• BMB Reports
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• v.38 no.3
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• pp.328-333
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• 2005

A human homologue of Sar1, named Sara2, was shown to be preferentially expressed during erythropoiesis in a culture stimulated by EPO. Previous studies, in yeast, have shown that secretion-associated and Ras-related protein (Sar1p) plays an essential role in protein transport from the endoplasmic reticulum to the Golgi apparatus. Here, we report the molecular analysis of Sara2 in erythroid cell culture. A 1250 bp long cDNA, encoding a 198 amino-acid protein very similar to Sar1 proteins from other organisms, was obtained. Furthermore, we also report a functional study of Sara2 with Real-time quantitative PCR analysis, demonstrating that expression of Sara2 mRNA increases during the initial stages of erythroid differentiation with EPO and that a two-fold increase in expression occurs following the addition of hydroxyurea (HU). In K562 cells, Sara2 mRNA was observed to have a constant expression and the addition of HU also up-regulated the expression in these cells. Our results suggest that Sara2 is an important gene in processes involving proliferation and differentiation and could be valuable for understanding the vesicular transport system during erythropoiesis.

• Radiation Oncology Journal
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• v.19 no.2
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• pp.171-180
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• 2001

Purpose : Expression of TIMP, intrinsic inhibitor of MMP, is regulated by signal transduction in response to genotoxins and is likely to be an important step in metastasis, angiogenesis and wound healing after ionizing radiation. Therefore, we studied radiation mediated TIMP expression and its mechanism in head and neck cancer cell lines. Materials and Methods : Human head and neck cancer cell lines established at Asan Medical Center were used and radiosensitivity $(D_0)$, radiation cytotoxicity and metastatic potential were measured by clonogenic assay, n assay and invasion assay, respectively. The conditioned medium was prepared at 24 hours and 48 hours after 2 Gy and 10 Gy irradiation and expression of TIMP protein was measured by Elisa assay with specific antibodies against human TIMP. hTIMP1 promoter region was cloned and TIMP1 luciferase reporter vector was constructed. The reporter vector was transfected to AMC-HN-1 and -HN-9 cells with or without expression vector Ras, then the cells were exposed to radiation or PMA, PKC activator. EMSA was peformed with oligonucleotide (-59/-53 element and SP1) of TIMP1 promoter. Results : $D_0$ of HN-1, -2, -3, -5 and -9 cell lines were 1.55 Gy, 1.8 Gy, 1.5 Gt, 1.55 Gy and 2.45 Gy respectively. n assay confirmed cell viability, over $94\%$ at 24hrs, 48hrs after 2 Gy irradiation and over 73% after 10 Gy irradiation. Elisa assay confirmed that cells secreted TIMP1, 2 proteins continuously. After 2 Gy irradiation, TIMP2 secretion was decreased at 24hrs in HN-1 and HN-9 cell lines but after 10 Gy irradiation, it was increased in all cell lines. At 48hrs after irradiation, it was increased in HN-1 but decreased in HN-9 cells. But the change in TIMP secretion by RT was mild. The transcription of TIMP1 gene in HN-1 was induced by PMA but in HN-9 cell lines, it was suppressed. Wild type Ras induced the TIMP-1 transcription by 20 fold and 4 fold in HN-1 and HN-9 respectively. The binding activity to -59/-53, AP1 motif was increased by RT, but not to SP1 motif in both cell lines. Conclusions : We observed the difference of expression and activity of TIMPs between radiosensitive and radioresistant cell line and the different signal transduction pathway between in these cell lines may contribute the different radiosensitivity. Further research to investigate the radiation response and its signal pathway of TIMPs is needed.

