Search

Summary Background and objective Pleiomorphic adenoma gene-like 1 ( PLAGL1 , also known as LOT1 and ZAC ) is a zinc-finger nuclear transcription factor, which possesses antiproliferative effects and is frequently epigenetically silenced during tumorigenesis. PLAGL1 gene is located on 6q24-25, a chromosomal region that is frequently deleted in various kinds of cancers. Both promoter hyper-methylation and loss of heterozygosity may lead to the down-regulation of PLAGL1 in human somatic cancers. Here we aimed to investigate the abnormalities of PLAGL1 in gastric cancers. Methods We collected 153 case-matched gastric adenocarcinoma (GAC) cases. Quantitative real-time PCR method was applied to evaluate the expression levels as well as gene copy numbers of PLAGL1 in the collected samples. Methylation-specific PCR (MSP) assay was performed to analyze the methylation status of PLAGL1 P1 promoter. Results Decreased expression of PLAGL1 mRNA was observed in GAC tissues, especially in advanced GACs. Copy number decrease of PLAGL1 gene in GACs was observed in 9.15% (19 out of 153) of the GAC samples and was closely correlated with gene expression. Methylation status of PLAGL1 promoter in GAC tissues was higher than in normal controls, which was inversely correlated with the expression levels of PLAGL1 mRNA. Conclusion DNA deletion and promoter hyper-methylation both contribute to the down-regulation of PLAGL1 in GACs.

Recent population studies suggest that the use of artemisinin is associated with reduced incidence and improved prognosis of certain cancers. In the current study, we assessed the effect of artemisinin on gastric cancer cells (AGS and MKN74 cells). We found that artemisinin inhibited growth and modulated expression of cell-cycle regulators in these cells. Treatment with artemisinin was also associated with induction of p27 kip1 and p21 kip1, two negative cell-cycle regulators. Furthermore, we revealed that artemisinin treatment led to an increased expression of p53. Taken together, these results provide evidence for a mechanism that may contribute to the antineoplastic effects of artemisinin suggested by recent population studies and justify further work to explore potential roles for it in gastric cancer prevention and treatment.

Genome-wide association studies have identified susceptibility loci for esophageal squamous cell carcinoma (ESCC). We conducted a meta-analysis of all single-nucleotide polymorphisms (SNPs) that showed nominally significant P-values in two previously published genome-wide scans that included a total of 2961 ESCC cases and 3400 controls. The meta-analysis revealed five SNPs at 2q33 with P5 × 10(-8), and the strongest signal was rs13016963, with a combined odds ratio (95% confidence interval) of 1.29 (1.19-1.40) and P= 7.63 × 10(-10). An imputation analysis of 4304 SNPs at 2q33 suggested a single association signal, and the strongest imputed SNP associations were similar to those from the genotyped SNPs. We conducted an ancestral recombination graph analysis with 53 SNPs to identify one or more haplotypes that harbor the variants directly responsible for the detected association signal. This showed that the five SNPs exist in a single haplotype along with 45 imputed SNPs in strong linkage disequilibrium, and the strongest candidate was rs10201587, one of the genotyped SNPs. Our meta-analysis found genome-wide significant SNPs at 2q33 that map to the CASP8/ALS2CR12/TRAK2 gene region. Variants in CASP8 have been extensively studied across a spectrum of cancers with mixed results. The locus we identified appears to be distinct from the widely studied rs3834129 and rs1045485 SNPs in CASP8. Future studies of esophageal and other cancers should focus on comprehensive sequencing of this 2q33 locus and functional analysis of rs13016963 and rs10201587 and other strongly correlated variants.

Li Dong Wang and colleagues report a genome wide association study for esophageal squamous cell carcinoma in the Chinese population. They identify two risk loci at PLCE1 and C20orf54.

