Reiko Makino

Molecular differences between sporadic serrated and conventional colorectal adenomas.

Purpose: The purpose is to compare the molecular characteristics of serrated adenomas (SAs) with those of conventional adenomas (CADs) and hyperplastic polyps (HPs). Experimental Design: We evaluated the proliferative activity and molecular alterations in 47 SAs (25 pure-type and 22 mixed-type), 71 CADs, and 23 HPs. Results: The proliferative activity of SAs, as evaluated by Ki-67 expression, was intermediate between CADs and HPs. There was no significant difference in the incidence of KRAS or p53 mutations between the three histological groups. In the microsatellite instability (MSI) analysis, 21% of SAs (9 of 43) showed MSI at two or more loci (MSI-H); corresponding values were 5% of CADs (3 of 64) and 8% of HPs (1 of 13; SAs versus CADs, P = 0.0125). MSI-H was more likely to be found in pure-type SAs (36%; 8 of 22) than in mixed-type SAs (5%; 1 of 21; P = 0.0212). Loss of hMLH-1 expression was found in 8 of 9 SAs with MSI-H. The incidence of BRAF or KRAS mutations was 36 and 15% of SAs, respectively; the combined incidence of BRAF and KRAS mutations occurred in 49% of SAs. However, there was no significant difference in the incidence of BRAF or KRAS mutations between SAs with and without MSI-H. Conclusions: Genetic instability is more frequently implicated in the tumorigenesis of SAs, especially pure-type SAs, than in that of CADs. In contrast, activation of the Ras/Raf/MEK/MAP kinase cascade by BRAF or KRAS mutation, independently of the genetic instability, may be associated with the progression of about half of SAs.

Gastric and Intestinal Phenotypic Marker Expression in Early Differentiated-Type Tumors of the Stomach: Clinicopathologic Significance and Genetic Background

Purpose: Gastric and intestinal phenotypic cell markers are expressed in gastric carcinomas, irrespective of their histologic type. In the present study, we determined the clinicopathologic significance of phenotypic marker expression in early-stage gastric differentiated-type tumors and the association between marker expression and genetic alterations. Experimental Design: Phenotypic marker expression was determined by examining the expressions of human gastric mucin (HGM), MUC6, MUC2, and CD10 in 63 gastric adenomas, 133 early differentiated-type carcinomas, and 24 follow-up cases with gastric adenoma. Tumors were classified into gastric, gastric and intestinal mixed, or intestinal phenotypes according to the immunopositivity of the above markers. The presence of mutations in APC, K-ras, and p53 and the microsatellite instability status were also determined in all tumors. Results: The expressions of HGM and MUC6, representing gastric or gastric and intestinal mixed phenotypes, were significantly associated with high-grade atypia in the 63 gastric adenomas. Among the 133 early differentiated-type carcinomas, HGM expression was significantly associated with mixed-type (with an undifferentiated-type component) tumors and lymph node metastasis. MUC2 expression was inversely associated with submucosal invasion. A multivariate analysis revealed that gastric adenomas were significantly associated with the intestinal phenotype and were inversely associated with p53 mutation compared with early differentiated-type carcinomas. Among all 196 tumors, APC mutation was significantly associated with CD10 expression and the intestinal phenotype and was inversely associated with the expressions of HGM and MUC6. The microsatellite instability status was significantly associated with MUC6 expression. Malignant transformation from gastric adenoma to carcinoma was shown in 5 of the 24 follow-up cases of gastric adenoma. The malignant transformation was significantly associated with the gastric and intestinal mixed phenotype and was inversely associated with APC mutation. No malignant transformation was found in intestinal phenotype gastric adenomas with APC mutation. Conclusions: Our present findings show that phenotypic marker expression is associated with tumor aggressiveness during the early stage of gastric differentiated-type tumors. Differences in the biological behavior of tumors with different phenotypes may result from differences in the genetic backgrounds during the incipient phase of gastric tumorigenesis.

p53 mutations and overexpression affect prognosis of ovarian endometrioid cancer but not clear cell cancer

