There may be a close relationship between myc oncogenes and carcinogenesis of human neuroblastoma. In previous studies, we were able to induce differentiation of certain neuroblastoma cell lines with NGF. In order to...There may be a close relationship between myc oncogenes and carcinogenesis of human neuroblastoma. In previous studies, we were able to induce differentiation of certain neuroblastoma cell lines with NGF. In order to study gene regulation during differentiation, N-myc and c-myc cDNA probe were hybridized with RNA extracted from different cell lines before and after NGF treatment. It was found that cell lines which expressed N-myc did not express c-myc while those with c-myc did not express N-myc except for SHEP cell line which had neither c-myc nor N-myc expression. In NGF-induced differentiated neuroblastoma cells, c-myc oncogene was down-regulated in comparison with the control samples. The time course of c-myc down-regulation was concomitant with the appearance of morphological differentiation. In situ hybridization also showed remarkable reduction of c-myc oncogene expression in NGF-induced differentiated cells as compared with the untreated control cells. These results indicate that down-regulation of c-myc oncogene may be a key event during NGF-induced differentiation and overexpression of c-myc oncogene may, at least partially, be responsible for the genesis of neuroblastoma.展开更多
Ojective: To investigate the effect of hammerhead ribozyme that specifically cleaves c-myc mRNA on the proliferation of vascular smooth muscle cells (VSMCs ). Methods: Based on the computer analysis of the secondary s...Ojective: To investigate the effect of hammerhead ribozyme that specifically cleaves c-myc mRNA on the proliferation of vascular smooth muscle cells (VSMCs ). Methods: Based on the computer analysis of the secondary structure of c-myc mRNA, nt 2029 in rat c-myc oncogene was selected as a cleaving site for hammerhead ribozyme and the ribozyme was designed. With automatic DNA synthesizer, the two complementary DNA strands of the ribozyme were synthesized. The ribozyme gene was cloned into pGEM3Zf ( + ) vector and subcloned into eukaryotic expression pcD-NA3 vector. The recombinant pcDNA-Rz was transfected into the cultured rat VSMCs by lipofectAMINE mediated DNA transfection protocol and individual cell clones were selected by G418. Results: The sequence of ribozyme gene inserted in pGEMSZf ( + ) vector was proved to be perfectly correct. In VSMCs transfected with recombinant pcDNA-Rz, flow cytometry analysis showed that the S phase and G2/M fractions were decreased significantly and cell proliferation stagnated in the G0/G1 phase. Conclusion: The results suggest that hammerhead ribozyme that specifically cleaves c-myc mRNA can significantly inhibit the proliferation of VSMCs.展开更多
Objective To investigate N-myc downstream-regulated gene 2(NDRG2) expression in ovarian cancer cells and its potential usefulness as a diagnostic marker and/or target for therapeutic intervention.Methods Human NDRG2 L...Objective To investigate N-myc downstream-regulated gene 2(NDRG2) expression in ovarian cancer cells and its potential usefulness as a diagnostic marker and/or target for therapeutic intervention.Methods Human NDRG2 L/S gene was obtained by revers-transcription polymerase chain reaction(RT-PCR). Sequence analysis confirmed the identity of NDRG2 L/S gene, which was then inserted into a eukaryotic vector p LNCX2, which was in turn transfected into NDRG2 gene-negative HO-8910 cells. Flow cytometry(FCM) and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide(MTT) assay were conducted to determine the proliferation rate of HO-8910 cells. Cisplatin resistance of HO-8910 cells transfected with p LNCX2-NDRG2 L/S was evaluated by FCM. Tumors were generated in female nude mice by subcutaneous injection of HO-8910 cells.Results NDRG2 gene was isolated and its expression vector was successfully constructed. NDRG2 expression positively correlated with the proliferation of HO-8910 cells. NDRG2 L/S promoted tumorigenicity in HO-8910 cells.Conclusion The present study identified a novel function of NDRG2 L/S gene and demonstrated its involvement in the promotion of ovarian cancer cell proliferation and enhancement of cisplatin resistance in HO-8910 cells. Future studies are warranted to determine the relationship between NDRG2 upregulation and ovarian cancer progression.展开更多
