Cortisol-induced lymphocytolysis of P1798 tumor cells in glucose-free, pyruvate-free medium.

Exposure of corticoid-sensitive P1798 tumor lymphocytes to cortisol resulted in progressive cell dissolution either with or without exogenous glucose and pyruvate. Therefore, inhibition of glucose transport is not required for cortisol-induced lymphocytolysis.     

Modulation of the effects of fluoropyrimidines on toxicity and tumor inhibition in rodents by uridine and thymidine

Uridine and/or thymidine were administered concomitantly with 5-fluorouracil (5-FU) and 5'-deoxy-5-fluorouridine (5'-dFUR) to mice and rats in order to establish whether the physiological nucleosides acting in vitro as antagonists can diminish fluoropyrimidine toxicity in vivo. In addition, the influence of orally co-administered uridine on antitumor activity of 5-FU and 5'-dFUR in mice has been studied. All co-administrations aggravated the general toxicity of both fluoropyrimidines. Tumor inhibition was enhanced by uridine, but the therapeutic ratio was not improved compared to monotherapy with either 5-FU or 5'-dFUR.     

Further observations on the inhibition of tumor growth by C. parvum with cyclophosphamide. VII. Effect of treatment prior to primary tumor removal on the growth of distant tumor.

The present investigations were directed toward determining whether primary tumor manipulation prior to its removal is advantageous for the control of metastases and survival. Studies were carried out to ascertain whether 1) there is justification for delaying surgical removal of a primary tumor to permit preoperative administration of cyclophosphamide (CY) and/or C. parvum (CP) and 2) there is an advantage to administering the immunotherapy directly into a primary tumor. After operation, in all investigations, systemic CP and CY was used. Despite the putative similarity of animals, tumors and treatment regimens there was marked variation in response of tumors to therapy. No benefit was derived from administering preoperative immunotherapy alone. When operation was delayed to employ systemic immuno-chemotherapy, a slight improvement in the control of distant tumor was noted. The employment of preoperative intratumor immunotherapy led to a greater prolongation of survival and more inhibition of distant tumor growth than did immediate primary tumor removal or the use of preoperative systemic immunotherapy. The results suggest that there may be an advantage to delaying removal of a primary tumor so that it may be employed in therapeutic strategies directed toward control of metastatic disease.     

Resistance and cross-resistance of cultured leukemia P388 cells to vincristine, adriamycin, adriamycin analogs, and actinomycin D.

Cultured P388 cells derived from leukemia P388 passaged in vivo in (C57BL X DBA/2)F1 mice were approximately one-tenth less sensitive to N-trifluoroacetyladriamycin-14-valerate (AD32) and cinerubin A, inasmuch as the concentrations of these agents had to be increased tenfold to produce a reduction in cell viability of the same order of magnitude as that produced by adriamycin, daunomycin, or actinomycin D. Cultured P388 cells derived from resistant cell populations developed in vivo retained their resistance to vincristine. These resistant cells exhibited cross-resistance to actinomycin D, adriamycin, daunomycin, and AD32, but cross-resistance to cinerubin A could not be detected. Data also showed that the vincristine-resistant cells were more sensitive to AD32 (2.8 x 10(-6) M) than to adriamycin (3.4 x 10(-6) M) during a 6-hour exposure of cells to agents.     

Cell-mediated inhibition of tumor colony formation in agarose by resting and interleukin 2-stimulated human lymphocytes

Human nonadherent peripheral blood mononuclear cells (PBMC) isolated from nonimmunized donors were preincubated for 18 h in medium alone or medium containing the lymphokine interleukin 2 and subsequently cocultured with tumor cells derived from malignant tumor cell lines or from fresh human tumors. The cell suspensions were subsequently inoculated into agarose; 14 days later, new tumor colony formation was determined. Although the different tumor cells displayed a wide range of sensitivity to the PBMC, in each instance, the number of colonies formed by the tumor cells exposed to the PBMC was consistently reduced relative to that of control cells. The inhibitory effect on the colony-forming cells was especially pronounced with PBMC preincubated with interleukin-2 and was dependent on the ratio of tumor cells to PBMC in the culture. This assay system provides an alternative to the standard 51Cr release assays in assessing the immunomodulatory effects of lymphokines and in quantitating the cytolytic or cytostatic activity of various effector cells against neoplastic stem cells from established cell lines and from heterogeneous cell preparations derived from fresh human tumors.     

