Genetic rearrangement of FOXP1 is predominantly detected in a subset of diffuse large B-cell lymphomas with extranodal presentation

Epigenetic, Metabolic, and Immune Crosstalk in Germinal-Center-Derived B-Cell Lymphomas: Unveiling New Vulnerabilities for Rational Combination Therapies

B-cell non-Hodgkin lymphomas (B-NHLs) are highly heterogenous by genetic, phenotypic, and clinical appearance. Next-generation sequencing technologies and multi-dimensional data analyses have further refined the way these diseases can be more precisely classified by specific genomic, epigenomic, and transcriptomic characteristics. The molecular and genetic heterogeneity of B-NHLs may contribute to the poor outcome of some of these diseases, suggesting that more personalized precision-medicine approaches are needed for improved therapeutic efficacy. The germinal center (GC) B-cell like diffuse large B-cell lymphomas (GCB-DLBCLs) and follicular lymphomas (FLs) share specific epigenetic programs. These diseases often remain difficult to treat and surprisingly do not respond advanced immunotherapies, despite arising in secondary lymphoid organs at sites of antigen recognition. Epigenetic dysregulation is a hallmark of GCB-DLBCLs and FLs, with gain-of-function (GOF) mutations in the histone methyltransferase EZH2, loss-of-function (LOF) mutations in histone acetyl transferases CREBBP and EP300, and the histone methyltransferase KMT2D representing the most prevalent genetic lesions driving these diseases. These mutations have the common effect to disrupt the interactions between lymphoma cells and the immune microenvironment, via decreased antigen presentation and responsiveness to IFN-γ and CD40 signaling pathways. This indicates that immune evasion is a key step in GC B-cell lymphomagenesis. EZH2 inhibitors are now approved for the treatment of FL and selective HDAC3 inhibitors counteracting the effects of CREBBP LOF mutations are under development. These treatments can help restore the immune control of GCB lymphomas, and may represent optimal candidate agents for more effective combination with immunotherapies. Here, we review recent progress in understanding the impact of mutant chromatin modifiers on immune evasion in GCB lymphomas. We provide new insights on how the epigenetic program of these diseases may be regulated at the level of metabolism, discussing the role of metabolic intermediates as cofactors of epigenetic enzymes. In addition, lymphoma metabolic adaptation can negatively influence the immune microenvironment, further contributing to the development of immune cold tumors, poorly infiltrated by effector immune cells. Based on these findings, we discuss relevant candidate epigenetic/metabolic/immune targets for rational combination therapies to investigate as more effective precision-medicine approaches for GCB lymphomas.

Gastrointestinal Tract Lymphomas: A Review of the Most Commonly Encountered Lymphomas

CONTEXT.—

The gastrointestinal (GI) tract is the most common site of extranodal non-Hodgkin lymphoma, accounting for 20% to 40% of all extranodal lymphomas. The majority of these are systemic processes secondarily involving the GI tract. Primary GI lymphomas are less common, accounting for approximately 10% to 15% of all non-Hodgkin lymphoma. Most non-Hodgkin lymphoma involving the GI tract are of B-cell lineage, of which diffuse large B-cell lymphoma is the most common subtype, irrespective of location.

OBJECTIVE.—

To review the lymphoproliferative neoplasms of B-cell and T-cell lineage involving the luminal GI tract according to the most prevalent subtypes at each anatomic site.

DATA SOURCE.—

Systematic search of the PubMed database for updated literature on GI lymphomas epidemiology, subtypes, clinical, endoscopic, and genetic findings. Histologic images are derived from our collection of clinical cases.

CONCLUSIONS.—

The GI tract is the most common site of extranodal lymphoproliferative neoplasms. Recognition of the most frequently encountered GI lymphomas is imperative for patient management and treatment.

Novel markers in pediatric-type follicular lymphoma

The aim of this study was to review the histopathological, phenotypic, and molecular characteristics of pediatric-type follicular lymphoma (PTFL) and to assess the diagnostic value of novel immunohistochemical markers in distinguishing PTFL from follicular hyperplasia (FH). A total of 13 nodal PTFLs were investigated using immunohistochemistry, fluorescence in situ hybridization (FISH), and PCR and were compared with a further 20 reactive lymph nodes showing FH. Morphologically, PTFL cases exhibited a follicular growth pattern with irregular lymphoid follicles in which the germinal centers were composed of numerous blastoid cells showing a starry-sky appearance. Immunohistochemistry highlighted preserved CD10 (13/13) and BCL6 (13/13) staining, CD20 (13/13) positivity, a K light chain predominance (7/13), and partial BCL2 expression in 6/13 cases (using antibodies 124, E17, and SP66). The germinal center (GC)–associated markers stathmin and LLT-1 were positive in most of the cases (12/13 and 12/13, respectively). Interestingly, FOXP-1 was uniformly positive in PTFL (12/13 cases) in contrast to reactive GCs in FH, where only a few isolated positive cells were observed. FISH revealed no evidence of BCL2, BCL6, or MYC rearrangements in the examined cases. By PCR, clonal immunoglobulin gene rearrangements were detected in 100% of the tested PTFL cases. Our study confirmed the unique morphological and immunophenotypic features of PTFL and suggests that FOXP-1 can represent a novel useful diagnostic marker in the differential diagnosis between PTFL and FH.

Ontogeny, Genetics, Molecular Biology, and Classification of B- and T-Cell Non-Hodgkin Lymphoma

Mature B- and T-cell lymphomas are diverse in their biology, etiology, genetics, clinical behavior, and response to specific therapies. Here, we review the principles of diagnostic classification for non-Hodgkin lymphomas, summarize the characteristic features of major entities, and place recent biological and molecular findings in the context of principles that are applicable across the spectrum of mature lymphoid cancers.

MALT Lymphoma as a Model of Chronic Inflammation-Induced Gastric Tumor Development

Mucosa-associated lymphoid tissue (MALT) lymphoma, or extranodal marginal zone lymphoma of MALT, is an indolent B-cell non-Hodgkin lymphoma linked with preexisting chronic inflammation. The stomach is the most commonly affected organ and the MALT lymphoma pathogenesis is clearly associated with Helicobacter pylori gastroduodenitis. Inflammation induces the lymphoid infiltrates in extranodal sites, where the lymphoma then subsequently develops. Genetic aberrations arise through the release of reactive oxygen species (ROS), H. pylori-induced endonucleases, and other effects. The involvement of nuclear factor kappa B (NF-κB) pathway activation, a critical regulator of pro-inflammatory responses, further highlights the role of inflammation in gastric MALT lymphoma. The NF-κB pathway regulates key elements of normal lymphocyte function, including the transcription of proliferation-promoting and anti-apoptotic genes. Aberrant constitutive activation of NF-κB signaling can lead to autoimmunity and malignancy. NF-κB pathway activation can happen through both the canonical and non-canonical pathways and can be caused by multiple genetic aberrations such as t(11;18)(q12;q21), t(1;14)(p22;q32), and t(14;18)(q32;q21) translocations, chronic inflammation and even directly by H. pylori-associated mechanisms. Gastric MALT lymphoma is considered one of the best models of how inflammation initiates genetic events that lead to oncogenesis, determines tumor biology, dictates clinical behavior and leads to viable therapeutic targets. The purpose of this review is to present gastric MALT lymphoma as an outstanding example of the close pathogenetic link between chronic inflammation and tumor development and to describe how this information can be integrated into daily clinical practice.

