A 37-mer hammerhead ribozyme has been designed to efficiently cleave t
he 1.4 kb mRNA of the urokinase plasminogen activator receptor (uPAR).
Under in vitro conditions, the chemically synthesized ribozyme cleave
d uPAR mRNA and inhibited its translation in a concentration-dependent
fashion. The ribozymes were 5'-[S-35]thiophosphorylated and used as a
model to analyze conditions for RNA delivery in a cultured human oste
osarcoma cell system. Ribozymes degraded immediately in cell-condition
ed medium but ribozymes complexed with lipofectin were protected from
RNases for up to 22 h. Lipofectin rapidly transported ribozyme into th
e cell, where it accumulated almost exclusively in the cytoplasm. Thus
, lipofectin dramatically enhances stability and cytoplasmic delivery
of ribozymes, potentially enabling targeting of mRNA in vivo.