Prognostic significance of XIAP expression in DLBCL and effect of its inhibition on AKT signalling

Exploiting transcription factors to target EMT and cancer stem cells for tumor modulation and therapy

Transcription factors (TFs) are essential in controlling gene regulatory networks that determine cellular fate during embryogenesis and tumor development. TFs are the major players in promoting cancer stemness by regulating the function of cancer stem cells (CSCs). Understanding how TFs interact with their downstream targets for determining cell fate during embryogenesis and tumor development is a critical area of research. CSCs are increasingly recognized for their significance in tumorigenesis and patient prognosis, as they play a significant role in cancer initiation, progression, metastasis, and treatment resistance. However, traditional therapies have limited effectiveness in eliminating this subset of cells, allowing CSCs to persist and potentially form secondary tumors. Recent studies have revealed that cancer cells and tumors with CSC-like features also exhibit genes related to the epithelial-to-mesenchymal transition (EMT). EMT-associated transcription factors (EMT-TFs) like TWIST and Snail/Slug can upregulate EMT-related genes and reprogram cancer cells into a stem-like phenotype. Importantly, the regulation of EMT-TFs, particularly through post-translational modifications (PTMs), plays a significant role in cancer metastasis and the acquisition of stem cell-like features. PTMs, including phosphorylation, ubiquitination, and SUMOylation, can alter the stability, localization, and activity of EMT-TFs, thereby modulating their ability to drive EMT and stemness properties in cancer cells. Although targeting EMT-TFs holds potential in tackling CSCs, current pharmacological approaches to do so directly are unavailable. Therefore, this review aims to explore the role of EMT- and CSC-TFs, their connection and impact in cellular development and cancer, emphasizing the potential of TF networks as targets for therapeutic intervention.

In vitro evaluation of Neosetophomone B inducing apoptosis in cutaneous T cell lymphoma by targeting the FOXM1 signaling pathway

BACKGROUND

Cutaneous T cell lymphoma (CTCL) is a T cell-derived non-Hodgkin lymphoma primarily affecting the skin, with treatment posing a significant challenge and low survival rates.

OBJECTIVE

In this study, we investigated the anti-cancer potential of Neosetophomone B (NSP-B), a fungal-derived secondary metabolite, on CTCL cell lines H9 and HH.

METHODS

Cell viability was measured using Cell counting Kit-8 (CCK8) assays. Apoptosis was measured by annexin V/PI dual staining. Immunoblotting was performed to examine the expression of proteins. Applied Biosystems' high-resolution Human Transcriptome Array 2.0 was used to examine gene expression.

RESULTS

NSP-B induced apoptosis in CTCL cells by activating mitochondrial signaling pathways and caspases. We observed downregulated expression of BUB1B, Aurora Kinases A and B, cyclin-dependent kinases (CDKs) 4 and 6, and polo-like kinase 1 (PLK1) in NSP-B treated cells, which was further corroborated by Western blot analysis. Notably, higher expression levels of these genes showed reduced overall and progression-free survival in the CTCL patient cohort. FOXM1 and BUB1B expression exhibited a dose-dependent reduction in NSP-B-treated CTCL cells.FOXM1 silencing decreased cell viability and increased apoptosis via BUB1B downregulation. Moreover, NSP-B suppressed FOXM1-regulated genes, such as Aurora Kinases A and B, CDKs 4 and 6, and PLK1. The combined treatment of Bortezomib and NSP-B showed greater efficacy in reducing CTCL cell viability and promoting apoptosis compared to either treatment alone.

CONCLUSION

Our findings suggest that targeting the FOXM1 pathway may provide a promising therapeutic strategy for CTCL management, with NSP-B offering significant potential as a novel treatment option.

The role of microRNA-induced apoptosis in diverse radioresistant cancers

Resistance to cancer radiotherapy is one of the biggest concerns for success in treating and preventing recurrent disease. Malignant tumors may develop when they block genetic mutations associated with apoptosis or abnormal expression of apoptosis; Tumor treatment may induce the expression of apoptosis-related genes to promote tumor cell apoptosis. MicroRNAs have been shown to contribute to forecasting prognosis, distinguishing between cancer subtypes, and affecting treatment outcomes in cancer. Constraining these miRNAs may be an attractive treatment strategy to help overcome radiation resistance. The delivery of these future treatments is still challenging due to the excess downstream targets that each miRNA can control. Understanding the role of miRNAs brings us one step closer to attaining patient treatment and improving patient outcomes. This review summarized the current information on the role of microRNA-induced apoptosis in determining the radiosensitivity of various cancers.

Subcellular localization of X-linked inhibitor of apoptosis protein (XIAP) in cancer: does that matter?

X-linked inhibitor of apoptosis protein (XIAP) finely tunes the balance between survival and death to control homeostasis. XIAP is found aberrantly expressed in cancer, which has been shown to promote resistance to therapy-induced apoptosis and confer poor outcome. Despite its predominant cytoplasmic localization in human tissues, growing evidence implicates the expression of XIAP in other subcellular compartments in sustaining cancer hallmarks. Herein, we review our current knowledge on the prognostic role of XIAP localization and discuss molecular mechanisms underlying differential biological functions played in each compartment. The comprehension of XIAP subcellular shuttling and functional dynamics might provide the rationale for future anticancer therapeutics.

Prognostic molecular biomarkers in diffuse large B-cell lymphoma in the rituximab era and their therapeutic implications

Diffuse large B-cell lymphoma (DLBCL) represents a group of tumors characterized by substantial heterogeneity in terms of their pathological and biological features, a causal factor of their varied clinical outcome. This variation has persisted despite the implementation of rituximab in treatment regimens over the last 20 years. In this context, prognostic biomarkers are of great importance in order to identify high-risk patients that might benefit from treatment intensification or the introduction of novel therapeutic agents. Herein, we review current knowledge on specific immunohistochemical or genetic biomarkers that might be useful in clinical practice. Gene-expression profiling is a tool of special consideration in this effort, as it has enriched our understanding of DLBCL biology and has allowed for the classification of DLBCL by cell-of-origin as well as by more elaborate molecular signatures based on distinct gene-expression profiles. These subgroups might outperform individual biomarkers in terms of prognostication; however, their use in clinical practice is still limited. Moreover, the underappreciated role of the tumor microenvironment in DLBCL prognosis is discussed in terms of prognostic gene-expression signatures, as well as in terms of individual biomarkers of prognostic significance. Finally, the efficacy of novel therapeutic agents for the treatment of DLBCL patients are discussed and an evidence-based therapeutic approach by specific genetic subgroup is suggested.

Genetic Events Inhibiting Apoptosis in Diffuse Large B Cell Lymphoma

Simple Summary

Diffuse large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL). Despite the genetic heterogeneity of the disease, most patients are initially treated with a combination of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), but relapse occurs in ~50% of patients. One of the hallmarks of DLBCL is the occurrence of genetic events that inhibit apoptosis, which contributes to disease development and resistance to therapy. These events can affect the intrinsic or extrinsic apoptotic pathways, or their modulators. Understanding the factors that contribute to inhibition of apoptosis in DLBCL is crucial in order to be able to develop targeted therapies and improve outcomes, particularly in relapsed and refractory DLBCL (rrDLBCL). This review provides a description of the genetic events inhibiting apoptosis in DLBCL, their contribution to lymphomagenesis and chemoresistance, and their implication for the future of DLBCL therapy.

