Combined oncolytic adenovirus carrying MnSOD and mK5 genes both regulated by survivin promoter has a synergistic inhibitory effect on gastric cancer.

Gastric cancer (GC) is one of the major causes of cancer-related mortality. The use of oncolytic virus for cancer gene-virotherapy is a new approach for the treatment of human cancers. In this study, a novel Survivin promoter-driven recombinant oncolytic adenovirus carrying mK5 or MnSOD gene was constructed, which was modified after deletion of the E1B gene. Human plasminogen Kringle 5 mutant (mK5) and manganese superoxide dismutase (MnSOD) are both potential tumor suppressor genes. By constructing Ad-Surp-mK5 and Ad-Surp-MnSOD oncolytic adenoviruses, we hypothesized that the combination of the two viruses would enhance the therapeutic efficacy of GC as compared to the one virus alone. The results of the in vitro experiments revealed that the combination of adenovirus carrying mK5 and MnSOD gene exhibited stronger cytotoxicity to GC cell lines as compared to the virus alone. Additionally, the virus could selectively kill cancer cells and human somatic cells. Cell staining, flow cytometry, and western blot analysis showed that the combination of two adenoviruses containing therapeutic genes could promote the apoptosis of cancer cells. In vivo experiments further verified that Ad-Surp-mK5 in combination with Ad-Surp-MnSOD exhibited a significant inhibitory effect on the growth of GC tumor xenograft as compared to the virus alone, and no significant difference was observed in the bodyweight of treatment and the normal mice. In conclusion, the combination of our two newly constructed recombinant oncolytic adenoviruses containing mK5 or MnSOD therapeutic genes could significantly inhibit gastric cancer growth by inducing apoptosis, suggestive of its potential for GC therapy.

Enhanced anti-melanoma efficacy through a combination of the armed oncolytic adenovirus ZD55-IL-24 and immune checkpoint blockade in B16-bearing immunocompetent mouse model.

Although the recent treatment in melanoma through the use of anti-PD-1 immunotherapy is successful, the efficacy of this approach remains to be improved. Here, we explore the feasibility of combination strategy with the armed oncolytic adenovirus ZD55-IL-24 and PD-1 blockade. We find that combination therapy with localized ZD55-IL-24 and systemic PD-1 blockade leads to synergistic inhibition of both local and distant established tumors in B16-bearing immunocompetent mouse model. Our further mechanism investigation reveals that synergistic therapeutic effect is associated with marked promotion of tumor immune infiltration and recognition in both local and distant tumors as well as spleens. PD-1 blockade has no obvious effect on promotion of tumor immune infiltration and recognition. Localized therapy with ZD55-IL-24, however, can help PD-1 blockade to overcome the limitation of relatively low tumor immune infiltration and recognition. This study provides a rationale for investigation of such combination therapy in the clinic.

Overview of role of survivin in cancer: expression, regulation, functions, and its potential as a therapeutic target.

Survivin holds significant importance as a member of the inhibitor of apoptosis protein (IAP) family due to its predominant expression in tumours rather than normal terminally differentiated adult tissues. The high expression level of survivin in tumours is closely linked to chemotherapy resistance, heightened tumour recurrence, and increased tumour aggressiveness and serves as a negative prognostic factor for cancer patients. Consequently, survivin has emerged as a promising therapeutic target for cancer treatment. In this review, we delve into the various biological characteristics of survivin in cancers and its pivotal role in maintaining immune system homeostasis. Additionally, we explore different therapeutic strategies aimed at targeting survivin.

Double-modified oncolytic adenovirus armed with a recombinant interferon-like gene enhanced abscopal effects against malignant glioma.

