Protective efficacy of Anopheles minimus CYP6P7 and CYP6AA3 against cytotoxicity of pyrethroid insecticides in Spodoptera frugiperda (Sf9) insect cells
- Author:
Duangkaew, P.
;
Kaewpa, D.
;
Rongnoparut, P.*
- Publication Type:Journal Article
- From:Tropical Biomedicine
2011;28(2):293-301
- CountryMalaysia
- Language:English
-
Abstract:
Cytochrome P450 monooxygenases (P450s) are enzymes known to metabolize a
wide variety of compounds including insecticides. Their overexpression leading to enhanced
insecticide detoxification could result in insecticide resistance in insects. The increased
mRNA expression of two P450 genes, CYP6P7 and CYP6AA3, has been previously observed
in laboratory-selected deltamethrin-resistant Anopheles minimus, a major malaria vector in
Southeast Asia, suggesting their role in detoxification of pyrethroids. In this study CYP6P7
and CYP6AA3 were expressed in insect Spodoptera frugiperda (Sf9) cells via baculovirusdirected
expression system. Insecticide detoxification capabilities of Sf9 cells with and
without expression of CYP6P7 or CYP6AA3 were evaluated using 3-(4,5-dimethyl-thiazol-2-
yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The results revealed that CYP6P7- or
CYP6AA3-expressing cells showed significantly higher cytoprotective capability than parental
Sf9 cells against cytotoxicity of pyrethroids including permethrin, cypermethrin and
deltamethrin. Such cytoprotective effect was not observed for bioallethrin (pyrethroid),
chlorpyrifos (organophosphate) and propoxur (carbamate). Moreover, expression of CYP6AA3,
but not CYP6P7, could protect cells against λ-cyhalothrin cytotoxicity. In MTT assays upon
co-incubation with piperonyl butoxide (P450 inhibitor), cytoprotective ability of CYP6P7 and
CYP6AA3 against deltamethrin was diminished, implying that pyrethroid detoxification was
due to activities of P450 enzymes. Insecticide detoxification capabilities of CYP6P7 and
CYP6AA3 observed from MTT assays were correlated to their pyrethroid metabolizing activities
observed from in vitro reconstitution enzymatic assays. Thus MTT assays using cells
expressing P450 enzymes of interest could be primarily used to determine detoxification
activities of enzymes against cytotoxic insecticides.
- Full text:W020150615366501534688.pdf
