Emerging functions of mitochondria-encoded noncoding RNAs.

Mitochondria, organelles that harbor their own circular genomes, are critical for energy production and homeostasis maintenance in eukaryotic cells. Recent studies discovered hundreds of mitochondria-encoded noncoding RNAs (mt-ncRNAs), including novel subtypes of mitochondria-encoded circular RNAs (mecciRNAs) and mitochondria-encoded double-stranded RNAs (mt-dsRNAs). Here, we discuss the emerging field of mt-ncRNAs by reviewing their expression patterns, biogenesis, metabolism, regulatory roles, and functional mechanisms. Many mt-ncRNAs have regulatory roles in cellular physiology, and some are associated with, or even act as, causal factors in human diseases. We also highlight developments in technologies and methodologies and further insights into future perspectives and challenges in studying these noncoding RNAs, as well as their potential biomedical applications.

Cytoskeleton remodeling mediated by circRNA-YBX1 phase separation suppresses the metastasis of liver cancer.

Metastasis, especially intrahepatic, is a major challenge for hepatocellular carcinoma (HCC) treatment. Cytoskeleton remodeling has been identified as a vital process mediating intrahepatic spreading. Previously, we reported that HCC tumor adhesion and invasion were modulated by circular RNA (circRNA), which has emerged as an important regulator of various cellular processes and has been implicated in cancer progression. Here, we uncovered a nuclear circRNA, circASH2, which is preferentially lost in HCC tissues and inhibits HCC metastasis by altering tumor cytoskeleton structure. Tropomyosin 4 (TPM4), a critical binding protein of actin, turned out to be the major target of circASH2 and was posttranscriptionally suppressed. Such regulation is based on messenger RNA (mRNA)/precursormRNA splicing and degradation process. Furthermore, liquid-liquid phase separation of nuclear Y-box binding protein 1 (YBX1) enhanced by circASH2 augments TPM4 transcripts decay. Together, our data have revealed a tumor-suppressive circRNA and, more importantly, uncovered a fine regulation mechanism for HCC progression.

Cancer-derived exosomes as novel biomarkers in metastatic gastrointestinal cancer.

Gastrointestinal cancer (GIC) is the most prevalent and highly metastatic malignant tumor and has a significant impact on mortality rates. Nevertheless, the swift advancement of contemporary technology has not seamlessly aligned with the evolution of detection methodologies, resulting in a deficit of innovative and efficient clinical assays for GIC. Given that exosomes are preferentially released by a myriad of cellular entities, predominantly originating from neoplastic cells, this confers exosomes with a composition enriched in cancer-specific constituents. Furthermore, exosomes exhibit ubiquitous presence across diverse biological fluids, endowing them with the inherent advantages of non-invasiveness, real-time monitoring, and tumor specificity. The unparalleled advantages inherent in exosomes render them as an ideal liquid biopsy biomarker for early diagnosis, prognosticating the potential development of GIC metastasis.In this review, we summarized the latest research progress and possible potential targets on cancer-derived exosomes (CDEs) in GIC with an emphasis on the mechanisms of exosome promoting cancer metastasis, highlighting the potential roles of CDEs as the biomarker and treatment in metastatic GIC.

HBV PreC interacts with SUV39H1 to induce viral replication by blocking the proteasomal degradation of viral polymerase.

Hepatitis B e antigen (HBeAg) seropositivity during the natural history of chronic hepatitis B (CHB) is known to coincide with significant increases in serum and intrahepatic HBV DNA levels. However, the precise underlying mechanism remains unclear. In this study, we found that PreC (HBeAg precursor) genetic ablation leads to reduced viral replication both in vitro and in vivo. Furthermore, PreC impedes the proteasomal degradation of HBV polymerase, promoting viral replication. We discovered that PreC interacts with SUV39H1, a histone methyltransferase, resulting in a reduction in the expression of Cdt2, an adaptor protein of CRL4 E3 ligase targeting HBV polymerase. SUV39H1 induces H3K9 trimethylation of the Cdt2 promoter in a PreC-induced manner. CRISPR-mediated knockout of endogenous SUV39H1 or pharmaceutical inhibition of SUV39H1 decreases HBV loads in the mouse liver. Additionally, genetic depletion of Cdt2 in the mouse liver abrogates PreC-related HBV replication. Interestingly, a negative correlation of intrahepatic Cdt2 with serum HBeAg and HBV DNA load was observed in CHB patient samples. Our study thus sheds light on the mechanistic role of PreC in inducing HBV replication and identifies potential therapeutic targets for HBV treatment.

