Article: Induction of LGR5 by H2O2 treatment is associated with cell proliferation via the JNK signaling pathway in colon cancer cells.[show abstract] [hide abstract]
ABSTRACT: Recently, the leucine-rich repeat G protein-coupled receptor 5 (LGR5/GPR49) was identified as a potential marker of intestinal stem cells in human. The LGR5 is known as a Wnt signaling target gene, and its expression pattern is related with β-catenin mutation. H2O2 is a member of reactive oxygen species (ROS) and regulates metabolism, aging, apoptosis and the intensity of growth factor signaling. In addition, it acts as a negative or positive regulator of Wnt signaling. However, the effect of H2O2 on Wnt signaling and its target gene LGR5 is not clear. In this study, we investigated the effects of ROS on cancer stem cells, in colorectal cancer cells. Colorectal cancer cells were treated with exogenous H2O2, after which cellular responses and the expression of LGR5 were examined. In SNU-C2A cells, proliferation increased following treatment with 50-300 µM of H2O2, whereas cell viability significantly decreased after treatment with 600-900 µM of H2O2. Expression of heme oxygenase (HO)-1 and jun, which aid in the reduction of oxidative stress, were induced in the low dose H2O2-treated SNU-C2A cells. The LGR5 expression level was significantly increased following 50-300 µM H2O2 treatment; in addition, β-catenin was increased in H2O2-treated colon cancer cells. However, the increased β-catenin was detected not in the nucleus but in the cytoplasm, which means that β-catenin was stabilized in the cytoplasm and not translocated into the nucleus where it could function as a transcription factor for the expression of LGR5. In addition, there was no direct interaction between LGR5 and β-catenin. In this study, we found that LGR5 expression increased when cancer cells were treated with a low dose of H2O2. Our results indicate that the LGR5 increase resulted via activation of the JNK signaling pathway. The induction of LGR5 expression influenced cell proliferation in colorectal cancer cells.International Journal of Oncology 08/2012; 41(5):1744-50. · 2.40 Impact Factor
Article: Establishment and characterization of six human gastric carcinoma cell lines, including one naturally infected with Epstein-Barr virus.Ja-Lok Ku, Kyung-Hee Kim, Jin-Sung Choi, Sung-Hee Kim, Young-Kyoung Shin, Hee Jin Chang, Jae-Moon Bae, Young-Woo Kim, Jun Ho Lee, Han-Kwang Yang, Woo-Ho Kim, Seung-Yong Jeong, Jae-Gahb Park[show abstract] [hide abstract]
ABSTRACT: We report the characterization of six new gastric carcinoma cell lines (designated NCC-19, NCC-20, NCC-24, NCC-59, SNU-1750 and SNU-1967) established from primary tumor samples of Korean patients. Four cell lines grew as adherent monolayers, one as both adherent and floating cell clumps and one as floating cell aggregates. The cell phenotypes, including the histopathology of the primary tumors and in vitro growth characteristics, were determined. We also performed molecular characterization, including DNA fingerprinting analysis and abnormalities of K-ras, p53, β-catenin, and TGF-βRII genes by PCR-SSCP and sequencing analyses. Population doubling times varied from 47-135 h. All cell lines showed relatively high viability, absence of mycoplasma or bacteria contamination and genetic heterogeneity by DNA fingerprinting analysis. Three lines had p53 mutations; one line had mutations in codon 13 (Gly13Asp) in K-ras and no line had a β-catenin mutation. NCC-59 cell line had a -1-bp mutation in 10-bp poly deoxy adenine repeat tract of the TGF-βRII gene. Moreover, NCC-24 gastric cancer cell line was found to be infected with Epstein-Barr virus (EBV). EBV infection was also shown in the original carcinoma tissue of the NCC-24 cell line. These well-characterized six gastric cancer cell lines should serve as useful tools for investigating the biological characteristics of gastric cancer and, in particular, NCC-24 may serve as a valuable model system to clarify the precise role of EBV in gastric carcinogenesis.Cellular oncology (Dordrecht). 02/2012; 35(2):127-36.
