Recurrent germline mutation in MSH2 arises frequently de novo

INTRODUCTION

An intronic germline mutation in the MSH2 gene, A-->T at nt942+3, interferes with the exon 5 donor splicing mechanism leading to a mRNA lacking exon 5. This mutation causes typical hereditary non-polyposis colorectal cancer (HNPCC) and has been observed in numerous probands and families world wide. Recurrent mutations either arise repeatedly de novo or emanate from ancestral founding mutational events. The A-->T mutation had previously been shown to be enriched in the population of Newfoundland where most families shared a founder mutation. In contrast, in England, haplotypes failed to suggest a founder effect. If the absence of a founder effect could be proven world wide, the frequent de novo occurrence of the mutation would constitute an unexplored predisposition.

METHODS

We studied 10 families from England, Italy, Hong Kong, and Japan with a battery of intragenic and flanking polymorphic single nucleotide and microsatellite markers.

RESULTS

Haplotype sharing was not apparent, even within the European and Asian kindreds. Our marker panel was sufficient to detect a major mutation arising within the past several thousand generations.

DISCUSSION

As a more ancient founder is implausible, we conclude that the A-->T mutation at nt942+3 of MSH2 occurs de novo with a relatively high frequency. We hypothesise that it arises as a consequence of misalignment at replication or recombination caused by a repeat of 26 adenines, of which the mutated A is the first. It is by far the most common recurrent de novo germline mutation yet to be detected in a human mismatch repair gene, accounting for 11% of all known pathogenic MSH2 mutations.

Chromosomal instability and p53 inactivation are required for genesis of glioblastoma but not for colorectal cancer in patients with germline mismatch repair gene mutation

We have previously reported high-frequency microsatellite instability (MSI-H) and germ-line mismatch repair gene mutation in patients with unusually young onset of high-grade glioma. Some of these patients developed metachronous MSI-H colorectal cancer and conformed to the diagnosis of Turcot's syndrome. Frameshift mutation of TGFbetaRII was present in all the colorectal carcinomas but not in brain tumours. We further characterized the genetic pathways of tumour evolution in these metachronous gliomas and colorectal carcinomas. All MSI-H glioblastomas had inactivation of both alleles of the p53 gene and showed over-expression of the p53 protein while none of the colorectal carcinomas had p53 mutation or protein over-expression. Flow cytometry and comparative genomic hybridization revealed that all glioblastomas were chromosomal unstable with aneuploid DNA content, and with a variable number of chromosomal arm aberrations. In contrast, the colorectal carcinomas had diploid or near-diploid DNA content with few chromosomal arm aberrations. The pattern of chromosomal aberrations in the two organs was different. Loss of 9p was consistently observed in all glioblastomas but not in colorectal carcinomas. Epidermal growth factor receptor amplification was absent in all glioblastomas and colorectal carcinomas. Our results suggest that both the frequency of p53 mutation and its effects differ greatly in the two organs. Following loss of mismatch repair function, p53 inactivation and chromosomal instability are not necessary for development of colorectal carcinoma, but are required for genesis of glioblastoma. Oncogene (2000) 19, 4079 - 4083.

Distinct clinical features associated with microsatellite instability in colorectal cancers of young patients

The Hong Kong Chinese population has an unusually high incidence of colorectal cancer in the young, suggestive of hereditary susceptibility. To search for a genetic basis for this predisposition, we studied the incidence of microsatellite instability (MSI) in paraffin-embedded colectomy specimens of 124 young (<50 years old) Chinese colorectal cancer patients referred to the Hong Kong Hereditary Gastrointestinal Cancer Registry from 1995 to 1998. By medical record review and personal interview, we searched for distinct clinical features associated with the manifestation of MSI in this group of patients. For patients with MSI tumours, blood was taken for detection of germline mutation in 2 mismatch repair (MMR) genes. MSI was present in 33 tumours from 23 males and 10 females (26.6%). Ongoing mutation analysis has so far identified MMR gene mutations in 8 patients with MSI tumours. The incidence of MSI increased significantly with decreasing age at cancer diagnosis. For patients aged 30 to 49, MSI tumours were located mainly at the proximal colon. However, for exceptionally young patients (<30 years), MSI tumours tended to be at the distal large bowel. This observation suggested a differential activity of the MMR pathway in colorectal carcinogenesis in different age groups. On multivariate analysis, young age at cancer diagnosis, proximal tumour location, a strong family history of colorectal cancer, and a personal history of metachronous cancer were independent predictors for MSI status. This knowledge may have an impact on the management of young colorectal cancer patients and their families.

