Overexpression of miR-297b-5p in Mouse Insulin-Secreting Cells Promotes Metformin-Mediated Protection Against Stearic Acid-Induced Senescence by Targeting Igf1r

BACKGROUND

A long-term consumption of saturated fat significantly increases the concentration of saturated fatty acids in serum, which accelerates the appearance of senescence markers in β-cells and leads to their dysfunction. An understanding of the mechanisms underlying β-cell senescence induced by stearic acid and the exploration of effective agents preventing it remains largely unclear. Here, we aimed to investigate the protective effect of metformin against stearic acid-treated β-cell senescence and to assess the involvement of miR-297b-5p in this process.

METHODS

To identify senescence, we measured senescence-associated β-galactosidase activity and the expression of senescence-related genes. Gain and loss of function approaches were applied to explore the role of miR-297b-5p in stearic acid-induced β-cell senescence. Bioinformatics analysis and a luciferase activity assay were used to predict the downstream targets of miR-297b-5p.

RESULTS

Stearic acid markedly induced senescence and suppressed miR-297b-5p expression in mouse β-TC6 cells, which were significantly alleviated by metformin. After transfection of miR-297b-5p mimics, stearic acid-evoked β-cell senescence was remarkably prevented. Insulin-like growth factor-1 receptor was identified as a direct target of miR-297b-5p. Inhibition of the insulin-like growth factor-1 receptor prevented stearic acid-induced β-cell senescence and dysfunction. Moreover, metformin alleviates the impairment of the miR-297b-5p inhibitor in β-TC6 cells. Additionally, long-term consumption of a high-stearic-acid diet significantly increased senescence and reduced miR-297b-5p expression in mouse islets.

CONCLUSIONS

These findings imply that metformin alleviates β-cell senescence by stearic acid through upregulating miR-297b-5p to suppress insulin-like growth factor-1 receptor expression, thereby providing a potential target to not only prevent high fat-diet-induced β-cell dysfunction but also for metformin therapy in type 2 diabetes.

Inhibition of miR-146a-5p and miR-8114 in Insulin-Secreting Cells Contributes to the Protection of Melatonin against Stearic Acid-Induced Cellular Senescence by Targeting Mafa

BACKGRUOUND

Chronic exposure to elevated levels of saturated fatty acids results in pancreatic β-cell senescence. However, targets and effective agents for preventing stearic acid-induced β-cell senescence are still lacking. Although melatonin administration can protect β-cells against lipotoxicity through anti-senescence processes, the precise underlying mechanisms still need to be explored. Therefore, we investigated the anti-senescence effect of melatonin on stearic acid-treated mouse β-cells and elucidated the possible role of microRNAs in this process.

METHODS

β-Cell senescence was identified by measuring the expression of senescence-related genes and senescence-associated β-galactosidase staining. Gain- and loss-of-function approaches were used to investigate the involvement of microRNAs in stearic acid-evoked β-cell senescence and dysfunction. Bioinformatics analyses and luciferase reporter activity assays were applied to predict the direct targets of microRNAs.

RESULTS

Long-term exposure to a high concentration of stearic acid-induced senescence and upregulated miR-146a-5p and miR- 8114 expression in both mouse islets and β-TC6 cell lines. Melatonin effectively suppressed this process and reduced the levels of these two miRNAs. A remarkable reversibility of stearic acid-induced β-cell senescence and dysfunction was observed after silencing miR-146a-5p and miR-8114. Moreover, V-maf musculoaponeurotic fibrosarcoma oncogene homolog A (Mafa) was verified as a direct target of miR-146a-5p and miR-8114. Melatonin also significantly ameliorated senescence and dysfunction in miR-146a-5pand miR-8114-transfected β-cells.

CONCLUSION

These data demonstrate that melatonin protects against stearic acid-induced β-cell senescence by inhibiting miR-146a- 5p and miR-8114 and upregulating Mafa expression. This not only provides novel targets for preventing stearic acid-induced β-cell dysfunction, but also points to melatonin as a promising drug to combat type 2 diabetes progression.

