MicroRNAs modulation in lung cancer: exploring dual mechanisms and clinical prospects

The global incidence of lung cancer is marked by a considerably elevated mortality rate.MicroRNAs(miRNAs)exert pivotal influence in the intricate orchestration of gene regulation,and their dysregulation can precipitate dire consequences,notably cancer.Within this context,miRNAs encapsulated in exosomes manifest a diversified impact on the landscape of lung cancer,wherein their actions may either foster angiogenesis,cell proliferation,and metastasis,or counteract these processes.This comprehensive review article discerns potential targets for the prospective development of therapeutic agents tailored for lung cancer.Tumor-suppressive miRNAs,such as miR-204,miR-192,miR-30a,miR-34a,miR-34b,miR-203,and miR-212,exhibit heightened expression and demonstrate the capacity to inhibit cellular proliferation and invasiveness.Conversely,the deleterious effects of tumor-promoting miRNAs like miR-21,miR-106a,miR-155,miR-205,and miR-210 can be attenuated through the application of their respective inhibitors.Distinct miRNAs selectively target various oncogenes,including NUAK Family Kinase 1(NUAK1),Snail Family Transcriptional Repressor 1(Snai1),Astrocyte elevated gene-1(AEG-1),Vimentin,Proliferation and apoptosis adaptor protein 15(PEA-15/PED),Hypoxia-inducible factor 1-alpha(HIF1),as well as tumor suppressor genes such as phosphatase and tensin homolog(PTEN),Suppressor of cytokine signaling 1(SOCS1),Tumor protein P53 binding protein 1(TP53BP1),and PH Domain and Leucine Rich Repeat Protein Phosphatase 2(PHLP22).This investigative approach proves invaluable in elucidating the specific miRNAs implicated in the deregulation of crucial genes pivotal to the pathogenesis of cancer.

Engineered targeting tLyp-1 exosomes as gene therapy vectors for efficient delivery of siRNA into lung cancer cells

Natural exosomes can express specific proteins and carbohydratemolecules on the surface and hence have demonstrated the great potentials for gene therapy of cancer.However,the use of natural exosomes is restricted by their low transfection efficiency.Here,we report a novel targeting tLyp-1 exosome by gene recombinant engineering for delivery of siRNA to cancer and cancer stem cells.To reach such a purpose,the engineered tLyp-1-lamp2b plasmids were constructed and amplified in Escherichia coli.The tLyp-1-lamp2b plasmids were further used to transfect HEK293T tool cells and the targeting tLyp-1 exosomes were isolated from secretion of the transfected HEK293T cells.Afterwards,the artificially synthesized siRNA was encapsulated into targeting tLyp-1 exosomes by electroporation technology.Finally,the targeting siRNA tLyp-1 exosomes were used to transfect cancer or cancer stem cells.Results showed that the engineered targeting tLyp-1 exosomes had a nanosized structure(approximately 100 nm)and high transfection efficiency into lung cancer and cancer stem cells.The function verifications demonstrated that the targeting siRNA tLyp-1 exosomes were able to knock-down the target gene of cancer cells and to reduce the stemness of cancer stem cells.In conclusion,the targeting tLyp-1 exosomes are successfully engineered,and can be used for gene therapy with a high transfection efficiency.Therefore,the engineered targeting tLyp-1 exosomes offer a promising gene delivery platform for future cancer therapy.

PREPARATION OF GENE-VIRAL THERAPEUTIC SYSTEM CNHK200-HA AND ITS ANTITUMOR ACTIVITY ON LUNG CANCER

Objective： To develop a novel adenoviral vector system, which combines the advantages of the antiangiogenic gene therapy and virus therapy, and to investigate its antitumor activity on lung cancer. Methods： A new kind of viral vector CNHK200, in which the Elb55kDa gene was deleted and the whole Ela gene was preserved, was constructed. Human angiostatin gene Kringle 1-5 （hA） was amplified and inserted into the genome of the replicative virus CNHK200, generating CNHK200-hA. The expression of hA and its effect on lung cancer cell growth in vitro and in vivo were studied. Results： The novel vector system CNHK200-hA, just like the replicative virus ONYX-015, replicated in p53-deficient tumor cells but not in normal cells, and thus specifically killed tumor cells. In in vitro experiment, both CNHK200-hA and the non-replicative virus Ad-hA could kill tumor cells but the latter needed 100 times more MOI to achieve the same level of cell killing. In in vivo experiment, the therapeutic effect of CNHK200-hA on human lung cancer A549 xenografts in nude mice was significantly better than that of Ad-hA or that of ONYX-015. Conclusion： CNHK200-hA, which carries the angiostatin gene, has the advantages of specific tumor targeting, high expression of transgene in tumor cells and potent antitumor activity.

