Basic Research - Cancer(구연) Oral Session 3 / Basic Research - Cancer (Ⅱ) (O-027) Rm.201 10월 30일(수) 14:00-15:00 Phosphorylated PAK4 expression is associated with aggressive histologic features and poor prognosis in patients with surgically treated renal cell carcinoma 충북대학교 의과대학 비뇨의학교실 서성필, 변영준, 박현미, 정필두, 이희윤, 강호원, 김원태, 김용준, 윤석중, 이상철, 김원재 Objective: p21-Activated kinase 4 (PAK4) is a serine/threonine kinase that regulates a number of fundamental cellular processes and has been suggested as prognostic factor in renal cell carcinoma (RCC). The aim of the present study was to evaluate the clinical implications of phosphorylated PAK4 (pPAK4), which represent PAK4 activity, in surgically treated RCC. Materials and Methods: Immunohistochemical staining for PAK4 and pPAK4S474 was performed in 131 patients with surgically treated RCC. Expression of PAK4 and pPAK4S474 was compared with clinicopathological characteristics and survival after nephrectomy. Results: PAK4 and pPAK4 expressions were predominant in the nucleus. Overall, 57.3% (75/131) and 22.1% (29/119) of specimens exhibited high pPAK4S474 and PAK4 expression, respectively. High pPAK4S474 expression was associated with adverse pathologic features, including advanced tumor stage and grade (P= 0.036 and P= 0.002, respectively), whereas PAK4 expression was not associated with tumor characteristics (each P > 0.05). Kaplan-Meier estimates showed that high pPAK4S474 expression was significantly associated with shorter recurrence free survival in localized RCC subgroup and cancer specific survival in total RCC cohort (log rank test, P= 0.001, P= 0.005, respectively), while PAK4 expression did not. In multivariate Cox regression analysis, high pPAK4S474 expression was an independent predictor of development of recurrence in subgroup of localized RCC. Conclusions: Our study showed that pPAK4, which represent PAK4 activity, could be more accurate prognostic factor than total Pak4 expression in RCC patients. keywords : renal cell carcinoma, p21-Activated kinase 4, survival