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Biochimica Et Biophysica Acta Jan 1995A variant of human prostate PC3 cells, isolated from PC3 cells, was shown to be significantly resistant (> 10-fold) to several clinically active anticancer drugs,...
A variant of human prostate PC3 cells, isolated from PC3 cells, was shown to be significantly resistant (> 10-fold) to several clinically active anticancer drugs, including VP-16 and cisplatin. Previous studies showed that resistance to these drugs was not due to expression of the mdr1 gene, or modifications in topoisomerases but may have resulted from high expressions of certain proto-oncogenes (Yamazaki et al. (1994) Biochim. Biophys. Acta 1226, 89-96). Flow cytometry, DNA gel electrophoresis and northern blot analysis were used to further characterize drug responses in sensitive and resistant cells. Treatment of the sensitive PC3 cells with VP-16 and CDDP resulted in accumulation of cells in S and G2, and G1 and S phases, respectively, and caused significant degradation of the genomic DNA into internucleosomal sized DNA fragments, indicating apoptosis. In contrast, resistant PC3 cells showed little or no DNA fragmentation. Resistant PC3(R) cells expressed 2-3-fold more bcl2 protein than the parental PC3 cells, and overexpressed c-myc, c-jun and H-ras mRNA compared to sensitive cells. Treatment with VP-16 or CDDP significantly induced c-myc mRNA levels in sensitive PC3 cells. H-ras message was not affected by either VP-16 or CDDP treatment in PC3 cells. These studies, taken together, suggest that a differential susceptibility to apoptosis and chemosensitivity may be related to altered levels of bcl2 and/or oncogene overexpression in PC3(R) cells.
Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cisplatin; Drug Resistance; Etoposide; Gene Expression Regulation; Humans; Male; Prostatic Neoplasms; Proto-Oncogene Mas; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogenes; Tumor Cells, Cultured
PubMed: 7827130
DOI: 10.1016/0925-4439(94)00065-x -
British Journal of Cancer Mar 1991
Comparative Study Review
Topics: Adult; Aged; Biomarkers, Tumor; Breast Neoplasms; Gene Expression; Humans; Middle Aged; Neoplasm Staging; Prognosis; Proto-Oncogene Proteins; Proto-Oncogenes; Receptor, ErbB-2
PubMed: 1672251
DOI: 10.1038/bjc.1991.78 -
The American Journal of Pathology Dec 1995We investigated the possible role of RET proto-oncogene mutations in the development of sporadic hyperplastic, benign, and malignant parathyroid lesions. DNA extracted...
We investigated the possible role of RET proto-oncogene mutations in the development of sporadic hyperplastic, benign, and malignant parathyroid lesions. DNA extracted from paraffin-embedded specimens of forty parathyroid lesions was screened for RET proto-oncogene point mutations in exons 10, 11, and 16 by nonisotopic polymerase chain reaction-based single-strand conformation polymorphism and heteroduplex gel electrophoresis. The nucleotide sequence of samples with aberrant band patterns was identified by nonisotopic direct sequencing of polymerase chain reaction-amplified DNA. Parathyroids of seven patients with multiple endocrine neoplasia type 2A (MEN 2A) and MEN 2B served as positive controls. None of the eight hyperplastic lesions, three cases of parathyromatosis, ten parathyroid adenomas, eleven carcinomas or one normal parathyroid gland contained mutations in each of the three RET exons tested. Six MEN-2A-associated hyperplastic glands exhibited identical band shifts in the polymerase chain reaction single-strand conformation polymorphism analysis of exon 11, which corresponded to a Cys 634-->Arg substitution in the nucleotide sequence analysis (TGC-->CGC), whereas in the MEN 2B parathyroid specimen a point mutation was found at codon 918 of exon 16 (ATG-->ACG), causing a Met 918-->Thr substitution. Our data indicate that RET mutations of the MEN 2 loci in exons 10, 11, and 16 are not involved in the development of sporadically occurring benign or malignant parathyroid lesions. Furthermore, our results are in accordance with the observation that MEN 2A patients with Cys 634-->Arg (germline) mutations have a higher risk of developing parathyroid disease than those with other mutations at codon 634.
