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Possible role of P-glycoprotein in cyclophosphamide resistance of transplanted mouse RLS lymphosarcoma.

The causes of different sensitivity of mouse LS lymphosarcoma and its resistant RLS variant to cyclophosphamide were studied. Division of LS and RLS cells stops in the G2/M phase 24 h after cyclophosphamide treatment, but this stop lasts for more than 48 h in LS cells and less than 24 h in RLS cells. DNA fragmentation, a marker of apoptosis, is observed only in LS cells starting from 24 h after cyclophosphamide treatment. LS and RLS strains do not differ by the expression of bcl-2, bcl-6, bax, bad, mdr1a, mdr1b genes and P-glycoprotein protein. The strains differ by transport activity of P-glycoprotein, tested by SYTO 16 substrate release from cells: activity of P-glycoprotein in RLS cells was 2-fold higher than in LS cells. Presumably, the resistance of RLS tumor to cyclophosphamide-induced apoptosis is a result of inhibition of the apoptotic cascade by P-glycoprotein which is functionally more active in these cells than in LS cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Pathogenesis of hypercalcemia in lymphosarcoma cell leukemia. Role of an osteoclast activating factor-like substance and a mechanism of action for glucocorticoid therapy.

The pathogenesis of hypercalcemia and mode of action of glucocorticoid therapy was examined in a patient with lymphosarcoma cell leukemia. Circulating neoplastic cells were cultured in vitro and secreted a bone-resorbing factor. The bone-resorbing factor was partially purified with the use of a bioassay for bone resorption, and was found to be chromatographically and pharmacologically similar to osteoclast activiating factor (OAF), which is produced by normal mitogen-activated peripheral blood lymphocytes. Other factors which stimulate bone resorption, such as parathyroid hormone, prostaglandins and the vitamin D metabolites, were excluded by criteria which included dose-response curves, radioimmunoassays, extraction in organic solvents and failure of glucocorticoids to inhibit bone-resorbing activity. The patient's hypercalcemia responded rapidly to prednisone therapy. The effects of the bone-resorbing factor secreted by the neoplastic cells on bone cultures to which cortisol was added were examined. Cortisol inhibited bone resorption directly at low doses (10(-8) M), which suggests that prednisone may have lowered the serum calcium in this patient by direct inhibition of bone resorption.

Aged↗

Glycosaminoglycans of solid and ascites forms of the P1798 murine lymphosarcoma.

Total glycosaminoglycan levels are similar from subcutaneous, ascites and mesenteric forms of the P1798 lymphosarcoma. However, P1798 cells implanted subcutaneously produce a solid tumor rich in hyaluronic acid with lesser amounts of chondroitin 4-/6-sulfates as well as an undersulfated species of chondroitin sulfate, while cells implanted intraperitoneally produce ascites tumors which generate hyaluronic acid, almost exclusively. Mice bearing advanced ascites tumors develop solid mesenteric tumors which exhibit chondroitin 4-/6-sulfates and under-sulfated chondroitin sulfate in addition to hyaluronic acid.

Animals↗

A new vasopeptide formed by the action of a Murphy-Sturm lymphosarcoma acid protease on rat plasma kininogen.

A new vasoactive peptide, formed by the action of a Murphy-Sturm lymphosarcoma acid protease on rat plasma kininogen was purified by gel filtration on Sephadex G-50 (fine) and fractions assayed on the isolated rat uterus for smooth muscle stimulating activity. The most active fraction was purified further by CM-cellulose chromatography. High voltage electrophoresis showed the peptide to be one component (Mgly 2.49) with an electrophoretic mobility different from bradykinin, lysyl-bradykinin and methionyl-lysyl-bradykinin. The molecular weight of the peptide was estimated on Sephadex G-25 column to be 1460. The amino acid composition was determined and the carboxyl terminal sequence identified by carboxypeptidase Y treatment to be Pro-Phe-Arg-Leu. Dansyl-Edman procedure yielded an amino terminal sequence of Ile-Ser-Arg-Pro. The peptide produced a dose-dependent contraction of the isolated guinea pig anterior mesenteric vein and relaxed the rabbit superior mesenteric artery contracted by phenylephrine.

Amino Acids↗

DNA-DNA interstrand crosslinking by dimethyanesulphonic acid esters. Correlation with cytotoxicity and antitumour activity in the Yoshida lymphosarcoma model and relationship to chain length.