Expression of c-myc oncogene transcripts in colorectal neoplasia was studied in paraffin embedded tissue sections from 25 patients undergoing surgery and from the rectal carcinoma cell line HR-8348 by using in situ hy...Expression of c-myc oncogene transcripts in colorectal neoplasia was studied in paraffin embedded tissue sections from 25 patients undergoing surgery and from the rectal carcinoma cell line HR-8348 by using in situ hybridization,and its amplification was investigated in tumor and normal mucosa tissue from 25 coloproctomy samples by slot blot hybridization. Overexpression of this gene was seen in 78% (7/9) of the benign adenomas and 91% (20/22) of the malignancies sampled. There was no significant correlation between overexpression and the histologic type or grade, and no significant relationship between the level of expression and clinical stage was found, although overexpression was apparently more common in tumors with metastasis. Amplification of the gene was found in 0 of 4 benign adenomas and 7 of 22 malignancies. No obvious correlation was found between amplification and histological type or grade, though amplification was more frequent in tumors with metastasis. Amplification was also found in 2 adenomas with malignant change. The results suggest that multiple factors are involved in the progression of colorectal cancer , and in situ hybridization with a nonradiolabeled probe is useful in the detection of gene expression.展开更多
This study was designed using c-myc antisense transcripts to evaluate how alteration of c-myc expression in human myeloid leukemic HL-60 cells could influence the myelomonocytic differentiation and induction of apopto...This study was designed using c-myc antisense transcripts to evaluate how alteration of c-myc expression in human myeloid leukemic HL-60 cells could influence the myelomonocytic differentiation and induction of apoptosis. The recombinant plasmid pDACx expressing antisense transcripts to c-myc fragment containing a part of intron 1 and 137 nt exon 2 was constructed. pDACx was transfected into HL-60 cell line by lipofectin reagent.Cytochemical stainings including NBT reduction, peroxidase and α -NAE as well as detection of CD13 and CD33 antigens by flow cytometric analysis indicated occurrence of myelomonocytic differentiation in cells expressing antisense transcripts to c-myc. DNA degradation measured by DNA gel electrophoresis and typical morphological changes observed under electron microscope proved the switchon of apoptosis in terminally differentiating HL-60 cells.展开更多
Sprague-Dawley rats were implanted with silastic capsules containing β-estradiol. After 60 days, their pituitary weights, serum prolactin contentsand transcription level of c-myc proto-oncogene were found increasedsi...Sprague-Dawley rats were implanted with silastic capsules containing β-estradiol. After 60 days, their pituitary weights, serum prolactin contentsand transcription level of c-myc proto-oncogene were found increasedsignificantly. It was also found that the anterior pituitary cells proliferatedsignificantly, but their differentiation was suppressed.展开更多
A rat liver epithelial cell line designated LW13 was established using a sequential sedimentation method. The cell line retained many normal properties of liver epithelial cells and showed some structural and function...A rat liver epithelial cell line designated LW13 was established using a sequential sedimentation method. The cell line retained many normal properties of liver epithelial cells and showed some structural and functional features resembling those of liver parenchymal cells. LW13 cells became malignant after the introduction of exogenous transforming EJ Ha ras gene. Tumors produced by inoculation of the transformed cells into baby rats .contained areas of poorly differentiated hepatocellular carcinoma. In situ hybridization analysis confirmed the random rather than specific integration of exogenous ras gene into host chromosomes. Furthermore , an at least tenfold increase in the expression of the endogenous c myc gene was detected among transformed cell lines, suggesting the involvement of the c myc proto oncogene in the in vitro transformation of rat liver epithelial cells by EJ Ha ras oncogene.展开更多
