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Anti-calcyclin binding protein (CacyBP) monoclonal antibodies (MAb) were produced using an in vitro immunization method. BALB/c mouse splenocytes were immunized with purified 6 x His-CacyBP fusion protein and fused with myeloma cells using polyethylene glycol (PEG) 4000. By selection using enzyme-linked immunosorbent assay (ELISA), three anti-CacyBP MAbs were obtained. The MAb BD1, whose isotype was IgG1, interacted with the fusion protein. Western blot and immunofluorescence microscopy showed that the MAb BD1 against CacyBP could recognize CacyBP protein derived from human gastric cancer cell lines in both native and denatured forms. This MAb would act as a useful tool for the detection of CacyBP protein in future studies.

Although tamoxifen (TAM), a selective estrogen receptor modulator, has been widely used in the treatment of hormone-responsive breast cancer, its estrogen-like effect increases the risk of endometrial cancer. However, the molecular mechanisms of TAM-induced endometrial carcinoma still remain unclear. In this report, we explored the role of microRNAs (miRNAs) in TAM-induced epithelial-mesenchymal transition (EMT) in ECC-1 and Ishikawa endometrial cancer cell lines and found miR-200 is involved in this process via the regulation of c-Myc. When treated with TAM, ECC-1 and Ishikawa cells were characterized by higher invasiveness and motility and underwent EMT. miR-200, a miRNA family with tumor suppressive functions in a wide range of cancers, was found reduced in response to TAM treatment. Consistent with zinc finger E-box binding homeobox 2, which was confirmed as a direct target of miR-200b in endometrial cancer cell lines, some other key factors of EMT such as Snail and N-cadherin increased, whereas E-cadherin decreased in the TAM-treated cells, contributing to TAM-induced EMT in these endometrial cancer cells. In addition, we showed that c-Myc directly binds to and represses the promoter of miR-200 miRNAs, and its up-regulation in TAM-treated endometrial cancer cells leads to the down-regulation of miR-200 and eventually to EMT. Collectively, our data suggest that TAM can repress the miR-200 family and induce EMT via the up-regulation of c-Myc in endometrial cancer cells. These findings describe a possible mechanism of TAM-induced EMT in endometrial cancer and provide a potential new therapeutic strategy for it.

To construct a recombinant adenovirus vector carrying antisense heat shock protein 70 (HSP70) cDNA and observe its effect on inhibiting the growth of laryngeal carcinoma Hep-2 cells.The HSP70 gene fragment encoding the 5' region was cloned reversely into the shuttle plasmid PAdTrack-CMV, and the resultant plasmid was recombined with the backbone plasmid PadEasy-1 in the E.coli Bj5183 cells to generate the recombinant adenovirus vector. The adenovirus were then packaged and amplified in 293 cells, and the viral titer was determined using GFP.The recombinant adenovirus vector carrying antisense HSP70 cDNA was constructed successfully with a viral titer of 8 x 10(9). HSP70 expression of Hep-2 cells was obviously blocked by antisense HSP70 RNA, and Western blotting and immuohistochemistry demonstrated that cells transfected with antisense HSP70 did not express or express HSP70 at low levels. Flow cytometry presented apoptotic peak in the antisense HSP70-transfected cells, but not in the control cells.The recombinant adenovirus vector containing antisense HSP70 cDNA can effectively deliver antisense HSP70 gene into Hep-2 cells, suggesting the great potential of this gene therapy strategy in management of human laryngeal carcinoma.

To investigate the binding effect of the short peptide SY1 to the multidrug-resistant gastric cancer cell line SGC7901/VCR cells and its reversing effect on those cancer cells.The cultured cells were divided into two groups named SGC7901 and SGC7901/VCR. The SGC7901/VCR group was co-cultured with vincristine (VCR). SY1 was obtained from cyclic 7-mer peptide library by differential screening. Immunofluorescence technique was used to detect the capacity of SY1-containing positive phage specifically binding to SGC7901/VCR cells, compared with that of the negative phage and unrelated phage. MTT assay in vitro was performed to analyze the alteration of drug resistance of SGC7901/ VCR cells, using the positive phages and the chemically synthesized SY1 peptide. Flow cytometry assay was performed to detect the accumulation and retention of adriamycin (ADM) in the SGC7901/VCR cells.Immunofluorescence analysis showed that the SY1-containing positive phages could bind to the SGC7901/VCR cell surface but not to its parent cell line SGC7901 cells. The unrelated phage and negative phage did not bind to SGC7901/VCR cells. These results indicated that SY1 could specifically bind to SGC7901/VCR cells. MTT assay in vitro showed that the survival rate of SGC7901/VCR cells was reduced considerably by the positive phages and the chemically synthesized SY1 peptide (P0. 05), indicating that SY1 enhanced the sensitivity of SGC7901/VCR cells to chemotherapeutic drug VCR. Flow-cytometric detection showed that SY1 enhanced the accumulation of ADM in the SGC7901/VCR cells, compared with that of the negative phages and the unrelated phages (P0.05).SY1 not only is able to bind to SGC7901/VCR cells specifically, but also can partly reverse the resistance of SGC7901/VCR cell line to chemotherapeutic drug VCR. Those findings might be important to open a new approach to reverse the gastric cancer MDR.

