Telomere shortening: a biological marker of sporadic colorectal cancer with normal expression of p53 and mismatch repair proteins.

Uncontrolled growth of cells, a main criterion of cancer, is merged with pathologic telomere length alteration. Thereby, measurement of telomere length could provide important information on cell proliferation and senescence in cancer tissues. Telomere shortening and its potential correlation with clinicopathological predictive markers in sporadic colorectal cancer (CRC) with normal expression of mismatch repair (MMR) proteins (including Mlh1, Msh2, Pms2, and Msh6) and normal p53 expression was completely explored. Relative telomere length (RTL) was quantitatively measured in a cohort of 164 samples (68 patients with sporadic CRC and 96 healthy unrelated controls). Our results demonstrated a significant shortening of RTL in the tumor-derived tissue of patients compared with the control group (p<0.001). Interestingly, significant telomere shortening was observed in tumors from an ascending and sigmoid colon in comparison with tumors located in a descending colon. Additionally, the telomere length was significantly shorter in those with lymph node metastasis (p<0.05). The results suggest that pathological telomere shortening, leading to genome instability and lymphatic transformation, could serve as a potential sensitive detection and also as a classification marker for facilitating diagnosis and management of CRC.