Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cyclin-dependent kinase 4 (cdk4) inhibitor (p16INK4/MTS1/CDKN2) gene has been recently identified as a putative tumor suppressor gene because of the high frequency of homozygous deletion observed in numerous human tumor cell lines, including leukemias. However, results obtained from uncultured tumor samples have led to discussion of the relevance of these findings. Using reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot analysis, we have investigated p16INK4A gene at both RNA and genomic levels in various types of leukemias: acute myeloid leukemia (AML) (n = 23); acute lymphocytic leukemia (ALL) (n = 22) and B cell chronic lymphoproliferative disorders (CLPD) (n = 33). p16INK4A mRNA expression was not found in only 1/20 AML and 2/23 CLPD samples. Conversely, p16INK4A mRNA was not detected in 5/17 ALL cases, and intensity of PCR products were barely detectable in seven additional cases, possibly related to the contamination by normal cells in some cases. By Southern blotting, a homozygous deletion of p16INK4A gene was found in 6/17 ALL cases (35%) among which 4/6 were negative or weakly positive by RT-PCR assay. None of the five AML and 20 CLL samples studied had p16INK4A deletion. Sequence analysis of p16INK4A exon 2 did not show point mutation in two of these cases lacking mRNA expression. Our data provide further evidence that among hematological malignancies, ALL are the most likely to be associated with p16INK4A inactivation, mainly by homozygous gene deletion. Since most hematological malignancies-except ALL-are infrequently associated with p16INK4A and retinoblastoma (Rb) gene alteration it seems worthwhile to explore cdk4 and cdk6 expression to determine whether or not the disruption of the p16INK4A/Rb/cdk4/cdk6 regulatory loop might play a role in their pathogenesis.
Leukemia 1995 Jul
PMID:Alterations of cyclin-dependent kinase 4 inhibitor (p16INK4A/MTS1) gene structure and expression in acute lymphoblastic leukemias. 763 Jan 99

A recently described putative tumor suppressor gene, the cyclin-dependent kinase 4 inhibitor (p16), has been shown to be altered by deletions and/or point mutations in various human cancers. To assess the incidence and clinico-biologic correlations of p16 homozygous deletion in hemopoietic tumors, we studied a panel of 244 DNA samples representative of distinct acute (99 cases) and chronic (57 cases) leukemia subtypes, myelodysplastic (22 cases) and myeloproliferative (15 cases) syndromes, and lymphomas (51 cases). A 361-bp probe complementary to the p16 exon 2 gene sequences was generated by polymerase chain reaction and used in Southern blot hybridization against these tumor DNAs. Homozygous deletions of p16 (p16-/-) were detected in 10 of 58 (17%) cases of acute lymphoblastic leukemia (ALL) of either B or T lineage and in no other tumors. Single-strand conformation polymorphism analysis of p16 exons 1 and 2 was also performed in 40 of the 58 ALL cases and in 16 lymphomas. In no cases were point mutations detected. The comparison of clinical features at presentation in p16-/- and in p16 germline ALL cases showed a greater leukemic cell mass (P = .001) and higher white blood cell counts (P = .01) in the former group. Two ALL cases in which diagnostic and relapse DNA samples were available showed p16-/- in both specimens. We conclude that homozygous p16 gene deletions characterize a subset of ALL with features of aggressive disease.
 ...
PMID:Detection of homozygous deletions of the cyclin-dependent kinase 4 inhibitor (p16) gene in acute lymphoblastic leukemia and association with adverse prognostic features. 774 27

The putative tumor suppressor gene deleted in colorectal carcinoma (DCC), located on human chromosome band 18q21, is deleted or inactivated in many solid tumors. Its role in the pathogenesis of non-Hodgkin's lymphoma (NHL) has not been studied. Recently, inactivation of this gene was reported in cases of leukemia with monosomy 18. As monosomy 18 is frequently observed in low-grade NHL, we investigated the incidence of altered DCC gene expression in patients with NHL, and correlated it with the number of copies of chromosome 18. Fifteen unselected cases of NHL were studied for evidence of DCC gene expression by reverse transcriptase-polymerase chain reaction. The results were correlated with Southern blot analysis of the DCC gene and with the number of copies of chromosome 18 determined by fluorescent in situ hybridization (FISH). The controls were tissues from normal colon mucosa and normal tonsils. Eight of 15 (53%) NHL cases lacked DCC mRNA, and one expressed substantially less than normal. Southern blot analysis showed normal configuration of the DCC gene in all samples. Two copies of chromosome 18 were found in 9 of 11 samples studied by FISH: one case had a subpopulation of cells with monosomy 18 and one had trisomy 18. All controls expressed DCC. We conclude that DCC gene expression is frequently absent or decreased in NHL and may be involved in the pathogenesis of NHL. Monosomy 18 was not required for DCC inactivation.
 ...
PMID:Decreased expression of the deleted in colorectal carcinoma gene in non-Hodgkin's lymphoma. 774 42