Members of the homologous series of nine antitumour dimethanesulphonic acid esters, with the exception of ethylene dimethanesulphonate (EDMS), were found to cause DNA-DNA interstrand crosslinking in cells derived from the transplantable rodent Yoshida lymphosarcoma. The ability of the series to induce interstrand crosslinks was compared with in vitro cytotoxicity and in vivo antitumour activity and is discussed in relation to their chain length and ability to span critical target distances in DNA.

Animals↗

Rodent kinin-forming enzyme systems--II. Purification and characterization of an acid protease from Murphy-Sturm lymphosarcoma.

An acid protease from the rat Murphy-Sturm lymphosarcoma (MSLS) tumor was purified 640-fold by extraction of the tumor tissue, acid precipitation with glacial acetic acid, ammonium sulfate precipitation, DEAE-Sephadex A-50 batch adsorption, QAE-Sephadex A-50 column chromatography, Sephadex G-200 gel filtration, and CM-32 cellulose chromatography. The protease hydrolyzed bovine hemoglobin and formed vasopeptide kinins when incubated with purified rat plasma kininogen. Two protease fractions obtained by Sephadex G-200 gel filtration had identical molecular weights of 39,500-41,000 and were similar in other physico-chemical and kinetic characteristics. The purified enzyme showed three major isozymic forms (alpha, beta and gamma) with isoelectric points (pI) of 5.2, 5.5 and 5.8, respectively, and nearly identical amino acid compositions. The enzyme had a high moles percent of both aspartic and glutamic acids. The carbohydrate moiety of the enzyme contained 2 moles of N-acetylglucosamine and 8 moles of mannose per mole of enzyme. The pH optimum for the digestion of bovine hemoglobin was approximately 3.0 with a sharp decline of activity on either side of the pH optimum. The protease activity was very stable above pH 3.4. The Km values for the purified enzyme fractions A and B were 31.17 and 31.19 microM, respectively, and the corresponding Vmax values were 6.17 and 5.5 microM tyrosine per mg per min at 37 degrees and pH 3.0. The enzyme was inhibited strongly by pepstatin (Ki = 31 X 10(-9)M and alpha = 0.1). The acid protease released kinin from purified rat plasma kininogen at an initial rapid rate which plateaued at 460 ng bradykinin equivalents/mg substrate after a 2-hr incubation at 37 degrees.

Amino Acids↗

Modulation by a human interferon of antitumor effects of cyclophosphamide against a lymphosarcoma in hamsters.

Administration to hamsters of a highly purified human leukocyte interferon subtype, IFN-alpha A, obtained by recombinant DNA methods, abolished the efficacy of high doses of cyclophosphamide (2.5 mg/hamster) against the TBD 932 lymphosarcoma. The effect was more pronounced with concomitant than with sequential treatments and did not occur with melphalan. Antagonistic effects occurred at high interferon doses (10(5) I.U./treatment), but an additive or synergistic positive effect occurred at lower interferon doses (10(3) I.U./treatment) and at lower, non-protective, doses of cyclophosphamide. These effects may be due to immunomodulatory responses induced by the drugs involved.

Animals↗

Thymic lymphosarcoma with metastases causing spinal cord compression and pelvic limb paresis in a heifer.

Neurological examination of a heifer displaying pelvic limb ataxia and paresis progressing to a dog-sit position but with normal thoracic limb function indicated a spinal cord lesion in the low thoracic/high lumbar region. The progressive neurological deterioration despite normal radiological and cerebrospinal fluid findings were suggestive of a non-inflammatory, non-traumatic extradural compressive lesion; this was subsequently shown to be a lymphosarcoma.

Animals↗

Effect of aprotinin, EACA and heparin on growth and vasopeptide system of Murphy-Sturm lymphosarcoma.

The effect of aprotinin, EACA and heparin on the growth of the transplanted rodent Murphy-Sturm lymphosarcoma and on several components of the tumor kinin-forming enzyme system was studied. Therapy was administered for 15 days, 3 times daily, one day after tumor transplant. Tumor weights and biochemical parameters (prekallikrein, kininogen and kininase) were measured on the 8th, 10th, 12th and 15th day of therapy. Both aprotinin and heparin significantly inhibited (p less than 0.01) tumor growth by the 15th day, compared to control, saline-administered animals. EACA did not affect the tumor growth rate at any time period. Tumor prekallikrein and kininogen levels were significantly higher (p less than 0.01) in the aprotinin-treated animals. Kininogen levels were higher in the EACA-treated tumors during the latter phase of growth. None of the agents affected the increase in tumor kininase activity that occured during the growth of the tumors. The tumor inhibition and biochemical data suggest the involvement of proteases in the neoplastic process.