The angiopoietins, tie2 and vascular endothelial growth factor are differentially expressed in the transformation of normal lung to non-small cell lung carcinomas

The successful establishment of angiogenesis depends on a complex process of endothelial proliferation and organization. The angiopoietins (Ang-1 and Ang-2) and Tie2 ligand-receptor system is essential for the regulation of vascular maturation and stability during embryonic development. Together with the vascular endothelial growth factor (VEGF)-mediated pathway, they have been implicated in the control of normal physiological angiogenesis. We investigated their potential role and interaction in the development of lung cancers by comparing the expression pattern and inter-relationship of Ang-1 and 2, Tie2 and VEGF levels in 28 pairs of primary non-small cell lung cancers (NSCLC) and normal lung. Using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and in-situ hybridization (ISH), we showed that in NSCLC, there was significantly up-regulated VEGF expression by the tumour cells and an increased intensity of Ang-2 expression in the tumour vessels. The number of Ang-2-expressing vessels also correlated with the grades of tumour cell expression of VEGF. On the other hand, normal lung expressed constitutively high and correlated levels of Ang-1 and Tie2, which were significantly reduced in the carcinomas. The findings suggested a role of the Ang-1/Tie2 pathway in the maintenance of the complex vasculature in normal lung, while collaborative activities between the Ang-2 and VEGF pathways might be important in promoting tumour angiogenesis in NSCLC.

Overexpression of protein kinase C-beta1 isoenzyme suppresses indomethacin-induced apoptosis in gastric epithelial cells

BACKGROUND & AIMS

We have previously reported that nonsteroidal anti-inflammatory drugs (NSAIDs) could induce apoptosis of gastric epithelial cells both in vivo and in vitro. This study investigated the role of protein kinase C (PKC) isoforms in the regulation of NSAID-induced apoptosis.

METHODS

Protein levels of 12 PKC isoforms in AGS cells, in the presence or absence of indomethacin, were determined by Western blot. The effect of PKC-beta1 overexpression by transfection with its complementary DNA (cDNA) on indomethacin-induced apoptosis and apoptosis-related genes, including p53, p21(waf1/cip1), and c-myc, was further investigated.

RESULTS

Treatment with indomethacin decreased the abundance of PKC-beta1 and increased that of PKC-beta2, eta, and epsilon, but did not alter the expression of PKC alpha, gamma, zeta, delta, iota, and micro. Overexpression of PKC-beta1 attenuated the apoptotic response of AGS cells to indomethacin, associated with overexpression of p21(waf1/cip1) in both messenger RNA and protein levels. Inhibition of PKC-beta1-mediated overexpression of p21(waf1/cip1) by its antisense cDNA partially reduced the antiapoptotic effect of PKC-beta1.

CONCLUSIONS

Indomethacin-induced apoptosis in gastric cancer cells is partly mediated by differential regulation of PKC isoform expression. Enhanced expression of exogenous PKC-beta1 protects against indomethacin-induced apoptosis through up-regulation of p21(waf1/cip1).

Reduction of EGF is associated with the delay of ulcer healing by cigarette smoking

Cigarette smoking is associated with peptic ulcer diseases. Smokers have lower levels of salivary epidermal growth factor (EGF) than nonsmokers. We investigated whether reduction of EGF is involved in the delay of gastric ulcer healing by cigarette smoking. Rats with acetic acid-induced ulcers were exposed to cigarette smoke (0, 2, or 4% vol/vol) 1 day after ulcer induction. EGF level was elevated 1 day after ulcer induction in salivary glands and serum, and 4 days after ulcer induction in the gastric mucosa. However, cigarette smoke depressed these beneficial effects and EGF mRNA expression in salivary glands and gastric mucosa. Cigarette smoke delayed gastric ulcer healing and reduced cell proliferation, angiogenesis, and mucus synthesis. Exogenous EGF (10 and 20 microg/kg i.v.) before smoke exposure reversed the adverse effects of cigarette smoke, whereas vascular endothelial growth factor level and nitric oxide synthase activity were unaffected. It is concluded that the detrimental effect of cigarette smoke on ulcer healing is a consequence of reduction of angiogenesis, cell proliferation, and mucus secretion through the depressive action on EGF biosynthesis and its mRNA expression in salivary glands and gastric mucosa.