Repeat laparoscopic liver resection after an initial open hepatectomy.

BACKGROUND: Repeat open hepatectomy (ROH) for recurrent liver tumors is the preferred approach especially after initial open hepatectomy (OH). The aim of this study is to assess feasibility and safety of repeat laparoscopic hepatectomy (RLH) after initial OH in 2 high volume hepato-biliary hospitals. METHODS: Patients were retrieved from prospective data bases from 2012 to 2020. The patients were divided into two groups according to the approach used for repeat hepatectomy, ROH and RLH groups. RESULTS: Sixty-seven patients matched the criteria, 20 in RLH and 47 in ROH. Diagnoses were hepatocellular carcinoma in 52.3%, intrahepatic cholangiocarcinoma in 7.7% and colorectal liver metastases in 40%. Median operative time and blood loss were lower in RLH (199 vs 260 min, and 100 vs 400 ml respectively), as well as overall postoperative complications (20% vs 49%). There were 2 conversions (10%) due to adhesions and one died of postoperative pancreatitis in RLH. Median hospital stay was lower in RLH (5 vs 9 days). CONCLUSION: RLH is a feasible, safe technique and a realistic option to be considered in selected patients after previous OH. Early conversion should be considered when adhesions are more severe than expected.

iPS-derived neural stem cells for disease modeling and evaluation of therapeutics for mucopolysaccharidosis type II.

Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a rare, lysosomal disorder caused by mutations in a gene encoding iduronate-2-sulfatase (IDS). IDS deficiency results in an accumulation of glycosaminoglycans (GAGs) and secondary accumulations of other lipids in lysosomes. Symptoms of MPS II include a variety of soft and hard tissue problems, developmental delay, and deterioration of multiple organs. Enzyme replacement therapy is an approved treatment for MPS II, but fails to improve neuronal symptoms. Cell-based neuronal models of MPS II disease are needed for compound screening and drug development for the treatment of the neuronal symptoms in MPS II. In this study, three induced pluripotent stem cell (iPSC) lines were generated from three MPS II patient-derived dermal fibroblast cell lines that were differentiated into neural stem cells and neurons. The disease phenotypes were measured using immunofluorescence staining and Nile red dye staining. In addition, the therapeutic effects of recombinant human IDS enzyme, delta-tocopherol (DT), and hydroxypropyl-beta-cyclodextrin (HPBCD) were determined in the MPS II disease cells. Finally, the neural stem cells from two of the MPS II iPSC lines exhibited typical disease features including a deficiency of IDS activity, abnormal glycosaminoglycan storage, and secondary lipid accumulation. Enzyme replacement therapy partially rescued the disease phenotypes in these cells. DT showed a significant effect in reducing the secondary accumulation of lipids in the MPS II neural stem cells. In contrast, HPBCD displayed limited or no effect in these cells. Our data indicate that these MPS II cells can be used as a cell-based disease model to study disease pathogenesis, evaluate drug efficacy, and screen compounds for drug development.

Interplay between liver circadian rhythm and regeneration after PHx.

