Positive Regulatory Domain I-binding Factor 1 Research Articles

Abstract LB269: Inhibition Of C-C chemokine receptor 7 extends survival rate in murine model of T-cell acute lymphoblastic leukemia

Abstract C-C Chemokine Receptor 7 (CCR7) expression in pediatric T-cell acute lymphoblastic leukemia (T-ALL) promotes entry of leukemic cells into the central nervous system (CNS), where the disease finds sanctuary from systemic chemotherapies. To confirm that Notch1 drives expression of CCR7, we modified the ROSA26-PRDM14 ([PRDI-BF1 (positive regulatory domain I-binding factor 1) and RIZ (retinoblastoma interacting zinc finger) homology domain containing 14]) MX-1 Cre inducible CD8+ T-ALL mouse model. This model, upon induction with polyI:C, expresses NOTCH1 downstream of PRDM14, and the T-ALL cells enter the CNS during leukemogenesis. We crossed these mice with ROSA26-Luc2 mice, which allows for tracking of T-ALL cells during disease progression. We questioned if these T-ALL cells expressed CCR7. We found that not only do the T-ALL cells express CCR7 and enter the CNS, but that a CCR7 antagonist, CCL198-83 administered during leukemogenesis doubles the mean survival of the CCL198-83 treated mice from 45 to 90 days. These studies provide a novel platform for a potential therapeutic that can be used to limit CNS entry and potentially recycling through the CNS. Citation Format: Anahi Sanchez, Aaron E. Vazquez, Janet M. Valenzuela, Savannah Stanley, Colin A. Bill, Charlotte M. Vines. Inhibition Of C-C chemokine receptor 7 extends survival rate in murine model of T-cell acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB269.

PRDM12 in Health and Diseases.

PRDM12 is a member of the PRDI-BF1 (positive regulatory domain I-binding factor 1) homologous domain (PRDM)-containing protein family, a subfamily of Kruppel-like zinc finger proteins, controlling key processes in the development of cancer. PRDM12 is expressed in a spatio-temporal manner in neuronal systems where it exerts multiple functions. PRDM12 is essential for the neurogenesis initiation and activation of a cascade of downstream pro-neuronal transcription factors in the nociceptive lineage. PRDM12 inactivation, indeed, results in a complete absence of the nociceptive lineage, which is essential for pain perception. Additionally, PRDM12 contributes to the early establishment of anorexigenic neuron identity and the maintenance of high expression levels of pro-opiomelanocortin, which impacts on the program bodyweight homeostasis. PRDMs are commonly involved in cancer, where they act as oncogenes/tumor suppressors in a “Yin and Yang” manner. PRDM12 is not usually expressed in adult normal tissues but its expression is re-activated in several cancer types. However, little information is currently available on PRDM12 expression in cancers and its mechanism of action has not been thoroughly described. In this review, we summarize the recent findings regarding PRDM12 by focusing on four main biological processes: neurogenesis, pain perception, oncogenesis and cell metabolism. Moreover, we wish to highlight the importance of future studies focusing on the PRDM12 signaling pathway(s) and its role in cancer onset and progression.

Emerging Roles of PRDM Factors in Stem Cells and Neuronal System: Cofactor Dependent Regulation of PRDM3/16 and FOG1/2 (Novel PRDM Factors).

PRDI-BF1 (positive regulatory domain I-binding factor 1) and RIZ1 (retinoblastoma protein-interacting zinc finger gene 1) (PR) homologous domain containing (PRDM) transcription factors are expressed in neuronal and stem cell systems, and they exert multiple functions in a spatiotemporal manner. Therefore, it is believed that PRDM factors cooperate with a number of protein partners to regulate a critical set of genes required for maintenance of stem cell self-renewal and differentiation through genetic and epigenetic mechanisms. In this review, we summarize recent findings about the expression of PRDM factors and function in stem cell and neuronal systems with a focus on cofactor-dependent regulation of PRDM3/16 and FOG1/2. We put special attention on summarizing the effects of the PRDM proteins interaction with chromatin modulators (NuRD complex and CtBPs) on the stem cell characteristic and neuronal differentiation. Although PRDM factors are known to possess intrinsic enzyme activity, our literature analysis suggests that cofactor-dependent regulation of PRDM3/16 and FOG1/2 is also one of the important mechanisms to orchestrate bidirectional target gene regulation. Therefore, determining stem cell and neuronal-specific cofactors will help better understanding of PRDM3/16 and FOG1/2-controlled stem cell maintenance and neuronal differentiation. Finally, we discuss the clinical aspect of these PRDM factors in different diseases including cancer. Overall, this review will help further sharpen our knowledge of the function of the PRDM3/16 and FOG1/2 with hopes to open new research fields related to these factors in stem cell biology and neuroscience.

