Translational up-regulation of Aurora-A in EGFR-overexpressed cancer.
Abnormal expression of Aurora-A and epidermal growth factor receptor (EGFR) is observed in different kinds of cancer and associated with poor prognosis in cancer patients. However, the relationship between Aurora-A and EGFR in tumour development was not clear. In previous reports, we found that EGFR translocates to nucleus to activate Aurora-A expression after EGF treatment in EGFR-overexpressed cells. However, we also observed that not all the EGFR-overexpressed cells have the nuclear EGFR pathway to mediate the Aurora-A expression. In this study, we demonstrated that EGF signalling increased the Aurora-A protein expression in EGFR-overexpressed colorectal cancer cell lines via increasing the translational efficiency. In addition, the overexpression of EGFR was also associated with higher expression of Aurora-A in clinical colorectal samples. Activation of the PI3K/Akt/mTOR and MEK/ERK pathways mediated the effect of EGF-induced translational up-regulation. Besides, only the splicing variants containing exon 2 of Aurora-A mRNA showed increased interaction with the translational complex to synthesize Aurora-A protein under EGF stimulus. Besides, the exon 2 containing splicing variants were the major Aurora-A splicing forms expressed in human colorectal cancers. Taken together, our results propose a novel regulatory mechanism for the abnormal expression of Aurora-A in EGFR-overexpressed cancers, and highlight the importance of alternative 5'-UTR splicing variants in regulating Aurora-A expression. Furthermore, the specific expression of exon 2 containing splicing variants in cancer tissues may serve as a potential target for cancer therapy in the future.
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Chien-Hsien
CH
Lai
Joseph T
JT
Tseng
Yi-Chao
YC
Lee
Ying-Ju
YJ
Chen
Jeng-Chang
JC
Lee
Bo-Wen
BW
Lin
Tai-Chien
TC
Huang
Yao-Wen
YW
Liu
Tzeng-Horng
TH
Leu
Yi-Wen
YW
Liu
Ya-Ping
YP
Chen
Wen-Chang
WC
Chang
Liang-Yi
LY
Hung
D020121:5' Untranslated Regions / Q000235:genetics; D017398:Alternative Splicing / Q000235:genetics; D064127:Aurora Kinases; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000235:genetics* / Q000473:pathology; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics*
D020121:5' Untranslated Regions; D064127:Aurora Kinases; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger