5-Lipoxygenase (5-LO) catalyzes the formation of two major groups of leukotrienes, leukotriene B4 and cysteinyl leukotrienes (CysLTs), and it has been implicated as a promising drug target to treat various inflammatory diseases. However, its role in osteoclastogenesis has not been investigated. In this study, we used mouse bone marrow–derived macrophages (BMMs) to show that 5-LO inhibitor suppresses RANKL-induced osteoclast formation. Inhibition of 5-LO was associated with impaired activation of multiple signaling events downstream of RANK, including ERK and p38 phosphorylation, and IκB degradation, followed by a decrease in NFATc1 expression. Ectopic overexpression of a constitutively active form of NFATc1 partly rescued the antiosteoclastogenic effect of 5-LO inhibitor. The knockdown of 5-LO in BMMs also resulted in a significant reduction in RANKL-induced osteoclast formation, accompanied by decreased expression of NFATc1. Similar effects were shown with CysLT receptor (CysLTR)1/2 antagonist and small RNA for CysLTR1 in BMMs, indicating the involvement of CysLT and CysLTR1 in 5-LO–mediated osteoclastogenesis. Finally, 5-LO inhibitor suppressed LPS-induced osteoclast formation and bone loss in the in vivo mouse experiments, suggesting a potential therapeutic strategy for treating diseases involving bone destruction. Taken together, the results of this study demonstrate that 5-LO is a key mediator of RANKL-induced osteoclast formation and possibly a novel therapeutic target for bone-resorption diseases.

The differentiation of malignant mesotheliomas and benign mesothelial proliferations is crucial in determining patient care and prognosis. But, this distinction can be extremely difficult, particularly in small biopsies. Recently, insulin-like growth factor II mRNA-binding protein 3 (IMP3) and glucose transporter 1 (GLUT-1) have been reported as specific and sensitive markers in the distinction of mesotheliomas from benign mesothelial proliferations. The purpose of this study is to evaluate the utility of IMP3, GLUT-1, and epithelial membrane antigen (EMA) immunohistochemistry for distinguishing mesotheliomas from benign mesothelial proliferations. Immunoexpression of IMP3, GLUT-1, and EMA was evaluated in 88 malignant mesotheliomas, 35 adenomatoid tumors, and 20 benign lung tissues with reactive mesothelial cells. The sensitivity for IMP3, GLUT-1, and EMA was 37%, 21%, and 41%, respectively. The specificity for IMP3, GLUT-1, and EMA was 100%. When IMP3, GLUT1, and EMA combined, the sensitivity was 66% for IMP3/EMA staining, 53% for GLUT-1/EMA staining, and 45% for IMP3/GLUT-1. Use of IMP3 and EMA together is more helpful to distinguish malignant mesotheliomas from benign mesothelial proliferations than the use of IMP3 or EMA alone.

The Schizosaccharomyces pombe msrB(+) gene encoding methionine-R-sulfoxide reductase (MsrB) was cloned into the shuttle vector pRS316 to generate the recombinant plasmid pFMetSO. The msrB(+) mRNA level was significantly increased in the S. pombe cells harboring pFMetSO, indicating that the cloned msrB(+) gene is functioning. In the presence of 0.1 mM L-methionine-(R,S)-sulfoxide, the S. pombe cells harboring pFMetSO could grow normally but the growth of the vector control cells was almost arrested. The S. pombe cells harboring pFMetSO exhibited the enhanced growth on the minimal medium plates with stress-inducing agents, such as hydrogen peroxide, superoxide radical-generating menadione (MD), nitric oxide (NO)-generating sodium nitroprusside (SNP), and cadmium (Cd), when compared with the vector control cells. They also gave rise to the enhanced growth at the high incubation temperature of 37 °C than the vector control cells. The S. pombe cells harboring pFMetSO contained lower reactive oxygen species (ROS) and higher total glutathione (GSH) levels than the vector control cells. In brief, the S. pombe MsrB plays a protective role against oxidative, nitrosative, and thermal stresses, and is involved in diminishing intracellular ROS level.

