Epigenetic Inactivation of a RAS Association Domain Family Protein From the Lung Tumour Suppressor Locus 3p21.3

Nat Genet. 2000 Jul;25(3):315-9. doi: 10.1038/77083.

Abstract

Allelic loss at the short arm of chromosome 3 is one of the most common and earliest events in the pathogenesis of lung cancer, and is observed in more than 90% of small-cell lung cancers (SCLCs) and in 50-80% of non-small-cell lung cancers (NSCLCs). Frequent and early loss of heterozygosity and the presence of homozygous deletions suggested a critical role of the region 3p21.3 in tumorigenesis and a region of common homozygous deletion in 3p21.3 was narrowed to 120 kb (ref. 5). Several putative tumour-suppressor genes located at 3p21 have been characterized, but none of these genes appear to be altered in lung cancer. Here we describe the cloning and characterization of a human RAS effector homologue (RASSF1) located in the 120-kb region of minimal homozygous deletion. We identified three transcripts, A, B and C, derived from alternative splicing and promoter usage. The major transcripts A and C were expressed in all normal tissues. Transcript A was missing in all SCLC cell lines analysed and in several other cancer cell lines. Loss of expression was correlated with methylation of the CpG-island promoter sequence of RASSF1A. The promoter was highly methylated in 24 of 60 (40%) primary lung tumours, and 4 of 41 tumours analysed carried missense mutations. Re-expression of transcript A in lung carcinoma cells reduced colony formation, suppressed anchorage-independent growth and inhibited tumour formation in nude mice. These characteristics indicate a potential role for RASSF1A as a lung tumour suppressor gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-Methylcytosine
  • Alternative Splicing
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Carcinoma, Non-Small-Cell Lung / genetics*
  • Carcinoma, Small Cell / genetics*
  • Chromosomes, Human, Pair 3*
  • CpG Islands
  • Cytosine / analogs & derivatives
  • Cytosine / metabolism
  • DNA Methylation*
  • DNA, Complementary
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation, Neoplastic*
  • Genes, Tumor Suppressor*
  • HT29 Cells
  • HeLa Cells
  • Humans
  • Lung Neoplasms / genetics*
  • Mice
  • Molecular Sequence Data
  • Mutation, Missense
  • Neoplasm Proteins / genetics*
  • Neoplasm Proteins / metabolism
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • Rats
  • Sp1 Transcription Factor / metabolism
  • Tumor Suppressor Proteins*
  • Xeroderma Pigmentosum Group A Protein
  • ral Guanine Nucleotide Exchange Factor / metabolism*
  • ras Proteins / metabolism*

Substances

  • DNA, Complementary
  • DNA-Binding Proteins
  • Neoplasm Proteins
  • RASSF1 protein, human
  • RNA-Binding Proteins
  • Sp1 Transcription Factor
  • Tumor Suppressor Proteins
  • XPA protein, human
  • Xeroderma Pigmentosum Group A Protein
  • Xpa protein, mouse
  • ral Guanine Nucleotide Exchange Factor
  • 5-Methylcytosine
  • Cytosine
  • ras Proteins

Associated data

  • GENBANK/AC002455
  • GENBANK/AC002481
  • GENBANK/AF132675
  • GENBANK/AF132676
  • GENBANK/AF132677