Dual-targeted lung cancer therapy via inhalation delivery of UCNP-siRNA-AS1411 nanocages

Objective:Although great progress has been made in the field of siRNA gene therapy,safe,efficient,and targeted delivery of siRNA are still major challenges in siRNA therapeutics.Methods:We developed an up-conversion nanoparticle-based nanocage system.This system protected the siRNA from being degraded by nucleases in organisms and selectively delivered the siRNAs to the tumor sites,due to modifications of targeted molecules on the surfaces of nanocages and local inhalation.Results:The siRNAs delivered by the up-conversion nanoparticle nanocages were protected from degradation in transit to the tumor sites,where they accumulated.Compared with the passive target and control groups,the up-conversion nanoparticles based on the nanocage system showed a tumor suppressive effect after approximately 3 weeks of treatment.Conclusions:The up-conversion nanoparticle nanocages efficiently delivered vascular endothelial growth factor siRNAs to tumor sites.Mice with lung tumors treated with tumors targeting up-conversion nanoparticle nanocages showed steady body weight changes,high tumor inhibition ratios,and longer survival times.

Anticancer actions of PPARγ ligands:Current state and future perspectives in human lung cancer

Peroxisome proliferator-activated receptors(PPARs) are ligand-dependent nuclear transcription factors and members of the nuclear receptor superfamily.Of the three PPARs identified to date(PPARγ,PPARβ/δ,and PPARα),PPARγ has been studied the most,in part because of the availability of PPARγagonists(also known as PPARγ ligands)and its significant effects on the management of several human diseases including type 2 diabetes,metabolic syndrome,cardiovascular disease and cancers.PPARγ is expressed in many tumors including lung cancer,and its function has been linked to the process of lung cancer development, progression and metastasis.Studies performed in gynogenic and xenograft models of lung cancer showed decreased tumor growth and metastasis in animals treated with PPARγ ligands.Furthermore,data are emerging from retrospective clinical studies that suggest a protective role for PPARγ ligands on the incidence of lung cancer.This review summarizes the research being conducted in this area and focuses on the mechanisms and potential therapeutic effects of PPARγ ligands as a novel anti-lung cancer treatment strategy.

Expression of Coxsackievirus and Adenovirus Receptor in Human Lung Cancer： Possible Clinical Significance

OBJECTIVE To explore the relationship between CAR and the development of human lung cancer, as well as to provide the basis for the clinical treatment of lung cancer using an adenovirus vector-based gene therapy. METHODS CAR expression was assessed immunohisto- chemically in tumoral, paraneoplastic and normal samples from 112 lung cancer patients. At the same time, the mRNA and protein expression of CAR in 32 cases were determined by RT-PCR and Western blot. The relationship between CAR expression and clinicopathologic parameters was statistically analyzed. RESULTS There was no expression of CAR in normal lung tissue but a little in paraneoplastic tissue. The positive rate was 43% in squamous cell carcinoma, and 70% in adenocarcinoma. Both were much significantly higher than that in paraneoplastic tissue. The CAR expression level in adenocarcinoma was higher than that in squamous cell cancer, mRNA expression by RT-PCR and protein expression by Western blot were consistent with immunohistochemistry results. CONCLUSION CAR is overexpressed in human lung cancer, especially in adenocarcinoma. This data offer the reliable basis for adenovirus-mediated gene therapy of lung cancer; more important, CAR may take part in the formation or development of lung cancer; this may be exploitable for the development of antibody-directed therapy in human lung cancer.

