Antisense therapy:a potential breakthrough in the treatment of neurodegenerative diseases

Neurodegenerative diseases are a group of disorders characterized by the progressive degeneration of neurons in the central or peripheral nervous system.Currently,there is no cure for neurodegenerative diseases and this means a heavy burden for patients and the health system worldwide.Therefore,it is necessary to find new therapeutic approaches,and antisense therapies offer this possibility,having the great advantage of not modifying cellular genome and potentially being safer.Many preclinical and clinical studies aim to test the safety and effectiveness of antisense therapies in the treatment of neurodegenerative diseases.The objective of this review is to summarize the recent advances in the development of these new technologies to treat the most common neurodegenerative diseases,with a focus on those antisense therapies that have already received the approval of the U.S.Food and Drug Administration.

Long Non-coding RNA PCED1B Antisense RNA 1 Promotes Cell Proliferation and Invasion in Hepatocellular Carcinoma by Regulating the MicroRNA-34a/CD44 Axis

Objective This study aimed to examine the role of long non-coding RNA PCED1B antisense RNA 1(PCED1B-AS1)in the development of hepatocellular carcinoma(HCC).Methods A total of 62 pairs of HCC tissues and adjacent non-tumor tissues were obtained from 62 HCC patients.The interactions of PCED1B-AS1 and microRNA-34a(miR-34a)were detected by dual luciferase activity assay and RNA pull-down assay.The RNA expression levels of PCED1B-AS1,miR-34a and CD44 were detected by RT-qPCR,and the protein expression level of CD44 was determined by Western blotting.The cell proliferation was detected by cell proliferation assay,and the cell invasion and migration by transwell invasion assay.The HCC tumor growth after PCED1B-AS1 was downregulated was determined by in vivo animal study.Results PCED1B-AS1 was highly expressed in HCC tissues,which was associated with poor survival of HCC patients.Furthermore,PCED1B-AS1 interacted with miR-34a in HCC cells,but they did not regulate the expression of each other.Additionally,PCED1B-AS1 increased the expression level of CD44,which was targeted by miR-34a.The cell proliferation and invasion assay revealed that miR-34a inhibited the proliferation and invasion of HCC in vitro,while CD44 exhibited the opposite effects.Furthermore,PCED1B-AS1 suppressed the role of miR-34a.Moreover,the knockdown of PCED1B-AS1 repressed the HCC tumor growth in nude mice in vivo.Conclusion PCED1B-AS1 may play an oncogenic role by regulating the miR-34a/CD44 axis in HCC.

Alu antisense RNA ameliorates methylglyoxal-induced human lens epithelial cell apoptosis by enhancing antioxidant defense

AIM:To determine whether an antisense RNA corresponding to the human Alu transposable element(Aluas RNA)can protect human lens epithelial cells(HLECs)from methylglyoxal-induced apoptosis.METHODS:Cell counting kit-8(CCK-8)and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assays were used to assess HLEC viability.HLEC viability/death was detected using a Calcein-AM/PI double staining kit;the annexin V-FITC method was used to detect HLEC apoptosis.The cytosolic reactive oxygen species(ROS)levels in HLECs were determined using a reactive species assay kit.The levels of malondialdehyde(MDA)and the antioxidant activities of total-superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px)were assessed in HLECs using their respective kits.RT-q PCR and Western blotting were used to measure m RNA and protein expression levels of the genes.RESULTS:Aluas RNA rescued methylglyoxal-induced apoptosis in HLECs and ameliorated both the methylglyoxalinduced decrease in Bcl-2 m RNA and the methylglyoxalinduced increase in Bax m RNA.In addition,Aluas RNA inhibited the methylglyoxal-induced increase in Alu sense RNA expression.Aluas RNA inhibited the production of ROS induced by methylglyoxal,restored T-SOD and GSHPx activity,and moderated the increase in MDA content after treatment with methylglyoxal.Aluas RNA significantly restored the methylglyoxal-induced down-regulation of Nrf2 gene and antioxidant defense genes,including glutathione peroxidase,heme oxygenase 1,γ-glutamylcysteine synthetase and quinone oxidoreductase 1.Aluas RNA ameliorated methylglyoxal-induced increases of the m RNA and protein expression of Keap1 that is the negative regulator of Nrf2.CONCLUSION:Aluas RNA reduces apoptosis induced by methylglyoxal by enhancing antioxidant defense.

