Expression and Distribution of Galectin-3 in Chromophobe and Papillary Carcinomas

Probably due to their low occurrence, chromophobe and papillary renal cell carcinomas are less well characterized and, currently, there are no reliable prognostic markers for this group of patients. Moreover, the optimal therapy for patients with non-clear renal cell carcinoma (RCC) is unknown yet. Although elevated levels of Galectin-3 (Gal-3) were associated with poor prognosis in conventional RCC, the impact of this protein on carcinogenesis of chromophobe and papillary entities has not been previously described.

Gal-3 expression was investigated in 34 consecutive cases of RCCs, including 19 papillary carcinomas and 15 chromophobe carcinomas.

Immunohistochemical analysis of Gal-3 in tumor cells showed 3 patterns of expression: membranous, cytoplasmic and nuclear staining. Most tumors included in our study showed a cytoplasmic expression and it was almost equally distributed between the histologic subtypes. However, only nuclear staining of Gal-3 was associated with both Fuhrman grade and tumor stage (p=0.016 and p=0.032, respectively) in chromophobe subtype.

Our results indicate that the nuclear expression of Gal-3 has an essential role in the development of chromophobe carcinoma. The association with advanced tumor stage and nuclear grade suggests that this protein is an indicator of aggressiveness in the chromophobe subtype, thus targeting anti-nuclear transport may prove an effective therapy for this particular group of patients.