Masanori Sakashita

Glut1 expression in T1 and T2 stage colorectal carcinomas: its relationship to clinicopathological features.

Glucose uptake is mediated by glucose transporter (Glut) proteins, which exhibit altered expression in a variety of malignant neoplasms. Glut1 expression is thought to be a potential marker for malignant transformation. The aim of the present study was to investigate the expression of Glut1 protein in colorectal adenomas, T1 and T2 stage carcinomas. Immunohistochemical detection of Glut1 protein was examined in 141 formalin-fixed and paraffin-embedded colorectal tumour specimens (57 adenomas, 84 carcinomas). The degree of Glut1 immunostaining of a specimen was graded according to the proportion of Glut1-positive cells in it; absent (positive cells are 0%), weakly positive (less than 10%), moderately positive (10-50%), and strongly positive (more than 50%). Glut1 expression was present in 18% of the adenomas with low-grade dysplasia, and in 63% of the adenomas with high-grade dysplasia. The positivity in such lesions was usually weak, but was moderate in 8% of the adenomas with high grade dysplasia. For the carcinomas, there were significant correlations between Glut1-positivity and depth of invasion (T1 45% versus T2 74%, P<0.01), histological differentiation (well 49% versus moderately to poorly 74%, P< 0.05) and morphological type (polypoid 42% versus depressed 73%, P< 0.05), if the cut-off value was set at 10% of cells. In conclusion, we clarified the relationship between Glut1 expression and clinicopathological features in T1 and T2 stage colorectal carcinomas, and our results suggested a high malignant potential of the depressed-type carcinoma.

BRAF mutation associated with dysregulation of apoptosis in human colorectal neoplasms

To understand the role of BRAF dysfunction in the carcinogenesis and progression/development of colorectal tumors, the authors investigated genetic alterations in the BRAF gene in human colorectal neoplasms as well as the effects of an RAS inhibitor in BRAF‐mutant cells. Seven colon cancer cell lines and 116 colorectal tumors (34 adenomas and 82 adenocarcinomas) were analyzed. Genetic alterations in the BRAF and K‐ras genes were examined using polymerase chain reaction‐single strand conformation polymorphism and direct sequencing analyses. The growth‐inhibitory and apoptosis‐inducing effects of the FTI‐277 RAS inhibitor in colon cancer cell lines were analyzed as well. An immunohistochemical study was also performed to investigate the correlations between the clinicopathologic parameters involved in the Ki‐67 labeling index and the number of apoptotic bodies in tumor cells. FTI‐277 did not suppress the proliferation of BRAF‐mutant cells (WiDr and TCO), but remarkably inhibited the growth of K‐ras mutant cells (LoVo). Interestingly, LoVo cells underwent apoptosis by FTI‐277 in a dose‐dependent manner, whereas WiDr cells were resistant to this agent. In tumor samples, BRAF mutations were found in 1 (3.0%) of 33 adenomas and 6 (7.2%) of 83 adenocarcinomas. No tumor exhibited mutations in both the BRAF and K‐ras genes. Neither BRAF nor K‐ras mutations correlated with the Ki‐67 labeling index immunohistochemically. However, the number of apoptotic bodies was significantly decreased in the BRAF‐mutant tumors. Mutation in the BRAF gene may contribute to colorectal carcinogenesis by upregulating the antiapoptotic role of the RAS/RAF/MEK/ERK pathway.

Effect of Helicobacter pylori-Induced Cyclooxygenase-2 on Gastric Epithelial Cell Kinetics: Implication for Gastric Carcinogenesis

Background. Cyclooxygenase (COX)‐2 induced by Helicobacter pylori is thought to enhance gastric carcinogenesis by affecting the maintenance of epithelial homeostasis.

Analysis of Helicobacter pylori vacA gene and serum antibodies to VacA in Japan.

