Relationship between age and site of colorectal cancer based on colonoscopy findings

BACKGROUND

Colorectal cancer occurs more frequently in older people. Because the population of aged persons is increasing, a better understanding of the characteristics of colorectal cancer with respect to age would be useful. The purpose of this study was to determine whether there is any relationship between the site of colorectal adenoma and adenocarcinoma in the colon and age.

METHODS

Colonoscopy was performed (September 1995 to December 1998) on 2942 consecutive patients (1907 men, 1035 women; mean age 61 years, range 11 to 95 years) with no history of colorectal adenoma, adenocarcinoma, or inflammatory bowel disease. The occurrence of colorectal neoplasia, histologically proven as adenoma or adenocarcinoma, was analyzed for a possible association between site in the colon and patient age.

RESULTS

Adenocarcinoma was found in 191 patients (196 lesions). The proportion of patients with right-sided colonic adenocarcinoma increased with patient age: < 50 years, 15% (2/13); 50 to 59 years, 21% (8/39); 60 to 69 years, 32% (18/57); 70 to 79 years, 42% (25/49); > or =80 years, 57% (16/28). The proportion of patients with right-sided adenoma did not significantly differ among age groups: < 50 years, 40% (98/246); 50 to 59 years, 41% (280/678); 60 to 69 years, 46% (459/1001); 70 to 79 years, 53% (270/508); and > or =80 years, 57% (87/152).

CONCLUSION

The frequency of right-sided colon cancer increases with patient age. Hence, colonoscopy may be indicated in the elderly for colorectal cancer screening. Over half of colon carcinomas may be missed if sigmoidoscopy alone is used for screening.

Helicobacter pylori activates the proto-oncogene c-fos through SRE transactivation

Epidemiological studies have demonstrated a strong association between Helicobacter pylori infection and gastric cancer. However, there have been few detailed studies on the mechanism of cellular proliferation by H. pylori. Thus, we examined activation of the proto-oncogene c-fos to elucidate the underlying mechanism of cell proliferation caused by H. pylori. Activation of c-fos was evaluated in human gastric cancer cells (TMK1) by Northern blot and reporter assays with deletion analysis of the c-fos transcriptional control region. c-fos promoter activation and transcription were enhanced when cocultured with cag-positive strains. H. pylori-mediated c-fos promoter activation was inhibited by MEK1/2 inhibitor (U0126). The deletion analysis indicated that serum response element (SRE) was required for the activation of c-fos by H. pylori. In conclusion, c-fos promoter activation and transcription were enhanced through the activation of extracellular signal-regulated kinases (ERK)/mitogen-activated protein kinase (MAPK) cascade in gastric cancer cells when cocultured with H. pylori possessing intact cag PAI. SRE is required for the activation of c-fos by H. pylori. These results suggest a direct involvement of H. pylori infection in cellular proliferation, which may play a role in neoplastic transformation.

Polyurethane-covered metal stent for management of distal malignant biliary obstruction

BACKGROUND

The efficacy of polyurethane-covered metal expandable stents for treatment of neoplastic distal biliary obstruction was analyzed.

METHODS

Twenty-one patients with unresectable malignant tumors involving the mid to distal bile duct who were seen with obstructive jaundice were consecutively enrolled. Eighteen patients underwent endoscopic implantation of a polyurethane-covered metal stent and 3 patients underwent transhepatic insertion because of duodenal obstruction. The stent patency, complications, and patient survival were analyzed.

RESULTS

Effective biliary decompression was achieved in all patients. Adverse events were minor: mild pancreatitis (1) and cholecystitis (2) occurred within 7 days of stent insertion. Mean survival and stent patency were 233 days and 206 days, respectively. Stent occlusion occurred in 3 patients (14%) after a mean of 188 days. Tumor ingrowth through the stent mesh was not observed. However, 2 stents were occluded by tumor overgrowth and 1 by compacted alimentary debris.

