title: The a3 isoform vacuolar type H⁺-ATPase promotes distant metastasis in the mouse B16 melanoma cells.
abstract: Accumulating evidence indicates that the acidic microenvironments critically influence malignant behaviors of cancer including invasiveness, metastasis, and chemoresistance. Because the vacuolar-type H(+)-ATPase (V-ATPase) has been shown to cause extracellular acidification by pumping protons, we studied the role of V-ATPase in distant metastasis. Real-time PCR analysis revealed that the high-metastatic B16-F10 melanoma cells strongly expressed the a3 isoform V-ATPase compared to the low-metastatic B16 parental cells. Consistent with this, B16-F10 cells created acidic environments in lung metastases by acridine orange staining and strong a3 V-ATPase expression in bone metastases by immunohistochemistry. Immunocytochemical analysis showed B16-F10 cells expressed a3 V-ATPase not only in cytoplasm but also plasma membrane, whereas B16 parental cells exhibited its expression only in cytoplasm. Of note, knockdown of a3 V-ATPase suppressed invasiveness and migration with reduced MMP-2 and MMP-9 expression in B16-F10 cells and significantly decreased lung and bone metastases, despite that tumor growth was not altered. Importantly, administration of a specific V-ATPase a3 inhibitor FR167356 reduced bone metastasis of B16-F10 cells. These results suggest that a3 V-ATPase promotes distant metastasis of B16-F10 cells by creating acidic environments via proton secretion. Our results also suggest that inhibition of the development of cancer-associated acidic environments by suppressing a3 V-ATPase could be a novel therapeutic approach for the treatment of cancer metastasis.
authors.affiliation: Department of Molecular and Cellular Biochemistry, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nishisho
authors.forename: Kenji
authors.initials: K
authors.lastname: Hata
authors.forename: Masako
authors.initials: M
authors.lastname: Nakanishi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Morita
authors.forename: Ge-Hong
authors.initials: GH
authors.lastname: Sun-Wada
authors.forename: Yoh
authors.initials: Y
authors.lastname: Wada
authors.forename: Natsuo
authors.initials: N
authors.lastname: Yasui
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yoneda
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D001572:Benzofurans / Q000494:pharmacology; D001859:Bone Neoplasms / Q000201:enzymology / Q000556:secondary*; D049109:Cell Proliferation; D008175:Lung Neoplasms / Q000201:enzymology / Q000556:secondary*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008546:Melanoma, Experimental / Q000201:enzymology / Q000556:secondary*; D051379:Mice; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D059016:Tumor Microenvironment; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*; D014945:Wound Healing / Q000235:genetics
chemical_list: C484226:Atp6ap1 protein, mouse; D001549:Benzamides; D001572:Benzofurans; C495452:FR 167356; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D025262:Vacuolar Proton-Translocating ATPases