Abstract A48: Apoptosis induced by NFAT1 in transformed cells is dependent on TNF-alpha sensitivity

Abstract

Abstract The family of nuclear factor of activated T cells (NFAT) consists of four calcium-regulated members. NFAT proteins are largely known for playing a major role in gene expression regulation during T-cell activation. Nevertheless, NFAT members are also expressed in other cell types, such as adipocytes, neurons, cardiac muscle, breast, cartilage, pancreatic, and endothelial cells. Regulation of NFAT activity is essential to maintain homeostasis. Deregulation of NFAT is associated with many pathologies, such as cancer, neurodegenerative, and heart disorders. In cancer, different NFAT proteins were described for being involved in tumorigenesis and progression of the disease. However, some questions remain unanswered. NFAT1 deficient mice are more susceptible to chemical-induced carcinogenesis and develop spontaneous B-cell lymphomas and chondrosarcomas. Corroborating this data, NFAT1 is able to induce cell death in different cell types by the upregulation of apoptosis-inducing genes. Together, these studies suggest NFAT1 may act as tumor suppressor gene by inducing cell death. However, other studies point in the opposite direction by showing NFAT1's role in promoting migration and invasion of tumor cells in different types of cancer, contributing to the progression of the disease. Therefore, we aim to elucidate if NFAT1 is able to induce cell death in tumor cell lines to understand in which cell context NFAT1 may act as a tumor suppressor. Here, we show in our previous model that overexpression of constitutively active form of NFAT1 (NFAT1-ca) induces cell death in NIH3T3 H-RasV12 transformed fibroblasts. Gene expression analysis revealed that NFAT1-ca overexpression led to massive increase in TNF-alpha expression in these transformed fibroblasts. Deletion of Tnf gene, by CRISPR/Cas9 approach, turned NIH3T3 cells resistant to cell death induced by NFAT1-ca. Next, we addressed whether melanoma (B16F10), colon (HCT116, LoVo), and breast (4T1, MDA-MB-231) cancer cells are susceptible to apoptosis induced by NFAT1-ca. Both colon cancer cells underwent apoptosis when overexpressing NFAT1-ca. On the other hand, melanoma and breast cancer cells were not susceptible to cell death induced by NFAT1-ca. TNF-alpha expression was upregulated in melanoma and colon cancer cells and remains to be evaluated in breast cancer cells. Some studies show that B16F10 and MDA-MB-231 are resistant to TNF-alpha-induced apoptosis while HCT116 cells are susceptible. So far, our data suggest that NFAT1 may induce cell death mostly by TNF-alpha induction. Therefore, it is possible that cancer cells resistant to TNF-alpha are also resistant to NFAT1-ca. Financial support: FAPERJ, CNPq, Ministry of Health – Brazil. Citation Format: Douglas V. Faget, João P. B. Viola. Apoptosis induced by NFAT1 in transformed cells is dependent on TNF-alpha sensitivity [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A48.