Therapeutics targeting Bcl-2 in hematological malignancies

Current Therapeutic Sequencing in Chronic Lymphocytic Leukemia

The treatment landscape of chronic lymphocytic leukemia (CLL), the most frequent leukemia in adults, is constantly changing. CLL patients can be divided into three risk categories, based on their IGHV mutational status and the occurrence of TP53 disruption and/or complex karyotype. For the first-line treatment of low- and intermediate-risk CLL, both the BCL2 inhibitor venetoclax plus obinutuzumab and the second generation BTK inhibitors (BTKi), namely acalabrutinib and zanubrutinib, are valuable and effective options. Conversely, venetoclax-based fixed duration therapies have not shown remarkable results in high-risk CLL patients, while continuous treatment with acalabrutinib and zanubrutinib displayed favorable outcomes, similar to those obtained in TP53 wild-type patients. The development of acquired resistance to pathway inhibitors is still a clinical challenge, and the optimal treatment sequencing of relapsed/refractory CLL is not completely established. Covalent BTKi-refractory patients should be treated with venetoclax plus rituximab, whereas venetoclax-refractory CLL may be treated with second generation BTKi in the case of early relapse, while venetoclax plus rituximab might be used if late relapse has occurred. On these grounds, here we provide an overview of the current state-of-the-art therapeutic algorithms for treatment-naïve patients, as well as for relapsed/refractory disease.

B-cell lymphoma-2 family proteins in the crosshairs: Small molecule inhibitors and activators for cancer therapy

The B-cell lymphoma-2 (BCL-2) family of proteins plays a crucial role in the regulation of apoptosis, offering a dual mechanism for its control. Numerous studies have established a strong association between gene disorders of these proteins and the proliferation of diverse cancer cell types. Consequently, the identification and development of drugs targeting BCL-2 family proteins have emerged as a prominent area in antitumor therapy. Over the last two decades, several small-molecules have been designed to modulate the protein-protein interactions between anti- and proapoptotic BCL-2 proteins, effectively suppressing tumor growth and metastasis in vivo. The primary focus of research has been on developing BCL-2 homology 3 (BH3) mimetics to target antiapoptotic BCL-2 proteins, thereby competitively releasing proapoptotic BCL-2 proteins and restoring the blocked intrinsic apoptotic program. Additionally, for proapoptotic BCL-2 proteins, exogenous small molecules have been explored to activate cell apoptosis by directly interacting with executioner proteins such as BCL-2-associated X protein (BAX) or BCL-2 homologous antagonist/killer protein (BAK). In this comprehensive review, we summarize the inhibitors and activators (sensitizers) of BCL-2 family proteins developed over the past decades, highlighting their discovery, optimization, preclinical and clinical status, and providing an overall landscape of drug development targeting these proteins for therapeutic purposes.

SOHO State of the Art Updates and Next Questions: Understanding and Overcoming Venetoclax Resistance in Hematologic Malignancies

The discovery of Venetoclax (VEN) has transformed the therapeutic landscape of acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL). However, the response is heterogeneous with 10% to 50% of newly diagnosed AML patients not responding to hypomethylating agent (HMA) and VEN. Furthermore, up to 40% of responding patients relapse shortly. This review discusses the mechanism of action of Venetoclax and the major mechanisms of inherent and acquired resistance to VEN. VEN is highly specific to BCL-2 binding, as such other antiapoptotic proteins in BCL-2 family induce resistance. These antiapoptotic proteins can also be upregulated via a number of compensatory cell signaling pathways including PI3K/AKT/mTOR, the MAPK/ERK pathway, and mutant FLT3-ITD. Mutations can occur in BCL-2 and BAX proteins, or they can be silenced by TP53 mutations and other epigenetic changes. Changes to mitochondrial structure and metabolism can induce resistance. Key metabolic regulators include OXPHOS and alternative amino acid metabolism. Finally microenvironmental factors can influence VEN responses. This paper evaluates subsets of AML by differentiation, histology, cytogenetics and molecular markers and their different responses to VEN; with spliceosome mutations, ASXL1, NPM1 and IDH1/2 being favorable while others such as FLT3, TP53 and BCL-2 mutations being less responsive. Currently intensive multiagent chemotherapy and Venetoclax combinations such as 7+3+VEN are favored in fit younger AML patients. However, with resistant patients' subsets targeted combination therapies are becoming an increasingly attractive option. We explore the incorporation of non-BCL-2 inhibitors, next-generation BCL-2 and multi-protein agents, other inhibitors most prominently FLT-3 inhibitors in addition to Venetoclax, and other novel approaches for resolving Venetoclax resistance.

STEAP4 inhibits cisplatin-induced chemotherapy resistance through suppressing PI3K/AKT in hepatocellular carcinoma

Chemotherapy resistance is the leading cause for hepatocellular carcinoma (HCC)-induced death. Exploring resistance generation mechanism is an urgent need for HCC therapy. Here, we found STEAP4 was significantly downregulated in HCC patients with recurrence. Patients with low STEAP4 had poor outcome, suggesting STEAP4 might inhibit chemotherapy resistance. Cell viability assay, colony formation assay, apoptosis assay, soft agar growth assay, and tumor animal model showed STEAP4 inhibited cisplatin resistance. Mechanism analysis showed STEAP4 inhibited PI3K/AKT pathway through directly interacting with AKT. Double knockdown of STEP4 and AKT significantly inhibited cisplatin resistance. We also found STEAP4 expression was negatively correlated with PI3K/AKT pathway activity in clinic specimens. In summary, our findings suggested STEAP4 inhibited cisplatin resistance through suppressing PI3K/AKT pathway activity, providing a target for HCC therapy.

The mechanistic insights of the antioxidant Keap1-Nrf2 pathway in oncogenesis: a deadly scenario

The Nuclear factor erythroid 2-related factor 2 (Nrf2) protein has garnered significant interest due to its crucial function in safeguarding cells and tissues. The Nrf2 protein is crucial in preserving tissue integrity by safeguarding cells against metabolic, xenobiotic and oxidative stress. Due to its various functions, Nrf2 is a potential pharmacological target for reducing the incidence of diseases such as cancer. However, mutations in Keap1-Nrf2 are not consistently favored in all types of cancer. Instead, they seem to interact with specific driver mutations of tumors and their respective tissue origins. The Kelch-like ECH-associated protein 1 (Keap1)-Nrf2 pathway mutations are a powerful cancer adaptation that utilizes inherent cytoprotective pathways, encompassing nutrient metabolism and ROS regulation. The augmentation of Nrf2 activity elicits significant alterations in the characteristics of neoplastic cells, such as resistance to radiotherapy and chemotherapy, safeguarding against apoptosis, heightened invasiveness, hindered senescence, impaired autophagy and increased angiogenesis. The altered activity of Nrf2 can arise from diverse genetic and epigenetic modifications that instantly impact Nrf2 regulation. The present study aims to showcase the correlation between the Keap1-Nrf2 pathway and the progression of cancers, emphasizing genetic mutations, metabolic processes, immune regulation, and potential therapeutic strategies. This article delves into the intricacies of Nrf2 pathway anomalies in cancer, the potential ramifications of uncontrolled Nrf2 activity, and therapeutic interventions to modulate the Keap1-Nrf2 pathway.

Treatment Refractoriness in Chronic Lymphocytic Leukemia: Old and New Molecular Biomarkers

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. Despite its indolent clinical course, therapy refractoriness and disease progression still represent an unmet clinical need. Before the advent of pathway inhibitors, chemoimmunotherapy (CIT) was the commonest option for CLL treatment and is still widely used in areas with limited access to pathway inhibitors. Several biomarkers of refractoriness to CIT have been highlighted, including the unmutated status of immunoglobulin heavy chain variable genes and genetic lesions of TP53, BIRC3 and NOTCH1. In order to overcome resistance to CIT, targeted pathway inhibitors have become the standard of care for the treatment of CLL, with practice-changing results obtained through the inhibitors of Bruton tyrosine kinase (BTK) and BCL2. However, several acquired genetic lesions causing resistance to covalent and noncovalent BTK inhibitors have been reported, including point mutations of both BTK (e.g., C481S and L528W) and PLCG2 (e.g., R665W). Multiple mechanisms are involved in resistance to the BCL2 inhibitor venetoclax, including point mutations that impair drug binding, the upregulation of BCL2-related anti-apoptotic family members, and microenvironmental alterations. Recently, immune checkpoint inhibitors and CAR-T cells have been tested for CLL treatment, obtaining conflicting results. Potential refractoriness biomarkers to immunotherapy were identified, including abnormal levels of circulating IL-10 and IL-6 and the reduced presence of CD27⁺CD45RO^- CD8⁺ T cells.

