Effects of mutagenized X chromosomes of Drosophila melanogaster on viability and fitness in males

Drosophila melanogaster males were treated with different doses of X-rays or ethyl methanesulfonate (EMS) and mated so that mutagenized X chromosomes could be recovered and tested for lethal mutations and for less drastic mutations affecting viability and other aspects of fitness. The lethals were detected in standard X-linked lethal tests. The less drastic mutations were detected in one generation tests for effects on viability and in multigeneration tests for effects on overall fitness. The Poisson-corrected frequencies of the lethal mutations increased linearly with dose for both X-rays and EMS. Based on the data, 1 Krad X-rays given acutely induces the same number of lethals as 0.55 mM EMS administered by feeding. For some of the X-ray and EMS doses, the mutagenized chromosomes that were nonlethal reduced the viability of their carriers by a small amount, but there was no discernable dose-effect relationship. However in every case where a viability effect was seen, the percentage reduction was less than the corresponding frequency of lethals. All the groups of mutagenized nonlethal chromosomes reduced overall fitness by a significant percentage. Wherever a meaningful comparison was possible, this reduction was 2-3 times the reduction in viability, but, as in the viability data, no dose-effect relationship was discernable.     

Gene therapy: a molecular approach to cancer treatment

The current delineation of the molecular basis of cancer provides a strong rationale to consider gene therapy approaches for cancer as a complement to other cancer therapies. Phase III trials focused on adenoviral vector-mediated delivery of wild-type p53 to compliment p53 mutations were recently initiated for head and neck cancer and ovarian cancer. Clinical testing of the tumor inhibitory gene E1A, delivered by synthetic vectors is ongoing. Positive clinical data from these clinical studies will establish the use of gene therapy as a component of the multimodal treatment for certain cancers.     

Polymorphonuclear and monocyte functions in measles

The depression of immune responses during measles infection has been recognized since the early 20th century. Acute bacterial infections are the most common cause of morbidity and mortality in measles. This study investigated the phagocytic and bactericidal or fungicidal capacities of polymorphonuclear cells (PMN) and monocytes during measles infections. When 14 children with measles were compared with 25 healthy controls, a significant depression in PMN and monocyte function was found. Of these 14 children, seven developed acute bacterial infections. These seven children were compared with 11 children who had acute bacterial infections without measles. It was found that PMN in patients with measles did not achieve an activated state, as expected with acute infections. Serum immunoglobulins were not altered in these patients. These results confirm previous reports of depressed phagocytic and bactericial capacities of PMN in measles, and further document that peripheral blood monocyte functions are also depressed in measles.     

Defective chemotaxis and adherence in granulocytes from chronic myeloid leukemia (CML) patients

Adherence and motility of granulocytes from chronic myeloid leukemia (CML) patients was compared with that of granulocytes from normal subjects. The percentage of non-adherent granulocytes was significantly higher in untreated CML patients and patients in relapse and acute blastic crisis (ABC) (P less than 0.01). Chemotactic Index (C.I.) of granulocytes moving in a gradient of a synthetic chemoattractant F-Met-Leu-Phe was measured by time-lapse cinématography. While 84.5 +/- 3.53% of normal granulocytes were motile, only 30.3 +/- 14.7% granulocytes from untreated patients, 33.8 +/- 21.3% granulocytes from relapse patients and 36 +/- 9.9% granulocytes from ABC patients were found to be motile. The C.I. of motile granulocytes from CML patients was significantly lower in untreated patients (P less than 0.05), in patients in relapse (P less than 0.01) and in patients in ABC (P less than 0.05), as compared to that of normal granulocytes. Visualization of cytoplasmic actin by indirect immunofluorescence, revealed the presence of actin in granulocytes from patients in all stages of the disease. Thus, granulocytes from CML patients were defective in directional locomotion. Organized actin filaments were found in the small percentage of motile cells still found in CML patients.     

