RT Journal Article SR Electronic T1 Deletion of MTAP Highly Sensitizes Osteosarcoma Cells to Methionine Restriction With Recombinant Methioninase JF Cancer Genomics - Proteomics JO Cancer Genomics Proteomics FD International Institute of Anticancer Research SP 299 OP 304 DO 10.21873/cgp.20321 VO 19 IS 3 A1 YUSUKE AOKI A1 YASUNORI TOME A1 QINGHONG HAN A1 JUN YAMAMOTO A1 KAZUYUKI HAMADA A1 NORIYUKI MASAKI A1 YUTARO KUBOTA A1 MICHAEL BOUVET A1 KOTARO NISHIDA A1 ROBERT M. HOFFMAN YR 2022 UL http://cgp.iiarjournals.org/content/19/3/299.abstract AB 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.