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Int J Clin Exp Pathol 2012;5(2):126-136

Review Article
Tight junctions in lung cancer and lung metastasis: a review

Ylermi Soini

Department of Pathology and Forensic Medicine, Institute of Clinical Medicine, Pathology and Forensic Medicine, School of Medicine, University
of Eastern Finland, Cancer Center of Eastern Finland, P.O.Box 1627, FI-70211 Kuopio, Finland

Received January 9, 2012; accepted January 31, 2012; Epub February 12, 2012; Published February 28, 2012

Abstract: Tight junctions are structures located in the apicobasal region of the cell membranes. They regulate paracellular solute and electrical
permeability of cell layers. Additionally, they influence cellular polarity, form a paracellular fence to molecules and pathogens and divide the cell
membranes to apical and lateral compartments. Tight junctions adhere to the corresponding ones of neighbouring cells and by this way also
mediate attachment of the cells to one other. Molecules forming the membranous part of tight junctions include occludin, claudins, tricellulin
and junctional adhesion molecules. These molecules are attached to scaffolding proteins such as ZO-1, ZO-2 and ZO-3 through which signals
are mediated to the cell interior. Expression of tight junction proteins, such as claudins, may be up- or downregulated in cancer and they are
involved in EMT thus influencing tumor spread. Like in tumors of other sites, lung tumors show changes in the expression in tight junction
proteins. In this review the significance of tight junctions and its proteins in lung cancer is discussed with a focus on the proteins forming the
membranous part of these structures.

Keywords: Tight junction, claudin, lung, carcinoma, metastasis

Address all correspondence to:
Dr. Ylermi Soini
Department of Pathology and Forensic Medicine
School of Medicine, University of Eastern Finland
Po Box 1627, FI-70211 Kuopio, Finland.
E-mail: ylermi.soini@uef.fi