RESUMO
BACKGROUND: The majority of patients diagnosed with advanced epithelial ovarian carcinoma (EOC) relapse with resistant disease, and there are no biomarkers that possess clinical utility to identify or monitor these patients. This study aimed to identify secreted proteins ('secretome') collected from human EOC cell lines that differ in their inherent platinum sensitivity. METHODS: Secreted proteins collected from conditioned medium from ovarian cancer cell lines that vary in their sensitivity to cisplatin were digested with trypsin and analysed by liquid chromatography-tandem mass spectrometry for peptide identification. RESULTS: Of the 1688 proteins identified, 16 possessed significant differential abundances (P<0.05) between the platinum-resistant and -sensitive cell lines. A number of these were verified by immunoblot, including COL11A1, which was also found to be associated with worse progression-free survival (PFS; N=723) and overall survival (OS; N=1183) as assessed from publicly available transcript expression data from ovarian cancer tumour specimens. CONCLUSION: Secretome proteomics of EOC cells resulted in the identification of a novel candidate biomarker, COL11A1. The expression level of COL11A1 correlates to worse PFS and OS, and is predicted to reside in peripheral circulation making this an attractive candidate for validation in sera as a biomarker of cisplatin resistance and poor outcome.
Assuntos
Biomarcadores Tumorais/sangue , Colágeno Tipo XI/sangue , Proteínas de Neoplasias/sangue , Neoplasias Epiteliais e Glandulares/sangue , Neoplasias Ovarianas/sangue , Biomarcadores Tumorais/biossíntese , Biomarcadores Tumorais/genética , Carcinoma Epitelial do Ovário , Linhagem Celular Tumoral , Cisplatino/farmacologia , Colágeno Tipo XI/biossíntese , Colágeno Tipo XI/genética , Meios de Cultura , Intervalo Livre de Doença , Resistencia a Medicamentos Antineoplásicos , Feminino , Expressão Gênica , Humanos , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Neoplasias Epiteliais e Glandulares/tratamento farmacológico , Neoplasias Epiteliais e Glandulares/genética , Neoplasias Epiteliais e Glandulares/metabolismo , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Proteômica , Taxa de SobrevidaRESUMO
Nuclear factor kappa B (NF-kappaB) is a ubiquitous, inducible transcription factor that regulates the initiation and progression of immune and inflammatory stress responses. NF-kappaB activation depends on phosphorylation and degradation of its inhibitor protein, IkappaB, initiated by an IkappaB kinase (IKK) complex. This IKK complex includes a catalytic heterodimer composed of IkappaB kinase 1 (IKK1) and IkappaB kinase 2 (IKK2) as well as a regulatory adaptor subunit, NF-kappaB essential modulator. To better understand the role of IKKs in NF-kappaB activation, we have cloned, expressed, purified, and characterized the physiological isoform, the rhIKK1/rhIKK2 heterodimer. We compared its kinetic properties with those of the homodimers rhIKK1 and rhIKK2 and a constitutively active rhIKK2 (S177E, S181E) mutant. We demonstrate activation of these recombinantly expressed IKKs by phosphorylation during expression in a baculoviral system. The K(m) values for ATP and IkappaBalpha peptide for the rhIKK1/rhIKK2 heterodimer are 0.63 and 0.60 micrometer, respectively, which are comparable to those of the IKK2 homodimer. However, the purified rhIKK1/rhIKK2 heterodimer exhibits the highest catalytic efficiency (k(cat)/K(m)) of 47.50 h(-1) micrometer(-1) using an IkappaBalpha peptide substrate compared with any of the other IKK isoforms, including rhIKK2 (17.44 h(-1) micrometer(-1)), its mutant rhIKK2 (S177E, S181E, 1.18 h(-1) micrometer(-1)), or rhIKK1 (0.02 h(-1) micrometer(-1)). Kinetic analysis also indicates that, although both products of the kinase reaction, ADP and a phosphorylated IkappaBalpha peptide, exhibited competitive inhibitory kinetics, only ADP with the low K(i) of 0.77 micrometer may play a physiological role in regulation of the enzyme activity.
Assuntos
Proteínas Serina-Treonina Quinases/química , Catálise , Dimerização , Eletroforese em Gel de Poliacrilamida , Humanos , Quinase I-kappa B , Cinética , Peso Molecular , Proteínas Recombinantes/químicaRESUMO
Eikenella corrodens is a gram-negative human pathogen associated with periodontal diseases and soft-tissue infections. Pilin was purified by association-dissociation and fast protein liquid chromatography; it had an apparent molecular mass of about 14.8 kDa and an N-terminal amino acid sequence reflective of type IV pilins. Antibodies to the purified protein reacted with pili on whole cells. This is the first report of purification of type IV pili/pilin from this organism. Other type IV pili are important virulence factors; we are currently investigating the biological role of pili in E. corrodens.