Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have designed and studied antisense oligodeoxynucleotides (oligonucleotides; oligos) which we call 'pseudo-cyclic oligonucleotides' (PCOs). PCOs contain two oligonucleotide segments attached through their 3'-3'- or 5'-5'-ends. One of the segments of the PCO is an antisense oligo complementary to a target mRNA, and the other is a short protective oligo that is 5-8 nucleotides long and complementary to the 3'- or 5'-end of the antisense oligo. As a result of complementarity between the antisense and protective oligo segments, PCOs form intramolecular pseudo-cyclic structures in the absence of the target RNA. The antisense oligo segment of PCOs used for the studies described here is complementary to an 18-nucleotide-long site on the mRNA of the protein kinase A regulatory subunit RIalpha (PKA-RIalpha). Thermal melting studies of PCOs in the absence and presence of the complementary RNA suggest that the pseudo-cyclic structures formed in the absence of the target RNA dissociate, bind to the target RNA, and form heteroduplexes. The results of RNase H cleavage assays suggest that PCOs bind to complementary RNA and activate RNase H in a manner similar to that of an 18-mer conventional antisense PS-oligo. In snake venom (a 3'-exonuclease) or spleen (a 5'-exonuclease) phosphodiesterase digestion studies, PCOs are more stable than conventional antisense oligos because of the presence of 3'-3'- or 5'-5'-linkages and the formation of intramolecular pseudo-cyclic structures. PCOs with a phosphorothioate antisense oligo segment inhibited cell growth of MDA-MB-468 and GEO cancer cell lines similar to that of the conventional antisense PS-oligo, suggesting efficient cellular uptake and target binding. The nuclease stability studies in mice suggest that PCOs have higher in vivo stability than antisense PS-oligos. The studies in mice showed similar pharmacokinetic and tissue distribution profiles for PCOs to those of antisense PS-oligos in general, but rapid elimination from selected tissues.
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PMID:Pseudo-cyclic oligonucleotides: in vitro and in vivo properties. 1065 77

A blunt-ended 19-mer short interfering hybrid (siHybrid) (H) comprised of sense-DNA/antisense-RNA targeting HER-2 mRNA was encapsulated in a liposomal nanoplex with anti-transferrin receptor single-chain antibody fragment (TfRscFv) as the targeting moiety for clinically relevant tumor-specific delivery. In vitro delivery to a human pancreatic cell line (PANC-1) was shown to exhibit sequence-specific inhibition of 48-h cell growth with an IC50 value of 37 nM. The inhibitory potency of this siHybrid was increased (IC50 value of 7.8 nM) using a homologous chemically modified siHybrid (mH) in which the 19-mer sense strand had the following pattern of 2 '-deoxyinosine (dI) and 2 '-O-methylribonucleotide (2 '-OMe) residues: 5'-d(TITIT)-2'OMe(GCGGUGGUU)-d(GICIT). These modifications were intended to favor antisense strand-mediated RNAi while mitigating possible sense strand-mediated off-target effects and RNase H-mediated cleavage of the antisense RNA strand. The presently reported immunoliposomal delivery system was successfully used in vivo to inhibit HER-2 expression, and thus induce apoptosis in human breast carcinoma tumors (MDA-MB-435) in mice upon repeated i.v. treatment at a dose of 3 mg/kg of H or mH. The in vivo potency of modified siHybrid mH appeared to be qualitatively greater than that of H, as was the case in vitro.
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PMID:Chemically modified short interfering hybrids (siHYBRIDS): nanoimmunoliposome delivery in vitro and in vivo for RNAi of HER-2. 1690 21

Procathepsin D (pCD), a zymogen of lysosomal aspartic peptidase cathepsin D, overexpression is correlated with highly invasive malignancies, including breast cancer. Recently, different studies have shown the role of secreted pCD as mitogen acting both in an autocrine and a paracrine manner. The aim of the present study is to examine the anti-tumor effects elicited by a decrease in the protein level of pCD by ribozyme and to explore the therapeutic potential of this specific targeting. Using the mFold program, we designed seven anti-pCD ribozymes and checked the accessibility to target pCD mRNA by RNase H cleavage experiment in a cell-free system. The sequences of the 4 most effective ribozymes were cloned and stably transfected in a highly metastatic human breast cancer cell line, MDA-MB-231, to knock down the expression of pCD. Downregulation of pCD due to ribozyme expression was observed by Western blotting and real-time RT-PCR. Stably transfected cells with anti-pCD ribozymes exhibited a significant lowering of in vitro invasion (p<0.001) and reduction in lung colonization potential in nude mice when compared to control ribozyme transfected cells. We also found that downregulation of pCD by ribozyme promotes apoptosis of MDA-MB-231 cells on serum deprivation. These results suggest that we have generated a biologically functional ribozyme against pCD with possible therapeutic implications in breast cancer cells.
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PMID:Ribozyme-targeting procathepsin D and its effect on invasion and growth of breast cancer cells: an implication in breast cancer therapy. 1739 25