The role of growth factors and proto-oncogene in pulmonary vascular structural remodelling is not well known.The present study examined gene expression of platelet-derived growth factor(PDGF)-A and -B chain and proto-...The role of growth factors and proto-oncogene in pulmonary vascular structural remodelling is not well known.The present study examined gene expression of platelet-derived growth factor(PDGF)-A and -B chain and proto-oncogene,c-myc,in lung tissue and pulmonary artery of rats exposed to hypoxia and compared to those levels of gene expression in normal rats.Normal lungs and pulmonary artery expressed PDGF-A chain transcript of 1.7 kb and PDGF-B chain transcript of 3.5 Kb.The c-myc transcript of 2.2 kb was expressed as well. After hypoxic exposure for 7 and 14 days mRNA levels of PDGF-B chain and cmyc were elevated significantly compared with those of control rats.PDGF-A chain mRNA increased after hypoxia for 7 days,and then declined.These results suggest that activation of autocrine and/or paracrine is important in proliferation mechanism of pulmonary artery smooth muscle cells in hypoxic pulmonary hypertensive rats.展开更多
Objective:To study the effects of recombinant antisense c-myc adenovirus (rAS-c-myc-Ad) on SGG 7901 human gastric carcinoma cell line in for and in nude mice. Methods:The effects of rAS-c-myc-Ad and LacZ-Ad on SGG 790...Objective:To study the effects of recombinant antisense c-myc adenovirus (rAS-c-myc-Ad) on SGG 7901 human gastric carcinoma cell line in for and in nude mice. Methods:The effects of rAS-c-myc-Ad and LacZ-Ad on SGG 7901 gastric carcinoma cells were observed with X-galstaining, MTT, DNA gradient degradation test, TUNEL, flow cytometry, PCR and western blot. The therapeutic effects of rAS-c-myc-Ad on the implanted ax 7901 cells in nude mice were also ob served.Results: rAS-c-myc-Ad significantly inhibited the growth of SGG 7901 cells and induced their apoptosis. After the treatment of rAS-c-myc-Ad, the prolifetion rate of the cells was decreased by 44’ l% in de and SGC 7901 cells failed to form caxcinoma ther they were implanted into nude mice. Injection of rAS-c-myc-Ad into the carcinoma subcutaneously implanted to the nude mice significantly inhibited the growth of the implanted carcinoma with an inhibition rate of 68. 9%. Conclusion: rAS-c- myc- Ad significantly inhibits the growth of SGG 7901 human gastric carcinoma cells in vitro and in nude展开更多
Induction of c-myc gene amplification in L1210 cells by hydroxyurea and its inhibition by homohar-ringtonine were investigated using the DNA-DNA molecular hybridization technique. When the cells were treated with hydr...Induction of c-myc gene amplification in L1210 cells by hydroxyurea and its inhibition by homohar-ringtonine were investigated using the DNA-DNA molecular hybridization technique. When the cells were treated with hydroxyurea 1.0 mM for 16 hours, and incubated a further 16 hours in a drug-free medium, the c-myc gene amplified 23.5-fold. If homohar-ringtonine 50 μM was used at the same time as hydroxyurea, gene amplification did not occur. Cycloheximide, an inhibitor of protein biosynthesis, produced a similar effect. Our results indicated that a (or some) protein factor(s) might be involved in gene amplification. Detailed analysis showed that the synthesis of this protein factor(s) started 4 hours before the initiation of the S phase but did not continue in the S phase. It was also found that this protein factor(s) was very labile and began to degrade 2 hours after its appearance.展开更多
