Abstract 1564: Spanxa1 is a novel mediator of epithelial-mesenchymal transition in lung cancer

Abstract

Abstract SPANX (Sperm protein associated with the nucleus, X-linked) gene family express throughout spermatogenesis in agreement with a potential role in sperm development. It has been reported as a CTA (Cancer/Testis Antigen), which was highly expressed in testis and several cancers, such as gliobastoma, melanoma, testicular germ tumor and hematologic malignancies. Nevertheless, the function and molecular mechanism of SPANX involved in the cancer progression are greatly unknown. We found that the SPANX gene family member A1 (SPANXA1) was high-expressed in CL1-0, a less metastatic lung cancer cell line, and low-expressed in CL1-5, a more metastatic cell line. In vitro assays showed that the enforced expression of SPANXA1 suppressed the abilities of migration and invasion, and induced a dramatically mesenchymal - epithelial transition (EMT). In contrast, knock-down SPANXA1 could increase the cell mobility and invasiveness. To identify the underlying mechanism of SPANXA1, RNAs derived from SPANXA1-expressed cells and mock controls wrer assayed by gene expression microarrays and pathway analysis. The results showed that 1024 genes were differentially expressed in presence of SPANXA1 and six of top ten pathways belonged to EMT-related pathways analyzed by MetaCore software. The fact implied that SPANXA1 largely induces the EMT-related signalings. Quantitative RT-PCR assays were used to validate the altered expression of certain important genes induced by SPANXA1 in the identified pathways. The EMT regulating transcription factor, Slug, was decreased in SPAXA1-overexpressed cells and it also acts as a repressor for E-cadherin expression. We found that SPANXA1 mainly localized at nucleus and inhibited the formation of filopodia assayed by immunofluoresence staining. To explore the function of SPANXA1 in the nucleus, we performed Chromatin IP sequencing and the results elucidated that SPANXA1 might bind onto chromosome and regulate gene expressions. Furthermore, mouse model demonstrated that the distal metastasis was dramatically decreased in SPANXA1-overexpressed cells compared with the mock controls. These data suggest that SPANXA1 is a novel EMT modulator involved in lung cancer progression and implies the potential therapeutic role of SPANXA1 in the future. Citation Format: Shih-Chun Hsu, Yi-Jing Hsiao, Sing-Liang Yu, Ming-Shyue Lee. Spanxa1 is a novel mediator of epithelial-mesenchymal transition in lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1564. doi:10.1158/1538-7445.AM2014-1564