title: Combinatorial selection of DNA thioaptamers targeted to the HA binding domain of human CD44.
abstract: CD44, the primary receptor for hyaluronic acid, plays an important role in tumor growth and metastasis. CD44-hyaluronic acid interactions can be exploited for targeted delivery of anticancer agents specifically to cancer cells. Although various splicing variants of CD44 are expressed on the plasma membrane of cancer cells, the hyaluronic acid binding domain (HABD) is highly conserved among the CD44 splicing variants. Using a novel two-step process, we have identified monothiophosphate-modified aptamers (thioaptamers) that specifically bind to the CD44's HABD with high affinities. Binding affinities of the selected thioaptamers for the HABD were in the range of 180-295 nM, an affinity significantly higher than that of hyaluronic acid (K(d) above the micromolar range). The selected thioaptamers bound to CD44 positive human ovarian cancer cell lines (SKOV3, IGROV, and A2780) but failed to bind the CD44 negative NIH3T3 cell line. Our results indicated that thio substitution at specific positions of the DNA phosphate backbone results in specific and high-affinity binding of thioaptamers to CD44. The selected thioaptamers will be of great interest for further development as a targeting or imaging agent for the delivery of therapeutic payloads for cancer tissues.
authors.affiliation: Institute of Molecular Medicine, University of Texas Health ScienceCenter, Houston, Texas 77030, United States.
authors.forename: Anoma
authors.initials: A
authors.lastname: Somasunderam
authors.forename: Varatharasa
authors.initials: V
authors.lastname: Thiviyanathan
authors.forename: Takemi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Muniasamy
authors.initials: M
authors.lastname: Neerathilingam
authors.forename: Ganesh Lakshmana Rao
authors.initials: GL
authors.lastname: Lokesh
authors.forename: Aman
authors.initials: A
authors.lastname: Mann
authors.forename: Yang
authors.initials: Y
authors.lastname: Peng
authors.forename: Mauro
authors.initials: M
authors.lastname: Ferrari
authors.forename: Jim
authors.initials: J
authors.lastname: Klostergaard
authors.forename: David G
authors.initials: DG
authors.lastname: Gorenstein
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D014408:Biomarkers, Tumor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D041681:NIH 3T3 Cells; D009690:Nucleic Acid Conformation; D010051:Ovarian Neoplasms / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D052156:SELEX Aptamer Technique
chemical_list: D052157:Aptamers, Nucleotide; D014408:Biomarkers, Tumor; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D011994:Recombinant Proteins; D006820:Hyaluronic Acid