Interruption of p53-MDM2 Interaction by Nutlin-3a in Human Lymphoma Cell Models Initiates a Cell-Dependent Global Effect on Transcriptome and Proteome Level

In most lymphomas, p53 signaling pathway is inactivated by various mechanisms independent to p53 gene mutations or deletions. In many cases, p53 function is largely regulated by alterations in the protein abundance levels by the action of E3 ubiquitin-protein ligase MDM2, targeting p53 to proteasome-mediated degradation. In the present study, an integrating transcriptomics and proteomics analysis was employed to investigate the effect of p53 activation by a small-molecule MDM2-antagonist, nutlin-3a, on three lymphoma cell models following p53 activation. Our analysis revealed a system-wide nutlin-3a-associated effect in all examined lymphoma types, identifying in total of 4037 differentially affected proteins involved in a plethora of pathways, with significant heterogeneity among lymphomas. Our findings include known p53-targets and novel p53 activation effects, involving transcription, translation, or degradation of protein components of pathways, such as a decrease in key members of PI3K/mTOR pathway, heat-shock response, and glycolysis, and an increase in key members of oxidative phoshosphorylation, autophagy and mitochondrial translation. Combined inhibition of HSP90 or PI3K/mTOR pathway with nutlin-3a-mediated p53-activation enhanced the apoptotic effects suggesting a promising strategy against human lymphomas. Integrated omic profiling after p53 activation offered novel insights on the regulatory role specific proteins and pathways may have in lymphomagenesis.

Establishment and characterization of a novel breast implant-associated anaplastic large cell lymphoma cell line and PDX model (BIA-XR1) with a unique KRAS mutation

Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is an uncommon T-cell lymphoma type with distinct clinical, molecular and genetic features. Establishment of BIA-ALCL cell lines and patient-derived xenograft (PDX) models are essential experimental tools to investigate the molecular pathogenesis of the disease. We characterized a novel BIA-ALCL cell line and PDX model, named BIA-XR1, derived from a patient with textured breast implant who developed lymphoma. Next-generation sequencing revealed a STAT3 mutation, commonly detected in BIA-ALCL, and a unique KRAS mutation reported for the first time in this lymphoma type. Both JAK/STAT3 and RAS/MEK/ERK oncogenic pathways were activated in BIA-XR1, which are targetable with clinically available agents.

ALK+ Anaplastic Large Cell Lymphoma (ALCL)-Derived Exosomes Carry ALK Signaling Proteins and Interact with Tumor Microenvironment

Simple Summary

ALK+ anaplastic large cell lymphoma (ALK+ ALCL) is a distinct type of aggressive non-Hodgkin lymphoma of T-cell origin, which is characterized by overexpression and activation of ALK kinase due to chromosomal translocations of the gene. The most frequent chromosomal aberration is the t(2;5) resulting in the NPM-ALK chimeric protein, which exerts its oncogenic functions through activation of multiple oncogenic pathways. Exosomes, the best characterized type of extracellular vesicles, are secreted from the tumor cells, thus transferring signals to other cells that uptake exosomes. In this study, we demonstrate that ALK+ ALCL cells secrete exosomes that carry critical molecules of ALK signaling, which can be taken up by other cells with significant biologic effects including functional interactions with tumor microenvironment cells, which may contribute to tumor aggressiveness and possibly resistance to treatment.

Abstract

The oncogenic pathways activated by the NPM-ALK chimeric kinase of ALK+ anaplastic large cell lymphoma (ALCL) are well characterized; however, the potential interactions of ALK signaling with the microenvironment are not yet known. Here we report that ALK+ ALCL-derived exosomes contain critical components of ALK signaling as well as CD30, and that exosome uptake by lymphoid cells led to increased proliferation and expression of critical antiapoptotic proteins by the recipient cells. The bone marrow fibroblasts highly uptake ALK+ ALCL-derived exosomes and acquire a cancer-associated fibroblast (CAF) phenotype. Moreover, exosome-mediated activation of stromal cells altered the cytokine profile of the microenvironment. These interactions may contribute to tumor aggressiveness and possibly resistance to treatment.

MDMX/MDM4 is highly expressed and contributes to cell growth and survival in anaplastic large cell lymphoma

We hypothesized that murine double minute X (MDMX), a negative p53-regulator, may be involved in dysfunctional p53-signaling in anaplastic large cell lymphoma (ALCL), anaplastic lymphoma kinase (ALK)-positive and ALK-negative, characterized frequently by non-mutated TP53 (wt-p53). By western blot analysis, MDMX was highly expressed in ALK + ALCL and expressed at variable levels in ALK- ALCL cell lines. By immunohistochemistry, high MDMX levels were observed more frequently in ALK + ALCL (36/46; 78%), compared with ALK- ALCL tumors (12/29; 41%) (p < .0018, Mann-Whitney-test). FISH analysis showed MDMX-amplification in 1 of 13 (8%) ALK- ALCL tumors, and low-level MDMX copy gains in 2 of 13 (15%) ALK- ALCL and 3 of 11 (27%) ALK + ALCL tumors. MDMX-pharmacologic inhibition or siRNA-mediated MDMX-silencing were associated with activated p53 signaling, growth inhibition and apoptotic cell death in wt-p53 ALCL cells, providing evidence that targeting MDMX may provide a new therapeutic approach for ALCL patients with wt-p53.

Expression of the novel tumour suppressor sterile alpha motif and HD domain-containing protein 1 is an independent adverse prognostic factor in classical Hodgkin lymphoma

The expression patterns and prognostic significance of sterile alpha motif and HD domain-containing protein 1 (SAMHD1) protein in the neoplastic Hodgkin and Reed Sternberg (HRS) cells of Hodgkin lymphoma (HL) were investigated in a cohort of 154 patients with HL treated with standard regimens. SAMHD1 expression was assessed by immunohistochemistry using diagnostic lymph node biopsies obtained prior to treatment. Using an arbitrary 20% cut-off, SAMHD1 was positive in HRS cells of 48/154 (31·2%) patients. SAMHD1 expression was not associated with clinicopathologic parameters, such as age, gender, stage or histologic subtype. In 125 patients with a median follow-up of 90 months (7-401 months), SAMHD1 expression in HRS cells significantly correlated with inferior freedom from progression (FFP) (P = 0·025), disease-specific survival (DSS) (P = 0·013) and overall survival (OS) (P = 0·01). Importantly, in multivariate models together with disease stage, histology subtype and type of treatment as covariates, SAMHD1 expression retained an independent significant association with unfavourable FFP (P = 0·005) as well as DSS (P = 0·022) and OS (P = 0·018). These findings uncover the significance of a novel, adverse prognostic factor in HL that may have therapeutic implications since SAMHD1 inhibitors are now available for clinical use.

PD-1 protein and gene expression in early breast cancer: Prognostic implications

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Background: We have previously shown the prognostic value of PD-L1 protein and gene expression in early breast cancer (BC), however, the prognostic role of PD-1 expression remains unclear. Methods: The prognostic value of PD-1 in early BC was investigated using three different approaches: i) evaluation of PD-1 at the protein (IHC, immunohistochemistry in tissue microarrays) and mRNA levels in a retrospective patient cohort of 586 patients treated for early BC in Stockholm, Sweden between 1997-2005, ii) systematic review and trial-level meta-analysis of studies published in Medline, Embase, Cochrane Library and Web of Science Core Collection libraries on the prognostic value of PD-1 IHC expression, and iii) pooled analysis of transcriptomic data from 39 publicly available datasets for the prognostic capacity of PD-1 gene expression. Univariate and multivariable Cox regression models were used. Results: In the retrospective study cohort, PD-1 protein was significantly associated with biologically high-risk characteristics. PD-1 protein, but not gene expression, was correlated with improved overall survival (OS) (adjusted HR = 0.73, 95% CI 0.55 – 0.96, p = 0.023 and adjusted HR = 0.88, 95% CI 0.68 – 1.13, p = 0.307, respectively). In the trial-level meta-analysis, 4736 entries were initially identified and 15 studies, including our original cohort, fulfilled the predefined eligibility criteria. PD-1 IHC expression was not prognostic in unselected patients. However, a significant correlation to improved disease-free survival was seen within the triple-negative subtype (pooled multivariate HR = 0.57, 95% CI 0.29 – 0.90, p = 0.02). In the pooled gene expression analysis, PD-1 gene expression was associated with improved OS in the entire population (adjusted HR = 0.89, 95% CI 0.80 – 0.99, p = 0.025) and in basal-like (adjusted HR = 0.77, 95% CI 0.63 – 0.95, p = 0.014) tumors. Conclusions: PD-1 expression at the RNA and protein levels represent promising prognostic factors, especially in the triple-negative and basal-like subtypes. Standardization and further validation are needed prior to clinical implementation.

