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Publications (7)18 Total impact

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    ABSTRACT: Currently, no curative treatments are available for late-stage metastatic or recurrent breast cancer, because the cancer tolerates both chemotherapy and endocrine therapy. In this study, we investigated the feasibility of a dual-regulated oncolytic adenoviral vector with a novel suicide gene to treat breast cancer. Following targeted gene virotherapy of conditionally replicating adenoviruses (CRAds), the novel suicide gene of multisubstrate deoxyribonucleoside kinase of Drosophila melanogaster (Dm-DNK) was inserted into the double-regulated oncolytic adenovirus SG500 to ensure more safety and enhanced antitumor activity against breast cancer both in vitro and in vivo. Selective replication, cell-killing efficacy, and cytotoxicity, combined with chemotherapeutics were investigated in several breast cell lines (MDA-MB-231 and MCF-7), normal cells (WI-38 and MRC-5), and human (MDA-MB-231) tumor models in vivo. The double-regulated SG500-dNK had high cell-killing activity in breast cancer. Replication was similar to wild-type in breast cells and was attenuated in normal cells. SG500-dNK combined with the chemotherapeutics (E)-5-(2-bromovinyl)-2′-deoxyuridine (Bvdu) and 2′,2′-difluoro-deoxycytidine (dFdC) resulted in synergistically enhanced cell killing and greatly improved antitumor efficacy in vitro or in breast xenografts in vivo. These data suggest that the novel oncolytic variant SG500-dNK is a promising candidate for targeting breast tumors specifically when combined with chemotherapeutics.
    Cancer letters 01/2013; 328(1):95–103. · 5.02 Impact Factor
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    ABSTRACT: In contrast to other enzymes, Drosophila melanogaster deoxyribonucleoside kinase (Dm-dNK) has a broad substrate specificity and high catalytic rate when transferred in human cells. This makes it a promising therapeutic agent when administered together with several cytotoxic nucleoside analogs, such as gemcitabine 2',2'-difluoro-deoxycytidine (dFdC). Therefore, lentiviral vectors, which potentially allow stable long-term transgene expression, are good candidates for gene delivery vehicles. In the present study, we successfully developed a lentivirus-mediated transgene expression system of Dm-dNK under the control of hTERT promoter against the breast cancer cell line (Bcap37), the gastric cancer cell line (SGC7901) and the normal fibroblast cell line (WI-38). Moreover, we also analyzed its targeted cytotoxicity in vitro with treatment of the prodrug dFdC. Bcap37 tumor growth was inhibited in nude mice. Both cancer cell lines exhibited apparent cytotoxicity when infected with recombinant lentivirus constructs expressing Dm-dNK. In contrast, lentivirus-infected WI-38 cells exhibited less cytotoxicity. These data suggested that Dm-dNK was sensitive to dFdC, and it resulted in synergistic growth inhibition and apoptosis induction in vitro. In addition, Lenti-hTERT-dNK/dFdC also suppressed tumor growth in vivo. Our results suggest that the Lenti-hTERT-dNK/dFdC system is a safe and feasible treatment strategy in the development of suicide gene therapy.
    International Journal of Molecular Medicine 06/2012; 30(3):659-65. · 1.96 Impact Factor
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    ABSTRACT: BACKGROUND: As a known regulator of apoptosis, survivin has positive relationship with lymphatic metastasis in breast cancer. This study aims to detect the difference in expression between survivin and vascular endothelial growth factor-C (VEGF-C) in treated breast cancer cells and tissues, and to analyze the correlation among survivin, VEGF-C and lymphatic metastasis. METHODS: Plasmid with survivin and VEGF-C shRNA and lentivirus with survivin gene were constructed and transfected into breast cancer cell ZR-75-30. Then the expressions of the two genes were examined using western blot analysis and real-time PCR. The change of invasiveness of breast cancer cells was assessed using matrigel invasion assay. Using immunohistochemistry, the expression of survivin and VEGF-C were analyzed in 108 clinical breast cancer cases with breast cancer tissue and lymph node. RESULTS: Survivin regulated the expression of VEGF-C at both protein and mRNA levels in breast cancer cells. Immunohistochemical analysis showed that the level of VEGF-C expression was significantly related with that of survivin in breast cancer tissues (p<0.05). VEGF-C was found to participate in the process of breast cancer cells invasion mediated by survivin. The co-expression of the two and the single expression of any one took significant difference in positive lymph node (p<0.05). CONCLUSIONS: Survivin takes an important part in regulating the expression of VEGF-C. VEGF-C could influence the invasive ability mediated by survivin. The co-expression of survivin and VEGF-C is more statistically significant to assess lymphatic metastasis in breast cancer. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9193530897100952.
    Diagnostic Pathology 05/2012; 7(1):52. · 2.41 Impact Factor
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    ABSTRACT: Drosophila melanogaster multisubstrate deoxyribonucleoside kinase (Dm-dNK) was applied as a cancer gene therapeutic approach. To improve the antitumor effect of Dm-dNK, a novel suicide gene system based on an oncolytic adenovirus vector was developed to produce therapeutic effects towards colorectal cancer cells. We constructed an oncolytic adenoviral vector (ZD55), which was designed by deletion of the E1B-55 kDa gene for selective replication in tumor cells, containing suicide gene (Dm-dNK) driven by a cytomegalovirus promoter. We analysed the expression and activity of Dm-dNK in colorectal cancer cells (HCT-116 and SW620) via reverse transcription (RT)-PCR and enzyme assay. We assessed selective cytotoxic effects of Dm-dNK with the presence of the analogs (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU), difluorodeoxycytidine (dFdC) or 1-β-D-arabinofuranosylthymine (ara-T) by MTT and FACS; the variation of oncolytic adenovirus was detected by titer assay and western blot analysis. Our data showed that ZD55-Dm-dNK mediated high expression of Dm-dNK in HCT-116 and SW620 cancer cell lines and low levels of expression in WI-38 and MRC-5 normal cells, strong cytotoxicity was observed only in tumor cells after ZD55-Dm-dNK infection combined with nucleoside analogs (NA). When ZD55-Dm-dNK was combined with BVDU or dFdC, it produced a synergistic inhibitive effect of adenovirus replication while maintaining specific cancer cell killing activity. The results suggest that the novel oncolytic virus ZD55-Dm-dNK, in combination with NA, has potential as an efficient selective antitumoral agent and may produce synergistic effects in safe control of adenovirus, which is a new promising therapeutic for colorectal cancer.