Hide or defend, the two strategies of lymphoma immune evasion: potential implications for immunotherapy

Evading immune eradication is a prerequisite for neoplastic progression and one of the hallmarks of cancer. Here, we review the different immune escape strategies of lymphoma and classify them into two main mechanisms. First, lymphoma cells may “hide” to become invisible to the immune system. This can be achieved by losing or downregulating MHC and/or molecules involved in antigen presentation (including antigen processing machinery and adhesion molecules), thereby preventing their recognition by the immune system. Second, lymphoma cells may “defend” themselves to become resistant to immune eradication. This can be achieved in several ways: by becoming resistant to apoptosis, by expressing inhibitory ligands that deactivate immune cells and/or by inducing an immunosuppressive (humoral and cellular) microenvironment. These immune escape mechanisms may have therapeutic implications. Their identification may be used to guide “personalized immunotherapy” for lymphoma.

Recent advances in understanding the biology of marginal zone lymphoma

There are three different marginal zone lymphomas (MZLs): the extranodal MZL of mucosa-associated lymphoid tissue (MALT) type (MALT lymphoma), the splenic MZL, and the nodal MZL. The three MZLs share common lesions and deregulated pathways but also present specific alterations that can be used for their differential diagnosis. Although trisomies of chromosomes 3 and 18, deletions at 6q23, deregulation of nuclear factor kappa B, and chromatin remodeling genes are frequent events in all of them, the three MZLs differ in the presence of recurrent translocations, mutations affecting the NOTCH pathway, and the transcription factor Kruppel like factor 2 ( KLF2) or the receptor-type protein tyrosine phosphatase delta ( PTPRD). Since a better understanding of the molecular events underlying each subtype may have practical relevance, this review summarizes the most recent and main advances in our understanding of the genetics and biology of MZLs.

Foxp1 controls mature B cell survival and the development of follicular and B-1 B cells

Many patients with B cell lymphoma carry alterations in the gene coding for the transcription factor Foxp1. High Foxp1 expression has been linked to poor prognosis in those malignancies; however, the physiological functions of Foxp1 in mature B cells remain unknown. By employing genetic mouse models, we show that Foxp1 deletion results in reduced B cell numbers and impaired antibody production upon T cell-independent immunization. Foxp1-deficient mature B cells are impaired in survival and exhibit an increased proliferation capacity, and transcriptional analysis identified defective expression of the prosurvival Bcl-xl gene. Our results provide insight into the regulation of mature B cell survival by Foxp1 and have implications for understanding the role of Foxp1 in the development of B cell malignancies.

The transcription factor Foxp1 is critical for early B cell development. Despite frequent deregulation of Foxp1 in B cell lymphoma, the physiological functions of Foxp1 in mature B cells remain unknown. Here, we used conditional gene targeting in the B cell lineage and report that Foxp1 disruption in developing and mature B cells results in reduced numbers and frequencies of follicular and B-1 B cells and in impaired antibody production upon T cell-independent immunization in vivo. Moreover, Foxp1-deficient B cells are impaired in survival even though they exhibit an increased capacity to proliferate. Transcriptional analysis identified defective expression of the prosurvival Bcl-2 family gene Bcl2l1 encoding Bcl-xl in Foxp1-deficient B cells, and we identified Foxp1 binding in the regulatory region of Bcl2l1. Transgenic overexpression of Bcl2 rescued the survival defect in Foxp1-deficient mature B cells in vivo and restored peripheral B cell numbers. Thus, our results identify Foxp1 as a physiological regulator of mature B cell survival mediated in part via the control of Bcl-xl expression and imply that this pathway might contribute to the pathogenic function of aberrant Foxp1 expression in lymphoma.

Clinical aspects and therapy of gastrointestinal MALT lymphoma

Extranodal marginal zone B-cell lymphomas of the mucosa associated lymphoid tissue (MALT) arise from lymphoid populations that are induced by chronic inflammation in extranodal sites. Among the MALT lymphomas, gastrointestinal (GIT) MALT lymphoma is the most frequent compared to non-GIT MALT lymphoma arising from other sites. Gastric MALT lymphoma has been the first to be described with the evidence of an etiopathogenetic link provided by the association between Helicobacter pylori-positive gastritis and gastric MALT lymphoma. Indeed, successful eradication of this micro-organism with antibiotics can be followed by a lymphoma regression in most cases. When there is no association with Helicobacter pylori, there is no clear therapeutic consensus. Both radiotherapy and systemic treatments with chemotherapy and anti-CD20 antibodies are efficacious and thus the experience of individual centers and each patient's preferences in terms of adverse effects are important parameters in the decision process.

The small FOXP1 isoform predominantly expressed in activated B cell-like diffuse large B-cell lymphoma and full-length FOXP1 exert similar oncogenic and transcriptional activity in human B cells

The forkhead transcription factor FOXP1 is generally regarded as an oncogene in activated B cell-like diffuse large B-cell lymphoma. Previous studies have suggested that a small isoform of FOXP1 rather than full-length FOXP1, may possess this oncogenic activity. Corroborating those studies, we herein show that activated B cell-like diffuse large B-cell lymphoma cell lines and primary activated B cell-like diffuse large B-cell lymphoma cells predominantly express a small FOXP1 isoform, and that the 5′-end of the Foxp1 gene is a common insertion site in murine lymphomas in leukemia virus- and transposon-mediated insertional mutagenesis screens. By combined mass spectrometry, (quantative) reverse transcription polymerase chain reaction/sequencing, and small interfering ribonucleic acid-mediated gene silencing, we determined that the small FOXP1 isoform predominantly expressed in activated B cell-like diffuse large B-cell lymphoma lacks the N-terminal 100 amino acids of full-length FOXP1. Aberrant overexpression of this FOXP1 isoform (ΔN100) in primary human B cells revealed its oncogenic capacity; it repressed apoptosis and plasma cell differentiation. However, no difference in potency was found between this small FOXP1 isoform and full-length FOXP1. Furthermore, overexpression of full-length FOXP1 or this small FOXP1 isoform in primary B cells and diffuse large B-cell lymphoma cell lines resulted in similar gene regulation. Taken together, our data indicate that this small FOXP1 isoform and full-length FOXP1 have comparable oncogenic and transcriptional activity in human B cells, suggesting that aberrant expression or overexpression of FOXP1, irrespective of the specific isoform, contributes to lymphomagenesis. These novel insights further enhance the value of FOXP1 for the diagnostics, prognostics, and treatment of diffuse large B-cell lymphoma patients.

Transformation of marginal zone lymphoma (and association with other lymphomas)

Marginal zone lymphomas (MZL) are a diverse group of indolent lymphoproliferative disorders that comprise three subtypes: nodal, splenic and mucosal associated marginal zone lymphomas (MALT). Histologic transformation (HT) to an aggressive lymphoma is a rare event that can occur in any subtype, and at lower frequency compared to other indolent non Hodgkin lymphomas (NHL) like follicular lymphoma. There are few data directly associated with risk and prognosis of transformation in MZL. However, recent advances in the understanding of molecular and genetic features of MALT have contributed to an evolving appreciation of HT in this disease. Optimal treatment of HT of MZL remains unknown. Much of the approach to managing transformed MZL is extrapolated from other indolent NHLs.