The role and regulation of Maf proteins in cancer

The Maf proteins (Mafs) belong to basic leucine zipper transcription factors and are members of the activator protein-1 (AP-1) superfamily. There are two subgroups of Mafs: large Mafs and small Mafs, which are involved in a wide range of biological processes, such as the cell cycle, proliferation, oxidative stress, and inflammation. Therefore, dysregulation of Mafs can affect cell fate and is closely associated with diverse diseases. Accumulating evidence has established both large and small Mafs as mediators of tumor development. In this review, we first briefly describe the structure and physiological functions of Mafs. Then we summarize the upstream regulatory mechanisms that control the expression and activity of Mafs. Furthermore, we discuss recent studies on the critical role of Mafs in cancer progression, including cancer proliferation, apoptosis, metastasis, tumor/stroma interaction and angiogenesis. We also review the clinical implications of Mafs, namely their potential possibilities and limitations as biomarkers and therapeutic targets in cancer.

A real-world pharmacovigilance study of FDA Adverse Event Reporting System (FAERS) events for venetoclax

BACKGROUND

Venetoclax (VEN) is the first selective small molecule Bcl-2 inhibitor approved by FDA and used in adult chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL) and some acute myeloid leukemia (AML). However, the long-term safety of VEN in large sample population was unknown. This study evaluated the adverse events (AEs) of VEN from FDA Adverse Event Reporting System (FAERS) since its approval in 2016 by data mining.

METHODS

The disproportionality analyses, including four algorithms of reporting odd ratio (ROR), proportional reporting ratio (PRR), bayesian configuration promotion neural network (BCPNN), and multi item gamma poisson shrinker (MGPS), were employed to quantify the signals of VEN-associated AEs.

RESULTS

From the FAERS database, a total of 8,379,682 reports were collected during the study period. After removing the duplication, the number of reports with VEN as the primary suspect (PS) was 19,107. The 19,107 cases of AEs involved 27 organ systems, 256 significant PTs which conforming to the four algorithms. Unexpected serious AEs, such as pleural effusion, splenic infarction, atrial fibrillation, skin squamous cell carcinoma, etc., have signals. The median time of occurrence of AEs related to VEN was 31 days (inter quartile range [IQR] 7-131 days), and half of the reported AEs occurred within 1 month after administration.

CONCLUSION

Our research has found new significant AEs signals of VEN, which improved its safety information in real-world after marketing approval, and contributed to its risk control of use in clinic.

Targeting Ca2+ and Mitochondrial Homeostasis by Antipsychotic Thioridazine in Leukemia Cells

Mitochondria have pivotal roles in cellular physiology including energy metabolism, reactive oxygen species production, Ca2+ homeostasis, and apoptosis. Altered mitochondrial morphology and function is a common feature of cancer cells and the regulation of mitochondrial homeostasis has been identified as a key to the response to chemotherapeutic agents in human leukemias. Here, we explore the mechanistic aspects of cytotoxicity produced by thioridazine (TR), an antipsychotic drug that has been investigated for its anticancer potential in human leukemia cellular models. TR exerts selective cytotoxicity against human leukemia cells in vitro. A PCR array provided a general view of the expression of genes involved in cell death pathways. TR immediately produced a pulse of cytosolic Ca2+, followed by mitochondrial uptake, resulting in mitochondrial permeabilization, caspase 9/3 activation, endoplasmic reticulum stress, and apoptosis. Ca2+ chelators, thiol reducer dithiothreitol, or CHOP knockdown prevented TR-induced cell death. TR also exhibited potent cytotoxicity against BCL-2/BCL-xL-overexpressing leukemia cells. Additionally, previous studies have shown that TR exhibits potent antitumor activity in vivo in different solid tumor models. These findings show that TR induces a Ca2+-mediated apoptosis with involvement of mitochondrial permeabilization and ER stress in leukemia and it emphasizes the pharmacological potential of TR as an adjuvant in antitumor chemotherapy.

The molecular biology and therapeutic potential of Nrf2 in leukemia

NF-E2-related factor 2 (Nrf2) transcription factor has contradictory roles in cancer, which can act as a tumor suppressor or a proto-oncogene in different cell conditions (depending on the cell type and the conditions of the cell environment). Nrf2 pathway regulates several cellular processes, including signaling, energy metabolism, autophagy, inflammation, redox homeostasis, and antioxidant regulation. As a result, it plays a crucial role in cell survival. Conversely, Nrf2 protects cancerous cells from apoptosis and increases proliferation, angiogenesis, and metastasis. It promotes resistance to chemotherapy and radiotherapy in various solid tumors and hematological malignancies, so we want to elucidate the role of Nrf2 in cancer and the positive point of its targeting. Also, in the past few years, many studies have shown that Nrf2 protects cancer cells, especially leukemic cells, from the effects of chemotherapeutic drugs. The present paper summarizes these studies to scrutinize whether targeting Nrf2 combined with chemotherapy would be a therapeutic approach for leukemia treatment. Also, we discussed how Nrf2 and NF-κB work together to control the cellular redox pathway. The role of these two factors in inflammation (antagonistic) and leukemia (synergistic) is also summarized.

Progress in understanding the mechanisms of resistance to BCL-2 inhibitors

Venetoclax is a new type of BH3 mimetic compound that can target the binding site in the BCL-2 protein and induce apoptosis in cancer cells by stimulating the mitochondrial apoptotic pathway. Venetoclax is especially used to treat haematological malignancies. However, with the recent expansion in the applications of venetoclax, some cases of venetoclax resistance have appeared, posing a major problem in clinical treatment. In this article, we explored several common mechanisms of venetoclax resistance. Increased expression of the antiapoptotic proteins MCL-1 and BCL-XL plays a key role in conferring cellular resistance to venetoclax. These proteins can bind to the released BIM in the context of venetoclax binding to BCL-2 and thus continue to inhibit mitochondrial apoptosis. Structural mutations in BCL-2 family proteins caused by genetic instability lead to decreased affinity for venetoclax and inhibit the intrinsic apoptosis pathway. Mutation or deletion of the BAX gene renders the BAX protein unable to anchor to the outer mitochondrial membrane to form pores. In addition to changes in BCL-2 family genes, mutations in other oncogenes can also confer resistance to apoptosis induced by venetoclax. TP53 mutations and the expansion of FLT3-ITD promote the expression of antiapoptotic proteins MCL-1 and BCL-XL through multiple signalling pathways, and interfere with venetoclax-mediated apoptosis processes depending on their affinity for BH3-only proteins. Finally, the level of mitochondrial oxidative phosphorylation in venetoclax-resistant leukaemia stem cells is highly abnormal. Not only the metabolic pathways but also the levels of important metabolic components are changed, and all of these alterations antagonize the venetoclax-mediated inhibition of energy metabolism and promote the survival and proliferation of leukaemia stem cells. In addition, venetoclax can change mitochondrial morphology independent of the BCL-2 protein family, leading to mitochondrial dysfunction. However, mitochondria resistant to venetoclax antagonize this effect, forming tighter mitochondrial cristae, which provide more energy for cell survival.

J. PB, Larsen P, Taylor RE, Zhang J. Molecular mechanisms by which splice modulator GEX1A inhibits leukaemia development and progression

INTRODUCTION

Splice modulators have been assessed clinically in treating haematologic malignancies exhibiting splice factor mutations and acute myeloid leukaemia. However, the mechanisms by which such modulators repress leukaemia remain to be elucidated.

OBJECTIVES

The primary goal of this assessment was to assess the molecular mechanism by which the natural splice modulator GEX1A kills leukaemic cells in vitro and within in vivo mouse models.

METHODS

Using human leukaemic cell lines, we assessed the overall sensitivity these cells have to GEX1A via EC₅₀ analysis. We subsequently analysed its effects using in vivo xenograft mouse models and examined whether cell sensitivities were correlated to genetic characteristics or protein expression levels. We also utilised RT-PCR and RNAseq analyses to determine splice change and RNA expression level differences between sensitive and resistant leukaemic cell lines.

