RESUMO
Background: efficient screening for detection of colorectal cancer [CRC] at earlier stages reduces its mortality. The purpose of this study was to investigate expression of carcinoembryonic antigen [CEA] and human telomerase reverse transcriptase [hTERT] mRNA in peripheral blood of CRC patients and to present strategies for early detection screen test
Methods: twenty seven patients in non-metastatic stage and 27 healthy individuals were studied. Expression of CEA, hTERT mRNA and 18srRNA [18s subunit of ribosomal RNA, as reference gene] were determined based on real-time RT-PCR on 3 [micro]g of total RNA from blood in 3 separate vials [1 [micro]g per vial]
Results: positive expression rate of CEA mRNA [78%] and hTERT mRNA [81%] were higher in patient group [P<0.001]. These rates were meaningfully higher than the results of individual vials containing only 1 [micro]g of total RNA. Difference between Ct values of markers with 18srRNA [[DELTA]Ct] was higher in healthy group than patient one. Therefore, a [DELTA]Ct cut-off value was determined for distinguishing between true- and false-positive results. Concurrent expression of both markers was found in 67% of the patients, which was higher than healthy cases [11%]. Combination of concurrent marker expression with cut-off point strategy increased specificity to 100%
Conclusion: these results showed that concurrent evaluation of marker expression and performing the test on 3 [micro]g of samples in 3 separate vials may increase specificity and sensitivity of real-time RT-PCR for early detection of non-metastatic CRC. However, more investigations with larger numbers of samples are needed to verify these results. Iran. Biomed. J. 17 [1]: 15-21, 2013