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.

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.

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.

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.

The folate cycle enzyme MTHFD2 induces cancer immune evasion through PD-L1 up-regulation.

Metabolic enzymes and metabolites display non-metabolic functions in immune cell signalling that modulate immune attack ability. However, whether and how a tumour's metabolic remodelling contributes to its immune resistance remain to be clarified. Here we perform a functional screen of metabolic genes that rescue tumour cells from effector T cell cytotoxicity, and identify the embryo- and tumour-specific folate cycle enzyme methylenetetrahydrofolate dehydrogenase 2 (MTHFD2). Mechanistically, MTHFD2 promotes basal and IFN-γ-stimulated PD-L1 expression, which is necessary for tumourigenesis in vivo. Moreover, IFN-γ stimulates MTHFD2 through the AKT-mTORC1 pathway. Meanwhile, MTHFD2 drives the folate cycle to sustain sufficient uridine-related metabolites including UDP-GlcNAc, which promotes the global O-GlcNAcylation of proteins including cMYC, resulting in increased cMYC stability and PD-L1 transcription. Consistently, the O-GlcNAcylation level positively correlates with MTHFD2 and PD-L1 in pancreatic cancer patients. These findings uncover a non-metabolic role for MTHFD2 in cell signalling and cancer biology.

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.

Trail armed oncolytic poxvirus suppresses lung cancer cell by inducing apoptosis.

Lung cancer has a high morbidity rate worldwide and is often resistant to therapy. Oncolytic virus therapy is a developing trend for cancer treatment. Thus, we constructed an oncolytic poxvirus carrying human trail gene that expresses a membrane-binding tumor necrosis factor and associated apoptosis-inducing ligand (TRAIL, Oncopox-trail). We hypothesized that the expression of trail would increase the efficacy of the oncolytic poxvirus. The effect of the TRAIL protein depends on the death receptors on the surface of different cancer cells. The expression of death receptors in lung cancer cell lines was analyzed by western blot analysis. In vitro, the oncolytic poxvirus carrying the trail gene displayed a better cytotoxicity at the cell level in the lung cancer cell line than that carrying the Oncopox-empty. TRAIL protein mainly induced apoptosis and inhibited necrosis. In vivo, two transplanted tumor models of human A549 lung cancer cells and mouse Lewis lung cancer cells were used to verify the anti-cancer effect of the oncolytic poxvirus carrying the trail gene. TUNEL staining results of the tumor histological sections also verified the anti-cancer effect. Similarly, through systemic administration of Oncopox-trail, the oncolytic poxvirus also exhibited anti-cancer effect.

A dual yet opposite growth-regulating function of miR-204 and its target XRN1 in prostate adenocarcinoma cells and neuroendocrine-like prostate cancer cells.

Androgen deprivation therapy in prostate cancer (PCa) causes neuroendocrine differentiation (NED) of prostatic adenocarcinomas (PAC) cells, leading to recurrence of PCa. Androgen-responsive genes involved in PCa progression including NED remain largely unknown. Here we demonstrated the importance of androgen receptor (AR)-microRNA-204 (miR-204)-XRN1 axis in PCa cell lines and the rat ventral prostate. Androgens downregulate miR-204, resulting in induction of XRN1 (5'-3' exoribonuclease 1), which we identified as a miR-204 target. miR-204 acts as a tumor suppressor in two PAC cell lines (LNCaP and 22Rv1) and as an oncomiR in two neuroendocrine-like prostate cancer (NEPC) cell lines (PC-3 and CL1). Importantly, overexpression of miR-204 and knockdown of XRN1 inhibited AR expression in PCa cells. Repression of miR-34a, a known AR-targeting miRNA, contributes AR expression by XRN1. Thus we revealed the AR-miR-204-XRN1-miR-34a positive feedback loop and a dual function of miR-204/XRN1 axis in prostate cancer.

SMAC-armed vaccinia virus induces both apoptosis and necroptosis and synergizes the efficiency of vinblastine in HCC.

Hepatocellular carcinoma (HCC) has particularly high incidence rate in Asia and its resistance to the chemotherapeutic drugs and cell death make it intractable. Vaccinia virus (VV) is a potential vehicle and has been widely used in cancer therapy. SMAC/DIABLO is a critical factor in activating caspases and eliminating inhibition of IAPs when the programmed cell death is promoted. In this study, we constructed a tumor-targeted vaccinia virus carrying SMAC/DIABLO gene that was knocked in the region of viral thymidine kinase gene (VV-SMAC). Our results showed that VV-SMAC efficiently infected and destroyed HCC cells via triggering both caspase-dependent apoptosis and necroptosis with depletion of IAPs. Furthermore, ripoptosome, a prerequisite complex of necroptosis, was assembled and induced by VV-SMAC. In addition, the combination of VV-SMAC and vinblastine represented a synergistic effect on HCC cells. In summary, our data suggest that VV-SMAC is a potential candidate and combination of VV-SMAC and vinblastine may provide a new avenue in treatment of HCC.