Objective： To investigate the mechanism of herb cake-partitioned moxibustion treating ulcerative colitis （UC） from the relationship between expression of p53 and C-myc protein, and morbidity of UC. Methods： Rats m...Objective： To investigate the mechanism of herb cake-partitioned moxibustion treating ulcerative colitis （UC） from the relationship between expression of p53 and C-myc protein, and morbidity of UC. Methods： Rats model of UC was made with immune methods and local stimulation. Forty SD rats were divided into normal, model, herb cake-partitioned, and mild moxibustion group by a random number table, 10 rats in each group. Hanging moxibustion in the mild moxibustion group was applied to Tianshu （ST 25） and Qihai （CV 6） for 10 rain. Two moxa cones of herb cake-partitioned moxibustion were applied to the same acupoints respectively, in the herb cake-partitioned moxibustion group. Expression of p53 and C-myc protein was measured with immuno- histochemistical method in the colonic tissue of rats with UC. Results： Postive area, strength, and the immunohistochemistry index of the expression of p53 and C-myc protein were found more in the model rats than those in the normal rats （P〈0.01）, whereas less in the herb cake-partitioned moxibustion and mild moxibustion groups than those in the model group （P〈0.01）. Conclusion： p53 and C-myc play important roles in the morbidity and development of UC, and herb cake-partitioned moxibustion could regulate the expression of p53 and C-myc protein in the colonic tissue of UC rats.展开更多
文摘There may be a close relationship between myc oncogenes and carcinogenesis of human neuroblastoma. In previous studies, we were able to induce differentiation of certain neuroblastoma cell lines with NGF. In order to study gene regulation during differentiation, N-myc and c-myc cDNA probe were hybridized with RNA extracted from different cell lines before and after NGF treatment. It was found that cell lines which expressed N-myc did not express c-myc while those with c-myc did not express N-myc except for SHEP cell line which had neither c-myc nor N-myc expression. In NGF-induced differentiated neuroblastoma cells, c-myc oncogene was down-regulated in comparison with the control samples. The time course of c-myc down-regulation was concomitant with the appearance of morphological differentiation. In situ hybridization also showed remarkable reduction of c-myc oncogene expression in NGF-induced differentiated cells as compared with the untreated control cells. These results indicate that down-regulation of c-myc oncogene may be a key event during NGF-induced differentiation and overexpression of c-myc oncogene may, at least partially, be responsible for the genesis of neuroblastoma.
基金Supported by the National Natural Science Foundation of China(No.39600064)
文摘Ojective: To investigate the effect of hammerhead ribozyme that specifically cleaves c-myc mRNA on the proliferation of vascular smooth muscle cells (VSMCs ). Methods: Based on the computer analysis of the secondary structure of c-myc mRNA, nt 2029 in rat c-myc oncogene was selected as a cleaving site for hammerhead ribozyme and the ribozyme was designed. With automatic DNA synthesizer, the two complementary DNA strands of the ribozyme were synthesized. The ribozyme gene was cloned into pGEM3Zf ( + ) vector and subcloned into eukaryotic expression pcD-NA3 vector. The recombinant pcDNA-Rz was transfected into the cultured rat VSMCs by lipofectAMINE mediated DNA transfection protocol and individual cell clones were selected by G418. Results: The sequence of ribozyme gene inserted in pGEMSZf ( + ) vector was proved to be perfectly correct. In VSMCs transfected with recombinant pcDNA-Rz, flow cytometry analysis showed that the S phase and G2/M fractions were decreased significantly and cell proliferation stagnated in the G0/G1 phase. Conclusion: The results suggest that hammerhead ribozyme that specifically cleaves c-myc mRNA can significantly inhibit the proliferation of VSMCs.
文摘Objective To investigate N-myc downstream-regulated gene 2(NDRG2) expression in ovarian cancer cells and its potential usefulness as a diagnostic marker and/or target for therapeutic intervention.Methods Human NDRG2 L/S gene was obtained by revers-transcription polymerase chain reaction(RT-PCR). Sequence analysis confirmed the identity of NDRG2 L/S gene, which was then inserted into a eukaryotic vector p LNCX2, which was in turn transfected into NDRG2 gene-negative HO-8910 cells. Flow cytometry(FCM) and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide(MTT) assay were conducted to determine the proliferation rate of HO-8910 cells. Cisplatin resistance of HO-8910 cells transfected with p LNCX2-NDRG2 L/S was evaluated by FCM. Tumors were generated in female nude mice by subcutaneous injection of HO-8910 cells.Results NDRG2 gene was isolated and its expression vector was successfully constructed. NDRG2 expression positively correlated with the proliferation of HO-8910 cells. NDRG2 L/S promoted tumorigenicity in HO-8910 cells.Conclusion The present study identified a novel function of NDRG2 L/S gene and demonstrated its involvement in the promotion of ovarian cancer cell proliferation and enhancement of cisplatin resistance in HO-8910 cells. Future studies are warranted to determine the relationship between NDRG2 upregulation and ovarian cancer progression.
