Comparison of clinicopathological features and hRad21 expression between telomerase-dependent and telomerase-independent colorectal cancer.

Background/aims: To investigate the difference of clinicopathological features and expression of hRad21 between telomerase-dependent and telomerase-independent colorectal cancer (CRC).

Methodology: By detecting telomerase activity of surgical specimens using the TRAP method, 251 cases diagnosed as CRC were allocated to the telomerase-dependent and telomerase-independent groups, as appropriate. Expression difference of hRad21 between the two groups was investigated by immunohistochemistry. All patients were followed-up and clinicopathological features were compared.

Results: There were 38 and 213 cases in the telomerase-independent and telomerase-dependent groups, respectively. Expression of hRad21 in the telomerase-independent group is higher than that in the telomerase-dependent group. Clinicopathological analysis indicated that invasion of the rectal wall (T stage) in the telomerase-independent group was more superficial than that in the telomerase group (p=0.022). Age, gender, location of tumor, serum CEA, CA19-9, lymph node metastasis, distant metastasis, TNM stage and tumor differentiation showed no difference between groups. Follow-up indicated a significantly shortened survival time in the telomerase-dependent group (p=0.006).

Conclusions: Most CRC (84.9%) maintain their telomeres by telomerase, while a minority (15.1%) do so by telomerase-independent pathway. Depth of invasion in the telomerase-independent group was lower than that the telomerase group. Follow-up indicated that patients of telomerase-independent group had a higher survival rate than that of telomerase-dependent group. Expression of hRad21 in telomerase-independent CRC is higher than that of telomerase-dependent group, which suggested that hRad21 may be an important protein involved in telomerase-independent telomere maintenance mechanisms.