To construct prokaryotic expression plasmid of RPS13, express and purify the protein for the preparation of polyclonal antibody.RPS13 gene was amplified by reverse transcription polymerase chain reaction (RT-PCR) from the highly expressed cell of gastric multidrug cell SGC7901/VCR. After sequenced, the gene was cloned into the expression vector pET-28a(+) to construct RPS13 expression plasmid pET-28a(+)-RPS13. The expression plasmid was transformed into the E.coli BL21 and screened by ampiline, and then the E.coli BL21 containing the expression plasmid was induced by IPTG and the protein was purifed by Histag column. BALB/c mice were immunized by the immunogen His-RPS13. The titer was measured by ELISA and the polyclonal antibody was obtained.The expression plasmid pET-28a(+)-RPS13 was constructed. The 19 kDa recombined protein was successfully expressed in the E.coli BL21 by IPTG for 3 hours, purified by Histag column and confirmed by SDS-PAGE and Western blot. The polyclonal anti-His-RPS13 antibody was obtained by immunizing the mice with RPS13 protein. RPS13 could be specifically recognized by the antibody based on Western blot.RPS13 has bene expressed and purified successfully and polyclonal anti-His-RPS13 antibody has been prepared. Our study can be used for the preparation of monoclonal anti-His-RPS13 antibody and for further research of the function of the RPS13 protein in tumor.

To study the effect of calcyclin binding protein (CacyBP) on the proliferation of gastric cancer cells.CacyBP siRNA expression vector was constructed and transfected into the gastric cancer cells of the line SGC7901 (SGC/CacyBP-siRNA cells). Blank vector mU6 was transfected too as control group (SGC/mU6 cells). Western blotting and semi-quantitative RT-PCR were used to detect the protein expression and mRNA expression of CacyBP in the transfected cells. Immunofluorescence staining was used to detect the intensity of green fluorescence. The cell growth was determined by MTT method. Western blotting and semi-quantitative RT-PCR were used to detect the protein expression and mRNA expression of beta-catenin, cyclooxygenase-2 (COX-2), cyclin D1, rac1, and heat shock protein (HSP) 70. The protein level of beta-catenin in the nuclei of the transfected cells was detected. Twenty-fife nude mice were randomly divided into 5 groups to be inoculated with the SGC7901 cells stably transfected with CacyBP siRNA expression vector and the size of tumor was observed 1, 2, 3, 4, and 5 weeks after the inoculation respectively. The blank vector mU6 was inoculated as control group.The mRNA expression and protein expression of endogenous CacyBP in the SGC/CacyBP-siRNA cells were both markedly lower than those of the SGC/mU6 cells. Immunofluorescence staining showed weaker green fluorescence in the SGC/CacyBP-siRNA cells than the SGC/mU6 cells. MTT method showed that the growth of the SGC/CacyBP-siRNA cells was significantly faster than that of the SGC/mU6 cells (P0.01). Western blotting showed remarkable up-regulation of the protein expression of beta-catenin, COX-2, cyclin D1, rac1, and HSP 70 in the SGC/CacyBP-siRNA cells; and semi-quantitative RT-PCR showed remarkable up-regulation of the mRNA expression of COX-2 and cyclin D1 in the SGC/CacyBP-siRNA cells, however, the mRNA expression of HPS70, rac1, and beta-catenin showed no significant differences between these 2 groups. The size of tumor of the mice inoculated with SGC/CacyBP-siRNA cells was significantly larger than that of the mice inoculate with SGC/mU6 cells (P0.01). The survival times of the nude mice inoculated with SGC/CacyBP-siRNA1 and SGC/CacyBP-siRNA1 cells respectively were 60 d +/- 8 d and 50 d +/- 4 d, both significantly shorter than that of the control group (75 d +/- 9 d, both P0.01).The down-regulation of CacyBP can promote the proliferation of gastric cancer cells and aggravate their malignant behavior.