Targeting LncRNA LLNLR-299G3.1 with antisense oligonucleotide inhibits malignancy of esophageal squamous cell carcinoma cells in vitro and in vivo

Accumulating evidence has indicated that long non-coding RNAs(lncRNAs)play critical roles in the development and progression of cancers,including esophageal squamous cell carcinoma(ESCC).However,the mechanisms of lncRNAs in ESCC are still incompletely understood and therapeutic attempts for in vivo targeting cancer-associated lncRNA remain a challenge.By RNA-sequencing analysis,we identified that LLNLR-299G3.1 was a novel ESCC-associated lncRNA.LLNLR-299G3.1 was up-regulated in ESCC tissues and cells and promoted ESCC cell proliferation and invasion.Silencing of LLNLR-299G3.1 with ASO(antisense oligonucleotide)resulted in opposite effects.Mechanistically,LLNLR-299G3.1 bound to cancerassociated RNA binding proteins and regulated the expression of cancer-related genes,including OSM,TNFRSF4,HRH3,and SSTR3.ChIRP-seq(chromatin isolation by RNA purification and sequencing)revealed that these genes contained enriched chromatin binding sites for LLNLR-299G3.1.Rescue experiments confirmed that the effects of LLNLR-299G3.1 on ESCC cell proliferation were dependent on interaction with HRH3 and TNFRSF4.Therapeutically,intravenous delivery of placental chondroitin sulfate A binding peptide-coated nanoparticles containing antisense oligonucleotide(pICSA-BP-ANPs)strongly inhibited ESCC tumor growth and significantly improved animal survival in vivo.Overall,our results suggest that LLNLR-299G3.1 promotes ESCC malignancy through regulating gene-chromatin interactions and targeting ESCC by pICSA-BP-ANPs may be an effective strategy for the treatment of lncRNA-associated ESCC.

Investigation on small molecule-aptamer dissociation equilibria based on antisense displacement probe

Food safety is a major issue to public health and have attracted global attention.Fast,sensitive,and reliable detection methods for food hazardous substances is highly desirable.Aptamers which can bind to the target molecules with high affinity and specificity represent an attractive tool for the recognition of food hazardous substances,which play an important role in the development and application of new food safety detection technology.But current assays for characterizing small molecule-aptamer binding are limited by either the mass sensitivity or the size differentiation ability.Herein,we proposed a comprehensive method for assessing the dissociation equilibria of small molecule-aptamer,which is immobilized-free under ambient conditions.The design employs the Le Chatelier’s principle and could be used to effectively measure small molecule-aptamer interactions.ATP binding aptamer and anti-aflatoxin B1 aptamer were used as the model system to determine their affinity,in which their dissociation equilibria measurements are in excellent close to their previous work.Due to the simplicity and sensitivity of this new method,we believe that it could be recommended as an effective tool for characterizing small molecule-aptamer interactions and promote the further application of small molecular aptamer in food safety.

Anti-aging Effects of Alu Antisense RNA on Human Fibroblast Senescence Through the MEK-ERK Pathway Mediated by KIF15

Objective:To investigate whether human short interspersed nuclear element antisense RNA(Alu antisense RNA;Alu asRNA)could delay human fibroblast senescence and explore the underlying mechanisms.Methods:We transfected Alu asRNA into senescent human fibroblasts and used cell counting kit-8(CCK-8),reactive oxygen species(ROS),and senescence-associated beta-galactosidase(SA-β-gal)staining methods to analyze the anti-aging effects of Alu asRNA on the fibroblasts.We also used an RNA-sequencing(RNA-seq)method to investigate the Alu asRNA-specific mechanisms of anti-aging.We examined the effects of KIF15 on the anti-aging role induced by Alu asRNA.We also investigated the mechanisms underlying a KIF15-induced proliferation of senescent human fibroblasts.Results:The CCK-8,ROS and SA-β-gal results showed that Alu asRNA could delay fibroblast aging.RNA-seq showed 183 differentially expressed genes(DEGs)in Alu asRNA transfected fibroblasts compared with fibroblasts transfected with the calcium phosphate transfection(CPT)reagent.The KEGG analysis showed that the cell cycle pathway was significantly enriched in the DEGs in fibroblasts transfected with Alu asRNA compared with fibroblasts transfected with the CPT reagent.Notably,Alu asRNA promoted the KIF15 expression and activated the MEK-ERK signaling pathway.Conclusion:Our results suggest that Alu asRNA could promote senescent fibroblast proliferation via activation of the KIF15-mediated MEK-ERK signaling pathway.

