Abstract 2807: Cancer stem cells enhance invasion of cancer cells via CCL-5-mediated epithelial-mesenchymal transition.
Authors: Bo Zhu, Haixia Long
Journal: Cancer Research (2013)

Abstract Background: Growing evidences have demonstrated that the tumor microenvironment comprises a variety of stromal cells that play a crucial role in tumor progression and metastasis. Among them, cancer stem cells (CSCs) were a subset of the bulk tumor responsible for tumor development and metastasis. However, whether CSCs in cancer microenvironment could influence the characteristics of cancer cells has not been addressed. The present study is aimed to investigate the contribution of CSCs in ovarian cancer cell metastasis and signaling pathway that mediate CSCs effects. Material and methods: Ovarian CSCs were obtained from A2780 and SKOV3 cell lines by serum-free culture selection. Transwell and wound-healing assay were used to determine the ability of invasion and migration of cancer cells with or without CSCs in the lower wells. We next examined EMT markers at both protein and mRNA levels by real-time PCR, Western blotting and immunoﬂuorescence analysis in the ovarian cancer cells before and after co-cultured with CSCs, or treated with rhCCL5; or blocking with control IgG, anti-CCL5, CCR1, CCR3, CCR5 antibody and NF-kappa B inhibitor. ELISA, Immunoﬂuorescence and Western blotting were used to determine whether NF-κB activation was involved in CCL5-mediated EMT of cancer cells by CSCs. We further conducted an immunohistochemical staining of CCL5, CCR1, CCR3 and CCR5 in benign ovarian tissues, primary or invasive ovarian carcinoma tissues. Results: We found that co-culture of A2780 and SKOV3 cells with CSCs significantly promoted the migration and invasion of cancer cells in a cell number-dependent manner. Furthermore, in A2780 and SKOV3 cells, co-cultured with CSCs induced an EMT phenotype from cabblestone-like to spindle-like morphology, accompanied by down-regulated epithelial markers (E-cadherin) and up-regulated mesenchymal markers (Snail, vimentin, N-cadherin). We further found that addition of anti-CCL5 or its receptors (CCR1, CCR3, CCR5) antibody to the co-culture system of CSCs with A2780 or SKOV3 cells showed an inhibition of the invasion and migration, and EMT promoted by CSCs. Furthermore, treatment of A2780 and SKOV3 cells with recombinant CCL5 for 24 hours enhanced the invasion of cancer cells, and induced EMT in a dose-dependent manner. We also found that the expression of CCL5 and its receptors in invasive ovarian carcinoma were much stronger compared to primary ovarian carcinoma. Interestingly, we found the activity of NF-kappa B also increased in A2780 and SKOV3 cells when co-cultured with CSCs or treatment with rhCCL5; Moreover, NF-kappa B inhibitor significantly decreased the migration and invasion of cancer cells exerted by CSCs. Conclusions: Our results suggest that CCL5 derived from CSCs plays a critical role in promoting ovarian cancer progression by induction of EMT via the activation of NF-kappa B. Citation Format: Bo Zhu, Haixia Long. Cancer stem cells enhance invasion of cancer cells via CCL-5-mediated epithelial-mesenchymal transition. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2807. doi:10.1158/1538-7445.AM2013-2807 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.