| Malignant tumors do heavily harm to human health and life. It has taken the lead over the disease of the heart and cerebral veins and become the first-leading disease in life. It's estimated that there will be more than 7,000,000 death every year worldwide, among which ocurred 2,000,000 new cases of tumor and 1,600,000 death yearly in our country. Despite new insights into the molecular pathogenesis and improvements in traditional surgery, radiotherapy and chemotherapy, many middle or later magnant tumors can't be cured. This underlines the critical need for novel therapeutic strategies to treat the malignant cancer. Gene therapy in clinical trial has not broken through in essential to this day yet.It's recently reported that an ElB55kDa-deleted replication competent adenovirus, ONYX-015, obtained 63% therapeutic rate when combined with 5-FU and cisplatin in its Phase II trials for recurrent head and neck tumors. However, only 15% remission rate can be seen when using ONYX-015 alone. To address this problem, a new E1B55 kDa-deleted adenovirus (ZD55) was constructed, which is similar to but a little different from ONYX015. ZD55 has a Bgl II cloning site and can be inserted into foreign anticancer genes. We constructed an gene-virus ZD55-hTRAIL by insertion ofthe hTRAIL expression Cassette gene into ZD55. Moreover, this thesis was just focused on the following two aspects based on the ZD55-hTRAIL.Combination Of Targeting Gene-ViroTherapy with 5-FU Enhances Antitumor Efficacy in Malignant Colorectal Carcinoma: The ZD55 was armed with the therapeutic gene hTRAIL to form ZD55-hTRAIL which was used for cancer therapy and was called Targeting Gene-ViroTherapy by us. In vitro experiments with SW620, HCT116 and HT29 colorectal carcinoma cell lines demonstrated that they were all sensitive to ZD55-hTRAIL, especially most sensitive to ZD55-hTRAIL plus 5-FU treatment. In SW620 xenograft tumor model various treatment groups showed markedly difference at the 11th weak, with the tumor volume for PBS treatment group >1700 mm3, 5-FU>1300 mm3, ONYX015 for 1051.3 mm3, ZD55-hTRAIL for 600.05 mm3, and ZD55-hTRAIL plus 5-FU for 230.2 mm3. At the end of the 14th week, tumor bearing mice in other groups were almost all died but all the mice in the combined treated group still alived with one mouse tumor-free. By TEM assay, tumor cells treated with ONYX015, ZD55-hTRAIL single or in combination with 5-FU were mostly lysed due to the viral propagation. RT-PCR analysis and immunohistochemistry examination revealed that hTRAIL expressed in ZD55-hTRAIL treated SW620 tumor tissue. Furthermore, no detectable hepatoxicity was found by serum enzyme levels analysis. These results suggest that ZD55-hTRAIL alone or in combination with 5-FU may have potentially clinical implication. It has been no report on the armed replication competent adenovims with hTRAIL gene as well as the synergetic/augmentation effect of 5-FU on so farThe Combined Therapy with Human TRAIL and Plasminogen K5 Induced Complete Tumor Eradication via Tumor-Specific Replicating Adenovims-a Targeting Dual Gene-ViroTherapy Strategy: Antitumor effect of Gene-ViroTherapy is better than virotherapy alone both in vitro and in vivo, but in the study all the established tumors could not reach complete regression . To strengthen our above idea of targeting gene-viroTherapy, the Targeting Dual Gene-ViroTherapy was worked outby using hTRAIL and k5 genes. Because ZD55-luc could augment selective expression of GFP in Ad-GFP infected cell lines by fluorescence assay, we deduced that the effect of ZD55-hTRAIL combinated with Ad-k5 would more efficient than ZD55-hTRAIL on tumor killing. Laterly, the combination therapy when the tumor reached to 60-80 mm3 resulted in perfectly regression of all the tumors at day 30. Mechanism of Targeting Dual Gene-ViroTherapy by the use of ZD55-hTRAIL and Ad-k5 were further analyzed. For hTRAIL gene, it has been proved that ZD55-hTRAIL could augment selectively antitumor activity though tumor apoptosis-induced effect of TRAIL in vitro by FACS and in viv... |
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