RESULTS

We found that, in vitro, GEX1A induced an MCL-1 isoform shift to pro-apoptotic MCL-1S in all leukaemic cell types, though sensitivity to GEX1A-induced apoptosis was negatively associated with BCL-xL expression. In BCL-2-expressing leukaemic cells, GEX1A induced BCL-2-dependent apoptosis by converting pro-survival BCL-2 into a cell killer. Thus, GEX1A + selective BCL-xL inhibition induced synergism in killing leukaemic cells, while GEX1A + BCL-2 inhibition showed antagonism in BCL-2-expressing leukaemic cells. In addition, GEX1A sensitised FLT3-ITD⁺ leukaemic cells to apoptosis by inducing aberrant splicing and repressing the expression of FLT3-ITD. Consistently, in in vivo xenografts, GEX1A killed the bulk of leukaemic cells via apoptosis when combined with BCL-xL inhibition. Furthermore, GEX1A repressed leukaemia development by targeting leukaemia stem cells through inhibiting FASTK mitochondrial isoform expression across sensitive and non-sensitive leukaemia types.

CONCLUSION

Our study suggests that GEX1A is a potent anti-leukaemic agent in combination with BCL-xL inhibitors, which targets leukaemic blasts and leukaemia stem cells through distinct mechanisms.

Druggable Molecular Pathways in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL), the most common type of leukemia in adults, is characterized by a high degree of clinical heterogeneity that is influenced by the disease’s molecular complexity. The genes most frequently affected in CLL cluster into specific biological pathways, including B-cell receptor (BCR) signaling, apoptosis, NF-κB, and NOTCH1 signaling. BCR signaling and the apoptosis pathway have been exploited to design targeted medicines for CLL therapy. Consistently, molecules that selectively inhibit specific BCR components, namely Bruton tyrosine kinase (BTK) and phosphoinositide 3-kinase (PI3K) as well as inhibitors of BCL2, have revolutionized the therapeutic management of CLL patients. Several BTK inhibitors and PI3K inhibitors with different modes of action are currently used or are in development in advanced stage clinical trials. Moreover, the restoration of apoptosis by the BCL2 inhibitor venetoclax offers meaningful clinical activity with a fixed-duration scheme. Inhibitors of the BCR and of BCL2 are able to overcome the chemorefractoriness associated with high-risk genetic features, including TP53 disruption. Other signaling cascades involved in CLL pathogenesis, in particular NOTCH signaling and NF-kB signaling, already provide biomarkers for a precision medicine approach to CLL and may represent potential druggable targets for the future. The aim of the present review is to discuss the druggable pathways of CLL and to provide the biological background of the high efficacy of targeted biological drugs in CLL.

Synergistic effect of chidamide and venetoclax on apoptosis in acute myeloid leukemia cells and its mechanism

Background

Acute myeloid leukemia (AML) is a hematological malignancy with a low remission rate and high recurrence rate. Overexpression of the antiapoptotic protein Bcl-2 is associated with a lower overall survival rate in AML patients. Venetoclax (ABT199) is a selective inhibitor of Bcl-2 that has a significant effect in AML, but single-drug resistance often occurs due to the high expression of Mcl-1 protein. Studies have confirmed that chidamide can downregulate the expression levels of Bcl-2 and Mcl-1 and induce apoptosis.

Methods

This study aimed to use AML cell lines and primary cells to study the effects of venetoclax and chidamide combination therapy on AML cell apoptosis, the cell cycle, and changes in related signaling pathways in vitro; establish an AML mouse model to observe the efficacy and survival time of combination therapy in vivo; and analyze the drug effects with multi-omics sequencing technology. The changes in gene and protein expression before and after treatment were examined to clarify the molecular mechanism driving the synergistic effect of the two drugs.

Results

(I) Both venetoclax and chidamide promoted apoptosis in AML cell lines and primary cells in a time- and concentration-dependent manner. The effect was further enhanced when the two drugs were combined, and a synergistic effect was observed (combination index <1). (II) At both the mRNA and protein levels, the expression of Mcl-1 was upregulated by venetoclax and downregulated by chidamide, and the expression of Mcl-1 decreased further after combination treatment. (III) Transcriptome sequencing showed that differentially expressed genes in the combination group compared with the venetoclax monotherapy group were mainly enriched in the PI3K-AKT pathway and JAK2/STAT3 pathway. Moreover, qRT-PCR and Western blot confirmed these results. (IV) The combination therapy group exhibited significantly inhibited disease progression and a prolonged survival time among AML mice.

Conclusions

Chidamide combined with venetoclax synergistically promoted apoptosis in AML cell lines and primary cells by inhibiting activation of the PI3K/AKT pathway and JAK2/STAT3 pathway.

BH3-mimetics: recent developments in cancer therapy

The hopeful outcomes from 30 years of research in BH3-mimetics have indeed served a number of solid paradigms for targeting intermediates from the apoptosis pathway in a variety of diseased states. Not only have such rational approaches in drug design yielded several key therapeutics, such outputs have also offered insights into the integrated mechanistic aspects of basic and clinical research at the genetics level for the future. In no other area of medical research have the effects of such work been felt, than in cancer research, through targeting the BAX-Bcl-2 protein-protein interactions. With these promising outputs in mind, several mimetics, and their potential therapeutic applications, have also been developed for several other pathological conditions, such as cardiovascular disease and tissue fibrosis, thus highlighting the universal importance of the intrinsic arm of the apoptosis pathway and its input to general tissue homeostasis. Considering such recent developments, and in a field that has generated so much scientific interest, we take stock of how the broadening area of BH3-mimetics has developed and diversified, with a focus on their uses in single and combined cancer treatment regimens and recently explored therapeutic delivery methods that may aid the development of future therapeutics of this nature.

Stress Relief Techniques: p38 MAPK Determines the Balance of Cell Cycle and Apoptosis Pathways

Protein signaling networks are formed from diverse and inter-connected cell signaling pathways converging into webs of function and regulation. These signaling pathways both receive and conduct molecular messages, often by a series of post-translation modifications such as phosphorylation or through protein-protein interactions via intrinsic motifs. The mitogen activated protein kinases (MAPKs) are components of kinase cascades that transmit signals through phosphorylation. There are several MAPK subfamilies, and one subfamily is the stress-activated protein kinases, which in mammals is the p38 family. The p38 enzymes mediate a variety of cellular outcomes including DNA repair, cell survival/cell fate decisions, and cell cycle arrest. The cell cycle is itself a signaling system that precisely controls DNA replication, chromosome segregation, and cellular division. Another indispensable cell function influenced by the p38 stress response is programmed cell death (apoptosis). As the regulators of cell survival, the BCL2 family of proteins and their dynamics are exquisitely sensitive to cell stress. The BCL2 family forms a protein-protein interaction network divided into anti-apoptotic and pro-apoptotic members, and the balance of binding between these two sides determines cell survival. Here, we discuss the intersections among the p38 MAPK, cell cycle, and apoptosis signaling pathways.

Targeting Bcl-2 for cancer therapy

Apoptosis deficiency is one of the most important features observed in neoplastic diseases. The Bcl-2 family is composed of a subset of proteins that act as decisive apoptosis regulators. Research and clinical studies have both demonstrated that the hyperactivation of Bcl-2-related anti-apoptotic effects correlates with cancer occurrence, progression and prognosis, also having a role in facilitating the radio- and chemoresistance of various malignancies. Therefore, targeting Bcl-2 inactivation has provided some compelling therapeutic advantages by enhancing apoptotic sensitivity or reversing drug resistance. Therefore, this pharmacological route turned into one of the most promising routes for cancer treatment. This review discusses some of the well-defined and emerging roles of Bcl-2 as well as its potential clinical value in cancer therapeutics.

Tumor-targeted nanoparticles improve the therapeutic index of BCL2 and MCL1 dual inhibition

Cancer and normal cells use multiple antiapoptotic BCL2 proteins to prevent cell death. Therapeutic targeting of multiple BCL2 family proteins enhances tumor killing but is also associated with increased systemic toxicity. Here, we demonstrate that the dual targeting of MCL1 and BCL2 proteins using the small molecules S63845 and venetoclax induces durable remissions in mice that harbor human diffuse large B-cell lymphoma (DLBCL) tumors but is accompanied by hematologic toxicity and weight loss. To mitigate these toxicities, we encapsulated S63845 or venetoclax into nanoparticles that target P-selectin, which is enriched in tumor endothelial cells. In vivo and ex vivo imaging demonstrated preferential targeting of the nanoparticles to lymphoma tumors over vital organs. Mass spectrometry analyses after administration of nanoparticle drugs confirmed tumor enrichment of the drug while reducing plasma levels. Furthermore, nanoparticle encapsulation allowed 3.5- to 6.5-fold reduction in drug dose, induced sustained remissions, and minimized toxicity. Our results support the development of nanoparticles to deliver BH3 mimetic combinations in lymphoma and in general for toxic drugs in cancer therapy.

