Long non-coding RNAs and hepatocellular carcinoma.

Recent advances in next-generation sequencing technology in transcriptome analysis have helped identify numerous non-coding RNAs. The long non-coding RNA (lncRNA) is commonly defined as an RNA molecule with a length of 200 bp-100 kbp that lacks protein-coding potential. LncRNAs play a critical role in the regulation of gene expression, including chromatin modification, transcription and post-transcriptional processing. It has been confirmed that dysregulation of lncRNAs is associated with a number of human diseases, particularly tumors. In this study, we focused on the most extensively investigated lncRNAs in hepatocellular carcinoma (HCC). The biological functions and molecular mechanisms of the majority of lncRNAs have yet to be investigated. The improved knowledge on lncRNAs in HCC may help identify lncRNAs that may be used as novel prognostic markers and therapeutic targets.

[Expression of miRNA-29b and its clinical significances in primary hepatic carcinoma].

OBJECTIVE: To explore the clinical value of miRNA-29b expression and the combined detection of serum miRNA-29b and alpha-fetoprotein (AFP) in the diagnosis of primary hepatic carcinoma(PHC). METHODS: From January 2007 to May 2010, the serum levels of miRNA-29b and AFP from 96 healthy controls and 87 PHC patients were measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) respectively. The relationship of miRNA-29b and various clinical parameters was analyzed. RESULTS: Serum levels of miRNA-29b in PHC pre-operative group (0.250 (0.124 - 0.381)) significantly decreased versus the control group [0.860 (0.587 - 1.338)] and the post-operative group (0.890 (0.637 - 1.414)) (P < 0.001). Also, the levels of AFP in PHC pre-operative group (65.4 (20.1 - 212.3)) was obviously higher than that in the control group (13.3 (7.1 - 19.8)) and the post-operative group (23.2 (11.6 - 55.7)) (P < 0.001). A lower expression of miRNA-29b was correlated with lower differentiation and higher TNM stages (P < 0.045, P < 0.001). Kaplan-Meier curve analysis revealed that PHC patients with a low serum expression of miRNA-29b had a significantly shortened overall survival when compared with a high serum expression of miRNA-29b (25.52 vs 36.94 months, P = 0.008). Multivariable Cox regression analysis indicated that the serum expression of miRNA-29b was an independent risk factor for overall survival. Relative risk was 0.482 (95% confidence interval: 0.236 - 0.985). The critical values for miRNA-29b and AFP were determined at 0.38 and 23.1 µg/L through the ROC curves. Under the critical value, the sensitivity of miRNA-29b and AFP were 75.9% and 70.1% and the specificity of miRNA-29b and AFP 89.5% and 92.7% respectively. Combined detection could increase the sensitivity up to 87.3%, and achieve a specificity of 88.5%. CONCLUSION: The combined detection of miRNA-29b and AFP aids the diagnosis of PHC and the prediction of its prognosis.

Histone deacetylases inhibitor sodium butyrate inhibits JAK2/STAT signaling through upregulation of SOCS1 and SOCS3 mediated by HDAC8 inhibition in myeloproliferative neoplasms.

Constitutive activation of Janus kinase 2/signal transducers and activators of transcription (JAK2/STAT) signaling has an important role in the oncogenesis of myeloproliferative neoplasms (MPNs) and leukemia. Histone deacetylases (HDACs) inhibitors have been reported to possess anticancer activity through different mechanisms. However, whether HDACs inhibitors suppress JAK2/STAT signaling in MPNs is still unknown. In this study, we show that the HDAC inhibitor sodium butyrate (SB) inhibited JAK2/STAT signaling and increased the expression of suppressors of cytokine signaling 1 (SOCS1) and SOCS3, both of which are the potent feedback inhibitors of JAK2/STAT signaling. SB upregulated the expression of SOCS1 and SOCS3 by triggering the promoter-associated histone acetylation of SOCS1 and SOCS3 in K562 and HEL cell lines. Importantly, we found that upon knockdown of each class I HDACs, only knockdown of HDAC8 resulted in the increased expression of SOCS1 and SOCS3. Moreover, overexpression of SOCS1 and SOCS3 significantly inhibited cell growth and suppressed JAK2/STAT signaling in K562 and HEL cells. Furthermore, SB increased the transcript levels of SOCS1 and SOCS3 and inhibited the clonogenic activity of hematopoietic progenitors from patients with MPNs. Taken together, these data establish a new anticancer mechanism that SB inhibits JAK2/STAT signaling through HDAC8-mediated upregulation of SOCS1 and SOCS3. Thus, HDACs inhibitors may have therapeutic potential for the treatment of MPNs.

