title: High CerS5 expression levels associate with reduced patient survival and transition from apoptotic to autophagy signalling pathways in colorectal cancer.
abstract: Ceramide synthase 5 is involved in the de novo synthesis of ceramide, a sphingolipid involved in cell death and proliferation. In this study, we investigated the role of ceramide synthase 5 in colorectal cancer by examining ceramide synthase 5 expression, clinico-pathological parameters and association with survival/death signalling pathways in cancer. Immunohistochemical analysis of CerS5 was performed on 102 colorectal cancer samples using tissue microarrays constructed from formalin-fixed and paraffin-embedded tissues. We found strong membranous ceramide synthase 5 staining in 57 of 102 (56%) colorectal cancers. A multivariate Cox regression analysis of ceramide synthase 5 expression adjusted for disease stage, differentiation and lymphovascular invasion revealed reduced 5-year overall survival (p = 0.001) and 5-year recurrence-free survival (p = 0.002), with hazard ratios of 4.712 and 4.322, respectively. The effect of ceramide synthase 5 expression on tumourigenic processes was further characterised by reverse phase protein array analysis. Reverse phase protein arrays were generated from laser capture microdissection-enriched carcinoma cells from 19 fresh-frozen colorectal cancer tissues. Measurements of phosphorylation and total levels of signalling proteins involved in apoptosis, autophagy and other cancer-related pathways revealed two distinct signalling networks; weak membranous ceramide synthase 5 intensity was associated with a proteomic network dominated by signalling proteins linked to apoptosis, whereas strong ceramide synthase 5 intensity was associated with a proteomic sub-network mostly composed of proteins linked to autophagy. In conclusion, high ceramide synthase 5 expression was found in colorectal cancer tissue and was associated with poorer patient outcomes. Our findings suggest that this may be mediated by a transition from apoptotic to autophagy signalling pathways in ceramide synthase 5 High expressing tumours, thus implicating ceramide synthase 5 in the progression of colorectal cancer.
authors: Biomedical Diagnostics Institute, Dublin City UniversityDublinIreland; School of Biotechnology, Dublin City UniversityDublinIreland.
authors: Seán
authors: S
authors: Fitzgerald
authors: Department of Pathology Royal College of Surgeons in Ireland and Beaumont Hospital Dublin Ireland.
authors: Katherine M
authors: KM
authors: Sheehan
authors: Center for Applied Proteomics and Molecular Medicine George Mason University Manassas VA USA.
authors: Virginia
authors: V
authors: Espina
authors: Department of Pathology Royal College of Surgeons in Ireland and Beaumont Hospital Dublin Ireland.
authors: Anthony
authors: A
authors: O'Grady
authors: Department of Pathology Royal College of Surgeons in Ireland and Beaumont Hospital Dublin Ireland.
authors: Robert
authors: R
authors: Cummins
authors: Biomedical Diagnostics Institute, Dublin City UniversityDublinIreland; Molecular and Cellular TherapeuticsThe Royal College of Surgeons in IrelandDublinIreland.
authors: Dermot
authors: D
authors: Kenny
authors: Center for Applied Proteomics and Molecular Medicine George Mason University Manassas VA USA.
authors: Lance
authors: L
authors: Liotta
authors: Biomedical Diagnostics Institute, Dublin City UniversityDublinIreland; School of Biotechnology, Dublin City UniversityDublinIreland.
authors: Richard
authors: R
authors: O'Kennedy
authors: Department of Pathology Royal College of Surgeons in Ireland and Beaumont Hospital Dublin Ireland.
authors: Elaine W
authors: EW
authors: Kay
authors: Biomedical Diagnostics Institute, Dublin City University Dublin Ireland.
authors: Gregor S
authors: GS
authors: Kijanka
keywords: apoptosis; autophagy; ceramide synthase 5; colorectal cancer; laser capture microdissection; prognosis; reverse phase protein arrays