Polybromo-1 (PBRM1), a SWI/SNF complex subunit is a prognostic marker in clear cell renal cell carcinoma

To analyse the immunohistochemical and mRNA expression of SWI/SNF (SWItch/Sucrose NonFermentable) complex subunit polybromo-1 (PBRM1) in clear cell renal cell carcinoma (ccRCC) and its impact on clinical outcomes.

In all, 213 consecutive patients treated surgically for renal cell carcinoma (RCC) between 1992 and 2009 were selected. A single pathologist reviewed all cases to effect a uniform reclassification and determined the most representative tumour areas for construction of a tissue microarray. In addition, mRNA expression of PBRM1 was analysed by reverse transcriptase-polymerase chain reaction.

Of the 112-immunostained ccRCC specimens, 34 (30.4%) were PBRM1-negative, and 78 (69.6%) were PBRM1-positive. The protein expression of PBRM1 was associated with tumour stage (P < 0.001), clinical stage (P < 0.001), pN stage (P = 0.035) and tumour size (P = 0.002). PBRM1 mRNA expression was associated with clinical stage (P = 0.023), perinephric fat invasion (P = 0.008) and lymphovascular invasion (P = 0.042). PBRM1 significantly influenced tumour recurrence and tumour-related death. Disease-specific survival rates for patients whose specimens showed positive- and negative-PBRM1 expression were 89.7% and 70.6%, respectively (P = 0.017). Recurrence-free survival rates in patients with positive- and negative-expression of PBRM1 were 87.3% and 66.7%, respectively (P = 0.048).

PBRM1-negative expression is a markedly poor prognosis event in ccRCC. We encourage PBRM1 study by other groups in order to validate our findings and confirm its possible role as a useful marker in the management of patients with ccRCC.