Abstract P1-07-28: Expression of S100A14 promotes cancer cell invasion and metastasis and is associated with poor prognosis in breast cancer
Authors: Sugino Takashi , Tanaka Mizuko , Oishi Takuma , Nakajima Takashi 
Published: May 2015

Abstract
Introduction: Identifying key molecules involved in cancer metastasis is important in anticancer drug discovery. To identify such molecules, we used a dual approach involving: 1) gene screening and in vivo confirmation of metastasis-promoting molecules using a mouse mammary tumor model; and 2) functional and clinicopathological analyses of the candidate molecules in a human cancer. The products of several candidate genes promoted metastasis of mouse mammary tumors. A protein designated S100A14 promoted metastasis in the mouse model and was found to be associated with poor prognosis in human breast cancer patients.
Methods and Results: 1) Identification of metastasis-related molecules: We established two highly metastatic cell lines, 66Lu10 and 66HM, which formed multiple metastatic colonies in general organs, from MCH66 mouse mammary tumor cells. Two low-metastasis cell lines, 66C8 and 66LM1, were also established. DNA microarray analysis was used to identify candidate metastasis-related genes based on differential expression in 66Lu10 and 66HM cells compared with 66C8 and 66LM1. An in vivo metastasis assay in which the highly metastatic cells were transfected with gene-specific siRNAs and orthotopically inoculated into mice was performed to confirm the metastasis-promoting activity of the candidate genes. Several novel molecules that promoted metastasis in the mouse model were identified, including S100A14. 2) Significance of S100A14 in human cancer: Analysis of S100A14 protein expression in various human cancer cell lines and tissues revealed that S100A14 expression is upregulated in breast cancer. Functional analysis using MCF7 and SK-BR-3 human breast cancer cells showed that S100A14 colocalizes with F-actin on the cell membrane at cell-cell attachment sites and on focal adhesions at the leading edge. Immunoprecipitation analysis also demonstrated an interaction between S100A14 and F-actin. Boyden chamber and wound-healing assays showed that S100A14 knockdown substantially suppresses the invasive activity of both cell lines. Immunohistochemical analysis of archival specimens of primary tumors from 167 breast cancer patients showed strong membranous staining of S100A14 (53%). Elevated expression of this protein was significantly associated with younger age (&lt;60 years), ER-negative status, HER2-positive status, and poorer prognosis (P=0.0002).
Conclusions: Using our mouse mammary tumor model for identifying metastasis-related genes, we identified S100A14 as a strong candidate metastasis-promoting molecule in vivo. Functional analyses using human breast cancer cell lines indicated that S100A14 promotes invasive activity via interaction with cytoskeletal components. Upregulated expression of S100A14 is associated with poor prognosis in breast cancer patients. Therefore, S100A14 is a potential prognostic biomarker and breast cancer therapeutic target.
Citation Format: Takashi Sugino, Mizuko Tanaka, Takuma Oishi, Takashi Nakajima. Expression of S100A14 promotes cancer cell invasion and metastasis and is associated with poor prognosis in breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-07-28.