腺相关病毒携带hTERT启动子调控的TRAIL基因特异性杀伤肿瘤细胞

背景与目的:腺相关病毒(adeno-associated virus)作为载体已被广泛用于肿瘤的基因治疗研究.肿瘤坏死因子相关凋亡诱导配体(tumor necrosis factorrelated apoptosis.inducing ligand,TRAIL)基因可迅速诱导多种肿瘤细胞的凋亡.是一个安全有效的肿瘤杀伤基因.本研究旨在构建能在肿瘤细胞内特异性表达TRAIL基因的靶向腺相关病毒,并探讨其体外抗肿瘤效应的可能机制.方法:利用肿瘤特异性启动子端粒酶逆转录酶(human telomerase reverse transcfiptase,hTERT)构建特异性杀伤肿瘤细胞的腺相关病毒载体pAAV-hTERT-TRAIL.通过与pAAV-Rc、pHelper共转染HEK293细胞包装出病毒AAV-hTERT-TRAIL.将该病毒体外转染人结肠癌SW620细胞、人肝癌HepG2细胞、人肺癌A549细胞和正常细胞NHLF、MRC5后,检测TRAIL基因的肿瘤特异性表达.MTT法检测其对细胞增殖的影响,ELISA、Western blot法以及流式细胞仪检测细胞的凋亡,并分析其体外抗肿瘤效应的可能机制.结果:成功包装出病毒AAVhTERT-TRAIL.RT-PCR、Western blot和免疫组化法均证实AAV-hTERT-TRAIL能介导TRAIL基因在肿瘤细胞内特异性表达,但在正常细胞内不表达.以100 MOI AAV-IlTERTTRAIL感染细胞96 h后,SW620、A549和HepG2细胞的增殖率分别是41.55%、44.29%、49.95%,NHLF和MRC5细胞的增殖率分别是84.59%和87.22%.Western blot检测发现AAV-hTERT-TRAIL可激活Caspase通路.流式细胞仪和ELISA方法检测证实AAV-hTERT-TRAIL可诱导细胞凋亡.结论:hTERT的存在增强了腺相关病毒所携带TRAIL基因表达的肿瘤靶向性和对正常细胞的安全性.由它调控的杀伤基因可介导肿瘤细胞特异性的细胞毒效应.     

结肠癌TRAIL耐药细胞株的建立及其耐药机制的初步研究

背景与目的以人结肠癌DLD1细胞株为载体,探讨恶性肿瘤获得性TRAIL基因耐药的可能机制。材料与方法用重组腺病毒介导的TRAIL基因(Ad/gTRAIL)反复处理人结肠癌DLD1细胞,得到耐药细胞群DLD1-TRAIL/R。通过MTT比色法和蛋白电泳,检测耐药细胞对Ad/gTRAIL杀伤作用的敏感性及其凋亡通路中信号分子的表达情况,分析其获得性耐药的可能机制。结果DLD1-TRAIL/R细胞对Ad/gTRAIL和重组TRAIL蛋白处理耐药,但对腺病毒介导的Bax基因处理仍然敏感。耐药细胞内Bcl-XL的表达明显升高,caspase-8的表达显著下降,未见明显的caspase-8活性裂解形式。结论人结肠癌DLD1细胞株经Ad/gTRAIL反复处理后产生特异性针对TRAIL基因的耐药,其发生机制可能与Bcl-XL表达上调和caspase-8表达下调有关。     