CONCLUSIONS

A polyurethane membrane may prevent tumor ingrowth and reduce the occlusion rate for expandable metal stents implanted in patients with malignant obstruction of the distal bile duct.

Hepatic volumetry to predict adverse events in percutaneous ablation of hepatocellular carcinoma

BACKGROUND/AIMS

This study aimed to clarify the relation of hepatic volumetry to adverse events after percutaneous transhepatic ablation for hepatocellular carcinoma.

METHODOLOGY

One hundred and forty-nine patients with hepatocellular carcinoma who underwent percutaneous ablation sessions with complete ablation of cancer nodules, underwent volume measurement of the entire liver, tumor, and ablated area using computed tomography. The parenchymal ablation rate was calculated: (ablated volume-tumor volume)/(entire liver volume-tumor volume) x 100 (%). Other clinical parameters were also analyzed to determine their relationship to adverse events.

RESULTS

The median adjusted liver volume was 591 mL/body surface area (m2) (range: 300 to 1197 mL/m2). The median parenchymal ablation rate was 2.3% (range: 0.2% to 20.2%). Adverse events were observed in 17 patients after percutaneous ablation: liver abscess in 3, hepatic infarction in 3, portal vein thrombus in 3, hemobilia in 1, pleural effusion and/or ascites in 6, and gastric ulcer in 1. Multivariate analysis showed that Child B or C (P = 0.0009), adjusted liver volume < 600 mL/m2 (P = 0.0004), and parenchymal ablation rate > 5% (P = 0.0320) were independent risk factors for adverse events.

CONCLUSIONS

Measurement of liver volume and parenchymal ablation rate are useful to predict the presence of percutaneous ablation-related adverse events.

Hepatitis C virus NS4A and NS4B proteins suppress translation in vivo

Many viruses can inhibit protein synthesis in their host cells by targeting translation ("translational shutoff"). There are few reports on the effects of hepatitis C virus (HCV) infection on protein synthesis, because of the lack of a reproducible tissue culture system for HCV. In this study, the influence of seven HCV proteins (core, NS2, NS3, NS4A, NS4B, NS5A, NS5B) on protein synthesis was examined using a reporter assay. In addition, it was determined whether the HCV proteins inhibit protein synthesis via transcription or translation using an RNase protection assay and the effect of HCV proteins on translation from the HCV internal ribosome entry site (IRES) was also examined using a bicistronic reporter. Of the seven HCV proteins, NS4A and NS4B proteins inhibited cellular protein synthesis by targeting the process of translation. They also inhibited translation from the HCV IRES. Moreover, NS4A protein, induced under the control of doxycycline, inhibited the proliferation of HeLa cells. In conclusion, HCV NS4A and NS4B proteins have an effect of translational inhibition. This novel function may be involved in HCV infection and help its survival in host cells.

Weak response of helicobacter pylori antibody is high risk for gastric cancer: a cross-sectional study of 10,234 endoscoped Japanese

BACKGROUND

A large number of endoscoped members of the general Japanese population were surveyed to investigate the relationship between Helicobacter pylori infection and gastric cancer. Special attention was given to antibody titer and age of the subjects.

METHODS

We performed gastrointestinal endoscopy and measured serum anti-H. pylori antibody in 10,234 consecutive Japanese who participated in a health examination program. Gastric cancer, when suspected, was confirmed by histology. We graded the H. pylori antibody titer into three groups in accordance with optical density values by ELISA: 'strongly positive', 'weakly positive', and 'negative'.

RESULTS

Among the 10,234 subjects (men/women, 7.021/3,213; mean age, 49.1 years), 4,909 (48%) were strongly positive, 1,750 (17%) were weakly positive, and 3,575 (35%) were negative for H. pylori antibody. Thirty-seven cases of gastric cancer were found among the 10,234 subjects (0.36%); 23/4,909 (0.47%) in the strongly positive group, 9/1,750 (0.51%) in the weakly positive group, and 5/3,575 (0.14%) in the negative group. Both the strongly and weakly positive groups showed a higher risk of gastric cancer than the negative group. In the subjects over age 60, the weakly positive group seemed to show the highest risk for gastric cancer.