The expressions of HBV X gene and ets-2, IGF-I, c-myc and N-ras were studied in 7 pairs of human primary hepatocellular carcinoma (PHC) and tumor-adjacent tissues, using RNA hybridization and im-munoblot methods. The ...The expressions of HBV X gene and ets-2, IGF-I, c-myc and N-ras were studied in 7 pairs of human primary hepatocellular carcinoma (PHC) and tumor-adjacent tissues, using RNA hybridization and im-munoblot methods. The results showed that specific 17 and 28 kD HBV X gene products (HBxAg) were existed in a portion of PHC and tumor-adjacent tissues. The 17 kD HBxAg was detected in the sera of 3 patients who also had 17 kD HBxAg in their liver tissues. Multiple expressions of oncogenes such as ets-2, c-myc and N-ras were observed in PHC and tumor-adjacent tissues that had HBxAg expressed, indicating HBxAg might function as a transactivator in the course of intracellular proto-oncogene activation. It is also observed that in some tumor-adjacnet tissues the expressions of ets-2, c-myc and N-ras were higher than those in corresponding PHC. The relationship of HBxAg to the expression of est-2, IGF-Ⅱ, c-myc and their possible roles in the carcinogenesis of PHC are discussed.展开更多
Human c-myc cDNA was fused with the hormonebinding domain (HBD) cDNA of murine estrogen receptorgene and the chimeric gene was introduced into the CHOcells. The fusion protein, c-MycER, becomes activatedwhen the synth...Human c-myc cDNA was fused with the hormonebinding domain (HBD) cDNA of murine estrogen receptorgene and the chimeric gene was introduced into the CHOcells. The fusion protein, c-MycER, becomes activatedwhen the synthetic steroid, 4-hydroxy-tamoxifen (OHT),binds HBD. Activated c-MycER, likely c-Myc, can inducequiescent CHO cells reentry into S phase and subsequentcell death under serum-free condition. In addition, theexpression of some proposed c-myc target genes such asODC, MrDb, cad, rcc1 and rc1 were found to increase uponOHT induction before S, phase entry and apoptosis, indicating that these target genes are involved in cell cycleregulation and/or apoptosis control. However, the mutantD106-143c-MycER protein does not have above activities.展开更多
In a total of 83 UN specimens were investigated for proto-oncogene mutations, tumor supressor genes promoter methylation status and c-myc and Ki-67 expression. Point mutations in c-myc were detected in cases with high...In a total of 83 UN specimens were investigated for proto-oncogene mutations, tumor supressor genes promoter methylation status and c-myc and Ki-67 expression. Point mutations in c-myc were detected in cases with high grade and proliferation index. Mutated K-ras proto-onco- gene profiles were detected in 17 (21%) tumoral spiecemens that examined. Tumor specimens were also showed hypermethylated promoter domain for the SFRP2, MGMT tumor supressor genes. These findings showed the combine effect of mutated c-myc and K-ras oncogene and epigenetic inactivation of tissue specific tumor supressor genes (TS) play a crucial role in tumor progression and recurrence in UN carcinogenesis.展开更多
The human promyelocytic cell line HL-60 overexpresses the c-myc protooncogene. Plasmid pDACx carrying antisense human c-myc DNA and neo gene was introduced into HL-60 cells with lipofectin reagent. Upon DNA entering t...The human promyelocytic cell line HL-60 overexpresses the c-myc protooncogene. Plasmid pDACx carrying antisense human c-myc DNA and neo gene was introduced into HL-60 cells with lipofectin reagent. Upon DNA entering the tar-geted celis and expression of antisense transcripts to c-myc, C-MYC protein level, cell proliferation and colony-forming potentiality were all definitely inhibited.展开更多
AIM: To investigate a novel therapeutic strategy to target and suppress c-myc in human cancers using far up stream element (FUSE)-binding protein-interacting repressor (FIR).
