A Single Ribozyme to Catalyze both Trimming and Transacting Catalysis - Potential Therapeutic for HPV Infection and Cervical Cancer
Implementation of triplex systems that significantly enhance R434 in vitro activity is offered as an alternative to the antisense oligodeoxynucleotide treatment of cervical cancer
Full description
This technology relates to a potential therapeutic for treating
human papillomavirus (HPV) infection as well as cervical
cancer. It is acknowledged that HPV is the primary agent
associated with cervical cancer. The life cycle of HPVs
progresses with epithelial differentiation and may persist for
decades. The E6 and E7 oncogenes are responsible for two
viral proteins that target p53 and Rb. The persistence of E6
and E7 in cervical carcinomas has led to them being
recognized as the hallmark of cervical carcinomas and makes
them excellent targets for therapy. Previously, we reported
an engineered hairpin ribozyme (R434) that caused down-
regulation of HPV-16 E6/E7 mRNA and inhibited growth of
both HPV-16 immortalized cells and tumor cells. To increase
efficiency of R434 we constructed a ribozyme expression
system (TRL-5) entirely based on cis-cleaving (trimming)
hairpin ribozymes (triplex system) that release R434 from
long transcripts. Because of the modular structure of the
hairpin ribozyme, the catalytic domain B can independently
recognize cis or trans targets allowing the use of the same
ribozymes for both trimming and therapeutic duties. Thus,
this improved system was designed as a three-ribozymes
unit in a canonical triplex using an inverted cleavage from one
trimming ribozyme.
The Rz434bis system was designed to use a single R434
ribozyme to catalyze both trimming and trans-acting
activities. This procedure resulted in a reduced-size triplex
system that uses R434 catalytic domain to self-excise itself.
RNA from Rz434bis and TRL-5 templates released R434 by a
self-processing mechanism thus allowing for the individual
activity of multiple trans-acting ribozymes. Both Rz434bis
and TRL-5 systems produced an increased cleavage
efficiency of HPV-16 target site nt 410 to 445 when
expressed from linear or circular templates. Furthermore,
duplex Rz434bis and TRL-5 were more efficient in cleaving E6
than duplex single R434. The use of triplex configurations
with multi-target ribozymes will ultimately result in better in
vivo HPV-16 E6/E7 mRNA degradation. Therefore,
implementation of the triplex systems that significantly
enhance R434 in vitro activity is offered as an alternative to
the antisense oligodeoxynucleotide treatment of cervical
cancer.
Patent information
U.S. Provisional Application No. 60/675,076 filed 25 April
2005 (HHS Reference No. E-142-2005/0-US-01)
Inventors: Joseph A. DiPaolo (NCI) et al.
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