Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43146 (tumour suppressor)
 5,935 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

H-ras-transformed NIH3T3 cells that overexpressed a human melanoma-associated antigen ME491 (44-3H) were generated by transfection with the cloned ME491 antigen gene followed by a 'panning' selection, and effects of the antigen overexpression on H-ras-mediated malignant phenotypes were studied. Although in vitro growth properties of the 44-3H overexpresser cells, both anchorage-dependent and -independent, were practically the same as those of the 44-1C control cells, 44-3H cells exhibited less malignant phenotypes in athymic nude mice (in vivo), i.e. decreased tumourigenicity after subcutaneous inoculation and prolonged survival time after intraperitoneal inoculation, compared with 44-1C cells. These results suggested that overexpression of ME491 antigen partially suppressed malignant phenotypes of H-ras-transformed NIH3T3 cells in athymic nude mice through co-operating with a factor(s) or mechanism(s) that exist in vivo but not in vitro. Thus, ME491 antigen might act as a tumour suppressor under some circumstances.
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PMID:Overexpression of the human melanoma-associated antigen ME491 partially suppresses in vivo malignant phenotypes of H-ras-transformed NIH3T3 cells in athymic nude mice. 182 25

The growth of human prostate cancer and its relationship to the surrounding stroma are controlled by complex mechanisms that are incompletely understood. Clearly, peptide growth factors appear to have crucial roles in these processes. One of these factors, TGF-beta, and its family members are notable for their wide spectrum of biological effects. In terms of growth, TGF-beta inhibits the growth of prostate cancer cells in a cytostatic fashion while stimulating the growth of critical stromal cells, such as fibroblasts. Since the inhibitory effects of TGF-beta on prostate cancer cells appear to diminish as the process of transformation progresses towards less differentiated states, the net effect on prostate tumour growth may be positive. Recent evidence suggests that the inhibitory effects of TGF-beta on growth, at least, might be mediated through the RB tumour suppressor gene product and the proto-oncogene c-myc. Beyond its direct growth effects, TGF-beta also alters the response of prostate cancer cells to positive mitogenic factors, such as members of the EGF and FGF families, suggesting that growth control is a delicate balance between positive and negative influences. Non-mitogenic responses to TGF-beta by prostate cancer cells, the immune system, the stroma and the vascular system provide evidence that TGF-beta might also be important in the processes of carcinogenesis, tumour establishment and metastases. In addition, TGF-beta appears to influence metabolic pathways important to drug metabolism and steroidogenesis. In vivo, limited evidence suggests that TGF-beta can alter the growth and differentiation of some tumour types but appears to be very toxic when administered in high doses. A better understanding of the response of prostate cancer cells to members of the TGF-beta family may open new avenues of treating and controlling this disease.
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PMID:Response of prostate cancer cells to peptide growth factors: transforming growth factor-beta. 184 49

We have detected allelic loss in a majority of prostate cancers analysed. These losses have been detected on several chromosomes known to harbour tumour suppressor genes important in the development of other tumour types. Elevated rates of loss of heterozygosity on chromosome 16q and 10q suggest that tumour suppressor genes important in the pathogenesis of prostate cancer may be present on these chromosomes. Conversely, determination of the frequency of ras gene mutations in prostate cancer tissue suggests that these genetic alterations play a minor part in both the initiation and progression of this disease in humans.
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PMID:Genetic changes associated with prostate cancer in humans. 184 50

