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S J Collins

Publications and source records attributed to S J Collins.

At least 73 records · Page 4Linked to original sources
PubMed1991

A retinoic acid-responsive human zinc finger gene, MZF-1, preferentially expressed in myeloid cells.

Zinc finger genes encode metal-binding proteins that can act as transcriptional regulators of other genes. In an effort to identify activators of the genetic cascade in hemopoietic differentiation, we used degenerate synthetic oligonucleotides to the conserved zinc finger histidine-cysteine link to probe a human myeloid lambda gt11 cDNA library. One of the cDNA clones obtained hybridized preferentially to mRNA from myeloid cells. This cDNA was used to isolate clones encompassing the coding region for this gene. Sequence analysis found 13 zinc finger regions and a glycine-proline-rich region between the fourth and fifth zinc finger domain. The gene was localized to chromosome 19q13.2-4, a chromosome that has a large cluster of zinc finger genes. The gene was preferentially expressed in myeloid leukemia cell lines with the highest mRNA levels noted in HL-60 cells induced to differentiate with retinoic acid. Thus, this new zinc finger gene (designated MZF-1) may be one regulator of transcriptional events during hemopoietic development.

Amino Acid Sequence↗
PubMed1991

Retinoic acid receptors in myeloid leukemia: characterization of receptors in retinoic acid-resistant K-562 cells.

Although mRNA for the retinoic acid receptor alpha (RAR-alpha) is expressed in many different myeloid leukemias, most of these leukemia cells exhibit little if any phenotypic response when exposed to retinoic acid (RA). To determine whether such RA resistance is related to altered RA receptor structure or function, we performed a detailed analysis of nuclear RA receptors in RA-resistant K-562 cells. These cells exhibit RA receptors of the same approximate molecular weight and similar kd as those exhibited by the RA-sensitive HL-60 leukemia cell line, but the number of RA receptors in the RA-resistant K-562 cells (80 per cell) is significantly lower than that exhibited by RA-sensitive HL-60 cells (550 per cell). Retroviral-mediated transduction of RAR-alpha cDNA into K-562 significantly increased the number of RA receptors to 2,000 per cell. These RAR-alpha-transduced K-562 cells, when incubated with RA, exhibit diminished cell proliferation associated with decreased c-myc expression and an accumulation of cells in G0/G1. In addition, these RA-treated cells exhibit downregulation of the CD15 surface antigen and a slight increase in hemoglobin production but manifest no other evidence of significant erythroid, megakaryocytic, or myeloid differentiation. These results indicate that an elevated number of nuclear RA receptors can be involved in altering proliferation but not necessarily the differentiation of certain RA-treated myeloid leukemia cells.

Antigens, CD↗
PubMed1990

Absence of the c-Ha-ras codon 61 point mutation in murine solid tumors induced by subcutaneously applied 7,12-dimethylbenzanthracene.

The c-Ha-ras-1 codon 61 A----T transversion is a highly consistent finding in murine skin DMBA-initiated/TPA-promoted papillomas and carcinomas. We performed Xba I RFLP analysis on DNA from clonal cell lines derived from 11 independent papillomas and a single carcinoma derived from topically applied DMBA and compared this to RFLP on DNA from 7 clonal fibrosarcoma cell lines derived from tumors arising after subcutaneous administration of the same carcinogen. The A----T point mutation was present in all of the papillomas and carcinoma derived by the classic DMBA-TPA protocol but was absent in all of the fibrosarcomas arising after subcutaneous administration of DMBA.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Retroviral-mediated gene transfer of the leukocyte integrin CD18 subunit.

Children with leukocyte adherence deficiency (LAD) exhibit heterogeneous defects in the leukocyte integrin CD18 subunit that prevent surface expression of functional CD11/CD18 leukocyte integrin adherence complexes. We used a retroviral vector, designated LCD18SN, to transfer the CD18 cDNA into K562 human myeloid leukemia cells and into EBV B-cells from a child with LAD. Transfer of the LCD18SN retroviral construct, which expresses the CD18 cDNA from the Moloney Murine leukemia virus (MoMLV) long terminal repeat (LTR), into K562 cells resulted in relatively high levels of CD18 mRNA and intracellular protein. Retroviral-mediated gene transfer of CD18 into LAD EBV B-cells resulted in low, but readily measurable, levels of surface expression of the CD11a/CD18 complex in these previously deficient lymphocytes. The reconstitution of surface expression of the CD11a/CD18 complex by gene transfer of the CD18 cDNA into LAD EBV B-cells indicates that this syndrome represents a candidate disorder for gene therapy.

