Background and aim: The transcriptional co-activator Yes-associated protein-1 (YAP1) has been implicated as an oncogene and is overexpressed in different kinds of human cancers, especially hepatocellular carcinoma (HCC). However, the role of YAP1 has not been reported in residual/recurrent HCC after transarterial chemoembolization (TACE). Our aim is to determine whether YAP1 is overexpressed in the residual/recurrent HCC after TACE.
Methods: A total of 105 tumor tissues from 71 patients including 30 cases of primary HCC without prior treatment, 35 cases of residual/recurrent HCC post TACE, and 6 cases of hepatoblastoma were included in the immunohistochemical study. YAP1 immunoreactivity was blindly scored as 0, 1+, 2+ or 3+ in density and percentages of positive cells.
Results: About 33.3% (10/30) of primary HCC without prior treatment showed 2+ of YAP1 immunoreactivity. While 82.8% (29/35) of residual/recurrent HCCs after TACE treatment displayed 2-3+ of YAP1 immunoreactivity, which was significantly higher compared to primary HCC without prior treatment (P = 0.0002). YAP1 immunoreactivity was moderately to strongly positive (2-3+) in 100% of the hepatoblastoma, particularly in the embryonal components (3+ in 100% cases).
Conclusions: YAP1 is significantly upregulated in the residual/recurrent HCCs post TACE treatment, suggesting that YAP1 may serve as a sensitive diagnostic marker and a treatment target for residual/recurrent HCC post TACE.
Keywords: Cancer stem cell (CSC); Hepatoblastoma; Immunohistochemistry; Residual/recurrent hepatocellular; Transarterial chemoembolization (TACE); Yes-associated protein-1 (YAP1); carcinoma.