Dual inhibition of Bcl-2 and Bcl-xL strikingly enhances PI3K inhibition-induced apoptosis in human myeloid leukemia cells through a GSK3- and Bim-dependent mechanism

AMPK inhibition sensitizes acute leukemia cells to BH3 mimetic-induced cell death

BH3 mimetics, including the BCL2/BCLXL/BCLw inhibitor navitoclax and MCL1 inhibitors S64315 and tapotoclax, have undergone clinical testing for a variety of neoplasms. Because of toxicities, including thrombocytopenia after BCLXL inhibition as well as hematopoietic, hepatic and possible cardiac toxicities after MCL1 inhibition, there is substantial interest in finding agents that can safely sensitize neoplastic cells to these BH3 mimetics. Building on the observation that BH3 mimetic monotherapy induces AMP kinase (AMPK) activation in multiple acute leukemia cell lines, we report that the AMPK inhibitors (AMPKis) dorsomorphin and BAY-3827 sensitize these cells to navitoclax or MCL1 inhibitors. Cell fractionation and phosphoproteomic analyses suggest that sensitization by dorsomorphin involves dephosphorylation of the proapoptotic BCL2 family member BAD at Ser75 and Ser99, leading BAD to translocate to mitochondria and inhibit BCLXL. Consistent with these results, BAD knockout or mutation to BAD S75E/S99E abolishes the sensitizing effects of dorsomorphin. Conversely, dorsomorphin synergizes with navitoclax or the MCL1 inhibitor S63845 to induce cell death in primary acute leukemia samples ex vivo and increases the antitumor effects of navitoclax or S63845 in several xenograft models in vivo with little or no increase in toxicity in normal tissues. These results suggest that AMPK inhibition can sensitize acute leukemia to multiple BH3 mimetics, potentially allowing administration of lower doses while inducing similar antineoplastic effects.

Ultrasound-mediated delivery of Pik3cb shRNA using magnetic nanoparticles for the treatment of in-stent restenosis in a rat balloon-injured model

The aim of the present work was to examine the effect of polyethylene glycol (PEG)-coated superparamagnetic iron oxide (SPIO) nanoparticles carrying Pik3cb short hairpin RNA (shRNA) in the prevention of restenosis with the aid of ultrasound and a magnetic field. SPIO is a type of contrast agent used in medical imaging to enhance the visibility of specific tissues or organs. It consists of tiny iron oxide nanoparticles that can be targeted to specific areas of interest in the body. PEG-coated SPIO nanoparticles carrying Pik3cb shRNA (SPIO-shPik3cb) were prepared, and the particle size and zeta potential of PEG-coated SPIO nanoparticles with and without Pik3cb shRNA were examined. After a right common artery balloon-injured rat model was established, the rats were randomly divided into four groups, and the injured arteries were transfected with SPIO-shPik3cb, saline, SPIO-shcontrol and naked shRNA Pik3cb. During the treatment, each group was placed under a magnetic field and was transfected with the aid of ultrasound. Rats were sacrificed, and the tissue was harvested for analysis after 14 days. The results suggested that the mean particle size and zeta potential of SPIO-shPik3cbs were 151.45 ± 11 nm and 10 mV, respectively. SPIO-shPik3cb showed higher transfection efficiency and significantly inhibited the intimal thickening compared with naked Pik3cb shRNA in vascular smooth muscle cells (VSMCs) (*P < 0.05). Moreover, SPIO-shPik3cb could also significantly downregulate the expression of pAkt protein compared with naked Pik3cb shRNA. According to the results, SPIO-shPik3cb can remarkably inhibit the intimal thickening under a combination of magnetic field exposure and ultrasound.

