Browsing by Author "Ajit Sodhi"

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Activation of c-Jun N-terminal kinase is required for ultraviolet B-induced apoptosis of murine peritoneal macrophages in vitro
(2004) Gautam Sethi; Ajit Sodhi
The mechanisms of ultraviolet B (UVB)-induced apoptosis and the role of c-Jun N-terminal kinase (JNK) mitogen activated protein kinase (MAPK) in murine peritoneal macrophages, the terminally differentiated non-dividing cells were investigated. Exposure of macrophages to UVB 100 mJ/cm2 induced rapid apoptosis concurrent with activation of JNK and mitochondrial cytochrome c release leading to procaspase-3 activation. Late into the UVB-induced apoptosis, a caspase-mediated cleavage of Bid was observed. Caspase inhibitors N-Benzylocarbonyl-Val-Asp-fluoromethyl ketone and N-Acetyl-Asp-Glu-Val-Asp-aldehyde inhibited the UVB-induced apoptosis without preventing the release of cytochrome c and JNK activation. The inhibition of JNK MAPK prevented UVB-induced apoptosis, concomitant with inhibition in cytochrome c release and procaspase-3 activation. However, it had no effect on procaspase-8 activation. These results indicate that activation of JNK MAPK upstream of caspases might play an important role in the apoptotic process of macrophages exposed to UVB irradiation. © 2003 Elsevier B.V. All rights reserved.
Activation of human NK cells and monocytes with cisplatin in vitro
(1990) Ajit Sodhi; Kalpana Pai; Rakesh Kumar Singh; Sukh Mahendra Singh
Human natural killer (NK) cells and monocytes treated in vitro concomitantly with cisplatin and rIFN-γ enhanced lysis of K562 cells. Lysis was dependent upon the duration of treatment. Cisplatin and rIFN-γ treated monocytes were equally cytotoxic to NK sensitive (K562) and NK resistant (Daudi & Raji) cell lines whereas NK cells were not rendered cytotoxic against NK resistant tumor cells. NK- and monocyte-mediated cytotoxicity against K562 cells was further enhanced when the effector cells were primed with rIFN-γ and were subsequently treated with cisplatin. © 1990.
Activation of murine macrophages by tumor necrosis factor, interleukin-1, interferon-γ and cisplatin
(1990) Ajit Sodhi; Rakesh Kumar Singh; Kalpana Pai
Murine peritoneal macrophages were rendered tumoricidal to Dalton's lymphoma (DL) cells on incubation with recombinant tumor necrosis factor alpha (rTNF-α), recombinant interleukin-1 (rIL-1) and cisplatin in vitro. Simultaneous treatment of macrophages with suboptimal doses of rTNF-α and rIL-1 had additive effect on the activation of macrophages. Priming of macrophages with recombinant interferon gamma (rIFN-γ) significantly enhanced the rTNF-α and rIL-1-induced macrophage cytotoxicity. Cisplatin was found to up-regulate rIL-1-induced macrophage activation but inhibited the activation of macrophages with rTNF-α. These studies indicate the potential of appropriate combination of these Biological Response Modifiers (BRMs) against neoplasia. © 1990.
Activation of Murine Peritoneal Macrophages with Cisplatin and Lipopolysaccharide: Involvement of Protein Kinase C and Tyrosine Kinase
(1994) Rakesh Kumar; Ajit Sodhi
In the present study we report that protein kinase C (PKC) inhibitors, H-7 and chelerythrine chloride, inhibit the cisplatin- or lipopolysaccharide (LPS)-induced activation of murine peritoneal macrophages to the tumoricidal state. Similarly, the tumoricidal activity was also downregulated by protein tyrosine kinase (PTK) inhibitors, genestein and lavendustin A. The production of interleukin-1 (IL-1) and tumor necrosis factor (TNF) by cisplatin- or LPS-treated macrophages was also inhibited by both PKC and PTK inhibitors. These findings suggest the involvement of PKC and PTK in the activation of murine peritoneal macrophages with cisplatin and LPS. © 1994, SOCIETY FOR FREE RADICAL RESEARCH JAPAN. All rights reserved.
