High Nuclear NADPH Oxidase 4 Expression Levels Are Correlated with Cancer Development and Poor Prognosis in Hepatocellular Carcinoma = High Nuclear NADPH Oxidase 4 Expression Levels Are Correlated with Cancer Development and Poor Prognosis in Hepatocellular Carcinoma

다국어 초록 (Multilingual Abstract)

Aims: Hepatocellular carcinoma (HCC) is typically associated with prolonged inflammation in the cirrhotic liver, which results in the transition from chronic inflammation and fibrosis to dysplastic or regenerative nodules or HCC. As we previously reported, the expression of NOX4 in HCC is the highest compared to paired control tissues and the expression of NOX2 is the highest among NOX family genes in HCC. However, our understanding of the association of NOX2 or NOX4 expression with clinicopathological values in HCC is limited. Our study aimed to investigate correlation NOX2 and NOX4 expression levels with clinicopathological factors of HCC patients.
Methods: A total of 134 matched tissue pairs of HCC cells and non-tumor hepatocytes from HCC patients were examined by immunohistochemical staining. Through these analysis, we tried to find the association of NOX2 and NOX4 expression with multiple clinicopathological parameters. Moreover, Immunoblotting in 4 HCC cell lines (HepG2, Hep3B, Huh-7, and SK-Hep-1) and reverse transcription digital droplet polymerase chain reaction (RT-ddPCR) in 20 pairs of HCC and non-tumor tissue samples were also performed to detect NOX4.
Results: Cytoplasmic NOX2 and nuclear NOX4 expression levels were shown by immunohistochemistry to be higher in HCC cells than in nontumor hepatocytes (P<0.001, each). The Western blotting results for NOX4 in 4 HCC cell lines were consistent with the immunohistochemical results. Increased cytoplasmic expression of NOX2 and NOX4 was significantly correlated with liver cirrhosis (P<0.001 and P<0.031, respectively). However, decreased cytoplasmic expression of NOX2 and NOX4 was significantly correlated with advanced pathologic TNM stage (P<0.029 and P<0.007, respectively). Multivariate analysis with clinicopathologic parameters showed that high nuclear and low cytoplasmic NOX4 expression levels are correlated with short overall survival (P=0 .021). Our findings imply that cytoplasmic NOX2 and nuclear NOX4 expression is upregulated during HCC development.
Conclusions: In particular, NOX4 translocation into the nucleus may affect the development and progression of HCC. NOX2 and NOX4 could be diagnostic markers and have therapeutic implications in HCC.