Alteration of the <Emphasis Type="Italic">p14</Emphasis><Superscript><Emphasis Type="Italic">ARF</Emphasis></Superscript> gene and p53 status in human hepatocellular carcinomas

Background The INK4a/ARF locus encodes p16^INK4a and p14^ARF, both of which are crucial for two tumor suppressor pathways, retinoblastoma (RB)/p16^INK4a and p53/ARF. Inactivation of RB/p16^INK4a was frequently reported, but alterations of the p14^ARF gene in hepatocellular carcinoma (HCC) in the Japanese population have been insufficiently analyzed.Methods To determine the role of p53/ARF alteration in hepatocarcinogenesis, we examined 44 HCCs for mRNA expression, deletion, mutation, and promoter hypermethylation of the p14^ARF gene; alterations of p53 were also analyzed in the same series of HCCs.Results Homozygous deletion, spanning from exon 1 to exon 2, was found in 1 HCC mutations within exon 2 were found in 2 HCCs, but no promoter hypermethylation was detected. All 3 HCCs with p14^ARF alteration were well differentiated. Twelve of the 44 HCCs (27.2%) showed immunohistochemical evidence of p53 alteration; however, only 1 of the tumors with p53 alteration was well differentiated. TaqMan polymarase chain reaction (PCR) indicated that the expression of p14^ARF in HCCs was higher than in that in all but three of the corresponding non-tumorous tissues (P < 0.0001), and increased expression of p14^ARF seemed to be associated with poorly differentiated phenotype. Absence of p14^ARF expression was seen in only one HCC, with homozygous deletion of the p14^ARF gene.Conclusions Compared with p53 alteration, p14^ARF alteration does not occur frequently, but may play a role in a subset of Japanese HCCs in the early stage of hepatocarcinogenesis. On the other hand, overexpression of p14^ARF was frequently observed in HCC, especially in poorly differentiated tumors, probably reflecting oncogenic stimuli in these tumors.     

Aberrant methylation of <Emphasis Type="Italic">p16</Emphasis> predicts candidates for 5-fluorouracil-based adjuvant therapy in gastric cancer patients

Background Aberrant methylation of some cancer-related genes has been reported to correlate with sensitivity to chemotherapeutic agents. The present study was designed to determine whether DNA methylation in six cancer-related genes affects recurrence of gastric cancer in patients who received 5-fluorouracil-based adjuvant chemotherapy. Methods The methylation status of six genes, MGMT, CHFR, hMLH1, p16INK4a, E-cadherin, and Runx3, was analyzed in 56 surgically resected gastric cancer tissue specimens by methylation-specific polymerase chain reaction. Of the 56 patients who underwent surgical resection, 38 received 5-fluorouracil (5-FU)-based adjuvant chemotherapy postoperatively (adjuvant group), whereas the other 18 (32%) did not (surgery group). Results There were no significant differences between the two groups with respect to sex, cancer differentiation, depth of tumor invasion, lymph node metastasis, lymphatic invasion, vascular invasion and tumor stage. Among the genes, methylation of p16INK4a showed a significant correlation with longer survival in the 38 patients of the adjuvant group, but not in the 18 patients of the surgery group. A multivariate analysis identified p16INK4a methylation to be an independent factor predicting a longer recurrence-free period under 5-FU-based adjuvant chemotherapy. Conclusions The present study demonstrated for the first time that gastric cancer patients with p16INK4a methylation specifically benefit from 5-FU-based adjuvant chemotherapy.     

Methylation status of p16INK4A tumor suppressor gene in Iranian patients with sporadic breast cancer

Introduction   p16 ^INK4A is a tumor suppressor encoding the Cdk inhibitor protein, which acts to repress Cdk4/6 and pRb phosphorylation. p16 ^INK4A gene can be inactivated by a variety of events, including promoter hypermethylation. Materials and methods  To investigate the methylation status of the p16 ^INK4A gene in Iranian patients with breast carcinoma, promoter methylation was studied by methylation-specific PCR (MSP) and restriction enzyme-related PCR (REP). In addition, p16 ^INK4A promoter was analyzed by PCR-SSCP in order to detection of mutation and single nucleotide polymorphisms. Results  Analysis of 70 patients by MPS and REP showed hypermethylation of p16 ^INK4A promoter in 35.7% (25/70) and 40% (28/70) of samples, respectively. Comparison of the molecular data and pathological information of the samples suggested that p16 ^INK4A gene might be inactivated at the early stages in breast cancer. Conclusion  Therefore, it could be suggested that hypermethylation of p16 ^INK4A promoter is one of the epigenetic factors affecting the progress of sporadic breast carcinogenesis in Iranian patients.     

