KLF5 modulates NTSR1 to facilitate fatty acid oxidation and repress anoikis in gastric cancer

Abstract

Neurotensin receptor 1 (NTSR1) is linked with poor prognosis in many tumors, including gastric cancer (GC). However, the exact mechanism by which NTSR1 affects GC anoikis in GC is uncharted. Therefore, we aimed to elucidate the specific mechanism by which NTSR1 participates in GC anoikis. We used qRT-PCR (quantitative reverse transcription polymerase chain reaction) to assess the levels of NTSR1 and its upstream transcription factor KLF5 (a key member of the Kruppel-like factor family) in GC tissues, and bioinformatics to analyze the signaling pathways in which NTSR1 participated. A CCK-8 kit was applied to detect the viability of GC cells under different treatments. Dual luciferase and chromatin immunoprecipitation experiments verified the binding relationship between KLF5 and NTSR1. The rate of fatty acid oxidation (FAO) was analyzed using a cell metabolism meter, and FAO-related protein expression was detected using western blot (WB). Anoikis of cells in each treatment group was detected using flow cytometry, an anoikis apoptosis kit and WB. Knocking down NTSR1 repressed the viability of GC cells, and elevated the anoikis rate and the expression of cleaved PARP and cleaved caspase-3 in GC cells. Moreover, high expression of NTSR1 upregulated the expression of CPT1 protein in FAO and increased FAO levels, thereby suppressing the occurrence of anoikis in GC cells. Addition of the FAO inhibitor etomoxir reversed the above trends. Additionally, KLF5 was highly expressed in GC. Finally, KLF5 knockdown was found to overcome the repression of the FAO pathway and to facilitate anoikis in GC cells that were overexpressing NTSR1. In summary, KLF5 affects anoikis in GC cells by targeting NTSR1 to modulate the FAO pathway. Therefore, blocking the FAO pathway regulated by the KLF5/NTSR1 axis may become a new strategy for the treatment of GC.