Comparative analysis of circRNA expression profile and circRNA-miRNA-mRNA regulatory network between palmitic and stearic acid-induced lipotoxicity to pancreatic β cells

Chronic exposure to high concentrations of circulating palmitic acid and stearic acid leads to impaired β cell function, which accelerates the development of type 2 diabetes. However, differences in the mechanisms underlying this process between these two saturated fatty acids remain largely unknown. In this study, we screened for potential circular RNAs (circRNAs) and their associated regulatory pathways in palmitic acid- and stearic acid-induced mouse β-TC6 cell dysfunction. CircRNA high-throughput sequencing, gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes analysis were performed and co-expression and competing endogenous RNAs (ceRNA) networks were constructed. We identified that four circRNAs that were differentially expressed specifically in β cells exposed to palmitic acid, whereas four circRNAs were differentially expressed specifically in β cells exposed to stearic acid. Seven circRNAs were differentially co-expressed in palmitic acid- and stearic acid-treated β cells. In pathway exploration, we identified the core protein Solute carrier family 2 member 2 (SLc2a2), which is mainly involved in insulin resistance, maturity onset diabetes of the young and type 2 diabetes. The expressions of key circRNAs in β-TC6 cells were validated by Real time quantitative PCR, with a consistent result in high-throughput sequencing. The findings aid our understanding of the mechanisms governing the difference between palmitic acid- and stearic acid-induced β cell dysfunction and provide potential therapeutic targets for developing treatments against long-term high fat diet-induced β cell injury.

Abbreviations: Acvr1c: Activin A receptor, type 1C; CeRNA, Competing endogenous RNAs; circRNA, circular RNA; DEcircRNA: Differentially Expressed circular RNA; DEmiRNA: Differentially Expressed microRNA; DEmRNA: Differentially Expressed mRNA; GO: Gene Ontology; HPDHigh Palmitic acid Diet; HSD: High Stearic acid Diet; KEGG: Kyoto Encyclopedia of Genes and Genomes; miRNA: microRNA; ncRNAs: non-coding RNAs; qPCR: Real time quantitative PCRS; FAs: Saturated Fatty Acids; SLc2a2: Solute carrier family 2 member 2; T2D: Type 2 Diabetes

Propranolol induces apoptosis of human umbilical vein endothelial cells through downregulation of CD147

BACKGROUND

Infantile haemangiomas (IHs) are benign tumours in infancy. Most patients suffering from IHs do not require treatment. However, if there is a dramatic aesthetic or functional impairment, treatment is needed. Currently the most promising therapy for complicated IHs is the oral administration of propranolol, but its mechanism is unclear.

OBJECTIVES

To investigate the role of CD147 in propranolol-induced apoptosis in human umbilical vein endothelial cells (HUVECs).

METHODS

Human umbilical vein endothelial cells were treated with propranolol, and the treatment effects were investigated through the following methodology. (i) Cell proliferation and apoptosis were detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometric analysis. (ii) The expression level of CD147 was measured by reverse-transcription polymerase chain reaction and Western blotting. (iii) HUVECs were transfected with lentivirus encoding CD147 short hairpin (sh)RNA or CD147 cDNA. Ensuing changes in cell proliferation and apoptosis after transfection were measured using the MTT assay and flow cytometry. (iv) The level of phosphorylation of Bcl-2-associated death promoter (BAD) at Ser112 in HUVECs after propranolol treatment and/or CD147 shRNA transfection was detected by Western blotting.

RESULTS

Propranolol inhibited cell proliferation and induced apoptosis in HUVECs. It decreased CD147 protein expression in a concentration-dependent manner. Knocking down CD147 not only induced apoptosis but also exacerbated the apoptosis triggered by propranolol in HUVECs. Overexpression of CD147 can protect HUVECs from apoptosis and propranolol-induced apoptosis. Furthermore, knockdown of both propranolol and CD147 can downregulate Ser112 phosphorylation of BAD, indicating that propranolol and CD147 induce apoptosis in HUVECs through the same signalling transduction pathway.

