ISLET FORMATION AND REGENERATION

Objective To explore the mechanisms of differentiation and development of pancreatic endocrine cells as well as pancreatic regeneration.Methods Human embryonic pancreatic tissue at 7-14 weeks of gestation was collected.Diabetes mellitus rat model was induced with 65 mg/kg of streptozotocin.Insulin, glucagon, somatostatin, nestin, and cytokeratin 19 (CK19) of pancreatic tissues were observed by immunohistochemistry.Results At 9 weeks of gestation, pancreatic epithelial cells began to co-express insulin, glucagon, somatostatin, and CK19 before migration.Islet cells gradually congregated along with the increase of aging, and at 14 weeks of gestation histological examination showed islet formation.At 12 weeks of gestation, nestin-positive cells could be seen in the pancreatic mesenchyme.During early embryogenesis, islet cells of pancreatic ducts co-expressed insulin, glucagon, and somatostatin.During pancreatic regeneration after damage, nestin expression of islet cells increased.Conclusion In the early stage of embryogenesis, islet cells of primary pancreatic ducts can be differentiated to multipotential endocrine cells before migration.During tissue regeneration, pancreatic stem cells may differentiate and proliferate to form pancreatic islet.

Wnt/β-catenin signaling pathway is active in pancreatic development of rat embryo

AIM： To elucidate the role of Wnt/β-catenin signaling pathway in pancreatic development of rat embryo. METHODS： The mRNAs of β-catenin, APC, cyclin D1 genes were amplified by means of semiquantitative reverse transcription polymerase chain reaction （RTPCR） from embryonic pancreas in different periods and normal pancreas of rat, respectively. Protein expression of these genes in embryonic pancreas of E14.5-E18.5 was examined by immunohistochemical method. RESULTS： In embryonic pancreas of E14.5, the transcript amplification of β-catenin and cyclinD1 genes was detected. In embryonic pancreas of E18.5, the transcription levels of β-catenin and cyclinD1 genes became much higher than in other periods. But in adult rat pancreas the transcription of cyclinD1 gene could not be observed. Only until E18.5, the transcript amplification of mRNA of APC gene could be detected. Surprisingly, the transcription level of APC gene became much higher in adult rat pancreas than in embryonic pancreas. By means of immunohistochemical staining, identical results were obtained to the above by RP-PCR, except for β-catenin protein in adult rat pancreas. CONCLUSION： Active Wnt/β-catenin signaling occurs in rat embryonic pancreas and is probably important for pancreatic development and organ formation.

Comparative Proteome Analysis of Breast Cancer and Adjacent Normal Breast Tissues in Human

Two-dimensional polyacrylamide gel assisted laser desorption/ionization electrophoresis （2D-PAGE） and matrixtandem time-of-flight mass spectrometry （MALDI-TOF/TOF-MS）, incorporated with online database searching, were performed to investigate differential proteins of breast cancer and adjacent normal breast tissues. Considering that serum albumin is abundantly presented in normal control samples, 15 differential spots detected in 11 out of 12 （91.7%） breast cancer samples were identified by online SIENA-2DPAGE database searching and MALDI-TOF/TOF-MS analysis. The results indicate that pathological changes of breast cancer are concerned with augmentation of substance metabolism, promotion of proteolytic activity, decline of activity of some inhibitors of enzymes, and so on. Some important proteins involved in the pathological process of breast cancer with changed expression may be useful biomarkers, such as alpha-l-antitrypsin, EF- 1-beta, cathepsin D, TCTP, SMT3A, RPS12, and PSMA1, among which SMT3A, RPSl2, and PSMA1 were first reported for breast cancer in this study.