title: CD40 ligand induced cytotoxicity in carcinoma cells is enhanced by inhibition of metalloproteinase cleavage and delivery via a conditionally-replicating adenovirus.
abstract: BACKGROUND
  CD40 and its ligand (CD40L) play a critical role in co-ordinating immune responses. CD40 is also expressed in lymphoid malignancies and a number of carcinomas. In carcinoma cells the physiological outcome of CD40 ligation depends on the level of receptor engagement with low levels promoting cell survival and high levels inducing cell death. The most profound induction of cell death in carcinoma cells is induced by membrane-bound rather than recombinant soluble CD40L, but like other TNF family ligands, it is cleaved from the membrane by matrix metalloproteinases.
  
  
  RESULTS
  We have generated a replication-deficient adenovirus expressing a mutant CD40L that is resistant to metalloproteinase cleavage such that ligand expression is retained at the cell membrane. Here we show that the mutated, cleavage-resistant form of CD40L is a more potent inducer of apoptosis than wild-type ligand in CD40-positive carcinoma cell lines. Since transgene expression via replication-deficient adenovirus vectors in vivo is low, we have also engineered a conditionally replicating E1A-CR2 deleted adenovirus to express mutant CD40L, resulting in significant amplification of ligand expression and consequent enhancement of its therapeutic effect.
  
  
  CONCLUSIONS
  Combined with numerous studies demonstrating its immunotherapeutic potential, these data provide a strong rationale for the exploitation of the CD40-CD40L pathway for the treatment of solid tumours.
authors.affiliation: Cancer Research UK Institute for Cancer Studies, School of Cancer Sciences, University of Birmingham, UK.
authors.forename: Taha
authors.initials: T
authors.lastname: Elmetwali
authors.forename: Peter F
authors.initials: PF
authors.lastname: Searle
authors.forename: Iain
authors.initials: I
authors.lastname: McNeish
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Young
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Palmer
mesh_terms: D000256:Adenoviridae / Q000187:drug effects / Q000502:physiology*; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects; D023201:CD40 Ligand / Q000737:chemistry / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D006801:Humans; D045726:Metalloproteases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009369:Neoplasms / Q000473:pathology*; D011480:Protease Inhibitors / Q000494:pharmacology; D014779:Virus Replication / Q000187:drug effects / Q000502:physiology*
chemical_list: D011480:Protease Inhibitors; D023201:CD40 Ligand; D045726:Metalloproteases