Activation of P388D1 macrophage cell line by chemotherapeutic drugs
(Elsevier Inc., 1997) Kalpana Pai; Anju Shrivastava; Rakesh Kumar; Smriti Khetarpal; Bhaskarjyoti Sarmah; Pankaj Gupta; Ajit Sodhi
It has been found that certain antineoplastic drugs impart their function with a distinct duality. Besides being tumoricidal, they are capable of acting as immunopotentiator. This led us to investigate the effect of cytosine arabinoside (CA), vincristine sulphate (VS), cyclophosphamide (CS), mitomycin C (MMC), hydroxy urea (HU) and lipopolysaccharide (LPS) on a macrophage cell line P388D1. Supernatants collected from P388D1 cells treated with CA, VS, CS, MMC, HU or LPS demonstrated enhanced production of tumor necrosis factor (TNF) confirmed by bioassay on L929 tumor target cells and increased interleukin-1 (IL-1) production by standard thymocyte proliferation bioassay. Also, supernatants showed increased amounts of nitric oxide and lysozyme using Griess reaction and reduction in turbidity of Micococcus lysodeikticus, respectively. The above findings demonstrate that these drugs may be used not only as chemotherapeutic agents but also as macrophage-activating agents.
Age-associated hematopoietic alterations in the spleen of tumor-bearing hosts
(S. Karger AG, 1998) Vineeta Khare; Sukh Mahendra Singh; Ajit Sodhi
The present investigation was carried out to study the effect of tumor growth on the spleen of an aged host. Dalton's lymphoma (DL), a spontaneous T cell lymphoma, was grown in mice of different age groups classified as young, adult or old on the basis of their reproductive status. Splenocytes obtained from normal and tumor-bearing young, adult and old mice were checked for an in vitro blastogenic response to concanavalin A (Con A), colony-forming ability and apoptosis. There was an enhanced apoptosis of splenocytes and a concomitant inhibition of splenocyte blastogenesis and their responsiveness to the mitogenic stimulus of Con A in aged mice. The counts of granulocyte macrophage- and macrophage-colony forming units were significantly enhanced in the spleen of tumor-bearing adult mice. It is proposed that the DL-growth-dependent increase in the size of the spleen in adult mice is due to an increased blastogenesis of splenocytes, which, however, may not be applicable in the case of old tumor-bearing mice. The role of splenic macrophages in the regulation of the functions of the spleen by macrophage-derived NO is shown.
Age-dependent alterations in the tumoricidal functions of tumor- associated macrophages
(IOS Press BV, 1999) Vineeta Khare; Ajit Sodhi; Sukh Mahendra Singh
Age-dependent tumor cytolytic functions of tumor-associated macrophages (TAM) obtained from mice bearing different stages of Dalton's lymphoma (DL), a spontaneous T cell lymphoma, were studied. Mice were separated into three groups on the basis of their reproductive status as indicator of age: young (prereproductive); adult (reproductive) and old (postreproductive). DL was injected (1 x 105 cells/mouse) intraperitoneally in mice; days 4, 10 and 16 from the day of injection were referred to as early, mid and late tumor stages, respectively. Normal peritoneal macrophages and macrophages isolated from the ascitic fluid of DL-bearing mice (TAM); 1 x 105 cells activated with lipopolysaccharide (LPS) plus interferon-γ (IFN-γ) and assayed for age-dependent alterations in macrophage tumoricidal functions such as: tumor cell binding, cytotoxicity, production of reactive nitrogen intermediates (RNI), expression of inducible nitric oxide synthase (iNOS) and oncostatin-M (OSM) were observed. TAM from old mice were observed to be inhibited with respect to tumor cell binding, cytotoxicity and expression of iNOS and OSM, as compared to macrophages of young and adult mice. TAM obtained from early tumor stages showed augmented tumor cytotoxicity as well as enhanced expression of iNOS and OSM in all the age groups. This effect was most pronounced in the TAM obtained from adult mice and least in the TAM obtained from old mice. The reasons for the observed difference are discussed. These observations should be helpful in understanding the effect of progressive tumor growth and age on the functions of TAM and their responsiveness towards therapeutic manipulations.
