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Background/aim: Sunitinib continues to be administered as a first-line therapeutic agent in metastatic renal cell carcinoma (mRCC). This study aimed to examine the role of CD44 in sunitinib resistance and as a predictive marker in mRCC., Materials and Methods: We analyzed the effect of CD44 knockdown on sunitinib resistance in RCC cell lines using WST-1 assays. CD44 expression in mRCC patients treated with first-line sunitinib was determined by immunohistochemistry. We validated the findings of this study by in silico analysis., Results: CD44 knockdown increased sensitivity to sunitinib. Immunohistochemical analysis revealed that 19 (34.5%) of 55 mRCC cases were positive for CD44. CD44-positive cases were associated with poor progression-free survival (PFS) after first-line sunitinib treatment. In the JAVELIN 101 study, high CD44 expression was significantly associated with poor PFS after sunitinib but not after avelumab + axitinib therapy., Conclusion: CD44 is involved in sunitinib resistance and may be a promising marker for sunitinib treatment in mRCC., (Copyright © 2021 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background: MicroRNAs are a class of small noncoding RNAs that play an important role in progression and drug resistance in cancer. Several reports have shown that miR-130b modulates cell growth and drug resistance in some cancers. However, the expression and biological role of miR-130b in renal cell carcinoma (RCC) remain poorly understood. This study aimed to examine the expression and functional role of miR-130b and to analyze the association between miR-130b and sunitinib resistance in RCC., Methods: The expression of miR-130b in 32 RCC tissues and their corresponding normal kidney tissues was determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). We performed a 4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT) assay in RCC cell lines transfected with miR-130b inhibitor or miR-130b mimics. We evaluated the relationship between miR-130b and PTEN and also analyzed the effect of miR-130b on sunitinib resistance., Results: qRT-PCR analysis showed that the expression of miR-130b was higher in RCC tissues than in corresponding normal kidney tissues. The MTT assay revealed that miR-130b modulated cell growth. qRT-PCR revealed an inverse correlation between miR-130b and PTEN in RCC. Western blotting demonstrated that miR-130b regulated the expression of PTEN in the RCC cell line. Additionally, miR-130b was associated with sunitinib resistance through regulation of PTEN. We established the sunitinib-resistant Caki-1 (Caki-1-SR) cells and observed that the expression of miR-130b was elevated in Caki-1-SR cells compared with parental Caki-1 cells. Knockdown of miR-130b improved sunitinib resistance in Caki-1-SR cells., Conclusion: The expression of miR-130b was upregulated in RCC. miR-130b promoted cell growth and was associated with sunitinib resistance through regulating PTEN expression. Collectively, these results suggest that miR-130b may play an oncogenic role and be a promising therapeutic target., (© 2019 S. Karger AG, Basel.)

Objective: Spheroid colony formation is a useful method of cancer stem cell (CSC) characterization. We previously showed that the IQ motif containing the GTPase-activating protein 3 gene (IQGAP3) is upregulated in spheroid body-forming gastric cancer (GC) cells compared with parental cells. We investigated IQGAP3 expression in GC., Methods: IQGAP3 protein expression was analyzed by immunohistochemistry in 165 GC cases. RNA interference was used to inhibit IQGAP3 expression in GC cell lines., Results: In non neoplastic gastric mucosa, weak staining of IQGAP3 was observed in the foveolar epithelium, while GC tissue showed stronger, more extensive staining. Of the 165 GC cases, 34 (21%) were positive for IQGAP3 expression. GC cases positive for IQGAP3 were found more frequently in stage II/III/IV cases than in stage I cases. Univariate and multivariate analyses demonstrated that IQGAP3 expression is an independent prognostic classifier of GC patients. Both the number and size of the spheres formed by MKN-74 cells were significantly reduced by knockdown of IQGAP3. The phosphorylation of Akt and Erk1/2 was inhibited by knockdown of IQGAP3., Conclusion: These results suggest that IQGAP3 plays an important role in gastric CSCs. The location of IQGAP3 on the cell membrane makes it a potential therapeutic target for GC., (© 2017 S. Karger AG, Basel.)

