High frequencies of telomeric associations, chromosome aberrations, and sister chromatid exchanges in ulcerative colitis

Inflammatory Bowel Disease and Colorectal Cancer: Epidemiology, Etiology, Surveillance, and Management

Patients with inflammatory bowel diseases (IBDs), such as ulcerative colitis and Crohn's disease, have an increased risk of developing colorectal cancer (CRC). Although advancements in endoscopic imaging techniques, integrated surveillance programs, and improved medical therapies have contributed to a decreased incidence of CRC in patients with IBD, the rate of CRC remains higher in patients with IBD than in individuals without chronic colitis. Patients with IBD-related CRCs exhibit a poorer prognosis than those with sporadic CRCs, owing to their aggressive histological characteristics and lower curative resection rate. In this review, we present an updated overview of the epidemiology, etiology, risk factors, surveillance strategies, treatment recommendations, and prognosis of IBD-related CRCs.

Treatment with the anti-CD20 monoclonal antibody rituximab mitigates gonadal disruptions in the collagen-induced arthritis in male DBA/1 J mouse model

Rheumatoid arthritis (RA), which is driven by persistent activation of the immune system, primarily affects the joints. Several reports have estimated the risk of gonadal disruptions in arthritic patients, with potential attributable risk factors such as treatments with the disease-modifying antirheumatic drugs and the influence of the disease itself. The FDA approved rituximab, a therapy for non-Hodgkin's lymphoma, for management of RA in February 2006. However, the influence of repeated treatment with rituximab on gonadal function in RA has not been reported yet. Thus, the aim of the presents study is to evaluate whether repeated treatment with the clinically relevant dose of rituximab may change the gonadal disruptions in collagen-induced arthritis in male DBA/1 J mouse, a model of RA. Testicular disruptions, as determined by the sperm DNA strand breaks, spermatocyte chromosomal analysis and spermiogram examination have been conducted by the use of standard techniques. Additionally, we aimed to test whether the anti-rheumatic effect of rituximab also decreases the cellular oxidant-antioxidant imbalance in arthritic male DBA/1 J mice. Repeated treatment of naïve control DBA/1 J mice with rituximab did not exhibit any significant deleterious effects. Moreover, repeated administration of rituximab to the arthritic DBA/1 J mice suppressed disease severity and decreased testicular disruptions. Rituximab treatment also diminished gonadal oxidative stress, through decreasing reactive oxygen species generation and restoring the reduced glutathione level in arthritic DBA/1 J mice. In conclusion, rituximab is a safe therapeutic agent and can mitigate gonadal disruptions induced by arthritis, which insinuates the importance for arthritic patients especially at reproductive age.

Keratin intermediate filaments in the colon: guardians of epithelial homeostasis

Keratin intermediate filament proteins are major cytoskeletal components of the mammalian simple layered columnar epithelium in the gastrointestinal tract. Human colon crypt epithelial cells express keratins 18, 19 and 20 as the major type I keratins, and keratin 8 as the type II keratin. Keratin expression patterns vary between species, and mouse colonocytes express keratin 7 as a second type II keratin. Colonic keratin patterns change during cell differentiation, such that K20 increases in the more differentiated crypt cells closer to the central lumen. Keratins provide a structural and mechanical scaffold to support cellular stability, integrity and stress protection in this rapidly regenerating tissue. They participate in central colonocyte processes including barrier function, ion transport, differentiation, proliferation and inflammatory signaling. The cell-specific keratin compositions in different epithelial tissues has allowed for the utilization of keratin-based diagnostic methods. Since the keratin expression pattern in tumors often resembles that in the primary tissue, it can be used to recognize metastases of colonic origin. This review focuses on recent findings on the biological functions of mammalian colon epithelial keratins obtained from pivotal in vivo models. We also discuss the diagnostic value of keratins in chronic colonic disease and known keratin alterations in colon pathologies. This review describes the biochemical properties of keratins and their molecular actions in colonic epithelial cells and highlights diagnostic data in colorectal cancer and inflammatory bowel disease patients, which may facilitate the recognition of disease subtypes and the establishment of personal therapies in the future.

