Chadderton N, Cowen RL, Sheppard FCD, Robinson S, Greco O, Scott SD, Stratford IJ, Patterson AV, Williams KJ. Dual responsive promoters to target therapeutic gene expression to radiation-resistant hypoxic tumor cells.
Int J Radiat Oncol Biol Phys 2005;
62:213-22. [PMID:
15850924 DOI:
10.1016/j.ijrobp.2005.01.031]
[Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Revised: 11/19/2004] [Accepted: 01/11/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE
Tumor hypoxia is unequivocally linked to poor radiotherapy outcome. This study aimed to identify enhancer sequences that respond maximally to a combination of radiation and hypoxia for use in genetic radiotherapy approaches.
METHODS AND MATERIALS
The influence of radiation (5 Gy) and hypoxia (1% O2) on reporter-gene expression driven by hypoxia (HRE) and radiation (Egr-1) responsive elements was evaluated in tumor cells grown as monolayers or multicellular spheroids. Hypoxia-inducible factor-1alpha (HIF-1alpha) and HIF-2alpha protein expression was monitored in parallel.
RESULTS
Of the sequences tested, an HRE from the phosphoglycerate kinase-1 gene (PGK-18[5+]) was maximally induced in response to hypoxia plus radiation in all 5 cell lines tested. The additional radiation treatment afforded a significant increase in the induction of PGK-18[5+] compared with hypoxia alone in 3 cell lines. HIF-1alpha/2alpha were induced by radiation but combined hypoxia/radiation treatment did not yield a further increase. The dual responsive nature of HREs was maintained when spheroids were irradiated after delivery of HRE constructs in a replication-deficient adenovirus.
CONCLUSIONS
Hypoxia-responsive enhancer element sequences are dually responsive to combined radiation and hypoxic treatment. Their use in genetic radiotherapy in vivo could maximize expression in the most radio-resistant population at the time of radiation and also exploit microenvironmental changes after radiotherapy to yield additional switch-on.
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