Abstract 6075: ROS-Nrf2-ABCB1 axis accompanied with pFyn nuclear accumulation plays pivotal roles in vinorelbine resistance in non-small cell lung cancer

Abstract

Introduction: Adjuvant cisplatin-vinorelbine is standard therapy for stage II/III lung cancer. Poor survival in lung cancer can be attributed to vinorelbine resistance arising from ABC sub-family B member 1 (ABCB1) and phosphorylated Fyn (pFyn) overexpression. However, the underlying mechanism remains unclear. Nrf2 regulates the cell-protective ABC family and activates nuclear transport of Fyn. Here, we aimed to evaluate the ROS-Nrf2-ABCB1 axis in both vinorelbine-resistant (VR) cells and clinical samples. Methods: We established VR cells by exposing H1299 cells to vinorelbine, and determined intracellular reactive oxygen species (ROS) level of H1299 cells induced by vinorelbine using DCFH-DA. We evaluated the total and subcellular expression of Nrf2, ABCB1, and pFyn in VR cells and performed immunofluorescence of VR cells to confirm the precise subcellular localization of pFyn. Cell viability assay was used to examine whether the sensitivity of VR cells to vinorelbine depends on Nrf2 activity. For immunohistochemistry, we used 104 tissue samples from lung cancer patients who underwent surgery followed by cisplatin-vinorelbine treatment between December 2006 and June 2018. Results: Persistent exposure to vinorelbine induced intracellular ROS formation of H1299 cells. Both ABCB1 and Nrf2 were overexpressed in VR cells, and ABCB1 expression was dependent on Nrf2 downstream activation. Subcellular fractionation and immunofluorescence revealed nuclear accumulation of pFyn in VR cells. Decreased expression of Nrf2 restored the sensitivity of VR cells to vinorelbine. In the 104 surgical samples, Nrf2 and ABCB1 were significantly associated with disease-free survival (p = 0.029 and 0.035, respectively), and pFyn was associated with overall survival (p = 0.040). Conclusions: ROS-Nrf2 upregulates ABCB1 and accompanied by nuclear accumulation of pFyn, induces vinorelbine resistance. Our findings may facilitate drug resistance prevention strategies or new drug target development against non-small cell lung cancer. Citation Format: Shigeyuki Tamari, Toshi Menju, Toshiya Toyazaki, Hideaki Miyamoto, Naohisa Chiba, Misa Noguchi, Hiroshi Date. ROS-Nrf2-ABCB1 axis accompanied with pFyn nuclear accumulation plays pivotal roles in vinorelbine resistance in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6075.

Nrf2 signaling pathway: current status and potential therapeutic targetable role in human cancers

“…However, during OS, the cysteine residues C273 and C288 of Keap1 are modified, resulting in a conformational change of Keap1, inactivating the E3 ligase function of Keap1, making the combination of Nrf2 and Keap1 unstable, and Nrf2 escapes proteasome degradation. Then excessive Nrf2 is released from the cytoplasm to the nucleus, forms a heterodimer with sMafs, and binds to ARE, ultimately inducing expression of cytoprotective genes including antioxidant genes and phase II enzymes (26,27). Another non-classical activation pathway of Nrf2 is driven by autophagy dysfunction.…”