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G F Saunders

Publications and source records attributed to G F Saunders.

At least 91 records · Page 5Linked to original sources
PubMed1988

Alteration and abnormal expression of the c-myc oncogene in human multiple myeloma.

Structural alterations of the c-myc oncogene in human Burkitt's lymphoma and mouse plasmacytoma suggest that this oncogene is involved in several B cell neoplasms. The possibility of c-myc alterations in human myeloma has not been explored, probably because the low proliferative activity characteristic of this tumor impairs the propagation of representative cell lines for the performance of adequate cytogenetic studies. This report describes alterations in the c-myc locus with concomitant elevated expression of mRNA in the tumor cells of two of 37 patients with multiple myeloma. In one case, somatic cell hybrid studies revealed that the cloned rearranged DNA was entirely derived from chromosome 8, thus indicating a novel mechanism of c-myc activation different from that in Burkitt's lymphoma. Seven other patients exhibited five- to 12-fold overexpression of c-myc RNA when compared with normal marrow cells. Elevated mRNA expression in about one fourth of our patients suggests that the c-myc oncogene has a pathogenetic role in the evolution of multiple myeloma.

Animals↗
PubMed1988

A myeloid-related sequence that localizes to human chromosome 8q21.1-22.

A myeloid-related sequence (mrs) has previously been identified that is highly expressed in selected subpopulations of myeloid leukocytes. Nucleotide sequence analysis indicates that mrs encodes what is apparently a unique 93-amino acid protein that includes an 18-amino acid leader sequence. Hybridization of an mrs cDNA probe to a Southern blot made from somatic cell hybrid DNAs shows 100% concordance with human chromosome 8, thus indicating that mrs localizes to this chromosome. In situ hybridization to metaphase chromosomes further sublocalizes mrs to bands 8q21.1-23 as 58% of the grains displayed on chromosome 8 were clustered in this region. This area encompasses the translocation breakpoint 8q22, which is rearranged in an estimated 18% of patients diagnosed with the M2 subclassification of acute nonlymphocytic leukemia (M2-ANLL). When Southern blot hybridization was performed by using somatic cell hybrid DNAs harboring either a single 8q- or a single 21q+ chromosome from two different patients with M2-ANLL, a signal was only detected in the hybrid containing the 8q-chromosome.

Amino Acid Sequence↗
PubMed1987

Differential expression of the human thymosin-beta 4 gene in lymphocytes, macrophages, and granulocytes.

A cDNA clone encoding human thymosin-beta 4 was isolated from a cDNA library prepared from peripheral blood leukocytes of a patient with acute lymphocytic leukemia. This clone contained the entire coding sequence of 43 amino acid residues of thymosin-beta 4 and had an initiation codon and two termination codons. The amino acid and nucleotide sequences in the coding region were well conserved between rat and human. Nine of 132 nucleotides were different in the coding sequences (93% homology), but the deduced amino acid sequences were identical. No signal peptide was found in the deduced protein sequence. Human thymosin-beta 4 mRNA, approximately 830 nucleotides in length, was about 30 nucleotides larger than rat thymosin-beta 4 mRNA. Expression of the human thymosin-beta 4 gene in various primary myeloid and lymphoid malignant cells and in a few human hemopoietic cell lines was studied. Northern blot analyses of different neoplastic B lymphocytes revealed that steady state levels of thymosin-beta 4 mRNA varied as a function of differentiation stage. Thymosin-beta 4 mRNA levels were decreased in myeloma cells as are class II human leukocyte antigen, Fc receptor, and complement receptor, suggesting a relationship between thymosin-beta 4 and the immune response. Thymosin-beta 4 mRNA was more highly expressed in mature granulocytes than in immature blastic cells. Treatment of THP-1 cells, a human monocytic cell line, with recombinant human interferon-lambda reduced the levels of thymosin-beta 4 mRNA. Its level decreased after differentiation of THP-1 cells into Ia+ macrophages, but increased after differentiation of HL-60 cells into Ia- macrophages. The pattern of thymosin-beta 4 gene expression suggests that it may play a fundamental role in the host defense mechanism.

Amino Acid Sequence↗
PubMed1987

HLA class II antigen associated invariant chain gene expression in malignant lymphoma.

