[Is immunohistochemistry for MLH1 and MSH2 proteins a useful method for detection of microsatellite instability in sporadic colorectal cancer?].
OBJECTIVE
In order to identify microsatellite instability (MSI), the test based on the polymerase chain reaction (PCR) can be used. However, PCR is not routinely performed in all hospital laboratories. Recently, immunohistochemistry (IHC) for MLH1 and MSH2 proteins has been reported as a rapid and useful method for MSI. However, the efficacy of IHC in the detection of the MSI has not been well established. The aim of this study was to evaluate the usefulness of IHC in the detection of the MSI by comparing it with the test results using PCR in colorectal cancer (CRC).


METHODS
Paraffin-embedded normal and tumor tissues from seventy-five patients who underwent surgical resection of CRC were used. Abnormal expression of MLH1 and MSH2 protein was determined by IHC using MLH1 and MSH2 antibodies. Normal and tumor DNAs were obtained from thirty CRC tissues that showed abnormal expression of MLH1 and MSH2 proteins by IHC. The MSI status was confirmed by PCR using five markers.


RESULTS
Thirty tumors showed abnormal expression of MLH1 and MSH2 proteins by IHC, but only three tumors out of them were confirmed to have MSI by PCR.


CONCLUSIONS
This result suggests that IHC with MLH1 and MSH2 antibodies does not seem to be a useful method to identify MSI in CRC, therefore PCR is required for detection of the MSI.
Do
Jae Hyuk
JH
Department of Internal Medicine, ChungAng University School of Medicine, Yongsan Hospital, 65-207 Hankangro 3-ga, Yongsan-gu, Seoul, 140-757, Korea.
Chang
Sae Kyung
SK
Ahnn
Ji Yong
JY
Cha
Bong Ki
BK
Cheong
Seung Moon
SM
Kim
Dae Won
DW
Cheong
Hey Ryung
HR
Kim
Hyung Joon
HJ
Kim
Jae Gyu
JG
Lee
Tae Jin
TJ
Park
Eon Sub
ES
Park
Sill Moo
SM
D048868:Adaptor Proteins, Signal Transducing; D000368:Aged; D002352:Carrier Proteins; D015179:Colorectal Neoplasms / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000032:analysis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009363:Neoplasm Proteins / Q000032:analysis*; D009687:Nuclear Proteins; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000032:analysis*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein