Biomedical subjects
Publications and source records attributed to Dooil Jeoung.
The role of c-FLIP in cell motility was investigated using RNA interference. Down-regulation of c-FLIP increased amounts of reactive oxygen species (ROS), while over-expression of c-FLIP produced opposite effect. ROS induced phosphorylation of Akt and impaired cell motility.
The cancer-associated gene (CAGE) is a novel cancer/testis antigen. Over-expression of it increased phosphorylation of focal adhesion kinase (FAK) and enhanced motility of SNU387 cells. Focal adhesion, kinase-related non-kinase (FRNK), an endogenous inhibitor of FAK, was significantly suppressed. This suggests that CAGE-promoted motility requires FAK. The inhibition of Rho-Associated coiled-coil-containing protein kinase (ROCK), an activator of FAK, also suppressed CAGE-promoted motility.
Heat shock protein 70 (Hsp70) release and its effects on pro-inflammatory cytokine production have been controversial. In this study, we investigated whether Hsp70 could be released from monocytes and activates matrix metalloproteinase-9 (MMP-9) gene expression. Hsp70 overexpression in human monocytic cell line U937 was found to increase PMA-induced MMP-9 expression and enhance cell motility. Hsp70 cDNA transfectants released Hsp70 protein into culture supernatants, and a part of released Hsp70 subsequently was bound to the surface of U937 cells. Addition of culture medium containing the extracelluar Hsp70 led to an increase not only in proMMP-9 secretion, but also the invasiveness of U937 cells through Matrigel or human umbilical vascular endothelial cells (HUVEC) in vitro. Immunodepletion of Hsp70 abolished its effect on MMP-9 expression. The released Hsp70 activated nuclear factor kappa B (NF-kappaB) and activating protein-1 (AP-1), which led to the activation of MMP-9 transcription. Taken together, these results suggest that extracellular Hsp70 induces the expression of MMP-9 gene through activation of NF-KappaB and AP-1.
We previously identified a novel cancer/testis antigen gene CAGE by screening cDNA expression libraries of human testis and gastric cancer cell lines with sera of gastric cancer patients. CAGE is expressed in many cancers and cancer cell lines, but not in normal tissues apart from the testis. In the present study, we investigated its role in the motility of cells of two human cancer cell lines: HeLa and the human hepatic cancer cell line, SNU387. Induction of CAGE by tetracycline or transient transfection enhanced the migration and invasiveness of HeLa cells, but not the adhesiveness of either cell line. Overexpression of CAGE led to activation of ERK and p38 MAPK but not Akt, and inhibition of ERK by PD98059 or p38 MAPK by SB203580 counteracted the CAGE-promoted increase in motility in both cell lines. Overexpression of CAGE also resulted in a reduction of ROS and an increase of ROS scavenging, associated with induction of catalase activity. Inhibition of ERK and p38 MAPK increased ROS levels in cells transfected with CAGE, suggesting that ROS reduce the motility of both cell lines. Inhibition of ERK and p38 MAPK reduced the induction of catalase activity resulting from overexpression of CAGE, and inhibition of catalase reduced CAGE-promoted motility. We conclude that CAGE enhances the motility of cancer cells by activating ERK and p38 MAPK, inducing catalase activity, and reducing ROS levels.
We employed RNA interference to determine the role of tissue transglutaminase II (TGase II) in motility of cancer cells. Down-regulation of TGase II by small interfering RNA against TGase II impaired adhesion and motility of HeLa cells by decreasing phosphorylation of the protein kinase, Akt, and reactive oxygen species (ROS). Over-expression of TGase II showed opposite effects. These results suggest potential utility of TGase II for development of therapeutic anti cancer vaccine.
The expression of heat shock proteins (HSPs) is known to be increased via activation of heat shock factor 1 (HSF1), and excess expression of HSPs exerts feedback inhibition of HSF1. However, the molecular mechanism to modulate such relationships between HSPs and HSF1 is not clear. In the present study, we show that stable transfection of either Hsp25 or inducible Hsp70 (Hsp70i) increased expression of endogenous HSPs such as HSP25 and HSP70i through HSF1 activation. However, these phenomena were abolished when the dominant negative Hsf1 mutant was transfected to HSP25 or HSP70i overexpressed cells. Moreover, the increased HSF1 activity by either HSP25 or HSP70i was found to result from dephosphorylation of HSF1 on serine 307 that increased the stability of HSF1. Either HSP25 or HSP70i inhibited ERK1/2 phosphorylation because of increased MKP1 phosphorylation by direct interaction of these HSPs with MKP1. Treatment of HOS and NCI-H358 cells, which showed high expressions of endogenous HSF1, with small interfering RNA (siRNA) of either HSP27 (siHSP27)or HSP70i (siHSP70i) inhibited both HSP27 and HSP70i proteins; this was because of increased ERK1/2 phosphorylation and serine phosphorylation of HSF1. The results, therefore, suggested that when the HSF1 protein level was high in cancer cells, excess expression of HSP27 or HSP70i strongly facilitates the expression of HSP proteins through HSF1 activation, resulting in severe radio- or chemoresistance.