CONCLUSIONS

In this investigation of 10,234 Japanese, based on endoscopy results, those with serum H. pylori antibody had an increased risk for gastric cancer, while those 'weakly positive' showed a high risk, particularly in the elderly.

The evaluation of putative virulence factors of Helicobacter pylori for gastroduodenal disease by use of a short-term Mongolian gerbil infection model

Few virulence determinants of Helicobacter pylori have been tested in vivo. We conducted this study to establish an animal model for their screening. Six-week-old male Mongolian gerbils were inoculated with wild-type H. pylori (TN2) or its isogenic mutant with deletion of cagE (TN2DeltacagE), total cag pathogenicity island (TN2DeltacagPAI), HP0499 (TN2DeltaHP499), or HP0638 (TN2DeltaHP638) (n=5 each). The animals were killed 3 weeks later, and the density of bacteria and the degree of inflammation in the stomach were compared. Infection was established in all animals except those inoculated with TN2DeltaHP638. TN2 and TN2DeltaHP499, but not TN2DeltacagE and TN2Deltacag PAI, induced intense inflammation, although the densities of bacteria were similar. The Mongolian gerbil model was useful for the screening of virulence determinants in vivo, which confirmed the importance of cag PAI while questioning that of HP0499.

Extensive mesenteric vein and portal vein thrombosis successfully treated by thrombolysis and anticoagulation

Mesenteric vein thrombosis is generally difficult to diagnose and can be fatal. A case of extensive thrombosis of the mesenteric and portal veins was diagnosed early and successfully treated in a 26-year-old man with Down syndrome who was admitted to hospital because of abdominal pain, severe nausea and high fever. Ultrasonography revealed moderate ascites, and there was minimal flow in the portal vein (PV) on the Doppler examination. Computed tomography (CT) showed remarkable thickening of the walls of the small intestine and extensive thrombosis of the mesenteric, portal and splenic veins. Because neither intestinal infarction nor peritonitis was seen, combined thrombolysis and anticoagulation therapy without surgical treatment was chosen. Urokinase was administered intravenously and later through a catheter in the superior mesenteric artery. Heparin and antibiotics were given concomitantly. The patient's symptoms and clinical data improved gradually. After 10 days, CT revealed that collateral veins had developed and the thrombi in the distal portions of the mesenteric veins had dissolved, although the main trunk of the PV had not recanalized. The only risk factor of thrombosis that was detected was decreased protein S activity.

Distinct mechanism of Helicobacter pylori-mediated NF-kappa B activation between gastric cancer cells and monocytic cells

NF-kappaB is a critical regulator of genes involved in inflammation. Gastric epithelial cells and macrophages are considered the main sources of pro-inflammatory cytokines. We investigated NF-kappaB activation by Helicobacter pylori in MKN45 gastric epithelial cells and THP-1 monocytic cells. Although, cag pathogenicity island (PAI)-positive H. pylori (wild type) activated NF-kappaB in both cells, isogenic mutant of cagE (DeltacagE) activated it only in THP-1 cells. Supernatant from the wild type culture could activate NF-kappaB in THP-1 cells but not in MKN45 cells. High density cDNA array analysis revealed that mRNA expression of NF-kappaB-regulated genes such as interleukin (IL)-8, tumor necrosis factor-alpha (TNFalpha), and IL-1beta was significantly up-regulated by the wild type in both cells, whereas it was up-regulated by DeltacagE only in THP-1 cells. Experiments using CD14-neutralizing antibody and IL-1 receptor-associated kinase (IRAK) assay showed that both wild type and DeltacagE H. pylori activated NF-kappaB through CD14 and IRAK in THP-1 cells but not in MKN45 cells. Macrophages from C3H/HeJ mice carrying point mutation in the Toll-like receptor 4 (TLR4) gene showed decreased NF-kappaB activation and TNFalpha secretion compared with C3H/HeN mouse macrophage when treated with H. pylori. In conclusion, H. pylori-induced NF-kappaB activation in epithelial cells is dependent on cag PAI and contact but does not involve CD14 and IRAK, whereas in macrophage/monocytic cells it is independent of cag PAI or contact but involves CD14 and TLR4.