The neonate is particularly susceptible to the development of hypoxic pulmonary hypertension. The present study was undertaken to observe the effect of hypoxia on DNA synthesis and c-myc gene expression between newbor...The neonate is particularly susceptible to the development of hypoxic pulmonary hypertension. The present study was undertaken to observe the effect of hypoxia on DNA synthesis and c-myc gene expression between newborn calf and adult bovine PASMC in vilro. DNA synthesis measured by 3H- TdR incorporation was increased after hypoxic challenge for 24h. Hypoxia enhanced the increment in 3H-TdR incorporation induced by EGF. Northern blot analysis revealed that PASMC cultured in both normoxia and hypoxia expressed c- myc gene transcript of 2. 2Kb ,but there is a higher 2. 2Kb mRNA expression in hypoxic PASMC than that in normoxia. We speculate that newborn calf PASMC exhibited potential response to hypoxia than adult,which was augmented by EGF. Enhanced c-myc gene expression may lead to a great understanding of the mechanism of PASMC growth in the development of pulmonary hypertension.展开更多
The recombinant plasmid PGC was constructed for transcription unit of c-myc gene with diorientation in vitro, to make RNA probes for detection of c-myc mRNA and antisence RNA expression of tranfectant HL-9,which was o...The recombinant plasmid PGC was constructed for transcription unit of c-myc gene with diorientation in vitro, to make RNA probes for detection of c-myc mRNA and antisence RNA expression of tranfectant HL-9,which was obtained from HL60 cells transfected with inducible c-myc antisense RNA expression plasmid. The results from HL-9 cells induced by Cd2+ indicated that expression of c-myc antisense RNA increased with Cd2+ concentration and exposure time, while c-myc mRNA expression progressively reduced. Using immunohistochemical technique no c-myc P62 protein expression was detected. The incorporation of 3H-TdR, 3H-UR and 3H-Leu revealed significant suppression of DNA, RNA and protein biosynthesis. It is suggested that the reversion changes previously reported in malignant Phenotypes of HL-9 cells and the inhibition of macromolecular biosynthesis mentioned above were associated with the blockade of c-myc gene expression by its antisense RNA.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 explore the inhibition of the expression of c-Myc in human hepatocellular carcinoma via vector-based RNA interference (RNAi). Methods: Two RNA interference DNA templates targeting c-Myc oncogene were des...Objective: To explore the inhibition of the expression of c-Myc in human hepatocellular carcinoma via vector-based RNA interference (RNAi). Methods: Two RNA interference DNA templates targeting c-Myc oncogene were designed via online software and synthesized. By ligation, the fragments were inserted into pSilencer 1.0-U6 to construct the recombinant siRNA expressing plasmids. The identified recombinants were introduced into BEL-7402 cells with Lipofactamine. The inhibition of c-Myc expression, together with the expression of CDK4, hTERT and Gadd45β in c-Myc down-regulated BEL-7402 cells, were analyzed by semi-quantitative RT-PCR. Results: Two recombinant plasmids pSic-myc-1 and pSic-myc-2, which direct the yields of siRNAs targeting c-Myc in cells, were constructed. Among which, pSic-myc-2 was shown to trigger a RNAi-mediated inhibition of expression of c-Myc in BEL-7402 by up to 90%. In c-Myc knockdown BEL-7402 cells, the expression of CDK4 and hTERT were down-regulated with a ratio of 85% and 57%, respectively, while the expression of Gadd45β was up-regulated by up to 110%. Conclusion: The expression of c-Myc in BEL-7402 could be suppressed by vector-based RNA interference successfully. The knockdown of c-Myc in turn resulted in the changes of expression of genes related to cell proliferation and apoptosis. Thus, our study provided a preliminary data in searching of a c-Myc-targeted RNAi therapy of human hepatocellular carcinoma.展开更多
Retinoblastoma (Rb) is the most common malignant'cancer of eye.So-Rb_(50) is the first Rb cell line established in China in 1988.It has passed to the 387th passage now.We collected cells of the 327th passage of SO...Retinoblastoma (Rb) is the most common malignant'cancer of eye.So-Rb_(50) is the first Rb cell line established in China in 1988.It has passed to the 387th passage now.We collected cells of the 327th passage of SO-Rb_(50),purified its genomic DNA and detected it with Rb and c-myc cDNA probes respectively(normal human white blood cells DNA was the control).We found the Rb gene was deleted while c-myc gene was amplified three times.This provides a basis for further study of the regulation of tumor development and tumor reversal with this cell line in vitro.Eye Science 1993;9:34-37.展开更多
