title: Cytokeratin 19 regulates endoplasmic reticulum stress and inhibits ERp29 expression via p38 MAPK/XBP-1 signaling in breast cancer cells.
abstract: Cytokeratin 19 (CK19) is widely used as a biomarker for the detection of disseminated tumor cells in blood and bone marrow, and its positivity is considered as an independent prognostication indicator in cancer patients. However, its role in breast cancer progression remains unknown. We had established a stable CK19-expressing clone in the CK19-negative BT549 human breast cancer cell line and found that CK19 expression in the BT549 cells caused cell cycle arrest, reduced cell motility and increased drug resistance. Further study revealed that CK19 expression regulated endoplasmic reticulum (ER) stress signaling by up-regulating p38/RNA-dependent protein kinase-like ER kinase (PERK)/p-eIF2alpha and 78 kDa glucose-regulated protein (Bip/GRP78), and down-regulating focal adhesion kinase (FAK). The level of ER protein 29 (ERp29) was shown to be decreased in the CK19-expressing BT549 cells by proteomic analyses and verified by Western blotting and RT-PCR. Pharmacological inhibition of p38 signaling by its specific inhibitor SB203580 or knockdown of p38 and transcription factor XBP-1 by siRNA in BT549/CK19 and MDA-MB-231 cells revealed that p38/XBP-1 signaling negatively regulated ERp29 expression. Our results indicated that CK19 modulates ER stress signaling and contributes to cell survival and dormancy in breast cancer cells.
authors.affiliation: Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: I Fon
authors.initials: IF
authors.lastname: Bambang
authors.forename: Dan
authors.initials: D
authors.lastname: Lu
authors.forename: Huiping
authors.initials: H
authors.lastname: Li
authors.forename: Lily-Lily
authors.initials: LL
authors.lastname: Chiu
authors.forename: Quek Choon
authors.initials: QC
authors.lastname: Lau
authors.forename: Evelyn
authors.initials: E
authors.lastname: Koay
authors.forename: Daohai
authors.initials: D
authors.lastname: Zhang
mesh_terms: D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D015870:Gene Expression; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D053539:Keratin-19 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008954:Models, Biological; D040901:Proteomics; D034741:RNA, Small Interfering / Q000235:genetics; D000071701:Regulatory Factor X Transcription Factors; D013312:Stress, Physiological; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D000071717:X-Box Binding Protein 1; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; C491738:ERP29 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D053539:Keratin-19; D034741:RNA, Small Interfering; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D048051:p38 Mitogen-Activated Protein Kinases