Molecular targeted therapies for diffuse large B-cell lymphoma based on apoptosis profiles

Mitochondrial Fission Factor Is a Novel Interacting Protein of the Critical B Cell Survival Regulator TRAF3 in B Lymphocytes

Proteins controlling mitochondrial fission have been recognized as essential regulators of mitochondrial functions, mitochondrial quality control and cell apoptosis. In the present study, we identified the critical B cell survival regulator TRAF3 as a novel binding partner of the key mitochondrial fission factor, MFF, in B lymphocytes. Elicited by our unexpected finding that the majority of cytoplasmic TRAF3 proteins were localized at the mitochondria in resting splenic B cells after ex vivo culture for 2 days, we found that TRAF3 specifically interacted with MFF as demonstrated by co-immunoprecipitation and GST pull-down assays. We further found that in the absence of stimulation, increased protein levels of mitochondrial TRAF3 were associated with altered mitochondrial morphology, decreased mitochondrial respiration, increased mitochondrial ROS production and membrane permeabilization, which eventually culminated in mitochondria-dependent apoptosis in resting B cells. Loss of TRAF3 had the opposite effects on the morphology and function of mitochondria as well as mitochondria-dependent apoptosis in resting B cells. Interestingly, co-expression of TRAF3 and MFF resulted in decreased phosphorylation and ubiquitination of MFF as well as decreased ubiquitination of TRAF3. Moreover, lentivirus-mediated overexpression of MFF restored mitochondria-dependent apoptosis in TRAF3-deficient malignant B cells. Taken together, our findings provide novel insights into the apoptosis-inducing mechanisms of TRAF3 in B cells: as a result of survival factor deprivation or under other types of stress, TRAF3 is mobilized to the mitochondria through its interaction with MFF, where it triggers mitochondria-dependent apoptosis. This new role of TRAF3 in controlling mitochondrial homeostasis might have key implications in TRAF3-mediated regulation of B cell transformation in different cellular contexts. Our findings also suggest that mitochondrial fission is an actionable therapeutic target in human B cell malignancies, including those with TRAF3 deletion or relevant mutations.

Identification of a 14-Gene Prognostic Signature for Diffuse Large B Cell Lymphoma (DLBCL)

Although immunotherapy is a potential strategy to resist cancers, due to the inadequate acknowledge, this treatment is not always effective for diffuse large B cell lymphoma (DLBCL) patients. Based on the current situation, it is critical to systematically investigate the immune pattern. According to the result of univariate and multivariate cox proportional hazards, LASSO regression and Kaplan-Meier survival analysis on immune-related genes (IRGs), a prognostic signature, containing 14 IRGs (AQP9, LMBR1L, FGF20, TANK, CRP, ORM1, JAK1, BACH2, MTCP1, IFITM1, TNFSF10, FGF12, RFX5, and LAP3), was built. This model was validated by external data, and performed well. DLBCL patients were divided into low- and high-risk groups, according to risk scores from risk formula. The results of CIBERSORT showed that different immune status and infiltration pattern were observed in these two groups. Gene set enrichment analysis (GSEA) indicated 12 signaling pathways were significantly enriched in the high-risk group, such as natural killer cell-mediated cytotoxicity, toll-like receptor signaling pathway, and so on. In summary, 14 clinically significant IRGs were screened to build a risk score formula. This formula was an accurate tool to provide a certain basis for the treatment of DLBCL patients.

Critically dysregulated signaling pathways and clinical utility of the pathway biomarkers in lymphoid malignancies

Accumulating evidence confirmed that many dysregulated signaling pathways and aberrant genetic alterations contribute to the oncogenesis and heterogeneity of lymphoid malignancies. Therapeutically targeting dysregulating signaling pathways and their hidden oncogenic biomarkers are becoming available, but did not show desired therapeutic effect in current clinical practice. It is meaningful to further understand the underlying mechanisms of the dysregulated signaling pathways and to address the potential utility of pathway-related biomarkers. To precisely identify the dysregulation of signaling pathways and the “driver” oncogenic biomarkers, as well as to develop reliable and reproducible risk-stratification based on biomarkers will be challenging. Nevertheless, pathway-based targeted therapy will raise the hope to improve the outcomes of the patients with lymphoid malignancies, especially with aggressive types, and the efficient utility of pathway-related biomarkers in diagnosis, prognosis, prediction of lymphoid malignancies may also be able to power precision medicine.