Programmed death-ligand 1 gene expression is a prognostic marker in early breast cancer and provides additional prognostic value to 21-gene and 70-gene signatures in estrogen receptor-positive disease

Gene and protein expression of programmed death‐ligand 1 (PD‐L1) are prognostic in early breast cancer (BC), but their prognostic information is inconsistent at least in some biological subgroups. The validated prognostic gene signatures (GS) in BC are mainly based on proliferation and estrogen receptor (ER)‐related genes. Here, we aimed to explore the prognostic capacity of PD‐L1 expression at the protein vs mRNA levels and to investigate the prognostic information that PD‐L1 can potentially add to routinely used GS. Gene expression data were derived from two early BC cohorts (cohort 1: 562 patients; cohort 2: 1081 patients). Tissue microarrays from cohort 1 were immunohistochemically (IHC) stained for PD‐L1 using the SP263 clone. GS scores (21‐gene, 70‐gene) were calculated, and likelihood‐ratio (LR) tests and concordance indices were used to evaluate the additional prognostic information for each signature. The immune cell composition was also evaluated using the CIBERSORT in silico tool. PD‐L1 gene and protein expressions were independently associated with better prognosis. In ER+/HER2− patients, PD‐L1 gene expression provided significant additional prognostic information beyond that of both 21‐GS [LR‐Δχ² = 15.289 and LR‐Δχ² = 8.812, P < 0.01 for distant metastasis‐free interval (DMFI) in cohorts 1 and 2, respectively] and 70‐GS score alone (LR‐Δχ² = 18.198 and LR‐Δχ² = 8.467, P < 0.01 for DMFI in cohorts 1 and 2, respectively). PD‐L1 expression was correlated with IHC‐determined CD3+ cells (r = 0.41, P < 0.001) and with CD8+ (r = 0.62, P < 0.001) and CD4+ memory activated (r = 0.66, P < 0.001) but not with memory resting (r = −0.063, P = 0.14) or regulatory (r = −0.12, P < 0.01) T cells in silico. PD‐L1 gene expression represents a promising favorable prognostic marker and can provide additional prognostic value to 21‐ and 70‐gene scores in ER+/HER2− BC.

Abstract P3-08-07: Expression of the novel tumor suppressor gene SAMHD1 correlates with favourable clinical outcome in basal-like (BL) early breast cancer

Introduction: The SAM domain and HD domain 1 (SAMHD1) protein is a deoxynucleoside triphosphate (dNTP) triphosphohydrolase initially described to restrict human immunodeficiency virus type 1 (HIV-1) in the immune cells through depletion of intracellular dNTP substrates required for HIV-1 replication. Because of its ability to deplete the dNTP pool, SAMHD1 may operate as a tumor suppressor in cancer. Mutations of SAMHD1 gene have been associated with Aicardi-Goutières syndrome and have been detected in certain hematologic malignancies. However, the potential role of SAMHD1 in breast oncogenesis as well as its expression patterns and clinical significance are not yet known. Methods: SAMHD1 expression was investigated at the mRNA and protein levels in a large cohort consisting of 562 patients diagnosed with primary breast cancer between 1997-2005 in Stockholm health care region. Gene expression profiling was performed using DNA microarrays (GSE48091). SAMHD1 protein expression was assessed by a previously validated double immunostaining method (SAMHD1/CD68) using tissue microarrays (TMA) that included duplicate cores from each tumor and specific antibody (SAMHD1, Bethyl laboratories; #A303-691A). CD68+ macrophages known to be strongly positive for SAMHD1 served as positive controls in each tumor core. Any nuclear staining for SAMHD1 was considered positive with either weak (1), intermediate (2), or strong (3) staining intensity. At least 500 neoplastic cells were counted in order to determine the percentage of SAMHD1+ tumor cells. The latter was combined with the staining intensity into the quickscore method, and a positive cutoff of greater or equal to 3 was used to dichotomize SAMHD1 protein expression. Survival analyses were performed using the Kaplan-Meier method (SAMHD1 mRNA level cutoff: median) and Cox proportional hazards models (univariate and multivariable analysis; SAMHD1 mRNA level was evaluated as continuous variable). Distant metastasis-free survival (DMFS) was used as the clinical endpoint. Results: Evaluable immunohistochemical (IHC) data for SAMHD1 were available for 439 of 562 (78%) patients. In the entire study group, SAMHD1 mRNA and protein levels were significantly correlated (Mann-Whitney p=5.2e-5). SAMHD1 mRNA level was higher in HER2-enriched (PAM50) tumors compared to the other subtypes (Kruskal-Wallis p=2.5e-12). By IHC, SAMHD1 was positive in 33/192 (17%) Luminal A, 17/85 (20%) Luminal B, 10/49 (20%) HER2-enriched, and 26/99 (26%) basal-like (BL). In the entire cohort, SAMHD1 expression was not associated with DMFS. However, in the group of BL subtype (n=122), high SAMHD1 mRNA level (logrank p=0.026) or SAMHD1 protein expression (logrank p=0.025) were associated with favourable DMFS. Using the Cox proportional hazards model, high SAMHD1 mRNA level (HR=0.68; 95% CI=0.48-0.96; p=0.029) and high SAMHD1 protein expression (HR=0.22; 95% CI=0.05-0.95; p=0.042; reference: SAMHD1 negative) were associated with improved survival in patients with BL subtype of breast cancer. In the multivariable analysis, SAMHD1 mRNA level was independently associated with survival (HR=0.66; 95% CI=0.47-0.94; p=0.021), after adjustment for lymph node status and tumor size, along with lymph node status (HR: 3.29; 95% CI=1.58-6.83; p=0.001; reference: lymph node negative) in the BL subgroup. At the meeting we will also present data on prognosis in relation to given adjuvant therapies.Conclusions: SAMHD1 gene is differentially expressed at the mRNA and protein levels among the breast cancer subtypes. SAMHD1 expression is significantly and independently associated with favourable clinical outcomes in breast cancer of BL subtype.

Citation Format: Maria Kouvaraki, Emmanuil G Sifakis, Ioannis Zerdes, Nikolas Herold, Jonas Bergh, George Z. Rassidakis, Theodoros Foukakis. Expression of the novel tumor suppressor gene SAMHD1 correlates with favourable clinical outcome in basal-like (BL) early breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-07.

STAT3 Activity Promotes Programmed-Death Ligand 1 Expression and Suppresses Immune Responses in Breast Cancer

Signal transducer and activator of transcription 3 (STAT3) is an oncogene and multifaceted transcription factor involved in multiple cellular functions. Its role in modifying anti-tumor immunity has been recently recognized. In this study, the biologic effects of STAT3 on immune checkpoint expression and anti-tumor responses were investigated in breast cancer (BC). A transcriptional signature of phosphorylated STAT3 was positively correlated with PD-L1 expression in two independent cohorts of early BC. Pharmacologic inhibition and gene silencing of STAT3 led to decreased Programmed Death Ligand 1 (PD-L1) expression levels in vitro, and resulted as well in reduction of tumor growth and decreased metastatic dissemination in a mammary carcinoma mouse model. The hampering of tumor progression was correlated to an anti-tumoral macrophage phenotype and accumulation of natural-killer cells, but also in reduced accrual of cytotoxic lymphocytes. In human BC, pro-tumoral macrophages correlated to PD-L1 expression, proliferation status and higher grade of malignancy, indicating a subset of patients with immunosuppressive properties. In conclusion, this study provides evidence for STAT3-mediated regulation of PD-L1 and modulation of immune microenvironment in BC.

Abstract P2-08-25: PD-L1 expression at the protein and RNA levels as prognostic factor in early breast cancer

Introduction:PD-L1 expression as assessed by immunohistochemistry (IHC) is a clinically relevant biomarker in certain malignancies such as lung cancer, since it selects appropriate candidates for PD-1 blockade. Since these agents are under evaluation for breast cancer, discovering and validating predictive biomarkers is of outmost importance. However, the clinical utility of PD-L1 expression in breast cancer is questionable, in light of prior inconclusive reports which have used various IHC antibodies, scoring methods and cut-offs. Moreover, there are only few previous studies on comparing IHC and RNA data at the same cohort, not limited to a single subtype.Methods: Our cohort is derived from a nested case-control study consisting of 619 patients diagnosed with primary breast cancer between 1997-2005 in Stockholm health care region.Tissue microarrays from epithelial tumor areas have been constructed using duplicate cores from primary tumors and tissue sections were used for IHC with PD-L1 (Ventana; clone SP263) antibody. Positivity was defined as the presence of any single cell with membranous expression of PD-L1. Gene expression profiling was performed using DNA microarrays (GSE48091). Data on clinical and pathological tumor characteristics, survival, loco-regional and systemic treatments, and follow-up have been collected. Correlations between transcript and protein expression levels were estimated using Mann-Whitney test, while survival analyses were conducted using the Kaplan-Meier method. Furthermore, we associated an immune gene module score (IMS) –whose predictive power in neoadjuvant and metastatic settings has been previously demonstrated- with PD-L1 transcript levels by using Spearman's rank correlation coefficient.Results: IHC data were available for 87.4% (541/619) of the patients. PD-L1 was expressed on tumor cells in 9.6% (52/541) of the patients while it was also expressed by immune cells in 23.1% (125/541) of the patients. Any PD-L1 expression (tumor and/or immune cells) was noted in 24.2% (131/541) of the patients. PD-L1 transcript levels and protein expression on tumor, immune and/or both cell types were statistically significantly associated (p&lt; 2.2e-16). In the whole cohort, patients with higher PD-L1 transcript levels were associated with better breast cancer-specific survival(BCSS) (p=0.0061). In addition, within intrinsic subtypes, high PD-L1 transcript expression was significantly associated with better BCSS only in basal-like (p=0.019) disease. There was no significant correlation between improved BCCS and PD-L1 protein expression by tumor (p=0.13), immune (p=0.12) or both types of cells (p=0.2). PD-L1 transcript levels were also positively associated with the IMS (Spearman's rho = 0.85). Conclusions:The prognostic value of PD-L IHC expression in breast cancer remains inconclusive. However, RNA expression of PD-L1 may be more informative as a prognostic factor, especially in basal-like disease and merits further validation.