Heterozygosity for the Pax6 allele is associated with impaired glucose tolerance in humans. With a Pax6 mutant mouse model, we found many of the metabolic abnormalities were consistent with the effects of down-regulating the expression of glucagon-like peptide 1 (GLP-1). In addition to impaired glucose tolerance, adult heterozygous mutant mice (Pax6m/+) secreted less insulin responding to glucose and arginine administration compared with control mice. Moreover, Pax6m/+ mice showed increased food intake compared with control mice, although they were resistant to diet-induced fat accumulation. Indeed, levels of circulating GLP-1 and intestinal transcription of Gcg/Proglucagon were dramatically reduced in Pax6m/+ mice. Mutated Pax6 also failed to activate the Gcg/Proglucagon promoter by in vitro transfection assay. Finally, administering the GLP-1 receptor agonist exendin-4 to Pax6m/+ mice largely reversed their abnormal food intake, glycemic excursion, and insulin secretion. Our studies suggested that disruption of metabolic homeostasis mainly caused by Pax6 haploinsufficiency was mainly mediated by down-regulation of GLP-1. Administration of exendin-4 may be a useful therapy in humans with a similar mutation.

Whelming evidence has demonstrated that WW domain containing E3 ubiquitin protein ligase 1 (WWP1) participates in a wide variety of biological processes and is tightly related to the initiation and progression of many tumors. Currently, although mounting evidence supports a role of WWP1 in tumor promotion and tumorigenesis, the potential roles of WWP1 and its biological functions in gastric carcinoma are not fully understood. Here, we found that WWP1 messenger RNA (mRNA) and protein were highly expressed in gastric carcinoma tissues and cells. High WWP1 mRNA and protein levels were tightly related to differentiation status, TNM stage, invasive depth, lymph node metastasis, and poor prognosis in gastric carcinoma. Furthermore, WWP1 siRNA significantly decreased WWP1 protein level in MKN-45 and AGS cells; meanwhile, WWP1 depletion markedly inhibited tumor proliferation in vitro and in vivo, arrested cell cycle at G0/G1 phase, and induced cell apoptosis in MKN-45 and AGS cells. Most notably, WWP1 downregulation both inactivated PTEN-Akt signaling pathway in MKN-45 and AGS cells. Taken altogether, our findings suggest that WWP1 acts as an oncogenic factor and should be considered as a novel interfering molecular target for gastric carcinoma.

We investigated the role of endoplasmic reticulum (ER) stress response and p38 MAPK pathways in the resistance of gastric cancer cells to chemotherapy. Pretreatment of the gastric cancer cells with the ER stress inducer drastically decreased the apoptotic rate induced by cisplatin or doxorubicin. Induction of ER stress also led to the activation of p38. Inhibition of p38 activity abrogated the effects of ER stress-induced resistance to apoptosis induced by cisplatin- and doxorubicin treatment. Thus, ER-stress response in gastric cancer cells causes resistance to cisplatin- and doxorubicin-induced apoptosis, and ER-stress induced chemo-resistance can be overcome by blocking p38 activity.

We performed a genome-wide association study of esophageal squamous cell carcinoma (ESCC) by genotyping 1,077 individuals with ESCC and 1,733 control subjects of Chinese Han descent. We selected 18 promising SNPs for replication in an additional 7,673 cases of ESCC and 11,013 control subjects of Chinese Han descent and 303 cases of ESCC and 537 control subjects of Chinese Uygur-Kazakh descent. We identified two previously unknown susceptibility loci for ESCC: PLCE1 at 10q23 (P(Han combined for ESCC) = 7.46 x 10(-56), odds ratio (OR) = 1.43; P(Uygur-Kazakh for ESCC) = 5.70 x 10(-4), OR = 1.53) and C20orf54 at 20p13 (P(Han combined for ESCC) = 1.21 x 10(-11), OR = 0.86; P(Uygur-Kazakh for ESCC) = 7.88 x 10(-3), OR = 0.66). We also confirmed association in 2,766 cases of gastric cardia adenocarcinoma cases and the same 11,013 control subjects (PLCE1, P(Han for GCA) = 1.74 x 10(-39), OR = 1.55 and C20orf54, P(Han for GCA) = 3.02 x 10(-3), OR = 0.91). PLCE1 and C20orf54 have important biological implications for both ESCC and GCA. PLCE1 might regulate cell growth, differentiation, apoptosis and angiogenesis. C20orf54 is responsible for transporting riboflavin, and deficiency of riboflavin has been documented as a risk factor for ESCC and GCA.