Topics: Adenoma; Base Sequence; Carcinoma; Drosophila Proteins; Humans; Hyperplasia; Molecular Sequence Data; Multiple Endocrine Neoplasia Type 2a; Nucleic Acid Heteroduplexes; Parathyroid Glands; Parathyroid Neoplasms; Point Mutation; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Proto-Oncogene Mas; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-ret; Proto-Oncogenes; Receptor Protein-Tyrosine Kinases
PubMed: 7495285
DOI: No ID Found -
Molecular and Cellular Biology Oct 1985Morphologic transformation of NIH 3T3 mouse cells occurs upon transfection of these cells with large amounts (greater than or equal to 10 micrograms) of recombinant DNA...
Morphologic transformation of NIH 3T3 mouse cells occurs upon transfection of these cells with large amounts (greater than or equal to 10 micrograms) of recombinant DNA molecules carrying the normal human H-ras-1 proto-oncogene. We provide experimental evidence indicating that transformation of these NIH 3T3 cells results from the combined effect of multiple copies of the H-ras-1 proto-oncogene rather than from spontaneous mutation of one of the transfected H-ras-1 clones (E. Santos, E.P. Reddy, S. Pulciani, R.J. Feldman, and M. Barbacid, Proc. Natl. Acad. Sci. USA 80:4679-4683, 1983). Levels of H-ras-1 RNA and p21 expression are highly elevated in the NIH 3T3 transformants, and in those cases examined, these levels correlate with the malignant properties of these cells. We have also investigated the presence of amplified ras genes in a variety of human carcinomas. In 75 tumor biopsies, we found amplification of the human K-ras-2 locus in one carcinoma of the lung. These results indicate that ras gene amplification is an alternative pathway by which ras genes may participate in the development of human neoplasia.
Topics: Animals; Cell Transformation, Neoplastic; Cell Transformation, Viral; Cloning, Molecular; Gene Amplification; Gene Expression Regulation; Humans; Mice; Neoplasms; Neoplasms, Experimental; Protein Biosynthesis; Proto-Oncogene Mas; Proto-Oncogene Proteins; Proto-Oncogenes; Transcription, Genetic
PubMed: 3915535
DOI: 10.1128/mcb.5.10.2836-2841.1985 -
Biophysical Journal Apr 2020Alternative splicing is a key step in eukaryotic gene expression that allows for the production of multiple transcript and protein isoforms from the same gene. Even...
Alternative splicing is a key step in eukaryotic gene expression that allows for the production of multiple transcript and protein isoforms from the same gene. Even though splicing is perturbed in many diseases, we currently lack insights into regulatory mechanisms promoting its precision and efficiency. We analyze high-throughput mutagenesis data obtained for an alternatively spliced exon in the proto-oncogene RON and determine the functional units that control this splicing event. Using mathematical modeling of distinct splicing mechanisms, we show that alternative splicing is based in RON on a so-called "exon definition" mechanism. Here, the recognition of the adjacent exons by the spliceosome is required for removal of an intron. We use our model to analyze the differences between the exon and intron definition scenarios and find that exon definition prevents the accumulation of deleterious, partially spliced retention products during alternative splicing regulation. Furthermore, it modularizes splicing control, as multiple regulatory inputs are integrated into a common net input, irrespective of the location and nature of the corresponding cis-regulatory elements in the pre-messenger RNA. Our analysis suggests that exon definition promotes robust and reliable splicing outcomes in RON splicing.
Topics: Alternative Splicing; Exons; Introns; Proto-Oncogenes
PubMed: 32336349
DOI: 10.1016/j.bpj.2020.02.022 -
Blood Dec 1991The myc proto-oncogenes encode nuclear phosphoproteins, which are believed to participate in the control of cell proliferation and differentiation. Deregulated...
