Endorectal ultrasonography and treatment of early stage rectal cancer

The purpose of this study was to evaluate the accuracy of preoperative staging by endorectal ultrasonography (EUS) and its contribution to treatment of early stage rectal cancer (ESRC). The results of EUS for 154 consecutive patients with ESRC (pTis to pT2) were compared prospectively with histologic findings, assessed according to the TNM classification. Results of treatment selection and long-term outcomes were analyzed retrospectively. There were 35 patients histologically staged as pTis, 8 as pT1-slight (invasion confined to the superficial one-third of the submucosa), 37 as pT1-massive (invasion extending to the deeper submucosa), and 74 as pT2. The equipment used was an echoendoscope GF-UM2 or GF-UM3 (Olympus, Tokyo, Japan). Sensitivity/specificity/overall accuracy rates for detection of slight submucosal invasion, massive submucosal invasion, and muscularis propria invasion were 99%/74%/96%, 98%/88%/97%, and 97%/93%/96%, respectively. Incidences of lymph node metastasis in pTis, pTis to pT1-slight, pT1, pT1-massive, and pT2 cases were 0%, 0%, 18%, 22%, and 30%, respectively. Incidences of lymph node metastasis in ESRCs staged by EUS (u) as uTis, uT1-slight, uT1-massive, uT2, and uT3 by EUS were 0%, 0%, 26%, 36%, and 64%, respectively. Sensitivity, specificity, and overall accuracy rates for detection of positive nodes in overall ESRCs were 53%, 77%, and 72%, respectively. Of the 43 patients with pTis to pT1-slight tumors, 22 underwent endoscopic polypectomy or local excision, 20 radical surgery, and 1 radical surgery after endoscopic polypectomy due to vascular invasion. All these patients are alive and all but one (who refused radical surgery due to vascular invasion after local excision and developed liver and lung metastases) are disease-free. Of the 37 patients with pT1-massive tumors, 34 underwent radical surgery and 3 transcoccygeal segmental resection. All these patients are alive disease-free except for one who died of peritoneal carcinomatosis after radical surgery. All patients with pT2 tumors underwent radical surgery. The overall 5-year survival rates for pTis, pT1, and pT2 cases were 100%, 98%, and 97%, respectively. EUS is an accurate method for evaluating invasion depth in ESRC. Patients with uTis or uT1-slight tumors staged by EUS are at low risk of positive nodes and good candidates for endoscopic polypectomy or local excision. Those with uT1-massive or uT2 lesions should be treated with a radical operation because of the high incidence of positive nodes.

Novel mutations in the microsomal triglyceride transfer protein gene causing abetalipoproteinemia

Abetalipoproteinemia (ABL) is an inherited disease characterized by the virtual absence of apolipoprotein B (apoB)-containing lipoproteins from plasma. Only limited numbers of families have been screened for mutations in the microsomal triglyceride transfer protein (MTP) gene. To clarify the genetic basis of clinical diversity of ABL, mutations of the MTP gene have been screened in 4 unrelated patients with ABL. Three novel mutations have been identified: a frameshift mutation caused by a single adenine deletion at position 1389 of the cDNA, and a missense mutation, Asn780Tyr, each in homozygous forms; and a splice site mutation, 2218-2A-->G, in a compound heterozygous form. The frameshift and splice site mutations are predicted to encode truncated forms of MTP. When transiently expressed in Cos-1 cells, the Asn780Tyr mutant MTP bound protein disulfide isomerase (PDI) but displayed negligible MTP activity. It is of interest that the patient having the Asn780Tyr mutation, a 27-year-old male, has none of the manifestations characteristic of classic ABL even though his plasma apoB and vitamin E were virtually undetectable. These results indicated that defects of the MTP gene are the proximal cause of ABL.

