Limits of stimulation of proliferation and differentiation of bone marrow cells of mice treated with swainsonine

The limits of stimulation of the immunomodulatory alkaloid swainsonine (8αβ-indolizidine-1α,2α,8β-triol) were studied in inbred C57BL/6 mice for potential support of intense high dose cancer chemotherapy and/or radiation because of its attractive pharmacologic profile on the hematopoietic system. Specifically, the effects of swainsonine on bone marrow cellularity and on in vitro progenitor cell proliferation to total colony forming units (CFU) and differentiation to different lineages were studied as a function of number of days post drug administration. The lineages evaluated were colony forming units-granulocyte-macrophage (CFU-GM), erythroid-burst forming units (BFU-e) and CFU-granulocyte-erythrocyte-monocyte-megakaryocyte (CFU-GEMM or CFU-Mix). Groups of mice were treated with swainsonine or plain vehicle, phosphate buffered saline for 10 consecutive days. The effects of these agents on the hematopoietic system were studied up to 60 days following their discontinuation. The magnitude of the effects of swainsonine on bone marrow system gradually declined with increasing duration of days following its discontinuation. Nevertheless, its residual stimulatory effects on bone marrow cellularity, total CFU, CFU-GM, BFU-e and CFU-Mix continued to be significant (P\u3c0.0001) up to 45, 50, 50, 55 and 50 days, respectively, compared to those of diluent buffer or untreated controls. Since cancer chemotherapeutic agents or radiation are normally given in schedules and/or cycles, these results strongly suggest that swainsonine effects are sustained long enough to potentially support and facilitate hematopoietic recovery during anti-cancer cytotoxic treatment. © 2003 Elsevier B.V. All rights reserved

Alterations in Monoclonal Antibody Affinity and Antigenic Receptor Site Expression on Mycoplasma-Infected Human Colorectal Cancer Cells

The affinity of MoAb CO 17–1A and expression of its antigenic target were studied on uninfected and mycoplasma-infected colorectal cancer cell lines SW 1116 and SW 948. Binding of 125I-labeled CO 17–1A to SW 1116 cells was quantified at 37°C by determination of the affinity constant (Ka) and the number of antigenic receptor sites (r) per cell using Scatchard plots. When mycoplasma-free SW 1116 cells were used as targets, Ka was 0.92 ± 0.06 × 108M -1 and r = 1.32 ± 0.14 × 106 at 37°C. One batch of unspeciated, mycoplasma-infected SW 1116 cells had reduced affinity and a decreased number of antigenic receptor sites per cell for 125I-labeled 17–1A, while another batch of infected SW 1116 cells had a 4- to 5-fold increase in r and diminished Ka for the antibody compared with uninfected cells. When unspeciated, mycoplasma-infected SW 948 cells were exposed to 125I-labeled 17–1A and the data subjected to Scatchard analysis, the affinity of the antibody deviated markedly from linearity and rendered analysis for Ka and r meaningless. These data indicate that mycoplasma infection can produce variable effects on the cellular expression of antigenic receptor sites and the affinity of antibody for its target, and emphasize the importance of using mycoplasma-free cell lines in studies of these parameters. © 1990, SAGE Publications. All rights reserved

A carcinogenesis- and tumorigenesis-associated rat fetal protein: An immuno-histochemical and immuno-biochemical study utilizing a new monoclonal antibody, MOFP

An oncofetal protein (OFP), which is a potential marker for carcinogenesis and tumorigenesis, was evaluated with monoclonal antibodies shown to be specific for the antigen. Treatment of partially hepatectomized rats with a single non-necrogenic dose of diethylnitrosamine induced OFP in the liver. Its concentration, as measured by a dual immunol/bioassay, increased steadily over a 5-week period of observation before reaching a constant level. Immunohistochemical localization of OFP in liver sections from rats treated with N-nitroso-N-diethyl-nitrosamine showed that the factor was primarily localized to the cell cytoplasm in cells of most of the altered hepatic foci although some of this shedding antigen was also extracellular. Monoclonal antibody 17-1A specific for 17-1A antigen, an established surface marker for adenocarcinomas of the gastrointestinal tract, showed a similar distribution in liver from the carcinogentreated rats, but localized to the cell membrane and cytoplasm. Scattered cells surrounding the altered hepatic foci were also positive for both monoclonal antibodies. Immunolocalization studies showed fetal rat liver and hepatoma were positive for OFP but adult normal or regenerating liver was negative. It was not detected in cells which morphologically could be classified as oval cells. As assessed by immuno/bioassay, the OFP released to the peripheral blood (plasma) of hepato-carcinogen-treated rats increased for 3 weeks, before undergoing a transitory decrease. Circulating antibodies specific for the factor were detected in the blood around 3-5 weeks post-treatment. Development of Western blots of the OFP with antiphosphotyrosine IgG indicates that the marker protein contains phosphotyrosine. © 1989 Oxford University Press

Protective effects of swainsonine on murine survival and bone marrow proliferation during cytotoxic chemotherapy

