Binghua Dai

Understanding differences in DNA double-strand break (DSB) repair between tumor and normal tissues would provide a rationale for developing DNA repair-targeted cancer therapy. Here, using knock-in mouse models for measuring the efficiency of two DSB repair pathways, homologous recombination (HR) and nonhomologous end-joining (NHEJ), we demonstrated that both pathways are up-regulated in hepatocellular carcinoma (HCC) compared with adjacent normal tissues due to altered expression of DNA repair factors, including PARP1 and DNA-PKcs. Surprisingly, inhibiting PARP1 with olaparib abrogated HR repair in HCC. Mechanistically, inhibiting PARP1 suppressed the clearance of nucleosomes at DNA damage sites by blocking the recruitment of ALC1 to DSB sites, thereby inhibiting RPA2 and RAD51 recruitment. Importantly, combining olaparib with NU7441, a DNA-PKcs inhibitor that blocks NHEJ in HCC, synergistically suppressed HCC growth in both mice and HCC patient-derived-xenograft models. Our results suggest the combined inhibition of both HR and NHEJ as a potential therapy for HCC. Significance Hepatocellular carcinoma (HCC) is the sixth most common type of cancer, and its mortality rate continues to increase. We generated knock-in reporter mouse models for measuring DNA double-strand break (DSB) repair efficiency and demonstrated that both DSB repair pathways are up-regulated in mouse HCCs. We then found that activation of PARP1 and DNA-PKcs is critical to HCC survival bothin vitro and in vivo. Targeting the two proteins to block both DSB repair pathways by combining olaparib and NU7441 synergistically inhibits HCC growth in both orthotopic HCC mouse and human PDX models. Our work not only establishes versatile tools for in vivo analysis of DNA repair, but also implies an effective combination therapy for HCC.

Background: Thousands of long non-coding RNAs (lncRNAs) have been functionally verified as crucial regulators of physiological processes and disease progressions, yet their roles in hepatocellular carcinoma (HCC) have not been clearly illuminated. Methods: We analyzed the expression of lncRNA-SNHG14 in TCGA data via bioinformatic analysis and detected its expression in HCC specimens by reverse transcription‐quantitative polymerase chain reaction (RT‐qPCR). Loss-of-function experiments were used to study the biological function of SNHG14 in HCC cells. RT-qPCR, Western blotting and dual-luciferase reporter assay were carried out to investigate the molecular mechanism of SNHG14 in HCC. Results: The upregulation of lncRNA-SNHG14 was observed in HCC tissues compared with normal tissues via RT-qPCR and bioinformatic analysis of TCGA data. Silencing of SNHG14 inhibited cell proliferation and induced cell apoptosis in HCC cells. microRNA-217 (miR-217), the tumor-suppressive miRNA in HCC, was predicted and confirmed as a miRNA sponged by SNHG14 in HCC cells. Via downregulation of miR-217, SNHG14 increased the expression of several miR-217-related oncogenes and subsequently activated oncogene-related signaling pathways in HCC cells. In addition, inhibition of miR-217 reversed SNHG14 silencing induced decrease of cell proliferation and increase of cell apoptosis. Their association was verified in the published microarray dataset and the collected HCC samples. Conclusion: In summary, SNHG14 is involved in the development of HCC via sponging miR-217 and it may be a biomarker for patients with HCC.

Hepatic ischemia-reperfusion injury (IRI) is a very complex pathological process that is often associated with liver trauma and surgery, especially liver transplantation surgery. Although endoplasmic reticulum stress (ERS) plays a role in this process, the posttranscriptional regulators and the underlying mechanisms are still unclear. Here, we report that the lncRNA AK054386 was increased in hepatic IRI models. Furthermore, AK054386 can act as a “competing endogenous RNA (ceRNA)” and regulate ERS-related factors by binding and sequestering miR-199, which was shown to inhibit ERS in our previous report. Increased expression of AK054386, which might be mediated by activated NF-κB, resulted in sustained ERS and increased cell apoptosis and death in hepatic IRI mouse and cellular models. In contrast, AK054386 inhibition had protective effects on these models. Our data indicate that AK054386 and miR-199 are critical players in hepatic IRI, and we broadened the scope regarding ceRNA mechanisms. We hope that our results will improve the understanding of hepatic IRI and may provide potential therapeutic targets.

