AIM： TO determine p15 promoter hypermethylation in gastric tumoral tissue and serum samples, its impact on p16-protein expression, and correlation with clinical and histological features. METHODS： Samples were obtai...AIM： TO determine p15 promoter hypermethylation in gastric tumoral tissue and serum samples, its impact on p16-protein expression, and correlation with clinical and histological features. METHODS： Samples were obtained from 52 histologically confirmed cases of gastric adenocarcinoma. Gastric tissue and serum of 50 age- and sex-matched individuals with normal gastroscopy and biopsy were obtained as control samples. Methylation-specific polymerase chain reaction （MSP） was used to evaluate methylation status of p16 promoter, p16-protein expression was analyzed by immunohistochemical staining on paraffin-embedded sections. RESULTS： Methylation was detected in 44.2% （23/52） of tumoral tissues. 60.9% of them were also methylated in serum, i.e., 26.9% of all patients （14/52）. Methylation was not detected in tissue and sera of control samples. p16-protein expression was decreased in 61.5% of cases （32/52）, and was significantly associated with promoter hypermethylation （P 〈 0.001）. Methylation was significantly more frequent in higher pathological grades （P 〈 0.05）. Methylation was not associated with other clinicopathological features and environmental factors including Hpylori infection and smoking. CONCLUSION： p16 promoter hypermethylation is an important event in gastric carcinogenesis. It is the principle mechanism of p16 gene silencing. It is related to malignant tumor behavior. Detection of DNA methylation in serum may be a biomarker for early detection of gastric cancer.展开更多
AIM： To identify the relationship between DNA hyper- methylation and histone modification at a hyperme- thylated, silenced tumor suppressor gene promoter in human gastric cancer cell lines and to elucidate whether al...AIM： To identify the relationship between DNA hyper- methylation and histone modification at a hyperme- thylated, silenced tumor suppressor gene promoter in human gastric cancer cell lines and to elucidate whether alteration of DNA methylation could affect histone modification. METHODS： We used chromatin immunoprecipitation （CHIP） assay to assess the status of histone acetylation and methylation in promoter regions of the p16 and rnutL homolog 1 （MLH1） genes in 2 gastric cancer cell lines, SGC-7901 and MGC-803. We used methylation- specific PCR （MSP） to evaluate the effect of 5-Aza-2＇- deoxycytidine （5-Aza-dC）, trichostatin A （TSA） or their combination treatment on DNA methylation status. We used RT-PCR to determine whether alterations of histone modification status after 5-Aza-dC and TSA treatment are reflected in gene expression. RESULTS： For thep16 and MLH1 genes in two cell lines, silenced loci associated with DNA hypermethylation were characterized by histone H3-K9 hypoacetylation and hypermethylation and histone H3-K4 hypomethylation. Treatment with TSA resulted in moderately increased histone H3-K9 acetylation at the silenced loci with no effect on histone H3-K9 methylation and minimal effects on gene expression. In contrast, treatment with 5-Aza- dC rapidly reduced histone H3-K9 methylation at the silenced loci and resulted in reactivation of the two genes. Combined treatment with 5-Aza-dC and TSA was synergistic in reactivating gene expression at the loci showing DNA hypermethylation. Similarly, histone H3-K4 methylation was not affected alter TSA treatment, andincreased moderately at the silenced loci after 5-Aza-dC treatment. CONCLUSION： Hypermethylation of DNA in promoter CpG islands is related to transcriptional silencing of tumor suppressor genes. Histone H3-K9 methylation in different regions of the promoters studied correlates with DNA methylation status of each gene in gastric cancer cells. However, histone H3-K9 acetylation and H3-K4 methylation inversely correlate 展开更多
AIM: To determine the effect of cis -9, trans -11-conjugated linoleic acid (c9, t11-CLA) on the cell cycle of gastric cancer cells (SGC-7901) and its possible mechanism in inhibition cancer growth. METHODS: Using cell...AIM: To determine the effect of cis -9, trans -11-conjugated linoleic acid (c9, t11-CLA) on the cell cycle of gastric cancer cells (SGC-7901) and its possible mechanism in inhibition cancer growth. METHODS: Using cell culture and immunocytochemical techniques, we examined the cell growth, DNA synthesis, expression of PCNA, cyclin A, B(1), D(1), p16(ink4a) and p21(cip/waf1) of SGC-7901 cells which were treated with various c9, t11-CLA concentrations (25, 50, 100 and 200 micromol.L(-1))of c 9, t 11-CLA for 