Diurnal oscillations in gene expression are a hallmark of the liver internal clock and can be regulated by a variety of environmental stimuli. The circadian rhythm and liver regeneration (LR) are intimately linked. However, how they affect each other at the transcriptomic level is mainly unknown. Here, we revealed that partial hepatectomy (PHx)-induced LR led to reprogramming of rhythmic gene expression profiles as a consequence of disrupted BMAL1 occupation on the chromatin, while the rhythm of core clock genes remained robust. Furthermore, we demonstrated retarded LR when PHx was carried out in the evening, possibly due to the accumulation of DEC1. In summary, our data offer a broad perspective of the relationship between circadian rhythm and LR and suggest that the timing of PHx should be considered in the clinic application.

Isoalantolactone suppresses gallbladder cancer progression via inhibiting the ERK signalling pathway.

CONTEXT: Gallbladder cancer (GBC) is the most common malignant tumour of the biliary tract. Isoalantolactone (IAL), an active sesquiterpene lactone compound isolated from the roots of Inula helenium L. (Asteraceae), has antitumour effects. OBJECTIVE: This study investigates the effects of IAL on GBC. MATERIALS AND METHODS: In vitro, NOZ and GBC-SD cells were treated with IAL (0, 10, 20 and 40 µM) for 24 h. The DMSO-treated cells were selected as a control. Cell proliferation, migration, invasion and apoptosis were measured by the CCK-8 assay, transwell assay, flow cytometry and western blot. In vivo, subcutaneous tumour xenografts were constructed by injecting nude mice (BALB/C) with 5 × 106 NOZ cells. Mice were divided into the control group (equal amount of DMSO), the IAL group (10 mg/kg/day) and the IAL + Ro 67-7476 group (IAL, 10 mg/kg/day; Ro 67-7476, 4 mg/kg/day). The study duration was 30 days. RESULTS: Compared with the DMSO group, cell proliferation of NOZ (IC50 15.98 µM) and GBC-SD (IC50 20.22 µM) was inhibited by about 70% in the IAL 40 µM group. Migration and invasion were suppressed by about 80%. Cell apoptosis rate was increased about three-fold. The phosphorylation level of ERK was decreased to 30-35%. Tumour volume and weight (about 80% reduction) were suppressed by IAL in vivo. Moreover, the effects of IAL were abolished by Ro 67-7476 in vitro and in vivo. DISCUSSION AND CONCLUSIONS: Our findings indicate that IAL could inhibit GBC progression in vitro and in vivo by inhibiting the ERK signalling pathway.

The potential of mecciRNA in hepatic stellate cell to regulate progression of nonalcoholic hepatitis.

BACKGROUND: Nonalcoholic steatohepatitis (NASH) occupies a substantial proportion of chronic liver disease worldwide, of which pathogenesis needs further research. Recent studies have demonstrated the significant roles of circular RNAs (circRNAs) in NASH, while the function of a novel type of circRNAs, namely mitochondria-encoded circRNAs (mecciRNAs), remains elusive. Therefore, we aimed to investigate their potential to regulate the progression of NASH in this study. METHODS: GSE134146 was used to screen for differentially expressed mecciRNAs in NASH, while GSE46300 was used to identify NASH-related genes. To establish the mecciRNA-miRNA-mRNA networks, circMINE and miRNet databases were used for predicting downstream targets. Then, consensus clustering analysis was used to determine immune subtypes of NASH. Finally, we successfully validated our findings in vitro (LPS-treated hepatic stellate cells [HSCs]) and in vivo (MCD-diet mice) NASH models. RESULTS: We confirmed that circRNomics balance is disrupted in HSCs of NASH, while two mecciRNAs (hsa_circ_0089761 and hsa_circ_0089763) could function as competing for endogenous RNAs (ceRNAs) to regulate fibrosis-related signals. Furthermore, we constructed two ceRNA networks based on mecciRNAs for the first time. Cell and animal NASH models validated our findings that c-MYC and SMAD2/3 were upregulated in HSCs, while THBS1 and p-STAT3 were upregulated in hepatocytes. Moreover, we identified 21 core genes by overlapping the differentially expressed genes (NASH vs. Normal) with mecciRNA-targeted genes. According to their expression profiles, NASH patients could be divided in 2 different clusters, in which proinflammatory signals (TNF and IL-17 pathways) are significantly activated in Cluster 1. CONCLUSION: We successfully established two novel mecciRNA-miRNA-mRNA networks in HSCs and hepatocytes, which were further confirmed by in vitro and in vivo models. Meanwhile, the novel immunotyping model revealed the heterogeneity of NASH, thereby might guiding treatment options. Altogether, our study brought a distinct perspective on the relationship between mecciRNAs and NASH.