In vivo efficacy of folate-targeted lipid-protamine-DNA (LPD-PEG-Folate) complexes in an immunocompetent syngeneic model for breast adenocarcinoma

Gene therapy utilizing lipid-based delivery systems holds tremendous promise for the treatment of cancer. However, due to the potential adverse inflammatory and/or immune effects upon systemic administration, treatments thus far have been predominantly limited to intratumoral or regional treatment. Previous studies from our group have demonstrated the antitumor efficacy of systemically administered, folate-targeted, lipid-protamine-DNA complexes (LPD-PEG-Folate) against breast cancer using an immunodeficient xenogenic murine model. In the current study, the antitumor efficacy of LPD-PEG-Folate in a syngeneic, immune competent, murine model of breast cancer was examined. In this model, the potential inflammatory or immune responses and their effects on systemic delivery can be addressed. The 410.4 murine breast adenocarcinoma cell line was initially evaluated in vitro for its interactions with LPD-PEG-Folate and control LPD-PEG formulations. Utilizing fluorescently labeled formulations and fluorescence-activated cell sorting (FACS) analysis, a 1.6-fold enhancement of binding and internalization of LPD-PEG-Folate over LPD-PEG formulations was observed, suggestive of specific receptor interaction. Increased binding was manifested as 5-26-fold increases in luciferase gene expression in 410.4 cell transfection when comparing LPD-PEG-Folate to LPD-PEG. Moreover, in vivo treatment of 410.4 breast tumors in BALB/c mice with i.v. injected LPD-PEG-Folate delivering the HSV-1 thymidine kinase (TK) gene, in combination with gancyclovir treatment, resulted in a significant reduction in mean tumor volume (260.1 mm3) compared to the LPD-PEG-TK (914.1 mm3), as well as the vehicle (749.7 mm3) and untreated (825.3 mm3) control groups (day 25, P<.019). In addition to a reduced tumor volume, LPD-PEG-Folate-TK treatment also increased median survival from 25 days in the nontargeted LPD-PEG-TK groups to 31 days (P=.0011), which correlated with the termination of treatment. Together, these results demonstrate that in the context of a fully functional immune system, LPD-PEG-Folate-TK treatment possesses significant specific antitumor efficacy and the potential for further preclinical development.     

Expression of M-CSF and its receptor (C-FMS) during factor-independent cell line evolution from hematopoietic progenitor cells cocultivated with gamma irradiated marrow stromal cell lines.

Gamma irradiation of plateau-phase clonal bone marrow stromal cell lines produces factor-independent growth of cocultivated clonal interleukin-3/granulocyte-macrophage colony-stimulating factor-dependent hematopoietic progenitor cell lines. The process is associated with three biologic changes including: (i) adherence of hematopoietic cells to stromal cells forming 'cobblestone islands'; (ii) an intermediate stage [during which the cells show proliferation in suspension in the presence in leukemogenic stromal factor (LSF), a factor similar to macrophage colony-stimulating factor (M-CSF) released by irradiated stromal cells, and transient hematopoietic cell surface expression of MAC-1, and c-fms (M-CSF receptor)]; and (iii) a third stage of factor-independence. A monoclonal antibody to M-CSF receptor inhibited proliferation of intermediate stage but not all factor-independent cell subclones. In the present studies, a subclonal factor-independent malignant subline of FDC-P1JL26 derived by cocultivation with gamma-irradiated stromal cells as well as the parent clone and intermediate stage cells were shown to express significant levels of M-CSF polyA+ mRNA and M-CSF of at least two sizes (23 and 15 kDa) as detected by 35S-methionine labelling and immunoprecipitation with polyclonal anti-M-CSF antiserum. There was no significant difference in intracellular M-CSF protein size between cells at each of the three stages of biologic change. This M-CSF was not detected on the cell surface by fluorescence-activated cell sorting (FACS). In contrast, c-fms expression at the cell surface was detected by FACS analysis and c-fms polyA+ mRNA was only detected during the intermediate stage of induction of factor-independence. FDC-P1JL26 parent cells, the subclone stimulated by LSF, and the factor-independent subclone, showed little or no detectable autophosphorylation of the c-fms receptor at tyrosine. There was no detectable rearrangement of the M-CSF or c-fms genes by Southern analysis between clonal lines during the three stages. While we cannot rule out an autocrine mechanism or mutated c-fms receptor mechanism, the data also suggest that evolution of hemopoietic cell factor-independence during cocultivation with irradiated stromal cells may involve a mechanism distal to the c-fms receptor/M-CSF interaction.     

