[Metabolic signatures of niraparib-resistant ovarian cancer cells based on non-target metabolomics].

Objective

To establish a niraparib-resistant ovarian cancer cell line and preliminarily explore its biological characteristics and metabolic signatures.

Methods

(1) Using ovarian adenocarcinoma cell line A2780 as parental cells, the niraparib-resistant cell line A2780-NiraR was established by the method of concentration gradient increased induction, and its morphological characteristics were observed using inverted phase-contrast microscope. The half-inhibitory concentration (IC50) of niraparib was determined by cytotoxicity assay. (2) Cell proliferation was determined by cell count kit-8 (CCK-8) assay and direct cell counting assay, cell cycle distribution was analyzed by flow cytometry. (3) The differential metabolites between A2780 and A2780-NiraR cells were detected by non-target metabolomics based on ultra-high performance liquid chromatography-high resolution mass spectrometry (UPLC/HRMS). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was conducted on the above differential metabolites to explore related metabolic pathways.

Results

(1) Compared with the parental A2780 cells, A2780-NiraR cells exhibited predominantly short-spindle or oval morphology with reduced cellular projections and indistinct cell borders. The IC50 values of niraparib were 3.17 and 26.19 μmol/L against A2780 cells and A2780-NiraR cells, respectively (F=98.50, P<0.001). (2) A2780-NiraR cells had a slower proliferation rate compared with A2780 cells (F=146.80, P<0.001). The doubling time of A2780-NiraR cells [(37.5±1.9) hours] was significantly longer than that of A2780 cells [(14.5±1.0) hours; t=10.50, P<0.001]. Compared with the parental A2780 cells, A2780-NiraR cells had a significantly lower S phase fraction [(44.5±0.7)% in A2780 cells, (30.2±2.9)% in A2780-NiraR cells; t=4.78, P<0.001] and higher G0/G1 phase fraction [(35.4±1.2)% in A2780 cells, (52.2±3.1)% in A2780-NiraR cells; t=5.10, P<0.001]. (3) The metabolites of A2780 and A2780-NiraR cells were analyzed by non-target metabolomics. Forty-four differential metabolites between A2780 and A2780-NiraR cells were screened using the orthogonal partial least squares-discriminant analysis (OPLS-DA) model, the majority of which were significantly increased, such as pyrrolidone carboxylic acid, L-lysine and 1-pyrroline-4-hydroxy-2-carboxylate. Pathway enrichment analysis indicated that the arginine metabolism, purine metabolism, and pyrimidine metabolism were the most significantly enriched pathways.

Conclusion

A2780-NiraR cells have acquired a stable niraparib resistance phenotype, and metabolic pathways including arginine metabolism may serve as potential therapeutic targets for enhancing niraparib efficacy in ovarian cancer.