Background: Hepatocellular carcinoma (HCC) is a malignancy with poor prognosis. Complex genetic and epigenetic alterations are the two primary causes of HCC. The aim of the study was mainly to explore the correlation between the methylation status of DNAH17 and HCC.Methods: We evaluated the methylation levels of DNAH17 in 163 HCC samples and their paired normal tissue using Sequenom EpiTYPER assays and performed the TaqMan copy number assay to assess the copy number status of DNAH17 in HCC samples.Results: The mean methylation levels were significantly decreased in the tumor tissues compared to the paired normal tissues in both selected regions of DNAH17 (amplicon 1:58.7% vs 84.5%, P < 0.0001; amplicon 2:69.9% vs 84.5%, P = 0.0060). Contrarily，both RNA‐seq and immunohistochemistry indicated the expression of DNAH17 was increased in tumor tissues (P < 0.05). DNMT inhibitor decitabine treatment could increase the expression of DNAH17 in HCC cell lines. DNAH17 gene amplification always companied with hypomethylation status. Moreover, hypomethylation status was associated with several clinical characteristics, such as male patients, higher AFP values, higher age of onset, fibrous capsules, tumor necrosis, liver cirrhosis, and tumor thrombus (P < 0.05). Receiver operator characteristic (ROC) curve analysis demonstrated the methylation levels of DNAH17 could efficiently predict the existence of the fibrous capsule (AUC = 0.695) and tumor thrombus (AUC = 0.806).Conclusions: These findings suggested that aberrant methylation of DNAH17 was associated with comprehensive HCC clinicopathological factors and could be a promising biomarker for tumor thrombosis in HCC patients.

The liver is the most common site of metastasis in patients with colorectal cancer, and colorectal cancer liver metastasis (CRLM) is associated with poor rates of survival. However, CRLM occurs infrequently in livers exhibiting signs of hepatitis or cirrhosis, suggesting a role for inflammation in attenuating CRLM. The molecular mechanisms driving this phenomenon remain unclear. The aim of this study was to confirm the mechanism by which liver inflammation inhibits CRLM. We used BALB/c animal models of inflammatory liver diseases to confirm that liver inflammation inhibits CRLM, and then elucidated the molecular mechanisms governing that process. Out data showed that liver inflammation induces IFN-γ expression, which then downregulates expression of the let-7a cluster through IRF-1 in colorectal cancer cells. Finally, we showed that modulation of let-7a expression regulated the epithelial–mesenchymal transition in colorectal cancer cell lines, and inhibited their capacity to metastasize in vivo. Cumulatively, we clarified the critical role played by the IFN-γ/IRF-1/let-7a cluster/EMT pathway in regulating the spread of circulating colorectal cancer cells to the liver, and highlighted the critical role that the hepatitis microenvironment plays in modulating that process.

Hepatocellular carcinoma (HCC) is the seventh most common type of cancer; notably, the incidence of HCC is four to eight times higher in men than women. Previous studies reported that the estrogen receptor (ER) signaling pathway is involved in the pathogenesis of HCC, although the extent of its involvement is unclear due to several conflicting reports. In the present study, tumor and paired adjacent non-cancerous tissues from 157 HCC patients were collected. Transcriptome sequencing and real-time quantitative polymerase chain reaction were used to quantify the ER α (ESR1) expression levels, and the Sequenom EpiTYPER assay was used to delineate the methylation patterns in the ESR1 promoter. We found that ESR1 expression was significantly reduced in tumor tissues ( P < 0.001) compared to adjacent non-cancerous tissues. The CpG sites around the transcription start site were significantly hypermethylated in the tumor ( P < 0.0001). This methylation pattern also correlated with the gene expression ( P < 0.0001). Additionally, we found that the hypermethylation of ESR1 was associated with the presence of fibrous capsules ( P = 1.2 × 10⁻⁴), the absence of microvascular invasions ( P = 8.0 × 10⁻⁴), thin trabecular pattern ( P = 0.025), and lower histologic gradings ( P = 5.2 × 10⁻³). Thus, ESR1 expression is a candidate tumor suppressor gene in HCC. Further, promoter hypermethylation may be a mechanism by which expression of ESR1 is repressed, and the extent of hypermethylation of ESR1 may be a marker for HCC status and progression.

Sustained endoplasmic reticulum (ER) stress has been linked to cell death and the pathogenesis of many liver diseases, including toxic liver, cholestasis, and infectious liver disease. The cellular pathways that attenuate hepatic ER stress have been the focus of many recent studies, but the role of microRNAs (miRNA) in this process remains unknown. Here, we report that one of the most abundant miRNAs in hepatocytes, miR-199a-5p, was elevated in both bile acid- and thapsigargin (TG)-stimulated cultured hepatocytes, as well as in the liver of bile duct-ligated mice. We identify the misfolded protein chaperone GRP78, as well as the unfolded protein response transducers endoplasmic reticulum to nucleus signaling 1 and activating transcription factor 6 as direct targets of miR-199a-5p, and show that endogenous miR-199a-5p represses the 3′ untranslated regions (UTRs) of their mRNAs. Through gain-of-function and loss of function approaches, we demonstrate that the elevated miR-199-5p disrupts sustained ER stress and prevents hepatocytes from undergoing bile acid- or TG-induced cell death. Furthermore, we reveal that the transcription factor AP-1 is a strong positive regulator of miR-199a-5p. In brief, our study demonstrates that AP-1/miR-199a-5p and ER stress mediators form a feedback loop, which shields hepatocytes from sustained ER stress and protects the liver from injury. On the basis of these findings, we also suggest that the miRNA miR-199a-5p is a potential target for clinical approaches aiming to protect hepatocytes in liver disease.