CHL1 hypermethylation as a potential biomarker of poor prognosis in breast cancer.
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.
Cancer Epigenetics Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.
Esperanza
E
Martín-Sánchez
Cancer Epigenetics Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.
Saioa
S
Mendaza
Cancer Epigenetics Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.
Ane
A
Ulazia-Garmendia
Cancer Epigenetics Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.
Iñaki
I
Monreal-Santesteban
Immunomodulation Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.
Idoia
I
Blanco-Luquin
Department of Pathology, Complejo Hospitalario de Navarra, Servicio Navarro de Salud-Osasunbidea, Pamplona, Spain.
Alicia
A
Córdoba
Department of Surgery, Complejo Hospitalario de Navarra, Servicio Navarro de Salud-Osasunbidea, Pamplona, Spain.
Francisco
F
Vicente-García
Cancer Epigenetics Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.
Noemí
N
Pérez-Janices
Immunomodulation Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.
David
D
Escors
Confocal Microscopy Unit, Spanish National Cancer Research Centre, Madrid, Spain.
Diego
D
Megías
Cancer Epigenetics Group, Cancer Epigenetics and Biology Program, Bellvitge Biomedical Research Institute - IDIBELL, Barcelona, Spain.
Paula
P
López-Serra
Cancer Epigenetics Group, Cancer Epigenetics and Biology Program, Bellvitge Biomedical Research Institute - IDIBELL, Barcelona, Spain.|Department of Physiological Sciences II, School of Medicine, University of Barcelona, Barcelona, Spain.|Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
Manel
M
Esteller
Department of Oncology, Complejo Hospitalario de Navarra, Servicio Navarro de Salud-Osasunbidea, Pamplona, Spain.
José Juan
JJ
Illarramendi
Cancer Epigenetics Group, Navarrabiomed. Departmento de Salud-UPNA. IdiSNA, Pamplona, Spain.|Department of Pathology, Complejo Hospitalario de Navarra, Servicio Navarro de Salud-Osasunbidea, Pamplona, Spain.
David
D
Guerrero-Setas
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D001943:Breast Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000096:biosynthesis / Q000235:genetics*; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D018572:Disease-Free Survival; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D016016:Proportional Hazards Models; D034622:RNA Interference; D017422:Sequence Analysis, DNA / Q000379:methods / Q000706:statistics & numerical data
D014408:Biomarkers, Tumor; C490650:CHL1 protein, human; D015815:Cell Adhesion Molecules
CHL1; DNA methylation; breast cancer; prognostic biomarker