Studies of multistage carcinogenesis in mouse skin have provided many of the early concepts of tumour initiation, promotion and progression. Genetic approaches have led to the identification of a number of mutational alterations in proto-oncogenes and tumour suppressor genes which take place at specific stages of carcinogenesis in this particular system. Initiation involves, at least in a proportion of tumours, mutational activation of the cellular H-ras proto-oncogene. Trisomy of chromosome 7, which develops during the premalignant clonal expansion phase, possibly as a consequence of tumour promoter treatment, is followed by further alterations on chromosome 7 which lead to a relative increase in the expression of mutant ras alleles. The p53 tumour suppressor gene undergoes mutational alteration and loss of heterozygosity in a proportion of squamous carcinomas but this particular gene does not appear to be involved in the further transition of squamous carcinomas to highly undifferentiated spindle cell tumours. The latter transition appears to be a recessive event which can be complemented by fusion with cells at earlier stages of malignancy. Mouse skin carcinogenesis therefore continues to provide invaluable information on the nature of the genetic and biological transitions which occur during the step-wise progression of normal cells to malignancy.
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PMID:Functional loss of tumour suppressor genes in multistage chemical carcinogenesis. 184 54

Recent studies have suggested the existence of a tumor suppressor gene located at chromosome region 5q21. DNA probes from this region were used to study a panel of sporadic colorectal carcinomas. One of these probes, cosmid 5.71, detected a somatically rearranged restriction fragment in the DNA from a single tumor. Further analysis of the 5.71 cosmid revealed two regions that were highly conserved in rodent DNA. These sequences were used to identify a gene, MCC (mutated in colorectal cancer), which encodes an 829-amino acid protein with a short region of similarity to the G protein-coupled m3 muscarinic acetylcholine receptor. The rearrangement in the tumor disrupted the coding region of the MCC gene. Moreover, two colorectal tumors were found with somatically acquired point mutations in MCC that resulted in amino acid substitutions. MCC is thus a candidate for the putative colorectal tumor suppressor gene located at 5q21. Further studies will be required to determine whether the gene is mutated in other sporadic tumors or in the germ line of patients with an inherited predisposition to colonic tumorigenesis.
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PMID:Identification of a gene located at chromosome 5q21 that is mutated in colorectal cancers. 184 68

Wild-type p53 protein has many properties consistent with its being the product of a tumour suppressor gene. Although the normal roles of tumour suppressor genes are still largely unknown, it seems that they could be involved in promoting cell differentiation as well as in mediating growth arrest by growth-inhibitory cytokines. Hence, the abrogation of wild-type p53 expression, which is a common feature of many tumours, could eliminate these activities. We have now tested this notion by restoring the expression of p53 in a murine myeloid leukaemic cell line that normally lacks p53. The use of a temperature-sensitive p53 mutant allowed us to analyse cells in which the introduced p53 had either wild-type or mutant properties. Although there seemed to be no effect on differentiation, the introduction of wild-type p53 resulted in rapid loss of cell viability in a way characteristic of apoptosis (programmed cell death). The effect of wild-type p53 was counteracted by interleukin-6. Thus products of tumour suppressor genes could be involved in restricting precursor cell populations by mediating apoptosis.
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PMID:Wild-type p53 induces apoptosis of myeloid leukaemic cells that is inhibited by interleukin-6. 185 10

