FOXC2 and CLIP4 : a potential biomarker for synchronous metastasis of ≤7-cm clear cell renal cell carcinomas

// Jinwoo Ahn 1, * , Kyung Seok Han 2, * , Jun Hyeok Heo 3 , Duhee Bang 1 , You Hyun Kang 3, 4 , Hyun A. Jin 3, 4 , Sung Joon Hong 3 , Ji Hyun Lee 5 , Won Sik Ham 3 1 Department of Chemistry, Yonsei University, Seoul, Korea 2 Department of Urology, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea 3 Department of Urology and Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea 4 Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea 5 Department of Clinical Pharmacology and Therapeutics, College of Medicine, Kyung Hee University, Seoul, Korea * These authors have contributed equally to this work Correspondence to: Won Sik Ham, email: uroham@yuhs.ac Ji Hyun Lee, email: hyunihyuni@khu.ac,kr Keywords: clear cell renal cell carcinoma (ccRCC), whole exome sequencing, metastasis, FOXC2, CLIP4 Received: February 10, 2016     Accepted: May 20, 2016     Published: June 06, 2016 ABSTRACT Renal cell carcinomas (RCC) smaller than 7-cm are heterogeneous and exhibit metastatic potential in approximately 15% of cases. Although large-scale characterization of mutations in clear cell RCC (ccRCC), the most common RCC subtype, has been established, the genetic alterations related to ≤7-cm ccRCCs undergoing synchronous metastasis are poorly understood. To discover biomarkers that can be used to estimate the risk of synchronous metastasis in these ccRCC patients, we performed whole exome sequencing on the formalin-fixed paraffin-embedded (FFPE) samples of 10 ccRCC patients with ≤7-cm tumors and synchronous metastasis and expanded our study using The Cancer Genome Atlas (TCGA) ccRCC dataset (n = 201). Recurrent mutations were selected according to functional prediction and statistical significance. Mutations in three candidate genes, RELN (1 out of 10), FOXC2 (1 out of 10), and CLIP4 (2 out of 10) were found in expanded analysis using a TCGA cohort. Furthermore, siRNA-mediated target gene knockdown ( FOXC2 and CLIP4 ) and overexpression ( RELN ) assays showed that FOXC2 and CLIP4 significantly increased cell migration and viability in ccRCCs. Our study demonstrated that FOXC2 and CLIP4 activity correlates to the presence of ≤7-cm ccRCCs with synchronous metastasis and may be potential molecular predictors of synchronous metastasis of ≤7-cm ccRCCs.