Abstract

Diffuse large B cell lymphoma (DLBCL) is curable with chemoimmunotherapy in ~65% of patients. One of the hallmarks of the pathogenesis and resistance to therapy in DLBCL is inhibition of apoptosis, which allows malignant cells to survive and acquire further alterations. Inhibition of apoptosis can be the result of genetic events inhibiting the intrinsic or extrinsic apoptotic pathways, as well as their modulators, such as the inhibitor of apoptosis proteins, P53, and components of the NF-kB pathway. Mechanisms of dysregulation include upregulation of anti-apoptotic proteins and downregulation of pro-apoptotic proteins via point mutations, amplifications, deletions, translocations, and influences of other proteins. Understanding the factors contributing to resistance to apoptosis in DLBCL is crucial in order to be able to develop targeted therapies that could improve outcomes by restoring apoptosis in malignant cells. This review describes the genetic events inhibiting apoptosis in DLBCL, provides a perspective of their interactions in lymphomagenesis, and discusses their implication for the future of DLBCL therapy.

Proteasome inhibitors and Smac mimetics cooperate to induce cell death in diffuse large B-cell lymphoma by stabilizing NOXA and triggering mitochondrial apoptosis

Copy number gains and increased expression levels of cellular Inhibitor of Apoptosis protein (cIAP)1 and cIAP2 have been identified in primary diffuse large B-cell lymphoma (DLBCL) tissues. Second mitochondria-derived activator of caspases (Smac) mimetics were designed to antagonize IAP proteins. However, since their effect as single agents is limited, combination treatment represents a strategy for their clinical development. Therefore, we investigated the Smac mimetic BV6 in combination with proteasome inhibitors and analyzed the molecular mechanisms of action. We discovered that BV6 treatment sensitizes DLBCL cells to proteasome inhibition. We show a synergistic decrease in cell viability and induction of apoptosis by BV6/Carfilzomib (CFZ) treatment, which was confirmed by calculation of combination index (CI) and Bliss score. BV6 and CFZ acted together to trigger activation of BAX and BAK, which facilitated cell death, as knockdown of BAX and BAK significantly reduced BV6/CFZ-mediated cell death. Activation of BAX and BAK was accompanied by loss of mitochondrial membrane potential (MMP) and activation of caspases. Pretreatment with the caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) rescued BV6/CFZ-induced cell death, confirming caspase dependency. Treatment with CFZ alone or in combination with BV6 caused accumulation of NOXA, which was required for cell death, as gene silencing by siRNA or Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9-mediated NOXA inactivation inhibited BV6/CFZ-induced cell death. Together, these experiments indicate that BV6 and CFZ cooperatively induce apoptotic cell death via the mitochondrial pathway. These findings emphasize the role of Smac mimetics for sensitizing DLBCL cells to proteasome inhibition with important implications for further (pre)clinical studies.

Akt1 and Jak1 siRNA based silencing effects on the proliferation and apoptosis in head and neck squamous cell carcinoma

Based on Akt1 and Jak1 key roles in apoptosis and proliferation of many cancers, the aim of this study was to find a new gene therapy strategy by silencing of these main anti-apoptotic genes for HNSCC treatment. Cancerous HN5 and normal HUVEC cell lines were treated with Akt1 and Jak1 siRNAs alone or with each other combined with/without cisplatin. The MTS, flow cytometry, 4',6-diamidino-2-phenylindole staining, real-time PCR and ELISA methods were utilized in this study. The highest percentage of apoptosis was observed in the treatment of Jak1 siRNA/cisplatin group in cancerous HN5 cells (96.5%) where this treatment showed 12.84% apoptosis in normal HUVEC cell line. Cell viability reduced significantly to 64.57% after treatment with Akt1 siRNA in HN5 treated group. Knocking down Akt1 and Jak1 genes using siRNAs could increase levels of apoptosis and reduce proliferation rate in HNSCC indicating the powerful effects of these genes siRNAs with or without chemotherapeutic agents in HNSCC treatment. In conclusion, the combination of siRNA-mediated gene-silencing strategy can be considered as a valuable and safe approach for sensitizing cancer cells to chemotherapeutic agents thus proposed further studies regarding this issue to approve some siRNA based therapeutics for using in clinic.

Dysregulation of Cell Survival in Diffuse Large B Cell Lymphoma: Mechanisms and Therapeutic Targets

Diffuse large B cell lymphoma (DLBCL) is the most common type of lymphoma worldwide, representing 30-40% of non-Hodgkin lymphomas, and is clinically aggressive. Although more than half of patients with DLBCL are cured by using standard first-line immunochemotherapy, the remaining patients are refractory to the first-line therapy or relapse after complete remission and these patients require novel therapeutic approaches. Understanding the pathogenesis of DLBCL is essential for identifying therapeutic targets to tackle this disease. Cell survival dysregulation, a hallmark of cancer, is a characteristic feature of DLBCL. Intrinsic signaling aberrations, tumor microenvironment dysfunction, and viral factors can all contribute to the cell survival dysregulation in DLBCL. In recent years, several novel drugs that target abnormal cell survival pathways, have been developed and tested in clinical trials of patients with DLBCL. In this review, we discuss cell survival dysregulation, the underlying mechanisms, and how to target abnormal cell survival therapeutically in DLBCL patients.

Overexpression of PARP is an independent prognostic marker for poor survival in Middle Eastern breast cancer and its inhibition can be enhanced with embelin co-treatment

Patients with aggressive breast cancer (BC) subtypes usually don’t have favorable prognosis despite the improvement in treatment modalities. These cancers still remain a major cause of morbidity and mortality in females. This has fostered a major effort to discover actionable molecular targets to treat these patients. Poly ADP ribose polymerase (PARP) is one of these molecular targets that are under comprehensive investigation for treatment of such tumors. However, its role in the pathogenesis of BC from Middle Eastern ethnicity has not yet been explored. Therefore, we examined the expression of PARP protein in a large cohort of over 1000 Middle Eastern BC cases by immunohistochemistry. Correlation with clinico-pathological parameters were performed. Nuclear PARP overexpression was observed in 44.7% of all BC cases and was significantly associated with aggressive clinico-pathological markers. Interestingly, nuclear PARP overexpression was an independent predictor of poor prognosis. PARP overexpression was also directly associated with XIAP overexpression, with PARP and XIAP co-expression in 15.8% (159/1008) of our cases. We showed that combined inhibition of PARP by olaparib and XIAP by embelin significantly and synergistically inhibited cell growth and induced apoptosis in BC cell lines. Finally, co-treatment of olaparib and embelin regressed BC xenograft tumor growth in nude mice. Our results revealed the role of PARP in Middle Eastern BC pathogenesis and prognosis. Furthermore, our data support the potential clinical development of combined inhibition of PARP and XIAP, which eventually could extend the utility of olaparib beyond BRCA deficient cancer.