Background: The development of new therapies for malignant gliomas has been stagnant for decades. Through the promising outcomes in clinical trials of oncolytic virotherapy, there is now a glimmer of hope in addressing this situation. To further enhance the antitumor immune response of oncolytic viruses, we have equipped a modified oncolytic adenovirus (oAds) with a recombinant interferon-like gene (YSCH-01) and conducted a comprehensive evaluation of the safety and efficacy of this modification compared to existing treatments. Methods: To assess the safety of YSCH-01, we administered the oAds intracranially to Syrian hamsters, which are susceptible to adenovirus. The efficacy of YSCH-01 in targeting glioma was evaluated through in vitro and in vivo experiments utilizing various human glioma cell lines. Furthermore, we employed a patient-derived xenograft model of recurrent glioblastoma to test the effectiveness of YSCH-01 against temozolomide. Results: By modifying the E1A and adding survivin promoter, the oAds have demonstrated remarkable safety and an impressive ability to selectively target tumor cells. In animal models, YSCH-01 exhibited potent therapeutic efficacy, particularly in terms of its distant effects. Additionally, YSCH-01 remains effective in inhibiting the recurrent GBM patient-derived xenograft model. Conclusions: Our initial findings confirm that a double-modified oncolytic adenovirus armed with a recombinant interferon-like gene is both safe and effective in the treatment of malignant glioma. Furthermore, when utilized in combination with a targeted therapy gene strategy, these oAds exhibit a more profound effect in tumor therapy and an enhanced ability to inhibit tumor growth at remote sites.

HCCS1-armed, quadruple-regulated oncolytic adenovirus specific for liver cancer as a cancer targeting gene-viro-therapy strategy.

BACKGROUND: In previously published studies, oncolytic adenovirus-mediated gene therapy has produced good results in targeting cancer cells. However, safety and efficacy, the two most important aspects in cancer therapy, remain serious challenges. The specific expression or deletion of replication related genes in an adenovirus has been frequently utilized to regulate the cancer cell specificity of a virus. Accordingly, in this study, we deleted 24 bp in E1A (bp924-bp947) and the entirety of E1B, including those genes encoding E1B 55kDa and E1B19kDa. We used the survivin promoter (SP) to control E1A in order to construct a new adenovirus vector named Ad.SP.E1A(Δ24).ΔE1B (briefly Ad.SPDD). HCCS1 (hepatocellular carcinoma suppressor 1) is a novel tumor suppressor gene that is able to specifically induce apoptosis in cancer cells. The expression cassette AFP-HCCS1-WPRE-SV40 was inserted into Ad.SPDD to form Ad.SPDD-HCCS1, enabling us to improve the safety and efficacy of oncolytic-mediated gene therapy for liver cancer. RESULTS: Ad.SPDD showed a decreased viral yield and less toxicity in normal cells but enhanced toxicity in liver cancer cells, compared with the cancer-specific adenovirus ZD55 (E1B55K deletion). Ad.SPDD-HCCS1 exhibited a potent anti-liver-cancer ability and decreased toxicity in vitro. Ad.SPDD-HCCS1 also showed a measurable capacity to inhibit Huh-7 xenograft tumor growth on nude mice. The underlying mechanism of Ad.SPDD-HCCS1-induced liver cancer cell death was found to be via the mitochondrial apoptosis pathway. CONCLUSIONS: These results demonstrate that Ad.SPDD-HCCS1 was able to elicit reduced toxicity and enhanced efficacy both in vitro and in vivo compared to a previously constructed oncolytic adenovirus. Ad.SPDD-HCCS1 could be a promising candidate for liver cancer therapy.

Optimization of the Administration Strategy for the Armed Oncolytic Adenovirus ZD55-IL-24 in Both Immunocompromised and Immunocompetent Mouse Models.

