Reduced mRNA expression in paraffin-embedded tissue identifies MLH1- and MSH2-deficient colorectal tumours and potential mutation carriers

Virchows Arch. 2008 Jul;453(1):9-16. doi: 10.1007/s00428-008-0637-2. Epub 2008 Jun 26.


Based on the principle of nonsense-mediated mRNA decay, we sought to identify MLH1 or MSH2-deficient colorectal tumours through relative quantification of mRNA expression with real-time PCR (RT-PCR) analysis. MLH1 and MSH2 mRNAs were almost equally expressed as defined by MLH1 to MSH2 transcript ratio (mean 1.41) in microsatellite stable, mismatch repair (MMR) proficient tumours (n = 16). A close correlation between loss of protein expression and MMR-mRNA levels was found in highly microsatellite instable (MSI-H) tumours deficient of MLH1 or MSH2. MLH1/MSH2 ratio was low in 11 sporadic and nine hereditary MLH1-deficient carcinomas (mean 0.51), whereas the ratio was high in 17 MSH2-deficient hereditary non-polyposis colorectal cancer (HNPCC) associated carcinomas (mean 6.8). Notably, in the normal tissues of HNPCC patients with MSH2 mutations, the MLH1/MSH2 transcript ratios were significantly elevated (ratio > 2.0) as compared to the ratios of normal mucosa in patients with MMR-proficient tumours (27 of 32 ratio < 2.0; p = 0.00113). Analysis of B-lymphocytes of HNPCC patients with proven MMR gene mutation confirmed these findings. In conclusion, RT-PCR allows relative quantification of MMR gene mRNA expression in formalin-fixed and paraffin-embedded tissue. Furthermore, this approach enables quantification of haploinsufficiency due to nonsense-mediated mRNA decay in normal tissue and B-lymphocytes from patients carrying MSH2 germline mutations and may be useful for identification of asymptomatic carriers of pathogenic germline mutations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / deficiency*
  • Adaptor Proteins, Signal Transducing / genetics
  • Adenoma / genetics
  • Adenoma / metabolism*
  • Adult
  • Aged
  • Aged, 80 and over
  • B-Lymphocytes / metabolism
  • Case-Control Studies
  • Colorectal Neoplasms / genetics
  • Colorectal Neoplasms / metabolism*
  • Colorectal Neoplasms, Hereditary Nonpolyposis / genetics
  • Colorectal Neoplasms, Hereditary Nonpolyposis / metabolism*
  • Gene Expression Regulation, Neoplastic
  • Genetic Predisposition to Disease / genetics
  • Genetic Testing
  • Germ-Line Mutation / genetics*
  • Humans
  • Intestinal Mucosa / metabolism
  • Middle Aged
  • MutL Protein Homolog 1
  • MutS Homolog 2 Protein / deficiency*
  • MutS Homolog 2 Protein / genetics
  • Nuclear Proteins / deficiency*
  • Nuclear Proteins / genetics
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • RNA, Neoplasm / metabolism


  • Adaptor Proteins, Signal Transducing
  • MLH1 protein, human
  • Nuclear Proteins
  • RNA, Messenger
  • RNA, Neoplasm
  • MSH2 protein, human
  • MutL Protein Homolog 1
  • MutS Homolog 2 Protein