Cloning of cDNA Encoding CCoAOMT from Populus tomentosa and Down-regulation of Lignin Content in Transgenic Plant Expressing Antisense Gene

cDNA encoding caffeoyl CoA O-methyltransferase (CCoAOMT) from Chinese white poplar ( Populus tomentosa Carr.) was cloned by RT-PCR and sequenced. Northern analysis displayed that the CCoAOMT was expressed specifically in the developing secondary xylem and its expression was coincident with lignification. The antisense CCoAOMT cDNA was transformed into P. tremula x P. alba mediated by Agrobacterium tumefaciens ( Smith et Townsend) Conn. Transgenic plants were identified with PCR, PCR-Southern and Southern analysis. Lignin content in 5- to 6-month-old transgenic plants was measured. One of the transgenic lines had significant reduction of 17.9% in Klason lignin content as compared with that of untransformed poplar. The results demonstrate that antisense repression of CCoAOMT is an efficient way to reduce lignin content for improving pulping property in engineered trees.

EXPRESSION OF TOMATO ANTISENSE ACC SYNTHASE GENE IN TRANSGENIC TOBACCO AND ITS ROLE IN SHOOT FORMATION

An ACC synthase cDNA isolated from tomato (Lycopersicum esculentum Mill.) fruit was constructed in antisense orientation under the transcriptional control of CaMV 35S promoter and then introduced into tobacco (Nicotiana tabacum L.) . PCR amplification demonstrated the integration of this antisense gene in tobacco genomes. Northern hybridization and reverse transcription-PCR analyses indicated the expression of this heterologous antisense gene in the transgenic tobacco tissues, which caused a decrease in the ethylene production, particularly when shoot regeneration exhibited. The ability of shoot regeneration of the transgenic plant during the culture process was enhanced remarkably as compared with that of the control. These results indicate at the molecular level that ethylene may play a regulatory role in shoot formation.

Inhibition of Telomerase with hTERT Antisense Increases Susceptibility of Leukemic Cells to CDDP-induced Apoptosis

Objective: To investigated the e?ect of inhibition of telomerase with hTERT antisense on leukemic cells (HL-60 and K562) to CDDP-induced apoptosis. Methods: Antisense phosphorothioate oligodeoxynucleotide (AS PS-ODN) was synthesized and puri?ed. Telomerase activity was detected by Telomerase PCR ELASA kit and cell apoptosis was observed by morphological method and determined by ?owcytometry. Results: AS PS-ODN could signi?cantly inhibit telomerase activity by down regulat- ing the hTERT expression, and increase the susceptibility of leukemic cells to CDDP-induced apoptosis. Conclusion: Inhibition of telomerase with hTERT antisense can increases the susceptibility of leukemic cells to CDDP-induced apoptosis.

Construction and Characterization of an Antisense RNA Eukaryotic Expression Vector for Survivin

Objective: To inhibit specifically survivin expression and block its function in leukemia cells, an antisense RNA expression plasmid for survivin was constructed and transfected into a leukemia cell line.Methods: A cDNA fragment of survivin obtained by RT-PCR was inserted into a plasmid vector named pcDNA3 in the reverse direction. Antisense RNA of survivin was confirmed by restriction enzyme digestion and DNA sequencing. The recombinant plasmid was transfected into the cell line HL-60 by electroporation. The effect of survivin antisense RNA on survivin mRNA expression in transfected cells was examined by RT-PCR.Results: The correct construction of the recombinant plasmid has been shown by restriction enzyme digestion and DNA sequencing. As compared to controls, the level of survivin mRNA expression in transfected cells decreased significantly.Conclusion: An antisense RNA vector for survivin has been successfully constructed and may be useful as a specific inhibitor in leukemia cells. Thus, antisense therapy on the basis of survivin can be further explored in leukemia. Key words leukemia - survivin - antisense RNA This project was supported by a grant from National Key Basis Research Program of China (No. CB 513109) and the National Natural Sciences Foundation of China (No. 39970693).