Comparison between the <Superscript>13</Superscript>C-urea breath test and stool antigen test for the diagnosis of childhood <Emphasis Type="Italic">Helicobacter pylori</Emphasis> infection

Background As noninvasive tests for Helicobacter pylori infection, the ¹³C-urea breath test (UBT) and stool antigen test have been widely used. In children, however, there are few studies reporting which test shows superior performance. The purpose of this study was to compare the ¹³C-UBT and stool antigen test for their accuracy in diagnosing H. pylori infection in children.Methods A total of 123 Japanese children, ages 2 to 17 years (mean, 12 years) who underwent gastric biopsies for H. pylori infection were studied. The diagnoses included gastritis (n = 55), gastric ulcer (n = 5), duodenal ulcer (n = 20), iron-deficiency anemia (n = 7), and other conditions (n = 36). The cutoff value of the ¹³C-UBT was defined to be 3.5. The stool antigen test was performed using the HpSA enzyme-linked immunosorbent assay (ELISA) (Premier Platinum HpSA). In 16 patients who received eradication therapy, the ¹³C-UBT and HpSA were repeated 2 months after treatment.Results Based on biopsy tests, 60 children were infected with H. pylori and 63 children were not. For the ¹³C-UBT, the sensitivity, specificity, and accuracy were 95.0% (95% confidence interval [CI], 86.1%–99.0%), 98.4% (95% CI, 91.5%–100%), and 96.4% (95% CI, 93.6%–99.9%), respectively. For the HpSA, the sensitivity, specificity, and accuracy were 98.3% (95% CI, 90.8%–100%), 98.4% (95% CI, 91.2%–100%), and 98.3% (95% CI, 96.0%–100%), respectively. There were no significant differences between the performance of these two tests. In the assessment of H. pylori eradication, the results of ¹³C-UBT and HpSA agreed with those of biopsy tests.Conclusions The ¹³C-UBT and the HpSA are equally accurate for the diagnosis of active H. pylori infection in Japanese children.Kazuie Iinuma, for the Japanese Pediatric Helicobacter study Group     

Expression of p16<Superscript>INK4A</Superscript> gene in human pituitary tumours

Pituitary adenomas comprise 10–15% of primary intracranial tumours but the mechanisms leading to tumour development are yet to be clearly established. The retinoblastoma pathway, which regulates the progression through the cell cycle, is often deregulated in different types of tumours. We studied the cyclin-dependent kinase inhibitor p16^INK4A gene expression at mRNA level in human pituitary adenomas. Forty-six tumour specimens of different subtypes, 21 clinically non-functioning, 12 growth hormone-secreting, 6 prolactin-secreting, 6 adrenocorticotropin-secreting, and 1 thyrotropin-secreting tumours were studied. All clinically non-functioning and most of the hormone-secreting tumours were macroadenomas (38/46). The RT–PCR assay and electrophoresis of the PCR-products showed that p16^INK4A mRNA was undetectable in: 62% of non-functioning, 8% of growth hormone-secreting, 17% of prolactin-secreting and 17% of adrenocorticotropin-secreting adenomas. Forty percent of all macroadenomas and 25% of microadenomas had negative p16^INK4A mRNA, the latter results suggest that the absence of p16^INK4A product might be an early event in tumours with no expression of this suppressor gene. Within the non-functioning adenomas 63% were “null cell” and 37% were positive for some hormone, both subgroups showed similar percentage of cases with absence of p16^INK4A mRNA. Our results show that clinically non-functioning macroadenomas have impaired p16^INK4A expression in a clearly higher proportion than any other pituitary tumour subtype investigated. Other regulatory pathways may be implicated in the development of tumours with positive p16^INK4A expression.     

