Showing papers by "Sug Hyung Lee published in 2004"

Somatic mutations of CASP3 gene in human cancers.

Abstract: Failure of apoptosis is one of the hallmarks of cancer. As an execution-phase caspase, caspase-3 plays a crucial role during apoptosis. To explore the possibility that the genetic alterations of CASP3, which encodes caspase-3, might be involved in the development of human tumors, we analyzed the entire coding region and all splice sites of human CASP3 gene for the detection of somatic mutations in a series of 944 human tumors, including 165 stomach carcinomas, 95 colon carcinomas, 76 breast carcinomas, 80 hepatocellular carcinomas, 181 non-small cell lung cancers, 45 acute leukemias, 28 multiple myelomas, 12 medulloblastomas, 15 Wilms' tumors, 12 renal cell carcinomas, 40 esophagus carcinomas, 33 urinary bladder carcinomas, 33 laryngeal carcinomas, and 129 non-Hodgkin lymphomas. Overall, we detected 14 somatic mutations of the CASP3 gene, including six missense and four silent mutations, two mutations in the introns, one mutation in the 5'-untranslated region, and one mutation in the 3'-untranslated region. The mutations were observed in four of 98 colon carcinomas (4.1%), four of 181 non-small cell lung cancers (2.2%), two of 129 non-Hodgkin lymphomas (1.6%), two of 165 stomach carcinomas (1.2%), one of 80 hepatocellular carcinomas (1.3%), and one of 28 multiple myelomas (3.6%). This is the first report on CASP3 gene mutations in human tumors; these data indicate that the CASP3 gene is occasionally mutated in human tumors.

Genetic alterations of the KLF6 gene in gastric cancer.

Abstract: Increased oxygen free radicals produced in gastric mucosa by H. pylori induce DNA damage and lead to dyspalsia and gastric cancers. However, only a small percentage of individuals that carry H. pylori develop gastric cancer, indicating that other factors are involved. We have screened a set of 95 sporadic gastric cancers for mutations and allele loss of the DNA glycosylase MYH gene, which excises adenine misincorporated opposite unrepaired 8-oxoG. Two of 95 cancers had bi-allelic mutations of the MYH gene with somatic missense mutation of one allele and loss of the remaining allele. The mutations were missense mutations, P391S and Q400R, in exon 13 encoding NUDIX hydrolase domain of the gene. The patients were H. pylori-positive and the tumors were of advanced intestinal-type gastric cancer with lymph node metastasis. In addition, 4 (17.4%) of 23 informative cases showed allele loss at MYH locus. Therefore, our data suggest that somatic mutations of base excision repair gene MYH contribute to the development of a sub-set of sporadic gastric cancers.

Loss of caspase-2, -6 and -7 expression in gastric cancers.

Abstract: Caspases play an essential role during apoptotic cell death, and alterations of caspases are known to contribute to human cancer development. In the current study, we analyzed the expression of caspase-2, -6 and -7 in 120 gastric carcinomas by immunohistochemistry using a tissue microarray approach. Caspase-2, -6 and -7 were expressed in 42 (35%), 63 (53%) and 39 (33%) of the gastric cancers, respectively. By contrast, the surface mucous cells and mucosal glandular cells in the normal gastric mucosa showed strong immunoreactivity for caspase-2, -6 and -7. Taken together, these results indicate that caspase-2, -6 and -7 expression in gastric cancer cells is decreased compared to in normal gastric mucosal cells, and suggest that loss of caspase-2, -6 and -7 expression might be involved in the mechanisms of gastric cancer development.

Altered expression of KCNK9 in colorectal cancers.

Abstract: K(+) channels have been reported to be involved in the proliferation of many types of cells, including some human carcinoma and tumor cell lines. KCNK9, a TASK channel, is amplified and overexpressed in several types of human cancer. In the present study, we examined the expression and somatic mutations of KCNK9 in 124 colorectal cancers by immunohistochemistry using tissue microarray and PCR-SSCP. Immunopositivity was observed in 57 (46.0%) of 124 colorectal cancers. Clinically, KCNK9 was immunopositive in 4 (30.7%) of 13 cases which were stage A, 26 (55.3%) of 47 which were stage B, 23 (41.1%) of 56 which were stage C, and 4 (50%) of 8 which were stage D. Statistically, KCNK9 protein expression was not related to tumor stage (Bartholomew test, p>0.05) and lymph node metastasis (Chi-Square test, p=0.8338). In the mutation study of the KCNK9 gene, we found only one sequence variation (ACG-->ACC, Thr-->Thr) at codon 170 both in corresponding normal and tumor DNAs. These results indicate that overexpression rather than mutation of the KCNK9 gene may contribute to the development of colorectal cancers and suggest that the development of KCNK9-targeted agents may provide new possibilities in the treatment of colorectal cancer.