CBF-Beta Mitigates PI3K-Alpha-Specific Inhibitor Killing through PIM1 in PIK3CA-Mutant Gastric Cancer

PIK3CA is the second most mutated gene in cancer leading to aberrant PI3K/AKT/mTOR signaling and increased translation, proliferation, and survival. Some 4%-25% of gastric cancers display activating PIK3CA mutations, including 80% of Epstein-Barr virus-associated GCs. Small molecules, including pan-PI3K and dual PI3K/mTOR inhibitors, have shown moderate success clinically, due to broad on-target/off-tissue effects. Thus, isoform-specific and mutant selective inhibitors have been of significant interest. However, drug resistance is a problem and has affected success of new drugs. There has been a concerted effort to define mechanisms of resistance and identify potent combinations in many tumor types, though gastric cancer is comparatively understudied. In this study, we identified modulators of the response to the PI3Kα-specific inhibitor, BYL719, in PIK3CA-mutant GCs. We found that loss of NEDD9 or inhibition of BCL-XL conferred hypersensitivity to BYL719, through increased cell-cycle arrest and cell death, respectively. In addition, we discovered that loss of CBFB conferred resistance to BYL719. CBFB loss led to upregulation of the protein kinase PIM1, which can phosphorylate and activate several overlapping downstream substrates as AKT thereby maintaining pathway activity in the presence of PI3Kα inhibition. The addition of a pan-PIM inhibitor re-sensitized resistant cells to BYL719. Our data provide clear mechanistic insights into PI3Kα inhibitor response in PIK3CA-mutant gastric tumors and can inform future work as mutant-selective inhibitors are in development for diverse tumor types.

IMPLICATIONS

Loss of either NEDD9 or BCL-XL confers hypersensitivity to PI3K-alpha inhibition whereas loss of CBFB confers resistance through a CBFB/PIM1 signaling axis.

Bcl-2 inhibition combined with PPARα activation synergistically targets leukemic stem cell-like cells in acute myeloid leukemia

Persistence of leukemic stem cells (LSCs) is one of the determining factors to acute myeloid leukemia (AML) treatment failure and responsible for the poor prognosis of the disease. Hence, novel therapeutic strategies that target LSCs are crucial for treatment success. We investigated if targeting Bcl-2 and peroxisome proliferator activated receptor α (PPARα), two distinct cell survival regulating mechanisms could eliminate LSCs. This study demonstrate that the Bcl-2 inhibitor venetoclax combined with the PPARα agonist chiglitazar resulted in synergistic killing of LSC-like cell lines and CD34+ primary AML cells while sparing their normal counterparts. Furthermore, the combination regimen significantly suppressed AML progression in patient-derived xenograft (PDX) mouse models. Mechanistically, chiglitazar-mediated PPARα activation inhibited the transcriptional activity of the PIK3AP1 gene promoter and down-regulated the PI3K/Akt signaling pathway and anti-apoptotic Bcl-2 proteins, leading to cell proliferation inhibition and apoptosis induction, which was synergized with venetoclax. These findings suggest that combinatorial Bcl-2 inhibition and PPARα activation selectively eliminates AML cells in vivo and vitro, representing an effective therapy for patients with relapsed and refractory AML.

mTOR in programmed cell death and its therapeutic implications

Mechanistic target of rapamycin (mTOR), a highly conserved serine/threonine kinase, is involved in cellular metabolism, protein synthesis, and cell death. Programmed cell death (PCD) assists in eliminating aging, damaged, or neoplastic cells, and is indispensable for sustaining normal growth, fighting pathogenic microorganisms, and maintaining body homeostasis. mTOR has crucial functions in the intricate signaling pathway network of multiple forms of PCD. mTOR can inhibit autophagy, which is part of PCD regulation. Cell survival is affected by mTOR through autophagy to control reactive oxygen species production and the degradation of pertinent proteins. Additionally, mTOR can regulate PCD in an autophagy-independent manner by affecting the expression levels of related genes and phosphorylating proteins. Therefore, mTOR acts through both autophagy-dependent and -independent pathways to regulate PCD. It is conceivable that mTOR exerts bidirectional regulation of PCD, such as ferroptosis, according to the complexity of signaling pathway networks, but the underlying mechanisms have not been fully explained. This review summarizes the recent advances in understanding mTOR-mediated regulatory mechanisms in PCD. Rigorous investigations into PCD-related signaling pathways have provided prospective therapeutic targets that may be clinically beneficial for treating various diseases.

Dual mTORC1/2 Inhibition Synergistically Enhances AML Cell Death in Combination with the BCL2 Antagonist Venetoclax

PURPOSE

Acute myelogenous leukemia (AML) is an aggressive disease with a poor outcome. We investigated mechanisms by which the anti-AML activity of ABT-199 (venetoclax) could be potentiated by dual mTORC1/TORC2 inhibition.

