MiR-181a promotes growth of thyroid cancer cells by targeting tumor suppressor RB1

OBJECTIVE

MicroRNAs (miRs) are critical regulators in cancer development and progression. The current study aimed to investigate the expression and potential function of miR-181a in thyroid cancer.

PATIENTS AND METHODS

A total of 15 paired thyroid cancer tissues and adjacent normal tissues were subjected to Real-time Polymerase Chain Reaction (PCR) to evaluate miR-181a expression. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, enzyme linked immunosorbent assay (ELISA) or flow cytometry was employed to assess the growth activity, apoptosis and cell cycle, respectively, upon modulation of the miR-181a expression in TPC-1 cells. Western blot was used to assess protein expression. The interaction between miR-181a and RB1 was tested by luciferase activity assay.

RESULTS

The expression of miR-181a was significantly upregulated in thyroid cancer tissues compared with the adjacent tissues. Inhibition of miR-181a attenuated cell growth, which could be abrogated by miR-181a co-transfection. MiR-181a overexpression reduced apoptosis and promoted cell cycle progression; inhibition of miR-181a exerted opposite effects on both cell cycle and apoptosis. MiR-181a directly suppressed RB1 expression. RB1 expression in tumor tissues was downregulated and negatively correlated with miR-181a expression.

CONCLUSIONS

miR-181a plays an oncogenic role in thyroid cancer; by targeting RB1, it promotes cell cycle progression and inhibits apoptosis.

An absorbed dose map of bone tissue treated with a radiopharmaceutical in vivo

A beagle humerus treated with Ho-chelate radiopharmaceutical in vivo was examined by electron paramagnetic resonance (EPR) dosimetry. The bone was sectioned and the absorbed dose to each bone fragment was determined by additive re-irradiation of the bone tissue with calibrated doses of gamma radiation. The measured doses ranged from 4.3 Gy to 62 Gy. The highest doses were recorded in the predominately trabecular bone tissue and the lowest doses in the predominately cortical bone tissue. The mean absorbed dose for the entire bone was 17 Gy. The data from 50 bone fragments were combined to create an absorbed dose map of the interior bone surface.

Plasmons in the metallic nanoparticle-film system as a tunable impurity problem

We show that the plasmon resonances of a metallic nanoparticle interacting with the surface plasmons of a metallic film is an electromagnetic analogue of the spinless Anderson-Fano model. This is the same model used to describe the interaction of a localized electronic state with a continuous band of electronic states. The three characteristic regimes of this model are realized here, where the energy of the nanoparticle plasmon resonance lies above, within, or below the energy band of surface plasmon states. These three interaction regimes are controlled by film thickness. The latter regime is experimentally observed and identified.

The role of disulfide-linked dimerization in interleukin-3 receptor signaling and biological activity

Cysteine residues 86 and 91 of the beta subunit of the human interleukin (hIL)-3 receptor (hbetac) participate in disulfide-linked receptor subunit heterodimerization. This linkage is essential for receptor tyrosine phosphorylation, since the Cys-86 --> Ala (Mc4) and Cys-91 --> Ala (Mc5) mutations abolished both events. Here, we used these mutants to examine whether disulfide-linked receptor dimerization affects the biological and biochemical activities of the IL-3 receptor. Murine T cells expressing hIL-3Ralpha and Mc4 or Mc5 did not proliferate in hIL-3, whereas cells expressing wild-type hbetac exhibited rapid proliferation. However, a small subpopulation of cells expressing each mutant could be selected for growth in IL-3, and these proliferated similarly to cells expressing wild-type hbetac, despite failing to undergo IL-3-stimulated hbetac tyrosine phosphorylation. The Mc4 and Mc5 mutations substantially reduced, but did not abrogate, IL-3-mediated anti-apoptotic activity in the unselected populations. Moreover, the mutations abolished IL-3-induced JAK2, STAT, and AKT activation in the unselected cells, whereas activation of these molecules in IL-3-selected cells was normal. In contrast, Mc4 and Mc5 showed a limited effect on activation of Erk1 and -2 in unselected cells. These data suggest that whereas disulfide-mediated cross-linking and hbetac tyrosine phosphorylation are normally important for receptor activation, alternative mechanisms can bypass these requirements.

