FXR1 facilitates axitinib resistance in clear cell renal cell carcinoma via regulating KEAP1/Nrf2 signaling pathway

Abstract

Axitinib is emerging as a first-line combination treatment drug for metastatic renal cell carcinoma, but the acquired resistance significantly bothers the treatment efficacy. This article is to investigate the impact of fragile X mental retardation autosomal homolog 1 (FXR1) and its mechanistic involvement with Kelch-like epoxy chloropropan-associated protein 1 (KEAP1)/NF-E2-related factor 2 (Nrf2) pathway on cell resistance to axitinib in clear cell renal cell carcinoma (ccRCC). Establishment of axitinib resistance cells (786-O, Caki-1, 786-O/axitinib, or Caki-1/axitinib) was made, and the cells were then transfected with sh-FXR1, or co-transfected with sh-FXR1 and sh-KEAP1. The quantitative real-time PCR (qRT-PCR) and western blotting assays were employed to measure the expression of FXR1, KEAP1, Nrf2, LC3 II/I, Beclin 1, p62, MDR-1, and MRP-1. In addition, the binding between FXR1 and KEAP1 was verified by RNA-immunoprecipitation and RNA pull-down assays, and FXR1-dependent KEAP1 mRNA degradation was determined. Herein, FXR1 was demonstrated to be overexpressed in ccRCC cells, and showed higher expression in 786-O/axitinib and Caki-1/axitinib cells. Mechanistically, FXR1 enriched KEAP1 mRNA, and pulled downed by biotinylated KEAP1 probes. Results of RNA stability assay reveled that KEAP mRNA stability was suppressed by FXR1. Furthermore, knockdown of FXR1 promoted cell apoptosis and showed a restrained feature on cell resistance to axitinib. Of note, KEAP1 knockdown suppressed cell autophagy, oxidative stress, resistance to axitinib, and promoted apoptosis, despite FXR1 was downregulated in ccRCC cells. In conclusion, FXR1 played an encouraging role in ccRCC cell resistance to axitinib by modulating KEAP/Nrf2 pathway.

Exploring the multifaceted antitumor activity of axitinib in lung carcinoids

“…The NCI-H835 cell line, which demonstrated no evidence of DNA damage and maintained a stable level of ROS over time, was able to activate a ROS resistance mechanism, probably through the Keap1/Nrf2 signaling. This mechanism, previously reported in renal cell carcinoma treated with AXI ( 45 , 66 ), involves reduced Keap1 expression, increased Nrf2 expression, and overall decreased susceptibility to AXI. The Keap1/Nrf2 pathway is critical for antioxidant responses and cellular defense mechanisms, contributing significantly to tumor progression and resistance to chemotherapy and radiotherapy in different cancer types ( 67 , 68 ).…”

Construction of a five-disulfidptosis-related-lncRNA signature for predicting prognosis and immune activity in kidney renal clear cell carcinoma

“…Silencing of the obesityassociated protein FTO enhances N6-methyladenosine (m6A)-mediated autophagic ux and inhibits tumour growth and metastasis in KIRC [39]. In addition, knockdown of KEAP1 inhibits the resistance of KIRC cells to axitinib and promotes apoptosis [40]. Wang et al constructed a 6-cuprotosis-related-gene signature to predict the prognosis of KIRC accurately [41].…”