Albert Gutierrez

LEF-1 is a prosurvival factor in chronic lymphocytic leukemia and is expressed in the preleukemic state of monoclonal B-cell lymphocytosis

The canonical Wnt signaling pathway is pathogenic in a variety of cancers. We previously identified aberrant expression of the Wnt pathway transcription factor and target gene lymphoid enhancer binding factor-1 (LEF1) in chronic lymphocytic leukemia (CLL). This suggested that the Wnt signaling pathway has a role in the biology of CLL. In this study, we performed a Wnt pathway analysis using gene expression profiling and identified aberrant regulation of Wnt pathway target genes, ligands, and signaling members in CLL cells. Furthermore, we identified aberrant protein expression of LEF-1 specifically in CLL but not in normal mature B-cell subsets or after B-cell activation. Using the T cell-specific transcription factor/LEF (TCF/LEF) dual luciferase reporter assay, we demonstrated constitutive Wnt pathway activation in CLL, although the pathway was inactive in normal peripheral B cells. Importantly, LEF-1 knockdown decreased CLL B-cell survival. We also identified LEF-1 expression in CD19(+)/CD5(+) cells obtained from patients with monoclonal B-cell lymphocytosis, suggesting a role for LEF-1 early in CLL leukemogenesis. This study has identified the constitutive activation and prosurvival function of LEF-1 and the Wnt pathway in CLL and uncovered a possible role for these factors in the preleukemic state of monoclonal B-cell lymphocytosis.

Calcinosis cutis in autoimmune connective tissue diseases

Calcinosis cutis is a chronic condition involving insoluble calcified deposits of the skin and subcutaneous tissue. It is commonly associated with autoimmune connective tissue diseases and can be a source of pain and functional disability. The likelihood of developing calcinosis varies among the autoimmune connective tissue diseases, with systemic sclerosis and dermatomyositis being the most commonly associated. Identification of therapy for this challenging disorder has been hampered by a paucity of large controlled trials. Although there is no uniformly effective treatment for calcinosis cutis, several surgical and medical therapies have demonstrated varying degrees of benefit in the treatment of calcinosis, including surgical excision, laser therapy, extracorporeal shock wave lithotripsy, diltiazem, minocycline, colchicine, and topical sodium thiosulfate, along with others. Recommendations for the diagnosis and therapy of calcinosis cutis in patients with autoimmune connective tissue diseases are discussed.

Tyrosines in the MUC1 cytoplasmic tail modulate transcription via the extracellular signal-regulated kinase 1/2 and nuclear factor-κB pathways

Much of the ability of the MUC1 oncoprotein to foster tumorigenesis and tumor progression likely originates from the interaction of its cytoplasmic tail with proteins involved in oncogenic signaling. Many of these interactions are regulated by phosphorylation, as the cytoplasmic tail contains seven highly conserved tyrosines and several serine/threonine phosphorylation sites. We have developed a cell line–based model system to study the effects of tyrosine phosphorylation on MUC1 signaling, with particular emphasis on its effects on gene transcription. COS-7 cells, which lack endogenous MUC1, were stably infected with wild-type MUC1 or a MUC1 construct lacking all seven tyrosines (MUC1 Y0) and analyzed for effects on transcription mediated by the extracellular signal-regulated kinase 1/2 (ERK1/2) and nuclear factor-κB (NF-κB) pathways. COS.MUC1 Y0 cells showed heightened active ERK1/2 with increased activator protein-1 (AP-1) and signal transducer and activator of transcription 3 (STAT3) transcriptional activity; there was also a simultaneous decrease in NF-κB transcriptional activity and nuclear localization. These changes altered the phenotype of COS.MUC1 Y0 cells, as this line displayed increased invasion and enhanced [3H]thymidine incorporation. Analysis of the three lines also showed significant differences in their cell cycle profile and bromodeoxyuridine incorporation when the cells were serum starved. These data support the growing evidence that MUC1 is involved in transcriptional regulation and link MUC1 for the first time to the NF-κB pathway. (Mol Cancer Res 2006;4(7):489–97)

Differentiation of Chronic Lymphocytic Leukemia B Cells into Immunoglobulin Secreting Cells Decreases LEF-1 Expression

