Showing papers by "Fred Hutchinson Cancer Research Center published in 1990"
TL;DR: It is proposed that HLH proteins lacking a basic region may negatively regulate other HLHprotein through the formation of nonfunctional heterodimeric complexes.
2,203 citations
TL;DR: Adjuvant therapy with levamisole and fluorouracil should be standard treatment for Stage C colon carcinoma, and this approach should be readily adaptable to conventional medical practice.
Abstract: Twelve hundred ninety-six patients with resected colon cancer that either was locally invasive (Stage B2) or had regional nodal involvement (Stage C) were randomly assigned to observation or to treatment for one year with levamisole combined with fluorouracil. Patients with Stage C disease could also be randomly assigned to treatment with levamisole alone. The median follow-up time at this writing is 3 years (range, 2 to 5 1/2). Among the patients with Stage C disease, therapy with levamisole plus fluorouracil reduced the risk of cancer recurrence by 41 percent (P<0.0001). The overall death rate was reduced by 33 percent (P ≈ 0.006). Treatment with levamisole alone had no detectable effect. The results in the patients with Stage B2 disease were equivocal and too preliminary to allow firm conclusions. Toxic effects of levamisole alone were infrequent, usually consisting of mild nausea with occasional dermatitis or leukopenia, and those of levamisole plus fluorouracil were essentially the same as t...
2,063 citations
TL;DR: A replication-defective retrovirus vector is used to compare the efficiency of gene transfer in stationary and replicating rat embryo fibroblasts and, in agreement with previous results, gene transfer was inhibited 100-fold in stationary versus replicating cells.
Abstract: Previous reports have shown that retrovirus infection is inhibited in nonreplicating (stationary-phase [hereafter called stationary]) cells. Infection of stationary cells was shown to occur when the cells were allowed to replicate at times up to a week after infection, suggesting that an unintegrated retrovirus could persist in a form that was competent to integrate after release of the block to replication. However, those studies were complicated by the use of replication-competent virus, which can spread in the infected cells. We have used a replication-defective retrovirus vector to compare the efficiency of gene transfer in stationary and replicating rat embryo fibroblasts. In agreement with previous results, gene transfer was inhibited 100-fold in stationary versus replicating cells. In contrast to previously reported results, the block to infection could not be relieved by stimulating stationary cells to divide at times from 6 h to 10 days after infection. Thus, for successful retroviral infection, the infected cells must be replicating at the time of infection. These results have important implications for the use of retroviral vectors for gene transfer.
1,531 citations
TL;DR: A new approach to the design and analysis of Phase 1 clinical trials in cancer and a particularly simple model is looked at that enables the use of models whose only requirements are that locally they reasonably well approximate the true probability of toxic response.
Abstract: This paper looks at a new approach to the design and analysis of Phase 1 clinical trials in cancer. The basic idea and motivation behind the approach stem from an attempt to reconcile the needs of dose-finding experimentation with the ethical demands of established medical practice. It is argued that for these trials the particular shape of the dose toxicity curve is of little interest. Attention focuses rather on identifying a dose with a given targeted toxicity level and on concentrating experimentation at that which all current available evidence indicates to be the best estimate of this level. Such an approach not only makes an explicit attempt to meet ethical requirements but also enables the use of models whose only requirements are that locally (i.e., around the dose corresponding to the targeted toxicity level) they reasonably well approximate the true probability of toxic response. Although a large number of models could be contemplated, we look at a particularly simple one. Extensive simulations show the model to have real promise.
1,402 citations
TL;DR: Yeast telomeres exert a position effect on the transcription of nearby genes, an effect that is under epigenetic control as demonstrated by phenotype and mRNA analyses.
1,379 citations
TL;DR: These studies demonstrate the feasibility and safety of using retroviral gene transduction for human gene therapy and have implications for the design of TIL with improved antitumor potency, as well as for the possible use of lymphocytes for the gene therapy of other diseases.
