Rap2B knockdown suppresses malignant progression of hepatocellular carcinoma by inactivating the PTEN/PI3K/Akt and ERK1/2 pathways

Molecular and Cellular Biochemistry - Rap2B, belonging to the Ras superfamily of small guanosine triphosphate-binding proteins, is upregulated and contributes to the progression of several tumors...     

Interleukin-11 promotes the progress of gastric carcinoma via abnormally expressed versican

Versican, a ubiquitous component of the extracellular matrix (ECM), accumulates both in tumor stroma and cancer cells and is highly regulated by various cytokines. The aberrant expression of versican and its isoforms is known to modulate cell proliferation, differentiation, and migration, all of which are features of the invasion and metastasis of cancer; versican is also known to favour the homeostasis of the ECM. Interleukin-11 (IL-11) is an important cytokine that exhibits a wide variety of biological effects in gastric cancer development. Here, we analysed the expression of versican isoforms and found that the major isoforms expressed by both gastric carcinoma tissue and gastric cell lines were V0 and V1, and V1 was significantly higher in gastric carcinoma tissue. The treatment of the gastric cell lines AGS and MKN45 with rhIL-11 resulted in a significant increase in the expression of V0 and V1. Exogenous IL-11 increased migration in AGS and MKN45 cells, whereas these effects were reversed when the expression of V0 and V1 were abolished by siRNA targeting versican V0/V1. Collectively, these findings suggest that the abnormally expressed versican and its isoforms participate, at least in part, in the progress of gastric carcinoma triggered by IL-11.     

Rac1 activation inhibits E-cadherin-mediated adherens junctions via binding to IQGAP1 in pancreatic carcinoma cells

Nck is a ubiquitously expressed adapter protein that is almost exclusively built of one SH2 domain and three SH3 domains. The two isoproteins of Nck are functionally redundant in many aspects and differ in only few amino acids that are mostly located in the linker regions between the interaction modules. Nck proteins connect receptor and non-receptor tyrosine kinases to the machinery of actin reorganisation. Thereby, Nck regulates activation-dependent processes during cell polarisation and migration and plays a crucial role in the signal transduction of a variety of receptors including for instance PDGF-, HGF-, VEGF- and Ephrin receptors. In most cases, the SH2 domain mediates binding to the phosphorylated receptor or associated phosphoproteins, while SH3 domain interactions lead to the formation of larger protein complexes. In T lymphocytes, Nck plays a pivotal role in the T cell receptor (TCR)-induced reorganisation of the actin cytoskeleton and the formation of the immunological synapse. However, in this context, two different mechanisms and adapter complexes are discussed. In the first scenario, dependent on an activation-induced conformational change in the CD3ε subunits, a direct binding of Nck to components of the TCR/CD3 complex was shown. In the second scenario, Nck is recruited to the TCR complex via phosphorylated Slp76, another central constituent of the membrane proximal activation complex. Over the past years, a large number of putative Nck interactors have been identified in different cellular systems that point to diverse additional functions of the adapter protein, e.g. in the control of gene expression and proliferation.     

Gankyrin drives malignant transformation of chronic liver damage-mediated fibrosis via the Rac1/JNK pathway