Expression of the gene encoding HLA class II antigen-associated invariant chain was studied in several types of fresh human malignant lymphoma by Northern blot analysis or slot-blot analysis. The invariant chain mRNA levels decreased with the stage of B-lymphocyte differentiation to plasma cells such as in immunoblastic lymphoma (IBL) or multiple myeloma (MM). The invariant chain gene (In-gene) was expressed in diffuse large cell lymphoma (DLCL), while its expression was hardly detected in IBL. It is suggested that the difference in In-gene expression between DLCL and IBL could be useful in distinguishing these two morphologically similar diseases.

Genes, MHC Class II↗
PubMed1987

Localization of the human catalase and apolipoprotein A-I genes to chromosome 11.

Studies of the catalase and apolipoprotein A-I genes are pertinent to the understanding of human disease. Not only are these genes involved in acatalasemia and atherosclerosis, respectively, but they are also important gene markers for chromosome 11, deletions of which are involved in the development of Wilms tumor. We have used in situ hybridization to localize these genes to specific bands on chromosome 11. Hybridization with a catalase cDNA yielded a significant number of cells (38%) exhibiting label at band 11p13. A high percentage of metaphase cells (50%) hybridized with a human genomic fragment containing the gene for apolipoprotein A-I displayed labeling at 11q13.

Apolipoprotein A-I↗
PubMed1987

Localization of an abundant myeloid-related sequence.

Differential screening of a CML-derived cDNA library was used to isolate a cDNA clone representing an abundant mRNA in leukocytes of chronic phase, chronic myelogenous leukemia (CML) patients. This myeloid-related sequence (mrs) comprises approximately 2% of the chronic phase, CML mRNA. Hybridization of the radiolabeled cDNA to the cellular RNAs of intact, morphologically distinguishable, primary hematopoietic cells indicates that the primary cells producing mrs RNA are eosinophils (Eo), basophils (Baso), promyelocytes (Pro) and myelocytes (Mye). In the neutrophilic series, the abundance of mrs RNA decreases as the cells mature. The mrs RNA potentially encodes a 93 amino acid protein that has not been previously described. It has been localized to chromosome 8, region 8q21.1-23.

Base Sequence↗
PubMed1987

Nonrandom loss of maternal chromosome 11 alleles in Wilms tumors.

A series of gene probes for chromosome 11 has been used to study the genetic events associated with the development of Wilms tumor. Examination of DNA samples from five patients with Wilms tumor in whom the tumors showed loss of chromosome 11 alleles and their parents indicate that alleles lost in the tumors are of maternal origin. These data suggest that the parental derivation of chromosome 11 alleles lost in these Wilms tumors is not random.

Alleles↗
PubMed1987

Genetic mechanisms of tumor-specific loss of 11p DNA sequences in Wilms tumor.

Wilms tumor, a common childhood renal tumor, occurs in both a heritable and a nonheritable form. The heritable form may occasionally be attributed to a chromosome deletion at 11p13, and tumors from patients with normal constitutional chromosomes often show deletion or rearrangement of 11p13. It has been suggested that a germinal or somatic mutation may occur on one chromosome 11 and predispose to Wilms tumor and that a subsequent somatic genetic event on the normal homologue at 11p13 may permit tumor development. To study the frequency and mechanism of such tumor-specific genetic events, we have examined the karyotype and chromosome 11 genotype of normal and tumor tissues from 13 childhood renal tumor patients with different histologic tumor types and associated clinical conditions. Tumors of eight of the 12 Wilms tumor patients, including all viable tumors examined directly, show molecular evidence of loss of 11p DNA sequences by somatic recombination (four cases), chromosome loss (two cases), and recombination (two cases) or chromosome loss and duplication. One malignant rhabdoid tumor in a patient heterozygous for multiple 11p markers did not show any tumor-specific 11p alteration. These findings confirm the critical role of 11p sequences in Wilms tumor development and reveal that mitotic recombination may be the most frequent mechanism by which tumors develop.

Child↗
PubMed1987

HLA-associated invariant chain gene expression in human B cell neoplasia.

