Short-term inhibition of TERT induces telomere length-independent cell cycle arrest and apoptotic response in EBV-immortalized and transformed B cells

open7siBesides its canonical role in stabilizing telomeres, telomerase reverse transcriptase (TERT) may promote tumorigenesis through extra-telomeric functions. The possible therapeutic effects of BIBR1532 (BIBR), a powerful TERT inhibitor, have been evaluated in different cellular backgrounds, but no data are currently available regarding Epstein-Barr virus (EBV)-driven B-cell malignancies. Our aim was to characterize the biological effects of TERT inhibition by BIBR on EBV-immortalized lymphoblastoid cell lines (LCLs) and fully transformed Burkitt's lymphoma (BL) cell lines. We found that BIBR selectively inhibits telomerase activity in TERT-positive 4134/Late and 4134/TERT+ LCLs and EBV-negative BL41 and EBV-positive BL41/B95.8 BL cell lines. TERT inhibition led to decreased cell proliferation, accumulation of cells in the S-phase and ultimately to increased apoptosis, compared with mock-treated control cells. All these effects occurred within 72 h and were not observed in BIBR-treated TERT-negative 4134/TERT- and U2OS cells. The cell cycle arrest and apoptosis, consequent upon short-term TERT inhibition, were associated with and likely dependent on the activation of the DNA damage response (DDR), highlighted by the increased levels of γH2AX and activation of ATM and ATR pathways. Analyses of the mean and range of telomere lengths and telomere dysfunction-induced foci indicated that DDR after short-term TERT inhibition was not related to telomere dysfunction, thus suggesting that TERT, besides stabilizing telomere, may protect DNA via telomere-independent mechanisms. Notably, TERT-positive LCLs treated with BIBR in combination with fludarabine or cyclophosphamide showed a significant increase in the number of apoptotic cells with respect to those treated with chemotherapeutic agents alone. In conclusion, TERT inhibition impairs cell cycle progression and enhances the pro-apoptotic effects of chemotherapeutic agents in TERT-positive cells. These results support new therapeutic applications of TERT inhibitors in EBV-driven B-cell malignancies.openCeleghin, Andrea; Giunco, Silvia; Freguja, Riccardo; Zangrossi, Manuela; Nalio, Silvia; Dolcetti, Riccardo; De Rossi, AnitaCeleghin, Andrea; Giunco, Silvia; Freguja, Riccardo; Zangrossi, Manuela; Nalio, Silvia; Dolcetti, Riccardo; DE ROSSI, Anit

Necrotizing Follicular Lymphoma of the Inguinal Region with Sternbergoid Cells: Clinical–Pathological Features of a Challenging Entity

Follicular lymphoma (FL) is one of the most common B-cell malignancies worldwide. While the diagnosis of conventional cases is straightforward, rare clinical–pathological variants may be challenging due to their misleading morphology, aberrant phenotype and/or atypical presentation. To add to the spectrum of unusual FLs, we report on a rare disease pattern characterized by (i) inguinal presentation, (ii) massive necrosis, (iii) Hodgkin/Reed–Sternberg (HRS)-like cells, and (iv) adjacent areas of diffuse large B-cell lymphoma evolution. All cases occurred in elderly patients (median age at diagnosis: 69.5 years), disclosed a low stage at diagnosis (Ann Arbor stage IA-IIA), and had deceiving clinical features. Despite the alarming histology, excellent responses to conventional therapies were reported in all patients. In conclusion, necrotizing FL of the inguinal region is a rare neoplasm characterized by peculiar clinical and histological features. This lymphoma should always be considered in the differential diagnosis of massively necrotic inguinal lesions

Genetic, epigenetic and immunologic profiling of MMR-deficient relapsed glioblastoma

PURPOSE: In-depth characterization of recurrent glioblastoma (rGBM) might contribute to a better understanding of the mechanisms behind tumor progression and enable rGBM treatment with targeted drugs. EXPERIMENTAL DESIGN: In this study, GBM samples were collected at diagnosis and recurrence from adult patients treated with Stupp protocol. Expression of mismatch repair (MMR) proteins was evaluated by IHC, followed by whole exome sequencing (WES) of tumor samples showing loss of MSH6 reactivity. Established genetic, epigenetic and immunologic markers were assessed by standard methods and correlated with loss of MMR proteins and patient survival. RESULTS: Expression of MMR proteins was partially or completely lost in 25.9% rGBM samples. Specifically, 12 samples showed partial or total MSH6 expression reduction. Conversely, 96.4% of GBM samples at diagnosis expressed MMR markers. WES disclosed lack of variants in MMR genes in primary samples, whereas two MSH6 negative rGBM samples shared a c.3438+1G>A* splicing MSH6 variant with a potential loss of function effect. MSH6 negative rGBM specimens had high tumor mutational burden (TMB), but no microsatellite instability. In contrast, GBM samples with partial loss of MMR proteins disclosed low TMB. MMR-deficient rGBM showed significant telomere shortening and MGMT methylation and are characterized by highly heterogeneous MHC class I expression. CONCLUSIONS: Multi-level profiling of MMR-deficient rGBM uncovered hypermutated genotype uncoupled from enriched expression of immune-related markers. Assessment of MHC class I expression and TMB should be included in protocols aiming to identify rGBM patients potentially eligible for treatment with drugs targeting immune checkpoint inhibitors