Hepatocarcinogenesis is a complex process involving chronic liver injury, inflammation, unregulated wound healing, subsequent fibrosis and carcinogenesis. To decipher the molecular mechanism underlying transition from chronic liver injury to dysplasia, we investigated the oncogenic role of gankyrin (PSMD10 or p28^GANK) during malignant transformation in a transgenic mouse model. Here, we find that gankyrin increased in patients with cirrhosis. In addition to more severe liver fibrosis and tumorigenesis after DEN plus CCl₄ treatment, hepatocyte-specific gankyrin-overexpressing mice (gankyrin^hep) exhibited malignant transformation from liver fibrosis to tumors even under single CCl₄ administration, whereas wild-type mice merely experienced fibrosis. Consistently, enhanced hepatic injury, severe inflammation and strengthened compensatory proliferation occurred in gankyrin^hep mice during CCl₄ performance. This correlated with augmented expressions of cell cycle-related genes and abnormal activation of Rac1/c-jun N-terminal kinase (JNK). Pharmacological inhibition of the Rac1/JNK pathway attenuated hepatic fibrosis and prevented CCl₄-induced carcinogenesis in gankyrin^hep mice. Together, these findings suggest that gankyrin promotes liver fibrosis/cirrhosis progression into hepatocarcinoma relying on a persistent liver injury and inflammatory microenvironment. Blockade of Rac1/JNK activation impeded gankyrin-mediated hepatocytic malignant transformation, indicating the combined inhibition of gankyrin and Rac1/JNK as a potential prevention mechanism for cirrhosis transition.Hepatocellular carcinoma (HCC) is the prototype of inflammation-associated cancer, as most patients with HCC have an established background of unresolved chronic liver disease and cirrhosis.¹ Major HCC risk factors include infection with hepatitis viruses, intake of aflatoxin-contaminated food, alcoholic liver disease, nonalcoholic steatohepatitis (NASH), chronic hepatic inflammation and cirrhosis.^{2, 3} Cirrhosis is the primary risk factor for developing HCC, accompanied by long periods of chronic liver disease.⁴ However, the molecular mechanisms of this malignant transformation remain elusive.Gankyrin was identified as an oncoprotein that frequently overexpressed in human liver cancers and increased in the earlier stage of liver carcinogenesis.^{5, 6} It controls phosphorylated Rb and p53 degradation,^{7, 8} promotes the expansion of tumor-initiating cells⁹ and accelerates HCC progression. In addition, it also has been shown to regulate NF-κB and AKT.^{10, 11} We recently found that, in a rat model of carcinogen-induced liver carcinogenesis, gankyrin elevated in the stage of cirrhosis.¹² However, it is still unknown how gankyrin promotes hepatocarcinogenesis in vivo.Here, we show increased gankyrin expression in patients with cirrhosis. We further used hepatocyte-specific gankyrin-overexpressing mice to study the role of gankyrin in hepatocarcinogenesis. Sustained gankyrin activation promotes DEN plus carbon tetrachloride (CCl₄)-induced HCC formation. Moreover, it aggravates CCl₄-mediated liver injury, hepatic fibrosis and ultimately leads to the development of cirrhosis and progression into HCC.     

New species of messenger RNA in aflatoxin B1 induced hepatocellular carcinoma

Differences in the mRNA species were observed when cDNA complementary to HnRNA from normal liver was hybridized with mRNA from hepatocellular carcinoma induced by aflatoxin B1. The hybridizations between cDNA complementary to HnRNA from liver cell carcinoma and HnRNA from normal liver indicate that there is homology between their sequences. The findings in this paper suggest that mRNA species normally restricted to the cell nucleus are present in the cytoplasm of liver carcinoma cells.     

A genetic variant at KIF1B predicts clinical outcome of HBV-related hepatocellular carcinoma in Chinese

BackgroundRecently, a genome-wide association study conducted in Chinese reported a single nucleotide polymorphism at KIF1B, rs17401966, associated with the susceptibility of hepatitis B virus-related hepatocellular carcinoma. In this study, we aim to investigate the effect of rs17401966 on the prognosis of hepatitis B virus-related hepatocellular carcinoma patients at intermediate or advanced stages.MethodsThe SNP rs17401966 was genotyped using the TaqMan allelic discrimination assay in 414 intermediate or advanced hepatocellular carcinoma patients. Log-rank test and Cox proportional hazard models were used for survival analyses.ResultsPrevious studies have identified that the G allele of rs17401966 demonstrated protective effect for the susceptibility of hepatitis B virus-related hepatocellular carcinoma. Here we found that subjects carrying the G allele of rs17401966 was significantly associated with a better survival compared with those carrying the A allele (adjusted hazard ratio = 0.82, 95% confidence intervals = 0.68–0.99, P = 0.044 in an additive genetic model).ConclusionThe variant G allele of rs17401966 may be a favorable biomarker for the prognosis of intermediate or advanced hepatitis B virus-related hepatocellular carcinoma patients in this Chinese population.     