Deletion of the Prdm3 Gene Causes a Neuronal Differentiation Deficiency in P19 Cells.

PRDM (PRDI-BF1 (positive regulatory domain I-binding factor 1) and RIZ1 (retinoblastoma protein-interacting zinc finger gene 1) homologous domain-containing) transcription factors are a group of proteins that have a significant impact on organ development. In our study, we assessed the role of Prdm3 in neurogenesis and the mechanisms regulating its expression. We found that Prdm3 mRNA expression was induced during neurogenesis and that Prdm3 gene knockout caused premature neuronal differentiation of the P19 cells and enhanced the growth of non-neuronal cells. Interestingly, we found that Gata6 expression was also significantly upregulated during neurogenesis. We further studied the regulatory mechanism of Prdm3 expression. To determine the role of GATA6 in the regulation of Prdm3 mRNA expression, we used a luciferase-based reporter assay and found that Gata6 overexpression significantly increased the activity of the Prdm3 promoter. Finally, the combination of retinoic acid receptors α and β, along with Gata6 overexpression, further increased the activity of the luciferase reporter. Taken together, our results suggest that in the P19 cells, PRDM3 contributed to neurogenesis and its expression was stimulated by the synergism between GATA6 and the retinoic acid signaling pathway.

Multifaceted Role of PRDM Proteins in Human Cancer.

The PR/SET domain family (PRDM) comprise a family of genes whose protein products share a conserved N-terminal PR [PRDI-BF1 (positive regulatory domain I-binding factor 1) and RIZ1 (retinoblastoma protein-interacting zinc finger gene 1)] homologous domain structurally and functionally similar to the catalytic SET [Su(var)3-9, enhancer-of-zeste and trithorax] domain of histone methyltransferases (HMTs). These genes are involved in epigenetic regulation of gene expression through their intrinsic HMTase activity or via interactions with other chromatin modifying enzymes. In this way they control a broad spectrum of biological processes, including proliferation and differentiation control, cell cycle progression, and maintenance of immune cell homeostasis. In cancer, tumor-specific dysfunctions of PRDM genes alter their expression by genetic and/or epigenetic modifications. A common characteristic of most PRDM genes is to encode for two main molecular variants with or without the PR domain. They are generated by either alternative splicing or alternative use of different promoters and play opposite roles, particularly in cancer where their imbalance can be often observed. In this scenario, PRDM proteins are involved in cancer onset, invasion, and metastasis and their altered expression is related to poor prognosis and clinical outcome. These functions strongly suggest their potential use in cancer management as diagnostic or prognostic tools and as new targets of therapeutic intervention.

PRDM14 promotes malignant phenotype and correlates with poor prognosis in colorectal cancer.

Emerging evidence suggests that stemness in cancer cells is a cause of drug resistance or metastasis and is an important therapeutic target. PR [positive regulatory domain I-binding factor 1 (PRDI-BF1) and retinoblastoma protein-interacting zinc finger gene (RIZ1)] domain containing 14 (PRDM14), that regulates pluripotency in primordial germ cell, has reported the overexpression and function of stemness in various malignancies, suggesting it as the possible therapeutic target. However, to our knowledge, there have been no reports on the expression and function of PRDM14 in colorectal cancer (CRC). Therefore, we investigated the expression and the role of PRDM14 in CRC. We performed immunohistochemistry evaluations and assessed PRDM14 expression on 414 primary CRC specimens. Colon cancer cell lines were subjected to functional and stemness assays in vitro and in vivo. We found that PRDM14 positive staining exhibited heterogeneity in the CRC primary tumor, especially at the tumor invasion front. The aberrant expression of PRDM14 at the invasion front was associated with lymph node metastasis and disease stage in patients with CRC. Furthermore, the multivariate analysis revealed high PRDM14 expression as an independent prognostic factor in the patients with Stage III CRC. Overexpression of PRDM14 enhanced the invasive, drug-resistant and stem-like properties in colon cancer cells in vitro and tumorigenicity in vivo. Our findings suggest that PRDM14 is involved in progression and chemoresistance of CRC, and is a potential prognostic biomarker and therapeutic target in the CRC patients.