Pharmacological inhibition of protein kinase C activity could induce apoptosis in gastric cancer cells by differential regulation of apoptosis-related genes

The protein kinase C (PKC) signaling pathway plays a key role in tumor cell proliferation, differentiation, and apoptosis. Gastric cancer usually possesses a higher level of PKC activity than normal tissue. We evaluated inhibition of PKC activity in apoptosis induction of gastric cancer cells and the expression profile of apoptosis-related genes. Gastric cancer cells (AGS) were incubated with two highly specific PKC inhibitors (RO-31-8220 and chelerythrine). Cell viability and cell cycle were determined by methyl-tetrazolium (MTT) assay and flow cytometry, respectively. Apoptosis was characterized by acridine orange staining, DNA gel electrophoresis, and flow cytometry. The expression of p53, p21(waf/cip1), c-myc, bcl-2, and bax was determined by western blot. The results showed that both PKC inhibitors hindered cell growth, arrested cells at G0/G1 phase and induced apoptosis. The protein level of p53, p21(waf/cip1), c-myc, and bax was elevated while bcl-2 kept unchanged following drug exposure. In conclusion, PKC inhibitors suppress growth of gastric cancer cells through apoptosis induction and cell cycle quiescence, which may be regulated by differential expression of apoptosis-related genes.

Seroprevalence of cytotoxin-associated gene A positive Helicobacter pylori strains in Changle, an area with very high prevalence of gastric cancer in south China

BACKGROUND

Helicobacter pylori, especially the CagA-positive strains, are closely associated with peptic ulcers and gastric cancers. We performed a large scale gastric cancer screening project and examined the prevalence of H. pylori and CagA-positive strains in Changle, China, an area with one of the World's highest gastric cancer mortality. We also compared the prevalence with that in Hong Kong which has one-tenth of the gastric cancer mortality of that in Changle.

METHODS

A total of 2424 subjects in Changle and 523 subjects in Hong Kong had endoscopic examination and venesection. Sera were tested for anti-H. pylori antibody and anti-CagA antibody and correlated with endoscopic findings.

RESULTS

In Changle, 80. 9% of the subjects were H. pylori carriers. Out of 551 carriers, 408 (74%) were positive for anti-CagA antibody. A total of 76% and 87% of the asymptomatic and gastric cancer patients were positive for anti-CagA antibody, respectively (P > 0.05). Compared to Hong Kong, there was a significantly (P < 0.0001) higher prevalence of CagA-positive strains in asymptomatic subjects in Changle (76%) than in Hong Kong (28%), but not in peptic ulcers or gastric cancers.

CONCLUSIONS

Subjects in Changle had a high prevalence of H. pylori infection and a high prevalence of the CagA-positive strains. The contrast in the prevalence of CagA-positive strains, in asymptomatic subjects in two areas with differing gastric cancer mortality, supports the pathogenic role of CagA-positive strains in gastric carcinogenesis.

Frequent microsatellite instability and mismatch repair gene mutations in young Chinese patients with colorectal cancer

BACKGROUND

The incidence of colorectal cancer in persons under 46 years of age is substantially higher in Hong Kong than in Scotland and many other countries. Consequently, we examined whether there is a hereditary predisposition for colorectal cancer in this Southern Chinese population.

METHODS

We investigated the incidence of microsatellite instability (MSI) at 10 DNA sites in 117 colorectal cancer specimens from Chinese patients of various ages. Those tumors with new alleles at 40% or more of the sites investigated were identified as highly unstable MSI (MSI-H). In young patients, we also searched for germline mutations in three mismatch repair genes (hMSH2, hMLH1, and hMSH6).