Anticancer drug-induced apoptosis in human monocytic leukemic cell line U937 requires activation of endonuclease(s)
(2000) Punya Shrivastava; Ajit Sodhi; Priya Ranjan
Anticancer agents effect tumor cell killing both in vivo and in vitro through the induction of apoptosis. Endonuclease-mediated internucleosomal DNA fragmentation, the most widely used biochemical marker of apoptosis, has been shown to play a central role in apoptosis in many experimental systems. In the present investigation, we report that activation of endonuclease(s) leading to oligonucleosomal DNA fragmentation is common and an essential event in apoptosis, induced by different anticancer drugs, adriamycin, etoposide and cisplatin. The endonuclease inhibitors aurintricarboxylic acid and zinc ion prevented apoptotic cell death in human monocytic leukemic cell line U937, as documented by DNA fragmentation, morphological and nuclear alterations, and cell viability assay. Additional studies suggest endonuclease(s)-mediated DNA fragmentation may not play a central role in apoptosis in the same cell line in response to other inducers such as heat shock and cells may undergo cell death showing all morphological features of apoptosis even in the absence of DNA fragmentation. (C) 2000 Lippincott Williams and Wilkins.
Antigen presentation by cisplatin-activated macrophages: Role of soluble factor(s) and second messengers
(1998) Rana A.K. Singh; Ajit Sodhi
Cisplatin [cis-dichlorodiammine platinum (II)], a potent anti-tumour compound, stimulates immune responses by activating macrophages and other cells of the immune system. The mechanism by which cisplatin activates these cells is poorly characterized. Present investigations were undertaken to study the mechanism of antigen presentation by cisplatin-treated macrophages. Cisplatin-treated macrophages showed a biphasic pattern of antigen presentation to keyhole limpet haemocyanin (KLH)-primed T cells. The second phase of antigen presentation was not due to the continuous presence of cisplatin in the culture medium; rather, it was induced by soluble factors released by cisplatin-treated macrophages. Co-incubation of macrophages with cisplatin and inhibitor of serine/threonine or protein tyrosine phosphatase resulted in an augmentation of cisplatin-induced antigen presentation. In contrast, treatment of macrophages with cisplatin and inhibitor of protein kinase C or protein tyrosine kinase inhibited cisplatin-induced antigen presentation. These observations suggest that antigen presentation by cisplatin-treated macrophages is regulated by reversible action of protein phosphatases and kinases. The antigen-presenting ability of cisplatin- treated macrophages was also inhibited by EGTA, nifedipine, TMB-8, W-7 and calmidazolium, suggesting the probable involvement of Ca2+, calmodulin and calmodulin-dependent kinases in this process.