Platycodin D reverses histone deacetylase inhibitor resistance in hepatocellular carcinoma cells by repressing ERK1/2-mediated cofilin-1 phosphorylation

BackgroundChemoresistance remains the main obstacle in hepatocellular carcinoma (HCC) therapy. Despite significant advances in HCC therapy, HCC still has a poor prognosis. Thus, there is an urgent need to identify a treatment target to reverse HCC chemotherapy resistance. Platycodon grandiflorus (PG) is a perennial herb that has been used as food and traditional Chinese medicine for thousands of years in Northeast Asia. Platycodin D (PD), a main active triterpenoid saponin found in the root of PG, has been reported to possess anticancer properties in several cancer cell lines, including HCC; however, the reversal effect of this molecule on HCC chemoresistance remains largely unknown.PurposeThis study aimed to investigate the role and the mechanism of PD-mediated reversal of the histone deacetylase inhibitor (HDACi) resistance in HCC cells.MethodsHuman HCC cells (HA22T) and HDACi-resistant (HDACi-R) cells were used. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Combination index was used to calculate the synergism potential. Expression of ERK1/2 (total/phospho), cofilin-1 (total/phospho) and apoptosis-related protein was determined using western blotting. Mitochondrial membrane potential was assessed using the JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolocarbocyanine iodide) probe. Apoptosis was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Mitochondrial reactive oxygen species generation was measured using the MitoSOX Red fluorescent probe.ResultsWe found that PD treatment inhibited cell viability both in HA22T HCC and HDACi-R cells. Inhibition of ERK1/2 by PD98059 could reverse drug resistance in HDACi-R cells treated with PD98059 and PD. Nevertheless, pre-treatment with U46619, an ERK1/2 activator, rescued PD-induced apoptosis by decreasing levels of apoptosis-related proteins in HCC cells. The combined treatment of PD with apicidin a powerful HDACi, dramatically enhanced the apoptotic effect in HDACi-R cells.ConclusionFor the first time, we showed that PD reversed HDACi resistance in HCC by repressing ERK1/2-mediated cofilin-1 phosphorylation. Thus, PD can potentially be a treatment target to reverse HCC chemotherapy resistance in future therapeutic trials.     

Rac1-PAK1 regulation of Rab11 cycling promotes junction destabilization

Rac1 GTPase is hyperactivated in tumors and contributes to malignancy. Rac1 disruption of junctions requires its effector PAK1, but the precise mechanisms are unknown. Here, we show that E-cadherin is internalized via micropinocytosis in a PAK1–dependent manner without catenin dissociation and degradation. In addition to internalization, PAK1 regulates E-cadherin transport by fine-tuning Rab small GTPase function. PAK1 phosphorylates a core Rab regulator, RabGDIβ, but not RabGDIα. Phosphorylated RabGDIβ preferentially associates with Rab5 and Rab11, which is predicted to promote Rab retrieval from membranes. Consistent with this hypothesis, Rab11 is activated by Rac1, and inhibition of Rab11 function partially rescues E-cadherin destabilization. Thus, Rac1 activation reduces surface cadherin levels as a net result of higher bulk flow of membrane uptake that counteracts Rab11-dependent E-cadherin delivery to junctions (recycling and/or exocytosis). This unique small GTPase crosstalk has an impact on Rac1 and PAK1 regulation of membrane remodeling during epithelial dedifferentiation, adhesion, and motility.     

Hypoxia blocks ferroptosis of hepatocellular carcinoma via suppression of METTL14 triggered YTHDF2-dependent silencing of SLC7A11

Residue hepatocellular carcinoma (HCC) cells enduring hypoxic environment triggered by interventional embolization obtain more malignant potential with little clarified mechanism. The N⁶-methyladenosine (m⁶A) biological activity plays essential roles in diverse physiological processes. However, its role under hypoxic condition remains largely unexplored. RT-qPCR and Western blot were used to evaluate METTL14 expression in hypoxic HCC cells. MDA assay and electronic microscopy photography were used to evaluate ferroptosis. The correlation between SLC7A11 and METTL14 was conducted by bioinformatical analysis. Flow cytometry was used to verify the effect of SLC7A11 on ROS production. Cell counting kit-8 assay was performed to detect cells proliferation ability. Hypoxia triggered suppression of METTL14 in a HIF-1α–dependent manner potently abrogated ferroptosis of HCC cells. Mechanistic investigation identified SLC7A11 was a direct target of METTL14. Both in vitro and in vivo assay demonstrated that METTL14 induced m⁶A modification at 5’UTR of SLC7A11 mRNA, which in turn underwent degradation relied on the YTHDF2-dependent pathway. Importantly, ectopic expression of SLC7A11 strongly blocked METTL14-induced tumour-suppressive effect in hypoxic HCC. Our investigations lay the emphasis on the hypoxia-regulated ferroptosis in HCC cells and identify the HIF-1α /METTL14/YTHDF2/SLC7A11 axis as a potential therapeutic target for the HCC interventional embolization treatment.     

