Cetuximab directly inhibits P-glycoprotein function in vitro independently of EGFR binding.
OBJECTIVE
Cancer chemotherapy typically combines anticancer drugs from different mechanisms of action. However, cancer cells could become resistant to chemotherapy via P-gp or other ATP binding cassette proteins. The objective of this study was to evaluate whether cetuximab, monoclonal antibody directed toward epidermal growth factor receptor, could increase intracellular concentration of conventional chemotherapy by interacting with P-gp.


METHODS
Two human ovarian carcinoma (IGROV1) and two human embryonary kidney (HEK) cell lines, overexpressing or weakly expressing P-gp, were used. Their EGFR expressions were compared. Cetuximab effect on P-gp functionality was evaluated by measuring doxorubicin (P-gp fluorescent substrate) intracellular accumulation. Cetuximab ability to increase doxorubicin cytotoxicity was evaluated by MTT test. A quaternary structure model of the P-gp-Cetuximab complex was established.


RESULTS
Exposure of cetuximab in therapeutic concentrations range with doxorubicin led to significant doxorubicin accumulation and reversion of doxorubicin resistance in P-gp expressing cells lines. Molecular modeling of P-gp-cetuximab interactions showed that cetuximab is able to bind P-gp extracellular part.


CONCLUSIONS
Cetuximab increases a P-gp substrate intracellular accumulation in both P-gp expressing cell lines, independently of their EGFR expression. One hypothesis is that cetuximab binding on P-gp could hamper the conformational changes that occur during drugs efflux. Our results offer new possibilities of research on monoclonal antibodies influence in MDR phenomena.
Laboratoire de Pharmacologie, Service Pharmacie, Hôpital Paul Brousse AP-HP, Villejuif, France; Laboratoire de Pharmacie Clinique - EA 4123, Univ Paris-sud 11, Faculté de Pharmacie, Châtenay-Malabry, France. Electronic address: celinechu82@yahoo.fr.
C
C
Chu
Laboratoire de Pharmacie Clinique - EA 4123, Univ Paris-sud 11, Faculté de Pharmacie, Châtenay-Malabry, France.
M S
MS
Noël-Hudson
UMR CNRS 8126, Institut de Cancérologie Gustave Roussy, Villejuif, France.
J
J
Bénard
BioCis - UMR CNRS 8076, Univ Paris-sud 11, Faculté de Pharmacie, Châtenay-Malabry, France.
T
T
Ha-Duong
Laboratoire de Pharmacie Clinique - EA 4123, Univ Paris-sud 11, Faculté de Pharmacie, Châtenay-Malabry, France.
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F
Allaoui
Laboratoire de Pharmacie Clinique - EA 4123, Univ Paris-sud 11, Faculté de Pharmacie, Châtenay-Malabry, France.
R
R
Farinotti
Laboratoire de Pharmacologie, Service Pharmacie, Hôpital Paul Brousse AP-HP, Villejuif, France; Laboratoire de Pharmacie Clinique - EA 4123, Univ Paris-sud 11, Faculté de Pharmacie, Châtenay-Malabry, France.
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L
Bonhomme-Faivre
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000970:Antineoplastic Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000068818:Cetuximab / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000378:metabolism / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D006801:Humans; D062105:Molecular Docking Simulation; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D014162:Transfection
C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D000970:Antineoplastic Agents; D004317:Doxorubicin; C512478:EGFR protein, human; D066246:ErbB Receptors; D000068818:Cetuximab
Cetuximab; HEK cells; IGROV1 cells; Molecular modeling; P-glycoprotein