EXPERIMENTAL DESIGN

Venetoclax/INK128 synergism was assessed in various AML cell lines and primary patient AML samples in vitro. AML cells overexpressing MCL-1, constitutively active AKT, BAK, and/or BAX knockout, and acquired venetoclax resistance were investigated to define mechanisms underlying interactions. The antileukemic efficacy of this regimen was also examined in xenograft and patient-derived xenograft (PDX) models.

RESULTS

Combination treatment with venetoclax and INK128 (but not the mTORC1 inhibitor rapamycin) dramatically enhanced cell death in AML cell lines. Synergism was associated with p-AKT and p-4EBP1 downregulation and dependent upon MCL-1 downregulation and BAK/BAX upregulation as MCL-1 overexpression and BAX/BAK knockout abrogated cell death. Constitutive AKT activation opposed synergism between venetoclax and PI3K or AKT inhibitors, but not INK128. Combination treatment also synergistically induced cell death in venetoclax-resistant AML cells. Similar events occurred in primary patient-derived leukemia samples but not normal CD34+ cells. Finally, venetoclax and INK128 co-treatment displayed increased antileukemia effects in in vivo xenograft and PDX models.

CONCLUSIONS

The venetoclax/INK128 regimen exerts significant antileukemic activity in various preclinical models through mechanisms involving MCL-1 downregulation and BAK/BAX activation, and offers potential advantages over PI3K or AKT inhibitors in cells with constitutive AKT activation. This regimen is active against primary and venetoclax-resistant AML cells, and in in vivo AML models. Further investigation of this strategy appears warranted.

Synergistic Interactions between the Hypomethylating Agent Thio-Deoxycytidine and Venetoclax in Myelodysplastic Syndrome Cells

Interactions between the novel hypomethylating agent (HMA) thio-deoxycytidine (T-dCyd) and the BCL-2 antagonist ABT-199 (venetoclax) have been examined in human myelodysplastic syndrome (MDS) cells. The cells were exposed to agents alone or in combination, after which apoptosis was assessed, and a Western blot analysis was performed. Co-administration of T-dCyd and ABT-199 was associated with the down-regulation of DNA methyltransferase 1 (DNMT1) and synergistic interactions documented by a Median Dose Effect analysis in multiple MDS-derived lines (e.g., MOLM-13, SKM-1, and F-36P). Inducible BCL-2 knock-down significantly increased T-dCyd's lethality in MOLM-13 cells. Similar interactions were observed in the primary MDS cells, but not in the normal cord blood CD34⁺ cells. Enhanced killing by the T-dCyd/ABT-199 regimen was associated with increased reactive oxygen species (ROS) generation and the down-regulation of the anti-oxidant proteins Nrf2 and HO-1, as well as BCL-2. Moreover, ROS scavengers (e.g., NAC) reduced lethality. Collectively, these data suggest that combining T-dCyd with ABT-199 kills MDS cells through an ROS-dependent mechanism, and we argue that this strategy warrants consideration in MDS therapy.

Anti-cancer effects of ginsenoside CK on acute myeloid leukemia in vitro and in vivo

Objectives

Acute myeloid leukemia (AML) is a malignant disease characterized by clonal proliferation of myeloid cells, and its treatment continues to be a challenge due to high morbidity and mortality. Ginsenoside compound K, a major active metabolite of the protopanaxadiol-type ginsenosides, exhibits biological activities in various cancer cells and animal models. Here, we investigated the role of CK in anticancer potential in AML both in vitro and in vivo.

Materials and methods

To investigate the inhibitory effects of CK in AML cells, in vitro experiments, including cell viability assays, colony forming assays, and cell cycle and apoptosis assays were performed. AML animal experiment was established and quantitative analysis of lung tumor growth nodules and spleen weight and H&E staining were carried out to further determine the effects of CK on AML. In addition, the potential key genes induced and influenced by CK during treatment was identification by RNA-seq and qRT-PCR.

Results

CK suppressed AML cell activity and induced apoptosis and G1 cell cycle arrest based on the experiment results. Moreover, significantly down-regulated expression genes of BCL2, KIT, DNMT3A, MYC and CSF-1 and up-regulated expression gene of TET2 in CK treatment AML cells were discovered.

Conclusion

Our results demonstrated that CK could be used as an anti-AML drug with significant therapeutic efficacy and good biosafety.