Venetoclax-rituximab with or without bendamustine vs bendamustine-rituximab in relapsed/refractory follicular lymphoma

This open-label phase 2 study (CONTRALTO) assessed the safety and efficacy of BCL-2 inhibitor venetoclax (VEN) plus rituximab (R), and VEN plus bendamustine (B) and R, vs B + R (BR) alone in relapsed/refractory (R/R) follicular lymphoma. Patients in the chemotherapy-free arm (arm A: VEN + R) received VEN 800 mg/d plus R 375 mg/m2 on days 1, 8, 15, and 22 of cycle 1 and day 1 of cycles 4, 6, 8, 10, and 12. After a safety run-in with VEN 600 mg, patients in the chemotherapy-containing cohort were randomized to either VEN + BR (arm B; VEN 800 mg/d for 1 year + 6 cycles of BR [B 90 mg/m2 on days 1 and 2 and R 375 mg/m2 on day 1]) or 6 cycles of BR (arm C). Overall, 163 patients were analyzed (9 in the safety run-in and 52, 51, and 51 in arms A, B, and C, respectively). Complete metabolic/complete response rates were 17% (arm A), 75% (arm B), and 69% (arm C). Of patients in arm B, only 61% received ≥90% of the planned B dose vs 96% of patients in arm C. More frequent hematologic toxicity resulted in more reduced dosing/treatment discontinuation in arm B vs arm C. Rates of grade 3/4 adverse events were 51.9%, 93.9%, and 60.0% in arms A, B, and C, respectively. VEN + BR led to increased toxicity and lower dose intensity of BR than in arm C, but efficacy was similar. Optimizing dose and schedule to maintain BR dose intensity may improve efficacy and tolerability of VEN + BR, while VEN + R data warrant further study. This study was registered at www.clinicaltrials.gov as #NCT02187861.

IKAROS and CK2 regulate expression of BCL-XL and chemosensitivity in high-risk B-cell acute lymphoblastic leukemia

High-risk B-cell acute lymphoblastic leukemia (B-ALL) is an aggressive disease, often characterized by resistance to chemotherapy. A frequent feature of high-risk B-ALL is loss of function of the IKAROS (encoded by the IKZF1 gene) tumor suppressor. Here, we report that IKAROS regulates expression of the BCL2L1 gene (encodes the BCL-XL protein) in human B-ALL. Gain-of-function and loss-of-function experiments demonstrate that IKAROS binds to the BCL2L1 promoter, recruits histone deacetylase HDAC1, and represses BCL2L1 expression via chromatin remodeling. In leukemia, IKAROS' function is impaired by oncogenic casein kinase II (CK2), which is overexpressed in B-ALL. Phosphorylation by CK2 reduces IKAROS binding and recruitment of HDAC1 to the BCL2L1 promoter. This results in a loss of IKAROS-mediated repression of BCL2L1 and increased expression of BCL-XL. Increased expression of BCL-XL and/or CK2, as well as reduced IKAROS expression, are associated with resistance to doxorubicin treatment. Molecular and pharmacological inhibition of CK2 with a specific inhibitor CX-4945, increases binding of IKAROS to the BCL2L1 promoter and enhances IKAROS-mediated repression of BCL2L1 in B-ALL. Treatment with CX-4945 increases sensitivity to doxorubicin in B-ALL, and reverses resistance to doxorubicin in multidrug-resistant B-ALL. Combination treatment with CX-4945 and doxorubicin show synergistic therapeutic effects in vitro and in preclinical models of high-risk B-ALL. Results reveal a novel signaling network that regulates chemoresistance in leukemia. These data lay the groundwork for clinical testing of a rationally designed, targeted therapy that combines the CK2 inhibitor, CX-4945, with doxorubicin for the treatment of hematopoietic malignancies.

Sustained high expression of NRF2 and its target genes induces dysregulation of cellular proliferation and apoptosis is associated with arsenite-induced malignant transformation of human bronchial epithelial cells

In arsenic toxicity, activation of the erythroid 2-related factor 2 (NRF2) pathway is regarded as a driver of cancer development and progression; however, the mechanisms by which NRF2 gene expression regulates cell cycle progression and mediates pathways of cellular proliferation and apoptosis in arsenic-induced lung carcinogenesis are poorly understood. In this study, we explored the regulatory functions of NRF2 expression and its target genes in immortalized human bronchial epithelial (HBE) cells continuously exposed to 1.0 μM sodium arsenite over approximately 43 passages (22 weeks). The experimental treatment induced malignant transformation in HBE cells, characterized by increased cellular proliferation and soft agar clone formation, as well as cell migration, and accelerated cell cycle progression from G0/G1 to S phase with increased levels of cyclin E-CDK2 complex,decreased cellular apoptosis rate. Moreover, we observed a sustained increase in NRF2 protein levels and those of its target gene products (NQO1, BCL-2) with concurrently decreased expression of apoptosis-related proteins (BAX, Cleaved-caspase-3/Caspase-3 and CHOP) and increased expression of the anti-apoptotic protein MCL-1. Silencing NRF2 expression with small interfering RNA (siRNA) in arsenite-transformed (T-HBE) cells was shown to reverse the malignant phenotype. Further, siRNA silencing of NQO1 significantly decreased levels of the cyclin E-CDK2 complex, inhibiting G0/G1 to S phase cell cycle progression and transformation to the T-HBE phenotypes. This study demonstrated a novel role for the NRF2/NQO1 signaling pathway in mediating arsenite-induced cell transformation by increasing the expression of cyclin E-CDK2, and accelerating the cell cycle and cell proliferation. Arsenite promotes activation of the NRF2/BCL-2 signaling pathway inhibited CHOP increasing cellular resistance to apoptosis and further promoting malignant transformation.

Chronic Lymphocytic Leukemia

Patients with chronic lymphocytic leukemia can be divided into three categories: those who are minimally affected by the problem, often never requiring therapy; those that initially follow an indolent course but subsequently progress and require therapy; and those that from the point of diagnosis exhibit an aggressive disease necessitating treatment. Likewise, such patients pass through three phases: development of the disease, diagnosis, and need for therapy. Finally, the leukemic clones of all patients appear to require continuous input from the exterior, most often through membrane receptors, to allow them to survive and grow. This review is presented according to the temporal course that the disease follows, focusing on those external influences from the tissue microenvironment (TME) that support the time lines as well as those internal influences that are inherited or develop as genetic and epigenetic changes occurring over the time line. Regarding the former, special emphasis is placed on the input provided via the B-cell receptor for antigen and the C-X-C-motif chemokine receptor-4 and the therapeutic agents that block these inputs. Regarding the latter, prominence is laid upon inherited susceptibility genes and the genetic and epigenetic abnormalities that lead to the developmental and progression of the disease.

Combination strategies to overcome resistance to the BCL2 inhibitor venetoclax in hematologic malignancies

Venetoclax has been approved by the United States Food and Drug Administration since 2016 as a monotherapy for treating patients with relapsed/refractory chronic lymphocytic leukemia having 17p deletion. It has led to a breakthrough in the treatment of hematologic malignancies in recent years. However, unfortunately, resistance to venetoclax is inevitable. Multiple studies confirmed that the upregulation of the anti-apoptotic proteins of the B-cell lymphoma 2 (BCL2) family mediated by various mechanisms, such as tumor microenvironment, and the activation of intracellular signaling pathways were the major factors leading to resistance to venetoclax. Therefore, only targeting BCL2 often fails to achieve the expected therapeutic effect. Based on the mechanism of resistance in specific hematologic malignancies, the combination of specific drugs with venetoclax was a clinically optional treatment strategy for overcoming resistance to venetoclax. This study aimed to summarize the possible resistance mechanisms of various hematologic tumors to venetoclax and the corresponding clinical strategies to overcome resistance to venetoclax in hematologic malignancies.

