Epigenetic Downregulation and Growth Inhibition of IGFBP7 in Gastric Cancer.

Background: Insulin-like growth factor-binding protein 7 (IGFBP7) has been found to be a tumor suppressor in several human cancers, but the role of IGFBP7 in gastric cancer has not yet been fully investigated. Herein, we examined the epigenetic downregulation of IGFBP7 expression in gastric cancer. Methods: Expression and methylation of IGFBP7 in gastric cancer cells and primary gastric cancer patients were determined using qRT-PCR, western blot, immunohistochemistry, and methylation specific-PCR, respectively.

Acyl-CoA thioesterase 7 is involved in cell cycle progression via regulation of PKCζ-p53-p21 signaling pathway.

Acyl-CoA thioesterase 7 (ACOT7) is a major isoform of the ACOT family that catalyzes hydrolysis of fatty acyl-CoAs to free fatty acids and CoA-SH. However, canonical and non-canonical functions of ACOT7 remain to be discovered. In this study, for the first time, ACOT7 was shown to be responsive to genotoxic stresses such as ionizing radiation (IR) and the anti-cancer drug doxorubicin in time- and dose-dependent manners.

Expression of the ERBB Family of Ligands and Receptors in Gastric Cancer.

Objective: Gastric cancer (GC) is the second most common cancer and the third leading cause of cancer-related death in Korea. Alterations in the ERBB (homology to the erythroblastoma viral gene product, v-erbB) receptor family and ERBB-related signaling pathways are frequently observed in GC. However, the roles of the ERBB receptors and their ligands in GC are not well established.

FOXO1 Suppression is a Determinant of Acquired Lapatinib-Resistance in HER2-Positive Gastric Cancer Cells Through MET Upregulation.

Purpose: Lapatinib is a candidate drug for treatment of trastuzumab-resistant, human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). Unfortunately, lapatinib resistance renders this drug ineffective. The present study investigated the implication of forkhead box O1 (FOXO1) signaling in the acquired lapatinib resistance in HER2-positive GC cells.

HER2-induced metastasis is mediated by AKT/JNK/EMT signaling pathway in gastric cancer.

Aim: To investigated the relationships between HER2, c-Jun N-terminal kinase (JNK) and protein kinase B (AKT) with respect to metastatic potential of HER2-positive gastric cancer (GC) cells.

Methods: Immunohistochemistry was performed on tissue array slides containing 423 human GC specimens. Using HER2-positve GC cell lines SNU-216 and NCI-N87, HER2 expression was silenced by RNA interference, and the activations of JNK and AKT were suppressed by SP600125 and LY294002, respectively.

Hypoxic inactivation of glycogen synthase kinase-3β promotes gastric tumor growth and angiogenesis by facilitating hypoxia-inducible factor-1 signaling.

Since the molecular mechanism of hypoxic adaptation in cancer cells is cell-type specific, we investigated whether glycogen synthase kinase-3β (GSK-3β) activation is involved in hypoxia-induced gastric tumor promotion. Stable gastric cancer cell lines (SNU-638, SNU-484, MKN1, and MKN45) were cultured under hypoxic conditions. Cells overexpressing wild-type GSK-3β (WT-GSK-3β) or kinase-dead mutant of GSK-3β (KD-GSK-3β) were generated and used for cell culture and animal studies.

c-Jun N-terminal kinase activation has a prognostic implication and is negatively associated with FOXO1 activation in gastric cancer.

Background: Since the biological function of c-Jun N-terminal kinase (JNK) in gastric cancer remains unclear, we investigated the clinical significance of JNK activation and its association with FOXO1 activation.

Methods: Immunohistochemical tissue array analysis of 483 human gastric cancer specimens was performed, and the results of the immunostaining were quantified. The correlation between JNK activation (nuclear staining for pJNK) and clinicopathological features, the proliferation index, prognosis or FOXO1 inactivation (cytoplasmic staining for pFOXO1) was analyzed.

Loss of FOXO1 promotes gastric tumour growth and metastasis through upregulation of human epidermal growth factor receptor 2/neu expression.

Background: The biological significance of FOXO1, a member of the forkhead box O transcription factor family, in gastric cancer (GC) remains unclear. The present study provides direct evidence of the role of FOXO1 in tumour growth and metastasis of GC in relation to human epidermal growth factor receptor 2 (HER2).

Methods: The expressions of FOXO1 and HER2 were modulated in GC cell lines (SNU-638, MKN45, SNU-216 and NCI-N87) by stable transfections.