增殖相关信号通路在肝癌中的研究进展

肝癌是世界范围内最常见的恶性肿瘤之一.随着分子生物学技术的迅速发展,阐明肝癌的分子机制以及发现新的治疗靶点,是当今肝癌领域的研究热点之一.目前,已发现肝癌的发病与细胞内增殖信号通路有关,比如Wnt/β-Catenin、PI3K/AKT、JAK/STAT、Hedgehog、Hippo等.本文介绍了细胞增殖与肝癌的关系、肝...     

Recurrence-associated pathways in hepatitis B virus-positive hepatocellular carcinoma

Background

Despite the recent identification of several prognostic gene signatures, the lack of common genes among experimental cohorts has posed a considerable challenge in uncovering the molecular basis underlying hepatocellular carcinoma (HCC) recurrence for application in clinical purposes. To overcome the limitations of individual gene-based analysis, we applied a pathway-based approach for analysis of HCC recurrence.

Results

By implementing a permutation-based semi-supervised principal component analysis algorithm using the optimal principal component, we selected sixty-four pathways associated with hepatitis B virus (HBV)-positive HCC recurrence (p < 0.01), from our microarray dataset composed of 142 HBV-positive HCCs. In relation to the public HBV- and public hepatitis C virus (HCV)-positive HCC datasets, we detected 46 (71.9%) and 18 (28.1%) common recurrence-associated pathways, respectively. However, overlap of recurrence-associated genes between datasets was rare, further supporting the utility of the pathway-based approach for recurrence analysis between different HCC datasets. Non-supervised clustering of the 64 recurrence-associated pathways facilitated the classification of HCC patients into high- and low-risk subgroups, based on risk of recurrence (p < 0.0001). The pathways identified were additionally successfully applied to discriminate subgroups depending on recurrence risk within the public HCC datasets. Through multivariate analysis, these recurrence-associated pathways were identified as an independent prognostic factor (p < 0.0001) along with tumor number, tumor size and Edmondson’s grade. Moreover, the pathway-based approach had a clinical advantage in terms of discriminating the high-risk subgroup (N = 12) among patients (N = 26) with small HCC (<3 cm).

Conclusions

Using pathway-based analysis, we successfully identified the pathways involved in recurrence of HBV-positive HCC that may be effectively used as prognostic markers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1472-x) contains supplementary material, which is available to authorized users.     

Inhibition of CTRP6 prevented survival and migration in hepatocellular carcinoma through inactivating the AKT signaling pathway

C1qTNF-related proteins (CTRPs) are a member of the adiponectin paralogs family, which are implicated in regulation of various biological processes. Recently, CTRP6 was found upregulated in human hepatocellular carcinomas (HCC). However, the specific roles and molecular mechanisms of CTRP6 in HCC remain unclear. Here, we investigated the effects of CTRP6 on the vitality, apoptosis, migration, and invasion of HCC cells. Firstly, we measured the levels of CTRP6 in HCC tissues and cell lines. Our results showed that CTRP6 was markedly upregulated in HCC tissues and Hep3B cells. Then, the CTRP6 siRNA was transfected into Hep3B cells. Cell counting kit-8 (CCK-8) assay and flow cytometry analysis revealed that silencing CTRP6-induced cell viability inhibition, and apoptosis. The wound-healing and transwell assay showed that CTRP6 deficiency suppressed the migration and invasion of Hep3B cells. Meanwhile, the AKT phosphorylation level was reduced by CTRP6 silencing. Next, Hep3B cells were pretreated with insulin-like growth factor-1 (IGF-1) (an activator of AKT), and then transfected with CTRP6 siRNA, and the cell vitality, apoptosis, migration, and invasion were measured again. We found that all these alterations caused by CTRP6 inhibition could be reversed by IGF-1 treatment. Taken together, CTRP6 suppression blocked cell survival, migration, and invasion and promoted cell apoptosis through inactivating the AKT signaling pathway. Our findings present a novel potential molecular target for HCC therapy.     