RESULTS

The incidence of MSI-H varied statistically significantly with age, being observed in more than 60% of those younger than age 31 years at diagnosis and in fewer than 15% of those age 46 years or older. In 15 patients (<46 years old) whose colorectal cancers showed MSI-H, eight possessed germline mutations in either hMSH2 or hMLH1. When mutations in hMSH6 were included, more than 80% of Chinese colorectal cancer patients younger than 31 years had germline mutations in mismatch repair genes. We found a novel germline missense mutation in hMSH6 in a 29-year-old man whose tumor showed no MSI. Two patients had a 4-base-pair insertion in exon 10 causing a truncated protein; this insertion is a common polymorphism with a population allele frequency in Chinese of 5.6%.

CONCLUSIONS

Our results indicate that germline mutations in mismatch repair genes contribute substantially to the pathogenesis and high incidence of colorectal cancer in young Hong Kong Chinese. However, because young Chinese and Caucasians show similar proportions of colorectal cancers with MSI-H, despite the higher incidence in the former, additional factors may underlie the high susceptibility of young Chinese to colorectal cancer.

Carcinoma of the colon with synchronous hepatic metastasis in a cirrhotic liver harboring a hepatocellular carcinoma

Tumor metastasis to a cirrhotic liver is rare. It has been suggested that colorectal cancer does not metastasize to the cirrhotic liver. We reported a 65 year-old man, a known carrier of hepatitis B surface antigen, diagnosed to have hepatocellular carcinoma with routine screening. A partial hepatectomy with resection of segments VI and VII was performed. The hepatectomy specimen revealed a 4.5 cm diameter HCC in a cirrhotic liver. Incidentally, 0.8 cm diameter ulcer at the descending colon. Histological examination of the left hemicolectomy specimen showed a moderately differentiated adenocarcinoma.

Vascular endothelial growth factor is up-regulated in the early pre-malignant stage of colorectal tumour progression

Angiogenesis is an essential requirement for the development, progression and metastasis of malignant tumours. Studies on transgenic mouse models have shown that angiogenesis begins in the pre-malignant phase of oncogenesis, when dysplastic lesions acquire an increased microvasculature. To investigate the relationship between the expression of vascular endothelial growth factor (VEGF) and colorectal tumour progression, we have studied VEGF expression level and splice variant pattern by semi-quantitative RT-PCR and the cellular source of VEGF expression by in situ hybrization (ISH) in a range of lesions that modelled the tumour-development pathway from normal colon to invasive colorectal adenocarcinomas. Colonic adenomas showed a statistically significant up-regulation of VEGF expression over normal tissues, with a further increase during the development of adenocarcinomas. Tumour cells formed the major source of VEGF expression, with a minor contribution from mononuclear cells in the tumour stroma and enhanced expression in tumour cells around necrotic regions. The comparable expression level in both the in situ and invasive components in the same tumours indicated that a high VEGF expression capacity had been acquired prior to establishment of the invasive phenotype. Our findings support activation of VEGF as the molecular basis for the discrete induction of angiogenesis in the pre-malignant phase of colorectal tumour development.

Vascular endothelial growth factor is up-regulated in the early pre-malignant stage of colorectal tumour progression

Angiogenesis is an essential requirement for the development, progression and metastasis of malignant tumours. Studies on transgenic mouse models have shown that angiogenesis begins in the pre-malignant phase of oncogenesis, when dysplastic lesions acquire an increased microvasculature. To investigate the relationship between the expression of vascular endothelial growth factor (VEGF) and colorectal tumour progression, we have studied VEGF expression level and splice variant pattern by semi-quantitative RT-PCR and the cellular source of VEGF expression by in situ hybrization (ISH) in a range of lesions that modelled the tumour-development pathway from normal colon to invasive colorectal adenocarcinomas. Colonic adenomas showed a statistically significant up-regulation of VEGF expression over normal tissues, with a further increase during the development of adenocarcinomas. Tumour cells formed the major source of VEGF expression, with a minor contribution from mononuclear cells in the tumour stroma and enhanced expression in tumour cells around necrotic regions. The comparable expression level in both the in situ and invasive components in the same tumours indicated that a high VEGF expression capacity had been acquired prior to establishment of the invasive phenotype. Our findings support activation of VEGF as the molecular basis for the discrete induction of angiogenesis in the pre-malignant phase of colorectal tumour development.