EGFR inhibitors sensitize non-small cell lung cancer cells to TRAIL-induced apoptosis

Apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand(TRAIL) can be regulated by the epidermal growth factor(EGF) signaling pathway.In this study,recombinant adenoviral vectors that encode TRAIL gene from the hTERT/RGD promoter(AdTRAIL) was combined with drugs including gefitinib,elotinib,and cetuximab that inhibit EGFR and the EGF signaling pathway in non-small cell lung cancer(NSCLC) cell lines to investigate their antitumor activity.In vitro,compared to single reagent,AdTRAIL combined with EGFR inhibitors reduced proliferation and enhanced apoptosis in H460,A549,and SW1573 cell lines.Western blot results suggested that these effects were relative to up-regulation of pro-apoptosis protein BAX and down-regulation of p-AKT.In vivo,AdTRAIL combined with cetuximab resulted in a significant growth reduction in H460 xenografts without damage to the main organs of nude mice.Histological examination and TUNEL analyses of xenografts showed that cetuximab enhanced cell apoptosis induced by AdTRAIL.These results indicate that EGFR inhibitors enhanced AdTRAIL anti-tumor activity in NSCLC cell lines and that inhibiting the AKT pathway played an important role in this enhancement.

A non-viral gene therapy for melanoma by staphylococcal enterotoxin A

Staphylococcal enterotoxin A(SEA)derived from Staphylococcus aureus,as a superantigen,shows potential for cancer immunotherapy,but systemic immunotoxicity restricts its clinical application.Targeted delivery of SEA to tumor site provides a promising option for reducing the systemic toxicity.Here,we constructed an iRGD peptide(H-[Cys-Arg-Gly-Asp-Lys-Gly-Pro-Asp-Cys]-NH_(2))modified nanoparticle(iDPP)to deliver plasmids encoding SEA for melanoma treatment.The iDPP/SEA nanocomplexes efficiently mediated SEA expression in B16-F10 cells in vivo and in vitro and induced the activation of lymphocytes and maturation of murine bone marrow-derived dendritic cells(BMDCs)in vitro.In the subcutaneous B16-F10 melanoma model,the iDPP/SEA nanocomplexes could effectively enhance immune response and T lymphocytes infiltration in tumor site after intravenous administration,thereby considerably decreased melanoma growth.Meanwhile,no obvious adverse effect was observed after intravenous administration of the iDPP/SEA nanocomplexes in vivo.Our findings demonstrated that gene therapy of SEA is a potential candidate for melanoma treatment.

Expression of coxsackie and adenovirus receptor in small cell lung cancer

Objective: We explored the expression of coxsackie and adenovirus receptor (CAR) in small cell lung cancer (SCLC) tissue. Methods: CAR expression in 31 SCLC was assessed in formaldehyde-fixed, paraffin-embedded tissue according to the EnVision immunohistochemistry procedure, while 3 samples of surgical specimens of non-malignant lung disease were taken as the negative control. Results: We observed that the expression of CAR was detectable positive in all the 31 cases from the small cell lung cancer tissue, in contrasting that non-malignant lung tissue control. Conclusion: The high expression of CAR appeared in SCLC tissue indicates that it play an important role in of adenovirus vector-based gene therapy in SCLC.

Expression of Coxsackie and Adenovirurus Receptor and its Significance in Human Lung Cancer

OBJECTIVE To study the relationship between the coxsackie and adenovirus receptor （CAR） and the development of human lung cancer. To optimize adenovirus vector-based gene therapy.METHODS The expression of CAR in 112 cases of lung cancer was examined using immunohistochemistry. At the same time, the relationship between CAR expression and clinicopathologic characteristics was analyzed,RESULTS ：lhere is a little expression of CAR in normal lung tissue. Compared with paraneoplastic epithelial tissue of the lung, the expression of CAR is generally up-regulated in tumor tissues showing a significant dif- ference （P〈0.01）. The positive rate of CAR expression in squamous cell carcinoma was 43.1%, and in adenocarcinoma 70.2%, with the difference between the two rates being statistically significant （P〈0.01）. Compared to the paraneoplastic tissues, the difference in CAR positive expression was 35.4% for squamous cell carcinoma and 38.3% for adenocarcinoma. But the difference in different stages of squamous cell carcinoma had no statistical significance （P〉0.05）. However, the expression of CAR was at a high level in the bronchioalveolar carcinomas as 80.4% were CAR positive. This research showed that there was a specially high expression of CAR in adenocarcinomas.CONCLUSION CAR is expressed in human lungs at a low level and up-regulated in the tumor tissues, suggesting that there is a relationship between adenocarcinoma and CAR. This research provides a basis for planning a regimen of gene therapy using an adenovirus vector,