Aminocaproates↗

Metabolic activity of the Sticker's lymphosarcoma.

Some parameters (glycolysis, respiration, levels of glycolytic enzymes) of the lymphoid cells from the Sticker's lymphosarcoma were established in order to better define the biochemical behavior of the venereal tumor of the dog. For comparative purposes lymphocytes from peripheral blood of normal and tumor-bearing dogs were also studied. Lactic acid produced by the tumor cells during aerobic glycolysis is liberated in the reaction medium. Oxygen uptake is enhanced in the presence of succinate, but not with pyruvate, alpha-ketoglutarate, or malate as substrates. Higher levels of some of the enzymes from the glycolytic pathways as well as differences on the physicochemical and kinetic properties of the glycolytic regulatory enzymes are found in Sticker's tumor cells, when compared with the lymphocytes from peripheral blood of normal and tumor-bearing dogs. A fructose-bisphosphate positively modulated pyruvatekinase is found in the tumor cells.

Animals↗

Cutaneous lymphosarcoma with abnormal chromosomes in a dog.

A poorly differentiated cutaneous lymphosarcoma with delayed multicentric anatomical distribution was diagnosed in a dog. The neoplasm had cells with chromosome numbers of 58 or 67 and the former cells lacked the subtelocentric marker chromosome seen in cells of canine transmissible venereal tumour with 58 chromosomes.

Animals↗

Primary lymphosarcoma of prostate.

A case of primary lymphosarcoma of the prostate in a seventy-one-year-old patient is presented. He had palliative surgical treatment and radiotherapy but died seven months later of heart failure with signs of metastatic disease. Treatment of this condition should include surgery and irradiation. Only its early discovery might change the prognosis.

Aged↗

Surface proteins of radiation-induced and radiation leukemia virus-induced thymic lymphosarcomas in mice.

Thymic lymphosarcomas (TLS) were induced in C57BL mice by X-rays or by Radiation Leukemia Virus (RadLV) and their surface glycoproteins (gps) compared after cell-surface radioiodination and polyacrylamide gel electrophoresis (SDS-PAGE). All lymphocytic antigens tested (T200, 170/100, Thy-1) and proteins with apparent molecular weight (Mr) around 120,000 and 100,000 were present on all tumours, as well as retrovirus--encoded proteins but considerable variation in the Mr of several serologically-related proteins was observed. Therefore, the TLS in C57BL mice form a heterogeneous group, suggesting that T cells can be transformed at different stages of maturation. The possibility that transformation allows or even triggers differentiation is also entertained.

Animals↗

Thymic lymphosarcomas obtained by X-rays in association with a weakly leukemogenic virus: cellular studies.

The association in C57BL/6 mice of a subleukemogenic radiation dose (1.75 Gy X 2) which induces 7% of thymic lymphosarcomas (TL) with the injection of a weakly oncogenic B-tropic retrovirus responsible for 5% of TL resulted in a higher incidence of TL (31%) than expected from a simple cumulative effect when the viral injection preceded the irradiations (VX protocol). When virus was injected after irradiation (XV protocol) TL incidence (19%) was not significantly different from that of a cumulative phenomenon. The B-tropic virus used (1223) was isolated from RadLV-Rs extract and cloned. The TL incidence correlates with the presence of virus firstly in the thymus and bone marrow (BM) during the preleukemic period, secondly in the cell lines established in vitro from TL obtained in both protocols. This suggests that B-tropic viruses derepressed by 4 radiation doses of 1.75 Gy might be similarly implicated in the mechanism of radio-induced TL. This hypothesis is further supported by the evidence that BM restoration inhibited leukemogenesis in processes induced either by 4 radiation doses of 1.75 Gy or by the association of 2 radiation doses and viral injection whereas it has no effect on TL induced by highly oncogenic thymotropic viruses. Transplantation of BM cells from animals which had been submitted shortly before to leukemogenic VX protocol failed to induce donor type TL or leukemias in irradiated recipients suggesting that preleukemic cells either are not present or cannot be detected. However a high incidence of recipient TL was observed indicating that viruses were transferred with the grafted cells.