Citation Format: Zerdes I, Sifakis E, Matikas A, Tobin NP, Charlotte R, Rassidakis GZ, Bergh J, Foukakis T. PD-L1 expression at the protein and RNA levels as prognostic factor in early breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-25.

Immune Profiling and Quantitative Analysis Decipher the Clinical Role of Immune-Checkpoint Expression in the Tumor Immune Microenvironment of DLBCL

PD-1/L1 and CTLA-4 blockade immunotherapies have been approved for 13 types of cancers and are being studied in diffuse large B-cell lymphoma (DLBCL), the most common aggressive B-cell lymphoma. However, whether both PD-1 and CTLA-4 checkpoints are active and clinically significant in DLBCL is unknown. Whether PD-1 ligands expressed by tumor cells or by the microenvironment of DLBCL are critical for the PD-1 immune checkpoint is unclear. We performed immunophenotypic profiling for 405 patients with de novo DLBCL using a MultiOmyx immunofluorescence platform and simultaneously quantitated expression/coexpression of 13 immune markers to identify prognostic determinants. In both training and validation cohorts, results demonstrated a central role of the tumor immune microenvironment, and when its functionality was impaired by deficiency in tumor-infiltrating T cells and/or natural killer cells, high PD-1 expression (but not CTLA-4) on CD8⁺ T cells, or PD-L1 expression on T cells and macrophages, patients had significantly poorer survival after rituximab-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) immunochemotherapy. In contrast, tumor-cell PD-L2 expression was associated with superior survival, as well as PD-L1⁺CD20⁺ cells proximal (indicates interaction) to PD-1 ⁺ CD8⁺ T cells in patients with low PD-1 ⁺ percentage of CD8⁺ T cells. Gene-expression profiling results suggested the reversibility of T-cell exhaustion in PD-1⁺/PD-L1⁺ patients with unfavorable prognosis and implication of LILRA/B, IDO1, CHI3L1, and SOD2 upregulation in the microenvironment dysfunction with PD-L1 expression. This study comprehensively characterized the DLBCL immune landscape, deciphered the differential roles of various checkpoint components in rituximab-CHOP resistance in DLBCL patients, and suggests targets for PD-1/PD-L1 blockade and combination immunotherapies.

Low-level expression of SAMHD1 in acute myeloid leukemia (AML) blasts correlates with improved outcome upon consolidation chemotherapy with high-dose cytarabine-based regimens

Sterile alpha motif and histidine/aspartic acid domain containing protein 1 (SAMHD1) limits the efficacy of cytarabine (ara-C) used in AML by hydrolyzing its active metabolite ara-CTP and thus represents a promising therapeutic target. SAMHD1 has also been implicated in DNA damage repair that may impact DNA damage-inducing therapies such as anthracyclines, during induction therapy. To determine whether SAMHD1 limits ara-C efficacy during induction or consolidation therapy, SAMHD1 protein levels were assessed in two patient cohorts of de novo AML from The University of Texas MD Anderson Cancer Center (USA) and the National University Hospital (Singapore), respectively, using immunohistochemistry and tissue microarrays. SAMHD1 was expressed at a variable level by AML blasts but not in a broad range of normal hematopoietic cells in reactive bone marrows. A sizeable patient subset with low SAMHD1 expression (<25% of positive blasts) was identified, which was significantly associated with longer event-free (EFS) and overall (OS) survival in patients receiving high-dose cytarabine (HDAC) during consolidation. Therefore, evaluation of SAMHD1 expression level in AML blasts at diagnosis, may stratify patient groups for future clinical trials combining HDAC with novel SAMHD1 inhibitors as consolidation therapy.

Genetic, transcriptional and post-translational regulation of the programmed death protein ligand 1 in cancer: biology and clinical correlations

The programmed death protein 1 (PD-1) and its ligand (PD-L1) represent a well-characterized immune checkpoint in cancer, effectively targeted by monoclonal antibodies that are approved for routine clinical use. The regulation of PD-L1 expression is complex, varies between different tumor types and occurs at the genetic, transcriptional and post-transcriptional levels. Copy number alterations of PD-L1 locus have been reported with varying frequency in several tumor types. At the transcriptional level, a number of transcriptional factors seem to regulate PD-L1 expression including HIF-1, STAT3, NF-κΒ, and AP-1. Activation of common oncogenic pathways such as JAK/STAT, RAS/ERK, or PI3K/AKT/MTOR, as well as treatment with cytotoxic agents have also been shown to affect tumoral PD-L1 expression. Correlative studies of clinical trials with PD-1/PD-L1 inhibitors have so far shown markedly discordant results regarding the value of PD-L1 expression as a marker of response to treatment. As the indications for immune checkpoint inhibition broaden, understanding the regulation of PD-L1 in cancer will be of utmost importance for defining its role as predictive marker but also for optimizing strategies for cancer immunotherapy. Here, we review the current knowledge of PD-L1 regulation, and its use as biomarker and as therapeutic target in cancer.

Alterations in the expression of DNA damage response-related molecules in potentially preneoplastic oral epithelial lesions

OBJECTIVES

The aim of this study was to evaluate the expression levels of DNA damage response (DDR) markers in potentially preneoplastic oral epithelial lesions (PPOELs).

STUDY DESIGN

Immunohistochemical expression of DDR markers (γΗ2 ΑΧ, pChk2, 53 BP1, p53, and phosphorylated at Ser 15 p53) was assessed in 41 oral leukoplakias, ranging from hyperplasia (H) to dysplasia (D) and in comparison with oral squamous cell carcinoma (OSCC) and normal mucosa (NM). Statistical and receiver operating characteristic curve analysis were performed.

RESULTS

γH2 AX immunoexpression demonstrated a gradual increase and upper layer extension from NM to H to higher D degrees to OSCC. pChk2 expression was minimal in NM, relatively low in PPOELs, with an increasing tendency from H to D, and higher in OSCC. 53 BP1 demonstrated higher levels in OSCC than in NM, whereas its expression in PPOELs was heterogeneous, gradually increasing according to D. p53 demonstrated progressively higher levels and upper layer extension from H to D to OSCC. Phosphorylated p53 was absent in NM and relatively low in PPOELs and OSCC.

CONCLUSIONS

DDR markers' expression is variable in PPOELs, showing a tendency to increase along with dysplasia. Activated DDR mechanisms may play an important protective role at early stages of oral carcinogenesis, but probably suffer progressive deregulation, eventually failing to suppress malignant transformation.

Deciphering lymphoma pathogenesis via state-of-the-art mass spectrometry-based quantitative proteomics

Mass spectrometry-based quantitative proteomics specifically applied to comprehend the pathogenesis of lymphoma has incremental value in deciphering the heterogeneity in complex deregulated molecular mechanisms/pathways of the lymphoma entities, implementing the current diagnostic and therapeutic strategies. Essential global, targeted and functional differential proteomics analyses although still evolving, have been successfully implemented to shed light on lymphoma pathogenesis to discover and explore the role of potential lymphoma biomarkers and drug targets. This review aims to outline and appraise the present status of MS-based quantitative proteomic approaches in lymphoma research, introducing the current state-of-the-art MS-based proteomic technologies, the opportunities they offer in biological discovery in human lymphomas and the related limitation issues arising from sample preparation to data evaluation. It is a synopsis containing information obtained from recent research articles, reviews and public proteomics repositories (PRIDE). We hope that this review article will aid, assimilate and assess all the information aiming to accelerate the development and validation of diagnostic, prognostic or therapeutic targets for an improved and empowered clinical proteomics application in lymphomas in the nearby future.

mTOR downstream effectors, 4EBP1 and eIF4E, are overexpressed and associated with HPV status in precancerous lesions and carcinomas of the uterine cervix

The present study aims to investigate the expression levels of two critical mammalian target of rapamycin (mTOR) downstream effectors, 4E binding protein 1 (4EBP1) and eukaryotic initiation factor 4E (eIF4E) proteins, in precancerous squamous intraepithelial lesions and cancer of the uterine cervix, and their association with human papilloma virus (HPV) infection status. Uterine cervical biopsies from 73 patients were obtained, including 40 fresh-frozen samples and 42 archival formalin-fixed, paraffin-embedded tissue specimens. Whole protein extracts were analyzed for the expression of 4EBP1 and eIF4E proteins using western blotting. In addition, distribution of 4EBP1 and eIF4E protein expression and 4EBP1 phosphorylation (P-4EBP1) were analyzed by immunohistochemistry in archival tissues and correlated with the degree of dysplasia. The presence of high-risk HPV (HR-HPV) types was assessed by polymerase chain reaction. Using western blot analysis, high expression levels of 4EBP1 and eIF4E were observed in all uterine cervical carcinomas, which significantly correlated with the degree of dysplasia. By immunohistochemistry, overexpression of 4EBP1 and eIF4E was detected in 20 of 21 (95%) and 17 of 21 (81%) samples, respectively, in patients with high-grade dysplasia and carcinomas, compared with 1 of 20 (5%) and 2 of 20 (10%) samples, respectively, in patients with low-grade lesions or normal histology. All 4EBP1-positive cases tested were also positive for P-4EBP1. Furthermore, overexpression of 4EBP1 and eIF4E significantly correlated with the presence of HR-HPV oncogenic types. The present study demonstrated that critical effectors of mTOR signaling, which control protein synthesis initiation, are overexpressed in cervical high-grade dysplasia and cancer, and their levels correlate with oncogenic HPV types. These findings may provide novel targets for investigational therapeutic approaches in patients with cancer of the uterine cervix.