OBJECTIVE Although ovarian clear cell adenocarcinoma (OCCA) and ovarian endometrioid adenocarcinoma (EC) are considered to be closely related to endometriosis, the mechanisms of carcinogenesis of these two malignancies and malignant transformation of endometriosis are unclear. In this study, we examined the biology of OCCA and EC by performing large-scale analysis of K-ras activation and p53 mutation and overexpression in these malignancies. The results were subsequently analyzed for correlation with the clinicopathologic data. METHODS In the present study of OCCA and EC, we obtained clinicopathological data and analyzed frequency of mutations and overexpression of K-ras and p53. DNA was extracted from formalin-fixed, paraffin-embedded tissue, and target sequences were amplified in vitro by polymerase chain reaction. The DNA was analyzed for K-ras and p53 mutations by testing for single-strand conformation polymorphisms and by direct sequencing. Immunohistochemical staining was performed using p53 monoclonal antibody. Univariate analysis was performed using the Kaplan-Meier algorithm, and differences in survival were analyzed using the log rank test. The prognostic significance of the studied variables for survival was assessed using multivariate analysis with Cox regression analysis. RESULTS K-ras mutation was detected in 16.2% (6/37) of OCCA patients and 3.7% (1/27) of EC patients. No evidence of p53 mutation was detected in OCCA patients, but p53 mutation was detected in 63.0% of EC patients; these findings are consistent with the results of p53 immunohistochemistry. No statistical significance was observed for K-ras mutation in OCCA or EC. In EC patients, the absence of endometriosis and p53 overexpression was associated with a poorer survival. In OCCA patients tubulocystic and papillary histotype as well as stage II correlated with a worse survival. CONCLUSIONS p53 mutation, which was found in 63% of EC tumors, is an independent prognostic factor for EC patients. However, no p53 mutation was found in OCCA tumors. K-ras mutations did not affect survival of OCCA or EC patients.

Expression of the c-Ha-ras and c-mye genes in aflatoxin B1-induced hepatocellular carcinomas

Expression and activation of several c-oncogenes in seven hepatocellular carcinomas from seven separate rats treated with aflatoxin B1 (AFB1) were examined by Northern and Southern blot analyses. Both c-Ha-ras and c-myc transcripts were elevated at high levels in all hepatomas. Moreover, in one of them, T2-1 hepatoma, the c-myc gene was amplified only in a tumor part of liver without significant rearrangement. N-ras specific transcripts were not elevated in these hepatomas. The present data suggest that the consistently increased expression or deregulation of the c-myc and c-Ha-ras genes may play an important role in the development of hepatomas induced by AFB1.

The 5′ end sequences and exon organization in rat regucalcin gene

The 5−flanking region of the gene for a Ca2−-binding protein regucalcin was cloned from a rat genomic library which was constructed in lambda EMBL3 SP6/T7 vector. The genomic library was screened by using the radiolabeled probe with the 5′ region (0.5 kb) of rat regucalcin complementary deoxyribonucleic acid (cDNA). Positive clone had the 5.5 kb fragment which was hybridized with the 5′-probe. This fragment contained three exons (I–III) of the gene coding for a rat regucalcin. The nucleotide sequence of exons completely agreed with that of a rat regucalcin cDNA clone. A supposed translational initiation site existed in the exon 11. Homology analysis showed that a putative transcription start site in the rat regucalcin gene was located at position 26 downstream from a TATA-box. Another upstream element, a CCAAT box-like sequence, was located at −170. Moreover, there were many regulatory elements (Hox, AP-1, AP-2 and AP-4) in the 5′-flanking region of the rat regucalcin gene. The organization of rat regucalcin gene seemed to be about 18 kb in size and consisted of seven exons and six introns.