MicroRNA (MiR)-301a-3p regulates the proliferation of esophageal squamous cells via targeting PTEN

Human esophageal carcinoma (EC) is a common cancer, which leads to many deaths worldwide every year. Our study aimed to explore the mechanism of miR-301a-3p regulating the proliferation of esophageal squamous cell carcinoma (ESCC) cells. We had collected ESCC tissues and adjacent normal esophageal tissues from 47 patients. The relative levels of miR-301a-3p/U6 in ESCC tissues and cells were analyzed by real-time PCR. And we measured the relative protein levels of PTEN, BCL-2, BAX, and p-AKT/AKT by Western blot. Eca-109 cell proliferation was detected by MTT assay and colony formation. Compared with adjacent normal esophageal tissues, the relative level of miR-301a-3p/U6 was elevated in ESCC tissues. MiR-301a-3p could facilitate ESCC cell proliferation. And miR-301a-3p directly bind to PTEN 3ʹ-UTR and negatively regulated PTEN protein expression. Moreover, silencing PTEN could reversed inhibited proliferation of Eca-109 cells induced by miR-301a-3p inhibitor, while overexpression PTEN could reversed enhanced proliferation of Eca-109 cells induced by miR-301a-3p mimic. Taken together, miR-301a-3p promoted ESCC cell proliferation by supressing PTEN.

Combinatorial Inhibition of Focal Adhesion Kinase and BCL-2 Enhances Antileukemia Activity of Venetoclax in Acute Myeloid Leukemia

Focal adhesion kinase (FAK) promotes cancer cell growth and metastasis. We previously reported that FAK inhibition by the selective inhibitor VS-4718 exerted antileukemia activities in acute myeloid leukemia (AML). The mechanisms involved, and whether VS-4718 potentiates efficacy of other therapeutic agents, have not been investigated. Resistance to apoptosis inducted by the BCL-2 inhibitor ABT-199 (venetoclax) in AML is mediated by preexisting and ABT-199-induced overexpression of MCL-1 and BCL-XL. We observed that VS-4718 or silencing FAK with siRNA decreased MCL-1 and BCL-XL levels. Importantly, VS-4718 antagonized ABT-199-induced MCL-1 and BCL-XL. VS-4718 markedly synergized with ABT-199 to induce apoptosis in AML cells, including primary AML CD34+ cells and AML cells overexpressing MCL-1 or BCL-XL. In a patient-derived xenograft (PDX) model derived from a patient sample with NPM1/FLT3-ITD/TET2/DNMT3A/WT1 mutations and complex karyotype, VS-4718 statistically significantly reduced leukemia tissue infiltration and extended survival (72 vs. control 36 days, P = 0.0002), and only its combination with ABT-199 effectively decreased systemic leukemia tissue infiltration and circulating blasts, and prolonged survival (65.5 vs. control 36 days, P = 0.0119). Furthermore, the combination decreased NFκB signaling and induced the expression of IFN genes in vivo The combination also markedly extended survival of a second PDX model developed from an aggressive, TP53-mutated complex karyotype AML sample. The data suggest that the combined inhibition of FAK and BCL-2 enhances antileukemia activity in AML at least in part by suppressing MCL-1 and BCL-XL and that this combination may be effective in AML with TP53 and other mutations, and thus benefit patients with high-risk AML.

A small-molecule ARTS mimetic promotes apoptosis through degradation of both XIAP and Bcl-2

Many human cancers over-express B cell lymphoma 2 (Bcl-2) or X-linked inhibitor of apoptosis (IAP) proteins to evade cell death. The pro-apoptotic ARTS (Sept4_i2) protein binds directly to both Bcl-2 and XIAP and promotes apoptosis by stimulating their degradation via the ubiquitin-proteasome system (UPS). Here we describe a small molecule, A4, that mimics the function of ARTS. Microscale thermophoresis assays showed that A4 binds XIAP, but not cellular inhibitor of apoptosis protein 1 (cIAP1). A4 binds to a distinct ARTS binding pocket in the XIAP-BIR3 (baculoviral IAP repeat 3) domain. Like ARTS, A4 stimulated poly-ubiquitylation and UPS-mediated degradation of XIAP and Bcl-2, but not cIAP1, resulting in caspase-9 and -3 activation and apoptosis. In addition, over-expression of XIAP rescued HeLa cells from A4-induced apoptosis, consistent with the idea that A4 kills by antagonizing XIAP. On the other hand, treatment with the SMAC-mimetic Birinapant induced secretion of tumour necrosis factor-α (TNFα) and killed ~50% of SKOV-3 cells, and addition of A4 to Birinapant-treated cells significantly reduced secretion of TNFα and blocked Birinapant-induced apoptosis. This suggests that A4 acts by specifically targeting XIAP. The effect of A4 was selective as peripheral blood mononuclear cells and normal human breast epithelial cells were unaffected. Furthermore, proteome analysis revealed that cancer cell lines with high levels of XIAP were particularly sensitive to the killing effect of A4. These results provide proof of concept that the ARTS binding site in XIAP is "druggable". A4 represents a novel class of dual-targeting compounds stimulating apoptosis by UPS-mediated degradation of important anti-apoptotic oncogenes.

miR-519 regulates the proliferation of breast cancer cells via targeting human antigen R

Breast cancer is one of the most prevalent types of cancer among women that leads to millions of deaths worldwide every year. The mechanisms of breast cancer pathogenesis remain unclear. It has been reported that aberrant expression of miR-519, is associated with breast cancer development; however, the effects of miR-519 on breast cancer cell proliferation remain unknown. Therefore, the present study aimed to determine whether miR-519 could regulate breast cancer cell proliferation. A total of 20 pairs of primary breast cancer and adjacent normal tissues were collected from patients with breast cancer. miR-519 expression level was determined by reverse transcription-quantitative polymerase chain reaction. Furthermore, miR-519 mimics or inhibitors were transfected into breast cancer MCF-7 cells in order to up- or downregulate miR-519 expression. Subsequently, human antigen R (HUR), BCL-2 and BAX protein levels were analyzed by western blotting. MCF-7 cell proliferation was assessed using MTT and colony formation assays. A luciferase assay was performed to verify whether miR-519 could directly bind to HUR mRNA. The results demonstrated that miR-519 expression level was lower in primary breast cancer tissues compared with adjacent normal tissues. Furthermore, miR-519 overexpression and downregulation inhibited and stimulated MCF-7 cell proliferation, respectively. In addition, the results from luciferase assay demonstrated that HUR was a target of miR-519. HUR overexpression could reverse the effect of miR-519 mimics on MCF-7 cell proliferation, whereas HUR silencing could rescue the effect of miR-519 inhibitors on MCF-7 cell proliferation. These findings suggested that miR-519 may regulate MCF-7 cell proliferation by targeting HUR.

Effect of nucleolin on adriamycin resistance via the regulation of B-cell lymphoma 2 expression in Burkitt's lymphoma cells

Nucleolin (NCL, C23) is an important nucleocytoplasmic multifunctional protein. Due to its multifaceted profile and high expression in cancer, NCL is considered to be a marker of drug resistance associated with chemotherapy. However, the biochemical mechanisms in which NCL suppresses drug sensitivity in several cancers have yet to be fully elucidated. This study aims to explore the effect of NCL on drug sensitivity and its potential mechanism in CA46 Burkitt's lymphoma (BL) cells. CA46 BL cells were transfected with lentiviruses carrying the NCL gene (CA46-NCL-overexpression, CA46-NCL-OE), or shRNA sequences that target the endogenous NCL gene (CA46-NCL-knockdown, CA46-NCL-KD). Adriamycin (ADM) IC50 levels for CA46-NCL-overexpressed (OE), CA46-NCL-OE control (OEC), CA46-NCL-knockdown (KD), and CA46-NCL-KD control (KDC) cells were 0.68 ± 0.06 μg/ml, 0.68 ± 0.06 μg/ml, 0.68 ± 0.06 μg/ml, and 0.30 ± 0.04 μg/ml, respectively. Apoptosis rates were significantly increased following NCL KD, whereas the opposite effect was noted in OE cells. A significant reduction of B-cell lymphoma 2 (Bcl-2) mRNA and protein levels in KD cells was observed, while OE cells displayed the opposite effect. The stability of Bcl-2 mRNA was influenced by NCL levels, the half-life of which was extended after NCL-OE, whereas it was reduced in KD cells. Finally, results of RNA-immunoprecipitation assays indicated that NCL could bind to Bcl-2 mRNA in CA46 cells. Taken together, these results suggested that NCL could mediate Bcl-2 expression and stability, and thus enhance ADM resistance in CA46 BL cells.

