Document Detail

HER2 as Therapeutic Target for Overcoming ATP-binding Cassette Transporter-Mediated Chemoresistance in Small Cell Lung Cancer.
MedLine Citation:
PMID:  22389470     Owner:  NLM     Status:  Publisher    
Small Cell Lung Cancer (SCLC) easily acquires multidrug resistance after successful initial therapy. Overexpression of ATP-binding cassette (ABC) transporters is important for the multidrug resistance. Among them, ABCB1 and ABCG2 are known to be upregulated in chemoresistant SCLC. We found that human epidermal growth factor receptor 2 (HER2) expressions are also upregulated in chemoresistant SBC-3/ETP, SBC-3/SN-38 and SBC-3/CDDP cells, compared to chemosensitive SBC-3 cells. Lapatinib, a tyrosine kinase inhibitor of HER2, could not suppress proliferation of these HER2-positive SCLC cells alone, but successfully restored chemosensitivity to etoposide and SN-38 with a clinically applicable concentration. The reversal effect of lapatinib was thought to be caused by inhibition of drug efflux-pump functions of ABC transporters, although lapatinib itself has been reported to be a substrate for them. Moreover, knocking down of HER2 by a small interfering RNA weakened the effect of lapatinib on ABCB1, indicating the involvement of HER2 in the inhibitory mechanisms. Notably, we demonstrated that caveolin-1 and Src play key roles in modulating ABCB1 function via HER2 inactivation. In SBC-3/ETP cells, dephosphorylation of HER2 by lapatinib activates Src and successively leads to increase caveolin-1 phosphorylation. Through this process, caveolin-1 dissociates from HER2 and strengthens association with ABCB1, and finally impairs the pump functions. Furthermore, we demonstrated that treatment by lapatinib in combination with etoposide or irinotecan significantly suppresses the growth of subcutaneous SBC-3/ETP and SBC-3/SN-38 tumors in mice, respectively. Collectively, these results indicate that combination therapy with lapatinib and cytotoxic agents could conquer ABC transporter-mediated chemoresistance especially in HER2-positive SCLC.
Toshiyuki Minami; Takashi Kijima; Yasushi Otani; Satoshi Kohmo; Ryo Takahashi; Izumi Nagatomo; Haruhiko Hirata; Mayumi Suzuki; Koji Inoue; Yoshito Takeda; Hiroshi Kida; Isao Tachibana; Atsushi Kumanogoh
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-3-2
Journal Detail:
Title:  Molecular cancer therapeutics     Volume:  -     ISSN:  1538-8514     ISO Abbreviation:  -     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-3-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101132535     Medline TA:  Mol Cancer Ther     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1Respiratory Medicine, Allergy and Rheumatic Diseases, Osaka University Graduate School of Medicine.
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