Histone deacetylase inhibitors activate CIITA and MHC class II antigen expression in diffuse large B‐cell lymphoma

Diffuse large B-cell lymphoma (DLBCL), the most common form of non-Hodgkin's lymphoma (NHL) diagnosed in the USA, consists of at least two distinct subtypes: germinal centre B (GCB) and activated B-cell (ABC). Decreased MHC class II (MHCII) expression on the tumours in both DLBCL subtypes directly correlates with significant decreases in patient survival. One common mechanism accounting for MHCII down-regulation in DLBCL is reduced expression of the MHC class II transactivator (CIITA), the master regulator of MHCII transcription. Furthermore, reduced CIITA expression in ABC DLBCL correlates with the presence of the transcriptional repressor positive regulatory domain-I-binding factor-1 (PRDI-BF1). However, the mechanisms underlying down-regulation of CIITA in GCB DLBCL are currently unclear. In this study, we demonstrate that neither PRDI-BF1 nor CpG hypermethylation at the CIITA promoters are responsible for decreased CIITA in GCB DLBCL. In contrast, histone modifications associated with an open chromatin conformation and active transcription were significantly lower at the CIITA promoters in CIITA(-) GCB cells compared with CIITA(+) B cells, which suggests that epigenetic mechanisms contribute to repression of CIITA transcription. Treatment of CIITA(-) or CIITA(low) GCB cells with several different histone deacetylase inhibitors (HDACi) activated modest CIITA and MHCII expression. However, CIITA and MHCII levels were significantly higher in these cells after exposure to the HDAC-1-specific inhibitor MS-275. These results suggest that CIITA transcription is repressed in GCB DLBCL cells through epigenetic mechanisms involving HDACs, and that HDACi treatment can alleviate repression. These observations may have important implications for patient therapy.

Blimp-1 is a tumor suppressor gene in lymphoid malignancies

B lymphocyte-induced maturation protein (Blimp-1) is a transcriptional factor, which controls the terminal differentiation of mature B cells to plasma cells. Blimp-1 is also called positive regulatory domain I-binding factor-1 (PRDI-BF1) or PR (PRDI-BF1-RIZ) domain zinc finger protein 1 (PRDM1). Furthermore, Blimp-1 is located in chromosome 6q21-22.1, a region frequently deleted in several tumors including lymphoid malignancies and has been supposed to be a candidate of tumor suppressor gene. Recently, mutational inactivation of Blimp-1 has been identified in a subset of diffuse large B-cell lymphomas of the activated B-cell type. In addition, an important role for Blimp-1 in maintaining the homeostasis of effector T cells is emerging and high expression of Blimp-1beta, a splicing variant of Blimp-1, have been presumed to be associated with poor prognosis in T cell lymphoma although this aspect of the gene needs further investigation. For this reason, we focused on the tumor suppressor function of Blimp-1 on not only B but also T cell malignancies in this review.

PU.1 Regulates Positive Regulatory Domain I-Binding Factor 1/Blimp-1 Transcription in Lymphoma Cells

The human positive regulatory domain I-binding factor 1 (PRDI-BF1) and its murine homolog Blimp-1 promote differentiation of mature B cells into Ab-secreting plasma cells. In contrast, ectopic expression of PRDI-BF1 in lymphoma cells can lead to inhibition of proliferation or apoptosis. However, little is currently known about the regulation of PRDM1, the gene encoding PRDI-BF1. This report establishes that in lymphoma cells stimulation through the BCR rapidly induces endogenous PRDM1 at the level of transcription with minor changes in mRNA stability. The induced PRDM1-encoded protein localizes to its target genes in vivo and suppresses their expression. In vivo genomic footprinting of the PRDM1 promoter in unstimulated lymphoma and myeloma cells reveals multiple common in vivo occupied elements throughout the promoter. Further functional and structural analysis of the promoter reveals that the promoter is preloaded and poised for activation in the B cell lines. The transcription factor PU.1 is shown to be required for the BCR-induced expression of PRDM1 in lymphoma cells and in PU.1-positive myeloma cells. Activation of PRDM1 is associated with loss of the corepressor transducin-like enhancer of split 4 from the PU.1 complex. These findings indicate that PRDM1 is poised for activation in lymphoma cells and therefore may be a potential therapeutic target to inhibit lymphoma cell proliferation and survival.

