Cuantificación en tiempo real de la subunidad hTERT (Telomerase Reverse Transcriptase) del gen de la telomerasa en plasma de pacientes con cáncer colorrectal.

by Ripoll Martín, Roberto

ABSTRACT BLACKGROUND: Telomerase is the enzime responsible for synthesizing DNA from chomosome ends during cellular division. Increased telomerase activity can be found in almost 90% of colorectal tumours. WORKING HYPOTHESIS: The determination of the subunit hTERT of the gene of telomerase in plasma of patients with colorrectal cancer, can be in use as scoreboard tumour. OBJECTIVES: To quantify in plasma the hTERT gene in a prospective series of patients operated on for colorectal cancer and to compare these values to a control group. To value the correlation of expression hTERT with the age and the sex, pre-operative CEA levels, stages and differentiation tumour. To determine the telomerase activity in tumour cells, and cells of mucous colon in a subgroup patients. MATERIALS AND METHODS: Eighty one patients undergoing surgery for colorectal cancer and a control group of fifty healthy volunteers were prospectively studied. Pre-operative venous blood samples were taken from all cancer patients and volunteers. Plasma hTERT expression was determined from peripheal blood based on real-time quantitative for transcription inverse and chain reaction of polimerase (RT-PCR), method normalized to the amount of RNA input using GAPDH gene expression. The telomerase activity was determinated in ten patients by method TRAP. RESULTS: Median values normalized hTERT (hTERTN) gene expression were higher in colorectal cancer patients (10.94, range 0.93-54.72) than healthy volunteers (0.29, range 0.00-4.63) (P<0.001). No significant differences in hTERTN expression between sex or with age (>0.05). No significant correlation was found between hTERTN expression and CEA values (P=0.218). We found significant differences between hTERTN expression and tumour stage (P=0.104). Median values of activity telomerase were higher in tumour cells of colorectal cancer (17.27, range 4.74-58.71), than cells of mucous colon (3.88, range 1.36-12.56). Sensitivity and specificity of the assay for colorectal cancer detection were 91.4% and 96%, respectively. CONCLUSIONS: These results show that detection of mRNA based on the qRT-PCR of the telomerase hTERTN gene in plasma clearly differentiates between healthy and colorectal cancer patients and that hTERTN can be detected and quantified in plasma. This opens up a new field as a non-invasive blood test for colorectal cancer diagnosis.