Mechanisms of venetoclax resistance and solutions

The BCL-2 inhibitor venetoclax is currently approved for treatment of hematologic diseases and is widely used either as monotherapy or in combination strategies. It has produced promising results in the treatment of refractory or relapsed (R/R) and aged malignant hematologic diseases. However, with clinical use, resistance to venetoclax has emerged. We review the mechanism of reduced dependence on BCL-2 mediated by the upregulation of antiapoptotic proteins other than BCL-2, such as MCL-1 and BCL-XL, which is the primary mechanism of venetoclax resistance, and find that this mechanism is achieved through different pathways in different hematologic diseases. Additionally, this paper also summarizes the current investigations of the mechanisms of venetoclax resistance in terms of altered cellular metabolism, changes in the mitochondrial structure, altered or modified BCL-2 binding domains, and some other aspects; this article also reviews relevant strategies to address these resistance mechanisms.

Targeting EZH2 Promotes Chemosensitivity of BCL-2 Inhibitor through Suppressing PI3K and c-KIT Signaling in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is one of the most common hematological malignancies with high heterogeneity, characterized by a differentiating block at the early progenitor stage. The selective BCL-2 inhibitor, Venetoclax (Ven), has shown exciting clinical results in a certain group of AML patients. However, Ven alone is insufficient to reach an enduringly complete response, which leads to the concern of Ven resistance. Alternative combined therapies with Ven are demanded in AML. Here, we reported the synergistic effect and molecular mechanism of the enhancer of zeste homolog 2 (EZH2) inhibitor DZNeP with Ven in AML cells. Results showed that the combination of DZNeP with Ven significantly induces cell proliferation arrest compared to single-drug control in AML cells and primary samples, and CalcuSyn analysis showed their significant synergy. The combination also significantly promotes apoptosis and increases the expression of pro-apoptotic proteins. The whole transcriptome analysis showed that phosphoinositide-3-kinase-interacting protein1 (PIK3IP1), the PI3K/AKT/mTOR signaling suppressor, is upregulated upon DZNeP treatment. Moreover, EZH2 is upregulated but PIK3IP1 is downregulated in 88 newly diagnosed AML cohorts compared to 70 healthy controls, and a higher expression of EZH2 is associated with poor outcomes in AML patients. Particularly, the combination of DZNeP with Ven dramatically eliminated CD117 (c-KIT) (+) AML blasts, suggesting the effect of the combination on tumor stem cells. In summary, our data indicated that DZNeP increases the sensitivity of Ven in AML by affecting PI3K and c-KIT signaling in AML. Our results also suggested that the therapeutic targeting of both EZH2 and BCL-2 provides a novel potential combined strategy against AML.

BCL-2 inhibitor synergizes with PI3Kδ inhibitor and overcomes FLT3 inhibitor resistance in acute myeloid leukaemia

Inhibitors targeting the antiapoptotic molecule BCL-2 have therapeutic potential for the treatment of acute myeloid leukaemia (AML); however, BCL-2 inhibitors such as venetoclax exhibit limited monotherapy efficacy in relapsed or refractory human AML. PI3Kδ/AKT signalling has been shown to be constitutively active in AML patients. Here, we demonstrate that the combination of BCL-2 and PI3Kδ inhibitors exerts synergistic antitumour effects both in vitro and in vivo in AML. Cotreatment with venetoclax and the specific PI3Kδ inhibitor idelalisib significantly enhanced antiproliferative effects and induced caspase-dependent apoptosis in a panel of AML cell lines. The synergistic effects were mechanistically based on the inactivation of AKT/4E-BP-1 signalling and the reduction of MCL-1 expression, which diminished the binding of Bim to MCL-1. Notably, compared with the parental FLT3-ITD-positive MV-4-11, the acquired FLT3 inhibitor quizartinib-resistant xenograft model carrying the F691L mutation, exhibited a markedly higher sensitivity to venetoclax. Furthermore, venetoclax combined with idelalisib led to tumour regression in all animals in this quizartinib-resistant AML model. Thus, these data indicate that combined inhibition of BCL-2 and PI3Kδ may be a promising strategy in AML, especially for patients with FLT3-ITD and/or FLT3-TKD mutations.