CONCLUSIONS

Our studies demonstrate that propranolol-induced apoptosis may be mediated through the downregulation of CD147 in HUVECs. This study highlights a novel step in propranolol action and suggests a potential new target for the treatment of IHs.

Abstract A44: Minority enrollment to clinical trials: Experience at the Dan L. Duncan Cancer Center

Background: The Dan L Duncan Cancer Center (DLDCC) is located in Houston, Texas, and provides care to uninsured and minority patients in several large hospitals including Ben Taub General Hospital, The Michael E. DeBakey VA Medical Center, and Texas Children's Hospital. The catchment area for the DLDCC is Harris County, an urban area with a population of nearly 4 million; approximately 18% of county residents are African American and 39% are Hispanic. While the percentage of African Americans in Harris County is nearly equal in all age groups, Hispanics make up nearly 45% of residents less than 30 years old, but only 10% of residents over 60, those most likely to develop cancer. One-third of the county population has no health insurance.

Objective: In 2006 the DLDCC set out to increase overall enrollment to therapeutic clinical trials while maintaining enrollment of patients belonging to racial and ethnic minorities.

Methods: A four-pronged strategy was used to maintain and improve accrual of racial and ethnic minority patients to cancer-related clinical trials while increasing overall accrual. First, the DLDCC invested significant resources in establishing research infrastructure in the hospitals including hiring bilingual coordinators and nurses, translating consents into Spanish, and underwriting the cost for conduct of NCI-sponsored trials. Second, the DLDCC partnered with hospitals to make office space available for research personnel, to provide discounted investigational pharmacy services and to obtain access to laboratory and imaging data and pathology samples. Third, the DLDCC introduced programs to make minority residents aware of clinical trials and build relationships and trust in the community including the establishment of a community advisory board, sponsorship of plays by minority playwrights that carry a cancer message, sponsorship of community health events, and creation of clinical trials newsletters and websites. Finally, the DLDCC pioneered and gained IRB approval for a form designed to collect accurate racial and ethnic data from trial participants.

Results: Overall enrollment to DLDCC therapeutic clinical trials increased by more than 50% between 2005/2006 and 2009 to an average of 13.4% of new cancer patients enrolled on trial. In 2009, 16.8% of subjects enrolled to therapeutic trials were African American, and 35.4% were Hispanic. Accrual of minority subjects was equivalent in pediatric and adult programs and on therapeutic and nontherapeutic trials.

Conclusion: Recruitment of pediatric and adult members of underserved minorities to clinical trials is possible with targeted strategies, dedicated research staff, hospital partnership and community involvement.

Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A44.

Influence of humic substances on the migration of237Np,238Pu and241Am in a weak loess aquifer

The influence of humic substances on the migration of radionuclides237Np,238Pu and241Am in a weak loess aquifer was investigated in situ with bisectional experimental columns. The experimental columns were constructed by connecting two undisturbed aquifer medium columns together, and inserted into the aquifer horizontally through holes pre-prepared in the wall of a vertical Experimental Shaft in an Underground Research Facility at the CIRP´s field test site. Quartz containing radionuclides3H,237Np,238Pu and241Am was introduced as point source and plane source at the central parts of the experimental columns, respectively. Outflow water of the experimental columns were collected and3H in the outflows were analyzed for calculating the water flow velocity in the experimental columns. When the experiment was completed, the experimental columns were dismounted and cut into slices and the activities of237Np,238Pu and241Am in the sliced samples were determined.

The water flow velocity in the point source experimental column and in the plane source experimental column was calculated as 1.15±0.05 cm/d and 1.06±0.05 cm/d, respectively. The concentration distribution of237Np,238Pu and241Am in the experimental columns indicate that, adjacent to the source, the concentration of each radionuclide is very large and decreases abruptly as the distance increases. In addition, some other high concentration regions/points were observed. This phenomenon may suggest that multiple species of these radionuclides with different mobility may exist in the in-situ aquifer condition. The calculated apparent distribution coefficients (Kd, ml/g) of the main specie of these radionuclides with and without additional humic substances are 8.90×101and 8.90×102for237Np, 1.93×102and 9.48×102for238Pu, 7.60×102and 9.79×102for241Am, respectively. These data suggest that the introduction of additional humic substances into the aquifer may enhance the mobility of237Np and238Pu, while it has no obvious influence on the migration of241Am.