We have investigated the ability of swainsonine, an indolizidine alkaloid with pleiotropic in vivo effects, to confer protection against the cytotoxic effects of both cell cyclespecific and cell cycle-nonspecific cytotoxic anticancer agents. The intraperitoneal administration of swainsonine decreased the lethality of methotrexate (MTX), fluorouracil (5-FU), cyclophosphamide (CPM), and doxorubicin (DOX) in non-tumor-bearing C57BL/6 mice. The increased survival rate was found to correlate with stimulation of bone marrow cell proliferation, as measured by increases in 1) bone marrow cellularity, 2) in vivo and in vitro colony-forming activity, and 3) engraftment efficiency. These responses were critically dependent on the dose, sequence, and timing of swainsonine administration. If these results are confirmed in humans, swainsonine may offer promise in future intensive chemotherapy programs, allowing increased dosage and/or frequency of administration of cytotoxic agents without increasing toxic effects in bone marrow. [J Natl Cancer Inst 83:1149-1156, 1991]. © 1991 Oxford University Press

The potential importance of swainsonine in therapy for cancers and immunology

Swainsonine, an indolizidine alkaloid, was initially used in biomedical research as a tool to investigate the biosynthesis and function of asparagine-linked \u27complex\u27 type oligosaccharide moieties of glycoproteins. Recently, swainsonine has generated interest in its potential use as an anticancer agent with reports that it (i) inhibits tumor growth and metastasis, (ii) augments natural killer (NK) and macrophage-mediated tumor cell killing, and (ii) stimulates bone marrow cell proliferation. The antineoplastic activity of swainsonine can be explained at least in part by augmentation of immune effector mechanisms. The potential application of swainsonine as an anticancer agent is discussed. © 1991

Activated eosinophils infiltrate MCF-7 breast multicellular tumor spheroids

Background: Previous studies in our laboratory have shown that activated eosinophils and eosinophilic cell lines inhibit the in vitro growth of MCF-7 breast tumor cells. We have also shown that IL-4 and IL-5 partiaIly inhibit MCF-7 growth in vitro. In this study MCF-7 multicellular tumor spheroids (MTS) were developed to study the effect of eosinophils and IL-4 on tumor growth. Materials and Methods: Hypo- and hyperdense metrizamide density gradient fractions of eosinophils from peripheral blood of individuals with mild to moderate esoinophilia were co-cultured with 2-day-old MCF-7 MTS in medium containing bacto agar overlay at 37°C. Results: Light microscopic analyses revealed the attachment of eosinophil effector cells to the spheroid borders. Moreover, the culture media was greater than 90% devoid of effector cells. At six days post co-culture, very large spheroids were observed in both test and control dishes; however the necrotic cores in the co-cultures were more intense and larger than in the control. When MCF-7 tumor cells (1 × 106) were pretreated with IL-4 at 0.5 ng/ml, there was a dramatic decrease in the number of spheroids formed. Conclusion: These data strongly indicate that cytokines like IL-4 and perhaps other eosinophil mediators are capable of killing and inhibiting tumor growth; they suggest that tumor infiltrating eosinophils can degranulate and release toxic inhibitory factors into the tumor milieu which destroy the surrounding tumor. These observations, along with the use of the eosinophil: MTS tumor model provide a unique model system for in depth studies of the role of eosinophils and the cytokines they produce in breast cancer and may offer potential therapeutic implications

Inhibition of prostate cancer cell growth by activated eosinophils

BACKGROUND. Host Immune response to prostate cancer primarily involves the CTL and NK effector cells. Recent immunotherapeutic strategies incorporating cytokine genes into the tumor cell and/or dendritic cells have had encouraging results. In this study, we describe the inhibitory activity of a third potential effector cell, the eosinophil, against DU 145 and PC-3 prostate tumor cells growth in vitro. METHODS. Subconfluent monolayer cultures of DU 145 and PC-3 cells were incubated with peripheral blood eosinophils from allergic or asthmatic individuals and also with eosinophil cultured supernatants. Newly established eosinophil cell lines were also studied. After harvesting, the plates were washed and stained with Hematoxylin/eosin (H/E) then photographed. The combination of monolayer cell growth inhibition and colony formation inhibition assays were used to evaluate eosinophil inhibitory activity. In the colony formation inhibition assay one hundred cells per well in 6-well plates were incubated overnight, after which peripheral blood eosinophils, conditioned media and cytokines, IL-4 and TNF-α were added. The plates were harvested after 10 days incubation period. Colonies were stained and counted. RESULTS. Hypo- and hyperdense peripheral blood eosinophils from allergic and asthmatic individuals as well as eosinophil cell lines established from these subpopulations inhibited both DU 145 and PC-3 cell growth at 58-78% and 10-38%, respectively. IL-5 up-regulated eosinophil cell line activity by 21-24%. The conditioned media which contained the released mediators of activated eosinophils were potent in their actions on both DU 145 and PC-3, inhibiting colony formation by as much as 90-100%. CONCLUSION. These results clearly demonstrate the inhibitory potential of activated eosinophils and their released soup of mediators and therefore support the hypothesis that eosinophils may participate in host response to prostate cancer together with CTLs and NK cells. Furthermore, this study offers insights into possible strategies for enhancing eosinophilic activity in prostate cancer. © 2003 Wiley-Liss, Inc