Colorimetric In Situ Hybridization Identifies MYC Gene Signal Clusters Correlating With Increased Copy Number, mRNA, and Protein in Diffuse Large B-Cell Lymphoma

Abstract

Abnormalities of the MYC oncogene on chromosome 8 are characteristic of Burkitt lymphoma and other aggressive B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL). We recently described a colorimetric in situ hybridization (CISH) method for detecting extra copies of the MYC gene in DLBCL and the frequent occurrence of excess copies of discrete MYC signals in the context of diploidy or polyploidy of chromosome 8, which correlated with increased mRNA signals. We further observed enlarged MYC signals, which were counted as a single gene copy but, by their dimension and unusual shape, likely consisted of “clusters” of MYC genes. In this study, we sought to further characterize these clusters of MYC signals by determining whether the presence of these correlated with other genetic features, mRNA levels, protein, and overall survival. We found that MYC clusters correlated with an abnormal MYC locus and with increased mRNA. MYC mRNA correlated with protein levels, and both increased mRNA and protein correlated with poorer overall survival. MYC clusters were seen in both the germinal center and activated B-cell subtypes of DLBCL. Clusters of MYC signals may be an underappreciated, but clinically important, feature of aggressive B-cell lymphomas with potential prognostic and therapeutic relevance.

Acute myeloid leukaemia: expression of MYC protein and its association with cytogenetic risk profile and overall survival

“…We failed to identify any specific translocation related to MYC locus (8q24) in this cohort, while MYC amplifications are not performed as part of routine clinical investigations. However, this may not be considered as restraint, as ample evidence in literature is available to prove that MYC protein expression is associated with MYC translocation/amplification . Another limitation of current study is lack of recently defined additional molecular risk factors (such a FLT3, NPM1 and CEBPA mutation status) in this cohort.…”

Approach to the diagnosis and treatment of high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements

“…52,53 However, this has not been consistently shown to be associated with increased MYC protein expression or an inferior clinical outcome. 17,[53][54][55][56][57][58] Other factors can affect MYC levels without directly altering the integrity or location of the MYC locus. Many signaling pathways, including BCR and NF-kB signaling, can lead to increased transcription of MYC through direct and indirect interactions at the MYC promoter as reviewed by Wierstra and Alves.…”

New clues to the molecular pathogenesis of Burkitt lymphoma revealed through next-generation sequencing

“…These samples were found to have chromosome 11q abnormalities, suggesting a new genetic signature for a minority of Burkitt lymphoma cases [31 & ]. A colorimetric in-situ hybridization assay developed to identify multiple copies of MYC in DLBCL revealed increased RNA and protein expression of MYC in clusters near MYC loci that had increased copy number because of either amplification or translocation [39]. In particular, MYC-IG translocations were found to be associated with significantly worse overall survival rates than patients with MYC-non-IG translocations.…”