Abstract 1138: Aberrant expression of Plastin3 (PLS3) induces liver metastasis via enhancing the epithelial-mesenchymal transition and stemness in colorectal cancer (CRC)

Abstract

Abstract Background PLS3 gene, located on chromosome Xq23, encodes a protein 10 product (PLS3) that reduces F-actin disassembly and inhibits cofilin-mediated depolymerization of actin fibers. We previously reported that PLS3 is a novel marker for circulating tumor cells in colorectal cancer (CRC), and the high expression of PLS3 in tumor tissue is associated with a poor prognosis in patients with primary CRC. In this study, we investigated its role in functional significance for metastatic potential of CRC performing in vitro and in vivo studies. Method Four patients with surgically resected both primary CRC and liver metastasis were included in this study. Those tissues were performed with the PLS3-immunohistochemical examination (PLS3-IHC). In vitro, we cultured LOVO, DLD-1 and HCT116 which caused no liver metastasis by injecting them into the spleen of NOD/SCID mice. We stably enhanced the expression of PLS3 in the cells by transfecting the lentiviral vector expressing PLS3. The expression levels of EMT-related genes were examined with real time RT-PCR. The migration, invasion and sphere formation assay were also performed. In vivo, NOD/SCID mice were divided into two groups, which included mice transplanted with only PLS3-transfected cells and mice transplanted with PLS3-transfected and PLS3-attenuated cells together, by injecting into the spleen. We calculated the established primary splenic tumors and liver metastasis. PLS3-IHC was also performed to the sacrificed tissues. Result (1) In the PLS3-IHC of four CRC samples, all the liver metastasis tissues included stained areas, but only one primary tissue showed PLS3-staining. This was the evidence that cancer cells expressing PLS3 had metastatic properties. (2) PLS3-transfected cells had the significant decrease of E-cadherin, while the expression levels of TWIST, ZEB and vimentin were significantly higher in PLS3-transfected than PLS3-attenuated cells. PLS3-transfected LOVO significantly induced invasion and migration, compared to PLS3-attenuatd LOVO. In the sphere formation assay, the high expression of PLS3 significantly increased the proportion of sphere generating cells (DLD-1) (p<0.001). (3) In vivo, PLS3-transfected cells (DLD-1 and HCT116) significantly induced the growth of liver metastasis. The volumes of liver metastasis of mice transplanted with the mixtures were significantly smaller than those of only PLS3-transfected cells. The liver metastasis tissues showed only stained areas in both groups in PLS3-IHC. However, the established splenic tumor of mice transplanted with the mixtures displayed not only the stained but also the nonstained areas in PLS3-IHC. Conclusion In conclusion, our study suggests experimental evidence to support the functional significance of PLS3 to induce epithelial-mesenchymal trandition, stemness and liver metastasis of human CRC. Citation Format: Masami Ueda, Keishi Sugimachi, Junji Kurashige, Shotarou Sakimura, Hidenari Hirata, Ryutarou Uchi, Yuki Takano, Hiroki Ueo, Tae Matsumura, Yoshiaki Shinden, Hidetoshi Eguchi, Tomoya Sudo, Masaki Mori, Koshi Mimori. Aberrant expression of Plastin3 (PLS3) induces liver metastasis via enhancing the epithelial-mesenchymal transition and stemness in colorectal cancer (CRC). [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 1138. doi:10.1158/1538-7445.AM2014-1138