非小细胞肺癌第三代ALK抑制剂洛拉替尼的耐药机制及其相关研究进展

间变淋巴瘤激酶(anaplastic lymphoma kinase,ALK)融合基因是非小细胞肺癌(non-small cell lung cancer,NSCLC)患者除表皮生长因子受体(epidermal growth factor receptor,EGFR)基因之外最常见的驱动基因。ALK融合基因阳性的NSCLC患者能从ALK酪氨酸激酶抑制剂(tyrosine kinase inhibitors,TKIs)靶向治疗中明显获益,但是患者最终会发生TKI耐药。探索ALK靶向治疗的耐药机制一直是研究重点。关于第一代和第二代ALK TKIs的耐药机制已有较多报道,第三代ALK TKI洛拉替尼的耐药机制亟待阐述。本文将主要从依赖ALK基因(即on-target resistance)和非依赖ALK基因(即off-target resistance)两方面阐述第三代ALK TKI洛拉替尼的耐药机制,重点总结了经序贯洛拉替尼治疗发生复合突变后对其他TKIs的敏感性以及旁路活化途径,一线洛拉替尼治疗潜在的耐药机制以及第四代ALK TKIs的研究进展,洛拉替尼治疗中液体活检动态监测的意义。

基于RNA-based NGS检测非小细胞肺癌融合基因临床实践中国专家共识

基于RNA水平的二代测序(RNA-based next-generation sequencing, RNA-based NGS)技术已被非小细胞肺癌(non-small cell lung cancer, NSCLC)临床实践指南和专家共识推荐为融合基因的检测方法之一。NSCLC可用药靶点主要包括基因突变和融合,用于评估靶向治疗可行性的基因突变和融合基因检测均不可或缺。目前,基于DNA水平的NGS(DNA-based NGS)结合RNA-based NGS一次性同步检测基因突变和融合的技术已部分应用于临床实践。然而,RNA-based NGS检测融合基因的应用时机、应用场景和质控方面在我国仍缺乏规范和标准。本共识将进一步明确RNA-based NGS在融合基因检测中的应用时机、应用场景和质控,并给予指导性建议,推动RNA-based NGS在NSCLC临床诊疗中的应用,使患者能够最大程度地从融合基因检测中获益。

Annual progress of clinical research on targeted therapy for nonsmall cell lung cancer in 2022

With the rapid development of lung cancer molecular detection and precisiontherapy, targeted therapy has covered the entire process of diagnosis andtreatment of nonsmall cell lung cancer patients. Overall mortality from lungcancer has decreased significantly over the past 20 years, especially since theintroduction of targeted drugs in 2013. In 2022, targeted therapy for lungcancer has developed rapidly. The optimization of treatment modes and theexploration of new target drugs such as antibody‐drug conjugates will broadenthe selection range of nonsmall cell lung cancer patients with positive drivergenes. This article reviews the latest advances in targeted therapy for drivergene‐positive lung cancer in 2022.

Folate-conjugated polyspermine for lung cancer–targeted gene therapy

Biodegradable polyamines have long been studied as potential recombinant viral gene vectors.Spermine(SPE) is an endogenous tetra-amine with excellent biocompatibility yet poor gene condensation capacity. We have previously synthesized a polyspermine based on SPE and poly(ethylene glycol)(PEG)diacrylate(SPE-alt-PEG) for enhanced transfection performance, but the synthesized SPE-alt-PEG still lacked specificity towards cancer cells. In this study, folic acid(FA) was incorporated into SPE-alt-PEG to fabricate a targeted gene delivery vector(FA-SPE-PEG) via an acylation reaction. FA-SPE-PEG exhibited mild cytotoxicity in both cancer cells and normal cells. FA-SPE-PEG possessed higher transfection efficiency than PEI 25 K and Lipofectamines2000 in two tested cancer cell lines at functional weight ratios, and its superiority over untargeted SPE-alt-PEG was prominent in cells with overexpressed folate receptors(FRs). Moreover, in vivo delivery of green fluorescent protein(GFP) with FA-SPE-PEG resulted in highest fluorescent signal intensity of all investigated groups. FA-SPE-PEG showed remarkably enhanced specificity towards cancer cells both in vivo and in vitro due to the interaction between FA and FRs. Taken together, FA-SPE-PEG was demonstrated to be a prospective targeted gene delivery vector with high transfection capacity and excellent biocompatibility.