miR-15a and miR-16-1 inhibit the proliferation of leukemic cells by down-regulating WT1 protein level.

BACKGROUND: miR-15a and miR-16-1(miR-15a/16-1) have been implicated as tumor suppressors in chronic lymphocytic leukemia, multiple myeloma, and acute myeloid leukemic cells. However the mechanism of inhibiting the proliferation of leukemic cells is poorly understood. METHODS: K562 and HL-60 cells were transfected with pRS-15/16 or pRS-E, cell growth were measured by CCK-8 assay and direct cell count. Meanwhile WT1 protein and mRNA level were measured by Western blotting and quantitative real-time PCR. RESULTS: In this study we found that over-expression of miR-15a/16-1 significantly inhibited K562 and HL-60 cells proliferation. Enforced expression of miR-15a/16-1 in K562 and HL-60 cells significantly reduced the protein level of WT1 but not affected the mRNA level. However enforced expression of miR-15a/16-1 can not reduce the activity of a luciferase reporter carrying the 3'-untranslated region(3'UTR) of WT1. Silencing of WT1 by specific siRNA suppressed leukemic cells proliferation resembling that of miR-15a/16-1 over-expression. Anti-miR-15a/16-1 oligonucleotides (AMO) reversed the expression of WT1 in K562 and HL-60 cells. Finally, we found a significant inverse correlation between miR-15a or miR-16-1 expression and WT1 protein levels in primary acute myeloid leukemia (AML) blasts and normal controls. CONCLUSIONS: These data suggest that miR-15a/16-1 may function as a tumor suppressor to regulate leukemic cell proliferation potentially by down-regulating the WT1 oncogene. However WT1 is not directly targeted by miR-15a/16-1 through miRNA-mRNA base pairing, therefore more study are required to understand the mechanism by which miR-15a/16-1 downregulate WT1.

Down-regulation of angiotensin II by shRNA reduces collagen synthesis in hepatic stellate cells.

The angiotensin-converting enzyme 2 (ACE-2), angiotensin II type I receptor (ATIR) antagonists and angiotensin-converting enzyme inhibitors (ACEI) were explored to block the renin-angiotensin-aldosterone system (RAAS). The experimental results were still not satisfactory, mainly due to excessive level of angiotensin II (AngII) in gene expression. RNA interference (RNAi) is a mature gene blocking technique, able to block target gene expression efficiently, specifically and continuously. In this study, we observed the effect of short hairpin RNA (shRNA) expression vectors targeting rat AngII on collagen synthesis in hepatic stellate cells (HSCs). According to rat AngII gene sequences, three AngII targeted shRNA expression vectors were designed and constructed. Using liposomes as transfection reagents, they were transfected into HSC-T6 cells. Enzyme digestion confirmed that the transfected shRNA target gene segment was successfully cloned to the vectors. Compared with the control group, AngII mRNA expression examined in shRNA1, shRNA2 and shRNA3 groups was inhibited by about 37, 30 and 61%, respectively. AngII protein expression in all three groups was also reduced by about 21, 24 and 59%, respectively. Furthermore, we revealed that the inhibitory effect exhibited a dose- and time-dependent relationship. In shRNA3 group, TGF-beta1 mRNA expression was reduced by about 51%. The levels of PIIIP, HA and LN were decreased by about 53, 47 and 58%, respectively. In conclusion, shRNA expression vectors targeting rat AngII can decrease collagen synthesis, which would hopefully serve as a foundation for RNAi study of liver fibrosis in vivo.