Effects of infliximab on sister chromatid exchanges and chromosomal aberration in patients with rheumatoid arthritis

The aim of this study was to evaluate in a 24-weeks the effect of anti-TNF-alpha, infliximab, on cytogenetic biomarkers in peripheral lymphocytes of patients with rheumatoid arthritis (RA). A total of 40 patients with RA met the criteria to be treated with methotrexate (15 mg/week) were evaluated. Twenty patients, randomly selected, were treated with infliximab in addition to methotrexate (group I), whereas the other 20 patients continued with only methotrexate treatment (group M). Twenty healthy volunteers matched for age, gender and smoking habits served as control group (group C). At baseline, sister chromatid exchange rate was 7.20 ± 2.21 in group I, 7.40 ± 1.60 in group M and 4.97 ± 1.32 in group C (P < 0.01 vs group I and M). After 24-weeks, sister chromatid exchange rate was 7.87 ± 2.54 in group I and 7.81 ± 1.95 in group M (P = ns). High frequency cells count was 4.9 % and 4.7 % in the groups I and M, respectively, at the end of the study (P = ns). The basal chromosomal aberration frequency was 4.90 % in group I and 5.20 % in groups M; after 24-weeks, this was 5.10 % in group I and 5.10 % in groups M (P = ns). Infliximab treatment, for 24 weeks, did not increase the cytogenetic biomarkers in patients with RA. Our data show that the use of infliximab has not a genotoxic effect in patients with RA.

Molecular Alterations of Colorectal Cancer with Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an important etiologic factor in the development of colorectal cancer (CRC). The risk of CRC begins to increase 8 or 10 years after the diagnosis of IBD. This type of cancer is called colitis-associated CRC (CA-CRC). The molecular pathogenesis of inflammatory epithelium might play a critical role in the development of CA-CRC. Genetic alterations detected in CA-CRC such as genetic mutations, microsatellite instability, and DNA hypermethylation are also recognized in sporadic CRC; however, there are differences in the timing and frequency of molecular events between CA-CRC and sporadic CRC. Interaction between gene-environmental factors, including inflammation, lifestyle, psychological stress, and prior appendectomy, might be associated with the etiopathology of IBD. The mucosal inflammatory mediators, such as oxidant stress, free radicals, and chemokines, may cause the genetic alterations. Understanding the molecular mechanisms of CA-CRC might be important to develop clinical efficacies for patients with IBD. This review discusses the molecular characteristics of CA-CRC, especially ulcerative colitis-associated CRC, including clinical features, signaling pathways, and interactions between genetic alterations and environment involved in inflammatory carcinogenesis.

Ulcerative colitis-associated colorectal cancer

The association between ulcerative colitis (UC) and colorectal cancer (CRC) has been acknowledged. One of the most serious and life threatening consequences of UC is the development of CRC (UC-CRC). UC-CRC patients are younger, more frequently have multiple cancerous lesions, and histologically show mucinous or signet ring cell carcinomas. The risk of CRC begins to increase 8 or 10 years after the diagnosis of UC. Risk factors for CRC with UC patients include young age at diagnosis, longer duration, greater anatomical extent of colonic involvement, the degree of inflammation, family history of CRC, and presence of primary sclerosing cholangitis. CRC on the ground of UC develop from non-dysplastic mucosa to indefinite dysplasia, low-grade dysplasia, high-grade dysplasia and finally to invasive adenocarcinoma. Colonoscopy surveillance programs are recommended to reduce the risk of CRC and mortality in UC. Genetic alterations might play a role in the development of UC-CRC. 5-aminosalicylates might represent a favorable therapeutic option for chemoprevention of CRC.