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.

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.

ASK1-JNK signaling cascade mediates Ad-ST13-induced apoptosis in colorectal HCT116 cells.

ST13, a co-factor of heat shock protein, has shown potential antitumor efficacy for colorectal cancer in our previous study. However, the molecular mechanisms governing ST13-induced apoptosis are poorly understood. Here, we demonstrate that Ad-ST13 (ST13 mediated by adenovirus) activates apoptosis signal-regulated kinase (ASK1) and c-Jun N-terminal kinase (JNK) but not p38 (mitogen-activated protein kinase) in human colorectal HCT116 cells. Ad-ST13 also increases extracellular-regulated kinase (ERK) phosphorylation levels, but the change is due to adenovirus replication. Overexpression of ST13 also increases the transcription activity of AP-1. Blocking ASK1-JNK pathway affects Ad-ST13-mediated colorectal cell apoptosis, decreases the release of cytochrome c in cytoplasm and caspase activation. Because ASK1 is known to contain a tetratricopeptide repeat (TPR)-acceptor site and ST13 has TPR domain, we found the interaction between ST13 and ASK1. These results strongly indicate Ad-ST13 triggers colorectal cell apoptosis via ASK1-JNK signaling cascade.

Reexpression of human somatostatin receptor gene 2 gene mediated by oncolytic adenovirus increases antitumor activity of tumor necrosis factor-related apoptosis-inducing ligand against pancreatic cancer.

PURPOSE: Pancreatic cancer continues to pose an enormous challenge to clinicians and cancer scientists. Clinical studies show that tumor necrosis factor-related apoptosis- inducing ligand (TRAIL) exerts a potent and tumor-specific proapoptotic activity. However, most pancreatic cancer cells are resistant to TRAIL therapy. Human somatostatin receptor gene 2 (hSSTr2) is lost in 90% of pancreatic carcinoma. Oncolytic viruses are able to selectively lyse cancer cells and represent a promising novel anticancer therapy. Here, we investigated whether oncolytic adenovirus-mediated reexpression of hSSTr2 would enhance TRAIL-induced antitumor efficacy against pancreatic cancer. EXPERIMENTAL DESIGN: The antitumor efficacies of combined or single treatment of hSSTr2 and TRAIL mediated by oncolytic adenovirus were compared in pancreatic cancer cell culture and xenografts. The mechanisms involved in hSSTr2-induced sensitization to TRAIL were studied. RESULTS: Oncolytic adenovirus-mediated reexpression of hSSTr2 potentiated TRAIL-induced tumor growth inhibition in vitro and in vivo. Reexpression of hSSTr2 augmented TRAIL-induced apoptosis against pancreatic cancer cells via up-regulation of death receptor 4 and down-regulation of Bcl-2. CONCLUSIONS: hSSTr2 restoration mediated by oncolytic adenovirus enhances TRAIL-induced antitumor efficacy against pancreatic cancer. Combined treatment with oncolytic adenovirus-mediated hSSTr2 and TRAIL gene provides the rationale for a clinical trial in pancreatic cancer.

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.

Potent anti-hepatoma efficacy of HCCS1 via dual tumor-targeting gene-virotherapy strategy.

We previously demonstrated that hepatocellular carcinoma suppressor 1 (HCCS1) exerts potent anti-tumor activity. In this study, we constructed a new dual tumor-targeting oncolytic adenovirus vector, PD55-HCCS1, in which E1A was driven by the promoter of progression elevated gene-3, which is hepatoma-specific, and a CMV-HCCS1 expression cassette replaced E1B55. The PD55-HCCS1-mediated selective expression of E1A and HCCS1 in hepatoma cells and tumor-selective cytotoxicity in vitro and in vivo demonstrated the strongest inhibition of BEL-7404 cell xenografts in nude mice among a number of control Ad vectors. These data indicated the efficacy and safety of the PD55-HCCS1 system for HCC treatment.

Suppression of colorectal tumor growth by regulated survivin targeting.