The myc proto-oncogenes encode nuclear phosphoproteins, which are believed to participate in the control of cell proliferation and differentiation. Deregulated expression of c-myc has been implicated in several human hematopoietic malignancies. We have studied the expression and mRNA processing of human L-myc, N-myc, and c-myc genes in a panel of human leukemias, leukemia cell lines, and normal hematopoietic cells. L-myc mRNA was expressed in three acute myeloid leukemias (AML) studied and in several myeloid leukemia cell lines. Only low expression levels were observed in adult bone marrow and in fetal spleen and thymus. The K562 and Dami leukemia cell lines showed a unique pattern of L-myc mRNA processing, with approximately 40% of L-myc mRNA lacking exon III and intron I. N-myc was expressed in five of six AML cases studied, in one of nine acute lymphocytic leukemia (ALL) cases, and in several leukemia cell lines, while c-myc mRNA was detected in all leukemias and leukemia cell lines studied. Coexpression of all three myc genes was observed in Dami and MOLT-4 cell lines and in two AMLs, and either L-myc or N-myc was coexpressed with c-myc in several other cases. These results show that in addition to c-myc, the L-myc and N-myc genes are expressed in some human leukemias and leukemia cell lines, and suggest a lack of mutually exclusive cross-regulation of the myc genes in human leukemia cells.
Topics: Blotting, Northern; Gene Expression; Genes, Retinoblastoma; Genes, myc; Humans; Leukemia; Molecular Weight; Proto-Oncogene Proteins c-myc; Proto-Oncogenes; RNA Splicing; RNA, Messenger; RNA, Neoplasm; Tumor Cells, Cultured
PubMed: 1954386
DOI: No ID Found -
Oncology (Williston Park, N.Y.) Jul 1998Among patients with congenital and acquired immunodeficiencies, non-Hodgkin's lymphoma (NHLs ) are the most common tumors of the immune system. In the setting of human... (Review)
Review
Among patients with congenital and acquired immunodeficiencies, non-Hodgkin's lymphoma (NHLs ) are the most common tumors of the immune system. In the setting of human immunodeficiency virus (HIV) infection, as many as 10% to 20% of people ultimately developed NHLs. These tumors are clinically aggressive, frequently involve extranodal sites, and often exhibit unique features that distinguish them from NHL arising in individuals with other forms of immunosuppression. Important in the development of HIV-associated NHL are cytokines and other factors that induce B-cell proliferation and increase the likelihood of mutations of c-myc, bcl-6, and other tumor-suppressor genes with carcinogenic potential. Specific forms of HIV-associated NHL are linked to expression of Epstein-Barr virus (EBV)-latent proteins; the newly described DNA virus, Karposi's sarcoma-associated herpesvirus/human herpesvirus-8 (KSHV/HHV-8); and perhaps HIV. Elucidation of the factors that contribute to the high incidence of NHL among patients infected with HIV provides insights into important elements of lymphomagenesis.
Topics: B-Lymphocytes; Cell Division; Cytokines; DNA-Binding Proteins; Gene Expression Regulation, Neoplastic; Gene Expression Regulation, Viral; Genes, Tumor Suppressor; Genes, myc; HIV; Herpesvirus 4, Human; Herpesvirus 8, Human; Humans; Immunocompromised Host; Lymphoma, AIDS-Related; Lymphoma, Non-Hodgkin; Mutation; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-6; Proto-Oncogenes; Transcription Factors; Viral Proteins; Zinc Fingers
PubMed: 9684278
DOI: No ID Found -
World Journal of Gastroenterology Sep 2003To investigate the effects of DNA methylation on the expression of tumor suppressor genes and proto-oncogene in human colon cancer cell lines.
AIM
To investigate the effects of DNA methylation on the expression of tumor suppressor genes and proto-oncogene in human colon cancer cell lines.
METHODS
Three colon cancer cell lines (HT-29, SW1116 and Colo-320) treated with different concentrations of DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC) were used to induce DNA demethylation. The expressions of p16(INK4A), p21(WAF1), APC and c-myc genes were observed by using RT-PCR. The methylation status of p16(INK4A) promoter in HT-29 cells was also determined by methylation-specific PCR (MSP).
RESULTS
Weak expressions of p16(INK4A) and APC in the three colon cancer cells were detected, and p21(WAF1) expression was not found in SW1116 and Colo-320 cells before treatment. After treatment of 1 micromol/L but not 10 micromol/L of 5-aza-dC, the methylation level of p16(INK4A) gene promoter decreased significantly, and the hypomethylation led to the up-regulation of p16(INK4A) gene transcription in HT-29 cells. In the cell lines of SW1116 and Colo-320, p16(INK4A) and APC mRNA expressions were obviously enhanced after treatment of either 10 micromol/L or 5 micromol/L 5-aza-dC for 24 h. However, no evidence was found that methylation regulated the expression of p21(WAF1) and c-myc genes in human colon cancer cell lines.