The B7-H1/PD-1 co-signaling pathway has recently been found to play a pivotal role in the immune evasion of tumor cells from host immune system. The aim of this study was to examine the B7-H1 and PD-1 expression and TILs status in gastric cancer and to elucidate the clinical relevance of B7-H1 and PD-1 to the pathogenesis of gastric carcinoma.Immunohistochemistry and ANAE histochemical staining were used to investigate the in situ expression of B7-H1 and PD-1 and TILs status in the gastric tissues. RT-PCR was used to explore B7-H1 and PD-1 expression at the transcriptional level. The B7-H1 expression at protein level was detected by Western blot.Expression of B7-H1 and PD-1 was found to be increased in gastric carcinoma, but absent in normal gastric tissue. B7-H1 expression in gastric carcinoma was inversely correlated with TILs infiltration. B7-H1 but not PD-1 expression in tumor tissue was significantly correlated with some clinicopathhological variables including depth of invasion, lymph node metastasis and distant metastasis.B7-H1 and PD-1 expressions are increased in gastric carcinoma. This signaling pathway may inhibit antitumor immune responses in gastric carcinoma. B7-H1 expression plays a critical role in the pathogenesis of human gastric carcinoma,and might be a promising prognostic marker and therapeutic target in the treatment of this disease.

To investigate the mRNA and protein expression of nucleostemin (NS) in human esophageal squamous cell carcinoma.The mRNA and protein expression of NS were detected in 31 mucosal atypical hyperplasia specimens, 62 esophageal squamous cell carcinoma specimens and the matched normal esophageal mucosa samples by RT-PCR and immunohistochemistry method, respectively.The positive expression rate of NS protein in normal esophageal mucosa, atypical hyperplasia and esophageal squamous cell carcinoma was 17.7% (11/62), 41.9% (13/31) and 69.4% (43/62), respectively. There was a significant difference among the above three groups (chi2 = 33.676, P0.01). The expression levels of NS mRNA in esophageal squamous cell carcinoma (0.971 +/- 0.121) was significantly higher than that in the atypical hyperplasia (0.913 +/- 0.085) and also in the normal esophageal mucosa (0.866 +/- 0.103; F = 14.829, P0.01). The expression level of both NS protein and mRNA was positively correlated with histological grade, infiltration depth, and lymph node metastasis (P0.05), but not with age, gender or pathological type (P0.05).Our results indicate that nucleostemin mRNA and protein are over-expressed in human esophageal squamous cell carcinoma, and it may be related with its oncogenesis.

To investigate the mRNA expression levels of nucleostemin (NS) in human esophageal squamous cell carcinoma tissue.Real-time PCR was used to quantify the mRNA expression of NS in the samples of esophageal squamous cell carcinoma tissue and their matched normal esophageal mucosa tissue from 62 patients, 36 males and 26 females, aged (61 +/- 10) (38-75). The relationship between NS mRNA expression level and clinical pathological features was analyzed.The NS mRNA expression level of the 62 cases of esophageal squamous cell carcinoma tissue was(4.5 +/- 2.1), significantly higher than that of the matched normal esophageal mucosa tissue [(2.1 +/- 1.3), t = -5.045, P = 0.000]. The mRNA expression level of NS was associated with tumor grade, depth of infiltration, and lymph node metastasis (all P0.05), but not with gender, age, and pathological type (all P0.05). Multiple linear regression analysis revealed that clinical and pathological features influenced the NS mRNA expression level (P = 0. 000), and the depth of infiltration and lymph node metastasis were important influencing factors for NS mRNA expression level(both P0.05).NS may play an important role in the progression and proliferation of esophageal squamous cell carcinoma.

