Correlation of telomerase activity with development and progression of adult t-cell leukemia

Telomerase is an enzyme that adds hexametric TTAGGG nucleotide repeats to the ends of vertebrate chromosomal DMAs (i.e., telomeres) to compensate for losses that occur with each round of DNA replication. Telomerase activity, demonstrable in most human tumors, enables them to maintain telomere stability. Peripheral blood mononuclear cells were sampled from 57 patients seropositive for human Tlymphotropic virus type I (HTLV-I), including many with adult T-cell leukemia (ATL). Telomerase activity was determined in samples using a modified telomeric repeat amplification protocol. We semiquantitatively determined telomerase activity by serial dilution of each sample. All samples from acute and chronic type ATL patients were positive, 7 of 10 (70%) smoldering type patients and 7 of 24 (29.2%) asymptomatic viral carriers were positive. Disease progression from asymptomatic viral carrier to acute type correlated with telomerase activity. Two samples from chronic type ATL patients with relatively high telomerase activity progressed to the acute type within 1 month. Serum lactate dehydrogenase level also correlated with telomerase activity. These results indicate that reactivation of telomerase activity is a key event in development and progression of ATL, and telomerase could be a useful marker for predicting the course.