Bcl-xL inhibition radiosensitizes PIK3CA/PTEN wild-type triple negative breast cancers with low Mcl-1 expression

Patients with radioresistant breast cancers, including a large percentage of women with triple negative breast cancer (TNBC), demonstrate limited response to radiation (RT) and increased locoregional recurrence; thus, strategies to increase the efficacy of RT in TNBC are critically needed. We demonstrate that pan Bcl-2 family inhibition (ABT-263, rER: 1.52-1.56) or Bcl-xL specific inhibition (WEHI-539, A-1331852; rER: 1.31-2.00) radiosensitized wild-type PIK3CA/PTEN TNBC (MDA-MB-231, CAL-120) but failed to radiosensitize mutant PIK3CA/PTEN TNBC (rER: 0.90 - 1.07; MDA-MB-468, CAL-51, SUM-159). Specific inhibition of Bcl-2 or Mcl-1 did not induce radiosensitization, regardless of PIK3CA/PTEN status (rER: 0.95 - 1.07). In wild-type PIK3CA/PTEN TNBC, pan Bcl-2 family inhibition or Bcl-xL specific inhibition with RT led to increased levels of apoptosis (p < 0.001) and an increase in cleaved PARP and cleaved caspase 3. CRISPR-mediated PTEN knockout in wild-type PIK3CA/PTEN MDA-MB-231 and CAL-120 cells induced expression of pAKT/Akt and Mcl-1 and abolished Bcl-xL inhibitor-mediated radiosensitization (rER: 0.94 - 1.07). Similarly, Mcl-1 overexpression abolished radiosensitization in MDA-MB-231 and CAL-120 cells (rER: 1.02 - 1.04) but transient MCL1 knockdown in CAL-51 cells promoted Bcl-xL-inhibitor mediated radiosensitization (rER 2.35 ± 0.05). In vivo, ABT-263 or A-1331852 in combination with RT decreased tumor growth and increased tumor tripling time (p < 0.0001) in PIK3CA/PTEN wild-type TNBC cell line and patient-derived xenografts. Collectively, this study provides the preclinical rationale for early phase clinical trials testing the safety, tolerability, and efficacy of Bcl-xL inhibition and RT in women with wild-type PIK3CA/PTEN wild-type TNBC at high risk for recurrence.

How Phosphofructokinase-1 Promotes PI3K and YAP/TAZ in Cancer: Therapeutic Perspectives

Simple Summary

We propose that PFK1 promotes a positive feedback loop with PI3K/AKT and YAP/TAZ signaling pathways in cancer cells. Therefore, targeting PFK1 (or its product F-1,6-BP) could improve the efficacy of PI3K and YAP/TAZ inhibitors currently tested in clinical trials. To this aim, we suggest the use of citrate, which is a physiologic and potent inhibitor of PFK1.

Abstract

PI3K/AKT is one of the most frequently altered signaling pathways in human cancers, supporting the activation of many proteins sustaining cell metabolism, proliferation, and aggressiveness. Another important pathway frequently altered in cancer cells is the one regulating the YAP/TAZ transcriptional coactivators, which promote the expression of genes sustaining aerobic glycolysis (such as WNT, MYC, HIF-1), EMT, and drug resistance. Of note, the PI3K/AKT pathway can also regulate the YAP/TAZ one. Unfortunately, although PI3K and YAP inhibitors are currently tested in highly resistant cancers (both solid and hematologic ones), several resistance mechanisms may arise. Resistance mechanisms to PI3K inhibitors may involve the stimulation of alternative pathways (such as RAS, HER, IGFR/AKT), the inactivation of PTEN (the physiologic inhibitor of PI3K), and the expression of anti-apoptotic Bcl-xL and MCL1 proteins. Therefore, it is important to improve current therapeutic strategies to overcome these limitations. Here, we want to highlight how the glycolytic enzyme PFK1 (and its product F-1,6-BP) promotes the activation of both PI3K/AKT and YAP/TAZ pathways by several direct and indirect mechanisms. In turn, PI3K/AKT and YAP/TAZ can promote PFK1 activity and F-1,6-BP production in a positive feedback loop, thus sustaining the Warburg effect and drug resistance. Thus, we propose that the inhibition of PFK1 (and of its key activator PFK2/PFKFB3) could potentiate the sensitivity to PI3K and YAP inhibitors currently tested. Awaiting the development of non-toxic inhibitors of these enzymes, we propose to test the administration of citrate at a high dosage, because citrate is a physiologic inhibitor of both PFK1 and PFK2/PFKFB3. Consistently, in various cultured cancer cells (including melanoma, sarcoma, hematologic, and epithelial cancer cells), this “citrate strategy” efficiently inhibits the IGFR1/AKT pathway, promotes PTEN activity, reduces Bcl-xL and MCL1 expression, and increases sensitivity to standard chemotherapy. It also inhibits the development of sarcoma, pancreatic, mammary HER⁺ and lung RAS-driven tumors in mice without apparent toxicities.

