The Saccharomyces cerevisiae orthologue of the human protein phosphatase 4 core regulatory subunit R2 confers resistance to the anticancer drug cisplatin

• Published in: The FEBS journal Vol. 273; no. 14; pp. 3322 - 3334
• Main Authors: Hastie, C. James, Vázquez‐Martin, Cristina, Philp, Amanda, Stark, Michael J. R., Cohen, Patricia T. W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.2006
• Subjects: Amino Acid Sequence; Animals; Antineoplastic Agents - pharmacology; Antineoplastic Agents, Alkylating - pharmacology; Benomyl - pharmacology; Binding Sites; Cancer; Cell Cycle Proteins - drug effects; Cell Line; Cells, Cultured; Checkpoint Kinase 2; cisplatin; Cisplatin - pharmacology; Dose-Response Relationship, Drug; Drosophila - cytology; Drosophila melanogaster; Drug resistance; Drug Resistance, Neoplasm - genetics; Enzymes; Homozygote; Humans; Methyl Methanesulfonate - pharmacology; Microbial Sensitivity Tests; Molecular Sequence Data; Open Reading Frames; Phosphoprotein Phosphatases - chemistry; Phosphoprotein Phosphatases - classification; Phosphoprotein Phosphatases - genetics; Phosphoprotein Phosphatases - isolation & purification; Phosphoprotein Phosphatases - metabolism; platinum‐based anticancer drugs; Pph3; Protein Binding; protein phosphatase 4; Protein Serine-Threonine Kinases - drug effects; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; Proteins; Psy4; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - drug effects; Saccharomyces cerevisiae Proteins - metabolism; Sequence Homology, Amino Acid; Yeast
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2006.05336.x

The anticancer agents cisplatin and oxaliplatin are widely used in the treatment of human neoplasias. A genome‐wide screen in Saccharomyces cerevisiae previously identified PPH3 and PSY2 among the top 20 genes conferring resistance to these anticancer agents. The mammalian orthologue of Pph3p is the protein serine/threonine phosphatase Ppp4c, which is found in high molecular mass complexes bound to a regulatory subunit R2. We show here that the putative S. cerevisiae orthologue of R2, which is encoded by ORF YBL046w, binds to Pph3p and exhibits the same unusually high asymmetry as mammalian R2. Despite the essential function of Ppp4c–R2 in microtubule‐related processes at centrosomes in higher eukaryotes, S. cerevisiae diploid strains with homozygous deletion of YBL046w and two or one functional copies of the TUB2 gene were viable and no more sensitive to microtubule‐depolymerizing drugs than the control strain. The protein encoded by YBL046w exhibited a predominantly nuclear localization. These studies suggest that the centrosomal function of Ppp4c–R2 is not required or may be performed by a different phosphatase in yeast. Homozygous diploid deletion strains of S. cerevisiae, pph3Δ, ybl046wΔ and psy2Δ, were all more sensitive to cisplatin than the control strain. The YBL046w gene therefore confers resistance to cisplatin and was termed PSY4 (platinum sensitivity 4). Ppp4c, R2 and the putative orthologue of Psy2p (termed R3) are shown here to form a complex in Drosophila melanogaster and mammalian cells. By comparison with the yeast system, this complex may confer resistance to cisplatin in higher eukaryotes.