Germline hMSH2 and differential somatic mutations in patients with Turcot's syndrome

Turcot's syndrome is characterized clinically by the occurrence of primary brain tumor and colorectal tumor and has in previous reports been shown to be associated with germline mutations in the genes APC, hMLH1, and hPMS2. Here we describe three patients with Turcot's syndrome, each having colorectal adenocarcinoma and malignant glioma. All the colorectal and brain tumors from these patients showed replication errors in most of the microsatellite loci investigated. Search for underlying germline mutations in the nucleotide mismatch repair genes revealed three different hMSH2 mutations. All colorectal tumors showed a frameshift in the A(10) tract in the coding sequence of the transforming growth factor beta type II receptor (TGFBRII) gene, but no such change was detected in any of the brain tumors. Frameshift mutation in the BAX gene was found in one colon carcinoma and mutations in insulin-like growth factor type II receptor (IGFIIR) gene in one glioma. Our data have broadened the possible mutation spectrum of patients with Turcot's syndrome. The difference in the mutation spectrum of TGFBRII, BAX, and IGFIIR between brain and colorectal tumors in these individuals suggests that the mutator phenotype may target different pathogenic pathways in the oncogenic process of the two organs.

Helicobacter pylori in Meckel's diverticulum with heterotopic gastric mucosa in a population with relatively high H. pylori prevalence rate

BACKGROUND

Helicobacter pylori (H. pylori) colonize only foveolar gastric-type mucosa and are associated with active chronic gastritis and peptic ulcer. The aim of this study was to investigate whether H. pylori can also be found in Meckel's diverticulum which contains heterotopic gastric mucosa.

METHODS

Biopsy specimens of Meckel's diverticulum resected in Queen Mary Hospital, University of Hong Kong, during the 10 year period 1986-1995 were retrieved and reviewed. Those containing gastric heterotopia were examined for the presence of H. pylori, using Warthin-Starry silver stain.

RESULTS

In the 59 cases of Meckel's diverticula studied, 16 were found to contain heterotopic gastric mucosa. Helicobacter pylori were not identified in any of these cases. In one of the 16 patients a concomitant gastric biopsy was performed. Although the gastric mucosa of this patient was heavily colonized by H. pylori, again no H. pylori was found in the heterotopic gastric mucosa in the Meckel's diverticulum.

CONCLUSIONS

The absence of H. pylori in all the Meckel's diverticula examined, even when the stomach was heavily colonized by the organisms, suggests that colonization of Meckel's diverticulum by H. pylori is a rare event. This, together with the overall rarity of H. pylori in all reported series of Meckel's diverticulum, argues against its causative role in complications of Meckel's diverticulum.

Histological changes during clearance of chronic hepatitis B virus infection by adoptive immunity transfer

BACKGROUND

Serological clearance of hepatitis B surface antigen (HBsAg) has been described after reception of hepatitis B surface antibody positive marrow, via allogeneic bone marrow transplantation (BMT). Histological changes during the clearance of HBsAg are unknown.

METHODS AND RESULTS

We described two chronic hepatitis B carriers (both hepatitis B e antigen negative), who cleared HBsAg after allogeneic bone marrow transplantation. Both received hepatitis B surface and core antibody positive human leucocyte antigen identical donors' marrow and had serological clearance of HBsAg 15 and 7 weeks after allogeneic BMT, respectively. Both events were preceded by hepatic flare. Both patients were also treated with famciclovir for the prevention of hepatitis B reactivation after BMT. Histological examination during the flare showed only mild necroinflammatory activity with multiple foci of confluent necrosis, associated with moderate lymphocytic infiltration. The majority of these lymphocytes were cluster of differentiation (CD) 8 positive. Using immunohistochemistry, there was no detectable hepatic expression of hepatitis B core antigen. However, HBsAg was positive, mainly in the area of confluent necrosis. Using in situ hybridization, hepatitis B virus (HBV) DNA was detected in the nucleus of 5% of hepatocytes, but not in the cytoplasm.

CONCLUSIONS

At their last follow up, 22 and 16 months after BMT, the serum of both patients remained HBsAg negative, hepatitis B surface antibody positive and HBV-DNA negative by branched DNA assay.