The feedback loop of LITAF and BCL6 is involved in regulating apoptosis in B cell non-Hodgkin's-lymphoma

Dysregulation of the apoptotic pathway is widely recognized as a key step in lymphomagenesis. Notably, LITAF was initially identified as a p53-inducible gene, subsequently implicated as a tumor suppressor. Our previous study also showed LITAF to be methylated in 89.5% B-NHL samples. Conversely, deregulated expression of BCL6 is a pathogenic event in many lymphomas. Interestingly, our study found an oppositional expression of LITAF and BCL6 in B-NHL. In addition, LITAF was recently identified as a novel target gene of BCL6. Therefore, we sought to explore the feedback loop between LITAF and BCL6 in B-NHL. Here, our data for the first time show that LITAF can repress expression of BCL6 by binding to Region A (-87 to +65) containing a putative LITAF-binding motif (CTCCC) within the BCL6 promoter. Furthermore, the regulation of BCL6 targets ( PRDM1 or c-Myc) by LITAF may be associated with B-cell differentiation. Results also demonstrate that ectopic expression of LITAF induces cell apoptosis, activated by releasing cytochrome c, cleaving PARP and caspase 3 in B-NHL cells whereas knockdown of LITAF robustly protected cells from apoptosis. Interestingly, BCL6, in turn, could reverse cell apoptosis mediated by LITAF. Collectively, our findings provide a novel apoptotic regulatory pathway in which LITAF, as a transcription factor, inhibits the expression of BCL6, which leads to activation of the intrinsic mitochondrial pathway and tumor apoptosis. Our study is expected to provide a possible biomarker as well as a target for clinical therapies to promote tumor cell apoptosis.

A Traditional Chinese Medicine Herb Mixture Qingjie Fuzheng Granules Inhibits Hepatocellular Carcinoma Cells Growth by Inducing Apoptosis

In this study, hepatocellular carcinoma (HCC) mouse xenograft model, MTT assay, colony formation, nuclear staining, and Annexin-V/PI staining assays were used to evaluate the effect of Qingjie Fuzheng granules (QFG) on cell proliferation and apoptosis of HCC cell in vivo and in vitro. Furthermore, Western blotting was performed to detect the expression of Fas, FasL, Bcl-2, Bax, and the activation of caspase-3/-8/-9. The results showed that QFG reduced tumor weight ( P < .05) but had no effect on body weight gain in HCC mice in vivo. QFG significantly reduced HCC cell viability and attenuated cell proliferation in a dose-dependent manner ( P < .05). QFG increased the expression of Fas, FasL, and Bax ( P < .05). QFG downregulated the expression of Bcl-2 and promoted the activation of caspase-8, -9, and -3 ( P < .05). These results suggested that QFG possessed anticancer effects, and the mechanisms of action may involve the death receptor pathway and mitochondrion-dependent pathway-mediated apoptosis.

Mannich bases of 1,2,4-triazole-3-thione containing adamantane moiety: Synthesis, preliminary anticancer evaluation, and molecular modeling studies

A series of 18 novel N-Mannich bases derived from 5-adamantyl-1,2,4-triazole-3-thione was synthesized and characterized using NMR spectroscopy and X-ray diffraction technique. All derivatives were evaluated for their anticancer potential against four human cancer cell lines. Several tested compounds exerted good cytotoxic activities on K562 and HL-60 cell lines, along with pronounced selectivity, showing lower cytotoxicity against normal fibroblasts MRC-5 compared to cancer cells. The effects of compounds 5b, 5e, and 5j on the cell cycle were investigated by flow cytometric analysis. It was found that these compounds cause the accumulation of cells in the subG1 and G1 phases of the cell cycle and induce caspase-dependent apoptosis, while the anti-angiogenic effects of 5b, 5e, and 5j have been confirmed in EA.hy926 cells using a tube formation assay. Further, the interaction of Bax protein with compound 5b was investigated by means of molecular modeling, applying the combined molecular docking/molecular dynamics approach.