Animals↗

Biochemical and functional characterization of lymphocytes from a horse with lymphosarcoma and IgM deficiency.

Neoplastic lymphocytes from a horse with lymphosarcoma and IgM deficiency were analyzed for ability to grow in culture; surface and cytoplasmic IgM; functional activity in blastogenesis, cytoxicity, and suppressor assays; and activities of six enzymes involved in purine and pyrimidine metabolism. The cells lacked surface and cytoplasmic IgM. They had elevated activity of adenosine deaminase and reduced activity of purine nucleoside phosphorylase. Neoplastic cells were nonresponsive in blastogenesis assay and did not kill allogeneic lymphocyte target cells or YAC-1 targets in a lectin-dependent cytotoxicity assay, however, the cells were active in a suppressor assay. They were grown for 16 weeks in cultures supplemented with interleukin 2, during which time the cells retained suppressive activity. These results are consistent with a T cell lymphoma of suppressor cell origin, and may explain the deficiency of IgM observed in some horses with lymphoreticular neoplasms.

Animals↗

Immunologic studies of a horse with lymphosarcoma.

Immunological, clinical, and pathological investigations were conducted on a horse with lymphosarcoma. The immunological status was investigated by measuring the level of antibodies by single radial immunodiffusion test and the ability of lymphocytes to proliferate in response to mitogens. Multiple immunological abnormalities were noted in this horse. They were; (1) decreased IgM, IgG, and IgA levels in the serum despite hyperproteinemia; (2) increased in-vitro spontaneous lymphoproliferation which reflects augmented mitosis; (3) decreased lymphoproliferative response to T cell stimulants (e.g. Concanavalin-A (Con-A)) suggesting impaired T cell activation; (4) presence of immunosuppressive factors in serum as demonstrated by in-vitro lymphocyte culture systems. Clinical pathology findings revealed an unusual monoclonal alpha peak in the serum and morphologically abnormal lymphocytes distributed throughout the body. Serum fractionated by fast protein liquid chromatography (FPLC) revealed that the immunosuppressive factors were found in this abnormal alpha peak. The immunopathological findings in this horse are discussed.

Animals↗

Differentiation analysis of bovine T-lymphosarcoma.

The tumor cells from three different types (calf, skin and thymic) of bovine lymphosarcoma identified as sporadic bovine leukosis (SBL) were transplanted to nude mice and established as lymphoid tumor lines. To clarify the T-cell lineage, clonality and differentiation stage, these cell lines were examined for the immunophenotypic profile, the expression and the gene rearrangement of T-cell receptor (TCR) genes. The tumor cells from all three types showed alpha-naphthyl acetate esterase-positive staining and the absence of surface immunoglobulin (sIg). Moreover, the tumor cells appeared to be all BoCD5+ BoCD6+ BoCD4- BoCD8- cells in the FACS analysis with mAbs. Rearrangement of TCR-beta and -delta, but not of TCR-alpha and -gamma, genes was found to be unique for each tumor line showing T-cell clonality. Mature or truncated TCR-beta, -gamma and -delta transcripts were detected in the tumor cells, but all of them were found to be non-functional in cDNA cloning analysis. These results suggested that tumor cells from SBL are immature double-negative T-cells expressing non-functional TCR gamma delta transcripts to somewhat differentiated degrees.

Amino Acid Sequence↗

Glucocorticoids repress ribosome biosynthesis in lymphosarcoma cells by affecting gene expression at the level of transcription, posttranscription and translation.

Growth arrest of P1798 murine lymphosarcoma cells by glucocorticoids is accompanied by a remarkable decrease in transcription of rRNA and translation of mRNAs encoding basic ribosomal proteins (rps). Here we report that the expression of other genes involved in ribosome biogenesis is repressed in dexamethasone-treated P1798 cells. These include posttranscriptionally regulated decline in the abundance of the mRNA and primary transcript of nucleolin; abrupt drop in the transcription rate of U3 small nucleolar RNA; and inhibition of translation of mRNAs coding for P2 and L5, acidic and basic rps, respectively. Normal expression of these genes is resumed upon hormonal withdrawal.

Animals↗