Targeting PI3K/AKT/mTOR pathway to enhance the anti-leukemia efficacy of venetoclax

BACKGROUND

The treatment of acute myeloid leukemia (AML) is developing towards "targeted therapy", which faces challenges such as low sensitivity and drug resistance. Therefore, targeted drugs need to be used in combination with other drugs to overcome clinical problems.

OBJECTIVE

AML cells and animal models were used to determine the synergistic anti-leukemic effect of Dactolisib (BEZ235) and Venetoclax (ABT199) and explore its mechanism.

METHODS

In vitro experiments, we used cell counting kit-8 (CCK8), flow cytometry, real-time quantitative PCR (qPCR), and Western blot to detect the anti-leukemic effects of ABT199 and BEZ235. In vivo experiments, female nude mice were injected subcutaneously with THP-1 cells to form tumors, evaluate the combined effect of ABT199 and BEZ235 by indicators such as tumor size, tumor weight, Ki67 and cleaved-Caspase3 staining. The mice's body weight and HE staining were used to evaluate the liver injury and adverse drug reactions.

RESULTS

The combination of BEZ235 and ABT199 has a synergistic effect through promoting apoptosis and inhibiting proliferation. The BEZ235 increased the drug sensitivity of ABT199 by reducing the MCL-1 protein synthesis and promoted the degradation of MCL-1 protein, which is considered as the mechanism of reversing ABT199 resistance. Furthermore, the BEZ235 and ABT199 can synergistically enhance the inhibition of PI3K/AKT/mTOR pathway.

CONCLUSION

The combination of BEZ235 and ABT199 exhibits a synergistic anti-tumor effect in AML by down-regulating MCL-1 protein.

Inhibition of B-cell lymphoma 2 family proteins alters optical redox ratio, mitochondrial polarization, and cell energetics independent of cell state

SIGNIFICANCE

The optical redox ratio (ORR) [autofluorescence intensity of the reduced form of nicotinamide adenine dinucleotide (phosphate) (NAD(P)H)/flavin adenine dinucleotide (FAD)] provides a label-free method to quantify cellular metabolism. However, it is unclear whether changes in the ORR with B-cell lymphoma 2 (Bcl-2) family protein inhibition are due to metabolic stress alone or compromised cell viability.

AIM

Determine whether ABT-263 (navitoclax, Bcl-2 family inhibitor) changes the ORR due to changes in mitochondrial function that are independent of changes in cell viability.

APPROACH

SW48 colon cancer cells were used to investigate changes in ORR, mitochondrial membrane potential, oxygen consumption rates, and cell state (cell growth, viability, proliferation, apoptosis, autophagy, and senescence) with ABT-263, TAK-228 [sapanisertib, mammalian target of rapamycin complex 1/2 (mTORC 1/2) inhibitor], and their combination at 24 h.

RESULTS

Changes in the ORR with Bcl-2 inhibition are driven by increases in both NAD(P)H and FAD autofluorescence, corresponding with increased basal metabolic rate and increased mitochondrial polarization. ABT-263 treatment does not change cell viability or induce autophagy but does induce a senescent phenotype. The metabolic changes seen with ABT-263 treatment are mitigated by combination with mTORC1/2 inhibition.

CONCLUSIONS

The ORR is sensitive to increases in mitochondrial polarization, energetic state, and cell senescence, which can change independently from cell viability.

