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Efficacy of targeted FasL in nasopharyngeal carcinoma
Jian-Hua Li1, Wei Shi, Marie Chia
1Ontario Cancer Institute, University of Toronto, Toronto, Ontario MS 1A1, Canada.
Abstract:
We have successfully achieved selective gene expression in human nasopharyngeal carcinoma (NPC) by exploiting the presence of the Epstein-Barr virus (EBV), utilizing a transcriptional targeting strategy (J. H. Li et al., 2002, Cancer Res. 62: 171). Building on this platform, we have generated a novel DeltaE1 adenoviral vector mediating the expression of a mutant noncleavable form of the FasL gene (HUGO-approved symbol TNFSF6) (ad5oriP.ncFasL). We observe that this therapy induces significant cytotoxicity in the EBV-positive NPC cell line C666-1, mediated by the induction of caspase-dependent apoptosis. The addition of ionizing radiation therapy (RT) causes additional cytotoxicity. Ex vivo infection of C666-1 cells with adv.oriP.ncFasL completely prevents tumor formation in SCID mice followed for up to 100 days. The combination of intratumoral adv.oriP.ncFasL with RT causes regression of established nasopharyngeal xenograft tumors for 2 weeks' duration. Systemic delivery of this targeted strategy achieves 50-fold higher gene expression in nasopharyngeal tumors than in normal organs. Intravenously injected adv.oriP.ncFasL results in mild perturbation of liver function that returns to normal 2 weeks after initial therapy. These results demonstrate the efficacy of our EBV-specific targeting strategy, which allows the potentially safe and effective utilization of a highly potent membrane-based apoptotic gene.
Insights
This study developed a targeted gene therapy for nasopharyngeal carcinoma (NPC) using an Epstein-Barr virus (EBV) vector to deliver a cancer-killing gene. The therapy effectively reduced tumors in mice and showed potential for safe, targeted cancer treatment.
Area of Science:
- Oncolytic virotherapy
- Gene therapy for cancer
- Molecular oncology
Background:
- Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC).
- Targeted gene delivery strategies can enhance cancer treatment efficacy.
- FasL (TNFSF6) is a pro-apoptotic gene with potential anti-cancer activity.
Purpose of the Study:
- To develop and evaluate a novel adenoviral vector for targeted gene expression in EBV-positive NPC.
- To assess the therapeutic efficacy of a mutant noncleavable FasL gene delivered by the vector, alone and in combination with radiation therapy (RT).
- To determine the safety and biodistribution of the targeted gene therapy in vivo.
Main Methods:
- Generation of a DeltaE1 adenoviral vector (ad5oriP.ncFasL) expressing a mutant noncleavable FasL.
- In vitro cytotoxicity assays on EBV-positive NPC cell line C666-1, assessing apoptosis induction.
- In vivo studies using SCID mice with C666-1 xenografts, evaluating tumor prevention and regression with ad5oriP.ncFasL and RT.
- Assessment of gene expression levels in tumors versus normal organs following systemic delivery.
- Monitoring of liver function after intravenous injection.
Main Results:
- The ad5oriP.ncFasL vector induced significant caspase-dependent apoptosis and cytotoxicity in C666-1 cells.
- Combination with ionizing radiation therapy (RT) enhanced cytotoxicity.
- Ex vivo infection completely prevented tumor formation in SCID mice.
- Intratumoral ad5oriP.ncFasL combined with RT led to regression of established xenograft tumors.
- Systemic delivery resulted in 50-fold higher gene expression in tumors compared to normal organs.
- Intravenous administration caused transient, mild liver function perturbation.
Conclusions:
- The EBV-specific transcriptional targeting strategy is effective for selective gene expression in NPC.
- The novel adenoviral vector expressing mutant noncleavable FasL demonstrates potent anti-cancer activity.
- The combination of targeted gene therapy with RT offers a promising approach for NPC treatment.
- This strategy allows for potentially safe and effective utilization of a potent apoptotic gene for cancer therapy.
