International Journal of Colorectal Disease

, Volume 27, Issue 7, pp 911–919

Aberrant protein expression and frequent allelic loss of MSH3 in colorectal cancer with low-level microsatellite instability

Authors

    • Department of Surgical Research, Carl Gustav Carus KlinikumTechnical University Dresden
  • Mark Preußler
    • Department of Surgical Research, Carl Gustav Carus KlinikumTechnical University Dresden
  • Andreas Ziegler
    • Institute of Medical Biometry and StatisticsUniversity of Lübeck
  • Hans K. Schackert
    • Department of Surgical Research, Carl Gustav Carus KlinikumTechnical University Dresden
Original Article

DOI: 10.1007/s00384-011-1408-0

Cite this article as:
Plaschke, J., Preußler, M., Ziegler, A. et al. Int J Colorectal Dis (2012) 27: 911. doi:10.1007/s00384-011-1408-0

Abstract

Purpose

High level of microsatellite instability (MSI-H) in colorectal cancer (CRC) is caused by the inactivation of mismatch repair (MMR) genes; however, it is unknown for tumors with low level MSI (MSI-L). The protein complex involving MSH3 preferentially recognizes insertion/deletion loops (IDLs) of two to eight bases and di- and tetranucleotide repeats are affected in the majority of MSI-L CRC.

Methods

We selected 10 and eight MSI-L CRCs from 228 and 204 patients with sporadic and hereditary disease, respectively. The tumors were analyzed for protein expression of MSH3, MSH2, MSH6, MLH1, and PMS2, and for mutations and loss of heterozygosity (LOH) in MSH3.

Results

Four tumors showed a markedly reduced MSH3 expression, whereas all 18 tumors had normal expression of the remaining MMR proteins. Twenty-five different sequence variants were identified. None of these results in a truncated protein, though L902W represents the first constitutional missense mutation in MSH3 predicted to be functional based on conservation among mutS homologues. All variants have also been found in normal DNA of the patients and in controls. LOH intragenic to MSH3 was evident for 12 of 16 (75%) informative tumors.

Conclusions

Occurrence of sequence variants in normal DNA of the patients and in controls excludes somatic mutations and mutations specific to the CRC patient population, respectively. In contrast, the high frequency of LOH as well as the aberrant protein expression in some tumors indicates an involvement of MSH3 impairment in MSI-L CRC.

Keywords

Colorectal cancerMicrosatellite instabilityMSH3Mismatch repairProtein expression

Copyright information

© Springer-Verlag 2012