AIM: To determine the features of microsatellite alterations and their association with clinicopathological characteristics of hepatocellular carcinoma (HCC). METHODS: Loss of heterozygosity (LOH) and microsatellite i...AIM: To determine the features of microsatellite alterations and their association with clinicopathological characteristics of hepatocellular carcinoma (HCC). METHODS: Loss of heterozygosity (LOH) and microsatellite instability (MSI) of 55 microsatellite loci were detected with PCR-based microsatellite polymorphism analyses in tumors and corresponding noncancerous liver tissues of 56 surgically resected HCCs using the MegaBACE 500 automatic DNA analysis system.RESULTS: LOH was found in 44 of 56 HCCs (78.6%) at one or several loci. Frequencies of LOH on 1p, 4q, 8p,16q, and 17p were 69.6% (39/56), 71.4% (40/56), 66.1% (37/56), 66.1% (37/56), and 64.3% (36/56), respectively. MSI was found in 18 of 56 HCCs (32.1%) at one or several loci. Ten of fifty-six (17.9%) HCCs had MSI-H. Serum HBV infection, alpha-fetoprotein concentration, tumor size, cirrhosis, histological grade, tumor capsule, as well as tumor intrahepatic metastasis, might be correlated with LOH on certain chromosome regions. CONCLUSION: Frequent microsatellite alterations exist in HCC. LOH, which represents a tumor suppressor gene pathway, plays a more important role in hepatocarcinogenesis. MSI, which represents a mismatch repair genepathway, is a rare event during liver carcinogenesis. Furthermore, LOH on certain chromosome regions may be correlated with clinicopathological characteristics in HCC.展开更多
Background and Objective: Colorectal cancer is one of the most common malignant cancers in the world. Although the clinicopathologic staging is the golden criterion for the prognosis at present, the optimum prognostic...Background and Objective: Colorectal cancer is one of the most common malignant cancers in the world. Although the clinicopathologic staging is the golden criterion for the prognosis at present, the optimum prognostic criteria for colorectal cancer should be a combination of the clinicopathologic staging and the molecular markers. However, there are currently no molecular markers available for the prognosis of colorectal cancer. Several tumor-suppressor genes associated with colorectal cancer have been mapped at the 18q21-23 region. In this study we detected the frequency of loss of heterozygosity (LOH) at chromosome 18q and investigated the relationship between LOH and clinicopathologic features and its prognostic value for patients with stage Ⅱ colon cancer. Methods: A total of 106 samples of tumor tissues and corresponding normal mucosa from patients with sporadic stage-Ⅱ colon cancer were included in this study. All the samples were formalin-fixed and paraffin-embedded. DNA was extracted from tumor tissues and LOH of D18S474, D18S55, D18S58, D18S61 and D18S64 at chromosome 18q was analyzed using polymerase chain reaction (PCR), polyacrylamide gel-electrophoresis, and DNA sequencing method. Multivariate analysis for association between LOH and prognosis in colon cancer patients was performed with Cox proportional hazards regression model. Results: The median follow-up time was 68 months. For 106 patients, 5-year survival rate was 83.6%, which was associated with age and gross tumor type (P = 0.011 and 0.034, respectively). Among 102 patients who were eligible for LOH information, the overall frequency of LOH is 49.0% (50/102), and that of LOH at 5 microsatellite loci of D18S474, D18S55, D18S58, D18S61, and D18S64 was 30.2% (26/86), 23.4% (18/77), 28.6% (20/70), 35.0% (28/80), and 20.8%(15/72), respectively. The occurrence of LOH was significantly associated with tumor location and histopathologic grade (P = 0.023, 0.016 and 0.005, respectively). LOH was more frequent on the left-side, poorly-differentiated展开更多