Ascitic growth of a spontaneous transplantable T cell lymphoma induces thymic involution. 2. Induction of apoptosis in thymocytes
(IOS Press BV, 2000) Anil Shanker; Sukh Mahendra Singh; Ajit Sodhi
It has been observed that the progressive ascitic growth of a transplantable T cell lymphoma of spontaneous origin, designated as Dalton's lymphoma (DL), induces inhibition of various immune responses and is associated with an involution of the thymus accompanied by a massive depletion of the cortical region and alteration in the distribution of thymocytes, with a decrease in CD4+CD8+, CD4+CD8- and CD4-CD8+ thymocytes. Morphological evaluation of thymocytes from DL-bearing mice revealed that with the progression of DL, a majority of thymocytes exhibited morphological features characteristic of apoptotic cell death, which included contracted cell bodies, condensed, uniformly circumscribed and densely stained chromatin, and membrane-bound apoptotic bodies containing one or more nuclear fragments. Quantitative and qualitative analysis of the DNA extracted from the thymocytes of DL-bearing mice revealed DNA fragmentation that increased concomitantly with the progression of DL and showed an oligonucleosomal DNA ladder pattern upon agarose gel electrophoresis, a hallmark of apoptotic cell death. Attempts to identify apoptotic factor(s) showed that the serum of DL- bearing mice contained certain soluble factor(s) that augmented the induction of apoptotis in thymocytes in a time- and dose-dependent manner. Although DL cells or their products, such as DL-cell-conditioned medium or DL-cell-free ascitic fluid, could also induce apoptosis of thymocytes in vitro, the magnitude of the same was consistently lower than that induced by the serum of DL-bearing mice. Further, elucidation of the mechanism of apoptosis induction in thymocytes with respect to the involvement of apoptosis-related genes revealed that the death pathway followed an interleukin-1β-converting- enzyme-dependent, Fas-mediated apoptotic cascade, with a concomitant increase in the protein products of the bax, bad, p53, fas and fasL genes and cleavage of the 23-kD N-terminal fragment of Bcl-2 that exhibited Bax-like death effector properties. Copyright (C) 2000 S. Karger AG, Basel.
Ascitic growth of a spontaneous transplantable T cell lymphoma induces thymic involution: 1. Alterations in the CD4/CD8 distribution in thymocytes
(IOS Press BV, 2000) Anil Shanker; Sukh Mahendra Singh; Ajit Sodhi
We have previously shown that the progressive ascitic growth of a transplantable T cell lymphoma of spontaneous origin in a murine host, designated as Dalton's lymphoma (DL), induces the inhibition of various immune responses. In a quest to understand the mechanism(s) of tumor-growth- dependent immunosuppression, we were interested to investigate if the thymus, the center for the differentiation of immunocompetent T cells, undergoes any alteration concomitant with the growth of DL. Thus, DL was grown as an ascitic tumor in BALB/c mice for a period of 4 or 17 days, designated as the early and late tumor stages, respectively, and the thymuses were examined immediately after sacrifice of the animals on the 4th or 17th day of tumor transplantation. Progressive growth of DL was observed to be associated with thymic atrophy, as well as an involution of thymic organization and a depletion of cell mass. Histological sections of thymus from DL-bearing mice revealed a complete disintegration of the thymic architecture with a massive depletion of the cortical region and disappearance of the corticomedullary junctions. Flow cytometric analysis of alterations in the distribution of thymocytes revealed a decrease in CD4+CD8-, CD4-CD8+ and CD4+CD8+ cell populations, whereas the CD4-CD8- population showed an increase, suggesting an impairment in thymocyte differentiation at an early T cell maturation stage. Furthermore, tumor growth was shown to suppress the proliferation ability of thymocytes. Moreover, an increase in thymocytes of smaller size was also found with the progression of DL, which is an indication that a large fraction of thymocytes of a small, abnormal size could be apoptotic cells. Furthermore, the paper discusses the immunological implications of thymic atrophy in a host bearing a T cell lymphoma. Copyright (C) 2000 S. Karger AG, Basel.