To determine the expression of nucleostemin (NS), epidermal growth factor (EGF) and epidermal growth factor receptor (EGFR) mRNA in human esophageal squamous cell carcinoma (ESCC) tissues and their association in a human ESCC cell line. The expression of NS, EGF and EGFR mRNA was determined in paired normal esophageal and ESCC tissues of 62 patients using in situ hybridization. The association between NS and EGF or EGFR was examined using immunoblotting and real time polymerase chain reaction in a human ESCC cell line transfected with NS siRNA or treated with a selective EGFR inhibitor. In normal esophageal and ESCC tissues, the positive detection rates were 21.0% (13/62) and 69.4% (43/62) for NS mRNA staining, 40.3% (25/62) and 77.4% (48/62) for EGF mRNA staining, and 30.6% (19/62) and 75.8% (41/62) for EGFR mRNA staining, respectively. These results indicated that NS, EGF and EGFR mRNA expression was upregulated mostly in ESCC tissues. Moreover, the expression of NS, EGF and EGFR mRNA was positively correlated with tumor grade, invasion and lymphatic metastasis of ESCC cells. NS mRNA was co-expressed with EGF and EGFR mRNA in ESCC tissues. The in vitro studies using a human ESCC cell line showed that knockdown of NS with NS siRNA significantly reduced EGF and EGFR expression. However, inhibition of the EGFR kinase activity with a specific EGFR kinase inhibitor had minimal effect on NS expression. The upregulation of NS, EGF and EGFR mRNA frequently occurs in ESCC tissues and is associated with malignancy of human esophageal squamous tumors. NS is required for EGF and EGFR expression.

To construct a eukaryotic expression vector for the small interfering RNA (siRNA) targeting nucleostemin (NS) gene.The siRNA targeting NS gene was designed according to the sequence of NS mRNA available in GenBank. Three siRNA sequences were obtained, and the corresponding cDNAs were synthesized and inserted into plasmid pRNAT-U6.1 for constructing the recombinant plasmids, which were transformed into E.coli DH5alpha strain. The plasmids, after identification by PCR and DNA sequencing, were transfected into EC9706 cell line via liposome, and the mRNA and protein expressions of NS gene in the cells were determined by RT-PCR and Western blotting, respectively.Three recombinant plasmids were identified by PCR and sequence analysis, the results of which showed correct insertion of the designed sequences in the plasmids. RT-PCR and Western blotting showed substantially decreased mRNA and protein expressions of NS gene in the transfected cells.The recombinant plasmid expressing the siRNA targeting NS gene has been successfully constructed, which provides the basis for studying RNA interference of the NS gene.

To investigate the effect of hTERT antisense oligodeoxynucleotide (ASODN) on the oncogenicity and the inductive apoptosis of HL-60 cells.Apoptosis of HL-60 cells was detected by flow cytometry (FCM) and agarose gel electrophoresis. Both treated and untreated HL-60 cells were collected and transplanted into 5 BALB/c nude mice respectively, the formation of transplanted neoplasm and its morphologic change were observed. After the transplanted neoplasms were uniform with the ameliorated method in another 10 BALB/c nude mice, they were divided into 2 groups and injected ASODN and PBS into the neoplasm respectively. Seven days later, the tumor were measured, its morphology were observed, and the apoptotic cells were detected with a TUNEL kit.After 72 h treatment there were DNA ladders and early apoptosis peak in hTERT ASODN treated HL-60 cells but was none in SODN treated and blank control cells. In tumor formation experiment, neoplasms were formed in ASODN treated group at 16-17 d and untreated group at 12-13 d. Neoplasm was formed in 2 of 5 ASODN treated mice and 4 of 5 untreated mice respectively. In untreated mice tumor tissues were rich in blood vasa and stromal tissue compared with that in ASODN treated mice. In tumor therapy experiment, before treatment, there was no difference in the average neoplasm physical volume between ASODN treated group [(100.9 +/- 24.6) mm3] and PBS treated group [(98.4 +/- 23.1) mm3] (P0.05). After treatment, the neoplasm volume in ASODN treated group [(422.7 +/- 326.4) mm3] was smaller than that in PBS treated group [(786.4 +/- 357.6) mm3] (P0.05). Histologically, there were many apoptosis cells in ASODN treated group, but was seldom seen in PBS treated group. The TUNEL positive cells in ASODN treated group were much more than that in PBS treated group (P0.05).The hTERT ASODN induces apoptosis of HL-60 cells in vitro, reduces the tumor formation in BALB/c nude mice and inhibits the growth of the transplanted neoplasm.