CONCLUSION
Expression of p16(INK4A) and APC genes is regulated by DNA methylation in three human colon cancer cell lines.
Topics: Colonic Neoplasms; DNA Methylation; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Humans; Proto-Oncogene Mas; Proto-Oncogenes; Tumor Cells, Cultured
PubMed: 12970888
DOI: 10.3748/wjg.v9.i9.1976 -
Immunology Mar 1990Phorbol ester-induced differentiation of human B-chronic lymphocytic leukaemic cells was found to be preceded by a rapid transient induction in expression of the c-jun...
Phorbol ester-induced differentiation of human B-chronic lymphocytic leukaemic cells was found to be preceded by a rapid transient induction in expression of the c-jun proto-oncogene, which paralleled that of c-fos. Induced expression of c-myc but not of c-fos/c-jun proto-oncogenes was markedly higher in a proliferating variant leukaemic cell population compared with that seen in typical lymphocytic leukaemia cells. These data suggest that the c-fos/c-jun nuclear oncogenes play a role in induced differentiation, whilst c-myc is more important in the proliferative response of B lymphocytes.
Topics: B-Lymphocytes; Gene Expression; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphocyte Activation; Proto-Oncogene Mas; Proto-Oncogenes; Tumor Cells, Cultured
PubMed: 2312171
DOI: No ID Found -
Journal of Virology Nov 1999We previously showed that B16 melanoma cells produce ecotropic melanoma-associated retrovirus (MelARV) which encodes a melanoma-associated antigen recognized by MM2-9B6...
We previously showed that B16 melanoma cells produce ecotropic melanoma-associated retrovirus (MelARV) which encodes a melanoma-associated antigen recognized by MM2-9B6 monoclonal antibody. The biological significance of MelARV in melanoma formation remains unknown. We found that infection of normal melanocytes with MelARV resulted in malignant transformation. It is likely that MelARV emerged from the defective Emv-2 provirus, a single copy of ecotropic provirus existing in the genome of C57BL/6 mice. In the present study, we cloned and sequenced the full-length MelARV genome and its insertion sites and we completed sequencing of the Emv-2 provirus. Our data show that MelARV has a typical full-length retroviral genome with high homology (98.54%) to Emv-2, indicating a close relationship between both viruses. MelARV probably emerged as a result of recombination between Emv-2 and an endogenous nonecotropic provirus. Some observed differences in the gag and pol regions of MelARV might account for the restoration of productivity and infectivity of a novel retrovirus that somatically emerged during melanoma formation. MelARV does not contain any oncogene and therefore might induce transformation by insertional mutagenesis. We sequenced two insertion sites of MelARV. The first insertion site represents the 3' coding region of the c-maf proto-oncogene at 67.0 centimorgans (cM) on chromosome 8. The c-maf proto-oncogene encodes a basic leucine zipper protein homologous to c-fos and c-jun. Insertion of MelARV in BL6 melanoma cells resulted in the up-regulation of c-maf. It is noteworthy that the Emv-2 provirus is also inserted into a noncoding region at 61.0 cM on the same chromosome 8. The second insertion site is the 3' noncoding region of the DNA polymerase gamma (PolG) gene on chromosome 7. The expression of PolG was not affected by the MelARV insertion. Further investigation of the biological significance of MelARV in melanoma formation is being undertaken.
Topics: Animals; Base Sequence; Blotting, Northern; Cloning, Molecular; DNA Polymerase gamma; DNA-Binding Proteins; DNA-Directed DNA Polymerase; Gammaretrovirus; Genome, Viral; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Mutagenesis, Insertional; Plasmids; Polymerase Chain Reaction; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-maf; Proto-Oncogenes; Proviruses; RNA, Viral; Sequence Analysis, DNA; Tumor Cells, Cultured; Virus Integration
PubMed: 10516025
DOI: 10.1128/JVI.73.11.9178-9186.1999