Inactivating mutations of proapoptotic Bad gene in human colon cancers.

Abstract: Evidence exists that deregulation of apoptosis is involved in the mechanisms of cancer development, and the somatic mutations of apoptosis-related genes have been reported in human cancers. Bcl-X L /Bcl-2-associated death promoter (Bad), a proapoptotic member of Bcl-2 family, plays an important role in the intrinsic apoptosis pathway. To explore the possibility that the genetic alterations of Bad might be involved in the development of human cancers, we analyzed the entire coding region and all splice sites of human Bad gene in 47 colon adenocarcinomas. Overall, we detected two somatic missense mutations (4.3%) in Bad gene. Interestingly, both of the Bad mutations were detected in the gene sequences encoding the Bcl-2 homology3 domain of Bad, which has a crucial role in inducing cell death. Transfection study revealed that both of the tumor-derived Bad mutants had decreased apoptosis activities compared with the wild-type Bad, indicating that the Bad mutations reduced the cell death function of Bad. Co-immunoprecipitation assay revealed that binding of one of the tumor-derived Bad mutants with Bcl-2 and Bcl-X L is reduced. This is the first report on Bad gene mutation in human malignancies, and our data suggest that Bad gene is occasionally mutated in colon cancers and that somatic mutation of Bad may contribute to the development of colon cancers.

Inactivating mutation of the pro-apoptotic gene BID in gastric cancer.

Abstract: There is evidence that deregulation of apoptosis is mechanistically involved in cancer development and somatic mutations of apoptosis-related genes have been reported in human cancers. BID, a pro-apoptotic member of the Bcl-2 family, interconnects the extrinsic apoptosis pathway initiated by death receptors to the intrinsic apoptosis pathway. To explore the possibility that genetic alterations of BID might be involved in the development of human cancers, this study analysed the entire coding region and all splice sites in the human BID gene in 67 advanced gastric carcinomas. Overall, four BID mutations (6.0%) were detected that consisted of one frameshift and three missense mutations. The tumour-derived BID mutants were expressed in 293T cells and it was found that, compared with wild-type BID, the frequency of apoptosis was significantly reduced in cells expressing the gene containing the frameshift mutation. Furthermore, expression of the inactivating frameshift mutant interfered with cell death by overexpression of death receptors, indicating that this mutant inhibits the extrinsic apoptosis pathway in a dominant-negative fashion. Also, the frameshift mutation rendered cancer cells resistant to apoptosis induced by the anti-cancer drug 5-fluorouracil (5-FU). This is the first report of BID gene mutation in human malignancy. The data suggest that such mutations occur rarely in gastric cancers and that only a small fraction of BID mutations may lead to the loss of its apoptotic function.

Inactivating mutations of the Siah-1 gene in gastric cancer.

Abstract: Siah-1 is the mammalian homolog of Drosophila seven in absentia (sina) and has been identified as a p53-inducible gene. Siah-1 can induce cell cycle arrests, tumor suppression, and apoptosis through a novel β-catenin degradation pathway. To determine whether genetic alterations of Siah-1 gene are involved in the development and/or progression of gastric cancer, we searched for mutation of the Siah-1 gene in 95 gastric cancers by single-strand conformational polymorphism and sequencing. The effect of Siah-1 on β-catenin degradation was further examined in wild- and mutant-type Siah-1-transfected HEK 293T cells. We found two missense mutations of the Siah-1 gene. The cases with Siah-1 mutation showed nuclear translocation and cytoplasmic staining of β-catenin. Interestingly, two mutants of Siah-1 stabilized cytoplasmic levels of β-catenin, even after treatment of adriamycin. Furthermore, both mutants failed to suppress cyclin D1 expression and to induce apoptosis. These data suggest that inactivating mutations of the Siah-1 may contribute to the development of gastric cancer through β-catenin stabilization and apoptosis block.