Ad.TERT-TRAIL对肿瘤细胞的杀伤作用及其机理

背景与目的：有学者用人端粒酶逆转录酶(TERT)启动子替换野生型腺病毒E1A自身的启动子,构建了一种肿瘤特异性增殖病毒,即溶瘤腺病毒Ad．TERT。细胞实验和动物实验表明,Ad．TERT有很好的抗癌作用。本研究目的是要在Ad．TERT中插入凋亡基因trail生成Ad．TERT—TRAIL,观察其是否具有更强的杀伤肿瘤细胞的功效并研究其机理。方法：通过腺病毒包装质粒pBHGE3与携带trail的小质粒pZhTERT—trail在HEK293细胞中同源重组构建Ad．TERT-TRAIL病毒．然后用PCR鉴定。并用Western blot检测E1A、trail基因的表达以进一步确证。用结晶紫染色法和MTT法检测Ad．TERT和Ad．TERT—TRAIL对肿瘤细胞和正常细胞杀伤作用的差异。用Western blot检测Caspase-3表达量以观察肿瘤细胞的凋亡情况,同时用流式细胞仪测定肿瘤细胞的凋亡率。结果：PCR扩增出来的条带为860bp．即为trail基因。Western blot结果显示．Ad．TERT—TRAIL中的E1A和trail只在肿瘤细胞中表达,说明Ad．TERT—TRAIL构建成功。结晶紫染色结果表明,Ad．TERT-TRAIL对肿瘤细胞的杀伤力比Ad．TERT高10～100倍．而对正常细胞的影响跟Ad．TERT一样小。100MOI(multiple of infection)Ad．TERT—TRAIL感染结肠癌细胞SW620 72h后．细胞存活率为4％：而感染了Ad．TERT的SW620细胞存活率却达56％。两种病毒对正常细胞NHLF的影响都比较弱,存活率在85％以上。随着作用时间的延长．感染了Ad．TERT—TRAIL和Ad．TERT的SW620细胞中Caspase-3的表达量都在升高,但前者的表达量明显大于后者．说明前者所引起的肿瘤细胞的凋亡程度比后者高。流式细胞仪检测结果显示,Ad．TERT—TRAIL引起SW620细胞的凋亡率是Ad．TFRT的4倍。结论：携带基因的溶瘤腺病毒Ad．TERT—TRAIL比单纯的溶瘤病毒Ad．TERT对肿瘤细胞的杀伤力更强,这种作用可能与trail基因能诱导Caspase-3表达量增加、大量肿瘤细胞凋亡有关。     

Gene transfer to cervical cancer with fiber-modified adenoviruses

Successful adenoviral (Ad) vector-mediated strategies for cancer gene therapy mandate gene-delivery systems that are capable of achieving efficient gene delivery in vivo. In many cancer types, in vivo gene-transfer efficiency remains limited due to the low or highly variable expression of the primary Ad receptor, the coxsackie Ad receptor (CAR). In this study, we evaluated the expression of CAR on cervical cancer cells as well as CAR-independent targeting strategies to integrins (Ad5.RGD), heparan sulfate proteoglycans (Ad5.pK7) or both (Ad5.RGD.pK7). We used a panel of established cervical cancer cell lines and primary cervical cancer cells isolated from patients to quantify the expression of CAR mRNA and to evaluate the gene-transfer efficiency of fiber-modified Ads. Of the fiber-modified vectors, Ad5.pK7 and Ad5.RGD.pK7 displayed significantly enhanced gene-transfer efficiency in vitro. Gene-delivery efficiency in vivo was evaluated using an s.c. cervical cancer mouse model. Ad5.RGD.pK7 significantly improves tumor targeting in vivo, resulting in a significantly improved tumor/liver ratio in mice. Our results suggest that the double-modified Ad5.RGD.pk7 vector enhances gene transfer to clinically relevant cervical cancer substrates, while the infectivity of nontarget cells in the mouse is not increased and comparable to Ad5. The fiber-modified virus described here can help achieve higher clinical efficacy of cervical cancer gene therapy.     

肿瘤坏死因子相关凋亡诱导配体基因对人大肠癌细胞株HT29作用的研究

目的 探讨肿瘤坏死因子（TNF）相关的凋亡诱导配体基因（TRAIL）用于人大肠癌细胞株HT29基因治疗的实验研究。方法 将重组腺病毒载体（Ad)介导的TRAIL基因作用于人大肠癌细胞株HT29,通过相差显微镜、MTT比色法和流式细胞仪,研究分析其对HT29细胞作用的效果。结果 Ad/GT-TRAIL能引起HT29细胞出现明显的形态学改变,对HT29细胞的生长抑制率和凋亡诱导率分别为54．3％和11．1％;联合Ad/PGK-GV16后,生长抑制率和凋亡诱导率均显著提高（P＜0．05）,分别为82．7％和24．6％。结论 Ad/GT-TRAIL能有效诱导HT29的凋亡从而抑制HT29的生长,联合Ad/PGK-GV16后将显著提高其疗效。     

A capsid-modified, conditionally replicating oncolytic adenovirus vector expressing TRAIL Leads to enhanced cancer cell killing in human glioblastoma models