Absence of ACAT-1 attenuates atherosclerosis but causes dry eye and cutaneous xanthomatosis in mice with congenital hyperlipidemia

Acyl-CoA:cholesterol acyltransferase (ACAT) catalyzes esterification of cellular cholesterol. To investigate the role of ACAT-1 in atherosclerosis, we have generated ACAT-1 null (ACAT-1-/-) mice. ACAT activities were present in the liver and intestine but were completely absent in adrenal, testes, ovaries, and peritoneal macrophages in our ACAT-1-/- mice. The ACAT-1-/- mice had decreased openings of the eyes because of atrophy of the meibomian glands, a modified form of sebaceous glands normally expressing high ACAT activities. This phenotype is similar to dry eye syndrome in humans. To determine the role of ACAT-1 in atherogenesis, we crossed the ACAT-1-/- mice with mice lacking apolipoprotein (apo) E or the low density lipoprotein receptor (LDLR), hyperlipidemic models susceptible to atherosclerosis. High fat feeding resulted in extensive cutaneous xanthomatosis with loss of hair in both ACAT-1-/-:apo E-/- and ACAT-1-/-:LDLR-/- mice. Free cholesterol content was significantly increased in their skin. Aortic fatty streak lesion size as well as cholesteryl ester content were moderately reduced in both double mutant mice compared with their respective controls. These results indicate that the local inhibition of ACAT activity in tissue macrophages is protective against cholesteryl ester accumulation but causes cutaneous xanthomatosis in mice that lack apo E or LDLR.

Endoscopic and histological reversibility of gastric adenoma after eradication of Helicobacter pylori

Although epidemiological studies strongly suggest an association between Helicobacter pylori infection and gastric carcinogenesis via a multistage process, a causal link between them has not been demonstrated. We evaluated the endoscopic and histological changes of gastric adenoma, which is considered a premalignant condition, after eradication of H. pylori. Thirty-five H. pylori-infected patients with gastric adenoma were treated with triple therapy (lansoprazole 30mg/day, clarithromycin 400mg/day, and amoxicillin 1500 mg/day) for 1 week. Of these 35 patients, 30 (86%) exhibited no H. pylori by culture or histology after the therapy. Of the 30 gastric adenomas, 7 decreased in size endoscopically; three gastric adenomas especially showed apparent remission, although histological cure in these three patients was not apparent. Our results suggest that removal of H. pylori infection may only mask a gastric adenoma endoscopically owing to the change around the gastric mucosa.

Expression of CD44 variants and prognosis in oesophageal squamous cell carcinoma

BACKGROUND

The CD44 variant (CD44v) isoforms have been noted as markers for tumour metastasis and prognosis in several adenocarcinomas.

AIMS

To investigate whether CD44v, especially the CD44v2 (v2) isoform, may be a useful prognostic factor for patients with oesophageal squamous cell carcinoma, using a recently developed monoclonal antibody against a v2 epitope.

PATIENTS

233 patients (211 men and 22 women; mean age 61.9 years), with oesophageal squamous cell carcinomas curatively removed without additional treatment between 1987 and 1996 at the National Cancer Center Hospital, were analysed for CD44v expression.

METHODS

The expression of CD44v was evaluated immunohistochemically using monoclonal antibodies against epitopes of the standard and variant protein, in paraffin embedded oesophageal squamous cell carcinoma tissue from 233 patients who had undergone cervical, mediastinal, and abdominal lymphadenectomy (three field dissection) for oesophagectomy. The data were evaluated for any correlation with clinicopathological indices or prognosis.

RESULTS

Although total CD44 and CD44v6 (v6) were respectively observed in 99% and 97% of the cancer specimens, the expression of v2 was only 30%. Patients whose tumours were v2 positive had a significantly better prognosis than those whose tumours were v2 negative (p = 0.031). Furthermore, in patients without lymph node metastasis, v2 positivity alone was a significant independent factor of prognosis (relative risk of death associated with v2 negativity, 4.7; p = 0.037) in multivariate analysis.

CONCLUSIONS

These results indicate that v2 is a useful marker for clinical prognosis in patients with oesophageal squamous cell carcinoma. Particularly in patients without lymph node metastasis, v2 status may thus have implications for the use of adjuvant chemotherapy and/or radiotherapy in patients with oesophageal cancer at an early stage.

