Ultraviolet (193, 216 and 254 nm) photoinactivation of Escherichia coli strains with different repair deficiencies

Four mouse B16 melanoma subclones representing distinct stages in the benign-to-malignant progression of that tumor (G3.15, G3.5, G3.12, and G3.26), and three phenotype conversion variants with enhanced malignancy (G3.15*, G3.5*, and G3.12*), were comparatively examined for exogenous mitogen and growth factor requirements and for responsiveness to exogenous and endogenous growth modulators in monolayer culture. Growth behavior in serum-free medium with or without mitogen or growth factor supplements, and in supplemented quiescent serum-containing medium, confirmed previous indications that the G3.5 and G3.15* phenotypes were identical, as were the G3.26 and G3.12* phenotypes. However, G3.12 differed from the closest conversion equivalent, G3.5*, and probably represents an aberrant phenotype within this sequence. There was a direct relationship between degree of malignancy (G3.15-->G3.5-->G3.5*-->G3.26), growth capacity in serum-free medium, and responsiveness to transferrin. Only G3.5*, G3.26, and G3.12* cells were growth-autonomous in serum-free medium and also highly responsive to mitogens. The polypeptide growth factors epidermal growth factor, platelet-derived growth factor, basic fibroblast growth factor, transforming growth factor-alpha, and insulinlike growth factor-1 and -2 were generally stimulatory in quiescent medium, but the degree of growth promotion was unrelated to malignancy level. Transforming growth factor-beta 1 was inhibitory to the more benign populations (G3.15, G3.5, and G3.15*) but stimulated proliferation of other cells. All populations produced autocrine fibronectin, and G3.12, G3.5*, G3.26, and G3.12* cells also produced autocrine transferrin. Only G3.12 cells failed to utilize both of those factors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lovastatin decreases de novo cholesterol synthesis and LDL Apo B-100 production rates in combined-hyperlipidemic males

The effect of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, on the kinetics of de novo cholesterol synthesis and apolipoprotein (apo) B in very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) was investigated in five male patients with combined hyperlipidemia. Subjects were counseled to follow a Step 2 diet and were treated with lovastatin and placebo in randomly assigned order for 6-week periods. At the end of each experimental period, subjects were given deuterium oxide orally and de novo cholesterol synthesis was assessed from deuterium incorporation into cholesterol and expressed as fractional synthesis rate (C-FSR) and production rate (C-PR). Simultaneously, the kinetics of VLDL, IDL, and LDL apo B-100 were studied in the fed state using a primed-constant infusion of deuterated leucine to measure fractional catabolic rates (FCR) and production rates (PR). Drug treatment resulted in significant decreases in total cholesterol (-29%), VLDL cholesterol (-40%), LDL cholesterol (-27%), and apo B (-16%) levels and increases in HDL cholesterol (+13%) and apolipoprotein (apo) A-I (+11%) levels. Associated with these plasma lipoprotein responses was a significant reduction in both de novo C-FSR (-40%; P = .04) and C-PR (-42%; P = .03). Treatment with lovastain in these patients had no significant effect on the FCR of apoB-100 in VLDL, IDL, or LDL, but resulted in a significant decrease in the PR of apoB-100 in IDL and LDL. Comparing the kinetic data of these patients with those of 10 normolipidemic control subjects indicates that lovastatin treatment normalized apoB-100 IDL and LDL PR. The results of these studies suggest that the declines in plasma lipid levels observed after treatment of combined hyperlipidemic patients with lovastatin are attributable to reductions in the C-FSR and C-PR of de novo cholesterol synthesis and the PR of apoB-100 containing lipoproteins. The decline in de novo cholesterol synthesis, rather than an increase in direct uptake of VLDL and IDL, may have contributed to the decline in the PR observed.     

