GFI1B, EVI5, MYB--additional genes that cooperate with the human BCL6 gene to promote the development of lymphomas

EVI5 is an oncogene that regulates the proliferation and metastasis of NSCLC cells

Background

The Ecotropic viral integration site 5 (EVI5), an important protein in regulating cell cycle, cytokinesis and cellular membrane traffic, functions as a stabilizing factor maintaining anaphase-promoting complex/cyclosome (APC/C) inhibitor Emi1 in S/G2 phase. However, the mechanism by which EVI5 promotes malignant transformation of non-small cell lung cancer (NSCLC) remains unknown. In the present study, we addressed the role of EVI5 in NSCLC by regulating tumor growth, migration and invasion.

Methods

The expression levels of EVI5 and miR-486-5p in NSCLC tissues and cells were measured by real-time PCR. Meanwhile, EVI5 and its associated protein expression were analyzed by western blot and co-immunoprecipitation assay. Flow cytometry was performed to determine cell proliferation and apoptosis. CCK-8 and clonogenic assays were used to analyze cell viability. Wound healing, transwell migration and matrigel invasion assays were utilized to assess the motility of tumor cells. To investigate the role of EVI5 in vivo, lung carcinoma xenograft mouse model was applied..

Results

EVI5 was upregulated in NSCLC tissues and cell lines when compared with that in normal tissues and cell line. Knockdown of EVI5 in vitro inhibited tumor cell proliferation, migration and invasion in NSCLC cells. Further, inoculation of EVI5-deficient tumor cells into nude mice suppressed tumor proliferation and metastasis compared to control mice inoculated with unmanipulated tumor cells. These data indicated that EVI5 promote the proliferation of NSCLC cells which was consistent with our previous results. Additionally, we showed that EVI5 was directly regulated by miR-486-5p, and miR-486-5p-EVI5 axis affected the NSCLC migration and invasion through TGF-β/Smad signaling pathway by interacting with TGF-β receptor II and TGF-β receptor I.

Conclusions

Based on these results, we demonstrated a new post-transcriptional mechanism of EVI5 regulation via miR-486-5p and the protumoral function of EVI5 in NSCLC by interacting with Emi1 and/or TGF-β receptors, which provides a new insight into the targeted therapy of NSCLC.

Early loss of Crebbp confers malignant stem cell properties on lymphoid progenitors

Loss-of-function mutations of cyclic-AMP response element binding protein, binding protein (CREBBP) are prevalent in lymphoid malignancies. However, the tumour suppressor functions of CREBBP remain unclear. We demonstrate that loss of Crebbp in murine haematopoietic stem and progenitor cells (HSPCs) leads to increased development of B-cell lymphomas. This is preceded by accumulation of hyperproliferative lymphoid progenitors with a defective DNA damage response (DDR) due to a failure to acetylate p53. We identify a premalignant lymphoma stem cell population with decreased H3K27ac, which undergoes transcriptional and genetic evolution due to the altered DDR, resulting in lymphomagenesis. Importantly, when Crebbp is lost later in lymphopoiesis, cellular abnormalities are lost and tumour generation is attenuated. We also document that CREBBP mutations may occur in HSPCs from patients with CREBBP-mutated lymphoma. These data suggest that earlier loss of Crebbp is advantageous for lymphoid transformation and inform the cellular origins and subsequent evolution of lymphoid malignancies.

EVI5 is a novel independent prognostic predictor in hepatocellular carcinoma after radical hepatectomy

The present study explored the correlation of ecotropic viral integration site 5 (EVI5) expression with clinicopathological features and prognosis in hepatocellular carcinoma (HCC). A total of 205 HCC patients were included retrospectively. Quantitative real-time polymerase chain reaction (RT-qPCR) and western blotting were performed to detect the profile of EVI5 expression in HCC cell lines and fresh tissues. Archived paraffin-embedded specimens were investigated for EVI5 expression by immunohistochemistry (IHC). Both the mRNA and protein levels of EVI5 were obviously upregulated in HCC cell lines and tumor tissues. EVI5 protein level was closely associated with the clinicopathological characteristics, including liver function (P=0.013), venous invasion (P=0.015) and TNM stage (P=0.014). Furthermore, univariate analysis showed that the patients with high EVI5 expression indicated shorter overall survival (OS, P<0.001) and recurrence-free survival (RFS, P=0.001) than those with low EVI5 expression. Importantly, high EVI5 expression also exerts predictive power for higher postoperative recurrence rate by stratified analysis. Multivariate Cox regression analysis demonstrated that OS was correlated with both tumor number (P=0.046) and EVI5 expression (P<0.001) and that RFS was correlated with serum AFP (P=0.023), tumor number (P=0.036) and EVI5 expression (P<0.001). Taken together, EVI5 is an useful independent prognostic marker of survival and recurrence in hepatocellular carcinoma.

Transcription Factor GFI1B in Health and Disease

Many human diseases arise through dysregulation of genes that control key cell fate pathways. Transcription factors (TFs) are major cell fate regulators frequently involved in cancer, particularly in leukemia. The GFI1B gene, coding a TF, was identified by sequence homology with the oncogene growth factor independence 1 (GFI1). Both GFI1 and GFI1B have six C-terminal C2H2 zinc fingers and an N-terminal SNAG (SNAIL/GFI1) transcriptional repression domain. Gfi1 is essential for neutrophil differentiation in mice. In humans, GFI1 mutations are associated with severe congenital neutropenia. Gfi1 is also required for B and T lymphopoiesis. However, knockout mice have demonstrated that Gfi1b is required for development of both erythroid and megakaryocytic lineages. Consistent with this, human mutations of GFI1B produce bleeding disorders with low platelet count and abnormal function. Loss of Gfi1b in adult mice increases the absolute numbers of hematopoietic stem cells (HSCs) that are less quiescent than wild-type HSCs. In keeping with this key role in cell fate, GFI1B is emerging as a gene involved in cancer, which also includes solid tumors. In fact, abnormal activation of GFI1B and GFI1 has been related to human medulloblastoma and is also likely to be relevant in blood malignancies. Several pieces of evidence supporting this statement will be detailed in this mini review.