Glioblastoma multiforme (GBM) is the most aggressive brain tumor, and patients rarely survive for more than 2 years. Gene therapy may offer new treatment options and improve the prognosis for patients with GBM. Adenovirus-mediated gene therapy strategies for brain tumors have been limited by inefficient gene transfer due to low expression of the adenovirus serotype 5 (Ad5) receptor. We have used an adenovirus vector that specifically replicates in tumor cells and uses an Ad5 capsid and the adenovirus serotype (Ad35) fiber for efficient infection of malignant tumor cells. This vector also expresses adenovirus E1A and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a tumor-specific manner. Here, we show that this oncolytic vector (Ad5/Ad35.IR-E1A/TRAIL) efficiently infects the GBM tumor cell lines SF767, T98G, and U-87 MG. Tumor cell killing was markedly enhanced with Ad5/Ad35.IR-E1A/TRAIL compared with wild-type Ad5 and Ad35 virus or Ad5/Ad35.IR-E1A- vectors without TRAIL expression in vitro. In vivo experiments using s.c. xenografted U-87 MG cells in NOD/SCID mice showed a significant growth delay of tumors after i.t. injection of Ad5/Ad35.IR-E1A/TRAIL, whereas adenovirus wild-type injections showed only marginal or no effect. Our findings indicate that the use of a capsid-modified adenoviral vector, in combination with TRAIL expression, is a promising novel approach for gene therapy of glioblastoma.     

TRAIL基因修饰联合阿霉素对大肠癌细胞株RKO作用的研究

目的:探讨肿瘤坏死因子(tumor necrsis factor,TNF)相关的凋亡诱导配体(TNF-related apoptosis-inducing ligand,TRAIL)基因联合阿霉索后,应用于人大肠癌细胞株RKO基因治疗的实验研究.方法:将重组腺病毒载体(Ad)介导的TRAIL基因作用于大肠癌细胞株RKO,并联合低剂量的阿霉素协同作用.通过MTF比色法与流式细胞仪研究分析其对RKO细胞的作用效果,并以RT-PCR检测联合应用阿霉素前后TRAIL基因的表达水平.结果:病毒载体对RKO细胞的生长有轻微的抑制作用,作用4 d抑制率为11.9%,但不增加RKO细胞的凋亡率.TRAIL对RKO细胞的生长抑制率及凋亡诱导率分别为50.1%和19.8%.联合阿霉素后,TRAIL对RKO细胞株的生长抑制率及凋亡率均有显著的增强作用,分别达60.3%及49.0%.RT-PCR结果提示联合应用阿霉素后,TRAIL基因的表达并未增强.结论:TRAIL能有效抑制RKO的生长,联合阿霉素后,其对RKO的生长抑制作用及凋亡诱导作用均明显增强.阿霉素不是通过增加TRAIL基因的表达来实现上述作用的.     

Gene transfer to carcinoma of the breast with fiber-modified adenoviral vectors in a tissue slice model system

Successful adenoviral (Ad) vector-mediated strategies for breast cancer gene therapy and virotherapy have heretofore been hindered by low transduction efficiency. This has recently been understood to result from a relative paucity of expression of the primary adenovirus receptor, coxsackie-adenovirus-receptor (CAR), on primary tumor cells. To further investigate this issue, we evaluated the expression of CAR on breast cancer cell lines as well as primary breast cancer cells. With the exception of one patient sample, CAR expression was notably higher in the tumor cells from patients compared to CAR expression in the tumor cell lines. Furthermore, we explored CAR-independent targeting strategies to breast cancer tissue by exploring a panel of infectivity-enhanced Ad vectors, which contain CAR-independent targeting motifs for their utility in breast cancer gene therapy and virotherapy. These targeting motifs included Ad 3 knob (Ad5/3), canine Ad serotype 2 knob (Ad5CAV-2), RGD (Ad5.RGD), polylysine (Ad5.pK7), or both RGD and polylysine (Ad5.RGD.pK7), and were tested using the breast cancer tissue slice model, which is the most stringent substrate system available. Of all the tested tropism modified Ad vectors, Ad5/3 exhibited the highest transductional efficiency in breast cancer. These preclinical results suggest that Ad5/3 is the most useful modification to achieve higher clinical efficacy of breast cancer gene therapy and virotherapy.     

