in prostate cancer and are significantly enriched for the concomitant loss of PTEN. Genetically engineered mouse models reveal that ERG overexpression alone is not sufficient to induce tumorigenesis, but combined loss of PTEN results in an aggressive invasive phenotype. Here, we show that oncogenic ERG repressed PI3K signaling through direct transcriptional suppression of IRS2, leading to reduced RTK levels and activity. In accordance with this finding, ERG-positive human prostate cancers had a repressed AKT gene signature and transcriptional downregulation of IRS2. Although overexpression of IRS2 activated PI3K signaling, promoting cell migration in a PI3K-dependent manner, this did not fully recapitulate the phenotype seen with loss of PTEN as PI3K signaling is not as robust as observed in the setting of loss of PTEN. Importantly, deletions of the PTEN locus, which promotes active PI3K signaling, were among the most significant copy-number alterations that co-occurred with ERG genomic rearrangements. This work provides insight on how initiating oncogenic events may directly influence the selection of secondary concomitant alterations to promote oncogenic signaling during tumor evolution. SIGNIFICANCE: This work provides insight on how initiating oncogenic events may directly influence the selection of secondary concomitant alterations to promote tumorigenesis.
DOI	10.1158/0008-5472.CAN-19-1394
PubMed ID	32015092
PubMed Central ID	PMC7127960