Chronic ulcerative colitis and colorectal cancer

One of the most important consequences of chronically active ulcerative colitis (UC) or Crohn's disease (CD) - the two major forms of inflammatory bowel disease (IBD) - is the development of colorectal cancer (CRC). An increased risk for the occurrence of CRC in up to 30% of affected patients after 35years of UC has been reported. Recent evidence from population based studies indicates a lower risk. Nevertheless the incidence is still significantly increased as compared to individuals without chronic colitis. Colitis-associated CRC (CAC) does not display the adenoma-carcinoma sequence which is typical for sporadic CRC and the pathophysiology appears to be different. Chronic inflammation and the increased turnover of epithelial cells contribute to the development of low- and high-grade dysplasia which may further transform into CAC. Reactive oxygen species (ROS) generated by the inflammatory infiltrate are thought to contribute to the generation of dysplastic lesions. In sporadic CRC the sequence of mutations that finally lead to malignancy involves early activation of Wnt/β-catenin pathway (in 90% of cases) including mutations in adenomatous polyposis coli (APC) tumor suppressor gene, its regulating kinase GSK3β and β-catenin itself. β-catenin mutations are rarer in CAC and mutations in APC occur rather late during the disease progression, whereas there are earlier mutations in p53 and K-ras. Recent data indicate that the intestinal microbiome and its interaction with a functionally impaired mucosal barrier may also play a role in CAC development. CACs frequently show aggressive growth and early metastases. The treatment of CAC in patients with colitis always includes proctocolectomy with ileoanal anastomosis as meta- or synchronic lesions are frequent.

Feline chronic kidney disease is associated with shortened telomeres and increased cellular senescence

Telomeres are protective structures at the ends of chromosomes that have important implications for aging. To address the question of whether telomeres contribute to feline chronic kidney disease (CKD), we evaluated kidney, liver, and skin samples from 12 cats with naturally occurring CKD, 12 young normal cats, and 6 old normal cats. Telomere length was assessed using standard telomere fluorescent in situ hybridization (TEL-FISH) combined with immunohistochemistry (TELI-FISH) to identify proximal (PTEC) and distal tubular epithelial cells (DTEC), whereas senescence-associated β-galactosidase (SABG) staining was used to evaluate senescence. Results revealed statistically significant decreases in the average telomere fluorescence intensity (TFI) of PTEC in CKD cats compared with young and geriatric normal cats, and in the DTEC of CKD cats compared with young normal cats. When histograms of individual TFI were compared, statistically significant decreases in the PTEC and DTEC of CKD cats were observed compared with young and geriatric normal cats. Concomitantly, a statistically significant increase in SABG staining was seen in CKD kidney samples compared with young normal cats. CKD cats tended to have increased SABG staining in the kidney compared with normal geriatric cats, but this did not reach statistical significance. No significant telomere shortening in liver or skin from any group was observed. Real-time quantitative telomeric repeat amplification protocol assessment of renal telomerase activity revealed comparable low levels of telomerase activity in all groups. Our results suggest that shortened telomeres and increased senescence in the kidneys of CKD cats may represent novel targets for interventional therapy.

Dysplastic lesions in inflammatory bowel disease: molecular pathogenesis to morphology

Context.-Inflammatory bowel disease (IBD) is a long-standing chronic active inflammatory process in the bowel with increased risk for the development of colorectal carcinoma. Several molecular events involved in chronic active inflammatory processes contribute to multistage progression of human cancer development, including reactive oxygen and nitrogen species, aberrant arachidonic acid metabolites and cytokines/growth factors, and immune dysfunction. These molecular events in IBD lead to genetic abnormality and promote aberrant cell proliferation, which further lead to epithelial changes encompassing a broad spectrum from inflammation-induced hyperplasia to dysplasia. Objective.-To review the (1) epidemiologic and molecular pathogenesis of the risk for colorectal cancer in IBD, (2) morphologic characterization, biomarker(s), and classification of dysplastic lesions, and (3) clinical management of dysplastic lesions arising in IBD. Data Sources.-The different IBD-related dysplastic lesions are illustrated by using morphology in conjunction with molecular pathways, and the "field cancerization" theory and its potential significance are discussed with a review of the literature. Conclusions.-Patients with IBD are at increased risk of developing colorectal cancer. The risk of developing carcinoma is related to the extent/duration/activity of the patient's disease. There is no consensus regarding the extent of carcinoma risk associated with IBD; however, all would agree that patients with IBD represent a group at significant risk for developing carcinoma and as such, warrant adequate surveillance and prevention. With better screening modalities and detection/characterization of dysplastic lesions, IBD-associated serrated lesions, and "field cancerization," we will improve our understanding of and approach to risk stratification.

