Aberrant expression of BCL11B in mycosis fungoides and its potential role in interferon-induced apoptosis

The function of BCL11B in base excision repair contributes to its dual role as an oncogene and a haplo-insufficient tumor suppressor gene

Genetic studies in mice and human cancers established BCL11B as a haploinsufficient tumor suppressor gene. Paradoxically, BCL11B is overexpressed in some human cancers where its knockdown is synthetic lethal. We identified the BCL11B protein in a proximity-dependent biotinylation screen performed with the DNA glycosylase NTHL1. In vitro DNA repair assays demonstrated that both BCL11B and a small recombinant BCL11B213-560 protein lacking transcription regulation potential can stimulate the enzymatic activities of two base excision repair (BER) enzymes: NTHL1 and Pol β. In cells, BCL11B is rapidly recruited to sites of DNA damage caused by laser microirradiation. BCL11B knockdown delays, whereas ectopic expression of BCL11B213-560 accelerates, the repair of oxidative DNA damage. Inactivation of one BCL11B allele in TK6 lymphoblastoid cells causes an increase in spontaneous and radiation-induced mutation rates. In turn, ectopic expression of BCL11B213-560 cooperates with the RAS oncogene in cell transformation by reducing DNA damage and cellular senescence. These findings indicate that BCL11B functions as a BER accessory factor, safeguarding normal cells from acquiring mutations. Paradoxically, it also enables the survival of cancer cells that would otherwise undergo senescence or apoptosis due to oxidative DNA damage resulting from the elevated production of reactive oxygen species.

Screening of potential immune-related genes expressed during sepsis using gene sequencing technology

To screen potential pivotal targets in sepsis through peripheral blood. Septic patients (n = 23) and healthy volunteers (n = 10) were enrolled according to SEPSIS 3.0. Peripheral blood was collected within 24 h of enrollment, RNA-seq was performed on the peripheral blood. The sequencing data was screened for DEGs (p < 0.01; logFC ≥ 2). PPI, WGCNA and survival curve analysis were used to identify potential targets. Then, 5 PBMC samples were conducted by single-cell sequencing for cell lineage location. Finally, mouse sepsis model and clinic samples were performed to verify the targets gene using RNA-seq and RT-PCR, respectively. Compared to the control group, 1007 DEGs were found in septic group. BCL9L, BCL11B, CD247, CD96, MAFG and SAMD3 were in the core of network. These six genes correlated to the survival rate of septic patients and they were mainly expressed in T cells, except that MAFG was located in monocyte cell. The expression levels of six key genes were confirmed by animal and clinical samples. BCL9L, BCL11B, CD247, CD96 and SAMD3 were decreased in sepsis and mainly expressed in the T cell; while MAFG increased in sepsis and localizes to monocytes. These genes may be therapeutic targets for sepsis.

Expression pattern and diagnostic utility of BCL11B in mature T- and NK-cell neoplasms

BCL11B is an essential transcription factor for T-cell lineage commitment and differentiation, and its dysregulation has been shown to be associated with T-cell tumourigenesis. In this study, we investigated BCL11B expression by immunohistochemical analysis in 120 cases of mature T-cell lymphoma, 34 B-cell lymphomas, 11 NK-cell neoplasms and 17 reactive cutaneous conditions. All cases of mycosis fungoides (n=23), primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (n=8) and T-prolymphocytic leukaemia (n=6) were positive for BCL11B and the staining intensity was higher than that of reactive T-cells. Fourteen of 15 (93%) cases of angioimmunoblastic T-cell lymphoma, 10 of 12 (83%) T-large granular lymphocytic leukaemia and 14 of 20 (70%) peripheral T-cell lymphoma, not otherwise specified, were also positive for BCL11B with an intensity comparable to reactive T-cells. Other T-cell neoplasms were uncommonly positive including one of three (33%) cases of primary cutaneous gamma delta T-cell lymphoma, one of four (25%) cases of subcutaneous panniculitis-like T-cell lymphoma, one of four (25%) cases of hepatosplenic T-cell lymphoma, and one of 20 (5%) cases of anaplastic large cell lymphoma (8 ALK-positive, 12 ALK-negative). T-cells in reactive cutaneous infiltrates were also positive for BCL11B, but staining intensity was much weaker than in mycosis fungoides. All NK-cell (n=11) and B-cell neoplasms (n=34) were negative for BCL11B. In conclusion, BCL11B shows a distinct expression pattern in various T-cell neoplasms. BCL11B appears to have utility as another T-cell marker and may be useful in the differential diagnosis of lymphoid neoplasms.