This study was purposed to investigate the inhibition of hTERT antisense oligodeoxynucleotide (ASODN) on the proliferation and telomerase activity in HL-60 cells and to explore the relativity between the telomerase activity and the expression of hTERT gene in HL-60 cells. After treated by hTERT ASODN the expression of hTERT was detected by RT-PCR, the morphological changes of HL-60 cells was observed with inverted microscopy, the cell proliferation was measured by MTT method, and the telomerase activity was determined with TRAP-ELISA and TRAP-PAGE. The results showed that after sealing hTERT gene with ASODN for 72 hours, the expression of hTERT gene was significantly inhibited, the cell growth was repressed and the ability of proliferation decreased, and the effect was specific in sequence and dependent in dose and time. OD(450-690) values were 2.648 +/- 0.42, 1.504 +/- 0.47, 1.223 +/- 0.39, 0.944 +/- 0.16 respectively, as the cells were treated with 0, 10, 20, 30 micromol/L ASODN for 72 hours. The difference was significant as compared 10, 20, 30 micromol/L groups with 0 micromol/L ASODN group respectively (P0.05), but the difference was no significant when compared 20 micromol/L SODN group (2.376 +/- 0.65) with untreated group (2.648 +/- 0.42) (P0.05). TRAP-PAGE detection revealed that comparing ASODN groups with SODN groups the telomerase image bands were decreased and least was found in groups of 30 +/- mol/L. It is concluded that the hTERT ASODN may inhibit the proliferation and down-regulate the telomerase activity in HL-60 cells by sealing the expression of hTERT gene.

To screen effective sequences of small interfering RNA targeting MDR1 gene in human gastric cancer SGC7901/VCR cells.Four siRNAs (MDR1si326, MDR1si1513, MDR1si2631 and MDR1si3071) targeting MDR1 gene were designed and synthesized by in vitro transcription. The siRNA duplexes were used to transfect into the human gastric cancer SGC7901/VCR cells. The expression level of MDR1 mRNA and P-gp were detected by RT-PCR and Western blotting, respectively. The accumulation of intracellular adriamycin (ADR) was examined by flow cytometry and the cell sensitivity to ADR was demonstrated by MTT.The SGC7901/VCR cells treated with 4 siRNAs led to reversal effect on multidrug resistance to different extents. Among the SGC7901/VCR cells treated by siRNAs for 48 h, the expression level of MDR1 mRNA in cells of MDR1si326 or MDR1si2631 group (0.42 +/- 0.07 or 0.49 +/- 0.02) was more decreased than that in cells of MDR1si1513 or MDR1si3071 group (P0.05). The accumulation of ADR in cells of MDR1si326 group was the most; in cells of MDR1si2631 group, more; in cells of MDR1si3071 group, lower and in cells of MDR1si1513 group, the lowest (P0.05). The relative reversal efficiency of cells of MDR1si2631 group to ADR was the highest and in cells of MDR1si326 group, higher (P0.05). There was no significant difference in the relative reversal efficiency between the cells of MDR1si1513 and MDR1si3071 groups (P0.05). The expression level of P-gp in cells of MDR1si326 group was the lowest among the SGC7901/VCR cells treated by siRNAs for 72 h.The MDR1si326 with most, MDR1si2631 with more, MDR1si3071 with less and MDR1si1513 with least reversal effects on MDR1 gene mediated multidrug resistance were found in the human gastric cancer SGC7901/VCR cells.

To detect methylation in promoter region of hMSH2 gene in esophageal cancer.Specimens of cancer and normal tissues freshly removed from 32 cases of esophageal cancer patients without previous radiotherapy, chemotherapy or other treatment were preserved at -80 degrees C within 30 min. Methylation specific PCR (MSP) was used to detect methylation of mismatch repair gene (MMR) hMSH2 in promoter region in esophageal cancer and normal esophageal tissues.The frequencies of methylation of hMSH2 gene in promoter region of cancer and normal esophageal tissues were 32.4% (11/32) and 0/30 (0%), respectively, and significant difference was found between the two groups (P0.01). The frequency of methylation in elder patients (or = 70 years old) was significantly higher than that in younger patients (70 years old) (P0.05). Methylation was less frequently found in grade I-II (18.2%) than in grade III-IV (70.0%) (P0.05).Methylation of hMSH2 gene in promoter region is related to patients' age and histopathological grade of the esophageal cancer.