Study on the expression of p53 and MMP-2 in patients with lung cancer after interventional therapy

The aim of the study was to investigate the expression of tumor suppressor gene p53 and MMP-9 in non-small cell lung cancer (NSCLC) before and after chemotherapy, and investigate its association with the effect of chemotherapy and prognosis. Fifty-eight elderly NSCLC patients comprised the observation group. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of p53 and MMP-9 in lung cancer tissues before and after chemotherapy. Immunohistochemistry and western blot analysis were used to detect the expression of p53 and MMP-9 proteins in NSCLC tissue before and after chemotherapy. Terminal deoxynucleotidyl transferase nick end-labeling (TUNEL) was used to detect apoptotic cells. The association between the effect of chemotherapy and the expression of p53 and MMP-9 in lung cancer tissues was analysed. RT-qPCR results showed that the expression of p53 and MMP-2 mRNA in the tumor tissue after chemotherapy was significantly lower than that in the tumor tissue before chemotherapy. Western blot analysis revealed that the expression of p53 and MMP-2 protein in the tumor tissue after chemotherapy was significantly decreased. The positive expression of p53 and MMP-2 in lung cancer tissues before chemotherapy was 76.25 and 71.25%, respectively, and were reduced to 27.50 and 23.75%, respectively, after chemotherapy. After chemotherapy, the positive rates of p53 and MMP-2 were significantly lower than those before chemotherapy. TUNEL results showed that the apoptosis index increased significantly after chemotherapy. Efficiency of chemotherapy in patients with a negative expression of p53 and MMP-2 in lung cancer before chemotherapy was significantly higher than that in patients with a positive p53 and MMP-2 expression. A significant difference was found in the expression levels of p53 and MMP-2 in lung cancer before and after chemotherapy. The findings of the present study indicate that the expression levels of p53 and MMP-2 can be used as a predictor of chemotherapy sensitivity.

ASTX660, a Novel Non-peptidomimetic Antagonist of cIAP1/2 and XIAP, Potently Induces TNFα-Dependent Apoptosis in Cancer Cell Lines and Inhibits Tumor Growth

Because of their roles in the evasion of apoptosis, inhibitor of apoptosis proteins (IAP) are considered attractive targets for anticancer therapy. Antagonists of these proteins have the potential to switch prosurvival signaling pathways in cancer cells toward cell death. Various SMAC-peptidomimetics with inherent cIAP selectivity have been tested clinically and demonstrated minimal single-agent efficacy. ASTX660 is a potent, non-peptidomimetic antagonist of cIAP1/2 and XIAP, discovered using fragment-based drug design. The antagonism of XIAP and cIAP1 by ASTX660 was demonstrated on purified proteins, cells, and in vivo in xenograft models. The compound binds to the isolated BIR3 domains of both XIAP and cIAP1 with nanomolar potencies. In cells and xenograft tissue, direct antagonism of XIAP was demonstrated by measuring its displacement from caspase-9 or SMAC. Compound-induced proteasomal degradation of cIAP1 and 2, resulting in downstream effects of NIK stabilization and activation of noncanonical NF-κB signaling, demonstrated cIAP1/2 antagonism. Treatment with ASTX660 led to TNFα-dependent induction of apoptosis in various cancer cell lines in vitro, whereas dosing in mice bearing breast and melanoma tumor xenografts inhibited tumor growth. ASTX660 is currently being tested in a phase I-II clinical trial (NCT02503423), and we propose that its antagonism of cIAP1/2 and XIAP may offer improved efficacy over first-generation antagonists that are more cIAP1/2 selective. Mol Cancer Ther; 17(7); 1381-91. ©2018 AACR.

Embelin: a benzoquinone possesses therapeutic potential for the treatment of human cancer

Natural products have been gaining recognition and are becoming a significant part of research in the area of drug development and discovery. Phytochemicals derived from these sources have been comprehensively studied and have displayed a wide range of activities against many fatal diseases including cancer. One such product that has gained recognition from its pharmacological properties and nontoxic nature is embelin, obtained from Embelia ribes. Amid all the vivid pharmacological activities, embelin has gained its prominence in the area of cancer research. Embelin binds to the BIR3 domain of XIAP, preventing the association of XIAP and caspase-9 resulting in the suppression of cell growth, proliferation and migration of various types of cancer cells. Furthermore, embelin modulates anti-apoptotic pathways by suppressing the activity of NF-κB, PI3-kinase/AKT, JAK/STAT pathway - among others. The present review summarizes the various reported effects of embelin on different types of cancer cells and highlights the cellular mechanisms of action.

Overcoming chemotherapy drug resistance by targeting inhibitors of apoptosis proteins (IAPs)

Inhibitors of apoptosis (IAPs) are a family of proteins that play a significant role in the control of programmed cell death (PCD). PCD is essential to maintain healthy cell turnover within tissue but also to fight disease or infection. Uninhibited, IAPs can suppress apoptosis and promote cell cycle progression. Therefore, it is unsurprising that cancer cells demonstrate significantly elevated expression levels of IAPs, resulting in improved cell survival, enhanced tumor growth and subsequent metastasis. Therapies to target IAPs in cancer has garnered substantial scientific interest and as resistance to anti-cancer agents becomes more prevalent, targeting IAPs has become an increasingly attractive strategy to re-sensitize cancer cells to chemotherapies, antibody based-therapies and TRAIL therapy. Antagonism strategies to modulate the actions of XIAP, cIAP1/2 and survivin are the central focus of current research and this review highlights advances within this field with particular emphasis upon the development and specificity of second mitochondria-derived activator of caspase (SMAC) mimetics (synthetic analogs of endogenously expressed inhibitors of IAPs SMAC/DIABLO). While we highlight the potential of SMAC mimetics as effective single agent or combinatory therapies to treat cancer we also discuss the likely clinical implications of resistance to SMAC mimetic therapy, occasionally observed in cancer cell lines.

The Application of Embelin for Cancer Prevention and Therapy

Embelin is a naturally-occurring benzoquinone compound that has been shown to possess many biological properties relevant to human cancer prevention and treatment, and increasing evidence indicates that embelin may modulate various characteristic hallmarks of tumor cells. This review summarizes the information related to the various oncogenic pathways that mediate embelin-induced cell death in multiple cancer cells. The mechanisms of the action of embelin are numerous, and most of them induce apoptotic cell death that may be intrinsic or extrinsic, and modulate the NF-κB, p53, PI3K/AKT, and STAT3 signaling pathways. Embelin also induces autophagy in cancer cells; however, these autophagic cell-death mechanisms of embelin have been less reported than the apoptotic ones. Recently, several autophagy-inducing agents have been used in the treatment of different human cancers, although they require further exploration before being transferred from the bench to the clinic. Therefore, embelin could be used as a potential agent for cancer therapy.