Esophageal squamous cell carcinoma (ESCC) is one of the most common human cancers. We previously reported that KIFC1 is involved in gastric cancer pathogenesis and that KIFC1 plays an important role in gastric cancer spheroid colony formation. However, the significance of KIFC1 in ESCC has not been examined. In the present study, we analyzed the expression and distribution of KIFC1 in 132 ESCC cases by immunohistochemistry. In contrast to weak or no staining of KIFC1 in non-neoplastic mucosa, ESCC tissue showed stronger, more extensive KIFC1 staining. In total, 95 (72%) of 132 ESCC cases were positive for KIFC1. Immunostaining of ALDH1 was also performed, and KIFC1-positive ESCC cases were significantly frequently found in ALDH1-positive ESCC cases compared with ALDH1-negative ESCC cases. Spheroid colony formation is an effective method to characterize CSCs, thus we analyzed sphere number and size at 15days in ESCC cells downregulated for KIFC1 by siRNA transfection. Both the number and size of sphere from TE-1 cells were significantly reduced in KIFC1 siRNA-transfected TE-1 cells than in negative control siRNA-transfected cells. These results suggest that KIFC1 plays an important role in ESCC pathogenesis., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

Background: Transcribed ultraconserved regions (T-UCRs) are a novel class of noncoding RNAs that are highly conserved among the orthologous regions in most vertebrates. It has been reported that T-UCRs have distinct signatures in human cancers. We previously discovered the downregulation of T-UCR expression in gastric cancer (GC), indicating that T-UCRs could play an important role in GC biology. Uc.160+, a T-UCR reported to be downregulated in human cancer, has not been examined in GC., Methods: We analyzed the expression pattern of Uc.160+ in nonneoplastic and tumor tissues of the stomach by using uantitative reverse transcription polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH), specifically focusing on the mechanism of transcriptional regulation and target genes that are regulated by T-UCRs. We also attempted to determine the effect of Uc.160+ expression on biological features of GC cell lines by Western blotting., Results: On the basis of the qRT-PCR and ISH results, Uc.160+ expression in adenoma and GC tissues was clearly downregulated compared with that in nonneoplastic mucosa tissues of the stomach. Cancer-specific DNA methylation in the promoter region of Uc.160 was observed by bisulfite genomic DNA sequencing analysis. The effect of DNA methylation on Uc.160+ expression was further confirmed by reporter gene assay. We also revealed that Uc.160+ inhibited the phosphorylation of Akt by regulating phosphatase and tensin homolog (PTEN) expression., Conclusions: These results indicate that Uc.160+ could possibly have a tumor suppressive role in GC.

Objective: Gastric cancer (GC) is one of the most common human cancers. A useful method of gastric cancer stem cell (CSC) characterization is spheroid colony formation. Previously, we reported that KIF11 expression is >2-fold in spheroid-body-forming GC cells compared with parental cells. Here, we analyzed the expression and distribution of KIF11 in human GC by immunohistochemistry., Methods: Expression of KIF11 in 165 GC cases was determined using immunohistochemistry. For mucin phenotypic expression analysis of GC, immunostaining of MUC5AC, MUC6, MUC2 and CD10 was evaluated. RNA interference was used to inhibit KIF11 expression in GC cell lines., Results: In total, 119 of 165 GC cases (72%) were positive for KIF11. Expression of KIF11 was not associated with any clinicopathologic characteristics; however, it was observed frequently in GC exhibiting an intestinal phenotype. Both the number and size of spheres formed by MKN-74 cells were significantly reduced following transfection of KIF11-targeting siRNA compared with negative-control siRNA. Furthermore, levels of phosphorylated Erk1/2 were lower in KIF11 siRNA-transfected cells than with negative-control siRNA-transfected cells., Conclusion: These results indicate that KIF11 is involved in intestinal mucin phenotype GC., (© 2016 S. Karger AG, Basel.)