ZD55-IL-24 is an armed oncolytic adenovirus similar but superior to ONYX-015. Virotherapeutic strategies using ZD55-IL-24 have been demonstrated to be effective against several cancer types. However, it is unclear whether the traditional administration strategy is able to exert the maximal antitumor efficacy of ZD55-IL-24. In this study, we sought to optimize the administration strategy of ZD55-IL-24 in both A375-bearing immunocompromised mouse model and B16-bearing immunocompetent mouse model. Although the underlying antitumor mechanisms are quite different, the obtained results are similar in these two mouse tumor models. We find that the antitumor efficacy of ZD55-IL-24 increases as injection times increase in both of these two models. However, no obvious increase of efficacy is observed as the dose of each injection increases. Our further investigation reveals that the administration strategy of sustained ZD55-IL-24 therapy can achieve a better therapeutic effect than the traditional administration strategy of short-term ZD55-IL-24 therapy. Furthermore, there is no need to inject every day; every 2 or 3 days of injection achieves an equivalent therapeutic efficacy. Finally, we find that the sustained rather than the traditional short-term ZD55-IL-24 therapy can synergize with anti-PD-1 therapy to reject tumors in B16-bearing immunocompetent mouse model. These findings suggest that the past administration strategy of ZD55-IL-24 is in fact suboptimal and the antitumor efficacy can be further enhanced through administration strategy optimization. This study might shed some light on the development of clinically applicable administration regimens for ZD55-IL-24 therapy.

Targeting Gene-ViroTherapy for prostate cancer by DD3-driven oncolytic virus-harboring interleukin-24 gene.

Prostate cancer (PCa) is the second leading cause of cancer-related deaths in Western male population. Previous studies have demonstrated that differential display code 3 (DD3 or DD3(PCA3)) is one of the most PCa-specific genes; therefore, it has been used as a clinical diagnostic marker for PCa. In this study, we constructed an oncolytic adenovirus Ad.DD3-E1A by using the minimal DD3 promoter to replace the native viral promoter of E1A gene. In addition, Ad.DD3-E1A was armed with therapeutic gene IL-24 to enhance its antitumor activity. The resulting adenovirus, Ad.DD3-E1A-IL-24, demonstrated PCa specificity and excellent antitumor effect. Further analyses on its antitumor mechanism revealed that it has the capacity to induce apoptosis in PCa cells and inhibit angiogenesis. These results suggest that Ad.DD3-E1A-IL-24 is a promising antitumor agent that may be able to be used in the future as a treatment for PCa.

The armed oncolytic adenovirus ZD55-IL-24 eradicates melanoma by turning the tumor cells from the self-state into the nonself-state besides direct killing.

ZD55-IL-24 is similar but superior to the oncolytic adenovirus ONYX-015, yet the exact mechanism underlying the observed therapeutic effect is still not well understood. Here we sought to elucidate the underlying antitumor mechanism of ZD55-IL-24 in both immunocompetent and immunocompromised mouse model. We find that ZD55-IL-24 eradicates established melanoma in B16-bearing immunocompetent mouse model not through the classic direct killing pathway, but mainly through the indirect pathway of inducing systemic antitumor immunity. Inconsistent with the current prevailing view, our further results suggest that ZD55-IL-24 can induce antitumor immunity in B16-bearing immunocompetent mouse model in fact not due to its ability to lyse tumor cells and release the essential elements, such as tumor-associated antigens (TAAs), but due to its ability to put a "nonself" label in tumor cells and then turn the tumor cells from the "self" state into the "nonself" state without tumor cell death. The observed anti-melanoma efficacy of ZD55-IL-24 in B16-bearing immunocompetent mouse model was practically caused only by the viral vector. In addition, we also notice that ZD55-IL-24 can inhibit tumor growth in B16-bearing immunocompetent mouse model through inhibiting angiogenesis, despite it plays only a minor role. In contrast to B16-bearing immunocompetent mouse model, ZD55-IL-24 eliminates established melanoma in A375-bearing immunocompromised mouse model mainly through the classic direct killing pathway, but not through the antitumor immunity pathway and anti-angiogenesis pathway. These findings let us know ZD55-IL-24 more comprehensive and profound, and provide a sounder theoretical foundation for its future modification and drug development.

A double-regulated oncolytic adenovirus with improved safety for adenocarcinoma therapy.

