BackgroundCircRNAs are found to affect initiation and progression of several cancer types. However, whether circRNAs are implicated in gallbladder cancer (GBC) progression remains obscure.MethodsWe perform RNA sequencing in 10 pairs of GBC and para-cancer tissues. CCK8 and clone formation assays are used to evaluate proliferation ability of GBC cells. qPCR and Western blot are used to determine expression of RNAs and proteins, respectively. CircRNA-protein interaction is confirmed by RNA pulldown, RNA immunoprecipitation, and fluorescence in situ hybridization.ResultsWe find that circRNA expression pattern is tremendously changed during GBC development. Among dozens of significantly changed circRNAs, a circRNA generated from the oncogene ERBB2, named as circERBB2, is one of the most significant changes. CircERBB2 promotes GBC proliferation, in vitro and in vivo. Other than being a miRNA sponge, circERBB2 accumulates in the nucleoli and regulates ribosomal DNA transcription, which is one of the rate-limiting steps of ribosome synthesis and cellular proliferation. CircERBB2 regulates nucleolar localization of PA2G4, thereby forming a circERBB2-PA2G4-TIFIA regulatory axis to modulate ribosomal DNA transcription and GBC proliferation. Increased expression of circERBB2 is associated with worse prognosis of GBC patients.ConclusionsOur findings demonstrate that circERBB2 serves as an important regulator of cancer cell proliferation and shows the potential to be a new therapeutic target of GBC.

Background Gallbladder cancer (GBC) is an extremely malignant tumor with a high mortality rate. Little is known about its invasion and metastasis mechanism so far. Methods To identify the driver genes in GBC metastasis, we performed a mRNA microarray of metastatic GBC and paired non-tumor samples, and found PLEK2 was markedly upregulated in GBC tissues. Next, the expression of PLEK2 in GBC were examined in a larger cohort of patients by qRT-PCR, western blot and IHC staining. The clinicopathologic correlation of PLEK2 was determined by statistical analyses. The biological involvement of PLEK2 in GBC metastasis and the underlying mechanisms were investigated. Results In this study, we found that PLEK2 had higher expression in GBC tumor tissues compared to non-cancerous adjacent tissues and cholecystolithiasis tissues. The clinicopathologic analyses showed PLEK2 expression was positively correlated with tumor TNM stage, distant metastasis and PLEK2 was an independent predictor of overall survival (OS) in GBC patients. The cellular function assays showed PLEK2 promoted GBC cells migration, invasion and liver metastasis in mouse model via the regulation of epithelial-mesenchymal transition (EMT) process. Our mass spectrum and co-immunoprecipitation (co-IP) assays demonstrated that PLEK2 could interact with the kinase domain of EGFR and suppress EGFR ubiquitination mediated by c-CBL, leading to constitutive activation of EGFR signaling. Furthermore, RNA-sequencing and qRT-PCR results demonstrated chemokine (C-C motif) ligand 2 (CCL2), a target gene downstream of PLEK2/EGFR signaling, mediated the motility-promoting function of PLEK2. Conclusions On the basis of these collective data, we propose that PLEK2 promotes the invasion and metastasis of GBC by EGFR/CCL2 pathway and PLEK2 can serve as a potential therapeutic target for GBC treatment. Electronic supplementary material The online version of this article (10.1186/s13046-019-1250-8) contains supplementary material, which is available to authorized users.

Gemcitabine is the first-line treatment for locally advanced and metastatic gallbladder cancer (GBC), but poor gemcitabine response is universal. Here, we utilize a genome-wide CRISPR screen to identify that loss of ELP5 reduces the gemcitabine-induced apoptosis in GBC cells in a P53-dependent manner through the Elongator complex and other uridine 34 (U34) tRNA-modifying enzymes. Mechanistically, loss of ELP5 impairs the integrity and stability of the Elongator complex to abrogate wobble U34 tRNA modification, and directly impedes the wobble U34 modification-dependent translation of hnRNPQ mRNA, a validated P53 internal ribosomal entry site (IRES) trans-acting factor. Downregulated hnRNPQ is unable to drive P53 IRES-dependent translation, but rescuing a U34 modification-independent hnRNPQ mutant could restore P53 translation and gemcitabine sensitivity in ELP5-depleted GBC cells. GBC patients with lower ELP5, hnRNPQ, or P53 expression have poor survival outcomes after gemcitabine chemotherapy. These results indicate that the Elongator/hnRNPQ/P53 axis controls gemcitabine sensitivity in GBC cells.

Bile acids (BAs), well-defined signaling molecules with diverse metabolic functions, play important roles in cellular processes associated with many cancers. As one of the most common BAs, deoxycholic acid (DCA) is originally synthesized in the liver, stored in the gallbladder, and processed in the gut. DCA plays crucial roles in various tumors; however, functions and molecular mechanisms of DCA in gallbladder cancer (GBC) still remain poorly characterized. Here, we analyzed human GBC samples and found that DCA was significantly downregulated in GBC, and reduced levels of DCA was associated with poor clinical outcome in patients with GBC. DCA treatment impeded tumor progression by halting cell proliferation. DCA decreased miR-92b-3p expression in an m6A-dependent posttranscriptional modification manner by facilitating dissociation of METTL3 from METTL3–METTL14–WTAP complex, which increased the protein level of the phosphatase and tensin homolog, a newly identified target of miR-92b-3p, and subsequently inactivated the PI3K/AKT signaling pathway. Our findings revealed that DCA might function as a tumor suppressive factor in GBC at least by interfering with miR-92b-3p maturation, and suggested that DCA treatment could provide a new therapeutic strategy for GBC.