To investigate the effect of gene Af116609 on gastric cancer multi-drug resistance (MDR) by introducing it into gastric cancer multi-drug resistant (MDR) cell line SGC7901/VCR.Gene Af116609 was cloned from SGC7901/VCR by RT-PCR and its differential expression between gastric cancer MDR cells and its parental cells was displayed by Northern blot. The gene was introduced to gastric cancer cells by transfection of recombinant eukaryotic expression vector by electroporation. MTT assay in vitro was applied to investigate its effect on multi-drug resistance phenotype of gastric cancer cells.The full length CDS of gene Af116609, as long as 327 bp, was cloned from gastric cancer MDR cell line SGC7901/VCR and its sequence was coincident with the hypothetical gene Af116609 in GenBank. It was overexpressed in MDR cells than its parental cells at mRNA level. In the MTT assay in vitro, the drug sensitive cells transfected with sense eukaryotic expression vector showed upregulated targeted gene, with increased resistance to vincristine, 5-fliorouracil and arabinoside, and decreased resistance to adriamycin, but no influence on resistance to methotrexate. However, the drug resistant cells transfected with anti-sense eukaryotic expression vector, showed down regulated targeted gene, with less resistance to all the five anticancer drugs to different degrees.Gene Af116609 is related to MDR phenotype of gastric cancer cells and may become a candidate molecular target to reverse the MDR of gastric cancer.

By means of phage-display technique, to screen polypeptides that specifically bind to human gastric cancer with high metastatic potential to peritoneum.Two human gastric cancer cell lines were used: GC9811-P with high metastatic potential to peritoneum and its wild type parental GC9811, to carry out subtractive screening with a phage display-12 peptide library.After three rounds of screening, 40 phage clones bond to GC9811-P cells were randomly selected. When injected into the peritoneal cavity of nude mice, 6 of the 40 clones did not bind to mouse peritoneum as examined by immunohistochemical staining. They were considered to be capable of binding specifically to GC9811-P cells. Sequence analysis revealed two different exogenous peptides: TLNINRLILPRT and SMSI(X)SPYI(XXX).Two peptides have been obtained that specifically bind to a gastric cancer cell variant GC9811-P, which easily disseminates to the peritoneum. Whether or not they could block GC9811-P metastasis to peritoneum in vivo remains to be determined.

To investigate the regulatory mechanisms of mitogen-activated protein kinase phosphatase-1 (MKP-1) in hypoxia inducible factor (HIF)-1 trans-activation.(1) Gastric cancer cells of the line SGC7901 were cultured, then continued to be cultured in hypoxic environment, and was lysed. The supernatant was collected. Western blotting was used to detect the content of total extracellular signal-regulated kinase (ERK) and phosphorylated ERK. (2) Another SGC7901 cells were cultured with PD98059, inhibitor of ERK passway, or SB203580, inhibitor of p38 passway, in the same manner as above-mentioned. Dual luciferase reporter (DLR) was used to detect the luciferase activity so as to measure the HIF-1 trans-activation. (3) siRNA vector U6M2 plasmid against MKP-1 mRNA was constructed. In another experiment SGC7901 cells were cultured and U6M2 and blank vector U6 were transfected into the cells respectively. 24 hours later, the cells were cultured in hypoxic environment with added PD98059 of different concentrations for 12 hours. Dual luciferase reporter (DLR) was used to detect the luciferase activity HIF-1 trans-activation. (4) Another SGC7901 cells were co-transfected with U6M2, pGL-3SV40HRE vector containing promoter SV40, and pRL-TK (internal control vector). Then PD98059 was added, the cells were lysed, and the activity of fluorescein was tested. (5) SGC7901 cells were cultured, transfected with UdM2 or U6 respectively, and 24 hours later cultured under hypoxia with PD98059 of different concentrations for 12 hours. ELISA was used to examine the VEGF protein concentration in the culture fluid.(1) The content of phosphorylated ERK in the SGC7901 cells increased along with the time of hypoxia, peaked at the 12th hour, and then decreased. However, there was no difference in total ERK expression. (2) After 12 hours of hypoxia, different concentrations of PD98059 inhibited the luciferase activity, however, SB203580 of different concentrations had no effect. (3) 24 hours after transfection, the expression of phosphorylated form of ERK in the SGC7901cells transfected with siRNA plasmid against MKP-1 mRNA was higher compared with that in cells transfected with blank vectors after 12 hour of exposure to hypoxia. (4) PD98059 inhibited the luciferase activity either in U6 cells or in U6M2 cells. Notably, when the PD98059 concentration was above 50 micromol/L, there was no difference in HIF-1 activity between the U6 and U6M2 cells. (5) PD98059 of different concentrations all inhibited the VEGF expression either in U6 cells or in U6M2 cells, and when the concentration of PD98059 was over 50 micromol/L there was no difference in VEGF expression level between the U6 cells and the U6M2 cells.In SGC7901 cells, the function of MKP-1 is involved in regulation of HIF-1 trans-activation via inactivation of the ERK pathway.

