Expression of DNA repair protein: MYH, NTH1, and MTH1 in colorectal cancer.
OBJECTIVE
Oxidative stress is one of the causative agents of carcinogenesis. The DNA repair protein: MYH, NTH1 and MTH1 eliminate the oxidative DNA damage. In various tumors, overexpression of MTH1 has been reported. This is the first report demonstrating the expression of those proteins in colorectal cancer.


METHODS
We investigated the expression of MYH, NTH1 and MTH1 by immunohistochemical typing methods in colorectal cancers obtained from consecutive patients undergoing surgery at the University of Tokyo hospital.


RESULTS
High MYH immunoreactivity was detected in 57% of cases (46/81), which showed a significant correlation with the depth of tumor (p=0.04). Cytoplasmic expression of NTH1 was detected in 35% of cases (28/81), which showed a significant correlation with lymph node metastasis (p=0.001), histological grade according to the Dukes' Classification (p=0.005), and disease-free survival (p=0.04). High MTH1 immunoreactivity was detected in 84% of cases (68/81), which showed a significant correlation with tumor location (p=0.04).


CONCLUSIONS
The expression pattern of DNA repair protein for oxidative DNA damage showed a significant correlation with aggressive features of colorectal cancer such as the depth of tumor, and lymph node metastasis, as well as with Dukes' classification and disease-free survival.
Koketsu
Shinichiro
S
Department of Surgical Oncology, Graduate School of Medicine, University of Tokyo, Japan. koketsu-tky@umin.ac.jp
Watanabe
Toshiaki
T
Nagawa
Hirokazu
H
D015179:Colorectal Neoplasms / Q000737:chemistry / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D045647:DNA Glycosylases / Q000096:biosynthesis*; D045643:DNA Repair Enzymes / Q000096:biosynthesis*; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010744:Phosphoric Monoester Hydrolases / Q000096:biosynthesis*
D043224:Deoxyribonuclease (Pyrimidine Dimer); C468347:NTHL1 protein, human; D010744:Phosphoric Monoester Hydrolases; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase; C078207:8-oxodGTPase; D045643:DNA Repair Enzymes