The significance of FOXP1 in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of mature B-cell lymphoma. While the majority of patients are cured with immunochemotherapy incorporating the anti-CD20 monoclonal antibody rituximab (R-CHOP), relapsed and refractory patients still have a dismal prognosis. DLBCL subtypes including an aggressive activated B-cell-like (ABC) and a more favorable prognosis germinal center-like (GCB) DLBCL have been identified by gene expression profiling and are characterized by distinct genetic abnormalities and oncogenic pathways. This identification of novel molecular targets is now enabling clinical trials to evaluate more effective personalized approaches to DLBCL therapy. The forkhead transcription factor FOXP1 is highly expressed in the ABC-DLBCL gene signature and has been extensively studied within the context of DLBCL for more than a decade. Here, we review the significance of FOXP1 in the pathogenesis of DLBCL, summarizing data supporting its utility as a prognostic and subtyping marker, its targeting by genetic aberrations, the importance of specific isoforms, and emerging data demonstrating a functional role in lymphoma biology. FOXP1 is one of the critical transcription factors whose deregulated expression makes important contributions to DLBCL pathogenesis. Thus, FOXP1 warrants further study as a potential theranostic in ABC-DLBCL.

The spectrum of MALT lymphoma at different sites: biological and therapeutic relevance

Extranodal marginal zone (MZ) B-cell lymphomas of the mucosa-associated lymphoid tissue (MALT) arise from lymphoid populations that are induced by chronic inflammation in extranodal sites. The best evidence of an etiopathogenetic link is provided by the association between Helicobacter pylori–positive gastritis and gastric MALT lymphoma. Indeed, successful eradication of this microorganism with antibiotics can be followed by gastric MALT lymphoma regression in most cases. Other microbial agents have been implicated in the pathogenesis of MZ lymphoma arising at different sites. Apart from gastric MALT lymphoma, antibiotic therapies have been adequately tested only in ocular adnexal MALT lymphomas where upfront doxycycline may be a reasonable and effective initial treatment of patients with Chlamydophila psittaci–positive lymphoma before considering more aggressive strategies. In all other instances, antibiotic treatment of nongastric lymphomas remains investigational. Indeed, there is no clear consensus for the treatment of patients with gastric MALT lymphoma requiring further treatment beyond H pylori eradication or with extensive disease. Both radiotherapy and systemic treatments with chemotherapy and anti-CD20 antibodies are efficacious and thus the experience of individual centers and each patient’s preferences in terms of adverse effects are important parameters in the decision process.

The hematopoietic oncoprotein FOXP1 promotes tumor cell survival in diffuse large B-cell lymphoma by repressing S1PR2 signaling

Aberrant expression of the oncogenic transcription factor forkhead box protein 1 (FOXP1) is a common feature of diffuse large B-cell lymphoma (DLBCL). We have combined chromatin immunoprecipitation and gene expression profiling after FOXP1 depletion with functional screening to identify targets of FOXP1 contributing to tumor cell survival. We find that the sphingosine-1-phosphate receptor 2 (S1PR2) is repressed by FOXP1 in activated B-cell (ABC) and germinal center B-cell (GCB) DLBCL cell lines with aberrantly high FOXP1 levels; S1PR2 expression is further inversely correlated with FOXP1 expression in 3 patient cohorts. Ectopic expression of wild-type S1PR2, but not a point mutant incapable of activating downstream signaling pathways, induces apoptosis in DLBCL cells and restricts tumor growth in subcutaneous and orthotopic models of the disease. The proapoptotic effects of S1PR2 are phenocopied by ectopic expression of the small G protein Gα13 but are independent of AKT signaling. We further show that low S1PR2 expression is a strong negative prognosticator of patient survival, alone and especially in combination with high FOXP1 expression. The S1PR2 locus has previously been demonstrated to be recurrently mutated in GCB DLBCL; the transcriptional silencing of S1PR2 by FOXP1 represents an alternative mechanism leading to inactivation of this important hematopoietic tumor suppressor.

Emerging role of infectious etiologies in the pathogenesis of marginal zone B-cell lymphomas

Extranodal marginal zone B-cell lymphomas of the mucosa-associated lymphoid tissue (MALT) arise from lymphoid populations that are induced by chronic inflammation in extranodal sites. The most frequently affected organ is the stomach, where MALT lymphoma is incontrovertibly associated with a chronic gastritis induced by a microbial pathogen, Helicobacter pylori. Gastric MALT lymphoma therefore represents a paradigm for evaluating inflammation-associated lymphomagenesis, which may lead to a deeper understanding of a possible etiologic association between other microorganisms and nongastric marginal zone lymphomas. Besides infectious etiology, chronic inflammation caused by autoimmune diseases, such as Sjögren syndrome or Hashimoto thyroiditis, can also carry a significant risk factor for the development of marginal zone lymphoma. In addition to the continuous antigenic drive, additional oncogenic events play a relevant role in lymphoma growth and progression to the point at which the lymphoproliferative process may eventually become independent of antigenic stimulation. Recent studies on MALT lymphomas have in fact demonstrated genetic alterations affecting the NF-κB) pathway, a major signaling pathway involved in many cancers. This review aims to present marginal zone lymphoma as an example of the close pathogenetic link between chronic inflammation and tumor development, with particular attention to the role of infectious agents and the integration of these observations into everyday clinical practice. See all articles in this CCR Focus section, "Paradigm Shifts in Lymphoma."

Immunohistochemical and molecular characteristics with prognostic significance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin lymphoma with marked biologic heterogeneity. We analyzed 100 cases of DLBCL to evaluate the prognostic value of immunohistochemical markers derived from the gene expression profiling-defined cell origin signature, including MYC, BCL2, BCL6, and FOXP1 protein expression. We also investigated genetic alterations in BCL2, BCL6, MYC and FOXP1 using fluorescence in situ hybridization and assessed their prognostic significance. BCL6 rearrangements were detected in 29% of cases, and BCL6 gene alteration (rearrangement and/or amplification) was associated with the non-germinal center B subtype (non-GCB). BCL2 translocation was associated with the GCB phenotype, and BCL2 protein expression was associated with the translocation and/or amplification of 18q21. MYC rearrangements were detected in 15% of cases, and MYC protein expression was observed in 29% of cases. FOXP1 expression, mainly of the non-GCB subtype, was demonstrated in 37% of cases. Co-expression of the MYC and BCL2 proteins, with non-GCB subtype predominance, was observed in 21% of cases. We detected an association between high FOXP1 expression and a high proliferation rate as well as a significant positive correlation between MYC overexpression and FOXP1 overexpression. MYC, BCL2 and FOXP1 expression were significant predictors of overall survival. The co-expression of MYC and BCL2 confers a poorer clinical outcome than MYC or BCL2 expression alone, whereas cases negative for both markers had the best outcomes. Our study confirms that DLBCL, characterized by the co-expression of MYC and BCL2 proteins, has a poor prognosis and establishes a significant positive correlation with MYC and FOXP1 over-expression in this entity.