Identification of invasion-metastasis associated MiRNAs in gallbladder cancer by bioinformatics and experimental validation.

BACKGROUND: Recent studies exploring the roles of invasion-metastasis associated miRNAs in gallbladder cancer (GBC) are limited. In the study, we aimed to identify the invasion-metastasis associated miRNAs in GBC by bioinformatics and experimental validation. METHODS: MiRNAs of different expression were identified by comparing GBC tumor samples with different survival from Gene Expression Omnibus database. MiRTarBase was used for identifying the potential target genes of miRNAs. Then, we performed Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. And miRNA-gene and protein-protein interaction (PPI) network were constructed for hub genes evaluation. We further explored and compared miR-642a-3p and miR-145-5p expression in both The Cancer Genome Atlas database and our hospital data. Finally, quantitative real-time PCR, wound healing assay, and Transwell assay were conducted to validate the invasion-metastasis associated miRNAs in GBC. RESULTS: In GSE104165 database, 25 up-regulated and 97 down-regulated miRNAs were detected with significantly different expression in GBC tumor samples. Then, 477 potential target genes were identified from the 2 most up-regulated miRNAs (miR-4430 and miR-642a-3p) and 268 genes from the 2 most down-regulated miRNAs (miR-451a and miR-145-5p). After GO and KEGG analysis, mTOR and PI3K-Akt signaling pathways were found associated with the potential target genes. Based on PPI network, the top 10 highest degree hub nodes were selected for hub genes. Furthermore, the miRNA-hub gene network showed significant miR-642a-3p up-regulation and miR-145-5p down-regulation in both GBC tissues and cell lines. In the experimental validation, miR-145-5p up-regulation and miR-642a-3p down-regulation were confirmed to suppress GBC invasion and metastasis. CONCLUSIONS: MiR-642a-3p and miR-145-5p were identified as invasion-metastasis associated miRNAs via bioinformatics and experimental validation, and both up-regulation of miR-642a-3p and down-regulation of miR-145-5p would be served as novel treatment options for GBC in the future.

Inhibition of AMPK/PFKFB3 mediated glycolysis synergizes with penfluridol to suppress gallbladder cancer growth.

BACKGROUND: Penfluridol (PF) is an FDA-approved antipsychotic drug that has recently been shown to have anticancer activity. However, the anticancer effects and underlying mechanisms of PF are not well-established in gallbladder cancer (GBC). METHODS: The anticancer efficacy of PF on GBC was investigated via a series of cell functions experiments, including cell viability, colony formation, apoptosis assays, and so on. The corresponding signaling changes after PF treatment were explored by western blotting. Then, nude mice were utilized to study and test the anticancer activity of PF in vivo. Besides, glucose consumption and lactic production assays were used to detect the glycolysis alteration. RESULTS: In this study, we discovered that PF greatly inhibited the proliferation and invasion ability of GBC cells (GBCs). The glucose consumption and lactic generation ability of GBCs were dramatically elevated following PF treatment. Additionally, we discovered that inhibiting glycolysis could improve PF's anticancer efficacy. Further studies established that the activation of the AMPK/PFKFB3 signaling pathway medicated glycolysis after PF treatment. We proved mechanistically that inhibition of AMPK/PFKFB3 singling pathway mediated glycolysis was a potential synergetic strategy to improve the anticancer efficacy of PF on GBC. CONCLUSIONS: By inhibiting AMPK, the anticancer effects of PF on GBCs were amplified. As a result, our investigations shed new light on the possibility of repurposing PF as an anticancer drug for GBC, and AMPK inhibition in combination with PF may represent a novel therapeutic strategy for GBC. Video abstract.