To investigate the effects of c-myc antisense oligodeoxynucleotide (ASODN) on the telomerase activity and the induction of apoptosis in HL-60 cells, and to explore the relationship between the telomerase activity and the expression of c-myc gene in HL-60 cells, after treatment by c-myc ASODN, the expression of c-myc was detected by RT-PCR, the apoptosis, cell cycle were detected with agarose gel electrophoresis and flow cytomety, and the telomerase activity was determined with TRAP-ELISA. The results showed that after blocking c-myc gene with ASODN for 72 hours, it is obvious that the expression of c-myc gene was inhibited. The percentage of S phase HL-60 cells decreased from 55.6% to 30%, the early apoptosis peak appeared (the percentage of apoptosis cells were 25.2%) and the DNA ladders were shown. OD(450 - 690) were 2.648 +/- 0.42, 2.324 +/- 0.36, 2.162 +/- 0.38, 1.952 +/- 0.14, 1.805 +/- 0.40, 1.616 +/- 0.41 and 2.466 +/- 0.29, respectively, as the cells were treated with 0, 1, 2, 3, 4, 5 micromol/L ASODN and 5 micromol/L SODN for 72 hours. The difference was significant when compared 3, 4, 5 micromol/L groups with 0 micromol/L ASODN group respectively (P0.05), but the difference was no significant when compared 1, 2 micromol/L ASODN and 5 micromol/L SODN groups with 0 micromol/L ASODN group (P0.05). It is concluded that the c-myc gene ASODN may induce the apoptosis of cells, inhibit cells from G(1) phase into S phase and regulate the telomerase activity down in HL-60 cells by blocking the expression of c-myc gene.

To observe the expression of DNA mismatch repair gene hMSH2 mRNA in esophageal cancer tissues.This study included 32 esophageal cancer patients who received no previous radiotherapy, chemotherapy or other treatments. Within 30 min following surgical removal of the tumor tissues, specimens of the tumor, the tissue adjacent to the tumor and normal tissue at the esophageal stump (1 cmx1 cmx1 cm in size for each specimen) were obtained for examining hMSH2 expression with hMSH2 ISH detection kit.The positivity rate of hMSH2 was 46.88% in the esophageal cancer tissues, 53.12% in the adjacent tissues, and 84.38% in normal tissues at the esophageal stump, showing significant difference of the former two tissues from the normal tissue (P0.05). No significant correlation was noted between the positivity rate of hMSH2 and such factors as the patients' age, sex, tumor size, tumor location, pathological type, histological grade, lymphatic metastasis or degree of tumor invasion (P0.05).The deletion of hMSH2 is an early event in the development of esophageal cancer.

To study the alteration of nuclear matrix proteins (NMPs) in gastric cancer.The NMPs extracted from 22 cases of gastric cancer and normal gastric tissues were investigated by SDS-PAGE technique and the data were analyzed using Genetools analysis software.Compared with normal gastric tissue, the expression of 30 ku and 28 ku NMPs in gastric cancer decreased significantly (P=0.002, P=0.001, P0.05). No significant difference was found in the expression of the two NMPs between the various differentiated grades (P=0.947, P=0.356) and clinical stages of gastric cancer (P=0.920, P=0.243, P0.05).The results suggested that the alteration of NMPs in gastric cancer occurred at the early stage of gastric cancer development.

AIM: To detect the loss of heterozygosity (LOH) frequency of microsatellite sites D9s171, D9s1604 of p16 gene and expression of hMSH2 mRNA in various differentiated types of gastric cancer, adjacent cancer tissues and normal gastric mucosa. METHODS: LOH was detected by polymerase chain reaction (PCR)-denaturing polyacrylamide gel electrophoresis-silver staining. The expression of hMSH2 mRNA was examined with in situ hybridization. RESULTS: The frequency rate of LOH was significantly higher in gastric cancers than that in adjacent cancer tissues (P = 0.032). No significant difference was noted among various differentiated types and various clinical stages of gastric cancers. The significantly reduced expression of hMSH2 mRNA positive signal cells exhibited in gastric cancers, in comparison with that in the adjacent cancer tissues and normal gastric mucosa, respectively (P = 0.001). No significant difference was noted among various clinical stages of gastric cancers (P > 0.05). The difference of positive signal cells in poorly differentiated cancers and those in well and moderately differentiated cancers were significant (P < 0.001). CONCLUSION: The frequencies of LOH in two microsatellite sites, D9s171 and D9s1604, in p16 genome were associated with development of gastric cancer and no significant correlation was demonstrated between the LOH frequency and the cell differentiated types of tumor cells or clinical stages. There was a positive relationship between the expression of hMSH2 mRNA and the differentiated types of gastric cancer.