Pre-irradiation with low-dose ^(12)C^(6+) beam significantly enhances the efficacy of AdCMV-p53 gene therapy in human non-small lung cancer

The combination of ionizing radiation and gene therapy has been investigated. However, there are very few reports about the combination of heavy-ion irradiation and gene therapy. To determine if the pre-exposure to low-dose heavy ion beam enhances the suppression of AdCMV-p53 on non-small lung cancer (NSLC), the cells pre-irradiated or non-irradiated were infected with 20, 40 MOI of AdCMV-p53. Survival fraction and the relative biology effect (RBE) were determined by clonogenic assay. The results showed that the proportions of p53 positive cells in 12C6+ beam induced AdCMV-p53 infected cells were more than 90%, which were signifi-cantly more than those in γ-ray induced AdCMV-p53 infected cells. The pre-exposure to low-dose 12C6+ beam significantly prevented the G0/G1 arrest and activated G2/M checkpoints. The pre-exposure to 12C6+ beam significantly improved cell to apoptosis. RBEs for the 12C6+ + AdCMV-p53 infection groups were 30%-60%, 20%-130% and 30%-70% more than those for the 12C6+-irradiated only, AdCMV-p53 infected only, and γ-irradiation induced AdCMVp53 infected groups, respectively. The data suggested that the pre-exposure to low-dose 12C6+ beam significantly promotes exogenous p53 expression in NSLC, and the suppression of AdCMV-p53 gene therapy on NSLC.

RNAi沉默VEGF的表达及其治疗肺癌的初步研究

目的:以RNAi干涉的方法沉默VEGF在肺癌细胞中的表达,为肺癌的RNAi基因治疗提供实验依据。方法:以VEGF为靶点,利用siRNA设计原则,设计VEGF-siRNA,构建pSilencerTM-3.1-VEGF的干涉载体,稳定转染入肺癌细胞株A549中,检测VEGF在细胞中的表达及稳定转染pSilen-cerTM-3.1-VEGF肺癌细胞系A549对内皮细胞血管形成的影响,体内观察pSilencerTM-3.1-VEGF肺癌细胞荷瘤小鼠的肿瘤生长情况。结果:pSilencerTM-3.1-VEGF-2明显抑制了肺癌细胞系A549中VEGF的表达,稳定转染pSilencerTM-3.1-VEGF-2的肺癌细胞株A549体外生长没有发生变化,但是其对内皮细胞的血管生成有明显的抑制作用,体内荷瘤小鼠结果显示,与肺癌细胞株A549荷瘤小鼠比较,pSilencerTM-3.1-VEGF-2-A549荷瘤小鼠中肿瘤的生长明显缓慢(P<0.05),生存期明显延长(P<0.05)。结论:我们成功构建了pSilen-cerTM-3.1-VEGF的干涉载体,稳定转染pSilencerTM-3.1-VEGF的肺癌细胞株A549中能够明显抑制VEGF的表达,抑制内皮细胞小管形成,延长了荷瘤小鼠的生存期。

ODC,AdoMetDC双反义腺病毒对肺癌增殖和侵袭抑制作用的体外和体内研究(英文)

鸟氨酸脱羧酶(ODC)和S-甲硫氨酸脱羧酶(AdoMetDC)是多胺体内合成的2个关键酶.研究腺病毒Ad-ODC-AdoMetDCas介导的ODC和AdoMetDC反义RNA对肺癌多胺合成,细胞增殖以及侵袭的抑制作用.用活细胞计数和流式细胞术分别检测Ad-ODCas和Ad-ODC-AdoMetDCas对肺癌A-549细胞增殖的影响,蛋白质印迹和HPLC方法分别检测腺病毒对肺癌A-549细胞中ODC和AdoMetDC蛋白表达以及胞内多胺含量的抑制作用,TUNEL标记检测法观察Ad-ODC-AdoMetDCas对肺癌细胞凋亡的影响,Matrigel侵袭实验分析腺病毒对肺癌A-549细胞侵袭活性的改变,裸鼠皮下移植瘤模型研究Ad-ODC-AdoMetDCas对体内肺癌生长的抑制作用.实验结果显示,Ad-ODC-AdoMetDCas明显抑制肺癌A-549细胞的增殖,导致细胞凋亡,显著降低肺癌A-549细胞的体外侵袭能力,肺癌A-549细胞感染Ad-ODC-AdoMetDCas后细胞内3种多胺含量都明显降低,Ad-ODC-AdoMetDCas对已形成的裸鼠皮下移植瘤具有明显的抑制作用.实验表明,ODC和AdoMetDC双反义腺病毒具有显著抑制肺癌增殖和侵袭的作用,对于肺癌的防治研究具有一定的前景.

