H-RYK, an unusual receptor kinase: isolation and analysis of expression in ovarian cancer

Mol Med. 1996 Mar;2(2):189-203.

Abstract

Background: Protein tyrosine kinases play an important role in cellular metabolism as key components of signal transduction pathways. They are involved in cellular growth, differentiation, and development. Receptor tyrosine kinases (EGF receptor and c-erbB2) have been shown to be important in the pathogenesis of cancer. In ovarian cancer, overexpression of c-erbB2, a type I receptor, has been correlated with an adverse effect on survival of patients.

Material and methods: An unusual receptor tyrosine kinase, H-RYK, has been isolated from a complimentary DNA library of SKOV-3, an epithelial ovarian cancer cell line, using a polymerase chain reaction-mediated approach.

Results: The primary structure of the predicted amino acid sequence of the protein shows a novel NH2-terminal region. The catalytic region shows homology to other tyrosine kinases, the closest homology being with v-sea (39%). A significant alteration in the catalytic domain is that the highly conserved "DFG" triplet in subdomain VII is altered to "DNA." The gene was mapped to chromosome 3q22. A single transcript of 3.0 kb is expressed in heart, brain, lung, placenta, liver, muscle, kidney, and pancreas by Northern analysis with maximal expression in skeletal muscle. In situ hybridization analysis on human tissues demonstrated localization of message in the epithelial and stromal compartment of tissues such as brain, lung, colon, kidney, and breast. There was minimal to absent expression of H-RYK on surface epithelium of ovaries. In benign (3) and borderline tumors of the ovary (5), there was expression in the stromal compartment. However, in malignant tumors (24) there was increased expression predominantly confined to the epithelium. Polyclonal antisera raised against synthetic peptides recognize a 100-kD protein in ovarian cancer cells and other cell lines. In contrast to other receptor tyrosine kinases, the receptor did not phosphorylate in an in vitro kinase assay.

Conclusions: The expression of this unusual receptor tyrosine kinase in epithelial ovarian cancer suggests that it may be involved in tumor progression, which needs further investigation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / enzymology*
  • Adenocarcinoma / genetics*
  • Adenocarcinoma / pathology
  • Amino Acid Sequence
  • Animals
  • Blotting, Northern
  • Blotting, Western
  • CHO Cells
  • Cell Line
  • Chromosome Mapping
  • Chromosomes, Human, Pair 3*
  • Cloning, Molecular
  • Conserved Sequence
  • Cricetinae
  • Epithelium / enzymology
  • Female
  • Gene Library
  • Humans
  • In Situ Hybridization
  • In Situ Hybridization, Fluorescence
  • Karyotyping
  • Lymphocytes / enzymology
  • Molecular Sequence Data
  • Organ Specificity
  • Ovarian Neoplasms / enzymology*
  • Ovarian Neoplasms / genetics*
  • Ovarian Neoplasms / pathology
  • Ovary / enzymology
  • Receptor Protein-Tyrosine Kinases / biosynthesis*
  • Receptor Protein-Tyrosine Kinases / isolation & purification
  • Recombinant Proteins / biosynthesis
  • Transcription, Genetic
  • Transfection
  • Tumor Cells, Cultured

Substances

  • Recombinant Proteins
  • RYK protein, human
  • Receptor Protein-Tyrosine Kinases