Bax/Bcl-2 Cascade Is Regulated by the EGFR Pathway: Therapeutic Targeting of Non-Small Cell Lung Cancer

Non-small cell lung carcinoma (NSCLC) comprises 80%-85% of lung cancer cases. EGFR is involved in several cancer developments, including NSCLC. The EGFR pathway regulates the Bax/Bcl-2 cascade in NSCLC. Increasing understanding of the molecular mechanisms of fundamental tumor progression has guided the development of numerous antitumor drugs. The development and improvement of rationally planned inhibitors and agents targeting particular cellular and biological pathways in cancer have been signified as a most important paradigm shift in the strategy to treat and manage lung cancer. Newer approaches and novel chemotherapeutic agents are required to accompany present cancer therapies for improving efficiency. Using natural products as a drug with an effective delivery system may benefit therapeutics. Naturally originated compounds such as phytochemicals provide crucial sources for novel agents/drugs and resources for tumor therapy. Applying the small-molecule inhibitors (SMIs)/phytochemicals has led to potent preclinical discoveries in various human tumor preclinical models, including lung cancer. In this review, we summarize recent information on the molecular mechanisms of the Bax/Bcl-2 cascade and EGFR pathway in NSCLC and target them for therapeutic implications. We further described the therapeutic potential of Bax/Bcl-2/EGFR SMIs, mainly those with more potent and selectivity, including gefitinib, EGCG, ABT-737, thymoquinone, quercetin, and venetoclax. In addition, we explained the targeting EGFR pathway and ongoing in vitro and in vivo and clinical investigations in NSCLC. Exploration of such inhibitors facilitates the future treatment and management of NSCLC.

A systems genetics approach delineates the role of Bcl2 in leukemia pathogenesis

Leukemia is a group of malignancies of the blood forming tissues, and is characterized by the uncontrolled proliferation of blood cells. In the United States, it accounts for approximately 3.5% and 4% of all cancer-related incidences and mortalities, respectively. The current study aimed to explore the role of Bcl2 and associated genes in leukemia pathogenesis using a systems genetics approach. The transcriptome data from BXD Recombinant Inbred (RI) mice was analyzed to identify the expression of Bcl2 in myeloid cells. eQTL mapping was performed to select the potential chromosomal region and subsequently identify the candidate gene modulating the expression of Bcl2. Furthermore, gene enrichment and protein-protein interaction (PPI) analyses of the Bcl2-coexpressed genes were performed to demonstrate the role of Bcl2 in leukemia pathogenesis. The Bcl2-coexpressed genes were found to be enriched in various hematopoietic system related functions, and multiple pathways related to signaling, immune response, and cancer. The PPI network analysis demonstrated direct interaction of hematopoietic function related genes, such as Bag3, Bak1, Bcl2l11, Bmf, Mapk9, Myc, Ppp2r5c, and Ppp3ca with Bcl2. The eQTL mapping identified a 4.5 Mb genomic region on chromosome 11, potentially regulating the expression of Bcl2. A multi-criteria filtering process identified Top2a, among the genes located in the mapped locus, as the best candidate upstream regulator for Bcl2 expression variation. Hence, the current study provides better insights into the role of Bcl2 in leukemia pathogenesis and demonstrates the significance of our approach in gaining new knowledge on leukemia. Furthermore, our findings from the PPI network analysis and eQTL mapping provide supporting evidence of leukemia-associated genes, which can be further explored for their functional importance in leukemia. DATA AVAILABILITY: The myeloid cell transcriptomic data of the BXD mice used in this study can be accessed through our GeneNetwork (http://www.genenetwork.org) with the accession number of GN144.

Glycogen Synthase Kinase 3β Involvement in Neuroinflammation and Neurodegenerative Diseases

BACKGROUND

GSK-3β activity has been strictly related to neuroinflammation and neurodegeneration. Alzheimer's disease is the most studied neurodegenerative disease, but GSK-3β seems to be involved in almost all neurodegenerative diseases including Parkinson's disease, amyotrophic lateral sclerosis, frontotemporal dementia, Huntington's disease and the autoimmune disease multiple sclerosis.

OBJECTIVE

The aim of this review is to help researchers both working on this research topic or not to have a comprehensive overview on GSK-3β in the context of neuroinflammation and neurodegeneration.

METHOD

Literature has been searched using PubMed and SciFinder databases by inserting specific keywords. A total of more than 500 articles have been discussed.

