Gene Expression Profiling of Different Huh7 Variants Reveals Novel Hepatitis C Virus Host Factors

Chronic Hepatitis C virus (HCV) infection still constitutes a major global health problem with almost half a million deaths per year. To date, the human hepatoma cell line Huh7 and its derivatives is the only cell line that robustly replicates HCV. However, even different subclones and passages of this single cell line exhibit tremendous differences in HCV replication efficiency. By comparative gene expression profiling using a multi-pronged correlation analysis across eight different Huh7 variants, we identified 34 candidate host factors possibly affecting HCV permissiveness. For seven of the candidates, we could show by knock-down studies their implication in HCV replication. Notably, for at least four of them, we furthermore found that overexpression boosted HCV replication in lowly permissive Huh7 cells, most prominently for the histone-binding transcriptional repressor THAP7 and the nuclear receptor NR0B2. For NR0B2, our results suggest a finely balanced expression optimum reached in highly permissive Huh7 cells, with even higher levels leading to a nearly complete breakdown of HCV replication, likely due to a dysregulation of bile acid and cholesterol metabolism. Our unbiased expression-profiling approach, hence, led to the identification of four host cellular genes that contribute to HCV permissiveness in Huh7 cells. These findings add to an improved understanding of the molecular underpinnings of the strict host cell tropism of HCV.

THAP7 promotes cell proliferation by regulating the G1/S phase transition via epigenetically silencing p21 in lung adenocarcinoma

PURPOSE

Lung adenocarcinoma (LUAD) is one of the most common cancers worldwide. The THanatos-Associated Proteins (THAP) family plays an essential role in multiple cancers. However, the role of THAP7 in cancers has remained elusive.

METHODS

THAP7 expression status in LUAD tissues was analysed by using the Oncomine database and qRT-PCR, and its expression level in LUAD cell lines was detected by qRT-PCR and Western blotting. The role of THAP7 in LUAD cells was determined by proliferation, colony formation, and cell cycle analyses. In vivo role of THAP7 was studied on xenograft models. Luciferase reporter assays and chromatin immunoprecipitation (ChIP) were used to determine the activity and acetylation of the p21 promoter.

RESULTS

THAP7 expression was increased in LUAD tissues and cell lines. Moreover, the high expression of THAP7 was correlated with poor prognosis. The overexpression of THAP7 accelerated the G1/S phase transition and promoted tumour growth both in vitro and in vivo. A mechanistic study revealed that THAP7 reduced the acetylation of histone H3 on the p21 promoter to suppress p21 transcription.

CONCLUSION

For the first time, we demonstrated the function of THAP7 in LUAD, and our findings suggested that THAP7 may be a potential molecular therapy target in LUAD.