XIAP over-expression is an independent poor prognostic marker in Middle Eastern breast cancer and can be targeted to induce efficient apoptosis

Background

Breast cancer is the most common cancer in females and is ranked second in cancer-related deaths all over the world in women. Despite improvement in diagnosis, the survival rate of this disease has still not improved. X-linked Inhibitor of Apoptosis (XIAP) has been shown to be over-expressed in various cancers leading to poor overall survival. However, the role of XIAP in breast cancer from Middle Eastern region has not been fully explored.

Methods

We examined the expression of XIAP in more than 1000 Middle Eastern breast cancer cases by immunohistochemistry. Apoptosis was measured by flow cytometry. Protein expression was determined by western blotting. Finally, in vivo studies were performed on nude mice following xenografting and treatment with inhibitors.

Results

XIAP was found to be over-expressed in 29.5% of cases and directly associated with clinical parameters such as tumor size, extra nodal extension, triple negative breast cancer and poorly differentiated breast cancer subtype. In addition, XIAP over-expression was also significantly associated with PI3-kinase pathway protein; p-AKT, proliferative marker; Ki-67 and anti-apoptotic marker; PARP. XIAP over-expression in our cohort of breast cancer was an independent poor prognostic marker in multivariate analysis. Next, we investigated inhibition of XIAP using a specific inhibitor; embelin and found that embelin treatment led to inhibition of cell viability and induction of apoptosis in breast cancer cells. Finally, breast cancer cells treated with combination of embelin and PI3-kinase inhibitor; LY294002 synergistically induced apoptosis and caused tumor growth regression in vivo.

Conclusion

These data suggest that XIAP may be playing an important role in the pathogenesis of breast cancer and can be therapeutically targeted either alone or in combination with PI3-kinase inhibition to induce efficient apoptosis in breast cancer cells.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3627-4) contains supplementary material, which is available to authorized users.

Apoptosis signaling and BCL-2 pathways provide opportunities for novel targeted therapeutic strategies in hematologic malignances

Apoptosis is an essential biological process involved in tissue homeostasis and immunity. Aberrations of the two main apoptotic pathways, extrinsic and intrinsic, have been identified in hematological malignancies; many of these aberrations are associated with pathogenesis, prognosis and resistance to standard chemotherapeutic agents. Targeting components of the apoptotic pathways, especially the chief regulatory BCL-2 family in the intrinsic pathway, has proved to be a promising therapeutic approach for patients with hematological malignances, with the expectation of enhanced efficacy and reduced adverse events. Continuous investigations regarding the biological importance of each of the BCL-2 family components and the clinical rationale to achieve optimal therapeutic outcomes, using either monotherapy or in combination with other targeted agents, have generated inspiring progress in the field. Genomic, epigenomic and biological analyses including BH3 profiling facilitate effective evaluation of treatment response, cancer recurrence and drug resistance. In this review, we summarize the biological features of each of the components in the BCL-2 apoptotic pathways, analyze the regulatory mechanisms and the pivotal roles of BCL-2 family members in the pathogenesis of major types of hematologic malignances, and evaluate the potential of apoptosis- and BCL-2-targeted strategies as effective approaches in anti-cancer therapies.

Relationship of the expression levels of XIAP and p53 genes in hepatocellular carcinoma and the prognosis of patients

In this study, we measured mRNA and protein expression levels of X-linked inhibitor of apoptosis protein (XIAP) and p53 in hepatocellular carcinoma (HCC) and analyzed their relationships to clinicopathological parameters and the prognosis of the patients. Samples were obtained from tumors and tumor-adjacent normal tissues from 70 patients with HCC who were hospitalized in Weifang People's Hospital from January 2009 to December 2011. Quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) were used to detect the mRNA and protein expression levels, respectively. The clinical data of patients who were followed for 5 years from the day of the tumor-resection surgery were collected in detailed clinical histories. Statistical analyses were used to find relationships between the XIAP and p53 levels and the clinical variables and 5-year survival of patients. Our qPCR results showed that the mRNA expression levels of XIAP and p53 in HCC tumors were significantly higher than those in tumor-adjacent normal tissues. At the same time, IHC results showed that the positive expression rates of XIAP and p53 in HCC in tumors were 81.4% (57/70) and 72.9% (51/70), respectively and their high expression was related to invasion, metastasis and tumor staging. The overall 5-year survival rate of the patients was 15.7% (11/70). Single factor survival analysis showed that both XIAP and p53 were influencing factors of the overall survival rate of patients with HCC (P<0.01). In conclusion, high expression levels of XIAP and p53 are closely related to clinicopathological parameters of patients with HCC, especially related to invasion, metastasis and tumor staging. XIAP and p53 levels can be used as reference values to guide the treatment of HCC and estimate the prognosis.

Targeting of X-linked inhibitor of apoptosis protein and PI3-kinase/AKT signaling by embelin suppresses growth of leukemic cells

The X-linked inhibitor of apoptosis (XIAP) is a viable molecular target for anticancer drugs that overcome apoptosis-resistance of malignant cells. XIAP is an inhibitor of apoptosis, mediating through its association with BIR3 domain of caspase 9. Embelin, a quinone derivative isolated from the Embelia ribes plant, has been shown to exhibit chemopreventive, anti-inflammatory, and apoptotic activities via inhibiting XIAP activity. In this study, we found that embelin causes a dose-dependent suppression of proliferation in leukemic cell lines K562 and U937. Embelin mediated inhibition of proliferation correlates with induction of apoptosis. Furthermore, embelin treatment causes loss of mitochondrial membrane potential and release of cytochrome c, resulting in subsequent activation of caspase-3 followed by polyadenosin-5’-diphosphate-ribose polymerase (PARP) cleavage. In addition, embelin treatment of leukemic cells results in a decrease of constitutive phosphorylations/activation level of AKT and downregulation of XIAP. Gene silencing of XIAP and AKT expression showed a link between XIAP expression and activated AKT in leukemic cells. Interestingly, targeting of XIAP and PI3-kinase/AKT signaling augmented inhibition of proliferation and induction of apoptosis in leukemic cells. Altogether these findings raise the possibility that embelin alone or in combination with inhibitors of PI3-kinase/AKT pathway may have therapeutic usage in leukemia and possibly other malignancies with up-regulated XIAP pathway.

Novel prognostic genes of diffuse large B-cell lymphoma revealed by survival analysis of gene expression data

Objective

This study aimed to identify prognostic genes for diffuse large B-cell lymphoma (DLBCL), using bioinformatic methods.

Methods

Five gene expression data sets were downloaded from the Gene Expression Omnibus database. Significance analysis of microarrays algorithm was used to identify differentially expressed genes (DEGs) from two data sets. Functional enrichment analysis was performed for the DEGs with the Database for Annotation, Visualization and Integration Discovery (DAVID). Survival analysis was performed with the Kaplan–Meier method using function survfit from package survival of R for the other three data sets. Cox univariate regression analysis was used to further screen out prognostic genes.