B Lymphocyte-Induced Maturation Protein-1/Positive Regulatory Domain I-Binding Factor 1 regulates two amino peptidases associated with antigen processing (78.9)

Abstract A diverse repertoire of specifically-trimmed peptides is presented by the Major Histocompatibility Complex Class I (MHCI) pathway of antigen presentation for immune surveillance by CD8+ cytotoxic T cells. These peptides are generated in the cytosol, then trimmed by amino peptidases to meet the binding requirements of MHCI. Two endoplasmic reticulum amino peptidases, ERAP1 and ERAP2, perform this function in human cells. Positive Regulatory Domain I-Binding Factor 1 (PRDI-BF1) called B Lymphocyte Induced Maturation Protein-1 (BLIMP-1) in mice drives the differentiation of B lymphocytes into plasma cells. We demonstrated that PRDI-BF1/BLIMP-1 regulates the MHCII pathway of antigen presentation by repressing MHC class II transactivator (CIITA) transcription. We now show that PRDI-BF1/BLIMP-1 plays a key role in modulating the MHCI pathway. Functional promoter analyses and protein/DNA binding studies demonstrate that both full-length PRDI-BF1/BLIMP-1 and a truncated form of this transcription factor called PRDI-BF1β, expressed in myeloma cells and associated with resistance to chemotherapy in diffuse large B-cell and T-cell lymphoma, mediate repression of ERAP1 and ERAP2. Repression occurs through a site nearly identical in sequence to a site for repression of CIITA. IFN-γ or ectopic expression of IRF-1 up regulates ERAP expression even in PRDI-BF1/BLIMP-1-expressing cells. The goal of this work is to uncover pathways useful in therapeutic approaches to improve the ability of the immune system to recognize and destroy PRDI-BF1-expressing tumors. Supported by grants from the National Cancer Institute (RO1CA102203) and MEDCEN Community Health Foundation of Central Georgia.

IFN-γ up-regulates expression of the MHC class II transactivator (CIITA) type IV promoter in multiple myeloma cells (35.20)

Abstract MHC Class II transactivator (CIITA) is the master transcriptional regulator of MHC class II (MHC II) genes. MHC II expression is central to antigen presentation and the immune recognition of tumor cells. The human CIITA gene, MHC2TA, is regulated in a cell-type specific manner by multiple promoters. Regulation by IFN-γ is generally via the type IV promoter (pIV) and involves the binding of IFN regulatory factor (IRF)-1 and IRF-2. The response of pIV to IFN-γ was examined in myeloma cells. Western blot and RT-PCR show that STAT1 is activated by phosphorylation and IRF-1 RNA expression increases in response to IFN-γ. RT-PCR and functional promoter analyses show that IFN-γ up-regulates the activity of MHC2TA pIV as does ectopic expression of IRF-1 or IRF-2, and the IRF-E site is required. Binding studies confirm IRF-1 and IRF-2 binding to MHC2TA pIV. Myeloma cells express positive regulatory domain I-binding factor 1 (PRDI-BF1), also called B lymphocyte-induced maturation protein-1 (Blimp-1), which represses both MHC2TA pIII and pIV. Importantly, these cells retain the ability to up-regulate CIITA pIV and MHC II in response to IFN-γ. Although PRDI-BF1/Blimp-1 diminishes the ability of myeloma cells to present antigen by limiting CIITA and MHC II expression, these studies indicate that expression can be restored by the use of cytokines like IFN-γ. Research support: RO1CA10220, RO1CA114504, MEDCEN Foundation of Central GA

Targeting Positive Regulatory Domain I-Binding Factor 1 and X Box-Binding Protein 1 Transcription Factors by Multiple Myeloma-Reactive CTL

