Clinical significance of telomerase activity in multiple myeloma

BACKGROUND. The clinical course of patients with multiple myeloma varies, and therefore it is important to evaluate the disease state. We studied the telomerase activity of myeloma cells as a possible prognostic factor in such patients. METHODS. Twenty five samples from patients with multiple myeloma were studied. We purified myeloma cells in bone marrow samples according to the expression of surface antigens, CD38 and CD45. CD38⁺/CD45^{- or dim} cells had morphologic characteristics of myeloma cells, with a purity exceeding 95%. The telomerase activity of myeloma cells was determined by a polymerase chain reaction-based telomeric repeat amplification protocol assay. Ki-67 positivity of the purified cells was determined by flow cytometry using anti-Ki-67 antibody. The relationship between telomerase activity and prognostic factors was also examined. RESULTS. A significantly high degree of telomerase activity was detected in subjects with a serum β2-microglobulin level ≥ 6mg/dL or at Stage III (P = 0.002). The serum C-reactive protein, lactate dehydrogenase, and creatinine levels did not correlate with the telomerase activity, but this activity did significantly correlate with Ki-67 positivity and the percentage of plasma cells in the bone marrow (r = 0.561, P = 0.004, and r = 0.397, P = 0.049, respectively). The patients with high levels of telomerase activity were thus found to have a significantly short survival time after sampling (P = 0.035). CONCLUSIONS. The measurement of the telomerase activity in myeloma cells was found to be a reliable marker for the proliferating capacity and tumor mass in myeloma patients. The telomerase activity of myeloma cells may therefore be useful as a prognostic factor.