Sulforaphane sensitizes tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis through downregulation of ERK and Akt in lung adenocarcinoma A549 cells

The cytotoxic effect of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is limited in some cancer cells, including A549 lung adenocarcinoma cells. However, treatment with TRAIL in combination with subtoxic concentrations of sulforaphane (SFN) sensitizes TRAIL-resistant A549 cells to TRAIL-mediated apoptosis. Combined treatment with SFN and TRAIL induced chromatin condensation, DNA fragmentation, annexin V staining and sub-G(1) phase DNA content. These indicators of apoptosis correlate with the induction of caspase-3 activity that results in the cleavage of poly(ADP-ribose) polymerase and the release of lactate dehydrogenase. Both the cytotoxic effect and apoptotic characteristics induced by combined treatment were significantly inhibited by z-DEVD-fmk, a caspase-3 inhibitor, demonstrating the important role of caspase-3 in the observed cytotoxic effect. Combined treatment also triggered the activation of p38 MAPK and JNK, and downregulation of ERK and Akt. Inhibitors of ERK (PD98059) or Akt (LY294002), but not p38 MAPK, resulted in significantly decreased cell viability. Although the activation of JNK was increased in response to combined treatment, inhibition of the JNK pathway significantly attenuated cell viability. These results indicate that caspase-3 is a key regulator of apoptosis in response to combined SFN and TRAIL in human lung adenocarcinoma A549 cells through downregulation of ERK and Akt.     

Growth suppression of esophageal squamous cell carcinoma induced by heavy carbon-ion beams combined with p53 gene transfer

Heavy carbon-ion beam therapy has revealed several potential advantages over X-rays. Heavy-ion therapy has been applied for various solid tumors including esophageal squamous cell carcinoma (SCC). Although the local control rate in carbon ion radiotherapy for esophageal cancer has revealed better rates than conventional radiotherapy, severe mucosal damage was observed in adjacent normal mucosa. A suitable treatment strategy is required to reduce irradiation dose by introducing combined local therapy. Recently, we initiated clinical p53 gene therapy for esophageal SCC. We herein evaluate the cytotoxic effects of heavy carbon-ion beams combined with p53 gene transfer on human esophageal SCC. We assessed the induction of apoptosis and growth suppression with the use of recombinant adenoviral vector Ad.p53 or heavy carbon-ion beam irradiation or both. Growth suppression was significantly potentiated by combined treatment with heavy carbon-ion beams and Ad.p53 as compared to that treated with either of them alone. Western blot analysis confirmed the expression of both exogenous p53 and p21 proteins after irradiation of Ad.p53 infected cells. Enhanced apoptotic cell death was observed with a terminal deoxynucleotidyl transferase-mediated nick end-labeling assay. These data suggest that heavy carbon-ion beam irradiation combined with Ad.p53 may be a potentially effective therapeutic strategy for locally advanced esophageal SCC.     

Tumor Necrosis Factor α-Gene Therapy for an Established Murine Melanoma Using RGB (Arg-Gly-Asp) Fiber-mutant Adenovirus Vectors

Although adenovirus vectors (Ad) provide high-level transduction efficacy to many cell types, extremely high doses of Ad are required for sufficient gene transduction into several tumors, including melanoma. Here, we demonstrated that the expression of coxsackie-adenovirus receptor, a primitive Ad-receptor, was very low in murine and human melanoma cells. We also found that fiber-mutant Ad containing the Arg-Gly-Asp (RGD) sequence in the fiber knob remarkably augmented gene transduction efficacy in melanoma cells by targeting α_v-integrins. In addition, intratumoral injection of RGD fiber-mutant Ad containing the tumor necrosis factor α gene (AdRGD-TNFα) revealed dramatic anti-tumor efficacy through hemolytic necrosis in an established murine B16 BL6 melanoma model. Ad-RGD-TNFα required one-tenth the dosage of Ad-TNFα to induce an equal therapeutic effect. These results suggest that α_v-integrin-targeted Ad will be a very powerful tool for the advancement of melanoma gene therapy.     

Potent antitumor effect elicited by RGD-mda-7, an mda-7/IL-24 mutant, via targeting the integrin receptor of tumor cells