24 and 48h, with a negative control (0.1% ethane). RESULTS: The cell growth and DNA synthesis of SGC-7901 cells were inhibited by c9, t11-CLA.SGC-7901 cells. Eight day after treatment with various concentrations of c9, t11-CLA mentioned above, the inhibition rates were 5.92%, 20.15%, 75.61% and 82.44%, respectively and inhibitory effect of c9, t11-CLA on DNA synthesis (except for 25 micromol.L, 24h) showed significantly less (3)H-TdR incorporation than that in the negative controls (P【0.05 and P【0.01). Immunocytochemical staining demonstrated that SGC-7901 cells preincubated in media supplemented with different c9, t11-CLA concentrations at various times significantly decreased the expressions of PCNA (the expression rates were 7.2-3.0%, 24h and 9.1-0.9% at 48h, respectively), Cyclin A (11.0-2.3%, 24h and 8.5-0.5%,48h), B(1) (4.8-1.8% at 24h and 5.5-0.6% at 48h)and D(1) (3.6-1.4% at 24h and 3.7%-0 at 48h) as compared with those in the negative controls(the expressions of PCNA, Cyclin A, B(1) and D(1) were 6.5% at 24h and 9.0% at 48h, 4.2% at 24h and 5.1% at 48h, 9.5% at 24h and 6.0% at 48h,respectively)(P【0.01), whereas the expressions of P16(ink4a) and P21(cip/waf1), cyclin-dependent kinases inhibitors(CDKI), were increased. CONCLUSION: The cell growth and proliferation of SGC-7901 cell is inhibited by c9, t11-CLA via blocking the cell cycle, with reduced expressions of cyclin A,B(1) and D(1) and enhanced expressions of CDKI(P16(ink4a) and p21(cip/waf1)).展开更多
Pancreatic cancer is the fourth most common cause of cancer-related deaths in the United States, with over 38000 deaths in 2013. The opportunity to detect pancreatic cancer while it is still curable is dependent on ou...Pancreatic cancer is the fourth most common cause of cancer-related deaths in the United States, with over 38000 deaths in 2013. The opportunity to detect pancreatic cancer while it is still curable is dependent on our ability to identify and screen high-risk populations before their symptoms arise. Risk factors for developing pancreatic cancer include multiple genetic syndromes as well as modifiable risk factors. Genetic conditions include hereditary breast and ovarian cancer syndrome, Lynch Syndrome, familial adenomatous polyposis, Peutz-Jeghers Syndrome, familial atypical multiple mole melanoma syndrome, hereditary pancreatitis, cystic fibrosis, and ataxia-telangiectasia; having a genetic predisposition can raise the risk of developing pancreatic cancer up to 132-fold over the general population. Modifiable risk factors, which include tobacco exposure, alcohol use, chronic pancreatitis, diet, obesity, diabetes mellitus, as well as certain abdominal surgeries and infections, have also been shown to increase the risk of pancreatic cancer development. Several largevolume centers have initiated such screening protocols, and consensus-based guidelines for screening high-riskgroups have recently been published. The focus of this review will be both the genetic and modifiable risk factors implicated in pancreatic cancer, as well as a review of screening strategies and their diagnostic yields.展开更多
基金A grant offered by Mashhad University of Medical Sciences, No. 84129
文摘AIM： TO determine p15 promoter hypermethylation in gastric tumoral tissue and serum samples, its impact on p16-protein expression, and correlation with clinical and histological features. METHODS： Samples were obtained from 52 histologically confirmed cases of gastric adenocarcinoma. Gastric tissue and serum of 50 age- and sex-matched individuals with normal gastroscopy and biopsy were obtained as control samples. Methylation-specific polymerase chain reaction （MSP） was used to evaluate methylation status of p16 promoter, p16-protein expression was analyzed by immunohistochemical staining on paraffin-embedded sections. RESULTS： Methylation was detected in 44.2% （23/52） of tumoral tissues. 60.9% of them were also methylated in serum, i.e., 26.9% of all patients （14/52）. Methylation was not detected in tissue and sera of control samples. p16-protein expression was decreased in 61.5% of cases （32/52）, and was significantly associated with promoter hypermethylation （P 〈 0.001）. Methylation was significantly more frequent in higher pathological grades （P 〈 0.05）. Methylation was not associated with other clinicopathological features and environmental factors including Hpylori infection and smoking. CONCLUSION： p16 promoter hypermethylation is an important event in gastric carcinogenesis. It is the principle mechanism of p16 gene silencing. It is related to malignant tumor behavior. Detection of DNA methylation in serum may be a biomarker for early detection of gastric cancer.
