Expression of Metallothionein and Ki-67 Antigen in GISTs of Different Grade of Malignancy*

Abstract Background. Metallothioneins (MTs) are low molecular weight proteins (6-7 kDa), which have been shown to regulate zinc ion homeostasis. MTs exert anti-apoptotic and pro-proliferative effect on cancer cells. Overexpression of MT-I and MT-II isoforms has been noted in many malignant tumors, but the role of their expression in gastrointestinal stromal tumors (GISTs) remains unclear. Objectives. The aim of the study was to examine the relationship between expression of MT-I/II and K-67 proliferation antigen in a subset of GISTs presenting differential grade of malignancy. Material and Methods. The study was conducted using immunohistochemical methods on archival paraffin sections of 34 cases of GISTs. Of those, 17 tumors were classified as benign (GISTB) and 17 tumors as malignant (GISTM). Results. The GISTM cases demonstrated higher MT-I/II expression as compared to the GISTB cases, but not significantly higher (p = 0.08). The GISTM tumors showed significantly higher expression of Ki-67 antigen than the GISTB cases (p = 0.01). MT-I/II and Ki-67 expression positively correlated in GISTBs (r = 0.48, p = 0.0463), but not in GISTMs. Conclusion. The results of this study may point to a potential role of MT-I/II in the proliferation of GIST cells and disease progression (Adv Clin Exp Med 2013, 22, 4, 513-518)