Mutations in TGFBR2, a component of the transforming growth factor (TGF)-β signaling pathway, occur in high-frequency microsatellite instability (MSI-H) colorectal cancer (CRC). In mouse models, Tgfbr2 inactivation in the intestinal epithelium accelerates the development of malignant intestinal tumors in combination with disruption of the Wnt-β-catenin pathway. However, no studies have further identified the genes influenced by TGFBR2 inactivation following disruption of the Wnt-β-catenin pathway. We previously described CDX2P-G19Cre;Apcflox/flox mice, which is stochastically null for Apc in the colon epithelium. In this study, we generated CDX2P-G19Cre;Apcflox/flox;Tgfbr2flox/flox mice, with simultaneous loss of Apc and Tgfbr2. These mice developed tumors, including adenocarcinoma in the proximal colon. We compared gene expression profiles between tumors of the two types of mice using microarray analysis. Our results showed that the expression of the murine homolog of GSDMC was significantly upregulated by 9.25-fold in tumors of CDX2P-G19Cre;Apcflox/flox;Tgfbr2flox/flox mice compared with those of CDX2P-G19Cre;Apcflox/flox mice. We then investigated the role of GSDMC in regulating CRC tumorigenesis. The silencing of GSDMC led to a significant reduction in the proliferation and tumorigenesis of CRC cell lines, whereas the overexpression of GSDMC enhanced cell proliferation. These results suggested that GSDMC functioned as an oncogene, promoting cell proliferation in colorectal carcinogenesis. In conclusion, combined inactivation of both Apc and Tgfbr2 in the colon epithelium of a CRC mouse model promoted development of adenocarcinoma in the proximal colon. Moreover, GSDMC was upregulated by TGFBR2 mutation in CRC and promoted tumor cell proliferation in CRC carcinogenesis, suggesting that GSDMC may be a promising therapeutic target., Competing Interests: The authors have declared that no competing interests exist.

The transcribed-ultraconserved regions (T-UCRs) are a novel class of non-coding RNAs, which are absolutely conserved (100%) between the orthologous regions of the human, rat and mouse genomes. Previous studies have described that several T-UCRs show differential expressions in cancers and might be involved in cancer development. We investigated the transcriptional levels of representative 26 T-UCRs and determined the regions that were differently expressed in prostate cancer (PCa) and gastric cancer (GC). A quantitative reverse transcription-polymerase chain reaction analysis revealed the downregulation of Uc.158+A expression by a DNA methylation-associated mechanism, which was restored by 5-Aza-dC (5-aza-2'-deoxycytidine) treatment. Bisulfite genomic sequencing using cell lines and tissue samples demonstrated cancer-specific CpG hypermethylation in both GC and PCa. However, Uc.416+A was only overexpressed in GC and we identified an miR-153 binding site in the possible regulatory region of Uc.416+A using online databases. Along with a forced expression or knockdown of miR-153 in MKN-74 GC cells, the transcriptional levels of Uc.416+A were significantly disturbed. A luciferase reporter gene assay supported the direct regulation of Uc.416+A expression by miR-153. Furthermore, Uc.416+A was associated with cell growth through the regulation of IGFBP6 (insulin-like growth factor-binding protein 6) in GC. These findings suggest an oncogenic role of Uc.416+A in GC, which suggests that our approach would provide new insights into functional studies of T-UCRs in cancer biology.

Background: Gastric cancer (GC) is the fifth commonest malignancy worldwide and still one of the leading causes of cancer-related death. The aim of this study was to identify a novel prognostic marker or therapeutic target for GC., Methods: We analyzed candidate genes from our previous Escherichia coli ampicillin secretion trap (CAST) libraries in detail, and focused on the FKTN gene because it was overexpressed in both GC cell line CAST libraries, MKN-1 and MKN-45., Results: Quantitative reverse transcriptase PCR analysis of FKTN revealed that FKTN messenger RNA was overexpressed in nine of 28 (32.1 %) GC tissue samples compared with nonneoplastic gastric mucosa. Immunostaining of fukutin showed that 297 of 695 cases (42.7 %) were positive for fukutin. Fukutin-positive GC cases were significantly associated with differentiated histological features, and advanced T grade and N grade. In addition, fukutin expression was observed more frequently in the intestinal phenotype (51 %) of GC than in other phenotypes (37 %) when defined by the expression patterns of mucin 5AC, mucin 6, mucin 2, and CD10. FKTN small interfering RNA treatment decreased GC cell proliferation., Conclusions: These results indicate that the expression of fukutin may be a key regulator for progression of GC with the intestinal mucin phenotype.

