Abstract 4343: Effects of the co-expression of RANTES and IL-6 on the transformed phenotype of breast cancer cells

Field: Medicine (Health Sciences)

Abstract Introduction: Cells of the tumor microenvironment play an important role in the progression of breast cancer through their interaction with cancer cells. In this regard, mesenchymal stem cells greatly increased the metastatic potential of breast cancer cells through the secretion of the chemokine CCL5/RANTES. In addition, we demonstrated that breast cancer cells migrate in response to either recombinant RANTES or interleukin-6 (IL-6). Starting from this observation, we analyzed whether the co-expression of RANTES and IL-6 induced a more aggressive phenotype in breast cancer cells. Methods: MCF-7 and MDA-MB-231 breast cancer cells were transfected with expression vectors coding for human RANTES and IL-6. XMAP Bio-Plex Cytokine arrays were employed to measure the levels of secreted RANTES and IL-6. To evaluate the proliferation of stable clones, anchorage-independent growth assays were used. Migration and invasion were analyzed using commercially available kits. Tumor growth in vivo was determined after injection of transfected cells in the mammary fat pad of nude mice. Results: MCF-7 and MDA-MB-231 clones that stably overexpressed RANTES and/or IL-6 were isolated after selection with appropriate antibiotics. Stable transfectants produced higher levels of secreted RANTES and IL-6 than control cells trasfected with mock vectors. To evaluate whether RANTES and IL-6 induced a more aggressive phenotype in breast cancer cells, we analyzed the proliferation, migration and invasive ability of stable clones. MCF-7 cells co-expressing RANTES and IL-6 had a greater ability to form colonies in soft agar, compared to cells overexpressing RANTES or IL-6. In addition, both MCF-7 and MDA-MB-231 clones co-expressing RANTES+IL6 showed a significantly higher ability to migrate through a fibronectin-coated and to invade through a matrigel-coated matrix. The analysis of phosphorylated ERK1/2, AKT and STAT3 signal transduction proteins revealed that in cells overexpressing both RANTES and IL-6 more signaling pathways are simultaneously activated as compared with cells overexpressing a single factor. Finally, MCF-7 cells overexpressing RANTES+IL6 showed a significant increase in in vivo tumor growth when clones were injected in the mammary fat pad of nude mice. Conclusions: Taken together, our data suggest that the simultaneous expression of IL-6 and RANTES produce a more aggressive phenotype in breast cancer cells. This observation might be useful for the identification of potential targets for novel therapeutic strategies aimed to prevent breast cancer progression through the blockade of the tumor-stroma interaction. Note: This abstract was not presented at the meeting. Citation Format: Marianna Gallo, Daniela Frezzetti, Nicola Normanno, Antonella De Luca. Effects of the co-expression of RANTES and IL-6 on the transformed phenotype of breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4343. doi:10.1158/1538-7445.AM2017-4343