Asp 187 and Phe 190 residues in lethal factor are required for the expression of anthrax lethal toxin activity
(2002) Aparna Singh; Vibha Chauhan; Ajit Sodhi; Rakesh Bhatnagar
Anthrax toxin consists of three proteins, protective antigen, lethal factor, and edema factor. Protective antigen translocates lethal factor and edema factor to the cytosol of mammalian cells. The amino-termini of lethal factor and edema factor have several homologous stretches. These regions are presumably involved in binding to protective antigen. In the present study we have determined the role of one such homologous stretch in lethal factor. Residues 187AspLeuLeuPhe190 were replaced by alanine. Asp187Ala and Phe190Ala were found to be non-toxic in combination with protective antigen. Their protective antigen-binding ability was drastically reduced. We propose that Asp187 and Phe190 are crucial for the expression of anthrax lethal toxin activity. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
Baculovirus P35 inhibits NO-induced apoptosis in activated macrophages by inhibiting cytochrome c release
(2004) Priya Ranjan; Punya Shrivastava; Sukh Mahendra Singh; Ajit Sodhi; Nicholas H. Heintz
The baculovirus protein P35 inhibits apoptosis in a diverse range of animals such as insects, nematodes and mammals. Evidence suggests that P35 can inhibit members of caspase family proteases that are key mediators of mammalian apoptosis. We demonstrate that p35 inhibits activation-induced nitric oxide (NO)-mediated apoptosis in the RAW 264.7 mouse macrophages. Parent or vector-transfected RAW 264.7 cells underwent apoptosis when treated with a combination of cisplatin and interferon-γ (IFN-γ) or LPS and IFN-γ in a NO-dependent manner. By contrast, RAW 264.7 cells stably expressing P35 did not undergo apoptosis when treated with a combination of cisplatin and IFN-γ or LPS and IFN-γ. Activation of parent, vector- or p35-transfected cells with cisplatin and IFN-γ or LPS and IFN-γ caused equivalent levels of inducible nitric oxide synthase (iNOS) expression and produced equal amounts of nitrite, which ruled out attenuated iNOS activity during P35-mediated protection. Rather, expression of P35 inhibited translocation of mitochondrial cytochrome c into cytosol, mitochondrial depolarization, activation of caspase-9 and caspase-3, and cleavage of poly(ADP-ribose)polymerase (PARP). These findings indicate that P35 inhibits NO-induced apoptotic cell death of activated macrophages by inhibiting mitochondrial cytochrome c release, which suggests that P35 has targets upstream of the caspase cascade in apoptosis.
Caspase-9 and Bax/Bcl-2 regulation in ultraviolet B-induced apoptosis of murine peritoneal macrophages
(2004) Ajit Sodhi; Gautam Sethi
This study was performed to determine the effect of UVB radiation on the activation of apoptosis regulatory proteins using murine peritoneal macrophages, which are terminally, differentiated non-dividing cells. UVB (100 mJ/cm 2) irradiation induced apoptosis in murine peritoneal macrophages concurrent with expression of p53, Apaf-1, upregulation of Bax, downregulation of Bcl-2, activation of caspases-9, -3, -2 and DNA fragmentation. Pretreatment of macrophages with serine protease inhibitors TPCK and TLCK inhibited UVB irradiation induced apoptosis. Interestingly, caspase-9 inhibitor Z-LEHD-FMK blocked caspase-2 activation suggesting that caspase-2 activation is not due to death receptor activation but results from activation of other caspases that are dependent on caspase-9 such as caspase-3. The data showed that the regulation of the Bcl-2 family and caspase-9 might work together to activate a caspase-3 mediated apoptotic pathway following UVB irradiation of macrophages.
cis-Dichlorodiammine platinum(II) induced aberrations in mouse bone-marrow chromosomes
(1985) Priti Tandon; Ajit Sodhi
The clastogenic effect of cis-dichlorodiammine platinum(II) (cis-platin) on mouse bone-marrow chromosomes has been studied. Cis-platin was injected at 3 different doses. Cells were fixed at different time intervals after treatment. Different types of aberrations together with the percent of mitotic index and frequency of abnormal metaphases were studied. The aberrations observed were primarily chromatid breaks, although isochromatid breaks, interchanges, and multiple breaks were also observed. A dose- and time-dependent effect was observed for both inhibition of mitotic index and frequency of abnormal metaphases. Trypsin-Giemsa staining of bone-marrow metaphase chromosomes from normal mice was compared with the bands of metaphase chromosomes obtained after Giemsa staining of chromosomes from platinum-treated mice and they were observed to be identical. Bands were present up to 120 h and aberrations were also induced in such plates. © 1985.
