Opposing influence of intracellular and membrane thiols on the toxicity of reducible polycations.
Toxicity of polycations has been recognized since their first use in gene delivery. Bioreducible polycations attract attention because of their improved safety due to selective intracellular degradation by glutathione (GSH). Here we present a systematic study of the toxicity of bioreducible poly(amido amine)s (PAA). PAA with increasing content of disulfide bonds were synthesized by Michael addition. Toxicity of PAA was evaluated in two cell lines with different innate levels of intracellular GSH. Increasing the content of disulfide bonds decreased the toxicity of PAA, with more significant decrease observed in cells with high GSH. Depleting intracellular GSH by diethyl maleate resulted in increased toxicity of bioreducible PAA. In contrast, increasing the GSH concentrations by growing cells in hypoxic conditions resulted in further decreased toxicity compared with cells grown in normoxic conditions. The presence of exofacial plasma membrane thiols selectively increased toxicity of bioreducible PAA while having no effect on non-degradable controls. These results improve our understanding of the cellular mechanisms of polycation toxicity. They also shed light on the opposing effects of different cellular thiol pools on the toxicity of bioreducible polycations.
Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, United States.
Chao
C
Wu
Jing
J
Li
Yu
Y
Zhu
Jun
J
Chen
David
D
Oupický
D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D053179:Caspase 7 / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005978:Glutathione / Q000737:chemistry*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D011073:Polyamines / Q000737:chemistry / Q000633:toxicity*; D000071228:Polyelectrolytes; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D023382:Toxicity Tests, Acute; D014162:Transfection
D053148:Caspase 3; D053179:Caspase 7; D005978:Glutathione; D007770:L-Lactate Dehydrogenase; D011073:Polyamines; D000071228:Polyelectrolytes; D013438:Sulfhydryl Compounds; C531249:Poly(amidoamine); C505407:CASP3 protein, human; C505520:CASP7 protein, human
Bioreducible polycations; Glutathione; Non-viral gene delivery; Polycations; Toxicity