title: IER3 is a crucial mediator of TAp73β-induced apoptosis in cervical cancer and confers etoposide sensitivity.
abstract: Infection with high-risk human papillomaviruses (HPVs) causes cervical cancer. E6 oncoprotein, an HPV gene product, inactivates the major gatekeeper p53. In contrast, its isoform, TAp73β, has become increasingly important, as it is resistant to E6. However, the intracellular signaling mechanisms that account for TAp73β tumor suppressor activity in cervix are poorly understood. Here, we identified that IER3 is a novel target gene of TAp73β. In particular, TAp73β exclusively transactivated IER3 in cervical cancer cells, whereas p53 and TAp63 failed to do. IER3 efficiently induced apoptosis, and its knockdown promoted survival of HeLa cells. In addition, TAp73β-induced cell death, but not p53-induced cell death, was inhibited upon IER3 silencing. Moreover, etoposide, a DNA-damaging chemotherapeutics, upregulated TAp73β and IER3 in a c-Abl tyrosine kinase-dependent manner, and the etoposide chemosensitivity of HeLa cells was largely determined by TAp73β-induced IER3. Of interest, cervical carcinomas from patients express no observable levels of two proteins. Thus, our findings suggest that IER3 is a putative tumor suppressor in the cervix, and the c-Ab1/p73β/IER3 axis is a novel and crucial signaling pathway that confers etoposide chemosensitivity. Therefore, TAp73β and IER3 induction would be a valuable checkpoint for successful therapeutic intervention of cervical carcinoma patients.
authors: Department of Pharmacy, CHA University, Seongnam, 463-836, Korea.
authors: Hanyong
authors: H
authors: Jin
authors: Department of Obstetrics and Gynecology, Asan Medical Center, University of Ulsan College of Medicine.
authors: Dae-Shik
authors: DS
authors: Suh
authors: Department of Biochemistry, Chosun University School of Medicine, Gwangju 501-759, Korea.
authors: Tae-Hyoung
authors: TH
authors: Kim
authors: Department of Life Science, Chung-Ang University, Seoul, 156-756, Korea.
authors: Ji-Hyun
authors: JH
authors: Yeom
authors: Department of Life Science, Chung-Ang University, Seoul, 156-756, Korea.
authors: Kangseok
authors: K
authors: Lee
authors: School of Pharmacy, Chung-Ang University, Seoul, 156-756, Korea.
authors: Jeehyeon
authors: J
authors: Bae
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D005047:Etoposide / Q000494:pharmacology*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; D004268:DNA-Binding Proteins; C099815:IER3 protein, human; D008565:Membrane Proteins; D009687:Nuclear Proteins; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D005047:Etoposide