The Anticancer Activity of Lycium barbarum Polysaccharide by Inhibiting Autophagy in Human Skin Squamous Cell Carcinoma Cells In Vitro and In Vivo

Objective. This study is aimed at investigating the effects of Lycium barbarum polysaccharide (LBP) on the proliferation and apoptosis of human cutaneous squamous cell carcinoma A431 cells in vitro and in vivo via its regulation on autophagy. Methods. In vitro experiment: A431 cells were treated with different concentrations of LBP, and cell viability was measured by the CCK8 method. Flow cytometry was used to detect the cell apoptosis rate. The expression of Ki67, PCNA, cl-caspase-3, Bcl-2, and LC3II and the phosphorylation status of JNK and ERK1/2, as well as the effect of SP600125 cotreatment on the expression of autophagy and apoptosis-associated proteins, were determined via Western blot. In vivo experiment: a transplanted tumor model was established by subcutaneous injection of A431 cells to the nude mice. 50 mg/kg LBP was injected into the mice intraperitoneally; the survival rate of mice, volume, and weight of tumor were determined on the 30th day. The expression of Ki67 and MMP-2 proteins was measured by immunohistochemistry. Results. LBP at concentrations of 400 μg/ml and above was significantly cytotoxic to A431 cells, whereas, within the dose range of 50 μg/ml~200 μg/ml, LBP significantly inhibited the expression of Ki67 and PCNA proteins, promoted the expression of cl-caspase-3, inhibited the expression of Bcl-2 protein, downregulated the expression of autophagy marker LC3II, and reduced the phosphorylation of ERK1/2, whereas the level of JNK phosphorylation was upregulated. At the same time, the regulation of Beclin1, LC3II, Bcl-2, and cl-caspase-3 by LBP was effectively reversed by the cotreatment of SP600125. In addition, LBP increased the survival rate of transplanted nude mice, reduced tumor volume and weight, and downregulated the expression of Ki67 and MMP-2. Conclusion. LBP can induce apoptosis of A431 cells by inhibiting autophagy and can inhibit tumor growth in vivo.

BCL2L12 improves risk stratification and prediction of BFM-chemotherapy response in childhood acute lymphoblastic leukemia

Background Risk-adjusted treatment has led to outstanding improvements of the remission and survival rates of childhood acute lymphoblastic leukemia (ALL). Nevertheless, overtreatment-related toxicity and resistance to therapy have not been fully prevented. In the present study, we evaluated for the first time the clinical impact of the apoptosis-related BCL2L12 gene in prognosis and risk stratification of BFM-treated childhood ALL. Methods Bone marrow specimens were obtained from childhood ALL patients upon disease diagnosis and the end-of-induction (EoI; day 33) of the BFM protocol, as well as from control children. Following total RNA extraction and reverse transcription, BCL2L12 expression levels were determined by qPCR. Patients' cytogenetics, immunophenotyping and minimal residual disease (MRD) evaluation were performed according to the international guidelines. Results BCL2L12 expression was significantly increased in childhood ALL and correlated with higher BCL2/BAX expression ratio and favorable disease markers. More importantly, BCL2L12 expression was associated with disease remission, while the reduced BCL2L12 expression was able to predict patients' poor response to BFM therapy, in terms of M2-M3 response and MRD≥0.1% on day 15. The survival analysis confirmed the significantly higher risk of the BFM-treated patients underexpressing BCL2L12 at disease diagnosis for early relapse and worse survival. Lastly, evaluation of BCL2L12 expression clearly strengthened the prognostic value of the established disease prognostic markers, leading to superior prediction of patients' outcome and improved specificity of BFM risk stratification. Conclusions The expression levels of the apoptosis-related BCL2L12 predict response to treatment and survival outcome of childhood ALL patients receiving BFM chemotherapy.

Current overview on the clinical update of Bcl-2 anti-apoptotic inhibitors for cancer therapy

Apoptosis is one of the major mechanisms exhibited in response to cell death and induction of apoptosis in tumour cells signifies a potential target for cancer therapy. Bcl-2 family proteins play a key role in regulation of the apoptotic pathway. Bcl-2 overexpression is commonly associated with various cancers including breast cancer, prostate cancer, B-cell lymphomas and colorectal adenocarcinomas etc. Thus, Bcl-2 is a novel anti-cancer target attracting medicinal chemists across the globe. Research investigations underlying Bcl-2 target have resulted in the generation of small molecule inhibitors, named as 'BH3-mimetics' (Bcl-2 homology 3 mimetics). These drugs display binding to pro-survival Bcl-2 proteins resulting in actuation of apoptosis of cancer cells. The first BH3 mimetics discovered as an outcome of structure-based drug design and Nuclear Magnetic Resonance (NMR)-based screening was ABT-263, an N-acylsulfonamide analogue. Thrombocytopenia a major dose-limiting toxicity, associated with ABT-263 had provoked the invention of a highly selective Bcl-2 inhibitor venetoclax. Several Bcl-2 inhibitors as small molecules are under clinical development and the results indicated that these molecules alone or in combination could be of potential application in cancer therapy. This review summarizes an up to date knowledge of the available small molecule inhibitors, their discovery, synthesis, current clinical and pre-clinical status.

Lycopene protects against myocardial ischemia-reperfusion injury by inhibiting mitochondrial permeability transition pore opening

Background

Mitochondria permeability transition pore (MPTP) is an important therapeutic target for myocardial ischemia-reperfusion injury (MIRI). Lycopene (LP) is a potent antioxidant extracted from the mature fruits of plants and has been reported to protect against MIRI; however, its mechanism of action has yet to be completely elucidated. The present study aimed to investigate the role of MPTP in the cardioprotection of LP.

Methods

H9c2 cells were pretreated with LP for 12 hrs and were subjected to 12-hr hypoxia/1-hr re-oxygenation, and cell viability was measured by a Cell Counting Kit-8 (CCK-8) assay. Male rats were subsequently intraperitoneally injected with LP for 5 consecutive days. At 24 hrs following the final injection, the rat hearts were isolated and subjected to 30-min ischemia/120-min reperfusion using Langendorff apparatus. The myocardial infarct size was measured by a TTC stain. Opening of the MPTP was induced by CaCl₂ and measured by colorimetry. The change in mitochondrial transmembrane potential (ΔΨm) was observed under a fluorescence microscope. Apoptosis was measured by flow cytometry and a TUNEL stain, and the expression of apoptosis-related proteins was detected by Western blotting.

Results

LP pretreatment significantly increased cell viability, reduced myocardial infarct size and decreased the apoptosis rate. In addition, opening and the decrease of ΔΨm were attenuated by LP and the expressions of cytochrome c, APAF-1, cleaved caspase-9 and cleaved caspase-3 were also decreased by LP. However, these beneficial effects on MIRI were abrogated by the MPTP opener (atractyloside). Furthermore, LP treatment markedly increased Bcl-2 expression, decreased Bax expression and the Bax/Bcl-2 ratio.

Conclusion

The results of the present study demonstrated that LP protects against MIRI by inhibiting MPTP opening, partly through the modulation of Bax and Bcl-2.

Exploiting Mitochondrial Vulnerabilities to Trigger Apoptosis Selectively in Cancer Cells

The transformation of normal cells to the cancerous stage involves multiple genetic changes or mutations leading to hyperproliferation, resistance to apoptosis, and evasion of the host immune system. However, to accomplish hyperproliferation, cancer cells undergo profound metabolic reprogramming including oxidative glycolysis and acidification of the cytoplasm, leading to hyperpolarization of the mitochondrial membrane. The majority of drug development research in the past has focused on targeting DNA replication, repair, and tubulin polymerization to induce apoptosis in cancer cells. Unfortunately, these are not cancer-selective targets. Recently, researchers have started focusing on metabolic, mitochondrial, and oxidative stress vulnerabilities of cancer cells that can be exploited as selective targets for inducing cancer cell death. Indeed, the hyperpolarization of mitochondrial membranes in cancer cells can lead to selective importing of mitocans that can induce apoptotic effects. Herein, we will discuss recent mitochondrial-selective anticancer compounds (mitocans) that have shown selective toxicity against cancer cells. Increased oxidative stress has also been shown to be very effective in selectively inducing cell death in cancer cells. This oxidative stress could lead to mitochondrial dysfunction, which in turn will produce more reactive oxygen species (ROS). This creates a vicious cycle of mitochondrial dysfunction and ROS production, irreversibly leading to cell suicide. We will also explore the possibility of combining these compounds to sensitize cancer cells to the conventional anticancer agents. Mitocans in combination with selective oxidative-stress producing agents could be very effective anticancer treatments with minimal effect on healthy cells.