Liver growth prediction in ALPPS - A multicenter analysis from the international ALPPS registry.

BACKGROUND: While ALPPS triggers a fast liver hypertrophy, it is still unclear which factors matter most to achieve accelerated hypertrophy within a short period of time. The aim of the study was to identify patient-intrinsic factors related to the growth of the future liver remnant (FLR). METHODS: This cohort study is composed of data derived from the International ALPPS Registry from November 2011 and October 2018. We analyse the influence of demographic, tumour type and perioperative data on the growth of the FLR. The volume of the FLR was calculated in millilitre and percentage using computed-tomography (CT) scans before and after stage 1, both according to Vauthey formula. RESULTS: A total of 734 patients were included from 99 centres. The median sFLR at stage 1 and stage 2 was 0.23 (IQR, 0.18-0.28) and 0.39 (IQR: 0.31-0.46), respectively. The variables associated with a lower increase from sFLR1 to sFLR2 were age˃68 years (p = .02), height ˃1.76 m (p ˂ .01), weight ˃83 kg (p ˂ .01), BMI˃28 (p ˂ .01), male gender (p ˂ .01), antihypertensive therapy (p ˂ .01), operation time ˃370 minutes (p ˂ .01) and hospital stay˃14 days (p ˂ .01). The time required to reach sufficient volume for stage 2, male gender accounts 40.3% in group ˂7 days, compared with 50% of female, and female present 15.3% in group ˃14 days compared with 20.6% of male. CONCLUSIONS: Height, weight, FLR size and gender could be the variables that most constantly influence both daily growths, the interstage increase and the standardized FLR before the second stage.

A stent-based diverting technique after low anterior resection of rectal cancer: our preliminary experience.

BACKGROUND: Anastomotic leakage (AL) is a severe complication of rectal cancer low anterior resection (LAR). Ileostomy, the most common method to reduce the severity of AL, is associated with the risk of permanent stoma and an additional operation for stoma reversal. This purpose of this study is to develop a novel protective technique called the stent-based diverting technique (SDT) to protect the anastomosis following LAR. METHODS: From March 2020 to December 2020, thirty-four patients treated with LAR followed by SDT were enrolled prospectively at Sir Run Run Shaw Hospital. Demographic characteristics, laboratory test results, surgical outcomes, and oncological features were recorded. RESULTS: Overall, the median period of stent degradation was 21 (18-24) days. One patient (2.9%) had anastomotic leakage, and another patient (2.9%) had intestinal obstruction, while no other complications (e.g., intestinal volvulus, perforation, fistula) were observed in this study. CONCLUSIONS: The unique SDT may be a novel approach to prevent anastomotic leakage following low anterior resection of rectal cancer.

Risk factors and consequences of conversion in minimally invasive distal pancreatectomy.

Background: Although recent studies have reported potential benefits of laparoscopic approach in distal pancreatectomy, reports of conversion during minimally invasive distal pancreatectomy (MIDP) were limited. Methods: This was a retrospective study using data from Sir Run Run Shaw Hospital around May 2013 to December 2018. Outcomes of patients who had conversions during MIDP were compared with patients with successful MIDP and with patients undergoing open distal pancreatectomy (ODP). Results: Two-hundred and eighty-three cases were included in this study: 225 (79.5%) had MIDP, 30 (10.6%) had conversions and 28 (9.9%) had outpatient department. The risk factors for conversion included large lesion size (heart rates [HR]: 5.632, 95% confidencevinterval [CI]: 1.036-1.450, P = 0.018) and pancreatic cancer (HR: 6.957, 95% CI: 1.359-8.022, P = 0.009). Compared with MIDP, those who required conversion were associated with longer operations (P = 0.003), higher blood loss (P < 0.001) and more severe of the complications (P < 0.001). However, no statistically significant differences were found between the conversion group and ODP. Conclusions: Large lesion size and pancreatic cancer were reported to be independent risk factors for conversion during MIDP. As for post-operative outcomes, the outcomes of successfully MIDP were better than those for conversion. However, conversion did not lead to worsening outcomes when compared with ODP.