Results

Thirty-one common DEGs were identified in the two data sets, mainly enriched in the regulation of lymphocyte activation, immune response, and interleukin-mediated signaling pathway. Combined with 47 DLBCL-related genes acquired by literature retrieval, a total of 78 potential prognostic genes were obtained. Cases from the other three data sets were used in hierarchical clustering, and the 78 genes could cluster them into several subtypes with significant differences in survival curves. Cox univariate regression analysis revealed 45, 33, and eleven prognostic genes in the three data sets, respectively. Five common prognostic genes were revealed, including LCP2, TNFRSF9, FUT8, IRF4, and TLE1, among which LCP2, FUT8, and TLE1 were novel prognostic genes.

Conclusion

Five prognostic genes of DLBCL were identified in this study. They could not only be used for molecular subtyping of DLBCL but also be potential targets for treatment.

XIAP and cIAP1 amplifications induce Beclin 1-dependent autophagy through NFκB activation

Perturbations in autophagy and apoptosis are associated with cancer development. XIAP and cIAP1 are two members of the inhibitors of apoptosis protein family whose expression is elevated in different cancers. Here we report that XIAP and cIAP1 induce autophagy by upregulating the transcription of Beclin 1, an essential autophagy gene. The E3 ubiquitin ligase activity of both proteins activates NFκB signalling, leading to the direct binding of p65 to the promoter of Beclin 1 and to its transcriptional activation. This mechanism may be relevant in cancer cells, since we found increased levels of autophagy in different B-cell lymphoma-derived cell lines where XIAP is overexpressed and pharmacological inhibition of XIAP in these cell lines reduced autophagosome biogenesis. Thus, the chemotherapy resistance associated with XIAP and cIAP1 overexpression observed in several human cancers may be, at least in part, due to the Beclin 1-dependent autophagy activation by IAPs described in this study. In this context, the disruption of this increased autophagy might represent a valuable pharmacological tool to be included in combined anti-neoplastic therapies.

Individualized medicine enabled by genomics in Saudi Arabia

The biomedical research sector in Saudi Arabia has recently received special attention from the government, which is currently supporting research aimed at improving the understanding and treatment of common diseases afflicting Saudi Arabian society. To build capacity for research and training, a number of centres of excellence were established in different areas of the country. Among these, is the Centre of Excellence in Genomic Medicine Research (CEGMR) at King Abdulaziz University, Jeddah, with its internationally ranked and highly productive team performing translational research in the area of individualized medicine. Here, we present a panorama of the recent trends in different areas of biomedical research in Saudi Arabia drawing from our vision of where genomics will have maximal impact in the Kingdom of Saudi Arabia. We describe advances in a number of research areas including; congenital malformations, infertility, consanguinity and pre-implantation genetic diagnosis, cancer and genomic classifications in Saudi Arabia, epigenetic explanations of idiopathic disease, and pharmacogenomics and personalized medicine. We conclude that CEGMR will continue to play a pivotal role in advances in the field of genomics and research in this area is facing a number of challenges including generating high quality control data from Saudi population and policies for using these data need to comply with the international set up.

Targeting the apoptosis pathway in hematologic malignancies

Apoptosis is a cell death program that is well-orchestrated for normal tissue homeostasis and for removal of damaged, old or infected cells. It is regulated by intrinsic and extrinsic pathways. The intrinsic pathway responds to signals such as ultraviolet radiation or DNA damage and activates "executioner" caspases through a mitochondria-dependent pathway. The extrinsic pathway is activated by death signals induced, for example, by an infection that activates the immune system or receptor-mediated pathways. The extrinsic pathway signals also cascade down to executioner caspases that cleave target proteins and lead to cell death. Strict control of cellular apoptosis is important for the hematopoietic system as it has a high turnover rate. However, the apoptosis program is often deregulated in hematologic malignancies leading to the accumulation of malignant cells. Therefore, apoptosis pathways have been identified for the development of anticancer therapeutics. We review here the proteins that have been targeted for anticancer drug development in hematologic malignancies. These include BCL-2 family proteins, death ligands and receptors, inhibitor of apoptosis family proteins and caspases. Except for caspase activators, drugs that target each of these classes of proteins have advanced into clinical trials.

Inhibitor of Apoptosis (IAP) proteins in hematological malignancies: molecular mechanisms and therapeutic opportunities

Inhibitor of Apoptosis (IAP) proteins exert essential functions during tumorigenesis as well as treatment resistance by simultaneously blocking cell death pathways and promoting cell survival. As IAP proteins are typically aberrantly expressed in human cancers including hematological malignancies, they represent in principle promising targets for therapeutic interventions. There are currently exciting opportunities to rationally exploit the therapeutic targeting of IAP proteins for the treatment of leukemia and lymphoma. Further insights into the signaling pathways that are under the control of IAP proteins and into the specific IAP protein-dependent vulnerabilities of hematological neoplasms are expected to pave the avenue to novel treatment strategies.

Activation of p38/JNK pathway is responsible for embelin induced apoptosis in lung cancer cells: transitional role of reactive oxygen species

The natural product embelin has been demonstrated to possess a wide range of therapeutic properties, however, the mechanisms by which it exerts anticancer effects are not yet clear. By monitoring the molecular changes associated during early apoptotic phase, we have identified the crucial role of oxidative stress induced MAP kinase signalling as a predominant mechanism for its anticancer effects. Treatment of A549 lung cancer cells with embelin resulted in the enhancement of phospho-p38 and phospho-JNK levels as early as 4h. Pretreatment of cells with specific inhibitors of p38 (PD169316) and JNK (SP600125) abrogated embelin-induced caspase-3 activation. Studies employing embelin in the presence or absence of specific MAP kinase inhibitors indicated that the observed changes in phosphorylation levels of p38, JNK and ERK 1/2 are solely due to embelin and not because of cross-talk between MAP kinases. Reactive oxygen species (ROS) play a crucial role in embelin induced alterations in MAP kinase phosphorylation and apoptosis as pretreatment of cells with FeTMPyP mitigated this effect. The observed changes are not due to the inhibitory effect of embelin on XIAP as cells treated with SMAC-N7-Ant peptide, a specific inhibitor of XIAP’s BIR3 domain did not mimic embelin induced apoptotic effects. The findings of the present study clearly indicate the crucial role of p38 and JNK pathways in embelin induced apoptosis and provide us with new clues for improving its therapeutic efficacy.

IAP proteins as targets for drug development in oncology

The inhibitors of apoptosis (IAPs) constitute a family of proteins involved in the regulation of various cellular processes, including cell death, immune and inflammatory responses, cell proliferation, cell differentiation, and cell motility. There is accumulating evidence supporting IAP-targeting in tumors: IAPs regulate various cellular processes that contribute to tumor development, such as cell death, cell proliferation, and cell migration; their expression is increased in a number of human tumor samples, and IAP overexpression has been correlated with tumor growth, and poor prognosis or low response to treatment; and IAP expression can be rapidly induced in response to chemotherapy or radiotherapy because of the presence of an internal ribosome entry site (IRES)-dependent mechanism of translation initiation, which could contribute to resistance to antitumor therapy. The development of IAP antagonists is an important challenge and was subject to intense research over the past decade. Six molecules are currently in clinical trials. This review focuses on the role of IAPs in tumors and the development of IAP-targeting molecules for anticancer therapy.

