[Frontiers in Bioscience 16, 815-837, January 1, 2011]

Epithelial and mesenchymal phenotypic switchings modulate cell motility in metastasis

Alan Wells1, Yvonne L Chao1, Jelena Grahovac1, Qian Wu1, Douglas A Lauffenburger2

1Department of Pathology, Pittsburgh VAMC and University of Pittsburgh, Pittsburgh PA 15217 USA, 2Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge MA 02139, USA


1. Abstract
2. Introduction
3. Disruption of cell adhesion in EMT enables cell motility
3.1.EMT and aberrant regulation of adhesion molecules at the primary site
3.1.1. Tight Junctions
3.1.2. Cadherins
3.1.3. Desmosomes
3.1.4. Gap Junctions
3.1.5. Integrins
3.2. Loss of cell polarity leads to dysfunctional growth factor signaling
4. Motility in escape from primary site
4.1. Motility signaled from soluble factors
4.1.1. EGF
4.1.2. HGF
4.1.3. IGF-1
4.1.4. TGFbeta
4.1.5. Cytokines/chemokines
4.1.6. TNFalpha
4.1.7. SDF-1/CXCL12
4.2. Motility signaled from the Matrix
4.2.1. Collagen I
4.2.2. Laminin 5
4.2.3. Tenascin C
4.3. Avoidance of Stop Signals
5. Motility and Phenotype at the Target Organ
5.1. Expression of adhesion molecules during extravasation
5.2. Adhesion molecules during colonization
6. Migration in mesenchymal and epithelial phenotypes
7. Future directions
8. Acknowledgements
9. References


The most ominous stage of cancer progression is metastasis, or the dissemination of carcinoma cells from the primary site into distant organs. Metastases are often resistant to current extirpative therapies and even the newest biological agents cure only a small subset of patients. Therefore a greater understanding of tumor biology that integrates properties intrinsic to carcinomas with tissue environmental modulators of behavior is needed. In no aspect of tumor progression is this more evident than the acquisition of cell motility that is critical for both escape from the primary tumor and colonization. In this overview, we discuss how this behavior is modified by carcinoma cell phenotypic plasticity that is evidenced by reversible switching between epithelial and mesenchymal phenotypes. The presence or absence of intercellular adhesions mediate these switches and dictate the receptivity towards signals from the extracellular milieu. These signals, which include soluble growth factors, cytokines, and extracellular matrix embedded with matrikines and matricryptines will be discussed in depth. Finally, we will describe a new mode of discerning the balance between epithelioid and mesenchymal moevement.