A major goal in cancer gene therapy is to develop efficient gene transfer protocols that allow tissue-specific and tightly regulated expression of therapeutic genes. The ideal vector should efficiently transduce cancer cells with minimal toxicity on normal tissues and persistently express foreign genes. One of the most promising regulatory systems is the mifepristone/RU486-regulated system, which has much lower basal transcriptional activity and high inducibility. In this work, we modified this system by incorporating a cancer-specific promoter, the human telomerase reverse transcriptase (hTERT) promoter. By utilizing hTERT promoter to control the regulator, RU486 could specifically induce the expression of foreign genes in cancer cells but not in normal cells. In the context of this system, a dominant negative mutant of survivin (surDN) was controllably expressed in colorectal tumor cells. The surDN expression induced by RU486 showed a dosage- and time-dependent pattern. Regulated expression of surDN caused caspase-dependent apoptosis in colorectal tumor cells but had little effect on normal cells. Analysis of cell viability showed that RU486-induced expression of surDN suppressed colorectal tumor cell growth and had synergic effect in combination with chemotherapeutic agents. The potential of this system in cancer therapy was evaluated in experimental animals. Tumor xenograft models were established in nude mice with colorectal tumor cells, and RU486 was intraperitoneally administered. The results showed that conditional expression of surDN efficiently inhibited tumor growth in vivo and prolonged the life of tumor-burdened mice. Synergized with the chemotherapeutic drug cisplatin, regulated surDN expression completely suppressed tumor growth. These results indicated that this modified RU486-regulated system could be useful in cancer-targeting therapy.

[A mini-review of targeting gene-virotherapy of cancer].

New progress has been made on the project "targeting gene-virotherapy of cancer" proposed by us, which is "targeting dual gene-virotherapy of cancer". By the use of two genes, all the xenograft tumors in nude mice could be completely eliminated. The researches have been published in international journals, such as Hepatology and Cancer Research (a highlight paper). In this study, a further superior strategy--"double targeting virus-dual gene therapy" was introduced. This strategy was specialized by the use of tumor specific promoter to control the tumor specific suppressor gene, such as alpha-fetoprotein (AFP), which controls hepatoma specific suppressor gene LFIRE or HCCS1. In addition, a second tumor specific promoter, such as hTERT or survivin was used to control E1A or E1B in the construct, as hTERT-E1A-AFP-E1B-HCCS1 or LFIRE, a double tumor specific promoter controlling hepatoma specific LFIRE or HCCS1 gene. By the combined use of this construct with a very strong antitumor construct, such as hTERT-E1A-AFP-E1B-IL-24, a strategy with both excellent tumor killing effect and excellent safety with very little damage to normal cells was obtained. Therefore, double targeting virus-dual gene therapy might be one of the most potential strategies for cancer treatment. Furthermore, a new type of interferon was also introduced, which might be an ideal antitumor drug.

A survivin-mediated oncolytic adenovirus induces non-apoptotic cell death in lung cancer cells and shows antitumoral potential in vivo.

BACKGROUND: Conditionally replicating adenoviruses or oncolytic adenoviruses, which can replicate selectively in tumor cells and kill them, represent an innovative class of promising cancer therapeutics. Survivin is the smallest member of the inhibitor of apoptosis (IAP) family, which is transcriptionally upregulated exclusively in most malignant tissues but not in normal tissues. It has been reported that activity of the survivin promoter is tumor-specific, which makes the survivin promoter a good candidate to construct oncolytic viral vectors. METHODS: A luciferase reporter assay was used to determine the activity of the survivin promoter in tumor and normal cells. An oncolytic adenovirus (Ad.SP/E1A) was generated by homologous recombination. The oncolytic efficacy of Ad.SP/E1A was evaluated in cell lines and in a human lung xenograft tumor mouse model. RESULTS: Survivin expression was highly upregulated in tumor cells both at the protein and mRNA level. The luciferase reporter assay showed that survivin promoter activity is tumor-specific. Ad.SP/E1A expressed E1A selectively in tumor cells and induced cytotoxicity, but not in normal cells. Moreover, in animal experiments, intratumoral administration of Ad.SP/E1A significantly suppressed the growth of xenograft tumors. Further investigation showed that Ad.SP/E1A induced cell death by an apoptosis-independent pathway. CONCLUSIONS: Ad.SP/E1A could be a potent therapeutic agent for cancer gene therapy. The investigation of the mechanisms of oncolytic virus-induced cell death in this work will shed light on the construction of more powerful vectors for cancer therapy.