Activation of cyclin E1, a key regulator of the G1/S cell-cycle transition, has been implicated in many cancers including hepatocellular carcinoma (HCC). Although much is known about the regulation of cyclin E1 expression and stability, its post-transcriptional regulation mechanism remains incompletely understood. Here, we report that nuclear factor 90 (NF90), a double-stranded RNA (dsRNA) binding protein, regulates cyclin E1 in HCC. We demonstrate that NF90 is upregulated in HCC specimens and that suppression of NF90 decreases HCC cell growth and delays G1/S transition. We identified cyclin E1 as a new target of NF90 and found a significant correlation between NF90 and cyclin E1 expression in HCC. The mRNA and protein levels of cyclin E1 were downregulated upon NF90 knockdown. Suppression of NF90 caused a decrease in the half-life of cyclin E1 mRNA, which was rescued by ectopic expression of NF90. Furthermore, NF90 bound to the 3′ untranslated regions (3′UTRs) of cyclin E1 mRNA in vitro and in vivo. Knockdown of NF90 also inhibited tumor growth of HCC cell lines in mouse xenograft model. Moreover, we showed that inhibition of NF90 sensitized HCC cells to the cyclin-dependent kinase 2 (CDK2) inhibitor, roscovitine. Taken together, downregulation of NF90 in HCC cell lines can delay cell-cycle progression, inhibit cell proliferation, and reduce tumorigenic capacity in vivo. These results suggest that NF90 has an important role in HCC pathogenesis and that it can serve as a novel therapeutic target for HCC.

Aristolochic acid (AA) is the causative agent of urothelial tumors associated with AA nephropathy and is also implicated in the development of Balkan endemic nephropathy‐associated urothelial tumors. These tumors contain AA‐characteristic TP53 mutations. We examined gene expression changes in Hupki (human TP53 knock‐in) mice after treatment with aristolochic acid I (AAI) by gavage (5 mg/kg body weight). After 3, 12 and 21 days of treatment gene expression profiles were investigated using Agilent Whole Mouse 44K Genome Oligo Array. Expression profiles were significantly altered by AAI treatment in both target (kidney) and nontarget (liver) tissue. Renal pathology and DNA adduct analysis confirmed kidney as the target tissue of AAI‐induced toxicity. Gene ontology for functional analysis revealed that processes related to apoptosis, cell cycle, stress response, immune system, inflammatory response and kidney development were altered in kidney. Canonical pathway analysis indicated Nfκb, aryl hydrocarbon receptor, Tp53 and cell cycle signaling as the most important pathways modulated in kidney. Expression of Nfκb1 and other Nfκb‐target genes was confirmed by quantitative real‐time PCR (qRT‐PCR) and was consistent with the induction of Nfκb1 protein. Myc oncogene, frequently overexpressed in urothelial tumors, was upregulated by AAI on the microarrays and confirmed by qRT‐PCR and protein induction. Collectively we found that microarray gene expression analysis is a useful tool to define tissue‐specific responses in AAI‐induced toxicity. Several genes identified such as TP53, Rb1, Mdm2, Cdkn2a and Myc are frequently affected in human urothelial cancer, and may be valuable prognostic markers in future clinical studies.

Introduction Glioblastoma (GBM) is identified as a lethal malignant tumor derived from the nervous system. Despite the standard clinical strategy including maximum surgical resection, temozolomide (TMZ) chemotherapy, and radiotherapy, the median survival of GBM patients remains <15 months. Accumulating evidence indicates that rapid‐acquired radioresistance is one of the most common reasons for GBM recurrence. Therefore, developing novel therapeutic targets for radioresistant GBM could yield long‐term cures. Aims To investigate the functional role of CXCL1 in the acquired radioresistance and identify the molecular pathway correlated to CXCL1. Results In this study, we identified that CXCL1 is highly expressed in GBM and the elevation of CXCL1 is involved in radioresistance and poor prognosis in GBM patients. Additionally, silencing CXCL1 attenuated the proliferation and radioresistance of GBM cells. Furthermore, we demonstrated that CXCL1‐overexpression induced radioresistance through mesenchymal transition of GBM via the activation of nuclear factor‐kappa B (NF‐κB) signaling. Conclusion CXCL1 was highly enriched in GBM and positively correlated with poor prognosis in GBM patients. Additionally, elevated CXCL1 induced radioresistance in GBM through regulation of NF‐κB signaling by promoting mesenchymal transition in GBM.

Globally, a relatively high incidence of KS was found among HIV-seropositive people and, in particular, in HIV-infected MSM. The introduction of HAART has largely prevented the development of KS, but it has not entirely removed the challenge of KS. In Africa, in particular, KS imposes a very heavy disease burden, which can mainly be attributed to the high prevalence of KS-associated herpesvirus and poor access to HAART.