Safety and efficiency are equally important to be considered in developing oncolytic adenovirus. Previously, we have reported that ZD55, an oncolytic adenovirus with the deletion of E1B-55K gene, exhibited potent antitumor activity. In this study, to improve the safety of ZD55, we utilized MUC1 promoter to replace the native promoter of E1A on the basis of ZD55, and generated a double-regulated adenovirus, named MUD55. Our data demonstrated that the expression of early and late genes of MUD55 was both reduced in MUC1-negative cells, resulting in its stricter glandular-tumor selective progeny production. The cytopathic effect of MUD55 was about 10-fold lower than mono-regulated adenovirus ZD55 or Ad.MUC1 in normal cells and not obviously attenuated in glandular tumor cells. Moreover, MUD55 showed the least liver toxicity when administrated by intravenous injection in nude mice. These results indicate that MUD55 could be a promising candidate for the treatment of adenocarcinoma.

Potent antitumor efficacy of ST13 for colorectal cancer mediated by oncolytic adenovirus via mitochondrial apoptotic cell death.

ST13 is a cofactor of heat shock protein 70 (Hsp70). To date, all data since the discovery of ST13 in 1993 until more recent studies in 2007 have proved that ST13 is downregulated in tumors and it was proposed to be a tumor suppressor gene, but no work reported its antitumor effect and apoptotic mechanism. In the work described in this paper, ST13 was inserted into ZD55, an oncolytic adenovirus with the E1B 55-kDa gene deleted, to form ZD55-ST13, which exerts an excellent antitumor effect in vitro and in an animal model of colorectal carcinoma SW620 xenograft. ZD55-ST13 inhibited tumor cells 100-fold more than Ad-ST13 and ZD55-EGFP in vitro. However, ZD55-ST13 showed no damage of normal fibroblast MRC5 cells. In exploring the mechanism of ZD55-ST13 in tumor cell killing, we found that ZD55-ST13-infected SW620 cells formed apoptotic bodies and presented obvious apoptosis phenomena. ZD55-ST13 induced the upregulation of Hsp70, the downregulation of antiapoptotic gene Bcl-2, and the release of cytochrome c. Cytochrome c triggered apoptosis by activating caspase-9 and caspase-3, which cleave the enzyme poly(ADP-ribose) polymerase in ZD55-ST13-infected SW620 cells. In summary, overexpressed ST13 as mediated by oncolytic adenovirus could exert potent antitumor activity via the intrinsic apoptotic pathway and has the potential to become a novel therapeutic for colorectal cancer gene therapy.

Significant antitumor activity of oncolytic adenovirus expressing human interferon-beta for hepatocellular carcinoma.

BACKGROUND: Human interferon-beta (IFN-beta) has been widely used in gene therapy for its antitumor activity but its therapeutic effect is limited. The conditionally replicative adenovirus ONYX-015 (a E1B-55-kDa-deleted adenovirus) targets well to tumor cells, but is not potent enough to cause significant tumor regression. To solve these problems, a tumor-selective replicating adenovirus expressing IFN-beta was constructed in this study. METHODS: The oncolytic adenoviruses were generated by homologous recombination in packaging cells. The expression of the IFN-beta protein was detected by enzyme-linked immunosorbent assay (ELISA). The antitumor efficacy of ZD55-IFN-beta was evaluated in cell lines and human hepatocellular carcinoma xenografts in nude mice. RESULTS: ZD55-IFN-beta can express much more IFN-beta than Ad-IFN-beta because of the replication of the ZD55 vector. Our data showed that ZD55-IFN-beta could exert a strong cytopathic effect on tumor cells (about 100-fold higher than Ad-IFN-beta or ONYX-015). Moreover, no obvious cytotoxic or apoptotic effects were detected in normal cells infected with ZD55-IFN-beta. CONCLUSIONS: The antitumor efficacy of IFN-beta could be significantly improved due to the increased gene expression level from the tumor-selective replicating vector. The oncolytic adenovirus expressing IFN-beta may provide a novel approach for cancer gene therapy.

