OBJECTIVETo study the effect of retinoid kappa receptor alpha (RXRalpha) transfection plus treatment with the RXRalpha ligand, 9-cis-RA, on the proliferation and phenotype of platelet-derived growth factor (PDGF) activated hepatic stellate cells (HSCs).

METHODSPDGF activated rat hepatic stellate cells were transfected with eukaryotic expression vector pcDNA3.1- human RXRalpha, and confirmed by Western blot. Proliferation of transfected HSC was assayed by bromodeoxyuridine (BrdU) incorporation as well as MTT, and the phenotype (alpha-smooth muscle actin, desmin) was observed by immunocytochemistry with image analysis.

RESULTSTransfection of the RXRalpha gene and treatment with ligand 9-cis-RA of PDGF-activated HSCs extended the increased expression of RXRalpha protein for at least 168 hours. Cell proliferation and expressions of alpha- smooth muscle actin (alpha-SMA) and desmin were blocked, compared with groups of sham-transfected, PDGF-activated, no transfection, no ligand treatment, and irrelevant ligand treated HSCs.

CONCLUSIONTransfection with the RXRalpha gene followed by 9-cis-RA ligand treatment will inhibit the proliferation and reverse the phenotype of activated HSC.

Animals ; Cell Division ; Cells, Cultured ; Liver ; cytology ; Liver Cirrhosis ; etiology ; Male ; Phenotype ; Platelet-Derived Growth Factor ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Retinoic Acid ; genetics ; physiology ; Retinoid X Receptors ; Transcription Factors ; genetics ; physiology ; Transfection

The growth inhibitory effects of four retinoic acid (RA) derivatives, 9-cis RA, 13-cis RA, N-(4-hydroxyphenyl) retinamide (4-HPR), and all-trans retinoic acid (ATRA) were compared. In addition, the effects of various combinations of these four agents were examined on non-small cell lung carcinoma (NSCLC) cell-lines, and on the expressions of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) on these cells. At the clinically achievable concentration of 1 micrometer, only 4-HPR inhibited the growths of H1299 and H460 cells-lines. However, retinoic acid receptor beta(RAR beta) expression was up-regulated on H460 and H1299 cells treated with 1 micrometer of ATRA, 13-cis RA, or 9-cis RA. All NSCLC cell lines showed growth inhibition when exposed sequentially to 1 micrometer ATRA and 0.1 micrometer 4-HPR. In particular, sequential treatment with 1 micrometer ATRA or 13-cis RA and 4-HPR markedly inhibited H1703 cell growth; these cells exhibited no basal RAR beta expression and were refractory to 4-HPR. However, in NSCLC cell lines that expressed RAR beta, the expressional levels of RAR beta were up-regulated by ATRA alone and by sequential treatment with ATRA and 4-HPR. 4-HPR was found to be the most active of the four agents in terms of NSCLC growth-inhibition. Moreover, sequential treatments with ATRA or 13-cis RA followed by 4-HPR were found to have synergistic growth-inhibitory effects and to regulate RAR expression.
Base Sequence ; Carcinoma, Non-Small-Cell Lung/*drug therapy/genetics/metabolism ; Cell Line, Tumor ; DNA Primers/genetics ; Drug Therapy, Combination ; Fenretinide/administration & dosage ; Gene Expression/drug effects ; Humans ; Isotretinoin/administration & dosage ; Lung Neoplasms/*drug therapy/genetics/metabolism ; Receptors, Retinoic Acid/genetics ; Retinoid X Receptors/genetics ; Tretinoin/administration & dosage/*analogs & derivatives