Growing evidence indicates that multiple myeloma (MM) and other malignancies are susceptible to CTL-based immune interventions. We studied whether transcription factors inherently involved in the terminal differentiation of mature B lymphocytes into malignant and nonmalignant plasma cells provide MM-associated CTL epitopes. HLA-A*0201 (A2.1) transgenic mice were used to identify A2.1-presented peptide Ag derived from the plasma cell-associated transcriptional regulators, positive regulatory domain I-binding factor 1 (PRDI-BF1) and X box-binding protein 1 (XBP-1). A2.1-restricted CTL specific for PRDI-BF1 and XBP-1 epitopes efficiently killed a variety of MM targets. PRDI-BF1- and XBP-1-reactive CTL were able to recognize primary MM cells from A2.1(+) patients. Consistent with the expression pattern of both transcription factors beyond malignant and nonmalignant plasma cells, PRDI-BF1- and XBP-1-specific CTL activity was not entirely limited to MM targets, but was also associated with lysis of certain other malignancies and, in defined instances, with low-to-intermediate level recognition of a few types of normal cells. Our results also indicate that the A2.1-restricted, PRDI-BF1- and XBP-1-specific human CD8(+) T cell repertoire is affected by partial self tolerance and may thus require the transfer of high-affinity TCR to break tolerance. We conclude that transcription factors governing terminal cellular differentiation may provide MM- and tumor-associated CTL epitopes.

Positive Regulatory Domain I Binding Factor 1 Silences Class II Transactivator Expression in Multiple Myeloma Cells

The major histocompatibility complex (MHC) class II transactivator (CIITA) acts as a master switch to activate expression of the genes required for MHC-II antigen presentation. During B-cell to plasma cell differentiation, MHC-II expression is actively silenced, but the mechanism has been unknown. In plasma cell tumors such as multiple myeloma the repression of MHC-II is associated with the loss of CIITA. We have identified that positive regulatory domain I binding factor 1 (PRDI-BF1), a transcriptional repressor, inhibits CIITA expression in multiple myeloma cell lines. Repression of CIITA depends on the DNA binding activity of PRDI-BF1 and its specific binding site in the CIITA promoter. Deletion of a histone deacetylase recruitment domain in PRDI-BF1 does not inhibit repression of CIITA nor does blocking histone deacetylase activity. This is in contrast to PRDI-BF1 repression of the c-myc promoter. Repression of CIITA requires either the N-terminal acidic and conserved PR motif or the proline-rich domain. PRDI-BF1 has been shown to be a key regulator of B-cell and macrophage differentiation. These findings now indicate that PRDI-BF1 has at least two mechanisms of repression whose function is dependent on the nature of the target promoter. Importantly, PRDI-BF1 is defined as the key molecule in silencing CIITA and thus MHC-II in multiple myeloma cells.

CD27/CD70 Interaction Augments IgE Secretion by Promoting the Differentiation of Memory B Cells into Plasma Cells

The induction of IgE switching in B cells requires several signals given by cytokines and cell contact-delivered signals. Here, we investigated the role of CD27/CD70 interaction in B cell IgE synthesis. The addition of CD27 ligand (CD70) transfectants to B cell cultures increased the IgE synthesis synergistically in the presence of IL-4 plus anti-CD40 mAb (anti-CD40). The effect of CD70 transfectants was dose dependent and was completely blocked by anti-CD70 mAb. CD27+ B cells had the ability to produce IgE, which was increased by contact with CD70 transfectants, whereas CD27- B cells did not produce IgE. CD27/CD70 interaction enhanced B cell proliferation in the presence of IL-4 or IL-4 plus anti-CD40. The augmentation of B cell proliferation by CD70 transfectants was apparent in CD27+ B cells, but was mild in CD27- B cells. The helper activity for IgE synthesis by the CD27/CD70 interaction did not contribute to the enhancement of germline epsilon transcripts. Flow cytometric and morphological analyses demonstrated that the addition of CD70 transfectants to B cell cultures remarkably promoted differentiation into plasma cells in the presence of IL-4 and CD40 signaling. Finally, CD27 cross-linking resulted in the up-regulation of positive regulatory domain I-binding factor-1. Taken together, our findings indicate that signaling via CD27 on B cells induces IgE synthesis, in cooperation with IL-4 and CD40 signaling, by promoting the generation of plasma cells through up-regulation of positive regulatory domain I-binding factor-1.