GFI-1 overexpression promotes cell proliferation and apoptosis resistance in mycosis fungoides by repressing Bax and P21

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma. The majority of patients with advanced stage MF are resistant to conventional chemotherapy and thus have a poor prognosis. The transcriptional repressor growth factor independence-1 (GFI-1) serves an important role in the development of T-cells. The results of the present study demonstrated that the expression of GFI-1 at different clinical stages of MF was significantly higher compared with benign inflammatory dermatoses, and there was a significant association with disease progression. Gene knockdown of GFI-1 results in the inhibition of Hut-78 cell proliferation and clone formation in vitro, cell cycle arrest and spontaneous apoptosis, upregulation of cell cycle-related P21, as well as the apoptosis-related proteins Bax and Caspase-3, and downregulation of CDK2. Using luciferase assays, and mutational analysis, it was demonstrated that GFI-1 directly regulated the transcription of P21. The results of the present study highlighted a potential molecular therapeutic approach for the treatment of advanced MF.

Bcl11b/Ctip2 in Skin, Tooth, and Craniofacial System

Ctip2/Bcl11b is a zinc finger transcription factor with dual action (repression/activation) that couples epigenetic regulation to gene transcription during the development of various tissues. It is involved in a variety of physiological responses under healthy and pathological conditions. Its role and mechanisms of action are best characterized in the immune and nervous systems. Furthermore, its implication in the development and homeostasis of other various tissues has also been reported. In the present review, we describe its role in skin development, adipogenesis, tooth formation and cranial suture ossification. Experimental data from several studies demonstrate the involvement of Bcl11b in the control of the balance between cell proliferation and differentiation during organ formation and repair, and more specifically in the context of stem cell self-renewal and fate determination. The impact of mutations in the coding sequences of Bcl11b on the development of diseases such as craniosynostosis is also presented. Finally, we discuss genome-wide association studies that suggest a potential influence of single nucleotide polymorphisms found in the 3’ regulatory region of Bcl11b on the homeostasis of the cardiovascular system.

A Case of Histiocytic Sarcoma Arising from Mycosis Fungoides

Histiocytic sarcoma (HS) is an uncommon malignant neoplasm arising from mature histiocytes and most commonly characterized by the immunophenotypic expression of CD68, CD163, or lysozyme. Although rare, HS arising as a second primary malignancy following hematolymphoid neoplasms has been reported. To our knowledge, this is the first reported case of HS occurring as a second primary malignancy in a patient with mycosis fungoides (MF), with the retained immunophenotype markers CD30 and CD4.

The N-Terminal CCHC Zinc Finger Motif Mediates Homodimerization of Transcription Factor BCL11B

The BCL11B gene encodes a Krüppel-like, sequence-specific zinc finger (ZF) transcription factor that acts as either a repressor or an activator, depending on its posttranslational modifications. The importance of BCL11B in numerous biological processes in multiple organs has been well established in mouse knockout models. The phenotype of the first de novo monoallelic germ line missense mutation in the BCL11B gene (encoding N441K) strongly implies that the mutant protein acts in a dominant-negative manner by neutralizing the unaffected protein through the formation of a nonfunctional dimer. Using a Förster resonance energy transfer-assisted fluorescence-activated cell sorting (FACS-FRET) assay and affinity purification followed by mass spectrometry (AP-MS), we show that the N-terminal CCHC zinc finger motif is necessary and sufficient for the formation of the BCL11B dimer. Mutation of the CCHC ZF in BCL11B abolishes its transcription-regulatory activity. In addition, unlike wild-type BCL11B, this mutant is incapable of inducing cell cycle arrest and protecting against DNA damage-driven apoptosis. Our results confirm the BCL11B dimerization hypothesis and prove its importance for BCL11B function. By mapping the relevant regions to the CCHC domain, we describe a previously unidentified mechanism of transcription factor homodimerization.

PAK1 overexpression promotes cell proliferation in cutaneous T cell lymphoma via suppression of PUMA and p21

BACKGROUND

Cutaneous T cell lymphoma (CTCL) comprises a heterogeneous group of skin-homing T cell tumors. The small guanosine triphosphate effector p21-activated kinase 1 (PAK1) plays an important role in many fundamental cellular functions, including cell motility, proliferation, and apoptosis. The expression of PAK1 is up-regulated in several types of human cancers. However, little is known about the role of PAK1 in the pathogenesis of CTCL.

OBJECTIVE

The aim of this study was to evaluate the expression pattern and underlying mechanism of PAK1 in CTCL.