A transcriptional signature associated with non-Hodgkin lymphoma in the blood of patients with Q fever

Coxiella burnetii, the agent causing Q fever, has been associated with B-cell non-Hodgkin lymphoma (NHL). To better clarify this link, we analysed the genetic transcriptomic profile of peripheral blood leukocytes from patients with C. burnetii infection to identify possible links to lymphoma. Microarray analyses revealed that 1189 genes were expressed differently (p <.001 and fold change ≥4) in whole blood of patients with C. burnetii infection compared to controls. In addition, 95 genes expressed in patients with non-Hodgkin lymphoma (NHL) and in patients with C. burnetii persistent infection have allowed us to establish the 'C. burnetii-associated NHL signature'. Among these, 33 genes previously found modulated in C. burnetii-associated -NHL by the microarray analysis were selected and their mRNA expression levels were measured in distinct C. burnetii-induced pathologies, namely, acute Q fever, focalized persistent infection, lymphadenitis and C.burnetii-associated NHL. Specific genes involved in anti-apoptotic process were found highly expressed in leukocytes from patients with C. burnetii associated-NHL: MIR17HG, REL and SP100. This signature differed from that found for NHL-control group. Patients with C. burnetii lymphadenitis presented significant elevated levels of BCL2 and ETS1 mRNAs. Altogether, we identified a specific transcriptionnal signature for NHL during C. burnetii infection reflecting the up-regulation of anti-apoptotic processes and the fact that lymphadenitis might constitute a critical step towards lymphomagenesis.

Ethyl Acetate Extract of Asclepias curassavica Induced Apoptosis in Human Cancer Cells via Activating p38 and JNK MAPK Signaling Pathways

Background. Asclepias curassavica L. (Asclepiadaceae), as a traditional medicinal plant, is used as treatment for tumors in traditional Chinese and Indian medical practice. However, its underlying molecular mechanisms remain largely unresolved. The current study investigated its antitumor activity and the underlying molecular mechanisms. Method. Cell viability was detected by a real-time cell analysis system and MTT assay. Antitumor effect of ethyl acetate extract of Asclepias curassavica (EAAC) on NIC-H1975 tumors in vivo was assessed in BALB/c-nu/nu mouse. Apoptosis was measured using Hoechst33342 staining and Annexin V/PI-staining. Apoptosis-related proteins and MAPK signaling pathways were analyzed based on Western blot assay. Results. EAAC exhibited the highest cytotoxic activity in vitro than other polar parts. Meanwhile, EAAC could inhibit sensitive cell line NIC-H1975 proliferation in a concentration-dependent and time-dependent manner. Furthermore, EAAC had a significant inhibitory effect on NIC-H1975 tumor growth in BALB/c-nu/nu mouse. NIC-H1975 cells showed obvious apoptosis characteristics after EAAC treatment. Fas, caspase family members caspase 3, caspase 9, and caspase 8 showed dose-dependent induction by EAAC treatment, with increasing PARP cleavage. Additionally, EAAC significantly downregulated antiapoptotic proteins Bcl-2, XIAP, survivin, and Mcl-1 and upregulated proapoptosis proteins Bak, Bax, as well as activation of p38 and JNK MAPK signaling pathways. Moreover, inhibiting p38 and JNK MAPK by pharmacological inhibitors abrogated EAAC-induced apoptosis. Conclusion. Our data indicated that EAAC exerted potent antitumor effect both in vitro and in vivo by triggering the apoptotic pathway.

BCL2 Amplicon Loss and Transcriptional Remodeling Drives ABT-199 Resistance in B Cell Lymphoma Models

Drug-tolerant "persister" tumor cells underlie emergence of drug-resistant clones and contribute to relapse and disease progression. Here we report that resistance to the BCL-2 targeting drug ABT-199 in models of mantle cell lymphoma and double-hit lymphoma evolves from outgrowth of persister clones displaying loss of 18q21 amplicons that harbor BCL2. Further, persister status is generated via adaptive super-enhancer remodeling that reprograms transcription and offers opportunities for overcoming ABT-199 resistance. Notably, pharmacoproteomic and pharmacogenomic screens revealed that persisters are vulnerable to inhibition of the transcriptional machinery and especially to inhibition of cyclin-dependent kinase 7 (CDK7), which is essential for the transcriptional reprogramming that drives and sustains ABT-199 resistance. Thus, transcription-targeting agents offer new approaches to disable drug resistance in B-cell lymphomas.

Regulating the BCL2 Family to Improve Sensitivity to Microtubule Targeting Agents

Chemotherapeutic targeting of microtubules has been the standard of care in treating a variety of malignancies for decades. During mitosis, increased microtubule dynamics are necessary for mitotic spindle formation and successful chromosomal segregation. Microtubule targeting agents (MTAs) disrupt the dynamics necessary for successful spindle assembly and trigger programmed cell death (apoptosis). As the critical regulators of apoptosis, anti-apoptotic BCL2 family members are often amplified during carcinogenesis that can result in MTA resistance. This review outlines how BCL2 family regulation is positioned within the context of MTA treatment and explores the potential of combination therapy of MTAs with emerging BCL2 family inhibitors.

Superior efficacy of cotreatment with BET protein inhibitor and BCL2 or MCL1 inhibitor against AML blast progenitor cells

First-generation bromodomain extra-terminal protein (BETP) inhibitors (BETi) (e.g., OTX015) that disrupt binding of BETP BRD4 to chromatin transcriptionally attenuate AML-relevant progrowth and prosurvival oncoproteins. BETi treatment induces apoptosis of AML BPCs, reduces in vivo AML burden and induces clinical remissions in a minority of AML patients. Clinical efficacy of more potent BETis, e.g., ABBV-075 (AbbVie, Inc.), is being evaluated. Venetoclax and A-1210477 bind and inhibit the antiapoptotic activity of BCL2 and MCL1, respectively, lowering the threshold for apoptosis. BETi treatment is shown here to perturb accessible chromatin and activity of enhancers/promoters, attenuating MYC, CDK6, MCL1 and BCL2, while inducing BIM, HEXIM1, CDKN1A expressions and apoptosis of AML cells. Treatment with venetoclax increased MCL1 protein levels, but cotreatment with ABBV-075 reduced MCL1 and Bcl-xL levels. ABBV-075 cotreatment synergistically induced apoptosis with venetoclax or A-1210477 in patient-derived, CD34+ AML cells. Compared to treatment with either agent alone, cotreatment with ABBV-075 and venetoclax was significantly more effective in reducing AML cell-burden and improving survival, without inducing toxicity, in AML-engrafted immune-depleted mice. These findings highlight the basis of superior activity and support interrogation of clinical efficacy and safety of cotreatment with BETi and BCL2 or MCL1 inhibitor in AML.

Identification and Validation of Core Genes Involved in the Development of Papillary Thyroid Carcinoma via Bioinformatics Analysis

BACKGROUND

Papillary thyroid carcinoma (PTC) is a common endocrine malignant neoplasm, and its incidence increases continuously worldwide in the recent years. However, efficient clinical biomarkers were still deficient; the present research is aimed at exploring significant core genes of PTC.

METHODS

We integrated three cohorts to identify hub genes and pathways associated with PTC by comprehensive bioinformatics analysis. Expression profiles GSE33630, GSE35570, and GSE60542, including 114 PTC tissues and 126 normal tissues, were enrolled in this research. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were utilized to search for the crucial biological behaviors and pathways involved in PTC carcinogenesis. Protein-protein interaction (PPI) network was constructed, and significant modules were deeply studied.

RESULTS

A total of 831 differentially expressed genes (DEGs) were discovered, comprising 410 upregulated and 421 downregulated genes in PTC tissues compared to normal thyroid tissues. PPI network analysis demonstrated the interactions between those DEGs, and top 10 pivotal genes (TGFB1, CXCL8, LRRK2, CD44, CCND1, JUN, DCN, BCL2, ACACB, and CXCL12) with highest degree of connectivity were extracted from the network and verified by TCGA dataset and RT-PCR experiment of PTC samples. Four of the hub genes (CXCL8, DCN, BCL2, and ACACB) were linked to the prognosis of PTC patients and considered as clinically relevant core genes via survival analysis.

CONCLUSION

In conclusion, we propose a series of key genes associated with PTC development and these genes could serve as the diagnostic biomarkers or therapeutic targets in the future treatment for PTC.