AIM: To examine the mechanism of inactivation of the p16 gene in gallbladder cancer,and to investigate p16 alterations and their correlation with clinicopathological features. METHODS: Specimens were collected surgica...AIM: To examine the mechanism of inactivation of the p16 gene in gallbladder cancer,and to investigate p16 alterations and their correlation with clinicopathological features. METHODS: Specimens were collected surgically from 51 patients with gallbladder cancer. We evaluated the status of protein expression,loss of heterozygosity (LOH),homozygous deletion and promoter hypermethylation using immunohistochemistry,microsatellite analysis,quantitative real-time polymerase chain reaction (PCR) and methylation-specific PCR,respectively. In addition,mutations were examined by direct DNA sequencing. RESULTS: Homozygous deletions of the p16 gene exon2,LOH at 9p21-22,p16 promoter hypermethylation,and loss of p16 protein expression were detected in 26.0% (13/50),56.9% (29/51),72.5% (37/51) and 62.7% (32/51),respectively. No mutations were found. LOH at 9p21 correlated with the loss of p16 protein expression (P < 0.05). Homozygous deletion of the p16 gene,a combination LOH and promoter hypermethylation,and multiple LOH at 9p21 were significantly correlated with the loss of p16 protein expression (P < 0.05). LOH at 9p21 and promoter hypermethylation of the p16 gene were detected in 15.4% (2/13) and 92.3% (12/13) of the tumors with homozygous deletion of the p16 gene,respectively. P16 alterations were not associated with clinicopathological features. CONCLUSION: Our results suggest that LOH and homozygous deletion may be two distinct pathways in the inactivation of the p16 gene. Homozygous deletion,a combination of LOH and promoter hypermethylation,and multiple LOH are major mechanisms of p16 inactivation in gallbladder cancer.展开更多
AIM: Microsatellites are the repeated DNA sequences scattered widely within the genomes and closely linked with many important genes. This study was designed to characterize the changes of microsatellite DNA loss of h...AIM: Microsatellites are the repeated DNA sequences scattered widely within the genomes and closely linked with many important genes. This study was designed to characterize the changes of microsatellite DNA loss of heterozygosity (LOH) in esophageal carcinogenesis. METHODS: Allelic deletions in 32 cases of matched precancerous, cancerous and normal tissues were examined by syringe microdissection under an anatomic microscope and microsatellite polymorphism analysis using 15 polymorphic markers on chromosomes 3p, 5q, 6p, 9p, 13q,17p, 17q and 18q.RESULTS: Microsatellite DNA LOH was observed in precancerous and cancerous tissues, except D9S1752. The rate of LOH increased remarkably with the lesions progressed from basal cell hyperplasia (BCH) to squamous cell carcinoma (SCC) (P＜0.05). Three markers, D9S171, D13S260 and TP53, showed the highest incidence of LOH (＞60%). LOH loci were different in precancerous and cancerous tissues. LOH in D3S1234 and TP53 was the common event in different lesions from the same patients. CONCLUSION: Microsatellite DNA LOH occurs in early stage of human esophageal carcinogenesis, even in BCH. With the lesion progressed, gene instability increases, the accumulation of this change may be one of the important mechanisms driving precancerous lesions to cancer.展开更多
基金Supported by the National Natural Science Foundation of China,No. 30370645the Hundred Leading Scientists Program of the Public Health Sector of Shanghai, No. 98BR007
文摘AIM: To determine the features of microsatellite alterations and their association with clinicopathological characteristics of hepatocellular carcinoma (HCC). METHODS: Loss of heterozygosity (LOH) and microsatellite instability (MSI) of 55 microsatellite loci were detected with PCR-based microsatellite polymorphism analyses in tumors and corresponding noncancerous liver tissues of 56 surgically resected HCCs using the MegaBACE 500 automatic DNA analysis system.RESULTS: LOH was found in 44 of 56 HCCs (78.6%) at one or several loci. Frequencies of LOH on 1p, 4q, 8p,16q, and 17p were 69.6% (39/56), 71.4% (40/56), 66.1% (37/56), 66.1% (37/56), and 64.3% (36/56), respectively. MSI was found in 18 of 56 HCCs (32.1%) at one or several loci. Ten of fifty-six (17.9%) HCCs had MSI-H. Serum HBV infection, alpha-fetoprotein concentration, tumor size, cirrhosis, histological grade, tumor capsule, as well as tumor intrahepatic metastasis, might be correlated with LOH on certain chromosome regions. CONCLUSION: Frequent microsatellite alterations exist in HCC. LOH, which represents a tumor suppressor gene pathway, plays a more important role in hepatocarcinogenesis. MSI, which represents a mismatch repair genepathway, is a rare event during liver carcinogenesis. Furthermore, LOH on certain chromosome regions may be correlated with clinicopathological characteristics in HCC.