Olaparib and enzalutamide synergistically suppress HCC progression via the AR-mediated miR-146a-5p/BRCA1 signaling.

Hepatocellular carcinoma (HCC) is one of most common cancers worldwide, however, the treatment for advanced HCC remains unsatisfactory. We focused on the function of the androgen receptor (AR) in HCC and tried to find new treatment strategy based on antiandrogen enzalutamide (Enz). Here, we found that olaparib, a FDA-approved PARP inhibitor, could enhance the cytotoxicity in HCC cells with a lower BRCA1 expression, and suppressing the AR with either Enz or AR-shRNA could further increase the olaparib sensitivity to better suppress the HCC cell growth via a synergistic mechanism that may involve suppressing the expression of BRCA1 and other DNA damage response (DDR) genes. Mechanism studies revealed that Enz/AR signaling might transcriptionally regulate the miR-146a-5p expression via binding to the Androgen Response Elements on its 5' promoter region, which could then lead to suppress the homologous recombination-related BRCA1 expression via direct binding to the mRNA 3'UTR. Preclinical studies using an in vivo mouse model also demonstrated that combining Enz plus olaparib led to better suppression of the HCC progression. Together, these in vitro/in vivo data suggest that combining Enz and olaparib may help in the development of a novel therapy to better suppress the HCC progression.

α-Fe2O3@Pt heterostructure particles to enable sonodynamic therapy with self-supplied O2 and imaging-guidance.

Sonodynamic therapy (SDT), presenting spatial and temporal control of ROS generation triggered by ultrasound field, has attracted considerable attention in tumor treatment. However, its therapeutic efficacy is severely hindered by the intrinsic hypoxia of solid tumor and the lack of smart design in material band structure. Here in study, fine α-Fe2O3 nanoparticles armored with Pt nanocrystals (α-Fe2O3@Pt) was investigated as an alternative SDT agent with ingenious bandgap and structural design. The Schottky barrier, due to its unique heterostructure, suppresses the recombination of sono-induced electrons and holes, enabling superior ROS generation. More importantly, the composite nanoparticles may effectively trigger a reoxygenation phenomenon to supply sufficient content of oxygen, favoring the ROS induction under the hypoxic condition and its extra role played for ultrasound imaging. In consequence, α-Fe2O3@Pt appears to enable effective tumor inhibition with imaging guidance, both in vitro and in vivo. This study has therefore demonstrated a highly potential platform for ultrasound-driven tumor theranostic, which may spark a series of further explorations in therapeutic systems with more rational material design.

Founder cells for hepatocytes during liver regeneration: from identification to application.

Liver regeneration (LR) capacity in vertebrates developed through natural selection over a hundred million years of evolution. To maintain homeostasis or recover from various injuries, liver cells must regenerate; this process includes the renewal of parenchymal and nonparenchymal cells as well as the formation of liver structures. The cellular origin of newly grown tissue is one of the critical questions in this area and has been a subject of prolonged debate. The regenerative tissue may derive from either hepatocyte self-duplication or liver stem/progenitor cells (LSPCs). Recently, hepatocyte subpopulations and cholangiocytes were also described as important founder cells. The niche that triggers the proliferation of hepatocytes and the differentiation of LSPCs has been extensively studied. Meanwhile, in vitro culture systems for liver founder cells and organoids have been developed rapidly for mechanistic studies and potential therapeutic purposes. This review summarizes the cellular sources and niches that give rise to renewed hepatocytes during LR, and it also describes in vitro culture studies of those founder cells for future applications, as well as current reports for stem cell-based therapies for liver diseases.

Laparoscopic anatomical portal territory hepatectomy using Glissonean pedicle approach (Takasaki approach) with indocyanine green fluorescence negative staining: how I do it.

