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Published on: May 6, 2015
Androgen receptor attenuation of Ad5 replication: implications for the development of conditionally replication
Naseruddin Höti1, Ying Li, Chien-Lun Chen
1James Buchanan Brady Urology Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-2101, USA.
Abstract:
Conditionally replication competent adenoviruses (CRAds) represent one of the most intensely studied gene therapy strategies for a variety of malignancies, including prostate cancer. These viruses can be generated by placing a tissue or cancer-specific promoter upstream of one or more of the viral genes required for replication (e.g., E1A, E1B). We report here that E1A inhibits androgen receptor (AR) target gene induction and, correspondingly, activated AR inhibits adenoviral replication. This mutual inhibition appears to be an indirect effect, possibly through competition for shared transcriptional co-activators. The net effect is that the oncolytic effect of prostate-specific CRAds is attenuated by these interactions. Fusion of the E1A to AR ameliorates this inhibition, while enhancing specificity. These findings have significant implications in the development of prostate-specific CRAd therapies.
Insights
Prostate cancer gene therapy using conditionally replication competent adenoviruses (CRAds) is hindered by mutual inhibition between viral E1A and androgen receptor (AR). Fusing E1A to AR enhances specificity and efficacy of these oncolytic viruses.
Area of Science:
- Oncolytic virotherapy
- Gene therapy for prostate cancer
- Adenovirus vector engineering
Background:
- Conditionally replication competent adenoviruses (CRAds) are investigated for cancer gene therapy, particularly for prostate cancer.
- CRAds are engineered with tissue-specific promoters to target cancer cells.
- Prostate cancer treatment often involves targeting the androgen receptor (AR) pathway.
Purpose of the Study:
- To investigate the interaction between adenoviral E1A and the androgen receptor (AR) in prostate cancer.
- To understand how this interaction affects CRAd replication and oncolytic efficacy.
- To explore strategies for improving prostate-specific CRAd therapy.
Main Methods:
- Generation of prostate-specific CRAds.
- Analysis of the effect of E1A on AR target gene induction.
- Assessment of AR's impact on adenoviral replication.
- Engineering of E1A-AR fusion proteins.
Main Results:
- Adenoviral E1A inhibits androgen receptor (AR) target gene induction.
- Activated AR inhibits adenoviral replication, likely via indirect mechanisms like co-activator competition.
- This mutual inhibition attenuates the oncolytic effect of prostate-specific CRAds.
- Fusion of E1A to AR reduces inhibition and enhances specificity.
Conclusions:
- The interaction between E1A and AR presents a challenge for prostate-specific CRAd therapy.
- Engineering strategies, such as E1A-AR fusion, can overcome this limitation.
- These findings are crucial for developing more effective CRAd-based prostate cancer treatments.
