ABSTRACT
A series of azulene-based derivatives were synthesized as potent inhibitors for receptor tyrosine kinases such as FMS-like tyrosine kinase 3 (FLT-3). Systematic side chain modification of prototype 1a was carried out through SAR studies. Analogue 22 was identified from this series and found to be one of the most potent FLT-3 inhibitors, with good pharmaceutical properties, superior efficacy, and tolerability in a tumor xenograft model.
Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/therapeutic use , Azulenes/chemistry , Azulenes/therapeutic use , Leukemia, Myeloid, Acute/drug therapy , Receptor Protein-Tyrosine Kinases/antagonists & inhibitors , Animals , Antineoplastic Agents/blood , Antineoplastic Agents/pharmacology , Azulenes/blood , Azulenes/pharmacology , Cell Line, Tumor , Cell Proliferation , Humans , Mice , Mice, Inbred BALB C , Mice, Nude , Rats , Receptor Protein-Tyrosine Kinases/metabolism , fms-Like Tyrosine Kinase 3/antagonists & inhibitorsABSTRACT
The DNA-binding preferences of two oligopeptide amides, (His-Pro-Arg-Lys)(3)NH(2) (HR-12) and (Ser-Pro-Arg-Lys)(3)NH(2) (SP-12), have been examined by quantitative DNase I footprinting studies. Two different DNA fragments were investigated: a pair of 5'-(32)P-labeled duplexes from pBR322 with one or other of the complementary strands labeled and a corresponding pair of 5'-(32)P-labeled duplexes representing fragments of the latent membrane protein (LMP-1) gene from a pathogenic Epstein-Barr virus variant derived from nasopharyngeal carcinoma. The major objective was to examine molecular recognition and cooperative features associated with sequence-selective binding of synthetic peptides to the LMP-1 fragments. At various binding sites on the pBR322 fragments, Hill coefficients (n(H)) ranging from 1.9-2.2 were observed; these results indicate modest positive cooperativity between binding sites for both peptides. By contrast, unusually high values of n(H), ranging from 4.0-9.3, were observed at various binding sites on the LMP-1 fragments. Allosteric models can be constructed to interpret the observed cooperative interactions between different DNA recognition sites in the LMP-1 gene upon binding of the peptide ligands. It is noteworthy that these models feature a novel network of cooperativity interconnecting multiple DNA allosteric sites. The evidence of sequence selectivity and strong cooperativity discovered in this work may prove to be a general feature of peptide interactions with some nucleic acids.
Subject(s)
DNA, Viral/genetics , DNA, Viral/metabolism , Herpesvirus 4, Human/genetics , Herpesvirus 4, Human/metabolism , Peptides/metabolism , Viral Matrix Proteins/genetics , Viral Matrix Proteins/metabolism , Base Sequence , Chemical Phenomena , Chemistry, Physical , DNA Footprinting , Deoxyribonuclease I/metabolism , Molecular Sequence DataABSTRACT
Three peptide amides, HPRK(Py)(4)HPRK-NH(2) (PyH-12), HPRK(Py)(3)HPRK-NH(2) (PyH-11) and HPRK(Py)(2)HPRK-NH(2) (PyH-10), incorporating two HPRK motifs and various 4-amino-1-methylpyrrole-2-carboxylic acid residues (Py) were synthesized by solid-phase peptide methodology. The binding of these three peptides to a 5'-32P-labeled 158-mer DNA duplex (Watson fragment) and to a 5'-32P-labeled 135-mer DNA duplex (complementary Crick fragment) was investigated by quantitative DNase I footprinting. On the 158-mer Watson strand, the most distinctive DNase I blockages seen with all three peptides occur around positions 105-112 and 76-79, corresponding to the sequences 5'-GAGAAAAT-3' and 5'-CGGT-3', respectively. However, on the complementary Crick strand, only PyH-12 strongly discriminates the 5'-TTT-3' site around positions 108-110 whereas both PyH-11 and PyH-10 have moderate binding around positions 102-112 comprising the sequence 5'-ATTTTCTCCTT-3'. Possible bidentate and single interactions of the side-chain functions and alpha-amino protons of the peptides with DNA bases are discussed.