Immunogenicity of solubilized tumor antigen extracted from P1798 murine lymphoma cells or isolated from tumor-bearer ascites fluid and reactivity with anti-thy-1.2 antiserum.

Solubilized antigen was prepared from P1798 lymphoma cells by sonication, 3 M KCI extraction, or isolated from the ascites fluid of syngeneic tumor-bearing BALB/c mice. Antigen was detected and quantitated by its ability to block activity of anti-P1798 serum raised in syngeneic mice, as assayed by cytotoxic and indirect immunofluorescence tests. It was established that the reaction was immunologically specific as the P1798 antigen did not inhibit the binding to L1210 lymphoma cells of antisera raised against L1210 in syngeneic DBA/2 or allogeneic BALB/c mice. Vaccination of BALB/c mice with different subcellular fractions of sonicated antigen or with ascites fluid resulted in protection against a live P1798 challenge with results comparable to those obtained using iodoacetamide-modified tumor cells. Solubilized antigen prepared by each of the three methods eluted from a Bio-Gel A5m agarose column exclusively in an early peak that had a molecular weight estimated to be greater than 2 X 10(6). This column-fractionated antigen was shown to cross-react with antiserum raised against Thy-1.2 antigen, which is present on P1798 cells. The purified P1798 antigen sedimented at 200,000 g and was shown to protect syngeneic mice in immunoprophylactic tests.     

Production of tumor necrosis factor-alpha by normal and malignant B lymphocytes in response to interferon-alpha, interferon-gamma and interleukin-4.

Since autocrine stimulation by tumor necrosis factor-alpha (TNF alpha) may be implicated in the proliferation of normal and malignant B cells, we measured the production of TNF alpha protein by these cells in response to various B-cell stimulatory agents. Purified malignant and non-malignant B lymphocytes were incubated with interleukin-4 (IL4), interferon-alpha (IFN alpha) and IFN gamma, and the supernatants were tested for the production of TNF alpha using an enzyme-linked immunosorbent assay (ELISA). Chronic lymphocytic (CLL) and prolymphocytic (PLL) leukemia cells produced low amounts of TNF alpha, irrespectively of the addition of inducers. Normal B lymphocytes (tonsillar and blood) produced TNF alpha, but the level was not influenced by any of the inducers tested. Hairy cell leukemia (HCL) cells produced TNF alpha in the absence of stimuli and this production was markedly enhanced by addition of IFN alpha or, to a lesser extent, by IFN gamma and IL4. These results contradict the hypothesis that IFN alpha exerts its therapeutic action in HCL by inhibition of autocrine TNF alpha production.     

Ras inhibition by FTS attenuates brain tumor growth in mice by direct antitumor activity and enhanced reactivity of cytotoxic lymphocytes

A major concern in targeted drug therapy is that the inhibition of receptors and signaling molecules in tumor cells may also affect similar components in the tumor microenvironment or in the immune system, with undefined consequences for inhibition of tumor growth. One example is given by the Ras inhibitor salirasib (Farnesythiosalycilic acid, FTS), which in addition to its antitumor activity in mice and humans also exhibits anti-inflammatory activity. Here we show three major effects through which Ras inhibition by FTS provides a favorable antitumor environment in immune-competent mice with subcutaneous or intracranial tumors. First, FTS exhibited antitumor activity in intracranial immune-competent tumor-bearing mice and increased their survival relative to tumor-bearing immune-compromised mice. Second, FTS induced an increase in regulatory T cells in mouse splenocytes, in which Foxp3+ T cells did not interfere with the tumor growth inhibitory effects of FTS. Third, FTS induced an increase in antitumor cytotoxic T-cell reactivity in glioma cells by downregulating their own expression of Foxp3. This downregulation induced a TGF-β-associated mechanism in glioma cells altering the tumor microenvironment and causing reduced resistance of the tumor to the immune system. These results are important as they might explain some of the major beneficial effects of Ras inhibitors. They may provide an experimental framework for examination of the impact of other anticancer drugs on cancer and the immune system.     