XIAP antisense therapy with AEG 35156 in acute myeloid leukemia

INTRODUCTION

AEG 35156 is an antisense oligonucleotide to X-linked inhibitor of apoptosis protein (XIAP). Overexpression of XIAP is common in acute myeloid leukemia (AML) and other cancers and is thought to cause resistance to cancer therapy. Effective treatment options for patients with relapsed or refractory AML are limited and survival continues to be poor. Targeting resistance mechanisms is expected to improve results in relapsed as well as front-line settings.

AREAS COVERED

Role of XIAP in apoptosis pathways, structure of AEG 35156, mechanism of action, pharmacokinetics and pharmacodynamics, clinical efficacy and review of clinical trials in AML.

EXPERT OPINION

AEG 35156 in combination with standard chemotherapy was generally very well-tolerated and had shown some evidence of anti-leukemic activity in AML. The target knock down was transient and has not always correlated with response. Future studies may be done with variations in dose scheduling and with more emphasis on comprehensive pharmacodynamic studies simultaneously analyzing other inhibitor of apoptosis proteins (IAPs) and various XIAP regulators. Use of small molecule mimetics of second mitochondria derived activator of caspases (Smac) simultaneously targeting other IAPs appears to be an attractive option.

Targeted apoptotic effects of thymoquinone and tamoxifen on XIAP mediated Akt regulation in breast cancer

X-linked inhibitor of apoptosis protein (XIAP) is constitutively expressed endogenous inhibitor of apoptosis, exhibit its antiapoptotic effect by inactivating key caspases such as caspase-3, caspase-7 and caspase-9 and also play pivotal role in rendering cancer chemoresistance. Our studies showed the coadministration of TQ and TAM resulting in a substantial increase in breast cancer cell apoptosis and marked inhibition of cell growth both in vitro and in vivo. Anti-angiogenic and anti-invasive potential of TQ and TAM was assessed through in vitro studies. This novel combinatorial regimen leads to regulation of multiple cell signaling targets including inactivation of Akt and XIAP degradation. At molecular level, TQ and TAM synergistically lowers XIAP expression resulting in binding and activation of caspase-9 in apoptotic cascade, and interfere with cell survival through PI3-K/Akt pathway by inhibiting Akt phosphorylation. Cleaved caspase-9 further processes other intracellular death substrates such as PARP thereby shifting the balance from survival to apoptosis, indicated by rise in the sub-G₁ cell population. This combination also downregulates the expression of Akt-regulated downstream effectors such as Bcl-xL, Bcl-2 and induce expression of Bax, AIF, cytochrome C and p-27. Consistent with these results, overexpression studies further confirmed the involvement of XIAP and its regulatory action on Akt phosphorylation along with procaspase-9 and PARP cleavage in TQ-TAM coadministrated induced apoptosis. The ability of TQ and TAM in inhibiting XIAP was confirmed through siRNA-XIAP cotransfection studies. This novel modality may be a promising tool in breast cancer treatment.

Embelin inhibits growth and induces apoptosis through the suppression of Akt/mTOR/S6K1 signaling cascades

BACKGROUND

Akt/mTOR/S6K1 signaling cascades play an important role both in the survival and proliferation of tumor cells.

METHODS

In the present study, we investigated the effects of embelin (EB), identified primarily from the Embelia ribes plant, on the Akt/mTOR/S6K1 activation, associated gene products, cellular proliferation, and apoptosis in human prostate cancer cells.

RESULTS

EB exerted significant cytotoxic and suppressive effects on Akt and mTOR activation against androgen-independent PC-3 cells as compared to androgen-dependent LNCaP cells. Moreover, EB suppressed the constitutive activation of Akt/mTOR/S6K1 signaling cascade, which correlated with the induction of apoptosis as characterized by accumulation of cells in subG1 phase, positive Annexin V binding, down-regulation of anti-apoptotic (Bcl-2, Bcl-xL, survivin, IAP-1, and IAP-2) and proliferative (cyclin D1) proteins, activation of caspase-3, and cleavage of PARP. We also observed that EB can significantly enhance the apoptotic effects of a specific pharmacological Akt inhibitor when used in combination and also caused broad inhibition of all the three kinases in Akt/mTOR/S6K1 signaling axis in PC-3 cells.

CONCLUSIONS

EB inhibits multiple signaling cascades involved in tumorigenesis and can be used as a potential therapeutic candidate for both the prevention and treatment of prostate cancer.

Activity and complexes of mTOR in diffuse large B-cell lymphomas--a tissue microarray study

Diffuse large B-cell lymphoma is a heterogeneous group of diseases with different responses to therapy. Targeting mTOR (mammalian target of rapamycin) offers a new approach to improve the treatment. mTOR inhibitors are being developed and are in clinical use in mantle cell lymphoma therapy and clinical trials are ongoing in other high-grade lymphomas as well. However, there is limited data about mTOR activity and the expression of its different complexes in diffuse large B-cell lymphomas. Tissue microarray blocks were constructed from paraffin-embedded biopsy specimens. More than 700 immunohistochemical stainings (mTOR signaling-related proteins and phosphoproteins, markers for lymphoma classification) were evaluated from 68 diffuse large B-cell lymphoma biopsies from conventionally treated and followed patients. Approximately 30% of cases were characterized as germinal center-derived diffuse large B-cell lymphomas, which showed virtually no mTOR activity, as determined by phospho-ribosomal S6 expression, the most sensitive marker of mTOR activity. In about 80% of non-germinal center-derived diffuse large B-cell lymphoma cases, positivity of mTOR-related phosphoproteins was observed, denoting mTOR activity. Moreover, Rictor (a characteristic protein of the mTOR complex2) was overexpressed in 43% of all diffuse large B-cell lymphomas and in 63% of mTOR-active non-germinal center diffuse large B-cell lymphoma samples. Rictor overexpression with mTOR activity indicated significantly worse survival for patients than mTOR inactivity or mTOR activity with low Rictor expression. These results suggest that mTOR activity is characteristic in most non-germinal center-derived diffuse large B-cell lymphomas with potentially variable mTOR-inhibitor sensitivity. Taken together, mTOR inhibitors may be useful in addition to regular therapy in diffuse large B-cell lymphomas, however, patient and inhibitor selection criteria must be carefully considered.

Centroblastic diffuse large B cell lymphoma displays distinct expression pattern and prognostic role of apoptosis resistance related proteins

Centroblastic diffuse large B cell lymphoma (DLBCL) samples were analyzed by immunohistochemistry to evaluate the expression of p53, Bcl-2, Survivin, XIAP, and Ki-67. Survivin was the only protein which expression exhibited a trend for impact in progression-free (p = .077) and overall survival (p = .054). In the Mann-Whitney test, Survivin expression correlated with a negative overall survival (p = .045). These results appeared to be intimately related to Survivin cytoplasmic localization. Moreover, the anti-apoptotic proteins Bcl-2 and Survivin were less frequent in centroblastic DLBCL. Our results indicate that centroblastic DLBCL may be a disease with characteristic biology and clinical course and, therefore, specific prognostic factors.