Down-regulation of the cyclin-dependent kinase inhibitor p57 is mediated by Jab1/Csn5 in hepatocarcinogenesis

Down-regulation of p57 (KIP2) cyclin-dependent kinase inhibitors accelerates the growth and invasion of hepatocellular carcinoma (HCC), suggesting that p57 may play an important role in liver carcinogenesis. However, the mechanism or oncogenic signal leading to p57 down-regulation in HCC remains to be determined. Herein, we demonstrated that Jab1/Csn5 expression is negatively correlated with p57 levels in HCC tissues. Kaplan-Meier analysis of tumor samples revealed that high Jab1/Csn5 expression with concurrent low p57 expression is associated with poor overall survival. The inverse pattern of Jab1 and p57 expression was also observed during carcinogenesis in a chemically induced rat HCC model. We also found that mechanistically, Jab1-mediated p57 proteolysis in HCC cells is dependent on 26S-proteasome inhibitors. We further demonstrated that direct physical interaction between Jab1 and p57 triggers p57 down-regulation, independently of Skp2 and Akt pathways, in HCC cells. These data suggest that Jab1 is an important upstream negative regulator of p57 and that aberrant expression of Jab1 in HCC could lead to a significant decrease in p57 levels and contribute to tumor cell growth. Furthermore, restoration of p57 levels induced by loss of Jab1 inhibited tumor cell growth and further increased cell apoptosis in HCC cells. Moreover, silencing Jab1 expression further enhanced the antitumor effects of cisplatin-induced apoptosis in HCC cells.

CONCLUSION

Jab1-p57 pathway confers resistance to chemotherapy and may represent a potential target for investigational therapy in HCC.

The emerging role of CD30 and p53 as novel targets for therapy in anaplastic large cell lymphoma

ALK+ anaplastic large cell lymphoma (ALCL). frequently carries the t(2;5).(p23;q35). resulting in expression of NPM-ALK oncogenic kinase, which is capable of activating multiple oncogenic pathways. ALK+ ALCL is also characterized by overexpression of CD30 receptor, a member of the tumor necrosis factor (TNF). receptor superfamily, which has been targeted for therapy using conjugated anti-CD30 antibodies with clinical success. Also, the tumor suppressor p53 is frequently non-mutated in ALK+ ALCL allowing for therapeutic modulation of p53 reactivation in this lymphoma type. Therefore, this review is focused on the role of CD30 receptor and p53 as novel targets for therapy in ALK+ ALCL, and also provides an update on their potential involvement in ALK+ ALCL pathogenesis.

Constitutive control of AKT1 gene expression by JUNB/CJUN in ALK+ anaplastic large-cell lymphoma: a novel crosstalk mechanism

Anaplastic lymphoma kinase-positive (ALK+) anaplastic large-cell lymphoma (ALCL) is an aggressive T-cell non-Hodgkin lymphoma characterized by the t(2;5), resulting in the overexpression of nucleophosmin (NPM)-ALK, which is known to activate the phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway, resulting in cell cycle and apoptosis deregulation. ALK+ ALCL is also characterized by strong activator protein-1 (AP-1) activity and overexpression of two AP-1 transcription factors, CJUN and JUNB. Here, we hypothesized that a biologic link between AP-1 and AKT kinase may exist, thus contributing to ALCL oncogenesis. We show that JUNB and CJUN bind directly to the AKT1 promoter, inducing AKT1 transcription in ALK+ ALCL. Knockdown of JUNB and CJUN in ALK+ ALCL cell lines downregulated AKT1 mRNA and promoter activity and was associated with lower AKT1 protein expression and activation. We provide evidence that this is a transcriptional control mechanism shared by other cell types even though it may operate in a way that is cell context-specific. In addition, STAT3 (signal transducer and activator of transcription 3)-induced control of AKT1 transcription was functional in ALK+ ALCL and blocking of STAT3 and AP-1 signaling synergistically affected cell proliferation and colony formation. Our findings uncover a novel transcriptional crosstalk mechanism that links AP-1 and AKT kinase, which coordinate uncontrolled cell proliferation and survival in ALK+ ALCL.

Expression of Somatostatin Receptors 1-5 and Dopamine Receptor 2 in Lung Carcinoids: Implications for a Therapeutic Role

OBJECTIVE

The expression of somatostatin receptors (SSTRs) and dopamine receptor 2 (DR2) in neuroendocrine tumors is of clinical importance as somatostatin analogues and dopamine agonists can be used for their localization and/or treatment. The objective of this study is to examine the expression of the five SSTR subtypes and DR2 in lung carcinoids (LCs).

METHODS

We conducted a retrospective study of 119 LCs from 106 patients [typical carcinoids (TCs): n = 100, and atypical carcinoids (ACs): n = 19]. The expression of all five SSTR subtypes and DR2 was evaluated immunohistochemically and correlated to clinicopathological data. In a subgroup of cases, receptor expression was further analyzed using semiquantitative RT-PCR.

RESULTS

SSTR2A was the SSTR subtype most frequently expressed immunohistochemically (72%), followed by SSTR1 (63%), SSTR5 (40%), and SSTR3 (20%), whereas SSTR4 was negative. DR2 was expressed in 74% and co-expressed with SSTR1 in 56%, with SSTR2A in 59%, with SSTR3 in 19%, and with SSTR5 in 37% of the tumors. Receptor expression was not related to the histological subtype, tumor aggressiveness (disease extent/grading) or functionality; however, DR2 was expressed more frequently in ACs than TCs (95 vs. 70%, p = 0.017). In a subset of patients, RT-PCR findings highly suggested that the expression of SSTR2A, SSTR3, DR2, and to a lesser extent that of SSTR1 and SSTR5 is the outcome of increased gene transcription.

CONCLUSIONS

The high and variable immunohistochemical expression of the majority of SSTRs along with their co-expression with DR2 in LCs provides a rationale for their possible treatment with agents that target these receptors.

SIN1, a critical component of the mTOR-Rictor complex, is overexpressed and associated with AKT activation in medullary and aggressive papillary thyroid carcinomas

BACKGROUND

Mammalian target of rapamycin (mTOR) forms 2 active complexes in the cell: the rapamycin-sensitive mTOR-Raptor (mTORC1) and the rapamycin-insensitive mTOR-Rictor (mTORC2). The latter activates AKT kinase, which promotes tumor cell survival and proliferation by multiple downstream targets. Mammalian stress-activated protein kinase interacting protein 1 (SIN1), an essential subunit of the mTORC2 complex, maintains the integrity of the complex and substrate specificity and regulates Akt activation. The role of mTOR-Rictor complex activation in thyroid carcinogenesis remains unknown. Therefore, we investigated expression patterns of Sin1 in the cells lines of thyroid carcinoma and tumors and their association with AKT activation, histologic type, and tumor aggressiveness.

METHODS

Tissue specimens from 42 patients with thyroid cancer, including follicular (5), papillary (18), medullary (16), and poorly differentiated (3) carcinomas were analyzed via immunohistochemistry for SIN1 expression and AKT phosphorylation at Ser473 residue (Ser473-p-AKT). Eight of 18 papillary carcinomas were aggressive histologic variants. In addition, expression of Sin1 and activation of AKT kinase were analyzed in fresh-frozen tissue samples (normal/tumor), primary cell cultures (papillary thyroid carcinoma [PTC]), and an established thyroid cancer cell line (medullary thyroid carcinoma) by Western blotting.

RESULTS

With immunohistochemistry, we found that Sin1 was overexpressed in medullary thyroid carcinomas and aggressive variants of papillary thyroid carcinoma compared with conventional papillary and follicular carcinomas (P < .001). Sin1 expression correlated with AKT activation in the entire study group (P = .002). Using Western blot analysis, we found that Sin1 and p-AKT were detected at a greater level in cultured primary cells from aggressive PTC compared with conventional PTC as well as in cell lines of medullary and anaplastic thyroid carcinoma. High expression levels of SIN1 were detected in papillary thyroid carcinomas compared with benign nodules in immunoblots in which we used fresh-frozen patient samples. Two of the Sin1 protein isoforms, p76 and p55, were detected predominantly in PTC samples.