The expression of the gene encoding the HLA-DR associated invariant chain (In-gene) in human B lymphocytes was analyzed by determining the level of invariant chain, mRNA in peripheral blood and bone marrow cells of several patients affected by hematological malignancies. In B cell neoplasms representative of different stages of B lymphocyte differentiation, In-gene activation was an early event that may occur in pre-B cells before immunoglobulin gene transcripts are detectable. The highest level of invariant chain mRNA were observed at an intermediate maturation stage corresponding to sIg, Ia, and B1 positive peripheral blood lymphocytes. At the terminal stage of B lymphocyte differentiation, the In-gene was turned off. In leukemic cell populations, the pattern of temporal activation of the In-gene corresponded to the pattern of activation of the genes encoding the HLA-DR alpha and beta chain.

Antigens, Differentiation↗
PubMed1987

Localization of an abundant myeloid mRNA to individual leukocytes in mixed cell populations.

Differential screening of cDNA libraries with radiolabeled RNAs isolated from various sources provides a convenient way to identify cDNA clones representing RNAs that are more (or less) abundant in selected tissues. This strategy was previously used to isolate cDNA clones representing poly(A+)RNAs (mRNA) that are abundant in leukocytes from chronic myelogenous leukemia (CML) patients. One limitation with the initial experiments was that the RNAs were isolated from heterogenous cell populations and it was impossible to distinguish whether all of the cells were producing the abundant mRNAs or if a subset of the cell population was responsible for the majority of the RNA species. To resolve this important issue, we have directly hybridized radiolabeled cDNAs to the cellular RNAs of intact, morphologically distinguishable, primary hematopoietic cells. In the present study clone pC-A3, which represents an mRNA species that is abundant in the chronic phase of CML, was used to examine three samples from normal bone marrow, one sample from normal peripheral blood, and four samples from peripheral blood of leukemic patients (one Ph1 + AL, two CML in compensated phase, and one CML in accelerated phase). The results show that while C-A3 gene expression is detectable in cells from the granulocytic, monocytic, and lymphoid lineage, its relative abundance peaks at the level of the neutrophilic myelocytes and promyelocytes. Earlier myeloid precursors like myeloblasts or mature neutrophilic granulocytes show less labeling. Further, all maturation stages of eosinophils (Eos) and basophil (Baso) are highly labeled. This finding reinforces recent evidence that Eos and Baso share a common progenitor and suggests that these two cell types may have a stronger role than previously noted in the prominent myeloproliferative response that is characteristic of CML.

Basophils↗
PubMed1986

Transcriptional enhancer within the human placental lactogen and growth hormone multigene cluster.

Human placental lactogen (hPL) and human growth hormone (hGH) are members of a multigene family that share amino acid sequence homology and similarity in gene structure and nucleotide sequence, but differ in both function and expression. To determine the sequence requirements for tissue specific expression recombinant plasmids containing the members of the hPL-hGH multigene family and flanking regions were analyzed by both transient and stable transfection assays. We have identified a transcriptional enhancer in a 1.0 kb region located 2.0 kb downstream of the hPL3 structural gene. This enhancer sequence is not strictly cell-type specific since it functions in cell lines of both placental (JEG-3) and pituitary (18-54,SF) origin. However, its efficiency is several fold higher in placental cells than in pituitary cells.

Base Sequence↗
PubMed1986

Structure of the human glucagon gene.

A clone containing the complete human glucagon gene was isolated and sequenced. The gene is approximately 9.4 kilobases in length and comprises six exons and five introns. The putative preproglucagon encoded by this gene, 180 amino acids in length and containing glucagon and two glucagon-like peptides, is very similar to that of other mammalian species (greater than 90% amino acid sequence homology). There is 88% nucleotide sequence homology between the proximal 130 base pairs of the 5' flanking regions of the human and rat glucagon genes. These sequences, highly conserved throughout evolution, are likely involved in the regulation of glucagon gene transcription.

Base Sequence↗
PubMed1986

HLA-DR-associated invariant chain is highly expressed in chronic lymphocytic leukemia.

