ABSTRACT
This study was designed to assess the potential chemopreventive effect of the administration of a standardized soy extract, SOYSELECT, on 7,12-Dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in rats. Three groups, 24 females each, were used. Animals were fed either a phytoestrogen-free diet alone (control) or the same diet supplemented with 0.35% or 0.7% of soy extract. Treatment started at weaning and continued to the end of the study (24 weeks after DMBA administration). At day 50 of age all animals received via oral gavage 80 mg/kg DMBA. Only tumors subsequently classified as adenocarcinomas were considered for data evaluation. In rats on the soy diet, mammary tumors took a longer period of time to develop as compared to control rats. However, at the end of the study, no relevant difference in tumor incidence and multiplicity was observed among the groups. The most significant changes were seen between control and soy-treated groups when tumor dimension and results from histopathologic examination were considered. The latter, in fact, showed a dose-dependent reduction in the percentage of poorly differentiated tumors in treated animals. This change was statistically significant in animals receiving 0.7% soy. In addition, assessment of estrogen and progesterone receptor (ERalpha, PR) levels, revealed a significant reduction in the percentage of ERalpha and PR positive tumors in animals receiving 0.7% dietary soy, when compared to controls. Interestingly, genistein and daidzein plasma levels determined at the end of the study were within the range of those detected in people consuming large amounts of soyfoods.
Subject(s)
Adenocarcinoma/prevention & control , Chemoprevention , Mammary Neoplasms, Animal/prevention & control , Soybean Proteins/pharmacology , 9,10-Dimethyl-1,2-benzanthracene/adverse effects , Adenocarcinoma/etiology , Adenocarcinoma/veterinary , Administration, Oral , Animals , Carcinogens/adverse effects , Diet , Female , Mammary Neoplasms, Animal/etiology , Neoplasms, Experimental , Rats , Rats, Sprague-Dawley , Receptors, Estrogen/analysis , Receptors, Progesterone/analysisABSTRACT
Using a model of human cervical cancer (ME-180 cells), the anti-tumour activity of paclitaxel was compared to that of docetaxel and IDN5109, a newly developed taxane. The growth inhibition effect of taxanes was assessed after 3 days of exposure. DNA analysis, the taxane-dependent modulation of the expression of the alpha and beta subunits of tubulin and DNA fragmentation were assessed by flow cytometry. The presence of apoptosis was confirmed by morphological analysis using a laser scan cytometer. For the evaluation of "in vivo" anti-tumour activity, taxanes were administered to nude mice intravenously once daily, according to a q3/4d x 4 schedule. Docetaxel, IDN5109 and paclitaxel obtained "in vitro" IC(50) values of 0.86, 1.4 and 2.4 nM, respectively. DNA analysis demonstrated a transient block at the G(2)/M phase of the cell cycle only after 12 h of culture in the presence of taxanes and an increase of nuclear fragmentation suggestive for apoptosis after additional 12 and 60 h of exposure. Morphological analysis confirmed the presence of apoptosis. Taxanes induced a down-modulation of the alpha subunit of tubulin in the G(0/1) phase of the cell cycle, and an overexpression of the beta subunit in the G(2)/M phase. A strong anti-tumour activity was obtained "in vivo" for nude mice xenografted using ME-180 cells (T/C=0% for all drugs). These data indicate that the three taxanes are strongly active both "in vitro" and "in vivo" toward ME-180 cells. Clinical studies are now needed to ascertain if the higher anti-tumour activity observed "in vitro" using docetaxel and IDN5109 yields a better clinical response in advanced cervical carcinoma with respect to paclitaxel.
Subject(s)
Antineoplastic Agents, Phytogenic/pharmacology , Bridged-Ring Compounds/pharmacology , Paclitaxel/analogs & derivatives , Paclitaxel/pharmacology , Taxoids , Uterine Cervical Neoplasms/pathology , Animals , Apoptosis/drug effects , Cell Cycle , DNA, Neoplasm/drug effects , Docetaxel , Drug Screening Assays, Antitumor , Female , Flow Cytometry , Humans , Mice , Mice, Nude , Transplantation, Heterologous , Tubulin/biosynthesis , Tumor Cells, Cultured/drug effectsABSTRACT
This study was designed to assess the effects of administration of dietary soy on reproductive function and fertility of female Wistar rats. Four groups, each of 20 females, were used. Control animals were fed a standard cereal-based diet for rats. Treated animals were fed a standard diet supplemented with 0.7%, 1.2% or 2.4% of a soy extract. Treatment started at weaning and continued until day 7 post-partum (day of sacrifice). Growth depression was seen in the 2.4% soy group. Vaginal opening occurred earlier in females receiving soy supplemented feed when compared with controls. Analysis of vaginal smears revealed that all animals were cycling, although an increase in the mean duration of each cycle was seen in the 2.4% soy group. Uterine effects were observed in high-dose females and included increases in weight, oedema, endothelial hyperplasia and leucocytic infiltration. Vaginal modifications (i.e. inflammation, hyperkeratosis and dyskeratosis) and alterations in the distribution of follicular size in the ovaries were also observed among treated animals. These data suggest that long-term exposure to high doses of phytoestrogens can produce significant agonistic actions in several oestrogen-dependent tissues and parameters, even though in this model no clear influence on reproductive processes was observed.