Identification of quantitative trait loci for serum cholesterol levels in stroke-prone spontaneously hypertensive rats

The stroke-prone spontaneously hypertensive rat (SHRSP) has been reported to show significantly lower levels of serum total cholesterol than the normotensive control strain Wistar-Kyoto rat (WKY). Because selective inbreeding was conducted for stroke proneness, this concomitantly inherited characteristic of SHRSP may play some pathophysiological role in stroke. We evaluated the genetic determinants of the cholesterol trait by estimating heritability and subsequently by undertaking a genome-wide screen with 161 genetic markers in F(2) progeny involving SHRSP and WKY (104 male and 106 female rats). Three quantitative trait loci (QTLs) were detected on rat chromosomes 5, 7, and 15. Markers from the linked region on chromosome 15 indicated significant evidence of linkage with a maximal log of the odds (LOD) score of 7.7, whereas those on chromosomes 5 and 7 cosegregated with the trait in a sex-specific manner (the QTL close to genetic marker D5 Mit5 reached an LOD score of 7.3 in males, and that close to D7 Mit10 reached an LOD score of 3.2 in females). The male-specific QTL on chromosome 5 appeared to overlap with previously reported QTLs for stroke-associated phenotypes, but an identical gene (or genes) appeared unlikely to control these and the cholesterol traits simultaneously. In the present study, serum cholesterol levels were shown to be highly genetically determined in SHRSP (the heritability estimates are 76% in males and 83% in females), and 3 QTLs with substantial effects were identified. Further work, however, is required to clarify whether the cholesterol trait is related to the etiology of stroke or has been retained by chance through the inbreeding process in SHRSP.

A crucial role of sterol regulatory element-binding protein-1 in the regulation of lipogenic gene expression by polyunsaturated fatty acids

Dietary polyunsaturated fatty acids (PUFA) are negative regulators of hepatic lipogenesis that exert their effects primarily at the level of transcription. Sterol regulatory element-binding proteins (SREBPs) are transcription factors responsible for the regulation of cholesterol, fatty acid, and triglyceride synthesis. In particular, SREBP-1 is known to play a crucial role in the regulation of lipogenic gene expression in the liver. To explore the possible involvement of SREBP-1 in the suppression of hepatic lipogenesis by PUFA, we challenged wild-type mice and transgenic mice overexpressing a mature form of SREBP-1 in the liver with dietary PUFA. In the liver of wild-type mice, dietary PUFA drastically decreased the mature, cleaved form of SREBP-1 protein in the nucleus, whereas the precursor, uncleaved form in the membranes was not suppressed. The decreases in mature SREBP-1 paralleled those in mRNAs for lipogenic enzymes such as fatty acid synthase and acetyl-CoA carboxylase. In the transgenic mice, dietary PUFA did not reduce the amount of transgenic SREBP-1 protein, excluding the possibility that PUFA accelerated the degradation of mature SREBP-1. The resulting sustained expression of mature SREBP-1 almost completely canceled the suppression of lipogenic gene expression by PUFA in the SREBP-1 transgenic mice. These results demonstrate that the suppressive effect of PUFA on lipogenic enzyme genes in the liver is caused by a decrease in the mature form of SREBP-1 protein, which is presumably due to the reduced cleavage of SREBP-1 precursor protein.

Sterol regulatory element-binding protein-1 as a key transcription factor for nutritional induction of lipogenic enzyme genes

To elucidate the physiological role of sterol regulatory element-binding protein-1 (SREBP-1), the hepatic mRNA levels of genes encoding various lipogenic enzymes were estimated in SREBP-1 gene knockout mice after a fasting-refeeding treatment, which is an established dietary manipulation for the induction of lipogenic enzymes. In the fasted state, the mRNA levels of all lipogenic enzymes were consistently low in both wild-type and SREBP-1(-/-) mice. However, the absence of SREBP-1 severely impaired the marked induction of hepatic mRNAs of fatty acid synthetic genes, such as acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase, that was observed upon refeeding in the wild-type mice. Furthermore, the refeeding responses of other lipogenic enzymes, glycerol-3-phosphate acyltransferase, ATP citrate lyase, malic enzyme, glucose-6-phosphate dehydrogenase, and S14 mRNAs, were completely abolished in SREBP-1(-/-) mice. In contrast, mRNA levels for cholesterol biosynthetic genes were elevated in the refed SREBP-1(-/-) livers accompanied by an increase in nuclear SREBP-2 protein. When fed a high carbohydrate diet for 14 days, the mRNA levels for these lipogenic enzymes were also strikingly lower in SREBP-1(-/-) mice than those in wild-type mice. These data demonstrate that SREBP-1 plays a crucial role in the induction of lipogenesis but not cholesterol biosynthesis in liver when excess energy by carbohydrates is consumed.