Colorectal tumors frequently express phosphorylated mitogen-activated protein kinase

Abstract: Mounting evidence suggests that activation of the mitogen-activated protein (MAP) kinase pathway plays an important role in tumorigenesis. MAP kinase/ERK kinase (MEK), a crucial constituent of this pathway, is activated by phosphorylation, and the phosphorylated MEK (pMEK) in turn activates ERK kinase. The expression of pMEK has been described in some human malignancies, but not in primary human colon tumors. In this study, we analyzed the expression of pMEK in 123 colorectal tumors by immunohistochemistry. pMEK was detected either in the cytoplasm (63 cases) or nucleus (40 cases) in 93 of the 123 tumors (76%). Tubular adenomas and villous adenomas also expressed pMEK in 30% and 40% of the tumors, respectively. By contrast, the epithelial cells in the normal colonic mucosa showed no or only weak expression of pMEK in the cytoplasm. Taken together, these results indicate that MEK is frequently phosphorylated in colorectal tumors, and suggest that phosphorylation of MEK may play a role in the development of colorectal tumors.

Mutational Analysis of the Epidermal Growth Factor Receptor Gene in Gastrointestinal Stromal Tumors

Abstract: Purpose: Most gastrointestinal stromal tumors (GISTs) have gain-of-function mutations of the KIT or the platelet-derived growth factor receptor alpha (PDGFRA) genes, but approximately of the GISTs are wild types for both the KIT and the PDGFRA genes. The purpose of this study was to investigate the possibility that epidermal growth factor receptor (EGFR) gene mutation might be responsible for the pathogenesis of GIST. Materials and Methods: We analyzed the EGFR gene in 60 GISTs for the detection of somatic mutations by using the polymerase chain reaction (PCR), the single strand conformation polymorphism (SSCP), and DNA sequencing in exon 18, 19, and 21 encoding the kinase domain. Results: The SSCP analysis revealed no evidence of EGFR mutations in exon 18, 19, and 21 in GISTs. Conclusion: The data indicate that the EGFR gene may not be mutated in human GIST and suggest that therapies targeting the mutated EGFR gene products might not be useful in the treatment of GISTs.

Mutation of FADD gene is rare in human colon and stomach cancers

Abstract: Failure of apoptosis is one of the hallmarks of cancer. As an adaptor, FADD plays a crucial role during death receptor-mediated apoptosis. We previously reported that the FADD gene is somatically mutated in non-small cell lung cancers. To explore the possibility that the genetic alterations of the FADD gene might be involved in the development of other human cancers, we analyzed the entire coding region and all splice sites of the human FADD gene to detect somatic mutations in 116 stomach cancers and 98 colon cancers. Overall, we detected a somatic missense mutation of the FADD gene in a colon carcinoma, which was predicted to change an amino acid (R140H) in the death domain (DD) of the FADD protein. This is the first report of FADD gene mutation in gastrointestinal cancers, and our data suggest that the FADD gene is rarely mutated in human colon and stomach cancers.

Minute excision system and minute excision method using the system

Abstract: The present invention relates to a microdissection system, comprising a stage device having a gathering box stage for moving a gathering box holder in which a body is disposed in a lengthy direction and a cap is inserted into an insertion hole between holder insertion units; an optical channel for a first optical axis of a microscope device; and an optical channel for a second optical axis having a dichroic mirror through which the first optical axis passes and a correction unit between observing units of the microscope device, wherein the dichroic mirror can refract the second optical axis of a laser beam generated from a laser device toward an objective lens of the microscope device. Therefore, compactness, high definition, easy manipulation, rapidness and exactness of a microdissection work, an increased rate of regions for a dissected cell or a tissue gathered, accurate microdissection, and reduced cost are accomplished. Further, the present invention provides a microdissection method in which optical definition of a tissue slice when observing the tissue slice using a microscope can be sufficiently improved, and a tissue slice of a cell having a thick tissue can be dissected rapidly and exactly while keeping high optical definition using a laser beam generated by a laser device whose energy and frequency can be controlled and a microdissection system having a focus correction unit.

CARD3X-2 polypeptides, encoding nucleic acids, and methods of use

Abstract: The invention provides a polypeptide corresponding to a newly identified splice variant of the CARD3X gene, termed CARD3X-2. Also provided by the invention is an encoding nucleic acid molecule, as well as a CARD3X-2 specific antibody. The invention further provides related screening, diagnostic and therapeutic methods.