Association of <Emphasis Type="Italic">Lewis</Emphasis> and <Emphasis Type="Italic">Secretor</Emphasis> gene polymorphisms and <Emphasis Type="Italic">Helicobacter pylori</Emphasis> seropositivity among Japanese-Brazilians

Background Secretor (Se) and Lewis (Le) genes are involved in the synthesis of Lewis b (Le^b) and type I antigens throughout the body, especially in the epithelial cells of gastric mucosa. Helicobacter pylori can attach to the gastric epithelial cells with the blood group antigen-binding adhesin, which binds to Le^b or H type I carbohydrate structures. In a previous study, a marked association between H. pylori seropositivity and polymorphism of the Se and Le genes was observed among Japanese outpatients of a gastroenterology clinic. The present work aims to investigate the associations between Se and Le gene polymorphisms and H. pylori infection among Japanese-Brazilians.Methods The subjects consisted of 942 healthy volunteer Japanese-Brazilians, who were tested for the presence of anti-H. pylori IgG antibodies and genotyped for Se and Le polymorphisms.Results The sex-age-adjusted odds ratios (aORs) for H. pylori seropositivity were 0.99 for the Sese genotype relative to the SeSe genotype (95% confidence interval [CI], 0.73–1.33), and 1.03 for sese relative to SeSe (95% CI, 0.71–1.48). On the other hand, the aOR for the subjects with the le allele (Lele or lele) relative to the LeLe genotype was 1.48 (95% CI, 1.07–1.79). When the Se and Le genotypes were analyzed in combination according to risk group, no statistically significant association was observed.Conclusions These results are inconsistent with previous work and may have been modulated by an external factor or some other unidentified factor. Japanese-Brazilians are genotypically the same as Japanese, but their lifestyle is adapted to that of Brazil. Further investigations are necessary to clarify this influence on susceptibility to H. pylori infection.     

The hypermethylation and protein expression of p16 INK4A and DNA repair gene O6-methylguanine-DNA methyltransferase in various uterine cervical lesions

Purpose This study is aimed at investigating the significance of gene promoter methylation status and protein expression of p16 ^INK4A and O⁶-methylguanine-DNA methyltransferase (MGMT) in the various uterine cervical lesions.Materials and methods Methylation status by using methylation-specific polymerase chain reaction (MS-PCR) and protein expression by using immunohistochemistry for p16 ^INK4A and MGMT genes were performed in cervical squamous intraepithelial neoplasms (CIN), invasive squamous cell carcinomas (SCC), adenocarcinomas and non-neoplastic cervices.Results None of 20 non-neoplastic cervices showed p16 ^INK4A and MGMT gene hypermethylation, whereas at least one of these genes was hypermethylated with 50.0% (5/10) of CIN I, 65.0% (13/20) of CIN II–III, 70.2% (33/47) of SCC and 85.0% (17/20) of adenocarcinoma. p16 ^INK4A protein was totally negative in non-neoplastic cervices, but positive with 90.0% of CIN I, 100% of CIN II–III and adenocarcinoma, and 78.7% of SCC. MGMT protein was expressed in 10% of non-neoplastic cervices, but significantly increased in SCC (42.5%) and adenocarcinoma (70.0%). The protein expression of p16 ^INK4A and MGMT was not related to their gene promoter methylation status.Conclusions The hypermethylation of p16 ^INK4A and MGMT genes in the uterine cervix may indicate the presence of malignant cells, and p16 ^INK4A immunostaining is useful in grading CIN and diagnosing invasive SCC and adenocarcinoma.     

Mutational analysis of serotonin receptor genes: <Emphasis Type="Italic">HTR3A</Emphasis> and <Emphasis Type="Italic">HTR3B</Emphasis> in fibromyalgia patients

The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) has been implicated in numerous human disorders. Dysfunction of serotonergic neurotransmission is thought to play a major role in the pathophysiology of the fibromyalgia syndrome (FMS) which is characterised by non-restorative sleep and severe pain. In our study, both serotonin receptor subunit genes, HTR3A and HTR3B, have been investigated for sequence variations in FMS patients in order to reveal a possible involvement in the aetiology of FMS. We examined DNA samples from 48 patients with FMS representing sporadic cases by single-strand conformation polymorphism (SSCP) and denaturing high-performance liquid chromatography (dHPLC) analysis, sequenced samples with conspicuous patterns and performed statistical calculations. HTR3A mutational analysis revealed one novel as well as five known sequence variations. Investigating HTR3B, we detected seven formerly described mutations and one novel sequence variant. Statistical computation rated all variants as probably non-disease-related polymorphisms. Nevertheless, one might speculate about an effect of the respective sequence variants on the severity of the disease. Sequence variants of the serotonin receptor subunit genes HTR3A and HTR3B indicate no obvious significance in the aetiology of fibromyalgia, yet they represent the basis for future studies on their pharmacogenetic relevance.     