Abstract: Background and Methods. Treatment with tumor-infiltrating lymphocytes (TIL) plus interleukin-2 can mediate the regression of metastatic melanoma in approximately half of patients. To optimize this treatment approach and define the in vivo distribution and survival of TIL, we used retroviral-mediated gene transduction to introduce the gene coding for resistance to neomycin into human TIL before their infusion into patients — thus using the new gene as a marker for the infused cells. Results. Five patients received the gene-modified TIL. All the patients tolerated the treatment well, and no side effects due to the gene transduction were noted. The presence and expression of the neomycin-resistance gene were demonstrated in TIL from all the patients with Southern blot analysis and enzymatic assay for the neomycin phosphotransferase coded by the bacterial gene. Cells from four of the five patients grew successfully in high concentrations of G418, a neomycin analogue otherwise toxic to eukaryotic cell...
1,284 citations
TL;DR: It was shown that homo- and heterooligomers of the helix-loop-helix proteins MyoD and E2A recognize a common consensus sequence, CA--TG, but otherwise bind to flanking and internal positions with different sequence preferences that suggest half-site recognition, suggesting that different combinations of dimeric proteins can have different binding sequence preferences.
Abstract: A technique was developed for studying protein-DNA recognition that can be applied to any purified protein, partially purified protein, or cloned gene. From oligonucleotides in which particular positions are of random sequence, that subset to which a given protein binds is amplified by the polymerase chain reaction and sequenced as a pool. These selected and amplified binding site (SAAB) "imprints" provide a characteristic set of preferred sequences for protein binding. With this technique, it was shown that homo- and heterooligomers of the helix-loop-helix proteins MyoD and E2A recognize a common consensus sequence, CA--TG, but otherwise bind to flanking and internal positions with different sequence preferences that suggest half-site recognition. These findings suggest that different combinations of dimeric proteins can have different binding sequence preferences.
906 citations
TL;DR: It is suggested that some of the biological functions of Myc family proteins are accomplished by sequence-specific DNA binding that is mediated by the carboxyl-terminal region of the protein.
Abstract: While it has been known for some time that the c-Myc protein binds to random DNA sequences, no sequence-specific binding activity has been detected. At its carboxyl terminus, c-Myc contains a basic--helix-loop-helix (bHLH) motif, which is important for dimerization and specific DNA binding, as demonstrated for other bHLH protein family members. Of those studied, most bHLH proteins bind to sites that contain a CA- -TG consensus. In this study, the technique of selected and amplified binding-sequence (SAAB) imprinting was used to identify a DNA sequence that was recognized by c-Myc. A purified carboxyl-terminal fragment of human c-Myc that contained the bHLH domain bound in vitro in a sequence-specific manner to the sequence, CACGTG. These results suggest that some of the biological functions of Myc family proteins are accomplished by sequence-specific DNA binding that is mediated by the carboxyl-terminal region of the protein.
855 citations
TL;DR: It is suggested that interaction of alpha 3 beta 1 with a secreted, laminin-containing ECM in cultured HFKs, duplicates the role of alpha 2 beta 1 in basal cell adhesion to the basement membrane zone (BMZ) in skin.
