Yes-associated protein expression is a predictive marker for recurrence of hepatocellular carcinoma after liver transplantation

To explore the expression of Yes-associated protein (YAP) in hepatocellular carcinoma (HCC) patients, and assess its prognostic value to recurrence of HCC after liver transplantation (LT).

Collected data of 105 consecutive patients undergoing LT for HCC were analyzed retrospectively. The immunohistochemistry was used to detect the expression of YAP, Mst1, Lats1/2, pYAP, pLats1/2 and pMst1/2 in tumor tissues. Contingency table and χ(2)-test were used to investigate the correlation between expression of YAP, Mst1, Lats1/2 and clinical characteristics. Univariate survival analysis and Multivariate Cox regression analysis were also performed to analyze the correlation of clinical and pathological factors with tumor recurrence after LT. The Kaplan-Meier method and log-rank test were used to analyze HCC-specific disease-free survival (DFS) rate.

Forty patients fulfilled Milan criteria with 1-, 2-, 3- and 5-years DFS of 86.7, 84.6, 84, 84%, respectively. The positive rates of YAP, Lats1/2, Mst1 in HCC were 51.4, 45.7, 64.8%, respectively. YAP expression in HCC tumors was significantly associated with tumor size (p = 0.041), venous infiltration (p = 0.002), AJCC tumor stage (p = 0.027). Lats1/2 expression was significantly associated with tumor size (p = 0.001) and AJCC tumor stage (p = 0.019). Mst1 expression was also significantly associated with tumor size (p = 0.042). HCC-specific DFS was significantly longer for patients with YAP negative expression compared with patients with YAP positive expression (1-, 2-, 3- and 5-years DFS of 71.7, 65.3, 65.3, 65.3 vs. 42.5, 36.6, 32.5, 30.4%, respectively, log-rank = 12.89, p < 0.001). Multivariate Cox regression analysis indicated that YAP expression (HR = 2.011, p = 0.020) in HCC was an independent prognostic factor for HCC-specific DFS after liver transplantation.

YAP is an independent prognostic marker for tumor recurrence for HCC patients after liver transplantation.