Aberrant methylation of <Emphasis Type="Italic">SOCS-1</Emphasis> was observed in younger colorectal cancer patients

Background Recently, it was demonstrated that suppressor of cytokine signaling-1 (SOCS-1) was frequently silenced by methylation of its CpG island in human hepatocellular carcinoma (HCC). To define the role of SOCS-1 in the tumorigenic pathway of the colorectum, we examined the methylation of SOCS-1 in tumors of colorectal cancer patients.Methods We examined 74 colorectal cancer patients, using a methylation-specific polymerase chain reaction (PCR; MSP) for SOCS-1 CpG island in primary tumors.Results Aberrant methylation of the SOCS-1 CpG island was detected in 6 of the 74 (8%) colorectal cancer specimens. No corresponding normal colorectal tissues showed SOCS-1 methylation. We then analyzed the correlation between the clinicopathological features and SOCS-1 aberrant methylation and found that younger age was significantly related to SOCS-1 methylation (P = 0.048).Conclusions These findings suggested that SOCS-1 may act as a tumor suppressor in at least some colorectal cancers and that SOCS-1 methylation may be a particular phenomenon related to an early onset of colorectal cancer.     

Novel <Emphasis Type="Italic">hMSH</Emphasis>2, <Emphasis Type="Italic">hMSH</Emphasis>6 and <Emphasis Type="Italic">hMLH</Emphasis>1 gene mutations and microsatellite instability in sporadic colorectal cancer

Purpose To detect the hMSH2, hMSH6 and hMLH1 DNA mismatch repair gene mutations and microsatellite instability in somatic colorectal cancer.Patients and methods The mutations of hMSH2, hMSH6, and hMLH1 genes, including microsatellite instability of BAT-26, BAT-40, D2S123, D5S346 and D17S250 were analyzed in 31 patients with colorectal.Results The results revealed that eight cases (25.8%) harbored mutations in DNA mismatch repair genes. Of these, five novel mutations including I237V in exon 4 of hMSH2, ins T at codon 1196 in exon 7 of hMSH6, and ins G at codon 154 in exon 6, N158H in exon 6, and del A at codon 257 in exon 9 of hMLH1 were identified. Moreover, several intronic polymorphisms, including c–g transversion at IVS-1 nt211 + 9 of hMSH2, del T in poly T track at IVS-6 nt3559-5, ATCT duplicate in IVS-7 nt 3642 + 35 and t–g transversion at IVS-10 nt4080 + 185 of hMSH6 were demonstrated in these patients. In addition, seven cases (22.5%) exhibited microsatellite instability (MSI).Conclusion These results suggested that the inactivation of DNA mismatch repair genes and microsatellite instability may play a minor role in somatic colorectal cancer development.     

<Superscript>13</Superscript>C-Urea Breath Test for Success of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Eradication: Study of 5885 Israeli Patients.

Helicobacter pylori (Hp) infection is highly prevalent in many countries and may cause gastritis, peptic ulcer disease, gastric cancer, and lymphoma. Successful eradication depends on the specific treatment used, patient compliance, and Hp antibiotic resistance. The primary aim was to characterize groups of patients with one or more failures of Hp eradication treatment. The secondary aim was to evaluate the factors that influence eradication failure. Between April 1, 1998, and December 31, 2001, 5885 patients were studied for the success of Hp eradication with the ¹³C-urea breath test (¹³C-UBT): 5442 after one course of treatment (Group I), 380 after two courses (Group II), and 63 after three courses (Group III). The ¹³C-UBT was positive in 27.8%, 37.4%, and 47.6% of patients in Groups I, II, and III, respectively (P_I-II = 0.000, P_II-III = 0.126). A combination of omeprazole, amoxicillin, and clarithromycin (OAC) was used in 31.3%, 27.4%, and 7.9% of Groups I, II, and III, respectively, and a combination of omeprazole, amoxicillin, and metronidazole (OAM) in 15.2%, 28.9%, and 28.6%, respectively. Regimens that contained clarithromycin were used in decreasing order in Groups I, II, and III, and regimens containing metronidazole, bismuth, or tetracycline, in increasing order. The only good prognostic factor for successful eradication was Israeli origin, while European–American and Asian–African origin, recurrence of symptoms, a history of duodenal ulcer, and chronic proton pump inhibitor (PPI) use did not favor successful eradication. Our results suggest that origin, history of peptic disease, and chronic PPI use are predictors of eradication failure.     