Biochemical correlates of mTOR inhibition by the rapamycin ester CCI-779 and tumor growth inhibition.

The rapamycin ester, CCI-779, potently inhibits cell growth in vitro, inhibits tumor growth in vivo, and is currently in Phase I clinical trials. To further understand the relationship between plasma systemic exposure and inhibition of the target Ser/Thr kinase, mTOR/FRAP, two assays have been developed. The first assay involves determination of the 4E suppressor protein (4E-BP1) bound to eukaryotic initiation factor 4E (eIF4E), and the second is direct Western analysis of phosphorylation of residue Thr(70) of 4E-BP1. Under normal growth conditions in vitro, rapamycin caused rapid association of 4E-BP1 with eIF4E within 1 h in Rh30 and GC(3) human tumor cells. Association was persistent up to 16 h. In mice, administration of rapamycin (5 or 20 mg/kg) caused rapid association of 4E-BP1 with eIF4E within 4 h in both human colon adenocarcinoma GC(3) and rhabdomyosarcoma Rh30 xenografts. Using phospho-specific antibody against Thr(70) of 4E-BP1, rapid and persistent dephosphorylation within 30 min of exposure to rapamycin was detected in Rh18 rhabdomyosarcoma cells. Evaluation of CCI-779 against Rh18 xenografts showed this tumor to be growth inhibited at daily dose levels of > or =8.7 mg/kg. Because immunoblotting may be more suitable for assaying tumor biopsy tissue, a "blinded" comparison between the effect of CCI-779 on Thr(70) phosphorylation and growth inhibition of human tumor xenografts was undertaken. Mice were treated daily for 5 days with CCI-779 (20 mg/kg/day) or with drug vehicle, and tumor diameters were measured. Tumors were excised 1 h after the final administration and frozen, and phospho Thr(70) was determined by Western blot analysis. The correlation coefficient for decreases in Thr(70) phosphorylation and growth inhibition was high (r(2), 0.99). The results indicate that an assay of decreases in phosphorylation of Thr(70) of 4E-BP1 may be a useful surrogate for determining the inhibition of mTOR activity in tumor specimens.     

Had-1, a uridine 5'-diphosphogalactose transport-defective mutant of mouse mammary tumor cell FM3A: composition of glycolipids, cell growth inhibition by lactosylceramide, and loss of tumorigenicity

Glycolipid compositions of mouse mammary tumor cell FM3A and its Newcastle disease virus-resistant mutant cell, Had-1, which was also characterized as a defective mutant of UDP-galactose transport to Golgi apparatus, have been studied. The major neutral glycolipid in FM3A was Gal beta 1-4Glc beta 1-1Cer (LacCer) (95%) and the rest was Glc beta 1-1Cer. The concentration of neutral glycolipids in Had-1 was only about one-fifth of that in FM3A. GlcB1-1Cer in Had-1 accounted for 79% of neutral glycolipids and the rest was LacCer, the content of which was decreased to 4% of that in FM3A. Ganglioside patterns of the two cell lines were similar, although gangliosides with N-glycolylneuraminic acid were increased in Had-1 cells compared with that in FM3A cells. The presence of NeuAc alpha 2-3-Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer, NeuAc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-2Cer, GM3, and GD3 was demonstrated by thin-layer chromatography immunostaining. 125I-Labeled Newcastle disease virus bound only poorly to gangliosides extracted from either FM3A or Had-1 cells on a high performance thin-layer chromatography plate. The effects of glycolipids on the growth of the two cell lines were also studied. Had-1 cells were more sensitive to glycolipids added exogenously than FM3A cells. Addition of GM3 had a stimulative effect on cell growth of Had-1. LacCer, Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc beta 4-1Cer, and Glc beta 1-1Cer inhibited the growth of Had-1 cells. LacCer was the most potent inhibitor. LacCer immobilized on the culture plate also inhibited the growth of Had-1 cells. The inhibitory effect was recovered completely overcome by transferring the cells to LacCer-free medium. Had-1 cells were not tumorigenic in C3H/He mice, and furthermore the tumorigenic activity of FM3A cells was suppressed by the prior administration of Had-1 cells.     