The cancer associated gene (CAGE) is a novel cancer/testis antigen. Over-expression of CAGE enhanced growth rates, promoted cell motility and led to an ROS scavenging effect which was accompanied by an induced catalase cavity. Further, peptides of CAGE induced cytolytic T lymphocytes (CTL) activity, and CD8+ T cells pre-sensitized with these peptides displayed cytotoxic effects against cancer cells expressing CAGE. These results suggest that CAGE would be a valuable target for the development of an anti-cancer vaccine.
OBJECTIVES: By utilizing serological analysis of a recombinant cDNA expression library (SEREX), we previously found that autoantibodies to poly (ADP-ribose) polymerase (PARP) are specifically present in the sera of patients with SLE. In this study, recombinant proteins of various domains of PARP were used to determine the PARP domain that is associated with SLE. METHODS: We produced four recombinant PARP proteins, which contained various PARP domains, and then carried out enzyme linked immunosorbent assay (ELISA) using these recombinant proteins to identify domains useful for SLE diagnosis. The recombinant proteins used in this analysis were; ADPNF (amino acids 1-234), ET-L2 (amino acids 339-680), ET-L3 (amino acids 681-1014), and ADPCF (amino acids 300-1014). RESULT: ELISA with ADPNF or ET-L2 showed low sensitivity in the sera of patients with SLE (14.3% and 17.0% respectively), whereas ELISA with ET-L3 or ADPCF showed high sensitivity in the sera of patients with SLE (34.0% and 49.1%, respectively). Autoantibodies to ADPCF were not found in the sera of patients with rheumatoid arthritis (0/30), systemic sclerosis (0/30) or healthy donors (0/54) and were rarely found in polymyositis/dermatomyositis (1/30) and Sjogren syndrome (1/14). Autoantibodies to ADPCF were closely associated with the presence of an oral ulcer in SLE (P=0.03, by the chi-square test). CONCLUSION: The high sensitivity and specificity shown by autoantibodies to ADPCF protein could be used as a valuable serologic maker for the diagnosis of SLE.
MOTIVATION: Multivariate analyses are advantageous for the simultaneous testing of the separate and combined effects of many variables and of their interactions. In factorial designs with many factors and/or levels, however, sufficient replication is often prohibitively costly. Furthermore, complicated statements are often required for the biological interpretation of the higher-order interactions determined by standard statistical techniques like analysis of variance. RESULTS: Because we are usually interested in finding factor-specific effects or their interactions, we assumed that the observed expression profile of a gene is a manifestation of an underlying factor-specific generative pattern (FSGP) combined with noise. Thus, a genetic algorithm was created to find the nearest FSGP for each expression profile. We then measured the distance between each profile and the corresponding nearest FSGP. Permutation testing for the distance measures successfully identified those genes with statistically significant profiles, thus yielding straightforward biological interpretations. Association networks of genes, drugs, and cell lines were created as tripartite graphs, representing significant and interpretable relations, by using a microarray experiment of gastric-cancer cell lines with a factorial design and no replication. The proposed method may benefit the combined analysis of heterogeneous expression data from the growing public repositories.
We performed SEREX (serological analysis of recombinant cDNA expression library) to identify autoantibodies that are prevalent in the cerebrospinal fluid of patients with moyamoya disease. These autoantibodies include PC326 (of unknown function), SRY (sex determining region Y), and peroxisomal D3,D2-enoyl-CoA isomerase.
RNA interference has become a powerful tool for silencing of gene expression in mammals and plants. To determine the effect of Smad3 on transforming growth factor-beta signaling, we constructed a small interfering RNA (siRNA) targeted to Smad3. This siRNA inhibited expression of the endogenous Smad3 leading to the prevention of nuclear localization of Smad3. Further, Smad3 siRNA prevented not only anti-proliferative activity of TGF-beta1 but also TGF-beta1-inducible promoter activity.
Human heavy chain ferritin (H-ferritin) was cloned from human heart cDNA library and expressed in Pichia pastoris. The H-ferritin transformant was cultivated by fed-batch and the cell mass reached about 52 g cell dry wt l(-1) after 150 h. In atomic absorption spectrometry analysis, intracellular content of iron in H-ferritin transformant was measured to 3038 +/- 72 microg g(-1) which was 9.6-fold more than that of control strain.