Six families of activated protooncogenes, ras, raf, fur, neu, jun and myc have so far been associated with human lung cancer. Human bronchial epithelial cells in vitro are being used to investigate the functional role of these specific oncogenes and growth regulatory genes in carcinogenesis and tumour progression. When transferred into normal human bronchial epithelial cells by the highly efficient protoplast fusion method, the v-Ha-ras oncogene initiates a cascade of events leading to decreased responsiveness of these cells to inducers of squamous differentiation, aneuploidy and, less frequently, 'immortality' and tumorigenicity with metastasis in athymic nude mice. Transfection of the SV40 T antigen gene results in nontumorigenic cell lines that have a nearly normal pathway of terminal squamous differentiation and can be transformed into malignant cells by transfected Ha-ras, N-ras or Ki-ras. The combination of transfected c-myc and c-raf-1 also transforms human bronchial epithelial cells into neoplastic cells that exhibit some phenotypic traits found in small-cell carcinomas. These and other results indicate that proto-oncogenes dysregulate the pathways of growth and differentiation of human bronchial epithelial cells and play an important role in human carcinogenesis. Analyses of allelic deletion and somatic cell hybrids are being used to identify the chromosomal localization of tumour suppressor genes. We have examined 54 non-small-cell bronchogenic carcinomas with 13 polymorphic markers. Loss of heterozygosity was more frequent than among 23 squamous-cell carcinomas than among 23 adenocarcinomas or eight large-cell carcinomas. Loss of heterozygosity for chromosome 17p was found in 89% of cases of squamous-cell carcinoma and 18% of adenocarcinomas. Analysis of chromosome 11 for allelic deletions revealed two commonly deleted regions (11p13 and 11p15.5). Somatic cell hybrids between normal human bronchial epithelial cells and Hut292DM, a lung carcinoma cell line, had a finite lifespan in vitro and were nontumorigenic in athymic nude mice. Tumour suppressive effects of individual or combinations of specific human chromosomes on Hut292DM are being examined by formation of microcell-cell hybrids. Chromosome 11 has tumour suppressor activity in these hybrids. Both of these studies suggest that tumour suppressor genes play a dominant role in lung carcinogenesis and provide in-vitro model systems for isolating these genes by subtraction library and insertional mutagenesis techniques.
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PMID:Role of oncogenes and tumour suppressor genes in human lung carcinogenesis. 185 68

Oncogenesis results from an accumulation of genetic mutations in a single cell. Mutations may result in the cell acquiring new functions or losing specific functions required for normal growth control. Evidence for the latter may be adduced from the results of fusing tumour and normal cells to form somatic cell hybrids, and from studies of allele loss in a number of human tumours. The locations the critical genes have been discerned in some cancer predisposition syndromes either by observations of consistent cytogenetic abnormalities, or by genetic linkage studies, or both. Genes whose inactivation is important in the genesis of retinoblastoma, Wilms' tumour and colorectal cancer have been identified and cloned. Their normal functions include control of transcription and cell-cell interactions. In the case of retinoblastoma, the interaction between the normal gene product and that of the transforming genes of a number of oncogenic DNA viruses has been delineated. Identification of 'tumour suppressor' genes has not only improved understanding of the process of oncogenesis, but may also aid in the presymptomatic detection of mutant gene carriers.
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PMID:Recessive oncogenes, antioncogenes and tumour suppression. 186 44

Cancer can be considered a genetic disorder of somatic cells. Strong evidence comes from several areas: (1) chromosomal analysis reveals cancer cells have abnormal karyotypes; (2) some inherited syndromes are associated with an increased risk of cancer and for others, cancer itself occurs as an inherited trait; (3) cells can become malignant by a variety of agents that damage DNA, and (4) some types of viruses can induce tumours. One common thread has been the normal cellular sequences transduced by viruses and mutated to become oncogenic (oncogenes) are the same sequences to become activated by nonviral mechanisms. These oncogenes appear involved in cell proliferation and/or differentiation and their products apparently function in the signal transduction pathway from the cell exterior to the nucleus. In addition, evidence from familial studies indicate mutations associated with gene inactivation or loss of function are also important in the aetiology of tumour formation. These genes, termed tumour suppressor genes, seem to be involved in the negative control of cellular proliferation. Cancer is a multistep process and it is now becoming clear that the different stages involve genetic alterations in both oncogenes and tumour suppressor genes.
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PMID:Genes and cancer. 186 49

The rapid advance in our understanding of cancer biology during the past decade, as exemplified by the discovery of oncogenes and tumour suppressor genes and their interactions in tumourigenesis, has revolutionized cancer research. This rapid progress has largely been due to the use of molecular genetics techniques. However, despite the wealth of available information as to the genetic basis of carcinogenesis, its clinical applicability remains limited. The review is a summary of the general principles and methods currently used to detect genetic alterations in neoplastic cells, with special emphasis on clinical applications.
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PMID:[Molecular genetics methods discovering the mechanisms of neoplasm etiology]. 188 Dec 16


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