A Synthetic Dosage Lethal Genetic Interaction Between CKS1B and PLK1 Is Conserved in Yeast and Human Cancer Cells

Genetics. 2016 Oct;204(2):807-819. doi: 10.1534/genetics.116.190231. Epub 2016 Aug 24.

Abstract

The CKS1B gene located on chromosome 1q21 is frequently amplified in breast, lung, and liver cancers. CKS1B codes for a conserved regulatory subunit of cyclin-CDK complexes that function at multiple stages of cell cycle progression. We used a high throughput screening protocol to mimic cancer-related overexpression in a library of Saccharomyces cerevisiae mutants to identify genes whose functions become essential only when CKS1 is overexpressed, a synthetic dosage lethal (SDL) interaction. Mutations in multiple genes affecting mitotic entry and mitotic exit are highly enriched in the set of SDL interactions. The interactions between Cks1 and the mitotic entry checkpoint genes require the inhibitory activity of Swe1 on the yeast cyclin-dependent kinase (CDK), Cdc28. In addition, the SDL interactions of overexpressed CKS1 with mutations in the mitotic exit network are suppressed by modulating expression of the CDK inhibitor Sic1. Mutation of the polo-like kinase Cdc5, which functions in both the mitotic entry and mitotic exit pathways, is lethal in combination with overexpressed CKS1 Therefore we investigated the effect of targeting the human Cdc5 ortholog, PLK1, in breast cancers with various expression levels of human CKS1B Growth inhibition by PLK1 knockdown correlates with increased CKS1B expression in published tumor cell data sets, and this correlation was confirmed using shRNAs against PLK1 in tumor cell lines. In addition, we overexpressed CKS1B in multiple cell lines and found increased sensitivity to PLK1 knockdown and PLK1 drug inhibition. Finally, combined inhibition of WEE1 and PLK1 results in less apoptosis than predicted based on an additive model of the individual inhibitors, showing an epistatic interaction and confirming a prediction of the yeast data. Thus, identification of a yeast SDL interaction uncovers conserved genetic interactions that can affect human cancer cell viability.

Keywords: CKS1; cyclin-dependent kinase; polo-like kinase; synthetic dosage lethal.

MeSH terms

  • Adaptor Proteins, Signal Transducing / biosynthesis
  • Adaptor Proteins, Signal Transducing / genetics
  • CDC2-CDC28 Kinases / biosynthesis
  • CDC2-CDC28 Kinases / genetics*
  • CDC28 Protein Kinase, S cerevisiae / biosynthesis
  • CDC28 Protein Kinase, S cerevisiae / genetics
  • Cell Cycle Proteins / biosynthesis
  • Cell Cycle Proteins / genetics*
  • Cell Line, Tumor
  • Conserved Sequence / genetics
  • Gene Expression Regulation, Fungal
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Mitosis / genetics
  • Neoplasms / genetics*
  • Neoplasms / metabolism
  • Nuclear Proteins / biosynthesis
  • Nuclear Proteins / genetics*
  • Protein Interaction Mapping
  • Protein-Serine-Threonine Kinases / biosynthesis
  • Protein-Serine-Threonine Kinases / genetics*
  • Protein-Tyrosine Kinases / biosynthesis
  • Protein-Tyrosine Kinases / genetics*
  • Proto-Oncogene Proteins / biosynthesis
  • Proto-Oncogene Proteins / genetics*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / biosynthesis
  • Saccharomyces cerevisiae Proteins / genetics
  • Synthetic Lethal Mutations / genetics

Substances

  • Adaptor Proteins, Signal Transducing
  • CKS1 protein, S cerevisiae
  • CKS1B protein, human
  • Cell Cycle Proteins
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • Saccharomyces cerevisiae Proteins
  • SWE1 protein, S cerevisiae
  • Protein-Tyrosine Kinases
  • WEE1 protein, human
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1
  • CDC5 protein, S cerevisiae
  • CDC2-CDC28 Kinases
  • CDC28 Protein Kinase, S cerevisiae