Effects of Ghrelin Antisense Inhibition on VEGF and Its Receptor Flt-1 mRNA Expression

[ Objective] This study was to investigate the effect of VEGF and its receptor Fit-1 mRNA expression in Mongolia sheep umbilical vein endothelial cells by ghrelin antisense inhibition. [ Method] Experiments were divided into 4 groups： group Ⅰ （blank control group） ; group Ⅱ （liposome group） ; group Ⅲ （SCON group： 20 μmol/L sense oligonucleotide） ; group Ⅳ （ASCON： 20 μmol/L antisense oligonucleotide）. VEGF and its receptor Fit-1 mRNA expression changes were detected by using real-time fluorescence quantitative detection after 24, 36 and 48 h. [ Result] The expression of VEGF mRNA in group Ⅰ, group Ⅱ were insignificantly different at higher expression levels, and did not change significantly with the time; the expression of VEGF mRNA in group Ⅲ assumed a slight decrease, but there were no significant differences between group I and group Ⅱ （P 〉0.05）, the expression of VEGF mRNA in group Ⅳ（antisense oligonucleotide group ） decreased significantly （P 〈 0.05） ; the expression of VEGF receptor FLT-1 mRNA was similar to that of VEGF. [ Conclusion] Antisense inhibition ghrelin has a downward effect to the expression of VEGF and its receptor Fit-1 the mRNA.

Apoptosis and Lipolysis of White Adipocytes Induced by Neuropeptide Y- Y5 Receptor Antisense Oligodeoxynucleotides

Objective: To investigate the influence of central administration ofneuropeptide Y-Y5 receptor antisense oligodeoxynucleotides (ODNs) on body weight, fat pads of SDrats, and the effects of white adipocytes lipolysis and apoptosis. Methods: Y5 receptor antisense,sense, mismatched ODNs or vehicle was intracerebroventricularly (i. c. v.) injected. Averageadipocyte area was calculated. DNA ladders were measured to evaluate adipocyte apoptosis, and RT-PCRwas used to analyse the expression of Bcl-2 and Bax gene. Results: Central administration of Y5antisense ODNs significantly decreased body weight, and average adipocyte area. DNA fragmentationwas present after electrophoresis at epididymal adipose tissue. The expression of Bcl-2 gene wasdownregulated, while the expression of Bax upregulated. Conclusion: Lipolysis and adipocyteapoptosis may be important mechanisms far 75 antisense therapy.

Effect of Bcl-2 Antisense Oligodeoxynucleotides on Human Lung Carcinoma Transplanted Subcutaneously in Nude Mice

Objective： To investigate the inhibitory effects of the Bcl-2 antisense oligodeoxynucleotides （ASODN） on tumor formation and growth of human lung carcinoma transplanted subcutaneously in nude mice. Methods： Human NCI-H460 cells treated with Bcl-2 ASODN or nonesense oligodeoxynucleotide （NSODN） and untreated NCI-H460 cells were respectively implanted subcutaneously into nude mice. When the diameters of tumor were above 0.5 cm after untreated NCI-H460 cells injection, the mice bearing tumor were randomly divided into three groups： saline control group, Bcl-2 ASODN group, NSODN group. ODN was directly injected into the tumor body for 3 weeks. The weight and volume of subcutaneous tumors were measured, and the morphology of tumor cells was observed. Results： The tumorigenic ability of the treated NCI-H460 cells by Bcl-2 ASODN was reduced. The mean time at which tumor can be detected was prolonged up to 12.6 days （P〈0.01）. The maximum tumor growth inhibitory rate was 87.5%. In therapeutic efficacy, growth of tumor was significantly inhibited in Bcl-2 ASODN group as compared with that in NSODN group, saline-treated group （P〈0.01）. The NSODN control was ineffective. In comparison with NSODN-treated, saline-treated mice, those treated with Bcl-2 ASODN showed a significant decrease in median weight of subcutaneous tumors （P〈0.01）. The growth inhibitory rate was 71.0% in ASODN group. Conclusion： Bcl-2 ASODN could inhibit tumor formation and tumor growth in nude mice.

