3D Telomere Dynamics In Hodgkin's Lymphoma
Authors: Knecht Hans , Kongruttanachok Narisorn , Sawan Bassem , Lichtensztejn Zelda , Lichtensztejn Daniel , Mai Sabine 
Published: October 2019

Abstract
Abstract 745

Introduction:
Innovative 3D telomere q-FISH allows a mechanistic understanding of the transition from the mononuclear Hodgkin (H) to the multinuclear Reed-Sternberg (RS) cell in in Hodgkin's lymphoma (HL) derived cell lines and diagnostic patient biopsies (Leukemia. 2009; 23:565-573). In RS-cells the telomere protecting shelterin complex appears to be disrupted and deregulation of DNA repair mechanisms is observed. These changes occur in both, classical EBV negative and EBV-associated, LMP1 expressing HL (Lab Invest. 2010; 90:611-619). However, it is not known whether the 3D telomere profile at diagnostic biopsy is different in patients entering rapid remission after initiation of standard chemotherapy (ABVD) compared to that-one of patients with relapsing or refractory disease. In order to answer this question we analyzed by 3D telomere q-FISH diagnostic biopsies of HL patients entering rapid complete remission and compared them to diagnostic biopsies of patients with relapsing or refractory disease.

Patients and methods:
Rapid remission group (after 1–4 cycles of ABVD): 7 diagnostic biopsies of 7 patients, 19–57 years old, 5 male, 3 LMP1 expressing, 4 nodular sclerosis subtype, 3 mixed cellularity subtype, stages IA, IIA, IIIA × 2, IIIB x2, IVA. Relapse group: 7 diagnostic biopsies of 4 patients, 40–77 years old, 2 male, 1 LMP1 expressing, 3 nodular sclerosis subtype, 1 mixed cellularity subtype, stages IIA bulky, IIIB × 2, IVB; first remission after 6–8 cycles of ABVD in 3 patients, 1 patient died from progressive disease after 11 months. 3D telomere q-FISH was performed as described (Lab Invest. 2010; 90:611-619) and statistical analysis was performed using nested or two-way analysis of variance.

Results:
Bi- or multinuclear RS-cells of all patients from both groups showed a significant increase of very short telomeres and telomere aggregates when compared to the mononuclear precursor H-cells. However, most importantly, all diagnostic biopsies of the relapse group contained a very high percentage of very small telomeres, including so-called “t-stumps”, in both, H-cells (76,8 ± 11,8%) and RS-cells (87,9 ± 7,3%). Compared to the percentage of very small telomeres identified in both, H-cells (33,7 ± 9,4%) and RS-cells (54,6 ± 15,0%) of the rapid remission group, this increase is highly significant (p <0.001). Moreover, analogous findings are observed for the number of telomere aggregates. In the relapse group the average numbers of telomere aggregates per cell were 4,3 ± 2,4 aggregates per H-cell and 5,4 ± 3.0 aggregates per RS-cell, compared to 1,2 ± 0,7 aggregates per H-cell and 3,3 ± 1,1 aggregates per RS-cell in the rapid remission group.

Discussion:
The 3D nuclear telomere organization of H- and RS- cells in diagnostic biopsies of relapsing or refractory HL is characterized by both, H- and RS-cells with abundant “t-stumps” and numerous telomere aggregates. Very short telomeres, including t-stumps, and telomere aggregates, both, are characteristics of aggressiveness in cancer biology (Mol Cell. 2007;28:315-327; J Cell Biochem. 2010; 109:1095-1102). Thus, H- and RS-cells of refractory or relapsing HL show significant differences in the 3D telomere dynamics already at first, diagnostic biopsy when compared to H- and RS-cells of HL entering rapid remissions.

Disclosures:
No relevant conflicts of interest to declare.