title: Reduction of tumorigenesis and invasion of human breast cancer cells by whey acidic protein (WAP).
abstract: Whey acidic protein (WAP) is a major component of whey, which has two or three WAP motif domains characterized by a four-disulfide core (4-DSC) structure similar to the serine protease inhibitor. We have previously found that WAP inhibits the proliferation of mammary epithelial cells in vitro and in vivo [N. Nukumi, K. Ikeda, M. Osawa, T. Iwamori, K. Naito, H. Tojo, Regulatory function of whey acidic protein in the proliferation of mouse mammary epithelial cells in vivo and in vitro, Dev. Biol. 274 (2004) 31-44]. We report herein that WAP also reduces the progression of human breast cancer cells (MCF-7 and MDA-MB-453 cells). We have demonstrated that the forced expression of WAP in MCF-7 cells reduces the proliferation in either the presence or absence of estrogen. The tumor progression of WAP-expressing MCF-7 cells in nude mice is significantly suppressed more than that of mock-MCF-7 cells following the reduced expression of angiopoietin-2 gene. We have confirmed that the invasive activity of breast cancer cells is reduced to approximately 30% of that of mock cells by the forced expression of exogenous WAP through its inhibition of degradation of laminin. These data suggest that WAP has a protease-inhibitory function on the progression of breast cancer cells. It is therefore possible to utilize WAP as therapeutic protein against tumorigenesis of breast cancer.
authors.affiliation: Laboratory of Applied Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan. nukumi@ims.u-tokyo.ac.jp
authors.forename: Naoko
authors.initials: N
authors.lastname: Nukumi
authors.forename: Tokuko
authors.initials: T
authors.lastname: Iwamori
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kano
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Naito
authors.forename: Hideaki
authors.initials: H
authors.lastname: Tojo
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D051379:Mice; D008894:Milk Proteins / Q000235:genetics / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D008894:Milk Proteins; C024471:whey acidic proteins; D010447:Peptide Hydrolases