IN VITRO MODELS FOR THE PRE-CLINICAL EVALUATION OF PROMISING CHEMOPREVENTIVE AND THERAPEUTIC MOLECULES

The use of in vitro models are playing an increasingly important role to generate data in support of clinical trials as well as to minimize the number and extension of animal studies. We set a panel of in vitro tests to profile risks and benefits associated with the use of promising tumor chemopreventive agents, innovative therapeutic molecules and drugs associations. The battery of assays included a modified protocol of BALB/c 3T3 transformation test and an innovative anti-transformation assay, cytotoxicity tests, clonogenicity tests, tests to evaluate the effect of the assayed compound on the invasive and metastatic phenotype and tests to assess the ability of the compounds to interfere with specific endpoints (apoptosis, differentiation, cell-to-cell communication). Different cell lines, other than BALB/c 3T3 fibroblasts, were used as representatives of target organs. In order to define and validate the protocols, we studied the toxicological profile and efficacy of tamoxifen (TAM) as a chemopreventive and therapeutic agent. TAM is a non-steroideal antiestrogen, in use for the clinical treatment of various hormone-dependent cancers and known to have significant chemopreventive effects in mammary carcinogenesis. We were able to define the dose-related toxicity in different human target cells as well as BALB/c 3T3 cells, to highlight that TAM exerted initiating activity at the dosage usually employed to control breast cancer, whereas it could prevent the onset of the transforming phenotype at lower concentrations than therapeutic ones. Since TAM belongs to the family of selective estrogen receptor modulators (SERMs), a subset of tests suitable to investigate a potential endocrine-disrupting activity of the tested agents were performed, including the E-screen assay in MCF-7 cells. The application of the microarray technology allowed us to improve the rate of information about the tested compounds. By the means of all the assays, we profiled the activity of several molecules including SERMs, retinoids, antioxidants, phytoestrogens, topoisomerases inhibitors as well as associations of several drugs. The results confirmed the feasibility and suitability of this in vitro approach as a pre-clinic screening of new drugs.