Increased suppression of oncolytic adenovirus carrying mutant k5 on colorectal tumor.

Angiogenesis plays a key role in the development of a wide variety of malignant tumors. The approach of targeting antiangiogenesis has become an important field of cancer gene therapy. In this study, the antiangiogenesis protein K5 (the kringle 5 of human plasminogen) has been mutated by changing leucine71 to arginine to form mK5. Then the ZD55-mK5, which is an oncolytic adenovirus expressing mK5, was constructed. It showed stronger inhibition on proliferation of human umbilical vein endothelial cell. Moreover, in tube formation and embryonic chorioallantoic membrane assay, ZD55-mK5 exhibited more effective antiangiogenesis than ZD55-K5. In addition, ZD55-mK5 generated obvious suppression on the growth of colorectal tumor xenografts and prolonged the life span of nude mice. These results indicate that ZD55-mK5 is a potent agent for inhibiting the tumor angiogenesis and tumor growth.

Targeting gene-virotherapy of cancer.

Our purpose is to completely elimination of xenograft tumor in animal tumor model in order to work out a protocal for the cure of patient. Gene therapy and viral therapy for cancer have got some therapeutic effects, but both have no great breakthrough. Therefore, we worked out a new strategy called Targeting Gene-Virotherapy of Cancer which is a combination of the advantage of gene therapy and virotherapy. This new strategy has stronger antitumor effect than either of them alone. A tumor specific replicative adenovirus vector ZD55 (E1B 55KD deleted Adv.) which is similar to ONYX-015 in targeting fuction but significant different in construction was produced and various single therapeutic gene was inserted into ZD55. Now such a conception as Targeting Gene-Virotherapy of Cancer was raised and systemically studied before, although there are some works on ONYX-015-tk, -cd or cd/-tk etc. separately. The antitumor effect of ZD55-Gene (for example IL-24 gene) is much better than ZD55 (virotherapy) alone and hundred fold high than that of Ad-IL-24 (gene therapy) alone. ZD55-IL-24 was in preclinal studying in the ZD55-IL-24 therapy, completely elimination of tumor mass was occurred in some mice but not in all mice, that means one gene was not effictive enough to eliminate all the tumor mass in all mice. Therefore two genes with compensative or synergetic effect were inserted into ZD55 separately and used in combination. This strategy was called Targeting Dual Gene-Virotherapy of Cancer (with PCT patent). Then much better results were obtained and all the xenograft tumor masses were completely eliminated in all mice, if two suitable genes were chosen. On the basis of the initiation of two gene results, it was thought about that using two tumors promoter to control the virus vector will be better for the targeting effect and the safty of the drugs. Then double tumor controlled virus vector harboring two genes for cancer therapy was worked out. Better results have been obtained and another patent has been applied. This antitumor strategy could be used to kill all the tumor cells completely in all mice with minimum damage to normal cells.

Interleukin-2 gene has superior antinociceptive effects when delivered intrathecally.

The antinociceptive effect of interleukin-2 gene on rat carrageenan-induced pain was explored using different delivery methods. Intrathecal (i.t.) or plantar s.c. delivery of plasmid harbouring the interleukin-2 gene produced a marked antinociceptive effect, which was maintained up to 6 days; the administration of recombinant human interleukin-2 only had a transitory effect. The antinociceptive effect lasted longer and was more potent when the interleukin-2 gene was administered i.t. than when delivered s.c. The effect of the interleukin-2 gene was related to its protein expression, was dose dependent, and could be potentiated by liposome. The results suggest that the interleukin-2 gene has a good prospect for clinical use.

Strategy of Cancer Targeting Gene-Viro-Therapy (CTGVT) a trend in both cancer gene therapy and cancer virotherapy.

