Telomerase inhibition by stable RNA interference impairs tumor growth and angiogenesis in glioblastoma xenografts

Pallini, Roberto; Sorrentino, Antonio; Pierconti, Francesco; Maggiano, Nicola; Faggi, Riccardo; Montano, Nicola; Maira, Giulio; Larocca, Luigi Maria; Levi, Andrea; Falchetti, Maria Laura

doi:10.1002/ijc.21613

Cited by 37 publications

(36 citation statements)

References 46 publications

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“…HEK293 was obtained from Microbix promotes cancer growth through mechanisms which are independent of telomere maintenance by producing growth factors or healing DNA damage. 16,17 Recently Li 18 and Pallini et al, 19 independently reported that telomerase inhibition by RNA interference targeting hTERT rapidly led to cell growth impairment both in vitro and in a mouse xenograft tumor model in several telomerase-positive human cancer cell lines. This effect was noted at early passages when no bulk telomere shortening had occurred.…”

Section: Methodsmentioning

confidence: 99%

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

Zheng¹,

Pei²,

Sun³

et al. 2009

Cancer Biology & Therapy

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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.

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Section: Methodsmentioning

confidence: 99%

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

Zheng¹,

Pei²,

Sun³

et al. 2009

Cancer Biology & Therapy

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“…14 We established a 5-mm TERT-NIS system to provide TERT-specific radionuclide therapy and to demonstrate the possibilities of molecular imaging and radioiodine gene therapy. 10 Though we observed that tumor growth was reduced after TERT-targeted I-131 therapy, tumor growth was still continued despite of initial tumor growth retardation after I-131 therapy. Thus, a new approach was required to enhance therapeutic effect of TERT-specific I-131 therapy.…”

Section: Discussionmentioning

confidence: 72%

“…3 We tried to inhibit telomerase activity after radionuclide gene therapy, because previously we found that radionuclide gene therapy had an inadequate effect on tumor growth. 10 One recent study found that hTERT promoter activity was increased in radiation-resistant laryngeal squamous cell carcinoma, and examined the effects of suicidal gene (hTERTp-HRP/IAA) therapy using hTERT promoter plus radiotherapy and they showed efficient tumor specific cytotoxicity of prodrug IAA in radiation-resistant human squamous cell carcinoma. 16 From immunofluorescence staining of xenografted tumor tissue, we could also find that the level of TERT expression was elevated in the I-131 tumor.…”

Section: Discussionmentioning

confidence: 99%

“…10 Cells were harvested, washed and resuspended in 200 ml of 1 Â CHAP lysis buffer provided in the kit. Lysates were then aliquoted into microcentrifuge tubes and stored at À80 1C until required.…”

Section: Western Blotmentioning

confidence: 99%

“…8 Interestingly, efficient telomerase inhibition using this system also has been reported. 9,10 In the present study, we engineered a retrovirus carrying TERT-specific shRNA (siTERT) to induce the stable inhibition of telomerase. We utilized a combination of hNIS-based I-131 therapy using the TERT promoter-NIS system to allow tumor-specific delivery of radionuclide and retrovirus carrying siTERT to inhibit hTERT expression, monitoring the synergistic effect of radiotherapy with siTERT in vitro and in vivo.…”

Section: Introductionmentioning

confidence: 99%

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Complementary treatment of siTERT for improving the antitumor effect of TERT-specific I-131 therapy