A cell type-specific constitutive point mutant of the common beta-subunit of the human granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-3, and IL-5 receptors requires the GM-CSF receptor alpha-subunit for activation

The high affinity receptor for human granulocyte-macrophage colony-stimulating factor (GM-CSF) consists of a cytokine-specific alpha-subunit (hGMRalpha) and a common signal-transducing beta-subunit (hbetac) that is shared with the interleukin-3 and -5 receptors. We have previously identified a constitutively active extracellular point mutant of hbetac, I374N, that can confer factor independence on murine FDC-P1 cells but not BAF-B03 or CTLL-2 cells (Jenkins, B. J., D'Andrea, R. J., and Gonda, T. J. (1995) EMBO J. 14, 4276-4287). This restricted activity suggested the involvement of cell type-specific signaling molecules in the activation of this mutant. We report here that one such molecule is the mouse GMRalpha (mGMRalpha) subunit, since introduction of mGMRalpha, but not hGMRalpha, into BAF-B03 or CTLL-2 cells expressing the I374N mutant conferred factor independence. Experiments utilizing mouse/human chimeric GMRalpha subunits indicated that the species specificity lies in the extracellular domain of GMRalpha. Importantly, the requirement for mGMRalpha correlated with the ability of I374N (but not wild-type hbetac) to constitutively associate with mGMRalpha. Expression of I374N in human factor-dependent UT7 cells also led to factor-independent proliferation, with concomitant up-regulation of hGMRalpha surface expression. Taken together, these findings suggest a critical role for association with GMRalpha in the constitutive activity of I374N.

Muscarinic m4 receptor activation by some atypical antipsychotic drugs

To clarify the findings that clozapine is both a muscarinic receptor agonist and antagonist, we examined the effects of neuroleptics on forskolin-stimulated cAMP accumulation in Chinese hamster ovary cells expressing human muscarinic m4 receptors (CHO-hm4) and in rat striatum. With CHO-hm4 cells, clozapine induced a concentration-dependent and atropine-sensitive inhibition on cAMP formation, with EC50 = 60 nM and Emax = 74% of carbachol maximum. Other atypical neuroleptics, fluperlapine, tenilapine and olanzapine, were similar but less potent, while risperidone, rilapine, quetiapine (ICI 204,636), sertindole, and ziprasidone had almost no effect. Typical neuroleptics, haloperidol, chlorpromazine, fluphenazine, thiothixene, thioridazine, and molindone, showed either no effect or an atropine-resistant inhibition of cAMP formation. However, in rat striatal tissues, clozapine, up to 10 microM, did not show a significant inhibition of cAMP formation, probably due to a relatively low abundance of muscarinic m4 receptors and the presence of multiple types of muscarinic and other receptors, with which clozapine interacts. Nevertheless, muscarinic m4 receptor agonism, to some extent, may be a relevant mechanism for the therapeutic efficacy and side effects of clozapine and some atypical neuroleptics.

Characterization of the genomic structure, promoter region, and a tetranucleotide repeat polymorphism of the human neurotensin receptor gene

In the present study, we have cloned the human neurotensin receptor (NTR) gene, determined its structure, demonstrated that its promoter is functional in transfection experiments, and identified the start site of transcription and a tetranucleotide repeat polymorphism that locates at less than 3 kilobase pairs from the gene. The gene contains three introns, all in the coding regions. Several differences in genomic clones and previously characterized cDNA sequences are reconciled. The 5' regulatory region, which is rich in presumptive transcription factors, can drive luciferase expression in transfected CHO-K1 cells. Stepwise 5' deletions identify a positive modulator between -782 and -1309 and a negative modulator between -1309 and -1563. Southern blot analyses demonstrate a single copy gene for the NTR. The tetranucleotide repeat polymorphism is highly informative with at least 23 alleles and might serve as a very useful marker for genetic study of the relationship between the NTR and neuropsychiatric disorders.

Characterization and chromosomal localization of the human A2a adenosine receptor gene: ADORA2A

The gene for the stimulatory G protein-coupled human A2a adenosine receptor was isolated and sequence analysis revealed two exons that are interrupted by an intron of approximately 6.4 kb. An intron is located in the same region in the human A1 and A2b adenosine receptor genes. Comparison of the A2a genomic and cDNA sequences reveals two nucleotide differences in the coding region and the presence of an aberrant sequence in the 5'208 base pairs of the A2a cDNA including a polymorphism in the third base of codon Tyr-361 and Gly codon which was always detected at residue 392, indicated that the Arg codon present in the cDNA may be an artifact. Fluorescent in situ hybridization and PCR analysis of human-hamster hybrid cell panels shows that the A2a receptor gene is localized to chromosome 22q11.2. This is in contrast with previous reports (subsequently retracted) which mapped the A2a gene to chromosome 11q11-13.

