Seneca Valley Virus 3Cpro Substrate Optimization Yields Efficient Substrates for Use in Peptide-Prodrug Therapy

PLoS One. 2015 Jun 12;10(6):e0129103. doi: 10.1371/journal.pone.0129103. eCollection 2015.

Abstract

The oncolytic picornavirus Seneca Valley Virus (SVV-001) demonstrates anti-tumor activity in models of small cell lung cancer (SCLC), but may ultimately need to be combined with cytotoxic therapies to improve responses observed in patients. Combining SVV-001 virotherapy with a peptide prodrug activated by the viral protease 3Cpro is a novel strategy that may increase the therapeutic potential of SVV-001. Using recombinant SVV-001 3Cpro, we measured cleavage kinetics of predicted SVV-001 3Cpro substrates. An efficient substrate, L/VP4 (kcat/KM = 1932 ± 183 M(-1)s(-1)), was further optimized by a P2' N→P substitution yielding L/VP4.1 (kcat/KM = 17446 ± 2203 M(-1)s(-1)). We also determined essential substrate amino acids by sequential N-terminal deletion and substitution of amino acids found in other picornavirus genera. A peptide corresponding to the L/VP4.1 substrate was selectively cleaved by SVV-001 3Cpro in vitro and was stable in human plasma. These data define an optimized peptide substrate for SVV-001 3Cpro, with direct implications for anti-cancer therapeutic development.

MeSH terms

  • 3C Viral Proteases
  • Amino Acid Sequence
  • Catalytic Domain
  • Cysteine Endopeptidases / chemistry*
  • Cysteine Endopeptidases / metabolism
  • Molecular Sequence Data
  • Picornaviridae / enzymology*
  • Substrate Specificity
  • Viral Proteins / chemistry*
  • Viral Proteins / metabolism

Substances

  • Viral Proteins
  • Cysteine Endopeptidases
  • 3C Viral Proteases