Aberrant promoter methylation is an important mechanism for gene silencing. In the present study, 50 Barrett's esophagus-associated esophageal adenocarcinomas (ADC), 50 cardiac ADC and 50 gastric ADC were investigated by means of methylation-specific real-time PCR for hypermethylation in the tumor suppressor genes APC, p16 INk4A Adenocarcinomas (ADC) of the esophagus and the stomach are characterized by important differences in etiological and clinical background. Whereas the incidence of esophageal ADC has increased in Western countries in the last 30 years, there has been a decrease in gastric ADC incidence during the whole 20th century. 1 Chronic gastroesophageal reflux disease and subsequent development of Barrett's esophagus on the one side and dietary factors, bile reflux and Helicobacter-pylori-infection on the other side are among the most important risk factors for esophageal or gastric ADC, respectively. 2,3 The position of cardiac ADC in this context is less clear. Although traditionally considered as a gastric carcinoma, cardiac ADC shares a number of features with esophageal ADC such as profound male predominance, rising incidence and etiological association with chronic gastroesophageal reflux. 4,5 Moreover, recent investigations using the comparative genomic hybridization technique showed that genetic aberrations in cardiac ADC are probably more closely correlated to esophageal than to gastric ADC. 6,7 However, the hypothesis that esophageal and cardiac ADC are probably one entity 5 has been contradicted by the results of others. 8 Aberrant DNA methylation is a common feature of human cancer. 9 -12 In recent years, a CpG island hypermethylation profile of tumors has emerged that indicates a tumor type specific methylation pattern at least for some tumor suppressor genes. 13,14 Concerning adenocarcinomas of the upper gastrointestinal tract, previous studies indicate that hypermethylation of the tumor suppressor genes APC and p16 INK4A are prevalent findings in esophageal 15,16 as well as in gastric ADC. 17,18 In contrast, hypermethylation of p14 ARF seems to be substantially less frequent in esophageal ADC 16 than in gastric ADC. 19,20 However, since methylation patterns of esophageal and gastric ADC have not yet been compared within one study, reported differences between both tumor types may be influenced by differences in the methods used for the detection of hypermethylation. Moreover, the prevalence of hypermethylation of APC, p16 INK4A and p14 ARF in cardiac ADC has not been investigated so far. Thus, it is currently unclear whether significant differences in methylation pattern of these tumor suppressor genes exist between esophageal, cardiac and gastric ADC. Furthermore, it is not known whether distinct methylation patterns exist in correlation with the predominant histological subtypes of upper gastrointestinal tract adenocarcinomas (diffuse subtype vs. gland-forming subtype) as it has been recently shown for histological subtypes of lung cancer 21 and breast cancer. 22 In our study, w...

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1 Using methylation-specific real-time PCR, we determined the prevalence of aberrant methylation in the mismatch repair gene hMLH1 and in the recently described HPP1 gene among 50 esophageal, 50 cardiac and 50 gastric ADCs. Additionally, expression of hMLH1 protein was detected immunohistochemically and correlated with DNA MSI. Hypermethylation of hMLH1 was found in 14% of esophageal, 28% of cardiac and 32% of gastric ADCs, whereas HPP1 hypermethylation was found more frequently in the 3 tumor types (64% vs. 38% vs. 54%). In gastric ADC, HPP1 hypermethylation was found more frequently in tumors with concomitant hMLH1 hypermethylation (81%) than in those without hMLH1 hypermethylation (41%, p ‫؍‬ 0.008). Complete loss of hMLH1 protein expression, which was present in 10 carcinomas (5 cardiac and 5 gastric), was invariably correlated with hMLH1 hypermethylation and MSI. In conclusion, our data indicate that MSI and loss of the mismatch repair protein hMLH1, which is mainly caused by hMLH1 gene hypermethylation, are more prevalent in stomach and cardia carcinogenesis than in that of the esophagus. Moreover, in gastric cancer, hMLH1 hypermethylation is correlated with hypermethylation of the HPP1 ADCs of the esophagus and stomach are characterized by important differences concerning etiologic and clinical background. Chronic gastroesophageal reflux disease and subsequent intestinal metaplasia of the esophagus (Barrett's esophagus), on the one side, and Helicobacter pylori infection with subsequent atrophic gastritis, on the other side, are among the most important risk factors for esophageal or gastric ADC, respectively. 1,2 Moreover, the incidence of esophageal ADC has been rising rapidly over the last 3 decades, whereas the incidence of gastric ADC has been declining. 3 Although traditionally considered a gastric carcinoma, cardiac ADC shares a number of features with esophageal ADC, e.g., profound male predominance, rising incidence and etiologic association with chronic gastroesophageal reflux. 4,5 Hypermethylation of CpG islands represents an important epigenetic mechanism for silencing tumor-suppressor genes during carcinogenesis. 6 For example, loss of function of the DNA mismatch repair gene hMLH1 by hypermethylation of its promoter has been described in different cancer types, such as colorectal and endometrial cancers. 6,7 Lack of hMLH1 protein expression strongly decreases the fidelity of DNA replication and has been correlated with MSI, a surrogate marker for the so-called RER phenotype. 8,9 Thus, hypermethylation of hMLH1 has been detected in about 95% of RER-positive gastric ADCs but in only 5% of RER-negative cases. 8 Shibata et al. 10 found an as yet unexplained association between hypermethylation of hMLH1 and HPP1 in a series of 32 gastric ADCs. Currently, only limited data exist about the structural and functional properties of HPP1. It is thought to encode for a cell membrane receptor. The HPP1 protein shares a high grade of structural homology to regulatory proteins of the CNS (i.e., tomoregulin...

Immunosuppressive therapy is the most crucial treatment of organ-transplanted patients. Both cyclosporin and tacrolimus have become a part of the standard immunosuppressive therapy for prevention of rejection. However, lower levels of these drugs are associated with insufficient therapy and eventually result in rejection of the organ, and, on the contrary, higher levels are associated with toxicity to certain organs such as liver and kidneys. Therefore, the levels of these drugs in body fluids should be monitored for the prevention of unwanted situations. In this retrospective study, the authors evaluated the 18-month profile of blood drug concentrations of cyclosporin and tacrolimus in patients admitted to the TDM Unit of the Marmara University Hospital (Istanbul, Turkey) between June 2000 and November 2001. A total of 578 blood samples (347 cyclosporin and 231 tacrolimus) from 134 patients (88 for cyclosporin, 46 for tacrolimus) were evaluated in this period. The therapeutic trough ranges were accepted as 100-350 ng/mL for cyclosporin and 5-20 ng/mL for tacrolimus, and levels below or above the identified levels were accepted to be subtherapeutic or toxic. Most of the results were found within the range of therapeutic levels (67.48% for cyclosporin and 82.71% for tacrolimus). Subtherapeutic levels were found in 19.92% of all cyclosporin and 10.53% of all tacrolimus assays, whereas toxic levels were seen in 12.60% and 6.77% of cyclosporin and tacrolimus results, respectively. In conclusion, this study gives information about the TDM practice in institutional clinical laboratory and also indicates the importance of critical information such as sampling time for individual decision making in dosage regiment.