Dosage-dependent regulation of VAV2 expression by steroidogenic factor-1 drives adrenocortical carcinoma cell invasion

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with a dismal prognosis. Genomic studies have enabled progress in our understanding of the molecular bases of ACC, but factors that influence its prognosis are lacking. Amplification of the gene encoding the transcription factor steroidogenic factor-1 (SF-1; also known as NR5A1) is one of the genetic alterations common in ACC. We identified a transcriptional regulatory mechanism involving increased abundance of VAV2, a guanine nucleotide exchange factor for small GTPases that control the cytoskeleton, driven by increased expression of the gene encoding SF-1 in ACC. Manipulating SF-1 and VAV2 abundance in cultured ACC cells revealed that VAV2 was a critical factor for SF-1-induced cytoskeletal remodeling and invasion in culture (Matrigel) and in vivo (chicken chorioallantoic membrane) models. Analysis of ACC patient cohorts indicated that greater VAV2 abundance robustly correlated with poor prognosis in ACC patients. Because VAV2 is a druggable target, our findings suggest that blocking VAV2 may be a new therapeutic approach to inhibit metastatic progression in ACC patients.