Antigens, CD↗
PubMed1990

N-ras mutations in adult de novo acute myelogenous leukemia: prevalence and clinical significance.

Point mutations of the N-ras proto-oncogenes have been previously detected in 20% to 60% of samples of acute myelogenous leukemia (AML), but the clinical significance of these mutations is presently unclear. We directly sequenced polymerase chain reaction (PCR) amplified N-ras fragments to determine the frequency of N-ras point mutations in 55 adult patients with de novo AML. Mutations were present in 8 of 55 (15%) patients. These mutations were usually in codon 12, 13, or 61, but one patient had mutations in both codons 13 and 61, and another had an unusual point mutation in N-ras codon 60. A comparison of patients with and without N-ras mutations showed no statistically significant differences in pretreatment clinical variables, response to induction therapy, or survival, except for a possibly higher percentage of FAB M4 subtypes in patients with the N-ras mutation. These data together with previous reports suggest that the presence of N-ras point mutations do not clearly define a unique clinical or biologic subset of AML patients.

Adolescent↗
PubMed1990

Retinoic acid-induced granulocytic differentiation of HL-60 myeloid leukemia cells is mediated directly through the retinoic acid receptor (RAR-alpha).

Retinoic acid (RA) induces terminal granulocytic differentiation of the HL-60 promyelocytic leukemia cell line as well as certain other human myeloid leukemias. Specific RA receptors that are members of the steroid-thyroid hormone superfamily of nuclear transcription factors have recently been identified. We developed an HL-60 subclone that was relatively resistant to RA-induced differentiation. Specific nuclear RA receptors in this RA-resistant subclone had a decreased affinity for RA and exhibited a lower molecular weight compared with nuclear RA receptors from the RA-sensitive parental HL-60 cells. Retroviral vector-mediated transduction of a single copy of the RA receptor (RAR-alpha) into this RA-resistant HL-60 subclone restored the sensitivity of these cells to RA. These observations indicate that RAR-alpha plays a critical and central role in mediating RA-induced terminal differentiation of HL-60 leukemia cells.

CD18 Antigens↗
PubMed1989

Regulation of expression of the CD11b and CD18 subunits of the neutrophil adherence receptor during human myeloid differentiation.

The receptor on human myeloid cells that mediates cellular adherence consists of a heterodimer complex (designated CD11b/CD18). This receptor complex plays a critical role in leukocyte chemotaxis, adherence to vascular endothelium, and phagocytosis. We investigated expression of the CD11b subunit of this adherence receptor complex in various leukocyte populations. As previously described for the CD18 subunit, enhanced CD11b surface antigen and mRNA expression are present in peripheral blood granulocytes, as well as in chemically induced, differentiating HL-60 cells. However, in contrast to CD18 mRNA expression, which is transcriptionally regulated in differentiating HL-60 cells, the steady state levels of CD11b mRNA appear to be post-transcriptionally regulated in these cells. Thus, although the steady state levels of mRNA for the individual subunits of the CD11b/CD18 adherence receptor complex generally parallel each other during human myeloid differentiation, the mechanisms responsible for regulating these levels are distinctly different.

Antibodies, Monoclonal↗
PubMed1989

Rare occurrence of N-ras point mutations in Philadelphia chromosome positive chronic myeloid leukemia.

Point mutations of the N-ras oncogene are relatively common in acute myelogenous leukemia (AML) cells, occurring in some 25% to 50% of patient samples. We used a technique involving the direct nucleotide sequencing of in vitro amplified N-ras genomic fragments to determine the frequency of N-ras point mutations in chronic myeloid leukemia (CML) cells at various stages of the disease. This approach will detect N-ras point mutations in a mixed population of cells if the mutation is present in 25% or more of the cells. We could not demonstrate any point mutation at N-ras codons 12,13 or 59-63 in any of the 44 CML cases analyzed, which included 21 blast crisis samples. In contrast with AML N-ras point mutations are exceedingly rare in CML.