Article: Resistance of colorectal cancer cells to radiation and 5-FU is associated with MELK expression.Seungho Choi, Ja-Lok Ku[show abstract] [hide abstract]
ABSTRACT: It was reported that the local recurrence would be caused by cancer stem cells acquiring chemo- and radio-resistance. Recently, one of the potential therapeutic targets for colorectal and other cancers has been identified, which is maternal embryonic leucine zipper kinase (MELK). MELK is known as an embryonic and neural stem cell marker, and associated with the cell survival, cell proliferation, and apoptosis. In this study, SNU-503, which is a rectal cancer cell line, was treated with radiation or 5-fluorouracil (5-FU), and elevation of the MELK expression level was observed. Furthermore, the cell line was pre-treated with small interfering RNA (siRNA) against MELK mRNA before treatment of radiation or 5-FU and its effects on cell cycle and proliferation were observed. We demonstrated that knockdown of MELK reduced the proliferation of cells with radiation or 5-FU treatment. In addition, MELK suppression caused changes in cell cycle. In conclusion, MELK could be associated with increased resistance of colorectal cancer cells against radiation and 5-FU.Biochemical and Biophysical Research Communications 07/2011; 412(2):207-13. · 2.48 Impact Factor
Article: Establishment and characterization of six human lung cancer cell lines: EGFR, p53 gene mutations and expressions of drug sensitivity genes.Ja-Lok Ku, Kyung-Hee Kim, Jin-Sung Choi, You-Kyung Jeon, Sung-Hee Kim, Young-Kyoung Shin, Tae-You Kim, Yung-Jue Bang, Woo Ho Kim, Jae-Gahb Park[show abstract] [hide abstract]
ABSTRACT: Six human lung cancer cell lines (SNU-371, SNU-963, SNU-1327, SNU-1330, SNU-2292 and SNU-2315) were newly established through primary cell cultures. These cell lines were derived from a pulmonary blastoma, a small cell lung cancer, three adenocarcinomas and a squamous cell carcinoma of the lung of six Korean lung cancer patients. The histopathology of the primary tumors and their in vitro growth characteristics were described. DNA fingerprinting analysis and genetic alterations in the p53, β-catenin, TGFβRII, K-ras and EGFR genes were conducted. mRNA expressions levels of E-cadherin, COX-2, MDR1, MXR, CGA, synatophysin and TTF1 genes were investigated and sensitivity to anticancer drugs was screened. Five cell lines grew as adherent cells and one cell line grew as floating aggregates. All lines were free of mycoplasma or bacteria and were proven unique by DNA fingerprinting analysis. A significant polymorphism at codon 72 (Arg to Pro) of the p53 gene was found in one line (SNU-1327) and a mutation at codon 176 was found in SNU-2292. No mutations in the K-ras, β-catenin and TGF-βRII genes were observed. E-cadherin was not expressed in SNU-371 and COX-2 was overexpressed in SNU-1330, SNU-2292 and SNU-2315 cell lines. MDR1 was overexpressed in SNU-371 and SNU-2292 cell lines and MXR was overexpressed in SNU-1327 cell line. Interestingly, the SNU-371 cell line derived from a pulmonary blastoma and which overexpressed MDR1 displayed cross resistance for several anticancer drugs. Neuroendocrine markers, chromogranin A and synaptophysin, were overexpressed in the small cell lung cancer cell line, SNU-963 and thyroid transcription factor-1 was also over expressed in this cell line. Two mutations (p.Glu746_Ser752delinsVal and p.Glu746_Ala750del) in exon 19 of EGFR were found in SNU-1330 and SNU-2315 cell lines, respectively. These well-characterized lung cancer cell lines may be useful tools for investigations of the biological characteristics of lung cancers, particularly for investigations related to mutations of EGFR.Cellular oncology (Dordrecht). 02/2011; 34(1):45-54.
Article: Methylation-specific PCR.[show abstract] [hide abstract]
ABSTRACT: DNA methylation patterns in CpG-rich regions of promoter, CpG islands, are concerned in regulation of gene expression in mammalian cells. Excessive methylation of CpG dinucleotides in promoter represses the gene expression. In cancer, especially, gene silencing is occurred through aberrant methylation in promoter of tumor suppressor genes. Methylation-specific PCR (MSP) is a method for analysis of DNA methylation patterns in CpG islands. For performing MSP, DNA is modified by and PCR performed with two primer pairs, which are detectable methylated and unmethylated DNA, respectively. MSP is a rapid measure for assession of the methylation status in CpG island.Methods in molecular biology (Clifton, N.J.) 01/2011; 791:23-32.