RPL5 on 1p22.1 is recurrently deleted in multiple myeloma and its expression is linked to bortezomib response

Chromosomal region 1p22 is deleted in ≥20% of multiple myeloma (MM) patients, suggesting the presence of an unidentified tumor suppressor. Using high-resolution genomic profiling, we delimit a 58 kb minimal deleted region (MDR) on 1p22.1 encompassing two genes: ectopic viral integration site 5 (EVI5) and ribosomal protein L5 (RPL5). Low mRNA expression of EVI5 and RPL5 was associated with worse survival in diagnostic cases. Patients with 1p22 deletion had lower mRNA expression of EVI5 and RPL5, however, 1p22 deletion status is a bad predictor of RPL5 expression in some cases, suggesting that other mechanisms downregulate RPL5 expression. Interestingly, RPL5 but not EVI5 mRNA levels were significantly lower in relapsed patients responding to bortezomib and; both in newly diagnosed and relapsed patients, bortezomib treatment could overcome their bad prognosis by raising their progression-free survival to equal that of patients with high RPL5 expression. In conclusion, our genetic data restrict the MDR on 1p22 to EVI5 and RPL5 and although the role of these genes in promoting MM progression remains to be determined, we identify RPL5 mRNA expression as a biomarker for initial response to bortezomib in relapsed patients and subsequent survival benefit after long-term treatment in newly diagnosed and relapsed patients.

ON 01910.Na inhibits growth of diffuse large B-cell lymphoma by cytoplasmic sequestration of sumoylated C-MYB/TRAF6 complex

Diffuse large B-cell lymphoma (DLBCL), the most common lymphoma, shows either no response or development of resistance to further treatment in 30% of the patients that warrants the development of novel drugs. We have reported that ON 01910.Na (rigosertib), a multikinase inhibitor, is selectively cytotoxic for DLBCL and induces more hyperphosphorylation and sumoylation of Ran GTPase-activating protein 1 (RanGAP1) in DLBCL cells than in non-neoplastic lymphoblastoid cell line. However, the exact mechanism of rigosertib-induced cell death in DLBCL remains to be clarified. Here, we analyzed the efficacy of rigosertib against DLBCL cells in vitro and in vivo and its molecular effects on tumor biology. We found for the first time that rigosertib attenuated expression of unmodified and sumoylated tumor necrosis factor receptor-associated factor 6 (TRAF6) and c-Myb and inhibited nuclear entry of sumoylated RanGAP1, TRAF6, and c-Myb that was confirmed by immunofluorescence. Moreover, co-immunoprecipitation showed that rigosertib induced sequestration of c-Myb and TRAF6 in the cytoplasm by stimulating their sumoylation through the RanGAP1*SUMO1/Ubc9 pathway. Specific knockdown of c-Myb and TRAF6 induced tumor cell apoptosis and cell cycle arrest at G1 phase. Xenograft mice bearing lymphoma cells also exhibited effective tumor regression on rigosertib treatment along with cytoplasmic expression of c-Myb and TRAF6. Nuclear expression of c-Myb in clinical cases of DLBCL correlated with a poor prognosis. Thus, suppression of c-Myb and TRAF6 activity may have therapeutic implication in DLBCL. These data support the clinical development of rigosertib in DLBCL.

Germline CARD11 Mutation in a Patient with Severe Congenital B Cell Lymphocytosis

PURPOSE

Activating germline mutations in CARD11 have recently been linked to a rare genetic disorder associated with congenital B cell lymphocytosis. We describe a patient with a similar clinical phenotype who had a de novo germline G123D CARD11 mutation.

METHODS

Whole exome sequencing was performed on DNA from the patient and his biological parents. Laboratory studies examined characteristics of the patient's B and T lymphocytes. A CARD11 cDNA containing the mutation was transfected into a lymphocyte cell line to gain an understanding of its function. RNA sequencing was performed on samples from the patient and from patients with alternate germline CARD11 mutations and differential gene expression analysis was performed.

RESULTS

The patient had a decade-long history of severe polyclonal B lymphocytosis in the 20,000-90,000 lymphocytes/mm(3) range, which was markedly exacerbated by EBV infection and splenectomy at different times. He had a heterozygous germline CARD11 mutation causing a G123D amino acid substitution, which was demonstrated to induce NF-κB activation in unstimulated lymphocytes. In contrast to previous patients with CARD11 mutations, this patient's B cells exhibited higher expression of several cell cycle progression genes, as well as enhanced proliferation and improved survival following B cell receptor stimulation.

CONCLUSIONS

This is the third reported germline and first de novo CARD11 mutation shown to cause congenital B cell lymphocytosis. The mutation was associated with a dramatically greater lymphocytosis than in previously described cases, disproportionate to the level of constitutive NF-κB activation. However, comparative review of the patient's clinical history, combined with additional genomic and functional analyses, underscore other important variables that may affect pathophysiology or regulate mutant CARD11 function in B cell proliferation and disease. We now refer to these patients as having BENTA disease (B cell Expansion with NF-κB and T cell Anergy).