The migration of radionuclides237Np,238Pu and241Am in a weak loess aquifer: A field column experiment

The migration of radionuclides237Np,238Pu and241Am in a weak loess aquifer were investigated in-situ with a bisectional experimental column. The experimental column was constructed by connecting 2 undisturbed aquifer medium columns together and inserted into the aquifer horizontally through holes pre-prepared in the wall of a vertical experimental shaft in an Underground Research Facility at the CIRP´s field test site. Quartz containing radionuclides3H,237Np,238Pu and241Am was introduced as a point source at the center of the experimental column. Outflow water of the experimental column was collected and3H in the outflow was determined for calculating the water flow velocity through the experimental column. The experimental column was cut into slices of 0.3 cm long and the radioactivity of237Np,238Pu and241Am in the sliced soil samples was analyzed when the experiment was completed.

The water flow velocity in the experimental column was calculated as 1.15±0.05 cm/d. The activity distribution of237Np,238Pu and241Am in the experimental column indicate that each radionuclide has a very strong activity distribution region adjacent to the source introduction point and decreases abruptly as the distance increases. In addition there are other secondary activity distribution regions with different strength and widths. The calculated apparent distribution coefficients of the main specie of these radionuclides is (8.90±1.51)×102ml/g for237Np, (9.48±1.61)×102ml/g for238Pu and (9.79±1.66)×102ml/g for241Am.

Prenatal molecular diagnosis of beta-thalassemia: report on the first two cases in Romania

Thalassaemia major is a classical example of a disease that can be prevented by prenatal diagnosis. In Romania there are currently 300 patients with thalassaemia major under the management of specialized institutions. Prenatal diagnoses of thalassemia have offered a new dimension to the prevention of this disease, but in order to implement prenatal diagnosis, knowledge of mutations and of their incidence is essential. Molecular testing using Denaturing Gradient Gel Electrophoresis (DGGE) scanning and direct mutation detection with Amplificaton Refractory Mutation System-PCR (ARMS-PCR) and Restriction endonuclease Analysis of PCR fragments (PCR-RFLP) was performed by using amplified DNA from amniotic cells samples, while mutations in the parents were determined in advance. Using our experience in molecular diagnosis, we were able to perform the first prenatal diagnosis for two young couples at risk for thalassaemia major. Foetal samplings were collected by amniocentesis and chorionic villus sampling in the second trimester of the pregnancies. Maternal contamination of the foetal DNA was ruled out by STR genotyping. The prenatal diagnosis revealed affected foetuses with homozygous status of beta-thalassemia major. The IVSI-110 (G-A)/IVS II-745 (C-G) genotype in the first case foetus and ed 8 (-AA)/cd 8 (-AA) in the second case foetus were reported. The results of this study point to a successful future prenatal diagnosis of beta-thalassnemia in Romania, using a rapid and accurate molecular method. Together with the implementation of proper preventive health measures and the education of parents regarding their carrier status, we are hoping that this method will be used as the common application approach to decrease the incidence of thalassacmia major.

Quantitation of the mass of fatty acid ethyl esters synthesized by Hep G2 cells incubated with ethanol