Oncogenic Signaling Pathways and Pathway-Based Therapeutic Biomarkers in Lymphoid Malignancies

Lymphoma is characterized by heterogeneous biology, pathologic features, and clinical outcome. This has been proven by accumulating pathologic and molecular evidence attributed to underlying aberrant alterations at genetic, epigenetic, transcriptional, protein, microenvironmental levels, and dysregulated oncogenic signaling pathways. In the era of precision medicine, targeting oncogenic pathways to design drugs and to optimize treatment regimens for the lymphoma patients is feasible and clinically significant. As such, further understanding of the biology and the mechanisms behind lymphoma development and identification of oncogenic pathway activation and pathway-based biomarkers to better design precise therapies are challenging but hopeful. Furthermore, pathway-based targeted therapies in combination with traditional chemotherapy, single specific targeted antibody therapy, and immunotherapy might raise the hope for the patients with lymphoma, especially for relapsed and refractory lymphoma patients.

Anticancer Effects of 1,3-Dihydroxy-2-Methylanthraquinone and the Ethyl Acetate Fraction of Hedyotis Diffusa Willd against HepG2 Carcinoma Cells Mediated via Apoptosis

Hedyotis Diffusa Willd, used in Traditional Chinese Medicine, is a treatment for various diseases including cancer, owing to its mild effectiveness and low toxicity. The aim of this study was to identify the main anticancer components in Hedyotis Diffusa Willd, and explore mechanisms underlying their activity. Hedyotis Diffusa Willd was extracted and fractionated using ethyl acetate to obtain the H-Ethyl acetate fraction, which showed higher anticancer activity than the other fractions obtained against HepG2 cells with sulforhodamine B assays. The active component of the H-Ethyl acetate fraction was identified to be 1,3-dihydroxy-2-methylanthraquinone (DMQ) with much high inhibitory rate up to 48.9 ± 3.3% and selectivity rate up to 9.4 ± 4.5 folds (p<0.01) at 125 μmol/L. HepG2 cells treated with the fraction and DMQ visualized morphologically using light and fluorescence microscopy. Annexin V--fluorescein isothiocyanate / propidium iodide staining flow cytometry, DNA ladder and cell cycle distribution assays. Mechanistic studies showed up-regulation of caspase-3, -8, and -9 proteases activities (p<0.001), indicating involvement of mitochondrial apoptotic and death receptor pathways. Further studies revealed that reactive oxygen species in DMQ and the fraction treated HepG2 cells increased (p<0.01) while mitochondrial membrane potential reduced significantly (p<0.001) compared to the control by flow cytometry assays. Western blot analysis showed that Bax, p53, Fas, FasL, p21 and cytoplasmic cytochrome C were up-regulated (p<0.01), while Bcl-2, mitochondrial cytochrome C, cyclin E and CDK 2 were down-regulated dose-dependently (p<0.01). The reverse transcriptase-polymerase chain reaction showed that mRNA expressions of p53 and Bax increased (p<0.001) while that of Bcl-2 decreased (p<0.001). Pre-treatment with caspase-8 inhibitor Z-IETD-FMK, or caspase-9 inhibitor Z-LEHD-FMK, attenuated the growth-inhibitory and apoptosis-inducing effects of DMQ and the fraction on HepG2 cells. These results suggested that DMQ and the H-Ethyl acetate fraction of Hedyotis Diffusa Willd showed potential anticancer effects. Furthermore, the mechanisms of action may involve mitochondrial apoptotic and death receptor pathways.

Reactive oxygen species mediate oridonin-induced apoptosis through DNA damage response and activation of JNK pathway in diffuse large B cell lymphoma

This study investigated the cytotoxic effect of oridonin (ORI), a diterpenoid isolated from Rabdosia rubescens, in human diffuse large B cell lymphoma (DLBCL) in vitro and in vivo and the potential molecular mechanisms for ORI-induced cell apoptosis. ORI treatment caused reactive oxygen species (ROS)-mediated oxidative DNA damage response (DDR) and the c-Jun N-terminal kinase (JNK) pathway activation, leading to an induction of intrinsic apoptosis. ROS abolition blocked ORI-induced apoptosis and attenuated the expression of phospho-histone H2AX and phospho-JNK, indicating that ROS-mediated DNA damage and JNK pathway activation were involved in ORI-induced apoptosis. The systemic administration of ORI suppressed the growth of human DLBCL xenografts without showing significant toxicity. These findings suggest that ORI may have promising therapeutic application in DLBCL.