SUMMARYThe first haematopoietic stem cells share a common origin with the dorsal aorta and derive from putative adult haemangioblasts in the dorsal lateral plate (DLP) mesoderm. Here we show that the transcription factor (TF) stem cell leukaemia (Scl/Tal1) is crucial for development of these adult haemangioblasts in Xenopus and establish the regulatory cascade controlling its expression. We show that VEGFA produced in the somites is required to initiate adult haemangioblast programming in the adjacent DLP by establishing endogenous VEGFA signalling. This response depends on expression of the VEGF receptor Flk1, driven by Fli1 and Gata2. Scl activation requires synergy between this VEGFA-controlled pathway and a VEGFA-independent pathway controlled by Fli1, Gata2 and Etv2/Etsrp/ER71, which also drives expression of the Scl partner Lmo2. Thus, the two ETS factors Fli1 and Etv6, which drives the VEGFA expression in both somites and the DLP, sit at the top of the adult haemangioblast gene regulatory network (GRN). Furthermore, Gata2 is initially activated by Fli1 but later maintained by another ETS factor, Etv2. We also establish that Flk1 and Etv2 act independently in the two pathways to Scl activation. Thus, detailed temporal, epistatic measurements of key TFs and VEGFA plus its receptor have enabled us to build a Xenopus adult haemangioblast GRN.

SummaryVEGFA signaling is critical for endothelial and hematopoietic stem cell (HSC) specification. However, blood defects resulting from perturbation of the VEGFA pathway are always accompanied by impaired vascular/arterial development. Because HSCs derive from arterial cells, it is unclear whether VEGFA directly contributes to HSC specification. This is an important question for our understanding of how HSCs are formed and for developing their production in vitro. Through knockdown of the regulator ETO2 in embryogenesis, we report a specific decrease in expression of medium/long Vegfa isoforms in somites. This leads to absence of Notch1 expression and failure of HSC specification in the dorsal aorta (DA), independently of vessel formation and arterial specification. Vegfa hypomorphs and isoform-specific (medium/long) morphants not only recapitulate this phenotype but also demonstrate that VEGFA short isoform is sufficient for DA development. Therefore, sequential, isoform-specific VEGFA signaling successively induces the endothelial, arterial, and HSC programs in the DA.

Introduction Glioblastoma (GBM) is the most lethal primary malignant brain tumor in adults with poor survival due to acquired therapeutic resistance and rapid recurrence. Currently, the standard clinical strategy for glioma includes maximum surgical resection, radiotherapy, and temozolomide (TMZ) chemotherapy; however, the median survival of patients with GBM remains poor despite these comprehensive therapies. Therefore, the identification of new prognostic biomarkers is urgently needed to evaluate the malignancy and long‐term outcome of glioma. Aims To further investigate prognostic biomarkers and potential therapeutic targets for GBM. Results In this study, we identified tribbles pseudokinase 2 (TRIB2) as one of the genes that is most correlated with pathological classification, radioresistance, and TMZ resistance in glioma. Additionally, the expression of mitogen‐activated protein kinase kinase kinase 1 (MAP3K1) showed a strong correlation with TRIB2. Moreover, a combined increase in TRIB2 and MAP3K1 was observed in GBM and indicated a poor prognosis of patients with glioma. Finally, enriched TRIB2 expression and MAP3K1 expression were shown to be associated with resistance to TMZ and radiotherapy. Conclusion Combined elevation of TRIB2 and MAP3K1 could be novel prognostic biomarkers and potential therapeutic targets to evaluate the malignancy and long‐term outcomes of GBM.

Cyclophilin A (CypA) is a member of peptidyl prolyl isomerases (PPIases), which catalyze the cis/trans isomerization of prolyl peptide bonds on the NH-terminal side of Pro residues in peptide chains. Altered expression of CypA has been reported in hepatocellular carcinoma (HCC), but the biological functions of CypA in HCC remain unknown. We found that the level of CypA expression correlated with the metastatic capability of two HCC cell lines, MHCC97-L and MHCC97-H. Stable expression of ectopic CypA in SK-Hep1 cells promotes cell adhesion, motility, chemotaxis, and in vivo lung metastasis, without affecting cell proliferation. We further analyzed microarray results to identify target genes controlled by CypA. Twenty-one genes related to metastasis were altered by CypA over-expression. A member of matrix metalloproteinase, MMP3, was identified by microarray analysis. The regulation of MMP3 and its homologue MMP9 by CypA were further confirmed by quantitative real-time RT-PCR and zymography assay. Taken together, our data suggest that CypA promotes HCC cell metastasis at least partially through up-regulation of MMP3 and MMP9.