Altered mRNA expression of telomere binding proteins (TPP1, POT1, RAP1, TRF1 and TRF2) in ulcerative colitis and Crohn's disease

AIMS

To determine mRNA expression of telomeric binding proteins in inflammatory bowel disease (IBD), and to note any effects of pharmacotherapy on telomere binding protein expression.

METHODS

Peripheral blood mononuclear cells (PBMC) obtained from 31 IBD patients and 13 controls were activated with phytohaemagglutinin and purified to yield activated (CD25+) T lymphocytes. TPP1, POT1, RAP1, TRF1 and TRF2 mRNA expression in PBMC and activated T lymphocytes was measured with RT-PCR.

RESULTS

In activated (CD25+) T lymphocytes, mean TRF2 mRNA levels were lower in both UC (6.6 vs 10, p=0.004) and CD subjects (6.9 vs 10; p=0.004). Similarly. in activated (CD25+) T lymphocytes mean RAP1 mRNA expression was significantly lower in UC subjects (4.5 vs 9.8, p=0.029) but not in CD subjects. In resting PBMC, mean TRF1 mRNA levels were lower in both UC (2.6 vs 3.5; p=0.008) and CD subjects (1.0 vs 3.5; p=0.04). No difference in PBMC and activated (CD25+) T lymphocytes mRNA levels of TPP1 and POT1 were noted in either UC or CD subjects. An association with 5-aminosalicylate therapy (R(2)=0.4) was only detected with RAP1 mRNA expression. TRF2 mRNA expression was inversely associated with disease duration only in UC subjects (p=0.05; R(2)=-0.6).

CONCLUSIONS

The downregulation of TRF2 and RAP1 mRNA expression in CD25+ T-lymphocytes in IBD suggests that these telomere binding proteins play a role in telomere regulation and may contribute to the telomeric fusions and chromosomal abnormalities observed in UC. These findings may also indicate a systemic process of telomere uncapping which could represent a biomarker for IBD associated cancer risk.

Mechanisms underlying development of ulcerative colitis-associated colorectal carcinoma

Ulcerative colitis (UC) is a chronic inflammatory disease of the gastrointestinal tract arising from the genetic predisposing factor and the abnormality of the immune system. Long-term course of UC may cause the development of several complications, such as colorectal carcinoma. The mechanisms underlying the development of UC-associated colorectal carcinoma, involving a series of changes from genetic materials to signal transduction, are extremely complicated and differ from those behind the development of sporadic colorectal carcinoma. This article discusses the mechanisms underlying the development of UC-associated colorectal carcinoma.

Antineoplastic Drugs as a Potential Risk Factor in Occupational Settings: Mechanisms of Action at the Cell Level, Genotoxic Effects, and Their Detection Using Different Biomarkers

U članku je prikazana osnovna podjela antineoplastičnih lijekova prema mehanizmima djelovanja na razini stanice. Objašnjeni su mehanizmi genotoksičnosti najvažnijih vrsta lijekova koji se primjenjuju u okviru uobičajenih protokola za liječenje zloćudnih novotvorina. Navedena je važeća klasifikacija antineoplastika prema kancerogenom potencijalu, podaci o mutagenom potencijalu te je prikazana njihova podjela u skladu s anatomsko-terapijsko-kemijskim sustavom klasifikacije. Sustavno su prikazani najvažniji rezultati svjetskih i hrvatskih istraživanja na populacijama radnika izloženih antineoplasticima, provedenih u razdoblju 1980.-2009. s pomoću četiri najčešće primjenjivane metode: analize izmjena sestrinskih kromatida, analize kromosomskih aberacija, mikronukleus-testa i komet-testa. Objašnjena su osnovna načela navedenih metoda te raspravljene njihove prednosti i nedostaci. Biološki pokazatelji daju važne podatke o individualnoj osjetljivosti profesionalno izloženih ispitanika koji mogu poslužiti unaprjeđenju postojećih uvjeta rada i upravljanju rizicima pri izloženosti genotoksičnim agensima. Na osnovi prednosti i nedostataka citogenetičkih metoda zaključeno je da je mikronukleus-test, koji podjednako uspješno dokazuje klastogene i aneugene učinke, jedna od najboljih metoda dostupnih za otkrivanje štetnih djelovanja antineoplastičnih lijekova koji su u aktivnoj primjeni.

