OBJECTIVETo investigate the expression of Yin Yang 1 (YY1) protein in human insulinoma and explore its clinical significance.

METHODSNineteen pancreatic neuroendocrine tumor tissue were collected from patients treated in Nanfang Hospital between 2000 and 2014. The protein expression of YY1 in benign and malignant insulinoma tissues were detected by immunohistochemistry.

RESULTSPositive expression for YY1 protein was detected in both benign and malignant tumor tissues, but the malignant tissues had a significantly greater intensity of YY1 expression than the benign tissues (P=0.042). The intensity of YY1 expression was positively correlated with the nature of the tumor, and the insulinomas with high expressions of YY1 had significantly greater malignant potentials (P=0.037).

CONCLUSIONThe high expression of YY1 protein is associated with the development of insulinima. YY1 may serve as a new tumor marker for detecting the malignant transformation of insulinoma.

Biomarkers, Tumor ; metabolism ; Cell Transformation, Neoplastic ; Humans ; Immunohistochemistry ; Insulinoma ; genetics ; metabolism ; Pancreatic Neoplasms ; genetics ; metabolism ; YY1 Transcription Factor ; genetics ; metabolism

Animals ; Carrier Proteins ; genetics ; metabolism ; Cell Line, Tumor ; Insulinoma ; genetics ; metabolism ; pathology ; Mice ; Neoplasm Proteins ; genetics ; metabolism ; Pancreatic Neoplasms ; genetics ; metabolism ; pathology ; Phosphoproteins ; genetics ; metabolism

Insulinoma-associated protein-2 (IA-2) is a transmembrane glycoprotein belonging to the tyrosine phosphatase-like protein family as well as an important autoantigen in the diagnosis of type 1 diabetes. IA-2 products have been marketed in Europe and the United States. At present, commercially available IA-2 antigens are either the recombinant IA-2ic domain or the IA-2 naturally extracted from bovine islets. However, the recombinant IA-2 antigen displays weak positive in clinic practice, which often results in occasional detection failures, thus cannot completely replace the naturally extracted IA-2 antigen. In this study, an HEK293 expression system was used to explore the production of recombinant IA-2. An IA-2 transmembrane fragment (IA-2 TMF) located at amino acid position 449-979, also known as the natural membrane protein form of IA-2, was produced in HEK293 through transfection, and both the expression conditions and dissolution conditions of the membrane protein were also optimized. The purified membrane protein yield was 0.78 mg/L cell culture. Subsequently, the antigen activity of IA-2 TMF was compared with RSR rhIA-2 through enzyme linked immunosorbent assay. The serum of 77 type 1 diabetes patients and 32 healthy volunteers were detected. Receiver operating characteristic curve (ROC) curve was used to characterize the sensitivity and specificity of the test results. The results showed that the sensitivity of IA-2 TMF was 71.4% (55/77), while the sensitivity of RSR rhIA-2 was 63.6% (49/77), and the specificity of both antigens were all 100%. There was no significant difference in specificity between the two antigens, but the sensitivity of IA-2 TMF was appreciably better than that of the imported gold standard RSR rhIA-2 antigen. In conclusion, the recombinant IA-2 TMF produced in HEK293 cells can be used as a raw material to develop in vitro diagnostic reagents for type 1 diabetes.
Humans ; Animals ; Cattle ; HEK293 Cells ; Insulinoma ; Diabetes Mellitus, Type 1/genetics* ; Recombinant Proteins ; Membrane Proteins ; Pancreatic Neoplasms

The study was designed to examine the effect of glucose on the expression of c-myc gene in cultured RINm5F cells. After monolayer culture was established in RPMI 1640 media supplemented with 10% fetal calf serum (FCS), the cells were cultured in various concentrations of glucose and 1 or 10% FCS for another 24 hours. A mRNA was extracted from the cultured cells by a single step method, and Northern analysis was done to detect RNA band. A 0.5 kilobase single band was detected as c-myc mRNA. The expression of c-myc gene mRNA was reduced with increased concentration of glucose with 1% FCS. However, supplementation of 10% FCS abolished the effect of glucose on expression of c-myc gene. These findings suggested that glucose in conjunction with other growth promoting factors played an important role in expression of oncogene and cell growth in RINm5F cells.
Animals ; Cell Line ; Gene Expression Regulation, Neoplastic/drug effects ; Genes, myc/*drug effects ; Glucose/*pharmacology ; Insulinoma/*genetics ; Pancreatic Neoplasms/*genetics ; Rats ; Tumor Cells, Cultured

OBJECTIVETo investigate the effect of small interfering RNA (siRNA)-mediated islet neogenesis associated protein (INGAP) gene silencing on the proliferation of islet cells.