Objectives To investigate the c myc gene expression in nasopharyngeal carcinoma (NPC) at mRNA and protein levels, and to evaluate the relationship between the degree of expression and the clinicopathological data. ...Objectives To investigate the c myc gene expression in nasopharyngeal carcinoma (NPC) at mRNA and protein levels, and to evaluate the relationship between the degree of expression and the clinicopathological data. Methods The expression of c myc specific mRNA and protein was detected using in situ hybridization with digoxigenin labeled probe and immunohistochemistry in 12 cases of normal nasopharyngeal epithelium (NE) and 48 cases of NPC. The intensity of staining for each sample was assessed as negative, weak, moderate and intense. Statistical analyses were performed using the Chi square test and the rank sum test. Results For normal NE, 41.7% (5/12) had weak (4/12) or moderate (1/12) staining for c myc protein and 41.7% (5/12) had weak staining for c myc mRNA. In contrast, 89.6% (43/48) of NPC showed some degree of c myc protein positive and 87.5% (42/48) showed some degree of c myc mRNA positive. In most samples, the expression of c myc protein was consistent with that of c myc mRNA. C myc protein and mRNA expression levels in NPC were significantly higher than those in normal NE, and correlated with early recurrence, but they were not significantly related to patient′s age, sex, EBVCA IgA titre, disease stage, lymph node status and metastasis. Conclusions C myc gene over expression may be involved in the pathogenesis and early recurrence of NPC. Further studies are needed to substantiate the preliminary findings.展开更多
Objective To investigate the expression of human telomerase catalytic subunit,hTERT, in human non-small cell lung cancer (NSCLC) and its correlations to c-myc gene.Methods hTERT and c-myc mRNA expressions were detecte...Objective To investigate the expression of human telomerase catalytic subunit,hTERT, in human non-small cell lung cancer (NSCLC) and its correlations to c-myc gene.Methods hTERT and c-myc mRNA expressions were detected by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Statistical correlation analysis was made to estimate whether there was interrelation between them.Results Positive rate of hTERT expression in 51 surgically resected lung cancer specimens was 86.3%,significantly higher than that in adjacent non-neoplastic lung tissues and benign lesions,which were 14.3% and 27.3% respectively. No statistical significance was observed between the frequency of hTERT expression and histologic types,degree of differentiation,TNM stages,tumor size or lymph nodes metastases. Correlation analysis revealed that the expression of c-myc gene was significantly related to that of hTERT (correlation coefficient,r =0.633,P <0.001).Conclusions hTERT may be a useful tumor marker in diagnosing lung cancer. Significant correlation between the expression of hTERT and c-myc mRNA indicates that the activation and up-regulation of hTERT might be conferred by over-expression of c-myc gene.展开更多
One of the important advancements in DNA repair research is the demonstration of preferential repair of transcriptionally active DNA in UV-irradiation cells. Experiment results have shown that repair in specific seque...One of the important advancements in DNA repair research is the demonstration of preferential repair of transcriptionally active DNA in UV-irradiation cells. Experiment results have shown that repair in specific sequence in and around展开更多
A human esophageal cancer cell line (EC8712) expressing high-level Myc protein was infected with recombmant retroviral particles (pA-BD9) at a multiplicity of infection (MOI) 1:1. This viral particle contains a neomyc...A human esophageal cancer cell line (EC8712) expressing high-level Myc protein was infected with recombmant retroviral particles (pA-BD9) at a multiplicity of infection (MOI) 1:1. This viral particle contains a neomycin-resistant gene and a 1.53-kb antisense RNA spanning the 2nd exon and its flanking sequences of the human c-myc oncogene. The G418-resistant EC8712 clones showed an 86% inhibition of growth rate and morphological changes characteristic of terminal differentiation and apoptosis. A decrease of about 80% of Myc protein was also observed in these infected cells by ABC-ELISA assay. 