Triple therapy for Helicobacter pylori eradication is more effective than long-term maintenance antisecretory treatment in the prevention of recurrence of duodenal ulcer: a prospective long-term follow-up study

BACKGROUND

The effectiveness of Helicobacter pylori eradication treatment and long term acid suppression maintenance in the natural course of duodenal ulcer has not been directly compared.

AIM

To compare in a prospective randomized study the effectiveness of H. pylori eradication on the prevention of recurrence of duodenal ulcer with long-term maintenance acid suppression therapy.

METHODS

One hundred and fourteen duodenal ulcer patients were randomized to the treatment over a 12-month period. Fifty-seven of them received triple therapy consisting of 1 g sucralfate q.d.s. for 28 days, 300 mg metronidazole q.d.s. for 14 days and 250 mg clarithromycin q.d.s. for 14 days. Another 57 received 20 mg omeprazole q.d.s. for 12 months. An upper endoscopy was performed before treatment, at 6 weeks, and 2, 6 and 12 months after the first endoscopy. Side-effects were self-recorded and clinical follow-ups were arranged for up to 4.25 years.

RESULTS

The ulcer healing rate was 90.2% (95% confidence interval (95% CI): 79-97%) in the omeprazole group at 6 weeks as compared to 83.3% (95% CI: 70-93%) in the triple therapy group (P = 0.38). There was a higher success rate of pain control in the omeprazole group. Side-effects were more frequently reported and compliance was poorer in the triple therapy group during the first 4 weeks. During follow-up, more relapses were seen in the omeprazole group (9.8%, 95% CI: 3-21%) than the triple therapy group (4.2%, 95% CI: 1-13%) at 1 year (P = 0.44). All relapses were due to the persistence of H. pylori infection. At the 1 year follow-up, none of the patients who were H. pylori negative had an endoscopic relapse compared to 7 out of 56 patients who remained H. pylori positive (12.5%, 95% CI: 5-24%, P = 0.018). After a mean follow-up of 4.07 years, none of those who remained H. pylori negative had an ulcer relapse while the 11 out of 41 who remained H. pylori positive had an ulcer relapse (26.8%, 95% CI 14-43, P = 0. 0005).

CONCLUSIONS

Both regimens were highly effective in healing ulcers. The eradication of H. pylori infection was associated with more side-effects and poor compliance but was more effective than the maintenance therapy in reducing the recurrence of duodenal ulcers. For the prevention of ulcer recurrence, testing of H. pylori status after triple therapy is more important than maintenance therapy.

Differential Helicobacter pylori infection rates in two contrasting gastric cancer risk regions of South China. China Gastric Cancer Study Group

BACKGROUND

Carriers of Helicobacter pylori are believed to have a three- to six-fold increased risk of developing gastric cancer. We have recently conducted a simultaneous cross-sectional population study on the prevalence of H. pylori infection in a cohort of asymptomatic adult volunteers in two contrasting gastric cancer risk regions of South China, Hong Kong and Changle of Fujian. Their mean annual gastric cancer mortality has been approximately 7.5 and 75/100 000 population, respectively, since the beginning of the last decade. The aim of this study was to evaluate if H. pylori prevalence bears any relationship to gastric cancer mortality rates in these two southern regions of China.

METHODS

Sera were obtained from 397 volunteers in Hong Kong. They were tested for anti-H.pylori immunoglobulin (Ig) G antibody by using a commercial enzyme-linked immunosorbent assay (ELISA) kit. Volunteers of Changle (1456) had upper endoscopy examination and were also tested for anti-H. pylori IgG antibody by the same ELISA method.

RESULTS

The overall H. pylori infection prevalence was significantly higher in Changle (80.4%) than in Hong Kong (58.4%; P< 0.01). The high prevalence is associated with more atrophic gastritis. The overall risk of gastric cancer in people of Changle is approximately five-fold that of Hong Kong (adjusted odds ratio 4.9, 95% CI 2.5-9.8).

CONCLUSIONS

It is concluded that the prevalence of H. pylori infection rates bear a direct relationship to gastric cancer mortality rates in these two southern regions of China. Thus, H. pylori most likely plays a significant aetiopathogenetic role in gastric carcinogenesis in subjects living in Changle.

