Insulated hsp70B' promoter: stringent heat-inducible activity in replication-deficient, but not replication-competent adenoviruses.
BACKGROUND
Key to the realization of gene therapy is the development of efficient and targeted gene transfer vectors. Therapeutic gene transfer by replication-deficient or more recently by conditionally replication-competent/oncolytic adenoviruses has shown much promise. For specific applications, however, it will be advantageous to provide vectors that allow for external control of gene expression. The efficient cellular heat shock system in combination with available technology for focused and controlled hyperthermia suggests heat-regulated transcription control as a promising tool for this purpose.


RESULTS
We investigated the feasibility of a short fragment of the human hsp70B' promoter, with and without upstream insulator elements, for the regulation of transgene expression by replication-deficient or oncolytic adenoviruses. Two novel adenoviral vectors with an insulated hsp70B' promoter were developed and showed stringent heat-inducible gene expression with induction ratios up to 8000-fold. In contrast, regulation of gene expression from the hsp70B' promoter without insulation was suboptimal. In replication-competent/oncolytic adenoviruses regulation of the hsp70B' promoter was lost specifically during late replication in permissive cells and could not be restored by the insulators.


CONCLUSIONS
We developed novel adenovirus gene transfer vectors that feature improved and stringent regulation of transgene expression from the hsp70B' promoter using promoter insulation. These vectors have potential for gene therapy applications that benefit from external modulation of therapeutic gene expression or for combination therapy with hyperthermia. Furthermore, our study reveals that vector replication can deregulate inserted cellular promoters, an observation which is of relevance for the development of replication-competent/oncolytic gene transfer vectors.
Rohmer
Stanimira
S
Department of Dermatology, University Hospital Erlangen, Hartmannstr. 14, Erlangen, Germany.
Mainka
Astrid
A
Knippertz
Ilka
I
Hesse
Andrea
A
Nettelbeck
Dirk M
DM
D000256:Adenoviridae / Q000235:genetics / Q000502:physiology*; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D006358:Hot Temperature; D006801:Humans; D038101:Insulator Elements; D050504:Oncolytic Viruses / Q000235:genetics / Q000502:physiology; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D019076:Transgenes; D014779:Virus Replication / Q000235:genetics
D018840:HSP70 Heat-Shock Proteins; C491129:HSPA7 protein, human