The anti-tumor mechanisms of p53 through the regulation of expression and glycosylation of insulin-like growth factor binding protein-3 / 소아과

PURPOSE: Insulin-like growth factor binding protein(IGFBP)-3 has been known as a tumor suppressor gene, and its anti-tumor function was divided into insulin-like growth factor(IGF)-dependent and IGF-independent mechanism. In IGF-independent mechanism, IGFBP-3 directly interacts with a cell without binding of IGFs, becoming an interesting object in oncology. Several studies demonstrate that one of the well-known tumor suppressor genes, p53, induces directly IGFBP-3 transcription, and the increment of IGFBP-3 expression induces apoptosis of many cancer cells. Recently, the anti-tumor mechanisms of IGFBP-3 have been reported, but post-translational modification of IGFBP-3 and its anti-tumor mechanism are not well known. In this study, we examined whether p53 regulated the glycosylation of IGFBP-3, and analysed the meaning of IGFBP-3 glycosylation related to the apoptosis of cancer cell. METHODS: The p53-mutated status of MDA-MB-231 human breast cancer cells was used in this experiment. The expression and glycosylation of IGFBP-3 were tested by Western blot analysis after infection of adenovirus mediated Ad/p53 and/or Ad/IGFBP-3. RESULTS: Ad/p53 infected cells resulted in growth retardation and the induced apoptosis. p53 induced direct expression and glycosylation of IGFBP-3. The increase of glcosylated IGFBP-3 was able to promote cellular apoptosis, and the glycosylation of IGFBP-3 was more activated by the double treatment of Ad/p53 and Ad/IGFBP-3. CONCLUSION: From this study, the anti-tumor activity of IGFBP-3 was shown to improve the stabilization of IGFBP-3 through the increment of glycosylation of IGFBP-3 by p53. This result suggests that the combined gene therapy of p53 and IGFBP-3 may appropriate treatment of cancer.

PTEN/MMAC1 enhances the growth inhibition by anticancer drugs with downregulation of IGF-II expression in gastric cancer cells

PTEN/MMAC1 is a tumor suppressor gene that is mutated in a variety of advanced and metastatic cancers. Its major function is likely to be the phosphatase activity that regulates the phosphotidylinositol (PI)3-kinase/ Akt pathway. On the other hand, IGF system plays an important role in cell proliferation and cell survival via PI3-kinase/Akt and mitogen-activated protein kinase pathways in many cancer cells. To evaluate effect of PTEN on cell growth and IGF system in gastric cancer, human gastric adenocarcinoma cells (SNU-5 & -216) were transfected with human PTEN cDNA. Those PTEN- transfected gastric cancer cells had a lower proliferation rate than the pcDNA3-transfected cells. PTEN overexpression induced a profound decrease in the IGF-II and IGF-IR expression levels, and downregulation of IGF-II expression by PTEN was mediated through the regulation of the IGF-II promoter. In addition, a PI3-kinase inhibitor, LY294002, induced the downregulation of IGF-II expression. The PTEN-overexpressing SUN-5 and -216 cells were more sensitive to death induced by etoposide and adriamycin that induce DNA damage than the pcDNA3-transfected cells. These findings suggest that PTEN suppresses the cell growth through modulation of IGF system and sensitizing cancer cells to cell death by anticancer drugs.

Novel Gap Junction Molecules, Connexin 37, Enhances the Bystander Effect in HSVtk/GCV Gene Therapy

PURPOSE: Gap junction intercellular communication(GJIC) is an important mechanism of the bystander effect in herpes simplex thymidine kinase/ganciclovir(HSVtk/GCV) gene therapy Therefore, we attempted to enhance the bystander effect in vitro by exogenous overexpressing connexin 37(Cx37) in cells to increase GJIC. METHODS: NIH3T3 cells were transfected with the Cx37 and HSVtk gene or the HSVtk gene alone by the calcium phosphate method, and we detected their expression from these cells by RT-PCR. GCV-mediated cytotoxicity and the bystander effect of each transfectant was then assessed and compared. RESULTS: Cells transfected with HSVtk became sensitive to low concentration of GCV. We found significantly increased cytotoxicity in HSVtk/GCV gene therapy after introduction of the HSVtk and Cx37 genes together compared with the cytotoxicity seen after introduction of the HSVtk gene in vitro. Co-expression of the HSVtk and Cx37 genes potentiates HSVtk/GCV gene therapy through the bystander effect. CONCLUSION: These results indicated that the increase of GJIC using Cx37 have potentiated the by stander effect of HSVtk/GCV therapy, and may be a new approach to improve response in suicidal cancer gene therapy.