Background: Gastric cancer (GC) is one of the most common human cancers. Genes expressed only in cancer tissue, especially on the cell membrane, will be useful biomarkers for cancer diagnosis and therapeutics., Methods: To identify novel genes encoding transmembrane protein specifically expressed in GC, we generated an Escherichia coli ampicillin secretion trap (CAST) library from diffuse-type GC cell line MKN-45. CAST is a survival-based signal sequence trap method that exploits the ability of mammalian signal sequences to confer ampicillin resistance to a mutant β-lactamase lacking the endogenous signal sequence., Results: By sequencing 1,536 colonies, we identified 23 genes encoding the transmembrane protein present in GC. Among these genes, TSPAN8 (also known as CO-029 and TM4SF3) gene, which encodes transmembrane protein tetraspanin 8, was emphasized as a candidate. Immunohistochemical analysis of tetraspanin 8 in human GC tissues revealed that 72 (34 %) of 210 GC cases were positive for tetraspanin 8, and microvessel density was significantly higher in tetraspanin 8-positive GC than in tetraspanin 8-negative GC. Furthermore, univariate and multivariate analyses revealed that tetraspanin 8 expression is an independent prognostic classifier of patients with GC. TSPAN8 knockdown by siRNA reduced the invasion of GC cell line. The reduction of invasiveness was retrieved by the tetraspanin 8-containing exosome., Conclusion: These results suggest that tetraspanin 8 is involved in tumor progression and is an independent prognostic classifier in patients with GC.

Gastric cancer (GC) is one of the most common malignancies worldwide. In particular, scirrhous type GC is highly metastatic and is characterized clinically by rapid disease progression and poor prognosis. MicroRNAs (miRNAs) play crucial roles in cancer development and progression. We previously demonstrated by microarray analysis that microRNA-145 (miR-145) is one of the more highly expressed miRNAs in scirrhous type GC vs. non-scirrhous types of GC. In the present study, we investigated the role of miR-145 in scirrhous type GC. The expression levels of miR-145 assessed by quantitative RT-PCR were higher in scirrhous type GC tissue samples than in non-scirrhous type GC and corresponding normal tissues. GC patients with high miR-145 expression were at a more advanced tumor stage (P=0.0156) and had more scirrhous type histology (P=0.0054) than those with low miR-145 expression. Furthermore, miR-145 expression was significantly associated with poor prognosis in GC patients (P=0.0438). miR-145 expression was localized in stromal fibroblasts of scirrhous type GC but not in cancer cells. miR-145 was induced by treatment by transforming growth factor-β, and it enhanced the expression of α-smooth muscle actin, a marker of myofibroblasts, in both normal gastric fibroblasts and cancer-associated fibroblasts. These data suggest that miR-145 may contribute to the progression of scirrhous type GC by regulating activation of peri-tumoral fibroblasts.

Aims: Genes expressed only in cancer tissue or specific organs will be useful molecular markers. To identify genes that encode secreted proteins present in prostate cancer (PCa), we generated Escherichia coli ampicillin secretion trap (CAST) libraries from PCa and normal prostate (NP)., Methods and Results: We identified 15 candidate genes that encode secreted proteins present in PCa and NP. Quantitative RT-PCR analysis revealed that MSMB, NBL1 and AZGP1 were expressed with much higher specificity in PCa and NP than in 14 other kinds of normal tissue. We focused on NBL1, which was originally identified as a putative tumor suppressor gene. Western blot analysis revealed that NBL1 protein was highly expressed in both cell lysate and culture media of the DU145 PCa cell line. Immunohistochemical analysis showed that NBL1 expression was highly detected in and restricted to NP and PCa and was significantly down-regulated in PCa. NBL1 expression was significantly reduced according to the tumor stage, Gleason grade and preoperative prostate-specific antigen (PSA) value., Conclusion: NBL1 is a secreted protein that is highly restricted to the prostate. Underexpression of NBL1 correlated with PCa progression. NBL1 might be a candidate tumor marker for PCa in addition to PSA., (Copyright © 2012 S. Karger AG, Basel.)

REG4, which encodes Reg IV protein, is a member of the calcium-dependent lectin superfamily and potent activator of the epidermal growth factor receptor/Akt/activator protein-1 signaling pathway. Several human cancers overexpress Reg IV, and Reg IV expression is associated with intestinal phenotype differentiation. However, regulation of REG4 transcription remains unclear. In the present study, we investigated whether CDX2 regulates Reg IV expression in gastric cancer (GC) cells. Expression of Reg IV and CDX2 was analyzed by Western blot and quantitative reverse transcription-polymerase chain reaction in 9 GC cell lines and 2 colon cancer cell lines. The function of the 5'-flanking region of the REG4 gene was characterized by luciferase assay. In 9 GC cell lines, endogenous Reg IV and CDX2 expression were well correlated. Using an estrogen receptor-regulated form of CDX2, rapid induction of Reg IV expression was observed in HT-29 cells. Reporter gene assays revealed an important role in transcription for consensus CDX2 DNA binding elements in the 5'-flanking region of the REG4 gene. Chromatin immunoprecipitation assays showed that CDX2 binds directly to the 5'-flanking region of REG4. These results indicate that CDX2 protein directly regulates Reg IV expression.

