title: Cyclooxygenase-2 (COX-2) negatively regulates expression of epidermal growth factor receptor and causes resistance to gefitinib in COX-2-overexpressing cancer cells.
abstract: Overexpression of cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) has been detected in many types of cancer. Although COX-2 and EGFR are closely related to each other, the exact mechanism of COX-2 in tumors has not been well understood. In this study, we investigated the relationship between COX-2 and EGFR in cancer cells. Using two cell lines stably overexpressing COX-2 (HCT-116-COX-2 and H460-COX-2) and a stable line of COX-2 knockdown MOR-P cells, we analyzed patterns of COX-2 and EGFR expression. To observe the effects of COX-2 on EGFR expression and activity, we did comparative analyses after treatment with various drugs (EGF, celecoxib, prostaglandin E(2), gefitinib, Ro-31-8425, PD98059, and SP600125) in HCT-116-Mock versus HCT-116-COX-2 cells and H460-Mock versus H460-COX-2 cells. Overexpression of COX-2 specifically down-regulated EGFR expression at the level of transcription. COX-2-overexpressing cells have a decreased sensitivity to gefitinib. COX-2 induced activation of extracellular signal-regulated kinase (ERK) and c-Jun NH(2)-terminal kinase (JNK) but suppressed Akt activation. JNK inhibition by SP600125, a specific JNK inhibitor, resulted in restoration of EGFR levels in COX-2-overexpressing cells, whereas ERK inhibition by PD98059 did not. Overexpressed COX-2 negatively regulates EGFR expression via JNK activation, leading to gefitinib resistance. COX-2 may also regulate ERK activity independently of EGFR. Therefore, resistance of COX-2-overexpressing cells to gefitinib may be due to decreased expression of EGFR by JNK activation and EGFR-independent elevation of ERK activity by COX-2. The ability of COX-2 to inhibit EGFR expression and gefitinib effects may have significance in clinical cancer therapy.
authors: Research Institute and Hospital, National Cancer Center, 809 Madu-1-dong, Ilsan-donggu, Goyang-si, Gyeonggi-do 410-769, Republic of Korea.
authors: Young Mee
authors: YM
authors: Kim
authors: Soo-Yeon
authors: SY
authors: Park
authors: Hongryull
authors: H
authors: Pyo
mesh_terms: D051546:Cyclooxygenase 2 / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D000077156:Gefitinib; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D045325:HCT116 Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D011799:Quinazolines; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D015232:Dinoprostone; D000077156:Gefitinib