METHODSDifferent siRNAs targeting INGAP gene were designed and transfected into INS-1 islet cells, and the expression levels of INGAP mRNA and protein following the transfection were detected using RT-PCR, flow cytometry and Western blotting. The proliferation of the transfected INS-1 cells was evaluated using MTT assay.

RESULTSCompared with those in the irrelevant siRNA, empty vector control, and un-transfected groups, the expression levels of INGAP mRNA and protein in the cells transfected with siRNA6 were reduced significantly. The cell proliferation rate significantly increased after transfection with siRNA6 (P<0.05).

CONCLUSIONsiRNA targeting INGAP can effectively down-regulate INGAP expression and inhibit the proliferation of INS-1 cells.

Animals ; Antigens, Neoplasm ; genetics ; Biomarkers, Tumor ; genetics ; Cell Line, Tumor ; Cell Proliferation ; Insulinoma ; pathology ; Islets of Langerhans ; pathology ; Lectins, C-Type ; genetics ; Pancreatitis-Associated Proteins ; RNA Interference ; RNA, Small Interfering ; genetics ; Rats

Multiple endocrine neoplasia type 1 (MEN1) is a dominantly inherited tumor syndrome characterized by development of various combinations of tumors in multiple endocrine glands, including the pituitary, parathyroid or pancreas. MEN1 results from mutations in tumor suppressor gene Men1, which encodes nuclear protein menin. Menin has been shown to preferentially repress cell proliferation in endocrine tissues including pancreatic beta cells. Herein, the present study was to explore the potential mechanisms underlying menin in repressing cell proliferation in mice MEN1 insulinoma. In the Gene Set Enrichment Analysis (GSEA), Ccnb2 (encoding cyclin B2) was up-regulated in pancreatic islets of Men1-excised mice after 14-day tamoxifen-feeding. Immunofluorescence with antibody against cyclin B2 revealed that the expression of cyclin B2 was greatly increased in MEN1 insulinoma. In Men1(-/-) cells, Men1 ablation leaded to an increase in cyclin B2 expression. Immunofluorescent staining by phospho-H3S10 antibody revealed the increasing number of Men1(-/-) cells in mitosis. Cells were seeded at a density of 5 × 10(4), then counted on day 2, 4 and 6, and the cell growth curve revealed Men1 ablation increased the cell proliferation. In contrast, knockdown of cyclin B2 by shRNA diminished the number of cells in mitosis and reduced cell proliferation. Further, chromatin immunoprecipitation (ChIP) assay indicated that menin affected the histone modification of the promoter of Ccnb2 by reducing the level of histone H3 lysine 4 tri-methylation (H3K4me3) and histone H3 acetylation but not affecting the level of histone H3 lysine 9 tri-methylation (H3K9me3) or histone H3 lysine 27 tri-methylation (H3K27me3). Our results suggest that menin may inhibit MEN1 insulinoma by suppressing cyclin B2 expression via histone modification.
Animals ; Cell Proliferation ; Cyclin B2 ; genetics ; metabolism ; Histones ; metabolism ; Insulinoma ; metabolism ; pathology ; Mice ; Mice, Knockout ; Multiple Endocrine Neoplasia Type 1 ; genetics ; Mutation ; Pancreatic Neoplasms ; metabolism ; pathology ; Proto-Oncogene Proteins ; genetics

OBJECTIVEResistin was thought to link the obesity to type 2 diabetes. This study aimed to investigate the effect of resistin on insulinoma cell proliferation.

METHODSpcDNA3.1-resistin was transfected into rat insulinoma cells RINm5F. Cell proliferation was assessed by the MTT assay. The resistin and SOCS3 mRNA levels were assessed by RT-PCR. The total Akt level and the phosphorylation status were assessed by Western blot.

