title: Marked reduction of type I keratin (K14) in cisplatin-resistant human lung squamous-carcinoma cell lines.
abstract: We have established two cisplatin-resistant human lung squamous-carcinoma cell lines, PC10-B3 and PC10-E5, from their original cell line PC10. To discover which proteins are associated with cisplatin resistance, we carried out a two-dimensional gel electrophoresis to analyze differences in protein alteration between PC10, PC10-B3 and PC10-E5. A protein spot M(r) 50 kDa, pI5.3, was reduced markedly and a spot M(r) 50 kDa, pI4.9 was increased when PC10-B3 and PC10-E5 were compared with PC10. A spot M(r) 58 kDa, pI5.8 newly appeared only in PC10-E5. Cell fractionation showed that the M(r) 50 kDa, pI5.3 (p50-5.3) and the M(r) 50 kDa, pI4.9 fell within the nuclear fraction, while the M(r) 58 kDa, pI5.8 was found among the cytosol and microsomal fractions. Microsequencing after in situ digestion of the dramatically reduced spot p50-5.3 revealed that it was identical to 50 kDa, type I keratin (K14). Moreover, a retinoic acid-mediated K14 reduction was concomitant with a 4.0-fold increase in cisplatin resistance in PC10. Our report is the first to suggest the possible association of marked K14 reduction and cisplatin resistance in PC10-B3 and PC10-E5.
authors.affiliation: Laboratory of Molecular Genetics, Cancer Institute, Sapporo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Katabami
authors.forename: H
authors.initials: H
authors.lastname: Fujita
authors.forename: K
authors.initials: K
authors.lastname: Honke
authors.forename: A
authors.initials: A
authors.lastname: Makita
authors.forename: H
authors.initials: H
authors.lastname: Akita
authors.forename: H
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Kawakami
authors.forename: N
authors.initials: N
authors.lastname: Kuzumaki
mesh_terms: D000595:Amino Acid Sequence; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D002999:Clone Cells / Q000378:metabolism; D004351:Drug Resistance; D006801:Humans; D007633:Keratins / Q000032:analysis*; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D007633:Keratins; D002945:Cisplatin