• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.81-89
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• 2004

Tumor necrosis factor-$\alpha$ (TNF-$\alpha$) and lymphotoxin-$\alpha$ (LT-$\alpha$, TNF-$\beta$) can initiate and perpetuate human diseases such as multiple sclerosis (MS), rheumatoid arthritis (RA), and insulin-dependent diabetes mellitus (IDDM). TNFs can be blocked by the use of soluble TNF receptors. However, since monomeric soluble receptors generally exhibit low affinity or function as agonists, the use of monomeric soluble receptors has been limited in the case of cytokines such as TNF-$\alpha$, TNF-$\alpha$, interleukin (IL)-1, IL-4, IL-6, and IL-13, which have adapted to a multi component receptor system. For these reasons, very high-affinity inhibitors were created for the purpose of a TNFs antagonist to bind the TNFR and trigger cellular signal by using the multistep polymerase chain reaction method. First, recombinant simple TNFR-Ig fusion proteins were constructed from the cDNA sequences encoding the extracellular domain of the human p55 TNFR (CD120a) and the human p75 TNFR (CD120b), which were linked to hinge and constant regions of human $IgG_1$ heavy chain, respectively using complementary primers (CP) encoding the complementary sequences. Then, concatameric TNFR-Ig fusion proteins were constructed using recombinant PCR and a complementary primer base of recombinant simple TNFR-Ig fusion proteins. For high level expression of recombinant fusion proteins, Chinese hamster ovary (CHO) cells were used with a retroviral expression system. The transfected cells produced the simple concatameric TNFR-Ig fusion proteins capable of binding TNF and inactivating it. These soluble versions of simple concantameric TNFR-Ig fusion proteins gave rise to multiple forms such as simple dimers and concatameric homodimers. Simple TNFR-1g fusion proteins were shown to have much more reduced TNF inhibitory activity than concatameric TNFR-Ig fusion proteins. Concatameric TNFR-Ig fusion proteins showed higher affinity than simple TNFR-Ig fusion proteins in a receptor inhibitor binding assay (RIBA). Additionally, concatameric TNFR-Ig fusion proteins were shown to have a progressive effect as a TNF inhibitor compared to the simple TNFR-Ig fusion proteins and conventional TNFR-Fc in cytotoxicity assays, and showed the same results for collagen induced arthritis (CIA) in mice in vivo.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4469-4475
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• 2012

Background: The potential use of hypomethylation of Long INterspersed Element 1 (LINE-1) and Alu elements (Alu) as a biomarker has been comprehensively assessed in several cancers, including head and neck squamous cell carcinoma (HNSCC). Failure to detect occult metastatic head and neck tumors on radical neck lymph node dissection can affect the therapeutic measures taken. Objective: The aim of this study was to investigate the LINE-1 and Alu methylation status and determine whether it can be applied for detection of occult metastatic tumors in HNSCC cases. Methods: We used the Combine Bisulfite Restriction Analysis (COBRA) technique to analyse LINE-1 and Alu methylation status. In addition to the methylation level, LINE-1 and Alu loci were classified based on the methylation statuses of two CpG dinucleotides in each allele as follows: hypermethylation ($^mC^mC$), hypomethylation ($^uC^uC$), and 2 forms of partial methylation ($^mC^uC$ and $^uC^mC$). Sixty-one lymph nodes were divided into 3 groups: 1) non-metastatic head and neck cancer (NM), 2) histologically negative for tumor cells of cases with metastatic head and neck cancer (LN), and 3) histologically positive for tumor cells (LP). Results: Alu methylation change was not significant. However, LINE-1 methylation of both LN and LP was altered, as demonstrated by the lower LINE-1 methylation levels (p<0.001), higher percentage of $^mC^uC$ (p<0.01), lower percentage of $^uC^mC$ (p<0.001) and higher percentage of $^uC^uC$ (p<0.001). Using receiver operating characteristic (ROC) curve analysis, $%^uC^mC$ and $%^mC^uC$ values revealed a high level of AUC at 0.806 and 0.716, respectively, in distinguishing LN from NM. Conclusion: The LINE-1 methylation changes in LN have the same pattern as that in LP. This epigenomic change may be due to the presence of occult metastatic tumor in LN cases.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6261-6265
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• 2013

Background: Recent studies have suggested that expression of the RAS protein activator like-1 gene (RASAL1) is decreased in gastric carcinoma tissues and cell lines, indicated a role in tumorigenesis and development of gastric cancer. Reduced expression of RASAL1 could result in aberrant increase of activity of RAS signaling pathways in cancer cells. However, the exact mechanism which induces down-regulation of the RASAL1 gene remains unclear. This study aimed to determine the methylation status and regulation of RASAL1 in gastric cancer. Materials and Methods: Using the methylation-specific polymerase chain reaction (MSP), the methylation status of CpG islands in the RASAL1 promoter in gastric cancers and paired adjacent non-cancerous tissues from 40 patients was assessed and its clinicopathological significance was analyzed. The methylation status of RASAL1 in gastric cancer lines MKN-28, SGC-790l, BGC-823, as well as in normal gastric epithelial cell line GES-l was also determined after treatment with a DNA methyltransferase inhibitor, 5-aza-2'-doexycytidine (5-Aza-CdR). RAS activity (GAS-GTP) was assessed through a pull-down method, while protein levels of ERK1/2, a downstream molecule of RAS signaling pathways, were determined by Western blotting. Results: The frequencies of RASAL1 promoter methylation in gastric cancer and paired adjacent non-cancerous tissues were 70% (28/40) and 30% (12/40) respectively (P<0.05). There were significantly correlations between RASAL1 promoter methylation with tumor differentiation, tumor size, invasive depth and lymph node metastasis in patients with gastric cancer (all P<0.05), but no correlation was found for age or gender. Promoter hypermethylation of the RASAL1 gene was detected in MKN-28, SGC-790l and BGC-823 cancer cells, but not in the normal gastric epithelial cell line GES-1. Elevated expression of the RASAL1 protein, a decreased RAS-GTP and p-ERK1/2 protein were detected in three gastric cancer cell lines after treatment with 5-Aza-CdR. Conclusions: Aberrant hypermethylation of the RASAL1 gene promoter frequently occurs in gastric cancer tissues and cells. In addition, the demethylating agent 5-Aza-CdR can reverse the hypermethylation of RASAL1 gene and up-regulate the expression of RASAL1 significantly in gastric cancer cells in vivo. Our study suggests that RASAL1 promoter methylation may have a certain relationship with the reduced RASAL1 expression in gastric cancer.