CONCLUSION

Sin1, a critical factor of the mTORC2 complex is overexpressed in clinically aggressive thyroid cancer types and is associated strongly with activation of AKT kinase. Sin1-dependent AKT activation might represent a target for experimental therapy.

CD3(-)CD16(-)CD56(bright) immunoregulatory NK cells are increased in the tumor microenvironment and inversely correlate with advanced stages in patients with papillary thyroid cancer

BACKGROUND

The innate immune system is the first line of defense and plays a key role in thyroid cancer development. The role of the tumor-infiltrating natural killer (NK) cells is becoming increasingly important in research and potential cancer therapies. NK cell subpopulations, CD3(-)CD16(+)CD56(dim) and CD3(-)CD16(-)CD56(bright), demonstrate a significant role in the tumor immuno-surveillance process.

METHODS

We investigated the distribution of CD3(-)CD16(+)CD56(dim) and CD3(-)CD16(-)CD56(bright) NK subpopulations in tissue and blood samples from patients with papillary thyroid cancer (PTC) and nodular goiter (NG). Twenty-eight patients with PTC, 13 patients with NG, and 50 healthy donors were included in the study. Tissue and blood samples from all patients and blood samples from healthy donors were analyzed for CD3(-)CD16(+)CD56(dim) and CD3(-)CD16(-)CD56(bright) NK cells by flow cytometry.

RESULTS

A significant predominance of CD3(-)CD16(+)CD56(dim) cells compared to CD3(-)CD16(-)CD56(bright) NK cells was found in blood samples in all groups (p<0.0001 in PTC, NG, and healthy donors). Increased infiltration by CD3(-)CD16(-)CD56(bright) NK cells was observed in thyroid tissue of patients with PTC, as compared to CD3(-)CD16(+)CD56(dim) NK cells (p=0.046), while CD3(-)CD16(+)CD56(dim) NK cells demonstrated a higher infiltration of NG tissues. CD3(-)CD16(+)CD56(dim) NK cell tissue infiltration positively correlated with advanced stages of PTC. In contrast, the CD3(-)CD16(-)CD56(bright) NK cell population was negatively associated with tumor stage in patients with PTC.

CONCLUSION

CD3(-)CD16(-)CD56(bright) NK cell infiltration seems to be associated with PTC progression. These findings contribute to a better understanding of the immune response in PTC and may lead to novel immunotherapeutic approaches in these patients.

Phenotypical analysis of lymphocytes with suppressive and regulatory properties (Tregs) and NK cells in the papillary carcinoma of thyroid

CONTEXT

The immune system seems to play a key role in preventing metastasis and recurrence of thyroid cancer. T regulatory lymphocytes (Tregs) and natural killer (NK) cells play an important role in the dysfunction of the host immune system in cancer patients.

OBJECTIVE

We investigated thyroid gland infiltration by Tregs and NK cells in patients with papillary thyroid cancer (PTC) and thyroid nodular goiter (TNG). The correlation between the extent of the disease and the lymphocytic infiltration of Tregs and NK cells was examined.

DESIGN, SETTING, AND PARTICIPANTS

A total of 65 patients with PTC, 25 with TNG, and 50 healthy controls were studied. Blood and tissue samples from 28 patients with PTC and 13 with TNG and blood samples from the healthy controls were analyzed for T4 (CD3(+)CD4(+)), T8 (CD3(+)CD8(+)), NK (CD3(-)CD16(+)CD56(+)), and CD4(+)CD25(+)CD127(-/low) Tregs by flow cytometry (FC). Tissue samples were also analyzed for Foxp3(+) Tregs by immunohistochemistry.

RESULTS

Tregs showed greater infiltration in thyroid tissue of PTC patients compared with patients with TNG (P < 0.0009 for FC and P < 0.0001 for immunohistochemistry); FC analysis of blood samples showed no difference between the groups. Flow cytometry analysis showed significantly increased NK cells in PTC tissue compared with TNG tissue (P = 0.037), whereas blood samples showed no difference. CD4(+) and CD8(+) T cells did not differ in blood and tissue samples. Increased Tregs tissue infiltration was positively correlated with advanced disease stage (P < 0.0026), whereas NK infiltration was negatively correlated (P < 0.0041).

CONCLUSION

Tregs and NK cells may be important regulators of thyroid cancer progression.

Activation of mTOR signaling in medullary and aggressive papillary thyroid carcinomas

BACKGROUND

Because mammalian target of rapamycin (mTOR) may be involved in thyroid carcinogenesis, we investigated the expression and activation patterns of mTOR signaling proteins in thyroid carcinoma cells and tumors and their association with tumor histology and aggressiveness.

METHODS

Tissue specimens from 50 patients with thyroid cancer were analyzed for eIF4E, a critical downstream target of the mTOR pathway, using immunohistochemistry. In addition, fresh-frozen samples from patients, and primary tumor cell cultures were analyzed for expression and activation of mTOR signaling proteins by Western blot. Moreover, pharmacologic studies with rapamycin were performed.

RESULTS

High expression of eIF4E was observed in medullary thyroid carcinomas (MTC) and in aggressive variants of papillary thyroid carcinomas (PTC) as compared with conventional PTC and follicular thyroid carcinomas (P < .0001). The level of eIF4E expression also correlated with tumor stage (P = .002). Using Western blot analysis, p-rpS6, p-4EBP1, 4EBP1, and eIF4E were detected at higher levels in aggressive PTC and MTC cells. Treatment of MTC cells with increasing concentrations of rapamycin resulted in significant cell death and in decreased cell growth associated with deactivation of the mTOR pathway.

CONCLUSION

mTOR signaling, which controls protein synthesis through regulation of translation initiation, is activated in aggressive PTC and MTC and represents a promising target for investigational therapies in these patients.

Expression patterns of endothelin-1 and its receptors in colorectal cancer

BACKGROUND AND OBJECTIVES

Endothelin-1 (ET-1), a potent vasoconstricting peptide, plays an important role in carcinogenesis. Previous in vitro studies have shown that colorectal cancer cells produce ET-1.

METHODS

ET-1 and its receptors ET-A (ET(A) R) and ET-B (ET(B) R) were analyzed in colorectal cancer cell lines and tumors by Western blot and immunohistochemistry. Also, ET-1 levels were measured by ELISA in blood samples collected before and after tumor resection.

RESULTS

ET-1 was immunohistochemically expressed by tumor cells at a variable level in 39 cases tested. The adjacent normal mucosa was negative for ET-1 expression. Strong ET(A) R expression observed in the deeper infiltrating areas at the periphery of neoplastic tissue correlated significantly with tumor stage. ET(B) R levels were very low or undetectable. Western blot analysis in paired (normal, tumor) fresh-frozen samples of colorectal cancers and in four colon carcinoma cell lines confirmed these findings. In addition, lower levels of ET-1 in the peripheral circulation after the tumor resection were found by ELISA as compared to those observed before surgery.

CONCLUSIONS

ET-1 and ET(A) R, but not ET(B) R, are expressed at a higher level in primary and cultured colon carcinoma cells as compared to normal colon mucosa cells. Further functional studies are needed to explore the role of ET-1/ET(A) R axis in colon carcinogenesis.

Activation of the p53 pathway by the MDM2 inhibitor nutlin-3a overcomes BCL2 overexpression in a preclinical model of diffuse large B-cell lymphoma associated with t(14;18)(q32;q21)

p53 is frequently wild type (wt) in diffuse large B-cell lymphoma (DLBCL) associated with t(14;18)(q32;q21) that overexpresses BCL2. Nutlin-3a is a small molecule that activates the p53 pathway by disrupting p53–MDM2 interaction. We show that nutlin-3a activates p53 in DLBCL cells associated with t(14;18)(q32;q21), BCL2 overexpression and wt p53, resulting in cell cycle arrest and apoptosis. Nutlin-3a treatment had similar effects on DLBCL cells of activated B-cell phenotype with wt p53. Cell cycle arrest was associated with upregulation of p21. Nutlin-3a-induced apoptosis was accompanied by BAX and PUMA upregulation, BCL-XL downregulation, serine-70 dephosphorylation of BCL2, direct binding of BCL2 by p53, caspase-9 upregulation and caspase-3 cleavage. Cell death was reduced when p53-dependent transactivation activity was inhibited by pifithrin-α (PFT-α), or PFT-μ inhibited direct p53 targeting of mitochondria. Nutlin-3a sensitized activation of the intrinsic apoptotic pathway by BCL2 inhibitors in t(14;18)-positive DLBCL cells with wt p53, and enhanced doxorubicin cytotoxicity against t(14;18)-positive DLBCL cells with wt or mutant p53, the latter in part via p73 upregulation. Nutlin-3a treatment in a xenograft animal lymphoma model inhibited growth of t(14;18)-positive DLBCL tumors, associated with increased apoptosis and decreased proliferation. These data suggest that disruption of the p53–MDM2 interaction by nutlin-3a offers a novel therapeutic approach for DLBCL associated with t(14;18)(q32;q21).

mTOR signaling is activated by FLT3 kinase and promotes survival of FLT3-mutated acute myeloid leukemia cells

Activating mutations of the FLT3 gene mediate leukemogenesis, at least in part, through activation of PI3K/AKT. The mammalian target of rapamycin (mTOR)-Raptor signaling pathway is known to act downstream of AKT. Here we show that the mTOR effectors, 4EBP1, p70S6K and rpS6, are highly activated in cultured and primary FLT3-mutated acute myeloid leukemia (AML) cells. Introduction of FLT3-ITD expressing constitutively activated FLT3 kinase further activates mTOR and its downstream effectors in BaF3 cells. We also found that mTOR signaling contributes to tumor cell survival, as demonstrated by pharmacologic inhibition of PI3K/AKT/mTOR, or total silencing of the mTOR gene. Furthermore, inhibition of FLT3 kinase results in downregulation of mTOR signaling associated with decreased survival of FLT3-mutated AML cells. These findings suggest that mTOR signaling operates downstream of activated FLT3 kinase thus contributing to tumor cell survival, and may represent a promising therapeutic target for AML patients with mutated-FLT3.