Inflammatory bowel disease: a model of chronic inflammation-induced cancer

Chronic inflammation is a well-recognized risk factor for the development of human cancer. Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a typical longstanding inflammatory disease of the colon with increased risk for the development of colorectal carcinoma. Several molecular events involved in chronic inflammatory process may contribute to multistage progression of human cancer development, including the overproduction of reactive oxygen and nitrogen species, overproduction/activation of key arachidonic acid metabolites and cytokines/growth factors, and immunity system dysfunction. Multiple animal models of IBD have been established, and in general, these models can be mainly categorized into chemically induced, genetically engineered (transgenic or gene knock-out), spontaneous, and adoptive transferring animal models. This chapter mainly focuses on (1) epidemiologic and molecular evidence on IBD and risk of colorectal cancer, (2) molecular pathogenesis of IBD-induced carcinogenesis, and (3) modeling of IBD-induced carcinogenesis in rodents and its application.

The genotoxic risk in health care workers occupationally exposed to cytotoxic drugs--a comprehensive evaluation by the SCE assay

Present study aimed at an integral assessment of sister chromatid exchange (SCE) frequencies in the health care workers occupationally exposed to cytostatics. The results of 500 individual analyses were evaluated. Drug handling practice was investigated in parallel and the results showed that cytostatics are mostly prepared outside hospital pharmacy (98%) and mainly handled by nurses (96%). Mean frequency of SCE was 5.63 +/- 2.28, while HFC represented 9.65% of the cells analysed. Both values were higher compared to previously established control values for Croatian population. The duration of exposure, profession, age, gender, smoking habit, medical exposures, and simultaneous exposure to other occupational mutagens significantly contributed to SCE and HFC values. The usefulness both biomarkers in the assessment of cytogenetic damage is confirmed. Since current practice in Croatian hospitals does not include regular monitoring of workplaces, to ensure maximal occupational safety, a surveillance on exposed health care workers, including periodic biomonitoring, is recommended.

Ulcerative colitis is a disease of accelerated colon aging: evidence from telomere attrition and DNA damage

BACKGROUND & AIMS

Telomere shortening is implicated in cancer and aging and might link these 2 biologic events. We explored this hypothesis in ulcerative colitis (UC), a chronic inflammatory disease that predisposes to colorectal cancer and in which shorter telomeres have been associated with chromosomal instability and tumor progression.

METHODS

Telomere length was measured by quantitative polymerase chain reaction in colonocytes and leukocytes of 2 different sets of UC patients and compared with normal controls across a wide range of ages. For a subset of patients, telomere length was measured in epithelium and stroma of right and left colon biopsy specimens. A third set of biopsy specimens was analyzed for phosphorylation of histone H2AX (gammaH2AX), a DNA damage signal, by immunofluorescence and for telomere length by quantitative fluorescence in situ hybridization. Relationships between telomere length, gammaH2AX intensity, age, disease duration, and age of disease onset were explored.

RESULTS

Colonocyte telomeres shorten with age almost twice as rapidly in UC patients as in normal controls. This extensive shortening occurs within approximately 8 years of disease duration. Leukocyte telomeres are slightly shorter in UC patients than in controls, but telomeres of colon stromal cells are unaffected. gammaH2AX intensity is higher in colonocytes of UC patients than in controls and is not dependent on age or telomere length.

CONCLUSIONS

Colonocytes of UC patients show premature shortening of telomeres, which might explain the increased and earlier risk of cancer in this disease. Shorter leukocyte telomeres and increased gammaH2AX in colonocytes might reflect oxidative damage secondary to inflammation.

Cancer surveillance in inflammatory bowel disease: new molecular approaches

PURPOSE OF REVIEW

Patients with chronic inflammatory bowel disease, such as ulcerative colitis and Crohn's disease, have an increased risk of colorectal cancer. Life-long colonoscopy surveillance is performed to detect the presence of dysplasia, but this approach is expensive and time-consuming. Thus, there is intensive research to identify molecular factors with prognostic value. This review summarizes recent research, with a special emphasis on the mechanisms underlying these molecular alterations.

