Abstract
Simple SummaryCYCLON is a nuclear protein, which has been associated with disease progression and treatment resistance in DLBCL, the most common form of aggressive B-cell lymphoma, but also represents a predictive factor of refractory disease and relapse for immuno-chemotherapy-treated DLBCL patients. The molecular mechanisms related to this unstructured protein remain largely uncharacterized. Here, we performed a mass-spectrometry-based identification of the CYCLON protein interactome that suggested it could exert nucleolar functions related to cell proliferation. Among the CYCLON oncogenic network, we performed an immunohistochemical evaluation of the multi-functional nucleolar protein NPM1 in a DLBCL cohort and showed that CYCLON/NPM1 concomitant expression delineates a poor prognosis subgroup of patients. Multivariate survival analyses demonstrated that specific sub-cellular localizations of CYCLON and NPM1 represent independent novel predictors specifically associated with refractory DLBCL.R-CHOP immuno-chemotherapy significantly improved clinical management of diffuse large B-cell lymphoma (DLBCL). However, 30–40% of DLBCL patients still present a refractory disease or relapse. Most of the prognostic markers identified to date fail to accurately stratify high-risk DLBCL patients. We have previously shown that the nuclear protein CYCLON is associated with DLBCL disease progression and resistance to anti-CD20 immunotherapy in preclinical models. We also recently reported that it also represents a potent predictor of refractory disease and relapse in a retrospective DLBCL cohort. However, only sparse data are available to predict the potential biological role of CYCLON and how it might exert its adverse effects on lymphoma cells. Here, we characterized the protein interaction network of CYCLON, connecting this protein to the nucleolus, RNA processing, MYC signaling and cell cycle progression. Among this network, NPM1, a nucleolar multi-functional protein frequently deregulated in cancer, emerged as another potential target related to treatment resistance in DLBCL. Immunohistochemistry evaluation of CYCLON and NPM1 revealed that their co-expression is strongly related to inferior prognosis in DLBCL. More specifically, alternative sub-cellular localizations of the proteins (extra-nucleolar CYCLON and pan-cellular NPM1) represent independent predictive factors specifically associated to R-CHOP refractory DLBCL patients, which could allow them to be orientated towards risk-adapted or novel targeted therapies.
Highlights
Diffuse large B-cell lymphoma (DLBCL) is a hematological malignancy deriving from the transformation of a mature B lymphocyte
This treatment allows a high response rate with approximately 60–70% of patients achieving a complete response [2], the remaining 30–40% of patients present a refractory disease or relapse, usually within two years. This outcome discrepancy can be explained by the high degree of clinical and biological heterogeneity of diffuse large B-cell lymphoma (DLBCL) [3]. This heterogeneity is related to a wide variety of genomic alterations and phenotypic features that include: (i) the cell-of-origin (COO) gene expression signatures defining “germinal center B cells” (GCB) or “activated B cells” (ABC) DLBCL subtypes, the latter being associated with an inferior prognosis [4,5] but not correlated with R-CHOP response, (ii) gene translocations involving MYC and BCL2/BCL6 and defining the refractory subtype “double/triple hit” (DH/TH), defined as a distinct category in the updated 2016 WHO Classification of Hematopoietic and Lymphoid Tissues termed high-grade B-cell lymphoma (HGBL) and iii) recently identified recurrent mutational events defining genetic subtypes that could have therapeutic implications [6,7,8]
We described that this protein, mainly expressed in testis, was overexpressed in several B-cell lymphoma subtypes and associated with poor prognosis in R-CHOP-treated DLBCL [10,11]
Summary
Diffuse large B-cell lymphoma (DLBCL) is a hematological malignancy deriving from the transformation of a mature B lymphocyte. This outcome discrepancy can be explained by the high degree of clinical and biological heterogeneity of DLBCL [3] This heterogeneity is related to a wide variety of genomic alterations and phenotypic features that include: (i) the cell-of-origin (COO) gene expression signatures defining “germinal center B cells” (GCB) or “activated B cells” (ABC) DLBCL subtypes, the latter being associated with an inferior prognosis [4,5] but not correlated with R-CHOP response, (ii) gene translocations involving MYC and BCL2/BCL6 and defining the refractory subtype “double/triple hit” (DH/TH), defined as a distinct category in the updated 2016 WHO Classification of Hematopoietic and Lymphoid Tissues termed high-grade B-cell lymphoma (HGBL) and iii) recently identified recurrent mutational events defining genetic subtypes that could have therapeutic implications [6,7,8]. R-IPI remains insufficient to recapitulate disease complexity and fails to accurately discriminate refractory/relapse (R/R) DLBCL cases
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