Liriodenine induces the apoptosis of human laryngocarcinoma cells via the upregulation of p53 expression

Laryngocarcinoma is one of the most aggressive cancers that affects the head and neck region. The survival rate of patients with laryngocarcinoma is low due to late metastases and the resistance of the disease to chemotherapy and radiotherapy. Liriodenine, an alkaloid extracted from a number of plant species, has demonstrated antitumor effects on multiple types of cancer. However, the effects of liriodenine upon laryngocarcinoma, and the underlying mechanisms, are yet to be elucidated. The present study therefore investigated the potential antitumor effects of liriodenine on HEp-2 human laryngocarcinoma cells in vitro and HEp-2-implanted nude mice in vivo. Liriodenine induced significant apoptosis and inhibition of cell migration in the HEp-2 cells. Furthermore, the rate of tumor growth in the HEp-2-implanted nude mice was inhibited by the administration of liriodenine. The potential mechanism underlying the antitumor effects of liriodenine may result from an upregulative effect upon p53 expression, which ultimately induces cellular apoptosis. By contrast, the downregulation of p53 significantly reduced the antitumor effects of liriodenine. Together, these results suggest that liriodenine exhibits potent antitumor activities in laryngocarcinoma HEp-2 cells, in vitro and in vivo, via the upregulation of p53 expression. Liriodenine may therefore be a potential therapy for the treatment of laryngocarcinoma.

Combining CAR T cells and the Bcl-2 family apoptosis inhibitor ABT-737 for treating B-cell malignancy

B-cell malignancies upregulate the B-cell lymphoma 2 (Bcl-2) family inhibitors of the intrinsic apoptosis pathway, making them therapy resistant. However, small-molecule inhibitors of Bcl-2 family members such as ABT-737 restore a functional apoptosis pathway in cancer cells, and its oral analog ABT-263 (Navitoclax) has entered clinical trials. Gene engineered chimeric antigen receptor (CAR) T cells also show promise in B-cell malignancy, and as they induce apoptosis via the extrinsic pathway, we hypothesized that small-molecule inhibitors of the Bcl-2 family may potentiate the efficacy of CAR T cells by engaging both apoptosis pathways. CAR T cells targeting CD19 were generated from healthy donors as well as from pre-B-ALL (precursor-B acute lymphoblastic leukemia) patients and tested together with ABT-737 to evaluate apoptosis induction in five B-cell tumor cell lines. The CAR T cells were effective even if the cell lines exhibited different apoptosis resistance profiles, as shown by analyzing the expression of apoptosis inhibitors by PCR and western blot. When combining T-cell and ABT-737 therapy simultaneously, or with ABT-737 as a presensitizer, tumor cell apoptosis was significantly increased. In conclusion, the apoptosis inducer ABT-737 enhanced the efficacy of CAR T cells and could be an interesting drug candidate to potentiate T-cell therapy.

Inhibitory Effects of 5-Aza-2'-Deoxycytidine and Trichostatin A in Combination with p53-Expressing Adenovirus on Human Laryngocarcinoma Cells

OBJECTIVE

To investigate the effects of 5-Aza-2'-deoxycytidine (5-Aza-Cdr) and trichostatin A (TSA) combined with p53-expressing adenovirus (Ad-p53) on Hep-2 cell line in vivo and in vitro, in order to explore its possibility in biological treatment of laryngocarcinoma.

METHODS

Effects of 5-Aza-Cdr and TSA in combination with Ad-p53 on Hep-2 cell line in vivo were determined by Cell Counting Kit-8 (CCK-8) assay. The effect of drug combination was calculated by Jin's formula. Effects on the cell line in vitro were investigated by establishing the nude mice model.

RESULTS

5-Aza-Cdr and TSA showed inhibitory effects on the proliferation of Hep-2 cells in dose- and time-dependent manner. Ad-p53 can inhibit the growth of Hep-2 cells in vivo and in vitro. However, the combination of epigenetic reagents (5-Aza-Cdr/TSA) and Ad-p53 was less effective than individual use of Ad-p53. 5-Aza-Cdr and Ad-p53 inhibited the growth of transplanted tumors and reduced the volume of tumors, and the tumor volume of Ad-p53 group was significantly smaller than that of the control group (P<0.05).