Cisplatin and interferon-γ treated murine macrophages induce apoptosis in tumor cell lines
(1997) Priya Ranjan; Ajit Sodhi; Anju Srivastava
Macrophages, treated in vitro with a combination of cisplatin and interferon (IFN)-γ, have been shown to develop enhanced tumoricidal activity against a number of tumor cell types, through mechanisms which remain largely unknown. In the present study, we have investigated the mechanism involved in the tumor cell cytotoxicity mediated by cisplatin and IFN-γ treated macrophages, and the effector molecules involved therein. Peritoneal macrophages treated with cisplatin and IFN-γ, when co-cultured with different tumor cell types, caused tumor cell death by induction of apoptosis. Evidence for this was provided by percent specific DNA fragmentation assay, by specific pattern of internucleosomal DNA fragmentation detected by agarose gel electrophoresis and by microscopic examination of the cells, which revealed nuclear alterations, characteristic of apoptosis. The time kinetics studies of DNA fragmentation, loss in cell viability and apoptotic cell population showed linearity with time; most of the cells that underwent apoptosis were found to be viable even after 24 h co-culture. Macrophages induced apoptosis in tumor targets even in the absence of cell-to-cell contact, i.e. via diffusible effector molecules. In P815 cells, NO produced by cisplatin and IFN-γ treated macrophages was found to induce apoptosis as addition of N(G)-monomethyl L-arginine (L-NMMA), a specific inhibitor of NO synthase to the co-culture, prevented apoptosis in P815 cells. Further, direct treatment of P815 cells with the NO donor, sodium nitroprusside (SNP), resulted in apoptosis. In L929 cells, the effector molecule was found to be tumor necrosis factor (TNF)-α as apoptosis was blocked by the addition of anti-TNF-α antibodies to the co-culture but the addition of L-NMMA or SNP had no effect. The study thus shows that cisplatin and IFN-γ treated macrophages can kill tumor cells by extracellular release of effector molecules which act by inducing apoptosis in a target cell-specific manner.
Cisplatin primes murine peritoneal macrophages for enhanced expression of nitric oxide, proinflammatory cytokines, TLRs, transcription factors and activation of MAP kinases upon co-incubation with L929 cells
(2009) Puja Chauhan; Ajit Sodhi; Anju Shrivastava
Cisplatin, a chemotherapeutic drug, may also act as a biological response modifier. Cisplatin (10 μg/ml) treatment of macrophages for 24 h activates them to produce enhanced amounts of nitric oxide (NO), ROI, proinflammatory cytokines and exhibit increased tumoricidal activity, which may or may not be contact mediated. In the present investigation, we report that the treatment of macrophages with cisplatin for a short period of 2 h is sufficient to make them more receptive to interaction with tumor cells. Macrophages pretreated with cisplatin for 2 h, and co-incubated with L929 cells, produced enhanced NO, TNF-α, IL-1β, IL-12 and IFN-γ. Production of NO, TNF-α, IL-1β, IL-12 and IFN-γ was maximum at 24 h of co-incubation. Enhanced transcription of iNOS, TNF-α, IL-1β, IL-12 and IFN-γ genes in cisplatin-pretreated macrophages were observed between 12 and 24 h of co-incubation with L929 cells. Cisplatin-treated macrophages on co-incubation with L929 cells also expressed enhanced transcription of Toll-like receptor (TLR)-2 and TLR-4 genes and their proteins. It is observed that cisplatin-pretreated macrophages on co-incubation with L929 cells showed activation of mitogen-activated protein (MAP) kinases and NF-κB. Pharmacological inhibitors like PD98059, SB202190 and wortmannin strongly inhibited the production of NO and proinflammatory cytokines suggesting the probable role of p42/44, p38 MAPK and PI3K in the above process. The c-Jun amino terminal kinase (JNK) inhibitor SP600125 was less effective in inhibiting the production of NO and proinflammatory cytokines. The data thus suggests that pretreatment of macrophages with cisplatin makes them biologically more responsive to interaction with L929 cells and become activated. © 2008 Elsevier GmbH. All rights reserved.