Lymphocyte enhancer binding factor 1 (LEF-1) plays a crucial role in B lineage development and is only expressed in B cell precursors as B cell differentiation into mature B and plasma cells silences its expression. Chronic lymphocytic leukemia (CLL) cells aberrantly express LEF-1 and its expression is required for cellular survival. We hypothesized that modification of the differentiation status of CLL cells would result in loss of LEF-1 expression and eliminate the survival advantage provided by its aberrant expression. In this study, we first established a methodology that induces CLL cells to differentiate into immunoglobulin (Ig) secreting cells (ISC) using the TLR9 agonist, CpG, together with cytokines (CpG/c). CpG/c stimulation resulted in dramatic CLL cell phenotypic and morphologic changes, expression of cytoplasmic Ig, and secretion of light chain restricted Ig. CpG/c stimulation also resulted in decreased CLL cell LEF-1 expression and increased Blimp-1 expression, which is crucial for plasma cell differentiation. Further, Wnt pathway activation and cellular survival were impaired in differentiated CLL cells compared to undifferentiated CLL cells. These data support the notion that CLL can differentiate into ISC and that this triggers decreased leukemic cell survival secondary to the down regulation of LEF-1 and decreased Wnt pathway activation.

Selective Induction of DNA Repair Pathways in Human B Cells Activated by CD4+ T Cells

Greater than 75% of all hematologic malignancies derive from germinal center (GC) or post-GC B cells, suggesting that the GC reaction predisposes B cells to tumorigenesis. Because GC B cells acquire expression of the highly mutagenic enzyme activation-induced cytidine deaminase (AID), GC B cells may require additional DNA repair capacity. The goal of this study was to investigate whether normal human B cells acquire enhanced expression of DNA repair factors upon AID induction. We first demonstrated that several DNA mismatch repair, homologous recombination, base excision repair, and ATR signaling genes were overexpressed in GC B cells relative to naïve and memory B cells, reflecting activation of a process we have termed somatic hyperrepair (SHR). Using an in vitro system, we next characterized activation signals required to induce AID expression and SHR. Although AID expression was induced by a variety of polyclonal activators, SHR induction strictly required signals provided by contact with activated CD4+ T cells, and B cells activated in this manner displayed reduced levels of DNA damage-induced apoptosis. We further show the induction of SHR is independent of AID expression, as GC B cells from AID -/- mice retained heightened expression of SHR proteins. In consideration of the critical role that CD4+ T cells play in inducing the SHR process, our data suggest a novel role for CD4+ T cells in the tumor suppression of GC/post-GC B cells.

Subacute Cutaneous Lupus Erythematosus: Clinical Characteristics, Disease Associations, Treatments, and Outcomes in a Series of 90 Patients at Mayo Clinic, 1996-2011

Objective: To characterize the clinical presentation, laboratory studies, disease associations, and treatments of subacute cutaneous lupus erythematosus (SCLE). Patients and Methods: A retrospective review of 90 patients with SCLE at Mayo Clinic from January 1, 1996, through October 28, 2011, was performed. Results: The mean patient age at diagnosis was 61 years; 64 patients (71%) were women, and 11 cases (12%) were drug induced (1996–2000, no drug‐induced cases; 2001–2005, 2 cases; 2006–2011, 9 cases). Seventeen of 59 patients (29%) with available data were smokers at the time of diagnosis. The SCLE lesions were photodistributed in 75 patients (83%), and 52 (58%) had papulosquamous morphologic findings. Anti‐Ro/SS‐A positivity was present in 84 of 85 patients tested (99%), whereas 32 of the 85 patients (38%) tested positive for anti‐La/SS‐B. Associated autoimmune connective tissue diseases included Sjögren syndrome (n=13, 14%) and systemic lupus erythematosus (SLE) (n=8, 9%). Eighteen patients (20%) had at least 4 American College of Rheumatology criteria for SLE; 1 had lupus nephritis, and none had neurologic or notable hematologic sequelae. The most common therapy was hydroxychloroquine, with a complete response noted in 34 of 46 patients (74%) with available follow‐up data. Conclusion: Twenty‐eight percent of patients with SCLE (n=25) had an associated autoimmune connective tissue disease, although the severe sequelae of SLE, such as nephritis, were rare. The frequency of drug‐induced SCLE increased during the study. Most patients responded to treatment with hydroxychloroquine.

Diseases Caused by Genetic or Congenital Defects in the Immune System or Skin Immune System

Skin manifestations are common findings of hereditary autoinflammatory disorders (HAIDs) and primary immunodeficiency disorders (PIDDs). The skin functions as both a barrier to and entry point for infections playing a role in activation of an effective immune response. Disorders of the immune system have a profound effect on the skin and are often a heralding symptom of immune dysfunction. Recognition of these skin manifestations can be helpful in raising suspicion for HAID or PIDD and initiating appropriate therapy. These manifestations include, but are not limited to, cutaneous infection, erythroderma, eczema, granulomatous disorders, urticaria, autoimmune conditions, and changes to the pigment, hair, and nails. This chapter will summarize the extensive body of current knowledge that focuses on the clinical manifestations as well as the continually advancing genetic basis underlying these rare genetic disorders.