CONCLUSION

Both epigenetic reagents (5-Aza-Cdr/TSA) and Ad-p53 can suppress cell proliferation on Hep-2 in vivo and in vitro and there may be some antagonistic mechanism between Ad-p53 and epigenetic reagents (5-Aza-Cdr/ TSA).

Dysfunction of the TP53 tumor suppressor gene in lymphoid malignancies

Mutations of the TP53 gene and dysregulation of the TP53 pathway are important in the pathogenesis of many human cancers, including lymphomas. Tumor suppression by p53 occurs via both transcription-dependent activities in the nucleus by which p53 regulates transcription of genes involved in cell cycle, DNA repair, apoptosis, signaling, transcription, and metabolism; and transcription-independent activities that induces apoptosis and autophagy in the cytoplasm. In lymphoid malignancies, the frequency of TP53 deletions and mutations is lower than in other types of cancer. Nonetheless, the status of TP53 is an independent prognostic factor in most lymphoma types. Dysfunction of TP53 with wild-type coding sequence can result from deregulated gene expression, stability, and activity of p53. To overcome TP53 pathway inactivation, therapeutic delivery of wild-type p53, activation of mutant p53, inhibition of MDM2-mediated degradation of p53, and activation of p53-dependent and -independent apoptotic pathways have been explored experimentally and in clinical trials. We review the mechanisms of TP53 dysfunction, recent advances implicated in lymphomagenesis, and therapeutic approaches to overcoming p53 inactivation.

Increased expression of the pro-apoptotic protein BIM, a mechanism for cAMP/protein kinase A (PKA)-induced apoptosis of immature T cells

The second messenger cAMP is proapoptotic for numerous cell types, but the mechanism for this proapoptotic action is not defined. Here, we use murine CD4(+)/CD8(+) S49 lymphoma cells and isolated thymocytes to assess this mechanism. In WT S49 cells, cAMP acts via protein kinase A (PKA) to induce G(1) phase cell cycle arrest and apoptosis. Treatment of WT and cAMP-Deathless (D-) S49 cells, which lack cAMP-promoted apoptosis, with the PKA agonist 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) differentially regulates transcripts for numerous proapoptotic and antiapoptotic proteins. In contrast, kin-S49 cells (which lack PKA) show no cAMP-promoted changes in transcript expression. In this study, we use knockdown and overexpression approaches to define the role in cAMP/PKA-promoted apoptosis of the proapoptotic factor BIM (Bcl-2 interacting mediator of cell death), whose expression prominently increases in response to CPT-cAMP treatment of WT but not D- or kin- S49 cells. Conditional expression of BimL, one of the three major forms of Bim, increases apoptosis of WT, D-, and kin-S49 cells, whereas inhibition of cAMP-mediated induction of Bim isoforms by shRNAi attenuates CPT-cAMP-mediated apoptosis of WT S49 cells. Bim protein levels increase in subpopulations of CPT-cAMP-treated cells that undergo apoptosis. Thymic CD4(+)/CD8(+) cells isolated from Bim(-/-) mice corroborated the requirement of Bim expression for cAMP-promoted apoptosis. Thus, up-regulation of Bim appears to be an important determinant of cAMP/PKA-mediated apoptosis in immature T cells and may be a mechanism for such apoptosis in other cell types as well.

A novel inhibitor of focal adhesion signaling induces caspase-independent cell death in diffuse large B-cell lymphoma

Focal adhesion (FA) proteins have been associated with transformation, migration, metastasis, and poor outcome in many neoplasias. We previously showed that these proteins were inhibited by E7123, a new celecoxib derivative with antitumor activity, in acute myeloid leukemia. However, little is known about FAs in diffuse large B cell lymphoma (DLBCL). This paper aimed to determine whether E7123 was effective against DLBCL and whether FAs were involved in its action. We evaluated the cytotoxicity and mechanism of action of E7123 and celecoxib in DLBCL cell lines. We also assessed the E7123 in vivo activity in a DLBCL xenograft model and studied FA signaling in primary DLBCL patient samples. We found that E7123 showed higher antitumor effect than celecoxib against DLBCL cells. Its mechanism of action involved deregulation of FA, AKT, and Mcl-1 proteins, a pathway that is activated in some patient samples, apoptosis-inducing factor release and induction of caspase-independent cell death. Moreover, E7123 showed suppression of in vivo tumor growth. These findings indicate that E7123 is effective against DLBCL in vitro and in vivo, with a mechanism of action that differs from that of most current therapies for this malignancy. Our results support further preclinical evaluation of E7123.

