Sorting nexin 2-mediated membrane trafficking of c-Met contributes to sensitivity of molecular-targeted drugs.
The sorting nexin (SNX) family is a diverse group of cytoplasmic and membrane-associated proteins that are involved in membrane-trafficking steps within the endocytotic network. SNX1 and SNX2 are components of the mammalian retromer complex and they also play critical roles in the membrane trafficking of growth factor receptors including epidermal growth factor receptor (EGFR) and c-Met. The human lung cancer cell lines, which harbor activating mutations in the kinase domain of EGFR gene, are sensitive to EGFR-targeted drugs gefitinib or erlotinib. However, a lung cancer cell line harboring gene amplification of c-Met is sensitive to the c-Met-targeted drug SU11274 but not to EGFR-targeted drugs. C-Met overexpression is identified as one of the bypass mechanisms for acquired resistance to EGFR-targeted drugs. Here we show that the siRNA-mediated knockdown of SNX2 decreases the cell-surface localization of c-Met, but not that of EGFR, resulting in lysosomal degradation of the c-Met protein. SNX2 specifically interacts with c-Met and treatment with lysosomal inhibitors almost completely annihilates downregulation of c-Met protein by SNX2 knockdown. Therefore, silencing of SNX2 markedly alters sensitivity to anticancer drugs targeted to c-Met (SU11274) and EGFR (gefitinib and erlotinib) through promotion of compensatory activation of the EGFR pathway in lung cancer cells. These findings suggest that development of drugs targeting SNX2 could be useful in overcoming drug resistance to EGFR-targeted drugs in lung cancer cells harboring c-Met gene amplification.
Department of Pharmaceutical Oncology, Kyushu University, Fukuoka, Japan.
Sayaka
S
Ogi
Hideaki
H
Fujita
Masaki
M
Kashihara
Chizuko
C
Yamamoto
Kahori
K
Sonoda
Isamu
I
Okamoto
Kazuhiko
K
Nakagawa
Shigehiro
S
Ohdo
Yoshitaka
Y
Tanaka
Michihiko
M
Kuwano
Mayumi
M
Ono
D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008247:Lysosomes / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D058990:Molecular Targeted Therapy; D009154:Mutation / Q000187:drug effects; D021381:Protein Transport; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism*; D011799:Quinazolines / Q000494:pharmacology; D058305:Sorting Nexins / Q000235:genetics / Q000378:metabolism*
D000970:Antineoplastic Agents; D026901:Membrane Transport Proteins; D011799:Quinazolines; C513979:SNX2 protein, human; D058305:Sorting Nexins; C512478:EGFR protein, human; D066246:ErbB Receptors; D019859:Proto-Oncogene Proteins c-met; D000077156:Gefitinib