Abstract: We have examined cultures of neonatal human foreskin keratinocytes (HFKs) to determine the ligands and functions of integrins alpha 2 beta 1, and alpha 3 beta 1 in normal epidermal stratification and adhesion to the basement membrane zone (BMZ) in skin. We used three assay systems, HFK adhesion to purified extracellular matrix (ECM) ligands and endogenous secreted ECM, localization of integrins in focal adhesions (FAs), and inhibition of HFK adhesion with mAbs to conclude: (a) A new anti-alpha 3 beta 1 mAb, P1F2, localized alpha 3 beta 1 in FAs on purified laminin greater than fibronectin/collagen, indicating that laminin was the best exogeneous ligand for alpha 3 beta 1. However, in long term culture, alpha 3 beta 1 preferentially codistributed in and around FAs with secreted laminin-containing ECM, in preference to exogenous laminin. Anti-alpha 3 beta 1, mAb P1B5, detached prolonged cultures of HFKs from culture plates or from partially purified HFK ECM indicating that interaction of alpha 3 beta 1 with the secreted laminin-containing ECM was primarily responsible for HFK adhesion in long term culture. (b) In FA assays, alpha 2 beta 1 localized in FAs conincident with initial HFK adhesion to exogenous collagen, but not laminin or fibronectin. However, in inhibition assays, anti-alpha 2 beta 1 inhibited initial HFK adhesion to both laminin and collagen. Thus, alpha 2 beta 1 contributes to initial HFK adhesion to laminin but alpha 3 beta 1 is primarily responsible for long-term HFK adhesion to secreted laminin-containing ECM. (c) Serum or Ca2(+)-induced aggregation of HFKs resulted in relocation of alpha 2 beta 1 and alpha 3 beta 1 from FAs to cell-cell contacts. Further, cell-cell adhesion was inhibited by anti-alpha 3 beta 1 (P1B5) and a new anti-beta 1 mAb (P4C10). Thus, interaction of alpha 3 beta 1 with either ECM or membrane coreceptors at cell-cell contacts may facilitate Ca2(+)-induced HFK aggregation. (d) It is suggested that interaction of alpha 3 beta 1 with a secreted, laminin-containing ECM in cultured HFKs, duplicates the role of alpha 3 beta 1 in basal cell adhesion to the BMZ in skin. Further, relocation of alpha 2 beta 1 and alpha 3 beta 1 to cell-cell contacts may result in detachment of cells from the BMZ and increased cell-cell adhesion in the suprabasal cells contributing to stratification of the skin.
598 citations
TL;DR: The times to treatment failure and the proportions of patients in various response categories were similar for primary and secondary treatment, suggesting that the potential efficacy of new immunosuppressive agents for treatment of acute GVHD can be assessed meaningfully in patients who have not responded adequately to initial therapy.
584 citations
TL;DR: The increased dose of TBI significantly reduced the probability of relapse but did not improve survival because of increased mortality from causes other than relapse.
TL;DR: A retroviral vector recently has been used to mark tumor infiltrating lymphocytes in patients with melanoma to follow the persistence of these cells following infusion into patients.
Abstract: Retroviral vectors promote the efficient transfer of genes into a variety of cell types from many animal species. An important contribution to their utility was the development of retrovir...
TL;DR: It is concluded that alpha 6 beta 4 in HFKs localizes in a new stable anchoring contact (SAC) that cooperates with alpha 3 beta 1- FAs to mediate adhesion to ECM, based on the following.
Abstract: Basal cells of stratified epidermis are anchored to the basement membrane zone (BMZ) of skin via hemidesmosomes. We previously identified integrin alpha 3 beta 1, in focal adhesions (FAs), of cultured human keratinocytes (HFKs) as a mediator of HFK adhesion to secreted BMZ-like extracellular matrix (ECM; Carter, W.G., E.A. Wayner, T.S. Bouchard, and P. Kaur. 1990. J. Cell Biol. 110: 1387-1404). Here, we have examined the relation of integrins alpha 6 beta 4 and alpha 3 beta 1, to bullous pemphigoid antigen (BPA), a component of hemidesmosomes. We conclude that alpha 6 beta 4 in HFKs localizes in a new stable anchoring contact (SAC) that cooperates with alpha 3 beta 1-FAs to mediate adhesion to ECM, based on the following. (a) Comparison of secreted ECM, with exogenous laminin, fibronectin and collagen identified ECM as the preferred ligand for HFK adhesion and spreading and for formation of both alpha 6 beta 4-SACs and alpha 3 beta 1-FAs. (b) Inhibition of HFK adhesion with combined anti-alpha 3 beta 1 (P1B5) and anti-alpha 6 beta 4 (GoH3) antibodies indicated that both receptors were functional in adhesion to ECM while alpha 3 beta 1 played a dominant role in spreading. (c) alpha 6 beta 4 colocalized with BPA in SACs that were proximal to but excluded from FAs. Both alpha 6 beta 4-SACs and alpha 3 beta 1-FAs were in contact with the adhesion surface as indicated by antibody exclusion and interference reflection microscopy. (d) In contrast to alpha 3 beta 1-FAs, alpha 6 beta 4-SACs were present only in nonmotile cells, not associated with stress fibers, and were relatively stable to detergents and urea, suggesting a nonmotile, or anchoring function for SACs and motility functions for alpha 3 beta 1-FAs. (e) alpha 6 beta 4 formed a detergent-insoluble complex with exogenous ECM in an affinity isolation procedure, confirming the ability of an unidentified ECM ligand to interact with alpha 6 beta 4. (f) We suggest that alpha 6 beta 4/BPA-SACs in culture restrict migration of HFKs on ECM while alpha 3 beta 1-FAs form dynamic adhesions in spreading and migrating cells. alpha 6 beta 4/BPA-SACs in culture bear functional and compositional similarities to hemidesmosomes in skin.
