PDF file - 672K, Figure S1. High eIF3b mRNA expression is associated with human bladder cancer. Figure S2. eIF3b antibody specificity Figure S3. High eIF3b mRNA expression is associated with aggressive phenotypes in human prostate cancer Figure S4. Time course of eIF3b depletion. Figure S5. Depletion of eIF3b inhibits prostate cancer cell growth. Figure S6. Depletion of eIF3b affects the cell cycle in cancer cells. Figure S7. Depletion of eIF3b does not induce apoptosis in UMUC3 cells. Figure S8. Depletion of eIF3b decreases cell spreading and adhesion through integrin alpha5 in PC3 cells. Figure S9. Depletion of eIF3c inhibits cell growth, protein synthesis and disrupts actin cytoskeleton organization and focal adhesion.
ARTICLE ABSTRACT
Purpose: Discovery transcriptomic analyses suggest eukaryotic initiation factor 3b (eIF3b) is elevated in human bladder and prostate cancer, yet its role as a prognostic factor or its requirement in the maintenance or progression of human cancer is not established. Here, we determine the therapeutic potential of eIF3b by examining the clinical relevance of its expression in human cancer tissues and its role in experimental tumor models.Experimental Design: We examined mRNA expression of eIF3b in bladder (N = 317) and prostate (N = 566) tissue samples and protein expression by immunohistochemistry in 143 bladder tumor samples as a function of clinicopathologic features. The impact of eIF3b depletion by siRNA in human cancer lines was evaluated in regard to in vitro cell growth, cell cycle, migration, in vivo subcutaneous tumor growth, and lung colonization.Results: eIF3b mRNA expression correlated to tumor grade, stage, and survival in human bladder and prostate cancer. eIF3b protein expression stratified survival in human bladder cancer. eIF3b depletion reduced in vitro cancer cell growth; inhibited G1–S cell-cycle transition by changing protein but not RNA expression of cyclin A, E, Rb, and p27Kip1; inhibited migration; and disrupted actin cytoskeleton and focal adhesions. These changes were associated with decreased protein expression of integrin α5. Integrin α5 depletion phenocopied effects observed with eIF3b. eIF3b-depleted bladder cancer cells formed fewer subcutaneous tumors that grew more slowly and had reduced lung colonization.Conclusion: eIF3b expression relates to human bladder and prostate cancer prognosis, is required for tumor growth, and thus a candidate therapeutic target. Clin Cancer Res; 19(11); 2850–60. ©2013 AACR.