Apoptotic cell signaling in cancer progression and therapy

Apoptosis is a tightly regulated cell suicide program that plays an essential role in the development and maintenance of tissue homeostasis by eliminating unnecessary or harmful cells. Impairment of this native defense mechanism promotes aberrant cellular proliferation and the accumulation of genetic defects, ultimately resulting in tumorigenesis, and frequently confers drug resistance to cancer cells. The regulation of apoptosis at several levels is essential to maintain the delicate balance between cellular survival and death signaling that is required to prevent disease. Complex networks of signaling pathways act to promote or inhibit apoptosis in response to various cues. Apoptosis can be triggered by signals from within the cell, such as genotoxic stress, or by extrinsic signals, such as the binding of ligands to cell surface death receptors. Various upstream signaling pathways can modulate apoptosis by converging on, and thereby altering the activity of, common central control points within the apoptotic signaling pathways, which involve the BCL-2 family proteins, inhibitor of apoptosis (IAP) proteins, and FLICE-inhibitory protein (c-FLIP). This review highlights the role of these fundamental regulators of apoptosis in the context of both normal apoptotic signaling mechanisms and dysregulated apoptotic pathways that can render cancer cells resistant to cell death. In addition, therapeutic strategies aimed at modulating the activity of BCL-2 family proteins, IAPs, and c-FLIP for the targeted induction of apoptosis are briefly discussed.

Ligand-based receptor tyrosine kinase partial agonists: New paradigm for cancer drug discovery?

INTRODUCTION: Receptor tyrosine kinases (RTKs) are validated targets for oncology drug discovery and several RTK antagonists have been approved for the treatment of human malignancies. Nonetheless, the discovery and development of RTK antagonists has lagged behind the discovery and development of agents that target G-protein coupled receptors. In part, this is because it has been difficult to discover analogs of naturally-occurring RTK agonists that function as antagonists. AREAS COVERED: Here we describe ligands of ErbB receptors that function as partial agonists for these receptors, thereby enabling these ligands to antagonize the activity of full agonists for these receptors. We provide insights into the mechanisms by which these ligands function as antagonists. We discuss how information concerning these mechanisms can be translated into screens for novel small molecule- and antibody-based antagonists of ErbB receptors and how such antagonists hold great potential as targeted cancer chemotherapeutics. EXPERT OPINION: While there have been a number of important key findings into this field, the identification of the structural basis of ligand functional specificity is still of the greatest importance. While it is true that, with some notable exceptions, peptide hormones and growth factors have not proven to be good platforms for oncology drug discovery; addressing the fundamental issues of antagonistic partial agonists for receptor tyrosine kinases has the potential to steer oncology drug discovery in new directions. Mechanism based approaches are now emerging to enable the discovery of RTK partial agonists that may antagonize both agonist-dependent and -independent RTK signaling and may hold tremendous promise as targeted cancer chemotherapeutics.

The basis and rational use of molecular genetic testing in mature B-cell lymphomas

An increasing number of neoplasms are associated with variably specific genetic abnormalities. This is best exemplified by hematological malignancies, in which there is a growing list of entities that are defined by their genetic lesion(s); this is not (yet) the case in mature B-cell lymphomas. However, enhanced insights into the pathogenesis of this large and diverse group of lymphomas have emerged with the ongoing unraveling of a plethora of fascinating genetic abnormalities. The purpose of this review is to synthesize well-recognized data and nascent discoveries in our understanding of the genetic basis of a spectrum of mature B-cell lymphomas, and how this may be applied to contemporary clinical practice. Despite the explosion of new and exciting knowledge in this arena, with the potential for enhanced diagnostic and prognostic strategies, it is essential to remain cognizant of the limitations (and complexity) of genetic investigations, so that assays can be developed and used both judiciously and rationally.