RECENT FINDINGS

The role of chromosomal instability in the progression to inflammatory bowel disease-associated colorectal cancer is clear and likely relates to chronic cycles of injury, inflammation, repair and telomere shortening. The role of microsatellite instability has been a subject of discussion, and data suggest that microsatellite instability in inflammatory bowel disease might be different from microsatellite instability in sporadic colorectal cancer. Methylation, as a mechanism of gene silencing, also plays a role in ulcerative colitis tumorigenesis. Chronic inflammation has been linked to p53 activation and oxidative stress, contributing to the extensive genomic DNA damage observed in ulcerative colitis.

SUMMARY

Improved understanding of the molecular biology of cancer progression in inflammatory bowel disease will hopefully lead to the identification of useful prognostic biomarkers. Efforts are needed to prove the clinical utility of the most promising markers now identified.

Telomeres, interstitial telomeric repeat sequences, and chromosomal aberrations

Telomeres are specialized nucleoproteic complexes localized at the physical ends of linear eukaryotic chromosomes that maintain their stability and integrity. The DNA component of telomeres is characterized by being a G-rich double stranded DNA composed by short fragments tandemly repeated with different sequences depending on the species considered. At the chromosome level, telomeres or, more properly, telomeric repeats--the DNA component of telomeres--can be detected either by using the fluorescence in situ hybridization (FISH) technique with a DNA or a peptide nucleic acid (PNA) (pan)telomeric probe, i.e., which identifies simultaneously all of the telomeres in a metaphase cell, or by the primed in situ labeling (PRINS) reaction using an oligonucleotide primer complementary to the telomeric DNA repeated sequence. Using these techniques, incomplete chromosome elements, acentric fragments, amplification and translocation of telomeric repeat sequences, telomeric associations and telomeric fusions can be identified. In addition, chromosome orientation (CO)-FISH allows to discriminate between the different types of telomeric fusions, namely telomere-telomere and telomere-DNA double strand break fusions and to detect recombination events at the telomere, i.e., telomeric sister-chromatid exchanges (T-SCE). In this review, we summarize our current knowledge of chromosomal aberrations involving telomeres and interstitial telomeric repeat sequences and their induction by physical and chemical mutagens. Since all of the studies on the induction of these types of aberrations were conducted in mammalian cells, the review will be focused on the chromosomal aberrations involving the TTAGGG sequence, i.e., the telomeric repeat sequence that "caps" the chromosomes of all vertebrate species.

Extended lifespan and long telomeres in rectal fibroblasts from late-onset ulcerative colitis patients

OBJECTIVES

Ulcerative colitis (UC) is characterized by damage to the intestinal epithelium and connective tissue. The causes of this damage could include changes in the ability of colonic fibroblasts to heal wounds and maintain epithelial cell proliferation. Telomeres shorten with each cell division and eventually signal senescence. The aim of this study is to investigate whether the impaired function of rectal fibroblasts in UC is due to accelerated telomere shortening, oxidative stress and premature senescence.

METHODS

We isolated rectal fibroblasts from eight UC patients and nine non-colitis controls, and recorded their in-vitro lifespans. Telomere lengths and superoxide dismutase mRNA expression were also measured by real-time polymerase chain reaction and peroxide levels were measured by flow cytometry.

RESULTS

The fibroblast lifespan decreased as patient age increased (R2=0.68, P=0.003) in control patients, but this relationship was absent in UC fibroblasts. We identified a group of patients who were diagnosed later in life than a second group (59 versus 35 years, P=0.002). Fibroblasts from these late-onset UC patients underwent significantly more population doublings before senescence than age-matched controls (25 versus 15, P=0.02). Slower in-vitro telomere shortening rates (32 versus 344, P=0.006) and trends towards longer telomeres at explant were also observed in late-onset UC fibroblasts. Peroxide levels correlated positively with telomere shortening rate (r=0.581, P=0.078).