Embryonic lethality and defective neural tube closure in mice lacking squalene synthase

Squalene synthase (SS) catalyzes the reductive head-to-head condensation of two molecules of farnesyl diphosphate to form squalene, the first specific intermediate in the cholesterol biosynthetic pathway. We used gene targeting to knock out the mouse SS gene. The mice heterozygous for the mutation (SS+/-) were apparently normal. SS+/- mice showed 60% reduction in the hepatic mRNA levels of SS compared with SS+/+ mice. Consistently, the SS enzymatic activities were reduced by 50% in the liver and testis. Nevertheless, the hepatic cholesterol synthesis was not different between SS+/- and SS+/+ mice, and plasma lipoprotein profiles were not different irrespective of the presence of the low density lipoprotein receptor, indicating that SS is not a rate-limiting enzyme in the cholesterol biosynthetic pathway. The mice homozygous for the disrupted SS gene (SS-/-) were embryonic lethal around midgestation. E9.5-10.5 SS-/- embryos exhibited severe growth retardation and defective neural tube closure. The lethal phenotype was not rescued by supplementing the dams either with dietary squalene or cholesterol. We speculate that cholesterol is required for the development, particularly of the nervous system, and that the chorioallantoic circulatory system is not mature enough to supply the rapidly growing embryos with maternal cholesterol at this developmental stage.

No prognostic significance of p53 expression in esophageal squamous cell carcinoma

BACKGROUND AND OBJECTIVES

It is generally accepted that the overexpression of p53 protein is associated with poor prognosis in breast, colorectal, and other types of cancer. However, the prognostic significance of p53 aberrations in esophageal squamous cell carcinoma has yet to be determined. We attempted to analyze the relationship between p53 expression and the clinicopathologic features of esophageal squamous cell carcinoma by reviewing the medical records of a large patient population. Our study of esophageal squamous cell carcinoma involves the largest patient population to date.

METHODS

p53 expression in formalin-fixed, paraffin-embedded samples of 239 patients with primary esophageal squamous cell carcinoma (TNM stage I:79 cases, stage II: 82 cases, stage III: 78 cases), who underwent esophageal resection without additional treatment, were analyzed by immunohistochemical staining using a polyclonal antibody, RSP53. The relationships between p53 immunoreactivity and prognostic factors were determined by the chi(2) test, and the prognostic impact of p53 protein expression was analyzed by univariate and multivariate survival analyses.

RESULTS

In 115 (48.1%) of 239 esophageal tumors, nuclear immunoreactivity for the p53 protein was detected. The expression of the p53 protein did not correlate with sex, age, histological grading, lymph node metastasis, vascular invasion, or TNM stage. Similarly, p53 expression did not correlate with prognosis in univariate and multivariate survival analysis.

CONCLUSIONS

The expression of the p53 gene product had no impact on the prognosis of esophageal squamous cell carcinoma.

Overexpressed lipoprotein lipase protects against atherosclerosis in apolipoprotein E knockout mice

Lipoprotein lipase (LPL) is known to play a crucial role in lipoprotein metabolism by hydrolyzing triglycerides; however its role in atherogenesis has yet to be determined. We have previously shown that low density lipoprotein receptor knockout mice overexpressing LPL are resistant to diet-induced atherosclerosis due to the suppression of remnant lipoproteins. Plasma lipoproteins and atherosclerosis of apolipoprotein (apo) E knockout mice which overexpress the human LPL transgene (LPL/APOEKO) were compared with those of control apoE knockout mice (APOEKO). On a normal chow diet, LPL/APOEKO mice showed marked suppression of the plasma triglyceride levels compared with APOEKO mice (54 vs. 182 mg/dl), but no significant changes in plasma cholesterol and apoB levels. Non-high density lipoproteins (HDL) from LPL/APOEKO mice had lower triglyceride content, a smaller size, and a more positive charge compared with those from APOEKO mice. Cholesterol, apoA-I, and apoA-IV were increased in HDL. Although both groups developed hypercholesterolemia to a comparable degree in response to an atherogenic diet, the LPL/APOEKO mice developed 2-fold smaller fatty streak lesions in the aortic sinus compared to the APOEKO mice. In conclusion, overproduction of LPL is protective against atherosclerosis even in the absence of apoE.

