Effects of Type 1 Insulin-Like Growth Factor Receptor Silencing in a Human Adrenocortical Cell Line

Type 1 insulin-like growth factor receptor (IGF-1R) is overexpressed in a variety of human cancers, including adrenocortical tumors. The aim of the work was to investigate the effects of IGF-1R downregulation in a human adrenocortical cell line by small interfering RNA (siRNA). The human adrenocortical tumor cell line NCI H295R was transfected with 2 specific IGF1R siRNAs (#1 and #2) and compared with untreated cells and a negative control siRNA. IGF1R expression was determined by quantitative reverse-transcription PCR (qRTPCR) and Western blot. The effects of IGF-1R downregulation on cell proliferation and apoptosis were assessed. IGF-1R levels were significantly decreased in cells treated with IGF1R siRNA #1 or #2. Relative expression of IGF1R mRNA decreased approximately 50 % and Western blot analysis revealed a 30 % of reduction in IGF-1R protein. Downregulation of this gene resulted in 40 % reduction in cell growth in vitro and 45 % increase in apoptosis using siRNA #2. These findings demonstrate that decreasing IGF1R mRNA and protein expression in NCI H295R cells can partially inhibit adrenal tumor cell growth in vitro. Targeting IGF-1R is a promising therapy for pediatric malignant adrenocortical tumor and can still be an option for adult adrenocortical cancer based on personalized genomic tumor profiling.