TL;DR: The results suggest that the LAR is required for both the erythroid-specific chromatin structure and timing of DNA replication over a large physical distance.
Abstract: Naturally occurring deletions that remove sequences located approximately 60 kb upstream of the human adult beta-globin gene result in the failure to transcriptionally activate the cis-linked globin genes in erythroid cells. In addition, transfection, transgenic, and somatic cell hybrid studies have revealed that sequences within this region are essential for the developmentally regulated high-level expression of cis-linked globin genes. This regulatory region located at the 5' end of the beta-globin locus has been termed the locus activation region (LAR). Using somatic cell hybrids, we have studied the chromatin structure and timing of DNA replication of the normal human beta-globin locus and a locus containing a de novo 25-kb deletion that removes elements of the LAR. As a result of this deletion, the entire beta-globin locus and sequences approximately 100 kb 5' and 3' of the adult beta-globin gene are DNase I-resistant and do not form characteristic distant hypersensitive sites. These sequences also replicate late in S phase in an erythroid cell background. In contrast, the sequences of the normal locus are DNase I sensitive and early replicating. These results suggest that the LAR is required for both the erythroid-specific chromatin structure and timing of DNA replication over a large physical distance.
TL;DR: Unexpectedly, overproduction of the RAP1 protein was also shown to decrease greatly chromosome stability, suggesting that R AP1 mediates interactions that have a more global effect on chromosome behavior than simply protecting telomeres from degradation.
TL;DR: The group of proto-oncogen es found to encode nuclear proteins now includes myc, myb, fos, jun, ski, cbl, eibA, members of the ets family^ and possibly several others and some new light is cast on both oncoproteins.
Abstract: The group of proto-oncogen es found to encode nuclear proteins now includes myc, myb, fos, jun, ski, cbl, eibA, members of the ets family^ and possibly several others. Given that so many cytoplasmic and membrane-asso ciated oncoproteins are involved in signal transduction pathways, one rather appealing notion has been that some or all of the nuclear oncoproteins encoded by these genes might act to mediate specific transcriptional re sponses to signals originally generated in the plasma membrane or cytoplasm (for review, see Weinberg 1989). During the last several years, a number of these onco proteins, including ErbA, Fos, Jun and, most recently, Ets, have been demonstrated to be directly involved in transcriptional regulation. It is somewhat ironic that Myc and Myb, two of the first oncoproteins to be shown localized to the nucleus, have appeared to elude func tional characterization. However, recent evidence has demonstrated that Myb also functions in transcription and, while Myc has remained a citadel of incomprehen sibility, new studies have begun to bring this mysterious protein into sharper focus. At first glance, Myc and Myb would appear to have little in common, aside from the fact that both are predominantly localized in the nu cleus. They are quite different structurally and their pat terns of expression are also rather distinct, with Myc present in nearly all cell types while Myb is restricted to hematopoietic cells. However, the functions of both of these oncoproteins appear to be linked to proliferation , and these oncoproteins clearly play major roles in cell differentiation. Furthermore, recent work has cast some new light on both oncoproteins, and in what follows we attempt to meld older with more recent evidence re lating to possible functions. This review will appear in two segments. In part I we consider studies relating to the structure and potential function of Myc; part II, to appear in the next issue, will discuss recent findings on Myb.
TL;DR: The results demonstrate that when amplified, this ubiquitous growth factor receptor behaves like an oncogenic protein and is capable of promoting neoplastic growth in vivo.