12-24 h after the infection of ECS712 cells with pA-BD9 at a high viral particle concentration (MOI = 1:10), the integration of the extrinsic 1.53-kb antisense c-myc fragment into the cancer cell genome was evidenced by the Southern blot analysis. Northern blot analyses showed the expression of this antisense fragment and a decrease of the intrinsic c-myc expression by 74% in comparison with that of the parental EC8712 cells. Heterotransplants of the infected EC8712 cells into the nude mice revealed a substantial decrease in tumorigemcity and morphological changes characteristic of terminal differentiation and apoptosis. Primary monolayer cell cultures of normal epithelia derived from the fetal and adult esophagus mucosa were set as controls. No noticeable increase in c-myc expression was found in these cultures Infection of these cells with the same recombinant viral particles neither affected the growth rate of the cells nor their normal morphology. Our experiments indicate that the drastic decrease of the over-expressed Myc protein in cancer cells may also be an entrance to one of many pathways leading to the terminal differentiation and programmed cell death.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
USING electron microscope, cytochemical and biochemical techniques we found that parts ofpolysomes, some mRNAs, several initiation factors and the elongation factor 2 are bound tocytoskeleton. This means that the cyto...USING electron microscope, cytochemical and biochemical techniques we found that parts ofpolysomes, some mRNAs, several initiation factors and the elongation factor 2 are bound tocytoskeleton. This means that the cytoskeleton may also play a role in gene expression.The c-jun, c-fos and c-myc proteins are transcription factors, which play an important role inthe regulation of progression from Go to S phase. The disruption of the microfilaments(MF) by cytochalasin D(CD) in HeLa cells results in the inhanced transcription of the展开更多
文摘The role of growth factors and proto-oncogene in pulmonary vascular structural remodelling is not well known.The present study examined gene expression of platelet-derived growth factor(PDGF)-A and -B chain and proto-oncogene,c-myc,in lung tissue and pulmonary artery of rats exposed to hypoxia and compared to those levels of gene expression in normal rats.Normal lungs and pulmonary artery expressed PDGF-A chain transcript of 1.7 kb and PDGF-B chain transcript of 3.5 Kb.The c-myc transcript of 2.2 kb was expressed as well. After hypoxic exposure for 7 and 14 days mRNA levels of PDGF-B chain and cmyc were elevated significantly compared with those of control rats.PDGF-A chain mRNA increased after hypoxia for 7 days,and then declined.These results suggest that activation of autocrine and/or paracrine is important in proliferation mechanism of pulmonary artery smooth muscle cells in hypoxic pulmonary hypertensive rats.
基金Supported by National 863 High Science and Technology Foundation of China, No.Z20-01-02
文摘Objective:To study the effects of recombinant antisense c-myc adenovirus (rAS-c-myc-Ad) on SGG 7901 human gastric carcinoma cell line in for and in nude mice. Methods:The effects of rAS-c-myc-Ad and LacZ-Ad on SGG 7901 gastric carcinoma cells were observed with X-galstaining, MTT, DNA gradient degradation test, TUNEL, flow cytometry, PCR and western blot. The therapeutic effects of rAS-c-myc-Ad on the implanted ax 7901 cells in nude mice were also ob served.Results: rAS-c-myc-Ad significantly inhibited the growth of SGG 7901 cells and induced their apoptosis. After the treatment of rAS-c-myc-Ad, the prolifetion rate of the cells was decreased by 44’ l% in de and SGC 7901 cells failed to form caxcinoma ther they were implanted into nude mice. Injection of rAS-c-myc-Ad into the carcinoma subcutaneously implanted to the nude mice significantly inhibited the growth of the implanted carcinoma with an inhibition rate of 68. 9%. Conclusion: rAS-c- myc- Ad significantly inhibits the growth of SGG 7901 human gastric carcinoma cells in vitro and in nude
文摘Induction of c-myc gene amplification in L1210 cells by hydroxyurea and its inhibition by homohar-ringtonine were investigated using the DNA-DNA molecular hybridization technique. When the cells were treated with hydroxyurea 1.0 mM for 16 hours, and incubated a further 16 hours in a drug-free medium, the c-myc gene amplified 23.5-fold. If homohar-ringtonine 50 μM was used at the same time as hydroxyurea, gene amplification did not occur. Cycloheximide, an inhibitor of protein biosynthesis, produced a similar effect. Our results indicated that a (or some) protein factor(s) might be involved in gene amplification. Detailed analysis showed that the synthesis of this protein factor(s) started 4 hours before the initiation of the S phase but did not continue in the S phase. It was also found that this protein factor(s) was very labile and began to degrade 2 hours after its appearance.