To investigate the role of human angiopoietin-1 (Ang1) in tumorigenesis and angiogenesis of human gastric cancer cell line SGC7901 in nude mice.Recombinant human Ang1 sense or antisense eukaryotic expression vectors were constructed, and transfected by lipofectin into human gastric cancer line SGC7901. Stable transfectants were obtained respectively, namely 7Ang1+ for sense, 7Ang1- for antisense, and 7901P for empty vector transfected cells. Semiquantitative PCR and Western blot were employed to testify the transfection efficiency. Cell growth curve and cell cycle were observed by MTT assays or flow cytometry. In in vivo study, growth of SGC7901 xeno-transplant was observed in BALB/c nude mice. Microvessel density (MVD) was analyzed by immunohistochemistry for Factor VIII staining.Stably transfected cell lines were established and decreased expression of Ang1 protein and mRNA in the antisense transfected SGC7901 cells was achieved. Tumorigenesis of 7Ang1- cells on day 30 days was significantly inhibited with decreased MVD as compared to that in 7901P and 7Ang1+ cells (P0.01).Angiopoietin-1 plays an important role in tumorigenesis and angiogenesis of gastric cancer which can be partially abrogated by antisense technique.

To investigate the significance of DARPP-32 protein expression in gastric carcinoma tissue and cell lines.The expression of DARPP-32 protein in normal gastric mucosa and gastric carcinoma tissue was evaluated by immunohistochemical staining using streptavidin-biotin complex technique. The expression in gastric carcinoma tissue and cell lines was evaluated by Western blotting.The expression rate of DARPP-32 protein in gastric adenocarcinoma tissue (92.7%) was significantly higher than that in normal gastric mucosa (52.6%, P0.05). There was no significant association between DARPP-32 protein expression and degree of tumor differentiation, local invasion and distant metastasis. As compared with adjacent non-carcinomatous gastric mucosa, both DARPP-32 and its truncated isoform t-DARPP were overexpressed in gastric adenocarcinoma tissue (t = 2.45, P = 0.015); and t-DARPP overexpression was more frequently seen. Expression of DARPP-32 and t-DARPP could also be detected in human gastric cancer cell lines. The expression of DARPP-32 protein was obviously reduced in SGC7901 drug-resistant cell strains.DARPP-32 is overexpressed in gastric carcinoma. It may play an important role in gastric carcinogenesis. The underlying signal pathways in neoplastic gastric epithelium may also be related to the multi-drug resistance property of gastric cancer cells.

To study the effect of alternative splicing form -MAD2beta of mitotic arrest deficient protein 2 (MAD2) on the formation of multidrug resistance in human gastric adenocarcinoma cell SGC7901.RNA was extracted from a multidrug resistance cell line SGC7901/ADR. The full-length MAD2beta cDNA was obtained by RT-PCR and cloned into the pUCm-T vector, and then recombined into the eukaryotic expression vector pcDNA3.1 in forward direction. Subsequently, pcDNA3.1/MAD2beta vectors were then transfected into SGC7901 cells by lipofectamine. Sensitivity to drug was detected by MTT assay. Cell cycle alteration and intracellular fluorescence intensity were determined by FACS.A fragment of 0.53 Kb was obtained and confirmed by DNA sequencing which was a new alternative splicing form of MAD2 named as MAD2beta. pcDNA3.1/MAD2beta transfected SGC7901 cells (SGC7901/MAD2beta) were more resistant to ADR, VCR and MMC than the control cells (SGC7901/pcDNA3.1), and also ADR fluorescence intensity of SGC7901/MAD2beta cells was lower (P0.05) than that of SGC7901/pcDNA3.1 cells.MAD2beta could increase the multidrug resistance of SGC7901 cell line.

