The Epithelial Mesenchymal Transition (EMT) Profile of Platelet Cloaked Cancer Cells.
Darragh J Crowley, Paul A Smyth, Sharon A O'Toole, Karl Egan, Dermot Kenny, Orla M Sheils, John J O'Leary. Trinity College Dublin, Ireland; Royal College of Surgeons Ireland, Dublin, Ireland
Background: Ovarian cancer (OC) has a mortality rate of 75% and is the leading cause of death from gynaecological malignancy. Almost half of patients diagnosed with OC present with thrombocytosis. This may be associated with Tumour Cell-Induced Platelet Aggregation (TCIPA), observed to protect platelet 'cloaked' cancer cells from TNF-α-, natural killer cell- and chemotherapeutic agent-mediated death, and enhance their capacity for metastasis. Epithelial-Mesenchymal Transition (EMT) is a programme of cell development employed during embryonic development, and also in oncogenesis and metastasis where it is characterised by loss of cell adhesion, increased mobility, invasiveness and chemoresistance. The present study was to determine if TCIPA mediates its enhancement of ovarian cancer cells' capacity to metastasise through induction of EMT.
Design: The effect of platelet releasate concentrations on cell lines representing normal ovarian epithelium (HIO-80) and ovarian epithelial cancer (59M, SK-OV 3, A2780, A2780cis) was optimised by MTT assay. Cells were exposed to platelet releasate (PLR) or equivalent concentration of washed platelets (WPL) for 8 h. Total RNA was extracted using Qiagen RNeasy Kit and cDNA was prepared for use in TaqMan assay of key markers of EMT: ALDH1A1, AKT1, CDH1, PIK3CA, SNAIL1, SNAIL2, TWIST1, VIM, ZEB1 and ZEB2. Expression changes were determined using the Spotfire Software suite.
Results: TaqMan analysis of EMT markers in ovarian cell lines exposed to washed platelets or platelet releasate indicates significant (p<0.05) alteration of some genes: ♦HIO-80 cells showed increased SLUG expression in response to WPL exposure. ♦59M cells showed increased CDH1 and reduced AKT1 expression in response to both WPL and PLR, reduced SNAIL expression and increased ZEB1 expression in response to WPL and PLR exposure respectively. ♦A2780cis cells increased VIM expression in response to both conditions and increased expression of TWIST in response to PLR.
Conclusions: These data indicate a differential response to platelet releasate and washed platelets in cell lines reflecting epithelial health from normal to malignant ovarian disease. Thus, in platelet cloaked metastasis, while cloaking may not be sufficient to independently drive EMT, it may contribute to establishing or maintaining a pro-EMT signal in metastasising ovarian cancer cells. 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 # 245, Monday Afternoon