The caudal-related homeobox transcription factor CDX2 has a key role in intestinal development and differentiation. CDX2 heterozygous mutant mice develop colonic polyps, and loss of CDX2 expression is seen in a subset of colon carcinomas in humans. Ectopic CDX2 expression in the stomach of transgenic mice promotes intestinal metaplasia, and CDX2 expression is frequently detected in intestinal metaplasia in the stomach and esophagus. We sought to define CDX2-regulated genes to enhance knowledge of CDX2 function. HT-29 colorectal cancer cells have minimal endogenous CDX2 expression, and HT-29 cells with ectopic CDX2 expression were generated. Microarray-based gene expression studies revealed that the Multidrug Resistance 1 (MDR1/P-glycoprotein/ABCB1) gene was activated by CDX2. Evidence that the MDR1 gene was a direct transcriptional target of CDX2 was obtained, including analyses with MDR1 reporter gene constructs and chromatin immunoprecipitation assays. RNA interference-mediated inhibition of CDX2 decreased endogenous MDR1 expression. In various colorectal cancer cell lines and human tissues, endogenous MDR1 expression was well correlated to CDX2 expression. Overexpression of CDX2 in HT-29 cells revealed increased resistance to the known substrate of MDR1, vincristine and paclitaxel, which was reversed by an MDR1 inhibitor, verapamil. These data indicate that CDX2 directly regulates MDR1 gene expression through binding to elements in the promoter region. Thus, CDX2 is probably important for basal expression of MDR1, regulating drug excretion and absorption in the lower gastrointestinal tract, as well as for multidrug resistance to chemotherapy reagent in CDX2-positive gastrointestinal cancers.

Wnt5a is a representative ligand that activates the beta-catenin-independent pathway in Wnt signaling. Although it has been reported that abnormal activation of the Wnt/beta-catenin-dependent pathway is often observed in human prostate cancer, the involvement of the beta-catenin-independent pathway in this cancer is unclear. Abnormal expression of Wnt5a and beta-catenin was observed in 27 (28%) and 49 (50%) of 98 prostate cancer cases, respectively, by immunohistochemical analyses. Simultaneous expression of Wnt5a and beta-catenin was observed in only five cases, suggesting their exclusive expression. The positive detection of Wnt5a was correlated with high Gleason scores and biochemical relapse of prostate cancer, but that of beta-catenin was not. Knockdown and overexpression of Wnt5a in human prostate cancer cell lines reduced and stimulated, respectively, their invasion activities, and the invasion activity required Frizzled2 and Ror2 as Wnt receptors. Wnt5a activated Jun-N-terminal kinase through protein kinase D (PKD) and the inhibition of PKD suppressed Wnt5a-dependent cell migration and invasion. In addition, Wnt5a induced the expression of metalloproteinase-1 through the recruitment of JunD to its promoter region. These results suggest that Wnt5a promotes the aggressiveness of prostate cancer and that its expression is involved in relapse after prostatectomy.

Regenerating islet-derived family, member 4 (REG4, which encodes Reg IV) is a candidate marker for cancer and inflammatory bowel disease. We investigated the potential prognostic role of Reg IV immunostaining in clinically localized prostate cancer (PCa) after radical prostatectomy. Immunohistochemical staining of Reg IV was performed in 98 clinically localized PCa tumors obtained during curative radical prostatectomy. Intestinal and neuroendocrine differentiation was investigated by MUC2 and chromogranin A immunostaining, respectively. The prognostic significance of immunohistochemical staining for these factors on prostate-specific antigen (PSA)-associated recurrence was assessed by Kaplan-Meier analysis and a Cox regression model. Phosphorylation of the epidermal growth factor receptor (EGFR) by Reg IV was analyzed by Western blot. In total, 14 (14%) of the 98 PCa cases were positive for Reg IV staining. Reg IV positivity was observed frequently in association with MUC2 (P = 0.0182) and chromogranin A positivity (P = 0.0012). Univariate analysis revealed that Reg IV staining (P = 0.0004), chromogranin A staining (P = 0.0494), Gleason score (P < 0.0001) and preoperative PSA concentration (P = 0.0167) were significant prognostic factors for relapse-free survival. Multivariate analysis indicated that Reg IV staining (P = 0.0312), Gleason score (P = 0.0014) and preoperative PSA concentration (P = 0.0357) were independent predictors of relapse-free survival. In the LNCaP cell line, EGFR phosphorylation was induced by the addition of Reg IV-conditioned medium. These results suggest that Reg IV expression is an independent prognostic indicator of relapse after radical prostatectomy.