Cancer gene therapy targeting cellular apoptosis machinery

The unraveling of cellular apoptosis machinery provides novel targets for cancer treatment, and gene therapy targeting this suicidal system has been corroborated to cause inflammation-free autonomous elimination of neoplastic cells. The apoptotic machinery can be targeted by introduction of a gene encoding an inducer, mediator or executioner of apoptotic cell death or by inhibition of anti-apoptotic gene expression. Strategies targeting cancer cells, which are achieved by selective gene delivery, specific gene expression or secretion of target proteins via genetic modification of autologous cells, dictate the outcome of apoptosis-based cancer gene therapy. Despite so far limited clinical success, gene therapy targeting the apoptotic machinery has great potential to benefit patients with threatening malignancies provided the availability of efficient and specific gene delivery and administration systems.

Association of expression of XIAP-associated factor 1 (XAF1) with clinicopathologic factors, overall survival, microvessel density and cisplatin-resistance in ovarian cancer

XIAP-associated factor 1 (XAF1) was identified as a novel X-linked inhibitor of apoptosis (XIAP) binding partner that can reverse the anti-apoptotic effect of XIAP. XAF1 levels are greatly decreased in many cancer tissues and cell lines. The aim of this study was to investigate the expression of XAF1 and XIAP in advanced epithelial ovarian cancer and role of XAF1 in cisplatin resistance of ovarian cancer cells. Tissues from 94 patients with advanced epithelial ovarian cancer (EOC) and 30 ovarian cystadenomas were obtained. We analyzed the association of the immunohistochemical-determined expression of these two factors and clinicopathologic variables, overall survival, and angiogenesis. We established SKOV3 cells stably overexpressing XAF1 and explored the possible functions of XAF1 in ovarian cancer cells in vitro and in vivo. The protein expression of XAF1 was significantly lower and that of XIAP higher in malignant than nonmalignant tissues. Low XAF1 expression was associated with high-grade tumors and poor overall survival for patients. XAF1 expression was associated with microvessel density. Overexpression of XAF1 suppressed cell proliferation and enhanced SKOV3 cells sensitivity to cisplatin, as well as inhibited tumor growth and decreased MVD in vivo. Overexpression of XAF1 induced XIAP inactivation, caspase-3 activation and cytosolic expression of cytochrome c. These results suggested that XAF1 may be involved in ovarian cancer development and up-regulation of XAF1 may confer sensitivity of ovarian cancer cells to cisplatin-mediated apoptosis.

Quantitative proteomics reveals that miR-155 regulates the PI3K-AKT pathway in diffuse large B-cell lymphoma

The aberrant expression of microRNA-155 (miR-155), which has emerged as having a significant impact on the biological characteristics of lymphocytes, plays important roles in B-cell malignancies, such as diffuse large B-cell lymphoma (DLBCL). DLBCL is the most common non-Hodgkin's lymphoma in the adult population, accounting for approximately 40% of newly diagnosed non-Hodgkin's lymphoma cases globally. To determine the specific function of miR-155, a quantitative proteomics approach was applied to examine the inhibitory effects of miR-155 on protein synthesis in DLBCL cells. PIK3R1 (p85α), a negative regulator of the phosphatidylinositol 3-kinase (PI3K)-AKT pathway, was identified as a direct target of miR-155. A luciferase reporter was repressed through the direct interaction of miR-155 and the p85α 3'-untranslated region, and overexpression of miR-155 down-regulated both the transcription and translation of p85α. The PI3K-AKT signaling pathway was highly activated by the sustained overexpression of miR-155 in DHL16 cells, whereas knockdown of miR-155 in OCI-Ly3 cells diminished AKT activity. Taken together, our results reveal a novel target involved in miR-155 biological characteristics and provide a molecular link between the overexpression of miR-155 and the activation of PI3K-AKT in DLBCL.

Targeting IAP proteins for therapeutic intervention in cancer

Evasion of apoptosis is one of the crucial acquired capabilities used by cancer cells to fend off anticancer therapies. Inhibitor of apoptosis (IAP) proteins exert a range of biological activities that promote cancer cell survival and proliferation. X chromosome-linked IAP is a direct inhibitor of caspases - pro-apoptotic executioner proteases - whereas cellular IAP proteins block the assembly of pro-apoptotic protein signalling complexes and mediate the expression of anti-apoptotic molecules. Furthermore, mutations, amplifications and chromosomal translocations of IAP genes are associated with various malignancies. Among the therapeutic strategies that have been designed to target IAP proteins, the most widely used approach is based on mimicking the IAP-binding motif of second mitochondria-derived activator of caspase (SMAC), which functions as an endogenous IAP antagonist. Alternative strategies include transcriptional repression and the use of antisense oligonucleotides. This Review provides an update on IAP protein biology as well as current and future perspectives on targeting IAP proteins for therapeutic intervention in human malignancies.

Overexpression of FoxM1 offers a promising therapeutic target in diffuse large B-cell lymphoma

BACKGROUND

FoxM1 has been shown to play a critical role in the pathogenesis of various epithelial malignancies. However, its role in lymphoid malignancies has not been fully clarified. We, therefore, investigated the role of FoxM1 expression in a large cohort of diffuse large B-cell lymphoma samples and panel of cell lines.

DESIGN AND METHODS

FoxM1 expression was investigated in a large series of diffuse large B-cell lymphoma tissues in a tissue microarray format by immunohistochemistry. Apoptosis was measured by flow cytometry and protein expression was detected by immunoblotting using diffuse large B-cell lymphoma cell lines following treatment with either pharmacological inhibitor of FoxM1 or small interference RNA knockdown strategy. Invasion/migration and soft agar colony assays were also performed following treatment with FoxM1 inhibitor.

RESULTS

FoxM1 expression was detected in 84.6% of diffuse large B-cell lymphoma tumors and found to be significantly associated with proliferative tumor marker Ki67 (P<0.0001), matrix metalloproteinases-2 (P=0.0008), matrix metalloproteinases-9 (P=0.0002), S-phase kinase associated protein-2 (P<0.0001) and inversely associated with p27 expression (P=0.0215). Expression of small interference RNA targeted against FoxM1 or treatment of diffuse large B-cell lymphoma cells with thiostrepton caused its downregulation accompanied by decreased expression of matrix metalloproteinases-2 and matrix metalloproteinases-9. Inhibition of FoxM1 in diffuse large B-cell lymphoma cells also decreased invasive and migratory capability, and induced caspase dependent apoptosis via activation of the mitochondrial apoptotic pathway. Finally, combined thiostrepton and bortezomib at sub-toxic doses led to efficient apoptosis in diffuse large B-cell lymphoma cells.

CONCLUSIONS

Altogether, these results suggest that FoxM1 is over-expressed in the majority of diffuse large B-cell lymphoma samples. These data also indicate that targeting FoxM1 signaling can serve as a potential therapeutic modality in the management of diffuse large B-cell lymphoma.