The melanoma differentiation-associated gene-7/interleukin-24 gene (mda-7/IL-24) is a novel tumor-suppressor/cytokine gene that exhibits potent tumor-suppressive activity without damaging normal cells. To enhance the antitumor effect, an mda-7/IL-24 mutant, RGD-mda-7, which includes the cell adhesive sequence 164Arg-165Gly-166Asp (RGD motif), was constructed and evaluated for bioactivity. RGD peptide binds to integrins α(V)β(3) and α(V)β(5), which are selectively expressed in tumor neovasculature and in the surface of some tumor cells. The wtmda-7/IL-24 and RGD-mda-7 were expressed in Escherichia coli and then purified and renatured. The immunostimulatory activity of RGD-mda-7 was assayed by stimulating peripheral blood mononuclear cells. The results suggested that the abilities of RGD-mda-7 to induce IL-6, TNF-α, and IFN-γ production were higher than wtmda-7/IL-24. Tumor targeting of RGD-mda-7 was assayed using cell adhesion experiments. The antitumor effect of the purified RGD-mda-7 on cell proliferation in vitro was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) uptake, cell apoptosis by staining with fluorescent probes of FITC-annexin V and DAPI, and caspase-3 expression and activity. The in vitro results showed that RGD-mda-7 inhibited the proliferation of multiple tumor cell lines (Hela, ACHN, HepG2, and A549). Staining with fluorescent probes of FITC-annexin V and DAPI indicated that RGD-mda-7 could induce apoptosis more effectively in four tumor cell lines than wtmda-7/IL-24, but has no effect on normal cell line NHLF. Western blotting showed that treatment of tumor cells with RGD-mda-7 could activate apoptotic pathway by cleavage of caspase-3 as same as wtmda-7/IL-24. Further, RGD-mda-7 group showed a higher cleaved level of caspase-3, but not in NHLF cells. These results demonstrate that RGD-MDA-7 possesses more potent antitumor effects than wtmda-7/IL-24 and therefore merits further investigation in preclinical and clinical studies.     

Gene-viro-therapy targeting liver cancer by a dual-regulated oncolytic adenoviral vector harboring IL-24 and TRAIL

Cancer-targeting gene-viro-therapy is a promising cancer therapeutic strategy that strengthens the antitumor effect of oncolytic viruses by expressing an inserted foreign antitumor gene. To achieve liver cancer targeting and to improve the safety of the ZD55 vector (a widely-used E1B55KD gene-deleted oncolytic adenoviral vector (OV), we previously constructed), we designed a novel OV named Ad·AFP·D55 that selectively replicates in hepatocellular carcinoma (HCC) cells by replacing the E1A promoter with the liver-cancer specific α-Fetoprotein (AFP) promoter based on the ZD55 vector. We found that the oncolytic adenoviruses Ad·AFP·D55-IL-24 and Ad·AFP·D55-TRAIL express tumor-suppressor gene interleukin-24 (IL-24) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), respectively, significantly suppressed the HCC cell growth in vitro by inducing apoptosis by the caspase-8 and mitochondria-dependent caspase-9 signaling pathways. Furthermore, the combined treatment of Ad·AFP·D55-IL-24 and Ad·AFP·D55-TRAIL showed strong antitumor effects in vivo by significantly inhibiting the tumor growth in HCC HuH-7 cell xenograft mice, and markedly increasing animal survival rate. Therefore, this novel HCC cell-targeting OV carrying tumor-suppressor genes may provide a promising approach for liver cancer gene therapy.     

Molecular requirements for the combined effects of TRAIL and ionising radiation.

BACKGROUND AND PURPOSE: Previously it was shown that combination of death ligand TRAIL and irradiation strongly increases cell kill in several human tumour cell lines. Since Bcl-2 overexpression did not strongly interfere with the efficacy, components of the mitochondrial death pathway are not required for an effective combined treatment. In the present study the minimal molecular prerequisites for the efficacy of a combined treatment were determined. MATERIALS AND METHODS: Apoptosis induction in control, caspase-8 and FADD negative Jurkat cells, BJAB control and FADD-DN cells was analysed by FACS. Activation of caspase-8, -10 and -3 and cleavage of PARP was determined by immunoblotting. TRAIL receptors were activated using recombinant human TRAIL. Surface expression of TRAIL receptors DR4 and DR5 was analysed by FACS. RESULTS: Jurkat T-cells express the agonistic DR5 receptor but not DR4. Presence of FADD was found to be essential for TRAIL induced apoptosis. Caspase-8 negative cells show very low rates of apoptosis after prolonged stimulation with TRAIL. No combined effects of TRAIL with irradiation could be found in FADD-DN overexpressing and FADD deficient cells. However, the combination of TRAIL and irradiation clearly lead to a combined effect in caspase-8 negative Jurkat cells, albeit with reduced death rates. In these cells activation of the alternative initiator caspase-10 could be detected after combined treatment. CONCLUSION: Our data show that a combined therapy with TRAIL and irradiation will only be effective in cells expressing at least one agonistic TRAIL receptor, FADD and caspase-8 or caspase-10.