et al. 2012

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Sodium iodide symporter (NIS)-based radionuclide therapy provides an effective means of treating malignant tumors. However, it is sometimes inadequate because of limited effects on radio-resistant tumors, and thus, combination therapies with other therapeutic options have been requested to enhance its efficacy. Human telomerase reverse transcriptase (hTERT) has been reported to be involved in the progression of most cancers and also been viewed as a good candidate for targeting tumor. Application of TERTspecific radionuclide therapies using NIS gene transfer have been reported to treat TERT-positive tumors, but this approach only demonstrated tumor regression rather than eradication. As inhibiting TERT expression by introducing the hTERT-specific shRNA (siTERT) has been suggested as a therapeutic option, we investigated the complementary role of siTERT treatment after the TERTspecific I-131 therapy and its possibility as a novel anticancer therapeutic strategy. Retroviruses containing TERT promoter/NIS for TERT specific Radionuclide therapy and siTERT for TERT targeting antisense therapy were produced. Hep3B cells expressing TERT specific NIS (Hep3B-TERT/NIS) were xenografted into nude mouse and visualized with micro-SPECT/CT for monitoring NIS activity. The levels of hTERT mRNA, protein and its activity were confirmed by RT-PCR, Western blotting and Telomerase repeat amplification protocol assay. Cell proliferation was monitored by MTT assay and induced apoptosis was confirmed by Annexin-V-PI staining. Therapeutic effects of I-131 and/or siTERT were evaluated by clonogenic assay and mouse tumor model. Reduction of hTERT mRNA, protein and TERT activity by siTERT were observed in Hep3B-TERT/NIS cells. The viabilities of the infected cells were significantly decreased to 50% versus siScramble treated controls. The early apoptotic cell population was increased by siTERT. The survival rates of cells treated with siTERT or I-131 alone were 72.4 ± 7.6% and 56.2 ± 5.2%, respectively. However, the survival rate of cells treated with I-131 and siTERT were decreased to 22.1 ± 2.8%. From mouse xenograft model, we also found that the siTERT gene therapy showed synergism to the radioiodine therapy for reducing tumor growth in vivo. Our Results suggested that complementary siTERT gene therapy offers a novel strategy of cancer therapy to improve the therapeutic efficacy of TERT-specific I-131.

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Inhibition of telomerase in the endothelial cells disrupts tumor angiogenesis in glioblastoma xenografts

Falchetti

Mongiardi

Fiorenzo

et al. 2007

Intl Journal of Cancer

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Tumor angiogenesis is a complex process that involves a series of interactions between tumor cells and endothelial cells (ECs).In vitro, glioblastoma multiforme (GBM) cells are known to induce an increase in proliferation, migration and tube formation by the ECs. We have previously shown that in human GBM specimens the proliferating ECs of the tumor vasculature express the catalytic component of telomerase, hTERT, and that telomerase can be upregulated in human ECs by exposing these cells to GBM in vitro. Here, we developed a controlled in vivo assay of tumor angiogenesis in which primary human umbilical vascular endothelial cells (HUVECs) were subcutaneously grafted with or without human GBM cells in immunocompromised mice as Matrigel implants. We found that primary HUVECs did not survive in Matrigel implants, and that telomerase upregulation had little effect on HUVEC survival. In the presence of GBM cells, however, the grafted HUVECs not only survived in Matrigel implants but developed tubule structures that integrated with murine microvessels. Telomerase upregulation in HUVECs enhanced such effect. More importantly, inhibition of telomerase in HUVECs completely abolished tubule formation and greatly reduced survival of these cells in the tumor xenografts. Our data demonstrate that telomerase upregulation by the ECs is a key requisite for GBM tumor angiogenesis. ' 2007 Wiley-Liss, Inc.Key words: HUVEC; glioblastoma multiforme; telomerase; tumor xenograft Glioblastoma multiforme (GBM) is the most aggressive brain cancer. In this tumor, angiogenesis is so prominent to represent a landmark for histological diagnosis.1 Human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, is expressed by endothelial cells (ECs) of the tumor vasculature with increasing incidence and relative quantity during the progression of astrocytic tumors toward malignancy. We first observed telomerase involvement in the angiogenesis of astrocytic tumors on human tissue sections.2 Expression of hTERT by vascular ECs is a phenomenon strictly related to tumor environment, since it is absent in the ECs of nonneoplastic granulation tissues as well as in normal brain.2 Moreover expression of hTERT is induced in ECs at an early stage of tumor progression and it is positively correlated with the histological grade of the tumor. Using in vitro models, we demonstrated that GBM is able to activate hTERT transcription as well as telomerase activity in human umbilical vascular endothelial cells (HUVECs) and that such effects are likely mediated by diffusible factor/s.3 Taken together, our data suggest that telomerase reactivation might improve the replicative potential of ECs, and that this phenomenon might be induced by the tumor itself. Telomerase expressing ECs are supposed to exhibit survival advantages, i.e. resisting the apoptotic cell death triggered by replication under the cell stressing conditions of the tumor environment. 4 Here, we inhibited telomerase activity in human ECs, either by RNA interference (RNAi) tar...

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Telomerase inhibition by stable RNA interference impairs tumor growth and angiogenesis in glioblastoma xenografts

Cited by 37 publications

References 46 publications

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

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

Complementary treatment of siTERT for improving the antitumor effect of TERT-specific I-131 therapy

Inhibition of telomerase in the endothelial cells disrupts tumor angiogenesis in glioblastoma xenografts

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