Non-steroidal anti-inflammatory drug-induced apoptosis in gastric cancer cells is blocked by protein kinase C activation through inhibition of c-myc

Apoptosis plays a major role in gastrointestinal epithelial cell turnover, ulcerogenesis and tumorigenesis. We have examined apoptosis induction by non-steroidal anti-inflammatory drugs (NSAIDs) in human gastric (AGS) cancer cells and the role of protein kinase C (PKC) and apoptosis-related oncogenes. After treatment with aspirin or indomethacin, cell growth was quantified by MTT assay, and apoptosis was determined by acridine orange staining, DNA fragmentation and flow cytometry. The mRNA and protein of p53, p21waf1/cip1 and c-myc was detected by Northern and Western blotting respectively. The influence of PKC on indomethacin-induced apoptosis was determined by co-incubation of 12-O-tetradecanoylphorbol 13-acetate (TPA). The role of c-myc was determined using its antisense oligonucleotides. The results showed that both aspirin and indomethacin inhibited cell growth and induced apoptosis of AGS cells in a dose- and time-dependent manner, without altering the cell cycle. Indomethacin increased c-myc mRNA and protein, whereas p53 and p21wafl/cip1 were unchanged. Down-regulation of c-myc by its antisense oligonucleotides reduced apoptosis induction by indomethacin. TPA could inhibit indomethacin-induced apoptosis and accumulate cells in G2/M. Overexpression of c-myc was inhibited by TPA and p21waf1/cip1 mRNA increased. In conclusion, NSAIDs induce apoptosis in gastric cancer cells which may be mediated by up-regulation of c-myc proto-oncogene. PKC activation can abrogate the effects of NSAIDs by decreasing c-myc expression.

Microsatellite instability, Epstein-Barr virus, mutation of type II transforming growth factor beta receptor and BAX in gastric carcinomas in Hong Kong Chinese

Microsatellite instability (MI), the phenotypic manifestation of mismatch repair failure, is found in a proportion of gastric carcinomas. Little is known of the links between MI and Epstein-Barr virus (EBV) status and clinicopathological elements. Examination of genes mutated through the MI mechanism could also be expected to reveal important information on the carcinogenic pathway. Seventy-nine gastric carcinomas (61 EBV negative, 18 EBV positive) from local Hong Kong Chinese population, an intermediate-incidence area, were examined. Eight microsatellite loci, inclusive of the A10 tract of type II transforming growth factor beta receptor (TbetaR-II), were used to evaluate the MI status. MI in the BAX and insulin-like growth factor II receptor (IGF-IIR) genes were also examined. High-level MI (>40% unstable loci) was detected in ten cases (12.7%) and low-level MI (1-40% unstable loci) in three (3.8%). High-level MI was detected in two EBV-associated cases (11%) and the incidence was similar for the EBV-negative cases (13%). The high-level MIs were significantly associated with intestinal-type tumours (P = 0.03) and a more prominent lymphoid infiltrate (P = 0.04). Similar associations were noted in the EBV-positive carcinomas. The high-level MIs were more commonly located in the antrum, whereas the EBV-associated carcinomas were mostly located in body. Thirteen cardia cases were negative for both high-level MI and EBV. All patients aged below 55 were MI negative (P = 0.049). Of the high-level MIs, 80% had mutation in TbetaR-II, 40% in BAX and 0% in IGF-IIR. Of low-level MIs, 33% also had TbetaR-II mutation. These mutations were absent in the MI-negative cases. Of three lymphoepithelioma-like carcinomas, two cases were EBV positive and MI negative, one case was EBV negative but with high-level MI. In conclusion, high-level MIs were present regardless of the EBV status, and were found in a particular clinicopathological subset of gastric carcinoma patient. Inactivation of important growth regulatory genes observed in these carcinomas confirms the importance of MI in carcinogenesis.

hMLH1 promoter methylation and lack of hMLH1 expression in sporadic gastric carcinomas with high-frequency microsatellite instability