Selection of Effective Bcl-2 Antisense Oligodeoxynucleotides with Computer Software and Experimental Assay

Objective： To explore and investigate the selection of effective antisense oligodeoxynuleotides with the help of computer and RNAstructure folding software. Methods： Bcl-2 gene was used as the target gene and five antisense oligodeoxynuleotides were designed to be bound to Bcl-2 mRNA optimal secondary structure regions that were predicted free from intramolecular fold or instability of free energy. The five antisense oligodeoxynucleotides were studied with experimental assay of leukemia cells, including cell grow assay with tropan blue exclusion, expression of Bcl-2 protein detected with immunochemistry and flowcytometry, Bcl-2 mRNA content detected with RT-PCR technique, as well as apoptosis observed and determined with morphonological method, electrophoresis and flowcytometry. Results： The results showed that two of the five antisense oligodeoxynucleotides were effective antisense oligodeoxynucleotides, which were able to inhibit cell growth in leukemia, to decrease the level of Bcl-2 mRNA and protein, to induce apoptosis of leukemia cells significantly. Conclusion： The computational prediction of antisense efficacy is faster than other methods and more efficient, which can potentially speed the development of sequences for both research and clinical applications.

Apoptosis Induced by Bcl-2 Antisense Peptide Acid in HL60 Cells

Objective To study the differences and similarities of the antisense drugs with different structures on the biological functions of HL60 cells. Methods Cytotoxic effects were measured by cell viability assay. The expression levels of protein were assayed by immunofluorescence using fluoresce isothiocyanate label. The morphological changes in apoptotic cells were observed. Flow cytometric analysis of DNA fragmentation was also performed. Results Antisense peptide nucleic acid (PNA) targeting the coding region of the Bcl-2 mRNA could effectively inhibit the growth of HL60 cells, down-regulate the synthesis of Bcl-2 protein and induce apoptosis. After HL60 cells were treated with 10 μmol/L Bcl-2 antisense PNA or antisense oligonucleotide for 72 h respectively, apoptotic rates of HL60 cells were 17.80±1.53 and 13.17±1.12, respectively( P <0.05). Conclusion Antisense PNA targeting the coding region of Bcl-2 mRNA may have stronger antisense effects than the antisense oligonucleotides and could induce apoptosis of HL60 cells.

Antisense telomerase RNA induced human gastric cancer cell apoptosis

INTRODUCTION Human tissue homeostasis is precisely regulated bycellular division,differentiation and death.Normalhuman somatic cells progressively lose telomererestriction fragment(TRF)length with eachsuccessive cell division,eventually leading tocellular quiescence,chromosomal end-degradationand apoptosis.On the contrary,stabilization oftelomere lengths by expressing telomerase,an RNA-dependent DNA polymerase,may be involved incellular immortality and carcinogenesis.

Antisense to cyclin D1 reverses the transformed phenotype of human gastric cancer cells

AIM To further investigate the effect of cyclin D1 on the biologic behavior of cancer cells and its potential role in gene therapy of tumor. METHODS A cyclin D1 subcloning plasmid termed BKSD1 was constructed by subcloning the human cyclin D1 cDNA into Bluescript KS, a plasmid vector with a pair of T7 and T3 promoters, with recombinant DNA technology of molecular biology. So, it is easy to generate digoxigenin (DIG) labeled RNA probes of antisense and sense to cyclin D1 using RKSD1 as a template vector. PDORD1AS, an eukaryotic expression vector containing the full length human cyclin D1 cDNA in its antisense orientation cloned into the retroviral vector pDOR neo, was successfully constructed with BKSD1 to change restriction sites. A gastric cancer cell line, SGC7901/VCR, was transfected with pDORD1AS by Lipofect Amine mediated introduction and a subline termed SGC7901/VCRD1AS, which had stable overexpression of antisense RNA to cyclin D1, was obtained by selection in G418. The subline, control subline transfected pDOR neo and SGC7901/VCR were evaluated by methods of immunohistochemistry, flow cytometry, molecular hybridization, morphology and cell biology. RESULTS Compared with control cell lines, SGC7901/VCRD1AS had a reduced expression of cyclin D1 (inhibition rate was about 36%), increased cell size and cytoplasm to nucleus ratio, increased doubling time (42 2h to 26 8h and 26 4h), decreased saturation density (18 9×10 4 to 4 8×10 5 and 4 8×10 5), increased percentage of cells in the G1/G0 phase (80 9%-64 6% and 63 8%), reacquired serum dependence, and a loss of tumorigenicity in nude mice (0/4 to 4/4 and 4/4). CONCLUSION Stable overexpression of antisense RNA to cyclin D1 can reverse the transformed phenotype of human gastric cancer cells and may provide an approach of gene therapy for gastric cancer.

