Overexpression of MTH1 and OGG1 proteins in ulcerative colitis-associated carcinogenesis.

Oxidative stress, demonstrated by an accumulation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), results in DNA damage, which is normally repaired by base excision repair enzymes including 8-OHdG DNA glycosylase (OGG1) and human MutY homolog (MUTYH), in addition to nucleotide pool sanitizing enzymes including MutT Homolog 1 (MTH1). Abnormalities of this repair system are present in various cancer types. The present study aimed to elucidate the clinicopathological significance of altered expression levels of inducible nitric oxide synthase (iNOS), 8-OHdG, OGG1, MTH1 and MUTYH in ulcerative colitis (UC) and UC-associated neoplasms. Immunohistochemical staining for these markers and p53 in 23 cases of UC-associated neoplasm (Group A, 14 carcinomas and nine dysplasias), 16 cases of UC without neoplasm (Group B) and 17 cases of normal colon specimens (Group C) was performed. Mutation analyses was conducted for KRAS proto-oncogene, GTPase (K-ras), tumor protein P53 (TP53) and isocitrate dehydrogenase (NADP (+)) 1, cytosolic (IDH1) genes. Immunohistochemically, the iNOS, 8-OHdG, OGG1 and MTH1 expression levels were increased in Groups A and B compared with Group C. The OGG1 and MTH1 expression levels in Group A were also increased compared with Group B. Group A and Group B exhibited increased cytoplasmic expression and decreased nuclear expression of MUTYH compared with Group C. Mutations of K-ras and TP53 were detected in 2/21 (9.5%) and 10/22 (45.5%) cases of Group A, respectively. IDH1 mutation was not detected in any cases. These findings suggest that, as a response to oxidative damage, OGG1 and MTH1 may be upregulated in UC through an inflammatory condition that progresses to cancer formation. Persisting oxidative damage stress may play a role in the pathogenesis of UC-associated tumors.

Reduced MUTYH, MTH1, and OGG1 expression and TP53 mutation in diffuse-type adenocarcinoma of gastric cardia.

The effects of oxidative stress in adenocarcinomas of gastric cardia (AGCs) have not been fully elucidated. With a strict definition of AGC, we examined the immunohistochemical expressions of inducible nitric oxide synthase; 8-hydroxy-deoxyguanosine; and the base excision repair enzymes such as MUTYH, MTH1, and OGG1, and TP53 mutational status. Sixty-three cases of AGC were characterized by younger patient age (P = .0227) and more frequent venous invasion (P = .0106) compared with the adenocarcinomas of pylorus (APs). 8-hydroxy-deoxyguanosine was accumulated (P = .0011), whereas MUTYH (P = .0325) and OGG1 (P = .0007) were decreased, in the AGCs compared with the adjacent mucosa, but these differences were not detected in the APs. Among the AGCs, lower expressions of MUTYH (P = .0013) and MTH1 (P = .0059) were each significantly associated with diffuse-type histology. A lower expression of OGG1 was correlated with higher T-stage (P = .0011), lymphatic invasion (P = .004), and lymph node metastasis (P = .0094). In addition, the presence of TP53 mutation was associated with diffuse-type histology (P = .0153) and a lower level of MUTYH (P = .0221). The AGCs also showed a relatively high rate of a transversion-type mutation of TP53 (50%), whereas all TP53 mutations in the APs were transition type. Age 62years or older (P = .0073), diffuse-type histology (P = .0020), and TP53 mutation (P = .0066) were each associated with worse survival in the AGC patients. Our results indicate that oxidative stress accumulation and a downregulation of base excision repair enzymes may play an important role in the pathogenesis of AGC, in particular diffuse-type AGCs. Diffuse-type AGC might involve molecular pathways different from those of other subsets of gastric cancer.

A case of Crohn's disease associated with Takayasu's arteritis and Henoch-Schönlein purpura.

A 14-year-old Japanese man was diagnosed with Crohn's disease in October 2001. Four years later, the patient was referred to our institution because of neck pain, fever and asymmetrical blood pressure. Magnetic resonance angiography, computed tomography and ultrasonography revealed findings compatible with Takayasu's arteritis. In March 2006, the patient developed purpura over bilateral hands and lower extremities, arthralgia, lower abdominal pain and microhematuria. The patient was diagnosed with Henoch-Schönlein purpura. This is the first reported case of Crohn's disease associated with two types of vascular complications.