Systematic analysis of the TGF-beta-Smad signaling pathway in gastrointestinal cancer cells

The transforming growth factor-beta (TGF-beta)-Smad signaling pathway has an important role in carcinogenesis. To study the frequency and mechanism of functional impairment of this pathway in human gastrointestinal cancers, we used a reporter assay to examine the response of 38 cell lines (11 colorectal, 9 pancreatic, 10 gastric, and 8 hepatic cancers) to TGF-beta. We then analyzed TGF-beta type II receptor (T beta RII) gene, immunoblots of Smad4, and restoration of the pathway by rescuing T beta R or Smad. We observed impaired signaling in 91% of colorectal, 67% of pancreatic, and 40% of gastric cancer cell lines, but in none of the hepatic cancer cells. We suggest that this pathway does not function as a tumor suppressor in hepatic carcinogenesis. The impairment is due to inactivation of T beta RII and Smad4 in colorectal and pancreatic cancers. However, because the signal was not recovered by rescuing T beta R or Smad genes in TGF-beta-response-defective gastric cancer cell lines, we suggest that novel molecules or mechanisms are involved in the impaired pathway in some gastric cancers.

Usefulness of MR imaging in the postsurgical monitoring of gallbladder cancer in a patient with bile duct cancer that developed 7 years after resection of mucinous adenocarcinoma of the gallbladder

We encountered a case of left hepatic duct cancer that developed 7 years after surgical resection of early-stage adenocarcinoma of the gallbladder. A 65-year-old woman was hospitalized with high fever and general fatigue. She also had elevated serum levels of alkaline phosphatase, gamma-glutamyltranspeptidase, and carbohydrate antigen 19-9. Seven years earlier, she had undergone extended cholecystectomy and resection of the extrahepatic bile duct for early-stage mucinous adenocarcinoma of the gallbladder. Conventional examinations did not reveal any responsible lesions. Magnetic resonance (MR) cholangiography, however, showed a tumor obstructing the left hepatic duct, and dynamic MR images revealed multiple foci of bacterial abscess in the liver. Surgically resected tissue again revealed mucinous adenocarcinoma. The present case is rare in that metachronous mucinous adenocarcinoma of the biliary system occurred after a long interval. This case suggests the usefulness of MR imaging in the postsurgical monitoring of patients with gallbladder carcinoma.

Inverse background of Helicobacter pylori antibody and pepsinogen in reflux oesophagitis compared with gastric cancer: analysis of 5732 Japanese subjects

BACKGROUND

The relationship between Helicobacter pylori and reflux oesophagitis remains controversial.

AIMS

To evaluate the relationship between H pylori and reflux oesophagitis in a large number of Japanese subjects.

SUBJECTS

A total of 5732 consecutive Japanese subjects during a health screening were enrolled.

METHODS

Gastrointestinal endoscopy was performed on all subjects. We simultaneously measured serum anti-H pylori antibody and pepsinogen as markers of H pylori infection together with gastric atrophy. The risk of reflux oesophagitis was evaluated in relation to these markers, and the results were compared with those of gastric cancer.