To express hCacyBP in E.coli and prepare mouse polyclonal antibody against hCacyBP so as to study tissue distribution of hCacyBP and evaluate its role during formation of multidrug resistance to gastric cancer.hCacyBP gene was subcloned into an expression vector pET28a, and then the recombinant vector was transformed into E. coli BL21. The recombinant protein was expressed in BL21 under IPTG induction. Using purified hCacyBP as immunogen, mouse polyclonal antibody against hCacyBP was prepared. hCacyBP was detected by Western blot in 10 kinds of rabbit tissues. Expression and distribution of hCacyBP in SGC7901/VCR and SGC7901 cells were detected by Western blot and immunohistochemical staining.hCacyBP was successfully expressed in E. coli. The Western blot analysis showed that hCacyBP was expressed in all 10 kinds of rabbit tissues, but expression of brain and liver tissues were higher as compared with other tissues. Expression and distribution of hCacyBP in both SGC7901/VCR and SGC7901 cells had no significant difference.CacyBP expressed widespreadly in varied tissues. Polyclonal antibody against hCacyBP that we prepared has high specificity, which provides a powerful tool for studying the function of hCacyBP.

To study the expression of RhoC in human gastric cancer cell lines and to construct and identify the RhoC-specific siRNA expressing vector.The expression of RhoC in human gastric cancer cell lines was detected by Western blot. According to the computer aided design(CAD),RhoC-specific siRNA gene was synthesized and cloned into the expression vector mU6pro. The constructed RhoC-siRNA was transiently transfected into high-metastatic gastric cancer cell line AGS and the inhibition effect of RhoC-siRNA on expression of RhoC in AGS cells was detected using Western blot.The expression level of RhoC was up-regulated in high metastatic cells lines. Double enzyme digestion analysis and DNA sequencing confirmed that the RhoC-specific siRNA expression vector was constructed successfully. RhoC expression in AGS cells was specifically suppressed after transfection of RhoC-siRNA.The RhoC-specific siRNA expression vector has been successfully constructed, which may provide a novel applicable strategy for gene therapy of gastric cancer.

To investigate the expression status of Mitogen-activated Protein Kinase Phosphatase-1 in oxygen-deprived gastric cancer cell line SGC7901 and its role in HIF-1 regulation.The expression of MKP-1 in gastric cell line SGC7901 was detected with Western blot and semiquantity RT-PCR; Eukaryotic sense expression vector was constructed based on DNA recombination technology. Transfections of SGC7901 were performed using liposome; The luciferase activity was determined using Dual Luciferase Reporter System and the levels of VEGF in SGC7901cells under normoxia and hypoxia were measured by ELISA.(1) Semiquantity RT-PCR and Western blot suggested that the expression of MKP-1 was elevated in oxygen-deprived gastric cancer cell line SGC7901; (2) 48 hours after transfection, the phosphorylated form of HIF-1alpha in cell line transfected with recombinant plasmids was lower compared with that in cell line transfected with empty vectors after 12 hours of exposure to hypoxia; (3) There was very low luciferase activity under nomoxia while under hypoxia luciferase activity increased in a time-dependent manner and at all time points there was significant lower luciferase activity in SGC7901 cells than in cells transfected with empty plasmids. (4) At different points of time course, the expression of VEGF in SGC7901 was significantly higher under hypoxia than that in SGC7901 under nomorxia, while under hypoxia, the expression of VEGF in SGC7901 transfected with recombinant plasmids was significantly lower than that in SGC7901 transfected with empty vectors at all time points as indicated.The expression of MKP-1 in SGC7901 was elevated under hypoxia, which could downregulate the HIF-1 trans-activition activity thereby repressing the expression of downstream target gene VEGF.