Non-IG aberrations of FOXP1 in B-cell malignancies lead to an aberrant expression of N-truncated isoforms of FOXP1

The transcription factor FOXP1 is implicated in the pathogenesis of B-cell lymphomas through chromosomal translocations involving either immunoglobulin heavy chain (IGH) locus or non-IG sequences. The former translocation, t(3;14)(p13;q32), results in dysregulated expression of FOXP1 juxtaposed with strong regulatory elements of IGH. Thus far, molecular consequences of rare non-IG aberrations of FOXP1 remain undetermined. Here, using molecular cytogenetics and molecular biology studies, we comprehensively analyzed four lymphoma cases with non-IG rearrangements of FOXP1 and compared these with cases harboring t(3;14)(p13;q32)/IGH-FOXP1 and FOXP1-expressing lymphomas with no apparent structural aberrations of the gene. Our study revealed that non-IG rearrangements of FOXP1 are usually acquired during clinical course of various lymphoma subtypes, including diffuse large B cell lymphoma, marginal zone lymphoma and chronic lymphocytic leukemia, and correlate with a poor prognosis. Importantly, these aberrations constantly target the coding region of FOXP1, promiscuously fusing with coding and non-coding gene sequences at various reciprocal breakpoints (2q36, 10q24 and 3q11). The non-IG rearrangements of FOXP1, however, do not generate functional chimeric genes but commonly disrupt the full-length FOXP1 transcript leading to an aberrant expression of N-truncated FOXP1 isoforms (FOXP1(NT)), as shown by QRT-PCR and Western blot analysis. In contrast, t(3;14)(p13;q32)/IGH-FOXP1 affects the 5' untranslated region of FOXP1 and results in overexpress the full-length FOXP1 protein (FOXP1(FL)). RNA-sequencing of a few lymphoma cases expressing FOXP1(NT) and FOXP1(FL) detected neither FOXP1-related fusions nor FOXP1 mutations. Further bioinformatic analysis of RNA-sequencing data retrieved a set of genes, which may comprise direct or non-direct targets of FOXP1(NT), potentially implicated in disease progression. In summary, our findings point to a dual mechanism through which FOXP1 is implicated in B-cell lymphomagenesis. We hypothesize that the primary t(3;14)(p13;q32)/IGH-FOXP1 activates expression of the FOXP1(FL) protein with potent oncogenic activity, whereas the secondary non-IG rearrangements of FOXP1 promote expression of the FOXP1(NT) proteins, likely driving progression of disease.

Reciprocal expression of the endocytic protein HIP1R and its repressor FOXP1 predicts outcome in R-CHOP-treated diffuse large B-cell lymphoma patients

We previously identified autoantibodies to the endocytic-associated protein Huntingtin-interacting protein 1-related (HIP1R) in diffuse large B-cell lymphoma (DLBCL) patients. HIP1R regulates internalization of cell surface receptors via endocytosis, a process relevant to many therapeutic strategies including CD20 targeting with rituximab. In this study, we characterized HIP1R expression patterns, investigated a mechanism of transcriptional regulation and its clinical relevance in DLBCL patients treated with immunochemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone, R-CHOP). HIP1R was preferentially expressed in germinal center B-cell-like DLBCL (P<0.0001) and inversely correlated with the activated B-cell-like DLBCL (ABC-DLBCL) associated transcription factor, Forkhead box P1 (FOXP1). HIP1R was confirmed as a direct FOXP1 target gene in ABC-DLBCL by FOXP1-targeted silencing and chromatin immunoprecipitation. Lower HIP1R protein expression (≤ 10% tumoral positivity) significantly correlated with inferior overall survival (OS, P=0.0003) and progression-free survival (PFS, P=0.0148) in R-CHOP-treated DLBCL patients (n=157). Reciprocal expression with ≥ 70% FOXP1 positivity defined FOXP1(hi)/HIP1R(lo) patients with particularly poor outcome (OS, P=0.0001; PFS, P=0.0016). In an independent R-CHOP-treated DLBCL (n=233) microarray data set, patients with transcript expression in lower quartile HIP1R and FOXP1(hi)/HIP1R(lo) subgroups exhibited worse OS, P=0.0044 and P=0.0004, respectively. HIP1R repression by FOXP1 is strongly associated with poor outcome, thus further understanding of FOXP1-HIP1R and/or endocytic signaling pathways might give rise to novel therapeutic options for DLBCL.

The molecular biology of diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) represents the most common type of malignant lymphoma. In the last few years, significant progress has been achieved in the understanding of the molecular pathogenesis of this entity. Gene expression profiling has identified three molecular DLBCL subtypes, termed germinal-center B-cell-like (GCB) DLBCL, activated B-cell-like (ABC) DLBCL, and primary mediastinal B-cell lymphoma (PMBL). In this review, we summarize our current understanding of the biology of these DLBCL subtypes with a special emphasis on novel diagnostic and therapeutic approaches.

Helicobacter pylori infection, chronic inflammation, and genomic transformations in gastric MALT lymphoma

Nowadays, it is believed that the main role in the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma plays Helicobacter pylori infection. This world-wide distributed bacteria is in charge of most cases of not only upper gastrointestinal tract disorders but also some of extragastric problems. Constant stimulation of the immune system causes a B-lymphocytes proliferation, which is considered to be responsible for the neoplastic transformation. On the other hand, there are 10%–20% of patients who do not respond to Helicobacter pylori eradication treatment. This group has often a chromosome translocation, which suggests that there is another unknown, so far, pathogenetic mechanism of MALT lymphoma. Majority of genetic abnormalities are connected with nuclear factor-κB (NF-κB) pathway, which activates the uncontrolled proliferation of neoplastic cells. Translocations already described in studies are t(11;18)(q21;q21), which is the most common, t(14;18)(q32;q21), t(14;18)(q32;q21), and t(3;14)(p14.1;q32). This non-Hodgkin's lymphoma is an indolent type originated outside lymph nodes. In more than 50% of cases, it occurs in the stomach. Occasionally, it can be found in salivary and thyroid gland, lung, breast, bladder, skin, or any other place in the human body. This paper is a review of the current knowledge on etiology, pathogenesis, treatment, and follow-up of gastric MALT lymphoma.

Chlamydia psittaci in ocular adnexa MALT lymphoma: a possible role in lymphomagenesis and a different geographical distribution

Ocular adnexa MALT-lymphomas represent approximatively 5-15% of all extranodal lymphomas. Almost 75% of OAMLs are localized in orbital fat, while 25% of cases involves conjunctive. MALT-lymphomas often recognize specific environmental factors responsible of lymphoma development and progression. In particular as Helicobacter pylori in gastric MALT lymphomas, other bacterial infections have been recognized related to MALT lymphomas in specific site. Recently Chlamydia psittaci has been identified in Ocular Adnexa MALT lymphomas, with variable frequence dependently from geographic areas. Thus bacterial infection is responsible of clonal selection on induced MALT with subsequent lymphoma development. Moreover Chlamydia psittaci could promote chromosomal aberration either through genetic instability as a consequence of induced proliferation and probably through DNA oxidative damage. The most common translocation described in MALT lymphomas affects NF-kB pathway with a substantial antiapoptotic effect. Several therapeutic approaches are now available, but the use of antibiotic-therapy in specific cases, although with conflicting results, could improve the treatment of ocular adnexa MALT lymphomas. In this review we analyse the most relevant features of Ocular adnexa MALT lymphomas, underlining specific biological characteristics mainly related to the potential role of Chlamydia psittaci in lymphomagenesis.

