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Modulation of gene expression and cell-cycle signaling pathways by the EGFR inhibitor gefitinib (Iressa) in rat urinary bladder cancer. Cancer Prev Res (Phila) 2012 Feb;5(2):248-59



Pubmed ID




Scopus ID

2-s2.0-84863237623   13 Citations


The epidermal growth factor receptor inhibitor Iressa has shown strong preventive efficacy in the N-butyl-N-(4-hydroxybutyl)-nitrosamine (OH-BBN) model of bladder cancer in the rat. To explore its antitumor mechanism, we implemented a systems biology approach to characterize gene expression and signaling pathways in rat urinary bladder cancers treated with Iressa. Eleven bladder tumors from control rats, seven tumors from rats treated with Iressa, and seven normal bladder epithelia were profiled by the Affymetrix Rat Exon 1.0 ST Arrays. We identified 713 downregulated and 641 upregulated genes in comparing bladder tumors versus normal bladder epithelia. In addition, 178 genes were downregulated and 96 genes were upregulated when comparing control tumors versus Iressa-treated tumors. Two coexpression modules that were significantly correlated with tumor status and treatment status were identified [r = 0.70, P = 2.80 × 10(-15) (bladder tumor vs. normal bladder epithelium) and r = 0.63, P = 2.00 × 10(-42) (Iressa-treated tumor vs. control tumor), respectively]. Both tumor module and treatment module were enriched for genes involved in cell-cycle processes. Twenty-four and twenty-one highly connected hub genes likely to be key drivers in cell cycle were identified in the tumor module and treatment module, respectively. Analysis of microRNA genes on the array chips showed that tumor module and treatment module were significantly associated with expression levels of let-7c (r = 0.54, P = 3.70 × 10(-8) and r = 0.73, P = 1.50 × 10(-65), respectively). These results suggest that let-7c downregulation and its regulated cell-cycle pathway may play an integral role in governing bladder tumor suppression or collaborative oncogenesis and that Iressa exhibits its preventive efficacy on bladder tumorigenesis by upregulating let-7 and inhibiting the cell cycle. Cell culture study confirmed that the increased expression of let-7c decreases Iressa-treated bladder tumor cell growth. The identified hub genes may also serve as pharmacodynamic or efficacy biomarkers in clinical trials of chemoprevention in human bladder cancer.

Author List

Lu Y, Liu P, Van den Bergh F, Zellmer V, James M, Wen W, Grubbs CJ, Lubet RA, You M


Pengyuan Liu PhD Adjunct Professor in the Physiology department at Medical College of Wisconsin
Ming You MD, PhD Associate Provost, Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Antineoplastic Agents
Biomarkers, Tumor
Blotting, Western
Cell Cycle
Cell Proliferation
ErbB Receptors
Gene Expression Profiling
Gene Expression Regulation, Neoplastic
Oligonucleotide Array Sequence Analysis
RNA, Messenger
Rats, Inbred F344
Real-Time Polymerase Chain Reaction
Signal Transduction
Urinary Bladder Neoplasms
jenkins-FCD Prod-484 8aa07fc50b7f6d102f3dda2f4c7056ff84294d1d