TY - JOUR T1 - Deletion of <em>MTAP</em> Highly Sensitizes Osteosarcoma Cells to Methionine Restriction With Recombinant Methioninase JF - Cancer Genomics - Proteomics JO - Cancer Genomics Proteomics SP - 299 LP - 304 DO - 10.21873/cgp.20321 VL - 19 IS - 3 AU - YUSUKE AOKI AU - YASUNORI TOME AU - QINGHONG HAN AU - JUN YAMAMOTO AU - KAZUYUKI HAMADA AU - NORIYUKI MASAKI AU - YUTARO KUBOTA AU - MICHAEL BOUVET AU - KOTARO NISHIDA AU - ROBERT M. HOFFMAN Y1 - 2022/05/01 UR - http://cgp.iiarjournals.org/content/19/3/299.abstract N2 - Background/Aim: Methionine addiction is a fundamental and general hallmark of cancer cells, which require exogenous methionine, despite large amounts of methionine synthesized endogenously. 5-Methylthioadenosine phosphorylase (MTAP) plays a principal role as an enzyme in the methionine-salvage pathway, which produces methionine and adenine from methylthioadenosine and is deleted in 27.5% to 37.5% of osteosarcoma patients. Materials and Methods: Human osteosarcoma cell lines U2OS, SaOS2, MNNG/HOS (HOS) and 143B, were used. The MTAP gene was knocked out in U2OS with CRISPR/Cas9. 143B and HOS have an MTAP deletion and SaOS2 is positive for MTAP. MTAP was determined by western blotting. The four cell lines were compared for sensitivity to recombinant methioninase (rMETase). Results: MTAP-deleted osteosarcoma cell lines MNNG/HOS and 143B were significantly more sensitive to rMETase than MTAP-positive osteosarcoma cell lines U2OS and SaOS2. In addition, MTAP knock-out U2OS cells were more sensitive to rMETase than the parental MTAP-positive U2OS cells. Conclusion: The present results demonstrated that the absence of MTAP sensitizes osteosarcoma cells to methionine restriction by rMETase, a promising clinical strategy. ER -