Par3 and ZO-1 Membrane Clustering is an Indicator of Poor Prognosis in Lung Squamous Cell Carcinoma.

Epithelial cells form epithelial tissue structures by joining together via intercellular adhesion structures composed of intercellular adhesion factors such as zona occludins-1 (ZO-1). Epithelial cells are polarized at the apical and basal regions, and are bordered by intercellular adhesion structures called tight junctions; the organelles within epithelial cells are distributed asymmetrically. Maintenance of this asymmetry in normal epithelial cells is essential for normal cytoskeletal remodeling, movement, and cell division. The key factor regulating cell polarity is called partitioning-defective protein 3 (Par3). Abnormalities in cell polarity and intercellular adhesion are common features of many cancer tissues. Mutation and loss of cell polarity regulators contributes to the immortalization of normal cells and to the malignant transformation of cancer cells. In this study, we investigated the relationship between the subcellular localization of Par3 and ZO-1 and clinicopathological features of lung squamous cell carcinoma (lung SqCC). Both molecules were localized to the cell membrane in normal lung tissue, but the levels were lower at this location in pulmonary tumor tissue compared with normal lung tissue. Both Par3 and ZO-1 accumulated in clusters on the cell membrane (hereinafter, "foci"). Tumor size, recurrence rate, and mortality rate were significantly higher in patients with Par3 foci compared to those without Par3 foci. Rates of lymph node metastasis, recurrence, and mortality were significantly higher in patients with ZO-1 foci than in those without ZO-1 foci. The expression of Par3 and ZO-1 mRNA was not s ignificantly different in s amples from p atients with foci versus those without. These results strongly suggest that the presence of Par3 and ZO-1 foci on the membrane may be a useful prognostic marker for lung SqCC. [ABSTRACT FROM AUTHOR]