Nat. Genet. 42, 759–763 (2010); published online 22 August 2010; corrected after print 27 August 2014 In contrast to the version of this article initially published, the authors now find no evidence to support association with esophageal squamous cell carcinoma susceptibility for rs13042395[T] at 20p13 in their original data, in two independent sets of cases and controls collected in other Chinese populations or in the joint analysis of these three studies.

AIM: To investigate the copy number variation of NACO3 gene in colorectal cancer (CRC) and its correlation with tumor progression. METHODS: A total of 142 samples of case-matched CRC tissues and adjacent normal tissues were obtained from patients undergoing bowel resection. Quantitative real-time polymerase chain reaction method was used to investigate the copy number variations of NCOA3 as well as gene expression in the collected tissues. RESULTS: Copy number gains of NCOA3 were detected in 39 CRC samples (27.5%) and were correlated with tumor progression (χ2 = 6.42, P = 0.0112). Moreover, there was a positive correlation between copy number gain and mRNA over-expression of NCOA3 in CRCs (P = 0.0023). Expression level of NCOA3 mRNA was also enhanced in the CRC samples with unaltered copy numbers (3.85 ± 1.23 vs 2.71 ± 0.64, P < 0.01). CONCLUSION: Sporadic colorectal cancers exhibit different mechanisms of NCOA3 regulation.

AIM: To study methylation, frequencies of homozygous deletion and mutation of p16 gene in gastric carcinoma. METHODS: The methylation pattern in exon 1 and exon 2 of p16 gene was studied with polymerase chain reaction (PCR), using methylation sensitive restriction endonuclease HpaII and methylation insensitive restriction endonuclease MspI. PCR technique was used to detect homozygous deletions of exon 1 and exon 2 of p16 gene and single strand conformation polymorphism (SSCP) technique was used to detect the mutation of the gene. RESULTS: Hypermethylation changes in exon 1 and exon 2 of p16 gene were observed in 25% and 45% of 20 gastric cancer tissues, respectively, while no methylation abnormality was found in normal tissues. The homozygous deletion frequency of exon 1 and exon 2 of p16 gene in 20 gastric cancer tissues was 20% and 10%, respectively. No mutation was found in exon 1 of p16 gene, while abnormal single strands were found in 2 (10%) cases in exon 2 as detected by SSCP. CONCLUSION: The results suggest that hypermethylation and abnormality of p16 gene may play a key role in the progress of gastric cancer. Hypermethylation of exon 2 of p16 gene may have effects on the carcinogenesis of gastric mucosa and may be a later event.

AIM: To investigate the expression of somatostatin mRNA in various differentiated types of gastric carcinoma. METHODS: By using in situ hybridization and immunohistochemical techniques, the expression of somatostatin mRNA and somatostatin immunoreactivity in the normal gastric mucosa, the poorly, moderately and well-differentiated gastric carcinomas, and various clinical stages of carcinoma were observed. RESULTS: In comparison with the normal gastric mucosa, the significantly increased expression of somatostatin mRNA positive cells was displayed in gastric carcinoma ( t = 2.681, P < 0.01). The positive signal cells were distributed in a scattered form or aggregated as a mass or a cord, and the positive cells were more significantly enhanced in poorly differentiated carcinomas than those in well and moderately differentiated carcinomas (t = 2.962, P < 0.01). The somatostatin mRNA hybridization signals in stages III and IV of gastric carcinoma were significantly higher than those in stages I and II. The results of somatostatin immunoreactivity were consistent with those of in situhybridization. CONCLUSION: The alteration of the expression of somatostatin mRNA was associated with the deve-lopment of gastric carcinoma and may play an important role in the process of tumor differentiation.