Abstract
Resistance to anoikis, a cell-detachment induced apoptosis, is one of the malignant phenotypes which support tumor metastasis. Molecular mechanisms underlying the establishment of this phenotype require further investigation. This study aimed at exploring protein expression profiles associated with anoikis resistance of a metastatic breast cancer cell. Cell survival of suspension cultures of non-metastatic MCF-7 and metastatic MDA-MB-231 cells were compared with their adherent cultures. Trypan blue exclusion assays demonstrated a significantly higher percentage of viable cells in MDA-MB-231 than MCF-7 cell cultures, consistent with analysis of annexin V-7-AAD stained cells indicating that MDA-MB-231 possess anti-apoptotic ability 1.7 fold higher than MCF-7 cells. GeLC-MS/MS analysis of protein lysates of MDA-MB-231 and MCF-7 cells grown under both culture conditions identified 925 proteins which are differentially expressed, 54 of which were expressed only in suspended and adherent MDA-MB-231 but not in MCF-7 cells. These proteins have been implicated in various cellular processes, including DNA replication and repair, transcription, translation, protein modification, cytoskeleton, transport and cell signaling. Analysis based on the STITCH database predicted the interaction of phospholipases, PLC and PLD, and 14-3-3 beta/alpha, YWHAB, with the intrinsic and extrinsic apoptotic signaling network, suggesting putative roles in controlling anti-anoikis ability. MDA-MB-231 cells grown in the presence of inhibitors of phospholipase C, U73122, and phospholipase D, FIPI, demonstrated reduced ability to survive in suspension culture, indicating functional roles of PLC and PLD in the process of anti-anoikis. Our study identified intracellular mediators potentially associated with establishment of anoikis resistance of metastatic cells. These proteins require further clarification as prognostic and therapeutic targets for advanced breast cancer.
Highlights
Metastasis and invasion are major causes of death from cancers
MDA-MB-231 cells grown in the presence of inhibitors of phospholipase C, U73122, and phospholipase D, Fluoro-2-indolyl des-chlorohalopemide (FIPI), demonstrated reduced ability to survive in suspension culture, indicating functional roles of PLC and PLD in the process of anti-anoikis
MDA-MB-231 cells grown under an anchorageindependent condition show anoikis property higher than MCF-7 cells
Summary
Metastasis and invasion are major causes of death from cancers. They are multi-step processes including dissociation of cancer cells from a primary site, survival in the circulatory and lymphatic systems, and colonization in the distant organs. Growing evidence have indicated that cancer cells achieve resistance to anoikis by several mechanisms including alternations of integrin repertoire, constitutive activation of pro-survival and proliferative signaling, epithelial mesenchymal transition (EMT) and metabolic reprogramming (Kim et al, 2012; Paoli et al, 2013). Following ECM detachment, the hyperactivation of receptor tyrosine kinase growth factor receptors, changes in integrin expression pattern and down-regulation of PTEN result in the activation of pro-survival phosphoinositide 3-kinase (PI3K)/AKT signaling systems This subsequently inhibits apoptotic process, while deregulation of E-cadherins during EMT elicits the migration of β-integrin to the nucleus, where it stimulates expression of target genes responsible for cell motility and invasion (Paoli et al, 2013).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
