Suchergebnisse

The tumor-suppressor protein p16 is paradoxically overexpressed in cervical cancer (CC). Despite its potential as a biomarker, its clinical value and the reasons for its failure in tumor suppression remain unclear. Our purpose was to determine p16 clinical and biological significance in CC. p16 expression pattern was examined by immunohistochemistry in 78 CC cases (high-grade squamous intraepithelial lesions (HSILs) and squamous cell carcinomas of the cervix –SCCCs). CC cell proliferation and invasion were monitored by real-time cell analysis and Transwell® invasion assay, respectively. Cytoplasmic p16 interactors were identified from immunoprecipitated extracts by liquid chromatography-tandem mass spectrometry, and colocalization was confirmed by double-immunofluorescence. We observed that SCCCs showed significantly more cytoplasmic than nuclear p16 expression than HSILs. Importantly, nuclear p16 absence significantly predicted poor outcome in SCCC patients irrespective of other clinical parameters. Moreover, we demonstrated that cytoplasmic p16 interacted with CDK4 and other unreported proteins, such as BANF1, AKAP8 and AGTRAP, which could sequester p16 to avoid nuclear translocation, and then, impair its anti-tumor function. Our results suggest that the absence of nuclear p16 could be a diagnostic biomarker between HSIL and SCCC, and an independent prognostic biomarker in SCCC; and explain why p16 overexpression fails to stop CC growth. ; This research was funded by the Health Department of the Navarre Government (Grant number 21/11), the Navarre Breast Cancer Patients' Association (SARAY) and the 'Proof of concept project on proteomic research' from Proteored (Grant number ProteoRed-0000029). The Proteomics Unit of Navarrabiomed is a member of Proteored, PRB3-ISCIII, and is supported by Grant PT17/0019/009, of the PE I + D + I 2013–2016 funded by ISCIII and ERDF. S.M. was a recipient of a predoctoral grant from the Public University of Navarre. E.M.-S. was a recipient of a fellowship from the Spanish Ministry of Science, Innovation and Universities (PTA2015-11895-I).

The CHL1 gene encodes a cell-adhesion molecule proposed as being a putative tumour-suppressor gene in breast cancer (BC). However, neither the underlying molecular mechanisms nor the clinical value of CHL1 downregulation in BC has been explored. The methylation status of three CpG sites in the CHL1 promoter was analysed by pyrosequencing in neoplastic biopsies from 142 patients with invasive BC and compared with that of non-neoplastic tissues. We found higher CHL1 methylation levels in breast tumours than in non-neoplastic tissues, either from mammoplasties or adjacent-to-tumour, which correlated with lower levels of protein expression in tumours measured by immunohistochemistry. A panel of five BC cell lines was treated with two epigenetic drugs, and restoration of CHL1 expression was observed, indicating in vitro dynamic epigenetic regulation. CHL1 was silenced by shRNA in immortalized but non-neoplastic mammary cells, and enhanced cell proliferation and migration, but not invasion, were found by real-time cell analysis. The prognostic value of CHL1 hypermethylation was assessed by the log-rank test and fitted in a Cox regression model. Importantly, CHL1 hypermethylation was very significantly associated with shorter progression-free survival in our BC patient series, independent of age and stage (p = 0.001). In conclusion, our results indicate that CHL1 is downregulated by hypermethylation and that this epigenetic alteration is an independent prognostic factor in BC. ; This work has been funded in competitive calls by the Spanish Institute of Health and FEDER (PI14/00579), the Basque Foundation for Healthcare Research and Innovation (BIO-11-CM-013), La Caixa Foundation (70789) and the Breast Cancer Patients' Association in Navarra (SARAY). EMS is the recipient of a grant from the Spanish Ministry of Economy and Competitiveness (PTA2015-11895-I); NPJ was the recipient of a predoctoral grant from the Department of Health of the Government of Navarra; DE is funded by a Miguel Servet fellowship from the Spanish Institute of Health.