Two general types of clonal chromosome abnormality are observed in de novo acute myeloid leukemia (AML): the unbalanced aberrations with visible gain or loss of chromosome material and the balanced aberrations without such visible gain or loss. AML can be induced by therapy with cytostatic drugs and radiation. The alkylating agents reacting directly with DNA induce AML which often presents as myelodysplasia with unbalanced aberrations, primarily loss of chromosome material. Cytostatic agents targeting DNA-topoisomerase II, frequently administered together with alkylating agents or cisplatin, induce the same type of leukemia. In addition, they often induce another type with a more rapid onset and with specific balanced chromosome aberrations rarely observed after therapy with alkylating agents alone. All of the most important chromosome aberrations found in de novo AML are now also found in therapy-related AML (t-AML); thus, t-AML may serve as a model in the search for mechanisms leading to the development of AML in general. Unbalanced chromosome aberrations with partial deletions or with loss of whole chromosomes may develop as a result of alkylation of DNA or other cellular targets. Balanced chromosome aberrations, on the other hand, may develop as illegitimate recombinations related to the activity of DNA-topoisomerase II. The balanced translocations contribute to malignant transformation by the formation of abnormal chimeric genes, whereas deletions may contribute by the loss of putative tumor suppressor genes. In either situation, the chromosome changes provide the altered cells with a proliferative advantage compared with normal cells.
 ...
PMID:The balanced and the unbalanced chromosome aberrations of acute myeloid leukemia may develop in different ways and may contribute differently to malignant transformation. 818 Mar 74

Ninety-five percent of radiation-induced murine myeloid leukemias contain chromosome 2 aberrations. A dominant molecular defect has not yet been identified: both deletions and breakpoint-specific events have been postulated. We have generated a model in which chromosome 2 lesions have been generated in vitro in a clonal tumor cell line. In this study cytogenetic and molecular comparisons are made between two of these in vitro generated lesions and eight derived in vivo: seven by the conventional radiation protocol, and one by infection with Moloney leukemia virus. All 10 lines consistently exhibited hemizygous loss of an 18 cM region between Hoxd-4 and II-1 alpha, with variable breakpoints at both ends. These results are consistent with deletion of a gene in common rather than breakpoint-specific events, for lesions resulting from all three protocols. This will allow a novel approach to the identification of a putative tumor suppressor gene, ie to describe the biological effect of the in vitro generated deletion, and to clone the gene by complementation. In preparation for this approach, we have further narrowed the region to approximately 6.5 cM by microsatellite mapping of 22 radiation-induced F1 tumors. In addition, we have eliminated the possibility that imprinting ablates expression from the remaining undeleted chromosome.
Leukemia 1995 Dec
PMID:Gene deletion explains both in vivo and in vitro generated chromosome 2 aberrations associated with murine myeloid leukemia. 860 10

Chromosome band 9p21-22 is one of the most common targets for deletions in cancer. The p16 tumor suppressor gene maps to this region and is inactivated in a wide variety of tumor cell lines and primary tumors. However, in some of the neoplasms with frequent 9p21 loss of heterozygosity (LOH), a structurally and functionally normal p16 is found suggesting that this gene might not be the primary or only target for inactivation. To define the smallest region of overlap of deletions at chromosome band 9p21-22 and to clarify the involvement of p16, p15 and the IFN cluster gene in lymphoblastic leukemias, we used a multiplex polymerase chain reaction to construct a detailed map of deletions at 9p21-22. We studied DNA from 30 lymphoblastic leukemia patients and nine cell lines using 10 genes/markers that map to this region, including four STS markers located between p16 and D9S171 (STS1, STS2) or between p16 and IFNalpha (STS3, STS4). We found that the size of the deletions in this region is variable and that the commonly deleted region spans at least 400 kb; it includes the p16 gene but excludes the IFN gene cluster and the p15 gene. The identification of this commonly deleted region enables a more focused search for other putative tumor suppressor gene at 9p21 which could be relevant to leukemogenesis.
Leukemia 1997 Feb
PMID:The commonly deleted region at 9p21-22 in lymphoblastic leukemias spans at least 400 kb and includes p16 but not p15 or the IFN gene cluster. 900 86

Acute lymphoblastic leukemia (ALL) is the most frequent cancer encountered in children. Little is known about the molecular pathology of childhood T cell ALL. Oncogenesis is a multistep process that involves alterations in proto-oncogenes and tumor suppressor genes. Recently, a mutator phenotype detectable by microsatellite instabilities was shown to be associated with predisposition to cancer. This new mechanism for human carcinogenesis is caused by defects in the DNA replication/repair system. To study the involvement of some of these mutational events in the development of T cell ALL, we have initiated a systematic search for losses of heterozygosity (LOH) and microsatellite instabilities in children affected with this disease. These patients were allelotyped by PCR using 56 microsatellite markers located near known or putative tumor suppressor genes. The microsatellite patterns were altered in more than 80% of the patients. LOH were detected in chromosomes 6p, 12p and 9p. Two third of the patients were deleted for chromosome 9p21, suggesting the involvement of a tumor suppressor gene, probably the p16 gene. The only patient refractory to chemotherapy was shown to be associated with a mutator phenotype. This is the first documented case of a childhood neoplasia associated with genomic instabilities. Our results suggest that defects in DNA replication/repair components are involved in the development of a subset of childhood T cell ALL.
Leukemia 1997 Jun
PMID:Microsatellite instability in childhood T cell acute lymphoblastic leukemia. 917 30