Exclusion of close linkage of bipolar disorder to the Gs-alpha subunit gene in nine Australian pedigrees

Growing evidence suggests that guanine nucleotide binding proteins (G proteins) may be involved in both the pathogenesis and treatment of bipolar affective disorder. Both overactive G proteins and increased levels of the alpha subunit of the stimulatory form (Gs-alpha) have been demonstrated in peripheral leucocytes of manic patients while an increase of Gs-alpha subunit levels has also been found in a postmortem study of bipolar disorder. The function of Gs and Gi alpha subunits has now been shown to be affected by lithium. The present study aimed to determine whether bipolar affective disorder was linked to the Gs-alpha subunit gene which has been mapped to chromosomal region 20q13.2. Linkage analysis utilized the PCR amplification of a portion of the Gs-alpha gene that contains a dinucleotide repeat (CA repeat) polymorphism. Linkage of bipolar disorder and recurrent depression to the Gs-alpha subunit gene was tested using a series of autosomal dominant and recessive models with varying penetrance levels. Additionally, linkage was examined using a series of levels of definitions of affective illness. Close linkage to the Gs-alpha subunit gene was strongly excluded using each model and definition. Thus, our study indicates that a genetic defect in the Gs-alpha subunit gene is unlikely to be the cause of bipolar disorder.

Exclusion of close linkage of bipolar disorder to the dopamine D3 receptor gene in nine Australian pedigrees

The recently cloned dopamine D3 receptor (DRD3) gene is of potential relevance to the aetiology of bipolar disorder because of an almost exclusive expression in limbic tissue, the region of the brain putatively responsible for control of emotion. We therefore aimed to determine whether bipolar disorder in nine pedigrees (with 171 members) was linked to this receptor gene, which has been mapped to chromosomal region 3q 13.3. Linkage of bipolar disorder and recurrent depression to the DRD3 gene was tested using a series of autosomal dominant and recessive models with varying penetrance levels. Additionally, linkage was examined using a series of levels of definitions of affective illness (ranging from bipolar I alone to all affective disorders). Close linkage to the DRD3 gene was strongly excluded using each model and definition, and these conclusions persisted when a wide range of rates of 'sporadic' (non-genetic) presentations of illness were incorporated in the analysis.

Involvement of gamma-aminobutyric acid and N-methyl-D-aspartate receptors in the inhibitory effect of ethanol on pentylenetetrazole-induced c-fos expression in rat brain

The expression of c-fos mRNA in rat brain was induced by intraperitoneal administration of pentylenetetrazole (PTZ) and picrotoxin, which act on the picrotoxin binding site of the gamma-aminobutyric acid-benzodiazepine (GABA-BZ) receptor complex, by N-methyl-D-aspartate (NMDA) and kainic acid, agonists of different classes of glutamate receptors and by caffeine, an antagonist of adenosine receptors. The actions of PTZ and picrotoxin but not that of NMDA were blocked by ethanol and the NMDA-receptor antagonist, MK-801. Ro 15-4513 partially reversed the inhibitory effect of ethanol on PTZ-induced c-fos mRNA synthesis. Acute ethanol administration blocked the actions of PTZ and NMDA without affecting the response to kainic acid or caffeine. Taken together, these data suggest that ethanol blocks c-fos gene activation by noncompetitive antagonists of the GABA-BZ receptor via actions on both the NMDA and GABA receptors.

[Isolated atrial fibrillation. The risk of embolism and its prevention]

Whether or not atrial fibrillation is alone, if not idiopathic, is difficult to determine. The risk of embolization in lone atrial fibrillation is distinctly higher in healthy subjects over 60 years of age when the left atrium is dilated. In chronic atrial fibrillation this risk is higher than in paroxysmal fibrillation, especially within the year following the onset of the arrhythmia. In most patients anticoagulant therapy is effective in the primary or secondary prevention of embolic accidents. In subjects older than 75 aspirin given in daily doses of 325 mg seems to give similar results. The risk of antithrombosis therapy must not be underevaluated. The alternative is to maintain or restore the sinus rhythm, even at an advanced age, if the arrhythmia is recent and the left atrium is moderately dilated.

Acute administration of ethanol suppresses pentylenetetrazole-induced c-fos expression in rat brain

The effect of acute ethanol administration on pentylenetetrazole-induced c-fos expression in rat brain was studied. Pentylenetetrazole induced the rapid and transient expression of c-fos mRNA in rat brain. Maximal induction at a dose of 30 mg/kg was detected within 30 min and persisted for 60 min. Thereafter c-fos gene expression decreased to control levels by 180 min. No increase in c-fos mRNA was evident at doses of pentylenetetrazole less than or equal to 20 mg/kg, whereas maximal elevation was seen at 30 to 40 mg/kg. This action was inhibited by acute ethanol treatment (blood alcohol level greater than or equal to 100 mg/dl). Acute ethanol treatment alone had no effect on c-fos gene expression.