Cancer Targeting Gene-Viro-Therapy (CTGVT) and Gene Armed Oncolytic Virus Therapy (GAOVT) both are identical by inserting an antitumor gene into an oncolytic virus. This approach has gradually become a hot topic in cancer therapy, because that CTGVT (GAOVT) has much higher antitumor than that of either gene therapy alone or oncolytic virotherapy alone. We proposed the CTGVT strategy in 1999-2001, insisted it as a long term systematic approach to be examined over 10 years and have published 68 SCI papers some in good Journals. The CD gene armed oncolytic adenovirus therapy (GAOVT) for cancer treatment with potent antitumor effect was also named in our laboratory in 2003. Several modifications to CTGVT will be carried out by our group and will be introduced briefly in this paper. Most importantly, the modifications of CTGVT usually resulted in complete eradication of xenograft tumors in nude mice. In future best antitumor drugs may emerge from the modified CTGVT strategy and not from either gene therapy or virotherapy alone.

Double-regulated oncolytic adenovirus-mediated interleukin-24 overexpression exhibits potent antitumor activity on gastric adenocarcinoma.

Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24), identified by subtraction hybridization in the mid-1990s, is a potent gene therapeutic for cancer. Using a replication-deficient adenovirus as vector, it provokes apoptosis in diverse cancer cells without harming normal cells or tissues. To exploit the anticancer capability of IL-24 to the best, in this study, we generated a novel gene-virotherapy agent MUD55-IL-24, utilizing a replication-competent oncolytic adenovirus MUD55 as the gene delivery vector. It was documented that MUD55-IL-24 exhibited much stronger antitumor activity on gastric carcinoma both in vitro and in vivo, and its safety was comparable to the replication-deficient adenovirus Ad-IL-24. The unique properties of IL-24, including apoptosis induction, antiangiogenesis, and antimigration, were all significantly enhanced in MUD55-IL-24. After looking into the underlying mechanism, we found that intracellular ROS (Reactive Oxygen Species) generation may have caused the induction of apoptosis, mitochondrial dysfunction, and the activation of caspases in MUD55-IL-24-infected SG-7901 cells. Taken together, these results suggest that MUD55-IL-24 may be able to provide a potential strategy for future treatment of human gastric carcinoma.

VEGI-armed oncolytic adenovirus inhibits tumor neovascularization and directly induces mitochondria-mediated cancer cell apoptosis.

Vascular endothelial cell growth inhibitor (VEGI) is a member of the tumor necrosis factor superfamily and plays an important role in vascular homeostasis. In this study, to investigate the anticancer therapeutic potential of this gene, a secreted isoform of VEGI (VEGI-251) was inserted into a selectively replicating adenovirus with E1B 55 kDa gene deletion (ZD55) to construct ZD55-VEGI-251. We report here that secreted VEGI-251 produced from ZD55-VEGI-251-infected cancer cells potently inhibits endothelial cell proliferation, tube formation in vitro and angiogenesis of chick chorioallantoic membrane in vivo. Additionally, ZD55-VEGI-251 infection leads to a much more severe cytopathic effect than control viruses on several human cancer cell lines, including cervical cancer cell line HeLa, hepatoma cell line SMMC-7721 and colorectal cancer cell line SW620. Further study reveals that the increased cytotoxicity is a result of VEGI-251 autocrine-dependent, mitochondria-mediated apoptosis accompanied by caspase-9 activation, enhanced caspase-3 activation and PARP cleavage. Moreover, ZD55-VEGI-251-treatment of athymic nude mice bearing human cervical and colorectal tumor xenografts markedly suppressed tumor growth. Our findings indicate that the combined effect of antiangiogenesis and apoptosis-induction activity makes the VEGI-251-armed oncolytic adenovirus a promising therapeutic agent for cancer.

Suppression of cancer growth in mice by adeno-associated virus vector-mediated IFN-beta expression driven by hTERT promoter.

