Cytoplasmic PAR-3 protein expression is associated with adverse prognostic factors in clear cell renal cell carcinoma and independently impacts survival.

Clear cell renal cell carcinomas (ccRCCs) represent 70% of renal cancers, and several clinical and histolopathological factors are implicated in their prognosis. We recently demonstrated that the overexpression of PAR-3 protein encoded by the PARD3 gene could be implicated in renal oncogenesis. The object of this work was to study the association of intratumoral PAR-3 expression with known prognostic parameters and clinical outcome. In this aim, PAR-3 expression was assessed by immunohistochemistry in ccRCC tumors of 101 patients from 2003 to 2005. The immunostaining of PAR-3 was scored either as membranous (mPAR-3) or as both membranous and cytoplasmic (cPAR-3). Cytoplasmic PAR-3 was significantly associated with worse histopathological and clinical prognostic factors: Fuhrman grades 3 and 4, tumor necrosis, sarcomatoid component, adrenal invasion, renal and hilar fat invasion, eosinophilic component, a noninactivated VHL gene, higher tumor grade, lymph node involvement, metastasis, and worse clinical Eastern Cooperative Oncology Group and S classification scores. After multivariate analysis, 2 parameters were independently associated with cPAR-3: necrosis and eosinophilic components. In addition, cPAR-3 patients had shorter overall and progression-free survivals independently from strong prognostic validated factors like metastases. A cytoplasmic expression of PAR-3 is therefore implicated in worse clinical and pathological cancer features in ccRCC and could be useful to identify patients with high-risk tumors.