fenretinide and Esophageal-Neoplasms

9-cis-Retinoic acid (9-cis-RA) and N-(4-hydroxyphenyl)retinamide (4-HPR) are effective chemopreventive agents against epithelial tumors in the oral cavity, breast, and prostate. We tested the inhibitory activity of these retinoids against N-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in the rat esophagus.. Male Fischer 344 rats were randomly assigned to receive diets either lacking or containing 9-cis-RA or 4-HPR for 1 week before tumor initiation with NMBA and then for the duration of the study. NMBA metabolism, O(6)-methylguanine adduct formation, and cytochrome P450 messenger RNA (mRNA) expression in the esophagi of the rats were studied to investigate the mechanisms by which dietary 4-HPR affects tumorigenesis. All statistical tests were two-sided.. Dietary 4-HPR resulted in a dose-dependent and statistically significant enhancement (P<.05) of tumorigenesis in response to NMBA. In two different tumor bioassays, the mean tumor multiplicity for rats fed the highest concentration of dietary 4-HPR (0.8 g/kg diet) was increased by 5.9 tumors (95% confidence interval [CI] = 1.7 to 10.1 tumors) and 6.7 tumors (95% CI = 5.6 to 7.8 tumors) compared with the mean tumor multiplicity for rats that received the control diet lacking 4-HPR. Animals fed diets containing 9-cis-RA displayed no statistically significant increase in tumorigenesis. Compared with animals fed a diet lacking 4-HPR, animals fed 4-HPR had increased NMBA metabolism in esophageal explant cultures and had higher levels of O(6)-methylguanine DNA adducts and CYP2A3 mRNA in their esophagi.. Dietary 4-HPR enhances tumorigenesis in response to NMBA in the rat esophagus by increasing tumor initiation events. Dietary 4-HPR may exert paradoxical effects at some sites, such as the aerodigestive tract, by modulating the bioactivation of carcinogens in target tissues.

Topics: Alitretinoin; Animals; Antineoplastic Agents; Carcinogens; Cytochrome P-450 Enzyme System; Dimethylnitrosamine; DNA Adducts; Esophageal Neoplasms; Esophagus; Fenretinide; Male; Rats; Rats, Inbred F344; Retinoids; RNA, Messenger; Time Factors; Tretinoin

In order to better understand the mechanisms that underlie the antiproliferative effect of retinoids, we have examined the response of human carcinoma cell lines to all-trans retinoic acid (RA) and N-(4-hydroxyphenyl) retinamide (4HPR) in terms of cell growth, apoptosis and regulation of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) mRNA. GLC82 (lung adenocarcinoma), BGC823 (stomach adenocarcinoma) and EC109 (esophageal squamous carcinoma) cells were treated with 10 microM of RA or 4HPR for various length of time and analyzed. The results show that growth inhibition by RA and 4HPR in GLC82 and BGC823 cells correlates with the induction of RARbeta2 gene, whereas RA resistance in EC109 cells parallels loss of RARbeta2 induction. Exogenous RARbeta2 expression did not restore RA responsiveness in EC109 cells, but potentiated 4HPR-induced growth inhibition, suggesting that 4HPR acts at least in part via the RARbeta receptor. We speculate that the loss of RARbeta2 inducibility in EC109 cells may be due to an unknown repressor.

Topics: Adenocarcinoma; Antineoplastic Agents; Cell Division; Drug Resistance, Neoplasm; Esophageal Neoplasms; Fenretinide; Humans; Lung Neoplasms; Neoplasms; Receptors, Retinoic Acid; Retinoid X Receptors; Stomach Neoplasms; Transcription Factors; Transfection; Tretinoin; Tumor Cells, Cultured

Retinoids are vitamin A analogs that regulate growth and differentiation of squamous epithelial cells in vitro and in vivo. We examined the effects of retinoic acid (RA) and N-(4-hydroxy-phenyl) retinamide (HPR) on the growth properties of esophageal squamous carcinoma cell lines, and found that both RA and HPR induce morphological changes and inhibit growth. Immunofluorescence studies suggest alterations in keratins as a result of treatment with RA or HPR. In order to determine underlying molecular mechanisms, we found that RA or HPR did not induce arrest of cells in the G1 phase nor did treated cells undergo apoptosis. However, RA and HPR treatment did result in the downregulation of epidermal growth factor receptor (EGFR) which is known to bind key proproliferative ligands, such as epidermal growth factor and transforming growth factor alpha.

Topics: Antineoplastic Agents; Apoptosis; Blotting, Western; Carcinoma, Squamous Cell; Cell Division; Cell Size; ErbB Receptors; Esophageal Neoplasms; Fenretinide; Flow Cytometry; Humans; Keratins; Time Factors; Tretinoin; Tumor Cells, Cultured