Gene expression evaluation of antioxidant enzymes in patients with hepatocellular carcinoma: RT-qPCR and bioinformatic analyses.

Andressa De Freitas Alves,Ana Carolina De Moura,Ana Beatriz Gorini Da Veiga,Silvana Almeida,Márcia Giovenardi,Huander Felipe Andreolla,Marilu Fiegenbaum

doi:10.1590/1678-4685-gmb-2019-0373

Abstract

Any condition leading to chronic liver disease is a potential oncogenic agent for hepatocellular carcinoma (HCC). Alterations in the expression of antioxidant enzymes could alter the redox balance. Our aim was to evaluate the expression of the genes GPX1, GPX4, SEP15, SELENOP, SOD1, SOD2, GSR, CAT, and NFE2L2 in patients with HCC. Differential gene expression analysis was performed using RNA-Seq data from the TCGA and GTEx databases, and RT-qPCR data from HCC patient samples. Bioinformatic analysis revealed significant differential expression in most genes. GPX4 expression was significantly increased (p=0.02), while SOD2 expression was significantly decreased (p=0.04) in experimental data. In TCGA samples, alpha-fetoprotein levels (mg/dL) were negatively correlated with the expression of SEP15 (p<0.001), SELENOP (p<0.001), SOD1 (p<0.001), SOD2 (p<0.001), CAT (p<0.001), and NFE2L2 (p=0.004). Alpha-fetoprotein levels were positively correlated with the expression of GPX4 (p=0.02) and SELENOP (p=0.01) in the experimental data. Low expression of GPX1 (p=0.006), GPX4 (p=0.01), SELENOP (p=0.006), SOD1 (p=0.007), CAT (p<0.001), and NFE2L2 (p<0.001), and higher levels of GSR, were associated with low overall survival at 12 months. These results suggest a significant role for these antioxidant enzymes in HCC pathogenesis and severity.

Highlights

Hepatocellular carcinoma (HCC) has a high mortality rate, and ranks as the third leading cause of cancer deaths worldwide (Ozakyol, 2017; Forner et al, 2018)
A number of differentially expressed genes were identified in tumoral samples from The Cancer Genome Atlas (TCGA) patients (Figure 1A, B), along with replication of two genes in the experimental data (Figure 1C, D)
Some studies evaluated the expression of the genes for these antioxidant enzymes separately in HCC tumoral samples, HepG2 and Huh7 cell lines (Table 1)

Summary

Introduction

Hepatocellular carcinoma (HCC) has a high mortality rate, and ranks as the third leading cause of cancer deaths worldwide (Ozakyol, 2017; Forner et al, 2018). Major risk factors for HCC include infection with hepatitis B and C viruses, alcohol intake, and fatty liver disease (Ozakyol, 2017; Yang et al, 2019). Prognosis and treatment options vary according to tumor stage and liver function. The percentage of patients eligible for curative treatment varies between high and low-resource countries (Ozakyol, 2017; Yang et al, 2019), but generally fluctuates between 20-30% of patients. The median survival of patients with untreated disease is nine months (Klungboonkrong et al, 2017; Forner et al, 2018). New markers or therapeutic targets are required for early diagnosis, and the development of novel treatment strategies for HCC (Klungboonkrong et al, 2017)

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