文摘Background and Objective: Colorectal cancer is one of the most common malignant cancers in the world. Although the clinicopathologic staging is the golden criterion for the prognosis at present, the optimum prognostic criteria for colorectal cancer should be a combination of the clinicopathologic staging and the molecular markers. However, there are currently no molecular markers available for the prognosis of colorectal cancer. Several tumor-suppressor genes associated with colorectal cancer have been mapped at the 18q21-23 region. In this study we detected the frequency of loss of heterozygosity (LOH) at chromosome 18q and investigated the relationship between LOH and clinicopathologic features and its prognostic value for patients with stage Ⅱ colon cancer. Methods: A total of 106 samples of tumor tissues and corresponding normal mucosa from patients with sporadic stage-Ⅱ colon cancer were included in this study. All the samples were formalin-fixed and paraffin-embedded. DNA was extracted from tumor tissues and LOH of D18S474, D18S55, D18S58, D18S61 and D18S64 at chromosome 18q was analyzed using polymerase chain reaction (PCR), polyacrylamide gel-electrophoresis, and DNA sequencing method. Multivariate analysis for association between LOH and prognosis in colon cancer patients was performed with Cox proportional hazards regression model. Results: The median follow-up time was 68 months. For 106 patients, 5-year survival rate was 83.6%, which was associated with age and gross tumor type (P = 0.011 and 0.034, respectively). Among 102 patients who were eligible for LOH information, the overall frequency of LOH is 49.0% (50/102), and that of LOH at 5 microsatellite loci of D18S474, D18S55, D18S58, D18S61, and D18S64 was 30.2% (26/86), 23.4% (18/77), 28.6% (20/70), 35.0% (28/80), and 20.8%(15/72), respectively. The occurrence of LOH was significantly associated with tumor location and histopathologic grade (P = 0.023, 0.016 and 0.005, respectively). LOH was more frequent on the left-side, poorly-differentiated
文摘AIM: To examine the mechanism of inactivation of the p16 gene in gallbladder cancer,and to investigate p16 alterations and their correlation with clinicopathological features. METHODS: Specimens were collected surgically from 51 patients with gallbladder cancer. We evaluated the status of protein expression,loss of heterozygosity (LOH),homozygous deletion and promoter hypermethylation using immunohistochemistry,microsatellite analysis,quantitative real-time polymerase chain reaction (PCR) and methylation-specific PCR,respectively. In addition,mutations were examined by direct DNA sequencing. RESULTS: Homozygous deletions of the p16 gene exon2,LOH at 9p21-22,p16 promoter hypermethylation,and loss of p16 protein expression were detected in 26.0% (13/50),56.9% (29/51),72.5% (37/51) and 62.7% (32/51),respectively. No mutations were found. LOH at 9p21 correlated with the loss of p16 protein expression (P < 0.05). Homozygous deletion of the p16 gene,a combination LOH and promoter hypermethylation,and multiple LOH at 9p21 were significantly correlated with the loss of p16 protein expression (P < 0.05). LOH at 9p21 and promoter hypermethylation of the p16 gene were detected in 15.4% (2/13) and 92.3% (12/13) of the tumors with homozygous deletion of the p16 gene,respectively. P16 alterations were not associated with clinicopathological features. CONCLUSION: Our results suggest that LOH and homozygous deletion may be two distinct pathways in the inactivation of the p16 gene. Homozygous deletion,a combination of LOH and promoter hypermethylation,and multiple LOH are major mechanisms of p16 inactivation in gallbladder cancer.
基金Supported by National Outstanding Young Scientist Foundation of China, No. 30025016 State Basic Research Development Program of China, No. G1998051206 Foundation of Henan Education Committee, No. 1999125 and the US NIH Grant, No. CA65871
文摘AIM: Microsatellites are the repeated DNA sequences scattered widely within the genomes and closely linked with many important genes. This study was designed to characterize the changes of microsatellite DNA loss of heterozygosity (LOH) in esophageal carcinogenesis. METHODS: Allelic deletions in 32 cases of matched precancerous, cancerous and normal tissues were examined by syringe microdissection under an anatomic microscope and microsatellite polymorphism analysis using 15 polymorphic markers on chromosomes 3p, 5q, 6p, 9p, 13q,17p, 17q and 18q.RESULTS: Microsatellite DNA LOH was observed in precancerous and cancerous tissues, except D9S1752. The rate of LOH increased remarkably with the lesions progressed from basal cell hyperplasia (BCH) to squamous cell carcinoma (SCC) (P＜0.05). Three markers, D9S171, D13S260 and TP53, showed the highest incidence of LOH (＞60%). LOH loci were different in precancerous and cancerous tissues. LOH in D3S1234 and TP53 was the common event in different lesions from the same patients. CONCLUSION: Microsatellite DNA LOH occurs in early stage of human esophageal carcinogenesis, even in BCH. With the lesion progressed, gene instability increases, the accumulation of this change may be one of the important mechanisms driving precancerous lesions to cancer.
