title: EGFR-independent Elk1/CIP2A signalling mediates apoptotic effect of an erlotinib derivative TD52 in triple-negative breast cancer cells.
abstract: Cancerous inhibitor of protein phosphatase 2A (CIP2A) has emerged as a therapeutic determinant mediating the anti-cancer effects of several new agents. We investigated the efficacy and mechanism of TD52, an erlotinib derivative with minimal p-EGFR inhibition but significant CIP2A downregulation, in triple-negative breast cancer (TNBC) cells.
  
  
  
  TNBC lines were used for in vitro studies. Cell apoptosis was examined by flow cytometry and Western blot. Signal transduction pathways in cells were assessed by Western blot. In vivo efficacy of TD52 was tested in xenograft nude mice.
  
  
  
  We explored the CIP2A mRNA expression in a publically available database and found that higher levels of CIP2A mRNA is associated with worse recurrence-free survival in patients with TNBC. TD52-enhanced apoptosis accompanied with CIP2A downregulation and CIP2A overexpression protected cells from TD52-mediated apoptosis. The activity of protein phosphatase 2A (PP2A) was also increased in TD52-treated cells. TD52-induced apoptosis and p-Akt downregulation was attenuated by PP2A antagonist okadaic acid. Furthermore, TD52 indirectly downregulated CIP2A transcription via disturbing the binding of Elk1 to the CIP2A promoter. Importantly, TD52 showed anti-tumour activity in mice bearing TNBC xenograft tumours and downregulated CIP2A and p-Akt in these xenografted tumours. Interestingly, higher Elk1 mRNA expression was also associated with worse recurrence-free survival in TNBC patients by Kaplan-Meier survival analysis.
  
  
  
  Our findings indicated that EGFR-independent pharmacological modulation on Elk1/CIP2A signalling mediates the apoptotic effect of TD52 in TNBC cells, suggesting the potential therapeutic strategy.
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan; School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei 112, Taiwan; Comprehensive Breast Health Center, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Liu
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan; Comprehensive Breast Health Center, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Tzu-Ting
authors.initials: TT
authors.lastname: Huang
authors.affiliation: School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei 112, Taiwan; Division of Hematology & Oncology, Department of Medicine, Yang-Ming Branch of Taipei City Hospital, No.145, Zhengzhou Road, Datong Dist., Taipei 10341, Taiwan.
authors.forename: Chun-Teng
authors.initials: CT
authors.lastname: Huang
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, Cardinal Tien Hospital, No. 362, Zhong-zheng Road, New Taipei City 231, Taiwan; School of Medicine, Fu Jen Catholic University, No. 510, Zhong-zheng Road, Xin-zhuang Dist., New Taipei City 24205, Taiwan.
authors.forename: Ming-Hung
authors.initials: MH
authors.lastname: Hu
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Duen-Shian
authors.initials: DS
authors.lastname: Wang
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Wan-Lun
authors.initials: WL
authors.lastname: Wang
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Wen-Chun
authors.initials: WC
authors.lastname: Tsai
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Chia-Han
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Ka-Yi
authors.initials: KY
authors.lastname: Lau
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
authors.forename: Hsiu-Ping
authors.initials: HP
authors.lastname: Yang
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan; School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei 112, Taiwan.
authors.forename: Ming-Huang
authors.initials: MH
authors.lastname: Chen
authors.affiliation: Institute of Biopharmaceutical Sciences, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei 112, Taiwan.
authors.forename: Chung-Wai
authors.initials: CW
authors.lastname: Shiau
authors.affiliation: School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei 112, Taiwan; Department of Surgery, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan; Comprehensive Breast Health Center, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan. Electronic address: lmtseng@vghtpe.gov.tw.
authors.forename: Ling-Ming
authors.initials: LM
authors.lastname: Tseng
authors.affiliation: Department of Medical Research, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan; National Taiwan University College of Medicine, No.1 Sec. 1, Jen-Ai Road, Taipei 100, Taiwan. Electronic address: kfchen1970@ntu.edu.tw.
authors.forename: Kuen-Feng
authors.initials: KF
authors.lastname: Chen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D066246:ErbB Receptors / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride / Q000494:pharmacology*; D064593:Heterografts; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D050807:ets-Domain Protein Elk-1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D001324:Autoantigens; C500266:CIP2A protein, human; C494112:ELK1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D050807:ets-Domain Protein Elk-1; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors
keywords: CIP2A; EGFR; Elk1; Erlotinib; Triple-negative breast cancer