METHODS

Quantitative real-time polymerase chain reaction(qRT-PCR) was used to detect PAK1 mRNA expression in the peripheral blood mononuclear cells (PBMCs) of patients with CTCL. The expression of PAK1 protein in CTCL tumor tissues was determined by immunohistochemistry. CTCL cell lines were treated with a small molecule inhibitor of PAK1, p21-activated kinase inhibitor III (IPA3), at concentrations of 2, 3.5 and 5 μM for 24 h. Hut 78 and HH CTCL cells were transfected with lentiviral-based PAK1 gene knockdown vectors. We determined the effects of PAK1 knockdown on cell proliferation and apoptosis in CTCL cells by MTS assay and flow cytometry. Animal experiments were performed to investigate the effects of PAK1 knockdown on the growth of tumors in vivo. Transcriptomic sequencing was performed to detect the direct downstream targets of PAK1 silencing. Reverse transcription polymerase chain reaction and western blot analysis were applied to verify the results of the transcriptomic analysis.

RESULTS

We detected PAK1 overexpression in PBMCs and skin lesions from patients with CTCL compared with benign inflammatory dermatoses (BID). Knockdown of PAK1 inhibited cell proliferation and promoted spontaneous apoptosis. In addition, the inhibitory effect of IPA3 was validated in the CTCL cell lines. Additionally, mice injected with PAK1-silenced cells presented with a decreased rate of tumor growth compared with the control groups. Moreover, the mRNA and protein expression of PUMA (BBC3) and p21 (CDKN1A) were increased in PAK1-silenced Hut 78 and HH cells.

CONCLUSIONS

Our data indicated that PAK1 is upregulated in CTCL. PAK1 silencing induced apoptosis and inhibited cell growth by stimulating the expression of PUMA and p21. Thus, PAK1 may be a potential tumor marker and therapeutic target of CTCL.

BCL11B-Mediated Epigenetic Repression Is a Crucial Target for Histone Deacetylase Inhibitors in Cutaneous T-Cell Lymphoma

The treatment options for advanced cutaneous T-cell lymphoma (CTCL) are limited because of its unclear pathogenesis. Histone deacetylase (HDAC) inhibitors (HDACis) are recently developed therapeutics approved for refractory CTCL. However, the response rate is relatively low and unpredictable. Previously, we discovered that BCL11B, a key T-cell development regulator, was aberrantly overexpressed in mycosis fungoides, the most common CTCL, as compared with benign inflammatory skin. In this study, we identified a positive correlation between BCL11B expression and sensitivity to HDACi in CTCL lines. BCL11B suppression in BCL11B-high cells induced cell apoptosis by de-repressing apoptotic pathways and showed synergistic effects with suberoylanilide hydroxamic acid (SAHA), a pan-HDACi. Next, we identified the physical interaction and shared downstream genes between BCL11B and HDAC1/2 in CTCL lines. This interaction was essential in the anti-apoptosis effect of BCL11B, and the synergism between BCL11B suppression and HDACi treatment. Further, in clinical samples from 46 mycosis fungoides patients, BCL11B showed increased but varied expression in advanced tumor stage. Analysis of four patients receiving SAHA treatment suggested a positive correlation between BCL11B expression and favorable response to SAHA treatment. In conclusion, BCL11B may serve as a therapeutic target and a useful marker for improving HDACi efficacy in advanced CTCL.

New aspects of the clinicopathological features and treatment of mycosis fungoides and Sézary syndrome

Mycosis fungoides and Sézary syndrome are T-helper (Th)2-skewed cutaneous lymphomas. The clinical course of mycosis fungoides is classically indolent, manifesting as patches, plaques and tumors. Along with their progression, Th2 dominance tends to be accelerated. In this review, we discuss the epidemiology, clinicopathogenetic features and therapeutic approaches in mycosis fungoides and Sézary syndrome.

SWI/SNF chromatin remodeling complexes and cancer

The identification of mutations and deletions in the SMARCB1 locus in chromosome band 22q11.2 in pediatric rhabdoid tumors provided the first evidence for the involvement of the SWI/SNF chromatin remodeling complex in cancer. Over the last 15 years, alterations in more than 20 members of the complex have been reported in a variety of human tumors. These include germline mutations and copy number alterations in SMARCB1, SMARCA4, SMARCE1, and PBRM1 that predispose carriers to both benign and malignant neoplasms. Somatic mutations, structural abnormalities, or epigenetic modifications that lead to reduced or aberrant expression of complex members have now been reported in more than 20% of malignancies, including both solid tumors and hematologic disorders in both children and adults. In this review, we will highlight the role of SMARCB1 in cancer as a paradigm for other tumors with alterations in SWI/SNF complex members and demonstrate the broad spectrum of mutations observed in complex members in different tumor types.