Metallothionein expression in renal cell carcinoma: Subcellular localization and prognostic significance

Purpose: We investigated the immunohistochemical localization of metallothi onein (MT) in renal cell carcinoma and determined the potential role of MT expression as a possible prognostic variable for tumor proliferation and pr ogression. Materials and Methods: Tumor tissue blocks from SU patients with renal cell carcinoma who underwent radical or partial nephrectomy were investigated, Mean followup plus or minus standard error was 36 +/- 3 months. Immunohisto chemical testing was performed by the avidin-streptavidin method using a mo noclonal mouse antiMT antibody. MT staining intensity in samples was evalua ted semiquantitatively. The subcellular distribution of MT was also determi ned. Staining characteristics were compared with the clinicopathological re sults. Results: MT immunostaining was found in 39 of 70 tumors (55.7%) and subcell ulary MT was localized in the cytoplasm, nucleus and cell membrane. The sur vival of patients with MT immunostaining was significantly worse than that of those with MT negative results (p = 0.02). A significant relationship of higher tumor grade and MT staining intensity was observed in grades I and III (p = 0.01), and grades II and III (p = 0.02) tumors. No association was found of MT expression and pathological stage. Sarcomatoid tumors showed s ignificantly higher MT expression than clear cell, papillary, granular or c hromophobe tumors (p = 0.02, 0.001, 0.91 and 0.01, respectively). MT expres sion was not an independent prognostic variable. Conclusions: MT over expression seems to be associated with malignant behav ior and poor prognosis in renal cell carcinoma. Therefore, MT expression ma y be considered a useful marker or less differentiated and more aggressive renal cell carcinoma.