Role of beta 1 and beta 2 integrins in the adhesion of human CD34hi stem cells to bone marrow stroma.

Hematopoietic stem cell interaction with elements of the underlying stroma is essential for sustained normal hematopoiesis. Here we have determined that adhesion receptors in the integrin family play a role in promoting adhesion of human hematopoietic stem cells to cultured human marrow stromal cells. Enriched CD34hi progenitor cells expressed VLA-4, VLA-5, and at least one or more beta 2 integrins. Homogeneous marrow stromal cell monolayers capable of supporting proliferation of cocultivated CD34hi cells expressed VCAM-1 and fibronectin (ligands for VLA-4 and VLA-5) as well as ICAM-1 (ligand for LFA-1 and Mac-1). Adhesion-blocking experiments indicated that VLA-4/VCAM-1, VLA-5/fibronectin, and beta 2-integrin/ICAM-1 pathways all are important for CD34hi cell attachment to stromal cells. Consistent with this suggestion, IL-1 stimulation of stromal cells caused both increased VCAM-1 and ICAM-1 expression and increased attachment by CD34hi bone marrow cells. In addition, CD34hi cells utilized VLA-4 to adhere to purified VCAM-1 and employed VLA-5 (and to a lesser extent VLA-4) to adhere to purified fibronectin. Together these results suggest that CD34hi stem cells may utilize multiple integrin-mediated adhesion pathways to localize within specialized microenvironmental niches created by marrow stromal cells.     

Engraftment of a clonal bone marrow stromal cell line in vivo stimulates hematopoietic recovery from total body irradiation.

Whether bone marrow stromal cells of donors contribute physiologically to hematopoietic stem cell reconstitution after marrow transplantation is unknown. To determine the transplantability of nonhematopoietic marrow stromal cells, stable clonal stromal cell line (GB1/6) expressing the a isoenzyme of glucose-6-phosphate isomerase (Glu6PI-a, D-glucose-6-phosphate ketol-isomerase; EC 5.3.1.9) was derived from murine long-term bone marrow cultures and made resistant to neomycin analogue G418 by retroviral gene transfer. GB1/6 cells were fibronectin+, laminin+, and collagen-type IV+ and collagen type I-; these GB1/6 cells supported in vitro growth of hematopoietic stem cells forming colony-forming units of spleen cells (CFU-S) and of granulocytes, erythrocytes, and macrophage/megakarocytes (CFU-GEMM) in the absence of detectable growth factors interleukin 3 (multi-colony-stimulating factor), granulocyte/macrophage colony-stimulating factor, granulocyte-stimulating factor, or their poly(A)+ mRNAs. The GB1/6 cells produced macrophage colony-stimulating factor constitutively. Recipient C57BL/6J (glucose-6-phosphate isomerase b) mice that received 3-Gy total-body irradiation and 13 Gy to the right hind limb were injected i.v. with GB1/6 cells. Engrafted mice demonstrated donor-originating Glu6PI-a+ stromal cells in marrow sinuses in situ 2 mo after transplantation and a significantly enhanced hematopoietic recovery compared with control irradiated nontransplanted mice. Continuous (over numerous passages) marrow cultures derived from transplanted mice demonstrated G418-resistant, Glu6PI-a+ stromal colony-forming cells and greater cumulative production of multipotential stem cells of recipient origin compared with cultures established from irradiated, nontransplanted control mice. These data are evidence for physiological function in vivo of a transplanted bone marrow stromal cell line.