CONCLUSIONS

Some UC-predisposed individuals may have more efficient antioxidant systems that protect the telomeres from oxidative damage. This may allow their rectal fibroblasts to live longer, function better and thus delay the onset of the disease until later life.

Lymphocyte telomere dynamics and telomerase activity in inflammatory bowel disease: effect of drugs and smoking

BACKGROUND

The chromosome instability observed in peripheral blood lymphocytes in ulcerative colitis could be a biomarker of cancer susceptibility.

AIM

To determine whether accelerated telomere shortening could explain chromosome instability and assess the effect of drugs and smoking on telomere dynamics in these cells.

METHODS

Peripheral blood lymphocytes were isolated from ulcerative colitis, Crohn's disease and non-inflammatory bowel disease control patients. Telomere lengths were measured by quantitative real-time polymerase chain reaction. After activation and cell separation, telomerase activity and human telomerase reverse transcriptase messenger ribonucleic acid were measured by telomerase repeat amplification protocol enzyme-linked immunosorbent serological assay and quantitative real-time polymerase chain reaction, respectively.

RESULTS

Age-related telomere loss in peripheral blood lymphocytes was similar in ulcerative colitis, Crohn's disease and control patients. Telomerase activity decreased with age in all groups and correlated positively with telomere length (r = 0.489, P = 0.006). Among Crohn's disease patients, azathioprine was associated with decreased telomerase activity (0.66 vs. 1.54, P = 0.026, P < 0.05) and smoking was associated with decreased human telomerase reverse transcriptase mRNA expression (10.5 vs. 33.3, P = 0.036, P < 0.05).

CONCLUSIONS

Telomere shortening is not accelerated and therefore cannot be the cause of the chromosome instability observed in ulcerative colitis peripheral blood lymphocytes. Azathioprine and cigarette smoking modify telomerase expression in these cells.

Telomere length study in celiac disease

OBJECTIVES

Telomeres are important structures that are critical for maintaining chromosomal integrity and cell surveillance. The aim of this study was to analyze telomere length in patients with celiac disease (CD), a multifactorial disorder with a strong genetic component that exhibits genomic instability and cancer predisposition, particularly T-cell lymphomas.

METHODS

Telomere length measured by telomere restriction fragments (TRF) was studied in small intestinal biopsy (SIB) samples and peripheral blood lymphocytes (PBL) from 20 untreated CD patients, distributed according to the clinical form as four asymptomatic, five monosymptomatic, and 11 polysymptomatic individuals. We also analyzed TRF from normal peripheral blood lymphocytes and normal biopsy samples as normal controls.

RESULTS

TRF evaluation showed a significant telomere shortening in SIB samples from CD patients (4.21 +/- 0.29 Kb) compared to PBL from the same individuals (9.17 +/- 0.35 Kb) (p < 0.0001), independently of clinical form. Mean TRF peak values from normal biopsy samples were significantly higher (8.33 +/- 0.38 Kb) than those observed in CD biopsy samples (p < 0.001). No differences between TRF values in CD-PBL and normal peripheral blood lymphocytes (8.89 +/- 0.37Kb) were found.

CONCLUSIONS

Our findings in patients with CD, a disorder in which the gluten-induced mucosal injury could accelerate telomere shortening, would increase the process of end-to-end fusions resulting in chromosomal changes, supports the hypothesis that genomic instability and telomere reduction may play a role in the cancer predisposition observed in these patients.

Molecular underpinnings of cancer in ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon that can lead to cancer. Patients with UC have approximately 20% lifetime risk of colon cancer, with the risk increasing with the duration of disease. Why some patients develop colorectal cancer and others do not is not clearly understood. Evidence reveals that the UC patients who develop cancer have an underlying process of instability in the colonic mucosa as measured by DNA fingerprinting and fluorescent in situ hybridization techniques. The cause of instability may be shortened telomeres, the protective ends of chromosomes. Patients who progress to dysplasia and cancer have shorter telomeres, which become sticky and cause telomeric bridges to form, with subsequent chromosomal breakage. Thus, UC patients who have dysplasia and cancer appear to have a mutator phenotype present in the colonic mucosa that underlies the process of tumorigenesis.