Fatty acid ethyl esters (FAEE), esterification products of fatty acids and ethanol, have been increasingly implicated as mediators of ethanol-induced organ damage. The first goal of this study was to determine the mass of FAEE synthesized by Hep G2 cells exposed to a given dose of ethanol. The second goal was to determine whether all fatty acids in cells are equally available for FAEE synthesis. Hep G2 cells and essential fatty acid deficient Hep G2 cells (Hep G2-EFD) were used to study the synthesis of FAEE upon exposure to ethanol. A two-pool fatty acid model was created: (1) a "previously incorporated pool" formed by incubating the cells with 14C-labeled fatty acids for 24 hr; and (2) a "newly incorporated pool" formed by incubating cells with 3H-labeled fatty acids for 0.5 hr. The FAEE production from each pool was then determined. The total production of FAEE within 3 hr by Hep G2 cells in culture was 150 to 250 pmol/mg cell protein. The fatty acids most recently incorporated into the cells were preferred as substrates for FAEE synthesis because a higher percentage of fatty acids from the newly incorporated pool was used for FAEE synthesis than from the previously incorporated pool. Furthermore, a dose-response relationship was observed between the amount of fatty acid in the newly incorporated pool and FAEE production, but not between the amount of fatty acid in the previously incorporated pool and FAEE synthesis. Taken together, the results indicate that a relatively small amount of endogenously synthesized FAEE is generated from specific intracellular pools of fatty acid since not all fatty acids are equally available for FAEE synthesis. This indicates that if endogenous FAEE are toxic, they exert their toxic effect at very low intracellular FAEE concentrations.

Ethyl palmitate and ethyl oleate are the predominant fatty acid ethyl esters in the blood after ethanol ingestion and their synthesis is differentially influenced by the extracellular concentrations of their corresponding fatty acids

The possibility that fatty acid ethyl esters (FAEEs), esterification products of fatty acids and ethanol, are mediators of ethanol-induced organ damage was suggested by an autopsy study in which individuals who died while acutely intoxicated were found to have FAEEs predominantly in the organs damaged by ethanol abuse. We initially observed in human subjects after ethanol consumption that there is a marked preference for the synthesis of ethyl palmitate and ethyl oleate over other FAEEs. To investigate the basis for this relative fatty acid specificity for FAEE synthesis, we used an in vitro system of Hep G2 cells incubated with ethanol. The cells were capable of synthesizing FAEEs upon exposure to ethanol and they showed a preference for synthesis of ethyl palmitate and ethyl oleate, as was found in human plasma after ethanol ingestion. This finding allowed us to explore the metabolic preference for palmitate and oleate for FAEE synthesis at the biochemical level using intact cells. We demonstrated that the preferential selection of palmitate and oleate for FAEE synthesis was not likely to be the result of specificity for palmitate and oleate by FAEE synthase or preferential uptake of palmitate and oleate by Hep G2 cells. In studies to determine whether the preference for ethyl palmitate and ethyl oleate synthesis was a result of higher concentrations of palmitate and oleate in the extracellular medium, we observed that the synthesis of ethyl oleate, ethyl linoleate, and ethyl arachidonate, but not ethyl palmitate, is influenced by the extracellular concentration of its corresponding fatty acid. The results of our studies indicate that ethyl palmitate and ethyl oleate are the predominant ethyl esters synthesized, that there is no preferential uptake or enzyme affinity for their fatty acid precursors to explain the predominance, and that ethyl palmitate synthesis is uniquely unaffected by the concentration of palmitate in the extracellular medium.

Aspects of hydatidosis in the adult population in Banat

An epidemiological study was performed on a lot of 505 adult subjects (over 20 years old) diagnosed with E.granulosus hydatidosis and operated in surgery units in hospitals from such towns as Timişoara, Arad and Reşita (1985-1992). The incidence of hydatid infection was almost uniformly distributed by sexes, being a little higher in rural areas (52.0%); the highest number of cases was reported in Timiş County (63.6%), followed by Caraş-Severin County (21.2%). Hydatidosis was most frequently found in liver (67.5%) and lungs (23.7%) and more rarely in kidneys (0.4%), brain (0.2%), pancreas (0.2%), ovary (0.2%). Secondary hydatidosis was reported on 12.7% of cases and multiple cyst forms in 12.7% of cases. The distribution of cases by age group was relatively balanced, a slightly increased incidence being found in the 20-29 years age group (23.2%), about 1/3 of pulmonary localizations being reported in the age group. Post-surgery complications were reported in 13.5% of the total hepatic localizations and in 30% of the pulmonary localizations. The average number of days in hospital was 29.5 days/case. The average morbidity in the adult population in Banat over an eight years time interval was 5.36%ooo, being higher in Timiş county-7.8%ooo where a peak (11%ooo) was reported in 1987.