基金National Natural Science Foundation of China,No.30271477,No.30572162
文摘AIM： To identify the relationship between DNA hyper- methylation and histone modification at a hyperme- thylated, silenced tumor suppressor gene promoter in human gastric cancer cell lines and to elucidate whether alteration of DNA methylation could affect histone modification. METHODS： We used chromatin immunoprecipitation （CHIP） assay to assess the status of histone acetylation and methylation in promoter regions of the p16 and rnutL homolog 1 （MLH1） genes in 2 gastric cancer cell lines, SGC-7901 and MGC-803. We used methylation- specific PCR （MSP） to evaluate the effect of 5-Aza-2＇- deoxycytidine （5-Aza-dC）, trichostatin A （TSA） or their combination treatment on DNA methylation status. We used RT-PCR to determine whether alterations of histone modification status after 5-Aza-dC and TSA treatment are reflected in gene expression. RESULTS： For thep16 and MLH1 genes in two cell lines, silenced loci associated with DNA hypermethylation were characterized by histone H3-K9 hypoacetylation and hypermethylation and histone H3-K4 hypomethylation. Treatment with TSA resulted in moderately increased histone H3-K9 acetylation at the silenced loci with no effect on histone H3-K9 methylation and minimal effects on gene expression. In contrast, treatment with 5-Aza- dC rapidly reduced histone H3-K9 methylation at the silenced loci and resulted in reactivation of the two genes. Combined treatment with 5-Aza-dC and TSA was synergistic in reactivating gene expression at the loci showing DNA hypermethylation. Similarly, histone H3-K4 methylation was not affected alter TSA treatment, andincreased moderately at the silenced loci after 5-Aza-dC treatment. CONCLUSION： Hypermethylation of DNA in promoter CpG islands is related to transcriptional silencing of tumor suppressor genes. Histone H3-K9 methylation in different regions of the promoters studied correlates with DNA methylation status of each gene in gastric cancer cells. However, histone H3-K9 acetylation and H3-K4 methylation inversely correlate
基金the National Natural Science Foundation of China,No.39870661
文摘AIM: To determine the effect of cis -9, trans -11-conjugated linoleic acid (c9, t11-CLA) on the cell cycle of gastric cancer cells (SGC-7901) and its possible mechanism in inhibition cancer growth. METHODS: Using cell culture and immunocytochemical techniques, we examined the cell growth, DNA synthesis, expression of PCNA, cyclin A, B(1), D(1), p16(ink4a) and p21(cip/waf1) of SGC-7901 cells which were treated with various c9, t11-CLA concentrations (25, 50, 100 and 200 micromol.L(-1))of c 9, t 11-CLA for 24 and 48h, with a negative control (0.1% ethane). RESULTS: The cell growth and DNA synthesis of SGC-7901 cells were inhibited by c9, t11-CLA.SGC-7901 cells. Eight day after treatment with various concentrations of c9, t11-CLA mentioned above, the inhibition rates were 5.92%, 20.15%, 75.61% and 82.44%, respectively and inhibitory effect of c9, t11-CLA on DNA synthesis (except for 25 micromol.L, 24h) showed significantly less (3)H-TdR incorporation than that in the negative controls (P【0.05 and P【0.01). Immunocytochemical staining demonstrated that SGC-7901 cells preincubated in media supplemented with different c9, t11-CLA concentrations at various times significantly decreased the expressions of PCNA (the expression rates were 7.2-3.0%, 24h and 9.1-0.9% at 48h, respectively), Cyclin A (11.0-2.3%, 24h and 8.5-0.5%,48h), B(1) (4.8-1.8% at 24h and 5.5-0.6% at 48h)and D(1) (3.6-1.4% at 24h and 3.7%-0 at 48h) as compared with those in the negative controls(the expressions of PCNA, Cyclin A, B(1) and D(1) were 6.5% at 24h and 9.0% at 48h, 4.2% at 24h and 5.1% at 48h, 9.5% at 24h and 6.0% at 48h,respectively)(P【0.01), whereas the expressions of P16(ink4a) and P21(cip/waf1), cyclin-dependent kinases inhibitors(CDKI), were increased. CONCLUSION: The cell growth and proliferation of SGC-7901 cell is inhibited by c9, t11-CLA via blocking the cell cycle, with reduced expressions of cyclin A,B(1) and D(1) and enhanced expressions of CDKI(P16(ink4a) and p21(cip/waf1)).
文摘Pancreatic cancer is the fourth most common cause of cancer-related deaths in the United States, with over 38000 deaths in 2013. The opportunity to detect pancreatic cancer while it is still curable is dependent on our ability to identify and screen high-risk populations before their symptoms arise. Risk factors for developing pancreatic cancer include multiple genetic syndromes as well as modifiable risk factors. Genetic conditions include hereditary breast and ovarian cancer syndrome, Lynch Syndrome, familial adenomatous polyposis, Peutz-Jeghers Syndrome, familial atypical multiple mole melanoma syndrome, hereditary pancreatitis, cystic fibrosis, and ataxia-telangiectasia; having a genetic predisposition can raise the risk of developing pancreatic cancer up to 132-fold over the general population. Modifiable risk factors, which include tobacco exposure, alcohol use, chronic pancreatitis, diet, obesity, diabetes mellitus, as well as certain abdominal surgeries and infections, have also been shown to increase the risk of pancreatic cancer development. Several largevolume centers have initiated such screening protocols, and consensus-based guidelines for screening high-riskgroups have recently been published. The focus of this review will be both the genetic and modifiable risk factors implicated in pancreatic cancer, as well as a review of screening strategies and their diagnostic yields.