文摘Expression of c-myc oncogene transcripts in colorectal neoplasia was studied in paraffin embedded tissue sections from 25 patients undergoing surgery and from the rectal carcinoma cell line HR-8348 by using in situ hybridization,and its amplification was investigated in tumor and normal mucosa tissue from 25 coloproctomy samples by slot blot hybridization. Overexpression of this gene was seen in 78% (7/9) of the benign adenomas and 91% (20/22) of the malignancies sampled. There was no significant correlation between overexpression and the histologic type or grade, and no significant relationship between the level of expression and clinical stage was found, although overexpression was apparently more common in tumors with metastasis. Amplification of the gene was found in 0 of 4 benign adenomas and 7 of 22 malignancies. No obvious correlation was found between amplification and histological type or grade, though amplification was more frequent in tumors with metastasis. Amplification was also found in 2 adenomas with malignant change. The results suggest that multiple factors are involved in the progression of colorectal cancer , and in situ hybridization with a nonradiolabeled probe is useful in the detection of gene expression.
文摘This study was designed using c-myc antisense transcripts to evaluate how alteration of c-myc expression in human myeloid leukemic HL-60 cells could influence the myelomonocytic differentiation and induction of apoptosis. The recombinant plasmid pDACx expressing antisense transcripts to c-myc fragment containing a part of intron 1 and 137 nt exon 2 was constructed. pDACx was transfected into HL-60 cell line by lipofectin reagent.Cytochemical stainings including NBT reduction, peroxidase and α -NAE as well as detection of CD13 and CD33 antigens by flow cytometric analysis indicated occurrence of myelomonocytic differentiation in cells expressing antisense transcripts to c-myc. DNA degradation measured by DNA gel electrophoresis and typical morphological changes observed under electron microscope proved the switchon of apoptosis in terminally differentiating HL-60 cells.
文摘Sprague-Dawley rats were implanted with silastic capsules containing β-estradiol. After 60 days, their pituitary weights, serum prolactin contentsand transcription level of c-myc proto-oncogene were found increasedsignificantly. It was also found that the anterior pituitary cells proliferatedsignificantly, but their differentiation was suppressed.
文摘A rat liver epithelial cell line designated LW13 was established using a sequential sedimentation method. The cell line retained many normal properties of liver epithelial cells and showed some structural and functional features resembling those of liver parenchymal cells. LW13 cells became malignant after the introduction of exogenous transforming EJ Ha ras gene. Tumors produced by inoculation of the transformed cells into baby rats .contained areas of poorly differentiated hepatocellular carcinoma. In situ hybridization analysis confirmed the random rather than specific integration of exogenous ras gene into host chromosomes. Furthermore , an at least tenfold increase in the expression of the endogenous c myc gene was detected among transformed cell lines, suggesting the involvement of the c myc proto oncogene in the in vitro transformation of rat liver epithelial cells by EJ Ha ras oncogene.
文摘Objective： To investigate the mechanism of herb cake-partitioned moxibustion treating ulcerative colitis （UC） from the relationship between expression of p53 and C-myc protein, and morbidity of UC. Methods： Rats model of UC was made with immune methods and local stimulation. Forty SD rats were divided into normal, model, herb cake-partitioned, and mild moxibustion group by a random number table, 10 rats in each group. Hanging moxibustion in the mild moxibustion group was applied to Tianshu （ST 25） and Qihai （CV 6） for 10 rain. Two moxa cones of herb cake-partitioned moxibustion were applied to the same acupoints respectively, in the herb cake-partitioned moxibustion group. Expression of p53 and C-myc protein was measured with immuno- histochemistical method in the colonic tissue of rats with UC. Results： Postive area, strength, and the immunohistochemistry index of the expression of p53 and C-myc protein were found more in the model rats than those in the normal rats （P〈0.01）, whereas less in the herb cake-partitioned moxibustion and mild moxibustion groups than those in the model group （P〈0.01）. Conclusion： p53 and C-myc play important roles in the morbidity and development of UC, and herb cake-partitioned moxibustion could regulate the expression of p53 and C-myc protein in the colonic tissue of UC rats.
