Expression of plasminogen activator and plasminogen activator inhibitor by rat mesothelioma induced by asbestos.

We have investigated the expression of plasminogen activators (PAs) and PA inhibitors (PAIs) by an asbestos-induced mesothelioma. Using zymographic, immunological and biochemical techniques it was demonstrated that cell lines derived from the tumor express high levels of PAI and low levels of a UK-like PA. Adherent and partially non-adherent variants of the mesothelioma expressed indistinguishable amounts of PAI and UK. Based on partial biochemical characterization, the PAI secreted by the mesothelioma cells was a set of PAIs which consisted of PAI-1 in addition to other species. These observations indicate that the difference in growth phenotype of the adherent and partially non-adherent lines was not due to detectable differences in PA and PAI expression.

Purification and characterization of the plasminogen activator inhibitors PAI-1, PAI-2, and PN-1 from the human glioblastoma U138.

This investigation presents data which indicate that the plasminogen activator inhibitor (PAI) activity secreted from U138 cells is composed of three separate PAIs: PAI-1, PAI-2, and PN-1. It was demonstrated that the U138 PAI-1-like protein had an apparent molecular mass of 50 kilodaltons (kDa) and was purified to apparent homogeneity by elution from an anti-PAI-1 immunoaffinity column. These fractions were also reactive with a second anti-PAI-1 monoclonal antibody using immunoblotting techniques. Northern blot analysis of RNA isolated from unstimulated U138 cells demonstrated positive hybridization with the cDNA specific for human PAI-1. The U138 PAI-2-like protein was adherent to an anti-PAI-2 immunoaffinity column and was demonstrated to be nonadherent to concanavalin A-agarose, heparin-Sepharose, and the anti-PAI-1 immunoaffinity column. The eluted U138 PAI-2-like protein was demonstrated to have an apparent molecular mass of 60 kDa and was also reactive with a second anti-PAI-2 monoclonal antibody using immunoblotting techniques. Further, the cDNA specific for PAI-2 was demonstrated to hybridize to a 2.5-kilobase message from RNA isolated from U138 cells. A third PAI was detected that was nonadherent to concanavalin A-agarose and both of the anti-PAI columns. This 50-kDa PAI was adherent to heparin-Sepharose and thrombin-agarose columns, and was not reactive with any antibodies for either PAI-1 or PAI-2. Northern blot analysis of U138 RNA demonstrated positive hybridization with an oligodeoxynucleotide specific for PN-1. This investigation demonstrates with biochemical, immunological, and molecular data that the U138 glioblastoma constitutively produces three PAIs.(ABSTRACT TRUNCATED AT 250 WORDS)

Lithium chloride enhances survival of NZB/W lupus mice: influence of melatonin and timing of treatment.

Daily administration of 4 mg 6LiCl to groups (15 mice/group) of female NZB/W mice starting at 8 weeks of age led to long-term survival (44 weeks of age) of 73% of the mice when injections were performed between 08:00 and 10:00 h and 67% of mice when injections were performed between 17:00 and 19:00 h. Untreated controls were dead by 34 weeks of age and the differences between untreated and treated groups was significant (P < or = 10(-4)). In contrast daily administration of melatonin (100 micrograms/mouse) did not significantly enhance survival when injections were performed between 17:00 and 19:00 h but did enhance survival when given between 08:00 and 10:00 h (P < or = 10(-3)). Differences between the two melatonin groups was also significant (P < or = 0.05). Mice treated with Li plus melatonin exhibited survival curves identical to mice treated with Li alone. Therefore, the Li effect was dominant and survival was not altered by melatonin. Cessation of treatment in long-term survivors at 44 weeks of age led to the rapid death of 80% of the mice previously treated between 17:00 and 19:00 h (Li, Li + melatonin). In contrast, only 40% of the long-term survivors in the other groups had died by 66 weeks of age (22 weeks post-treatment). Thus the p.m. groups were less protected from disease reactivation than were the a.m. groups. Neither Li, melatonin, nor Li+melatonin influenced anti-gp70 or anti-ssDNA levels in serum, but Li treatment maintained renal function as determined by proteinuria scores. These findings indicate that the effectiveness of Li is probably not related to melatonin metabolism and immunomodulating influences, but the influence of other neuroendocrine variables cannot be eliminated.

Partial characterization of the enhanced survival of female NZB/W mice treated with lithium chloride.

Previous investigations have indicated that initiation of LiCl treatment (4 mg/day) of female NZB/W mice at 10 weeks of age led to enhanced survival of 50% of the mice to > 11 months of age (Lithium, 3, 61-67, 1992). The present results indicate that this enhancement of survival is dose dependent in that 2 mg 7LiCl/day was less effective than 4 mg 7LiCl/day. Daily treatment of groups of mice with 2 or 4 mg LiCl per day starting at 8 weeks of age led to the survival of 40% and 70%, respectively, of the mice at 40 weeks of age, a time when only 10% of the untreated mice remained alive. Initiation of treatment with 2 mg 7LiCl/day after the disease process was evident (24 weeks of age) led to diminished effectiveness. Parallel experiments with mice treated with 4 mg 7LiCl/day revealed 60% long-term survivors in the early treatment groups and 33% in the delayed treatment groups. Cessation of treatment in both groups led to some additional deaths, but 20-27% of the mice remained alive at 60 weeks of age, even though animals had detectable levels of anti-ssDNA antibodies in their serum. Additional experiments with 2 and 4 mg 7LiCl/day in NZB/W mice pretreated with C. parvum-PER, a treatment previously shown to enhance survival (Int. J. Immunopharmac., 14, 35-41, 1992), indicated that the effect of the two modalities was not additive. The results presented indicate that treatment of NZB/W mice with LiCl leads to very effective prolongation of survival by unique mechanisms, possibly involving alteration of the effector phase of autoimmune damage to the kidney or the susceptibility of kidney elements to immune-mediated damage leading to renal failure.