Telomerase mRNA expression and immunohistochemical detection as a biomarker of malignant transformation in patients with inflammatory bowel disease.

BACKGROUND: Inflammatory bowel disease is a premalignant condition for developing colorectal cancer. Since a correlation has been suggested between telomere length, chromosomal instability and neoplastic transformation in this setting, we sought to investigate whether telomerase expression in colorectal mucosa may constitute a biomarker for malignant transformation in patients with inflammatory bowel disease. PATIENTS AND METHODS: Forty-seven patients with inflammatory bowel disease with and without cancer or dysplasia were evaluated for human telomerase reverse transcriptase hTERT immunostaining in paraffin-embedded, formalin-fixed colorectal tissues. In addition, hTERT mRNA expression was assessed in fresh frozen specimens from a second set of 35 patients with inflammatory bowel disease at high or low risk for neoplastic transformation. RESULTS: Five out of 10 patients (50%) with colorectal cancer or high-grade dysplasia exhibited hTERT immunochemical detection in adjacent, non-transformed colonic mucosa. However, this phenomenon was also observed in non-affected mucosa of patients with either long-standing (13 out of 19 patients; 68%) or short duration (13 out of 18 patients; 72%) disease without cancer or dysplasia. On the other hand, hTERT mRNA expression in non-affected colorectal mucosa from patients at high risk for neoplastic transformation due to long-standing disease was higher than in those at low risk (7.42+/-6.43 vs. 2.87+/-1.47, respectively; p=0.006). CONCLUSIONS: Whereas hTERT immunostaining provides equivocal results, the observation that patients at high risk for colorectal cancer because of long-standing inflammatory bowel disease overexpress hTERT mRNA in non-affected colorectal mucosa suggests its potential usefulness as a biomarker of the risk of malignant transformation.

Aberrant gene promoter methylation associated with sporadic multiple colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) multiplicity has been mainly related to polyposis and non-polyposis hereditary syndromes. In sporadic CRC, aberrant gene promoter methylation has been shown to play a key role in carcinogenesis, although little is known about its involvement in multiplicity. To assess the effect of methylation in tumor multiplicity in sporadic CRC, hypermethylation of key tumor suppressor genes was evaluated in patients with both multiple and solitary tumors, as a proof-of-concept of an underlying epigenetic defect. METHODOLOGY/PRINCIPAL FINDINGS: We examined a total of 47 synchronous/metachronous primary CRC from 41 patients, and 41 gender, age (5-year intervals) and tumor location-paired patients with solitary tumors. Exclusion criteria were polyposis syndromes, Lynch syndrome and inflammatory bowel disease. DNA methylation at the promoter region of the MGMT, CDKN2A, SFRP1, TMEFF2, HS3ST2 (3OST2), RASSF1A and GATA4 genes was evaluated by quantitative methylation specific PCR in both tumor and corresponding normal appearing colorectal mucosa samples. Overall, patients with multiple lesions exhibited a higher degree of methylation in tumor samples than those with solitary tumors regarding all evaluated genes. After adjusting for age and gender, binomial logistic regression analysis identified methylation of MGMT2 (OR, 1.48; 95% CI, 1.10 to 1.97; p = 0.008) and RASSF1A (OR, 2.04; 95% CI, 1.01 to 4.13; p = 0.047) as variables independently associated with tumor multiplicity, being the risk related to methylation of any of these two genes 4.57 (95% CI, 1.53 to 13.61; p = 0.006). Moreover, in six patients in whom both tumors were available, we found a correlation in the methylation levels of MGMT2 (r = 0.64, p = 0.17), SFRP1 (r = 0.83, 0.06), HPP1 (r = 0.64, p = 0.17), 3OST2 (r = 0.83, p = 0.06) and GATA4 (r = 0.6, p = 0.24). Methylation in normal appearing colorectal mucosa from patients with multiple and solitary CRC showed no relevant difference in any evaluated gene. CONCLUSIONS: These results provide a proof-of-concept that gene promoter methylation is associated with tumor multiplicity. This underlying epigenetic defect may have noteworthy implications in the prevention of patients with sporadic CRC.

Lynch syndrome in colorectal cancer patients.

Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer, is the most common form of hereditary colorectal cancer. It is characterized by early onset of colorectal cancer and other extracolonic-associated malignancies. This disorder is inherited in an autosomal dominant pattern and is due to a mutation in one of the DNA mismatch repair genes. Although clinical and molecular understanding of the syndrome has progressed dramatically in the last decade, diagnosis of the syndrome is still a clinical challenge. This review summarizes the main features of the syndrome and provides an update of its management.