Abstract: The human insulinlike growth factor I receptor was overexpressed in NIH 3T3 cells as well as human and rat primary fibroblast strains. The NIH 3T3 cells displayed a ligand-dependent, highly transformed phenotype. When exposed to insulinlike growth factor I or supraphysiologic levels of insulin, NIH 3T3 cells that expressed high levels of receptors formed aggregates in tissue culture dishes, colonies in soft agar, and tumors in nude mice. Expression of 1 million receptors per cell, a 40-fold increase above the base-line level, was required for anchorage-independent growth. Primary fibroblasts that expressed high levels of receptors displayed a ligand-dependent change in morphology and an increase in saturation density but did not acquire a fully transformed phenotype. The results demonstrate that when amplified, this ubiquitous growth factor receptor behaves like an oncogenic protein and is capable of promoting neoplastic growth in vivo.
TL;DR: T cell clones generated and maintained with monoclonal antibody stimulation are rapidly expanded and retain antigen- specific responses after 3 months in culture, suggesting this approach may prove useful for growing large numbers of antigen-specific T cell clones for cellular immunotherapy.
Journal Article•
TL;DR: Passive immunotherapy with intravenous immunoglobulin decreases the risk of acute GVHD, associated interstitial pneumonia, and infections after bone marrow transplantation.
Abstract: Background. Graft-versus-host disease (GVHD) and infection are major complications of allogeneic bone marrow transplantation. Since intravenous immunoglobulin has shown benefit in several immunodeficiency and autoimmune disorders, we studied its antimicrobial and immunomodulatory role after marrow transplantation. Methods. In a randomized trial of 382 patients, transplant recipients given immunoglobulin (500 mg per kilogram of body weight weekly to day 90, then monthly to day 360 after transplantation) were compared with controls not given immunoglobulin. By chance, the immunoglobulin group included more patients with advanced-stage neoplasms; otherwise, the study groups were balanced for prognostic factors. Results. Control patients seronegative for cytomegalovirus who received seronegative blood products remained seronegative, but seronegative patients who received immunoglobulin and screened blood had a passive transfer of cytomegalovirus antibody (median titer, 1:64). Among the 61 seronegativ...
TL;DR: RA sensitivity defines a labile intermediate that occurs during axial patterning of the primary body axis in embryos of the frog Xenopus laevis, and data suggest a possible role for RA in normal axis formation.
Abstract: Retinoic acid (RA) is able to profoundly alter patterning of the primary body axis in embryos of the frog Xenopus laevis. The response to RA is dose-dependent, and leads to progressive truncation of the anteroposterior axis, with anterior structures most sensitive. Both mesodermal and ectodermal tissues are affected, and in vitro assays demonstrate that induced dorsal ectoderm is one direct target of RA. RA represses expression of anterior-specific genes and concomitantly induces expression of at least one posterior-specific gene. Resistance to RA is acquired gradually, during gastrula and early neurula stages, with posterior structures becoming resistant before anterior structures. These data demarcate in the embryo an anterior "domain," which may define the head rudiment and which transcends germ layers. RA can alter the axial pattern after its initial induction; thus, RA sensitivity defines a labile intermediate that occurs during axial patterning. These data suggest a possible role for RA in normal axis formation.
TL;DR: It is concluded that a standardized, behavioral approach to measuring fat-related dietary behavior may be useful for designing and evaluating nutrition intervention programs.