RESULTS

Reflux oesophagitis was found in 108 subjects. Both positivity for H pylori antibody (adjusted odds ratio (OR) 0.67 (95% confidence interval 0.45-1.0)) and "low" pepsinogen indicating gastric atrophy (OR 0.35 (0.18-0.68)) were negatively associated with reflux oesophagitis. After subjects were classified into four groups based on positivity or negativity for H pylori antibody and "low" pepsinogen, the prevalence of reflux oesophagitis showed a decreasing trend as H pylori induced gastric atrophy became more severe. The risk of gastric cancer showed an increasing trend, exactly the opposite to that of reflux oesophagitis.

CONCLUSIONS

Analysis of a large series of Japanese subjects revealed a decreasing prevalence of reflux oesophagitis in conjunction with progress of gastric atrophy induced by H pylori infection. This pattern was completely opposite to that of gastric cancer cases. A protective role of H pylori for reflux oesophagitis through the development of gastric atrophy has been suggested.

Management of hepatocellular carcinoma: advances in diagnosis, treatment and prevention

Since the major causes of hepatocellular carcinoma are hepatitis viruses, the difference and similarity of clinical features in relation to the causative virus may indicate that persistent inflammation of the liver is a major role in hepatocellular carcinoma development in both HBV and HCV infection. However, there is a variety of molecular products of virus-inducing mutagenesis, especially in HBV. An advance in the diagnosis of hepatocellular carcinoma is imaging modality to detect hemodynamics of hepatocellular carcinoma with noninvasive methods of ultrasonography and tumor markers. Chemoprevention using synthetic retinoid is another important issue for the prevention of hepatocellular carcinoma development, as well as viral eradication and suppression of inflammation in the liver using interferon and other drugs.

Relationship between grade of microsatellite instability and target genes of mismatch repair pathways in sporadic colorectal carcinoma

Microsatellite instability (MSI) induces carcinoma through the alteration of target genes; TGF-beta RII, BAX, IGFIIR, hMSH3, and hMSH6. The grade of M

Power Doppler signals after percutaneous ethanol injection therapy for hepatocellular carcinoma predict local recurrence of tumors: a prospective study using 199 consecutive patients

BACKGROUND/AIMS

This study was prospectively conducted to elucidate the relationship between pre-/post-treatment power Doppler signals of hepatocellular carcinoma (HCC) and local recurrence.

METHODS

One hundred ninety-nine consecutive patients with 359 HCC lesions receiving percutaneous ethanol injection therapy (PEIT) as a first-line option were enrolled. Arterial power Doppler signals in the tumor were found in 130 nodules, but not detected in 229. After confirmation of complete tumor necrosis on dynamic CT, Doppler signals in nodules were re-evaluated. Patients received periodical examinations to detect HCC recurrence.

RESULTS

Local HCC recurrence was observed in 36 lesions; 22%(28/130) of the pretreatment signal positive lesions, in contrast to 3.5% (8/229) of the pretreatment signal negative lesions (P < 0.01). Out of 130 signal positive nodules, signals disappeared in 120 (92%) after PEIT, but were present in ten (8%). During the 25-month follow up, local recurrence was detected in 19 (16%) from the former, in contrast to nine (90%) from the latter (P < 0.001). Uni- and multivariate Cox analysis revealed that the presence of pre-/post-treatment power Doppler signals, histological differentiation and tumor number were independent factors for local recurrence. However, 3-year recurrence rate of new lesions was 51%, but no predictors were identified.

CONCLUSIONS

Residual Doppler signals in tumor after PEIT were related to the local HCC recurrence.

Thoracoscopic thermal ablation therapy for hepatocellular carcinoma located beneath the diaphragm

BACKGROUND AND STUDY AIMS

Percutaneous interstitial thermal ablation therapy effectively treats hepatocellular carcinoma (HCC) that can be visualized on percutaneous ultrasonography. However, when the tumor is located just under the top of the diaphragm, visualization can be difficult with conventional ultrasonographic examination. There are also problems concerning complete tumor ablation. We performed thoracoscopic thermal ablation therapy for HCC located just beneath the diaphragm in nine patients with advanced liver cirrhosis.