Exploiting inhibitor of apoptosis proteins as therapeutic targets in hematological malignancies

Resistance to apoptosis is one of the hallmarks of human cancers and contributes to the insensitivity of many cancers to commonly used treatment approaches. Inhibitor of apoptosis (IAP) proteins, a family of anti-apoptotic proteins, have an important role in evasion of apoptosis, as they can both block apoptosis-signaling pathways and promote survival. High expression of IAP proteins is observed in multiple cancers, including hematological malignancies, and has been associated with unfavorable prognosis and poor patients' outcome. Therefore, IAP proteins are currently considered as promising molecular targets for therapy. Indeed, drug-discovery approaches over the last decade aiming at neutralizing IAP proteins have resulted in the generation of small-molecule inhibitors or antisense oligonucleotides that demonstrated in vitro and in vivo antitumor activities in preclinical studies. As some of these strategies have already entered the stage of clinical evaluation, for example, in leukemia, an update on this promising molecular-targeted strategy to interfere with apoptotic pathways is of broad interest.

Resveratrol suppresses constitutive activation of AKT via generation of ROS and induces apoptosis in diffuse large B cell lymphoma cell lines

Background

We have recently shown that deregulation PI3-kinase/AKT survival pathway plays an important role in pathogenesis of diffuse large B cell lymphoma (DLBCL). In an attempt to identify newer therapeutic agents, we investigated the role of Resveratrol (trans-3,4′, 5-trihydroxystilbene), a naturally occurring polyphenolic compound on a panel of diffuse large B-cell lymphoma (DLBCL) cells in causing inhibition of cell viability and inducing apoptosis.

Methodology/Principal Findings

We investigated the action of Resveratrol on DLBCL cells and found that Resveratrol inhibited cell viability and induced apoptosis by inhibition of constitutively activated AKT and its downstream targets via generation of reactive oxygen species (ROS). Simultaneously, Resveratrol treatment of DLBCL cell lines also caused ROS dependent upregulation of DR5; and interestingly, co-treatment of DLBCL with sub-toxic doses of TRAIL and Resveratrol synergistically induced apoptosis via utilizing DR5, on the other hand, gene silencing of DR5 abolished this effect.

Conclusion/Significance

Altogether, these data suggest that Resveratrol acts as a suppressor of AKT/PKB pathway leading to apoptosis via generation of ROS and at the same time primes DLBCL cells via up-regulation of DR5 to TRAIL-mediated apoptosis. These data raise the possibility that Resveratrol may have a future therapeutic role in DLBCL and possibly other malignancies with constitutive activation of the AKT/PKB pathway.

Genotypic and phenotypic differences between nodal and extranodal diffuse large B-Cell lymphomas

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous group of diseases that have diverse clinical, pathological, and biological features. Here, it is shown that primary nodal and extranodal DLBCLs differ genomically and phenotypically. Using conventional comparative genomic hybridization (CGH), the authors assessed the chromosomal aberrations in 18 nodal, 13 extranodal, and 5 mixed DLBCLs. The results demonstrate significantly distinct chromosomal aberrations exemplified by gains of chromosomal arms 1p, 7p, 12q24.21-12q24.31, and 22q and chromosome X and loss of chromosome 4, 6q, and 18q22.3-23 in extranodal compared with nodal DLBCLs. Nodal DLBCLs showed an increased tendency for 18q amplification and BCL2 protein overexpression compared with extranodal and mixed tumors. Using a panel of five antibodies against GCET1, MUM1, CD10, BCL6, and FOXP1 proteins to subclassify DLBCLs according to the recent Choi algorithm, the authors showed that the genomic profiles observed between the nodal and extranodal DLBCLs were not due to the different proportions of GCB vs ABC in the two groups. Further delineation of these genomic differences was illuminated by the use of high-resolution 21K BAC array CGH performed on 12 independent new cases of extranodal DLBCL. The authors demonstrated for the first time a novel genome and proteome-based signatures that may differentiate the two lymphoma types.

Clioquinol induces cytoplasmic clearance of the X-linked inhibitor of apoptosis protein (XIAP): therapeutic indication for prostate cancer

Clioquinol (5-chloro-7-iodo-8-quinolinol) is a copper ionophore that was used primarily during the 1950-1970s as an oral antimicrobial agent. It has been established that clioquinol displays toxicity towards malignant cells, inducing caspase-dependent apoptosis. In the present study we therefore investigated the effect of clioquinol on the XIAP [X-linked IAP (inhibitor of apoptosis protein)], as one of its primary functions is to hinder caspase activity and suppress apoptotic cell death. Clioquinol treatment caused cytoplasmic XIAP to rapidly relocate to the nucleus in multiple human transformed (hyperplasic and carcinoma) prostate lines. Clioquinol also caused the cytoplasmic clearance of other IAP family members (cIAP1 and cIAP2). Copper, and no other relevant bivalent metal (e.g. zinc or iron), was exclusively required for clioquinol to elicit an effect on XIAP. We further demonstrated that clioquinol selectively targets and rapidly destroys transformed prostate lines without harming primary prostate epithelial cells. The toxicity of clioquinol was copper-dependent, positively correlated with the level of extracellular copper and could be abrogated by using the copper chelator TTM (tetrathiomolybdate). Clioquinol forced the profound accumulation of intracellular copper with ensuing toxicity influenced by key regulators of cellular copper homoeostasis. Taken together, our results provide significant insight into clioquinol toxicity and reveal an exciting therapeutic approach for the treatment of prostate cancer.

The biological and clinical impact of inhibition of NF-κB-initiated apoptosis in diffuse large B cell lymphoma (DLBCL)

NF-κB is frequently over-expressed in a variety of non-Hodgkin's lymphomas (NHLs) and has been implicated in lymphomagenesis; however, its role in diffuse large B cell lymphoma (DLBCL) as a prognostic biomarker has not been fully elucidated. Therefore, we investigated the role of NF-κB and its association with clinicopathological features in a tissue microarray cohort of 230 DLBCL patient samples. We then elucidated the role of NF-κB inhibition on cell viability and apoptosis in vitro, using DLBCL cell lines. Using immunohistochemistry, NF-κB was detected in 25.6% (52/203) DLBCL tumours, was associated with activated B cell (ABC) phenotype (p = 0.0054), Epstein-Barr virus (EBV; p = 0.0080) and over-expression of the anti-apoptotic marker XIAP (p = 0.0013). DLBCL cases with nuclear expression of NF-κB showed a significantly poorer overall survival as compared to those without NF-κB expression (p = 0.0236). In a multivariate analysis using a Cox proportional hazard model for IPI and NF-κB expression, the relative risk was 2.97 for high NF-κB expression (95% CI 1.27-6.94; p = 0.0113) and 7.55 for the high-IPI group (95% CI 3.34-18.35; p < 0.0001). In vitro, Bay 11-7085 inhibited constitutively active NF-κB expression in a dose-dependent manner and inhibition of NF-κB also down-regulated expression of the downstream target gene products Bcl-2, Bcl-XL (BCL2L1), XIAP and Survivin, leading to apoptosis via activation of the mitochondrial apoptotic pathway. NF-κB over-expression was found to be an independent prognostic marker for poor survival in DLBCL. Altogether, these results suggest that NF-κB may be a useful prognostic biomarker and a potential target for therapeutic intervention in DLBCL.