Assuntos
Transtornos Cromossômicos , Leucemia Linfocítica Crônica de Células B , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/terapia , Transtornos Cromossômicos/genética , Deleção Cromossômica , Cromossomos Humanos Par 13/genética , Cariótipo , PrognósticoAssuntos
Aberrações Cromossômicas , Cromossomos Humanos/genética , Diploide , Hibridização in Situ Fluorescente/métodos , Cariotipagem/métodos , Mieloma Múltiplo/classificação , Mieloma Múltiplo/genética , Biomarcadores Tumorais/genética , Feminino , Seguimentos , Humanos , Masculino , Mieloma Múltiplo/patologia , Prognóstico , Estudos Retrospectivos , Taxa de SobrevidaRESUMO
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: Multilevel 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.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias Encefálicas/genética , Reparo de Erro de Pareamento de DNA , Glioblastoma/genética , Recidiva Local de Neoplasia/genética , Biomarcadores Tumorais/imunologia , Encéfalo/patologia , Encéfalo/cirurgia , Neoplasias Encefálicas/imunologia , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/terapia , Quimiorradioterapia Adjuvante , Metilação de DNA , Epigênese Genética , Feminino , Perfilação da Expressão Gênica , Genes MHC Classe I/genética , Glioblastoma/imunologia , Glioblastoma/mortalidade , Glioblastoma/terapia , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Recidiva Local de Neoplasia/imunologia , Recidiva Local de Neoplasia/mortalidade , Recidiva Local de Neoplasia/cirurgia , Intervalo Livre de Progressão , Estudos Retrospectivos , Homeostase do Telômero/genética , Microambiente Tumoral/genética , Microambiente Tumoral/imunologia , Sequenciamento do ExomaRESUMO
Besides 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.