Combination of polymorphisms in OB-R and the OB gene associated with insulin resistance in Nauruan males

OBJECTIVE

To investigate the relationship between polymorphisms in the OB-R and OB genes and metabolic markers for obesity and glucose intolerance in a population of Nauruan men. In addition, we examined the effect of the simultaneous presence of the three polymorphisms on the phenotype of individuals in this population.

DESIGN AND SUBJECTS

This study was conducted in a population from the Pacific Island of Nauru. Populations in this region have some of the highest recorded rates of obesity and type 2 diabetes and are therefore of great interest in the genetic analysis of these diseases. Two hundred and thirty-two male subjects were examined in this cross-sectional study. All subjects were non-diabetic and the group had a mean age of 31 y and a mean body weight of 104 kg.

MEASUREMENTS

Several phenotypic measures of body fatness and fat distribution (anthropometry), fasting plasma insulin, glucose and leptin concentrations, blood pressure and 2 h plasma glucose concentration, genotypes of subjects for the Gln223Arg, PRO1019pro (OB-R gene) and OB gene polymorphisms.

RESULTS

Individually, the OB gene and Gln223Arg OB-R polymorphisms were not associated with the obese or glucose-intolerant phenotype in this population. Individuals with the PRO1019pro polymorphism were found to have elevated insulin concentrations and diastolic blood pressure (Pc = 0.04). In addition, individuals found to simultaneously exhibit homozygosity of the common allele of all three polymorphisms (genotypes: Arg/Arg, pro/pro and II/II) exhibited significantly elevated fasting insulin levels (Pc = 0.03).

CONCLUSIONS

Pacific Island populations exhibit a remarkably high prevalence rate of obesity and type 2 diabetes and represent a unique population for genetic studies of obesity. In the present study we have revealed that a specific combination of alleles in OB and OB-R, two candidate genes for obesity, may confer an increased risk for the development of insulin resistance in Nauruan males.

[The prognostic factors of pancreatic cancer--adhesion molecule CD44]

The prognosis for pancreatic cancer is extremely poor, because there are usually invasion of surrounding tissues and metastases to lymph nodes, liver or peritoneum at the time of diagnosis. Many studies from the molecular-biological stand point have demonstrated this poor prognosis. However, the mechanisms underlying these invasive and metastatic capabilities have not yet been clarified. We reviewed several reports for prognostic factors of pancreatic cancer in molecular-biological examinations, and introduced our recent study on the adhesion molecule CD44. The CD44 variant 6 (v6) molecule has been noted as a marker for tumor metastasis and prognosis in several tumors. We examined whether or not v6 is a useful marker for evaluating the prognosis of pancreatic cancer patients. In addition, we attempted to assess the clinicopathological implications for pancreatic cancer of the variant 2 (v2) isoform using a recently developed monoclonal antibody against a v2 epitope. The expression of CD44 v6 and v2 was observed only in tumor cells, if at all. The expression of CD44 v6 and v2 was correlated with decreased overall survival. A significant correlation was obtained between CD44 v2 and vessel invasion. These results suggest that CD44 v2 and CD44 v6 may be useful markers of a poor prognosis.

Expression of CD44 variants and its association with survival in pancreatic cancer

Since the CD44 variant 6(v6) molecule has been noted as a marker for tumor metastasis and prognosis in several tumors, we examined whether or not v6 is a useful marker for evaluating the prognosis of pancreatic cancer patients. In addition, we attempted to assess the clinicopathological implications for pancreatic cancer of the variant 2 (v2) isoform using a recently developed monoclonal antibody against a v2 epitope. The expression of CD44 variants was evaluated immunohistochemically in paraffin-embedded pancreatic cancer tissues from 42 patients who were confirmed surgically and histologically to have received curative resection. An indirect immunoperoxidase method was used with monoclonal antibodies against epitopes of the standard (CD44s) portion, v6 and v2. Protein expression data were evaluated statistically for any correlations with the length of survival or with histological parameters. The expression of CD44v6 and v2 was observed only in tumor cells, if at all. On the other hand, expression of total CD44 (including CD44v, as well as CD44s) was observed in both tumors and adjacent normal sites. Tumor tissue from 21 (50%) and 16 (38%) patients showed positive immunoreactivity with mAb 2F10 (anti-CD44v6) and mAb M23.6.1 (anti-CD44v2), respectively. The expression of CD44v6 and v2 was correlated with decreased overall survival (P = 0.0160 and P = 0.0125, respectively). A significant correlation was obtained between CD44v2 peptide expression and vessel invasion (P = 0.026). These results suggest that CD44v2 and CD44v6 may be useful markers for poor prognosis in curatively resected primary pancreatic cancer.

