The EGFR-GEP100-Arf6-AMAP1 signaling pathway specific to breast cancer invasion and metastasis.
Tumors are tissue-specific diseases, and their mechanisms of invasion and metastasis are highly diverse. In breast cancer, biomarkers that specifically correlate with the invasive phenotypes have not been clearly identified. A small GTPase Arf6 primarily regulates recycling of plasma membrane components. We have shown that Arf6 and its effector AMAP1 (DDEF1, DEF1, ASAP1 and centaurin beta4) are abnormally overexpressed in some breast cancers and used for their invasion and metastasis. Overexpression of these proteins is independent of the transcriptional upregulation of their genes, and occurs only in highly malignant breast cancer cells. We recently identified GEP100 (BRAG2) to be responsible for the Arf6 activation to induce invasion and metastasis, by directly binding to ligand-activated epidermal growth factor receptor (EGFR). A series of our studies revealed that for activation of the invasion pathway of EGFR, it is prerequisite that Arf6 and AMAP1 both are highly overexpressed, and that EGFR is activated by ligands. Pathological analyses indicate that a significant large population of human ductal cancers may utilize the EGFR-GEP100-Arf6-AMAP1 pathway for their malignancy. Microenvironments have been highly implicated in the malignancy of mammary tumors. Our results reveal an aspect of the precise molecular mechanisms of some breast cancers, in which full invasiveness is not acquired just by intracellular alterations of cancer cells, but extracellular factors from microenvironments may also be necessary. Possible translation of our knowledge to cancer therapeutics will also be discussed.
Department of Molecular Biology, Osaka Bioscience Institute, Osaka, Japan. sabe@obi.or.jp
Hisataka
H
Sabe
Shigeru
S
Hashimoto
Masaki
M
Morishige
Eiji
E
Ogawa
Ari
A
Hashimoto
Jin-Min
JM
Nam
Koichi
K
Miura
Hajime
H
Yano
Yasuhito
Y
Onodera
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015820:Cadherins / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009690:Nucleic Acid Conformation; D010587:Phagocytosis / Q000502:physiology; D012323:RNA Processing, Post-Transcriptional; D015398:Signal Transduction / Q000502:physiology*
D000089982:ADP-Ribosylation Factor 6; C117891:ASAP1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D015820:Cadherins; D002352:Carrier Proteins; D020662:Guanine Nucleotide Exchange Factors; C504483:IQSEC1 protein, human; C465633:MYCBPAP protein, human; D066246:ErbB Receptors; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human