Hepatocellular Carcinoma (HCC) is the most frequent malignant tumor of the liver, but its prognosis is poor. Histone acetylation is an important epigenetic regulatory mode that modulates chromatin structure and transcriptional status to control gene expression in eukaryotic cells. Generally, histone acetylation and deacetylation processes are controlled by the opposing activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Dysregulation of histone modification is reported to drive aberrant transcriptional programmes that facilitate liver cancer onset and progression. Emerging studies have demonstrated that several HDAC inhibitors exert tumor-suppressive properties via activation of various cell death molecular pathways in HCC. However, the complexity involved in the epigenetic transcription modifications and non-epigenetic cellular signaling processes limit their potential clinical applications. This review brings an in-depth view of the oncogenic mechanisms reported to be related to aberrant HCC-associated histone acetylation, which might provide new insights into the effective therapeutic strategies to prevent and treat HCC.
Background
Hepatic ischemia-reperfusion injury (IRI) is considered as an effecting factor for hepatocellular carcinoma (HCC) recurrence. Th17/Treg cells are a pair of essential components in adaptive immune response in liver IRI, and forkhead box O1 (FOXO1) has the properties of maintaining the function and phenotype of immune cells. Herein, we illuminated the correlation and function between Th17/Treg cell balance and FOXO1 in IRI-induced HCC recurrence.
Methods
RNA sequencing was performed on naive CD4+ T cells from normal and IRI model mice to identify relevant transcription factors. Western blotting, qRT-PCR, immunohistochemical staining, and flow cytometry were performed in IRI models to indicate the effect of FOXO1 on the polarization of Th17/Treg cells. Then, transwell assay of HCC cell migration and invasion, clone formation, wound healing assay, and Th17 cells adoptively transfer was utilized to assess the function of Th17 cells in IRI-induced HCC recurrence in vitro and in vivo.
Results
Owning to the application of RNA sequencing, FOXO1 was screened and assumed to perform a significant function in hepatic IRI. The IRI model demonstrated that up-regulation of FOXO1 alleviated IR stress by attenuating inflammatory stress, maintaining microenvironment homeostasis, and reducing the polarization of Th17 cells. Mechanistically, Th17 cells accelerated IRI-induced HCC recurrence by shaping the hepatic pre-metastasis microenvironment, activating the EMT program, promoting cancer stemness and angiogenesis, while the upregulation of FOXO1 can stabilize the liver microenvironment homeostasis and alleviate the negative effects of Th17 cells. Moreover, the adoptive transfer of Th17 cells in vivo revealed its inducing function in IRI-induced HCC recurrence.
Conclusions
These results indicated that FOXO1-Th17/Treg axis exerts a crucial role in IRI-mediated immunologic derangement and HCC recurrence, which could be a promising target for reducing the HCC recurrence after hepatectomy.
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