    Oncology Reports 05/2012; 27(5):1443-50. · 2.30 Impact Factor
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    ABSTRACT: Deoxyribonucleoside kinase of Drosophila melanogaster (Dm-dNK) mutants have been reported to exert suicide gene effects in combined gene/chemotherapy of cancer. Here, we aimed to further evaluate the capacity of the mutanted enzyme and its potential for inhibiting cancer cell growth. We altered the sequence of the last 10 amino acids of Dm-dNK to perform site-directed mutagenesis and constructed active site mutanted Dm-dNK (Dm-dNKmut), RT-PCR and western bloting studies were used to reveal the expression of lentivirus mediated Dm-dNKmut in a breast cancer cell line (Bcap37), a gastric cancer cell line (SGC7901) and a colorectal cancer cell line (CCL187). [3H]-labeled substrates were used for enzyme activity assays, cell cytotoxicity was assessed by MTT assays, cell proliferation using a hemocytometer and apoptosis induction by thenannexin-V-FITC labeled FACS method. In vivo, an animal study was set out in which BALB/C nude mice bearing tumors were treated with lentivirus mediated expression of Dm-dNKmut with the pyrimidine nucleoside analog brivudine (BVDU, (E)-5-(2-bromovinyl)-(2-deoxyuridine). The Dm-dNKmut could be stably expressed in the cancer cell lines and retained its enzymatic activity. Moreover, the cells expressing Dm-dNKmut exhibited increased sensitivity in combination with BVDU, with induction of apoptosis in vitro and in vivo. These findings underlined the importance of BVDU phosphorylated by Dm-dNKmut in transduced cancer cells and the potential role of Dm-dNKmut as a suicide gene, thus providing the basis for future intensive research for cancer therapy.
    Asian Pacific journal of cancer prevention: APJCP 01/2012; 13(5):2121-7. · 1.50 Impact Factor
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    ABSTRACT: The multisubstrate deoxyribonucleoside kinase of Drosophila melanogaster (Dm-dNK) was investigated for its broader substrate specificity and higher catalytic rate as a suicide gene in a combined gene/chemotherapy of cancer. To evaluate the effects of nucleoside analog phosphorylation by Dm-dNK in vitro and in vivo, we generated a replication-deficient retroviral vector expressing Dm-dNK to transduce human breast cancer cells MCF7 (ER+) and MDA-MB-231 (ER-). We further determined the enzymatic activity and the sensitivity of the nontransduced and Dm-dNK-transduced 231/dNK and MCF7/dNK cells to the pyrimidine nucleoside analogs araC and araT. The data obtained show that Dm-dNK is enzymatically active and its overexpression in the nuclei of breast cancer cells results in an increased sensitivity to the nucleoside analogs araC and araT in vitro. Furthermore, subcutaneously transplanted 231/dNK cells were significantly inhibited after araC treatment, whereas nontransduced cancer cells continued to grow and develop in vivo. These results suggest that the Dm-dNK/nucleoside analog system could be a novel therapeutic strategy for treating breast cancer and improving anti-tumor efficacy, as well as for optimizing approaches for suicide gene therapy.
    The Journal of Gene Medicine 06/2011; 13(6):305-11. · 2.16 Impact Factor
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    ABSTRACT: The purpose of this analysis was to investigate the enzyme activity and specificity of adenovirus-mediated Drosophila melanogaster deoxyribonucleoside kinase (Dm-dNK) mutants in combination with gemcitabine. Compared to herpes simplex type 1 thymidine kinases (HSV-TK) and other known dNKs, this Dm-dNK enzyme has a broader substrate specificity and a higher catalytic rate. We created the Dm-dNK mutants (dNKmut) by site-directed mutagenesis at the sites of 244E, 245S, 251S, and 252R, with the last 10 amino acids in the amino acid sequence randomly alternated. We subsequently evaluated the enzyme activity and substrate specificity. The engineered enzymes showed a relative increase in phosphorylation in the nucleoside analogs of gemcitabine (dFdC, 2',2'-difluoro-deoxycytidine) compared to the wild-type enzyme. The dNKmut enzymes were expressed in breast (Bcap37) and gastric (SGC-7901) cancer cell lines. In studying the sensitivity of the cell lines to dFdC, conditionally replicative adenovirus (CRAd) ZD55-dNKmut showed higher expression and enzymatic activity than the replication-defective adenovirus Ad-dNKmut in cancer cells, but with less cytotoxicity to cancer cells than that of Ad-dNKmut. Our data suggest that the triple phosphorylated dFdC catalyzed by dNKmut inhibited the replication of adenovirus with a simultaneous positive therapeutic effect on cancer cells. Therefore, concomitant use of the ZD55-dNKmut and dFdC could be a novel targeted strategy in suicide gene therapy with safe control of excessive virus replication.
    International Journal of Oncology 03/2011; 38(3):745-53. · 2.66 Impact Factor