Adeno-associated virus (AAV) has rapidly become a promising gene delivery vehicle for its excellent advantages of non-immunogenic, low pathogenicity and long-term gene expression in vivo. However, a major obstacle in development of effective AAV vector is the lack of tissue specificity, which caused low efficiency of AAV transfer to target cells. The application of human telomerase reverse transcriptase (hTERT) promoter is a prior targeting strategy for AAV in cancer gene therapy as hTERT activity is transcriptionally upregulated in most cancer cells. In the present work, we investigated whether AAV-mediated human interferon beta (IFN-beta) gene driven by hTERT promoter could specifically express in tumor cells and suppress tumor cell growth. Our data demonstrated that hTERT promoter-driven IFN-beta expression was the tumor-specific, decreased the cell viability of tumor cells but not normal cells, and induced tumor cell apoptosis via activation of caspase pathway and release of cytochrome c. AAV-mediated IFN-beta expression driven by hTERT promoter significantly suppressed the growth of colorectal cancer and lung cancer xenograft in mice and resulted in tumor cells death in vivo. These data suggested that AAVs in combination with hTERT-mediated IFN-beta expression could exert potential antitumor activity and provide a novel targeting approach to clinical gene therapy of varieties of cancers.

Inhibition of renal cancer cell growth by oncolytic adenovirus armed short hairpin RNA targeting hTERT gene.

RNA interference (RNAi) has been proved to be a powerful tool for gene knockdown purpose and holds a great promise for the treatment of cancer. Our previous study demonstrated that the reduction of hTERT expression by means of chemically synthesized siRNAs and shRNAs expressed from plasmid resulted in proliferation inhibition in human renal carcinoma cells. In this study, we constructed a novel oncolytic adenovirus-based shRNA expression system, ZD55-hTERT, and to explore ZD55-hTERT-mediated RNAi for hTERT gene silencing. Our results showed that ZD55-hTERT could induce silencing of hTERT gene effectively, allow for efficient tumor-specific viral replication and induce the apoptosis of tumor cells effectively in vitro and in nude mice. We conclude that combining shRNA gene therapy and oncolytic virotherapy can enhance antitumor efficacy as a result of synergism between CRAd oncolysis and shRNA antitumor responses.

[Specific antitumor effect of adeno-associated virus vector carrying TRAIL gene under the control of hTERT promoter].

BACKGROUND & OBJECTIVE: Adeno-associated virus (AAV) has been widely used in tumor gene therapy. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a safe and potent anti-tumor gene which could induce apoptosis of many tumor cells. This study was to use tumor-specific promoter hTERT to construct AAV-hTERT-TRAIL, and explore its antitumor effect and mechanism in vitro. METHODS: Purified AAV-hTERT-TRAIL was obtained after co-transfection of HEK293 with pAAV-hTERT-TRAIL and two other help plasmids. After transfection of AAV-hTERT-TRAIL into three tumor cell lines, SW620, HepG2, A549 and two normal cell lines, NHLF and MRC5, the expression of TRAIL was detected by RT-PCR, Western blot and immunohistochemistry (IHC); the influence of AAV-hTERT-TRAIL transfection on cell proliferation was evaluated using MTT assay. Activation of caspase-3 and PARP was measured by Western blot. Cell apoptosis was assessed using ELISA and flow cytometry. RESULTS: AAV-hTERT-TRAIL was successfully packaged in HEK293 cells. After AAV-hTERT-TRAIL infection, specific expression of TRAIL was detected in three tumor cell lines, but not in two normal cell lines. Cell proliferation rates in SW620, A549, HepG2, NHLF and MRC5 cells were 41.55%, 44.29%, 49.95%, 84.59% and 87.22%, respectively after transfection of AAV-hTERT-TRAIL at a multiplicity of infection (MOI) of 100 for 96 h. AAV-hTERT-TRAIL activated caspase-3 apoptotic pathway and induced apoptosis in tumor cell lines, but not in normal cell lines. CONCLUSIONS: hTERT increases selectivity and safety of AAV vector. hTERT promoter controls the expression of anti-tumor genes to specifically induce death of tumor cells.