Essential roles of Jab1 in cell survival, spontaneous DNA damage and DNA repair

Jun activation domain-binding protein 1 (JAB1) is a multifunctional protein that participates in the control of cell proliferation and the stability of multiple proteins. JAB1 overexpression has been implicated in the pathogenesis of human cancer. JAB1 regulates several key proteins and thereby produces varied effects on cell cycle progression, genome stability and cell survival. However, the biological significance of JAB1 activity in these cellular signaling pathways is unclear. Therefore, we developed mice that were deficient in Jab1 and analyzed the null embryos and heterozygous cells. This disruption of Jab1 in mice resulted in early embryonic lethality due to accelerated apoptosis. Loss of Jab1 expression sensitized both mouse primary embryonic fibroblasts and osteosarcoma cells to γ-radiation-induced apoptosis, with an increase in spontaneous DNA damage and homologous recombination (HR) defects, both of which correlated with reduced levels of the DNA repair protein Rad51 and elevated levels of p53. Furthermore, the accumulated p53 directly binds to Rad51 promoter, inhibits its activity and represents a major mechanism underlying the HR repair defect in Jab1-deficient cells. These results indicate that Jab1 is essential for efficient DNA repair and mechanistically link Jab1 to the maintenance of genome integrity and to cell survival.

Expression of eukaryotic initiation factor 4E predicts clinical outcome in patients with mantle cell lymphoma treated with hyper-CVAD and rituximab, alternating with rituximab, high-dose methotrexate, and cytarabine

BACKGROUND

Oncogenic AKT/mammalian target of rapamycin (mTOR) signaling has recently been shown to contribute to tumor survival and proliferation in mantle cell lymphoma (MCL) through its downstream effector eukaryotic initiation factor 4E (eIF4E), which may control cyclin D1 protein levels. However, the clinical significance of eIF4E expression in MCL is unknown.

METHODS

The authors investigated the prognostic significance of eIF4E expression in 70 MCL patients uniformly treated with hyper-CVAD and rituximab, alternating with the rituximab, high-dose methotrexate, and cytarabine regimen (R-hyper-CVAD). eIF4E expression was assessed using tissue biopsy specimens obtained before treatment, immunohistochemical methods, and a highly specific monoclonal antibody. Failure-free (FFS) and overall (OS) survival were used as endpoints in univariate and multivariate survival analysis.

RESULTS

High eIF4E expression was found in 28 (40%) MCL tumors. After a median follow-up of 51 months for survivors, the 5-year FFS was 20.6% for patients with high eIF4E expression, compared with 63.5% for patients with low or no eIF4E expression (P=.01, log-rank). Similarly, the 5-year OS was 40.1% for patients with high eIF4E expression, compared with 73.8% for patients with low or no eIF4E expression (P=.018, log-rank). In multivariate analysis, eIF4E expression was associated with poorer FFS and OS, along with age>60 years and high beta2-microglobulin in the final prognostic model.

CONCLUSIONS

In summary, eIF4E, which seems to recapitulate most of the biologic effects of mTOR signaling in MCL, is an independent predictor of clinical outcome in MCL patients uniformly treated with the R-hyper-CVAD regimen.

Potential role of Jun activation domain-binding protein 1 as a negative regulator of p27kip1 in pancreatic adenocarcinoma

Reduced expression of p27 has been associated with poor prognosis in most human cancers, including pancreatic adenocarcinoma. Jun activation domain-binding protein 1 (JAB1), an activator protein (AP-1) coactivator, previously implicated in p27 degradation, is overexpressed in various tumors and correlates with low p27 expression. We examined JAB1 and p27 in normal and neoplastic pancreatic tissues. Increased JAB1 expression was seen in pancreatic carcinoma samples but not in paired normal pancreatic tissues. Immunohistochemical analysis using tissue microarrays showed that JAB1 was overexpressed in all 32 (100%) pancreatic adenocarcinoma samples tested, predominantly nuclear in 23 (72%) samples and predominantly cytoplasmic in 9 (28%) tumors. When 10% was used as a cutoff for p27 positivity, p27 was expressed in 11 (34%) of tumors; however, p27 expression was localized in the nuclei of tumor cells in only 4 (13%) of the samples. Overexpression of the JAB1 in the pancreatic carcinoma cell lines Panc-1, Mia PaCa-2, and Panc-28 resulted in decreased p27 expression. Conversely, down-regulation of JAB1 by short interfering RNA substantially increased p27 expression and inhibited progression from G(1) to S phase of the cell cycle. Interestingly, JAB1-mediated p27 degradation was not impaired when S-phase kinase-interacting protein 2 (Skp2), an F-box protein required for the ubiquitination and consequent degradation of p27, was silenced. Thus, JAB1 may have an Skp2-independent p27 degradation mechanism in pancreatic cancer cells. These findings suggest that JAB1 overexpression is involved in the pathogenesis of pancreatic cancer through JAB1-mediated p27 degradation and that control of JAB1 expression is a novel therapeutic target in patients with pancreatic adenocarcinomas.

TCL1 in B-cell tumors retains its normal b-cell pattern of regulation and is a marker of differentiation stage

The high expression of the T-cell oncogene TCL1 in B-cell tumors and the emergence of B-cell lymphomas in TCL1-transgenic mice suggest a pathogenetic role for this kinase coregulator in B-cell malignancies. We compared the expression of TCL1 in B-cell tumors with their differentiation stage. As with normal B-cell subsets, uniform TCL1 expression was characteristic of tumors of pregerminal center derivation such as precursor B-cell lymphoblastic leukemia/lymphoma (85%, 47/55) and mantle cell lymphoma (84%, 49/58), and was more variable in follicular lymphoma (57%, 28/49). Large B-cell lymphoma was less frequently positive for TCL1 (36%, 18/50), especially among cases of the activated B-cell type. All types of Hodgkin lymphoma, splenic marginal zone lymphoma, and post-germinal center-derived tumors, including plasma cell myeloma and MALT lymphoma, were negative for TCL1, except for 1 case. In nearly all TCL1-expressing tumors, as with normal B cells, variations in cellular TCL1 levels were related to the proliferation and microenvironmental factors. In normal B cells, cell lines and primary B-cell tumor samples, TCL1 downmodulation occurred after prolonged cytokine treatment and/or B-cell receptor stimulation. In contrast to mature T-cell tumors where TCL1 expression is always indicative of an activating TCL1 gene translocation, TCL1 expression in B-cell tumors parallels its regulation in non-neoplastic B cells. Therefore, TCL1 expression can be used diagnostically as an indicator of the differentiation stage of a given B-cell tumor.

Inhibition of p53-murine double minute 2 interaction by nutlin-3A stabilizes p53 and induces cell cycle arrest and apoptosis in Hodgkin lymphoma

PURPOSE

p53 is frequently expressed but rarely mutated in Hodgkin and Reed-Sternberg (HRS) cells of Hodgkin's lymphoma (HL). p53 protein levels are regulated by murine double minute 2 (MDM2) through a well-established autoregulatory feedback loop. In this study, we investigated the effects of nutlin-3A, a recently developed small molecule that antagonizes MDM2 and disrupts the p53-MDM2 interaction, on p53-dependent cell cycle arrest and apoptosis in cultured HRS cells.

EXPERIMENTAL DESIGN

HL cell lines carrying wild-type (wt) or mutated p53 gene were treated with the potent MDM2 inhibitor nutlin-3A or a 150-fold less active enantiomer, nutlin-3B.

RESULTS

We show that nutlin-3A, but not nutlin-3B, stabilizes p53 in cultured HRS cells carrying wt p53 gene resulting in p53-dependent cell cycle arrest and apoptosis. Cell cycle arrest was associated with up-regulation of the cyclin-dependent kinase inhibitor p21. Nutlin-3A-induced apoptotic cell death was accompanied by Bax and Puma up-regulation and caspase-3 cleavage and was abrogated, in part, by inhibition of caspase-9 and caspase-3 activity. By contrast, no effects on cell cycle or apoptosis were found in HL cell lines harboring mutated p53 gene. Furthermore, combined treatment with nutlin-3A and doxorubicin revealed enhanced cytotoxicity in HRS cells with wt p53 gene. Blocking of nuclear export by leptomycin B, or inhibition of proteasome by MG132, stabilized p53 at a level comparable with that of nutlin-3A treatment in HRS cells with wt p53.