To study the expression and possible function of RhoA in human gastric cancer cell lines.The expression of RhoA in human gastrointestinal cancer cell lines was detected by Western blot. Antisense plasmid of RhoA was constructed by pGEFL and transferred into gastric cancer cell line AGS by lipofectamine. Cell survival was examined by MTT assays, and cell cycle was detected by flow cytometry.The expression of RhoA protein in 10 different kinds of human cancer cell lines was much higher than that in immortalized human intestinal epithelial cell line. After being transfected with antisense RhoA, with the decrease in RhoA protein expression, the growth rate of AGS was inhibited, and the number of cells in S phase was increased by 14%.RhoA is overexpressed in many human cancer cell lines. Some of the malignant characteristics of a gastric cancer cell line can be partially reversed by inhibiting RhoA expression.

To investigate the significance of Rac subfamily members in the gastrointestinal carcinogenesis and progression.The mRNA expression of Rac1, Rac2 and Rac3 in 12 kinds of gastrointestinal cancer cell lines was examined by semi-quantitative RT-PCR. The activities of Rac1 protein in 5 kinds of gastric cancer cell lines were tested by pull-down assay.Compared with the normal gastric mucosa and intestinal epithelial cell line, the mRNA expression of Rac1 and Rac3 was up-regulated in most of gastrointestinal cancer cell lines. The activities of Rac1 protein increased markedly in gastric cancer cell lines.The increased mRNA expression of Rac1 and Rac3 in gastrointestinal cancer cell lines and the abnormal activation of Rac1 protein in gastric cancer cell lines might be correlated with the carcinogenesis of gastrointestinal cancer.

To investigate the overexpression of prion protein (PrP) in drug-resistant gastric cancer cell line SGC7901/ADR and its role in multidrug resistance in gastric cancer.(1) The expression of PrP in SGC7901/ADR, SGC790/VCR and their parental cell line SGC7901 was detected with Northern and Western blot at the mRNA and protein level. (2) Eukaryotic sense and antisense expression vector were constructed based on DNA recombination technology and (3) introduced into SGC7901 and SGC7901/ADR cell lines through electroporation. (4) The accumulation and retention of ADR in transiently transfected cells were detected by flow cytometry.(1) Northern and western blot suggested significantly higher expression of PrP in SGC7901/ADR and SGC7901/VCR than that in SGC7901. (2) 48 hours after the vectors transfection, the average fluorescence intensity of Adr in transfected cells were detected. The accumulation intensity were 8.9 +/- 0.7 in BS, 6.6 +/- 0.3 in PS and 7.5 +/- 0.6 in PA. The retention intensity were 9.3 +/- 0.6 in SGC7901, 5.9 +/- 0.5 in PS and 7.1 +/- 0.5 in PA. There were significant difference between PS and BS with P0.01, as well as RA and BA with P0.01. These data suggested that PrP gene could affect the drug accumulation in gastric cancer cells after its transfected into cells.PrP was highly expressed in gastric cancer cell lines SGC7901/ADR and SGC7901/VCR. Overexpression of PrP had certain effect on drug accumulation in gastric cancer cells.

To study the expression and function of zinc ribbon gene ZNRD1 in drug-resistant cells of gastric cancer.Two tumor cell lines were used in this study: gastric cancer SGC7901 and its drug-resistant counterpart SGC7901/VCR stepwise-selected by vincristine. The expression of ZNRD1 in SGC7901 and SGC7901/VCR was detected by northern blot and semiquantitative RT-PCR. ZNRD1 antisense nucleic acid was transfected into SGC7901/VCR cells by lipofectamine. The expression of protein in SGC7901/VCR cells and the transfectants was detected by immunochemical method. Fluorescence activated cell scan (FACS) was applied to observe the cell cycle alteration. Growth curve and drug sensitization of cells for vincristine (VCR) and adriamycin (ADM) were analyzed by MTT assay.The expression of ZNRD1 was higher in SGC7901/VCR than in SGC7901 cells. Immunochemical results showed that the expression level of ZNRD1 protein was lower in anti ZNRD1-SGC7901/VCR cells than in non-transfectants. The anti ZNRD1-SGC7901/VCR cells were gradually accumulated in G(1) phase, with a concomitant decrease of cell population in S phase. MTT assay showed that transfectant cell proliferation was lagged and more sensitive to VCR and ADM than non-transfectants.ZNRD1 gene displays high expression in VCR resistant gastric cancer cells. Expression of ZNRD1 protein is effectively blocked in anti ZNRD1-SGC7901/VCR cells by gene transfection. ZNRD1 antisense nucleic acid could reverse, to some degree, the MDR of human drug-resistant gastric cancer cell SGC7901/VCR.