[Effect of the T4 on the viscera and embryo of perinatal mice]

58 Female Kun Ming mice of perinatal stage (from the 15th day of pregnacy to the 21th day after birth) were fed with Tripcholorolide (T4) isolated from multiglycosides of Tripterygium wilfordii (GTW) at a doze of 0.6 mg/kg for group 1 or 0.3 mg/kg for group 2 per day for 4 weeks. Lactation was decreased in some females and some F1 off spring died. The succinic dehydrogenase (SDH) activity of the mice liver were increased due to the destruction of its mitocondian. Liver cells degenerated and glycogen decreased. Distal tubules of kidney degenerated. Heart and spleen were normal. T4 was also fed to 10 female mice from the 5th to 17th day of pregnacy. However, neither the absorbed fetus nor dead fetus increased.

[The antifertility effect of gossypol plus testosterone and estrogen]

In order to reduce the side effect of gossypol, gossypol was used in combination with steroid hormones so that the dose of both drugs can be reduced. Silastic capsules containing testosterone (T) + estradiol (E) were implanted under the skin male wister rats for 8 weeks. After removing the implants, testosterone was given orally at the dose of 15 mg.kg-1 which is only 50% of the usual antifertility dose. Mating tests showed that the male rats became infertile. Microscopic examination of the heart, liver and kidneys showed no pathologic changes. The treated rats gained body weight as well as the controls. The fertility of the treated rats recovered four to five weeks after treatment. Thus, gossypol in combination with testosterone and estrogen exhibited a low degree of side effect and high antifertility activity.

[The radiofrequency ablation of Mahaim and Kent fibers during the repair of Ebstein's anomaly]

A young man 20 years old was referred to the Institute with Ebstein anomaly. He had experienced palpitations since the age of eight. Those episodes occurred several times a year. During the electrophysiologic study a regular antidromic reciprocating tachycardia was induced using a right atriofascicular connection (Mahaim). The atrial insertion of the Mahaim fibers was in the right posterolateral atrium. Also another orthodromic supraventricular tachycardia was induced with anterograde conduction over atrioventricular node and retrograde conduction over to canceled atrioventricular right posteroseptal bypass tract (Kent). During surgery to repair Ebstein anomaly we decided to perform radiofrequency catheter ablation of both Mahaim and Kent fibers at the tricuspid annulus in the posteroseptal and lateral regions, eliminating accessory pathways conduction. There were no complications during the procedure. The tachycardia has not recur in a six months period of follow up. No antiarrhythmic drugs has been given.

[The radiofrequency ablation of accessory pathways in 100 consecutive patients with supraventricular tachycardias]

The purpose of this study is to describe the results and the complications of radiofrequency catheter ablation, of accessory pathways in 100 consecutive patients. We had one patient with two pathways. Of the 101 accessory pathways, 56 were overt and 45 concealed. Only 19 patients have had a previous electrophysiology study, in the others, the study and the ablation were performed simultaneously. The location of the accessory pathways were as follows: 61 pathways in the free wall of the left ventricle, 4 in the free wall of the right ventricle, 25 in the left posteroseptal region, 9 in the right posteroseptal region and 2 in the right anteroseptal area. The time required for the diagnostic component of the electrophysiology study, the ablation procedure and the fluoroscopic time was recorded for each patient. Ninety-one of 101 accessory AV connections were successfully ablated (90%). Our success rate for the initial attempt was 87%. We had the opportunity to do a second attempt in only 4 out of 14 patients. The mean time of the procedure, including the electrophysiology test and the ablation was 95.6 %/-55.3 minutes. We have had a recurrence of 9% and 4% of non fatal complications. Radiofrequency catheter ablation can be performed safely and with a high success rate.