Coordination of Rho and Rac GTPase function via p190B RhoGAP

The Rac GTPase regulates Rho signaling in a broad range of physiological settings and in oncogenic transformation [1-3]. Here, we report a novel mechanism by which crosstalk between Rac and Rho GTPases is achieved. Activated Rac1 binds directly to p190B Rho GTPase-activating protein (RhoGAP), a major modulator of Rho signaling. p190B colocalizes with constitutively active Rac1 in membrane ruffles. Moreover, activated Rac1 is sufficient to recruit p190B into a detergent-insoluble membrane fraction, a process that is accompanied by a decrease in GTP-bound RhoA from membranes. p190B is recruited to the plasma membrane in response to integrin engagement [4]. We demonstrate that collagen type I, a potent inducer of Rac1-dependent cell motility in HeLa cells, counteracts cytoskeletal collapse resulting from overexpression of wild-type p190B, but not that resulting from overexpression of a p190B mutant specifically lacking the Rac1-binding sequence. Furthermore, this p190B mutant exhibits dramatically enhanced RhoGAP activity, consistent with a model whereby binding of Rac1 relieves autoinhibition of p190B RhoGAP function. Collectively, these observations establish that activated Rac1, through direct interaction with p190B, modulates subcellular RhoGAP localization and activity, thereby providing a novel mechanism for Rac control of Rho signaling in a broad range of physiological processes.     

Expression of human‐specific ARHGAP11B in mice leads to neocortex expansion and increased memory flexibility

Neocortex expansion during human evolution provides a basis for our enhanced cognitive abilities. Yet, which genes implicated in neocortex expansion are actually responsible for higher cognitive abilities is unknown. The expression of human‐specific ARHGAP11B in embryonic/foetal mouse, ferret and marmoset neocortex was previously found to promote basal progenitor proliferation, upper‐layer neuron generation and neocortex expansion during development, features commonly thought to contribute to increased cognitive abilities. However, a key question is whether this phenotype persists into adulthood and if so, whether cognitive abilities are indeed increased. Here, we generated a transgenic mouse line with physiological ARHGAP11B expression that exhibits increased neocortical size and upper‐layer neuron numbers persisting into adulthood. Adult ARHGAP11B‐transgenic mice showed altered neurobehaviour, notably increased memory flexibility and a reduced anxiety level. Our data are consistent with the notion that neocortex expansion by ARHGAP11B, a gene implicated in human evolution, underlies some of the altered neurobehavioural features observed in the transgenic mice, such as the increased memory flexibility, a neocortex‐associated trait, with implications for the increase in cognitive abilities during human evolution.     

Recent progress in the emerging role of exosome in hepatocellular carcinoma

Exosomes are small membrane vesicles 50‐150 nm in diameter released by a variety of cells, which contain miRNAs, mRNAs and proteins with the potential to regulate signalling pathways in recipient cells. Exosomes deliver nucleic acids and proteins to participate in orchestrating cell‐cell communication and microenvironment modulation. In this review, we summarize recent progress in our understanding of the role of exosomes in hepatocellular carcinoma (HCC). This review focuses on recent studies on HCC exosomes, considering biogenesis, cargo and their effects on the development and progression of HCC, including chemoresistance, epithelial‐mesenchymal transition, angiogenesis, metastasis and immune response. Finally, we discuss the clinical application of exosomes as a therapeutic agent for HCC.     

Circular RNA circFBXO11 modulates hepatocellular carcinoma progress and oxaliplatin resistance through miR‐605/FOXO3/ABCB1 axis

Increasing findings suggest the critical role of circular RNA (circRNA) in human cancer, and chemotherapy resistance is a poor prognostic factor for hepatocellular carcinoma (HCC). The function of circRNA in the HCC oxaliplatin (OXA) resistance remains largely unknown. In this study, we found that circRNA circFBXO11 was significantly up‐regulated in HCC tissues, and the circFBXO11 overexpression was associated with poor prognosis. CircFBXO11 was found to promote the HCC proliferation, cycle progress and OXA resistance. Mechanistically, circFBXO11 was predominantly localized in the cytoplasm and harboured the miR‐605, thereby targeting FOXO3 protein. Furthermore, FOXO3 targeted the promoter region of ABCB1 to accelerate its expression. In conclusion, this research reveals the role of circFBXO11/miR‐605/FOXO3/ABCB1 axis in the HCC OXA resistance, providing new insight for circRNA‐based diagnostic and therapeutic strategies.