The effects of intracellular Ca2+ on cardiac K+ channel expression and activity: novel insights from genetically altered mice.

We tested the hypothesis that chronic changes in intracellular Ca(2+) (Ca(2+)(i)) can result in changes in ion channel expression; this represents a novel mechanism of crosstalk between changes in Ca(2+) cycling proteins and the cardiac action potential (AP) profile. We used a transgenic mouse with cardiac-specific overexpression of sarcoplasmic reticulum Ca(2+) ATPase (SERCA) isoform 1a (SERCA1a OE) with a significant alteration of SERCA protein levels without cardiac hypertrophy or failure. Here, we report significant changes in the expression of a transient outward K(+) current (I(to,f)), a slowly inactivating K(+) current (I(K,slow)) and the steady state current (I(SS)) in the transgenic mice with resultant prolongation in cardiac action potential duration (APD) compared with the wild-type littermates. In addition, there was a significant prolongation of the QT interval on surface electrocardiograms in SERCA1a OE mice. The electrophysiological changes, which correlated with changes in Ca(2+)(i), were further corroborated by measuring the levels of ion channel protein expression. To recapitulate the in vivo experiments, the effects of changes in Ca(2+)(i) on ion channel expression were further tested in cultured adult and neonatal mouse cardiac myocytes. We conclude that a primary defect in Ca(2+) handling proteins without cardiac hypertrophy or failure may produce profound changes in K(+) channel expression and activity as well as cardiac AP.

A negatively charged residue in the outer mouth of rat sodium channel determines the gating kinetics of the channel.

Previous studies using combined techniques of site-directed mutagenesis and electrophysiology of voltage-gated Na(+) channels have demonstrated that there are significant overlaps in the regions that are important for the two fundamental properties of the channels, namely gating and permeation. We have previously shown that a pore-lining residue, W402 in S5-S6 region (P loop) in domain I of the micro1 skeletal muscle Na(+) channel, was important in the gating of the channel. Here, we determined the role of an adjacent pore-lining negatively charged residue (E403) in channel gating. Charge neutralization or substitution with positively charged side chain at this position resulted in a marked delay in the rate of recovery from slow inactivation. Indeed, the fast inactivation process appeared intact. Restoration of the negatively charged side chain with a sulfhydryl modifier, MTS-ethylsulfonate, resulted in a reactivation profile from a slow-inactivated state, which was indistinguishable from that of the wild-type channels. We propose an additional functional role for the negatively charged residue. Assuming no major changes in the pore structure induced by the mutations, the negatively charged residue E403 may work in concert with other pore regions during recovery from slow inactivation of the channel. Our data represent the first report indicating the role of negative charge in the slow inactivation of the voltage-gated Na(+) channel.

Presence of a calcium-activated chloride current in mouse ventricular myocytes.

The properties of several components of outward K(+) currents, including the pharmacological and kinetics profiles as well as the respective molecular correlates, have been identified in mouse cardiac myocytes. Surprisingly little is known with regard to the Ca(2+)-activated ionic currents. We studied the Ca(2+)-activated transient outward currents in mouse ventricular myocytes. We have identified a 4-aminopyridine (4-AP)- and tetraethyl ammonium-resistant transient outward current that is Ca(2+) dependent. The current is carried by Cl(-) and is critically dependent on Ca(2+) influx via voltage-gated Ca(2+) channels and the sarcoplasmic reticulum Ca(2+) store. The current can be blocked by the anion transport blockers niflumic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. Single channel recordings reveal small conductance channels (approximately 1 pS in 140 mM Cl(-)) that can be blocked by anion transport blockers. Ensemble-averaged current faithfully mirrors the transient kinetics observed at the whole level. Niflumic acid (in the presence of 4-AP) leads to prolongation of the early repolarization. Thus this current may contribute to early repolarization of action potentials in mouse ventricular myocytes.