Stimulation of thymus- and bone marrow-derived lymphocytes by tumor cells in culture.

In vitro lymphocyte stimulation by mitomycin-blocked tumor cells can be used to measure tumor-specific immune responses. In order to determine the responding cell type(s) in this reaction, lymph node and spleen cell populations were specifically depleted of thymus- or bone marrow-derived cells by the use of the appropriate antisera and complement or by immunoadsorption of the Fc receptor-bearing cells to antibody-coated sheep red blood cell monolayers. The compositions of both the original and the modified lymphocyte populations were determined by (a) viability counting following treatment with antisera and complement, (b) direct and indirect immunofluorescence, (c) antibody-coated erythrocyte rosette formation, and (d) response to thymus- and bone marrow-derived cell mitogens. In the lymph node cell populations, only the thymus-derived cells were stimulated by the tumor cells. However, both bone marrow- and thymus-derived cells from tumor-immune spleens underwent stimulation when exposed to tumor cells in culture.     

Sequential loss of tumor vessel pericytes and endothelial cells after inhibition of platelet-derived growth factor B by selective aptamer AX102

Inhibition of platelet derived growth factor (PDGF) can increase the efficacy of other cancer therapeutics, but the cellular mechanism is incompletely understood. We examined the cellular effects on tumor vasculature of a novel DNA oligonucleotide aptamer (AX102) that selectively binds PDGF-B. Treatment with AX102 led to progressive reduction of pericytes, identified by PDGF receptor beta, NG2, desmin, or alpha-smooth muscle actin immunoreactivity, in Lewis lung carcinomas. The decrease ranged from 35% at 2 days, 63% at 7 days, to 85% at 28 days. Most tumor vessels that lacked pericytes at 7 days subsequently regressed. Overall tumor vascularity decreased 79% over 28 days, without a corresponding decrease in tumor size. Regression of pericytes and endothelial cells led to empty basement membrane sleeves, which were visible at 7 days, but only 54% remained at 28 days. PDGF-B inhibition had a less pronounced effect on pancreatic islet tumors in RIP-Tag2 transgenic mice, where pericytes decreased 47%, vascularity decreased 38%, and basement membrane sleeves decreased 21% over 28 days. Taken together, these findings show that inhibition of PDGF-B signaling can lead to regression of tumor vessels, but the magnitude is tumor specific and does not necessarily retard tumor growth. Loss of pericytes in tumors is an expected direct consequence of PDGF-B blockade, but reduced tumor vascularity is likely to be secondary to pericyte regression.     

Nonimmune and immune surveillance. II. Effect of recipient's age, tumor immunogenicity, and neonatal thymectomy on tumor growth inhibition.

After a suspension of tumor pieces was grafted into newborn and adult (CBA X C57BL/6J)F1 and BALB/c mice, the growth of Lewis lung adenocarcinoma and mammary gland adenocarcinoma was inhibited in newborn mice, whereas sarcoma of the rectum (SR-1-75) grew at the same rate in newborn and adult recipients. Neonatal thymectomy stimulated the growth of hepatoma (H-2-73) in newborns. The degree of tumor growth inhibition was age-dependent: The maximum inhibition was observed in 1- to 6-day-old recipients, but later it gradually decreased. The hepatoma (H-2-73) and ovarian carcinoma (OC-1-75) with inhibited growth in newborns and the tumor (SR-1-75) with uninhibited growth had equally low immunogenicity. The data suggested that newborns possess factors that inhibit tumor growth but these factors disappear with increased age of recipients.     

Induction of tumor suppression and delayed-type footpad reaction by transfer of lymphocytes sensitized to a xenogenized tumor variant

Splenocytes immune to a highly immunogenic ("xenogenized", L5178Y/DTIC) variant of a murine lymphoma exert anti-parental-tumor activity in a systemic adoptive transfer system, the effect being apparently associated with the Lyt-2- fraction of the lymphocyte population. During investigation of the mechanisms of this protection, we found that the L5178Y/DTIC tumor-immune lymphocytes exhibited an appreciable anti-L5178Y delayed-type hypersensitivity (DTH) response. Enrichment of those lymphocytes in L3T4+ cells significantly enhanced the protective effect as well as the DTH reaction, whereas the use of an anti-L3T4 but not anti-Lyt-2 reagent blocked both activities. In vitro, lymphocyte proliferation against L5178Y cells occurred and was apparently associated with the Lyt-2- fraction of a population of L5178Y/DTIC immune splenocytes.     