Cisplatin-induced activation of murine bone marrow-derived macrophages require protein tyrosine phosphorylation
(Elsevier Ltd, 1998) Shishir Shishodia; Ajit Sodhi; Anju Shrivastava
The aim of the present study is to evaluate the involvement of tyrosine phosphorylation in the signal transduction mechanism of cisplatin-induced macrophage activation in vitro. Stimulation of bone marrow-derived macrophages (BMDM) with cisplatin (CP) resulted in a time- and dose-dependent phosphorylation of several proteins having estimated molecular weights of approximately 18, 20, 21, 30, 33, 35, 39, 41, 44, 58 and 123 kD, detected by immunoblot using anti-phosphotyrosine antibody. CP-induced tyrosine phosphorylation was inhibited by the tyrosine kinase inhibitor genistein. Using this inhibitor, we were able to correlate tyrosine phosphorylation with several functional effects of CP on murine bone marrow-derived macrophages (BMDM). Treatment of macrophages with genistein before incubation with CP completely inhibited the CP-induced tumoricidal activation of macrophages as well as production of TNF and NO, whereas pre-treatment of macrophages with phosphatase inhibitor sodium vanadate upregulated macrophage activation in addition to enhanced protein tyrosine phosphorylation. Taken together, these data suggest that tyrosine phosphorylation play a critical regulatory role in the activation of macrophages with CP.
Cisplatin-stimulated murine bone marrow-derived macrophages secrete oncostatin M
(Nature Publishing Group, 1997) Ajit Sodhi; Shishir Shishodia; Anju Shrivastava
Cisplatin (CP), a widely used anticancer drug activates cells of the immune system to a tumoricidal state, and thus functions as a potent biological response modifier. Expression of oncostatin M (OSM), a novel cytokine having a growth regulatory effect, was studied in bone marrow- derived macrophages treated with cisplatin. Supernatants from CP-stimulated macrophages were found to be cytostatic for OSM-sensitive A375 melanoma cells. Immunoblot analysis with anti-OSM antibody revealed that expression of OSM in macrophages upon CP stimulation is a rapid process and within 30 min of CP treatment, a significant amount of OSM is secreted into the culture supernatant. These results therefore indicate that CP can stimulate murine bone marrow-derived macrophages to produce OSM which can be implicated as one of the cytostatic/cytocidal factors in the antitumour action of cisplatin- stimulated macrophages.
Cisplatin-treated macrophages produce oncostatin M: Regulation by serine/threonine and protein tyrosine kinases/phosphatases and Ca2+/calmodulin
(1998) Rana A.K. Singh; Ajit Sodhi
In the present study it was investigated whether cisplatin-treated murine peritoneal macrophages produce oncostatin M (OSM) and what is the underlying mechanism. The culture supernatants of cisplatin-treated macrophages significantly inhibited the proliferation of OSM-sensitive cell line A375. Within 15 min of cisplatin treatment significant OSM was synthesized and secreted by macrophages. Inhibitors of serine/threonine and protein tyrosine phosphatases augmented cisplatin-induced OSM production of macrophages. The protein kinase C and protein tyrosine kinase inhibitors significantly inhibited OSM production of cisplatin-treated macrophages. The OSM production of cisplatin-treated macrophages was also inhibited in the presence of Ca2+ chelators, Ca2+ channel blocker and calmodulin/calmodulin-dependent kinase inhibitors. These data suggest that OSM production of cisplatin-treated macrophages is regulated by opposing actions of phosphatases and kinases. It is also suggested that OSM production of cisplatin-treated macrophages is dependent on Ca2+, calmodulin and calmodulin-dependent kinase.