PLK1 stabilizes a MYC-dependent kinase network in aggressive B cell lymphomas

Concordant activation of MYC and BCL-2 oncoproteins in double-hit lymphoma (DHL) results in aggressive disease that is refractory to treatment. By integrating activity-based proteomic profiling and drug screens, polo-like kinase-1 (PLK1) was identified as an essential regulator of the MYC-dependent kinome in DHL. Notably, PLK1 was expressed at high levels in DHL, correlated with MYC expression, and connoted poor outcome. Further, PLK1 signaling augmented MYC protein stability, and in turn, MYC directly induced PLK1 transcription, establishing a feed-forward MYC-PLK1 circuit in DHL. Finally, inhibition of PLK1 triggered degradation of MYC and of the antiapoptotic protein MCL-1, and PLK1 inhibitors showed synergy with BCL-2 antagonists in blocking DHL cell growth, survival, and tumorigenicity, supporting clinical targeting of PLK1 in DHL.

Targeting dipeptidyl peptidase 8 genes inhibits proliferation, migration and invasion by inhibition of cyclin D1 and MMP2MMP9 signal pathway in cervical cancer

BACKGROUND

DPP8 is a member of the dipeptidyl peptidase IV family, which belongs to the S9b protease subfamily. It regulates cell proliferation, apoptosis, migration and invasion during cancer progression.

METHODS

To investigate the role of DPP8 in cervical cancer, we examined DPP8 levels in cervical cancer tissues and cells. The localization of DPP8 was determined by immunofluorescence staining. Subsequently, SiHa and HeLa cells were treated with small interfering RNA (siRNA)-DPP8. We used cell cycle analysis, an 5-ethyl-2'-deoxyuridine assay proliferation assay and a cellular apoptosis assay to determine the effect of DPP8 on the proliferation and apoptosis of cervical cancer cells. We used a Transwell assay to assess the number of transfection cancer cells migrating through the matrix. A real-time polymerase chain reaction and western blot analysis were used to analyze the expression of related proteins and to determine the phenotype caused by the depletion or overexpression of DPP8 in cervical cancer cells.

RESULTS

We observed that DPP8 was highly expressed in cervical cancer tissues and cells. DPP8 expression was observed in the cytosol and in the perinuclear area, as well as in the nuclei of cervical cancer cells. Notably, when cells were treated with siRNA-DPP8, the expression of BAX increased, and the expression of cyclin D1, Bcl-2, MMP2 and MMP9 was downregulated. In cervical cancer cell lines, silencing the expression of DPP8 not only suppressed the proliferation, migration and invasion of the cervical cancer cells, but also promoted cervical cancer cell apoptosis.

CONCLUSIONS

The data obtained in the present study reveal that DPP8 promotes the progression of cervical cancer.

Taurine exhibits an apoptosis-inducing effect on human nasopharyngeal carcinoma cells through PTEN/Akt pathways in vitro

Nasopharyngeal carcinoma (NPC) is a distinctive type of head and neck malignancy with a high incidence in southern China. Previous studies have confirmed that taurine shows an anti-cancer effect on a variety of human tumors by inhibiting cell proliferation and inducing apoptosis. However, the underlying molecular mechanism of its anti-cancer effect on NPC is not well understood. To clarify these anti-cancer mechanisms, we performed cell viability and colony formation assays. Apoptotic cells were quantified by flow cytometry. The expression levels of apoptosis-related proteins were evaluated by Western blot. The results showed that taurine markedly inhibited cell proliferation in NPC cells, but only slightly in an immortalized normal nasopharyngeal cell line. Taurine suppressed colony formation and induced apoptosis of NPC cell lines in a dose-dependent manner. Furthermore, taurine increased the active form of caspase-9/3 in a dose-dependent manner. Taurine down-regulated the anti-apoptotic protein Bcl-xL and up-regulated the pro-apoptotic protein Bax and GRP78, a major endoplasmic reticulum (ER) chaperone. These results suggest the involvement of mitochondrial and ER stress signaling in apoptosis. In addition, taurine increased the levels of PTEN (phosphatase and tensin homolog deleted on chromosome 10) and p53, and reduced phosphorylated Akt (protein kinase B). In conclusion, taurine may inhibit cell proliferation and induce apoptosis in NPC through PTEN activation with concomitant Akt inactivation.

Exploring the Mechanism of Flavonoids Through Systematic Bioinformatics Analysis

Flavonoids are the largest class of plant polyphenols, with common structure of diphenylpropanes, consisting of two aromatic rings linked through three carbons and are abundant in both daily diets and medicinal plants. Fueled by the recognition of consuming flavonoids to get better health, researchers became interested in deciphering how flavonoids alter the functions of human body. Here, systematic studies were performed on 679 flavonoid compounds and 481 corresponding targets through bioinformatics analysis. Multiple human diseases related pathways including cancers, neuro-disease, diabetes, and infectious diseases were significantly regulated by flavonoids. Specific functions of each flavonoid subclass were further analyzed in both target and pathway level. Flavones and isoflavones were significantly enriched in multi-cancer related pathways, flavan-3-ols were found focusing on cellular processing and lymphocyte regulation, flavones preferred to act on cardiovascular related activities and isoflavones were closely related with cell multisystem disorders. Relationship between chemical constitution fragment and biological effects indicated that different side chain could significantly affect the biological functions of flavonoids subclasses. Results will highlight the common and preference functions of flavonoids and their subclasses, which concerning their pharmacological and biological properties.

NRF2 and the Hallmarks of Cancer

The transcription factor NRF2 is the master regulator of the cellular antioxidant response. Though recognized originally as a target of chemopreventive compounds that help prevent cancer and other maladies, accumulating evidence has established the NRF2 pathway as a driver of cancer progression, metastasis, and resistance to therapy. Recent studies have identified new functions for NRF2 in the regulation of metabolism and other essential cellular functions, establishing NRF2 as a truly pleiotropic transcription factor. In this review, we explore the roles of NRF2 in the hallmarks of cancer, indicating both tumor suppressive and tumor-promoting effects.

Seeking Convergence and Cure with New Myeloma Therapies

For over a decade, the mainstay of multiple myeloma therapy has been small molecules that directly attack malignant plasma cell biology. However, potent immunotherapies have recently emerged, transforming the myeloma therapeutic landscape. Here we first review new promising strategies to target plasma cells through protein homeostasis and epigenetic modulators. We then discuss emerging immunotherapy strategies that are leading to dramatic results in patients. Finally, we focus on recent preclinical data suggesting that enforcing cell-surface antigen expression through small molecules may enhance immunotherapy efficacy and avoid resistance. We argue that these emerging observations point the way toward potential convergence between drug classes. With recent rapid progress we may finally be on the verge of the 'C' word: a cure for myeloma.

The combination of a sphingosine kinase 2 inhibitor (ABC294640) and a Bcl-2 inhibitor (ABT-199) displays synergistic anti-myeloma effects in myeloma cells without a t(11;14) translocation

Multiple myeloma (MM) remains an incurable disease in need of the development of novel therapeutic agents and drug combinations. ABT‐199 is a specific Bcl‐2 inhibitor in clinical trials for MM; however, its activity as a single agent was limited to myeloma patients with the t(11;14) translocation who acquire resistance due to co‐expression of Mcl‐1 and Bcl‐xL. These limitations preclude its use in a broader patient population. We have recently found that a sphingosine kinase 2‐specific inhibitor (ABC294640) induces apoptosis in primary human CD138⁺ cells and MM cell lines. ABC294640 is currently in phase I/II clinical trials for myeloma (clinicaltrials.gov: #NCT01410981). Interestingly, ABC294640 down‐regulates c‐Myc and Mcl‐1, but does not have any effects on Bcl‐2. We first evaluated the combinatorial anti‐myeloma effect of ABC294640 and ABT‐199 in vitro in 7 MM cell lines, all of which harbor no t(11;14) translocation. Combination index calculation demonstrated a synergistic anti‐myeloma effect of the combination of ABC294640 and ABT‐199. This synergistic anti‐myeloma effect was maintained even in the presence of bone marrow (BM) stromal cells. The combination of ABC294640 and ABT‐199 led to enhanced cleavage of PARP and caspase‐3/9 and increased Annexin‐V expression, consistent with the induction of apoptosis by the combination treatment. In addition, the combination of ABC294640 and ABT‐199 resulted in the down‐regulation of the anti‐apoptotic proteins Mcl‐1, Bcl‐2, and Bcl‐xL and the cleavage of Bax and Bid. The combination induced both the mitochondrial mediated‐ and caspase‐mediated apoptosis pathways. Finally, the combination of ABC294640 and ABT‐199 resulted in augmented anti‐myeloma effect in vivo in a mouse xenograft model. These findings demonstrate that the co‐administration of ABC294640 and ABT‐199 exhibits synergistic anti‐myeloma activity in vitro and in vivo, providing justification for a clinical study of this novel combination in patients with relapsed/refractory multiple myeloma.