Inhibition of murine renal carcinoma pulmonary metastases by systemic administration of interferon gamma: mechanism of action and potential for combination with interleukin 4

We have previously demonstrated that IFN-gamma causes cell growth inhibition and up-regulation of MHC antigens in human renal cell carcinoma cell lines. In this study, we have investigated the therapeutic potential of IFN-gamma for the treatment of 5-day established pulmonary metastases induced by i.v. injection of Renca cells, a murine renal adenocarcinoma. We found that systemic injections of IFN-gamma significantly reduced the number of lung metastases in a dose-dependent manner and increased mouse survival. Histological evaluation of IFN-gamma-treated lungs showed residual small tumor nodules containing extensive necrosis and mononuclear infiltrates. Immunohistochemistry studies on lung sections showed macrophage infiltration into tumor nodules, and in vivo depletion of macrophages partially inhibited IFN-gamma antitumor effect, suggesting a role for the macrophages in tumor destruction. Lymphocyte depletion of either natural killer (NK) cells or CD4+ or CD8+ T-cell subsets or both T-cell subsets did not affect the IFN-gamma effect, whereas depletion of both NK and T cells decreased the antitumor activity of IFN-gamma. These data indicate that neither T cells nor NK cells are essential for this activity but that either lymphocyte population can contribute to the IFN-gamma effect. An optimal dose of IFN-gamma inhibited by 60% the growth of Renca cells treated for 3 days in vitro, but this effect was transient and less pronounced in a long-term colony assay, suggesting that IFN-gamma direct growth inhibition may play a role but may not be sufficient to mediate its antitumor effect in vivo. In vitro, IFN-gamma caused up-regulation of class I MHC antigens and induction of class II antigen expression in Renca cells, an effect that may enhance Renca immunogenicity but may be relevant only when a T-cell response is elicited. A sequential administration of IFN-gamma followed by interleukin 4 was therapeutically better than IFN-gamma alone for the treatment of advanced pulmonary metastases, probably due to different antitumor mechanisms induced by these two cytokines.     

Systemic interleukin 2 therapy for human prostate tumors in a nude mouse model

Once the regional lymph nodes become involved in prostate carcinoma, 85% of patients develop distant metastases within 5 years, and metastatic disease is difficult to treat. We have investigated the effect of systemic interleukin 2 (IL-2) treatment on metastatic prostate carcinoma using a xenograft tumor model. Cells from a PC-3/IF cell line, produced by intrafemoral injection of human PC-3 prostate carcinoma cells, were injected in the prostate of Balb/c nude mice. Prostate tumors and para-aortic lymph nodes were resected, and tumor cells were recultured and passaged in the prostate in vivo to produce new cell lines. On day 6 following prostatic injection of these cell lines, mice were treated with i.p. injections of IL-2 at 25,000-50,000 units/ day for 5 consecutive days. The effect of IL-2 on tumor progression was assessed, and histological studies were performed on prostate tumor and lymph node sections. The tumor cell lines generated by serial prostate injection were tumorigenic and metastasized to regional para-aortic lymph nodes. Tumors of 0.4 cm were obtained by day 16 and grew to 1-1.5 cm by day 40 with metastasis to para-aortic lymph nodes. Following two to three weekly courses of 5 days of 25,000-40,000 units/day of IL-2, the growth of prostate tumors was inhibited by 94%. Higher doses of 50,000 units/ day were toxic. Histologically, prostate sections showed vascular damage manifested by multifocal hemorrhages and an influx of lymphocytes and polymorphonuclear cells into disintegrating tumors and areas of necrosis containing numerous apoptotic cells. In contrast to control mice, para-aortic lymph nodes were not enlarged in responding mice. These findings suggest that systemic IL-2 therapy can induce an antitumor response in prostate tumors and control their growth and metastasis.     

Activation of cysteine proteases in cowpea plants during the hypersensitive response--a form of programmed cell death

The matrix metalloproteinases appear to play a key role in mammary tissue remodeling during involution. By immunoprecipitation and immunoblot using antibodies against 60K gelatinase which appears during involution a 90K polypeptide has been identified as its inactive proenzyme in the early involuting rat mammary gland. 90K polypeptide was isolated from the second day involuting rat mammary gland by immunoaffinity chromatography. On proteolytic digestion, the inactive 90K polypeptide was converted to active gelatinase. Primary cultures of mammary epithelial cells secreted the 90K polypeptide. These results indicated that the 60K inducible MMP involved in mammary gland involution and remodeling is produced as a 90K proenzyme which is activated by proteolysis in the extracellular sites.