Abnormalities of tumor suppressor gene <Emphasis Type="Italic">p16</Emphasis>in pancreatic carcinoma: immunohistochemical and genetic findings compared with clinicopathological parameters

Background. Abnormalities of the tumor suppressor gene p16 have been reported in a variety of human tumors but are rare in pancreatic carcinoma except for cancer cell lines and xenografts. Their clinicopathological significance remains unknown. The purpose of this study was to examine immunohistochemical and genetic alterations of p16 in primary pancreatic carcinoma tissues and to investigate the relation between abnormalities of p16 and clinicopathological parameters to elucidate their clinicopathological significance. Methods. We investigated p16 expression in 60 pancreatic carcinoma cases by immunohistochemistry using a monoclonal antibody clone G175-405. In addition, we analyzed genetic alterations of the p16 gene using DNA extracted from microdissected tissue of pancreatic carcinoma, by polymerase chain reaction, nonradioisotopic single-strand conformation polymorphism (non-RI-SSCP), DNA sequencing, and hypermethylation analyses using restriction enzymes. We compared the abnormalities of p16 alterations with clinicopathological parameters to elucidate their significance. Results. On immunohistochemical study, staining for p16 protein was strongly positive in 22 (37%) of 60 pancreatic carcinoma cases, weakly positive in 24 (40%), and negative in 14 (23%). In contrast, p16 mutations were recognized in 9 (15%) of the 60 pancreatic carcinoma cases. The incidence of p16 mutations was 2 (9%) in 22 cases of pancreatic carcinoma with strongly positive staining, 4 (17%) in 24 with weakly positive staining, and 3 (21%) in 14 with negative staining. Hypermethylation of p16 was detected in the two pancreatic carcinoma cases with weakly positive staining, although homozygous deletions were not found in any case. There was no significant correlation between the expression of p16 protein and any of the clinicopathological parameters. However, there was a tendency for the tumor to be larger in patients with decreased expression of p16 protein than in those with normal expression levels. In contrast, the tumor was significantly larger and the survival period significantly shorter for patients with pancreatic carcinoma with p16 mutation or hypermethylation than for those with pancreatic carcinoma with an intact p16 gene (P 0.05). Conclusions. These findings suggest that p16 alterations may participate in the aggressiveness of pancreatic carcinoma.     

Increased <Emphasis Type="Italic">C-MYC</Emphasis> copy numbers on the background of <Emphasis Type="Italic">CDKN2A</Emphasis> loss is associated with improved survival in nodular melanoma

Purpose In order to obtain better insight into the genetic background of nodular melanoma (NM), we aimed to analyse the frequency of CDKN2A and C-MYC copy number changes. The impact of these aberrations on the metastatic potential and patient’s survival was considered.Methods Fluorescent in situ hybridization was used to analyse the C-MYC and CDKN2A genes on isolated nuclei from 49 paraffin-embedded primary NMs.Results Thirty-six (73.47%) melanoma samples showed CDKN2A deletion while 11 of these 36 (22.45%) additionally displayed C-MYC increased copy numbers. Cases positive for metastases more commonly displayed CDKN2A deletions. However, the combined C-MYC and CDKN2A aberrations were found predominantly in the non-metastasizing group of primary NM. The survival analysis furthermore demonstrated that patients with combined CDKN2A and C-MYC aberrations have a significantly better prognosis than carriers of CDKN2A deletion only.Conclusions We conclude that the C-MYC increased copy number changes on the background of CDKN2A deletions seem to be related to a low metastatic potential and better patients’ outcome in primary NMs.     

