Retinoids have been used as chemopreventive agents in the treatment of different tumors including breast cancer. The synthetic retinoid Ro 41-5253 (Ro) is a selective RARalfa antagonist, exerting antiproliferative activity without inducing the known toxic side effects of retinoids. A pattern of in vitro tests was performed in order to verify the potential chemopreventive activity of Ro. The ability of Ro to inhibit the 3-MCA induced cell transformation was assessed by a modified BALB/c 3T3 cell transformation assay. The plating efficiency and the proliferation rate of BALB/c 3T3 clone A31 cells were significantly reduced when the cells were exposed to 10 µM Ro. In the anti-transformation assay, carcinogen-treated BALB/c-3T3 cells were chronically exposed to several concentrations (0.1-10 µM) of Ro throughout the duration of the experiment. A dose-related reduction of the transformation frequency (TF) induced by Ro was observed . A significant inhibition of foci occurrence was detected after the chronic administration of 1 e 10 µM Ro. The potential anti-cancer effects of Ro were also analyzed on human breast and colon carcinoma cell models, differing for the estrogen receptor expression (MCF-7 and Caco-2, ER+; HuMi-TTu2 and HT29, ER-). The GI50 values showed a different degree of susceptibility of the assayed cell lines (HT29 > Caco-2 > HuMi-TTu2 = MCF-7). These toxicological profiles, which were evaluated in both cytotoxicity and viability assays, were suggestive of apoptosis induction. The enhancement of apoptotic cell death 4 and 6 days after the exposure to 0.01-10 µM Ro was dose- and time-dependent. The growth of breast and colon cell lines in soft agar was strongly reduced by Ro treatment; the number of colonies in the semisolid medium was lowered nearly by 50% at 0.1 µM Ro. The experimental results showed that Ro was able to modulate either the programmed cell death and the anchorage independent growth, which are key steps in the neoplastic process. Ten µM Ro was the most effective dose in the antitransformation assay since it almost completely inhibited the clonogenicity. Ro 41-5253 seemed to be effective in inhibiting both chemical transformation and proliferation of malignant cells. Results gave also evidence for a high responsiveness of the target cells to this potential antitumor agent, therefore Ro could be regarded as a promising candidate for cancer therapy.
EVALUATION OF AN INNOVATIVE RETINOID, RO 41-5253, AS A CHEMOPREVENTIVE AGENT.
GRILLI, SANDRO;MASCOLO, MARIA GRAZIA;SILINGARDI, PAOLA;HORN, WOLFANGO;CHIOZZOTTO, DANIELA;VACCARI, MONICA;COLACCI, ANNAMARIA
2005
Abstract
Retinoids have been used as chemopreventive agents in the treatment of different tumors including breast cancer. The synthetic retinoid Ro 41-5253 (Ro) is a selective RARalfa antagonist, exerting antiproliferative activity without inducing the known toxic side effects of retinoids. A pattern of in vitro tests was performed in order to verify the potential chemopreventive activity of Ro. The ability of Ro to inhibit the 3-MCA induced cell transformation was assessed by a modified BALB/c 3T3 cell transformation assay. The plating efficiency and the proliferation rate of BALB/c 3T3 clone A31 cells were significantly reduced when the cells were exposed to 10 µM Ro. In the anti-transformation assay, carcinogen-treated BALB/c-3T3 cells were chronically exposed to several concentrations (0.1-10 µM) of Ro throughout the duration of the experiment. A dose-related reduction of the transformation frequency (TF) induced by Ro was observed . A significant inhibition of foci occurrence was detected after the chronic administration of 1 e 10 µM Ro. The potential anti-cancer effects of Ro were also analyzed on human breast and colon carcinoma cell models, differing for the estrogen receptor expression (MCF-7 and Caco-2, ER+; HuMi-TTu2 and HT29, ER-). The GI50 values showed a different degree of susceptibility of the assayed cell lines (HT29 > Caco-2 > HuMi-TTu2 = MCF-7). These toxicological profiles, which were evaluated in both cytotoxicity and viability assays, were suggestive of apoptosis induction. The enhancement of apoptotic cell death 4 and 6 days after the exposure to 0.01-10 µM Ro was dose- and time-dependent. The growth of breast and colon cell lines in soft agar was strongly reduced by Ro treatment; the number of colonies in the semisolid medium was lowered nearly by 50% at 0.1 µM Ro. The experimental results showed that Ro was able to modulate either the programmed cell death and the anchorage independent growth, which are key steps in the neoplastic process. Ten µM Ro was the most effective dose in the antitransformation assay since it almost completely inhibited the clonogenicity. Ro 41-5253 seemed to be effective in inhibiting both chemical transformation and proliferation of malignant cells. Results gave also evidence for a high responsiveness of the target cells to this potential antitumor agent, therefore Ro could be regarded as a promising candidate for cancer therapy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