CONCLUSIONS

These data suggest that nutlin-3A stabilized p53 by preventing MDM2-mediated p53 degradation in HRS cells. wt p53 stabilization and activation by nutlin-3A may be a novel therapeutic approach for patients with HL.

NPM-ALK oncogenic kinase promotes cell-cycle progression through activation of JNK/cJun signaling in anaplastic large-cell lymphoma

Anaplastic large-cell lymphoma (ALCL) frequently carries the t(2;5)(p23;q35), resulting in aberrant expression of nucleophosmin-anaplastic lymphoma kinase (NPM-ALK). We show that in 293T and Jurkat cells, forced expression of active NPM-ALK, but not kinase-dead mutant NPM-ALK (210K>R), induced JNK and cJun phosphorylation, and this was linked to a dramatic increase in AP-1 transcriptional activity. Conversely, inhibition of ALK activity in NPM-ALK(+) ALCL cells resulted in a concentration-dependent dephosphorylation of JNK and cJun and decreased AP-1 DNA-binding. In addition, JNK physically binds NPM-ALK and is highly activated in cultured and primary NPM-ALK(+) ALCL cells. cJun phosphorylation in NPM-ALK(+) ALCL cells is mediated by JNKs, as shown by selective knocking down of JNK1 and JNK2 genes using siRNA. Inhibition of JNK activity using SP600125 decreased cJun phosphorylation and AP-1 transcriptional activity and this was associated with decreased cell proliferation and G2/M cell-cycle arrest in a dose-dependent manner. Silencing of the cJun gene by siRNA led to a decreased S-phase cell-cycle fraction associated with upregulation of p21 and downregulation of cyclin D3 and cyclin A. Taken together, these findings reveal a novel function of NPM-ALK, phosphorylation and activation of JNK and cJun, which may contribute to uncontrolled cell-cycle progression and oncogenesis.

Differential expression of the human MIXL1 gene product in non-Hodgkin and Hodgkin lymphomas

The Mix1 homeobox-like (MIXL1) gene encodes a paired class homeobox transcription factor that is involved in embryogenesis. Previous studies have shown that the MIXL1 gene product is expressed in B- and T-cell progenitors of normal bone marrow and, in some cell lines derived from hematopoietic neoplasms. The status of MIXL1 expression and subcellular localization in human lymphomas is unknown. Using a highly specific antibody, we assessed for MIXL1 expression in lymphoma cell lines of B- and T-cell lineage by reverse transcriptase-polymerase chain reaction, Western blot analysis, and immunohistochemistry. We also assessed for MIXL1 expression using immunohistochemical methods in 193 lymphoid tumors, including 140 B-cell non-Hodgkin lymphomas (NHL), 36 T-cell NHL, and 17 Hodgkin lymphomas (HL). MIXL1 was detected predominantly in the nuclear fraction of all cell lines tested and was predominantly nuclear in primary tumor specimens. Based on the distribution of the staining results (histogram), a 50% cutoff was selected for high versus low MIXL1 expression. High MIXL1 expression was detected more frequently in Burkitt lymphoma and diffuse large B-cell lymphoma compared with other types of B-cell NHL (P < .0001, chi(2) test). Most cases of T-cell NHL and all cases of HL also highly expressed MIXL1. Most plasma cell myelomas were negative for MIXL1, but rare cases had low MIXL1 expression. MIXL1 expression significantly correlated with proliferation index (Ki-67) in B-cell NHL (P < .0001). The frequent and high expression of MIXL1 in aggressive B-cell NHL, T-cell NHL, and HL suggests that MIXL1 may be involved in lymphomagenesis.

c-Jun Expression and Activation are Restricted to CD30+ Lymphoproliferative Disorders

Cellular Jun (c-Jun), a member of the JUN family, is an activator protein-1 transcription factor involved in cell differentiation, proliferation, and apoptosis that can be activated by phosphorylation at serine-73 and -63 residues. Using tissue microarrays and immunohistochemistry, we investigated c-Jun expression and serine-73 phosphorylation in 112 CD30 lymphomas and 232 CD30 lymphomas of B- or T-cell lineage, and 24 cases of lymphomatoid papulosis. c-Jun was expressed exclusively by CD30 lymphoproliferative disorders including 41/41 (100%) classical Hodgkin lymphoma (cHL), 20/23 (87%) anaplastic lymphoma kinase (ALK)+ anaplastic large cell lymphoma (ALCL), 18/26 (69%) ALK- ALCL, 5/9 (56%) primary cutaneous ALCL, 4/11 (36%) CD30 diffuse large B-cell lymphoma (DLBCL), and 11/24 (46%) cases of lymphomatoid papulosis. The percentage of c-Jun-positive tumor cells was highest in cHL and ALCL (P=0.002). In contrast, all CD30 lymphomas, including nodular lymphocyte predominant HL and CD30 non-Hodgkin lymphomas of B- or T-cell lineage were negative for c-Jun. Serine-73 phosphorylated c-Jun (p-c-Jun), the activated form of c-Jun, was expressed more frequently and at a higher level in cHL and ALK+ ALCL than other CD30 tumors. The percentage of p-c-Jun-positive tumor cells correlated significantly with the percentage of total c-Jun-positive cells (P<0.0001), suggesting that activated c-Jun positively regulates total c-Jun levels in CD30 lymphomas through a well-established positive feedback loop. We conclude that CD30 lymphomas are characterized by common patterns of c-Jun expression and activation suggesting a potential role of c-Jun in the pathogenesis of these tumors.

Activation of mammalian target of rapamycin signaling promotes cell cycle progression and protects cells from apoptosis in mantle cell lymphoma

Mantle cell lymphoma (MCL) is characterized by the t(11;14) and cyclin D1 overexpression. However, additional molecular events are most likely required for oncogenesis, possibly through cell cycle and apoptosis deregulation. We hypothesized that mammalian target of rapamycin (mTOR) is activated in MCL and contributes to tumor proliferation and survival. In MCL cell lines, pharmacological inhibition of the phosphoinositide 3-kinase/AKT pathway was associated with decreased phosphorylation (activation) of mTOR and its downstream targets phosphorylated (p)-4E-BP1, p-p70S6 kinase, and p-ribosomal protein S6, resulting in apoptosis and cell cycle arrest. These changes were associated with down-regulation of cyclin D1 and the anti-apoptotic proteins cFLIP, BCL-XL, and MCL-1. Furthermore, silencing of mTOR expression using mTOR-specific short interfering RNA decreased phosphorylation of mTOR signaling proteins and induced cell cycle arrest and apoptosis. Silencing of eukaryotic initiation factor (eIF4E), a downstream effector of mTOR, recapitulated these results. We also assessed mTOR signaling in MCL tumors using immunohistochemical methods and a tissue microarray: 10 of 30 (33%) expressed Ser473p-AKT, 13 of 21 (62%) Ser2448p-mTOR, 22 of 22 (100%) p-p70S6K, and 5 of 20 (25%) p-ribosomal protein S6. Total eIF4E binding protein 1 and eukaryotic initiation factor 4E were expressed in 13 of 14 (93%) and 16 of 29 (55%) MCL tumors, respectively. These findings suggest that the mTOR signaling pathway is activated and may contribute to cell cycle progression and tumor cell survival in MCL.

The t(14;19)(q32;q13)-positive small B-cell leukaemia: a clinicopathologic and cytogenetic study of seven cases

The t(14;19)(q32;q13), involving the BCL3 locus at chromosome 19q13 and the immunoglobulin heavy chain gene at 14q32, is a rare recurrent cytogenetic abnormality identified in B-cell neoplasms, most of which have been classified as chronic lymphocytic leukaemia (CLL) in the literature. We describe the clinicopathological, immunophenotypic and cytogenetic findings in seven patients with B-cell neoplasms associated with t(14;19)(q32;q13). There were five men and two women, with a median age of 48 years (range 33-68). All had absolute lymphocytosis, six had lymphadenopathy, and one had splenomegaly. Lymphocytes in blood and bone marrow aspirate smears were predominantly small and cytologically atypical. Flow cytometric immunophenotyping showed an atypical immunophenotype with low CLL scores. The growth pattern in bone marrow biopsy specimens was interstitial to diffuse; immunohistochemical stains were positive for bcl3 and negative for cyclin D1. Lymph node biopsy specimens of two patients revealed total architectural effacement by neoplasm with proliferation centres. In addition to t(14;19), cytogenetic studies demonstrated trisomy 12 in five patients. These results suggest that B-cell neoplasms with the t(14;19)(q32;q13) present frequently as leukaemia composed of small B-lymphocytes and share many features with CLL. However, these neoplasms also differ from CLL cytologically and in their immunophenotype.

