Platelet Cloaking of Cancer Cells Alters Apoptotic Potential: Implications for Metastasis.
Darragh J Crowley, Paul A Smyth, Cathy D Spillane, Sharon A O'Toole, Karl Egan, Dermot Kenny, Orla M Sheils, John J O'Leary. Trinity College Dublin, Ireland; Royal College of Surgeons in Ireland, Dublin, Ireland
Background: Ovarian cancer (OC) is the leading cause of death from gynaecological malignancy. OC frequently presents with thrombocytosis, possibly associated with Tumour Cell Induced Platelet Aggregation (TCIPA). TCIPA has been observed to protect platelet 'cloaked' cancer cells from TNF-α-, NK cell- and chemotherapeutic agent-mediated destruction, and enhance their metastatic capacity. This study aims to determine the genetic basis for this enhancement though whole transcriptome analysis of cells exposed to washed platelets (WPL) or platelet releasate (PLR).
Design: PLR concentrations for use on cell lines representing normal ovarian epithelium (HIO-80) and ovarian epithelial cancer (59M, SK-OV 3, A2780, A2780cis) were optimised by MTT assay. Cells were exposed to PLR or equivalent WPL for 8 h. Total RNA was extracted, prepared for Affymetrix Human Exon Array and analysis was performed using Affymetrix Gene Chip QC and Biotique Systems XRAY software. Twenty six significantly altered genes were validated by Fluidigm Dynamic Array for Gene Expression.
Results: XRAY analysis indicates context-specific significant changes (P<0.05; fold change >1.5) in gene expression in response to PLR and WPL exposure. Ovarian cancer cell lines 59M and SK-OV 3 returned the greatest response to PLR exposure with A2780cis, HIO-80 and 59M responding most to WPL. These exposures altered expression of genes involved in; ♦59M: anti-apoptotic, anti-autophagy, pro-angiogenic and proliferative signalling and reduced expression of genes important in maintaining genomic stability. ♦SK-OV 3: cell cycle, metabolic and transcriptional regulation, regulators of TSGs/oncogenes. ♦A2780cis: anti-apoptosis, transcriptional regulation, protease expression and cell-cell interaction. ♦HIO-80: metabolic and transcription regulation
Conclusions: Relative changes in gene expression in exposure groups compared to control group indicate a context-defined response in a panel of ovarian cell lines to either PLR or WPL. We hypothesise that these changes indicate TCIPA-induced pro-metastatic signalling, mediating its effects through mechanical platelet-cancer cell signalling and via the content of platelet granules released during this interaction. This results in pro-angiogenic, proliferative and anti-apoptotic signalling in addition to regulation of translation, cell cycle and metabolism to enhance successful metastasis. This work is supported the Irish Health Research Board (HRB) PhD Programme in Molecular Medicine: From Genes to Function.
Category: Special Category - Pan-genomic/Pan-proteomic approaches to Cancer
Monday, February 28, 2011 1:00 PM
Poster Session II # 232, Monday Afternoon