• Journal of Nutrition and Health
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• v.25 no.6
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• pp.492-500
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• 1992

The rate of vitamin K-dependent carboxylation of endogenous liver microsomal proteins and an exogenous peptide substrate for carboxylase were measured to test the effects of excess vitamin A on vitamin K function in rats. In vitro vitamin A incubation in normal rat microsomes of vitamin K-sufficient ras did not influence the carboxylation rates of either endogenous prothrombin precursors or a peptide substrate added, Similarly vitamin A incubation in micro-somes from control and excess vitamin A-fed rats that were on vitamin K-free diet did not change the rate significantly within the respectively groups ; however the rates of endogenous protein carboxylation from excess vitamin A-fed rats tended to be increased by the in vitro vitamin A addition compared to that of control rats. Excess vitamin A-fed rats had 2- to 3- fold higher carboxylase activites of endogenous protein carboxylation either with or without the invitro vitamin A incubation than did control rats. In an in vivo study carboxyalase activites with an added exogenous peptide substrate were not influenced by excess intake of vitamin excess vitamin A-fed rats than for control rats. Carboxylase activites tended to be increased amounts of vitamin A on endogenous protein carboxylation appeareed as early as one week post-initiation of the diet. The results of this study indicate that excess vitamin A produces toxic effect rapidly and that excess dietary vitamin A increase the rate of carboxylation of endogenous protein mainly prothrombin precursors which is an indication of vitamin K defi-ciency.

• Tuberculosis and Respiratory Diseases
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• v.68 no.4
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• pp.212-217
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• 2010

Background: Acyl protein thioesterase-1 (APT1) is a cytosolic protein that may function in the depalmitoylation of numerous proteins, including the Ras family. However, the clinical role of depalmitoyl thioesterase in human cancer is not known. We evaluated the APT1 expression in lung cancer tissue and its clinicopathological findings according APT1 expression pattern. Methods: APT1 expression was examined by immunohistochemistry in the tumor tissue from 79 patients, who had undergone curative surgical removal of the primary lesion; all patients had been diagnosed with stage I non-small cell lung cancer between 1993 and 2004, at Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. Results: The APT1 expression was seen in 50 out of 79 (63.3%) cases. The positive APT1 expression was significantly related with histologic subtype and T stage, but was not influenced by differentiation. The positive APT1 expression was not significantly related to patient age, gender, or smoking history. The median follow-up duration was 10.0 years; the 5-year survival rate was 71.0%. The positive APT1 expression group showed significantly worse overall survival and worse disease-free survival without statistical significance. Conclusion: We conclude that positive APT1 expression in stage I lung cancer after surgery is closely associated with overall survival. To evaluate APT1 as a prognostic marker in lung cancer, comprehensive studies on advanced stage cases are needed.

• Journal of Oral Medicine and Pain
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• v.36 no.1
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• pp.11-20
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• 2011

Valproic acid (VPA) is a well-known anticonvulsive agent and has been used in the treatment of epilepsy for almost 30 years. VPA emerged in 1997 as an antineoplastic agent. And it is known that antitmor activity of VPA is associated with its targeted at histone deacetylases. 17AAG, Inhibition of HSP90 leads to the proteasome degradation of the HSP90 client proteins, such as Akt, Raf/Ras, Erk, VEGF, cyclin D and p53, and causes potent antitumor activity. It is reported that 17AAG-induced HSP90 inhibition results in prevention of cell proliferation and induction of apoptosis in several types of cancer. This study was undertaken to investigate the synergistic apoptotic effect of co-treatment with the histone deacetylases inhibitor, VPA and the HSP90 inhibitor, 17AAG on human osteosarcoma (HOS) cells. Cell viability was evaluated by trypan-blue exclusion. Induction and augmentation of apoptosis were confirmed by Hoechst staining, flow cytometry (DNA hypoploidy and MMP change), Westen blot analysis and immunofluorescent staining. In this study, HOS cells co-treated with VPA and 17AAG showed several lines of apoptotic manifestation such as nuclear condensations, the reduction of MMP, the decrease of DNA content, the release of cytochrome c into cytosol, the translocation of AIF onto nuclei, and activation of caspase-3, caspase-7 and PARP whereas each single treated HOS cells did not. Although the single treatment of 1 mM VPA or 0.5 ${\mu}M$ 17AAG for 48 h did not induce apoptosis, the co-treatment with them induced prominently apoptosis. Therefore our data in this study provide the possibility that combination therapy with VPA and 17AAG could be considered as a novel therapeutic strategy for human osteosarcoma.