BACKGROUND: Laparoscopic anatomical resection (LAR) is a highly challenging procedure. This study aimed to describe our experience of the LAR with an indocyanine green fluorescence negative staining (ICGNS) by the Glissonean pedicle transection (Takasaki) approach. METHODS: From April 2017 to December 2019, 43 consecutive patients underwent LAR with ICGNS strategy in our medical team. The details of the ICGNS strategy were described. The demographic and clinicopathological data of the included patients were retrospectively analyzed. RESULTS: The extent of resections included right hemihepatectomy (n = 12), left hemihepatectom (n = 4), left lateral sectionectomy (n = 3), Right anterior sectionectomy (n = 3), Right posterior sectionectomy (n = 6), central hepatectomy (n = 2), single anterolateral segmentectomy (n = 5), single posterosuperior segmentectomy (n = 6), and bisegmentectomy (n = 2). The mean operation time was 212 ± 53 min, and the median estimated blood loss was 200 (100-300) ml. The overall complication rate was 30.2% (grade I, 14%; grade II, 14%; grade III, 2.3%). The median duration of postoperative hospital stay was 6 (4-7) days. CONCLUSION: ICGNS is a safe and feasible LAR strategy that greatly facilitates selecting the liver transection plane, although its benefits need to be verified by large-sample comparative studies.

N6-methyladenosine-modified CircRNA-SORE sustains sorafenib resistance in hepatocellular carcinoma by regulating ß-catenin signaling.

BACKGROUND AND AIMS: Accumulating evidence suggests that the primary and acquired resistance of hepatocellular carcinoma (HCC) to sorafenib is mediated by multiple molecular, cellular, and microenvironmental mechanisms. Understanding these mechanisms will enhance the likelihood of effective sorafenib therapy. METHODS: In vitro and in vivo experiments were performed and clinical samples and online databases were acquired for clinical investigation. RESULTS: In this study, we found that a circular RNA, circRNA-SORE, which is up-regulated in sorafenib-resistant HCC cells, was necessary for the maintenance of sorafenib resistance, and that silencing circRNA-SORE substantially increased the efficacy of sorafenib-induced apoptosis. Mechanistic studies determined that circRNA-SORE sequestered miR-103a-2-5p and miR-660-3p by acting as a microRNA sponge, thereby competitively activating the Wnt/ß-catenin pathway and inducing sorafenib resistance. The increased level of circRNA-SORE in sorafenib-resistant cells resulted from increased RNA stability. This was caused by an increased level of N6-methyladenosine (m6A) at a specific adenosine in circRNA-SORE. In vivo delivery of circRNA-SORE interfering RNA by local short hairpin RNA lentivirus injection substantially enhanced sorafenib efficacy in animal models. CONCLUSIONS: This work indicates a novel mechanism for maintaining sorafenib resistance and is a proof-of-concept study for targeting circRNA-SORE in sorafenib-treated HCC patients as a novel pharmaceutical intervention for advanced HCC.

Role of cellular, molecular and tumor microenvironment in hepatocellular carcinoma: Possible targets and future directions in the regorafenib era.

Hepatocellular carcinoma (HCC) remains as one of the major causes of cancer-related mortality, despite the recent development of new therapeutic options. Regorafenib, an oral multikinase inhibitor, is the first systemic therapy that has a survival benefit for patients with advanced HCC that have a poor response to sorafenib. Even though regorafenib has been approved by the FDA, the clinical trial for regorafenib treatment does not show significant improvement in overall survival. The impaired efficacy of regorafenib caused by various resistance mechanisms, including epithelial-mesenchymal transitions, inflammation, angiogenesis, hypoxia, oxidative stress, fibrosis and autophagy, still needs to be resolved. In this review, we provide insight on regorafenib microenvironmental, molecular and cellular mechanisms and interactions in HCC treatment. The aim of this review is to help physicians select patients that would obtain the maximal benefits from regorafenib in HCC therapy.