Increased expression of cyclooxygenase-2 to -1 in human colorectal cancers and adenomas, but not in hyperplastic polyps

BACKGROUND

Non-steroidal anti-inflammatory drugs can reduce the risk of colorectal cancer. Reportedly, mRNA expression of cyclooxygenase-2 (COX-2) is elevated in human colorectal cancers compared with accompanying normal mucosa. The present study was undertaken to establish a simple analytical procedure to quantify COX-2 expression levels and to characterize COX-2 expression levels in human colorectal cancers, adenomas and hyperplastic polyps.

METHODS

The combination of PCR using common primers designed in the highly conserved regions and fluorescence-based single-strand conformation polymorphism (F-SSCP) analysis of the products is used for quantitative determination of the proportions of COX-2 mRNA in human colorectal cancers, adenomas, hyperplastic polyps and accompanying normal mucosa.

RESULTS

The present F-SSCP analysis was a simple and powerful method for quantitative determination of the proportions of COX-2 mRNA. The proportion of COX-2 mRNA was higher in cancer tissues than in accompanying normal mucosa in 46 of the 50 cancers. There was no significant correlation between the increase of the COX-2 proportion and tumor location or stages. The enhanced COX-2 expression was also observed in colorectal adenomas. On the other hand, the proportion of COX-2 mRNA in hyperplastic polyps was not significantly different from that in normal mucosa.

CONCLUSIONS

The proportion of COX-2 to COX-1 expression was elevated in most human colorectal cancers and adenomas, but not in hyperplastic polyps. Therefore, the increased proportion of COX-2 expression might be an early event in the carcinogenesis of colorectal cancer.

Clinical features associated with the homozygous Trp64Arg mutation of the beta3-adrenergic receptor: no evidence for its association with obesity in Japanese

To characterize the clinical features associated with the Trp64Arg mutation of the beta3-adrenergic receptor (beta3-AR), the effects of this mutation, in particular the homozygous state (Arg/Arg), on obesity, blood pressure, and plasma lipoproteins were investigated in 2 populations: subjects residing on a small isolated island (group 1; n=746) and patients residing in Tokyo who attend a clinic for metabolic diseases (group 2; n=371). The allelic frequency of the Trp64Arg mutation was 23.4% in group 1 and 18.3% in group 2. No significant difference in the body mass index was observed between subjects with 3 different genotypes in each group. There was a trend that the Arg/Arg had higher systolic blood pressure than the Trp/Trp in both groups, but the differences were not statistically significant. The plasma LDL cholesterol levels were significantly lower in Arg/Arg than in Trp/Trp in men from the group 1 cohort (2.82+/-0.84 versus 3.19+/-0.7 mmol/L, P<0.05). These results suggest that the homozygous Trp64Arg mutation is not a major contributing factor for obesity, but potentially contributed to higher systolic blood pressure and low plasma levels of LDL cholesterol in Japanese men.

Effect of macrophage colony stimulating factor on the advanced atherosclerosis in Watanabe heritable hyperlipidemic rabbits

We have reported that macrophage colony-stimulating factor (M-CSF) prevents atherosclerosis in young WHHL rabbits (Atherosclerosis 93:245, 1993). In the present study, we injected recombinant human M-CSF (250 micrograms/day) into WHHL rabbits aged 11 months 3 times a week after advanced atherosclerosis was established. After 8 months of treatment, we did not find any significant difference in plasma lipid levels, cholesterol ester content in the aorta or macroscopic atherosclerosis lesion area between M-CSF treated and non-treated rabbits. There was, however, a significant difference in the ratio of intimal to medial thickness (1.08 vs 1.7, p < 0.01). Thus, M-CSF may influence vascular smooth muscle cell function and modify the process of atherosclerosis in advance lesions.