Pathogenesis of human B cell lymphomas

The mechanisms that drive normal B cell differentiation and activation are frequently subverted by B cell lymphomas for their unlimited growth and survival. B cells are particularly prone to malignant transformation because the machinery used for antibody diversification can cause chromosomal translocations and oncogenic mutations. The advent of functional and structural genomics has greatly accelerated our understanding of oncogenic mechanisms in lymphomagenesis. The signaling pathways that normal B cells utilize to sense antigens are frequently derailed in B cell malignancies, leading to constitutive activation of prosurvival pathways. These malignancies co-opt transcriptional regulatory systems that characterize their normal B cell counterparts and frequently alter epigenetic regulators of chromatin structure and gene expression. These mechanistic insights are ushering in an era of targeted therapies for these cancers based on the principles of pathogenesis.

Myc-mediated repression of microRNA-34a promotes high-grade transformation of B-cell lymphoma by dysregulation of FoxP1

Gastric marginal zone B-cell lymphoma of MALT type (MALT lymphoma) arises in the context of chronic inflammation induced by the bacterial pathogen Helicobacter pylori. Although generally considered an indolent disease, MALT lymphoma may transform to gastric diffuse large B-cell lymphoma (gDLBCL) through mechanisms that remain poorly understood. By comparing microRNA expression profiles of gastric MALT lymphoma and gDLBCL, we have identified a signature of 27 deregulated microRNAs(miRNAs) that share the characteristic of being transcriptionally repressed by Myc. Myc overexpression was consequently detected in 80% of gDLBCL but only 20% of MALT lymphomas spotted on a tissue microarray. A highly similar signature of Myc-repressed miRNAs was further detected in nodal DLBCL. Small interfering RNA-mediated knock-down of Myc blocked proliferation of DLBCL cell lines. Of the Myc-repressed miRNAs down-regulated in malignant lymphoma, miR-34a showed the strongest antiproliferative properties when overexpressed in DLBCL cells. We could further attribute miR-34a's tumor-suppressive effects to deregulation of its target FoxP1. FoxP1 overexpression was detected in gDLBCL but not in gastric MALT lymphoma; FoxP1 knock-down efficiently blocked DLBCL proliferation. In conclusion, our results elucidate a novel Myc- and FoxP1-dependent pathway of malignant transformation and suggest miR-34a replacement therapy as a promising strategy in lymphoma treatment.

Multiple faces of FoxM1 transcription factor: lessons from transgenic mouse models

FoxM1 transcription factor (previously called HFH-11B, Trident, FoxM1b, Win, and MPP2) is expressed in actively dividing cells and critical for cell cycle progression. FoxM1 expression is induced in a variety of tissues during embryogenesis, and Foxm1 (-/-) mice exhibit embryonic lethal phenotype due to multiple abnormalities in the liver, heart, lung and blood vessels. FoxM1 levels are dramatically decreased in adult tissues, but FoxM1 expression is re-activated during organ injury and numerous cancers. In this review, we discussed the role of FoxM1 in different cell lineages using recent data from transgenic mouse models with conditional "gain-of-function" and "loss-of-function" of FoxM1, as well as tissue samples from human patients. In addition, we provided experimental data showing additional sites of FoxM1 expression in the mouse embryo. Novel cell-autonomous roles of FoxM1 in embryonic development, organ injury and cancer formation in vivo were analyzed. Potential application of these findings for the diagnosis and treatment of human diseases were discussed.

BCL6 gene rearrangement and protein expression are associated with large cell presentation of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is an indolent B-cell lymphoma, which is often localized in the stomach. It is characterized by typical morphology, immunology, cytogenetics and expression profile. The coexistence of a large B-cell lymphoma and a MALT lymphoma in the gastrointestinal tract is defined as a composite lymphoma (ComL) and, as we have previously shown, is almost always the consequence of secondary transformation of MALT lymphoma. Here, we have analyzed a panel of seven MALT lymphomas, seven ComL and thirteen large cell variants of marginal zone B-cell lymphomas (MZBL) using FISH for the detection of rearrangements of IGH, MALT1, BCL6, BCL10 and FOXP1 and immunohistochemistry for Bcl6, Bcl10 and FoxP1. Translocations involving IGH were found in 10/27 lymphomas including two cases with IGH-BCL6 fusion and one with IGH-BCL10 fusion; in 7/10 cases, the translocation partner was not identified. Bcl10 and FoxP1 protein expression was heterogeneous throughout the series. Genetic rearrangements of BCL6 and Bcl6 protein expression were found almost exclusively in the large cell components of the ComL and the large cell extranodal MZBL (p = 0.2093 and p = 0.0261, respectively). These findings suggest Bcl6 as a marker for transformation of MALT lymphoma.

FOXP1 protein overexpression is associated with inferior outcome in nodal diffuse large B-cell lymphomas with non-germinal centre phenotype, independent of gains and structural aberrations at 3p14.1

AIMS

To determine the molecular epidemiology and prognostic importance of structural and numeric FOXP1 gene aberrations with respect to BCL-6 gene and to FOXP1 protein expression in 389 diffuse large B-cell lymphomas (DLBCL) from the pre-rituximab era on tissue microarrays.

METHODS AND RESULTS

By interphase fluorescence in situ hybridization with colour-labelled bacterial artificial chromosome clones, 12% (27/223) analysable cases showed FOXP1 gains and 1% (2/210) FOXP1 breaks. Seven percent of cases with known BCL-6 and FOXP1 gene status (n = 159) showed an isolated FOXP1 gain, 19% an isolated BCL-6 gain and 18% a trisomy 3. FOXP1 gains (isolated and due to trisomy 3) were more frequent in nodal than extranodal DLBCL and in non-germinal centre B-cell-like (non-GCB) DLBCL than in GCB DLBCL. By immunohistochemistry, FOXP1 protein was more often overexpressed in non-GCB than in GCB cases. FOXP1 overexpression was associated with poor disease-specific survival in all DLBCL, particularly in nodal and non-GCB cases. There was no correlation between FOXP1 gene aberrations and either FOXP1 protein expression or survival.

CONCLUSIONS

FOXP1 is recurrently targeted by numeric, and rarely by structural, genetic aberrations in DLBCL. Only the presence of FOXP1 protein, irrespective of its gene status, is decisive for prognosis in DLBCL.

FOXP1 and BCL2 show similar immunoenzymatic pattern in bone marrow trephines of chronic lymphocytic leukemia patients

Indolent B lymphoproliferative disorder, chronic lymphocytic leukemia (CLL) represents one of the most common hematologic diseases in the Western world. Although there are many disease development markers known so far, for example, B-cell lymphoma/leukemia (BCL) 2, new ones are needed for better understanding course of the disease. FOXP1 is known to be strongly expressed after B-cell activation. Its essential role in B-cell development suggested that it could also have a role in a various tumor B-cells. We have analyzed 74 bone marrow samples from B-CLL patients for presence of FOXP1 and its gene aberrations in tumor cells. Our results showed presence of FOXP1 protein mostly in the same tumor cells as BCL2 protein, and their specific immunostaining pattern. Diffuse immunostaining pattern of both proteins is present in patients with higher clinical stages of B-CLL and with some other markers that indicate worse outcome of the disease. Thus, FOXP1 and/or BCL2 immunostaining of bone marrow trephine sections could serve as an immunohistochemical marker in B-CLL.