Background: The cancer stem cell (CSC) theory which postulates a small subset of tumor cells have the capacity in tumor initiation, progression and importantly resistance to chemotherapy. CD133 is a transmembrane glycoprotein that serves as a putative cancer stem cell (CSC) marker in colon cancer and its relationship with the chemoresistance has been on debate. In our previous clinical study, we found the patients with CD133+ colon cancer have better prognosis after 5 fluorouracil (5-FU) chemotherapy compared to CD133- tumors. Purpose: To understand the role of CSC marker expression in relation to chemoresistance in colon cancer, we evaluated the effect of CD133 inhibition in colorectal cancer (CRC) cell line on the genes expression which are related to chemoresistance or cell survival. Materials & Methods: CD133 siRNA transfection was performed on CD133+ colon cancer cell line (Caco-2). The proliferation assay used to detect the cytotoxic effect of 5-FU chemotherapy. The change in expression of chemoresistance related genes (AKT1, ABCG2 and MDR1) and cell survival related genes (survivin and beta-catenin) were evaluated by qRT-PCR and western blotting at 48hrs and 72hrs after CD133 siRNA transfection. Results: The proliferation assay demonstrated the increased chemoresistance of colon cancer cells after inhibition of CD133 expression when 5µM 5-FU was treated (p=0.0014). The mRNA expression of chemoresistance related genes (AKT1, ABCG2, MDR1) and cell survival related genes (survivin and β-catenin) were all significantly increased after transfection (p<0.05) but there was no significant changes in expression at the protein level of all genes. Conclusions: The inhibition of CD133 expression in CD133+colon cancer cell line induce the chemoresistance to 5-FU chemotherapy through the increased expression of chemoresistance related genes. Therefore, CD133 expression seems to be related with the chemosensitivity to 5-FU in colon cancer despite the mechanism needs to be proven. Citation Format: Mi-Ra Lee, Sun-Young Ji, Khalilullah Mia-Jan, Mee-Yon Cho. Inhibition of CD133 expression induce the chemoresistance to 5-fluorouracil in the colon cancer cell line. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 219. doi:10.1158/1538-7445.AM2014-219

Background: The DNA methylation change is known to play a crucial role in early gastric carcinogenesis. However, its association with the histologic subtypes of EGCs has not been fully elucidated. In this study, we aim to know whether the subtypes of early gastric carcinomas (EGCs) are related to the differences of DNA methylation or not using genome wide methylation assay. Materials and Method: The comprehensive methylation analysis was performed by Illumina Infinium methylation assay (IIMA, 450K BeadChip kit) covering 450,000 sites on 12 tumors and 12 matched non-tumor mucosa from 12 patients with EGC. Hisytologically, the EGCs were devided into intestinal type (group A, n=6) and non-intestinal type (group B, diffuse=4 and mixed=2). The CpG sites in 450K microarray chip are classified into CpG islands, shores (2kb), shelves (2kb∼4kb) and open sea (>4kb) by CpG content and neighborhood context. According to the functional genomic distribution they are classified into promoter, body, 3′UTR and intergenic. To determine DMRs, average β-values were computed with β-values in signal intensity of over 3000. The Δβ-value was a result substracted average β-value of one from the other. When Δβ is over 0.2 or below -0.2, it was considered to be meaningful and refered to differentially methylated regions (DMRs) . Results: There were 484 DMRs in group A tumor and 208 DMRs in group B. The pattern of DMRs were different between two groups. In group A tumor, most of DMRs (97.73%) were hypermethylated and 75.26% were in CpG island. On the other hand, the group B tumors showed that 63.94% of DMRs were hypermethylated and only less than half of them (48.87%) were in CpG island. In terms of functional genomic distribution of DMRs, promoter (38.66%) was the most common site in group A while body (54.14%) was in group B. On Hierarchical clustering analysis, the clear grouping was made by 208 DMRs in three cases, two of them being mixed-type, by both correlation and Euclidean methods. However, no distinct grouping was found with DMRs in group A. Hierarchical clustering analysis of non-tumor mucosa showed a distinct separation between group A and B. Conclusions: DNA methylation pattern was distinctively different between the histologic subtype of EGCs. In the intestinal type of EGCs, the DNA methylation seems to be started in non-tumor mucosa. Citation Format: Khalilullah Mia-Jan, Hoon Ryu, Mi-Ra Lee, Sun-Young Ji, Mee-Yon Cho. Differences of DNA methylation patterns according to histologic subtypes of early gastric carcinomas. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 421. doi:10.1158/1538-7445.AM2014-421