Abstract 706: Chemotherapy and inflammation show a p65- and STAT3-dependent pro-tumorigenic potential

Abstract

Tumor microenvironment (TME) plays a critical role in cancer progression and response to therapies. Therapeutic intervention strategies for cancer treatment can induce inflammation, resulting in changes in the TME. To investigate the response of cancer cells to chemotherapy in the context of an inflammatory microenvironment, we studied the effects driven by the chemotherapeutic drug doxorubicin, and the inflammatory cytokine TNFá. We previously demonstrated using expression microarrays experiments (validated also through qPCR) that the Doxo+TNFá combined treatment determined a strong up-regulation of migration-related genes as well as increased motility in breast cancer cells (MCF7). We confirmed the synergistic activation of a group of 6 different genes upon Doxo+TNFá combined treatment in different cell line models coming from different cancer types (A549-lung, U2OS-osteosarcoma). Moreover, we demonstrated that this effect was only partially p53-depenedent but strongly Doxo-dependent using p53 mutated MDA-MB-231 breast cancer cells or knocking-out p53 in MCF7 or U2OS cells through the cutting edge technology CRISPR/Cas9. We also demonstrated that the combined Doxo+TNFá treatment was not only able to disrupt the 3D architecture of mammary acini observed with MCF10A primary cells grown within matrigel, but also to stimulate the tube-forming potential of Human Umbilical Vein Endothelial Cells (HUVEC). Furthermore, a signature of Doxo+TNFá highly synergistic genes (DT-29) was shown to exhibit prognostic value for luminal breast cancer patients, with adverse outcome correlating with higher relative expression (based on Kaplan-Meier plotter tool). We further used available experimental data sets (RNA-seq measurements from Gene Expression Omnibus) both from breast cancer cell lines (luminal-like vs basal-like breast cancer cells) and breast cancer patients (ER positive vs Triple Negative Breast Cancer, TNBC and vs healthy adjacent tissues). The expression of DT-29 gene signature was analyzed and compared among the different groups of samples. The most statistically relevant genes differentially expressed among the different groups were involved in the STAT3-driven pathways and were prevalently highly expressed in TNBC patients and cell lines. In order to demonstrate a STAT3-dependent regulation of up-regulated genes upon Doxo+TNFá combined treatment, we pharmacologically inhibited STAT3 using Stattic or we knocked-out STAT3 using CRISPR/Cas9 in MCF7, MDA-MB-231 and U2OS cells. Results demonstrated a STAT3-dependent up-regulation for some of the selected genes and STAT3 inhibition resulted also in a reduced migration potential particularly in U2OS cells. We propose that the combined treatment with Doxo+TNFá can lead to the activation of specific gene expression programs that may impact on cancer phenotypes and potentially modify the efficacy of cancer therapy. Citation Format: Federica Alessandrini, Laura Pezze, Francesca Precazzini, Silvia D’Ambrosi, Dennis Pedri, Lia Pinto, Yari Ciribilli. Chemotherapy and inflammation show a p65- and STAT3-dependent pro-tumorigenic potential. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 706.