Worldwide gastric carcinoma has marked geographical variations and worse outcome in patients from the West compared to the East. Although these differences has been explained by better diagnostic criteria, improved staging methods and more radical surgery, emerging evidence supports the concept that gene expression differences associated to ethnicity might contribute to this disparate outcome. Here, we collected datasets from 4 normal and 11 gastric carcinoma Serial Gene Expression Analysis (SAGE) libraries from two different ethnicities. All normal SAGE libraries as well as 7 tumor libraries were from the West and 4 tumor libraries were from the East. These datasets we compare by Correspondence Analysis and Support Tree analysis and specific differences in tags expression were identified by Significance Analysis for Microarray. Tags to gene assignments were performed by CGAP-SAGE Genie or TAGmapper. The analysis of global transcriptome shows a clear separation between normal and tumor libraries with 90 tags differentially expressed. A clear separation was also found between the West and the East tumor libraries with 54 tags differentially expressed. Tags to gene assignments identified 15 genes, 5 of them with significant higher expression in the West libraries in comparison to the East libraries. qRT-PCR in cell lines from west and east origin confirmed these differences. Interestingly, two of these genes have been associated to aggressiveness (COL1A1 and KLK10). In conclusion we found that in silico analysis of SAGE libraries from two different ethnicities reveal differences in gene expression profile. These expression differences might contribute to explain the disparate outcome between the West and the East.

Previous studies have indicated that lymphangiogenesis in solid tumors is associated with lymphatic metastasis. Overexpression of Vascular endothelial growth factor (VEGF)-C plays a major role in lymphangiogenesis in cancers. In the present study, DNA methylation and expression of the VEGF-C gene was investigated in gastric cancer (GC). Four GC cell lines (MKN-45, MKN-74, HSC-39 and HSC-43) showed no expression of VEGF-C, and the VEGF-C gene was found to be methylated in these cells. In contrast, 7 GC cell lines (MKN-1, MKN-7, MKN-28, TMK-1, KATO-III, SH101-P4 and HSC-44PE) expressed VEGF-C, and the VEGF-C gene was found to be unmethylated in these cell lines. In addition, expression of VEGF-C mRNA was retrieved by treatment with a demethylating agent, Aza-2'-deoxycytidine. In GC tissue samples, bisulfite DNA sequencing analysis revealed that VEGF-C was not methylated in 9 (29.0%) of 31 GC samples, whereas demethylation was not observed in corresponding non-neoplastic mucosa samples. Overexpression of VEGF-C mRNA was observed in 16 (51.6%) of 31 GC samples by quantitative reverse transcription-polymerase chain reaction. Of the 9 GC cases with VEGF-C demethylation, 8 (88.9%) overexpressed VEGF-C. In contrast, of the 22 GC cases without VEGF-C demethylation, 8 (36.4%) overexpressed VEGF-C (p = 0.0155). Furthermore, lymphatic vessel density determined by immunostaining of podoplanin in GC tissues was associated with overexpression of VEGF-C (p < 0.0001). These results suggest that demethylation and activation of the VEGF-C gene is likely involved in lymphangiogenesis in GC., ((c) 2007 Wiley-Liss, Inc.)