Gastric MALT lymphoma: a model of chronic inflammation-induced tumor development

Mucosa-associated lymphoid tissue (MALT) lymphoma, or extranodal marginal zone lymphoma of MALT, is an indolent B-cell non-Hodgkin lymphoma arising in lymphoid infiltrates that are induced by chronic inflammation in extranodal sites. The stomach is the most commonly affected organ, in which MALT lymphoma pathogenesis is clearly associated with Helicobacter pylori gastroduodenitis. Gastric MALT lymphoma has attracted attention because of the involvement of genetic aberrations in the nuclear factor kappaB (NFkappaB) pathway, one of the most investigated pathways in the fields of immunology and oncology. This Review presents gastric MALT lymphoma as an outstanding example of the close pathogenetic link between chronic inflammation and tumor development, and describes how this information can be integrated into daily clinical practice. Gastric MALT lymphoma is considered one of the best models of how genetic events lead to oncogenesis, determine tumor biology, dictate clinical behavior and represent viable therapeutic targets. Moreover, in view of the association of gastric MALT lymphoma with dysregulation of the NFkappaB pathway, this signaling pathway will be discussed in depth in both normal and pathological conditions, highlighting strategies to identify new therapeutic targets in this lymphoma.

Chronic inflammatory disease, lymphoid tissue neogenesis and extranodal marginal zone B-cell lymphomas

Chronic autoimmune or pathogen-induced immune reactions resulting in lymphoid neogenesis are associated with development of malignant lymphomas, mostly extranodal marginal zone B-cell lymphomas (MZBCLs). In this review we address (i) chemokines and adhesion molecules involved in lymphoid neogenesis; (ii) the autoimmune diseases and pathogens which are associated with development of B-cell lymphomas; (iii) the molecular mechanisms involved in the initiation and progression of MZBCL; and (iv) 'potential' mouse models for MZBCL.

FOXP1 expression in monoclonal gammopathy of undetermined significance and multiple myeloma

Multiple myeloma (MM) is a clonal disorder of terminally differentiated B cells. In some cases the premalignant state is monoclonal gammopathy of undetermined significance (MGUS). Neoplastic plasma cells in both entities carry multiple and complex chromosomal abnormalities that make understanding of the disease development difficult. New insight into malignant mechanisms that underlie multiple myeloma may come from forkhead box P1 transcription factor (FOXP1) analysis in neoplastic plasma cells. FOXP1 is known to be important for B-cell maturation and differentiation and could play a significant role in plasma cell tumors. The purpose of the present study was therefore to analyze FOXP1 protein presence and FOXP1 gene abnormalities in 13 cases of MGUS and 60 cases of MM. It was found that FOXP1 protein was expressed in neoplastic plasma cells, unlike in their normal counterparts, and that additional FOXP1 gene copies could be found in both MGUS and MM. Based on FOXP1 presence in MM and its role in diffuse large B-cell lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, FOXP1 might play an important role in plasma cell neoplasm.

A20 deletion is associated with copy number gain at the TNFA/B/C locus and occurs preferentially in translocation-negative MALT lymphoma of the ocular adnexa and salivary glands

The genetic basis of MALT lymphoma is largely unknown. Characteristic chromosomal translocations are frequently associated with gastric and pulmonary cases, but are rare at other sites. We compared the genetic profiles of 33 ocular adnexal and 25 pulmonary MALT lymphomas by 1 Mb array-comparative genomic hybridization (CGH) and revealed recurrent 6q23 losses and 6p21.2-6p22.1 gains exclusive to ocular cases. High-resolution chromosome 6 tile-path array-CGH identified NF-kappaB inhibitor A20 as the target of 6q23.3 deletion and TNFA/B/C locus as a putative target of 6p21.2-22.1 gain. Interphase fluorescence in situ hybridization showed that A20 deletion occurred in MALT lymphoma of the ocular adnexa (8/42=19%), salivary gland (2/24=8%), thyroid (1/9=11%) and liver (1/2), but not in the lung (26), stomach (45) and skin (13). Homozygous deletion was observed in three cases. A20 deletion and TNFA/B/C gain were significantly associated (p<0.001) and exclusively found in cases without characteristic translocation. In ocular cases, A20 deletion was associated with concurrent involvement of different adnexal tissues or extraocular sites at diagnosis (p=0.007), a higher proportion of relapse (67% versus 37%) and a shorter relapse-free survival (p=0.033). A20 deletion and gain at TNFA/B/C locus may thus play an important role in the development of translocation-negative MALT lymphoma.

Prognostic markers and gene abnormalities in subgroups of diffuse large B-cell lymphoma: single center experience

AIM

To explore the association between FOXP1, BCL2, and BCL6 gene expression in diffuse large B-cell lymphoma tumor cells and their association with the presence of FOXP3 lymphocytes.

METHODS

Samples of lymph nodes from 53 patients with newly diagnosed diffuse large B-cell lymphoma were taken at the time of the diagnosis and immunostained for CD10, MUM1, BCL6, BCL2, FOXP1, and FOXP3. Fluorescent in situ hybridization analysis was used for the detection of FOXP1, BCL2, and BCL6 gene abnormalities. The chi(2) test was used for data analysis.

RESULTS

FOXP1 protein was detected in 28 cases, genetic abnormalities involving the FOXP1 locus were found in 19 cases, and both were present in 13 cases (chi(2)=7.157; P=0.028). FOXP3 positive cells were detected in 37 cases. There was a significant relationship between BCL2 expression and FOXP1 genetic abnormalities (chi(2)= 5.858; P=0.016) and between BCL2 expression and BCL2 genetic abnormalities (chi(2)= 6.349; P=0.012). There was also an association between BCL6 and FOXP1 genetic abnormalities (chi(2)=8.497;P=0.004).

CONCLUSION

There was an association between FOXP1 and BCL2. The presence of FOXP3 positive cells had no influence on any of the analyzed markers.

Molecular subtypes of diffuse large B-cell lymphoma arise by distinct genetic pathways

Gene-expression profiling has been used to define 3 molecular subtypes of diffuse large B-cell lymphoma (DLBCL), termed germinal center B-cell-like (GCB) DLBCL, activated B-cell-like (ABC) DLBCL, and primary mediastinal B-cell lymphoma (PMBL). To investigate whether these DLBCL subtypes arise by distinct pathogenetic mechanisms, we analyzed 203 DLBCL biopsy samples by high-resolution, genome-wide copy number analysis coupled with gene-expression profiling. Of 272 recurrent chromosomal aberrations that were associated with gene-expression alterations, 30 were used differentially by the DLBCL subtypes (P < 0.006). An amplicon on chromosome 19 was detected in 26% of ABC DLBCLs but in only 3% of GCB DLBCLs and PMBLs. A highly up-regulated gene in this amplicon was SPIB, which encodes an ETS family transcription factor. Knockdown of SPIB by RNA interference was toxic to ABC DLBCL cell lines but not to GCB DLBCL, PMBL, or myeloma cell lines, strongly implicating SPIB as an oncogene involved in the pathogenesis of ABC DLBCL. Deletion of the INK4a/ARF tumor suppressor locus and trisomy 3 also occurred almost exclusively in ABC DLBCLs and was associated with inferior outcome within this subtype. FOXP1 emerged as a potential oncogene in ABC DLBCL that was up-regulated by trisomy 3 and by more focal high-level amplifications. In GCB DLBCL, amplification of the oncogenic mir-17-92 microRNA cluster and deletion of the tumor suppressor PTEN were recurrent, but these events did not occur in ABC DLBCL. Together, these data provide genetic evidence that the DLBCL subtypes are distinct diseases that use different oncogenic pathways.

