RESUMO
Alteration in RNA splicing is implicated in carcinogenesis and progression. Mutations in spliceosome genes and alternative splicing of other genes have been noted in chronic lymphocytic leukaemia (CLL), a common B cell malignancy with heterogeneous outcomes. We previously demonstrated that differences in the amount of SET oncoprotein (a physiological inhibitor of the serine/threonine phosphatase, PP2A) is associated with clinical aggressiveness in patients with CLL. It is unknown if alternative splicing of gene transcripts regulating kinases and phosphatases affects disease pathobiology and CLL progression. We show here for the first time that mRNA levels of the alternatively spliced SET isoforms, SETA and SETB (SETα and SETß), significantly correlate with disease severity (overall survival and time-to-first-treatment) in CLL patients. In addition, we demonstrate that relative increase of SETA to SETB mRNA can discriminate patients with a more aggressive disease course within the otherwise favourable CLL risk classifications of IGHV mutated and favourable hierarchical fluorescence in situ hybridisation groups. We validate our finding by showing comparable relationships of SET mRNA with disease outcomes using samples from an independent CLL cohort from a separate institution. These findings indicate that alternative splicing of SET, and potentially other signalling cascade molecules, influences CLL biology and patient outcomes.
Assuntos
Chaperonas de Histonas , Leucemia Linfocítica Crônica de Células B , Proteínas de Neoplasias , RNA Mensageiro , RNA Neoplásico , Fatores de Transcrição , Adulto , Idoso , Idoso de 80 Anos ou mais , Processamento Alternativo , Proteínas de Ligação a DNA , Intervalo Livre de Doença , Feminino , Chaperonas de Histonas/biossíntese , Chaperonas de Histonas/genética , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/metabolismo , Leucemia Linfocítica Crônica de Células B/mortalidade , Leucemia Linfocítica Crônica de Células B/terapia , Masculino , Pessoa de Meia-Idade , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , Isoformas de Proteínas/biossíntese , Isoformas de Proteínas/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , RNA Neoplásico/biossíntese , RNA Neoplásico/genética , Taxa de Sobrevida , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genéticaRESUMO
Chronic lymphocytic leukaemia (CLL) is characterized by expression of CD5 on clonal B cells, and is partly driven by activated B-cell receptor (BCR) signalling. While CD5 is known to be a negative regulator of BCR signalling, it is unknown if variability in CD5 expression exists among patients and whether CLL cell CD5 expression affects CLL clinical outcomes. We assessed the extent to which CD5 expression is correlated with clinical outcomes, and whether this information adds to currently used prognostic markers. We evaluated CD5 expression from 1275 blood samples, established prognostic markers and time to event data from 423 CLL patients followed at the Duke University and Durham VA Medical Centers. CD5 median fluorescence intensity (MFI) was largely stable over time in individual patients, but ranged between 0·5 and 760 in the entire cohort. Lower CD5 MFI was significantly associated with a shorter time to first therapy. CD5 MFI, combined with established clinical and molecular prognostic markers, significantly improved risk-stratification. CD5 may affect disease outcomes by suppressing signalling through the BCR. Thus, a strategy to modulate CLL cell CD5 expression or function could be a therapeutic approach in CLL.
Assuntos
Antígenos CD5/metabolismo , Leucemia Linfocítica Crônica de Células B/terapia , Receptores de Antígenos de Linfócitos B/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Linfócitos B/metabolismo , Biomarcadores Tumorais/metabolismo , Feminino , Humanos , Leucemia Linfocítica Crônica de Células B/sangue , Leucemia Linfocítica Crônica de Células B/mortalidade , Masculino , Pessoa de Meia-Idade , Prognóstico , Transdução de Sinais/fisiologia , Virginia/epidemiologiaRESUMO
Rituximab therapy for B cell chronic lymphocytic leukemia (B-CLL) has met with mixed success. Among several factors to which resistance can be attributed is failure to activate complement dependent cytotoxicity (CDC) due to protective complement regulatory proteins, including the soluble regulator complement factor H (CFH). We hypothesized that rituximab killing of non-responsive B-CLL cells could be augmented by a novel human monoclonal antibody against CFH. The B cells from 11 patients with B-CLL were tested ex vivo in CDC assays with combinations of CFH monoclonal antibody, rituximab, and a negative control antibody. CDC of rituximab non-responsive malignant B cells from CLL patients could in some cases be augmented by the CFH monoclonal antibody. Antibody-mediated cytotoxicity of cells was dependent upon functional complement. In one case where B-CLL cells were refractory to CDC by the combination of rituximab plus CFH monoclonal antibody, additionally neutralizing the membrane complement regulatory protein CD59 allowed CDC to occur. Inhibiting CDC regulatory proteins such as CFH holds promise for overcoming resistance to rituximab therapy in B-CLL.