Abstract: This report describes the development and evaluation of a behavioral measure of dietary patterns related to selecting low-fat diets. An 18-item questionnaire, based on an anthropological theory of dietary change, was developed to assess four relevant dimensions of dietary behavior: (a) excluding high-fat ingredients and preparation techniques, (b) modifying high-fat foods, (c) substituting specially manufactured low-fat foods for their higher-fat counterparts, and (d) replacing high-fat foods with low-fat alternatives. In this study, 99 women completed the diet behavior questionnaire twice and, to characterize precisely their dietary fat intake, also completed two 4-day food records and a food frequency questionnaire. Participants were aged 45 to 59 years and were selected to have a wide range of fat intakes (19.4% to 49.4% of calories from fat). Confirmatory factor analysis identified five scales that corresponded to those hypothesized, except for exclusion, which split into avoiding meat and avoiding fat as a seasoning. The scales had high test-retest and internal consistency reliabilities, and correlations with percent of calories from fat ranged from 0.34 to 0.57 (p less than .01). The correlation of the sum of the five scales (18 items) with percent of calories from fat was 0.68 (p less than .001) and, in multiple regression models, the multiple R2 using all factors to predict percent of calories from fat was 0.47. Overall, these findings supported the validity of the theoretical model of dietary patterns related to selecting diets low in fat. We conclude that a standardized, behavioral approach to measuring fat-related dietary behavior may be useful for designing and evaluating nutrition intervention programs.
TL;DR: The ras proto-oncogene products appear to relay intracellular signals via the Ras guanosine triphosphatase (GTPase) activator protein, GAP, in dog epithelial cells expressing human platelet-derived growth factor receptors.
Abstract: The ras proto-oncogene products appear to relay intracellular signals via the Ras guanosine triphosphatase (GTPase) activator protein, GAP. In dog epithelial cells expressing human platelet-derived growth factor (PDGF) receptors, binding of PDGF caused approximately one-tenth of the total GAP molecules to complex with the receptor. Studies with mutant PDGF receptors showed that maximum association required both receptor kinase activity and phosphorylatable tyrosine residues at both the identified sites of receptor autophosphorylation.
TL;DR: The two most common reasons women gave for never having had a mammogram were that they did not know they needed it and that their physician had not recommended it.
Abstract: Data from seven studies sponsored by the National Cancer Institute (NCI) were used to determine current rates of breast cancer screening and to identify the characteristics of and reasons for women not being screened. All seven studies were population-based surveys of women aged 50 to 74 years without breast cancer. While over 90% of non-Hispanic white respondents had regular sources of medical care, 46% to 76% had had a clinical breast examination within the previous year, and only 25% to 41% had had a mammogram. Less educated and poorer women had had fewer mammograms. The two most common reasons women gave for never having had a mammogram were that they did not know they needed it and that their physician had not recommended it. Many physicians may have overlooked the opportunity to recommend mammography for older women when performing a clinical breast examination and to educate their patients about the benefit of screening mammography.
TL;DR: Investigation of the relevance of HLA incompatibility to acute graft-versus-host disease, relapse, and survival in 281 patients with hematologic neoplasms who underwent bone marrow transplantation found it was associated with lower leukemic relapse after transplant in patients with acute lymphocytic leukemia.
TL;DR: The c-Myb nuclear oncoprotein is phosphorylated in vitro and in vivo at an N-terminal site near its DNA-binding domain by casein kinase II (CK-II) or a CK-ll-like activity, resulting in DNA- binding that is indepen-dent of CK-II.
Abstract: The c-Myb nuclear oncoprotein is phosphorylated in vitro and in vivo at an N-terminal site near its DNA-binding domain by casein kinase II (CK-II) or a CK-II-like activity. This in vitro phosphorylation reversibly inhibits the sequence-specific binding of c-Myb to DNA. The site of this phosphorylation is deleted in nearly all oncogenically activated Myb proteins, resulting in DNA-binding that is independent of CK-II. Because CK-II activity is modulated by growth factors, loss of the site could uncouple c-Myb from its normal physiological regulator.
TL;DR: Consistency was found between the aggregate and analytic data results, leaving open the strong possibility that a practical reduction in dietary fat could result in a major reduction in the incidence of several prominent cancers in the United States and in other nations having high fat consumption.