Gastric cancer (GC) is one of the most common malignancies worldwide. Genes expressed only in cancer tissue will be useful molecular markers for diagnosis and may also be good therapeutic targets. However, little is known about cancer-specific genes, at least in GC. In this study, we searched for GC-specific genes by serial analysis of gene expression (SAGE) data analysis and quantitative reverse transcription (RT)-PCR. Comparing GC SAGE libraries with those of various normal tissues in the SAGEmap database, we identified 54 candidate GC-specific genes. Quantitative RT-PCR analysis of these candidates revealed that APin protein (APIN), taxol resistance-associated gene 3 (TRAG3), cytochrome P450, family 2, subfamily W, polypeptide 1 (CYP2W1), melanoma inhibitory activity (MIA), matrix metalloproteinase-10 (MMP-10), dickkopf homolog 4 (DKK4), GW112, regenerating islet-derived family, member 4 (REGIV), and HORMA domain-containing 1 (HORMAD1) were expressed much more highly in GC than in 14 kinds of normal tissues. Immunohistochemical staining for MIA, MMP-10, and DKK4 was found in 47 (31.1%), 68 (45.0%), and two (1.3%) of 151 GCs, respectively, and staining for both MIA and MMP-10 was correlated with poor prognosis in advanced GC (P=0.0001 and 0.0141, respectively). Moreover, enzyme-linked immunosorbent assay showed high levels of MMP-10 (65/69, 94.2%) in serum samples from patients with GC. Levels of MIA were raised in a small proportion of serum samples from patients with GC (4/69, 5.8%). In Boyden chamber invasion assays, MIA-transfected GC cells were up to three times more invasive than cells transfected with empty vector. Taken together, these results suggest that MMP-10 is a good marker for the detection of GC and that MIA and MMP-10 are prognostic factors for GC. As expression of MIA and MMP-10 is narrowly restricted in cancer, these two molecules may be good therapeutic targets for GC.

Background: The authors purpose in this study was to clarify the difference in terms of clinicopathologic features between gastric cancer (GC) with high numbers of DNA methylated genes and CpG island methylator phenotype (CIMP)-positive GC as originally defined., Methods: We analyzed DNA methylation of 12 tumor-related genes (hMLH1, MGMT, p16(INK4a), CDH1, RAR-beta, HLTF, RIZ1, TM, FLNc, LOX, HRASLS, HAND1) in 75 samples of GC from 75 patients, 25 samples of corresponding nonneoplastic mucosa from 25 patients, and 10 samples of normal gastric mucosa from 10 healthy young individuals by methylation-specific polymerase chain reaction (PCR) and bisulfite PCR. We also investigated CIMP status by examining the methylation of five MINT loci and p53 mutation status by PCR single-strand conformation polymorphism. We measured levels of expression of mRNAs for these 12 genes by quantitative reverse transcription PCR in 50 GC specimens., Results: The average number of methylated genes per tumor was 4.83. DNA methylation of each gene was correlated with low expression of the respective mRNA. High methylation (GC with 5 or more methylated genes) was detected in 39 (52.0%) of 75 GCs. Twenty-nine (37.8%) of 75 GCs were CIMP-positive. DNA methylation of each of the 12 genes was observed more frequently in the high-methylation group than in the low-methylation group. Methylation of 6 specific genes occurred more frequently in CIMP-positive GC than in CIMP-negative GC. Methylation of the remaining 6 genes was not correlated with CIMP-status. High methylation was found more frequently in Stage III/IV GC (26 of 40 cases, 65.0%) than in Stage I/II GC (13 of 35 cases, 37.1%, P = 0.029).CONCLUSIONS.These findings indicate that GCs with higher numbers of methylated genes have more distinct DNA methylation profiles than the originally defined CIMP-positive GCs. DNA methylation of tumor-related genes accumulates in conjunction with tumor progression., ((c) 2006 American Cancer Society.)

Background: Hypermethylation of CpG islands has been associated with silencing of various tumor suppressor genes, and the retinoid acid receptor beta (RARbeta), cellular retinol-binding protein 1 (CRBP1), and tazarotene-induced gene 1 (TIG1) genes have been associated with retinoic acid signaling. To the authors' knowledge, little is known regarding the involvement of these three genes in gastric carcinoma (GC). In this study, the authors investigated the methylation status of these genes and analyzed the role of their DNA methylation in GC., Methods: DNA methylation of 3 retinoic acid-associated genes was analyzed in 42 samples of GC from 42 patients and in 8 GC cell lines by methylation-specific polymerase chain reaction (PCR) analysis. The mRNA expression levels for these three genes were measured by quantitative reverse transcription-PCR., Results: In 7 of 8 GC cell lines, the CRBP1 gene was hypermethylated, and CRBP1 transcription was inactive. In 6 of 8 GC cell lines, the TIG1 gene was hypermethylated, and TIG1 transcription was inactive. Treatment with demethylating agent 5-aza-2'-deoxycytidine restored both CRBP1 and TIG1 transcription. DNA methylation of the RARbeta, CRBP1, and TIG1 genes was detected in 15 of 42 GC samples (36%), 14 of 42 GC samples (33%), and 4 of 42 GC samples (10%), respectively, and in 6 of 30 samples (20%), 0 of 30 samples (0%), and 1 of 30 samples (3%) of corresponding nonneoplastic mucosa. None of the 10 normal gastric mucosa samples from young, healthy individuals demonstrated hypermethylation of any of these genes. DNA methylation of each gene was associated significantly with low mRNA expression of the respective gene. Twenty-four of 42 GC samples (57%) demonstrated hypermethylation of at least 1 of the 3 genes. However, no significant, concordant hypermethylation of these genes was observed., Conclusions: The results suggested that gastric carcinogenesis involves transcriptional inactivation by aberrant DNA methylation of genes related to retinoid signaling., (Copyright 2005 American Cancer Society)