文摘The expressions of HBV X gene and ets-2, IGF-I, c-myc and N-ras were studied in 7 pairs of human primary hepatocellular carcinoma (PHC) and tumor-adjacent tissues, using RNA hybridization and im-munoblot methods. The results showed that specific 17 and 28 kD HBV X gene products (HBxAg) were existed in a portion of PHC and tumor-adjacent tissues. The 17 kD HBxAg was detected in the sera of 3 patients who also had 17 kD HBxAg in their liver tissues. Multiple expressions of oncogenes such as ets-2, c-myc and N-ras were observed in PHC and tumor-adjacent tissues that had HBxAg expressed, indicating HBxAg might function as a transactivator in the course of intracellular proto-oncogene activation. It is also observed that in some tumor-adjacnet tissues the expressions of ets-2, c-myc and N-ras were higher than those in corresponding PHC. The relationship of HBxAg to the expression of est-2, IGF-Ⅱ, c-myc and their possible roles in the carcinogenesis of PHC are discussed.
文摘Human c-myc cDNA was fused with the hormonebinding domain (HBD) cDNA of murine estrogen receptorgene and the chimeric gene was introduced into the CHOcells. The fusion protein, c-MycER, becomes activatedwhen the synthetic steroid, 4-hydroxy-tamoxifen (OHT),binds HBD. Activated c-MycER, likely c-Myc, can inducequiescent CHO cells reentry into S phase and subsequentcell death under serum-free condition. In addition, theexpression of some proposed c-myc target genes such asODC, MrDb, cad, rcc1 and rc1 were found to increase uponOHT induction before S, phase entry and apoptosis, indicating that these target genes are involved in cell cycleregulation and/or apoptosis control. However, the mutantD106-143c-MycER protein does not have above activities.
文摘In a total of 83 UN specimens were investigated for proto-oncogene mutations, tumor supressor genes promoter methylation status and c-myc and Ki-67 expression. Point mutations in c-myc were detected in cases with high grade and proliferation index. Mutated K-ras proto-onco- gene profiles were detected in 17 (21%) tumoral spiecemens that examined. Tumor specimens were also showed hypermethylated promoter domain for the SFRP2, MGMT tumor supressor genes. These findings showed the combine effect of mutated c-myc and K-ras oncogene and epigenetic inactivation of tissue specific tumor supressor genes (TS) play a crucial role in tumor progression and recurrence in UN carcinogenesis.
文摘The human promyelocytic cell line HL-60 overexpresses the c-myc protooncogene. Plasmid pDACx carrying antisense human c-myc DNA and neo gene was introduced into HL-60 cells with lipofectin reagent. Upon DNA entering the tar-geted celis and expression of antisense transcripts to c-myc, C-MYC protein level, cell proliferation and colony-forming potentiality were all definitely inhibited.
基金Supported by In part by the 21st Century COE(Center Of Ex-cellence)Programs to Dr.Takenori Ochiaiby a Grant-in-Aid 18591453 to K.M from the Ministry of Education,Science,Sports and Culture of Japan
文摘AIM: To investigate a novel therapeutic strategy to target and suppress c-myc in human cancers using far up stream element (FUSE)-binding protein-interacting repressor (FIR).
文摘The neonate is particularly susceptible to the development of hypoxic pulmonary hypertension. The present study was undertaken to observe the effect of hypoxia on DNA synthesis and c-myc gene expression between newborn calf and adult bovine PASMC in vilro. DNA synthesis measured by 3H- TdR incorporation was increased after hypoxic challenge for 24h. Hypoxia enhanced the increment in 3H-TdR incorporation induced by EGF. Northern blot analysis revealed that PASMC cultured in both normoxia and hypoxia expressed c- myc gene transcript of 2. 2Kb ,but there is a higher 2. 2Kb mRNA expression in hypoxic PASMC than that in normoxia. We speculate that newborn calf PASMC exhibited potential response to hypoxia than adult,which was augmented by EGF. Enhanced c-myc gene expression may lead to a great understanding of the mechanism of PASMC growth in the development of pulmonary hypertension.