Gene Rearrangement↗
PubMed1988

Expression of the beta-subunit of the human leukocyte adherence receptor depends upon cell type and stage of differentiation.

Using a cDNA clone for the beta-subunit of the receptor on human leukocytes that mediates cellular adherence (CD18), we investigated the lineage specificity of beta-subunit mRNA expression in human hematopoietic cells. Relatively high levels of the beta-subunit mRNA transcript were detected in mature peripheral blood leukocytes, including granulocytes and both resting and PHA-activated T lymphocytes. In contrast, relatively low levels of this transcript were observed in EBV-transformed B cells, in the immature Jurkat T cell line, and in chronic myelogenous leukemia myeloblasts and lymphoblasts. The beta-transcript was undetectable in the K562 chronic myelogenous leukemia blast crisis cell line with erythroblastic characteristics and in cultured skin fibroblasts. Two acute myeloid leukemia samples displayed unusually high levels of this transcript, comparable to levels observed in mature PBL. beta-subunit mRNA expression appeared to be primarily confined to leukocytes. In all cells examined the levels of surface beta-Ag expression paralleled levels of beta-mRNA.

Antigens, Surface↗
PubMed1988

Transcriptional regulation of the leukocyte adherence protein beta subunit during human myeloid cell differentiation.

Adherence reactions involving human leukocytes are mediated by a family of glycoprotein surface antigens composed of three different alpha subunits designated alpha L, alpha M, and alpha X, each of which is associated with a single beta subunit in an alpha 1 beta 1 heterodimer structure. We cloned the cDNA for the common beta subunit and investigated beta subunit mRNA expression in HL-60 promyelocytic leukemia cells and human granulocytic cells. Leukocyte adherence receptor beta subunit mRNA transcripts were present in low levels in HL-60 myeloblasts and promyelocytes and increased 10-fold or greater with chemically induced differentiation to more mature granulocytes (using retinoic acid and dimethylformamide) or monocyte/macrophages (using phorbol myristate acetate). Levels of beta subunit mRNA expression were also increased both in normal human peripheral blood granulocytes and in granulocytes from patients with chronic myelogenous leukemia. Nuclear run-off assays indicated that the increased steady state level of the beta subunit mRNA in retinoic acid-differentiated HL-60 cells was secondary to enhanced beta subunit gene transcription. We conclude that mRNA levels for the beta subunit of the receptor on human leukocytes that mediates cellular adherence are increased in more mature granulocytic cells compared to immature myeloid precursors and that this enhanced mRNA expression is transcriptionally regulated.

CD18 Antigens↗
PubMed1988

Different mechanisms account for the relative resistance of KG-1 and HL-60 cell lines to retrovirus infection.

I infected three different human leukemic cell lines (K562, KG-1, and HL-60) with an amphotropic retrovirus vector (designated PA317/N2) which confers G418 resistance and contains the Moloney murine leukemia virus long terminal repeat. Compared with K562 cells, both KG-1 and HL-60 cells were relatively resistant to infection with this retrovirus vector. In HL-60 cells, this resistance appeared to result from diminished viral DNA synthesis, while in KG-1 cells there was a block to the genomic integration of the viral DNA.

Cell Line↗
PubMed1988

Retinoic acid-induced differentiation of retrovirus-infected HL-60 cells is associated with enhanced transcription from the viral long terminal repeat.

I infected different human leukemic cell lines with an amphotropic retrovirus vector (designated PA317/N2) which confers G418 resistance and contains the Moloney murine leukemia virus long terminal repeat. In retrovirus-infected G418-resistant HL-60 cells, induction of granulocyte differentiation by retinoic acid was invariably accompanied by a marked increase (5- to 10-fold) in the transcriptional activity of the integrated retroviral long terminal repeat.

Blotting, Northern↗
PubMed1988

Direct sequencing of amplified genomic fragments documents N-ras point mutations in myeloid leukemia.

A number of different techniques have been utilized to document point mutations in ras oncogenes in leukemic cells, but these approaches are either labor intensive, require relatively large numbers of leukemic cells or provide sequence data for only a limited number of codons. Here we describe a technique for documenting N-ras point mutations that involves the direct sequencing of N-ras genomic fragments that have been amplified in vitro utilizing the polymerase chain reaction (PCR). This technique permits the rapid analysis of a relatively large number of samples. Moreover this approach requires relatively small numbers of cells and provides direct nucleotide sequence information of multiple N-ras codons at a single reading.