Vacuolating cytotoxin, VacA, is one of the most important pathogenetic factors produced by Helicobacter pylori. However, it is not clear whether the diversity in disease outcome may be ascribed to variations in strain and/or to the host responses to virulence factors. In this study, we analyzed the vacA middle region sequence among 65 Japanese isolates to clarify the variation in strain and assayed antibody titer to VacA by ELISA using purified VacA to evaluate the host response to cytotoxin. The nucleotide sequence identities compared among Japanese isolates were 92.8 ± 3.56%, and compared to 88.3 ± 2.89% in tox+ strains reported in GenBank. Positive correlation was found between the antibody titers and the severity of atrophic change of the stomach. In Japan the nucleotide sequences of the vacA middle region were highly homologous and genetically closer to tox+ strains. Antibody titers and host response to cytotoxin may be associated with atrophy of the stomach.

Relationship Between Gastric Ulcer and Helicobacter pylori VacA Detected in Gastric Juice Using Bead-ELISA Method

Background. VacA is an important pathogenetic factor produced by Helicobacter pylori. VacA has often been detected in supernatants of liquid cultures or lysates of whole bacterial cells. However, no studies have ever tried to assay VacA produced in the human stomach. We applied a very sensitive and simple method, bead‐ELISA, to detect VacA in gastric juice.

Relationship of BRAF mutation, morphology, and apoptosis in early colorectal cancer

Background and aimsMany investigators have reported flat and depressed lesions as a new type of precursor of colorectal cancer. In our previous study, we determined that mutations in the BRAF gene may contribute to colorectal carcinogenesis by inhibiting apoptosis. However, the relationship among BRAF mutations, morphology and apoptosis in early colorectal cancer has not been clear. Therefore, gene alternation, morphology, and apoptosis in early colorectal cancer were investigated.Materials and methodsForty-five flat and depressed early colorectal cancer samples and 43 polypoid early colorectal cancer samples were analyzed. Mutations in the BRAF gene and the K-ras gene were examined by direct sequence analysis, and proliferative activity and induction of apoptosis were evaluated using immunohistochemical examination.Results findingsBRAF mutations were found in 5 (11.1%) of 45 flat and depressed early colorectal cancer samples. No BRAF alteration was found in polypoid early colorectal cancer samples. Mutations in the K-ras gene were detected in 13 (30.2%) of 43 polypoid early colorectal cancer samples. The rate of submucosal invasion of the samples with BRAF mutations was significantly higher than that of the samples with K-ras mutations (p < 0.05).Interpretation/conclusionsBRAF and K-ras mutations were independent factors that influenced morphology in early colorectal cancer. In this study, the relationship between BRAF mutation and apoptosis is not so clear, but BRAF mutations and inhibition in apoptosis may play an important role in the developmental process of flat and depressed early colorectal cancer.