Use of nitrite and hypochlorite treatments in determination of the contributions of IQ-type and non-IQ-type heterocyclic amines to the mutagenicities in crude pyrolyzed materials

The mutagenic heterocyclic amines Glu-P-2, MeA alpha C and Phe-P-1, which possess a 2-aminopyridine structure in their molecule (non-IQ-type mutagens), were found to be inactivated by nitrite treatment under acidic conditions, as observed previously with Trp-P-1, Trp-P-2, Glu-P-1 and A alpha C. In contrast, MeIQx, 4,8- and 7,8-DiMeIQx, which were originally isolated from fried beef or heated model mixtures of creatinine, amino acids and glucose, and which have a 2-aminoimidazole moiety in their molecules (IQ-type mutagens), were very resistant to nitrite treatment like IQ and MeIQ. Both types of mutagenic heterocyclic amines were completely inactivated by treatment with hypochlorite. This differential inactivation of mutagenic heterocyclic amines by nitrite and hypochlorite was used in determination of the contributions of IQ-type and non-IQ-type mutagens to the total mutagenicities of various pyrolyzed materials. The percentage contributions of IQ-type mutagens to the mutagenicities of broiled sardine, fried beef, broiled horse mackerel, cigarette smoke condensate and albumin tar were 88, 75, 48, 6 and 4, respectively.

Detection of mutation of the p53 gene with high sensitivity by fluorescence-based PCR-SSCP analysis using low-pH buffer and an automated DNA sequencer in a large number of DNA samples.

Detection of mutations in genes responsible for hereditary diseases or tumors is important clinically. It is necessary to establish a simple technique for screening mutations in large numbers of samples. The polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method has proved to be a useful technique for analyzing mutations or DNA polymorphisms. Non-radioisotopic versions using fluorescent dye and an automated DNA sequencer have also been exploited to extend this technique into the clinical field. We have examined mutations of exons 5-9 of the p53 gene in 112 colorectal, 28 esophageal and 33 hepatocellular carcinomas by fluorescence-based PCR-SSCP (F-SSCP) under various conditions. We found 64 types of mutations in 63, 17 and 12 cases of colon, esophageal and hepatocellular carcinomas by F-SSCP. We determined the sequence of all samples, and confirmed that all mutations were successfully detected by F-SSCP. With the low-pH buffer system, 61 types of mutants were detected, while 51 types were detected by TBE and 57 types were detected by TBE with glycerol gel. The polyacrylamide gel in TME or TBE without glycerol was tough and could be used repeatedly, but the glycerol containing gel was fragile and could not stand repeated use. Thus, use of a low-pH buffer in the electrophoresis of F-SSCP is simpler and better at detecting mutations than the conventional TBE buffer system. We believe that low-pH F-SSCP analysis is an efficient and powerful technique for examination of a large number of samples, in particular clinical specimens obtained by biopsy or surgery.

Prognostic value of p53 mutations in patients with locally advanced esophageal carcinoma treated with definitive chemoradiotherapy.

Purpose. A significant correlation has been found between p53 mutation and response to chemotherapy or radiotherapy. To determine the prognostic value of p53 mutation in patients with locally advanced esophageal carcinoma treated with definitive chemoradiotherapy, p53 mutation was analyzed using the biopsied specimens taken for diagnosis. Methods. Concurrent chemoradiotherapy was performed for 40 patients with severe dysphagia caused by esophageal squamous cell carcinoma associated with T3 or T4 disease. Chemotherapy consisted of protracted infusion of 5-fluorouracil, combined with an infusion of cisplatinum. Radiation treatment of the mediastinum was administered concomitantly with chemotherapy. The p53 gene mutation was detected by fluorescence-based polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) methods. DNA sequences were determined for DNA fragments with shifted peaks by SSCP methods. Results. Of the 40 patients, 15 had T3 disease and 25 had T4 disease; 11 patients had M1 lymph node (LYM) disease. Of the 40 patients, 13 (33%) achieved a complete response. The median survival time was 14 months, and the 2-year survival rate was 20%. Among the 40 tumor samples, p53 mutation was detected in 24 tumors (60%). The survival rate in the 24 patients with p53 mutation did not differ significantly from that in the 16 patients without p53 mutation. In contrast, the 15 patients with T3 disease survived longer than the 25 patients with T4 disease (P = 0.016); however, the survival rate in the 11 patients with M1 LYM disease did not differ significantly from that in the 29 patients without M1 LYM disease. Conclusion. Concurrent chemoradiotherapy is potentially curative for locally advanced esophageal carcinoma, but p53 genetic abnormality has no impact on prognosis.