Enhanced susceptibility of adriamycin-treated human renal cell carcinoma cells to lysis by peripheral blood lymphocytes and tumor infiltrating lymphocytes

Previous studies indicated that the anticancer agent adriamycin (ADR) could induce activation of cytotoxic T lymphocytes (CTL) and natural killer cells. In this study, we investigated the effect of ADR on the susceptibility of human renal cell carcinoma (RCC) cells to lysis by peripheral blood lymphocytes (PBL) and tumor infiltrating lymphocytes (TIL). Treatment of human RCC cell line ACHN and freshly derived RCC cells with ADR at 1 microg/ml or more for 3 h significantly enhanced their susceptibility to lysis by PBL (P<0.05). This ADR-induced enhancement of susceptibility of RCC cells to lysis by PBL was also observed when freshly derived TIL were used as effector cells (P<0.05). ADR up-regulated the expression of leukocyte function-associated antigen-3 (LFA-3) and intercellular adhesion molecule-1 (ICAM-1), which are critical in the binding and killing of CTL against cancer cells. Of the five fresh RCC cell cultures treated with ADR, LFA-3 was increased in all and ICAM-1 was increased in three of them, respectively (P<0.05). Up-regulation of LFA-3 and ICAM-1 was also observed in ACHN cells treated with two derivatives of ADR, epirubicin and pirarubicin. ADR further significantly increased the bindings of PBL to RCC cells (P<0.05). These findings suggest that treatment of RCC patients with low doses of ADR may sensitize the RCC cells to killing by PBL and TIL and may be a novel immunotherapeutic modality for the treatment of drug-resistant and/or immune-resistant RCC. The inducing of LFA-3 and ICAM-1 by ADR may be involved in the enhancement of susceptibility of PBL and TIL-mediated cytolysis in human RCC cells.     

Correlation between docetaxel clearance and estimated cytochrome P450 activity by urinary metabolite of exogenous cortisol.

PURPOSE: There is no simple and practical method for the estimation of the interpatient variability of cytochrome P450 (CYP3A4) enzyme activity. Cortisol is metabolized by this enzyme and excreted as 6-beta-hydroxycortisol (6beta-OHF) and free-cortisol (FC) in urine, and docetaxel is also metabolized by hepatic CYP3A4 enzyme. We developed a new method for the estimation of CYP3A4 activity by measuring urinary cortisol metabolite after administration of exogenous cortisol. This study was aimed at assessing the predictability of the individual activity of CYP3A4 estimated by this method. PATIENTS AND METHODS: Thirty patients with advanced non-small-cell lung cancer were entered onto this study. Hydrocortisone 300 mg was administered intravenously, and urinary 6beta-OHF and FC were measured. More than 2 days later, 60 mg/m(2) of docetaxel was administered intravenously with pharmacokinetic sampling. The correlation between docetaxel pharmacokinetics and estimated interpatient variability of CYP3A4 activity with the application of our method was assessed. RESULTS: After cortisol administration, the total amount of 24-hour urinary 6beta-OHF (T6beta-OHF) increased about 60-fold compared with pretreatment levels, averaging 12,273 +/- 4,076 microg/d (mean +/- SD). Docetaxel clearance (CL) and area under the concentration-time curve averaged 24.5 +/- 6.4 L/h/m(2) and 2.66 +/- 0.91 mg/L 8729. h, respectively. An excellent correlation between docetaxel CL and T6beta-OHF was observed (r =.867). In multivariate analysis, T6beta-OHF (P <.001), alpha-1-acid glycoprotein (P <.004), AST (P =.007), and age (P =. 022) significantly correlated with docetaxel CL. CONCLUSION: The interpatient variability of CYP3A4 activity and docetaxel CL could be predicted by measuring T6beta-OHF after cortisol administration.