Decreased CD11c-positive dendritic cells in the tumor microenvironment predict double-hit/triple-hit genotype and survival in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma and is a potentially curable disease. However, it is heterogenous, and the prognosis is poor if the tumor cells harbor fusions involving MYC and BCL2 or MYC and BCL6 (double-hit [DH] lymphoma), or fusions involving all three genes (triple-hit [TH] lymphoma). Fluorescence in situ hybridization is currently the gold standard for confirming the presence of DH/TH genotypes. However, the test is laborious and not readily available in some laboratories. Germinal center B (GCB) signatures and dual expression of MYC and BCL2 are commonly used as initial screening markers (traditional model) in clinical practice. Our study proposes immunohistochemical markers for more conveniently and accessibly screening DH/TH genotypes in DLBCL. We retrospectively reviewed the clinical and pathological parameters of patients with DLBCL. We assessed the proliferative index, apoptotic index, and tumor microenvironment (TME), with regard to T cells and CD11c(+) dendritic cells, in formalin-fixed paraffin-embedded tissue. We then generated a decision tree as a screening algorithm to predict DH/TH genotypes and employed decision curve analysis to demonstrate the superiority of this new model in prediction. We also assessed the prognostic significance of related parameters. Our study revealed that GCB subtypes, a Ki67 proliferative index higher than 70%, and BCL2 expression were significantly associated with DH/TH genotypes. Decreased CD11c(+) dendritic cells in the TME indicated additional risk. Our proposed screening algorithm outperformed a traditional model in screening for the DH/TH genotypes. In addition, decreased CD11c(+) dendritic cells in the DLBCL TME were an independent unfavorable prognosticator. In conclusion, we provide a convenient, well-performing model that predicts DH/TH genotypes in DLBCL. The prognostic significance of CD11c(+) dendritic cells in the TME might influence the classification and development of immunotherapy for DLBCL in the future.

New fusion sarcomas: histopathology and clinical significance of selected entities.

Many sarcomas contain gene fusions that can be pathogenetic mechanisms and diagnostic markers. In this article we review selected fusion sarcomas and techniques for their detection. CIC-DUX4 fusion sarcoma is a round cell tumor now considered an entity separate from Ewing sarcoma with a more aggressive clinical course, occurrence in older age, and predilection to soft tissues. It is composed of larger cells than Ewing sarcoma and often has prominent necrosis. Nuclear DUX4 expression is a promising immuno histochemical marker. BCOR-CCNB3 fusion sarcoma is cyclin B3-positive, usually occurs in bone or soft tissue of children, and may mimic a poorly differentiated synovial sarcoma. EWSR1-NFATC2 sarcoma may present in bone or soft tissue. It is typically composed of small round cells in a trabecular pattern in a myxoid matrix resembling myoepithelioma. ACTB-GLI1 fusion sarcoma may mimic a skin adnexal carcinoma, showing focal expression of epithelial markers and S100 protein. NTRK-fusion sarcomas include, in addition to infantile fibrosarcoma with ETV6-NTRK3 fusion, LMNA-NTRK1 fusion sarcoma, a low-grade spindle cell sarcoma seen in peripheral soft tissues in children and young adults. Methods to detect gene fusions include next-generation sequencing panels, anchored multiplex polymerase chain reaction systems to detect partner for a known fusion gene, and comprehensive RNA sequencing to detect virtually all gene fusions. In situ hybridization testing using probes for both fusion partners can be used as an alternative confirmation technique, especially in the absence of satisfactory RNA yield. In addition, fusion protein-related and other immunohistochemical markers can have a high specificity for fusion sarcomas.

End-joining, translocations and cancer.

Fusion genes that are caused by chromosome translocations have been recognized for several decades as drivers of deregulated cell growth in certain types of cancer. In recent years, oncogenic fusion genes have been found in many haematological and solid tumours, demonstrating that translocations are a common cause of malignancy. Sequencing approaches have now confirmed that numerous, non-clonal translocations are a typical feature of cancer cells. These chromosome rearrangements are often highly complex and contain DNA sequence from multiple genomic sites. The factors and pathways that promote translocations are becoming clearer, with non-homologous end-joining implicated as a key source of genomic rearrangements.

MAPK pathway activation through BRAF gene fusion in pilocytic astrocytomas; a novel oncogenic fusion gene with diagnostic, prognostic, and therapeutic potential.

Recently, a new mechanism for activation of B-RAF was identified resulting from a tandem duplication, generating a fusion protein with constitutive BRAF activity and thereby activating the MAPK pathway. Different fusion variants involving BRAF and KIAA1549 were demonstrated, present in 80% of pilocytic astrocytomas in children. As the KIAA1549-BRAF fusion gene is detected at a much lower frequency in diffuse low-grade astrocytomas and survival was much longer than expected in the patients with a 'non-pilocytic' astrocytoma carrying the fusion gene, identification of this fusion gene can be of diagnostic and prognostic value. In the near future, interference with the (fusion gene causing) activation of the MAPK signalling cascade may open new therapeutic avenues for children with pilocytic astrocytomas, as a first line of defence against tumour growth or in situations where the tumour has become refractory to other therapeutic modalities.

1{alpha},25-Dihydroxyvitamin D3 inhibits growth of VCaP prostate cancer cells despite inducing the growth-promoting TMPRSS2:ERG gene fusion.

Vitamin D receptor (VDR) agonists have been shown to reduce the growth of several prostate cancer cell lines. However, the effects of VDR activation have not been examined in the presence of the recently identified androgen-regulated TMPRSS2:ERG gene fusions, which occur in a high percentage of prostate cancers and play a role in growth and invasiveness. In a previous microarray study, we found that VDR activation induces TMPRSS2 expression in LNCaP prostate cancer cells. Here we show that the natural VDR agonist 1alpha,25-dihydroxyvitamin D(3) and its synthetic analog EB1089 increase expression of TMPRSS2:ERG mRNA in VCaP prostate cancer cells; this results in increased ETS-related gene (ERG) protein expression and ERG activity as demonstrated by an increase in the ERG target gene CACNA1D. In VCaP cells, we were not able to prevent EB1089-mediated TMPRSS2:ERG induction with an androgen receptor antagonist, Casodex, although in LNCaP cells, as reported for some other common androgen receptor and VDR target genes, Casodex reduces EB1089-mediated induction of TMPRSS2. However, despite inducing the fusion gene, VDR agonists reduce VCaP cell growth and expression of the ERG target gene c-Myc, a critical factor in VDR-mediated growth inhibition. Thus, the beneficial effects of VDR agonist treatment override some of the negative effects of ERG induction, although others remain to be tested.