Prognostic significance of leucine-rich-repeat-containing G-protein-coupled receptor 5, an intestinal stem cell marker, in gastric carcinomas.

Background: Cells expressing LGR5, an intestinal stem cell marker, have been suggested as cancer stem cells in human colon cancers. Previously, we discovered that LGR5-expressing cells exist in the gastric antrum and remarkably increase in number in intestinal metaplasia. In addition, most gastric adenomas contain abundant LGR5-expressing cells coexpressing intestinal stem cell signatures.

Olfactomedin-related proteins 4 (OLFM4) expression is involved in early gastric carcinogenesis and of prognostic significance in advanced gastric cancer.

Olfactomedin 4 (OLFM4) has been demonstrated to be upregulated in various cancers and involved in many cellular processes such as cell adhesion, apoptosis, and cell proliferation. In gastric cancer, clinicopathological relevance of OLFM4 expression has been reported. However, there are few studies showing how expression of OLFM4 evolves during multistep gastric carcinogenesis.

Intestinal Stem Cell Markers in the Intestinal Metaplasia of Stomach and Barrett's Esophagus.

Gastric intestinal metaplasia (IM) is a highly prevalent preneoplastic lesion; however, the molecular mechanisms regulating its development remain unclear. We have previously shown that a population of cells expressing the intestinal stem cell (ISC) marker LGR5 increases remarkably in IM. In this study, we further investigated the molecular characteristics of these LGR5+ cells in IM by examining the expression profile of several ISC markers.

Signal transducers and activators of transcription 3-induced metastatic potential in gastric cancer cells is enhanced by glycogen synthase kinase-3β.

The transcription factor signal transducers and activators of transcription 3 (STAT3) can promote cancer metastasis, but its underlying regulatory mechanisms in gastric cancer cell invasiveness still remain obscure. We investigated the relationship between STAT3 and glycogen synthase kinase-3β (GSK-3β) and its significance in metastatic potential in gastric cancer cells. Immunohistochemical tissue array analysis of 267 human gastric carcinoma specimens showed that the expressions of active forms of STAT3 (pSTAT3) and GSK-3β (pGSK-3β) were found in 68 (25%) and 124 (46%) of 267 gastric cancer cases, respectively, showing a positive correlation (p < 0.

Forkhead Transcription Factor FOXO1 Inhibits Angiogenesis in Gastric Cancer in Relation to SIRT1.

Purpose: We previously reported that forkhead transcription factors of the O class 1 (FOXO1) expression in gastric cancer (GC) was associated with angiogenesis-related molecules. However, there is little experimental evidence for the direct role of FOXO1 in GC. In the present study, we investigated the effect of FOXO1 on the tumorigenesis and angiogenesis in GC and its relationship with SIRT1.

Bile acid induces MUC2 expression and inhibits tumor invasion in gastric carcinomas.

Purpose: Bile acids might induce mucin expression and regulate tumor behavior in esophageal and colon cancers. However, little is known about the effect of bile acids on tumor invasiveness of gastric carcinoma (GC). The aim of the current study was to elucidate the mechanisms by which bile acids regulate tumor invasion in GC.

Forkhead transcription factor FOXO1 inhibits nuclear factor-κB in gastric cancer.

FOXO1, a forkhead box O (FOXO) transcription factor, and nuclear factor-κB (NF-κB) are prognostically significant transcription factors in gastric cancer. As their relationship has been inconsistent depending on the cell type, we aimed to investigate whether FOXO1 is associated with NF-κB p65 (RelA) in gastric cancer. Immunohistochemistry was performed on tissue array slides containing 298 gastric carcinoma specimens.

Distribution of LGR5+ cells and associated implications during the early stage of gastric tumorigenesis.

Lgr5 was identified as a promising gastrointestinal tract stem cell marker in mice. Lineage tracing indicates that Lgr5(+) cells may not only be the cells responsible for the origin of tumors; they may also be the so-called cancer stem cells. In the present study, we investigated the presence of Lgr5(+) cells and their biological significance in normal human gastric mucosa and gastric tumors.

The forkhead transcription factor FOXO1 mediates cisplatin resistance in gastric cancer cells by activating phosphoinositide 3-kinase/Akt pathway.

Background: Cisplatin (CDDP) is one of the most important chemotherapeutic agents in the treatment of advanced gastric cancer, but its efficacy is limited by CDDP resistance. Because the transcription factor FOXO1 is related to chemoresistance in various cancer cells, we investigated the function of FOXO1 in CDDP resistance in human gastric cancer cells.