RESULTSThe over-expressed resistin inhibited the RINm5F cell proliferation (p<0.05). SOCS-3 expression was up-regulated by resistin over-expression (3.2 folds over the control; p<0.05). Akt phosphorylation was down-regulated by resistin over-expression (0.6 fold over the control; p<0.05).

CONCLUSIONSResistin impairs the rat insulinoma cell RINm5F proliferation. This might be attributed to a down-regulation of Akt level caused by increased SOCS-3 expression.

Animals ; Cell Line, Tumor ; Cell Proliferation ; Insulinoma ; pathology ; Pancreatic Neoplasms ; pathology ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Resistin ; genetics ; physiology ; Suppressor of Cytokine Signaling 3 Protein ; Suppressor of Cytokine Signaling Proteins ; genetics ; Transfection

OBJECTIVETo investigate the protective effect of losartan against angiotensin II (AngII)-induced beta cell (RIN-m) impairment and explore its mechanism.

METHODSIn vitro cultured RIN-m cells were divided into control group, 100 nmol/L AngII group and losartan pretreatment group. After cell incubation with the corresponding agents for 24 h, the amount of basal (3.3 mmol/L) and glucose-stimulated (16.7 mmol/L) insulin secretion (GSIS) was detected by radioimmunoassay, and the cellular reactive oxygen species (ROS) was assayed by flow cytometry with DCFH-DA staining; the mRNA and protein expressions of uncoupling protein 2 (UCP2) were determined by RT-PCR and Western blotting, respectively.

RESULTSThe basal insulin secretion showed no significant differences between the 3 groups (P>0.05). The GSIS in 100 nmol/L AngII group was significantly lower than that of the control group (P<0.001), but losartan pretreatment markedly restored the insulin secretion function to a level comparable to that of the control group (P<0.05). Compared with the control group, 100 nmol/L AngII significantly increased the cellular ROS level and the mRNA and protein expressions of UCP2 (P<0.05), and these changes were eliminated by losartan pretreatment.

CONCLUSIONSLosartan pretreatment offers protective effect against AngII-induced impairment of the GSIS of beta cells possibly by antagonizing the effects of AngII that causes increased ROS level and UCP2 expressions in beta-cells.

Angiotensin II ; adverse effects ; antagonists & inhibitors ; Animals ; Antihypertensive Agents ; pharmacology ; Cell Line, Tumor ; Insulin-Secreting Cells ; drug effects ; physiology ; Insulinoma ; pathology ; Ion Channels ; genetics ; metabolism ; Losartan ; pharmacology ; Mitochondrial Proteins ; genetics ; metabolism ; Protective Agents ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Uncoupling Protein 2

Multiple endocrine neoplasia (MEN) mutation is an autosomal dominant disorder characterized by the occurrence of parathyroid, pancreatic islet, and anterior pituitary tumors. The incidence of insulinoma in MEN is relatively uncommon, and there have been a few cases of MEN manifested with insulinoma as the first symptom in children. We experienced a 9-year-old girl having a familial MEN1 mutation. She complained of dizziness, occasional palpitation, weakness, hunger, sweating, and generalized tonic-clonic seizure that lasted for 5 minutes early in the morning. At first, she was only diagnosed with insulinoma by abdominal magnetic resonance images of a 1.3 × 1.5 cm mass in the pancreas and high insulin levels in blood of the hepatic vein, but after her father was diagnosed with MEN1. We found she had familial MEN1 mutation, and she recovered hyperinsulinemic hypoglycemia after enucleation of the mass. Therefore, the early genetic identification of MEN1 mutation is considerable for children with at least one manifestation.
Alleles ; Base Sequence ; Child ; DNA Mutational Analysis ; Female ; Humans ; Hypoglycemia/diagnosis ; Insulin/blood ; Insulinoma/diagnostic imaging/*pathology ; Magnetic Resonance Imaging ; Multiple Endocrine Neoplasia Type 1/*diagnosis/pathology ; Pancreatic Neoplasms/diagnostic imaging/*pathology ; Pedigree ; Polymorphism, Single Nucleotide ; Proto-Oncogene Proteins/genetics ; Seizures/complications