Activation of mammalian target of rapamycin signaling pathway contributes to tumor cell survival in anaplastic lymphoma kinase-positive anaplastic large cell lymphoma

Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL) frequently carries the t(2;5)(p23;q35) resulting in aberrant expression of chimeric nucleophosmin-ALK. Previously, nucleophosmin-ALK has been shown to activate phosphatidylinositol 3-kinase (PI3K) and its downstream effector, the serine/threonine kinase AKT. In this study, we hypothesized that the mammalian target of rapamycin (mTOR) pathway, which functions downstream of AKT, mediates the oncogenic effects of activated PI3K/AKT in ALK+ ALCL. Here, we provide evidence that mTOR signaling phosphoproteins, including mTOR, eukaryotic initiation factor 4E-binding protein-1, p70S6K, and ribosomal protein S6, are highly phosphorylated in ALK+ ALCL cell lines and tumors. We also show that AKT activation contributes to mTOR phosphorylation, at least in part, as forced expression of constitutively active AKT by myristoylated AKT adenovirus results in increased phosphorylation of mTOR and its downstream effectors. Conversely, inhibition of AKT expression or activity results in decreased mTOR phosphorylation. In addition, pharmacologic inhibition of PI3K/AKT down-regulates the activation of the mTOR signaling pathway. We also show that inhibition of mTOR with rapamycin, as well as silencing mTOR gene product expression using mTOR-specific small interfering RNA, decreased phosphorylation of mTOR signaling proteins and induced cell cycle arrest and apoptosis in ALK+ ALCL cells. Cell cycle arrest was associated with modulation of G(1)-S-phase regulators, including the cyclin-dependent kinase inhibitors p21(waf1) and p27(kip1). Apoptosis following inhibition of mTOR expression or function was associated with down-regulation of antiapoptotic proteins, including c-FLIP, MCL-1, and BCL-2. These findings suggest that the mTOR pathway contributes to nucleophosmin-ALK/PI3K/AKT-mediated tumorigenesis and that inhibition of mTOR represents a potential therapeutic strategy in ALK+ ALCL.

Expression of B cell-specific activator protein/PAX5 in acute myeloid leukemia with t(8;21)(q22;q22)

The blasts of acute myeloid leukemia (AML) with t(8;21)(q22;q22) frequently express the B-cell antigen CD19, which is regulated by B cell-specific activator protein (BSAP) encoded by the PAX5 gene, a protein important for B-cell lineage commitment and development. We assessed for BSAP expression in 28 AML cases with t(8;21) and 46 AML cases of other types. CD19 was expressed by 26 (93%) cases of AML with t(8;21) and 1 AML case (2%) without t(8;21). We also tested a subset of cases for the B-cell transcription factors Oct2 and OCA-B (BOB.1) and the B-cell antigens CD20, CD22, and CD79a. Immunostaining performed on bone marrow biopsy specimens demonstrated BSAP expression in all 28 AML cases with t(8;21): weak, 21; strong, 7. By contrast, BSAP was expressed weakly in only 1 AML case without t(8;21). Oct2 was expressed strongly in 12 of 16 AML cases with t(8;21) and 19 of 46 without t(8;21). OCA-B, CD20, CD22, or CD79a were negative in all cases assessed. These results indicate that silencing of PAX5 is not required for commitment to myeloid differentiation and that BSAP expression in AML is found mainly in cases with t(8;21).

Intrinsic apoptotic pathway in anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) includes a subset of tumors that has abnormalities of chromosome 2p23, resulting in overexpression of anaplastic lymphoma kinase (ALK). Previous studies have reported differences in apoptotic rate and expression levels of apoptosis regulatory proteins between ALK+ and ALK- ALCL. In this study, we assessed for expression of the intrinsic apoptotic pathway proteins cytochrome c, apoptosis protease-activating factor 1, and procaspase 9 in 2 ALK+ ALCL cell lines and 42 ALCL tumors (17 ALK+, 25 ALK-). We used the Karpas 299 and SU-DHL-1 cell lines, and the inhibitors Z-LEHD-FMK (specific for caspase 9) and Boc-D-FMK (general caspase inhibitor) to investigate the role of caspase 9 activation in chemotherapy-induced apoptotic cell death. Caspase 9 activity was significantly increased in Karpas-299 and SU-DHL-1 cells after chemotherapy treatment, but remained as low as control levels with addition of either caspase inhibitor. Both caspase inhibitors rescued a substantial fraction of Karpas 299 and SU-DHL-1 cells from drug-induced cell death. In ALCL tumors, expression of cytochrome c, apoptosis protease-activating factor 1, and procaspase 9 was also assessed and correlated with apoptotic rate and activated caspase 3 levels. Cytochrome c was expressed in all 13 (100%) ALK+ and 18 (95%) of 19 ALK- ALCL tumors. Apoptosis protease-activating factor 1 was detected in 14 (88%) of 16 ALK+ and 19 (79%) of 24 ALK- ALCL tumors. Procaspase 9 was expressed in 5 (30%) of 17 ALK+ and 2 (8%) of 25 ALK- ALCL tumors (P = .09). In the entire study group (ALK+ and ALK- ALCL), procaspase 9 expression levels significantly correlated with apoptotic rate (P = .02) and activated caspase 3 levels (P = .05). This correlation could not be shown in the ALK+ or ALK- ALCL subgroups, presumably because of the small sample size. In conclusion, chemotherapy-induced cell death in ALK+ ALCL cells involves the intrinsic apoptotic pathway, and apoptosome function may be an important determinant of apoptosis in ALCL tumors.

Z-138 cell line was derived from a patient with blastoid variant mantle cell lymphoma

The Z-138 cell line, reported in the journal in 1998, was derived from a patient who developed a leukemia initially classified as chronic lymphocytic leukemia in 1987. Splenectomy for massive involvement was required in 1998 and the neoplasm subsequently transformed to an aggressive, mature B-cell leukemia 2 years later. At time of transformation, the neoplasm had a complex karyotype, including the t(11;14)(q13;q32). In light of the extensive updates in lymphoma classification that have occurred since that time, we reviewed the slides of the patient's neoplasm. The initial peripheral blood and bone marrow aspirate smears and the spleen were involved by numerous small lymphocytes with mature chromatin. The last bone marrow specimen was involved by slightly larger, irregular lymphocytes with immature chromatin and a high mitotic rate. Immunohistochemical analysis performed on the spleen and last bone marrow for this report showed that the neoplastic cells over-expressed cyclin D1. According to the criteria of the current World Health Organization lymphoma classification, this neoplasm is best classified as mantle cell lymphoma, with blastoid transformation present in the terminal phase of disease.

53BP1 and p53 synergize to suppress genomic instability and lymphomagenesis

p53-binding protein 1 (53BP1) participates in the cellular response to DNA double-stranded breaks where it associates with various DNA repair/cell cycle factors including the H2AX histone variant. Mice deficient for 53BP1 (53BP1(-/-)) are sensitive to ionizing radiation and immunodeficient because of impaired Ig heavy chain class switch recombination. Here we show that, as compared with p53(-/-) mice, 53BP1(-/-)/p53(-/-) animals more rapidly develop tumors, including T cell lymphomas and, at lower frequency, B lineage lymphomas, sarcomas, and teratomas. In addition, T cells from animals deficient for both 53BP1 and p53 (53BP1(-/-)/p53(-/-)) display elevated levels of genomic instability relative to T cells deficient for either 53BP1 or p53 alone. In contrast to p53(-/-) T cell lymphomas, which routinely display aneuploidy but not translocations, 53BP1(-/-)/p53(-/-) thymic lymphomas fall into two distinct cytogenetic categories, with many harboring clonal translocations (40%) and the remainder showing aneuploidy (60%). We propose that 53BP1, in the context of p53 deficiency, suppresses T cell lymphomagenesis through its roles in both cell-cycle checkpoints and double-stranded break repair.

c-FLIP confers resistance to FAS-mediated apoptosis in anaplastic large-cell lymphoma

We hypothesized that inhibition of the FAS-mediated apoptosis pathway by FLICE-like inhibitory protein (c-FLIP) may contribute to oncogenesis in ALK+ anaplastic large-cell lymphoma (ALCL). Treatment with increasing concentrations of CH-11 (CD95/FAS agonistic antibody) had no effect on cell viability of 2 ALK+ ALCL cell lines, Karpas 299 and SU-DHL1, each expressing high levels of c-FLIP. However, inhibition of endogenous c-FLIP expression by specific c-FLIP siRNA in Karpas 299 and SU-DHL1 cells treated with CH-11 resulted in FAS-mediated cell death associated with increased annexin V binding, apoptotic morphology, and cleavage of caspase-8. In 26 ALK+ ALCL tumors, assessed for expression of DISC-associated proteins, CD95/FAS and c-FLIP were commonly expressed, in 23 (92%) of 25 and 21 (91%) of 23 tumors, respectively. By contrast, CD95L/FASL was expressed in only 3 (12%) of 26 ALCL tumors, although it was strongly expressed by surrounding small reactive lymphocytes. Our findings suggest that overexpression of c-FLIP protects ALK+ ALCL cells from death-receptor-induced apoptosis and may contribute to ALCL pathogenesis.