KFERQ Sequence in Ribonuclease A-mediated Cytotoxicity

Onconase® (ONC) is an amphibian ribonuclease that is in clinical trials as a cancer chemotherapeutic agent. ONC is a homolog of ribonuclease A (RNase A). RNase A can be made toxic to cancer cells by replacing Gly88 with an arginine residue, thereby enabling the enzyme to evade the endogenous cytosol...

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Bibliographic Details
Published in:The Journal of biological chemistry 2002-03, Vol.277 (13), p.11576-11581
Main Authors: Haigis, Marcia C., Kurten, Erin L., Abel, Richele L., Raines, Ronald T.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Antineoplastic Agents - chemistry
Antineoplastic Agents - pharmacology
Cell Division - drug effects
Cell Survival - drug effects
Humans
K562 Cells
Models, Molecular
Molecular Sequence Data
onconase
Protein Conformation
ribonuclease A
Ribonuclease, Pancreatic - chemistry
Ribonuclease, Pancreatic - pharmacology
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Summary:Onconase® (ONC) is an amphibian ribonuclease that is in clinical trials as a cancer chemotherapeutic agent. ONC is a homolog of ribonuclease A (RNase A). RNase A can be made toxic to cancer cells by replacing Gly88 with an arginine residue, thereby enabling the enzyme to evade the endogenous cytosolic ribonuclease inhibitor protein (RI). Unlike ONC, RNase A contains a KFERQ sequence (residues 7–11), which signals for lysosomal degradation. Here, substitution of Arg10 of the KFERQ sequence has no effect on either the cytotoxicity of G88R RNase A or its affinity for RI. In contrast, K7A/G88R RNase A is nearly 10-fold more cytotoxic than G88R RNase A and has more than 10-fold less affinity for RI. Up-regulation of the KFERQ-mediated lysosomal degradation pathway has no effect on the cytotoxicity of these ribonucleases. Thus, KFERQ-mediated degradation does not limit the cytotoxicity of RNase A variants. Moreover, only two amino acid substitutions (K7A and G88R) are shown to endow RNase A with cytotoxic activity that is nearly equal to that of ONC.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M112227200