We have characterized the cDNA of MZFM, the mouse homolog to the novel human putative tumor suppressor gene ZFM1. The total length of the cDNA is 2,637 nucleotides with an open reading frame for a protein of 548 amino acids containing 4.7% methionine and 17.2% proline. The predicted molecular mass of 59 kD fits the 62-kD band experimentally determined by NaDodSO4-PAGE from in vitro translation products of in vitro-transcribed MZFM cDNA. The MZFM cDNA best matches to that ZFM1-isoform without the so-called 0.25-kb E-domain and to the L49345 cDNA recently identified in a human leukemia cell line. Northern analysis reveals expression of MZFM only in spleen macrophages. Reverse transcription polymerase chain reaction (RT-PCR) in combination with Southern analysis also detects a low basal expression in splenic T cells and B cells, as well as in other tissues such as heart, kidney, brain, liver, testis, bone marrow, adrenal gland, lymph nodes, pancreas, and thymus. In splenic macrophages, MZFM mRNA is alternatively spliced yielding a 3.6-kb transcript with E-domain, a 3.0-kb transcript without E-domain, and a 2.7-kb transcript with E-domain. The predicted MZFM protein contains diverse functional domains, i.e., a nuclear localization signal, a metal binding motif, a glutamine/proline stretch, proline-clusters, a CGA-motif, and a QUA1-KH-QUA2 region, thus indicating multiple functions of MZFM. Presumably, MZFM is a new member of those proteins combining features of signal transduction and RNA activation (STAR-proteins). The different MZFM-isoforms may be part of a macrophage-inherent program of transduction of environmental signals into different activational states of macrophages.
 ...
PMID:Enhanced expression in spleen macrophages of the mouse homolog to the human putative tumor suppressor gene ZFM1. 921 69

Previous studies have indicated the presence of a putative tumor suppressor gene on chromosome 13q14, commonly deleted in patients with B-cell chronic lymphocytic leukemia (B-CLL). We have previously defined a minimally deleted region of 130 kb centromeric to the marker D13S272, and constructed a PAC and cosmid contig encompassing this area. In the present study we have made a detailed restriction and transcriptional map of the region of interest. Using these tools we have screened a panel of 206 primary CLL clones and three cell lines. In five CLL cases we found limited deletions defining the region of interest to an area of no more than 10 kb. Two adjacent genes, termed Leu1 and Leu2 (leukemia-associated gene 1 and 2), were mapped to the minimally deleted region, with several patients showing deletion borders within these genes. The Leu1 and Leu2 genes show little homology to previously published genes at the nucleotide and expected translated amino acid sequence level. Mutational analysis of the Leu1 and 2 genes in 170 CLL samples revealed no small intragenic mutations or point mutations. However, in all cases of 13q14 loss examined, the first exon of both genes, which are only 300 bp apart, were deleted. We conclude that the Leu1 and Leu2 genes are strong candidates as tumor suppressor gene(s) involved in B-CLL leukemogenesis.
 ...
PMID:Cloning of two candidate tumor suppressor genes within a 10 kb region on chromosome 13q14, frequently deleted in chronic lymphocytic leukemia. 939 42

p16 and p15 genes are putative tumor suppressor genes located on chromosome 9p21. In acute leukemias, alterations of p16 and p15 genes have been reported to occur exclusively in lymphoid lineage. We analyzed alterations of p16 and p15 genes in 46 acute leukemias with MLL gene rearrangements by Southern blot analysis, and investigated the association with clinical characteristics. We identified homozygous deletion of p16 and p15 genes in five (19%) of 27 acute lymphoblastic leukemias (ALLs) and in two (11%) of 19 acute myeloid leukemias (AMLs). Patients with homozygous deletion of p16 and p15 genes showed higher average leukocyte counts (343 x 10(9)/l vs 271 x 10(9)/l) and lower estimated 2-year survival rates than those with normal p16 and p15 genes (14.3 vs 30.7%), although the differences were not statistically significant. In addition, we investigated mutation of p16 gene by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) in 31 patients, but no mutation was found in the patients tested. Our results suggest that alterations of p16 and p15 genes are involved in a subset of acute leukemias with MLL gene rearrangement not only of lymphoid but also of myeloid phenotype. Homozygous deletion of p16 and p15 genes may be a possible adverse prognostic factor, although further analysis would be needed to confirm it.
Leukemia 1997 Dec
PMID:Alterations of p16 and p15 genes in acute leukemia with MLL gene rearrangements and their correlation with clinical features. 944 29


1 2 3 4 Next >>