Apoptotic Pathway Induced by Dominant Negative ATM Gene in CT-26 Colon Cancer Cells

PURPOSE: Ataxia telangiectasia mutated(ATM) is involved in DNA damage responses at different cell cycle checkpoints, and signalling pathways associated with regulation of apoptosis in response to ionizing radiation(IR). However, the signaling pathway that underlies IR-induced apoptosis in ATM cells has remained unknown. The purpose of this study was, therefore, to investigate the apoptotic pathway that underlies IR-induced apoptosis in a CT-26 cells expressing dominant negative ATM (DN-ATM). METHODS: We generated a replication-deficient recombinant adenovirus encoding the DN-ATM(Ad/DN-ATM) or control adenovirus encoding no transgene(Ad/GFP) and infected adenovirus to CT-26 cells. After infection, we examined apoptosis and apoptotic pathway by [3H]-thymidine assay, DNA fragmentation, and Western immunoblot analysis. RESULTS: DN-ATM gene served as the creation of AT phenotype in a CT-26 cells as revealed by decreased cell proliferations following IR. In addition, IR-induced apoptosis was regulated through the reduced levels of the anti-apoptotic protein Bcl-2, the increased levels of the apoptotic protein Bax, and the activation of caspase-9, caspase-3, and PARP. CONCLUSION: These results indicate that the pathway of IR-induced apoptosis in CT-26 cells expressing DN-ATM is mediated by mitochondrial signaling pathway involving the activation of caspase 9, caspase 3, and PARP.

A study of patellofemoral pain using computerized tomography / 대한정형외과학회잡지

No abstract available.

A Clinical Study of the Mechanism of Injury of Juvenile Tillaux Fracture and Triplane Fracture / 대한정형외과학회잡지

The juvenile Tillaux fracture and the triplane fracture of the distal end of the tibia in adolescents are considered uncommon injuries and the mechanism of both injuries has been uncertain. It has been postulated that both fractures probably are caused by external rotation of the foot. We atempted to evaluate the mechanism of injury as well as to conform the role of the external rotation of the foot for the juvenile Tillaux fracture and triplane fracture. From 1983 to 1988 at the department of orthopedic surgery, college of medicine, Hallym University, we evaluated the cases of nine adolescent patients with the juvenile Tillaux fracture and nine patients with the triplane fracture of the distal tibial epiphysis. We confirmed that external rotation force produced the triplane fracture as well as juvenile Tillaux fracture. And we could postulate that the triplane fracture needed further external rotation force, less closure of the distal tibial epiphysis, and more complicated mechanism of injury than the juvenile Tillaux fracture. The knowledge of these mechanism of injury enables us to use a rational manipulative approach to reduce these fractures.

Congenital High Scapula Associated with Anomaly of the Acromion: A Case Report / 대한정형외과학회잡지

Congenital high scapula, more commonly referred to as Sprengel's deformity, was first described by Eulenberg in 1863. Usually other congenital anomalies are associated such as absent or fused ribs, chest wall asymmetry, Klippel-Feil syndrome, cervical ribs, congenital scoliosis, cervical spina biffida was treated with the excision of the elongated acromion and the resection of prominent elongated acromion to be described is an extremely rare malformation. We experienced one case of congenital high scapula associated with anomaly of the acromion, which was treated with the excision of the elongated acromion and the resection of prominent supermedial border of the scapula for the purpose of the cosmetic and functional correction. After 1 year follow up, abduction was improved by only 10 degrees in the glenohumeral joint with the definite cosmetic improvement.

A Clinical Study of the Adolescent ankle Fracture / 대한정형외과학회잡지

The distal tibial physes begins its closure about 18 months prior to complete cessation of the tibial growth, closing first in its midportion, then medially, and finally, laterally. So the patterns of the ankle fracture during this period would be different from those of the adult or the children before this period. During the six year period from 1983 to 1988 at the department of orthopedic surgery, college of medi-cine, Hallym University, we found and analysed 54 adolescent patients with the ankle fracture which developed before the closure of the distal tibial growth plate, which were followed up more than 1 year. The results were as follows 1. During the 6 year period of this study, the adolescent ankle fracture comprise 4.4% (54 cases) of all the ankle fractures(1158 cases). Injury occurred more often in male than in female(44 versus 10). The mean age was 13.7 years. 2. The most common cause of injury was traffic accident being in 26 cases(48.1%), the next was slip down accident in 11 cases, and the third was sports activity in 10 cases. 3. The incidence of the adoescent ankle fractures using the Salter-Harris classification revealed 20 (37%) type II, 7 (13%) type III, 5 (9.3%) type IV, and 4 (7.4%) type I and that using the Dias and Tachdjian classification revealed 14 (25.9%) Supination-Inversion, 10 (18.5%) Supination-External rotation, 7 (12.7%) Pronation-Eversion-External rotation, and 1 (1.9%) no adjustable fracture. There were 9 (16.7%) Tillaux and 9 (16.7%) triplane fractures, which were belonged to both classifications 4. The treatments performed were closed reduction and cast immobilization for 28 cases (51.9 %), open reduction and internal fixation for 20 cases (37%), and closed reduction and percutaneous pinning for 6 cases. 5. There were complications experienced in 9 cases, which were 3 premature epiphyseal closure, 3 joint surface incongruity, 2 angular deformity, and 1 leg shortening. 6. For the prevention of the complication, the treatment of the adolecsent ankle fracture should be treated like as adult fracture.