Calponin h1 expression in renal tumor vessels: correlations with multiple pathological factors of renal cell carcinoma.

PURPOSE

We determined whether the architecture of renal tumor vessels is immunohistochemically different from that of normal renal vessels and related to the various pathological factors that affect prognosis of renal cell carcinoma (RCC).

MATERIALS AND METHODS

A total of 52 cases of primary RCC were selected. Tissues from radical nephrectomy specimens were stained with antibody to alpha-smooth muscle actin (alpha-SMA) and calponin h1. Immunostaining was evaluated semiqualitatively as 0-no staining to 3+-strong staining. Tumor cell proliferation was observed using proliferating marker Ki-67. Data were statistically compared with pathological factors, such as tumor size, histological pattern, growth pattern, cell type, nuclear grade, pathological stage and presence or absence of venous invasion.

RESULTS

In normal renal tissues smooth muscle cells of the blood vessels showed strong immunoreactions with antibody to calponin h1 and alpha-SMA. Although alpha-SMA antibody showed similar strong immunoreactions in all types of renal tumor vessels, we observed qualitative alterations in the expression of calponin h1 in different types of RCCs. Strong to moderate immunoreactions with calponin h1 were observed in tumors with expansive growth and an alveolar pattern. Small tumors without venous invasion and chromophobe cell carcinomas also showed strong to moderate expression of calponin h1. Weak or absent expression of calponin h1 was observed significantly in infiltrating tumors, sarcomatous type, large, high grade and high stage tumors associated with significantly higher proliferating indexes.

CONCLUSIONS

Our results strongly suggest that the renal tumor vessels are immunohistochemically different from normal renal vessels in respect to calponin h1 expression. We speculate that due to the decrease in or absence of calponin h1 tumor vessels do not develop adequate maturity to maintain vascular integrity. In addition, the distribution of calponin h1 significantly correlated with multiple pathological factors of RCC. Therefore, calponin h1 expression in renal tumor vessels could be a new, important pathological factor in RCC.