Retroviral Vector-mediated The IFN�� Gene Transfer Synergistic ATRA Induced Apoptosis In HL-60 Cells And Mechanisms

Retinoic acid(RA) is a active metabolite of Vitamin A and possesses a wide specutrum of biological effects.RA has been widely used in treatment of various tumor including APL.The effects of RA on APL is different from tranditional chemotherapy,RA doesntt kill the normal cells ,but induce differentiation of APL cells toward mature cells without growth inhibition of bone marrow.In recent years,it has been reported that some APL cases were not sensitive to ATRA or easy to replase. A variety of data showed that the combination of RA and IFN lead to a more potent differentiation,growth inhibition and antivirus activity in vitro and in vivo.Using both RA and TEN to treat head and neck cancer and advanced solid tumors has shown some promising result,but long-term administration of high dose IFN produced severe side effects in almost all patients.One of the way of overcoming the side effects is gene transfer of TEN into tumor cells in which one could achieve efficient and constant expression.To explore the synergistic effects of RA and IFN on differentiation and apoptosis of APL cells,HL-60 cells,which were sensitive to ATRA,were infected with the supernatants of PA3 17 cells transfected with retrovial vectors pLXSN-IFN a Infected HL-60 cells were treated with ATRA after analysing expression of lEN a mRNA by RT-PCR and detecting secretion of IFN a by ELISA.For examining the changes of cellular proliferation capacity,cell cycle distribution and expression of apoptosis associated genes,the methods of flow cytometer analysis,Westen blot,RT-PCR were applied.The results showed that:@DWN a highly expressed in I-JL-60 cells by retrovius mediated TEN a gene transfer;㏕he capacity of ATRA in inducing differentiation and inhibiting proliferation of l-IL-60 cells was enhenced because of high expression of lEN a ;igh exprssion of IFN a in HL-60 ells existed synergetic effects with ATRA on up-regulation of Fas and Caspase-3 and down-regulation of Bcl-2.These observations suggest that high expressed TEN a in HL-60 cell can improve ATRA effects on l-IL-60 cells and it may be a efficient method in preventing and overcoming ATRA resistance and relieving side effects of ATRA.