tretinoin and Adenocarcinoma--Bronchiolo-Alveolar

In this study, we examined the effects of all trans-retinoic acid (at-RA) on the vascular endothelial growth factor (VEGF) expression in human bronchioloalveolar carcinoma NCI-H322 cells to evaluate the potential of at-RA to affect tumor progression. Northern blot and enzyme-linked immunosorbent assay analyses indicate that VEGF production is significantly increased by 1 microM of at-RA. A series of 5'-deletion and site-directed mutation analyses indicated that G+C-rich sequence located at -81 and -52 was required for at-RA- and retinoic acid receptor alpha-mediated induction of VEGF promoter. Electrophoretic mobility shift and supershift assays showed that major constituents of nuclear factors binding to G+C-rich sequences are Sp1 and Sp3. Pretreatment with cycloheximide, a protein synthesis inhibitor, prevented the at-RA-mediated induction of VEGF mRNA expression. Likewise, at-RA-mediated VEGF expression was completely blocked in the presence of genistein, an inhibitor for tyrosine kinases. These results suggest that an increase in transcription of the VEGF promoter by at-RA is mediated through Sp1 site, and both new protein synthesis and tyrosine kinase activation are necessary for this induction. Because VEGF can promote neovascularization in cancer cells, an induction of VEGF by at-RA may preclude the therapeutic application of at-RA to cancer patients.

Topics: Adenocarcinoma, Bronchiolo-Alveolar; Animals; Binding Sites; Cycloheximide; DNA-Binding Proteins; Endothelial Growth Factors; Enzyme Inhibitors; Genes, Reporter; Genistein; Humans; Lung Neoplasms; Lymphokines; Mice; Mutagenesis, Site-Directed; Promoter Regions, Genetic; Protein Synthesis Inhibitors; Recombinant Fusion Proteins; Sp1 Transcription Factor; Sp3 Transcription Factor; Transcription Factors; Transcription, Genetic; Tretinoin; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

The tumoricidal activity of mouse macrophage (M phi) activated with retinoic acid (RA) and the effect of RA in combination with CP on mouse M phi were studied with phase contrast microscopy, light microscopy, and 3HTdR labelling technique. The results of our studies suggest that: (1) RA can activate mouse peritoneal M phi both in vivo and in vitro, and the RA-activated M phi are cytostatic and cytolytic to A549 cells. The degree of activation is related to the concentration or dosage of RA given, and (2) RA can enhance the function of CP-activated M phi. A summation effect was obtained by giving RA in combination with CP. This effect was related to the dosage of RA. When optimal dosage was given in combination with CP, a synergistic action in activating M phi could be obtained. Morphological changes could be seen under phase contrast microscope and light microscope in killed tumor cells.

Topics: Adenocarcinoma, Bronchiolo-Alveolar; Animals; Bacterial Vaccines; Cytotoxicity, Immunologic; Dose-Response Relationship, Drug; Female; Lung Neoplasms; Macrophage Activation; Macrophages; Mice; Mice, Inbred Strains; Peritoneal Cavity; Tretinoin; Tumor Cells, Cultured