Human levels of dexterity has not been duplicated in a robotic form to date. Dexterity is achieved in part due to the biomechanical structure, and in part due to the neural control of movement. An anatomically correct test-bed (ACT) hand has been constructed to investigate the importance and behavioral consequences of anatomical features and neural control strategies of the human hand. This paper focused on the role of the human hand's variable moment arm. System identification was conducted on the ACT index finger's two degrees of freedom at the metacarpal-phalange (MCP) joint to provide an understanding of, for the first time, how the moment arms vary with multiple joints moving simultaneously. The specific combination of nonlinear moment arms results in an increased ability to produce force at the fingertip for the same neural input when the finger's flexion and adduction angles increase (that is toward the middle of the hand). This preliminary work will lead to answering what biomechanical and neural functions are required to construct fully dexterous robotic and prosthetic hands in the future.

The CD4 ؉ CD25 ؉ FOXP3 ؉ regulatory T (Treg) cells are critical for maintaining immune tolerance in healthy individuals and are reported to restrict anti-inflammatory responses and thereby promote tumor progression, suggesting them as a target in the development of antitumor immunotherapy. Forkhead box P3 (FOXP3) is a key transcription factor governing Treg lineage differentiation and their immune-suppressive function. Here, using Treg cells, as well as HEK-293T and Jurkat T cells, we report that the stability of FOXP3 is directly and positively regulated by the E3 ubiquitin ligase ring finger protein 31 (RNF31), which catalyzes the conjugation of atypical ubiquitin chains to the FOXP3 protein. We observed that shRNA-mediated RNF31 knockdown in human Treg cells decreases FOXP3 protein levels and increases levels of interferon-␥, resulting in a Th1 helper cell-like phenotype. Human Treg cells that ectopically expressed RNF31 displayed stronger immune-suppressive capacity, suggesting that RNF31 positively regulates both FOXP3 stability and Treg cell function. Moreover, we found that RNF31 is up-regulated in Treg cells that infiltrate human gastric tumor tissues compared with their counterparts residing in peripheral and normal tissue. We also found that elevated RNF31 expression in intratumoral Treg cells is associated with poor survival of gastric cancer patients, suggesting that RNF31 supports the immune-suppressive functions of Treg cells. Our results suggest that RNF31 could be a potential therapeutic target in immunity-based interventions against human gastric cancer.

Finite treatment with nucleos(t)ide analogues (NAs) remains a great challenge for chronic hepatitis B in the clinic. This study aimed to investigate the relationship between intrahepatic quasispecies heterogeneity and the NAs off-treatment outcomes in a prospective cohort. Eighteen HBeAg-positive patients with chronic hepatitis B who achieved the cessation criteria underwent liver biopsy, and stopped treatment thereafter. Patients were followed up prospectively for 1 year. The reverse transcriptase (RT) gene of intrahepatic hepatitis B virus (HBV) was cloned and sequenced. Intrahepatic quasispecies heterogeneity and specific gene mutations were analysed using bioinformatic methods. Ten patients achieved sustained response, and eight patients developed viral relapse. The intrahepatic quasispecies Shannon entropy and nucleotide diversity within either RT or the surface (S) region of patients with sustained response were significantly higher (p < 0.05) than those of patients who had a viral relapse. Intrahepatic quasispecies Shannon entropy at the nucleotide level predicted the sustained off-treatment response (area under receiver operating characteristics curve 0.925; 95% CI 0.807-1.000; p 0.003). More positive selection sites and N-glycosylation mutations within the S region were found in patients with sustained response than in the patients with viral relapse (p < 0.01). Most of the positive selection sites in patients with sustained response were located in reported HLA-I-restricted or HLA-II-restricted epitopes. Intrahepatic quasispecies heterogeneity at the end of treatment was correlated with off-treatment outcomes in HBeAg-positive patients with chronic hepatitis B. More immune escape mutations were found within the S region in patients with sustained response. The higher intrahepatic quasispecies heterogeneity indicated a more robust immune control over HBV, which in turn maintained a sustained response after withdrawal of NAs.

CD4 CD25 regulatory T (Treg) cells comprise a unique subset of T cells required for maintaining immune homeostasis. However, the molecular mechanisms associated with the functional variety of Treg cells are not fully delineated. In the present study, we demonstrate that ubiquitin-specific protease (USP)4 physically interacted with interferon regulatory factor 8 (IRF8) function via a K48-linked deubiquitinase, which stabilized IRF8 protein levels in Treg cells. Depletion of USP4 promoted the polyubiquitination of IRF8 and the upregulation of type 2 inflammatory cytokine gene expression in Treg cells. Consistently, treatment of Treg cells with USP4 inhibitor facilitated the polyubiquitination of IRF8. In addition, the deficiency of USP4 alleviated the suppressive function of Treg cells. Taken together, our results suggest that USP4 interacts with and stabilizes IRF8 to promote the suppressive function of Treg cells.