Germline control of somatic Kras mutations in mouse lung tumors.

Somatic KRAS mutations are common in human lung adenocarcinomas and are associated with worse prognosis. In mice, Kras is frequently mutated in both spontaneous and experimentally induced lung tumors, although the pattern of mutation varies among strains, suggesting that such mutations are not random events. We tested if the occurrence of Kras mutations is under genetic control in two mouse intercrosses. Codon 61 mutations were prevalent, but the patterns of nucleotide changes differed between the intercrosses. Whole genome analysis with SNPs in (A/J x C57BL/6)F4 mice revealed a significant linkage between a locus on chromosome 19 and 2 particular codon 61 variants (CTA and CGA). In (AIRmax × AIRmin) F2 mice, there was a significant linkage between SNPs located on distal chromosome 6 (around 135 Mbp) and the frequency of codon 61 mutation. These results reveal the presence of two loci, on chromosomes 6 and 19, that modulate Kras mutation frequency in different mouse intercrosses. These findings indicate that somatic mutation frequency and type are not simple random events, but are under genetic control.

Evaluation in melanoma-bearing mice of an etoposide derivative associated to a cholesterol-rich nano-emulsion.

A cholesterol-rich nano-emulsion (LDE) may be used as a vehicle to target antineoplastic drugs against cancer cells. The association of an etoposide derivative to LDE is stable and retains the cytotoxic activity of etoposide. We have evaluated the toxicity and antitumoral action of this new preparation in-vivo. Melanoma-bearing mice and control mice were administered LDE-etoposide oleate or commercial etoposide, either with or without radioactive labelling. The maximum tolerated dose (MTD), tissue distribution, plasma decay curves, pharmacokinetic parameters and antitumoral activity were determined. Association to LDE drastically reduced the drug toxicity, since MTD was approximately five-fold greater than in commercial etoposide. LDE-etoposide oleate was concentrated four-fold in the tumour compared with the normal adjacent tissues, was removed faster from plasma in tumour-bearing mice than in controls, and remained in the bloodstream longer than commercial etoposide. The tumour growth inhibition rate and survival were greater in animals treated with LDE-etoposide oleate compared with commercial etoposide. However, increasing the dose from 17 to 85 microM kg(-1) did not result in further improvement of the antitumour action. The incorporation of etoposide oleate to LDE resulted in markedly reduced toxicity and superior antitumoral activity. LDE-etoposide oleate is a promising new weapon for cancer treatment.

Improvement of paclitaxel therapeutic index by derivatization and association to a cholesterol-rich microemulsion: in vitro and in vivo studies.

A cholesterol-rich microemulsion or nanoparticle termed LDE concentrates in cancer tissues after injection into the bloodstream. Here the cytotoxicity, pharmacokinetics, toxicity to animals and therapeutic action of a paclitaxel lipophilic derivative associated to LDE is compared with those of the commercial paclitaxel. Results show that LDE-paclitaxel oleate is stable. The cytostatic activity of the drug in the complex is diminished compared with the commercial paclitaxel due to the cytotoxicity of the vehicle Cremophor EL used in the commercial formulation. Competition experiments in neoplastic cultured cells show that paclitaxel oleate and LDE are internalized together by the LDL receptor pathway. LDE-paclitaxel oleate arrests the G(2)/M phase of cell cycle, similarly to commercial paclitaxel. Tolerability to mice is remarkable, such that the lethal dose (LD(50)) was ninefold greater than that of the commercial formulation (LD(50) = 326 microM and 37 microM, respectively). LDE concentrates paclitaxel oleate in the tumor roughly fourfold relative to the normal adjacent tissues. At equimolar doses, the association of paclitaxel oleate with LDE results in remarkable changes in the drug pharmacokinetic parameters when compared to commercial paclitaxel (t(1/2)=218 min and 184 min, AUC=1,334 microg h/ml and 707 microg h/ml and CL=0.125 ml/min and 0.236 ml/min, respectively). Finally, the therapeutic efficacy of the complex is pronouncedly greater than that of the commercial paclitaxel, as indicated by the reduction in tumor growth, increase in survival rates and % cure of treated mice. In conclusion, LDE-paclitaxel oleate is a stable complex and compared with paclitaxel toxicity is considerably reduced and activity is enhanced, which may lead to improved therapeutic index in clinical use.

Efeito do BCG na resposta alérgica à ovalbumina em camundongos geneticamente selecionados (IV-A) / The effect of BCG on the allergic response to ovalbumin in genetically selected strains of mice (IV-A)

Objetivo: Investigar se o tratamento com BCG é capaz de bloquear a resposta alergica pulmonar de camundongos geneticamente selecionados para uma boa (HIV-A) ou má resposta ( LIV-A) de anticorpos imunizados com ovalbumina ( OVA)...

To investigate whether BCG inhibits allergic pulmonary response in genetically selected mice for high (HIV-A) or low antibody response (LIV-A)...