Methods: Human gastric cancer cell lines MKN45 and SNU-601 were used.

DNA damage response-related proteins in gastric cancer: ATM, Chk2 and p53 expression and their prognostic value.

Objectives: The aims of this study were to assess expressions of the DNA damage response (DDR)-related proteins and to investigate their clinical significances in gastric carcinoma.

Methods: Two independent cohorts, a training set (n=524) and validation set (n=394), of gastric cancer patients were enrolled. Ataxia telangiectasia mutated (ATM), checkpoint kinase 2 (Chk2), and p53 expressions were examined by immunohistochemistry using tissue microarray.

Epstein-Barr virus-encoded BARF1 promotes proliferation of gastric carcinoma cells through regulation of NF-κB.

In Epstein-Barr virus (EBV)-infected gastric carcinoma, EBV-encoded BARF1 has been hypothesized to function as an oncogene. To evaluate cellular changes induced by BARF1, we isolated the full-length BARF1 gene from gastric carcinoma cells that were naturally infected with EBV and transfected BARF1 into EBV-negative gastric carcinoma cells. BARF1 protein was primarily secreted into culture supernatant and only marginally detectable within cells.

A synergistic interaction between transcription factors nuclear factor-κB and signal transducers and activators of transcription 3 promotes gastric cancer cell migration and invasion.

Background: The transcription factor nuclear factor-κB (NF-κB) has been implicated in gastric cancer metastasis, but the underlying molecular mechanisms remain unclear. We investigated the role of the interaction between NF-κB and signal transducers and activators of transcription 3 (STAT3) in controlling metastatic potential of gastric cancer cells.

Methods: Immunohistochemistry for NF-κB p65 (RelA), phospho-Tyr705-STAT3 (pSTAT3), or matrix metalloproteinase 9 (MMP9) was performed on tissue array slides containing 255 gastric carcinoma specimens.

Concordance of ATM (ataxia telangiectasia mutated) immunohistochemistry between biopsy or metastatic tumor samples and primary tumors in gastric cancer patients.

ATM (ataxia telangiectasia mutated) is one of several DNA repair proteins that are suggested to sensitize tumor cells to the poly(ADP-ribose) polymerase inhibitor olaparib when deficient. The aim of this study was to assess the spatiotemporal concordance of ATM immunohistochemistry (IHC) in gastric cancer in order to determine if measurements made at the level of various sample types and times could be inferred as having the potential to be relevant to treatment decisions made at the patient level. Two independent cohorts composed of 591 gastric cancer patients divided into a gastrectomy cohort (n = 450) and a metastasis cohort (n = 141) were used in this study.

Caveolin 1 expression correlates with poor prognosis and focal adhesion kinase expression in gastric cancer.

Objective: Caveolin 1 gene is known as a tumor promoter or suppressor, depending on the tumor type and/or tumor stage. We aimed to investigate the clinical significance of caveolin 1 protein (Cav1) expression in gastric cancer (GC).

Methods: Immunohistochemistry was performed on tissue array slides containing 405 GC specimens.

Constitutive activation of signal transducers and activators of transcription 3 correlates with better prognosis, cell proliferation and hypoxia-inducible factor-1α in human gastric cancer.

Objective: We aimed to investigate the biological significance of signal transducers and activators of transcription 3 (STAT3) in gastric carcinoma.

Methods: Immunohistochemistry was performed on tissue array slides containing 285 gastric carcinoma specimens. The relationship between the nuclear expression of phospho-Tyr705-STAT3 (pSTAT3), an active form of STAT3, and prognosis, clinicopathological factors, proliferation, cell cycle regulators, apoptosis regulators, or angiogenesis-related proteins was evaluated.

Constitutive phosphorylation of the FOXO1 transcription factor in gastric cancer cells correlates with microvessel area and the expressions of angiogenesis-related molecules.

Background: Although FOXO transcription factors may have an anti-angiogenic role, little is known about their role in tumor angiogenesis. The present study was performed to investigate the correlation between the constitutive expression of phosphorylated FOXO1 (pFOXO1) and angiogenesis in gastric cancer.

Methods: Immunohistochemistry was performed on tissue array slides containing 272 gastric carcinoma specimens, and the correlations between the cytoplasmic pFOXO1 expression in gastric cancer cells and CD34-immunopositive microvessel area (MVA) or the expressions of angiogenesis-related molecules were analyzed.