PATIENTS AND METHODS

Eight patients underwent thoracoscopic microwave coagulation therapy, and one patient underwent thoracoscopic radiofrequency ablation therapy.

RESULTS

Despite the poor hepatic reserve, postoperative recovery after thoracoscopic thermal ablation therapy was rapid in all patients, without deterioration of hepatic function.

CONCLUSIONS

This preliminary study suggests that the new technique of thoracoscopic thermal ablation therapy is a less invasive optional therapy for HCC located in segments VII or VIII in cirrhotic patients.

Reduced C-terminal Src kinase activity is correlated inversely with pp60(c-src) activity in colorectal carcinoma

BACKGROUND

Specific kinase activity of the proto-oncogene product pp60(c-src) is reported to be elevated in patients with carcinoma of the colon, and a novel cytoplasmic protein-tyrosine kinase, C-terminal Src kinase (Csk), has been found to inactivate the members of the Src family protein-tyrosine kinase. In this study, Csk activity and pp60(c-src) activity were examined in colorectal tumors as well as in colon carcinoma cell lines.

METHODS

Colorectal carcinoma tissue and adjacent nonneoplastic tissue from 24 patients, from 8 colon carcinoma cell lines, and from 1 normal colon cell line were used. The levels of pp60(c-src) and Csk in colorectal tissue and cell lines were analyzed by Western and/or Northern blot analysis, and their kinase activity levels were measured by in-gel kinase assay.

RESULTS

In the samples from 24 patients with colorectal carcinoma, pp60(c-src) kinase activity and protein levels were increased by 7.8 +/- 0.55 and 2.6 +/- 0.13 times the control levels, respectively. Conversely, the Csk protein level and its kinase activity were reduced by 0.53 +/- 0.08 and 0.53 +/- 0.09 times the control levels, respectively. pp60(c-src) kinase activity was correlated inversely with Csk activity (correlation coefficient = -0.71; P < 0.0001). Of the cell lines, pp60(c-src) kinase activity and protein levels, respectively, were 7.4 +/- 1.22 and 1.86 +/- 0.28 times greater than normal control levels. Csk protein level and kinase activity, respectively, were 0.54 +/- 0.13 and 0.52 +/- 0.11 times less normal control levels and were correlated with mRNA amount.

CONCLUSIONS

Csk mRNA, protein, and its kinase activity were reduced in colorectal carcinoma and were correlated with pp60(c-src) kinase activity level. The reduced activity of Csk may be involved in the transformation of a subset of colorectal carcinoma.

Design and synthesis of novel benzofurans as a new class of antifungal agents targeting fungal N-myristoyltransferase. Part 1

Potent and selective Candida albicans N-myristoyltransferase (CaNmt) inhibitors have been identified through optimization of a lead compound 1 discovered by random screening. The inhibitor design is based on the crystal structure of the CaNmt complex with compound (S)-3 and structure-activity relationships (SARs) have been clarified. Modification of the C-4 side chain of 1 has led to the discovery of a potent and selective CaNmt inhibitor 11 (RO-09-4609), which exhibits antifungal activity against C. albicans in vitro.

Reduced C-terminal Src kinase activity is correlated inversely with pp60(c-src) activity in colorectal carcinoma

BACKGROUND

Specific kinase activity of the proto-oncogene product pp60(c-src) is reported to be elevated in patients with carcinoma of the colon, and a novel cytoplasmic protein-tyrosine kinase, C-terminal Src kinase (Csk), has been found to inactivate the members of the Src family protein-tyrosine kinase. In this study, Csk activity and pp60(c-src) activity were examined in colorectal tumors as well as in colon carcinoma cell lines.

