This work was supported by the Italian Ministry of University and Research (grant no. 2009AMPA9C to C.F.) and Padova University (grant 2010 to A.D.R.). The authors have no competing interests to declare.

The online version of this article has a Supplementary Appendix. BackgroundB-cell chronic lymphocytic leukemia is a clinically heterogeneous disease; some patients rapidly progress and die within a few years of diagnosis, whereas others have a long life expectancy with minimal or no treatment. Telomere length and telomerase levels have been proposed as prognostic factors; however, very few cases have been characterized for both parameters and no study has analyzed the prognostic value of the telomere/telomerase profile. Design and MethodsOne hundred and seventy-three cases of chronic lymphocytic leukemia were characterized for telomere lengths and telomerase levels by real-time polymerase chain reaction. Data were correlated with established prognostic markers, IGVH mutational status and chromosomal aberrations, and clinical outcome. ResultsTelomere lengths were inversely correlated with telomerase levels (rs= -0.213; P=0.012), and most of the cases of chronic lymphocytic leukemia with high levels (above median) of telomerase had short (below median) telomeres (P=0.0001). Telomerase levels were higher and telomeres were shorter in unmutated IGVH cases than in mutated IGVH ones (P<0.0001). Chronic lymphocytic leukemias with 11q, 17p deletion or 12 trisomy had significantly higher levels of telomerase and shorter telomeres than those with no chromosomal aberration or the sole 13q deletion (P<0.001). Telomere length/telomerase level profiles identified subgroups of patients with different clinical outcomes (P<0.0001), even within the subsets of chronic lymphocytic leukemia defined by IGVH mutational status or chromosomal aberrations. Short telomere/high telomerase profile was independently associated with more rapid disease progression. ConclusionsComprehensive analyses of telomeres, telomerase, chromosomal aberrations, and IGVH mutational status delineate groups of chronic lymphocytic leukemias with distinct biological characteristics and clinical outcomes. The telomere/telomerase profile may be particularly useful in refining the prognosis of chronic lymphocytic leukemia patients with mutated IGVH and no high-risk chromosomal aberrations.Key words: B-CLL, telomere, telomerase, chromosomal aberrations. Bonaldi L, Trentin L, Visco C, Keppel S, Giunco S, Frezzato F, Facco M, Novella E, Giaretta I, Del Bianco P, Semenzato G, and De Rossi A. Telomere length and telomerase levels delineate subgroups of B-cell chronic lymphocytic leukemia with different biological characteristics and clinical outcomes. Haematologica 2012;97(1):56-63. doi:10.3324/haematol.2011 Telomere length and telomerase levels delineate subgroups of B-cell chronic lymphocytic leukemia with different biological characteristics and clinical outcomes

Purpose: Induction of viral lytic cycle, which induces death of host cells, may constitute a useful adjunct to current therapeutic regimens for Epstein-Barr virus (EBV)-driven malignancies. Human telomerase reverse transcriptase (hTERT), essential for the oncogenic process, may modulate the switch from latent to lytic infection. The possible therapeutic role of hTERT inhibition combined with antiviral drugs was investigated.Experimental Design: EBV-negative BL41 and convertant EBV-positive BL41/B95.8 Burkitt's lymphoma cell lines and lymphoblastoid cell lines (LCL) were infected with retroviral vector encoding short hairpin RNA (shRNA) anti-hTERT and cultured with or without the prodrug ganciclovir. The effects on EBV lytic replication, cell proliferation, and apoptosis were characterized.Results: hTERT silencing by shRNA induced the expression of BZLF1, EA-D, and gp350 EBV lytic proteins and triggered a complete lytic cycle. This effect was associated with downregulation of BATF, a negative regulator of BZLF1 transcription. hTERT silencing also resulted in antiproliferative and proapoptotic effects. In particular, hTERT inhibition induced an accumulation of cells in the S-phase, an effect likely due to the dephosphorylation of 4E-BP1, an AKT1-dependent substrate, which results in a decreased availability of proteins needed for cell-cycle progression. Besides inducing cell death through activation of complete EBV lytic replication, hTERT inhibition triggered AKT1/FOXO3/NOXA-dependent apoptosis in EBV-positive and -negative Burkitt's lymphoma cells. Finally, ganciclovir enhanced the apoptotic effect induced by hTERT inhibition in EBV-positive Burkitt's lymphomas and LCLs.Conclusions: These results suggest that combination of antiviral drugs with strategies able to inhibit hTERT expression may result in therapeutically relevant effects in patients with EBV-related malignancies.

Plasma levels of cfRNA and hTERT are promising markers of tumor response to pCRT for rectal cancer.