Alterations of tumor suppressor gene <Emphasis Type="Italic">p16</Emphasis><Superscript><Emphasis Type="Italic">INK4a</Emphasis></Superscript>in pancreatic ductal carcinoma

Background  

Cell cycle inhibitor and tumor suppressor gene p16 / MTS-1 has been reported to be altered in a variety of human tumors. The purpose of the study was to evaluate primary pancreatic ductal adenocarcinomas for potentially inactivating p16 alterations.     

Joint effects of HLA, <Emphasis Type="Italic">INS</Emphasis>, <Emphasis Type="Italic">PTPN22</Emphasis> and <Emphasis Type="Italic">CTLA4</Emphasis> genes on the risk of type 1 diabetes

Background/hypothesis HLA, INS, PTPN22 and CTLA4 are considered to be confirmed type 1 diabetes susceptibility genes. HLA, PTPN22 and CTLA4 are known to be involved in immune regulation. Few studies have systematically investigated the joint effect of multiple genetic variants. We evaluated joint effects of the four established genes on the risk of childhood-onset type 1 diabetes. Methods We genotyped 421 nuclear families, 1,331 patients and 1,625 controls for polymorphisms of HLA-DRB1, −DQA1 and −DQB1, the insulin gene (INS, −23 HphI), CTLA4 (JO27_1) and PTPN22 (Arg620Trp). Results The joint effect of HLA and PTPN22 on type 1 diabetes risk was significantly less than multiplicative in the case-control data, but a multiplicative model could not be rejected in the trio data. All other two-way gene–gene interactions fitted multiplicative models. The high-risk HLA genotype conferred a very high risk of type 1 diabetes (OR 20.6, using the neutral-risk HLA genotype as reference). When including also intermediate-risk HLA genotypes together with risk genotypes at the three non-HLA loci, the joint odds ratio was 61 (using non-risk genotypes at all loci as reference). Conclusion Most established susceptibility genes seem to act approximately multiplicatively with other loci on the risk of disease except for the joint effect of HLA and PTPN22. The joint effect of multiple susceptibility loci conferred a very high risk of type 1 diabetes, but applies to a very small proportion of the general population. Using multiple susceptibility genotypes compared with HLA genotype alone seemed to influence the prediction of disease only marginally. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Ile<Superscript>105</Superscript>Val <Emphasis Type="Italic">GSTP1</Emphasis> polymorphism and susceptibility to colorectal carcinoma in Bulgarian population

Background and aims Etiologically, the sporadic colorectal cancer (CRC) is a complex and multifactorial disease that is linked to both exogenic and endogenic factors. Accumulating evidence indicates that susceptibility to cancers, including CRC, is mediated by genetically determined differences in the effectiveness of detoxification of potential carcinogens. A member of the glutathione-S-transferase (GST) family, GSTP1, is an important candidate for involvement in susceptibility to carcinogen-associated CRC. An A→G transition in exon 5 of the GSTP1 gene resulting in Ile¹⁰⁵Val amino acid substitution has been identified. This change leads to alteration in catalytic efficiency of variant enzyme. The aim of the current study was to evaluate the influence of Ile¹⁰⁵Val GSTP1 polymorphism on susceptibility to CRC. Materials and methods The GSTP1 genotyping was conducted in a case-control study of 80 ethnic Bulgarian CRC patients and 126 unaffected controls using polymerase chain reaction restriction fragment length polymorphism method. Results A statistically significant case-control difference in genotype frequencies was observed: 0.69 vs 0.54 for Ile/Ile, 0.22 vs 0.39 for Ile/Val, and 0.09 vs 0.07 for Val/Val (p = 0.049). The odds ratio (OR) for Val/Val was close to 1 (0.96, 95%CI: 0.35–2.66, p = 0.942), whereas the OR for Ile/Val was significantly lower, 0.45 (95%CI: 0.24–0.86, p = 0.016), compared to the referent Ile/Ile genotype. Although a prevalence of the GSTP1 variant allele-containing genotypes (Ile/Val or Val/Val) was found in controls than in patients (OR = 0.53, 95%CI: 0.30–0.96, p = 0.035), the allele frequencies did not show significant difference between cases and controls (p = 0.127). Conclusions Based on the obtained protective effect of Ile/Val GSTP1 genotype, we could suggest that Ile¹⁰⁵Val GSTP1 polymorphism may play some role in susceptibility to CRC.     

