Identification of URST1 as a novel prognostic biomarker and therapeutic target for various subtypes of breast cancer

Breast cancer is one of the most common causes of cancer death for women worldwide. To identify diagnostic and therapeutic targets for breast cancer, we screened molecules that were highly expressed in the majority of breast cancers by our gene expression profile database. During this process, we identified URST1 (up-regulated in solid tumor 1) as a candidate. Immunohistochemical analysis showed that URST1 was expressed in 195 of 257 (75%) breast cancer cases (69% in luminal type, 88% in HER2-positive cancer, 86% in Triple-negative cancer) that had undergone curative surgery, whereas no staining was observed in adjacent normal breast tissues. URST1 expression was significantly related to poor clinical outcome for breast cancer patients (P = 0.01, Log-rank test) and multivariate analysis showed that it was an independent prognostic factor. Knockdown of endogenous URST1 expression by siRNAs against URST1 or treatment with URST1 inhibitor significantly inhibited the growth of breast cancer cells through cell cycle arrest at G2/M phase. Our data suggest that URST1 is likely to be a prognostic biomarker and therapeutic target for various subtypes of breast cancers. Citation Format: Masako Nakamura, Atsushi Takano, Phung Manh Thang, Yohei Miyagi, Yataro Daigo. Identification of URST1 as a novel prognostic biomarker and therapeutic target for various subtypes of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2910.