Enhancing the anticancer effect of NAMPT inhibition by targeting NAPRT in breast cancer cells

Two pathways in the synthesis of NAD, catalyzed by the key enzymes nicotinamide phosphoribosyltransferase (NAMPT) and nicotinate phosphoribosyltransferase (NAPRT), support constant survival, growth, and propagation of cancer cells. This study investigated the effect of the NAMPT inhibitor FK866 combined with 2-Hydroxynicotinic Acid (2-HNA), an inhibitor of nicotinate phosphoribosyltransferase (NAPRT), on breast cancer cell survival, apoptosis, and metastasis. MCF-7 and MDA-MB-231 breast cancer cells were cultured and treated with FK866, 2-HNA, or their combinations. Cell viability and apoptosis were evaluated using the MTT assay and Annexin V staining. The effect of inhibitors on p21, BAX, and p53 gene expression was assessed after RNA extraction and cDNA synthesis by real-time PCR using gene-specific primers. Cell migration and invasion were investigated using a scratch assay and matrigel penetration, respectively. The combination of inhibitors showed synergistic and additive effects in reducing cell viability in MCF-7 and MDA-MB-231 cells, respectively. Both inhibitors induced apoptosis and decreased invasion and migration in breast cancer cells; however, co-treatment was more effective than monotherapy. They significantly enhanced pro-apoptotic gene expression of p53, p21, and BAX, with co-treatment showing greater efficacy in both cell lines. Simultaneous inhibition of NAMPT and NAPRT reduced cell viability, induced apoptosis, and inhibited metastasis of breast cancer cells. Therefore, targeting NAPRT in addition to NAMPT may offer a more effective therapeutic strategy for breast cancer. 1. NAMPT inhibition decreased cell survival, promoted apoptosis, and suppressed the migration and invasion of breast cancer cells. 2. Concurrent NAPRT inhibition enhances the efficacy of NAMPT inhibition and lowers its effective dose.