Methylation of the <Emphasis Type="Italic">hMLH1</Emphasis> and <Emphasis Type="Italic">hMSH2</Emphasis> promoter in early-onset sporadic colorectal carcinomas with microsatellite instability

BACKGROUND AND AIMS: Microsatellite instability (MSI) occurring from defects in mismatch repair has been found to be associated with about 15% of sporadic colorectal carcinomas. This study examined the incidence of MSI in early-onset sporadic colorectal carcinomas and the role of methylation of the hMLH1 and hMSH2 promoter in sporadic colorectal carcinoma presenting with MSI. PATIENTS AND METHODS: MSI in 38 early-onset and 40 late-onset sporadic colorectal carcinomas were determined as MSI-H, MSI-L, and MSS using five markers. Methylation of the promoter region in hMLH1 and hMSH2 was assessed using methylation-specific PCR (MSP). Their protein expressions were also identified on immunohistochemical staining. RESULTS: MSI-H, MSI-L, and MSS were found in six (15.8%), three (7.9%), and 29 (76.3%) cases, respectively, in the early-onset group, and in one (2.5%), five (12.5%), and 34 (85%) cases in the late-onset group. Five cases (71.4%) of MSI-H and two cases (25%) of MSI-L showed methylation of the promoter region in hMLH1. No cases with methylation of the promoter region expressed the hMLH1 protein. Only one case of MSI-H showed methylation of the promoter region in hMSH2 with lack of expression of hMSH2. CONCLUSION: The mutator pathway in colorectal carcinogenesis appeared more frequently in early-onset than in late-onset colorectal carcinoma. Many cases with MSI in sporadic colorectal carcinoma may be associated with methylation of the promoter in hMLH1.     

<Emphasis Type="Italic">cagA</Emphasis> Gene and Protein Status Among Iranian <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Strains

The wide geographic genetic diversity of Helicobacter pylori (Hp) and, in particular, the varying prevalence of cagA in different countries has been documented repeatedly. This study was designed to determine the frequency of cagA in Iranian Hp strains by means of genotyping and assessment of host antibodies. Helicobacter pylori strains from 235 patients, including 174 non-ulcer dyspepsia, 25 peptic ulcer and 36 gastric cancer patients, were studied. The frequencies of the 5′, middle and 3′ terminal regions of the cagA gene were 90.6, 57.6, 89%, respectively, with no correlation to the clinical outcomes. Antibodies against the CagA protein were present in 90.7% of patients. Multiple biopsy sampling in 97 cases revealed multiple infection in 16.5% of the patients. Sequencing of the seven variants of the 3′ end of the cagA gene revealed no clustering and the distribution of the Iranian strains among those of other countries. Our results from the genotyping and serology analyses confirm that the majority of Iranian Hp strains are cagA-positive.     

Colorectal carcinoma prognosis can be predicted by alterations in gene <Emphasis Type="Italic">p53</Emphasis> exons 5 and 8

Background and aims Gene p53 alteration is a genetic event described in the progression from adenoma to colorectal carcinoma. Most of the p53 mutations occur in exons 5 to 8 in highly preserved regions and in the three main structural domains of the p53 protein. It is possible that mutations affecting different structural regions may present different effects on the p53 protein function and, due to this, they may have different prognostic meaning. Materials and methods The study population consisted of 353 patients diagnosed with sporadic colorectal cancer. Mutations in 5–8 exons of p53 gene were detected by means of single strand conformation polymorphism (SSCP). All samples that showed different migration bands in SSCP were confirmed by sequencing. Results A total of 69 patients (19.7%) showed alterations of the gene p53. It was observed that mutation in codon 175 in exon 5 was related to tumors located in the colon (p = 0.01) and the mutation in the codon 288 in exon 8 was related to rectal tumors (p = 0.02). In the study of overall survival, mutation in codon 175 of exon 5 conferred a better prognosis and alterations of exon 8 were related to a worse prognosis in different population subgroups: in men, in patients younger than 71 years old, in the tumors located in the proximal colon, the ones moderately differentiated, and those that are mucinous. Conclusion According to this study, mutations in different exons of p53 are related to different phenotypes in colorectal cancer. These phenotypes could mean differences in the clinical evolution of the patients. This study was supported by grant no. PI030514 from the Fondo de Investigaciones Sanitarias, Spain.