Coordinated actions of the forkhead protein Foxp1 and Hox proteins in the columnar organization of spinal motor neurons

The formation of locomotor circuits depends on the spatially organized generation of motor columns that innervate distinct muscle and autonomic nervous system targets along the body axis. Within each spinal segment, multiple motor neuron classes arise from a common progenitor population; however, the mechanisms underlying their diversification remain poorly understood. Here, we show that the Forkhead domain transcription factor Foxp1 plays a critical role in defining the columnar identity of motor neurons at each axial position. Using genetic manipulations, we demonstrate that Foxp1 establishes the pattern of LIM-HD protein expression and accordingly organizes motor axon projections, their connectivity with peripheral targets, and the establishment of motor pools. These functions of Foxp1 act in accordance with the rostrocaudal pattern provided by Hox proteins along the length of the spinal cord, suggesting a model by which motor neuron diversity is achieved through the coordinated actions of Foxp1 and Hox proteins.

FOXP1 abnormalities in lymphoma: translocation breakpoint mapping reveals insights into deregulated transcriptional control

Deregulation of FOXP1 expression plays an important role in lymphoma development although the underlying molecular mechanism is poorly understood. FOXP1 is targeted by chromosome translocations in MALT lymphoma and diffuse large B-cell lymphoma, where high-level protein expression is associated with poor prognosis. Nonetheless, the incidence and nature of FOXP1 abnormalities at both the genetic and protein levels, and their correlation in these lymphomas are not well established. We investigated FOXP1 translocation, copy number change and protein expression in MALT lymphoma (n=321), MALT lymphoma with a diffuse large B-cell lymphoma component (59), nodal diffuse large B-cell lymphoma (64) and extranodal diffuse large B-cell lymphoma (151) by interphase fluorescence in situ hybridization and immunohistochemistry. FOXP1 translocation was found in eight MALT lymphomas and three MALT lymphomas with diffuse large B-cell lymphoma, with all positive cases originating in the stomach. In diffuse large B-cell lymphoma, the translocation was seen in 5 cases originating in the stomach (2), tonsil (1), large intestine (1) and lymph node (1). Immunoglobulin heavy chain gene was the translocation partner in 11 of the 16 positive cases. Fluorescence in situ hybridization mapping revealed FOXP1 breakpoints within the 5' untranslated region of the gene (upstream of exon 6, the first coding exon of full-length FOXP1) in 14 cases, but downstream of exon 6 (most likely upstream of exon 8) in the remaining 2 cases. Three copies of the FOXP1 gene were observed in MALT lymphoma (17%), MALT lymphoma with diffuse large B-cell lymphoma (12%) and diffuse large B-cell lymphoma (32%), including cases with FOXP1 translocation (19%). Immunohistochemistry showed strong/moderate FOXP1 staining in all the cases with FOXP1 translocation. However, FOXP1 expression was independent of FOXP1 translocation or copy number changes. Our findings suggest that (1) FOXP1 translocation may disrupt the full-length FOXP1 transcript and lead to expression of FOXP1 transcript variants with alternate 5' ends and (2) mechanisms other than translocation and copy number changes are also responsible for FOXP1 overexpression in lymphoma.

MALT lymphoma : recent advances in aetiology and molecular genetics

Mucosa-associated lymphoid tissue (MALT) lymphoma is a common low grade B-cell lymphoma arising from a background of chronic inflammatory disease at a number of mucosal sites. Those originating in the stomach are causatively linked to Helicobacter pylori infection and eradication of the bacterium with antibiotics leads to long-term complete regression of the lymphoma in aproximately 70% of cases. Now, there is further evidence of linking Campylobacter jejuni, Borrelia burgdorferi and Chlamydia psittaci infection with immunoproliferative small intestine disease, MALT lymphoma of the skin and ocular adnexa respectively. t(11;18)/API2-MALT1, t(1;14)/IGH-BCL10, t(14;18)/IGH-MALT1 and t(3;14)/IGH-FOXP1 occur at considerably variable incidences in MALT lymphomas of different sites. The first three chromosome translocations are specifically associated with the MALT lymphoma entity and the oncogenic products of these translocations have been shown to target a common molecular pathway, i.e. the nuclear factor-kappaB pathway. Here, I review the recent advances in our understanding of the association of microbial pathogens with MALT lymphoma of various sites and the molecular genetics underlying the lymphoma development.

Potentially oncogenic B-cell activation-induced smaller isoforms of FOXP1 are highly expressed in the activated B cell-like subtype of DLBCL

The FOXP1 forkhead transcription factor is targeted by recurrent chromosome translocations in several subtypes of B-cell non-Hodgkin lymphomas, where high-level FOXP1 protein expression has been linked to a poor prognosis. Western blotting studies of diffuse large B-cell lymphoma (DLBCL) cell lines unexpectedly identified the atypical high-level expression of 2 smaller, 60 to 65 kDa, FOXP1 isoforms in all 5 of those with the activated B cell (ABC)-like DLBCL subtype and in a subgroup of primary DLBCL. The anti-FOXP1 (JC12) monoclonal antibody cannot distinguish FOXP1 isoforms by immunohistochemistry, a finding that may be clinically relevant as high-level expression of the full-length FOXP1 protein was observed in some germinal center-derived DLBCLs. ABC-like DLBCL-derived cell lines were observed to express 2 novel, alternatively spliced FOXP1 mRNA isoforms, encoding N-terminally truncated proteins. These transcripts and the smaller protein isoforms were induced as a consequence of normal B-cell activation, which thus represents an additional mechanism for up-regulating FOXP1 expression in lymphomas. The expression of potentially oncogenic smaller FOXP1 isoforms may resolve the previously contradictory findings that FOXP1 represents a favorable prognostic marker in breast cancer and an adverse risk factor in B-cell lymphomas.