Total RNA extracted from peripheral blood lymphocytes of a patient with B-cell chronic lymphocytic leukemia (CLL) and the poly (A+) RNA was purified. A cDNA library was constructed and approximately 4,000 clones were screened in order to identify genes preferentially expressed in CLL. A relatively low repetition frequency characterizes the majority of the abundant mRNA species present in CLL lymphocytes. One clone, corresponding to the mRNA encoding the HLA-DR-associated invariant chain, was selected and its expression was examined in different leukemic cell populations and in normal tissues. DNA-RNA hybridization studies showed that the invariant chain mRNA (In-mRNA) is detectable in RNA preparations from human blood cells and their precursors, whereas no In-mRNA is found in several other tissues examined. Among various normal and leukemic leukocyte populations, the highest levels of In-mRNA are found in CLL. Therefore, a role of In-chain mRNA as a marker of CLL is proposed. Our data support a relationship between high levels of invariant chain mRNA and the out of cycle condition of CLL peripheral blood lymphocytes.

Clone Cells↗
PubMed1985

Structure of the human gene encoding the invariant gamma-chain of class II histocompatibility antigens.

The primary structures of a cDNA and the genomic DNA of a gene selectively expressed in chronic lymphocytic leukemia were determined. A computer search of the nucleotide sequence data bank identified this gene as the invariant gamma-chain associated with class II histocompatibility antigens. The invariant gamma-chain genomic sequence spans about 11 kilobases, with eight exons and seven introns. Three of the introns contain members of the Alu repeat family. A putative cap site and promoter sequence were identified at the 5' end of the gene. One or two copies of the gene is present in each haploid genome, and no evidence for amplification or polymorphism was obtained.

Base Sequence↗
PubMed1985

Recent amplification of an alpha satellite DNA in humans.

A repeat sequence 682 base pairs (bp) long produced by cleavage of human DNA with Xba I restriction enzyme is composed of four tandemly arranged subunits with lengths of 171, 170, 171, and 170 bp each. The sequence organization of the 682 bp Xba I repeat bears a striking resemblance to other complex satellite DNAs of primates, including the Eco RI human alpha satellite family which also occurs as a 170 bp repeat. The Eco RI tetramer and the 682 bp Xba I repeat show a sequence divergence of 21%. The 682 bp Xba I repeat sequence is restricted to humans and is only distantly related to the previously reported 340 bp Xba human repeated DNA sequence. These finding are consistent with the concept of occasional amplifications of members or groups of members of alpha satellite DNA during human evolution. Amplifications apparently occurred after humans, apes and gibbons diverged from Old World monkeys (Eco RI satellite), after humans and apes diverged from gibbons (340 bp Xba I satellite) and after humans diverged from the great apes (682 bp Xba I satellite).

Animals↗
PubMed1985

Preferentially expressed genes in chronic myelogenous leukemia.

The predominant circulating cells in chronic myelogenous leukemia (CML) morphologically resemble normal myeloid precursors; however, certain characteristics indicate the two are not identical. Approximately 88% of the patients with clinically typical CML present with a cytogenetic abnormality known as the Philadelphia chromosome (Ph1). Additionally, the leukocyte alkaline phosphatase (LAP) value is decreased in CML. To investigate if there are selected genes expressed in the CML cell population, poly(A+)RNA from a chronic-phase, Ph1-positive CML patient was used for construction of a complementary DNA (cDNA) library. Recombinant clones representing moderately to abundantly transcribed sequences were selected by annealing [32P]-cDNA transcribed from homologous RNA to the library sequences and assessing radioactivity in the hybrids. From an initial 729 colonies, 417 (57.2%) displayed a hybridization signal more intense than controls, indicating these recombinant plasmids contained sequences homologous to moderately or highly expressed RNAs from this particular patient. Screening of the 417 clones--utilizing 32P-cDNAs derived from normal human placenta, an acute myelomonocytic leukemia (AMML), and two other CML samples--was used to select clones likely to represent sequences preferentially expressed in CML. Sixteen recombinants were initially selected that repeatedly failed to display hybridization with the placenta and AMML-derived probes. Further analysis of eight of these clones indicated that six contain sequences preferentially expressed in CML. One clone, C-A3, has been studied with 63 different RNA samples. This sequence is found to be highly expressed in peripheral blood cells from the chronic phase of both Ph1-positive and Ph1-negative CML as well as in a Ph1-positive acute myelogenous leukemia (AML). Expression is reduced in lymphoblastic crisis of CML (L BC-CML) and essentially absent in myeloblastic crisis of CML (M BC-CML). While preliminary, the results suggest that this probe may be useful as an aid in diagnosing Ph1-negative CML and in distinguishing M BC-CML from L BC-CML and Ph1-positive AML.

Adolescent↗