Depressed type of inflammatory fibroid polyp of the colon

Dear Editor: A 45-year-old man, who has been suffering from recurrent diarrhea and constipation, was referred to our hospital. Colonoscopy showed a reddened depressed lesion with marginal elevation in the transverse colon, near the hepatic flexure. After the mucosal surface was sprayed with indigo carmine or crystal violet dye, magnifying endoscopy revealed a type VI pit pattern of the Kudo’s classif ication in the central depression and a type I pit pattern in the surrounding area. Endoscopic ultrasonography showed that the lesion was inf iltrating into the submucosal layer. Therefore, we considered that the lesion might be a submucosal invasive colon cancer presenting like a submucosal tumor, although the biopsy specimen taken from the lesion did not contain distinct malignant components. Since we could not deny that the lesion was a malignant tumor, laparoscopy-assisted right hemicolectomy was performed. The resected specimen measured 18×18 mm in size. Zoom stereomicroscopy of the resected specimen demonstrated a type VN pit pattern in the part of the central depression, a type VI pit pattern in the rest area of the central depression, and a type I pattern in the surrounded area. Histological examination showed an enormous proliferation in the connective tissues and infiltration of eosinophils mainly in the submucosa. There were thickwalled vessels surrounded by the proliferative f ibromuscular f ibers, resulting in onion skin appearances. These f indings were compatible with inflammatory f ibroid polyp. The term “inflammatory f ibroid polyp” was introduced by Helwig and Rainer in 1953. Its etiology, suggested to be the involvement of inflammatory mechanisms or reactive responses, remains unclear. It usually forms a pedunculated or subpedunculated submucosal tumor, with erosion or ulceration overlying the mucosa. The lesions are solitary and occur predominantly in the stomach, small intestine, and rarely in the colon. Because it is usually located in the base mucosa and submucosa, diff iculty in obtaining a histological diagnosis before treatment was reported. Magnifying colonoscopy with chromoendoscopy was reported to be useful in differentiating almost all lesions detected at colonoscopy before histological evaluation. Kudo proposed the classification of the pit patterns: types I, II, IIIL, IIIs, IV, and V. Type V is divided into two types: VI and VN. In this classification, type I corresponds to normal gland, whereas type V corresponds to cancerous gland with type VN pointing towards submucosal infiltration. In the present study, magnifying endoscopy showed a type VI pit pattern in the central depression and a type I pattern in the surrounding area. These f indings, as well as depressed type macroscopic appearance, suggested that the lesion might be a depressed colon cancer, which is thought to posses high malignant potential. Zoom stereomicroscopic f indings corresponded to the endoscopic f indings, except for a demonstration of type VN pit pattern in the part of the central depression. In this case, the area showing type VN or VI pit pattern is thought to correspond to the lesion where the surface epithelium was abraded by benign erosive inflammation. With this result, it is suggested that endoscopists should be aware, when performing endoscopic examinations, that a colonic depressed lesion presenting a type V pit pattern can be an inflammatory f ibroid polyp. Int J Colorectal Dis (2007) 22:1409 DOI 10.1007/s00384-006-0180-z

Variation in MT expression in early-stage depressed-type and polypoid-type colorectal tumours

Metallothionein (MT) expression is observed in various carcinomas, but its role is not fully understood. To clarify the clinicopathological significance of MT, 87 colorectal adenomas and 128 early-stage carcinomas were immunohistochemically analysed for MT expression. The degree of MT immunostaining of a specimen was graded according to the proportion of MT-positive cells; negative (<5%) and positive (focally 5-50%, diffusely >50%). MT expression significantly decreased with tumour development. For carcinomas, MT-positivity was significantly associated with depth of invasion (T1 60% versus T2 33%; P<0.01), vascular involvement (positive 35% versus negative 61%; P<0.01) and morphology (polypoid 62% versus depressed 26%; P<0.01). Regarding MT-positive distribution, the diffuse-positive rate in MT-positive polypoid lesions was 28%, while MT-positive depressed lesions were all diffusely stained (P<0.01). In conclusion, our results suggested that decreasing MT expression is an early event in colorectal carcinogenesis and may reflect local invasion. Furthermore, MT-positive distribution may reflect genetic differences between the polypoid and depressed-type.

What is the purpose of magnifying endoscopy for colorectal tumors

depressed types (IIc-origin lesions), adenomas not larger than 9 mm in diameter accounted for 42.1% (8/19), with the majority not being appropriate for endoscopic treatment; therefore, their diagnosis was important. Identification of depressed surface type IIIs pits, type V pits and border non-neoplastic pits by magnified endoscopic observation is extremely useful as objective information that supports diagnosis of IIc-origin lesions. The differential diagnosis of lesions with depression and the diagnosis of depth of invasion of IIc-origin lesions is shown in Figure 1. The peripheral pits of IIc origin lesions present non-neoplastic pits of type I or type II. In addition, the shape of the depressed surface changes from a star shape to an extensive shape accompanying submucosal massive invasion, and the pits in the depressed surface range from type IIIs to type V. Nearly all small depressed lesions that have IIIl pits are mild to moderate atypical adenomas, and should be identified as IIc lesions in the form of IIa+ depressions. The general relationships among depressed shapes, schematic presentations of the margins, depressed surface pits and depth of penetration of the lesions are shown in Figure 1. The depressions are star-shaped in adenomas and mucosal cancers and the pits are of type IIIs . After going through a stage of irregular Va pits, amorphous Vn pits having a extensive shape occur in submucosal massive invasive cancers. It is most important that caution is taken with respect to small, IIc-origin submucosal massive invasive cancers, as these can be life-threatening if overlooked.