MACC1基因siRNA对肺癌SBC-5细胞增殖和迁移的影响

目的:探讨MACC1(metastasis-associated in colon cancer l)基因特异性siRNA(small interfering RNA)对肺癌细胞系SBC-5体外增殖和迁移的影响。方法:化学合成MACC1基因特异性siRNA,阳离子脂质体LipofectamineTM 2000转染肺癌细胞系SBC-5细胞,RT-PCR和Western blot方法检测转染后SBC-5细胞中MACC1基因和蛋白的表达情况;MTT法检测细胞的生长增殖状况;划痕试验观察细胞迁移能力的改变。结果:MACC1基因特异性siRNA转染细胞后,SBC-5细胞MACC1的mRNA和蛋白表达水平明显降低,MTT试验和划痕试验观察到转染MACC1-siRNA的SBC-5细胞增殖、迁移能力明显减弱。结论:MACC1基因特异性siRNA可以明显抑制肺癌SBC-5细胞增殖和迁移,MACC1可能成为肺癌治疗的新靶点。

pVAX-WIF-1真核表达载体的构建及其抗肺癌作用

背景与目的 WIF-1是肺癌中重要的抑癌基因之一,其编码蛋白WIF-1能够通过抑制Wnt/β-catenin信号通路达到抑制肿瘤生长增殖及促进凋亡等抗肺癌作用。本研究旨在利用美国食品和药品管理委员会认可用于临床治疗的p VAX载体,构建p VAX-WIF-1真核表达载体,初步探究p VAX-WIF-1在体内外对A549肺癌细胞的抗肿瘤作用。方法应用PCR方法扩增人WIF-1编码序列片段,构建p VAX-WIF-1载体后转染肺癌A549细胞,Western blot检测WIF-1基因的表达;采用MTT法、Hoechst3235染色和流式细胞术分别检测p VAX-WIF-1在体外对肺癌A549细胞增殖、凋亡作用的影响;构建A549小鼠皮下瘤模型,探究p VAX-WIF-1在体内的抗肺癌作用。结果真核表达质粒载体p VAX-WIF-1构建成功,p VAX-WIF-1转染A549细胞后,WIF-1蛋白表达升高。p VAX-WIF-1转染A549后能抑制细胞增殖和诱导凋亡。动物体内结果表明,p VAX-WIF-1能有效抑制肺癌肿瘤生长。结论本研究成功构建了p VAX-WIF-1真核表达质粒,p VAX-WIF-1能明显抑制A549肺癌细胞增殖和促进凋亡,有效抑制A549皮下瘤生长。本研究将为WIF-1基因的肺癌临床治疗奠定了基础。

乏氧照射双敏感启动子HRE.CArG调控HSVtk基因对肺癌细胞的杀伤效应

目的观察乏氧照射后HRE.CArG融合性启动子诱导增强的绿色荧光蛋白(EGFP)在SPCA1和A549肺癌细胞株中的表达变化及乏氧照射诱导下该启动子驱动自杀基因HSVtk对肺癌细胞的杀伤作用。方法用聚乙烯亚胺转染法转染SPCA1和A549细胞,乏氧照射后24 h测EGFP表达强度;乏氧照射后24 h加入GCV,48 h后用MTT法测定细胞存活率。结果乏氧照射后转染pDNA.HRE.CArG.EGFP质粒的SPCA1和A549细胞EGFP表达强度分别是对照组的(3.37±0.23)倍和(3.10±0.28)倍(P<0.01);转染pDNA.HRE.CArG.HSVtk质粒的SPCA1和A549细胞存活率较对照组分别降低(63.23±2.31)%和(76.58±2.19)%(P<0.01)。结论质粒载体中包含的HRE.CArG元件对乏氧照射敏感,乏氧照射后通过诱导下游的HSVtk基因大量表达,使转染细胞对GCV的敏感性增高,而大大增加对SPCA1和A549细胞的杀伤效应。