Invasion and metastasis are critical determinants of cancer morbidity. Genes and molecules participating in these steps must be regarded as potential prognostic factors. Growth factors and their receptors, cell-cycle regulators, cell-adhesion molecules and matrix-degrading enzymes are those to be used as prognostic factors, including epidermal growth factor (EGF), EGF receptor, K-sam, HER-2, interleukin (IL)-8, vascular endothelial growth factor (VEGF), cyclin E, p27, E-cadherin, CD44v6, matrix metalloproteinase-1 (MMP-1), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1). Alterations in epigenetics, such as aberrant DNA methylation and histone modification that are, in part, associated with the tumor progression of gastric cancer, can be candidate prognostic factors. The number of methylated genes may serve as a marker of tumor progression. Genetic polymorphism not only affects cancer susceptibility but also influences malignant phenotype; examples include single-nucleotide polymorphism in the HER-2 and MMP-9 genes. Comprehensive gene expression analyses are useful to search for novel genes related to invasion and metastasis and potential prognostic factors. Serial analysis of gene expression (SAGE) has identified several these genes, such as CDH17, APOE, FUS, COL1A1, COL1A2, GW112, and MIA. Overexpression of MIA is found to be associated with poor prognosis. Microarray analysis has great potential for identifying the characteristics of individual cancers, from the view point of gene expression profiles. A combination of these examinations can not only foretell a patient's prognosis but can also give information directly connected with personalized cancer medicine and prevention.

Pot1, a telomere end-binding protein in fission yeast and human, is proposed not only to cap telomeres but also to recruit telomerase to the ends of chromosomes. No study has been performed regarding Pot1 expression status in human cancers. Thus, we examined POT1 mRNA expression in 51 gastric cancer (GC) tissues and evaluated telomere length and 3' telomeric overhang signals in 20 of the 51 GC tissues. Quantitative reverse transcription-PCR analysis showed that POT1 expression levels in the tumor relative to those in nonneoplastic mucosa (T/N ratio) were significantly higher in stage III/IV tumors than in stage I/II tumors (P = 0.005). Down-regulation of POT1 (T/n < 0.5) was observed more frequently in stage I/II GC (52.4%, 11 of 21) than in stage III/IV GC (23.3%, 7 of 30; P = 0.033), whereas up-regulation of POT1 (T/n > 2.0) was observed more frequently in stage III/IV GC (33.3%, 10 of 30) than in stage I/II GC (9.5%, 2 of 21; P = 0.048). POT1 expression levels showed decreased in accordance with telomere shortening (r = 0.713, P = 0.002). In-gel hybridization analysis showed that 3' telomeric overhang signals decreased in accordance with decreases in POT1 expression levels (r = 0.696, P = 0.002) and telomere shortening (r = 0.570, P = 0.013). Reduced POT1 expression was observed in GC cell lines with telomeres shortened by treatment with azidothymidine. In addition, inhibition of Pot1 by antisense oligonucleotides led to telomere shortening as well as inhibition of telomerase activity in GC cells. Moreover, inhibition of Pot1 decreased 3' overhang signals and increased the frequency of anaphase bridge (P = 0.0005). These data suggest that Pot1 may play an important role in regulation of telomere length and that inhibition of Pot1 may induce telomere dysfunction. Moreover, changes in POT1 expression levels may be associated with stomach carcinogenesis and GC progression.