METHODS

Colorectal carcinoma tissue and adjacent nonneoplastic tissue from 24 patients, from 8 colon carcinoma cell lines, and from 1 normal colon cell line were used. The levels of pp60(c-src) and Csk in colorectal tissue and cell lines were analyzed by Western and/or Northern blot analysis, and their kinase activity levels were measured by in-gel kinase assay.

RESULTS

In the samples from 24 patients with colorectal carcinoma, pp60(c-src) kinase activity and protein levels were increased by 7.8 +/- 0.55 and 2.6 +/- 0.13 times the control levels, respectively. Conversely, the Csk protein level and its kinase activity were reduced by 0.53 +/- 0.08 and 0.53 +/- 0.09 times the control levels, respectively. pp60(c-src) kinase activity was correlated inversely with Csk activity (correlation coefficient = -0.71; P < 0.0001). Of the cell lines, pp60(c-src) kinase activity and protein levels, respectively, were 7.4 +/- 1.22 and 1.86 +/- 0.28 times greater than normal control levels. Csk protein level and kinase activity, respectively, were 0.54 +/- 0.13 and 0.52 +/- 0.11 times less normal control levels and were correlated with mRNA amount.

CONCLUSIONS

Csk mRNA, protein, and its kinase activity were reduced in colorectal carcinoma and were correlated with pp60(c-src) kinase activity level. The reduced activity of Csk may be involved in the transformation of a subset of colorectal carcinoma.

[HCV proteins suppress translation]

Viruses influence host cell protein synthesis in various ways. There are many reports that viral infections inhibit host cell translation, in a process called 'translational shutoff'. In most cases, viral translational shutoff gives an advantage to virus survival because host cell translation is suppressed and the translational machinery is used to translate viral RNA instead. However, there are few reports on the effects of hepatitis C virus (HCV) infection on protein synthesis, because of the lack of a reproducible tissue culture system for HCV. We found that HCV also have the effect of translational inhibition. This novel function may help HCV survival.

Helicobacter pylori induced transactivation of SRE and AP-1 through the ERK signalling pathway in gastric cancer cells

BACKGROUND AND AIMS

Helicobacter pylori infection induces expression of proinflammatory cytokines such as interleukin (IL)-8 and tumour necrosis factor alpha (TNF-alpha) in gastric mucosa, and their genes have AP-1 binding sites in the promoter region. c-Fos is important for transactivation of AP-1 which has SRE in the promoter region. We conducted this study to confirm H pylori induced transactivation of these binding sites.

METHODS

Transactivation of SRE and AP-1 was evaluated in human gastric cancer cells TMK1 and MKN45 by luciferase reporter assay in transient transfection. We compared the effects of coculture with four H pylori strains, a cag pathogenicity island (PAI) positive strain TN2, its isogenic vacA negative (TN2-DeltavacA) or cagE negative (TN2-DeltacagE) mutants, and a cag PAI negative clinical isolate T68. Phosphorylation of ERK1/2, JNK, and c-Jun was measured by immunoblot, induction of IL-8 secretion by ELISA, and the effects of MEK by inhibitor U0126.

RESULTS

Both SRE and AP-1 were transactivated by coculture with TN2. Although TN2-DeltavacA induced comparable transactivation, TN2-DeltacagE and T68 showed decreased transactivation of SRE (65% and 51%) and AP-1 (71% and 54%, respectively, of TN2). Heat killed TN2 or indirect contact using a permeable membrane inhibited transactivation. Levels of phosphorylated ERK1/2, JNK, and c-Jun were increased by coculture with TN2. MEK inhibitor U0126 reduced TN2 induced transactivation of SRE and AP1, as well as secretion of IL-8, by 83%, 87%, and 53%, respectively, of TN2.

CONCLUSIONS

Transactivation of SRE and AP-1, through ERK/MAPK and JNK/SAPK cascades, respectively, was found in gastric cancer cells cocultured with H pylori. Direct contact with viable bacteria possessing intact cag PAI is a prerequisite for the onset of intracellular signalling leading to AP-1 transactivation.