文摘The recombinant plasmid PGC was constructed for transcription unit of c-myc gene with diorientation in vitro, to make RNA probes for detection of c-myc mRNA and antisence RNA expression of tranfectant HL-9,which was obtained from HL60 cells transfected with inducible c-myc antisense RNA expression plasmid. The results from HL-9 cells induced by Cd2+ indicated that expression of c-myc antisense RNA increased with Cd2+ concentration and exposure time, while c-myc mRNA expression progressively reduced. Using immunohistochemical technique no c-myc P62 protein expression was detected. The incorporation of 3H-TdR, 3H-UR and 3H-Leu revealed significant suppression of DNA, RNA and protein biosynthesis. It is suggested that the reversion changes previously reported in malignant Phenotypes of HL-9 cells and the inhibition of macromolecular biosynthesis mentioned above were associated with the blockade of c-myc gene expression by its antisense RNA.
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.
基金Supported by grants from the Young Scientific and Technical InnovationFoundation of Fujian Province (No. 2004J067).
文摘Objective: To explore the inhibition of the expression of c-Myc in human hepatocellular carcinoma via vector-based RNA interference (RNAi). Methods: Two RNA interference DNA templates targeting c-Myc oncogene were designed via online software and synthesized. By ligation, the fragments were inserted into pSilencer 1.0-U6 to construct the recombinant siRNA expressing plasmids. The identified recombinants were introduced into BEL-7402 cells with Lipofactamine. The inhibition of c-Myc expression, together with the expression of CDK4, hTERT and Gadd45β in c-Myc down-regulated BEL-7402 cells, were analyzed by semi-quantitative RT-PCR. Results: Two recombinant plasmids pSic-myc-1 and pSic-myc-2, which direct the yields of siRNAs targeting c-Myc in cells, were constructed. Among which, pSic-myc-2 was shown to trigger a RNAi-mediated inhibition of expression of c-Myc in BEL-7402 by up to 90%. In c-Myc knockdown BEL-7402 cells, the expression of CDK4 and hTERT were down-regulated with a ratio of 85% and 57%, respectively, while the expression of Gadd45β was up-regulated by up to 110%. Conclusion: The expression of c-Myc in BEL-7402 could be suppressed by vector-based RNA interference successfully. The knockdown of c-Myc in turn resulted in the changes of expression of genes related to cell proliferation and apoptosis. Thus, our study provided a preliminary data in searching of a c-Myc-targeted RNAi therapy of human hepatocellular carcinoma.
基金The project was supported by National Natural Science Foundation of China(NAFC)
文摘Retinoblastoma (Rb) is the most common malignant'cancer of eye.So-Rb_(50) is the first Rb cell line established in China in 1988.It has passed to the 387th passage now.We collected cells of the 327th passage of SO-Rb_(50),purified its genomic DNA and detected it with Rb and c-myc cDNA probes respectively(normal human white blood cells DNA was the control).We found the Rb gene was deleted while c-myc gene was amplified three times.This provides a basis for further study of the regulation of tumor development and tumor reversal with this cell line in vitro.Eye Science 1993;9:34-37.
