Altered mRNA Expression of Telomere-Associated Genes in Monoclonal Gammopathy of Undetermined Significance and Multiple Myeloma

Abstract

In this study, we explored changes in the expression of the telomere maintenance genes, TRF1, TRF2 and TANK1 in patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM). Results were correlated with human telomerase reverse transcriptase (hTERT ) expression, telomere length (TL) and clinicopathological characteristics. Bone marrow (BM) samples from 132 patients, 64 with MGUS and 68 with MM, were studied. Real-time quantitative reverse transcription-polymerase chain reaction was used to quantify gene expression. TL was evaluated by terminal restriction fragment length analysis. MGUS patients showed increased TRF1 levels (P = 0.006) and lower expression of TRF2 (P = 0.005) and TANK1 (P = 0.003) compared with MM patients. For hTERT analysis, patients were divided into three groups by use of receiver operating characteristics: low (group I [GI]), intermediate (group II [GII]) and high (group III [GIII]) expression. We observed increasing expression of TRF2 and TANK1 from GI to GIII in MGUS and MM, with differences for both genes in MM (P < 0.01) and for TRF2 in MGUS (P < 0.01). GIII patients with the highest telomerase expression had the shortest TL. In both entities, a positive association between TRF2-TANK1, TRF2-hTERT and TANK1-hTERT (P ≤ 0.01) was observed. In MM, the percentage of BM infiltration and Ki-67 index were positively associated with TRF2, TANK1 and hTERT expression (P ≤ 0.03) and negatively with TL (P = 0.02), whereas lactate dehydrogenase was significantly correlated with TRF2 mRNA (P = 0.008). Our findings provide the first evidence of a modification in the expression of telomeric proteins in plasma cell disorders, and suggest that mechanisms other than telomerase activation are involved in TL maintenance in these pathologies.

Telomere protein complexes and their role in lymphoid malignancies

“…The expression profile of shelterin genes in plasma cell disorders have been extensively studied by our group (Table 1) (94,96,97). Our findings showed increased expression of shelterin components in MM compared to MGUS.…”

“…However, telomerase levels were not elevated in MGUS. As shown in Table 1, studies of our group have found increased expression levels of TERT, in MM as well as in MGUS, providing the first evidence of a modification in the expression of telomerase gene in these entities (94). Interestingly, in both pathologies a similar pattern of TERT expression was observed, in which patients displaying the highest telomerase transcription levels had the shortest TLs.…”

Expression profile of telomere‐associated genes in multiple myeloma

“…To confirm the results from the microarray analysis we analysed gene expression by quantitative PCR. We used reverse transcribed RNA extracted from five controls of PBMC from healthy donors, eight HMCLs, six samples of CD138 + malignant plasma cells and CD138 − plasma cells from patients with MM, two hESCs and one iPSCs, and measured expression levels for all sixteen deregulated genes plus four additional genes involved in telomere maintenance ( TRF1 , TRF2 , TNKS and hTERT ) . Log 2 of the normalized microarrays ratio values were compared with log 2 ratio values from qPCR experiments.…”

Differential Expression of Non-Shelterin Genes Associated with High Telomerase Levels and Telomere Shortening in Plasma Cell Disorders

“…Total RNA was extracted from mononuclear cells isolated from BM samples of patients, as previously reported [ 28 ]. The cDNA synthesis was performed in a final volume of 20 μl, containing 1μg of the total RNA, for 10 minutes at 95°C, for 60 minutes at 37°C and 10 minutes at 95°C to inactive the enzyme.…”