Differences in the histological findings, phenotypic marker expressions and genetic alterations between adenocarcinoma of the gastric cardia and distal stomach

Adenocarcinoma of the gastric cardia (C-Ca) is possibly a specific subtype of gastric carcinoma. The purpose of this study was to clarify the differences in the clinicopathological characteristics between C-Ca and adenocarcinoma of the distal stomach (D-Ca), and also the differences in the expressions of gastric and intestinal phenotypic markers and genetic alterations between the two. The clinicopathological findings in 72 cases with C-Ca were examined and compared with those in 170 cases with D-Ca. The phenotypic marker expressions examined were those of human gastric mucin (HGM), MUC6, MUC2 and CD10. Furthermore, the presence of mutations in the APC, K-ras and p53 genes and the microsatellite instability status of the tumour were also determined. C-Ca was associated with a significantly higher incidence of differentiated-type tumours and lymphatic vessel invasion (LVI) as compared with D-Ca (72.2 vs 48.2%, P=0.0006 and 72.2 vs 55.3%, P=0.0232, respectively). Oesophageal invasion by the tumour beyond the oesophago-gastric junction (OGJ) was found in 56.9% of cases with C-Ca; LVI in the area of oesophageal invasion was demonstrated in 61% of these cases. Also, LVI was found more frequently in cases of C-Ca with oesophageal invasion than in those without oesophageal invasion (82.9 vs 58.1%, P=0.0197). The incidence of undifferentiated-type tumours was significantly higher in cases with advanced-stage C-Ca than in those with early-stage C-Ca (5 vs 36.5%, P=0.0076). A significantly greater frequency of HGM expression in early-stage C-Ca and significantly lower frequency of MUC2 expression in advanced-stage C-Ca was observed as compared with the corresponding values in cases of D-Ca (78.9 vs 52.2%, P=0.0402 and 51.5 vs 84.6%, P=0.0247, respectively). Mutation of the APC gene was found in only one of all cases of C-Ca, and the frequency of mutation of the APC gene was significantly lower in cases of C-Ca than in those of D-Ca (2.4 vs 20.0%, P=0.0108). The observations in this study suggest that C-Ca is a more aggressive tumour than D-Ca. The differences in biological behavior between C-Ca and D-Ca may result from the different histological findings in the wall of the OGJ and the different genetic pathways involved in the carcinogenesis.

Delayed expressed TNFR1 co-localize with ICAM-1 in astrocyte in mice brain after transient focal ischemia.

Intercellular adhesion molecule-1 (ICAM-1) is expressed after brain ischemia and is participated in the induction of neuronal cell death. Recently, we have reported that ICAM-1 is localized in astrocytes in the chronic phase of ischemia. However, the regulation of astroglial ICAM-1 after brain ischemia is not elucidated in detail. Therefore, we examined the gene and protein expression of TNFR1 after transient middle cerebral artery occlusion (tMCAO) by using real time-PCR and immunohistochemistry. Moreover, we determined the relationship of TNFR1 and ICAM-1 in the astrocyte in chronic phase of ischemia. Increased expression of TNFR1 mRNA in the ipsilateral cortex was noted slightly during ischemia and was significantly increased at 12 h after reperfusion. Few TNFR1-like imuunoreactivity (TNFR1-LI) was observed in the cortex of normal animals. However, TNFR1-LI was increased at 1 h during ischemia, then it was decreased at 3-6 h, and was increased again at 12-24 h after reperfusion in the core of ischemic area. TNFR1-LI was demonstrated in both neurons and astrocytes but not in oligodendrocytes and microglia/macrophages at 24 h after reperfusion. At 96 h after tMCAO, TNFR1-LI was increased in the perifocal region and it appeared to be displayed the astrocyte-like cells. By use of double immunostaining method, we found that the ICAM-1-LI was overlapped with GFAP-LI. Our data indicates that the expression of TNFR1 is up-regulated in accordance with ischemic insult and delayed expressed TNFR1-LI co-localized with ICAM-1-LI in astrocytes after tMCAO. These results suggest that astroglial ICAM-1 is regulated by TNF-alpha dependent pathway.