Ocular adnexal MALT lymphoma: an intriguing model for antigen-driven lymphomagenesis and microbial-targeted therapy

Non-Hodgkin's lymphomas constitute one half of malignancies arising in the orbit and the ocular adnexae. Mucosa-associated lymphoid tissue (MALT)-type lymphoma is the most common histological category in this anatomic region. The incidence of ocular adnexal lymphoma of mucosa-associated lymphoid tissue-type (OAML) is increasing and recent studies offered new relevant insights in molecular, pathogenetic and therapeutic issues on these neoplasms. A pathogenetic model of antigen-driven lymphoproliferation similar to that reported for Helicobacter pylori-related gastric MALT lymphomas has been hypothesized for OAML. This notion is supported by the association between OAML and Chlamydophila psittaci infection, an association that is of likely pathogenetic relevance and may influence both the biological behavior and the therapeutic management of these neoplasms. However, this association displays evident geographical variability indicating that other etiopathogenic agents could be involved. These recent acquisitions coupled with the occurrence of chromosomal translocations and other genetic alterations, as well as additional risk factors like autoimmune disorders have contributed to render OAML an exciting challenge for a broad group of physicians and scientists. OAML is an indolent and rarely lethal malignancy that, in selected patients, can be managed with observation alone. Lymphomatous lesions are frequently responsible for symptoms affecting patient's quality of life, requiring, therefore, immediate treatment. Several therapeutic strategies are available, often associated with relevant side-effects. However, the therapeutic choice in OAML is not supported by consolidated evidence due to the lack of prospective trials. In this review, we analyze the most relevant biological, molecular, pathological and clinical features of OAML and propose some therapeutic guidelines for patients affected by this malignancy.

The emerging roles of forkhead box (Fox) proteins in cancer

Forkhead box (Fox) proteins are a superfamily of evolutionarily conserved transcriptional regulators, which control a wide spectrum of biological processes. As a consequence, a loss or gain of Fox function can alter cell fate and promote tumorigenesis as well as cancer progression. Here we discuss the evidence that the deregulation of Fox family transcription factors has a crucial role in the development and progression of cancer, and evaluate the emerging role of Fox proteins as direct and indirect targets for therapeutic intervention, as well as biomarkers for predicting and monitoring treatment responses.

[Extranodal diffuse large B-cell lymphoma--an organotypic disease?]

Roughly 30-40% of diffuse large B-cell lymphomas (DLBCL) arise primarily in extranodal sites. Most frequently, they occur in the gastrointestinal tract, especially in the gastric mucosa. They also occur in the central nervous system, as testicular lymphomas, in the lungs, or in the skin. Morphologically, they show the whole spectrum of peripheral B-blasts: centroblasts, immunoblasts, or plasmoblasts. Thus, there is no actual difference in their cytomorphological presentation compared to their nodal-and frequently systemic-counterparts. However, recent data point to profound differences in primary extranodal DLBCL compared to primary nodal tumors, as well as to each other, frequently relating to their molecular characteristics and especially implying organotypic features. These characteristics may relate to a particular organotypic site of origin, or the particular clinico-pathogenetic setting in which the tumors arise. This is exemplified in the description of the DLBCL subtypes as defined by the World Health Organization classification (mediastinal or intravascular B-cell lymphoma; primary effusion lymphoma). On the other hand, primary extranodal DLBCL are frequently characterized by a particular (cyto-)genetic constitution, often related to their site of origin. Finally, some preliminary data on gene expression profiling strongly argue in favor of particular gene signatures for primary extranodal DLBCL, and hence in favor of particular organotypic transformation pathways.

[Extranodal marginal zone B-cell lymphoma of MALT-type]

Extranodal marginal zone B-cell lymphomas of the MALT type constitute, with around 8% of all B-cell lymphomas, the third most frequent lymphoma in the Western hemisphere. Their unifying characteristic principle is their origin in organs that are typically devoid of a regular lymphatic parenchyma ("primary" MALT). In contrast, "secondary" MALT is acquired in these sites by chronic inflammatory processes triggered by chronic infections or autoimmune diseases. The organotypic characteristics of these particular lymphoid tumours are also mirrored by organ-specific precursor lesions and in tumour biology. Usually, MALT-type lymphomas remain confined to their site of origin for a long time, disseminating only late during the course of the disease. Hence, they may be controlled by local treatment (excision, irradiation). Moreover, the distinctive genetic constitution of MALT-type lymphomas, although varying from organ to organ, indicates particular transformation pathways obviously related to the specific precursor lesion and, hence, of organ-specific quality.

FOXP1: a potential therapeutic target in cancer

Forkhead Box P1 (FOXP1) is a member of the FOX family of transcription factors which have a broad range of functions. Foxp1 is widely expressed and has been shown to have a role in cardiac, lung and lymphocyte development. FOXP1 is targeted by recurrent chromosome translocations and its overexpression confers a poor prognosis in a number of types of lymphomas, suggesting it may function as an oncogene. In contrast, FOXP1 localises to a tumour suppressor locus at 3p14.1 and loss of FOXP1 expression in breast cancer is associated with a worse outcome, suggesting FOXP1 may function as a tumour suppressor in other tissue types. These data suggest that FOXP1 may not only be useful in prognosis but also may be used to develop FOXP1-directed therapeutic strategies.

FOXP1: a potential therapeutic target in cancer

Forkhead Box P1 (FOXP1) is a member of the FOX family of transcription factors which have a broad range of functions. Foxp1 is widely expressed and has been shown to have a role in cardiac, lung and lymphocyte development. FOXP1 is targeted by recurrent chromosome translocations and its overexpression confers a poor prognosis in a number of types of lymphomas, suggesting it may function as an oncogene. In contrast, FOXP1 localises to a tumour suppressor locus at 3p14.1 and loss of FOXP1 expression in breast cancer is associated with a worse outcome, suggesting FOXP1 may function as a tumour suppressor in other tissue types. These data suggest that FOXP1 may not only be useful in prognosis but also may be used to develop FOXP1-directed therapeutic strategies.

Expression of the forkhead transcription factor FOXP1 is associated both with hypoxia inducible factors (HIFs) and the androgen receptor in prostate cancer but is not directly regulated by androgens or hypoxia

BACKGROUND

FOXP1 is a member of the winged helix or forkhead transcription factors. Recent studies have indicated possible roles for FOXP1 as a candidate tumor suppressor gene and a potential estrogen receptor (ER) co-regulator in the development of breast cancer. This study investigated whether FOXP1 has a similar relationship to the androgen receptor (AR) in prostate cancer and how these factors relate to the presence of hypoxia.

METHODS

FOXP1, the AR and various hypoxia-regulated proteins (HIF-1alpha, HIF-2alpha, and VEGF) were measured with immunohistochemistry using a tissue microarray constructed from 167 archival radical prostatectomies. Statistical analyses compared the co-expression of these factors both with each other and conventional parameters including patient age, pre-operative prostate specific antigen (PSA), post-operative Gleason score, capsular invasion, surgical margin status, tumor volume, and PSA recurrence. The influence of hypoxia, dihydrotestosterone, and the AR blocker Casodex was investigated in prostate cell lines VCaP and LNCaP in vitro.

RESULTS

Expression of nuclear FOXP1 was significantly positively correlated with AR (P = 0.0001), hypoxia inducible factor 1alpha (HIF-1alpha) (P = 0.01), HIF-2alpha (P = 0.0001), and vascular endothelial growth factor (VEGF) (P = 0.007) expression. A positive significant relationship was also identified with the post-operative Gleason score (P = 0.03) but not with the other variables, including PSA recurrence (P > 0.05). There was no significant change in expression in FOXP1 protein levels under conditions of hypoxia (0.1%), dihydrotestosterone stimulation (10 or 100 nM), or androgen blockade with Casodex (1, 10, or 50 microM).

CONCLUSION

These findings suggest that there may be a hormonal and hypoxia independent regulatory mechanism coordinating the expression of HIFs, the AR, and FOXP1 in prostate tumors.