文摘Objectives To investigate the c myc gene expression in nasopharyngeal carcinoma (NPC) at mRNA and protein levels, and to evaluate the relationship between the degree of expression and the clinicopathological data. Methods The expression of c myc specific mRNA and protein was detected using in situ hybridization with digoxigenin labeled probe and immunohistochemistry in 12 cases of normal nasopharyngeal epithelium (NE) and 48 cases of NPC. The intensity of staining for each sample was assessed as negative, weak, moderate and intense. Statistical analyses were performed using the Chi square test and the rank sum test. Results For normal NE, 41.7% (5/12) had weak (4/12) or moderate (1/12) staining for c myc protein and 41.7% (5/12) had weak staining for c myc mRNA. In contrast, 89.6% (43/48) of NPC showed some degree of c myc protein positive and 87.5% (42/48) showed some degree of c myc mRNA positive. In most samples, the expression of c myc protein was consistent with that of c myc mRNA. C myc protein and mRNA expression levels in NPC were significantly higher than those in normal NE, and correlated with early recurrence, but they were not significantly related to patient′s age, sex, EBVCA IgA titre, disease stage, lymph node status and metastasis. Conclusions C myc gene over expression may be involved in the pathogenesis and early recurrence of NPC. Further studies are needed to substantiate the preliminary findings.
文摘Objective To investigate the expression of human telomerase catalytic subunit,hTERT, in human non-small cell lung cancer (NSCLC) and its correlations to c-myc gene.Methods hTERT and c-myc mRNA expressions were detected by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Statistical correlation analysis was made to estimate whether there was interrelation between them.Results Positive rate of hTERT expression in 51 surgically resected lung cancer specimens was 86.3%,significantly higher than that in adjacent non-neoplastic lung tissues and benign lesions,which were 14.3% and 27.3% respectively. No statistical significance was observed between the frequency of hTERT expression and histologic types,degree of differentiation,TNM stages,tumor size or lymph nodes metastases. Correlation analysis revealed that the expression of c-myc gene was significantly related to that of hTERT (correlation coefficient,r =0.633,P <0.001).Conclusions hTERT may be a useful tumor marker in diagnosing lung cancer. Significant correlation between the expression of hTERT and c-myc mRNA indicates that the activation and up-regulation of hTERT might be conferred by over-expression of c-myc gene.
基金Project supported by the National Natural Science Foundation of China.
文摘One of the important advancements in DNA repair research is the demonstration of preferential repair of transcriptionally active DNA in UV-irradiation cells. Experiment results have shown that repair in specific sequence in and around
文摘A human esophageal cancer cell line (EC8712) expressing high-level Myc protein was infected with recombmant retroviral particles (pA-BD9) at a multiplicity of infection (MOI) 1:1. This viral particle contains a neomycin-resistant gene and a 1.53-kb antisense RNA spanning the 2nd exon and its flanking sequences of the human c-myc oncogene. The G418-resistant EC8712 clones showed an 86% inhibition of growth rate and morphological changes characteristic of terminal differentiation and apoptosis. A decrease of about 80% of Myc protein was also observed in these infected cells by ABC-ELISA assay. 12-24 h after the infection of ECS712 cells with pA-BD9 at a high viral particle concentration (MOI = 1:10), the integration of the extrinsic 1.53-kb antisense c-myc fragment into the cancer cell genome was evidenced by the Southern blot analysis. Northern blot analyses showed the expression of this antisense fragment and a decrease of the intrinsic c-myc expression by 74% in comparison with that of the parental EC8712 cells. Heterotransplants of the infected EC8712 cells into the nude mice revealed a substantial decrease in tumorigemcity and morphological changes characteristic of terminal differentiation and apoptosis. Primary monolayer cell cultures of normal epithelia derived from the fetal and adult esophagus mucosa were set as controls. No noticeable increase in c-myc expression was found in these cultures Infection of these cells with the same recombinant viral particles neither affected the growth rate of the cells nor their normal morphology. Our experiments indicate that the drastic decrease of the over-expressed Myc protein in cancer cells may also be an entrance to one of many pathways leading to the terminal differentiation and programmed cell death.
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.
文摘USING electron microscope, cytochemical and biochemical techniques we found that parts ofpolysomes, some mRNAs, several initiation factors and the elongation factor 2 are bound tocytoskeleton. This means that the cytoskeleton may also play a role in gene expression.The c-jun, c-fos and c-myc proteins are transcription factors, which play an important role inthe regulation of progression from Go to S phase. The disruption of the microfilaments(MF) by cytochalasin D(CD) in HeLa cells results in the inhanced transcription of the
