title: Hair keratin KRT81 is expressed in normal and breast cancer cells and contributes to their invasiveness.
abstract: Keratins are fibrous proteins. Hair keratins constitute hard structures such as the hair and nails, and cytokeratins have been used as markers of breast carcinoma. However, the expression and function of full-size hair keratin genes have not been previously demonstrated in breast cancer. We investigated the expression of the hair keratin, KRT81, and its function in human breast cancer and normal mammary epithelial cells. Western blotting showed full size 55-kDa KRT81 expression in the human breast cancer cell lines, MCF7, SKBR3 and MDA-MB-231, normal human mammary epithelial cells (HMEC), and non-neoplastic cells (MCF10A). Reverse transcription-polymerase chain reaction revealed that the full size KRT81, including its 5' region is expressed in breast cells. Immunohistochemical and immunofluorescence analyses showed that KRT81 was located in the cytoplasm. To investigate the function of KRT81, we knocked down KRT81 by siRNA in MCF10A cells. Microarray analysis revealed that the expression of genes related to invasion such as matrix metallopeptidase (MMP)9 was decreased. In KRT81-knockdown MDA-MB231 cells, zymography revealed a decrease in MMP9 activity, while scratch and invasion assays revealed that KRT81-knockdown decreased cell migration and invasion abilities. This is the first study showing that full size KRT81 is expressed in normal breast epithelial cells and breast cancer cells. Moreover, our results indicate that KRT81 contributes to the migration and invasion of breast cancer cells.
authors.affiliation: Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki 036-8564, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Nanashima
authors.affiliation: Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki 036-8564, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Horie
authors.affiliation: Department of Biochemistry and Genome Biology, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Department of Biochemistry and Genome Biology, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Shimizu
authors.affiliation: Department of Biochemistry and Genome Biology, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Tsuchida
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement; D003593:Cytoplasm / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053564:Keratins, Hair-Specific / Q000235:genetics* / Q000378:metabolism*; D053531:Keratins, Type II / Q000235:genetics* / Q000378:metabolism*; D061986:MCF-7 Cells; D042361:Mammary Glands, Human / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods
chemical_list: C507600:KRT81 protein, human; D053564:Keratins, Hair-Specific; D053531:Keratins, Type II