Mutation of DNA mismatch repair genes has rarely been documented in sporadic gastric carcinoma with microsatellite instability (MSI). In sporadic colorectal carcinoma, hMLH1 promoter methylation associated with protein loss is found in the majority of high-frequency MSI cases. We investigated a series of 35 sporadic gastric carcinomas stratified into high-frequency MSI (MSI-H), low-frequency MSI (MSI-L) and microsatellite stable (MSS) groups and found that hypermethylation of the CpG island in the hMLH1 promoter region was present in 100% of MSI-H sporadic gastric carcinomas. In 90% of cases, there was an associated complete loss of hMLH1 protein, as detected by immunohistochemistry, and a markedly lowered hMLH1 mRNA level. This loss of hMLH1 protein occurred in the MSI-H invasive tumor but not in the adjacent carcinoma-in situ or dysplastic components that were MSS. The MSI-L and MSS forms of gastric carcinoma all showed predominantly unmethylated hMLH1 promoter, positive hMLH1 protein and high hMLH1 mRNA level. On the other hand, hMSH2 protein was expressed in all of the tumors irrespective of the MSI status. Our results suggest that high-frequency MSI in sporadic gastric cancer is mostly due to epigenetic inactivation of hMLH1 in association with promoter methylation, and the loss of hMLH1 protein is a significant event in the development of invasive tumor.

Clearance of persistent hepatitis B virus infection in Chinese bone marrow transplant recipients whose donors were anti-hepatitis B core- and anti-hepatitis B surface antibody-positive

Thirteen hepatitis B surface antigen-positive Chinese patients who received hepatitis B surface antibody-positive marrow (hepatitis B core antibody-positive or -negative: 6 and 7, respectively) via allogeneic bone marrow transplantation (BMT) were studied. After BMT, 4 recipients had serologic clearance of hepatitis B surface antigen from hepatitis B core antibody-positive marrow, but none of the recipients of hepatitis B core antibody-negative marrow had serologic clearance (P=.02). There was no significant difference in the donors' hepatitis B surface antibody titer before BMT for patients with or without serologic clearance of hepatitis B surface antigen (2255.2+/-4244.0 vs. 854.2+/-2306.7 mIU/mL; P=not significant). Adoptive immunity clearance of hepatitis B surface antigen was favored by hepatitis B core antibody positive-donor marrow and was not related to donor pre-BMT hepatitis B surface antibody titer.

Monocyte chemoattractant protein-1 (MCP-1) expression in primary lymphoepithelioma-like carcinomas (LELCs) of the lung

Lymphoepithelioma-like carcinoma (LELC) of the lung is a recently recognized primary non-small cell lung carcinoma with distinct clinicopathological features and an aetiological association with Epstein-Barr virus (EBV) infection. The tumour consists of clusters and sheets of poorly or undifferentiated tumour cells in close association with numerous mononuclear inflammatory cells, including a rich component of tumour-associated macrophages (TAMs). To investigate the molecular mechanism leading to the TAM-rich stroma, the expression of a monocyte-specific chemotactic and activating factor, monocyte chemoattractant protein-1 (MCP-1), was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH), and the presence of TAMs was demonstrated by immunohistochemistry in nine LELCs. The results were compared with those found in 17 conventional non-small cell lung carcinomas. RT-PCR showed specific MCP-1 amplification in both LELCs and non-LELCs, but ISH demonstrated a unique and extensive expression of MCP-1 transcripts by the tumour cells of LELCs only, while TAMs, stromal fibroblasts, and endothelial cells formed the major source of MCP-1 in non-LELCs. TAMs in LELCs were more abundant and showed a close topographical relationship with the MCP-1-expressing tumour cells. The results indicate that tumour cell expression of MCP-1 in LELCs is an important mechanism contributing to their distinctive morphological features. This is the first study that demonstrates the in vivo upregulation of a monocyte-specific chemokine by EBV-related carcinomas, illustrating an interesting aspect of tumour biology in EBV-related neoplasms.

Ultrasound diagnosis of fetal diaphragmatic hernia and complex congenital heart disease at 12 weeks' gestation--a case report

Congenital diaphragmatic hernia is commonly associated with congenital heart disease. Their coexistence indicates a poor prognosis. Prenatal diagnosis of these conditions in early pregnancy allows the option of pregnancy termination. We present a case of left-sided fetal diaphragmatic hernia and complex congenital heart disease diagnosed by ultrasound examination at 12 weeks' gestation.