Acquisition of EMT phenotype in the gefitinib-resistant cells of a head and neck squamous cell carcinoma cell line through Akt/GSK-3β/snail signalling pathway.
BACKGROUND
Epithelial mesenchymal transition (EMT) is known to be associated with chemoresistance as well as increased invasion/metastasis. However, the relationship between EMT and resistance to an epidermal growth factor receptor (EGFR) -targeting drug in head and neck squamous cell carcinoma (HNSCC) remains unknown. In this study, we investigated the acquisition of EMT by gefitinib in HNSCC cell line (UMSCC81B).


METHODS
We isolated fibroblastoid variant (81B-Fb) from gefitinib-resistant UMSCC81B-GR3 cells obtained after increasing the doses of gefitinib treatment in vitro and examined EMT and its underlying mechanism.


RESULTS
81B-Fb cells exhibited fibroblast-like morphology, increased motility, loss of E-cadherin, acquisition of vimentin and snail expression. In 81B-Fb cells, downregulation of EGFR, which is mediated by increased ubiquitination, and activation of downstream protein kinase B (Akt), glycogen synthase kinase-beta (GSK-3β) signalling and upregulation of snail expression were observed compared with UMSCC81B cells. LY294002, but not U0126, suppressed foetal bovine serum or heregulin-β1-induced phosphorylation of Akt/GSK-3β and snail expression together with the inhibition of 81B-Fb cell motility. Furthermore, forced expression of EGFR resulted in partial restoration of gefitinib sensitivity and reversal of EMT.


CONCLUSIONS
These results suggest that EMT in the gefitinib-resistant cells is mediated by the downregulation of EGFR and compensatory activation of Akt/GSK-3β/snail pathway.
Division of Oncological Pathology, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya 464-8681, Japan.
S
S
Maseki
K
K
Ijichi
H
H
Tanaka
M
M
Fujii
Y
Y
Hasegawa
T
T
Ogawa
S
S
Murakami
E
E
Kondo
H
H
Nakanishi
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor / Q000187:drug effects; D002465:Cell Movement; D049109:Cell Proliferation; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D058750:Epithelial-Mesenchymal Transition; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D000077156:Gefitinib; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006258:Head and Neck Neoplasms / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010641:Phenotype; D010766:Phosphorylation; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology*; D015398:Signal Transduction; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism
D000970:Antineoplastic Agents; D011799:Quinazolines; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D066246:ErbB Receptors; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D000077156:Gefitinib