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/β-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.

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HCC is a common malignancy worldwide and surgery or reginal treatments are deemed insufficient for advancedstage disease. Sorafenib is an inhibitor of many kinases and was shown to benefit advanced HCC patients. However, resistance emerges soon after initial treatment, limiting the clinical benefit of sorafenib, and the mechanisms still remain elusive. Thus, this study aims to investigate the mechanisms of sorafenib resistance and to provide possible targets for combination therapies. Through miRNA sequencing, we found that miR-486-3p was downregulated in sorafenib resistant HCC cell lines. Cell viability experiments showed increased miR-486-3p expression could induce cell apoptosis while miR-486-3p knockdown by CRISPR-CAS9 technique could reduce cell apoptosis in sorafenib treatment. Clinical data also indicated that miR-486-3p level was downregulated in tumor tissue compared with adjacent normal tissue in HCC patients. Mechanism dissections showed that FGFR4 and EGFR were the targets of miR-486-3p, which was verified by luciferase reporter assay. Importantly, FGFR4 or EGFR selective inhibitor could enhance sorafenib efficacy in the resistant cells. Moreover, in vivo sorafenib resistant model identified that over-expressing miR-486-3p by lentivirus injection could overcome sorafenib resistance by significantly suppressing tumor growth in combination with the treatment of sorafenib. In conclusion, we found miR-486-3p was an important mediator regulating sorafenib resistance by targeting FGFR4 and EGFR, thus offering a potential target for HCC treatment.

Sorafenib resistance is a major obstacle to the treatment of advanced hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) are multifunctional regulators of gene expression with profound impact for human disease. Therefore, better understanding of the biological mechanisms of abnormally expressed miRNAs is critical to discovering novel, promising therapeutic targets for HCC treatment. This study aimed to investigate the role of miR-378a-3p in the sorafenib resistance of HCC and elucidate the underlying molecular mechanisms. Methods : A novel hub miR-378a-3p was identified based on miRNA microarray and bioinformatics analysis. The abnormal expression of miR-378-3p was validated in different HCC patient cohorts and sorafenib-resistant (SR) HCC cell lines. The functional role of miR-378a-3p and its downstream and upstream regulatory machinery were investigated by gain-of-function and loss-of-function assays in vitro and in vivo . Interactions among miR-378a-3p, LXRα, and IGF1R were examined by a series of molecular biology experiments. Then, the clinical relevance of miR-378a-3p and its targets were evaluated in HCC samples. HCC patient-derived xenograft (PDX) model was used to assess the therapeutic value of LXRα and its downstream miR-378a-3p. Results : miR-378a-3p expression was frequently reduced in established sorafenib-resistant HCC cell lines. The decreased miR-378a-3p levels correlated with poor overall survival of HCC patients following sorafenib treatment. miR-378a-3p overexpression induced apoptosis in SR HCC cells, whereas miR-378a-3p silencing exerted the opposite effects. IGF1R was identified as a novel target of miR-378a-3p. Furthermore, the primary miR-378 level was not consistent with its precursor miRNA level in SR HCC cells, which was attributed to the downregulation of exportin5 (XPO5) and subsequently reduced nuclear export of precursor miR-378 and restrained maturation of miR-378-3p. In this context, we combined an agonist GW3965 of liver X receptor alpha (LXRα), which functioned as a transcription activator of miRNA-378a, and its activation re-sensitized sorafenib-resistant cells to sorafenib treatment in vitro and in vivo . Conclusions : Our finding suggested decreased expression of XPO5 prevents maturation of miR-378a-3p, which leaded to the overexpression of IGF-1R and counteracted the effects of sorafenib-induced apoptosis. LXRα was able to activate miRNA-378a-3p transcription in HCC cells and could be a potential combinable treatment strategy with sorafenib to suppress HCC progression.

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A proposed method based on combining the concepts of shape functions of the finite element method (FEM) and a molecular dynamics (MD) technique was developed to evaluate the chip formation and strain and stress distribution in the cutting of single-crystal copper by a nano-scale mechanism. The displacement components for the atom in any temporary situation during the nano-scale cutting could be found. In this paper, the atom is regarded as a node and the lattice is regarded as an element. Using the atom displacements calculated by the MD program and combining the concepts of shape functions of FEM we calculate the equivalent strain for material deformation in the atomic-scale cutting mechanism. The equivalent stress was derived from the equivalent strain from the corresponding flow stress–strain curve, whereas the flow stress–strain curve was obtained from the regression of the stress–strain curve of a nano-copper thin film tension test simulation. In addition, the chip atoms within the diamond space were moved along the tool surface using a mathematical method. Also, this study introduced a new concept: ‘a combined Morse potential function and rigid tool space restrictions criterion as the chip separation criterion’ for the nano-scale cutting model.

The treatment for hepatocellular carcinoma (HCC) is promising in recent years, but still facing critical challenges. The first targeted therapy, sorafenib, prolonged the overall survival by months. However, resistance often occurs, largely limits its efficacy. Sorafenib was found to target the electron transport chain complexes, which results in the generation of reactive oxygen species (ROS). To maintain sorafenib resistance and further facilitate tumor progression, cancer cells develop strategies to overcome excessive ROS production and obtain resistance to oxidative stress-induced cell death. In the present study, we investigated the roles of ROS in sorafenib resistance, and found suppressed ROS levels and reductive redox states in sorafenib-resistant HCC cells. Mitochondria in sorafenib-resistant cells maintained greater functional and morphological integrity under the treatment of sorafenib. However, cellular oxygen consumption rate and mitochondria DNA content analyses revealed fewer numbers of mitochondria in sorafenib-resistant cells. Further investigation attributed this finding to decreased mitochondrial biogenesis, likely caused by the accelerated degradation of peroxisome proliferator-activated receptor γ coactivator 1β (PGC1β). Mechanistic dissection showed that upregulated UBQLN1 induced PGC1β degradation in a ubiquitination-independent manner to attenuate mitochondrial biogenesis and ROS production in sorafenib-resistant cells under sorafenib treatment. Furthermore, clinical investigations further indicated that the patients with higher UBQLN1 levels experienced worse recurrence-free survival. In conclusion, we propose a novel mechanism involving mitochondrial biogenesis and ROS homeostasis in sorafenib resistance, which may offer new therapeutic targets and strategies for HCC patients.

For the Gaussian beam, the power density distribution of the aluminum-coated optical tapered fiber probe is discussed and a theoretical fixed-point fabrication model for near-field photolithography is established. The energy density theorem is used to explore the surface exposure of photoresist, which is divided into multiple grids to evaluate the changes in the concentration of photoactive compounds at specific nodes of the interior layer. The full width at half maximum (FWHM) and the contour of the photolithograph following development are then calculated. The fixed-point lithographic experiment and aperture verification of the optic fiber probe are performed to confirm the reliability of the present model, and Dill A, B, C parameters are first measured in this article. According to the experimental results, a better image of the probe aperture can be achieved by increasing the conductivity of the measured articles and reducing the electric charges during the image taken by field-emission scanning electron microscope. The FWHM measured is 166.6 nm, while the measured average probe aperture size is 317.4 nm and the FWHM simulated by the proposed model is 151.3 nm. The error between experiment and simulation is <-9.2%. It is thus concluded that the proposed theoretical model is reasonable and acceptable.