Diagnostic Value II: Hematopoietic Malignancies

Telomerase activity has been suggested to play a critical role in hematopoietic stem cell (HSC) maintenance. The most primitive HSCs, long-term HSCs, present in specific niches where they can remain mitotically quiescent for long periods of time, exhibiting a low level of telomerase activity. Short-term HSCs undergo asymmetric cell divisions with upregulated telomerase activity. Leukemic stem cells (LSCs) have shortened telomeres with high telomerase activity, and the downstream rapidly cycling blasts have more shortened telomeres with higher telomerase activity. This indicates that telomerase activity, hTERT expression, or both are valuable for diagnostic and prognostic factor in treating leukemia patients. Telomere biology in chronic myeloid leukemia model also suggests that telomere length may be a good parameter to measure response to anticancer therapy. To prove the validity and efficacy of LSC-directed chemotherapy regimens, further study is required on the basis of telomere biology in normal and LSCs.