Abstract: International variations and national time trends in disease rates suggest major associations between dietary fat and several important cancers. In contrast, case-control and cohort studies of dietary fat in relation to the same cancers generally report weak associations, or have failed to detect any association with fat intake. This study was undertaken in an attempt to understand the apparent discrepancy between these observations. The results provide an insight into the magnitude of cancer risk reduction that may follow from a practical reduction in dietary fat. Regression analyses of international variations in cancer incidence rates were used to estimate relative risks (RR) as a function of fat intakes for both males and females. These analyses focused on cancers of the breast, colon, rectum, ovary, and endometrium in females, and colon, rectum, and prostate cancers in males. Ages 55–69 and 30–44 were considered in order to compare RR estimates between an older and younger age group, and between post- and pre-menopausal women. Corresponding RR estimates were also calculated, based on the regression of changes in disease rates from the mid-1960s to 1980 on changes in dietary fat, using data from several countries. A strong degree of consistency with the RR estimates from international comparisons was observed. The international regression analyses were also used to project changes in cancer rates among Japanese migrants to the United States. A high level of consistency with the observed disease-rate changes was noted. Similarly, the international data analyses were used to project RRs for the fat intake categories used in specific case-control and cohort studies, while acknowledging measurement error in individual dietary assessment. Although certain exceptions are noted, considerable consistency was found between the aggregate and analytic data results, leaving open the strong possibility that a practical reduction in dietary fat could result in a major reduction in the incidence of several prominent cancers in the United States and in other nations having high fat consumption.
TL;DR: 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, indicating that RAR- alpha plays a critical and central role in mediating RA-induced terminal differentiation of HL- 60 leukemia cells.
Abstract: 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.
TL;DR: Position-effect variegation in Drosophila--the mosaic expression of a gene placed adjacent to a junction between euchromatin and heterochromatin--remains an enigma, but new insights are being gained from recent studies of genetic modifiers, new model systems, and variegating genes showing exceptional behavior.
Journal Article•
TL;DR: The results suggest that IL-4 may have potent effects on lymphocyte recirculation in vivo, and the avidity ofIL-4-activated microvascular EC for lymphocytes, and analyses of kinetics, cation and temperature dependence, and/or lack of blockade with mAb to endothelial leukocyte adhesion molecule-1, intra-cellular adhesion molecules-1 and MECA-79 indicated that these CAM were not central to the phenomenon.
Abstract: Adhesion of lymphocytes to endothelial cells (EC) is the requisite first element in the multistep process of transmigration from blood across the postcapillary venules. Selective expression of cell adhesion molecules (CM) by microvascular EC in lymphoid organs (e.g., lymph nodes) and during tissue inflammation modulates this traffic in a site-directed manner. CAM synthesis by EC is regulated in turn by cytokines released in the local microenvironment. Studies done largely with human umbilical vein EC have implicated IL-1, IFN-gamma, and TNF-alpha as cytokines which promote leukocyte adhesion to EC. In the work reported here, the responses of cultured microvascular EC derived from macaque lymph nodes to IL-1beta, IL-2, IFN-gamma, and IL-4 were examined. Increases in lymphocyte adhesion after preculture of microvascular EC in IL-1beta or IFN-gamma were typically 2-to 4-fold above controls and comparable to those reported for human umbilical vein EC. IL-2 had no effect. In contrast, IL-4 markedly enhanced adhesion to microvascular EC. IL-4-induced adhesion was observed as early as 4 h after induction, plateaued by 24 h, was stable through 72 h of culture, but decayed to basal levels within 72 h after removal of IL-4 from the cultures. IL-1beta, but not IL-2 or IFN-gamma, synergistically enhanced the action of IL-4 on cultured microvascular EC to promote lymphocyte binding. Adhesion triggered in this manner required de novo protein synthesis. However, the avidity of IL-4-activated microvascular EC for lymphocytes, and analyses of kinetics, cation and temperature dependence, and/or lack of blockade with mAb to endothelial leukocyte adhesion molecule-1, intra-cellular adhesion molecule-1, and MECA-79 indicated that these CAM were not central to the phenomenon. To aid identification of the relevant CAM, mAb specific to IL-4-induced microvascular EC were produced. One of these, 6G10, blocked up to 90% of lymphocyte adhesion to IL-4-induced microvascular EC, immunoprecipitated an IL-4-induced cell-surface molecule of 110-kDa molecular mass, and reacted specifically with Chinese hamster ovary cells transfected with human vascular cell adhesion molecule-1. Our results suggest that IL-4 may have potent effects on lymphocyte recirculation in vivo.