Base Sequence↗
PubMed1987

Effect of recombinant alpha-interferon on the expression of the bcr-abl fusion gene in human chronic myelogenous human leukemia cell lines.

Recent investigations have shown a therapeutic and cytogenetic response in chronic myelogenous leukemia (CML) patients treated with recombinant alpha 2-interferon (IFN alpha 2). Philadelphia chromosome-positive (and many Ph1-negative) chronic myelogenous leukemia cells transcribe a novel bcr-abl fusion mRNA which may confer a growth advantage upon these cells. We investigated the effect of IFN alpha 2 on the levels of bcr-abl transcript expression in three Ph1-positive CML cell lines, EM2, KCL22, and K562. Although IFN alpha 2 inhibited cell proliferation in all three CML cell lines, IFN alpha 2 had no effect on the level of bcr-abl mRNA expression in any of the CML cell lines. In contrast, IFN alpha 2 increased the expression of class I HLA gene products. We conclude that while the bcr-abl fusion gene and its transcript undoubtedly play key roles in the pathogenesis of CML, the antiproliferative effect of IFN alpha 2 in CML cell lines relies upon genetic mechanisms other than modulation of bcr-abl expression.

Cell Division↗
PubMed1987

Bone marrow transplantation in a patient with myelodysplasia associated with diffuse eosinophilic fasciitis.

A 34-year-old man with diffuse eosinophilic fasciitis and a hypocellular myelodysplastic syndrome underwent marrow transplantation from an HLA-identical brother. Prompt hematopoietic reconstitution was observed, strongly suggesting that the marrow hypocellularity was caused by neither a serum inhibitory factor nor a microenvironmental disorder. The patient died of disseminated cytomegalovirus infection too early to evaluate the impact of hematopoietic reconstitution on the eosinophilic fasciitis. Nevertheless, marrow transplantation may offer a therapeutic option for those patients with this disorder who develop severe hematopoietic dysfunction and who have a suitable marrow donor.

Adult↗
PubMed1987

Heterogeneity in expression of the bcr-abl fusion transcript in CML blast crisis.

The 9;22 Philadelphia chromosome translocation in chronic myelogenous leukemia (CML) generates a bcr-abl fusion gene which codes for an aberrant 8-kb bcr-abl hybrid message. CML blast crisis cell lines display enhanced in vitro expression of this aberrant bcr-abl transcript when compared with fresh CML chronic phase cells. We directly compared in fresh patient samples the level of expression of the bcr-abl transcript in CML blast crisis versus chronic phase cells. All chronic phase patients displayed relatively low amounts of this aberrant transcript, while four of 10 blast crisis patients expressed this transcript at significantly higher levels. The remaining six blast crisis samples exhibited low levels of the aberrant transcript comparable to chronic phase cells. The two patients displaying the highest levels of the bcr-abl transcript did not harbor amplified copies of the bcr-abl fusion gene. This heterogeneity in the level of expression of the bcr-abl transcript in CML blast crisis indicates that enhanced expression of this aberrant transcript is not an absolutely necessary condition for blast transformation.

Adult↗
PubMed1987

Chronic myelogenous leukemia: amplification of a rearranged c-abl oncogene in both chronic phase and blast crisis.

The specific genetic events that distinguish the blast crisis from the chronic phase cells of chronic myelogenous leukemia (CML) are unknown. The most common karyotypic change that occurs as CML evolves from chronic phase to blast crisis is the development of multiple Philadelphia (Ph1) chromosomes, each of which is presumably harboring a translocated c-abl oncogene. We describe here a patient with CML who presented in lymphoid blast crisis with three Ph1 chromosomes/metaphase associated with an amplified, rearranged c-abl oncogene fragment and high levels of the aberrant 8-kilobase bcr-abl transcript. This rearranged c-abl fragment was amplified to a similar degree in both the patient's blast crisis cells and in his terminally differentiated granulocytes, but the level of the aberrant CML-specific bcr-abl transcript was some eight- to 16-fold higher in the blast crisis cells v the granulocytes. This analysis indicates that genomic amplification of a translocated c-abl oncogene, although perhaps important in the evolution of CML, nevertheless cannot, by itself, be the sole genetic event giving rise to blast crisis.

Adult↗