Inhibitory effect of IGF-Ⅱ antisense RNA on malignant phenotype of hepatocellular carcinoma

INIRODUCTIONAccording to the therapeutic effect and strategy ofantisense RNA for hepatoccllular carcinoma(HCC),we have specifically synthesized partialcDNA of human insulin-like growth factor Ⅱ(IGF-Ⅱ)and constructed IGF-Ⅱ cDNA antisenseeukaryotic expression vector.The constructedvector was introduced into hepatoma cell lineSMMC-7721 to block the intrinsic IGF-Ⅱexpression.The biological behavior changes ofhepatoma cells were observed.All these

Sequencing of PCR amplified HBV DNA pre-c and c regions in 2.2.15 cells and antiviral action by targeted antisense oligonucleotide directed against sequence

AIM To study the specific inhibition of HBV gene expression by liver-targeting antisense oligonucleotide (ASON) directed against pre-c and c regious in a sequence-specific manner.METHODS According to the result of direct sequencing of PCR amplified products, a 16-mer phosphorothioate analogue of the antisense oligonucleotide (PS-ASOn) directed against the HBV U5-like region was synthesized and then linked with one live-targeting ligand, the galactosylated poly-L-lysine. Their effect on the expression of HBV gene was observed using the 2.2.15 cells.RESULTS HBV DNA in the 2.2.15 cells was from HBV with surface antigen subtype ayw1 by sequencing so that antisense oligonucleotides could bind specifically to the target sequence through base piring. Under the same experimental conditions, the inhibitory rates of PS-ASON to HBsAg and HBeAg were 70% and 58% at a concentration of 10μmol/L, while by ligand-PS-ASON they were 96% and 82%, the amount of HBV DNA in cultured supernatant and cells was reduced significantly. An unrelated sequence oligonucleotide showed no effectiveness. All the oligonucleotides had no cytotoxicity.CONCLUSION Antisense oligonucleotides complexed by the liver-targeting ligand can be targeted to cells via asialoglycoprotein receptors, resulting in supecific inhibition of HBV gene expression and replication.

Transduction of Fas gene or Bcl-2 antisense RNA sensitizes cultured drug resistant gastric cancer cells to chemotherapeutic drugs

AIM To compare the expression level of Fas gene and Bcl-2 gene in gastric cancer cells SGC7901 and gastric cancer MDR (multidrug resistant) cells SGC7901/VCR, to transduce Fas cDNA and Bcl-2 antisense nucleic acid into SGC7901/VCR cells respectively, and to observe the expression of two genes in transfectants and non-transfectants as well as their drug sensitivity.METHODS Eukaryotic expression vector pBK-Fas cDNA and pDOR-anti Bcl-2 were constructed and transfected into SGC7901/VCR cells by lipofectamine, respectively. Northern blot and Western blot were used to detect the expression of mRNA and protein in SGC7901/VCR and SGC7901 cells and transfectants, and drug sensitivity of transfectants for VCR, CDDP and 5-FU was analyzed with MTT assay.RESULTS After gene transfection, 80 for Fas and 120 for antisense Bcl-2 drug-resistant clones were selected from 2×105 cells, transfection rate being 0.04% and 0.06%. Two clones of SGC7901 Fas/VCR cells and SGC7901 anti Bcl-2/VCR cells were randomly selected for further incubation. Hybridization results showed that the expression level of Fas mRNA and protein in SGC7901/VCR cells was much lower, but that of Bcl-2 mRNA and protein was higher than that in SGC7901 cells. The expression of Fas mRNA and protein in SGC7901 Fas/VCR cells was higher, and of Bcl-2 mRNA and protein was lower in SGC7901 anti Bcl-2/VCR cells than that in non-transfectants. MTT assay showed that transfectants were more sensitive to VCR, CDDP, 5-FU than non-transfectants.CONCLUSION Bcl-2 gene displayed high expression while Fas gene had low expression in drug resistant gastric cancer cells. Expression of Bcl-2 protein was effectively blocked in SGC7901 anti Bcl-2/VCR cells by gene transfection. In contrast, the expression of Fas mRNA and protein in SGC7901 Fas/VCR cells increased. Fas gene and Bcl-2 antisense nucleic acid transfection sensitized drug resistant gastric cancer cells to chemotherapeutic drugs. These results suggest cell apoptosis plays an important role in the mechanism of MDR, and enhancing apoptosis might reverse MDR.