RESULTS

First of all, the structure and regulation of the kinase were briefly discussed and then, specific GSK-3β implications in neuroinflammation and neurodegenerative diseases were illustrated also with the help of figures, to conclude with a comprehensive overview on the most important GSK-3β and multitarget inhibitors. For all discussed compounds, the structure and IC50 values at the target kinase have been reported.

CONCLUSION

GSK-3β is involved in several signaling pathways both in neurons as well as in glial cells and immune cells. The fine regulation and interconnection of all these pathways are at the base of the rationale use of GSK-3β inhibitors in neuroinflammation and neurodegeneration. In fact, some compounds are now under clinical trials. Despite this, pharmacodynamic and ADME/Tox profiles of the compounds were often not fully characterized and this is deleterious in such a complex system.

Pterostilbene Coupled with Physical Exercise Effectively Mitigates Collagen-Induced Articular Synovial by Correcting the PI3K/Akt/NF-κB Signal Pathway

Studies have revealed that a novel anti-inflammatory mediator─maresin-1 (MaR1)─can reduce the level of inflammatory factors. There is evidence that physical exercise (PE) promotes the biosynthesis of MaR1, leading to the prevention of rheumatoid arthritis (RA). Previously, we have proven that resveratrol can mitigate the formation of RA. Pterostilbene (Pte) is an analogue of resveratrol, but it is around four times more bioavailable. Hence, we hypothesize that Pte could be more effective in preventing RA, in particular, when accompanied by moderate PE. Based on this hypothesis, we explored the preventive effect of Pte combined with PE on a bovine type II collagen (BIIC)-stimulated rat RA model and its underlying molecular mechanism. Compared with the BIIC-stimulated group, the serum content of MaR1 with continuous intervention of Pte plus PE for 8 weeks was significantly increased to 46.3 pg/mL from 7.2 pg/mL in BIIC-treated alone. Besides, the variation in the relative expression levels of p-NF-κB and p-Akt was reversed with the administration of Pte plus PE. More importantly, the in vitro results confirmed that the treatment of Pte plus MaR1 inhibited proliferation and apoptosis and promoted the autophagy of the interleukin (IL)-1β-stimulated primary rat synovial cells through the PI3K/Akt/NF-κB signal pathway. Collectively, the oral administration of Pte plus moderate PE helped to ameliorate the pathological process of RA by correcting the PI3K/Akt/NF-κB signal pathway.

MicroRNA-221 regulates cell activity and apoptosis in acute lymphoblastic leukemia via regulating PTEN

T cell acute lymphoblastic leukemia (T-ALL), an aggressive and heterogeneous malignancy originating from T cell precursors (thymocytes), accounts for ~15% of all ALL cases in children and for ~25% in adults. The present study aimed to investigate the role of microRNA-221 (miR-221) in the regulation of cell viability and apoptosis of human T-ALL cells and its related regulatory mechanisms. To perform this investigation, miR-221 was upregulated or knocked down in human T-ALL cells (Jurkat cells) using miR-221 mimic or inhibitor, respectively. Then, cell viability was determined using a 3-(4,5-dimethylthiahiazol-2-y1)-2,5-diphenytetrazolium bromide assay, cell invasion and migration were analyzed via Transwell assays, and cell apoptosis was detected using flow cytometry. It was found that transfection with a miR-221 inhibitor significantly inhibited Jurkat cell viability, migration and invasion, and induced Jurkat cell apoptosis. Whereas, transfection with the miR-221 mimic resulted in the opposite effects. Besides, the results showed that phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was a target of miR-221. Moreover, it was observed that the effects of the miR-221 inhibitor on Jurkat cell viability, migration and invasion, and cell apoptosis were significantly eliminated by PTEN-small interfering RNA. In addition, it was shown that the phosphatidylinositol 3-kinase/AKT pathway was involved in the effect of miR-221 on Jurkat cells. In conclusion, the data indicated that miR-221 existed as an oncogene in T-ALL, and its downregulation could inhibit the development of ALL by targeting PTEN. Therefore, miR-221 may be a novel potential therapeutic target for ALL.

Seed oil of Brucea javanica induces apoptosis through the PI3K/Akt signaling pathway in acute lymphocytic leukemia Jurkat cells

Brucea javanica oil emulsion (BJOE) has been used to treat tumor in China for more than 40 years. However, its components and effectiveness in the treatment of acute lymphocytic leukemia (ALL) and its mechanism of anti-cancer activity remain unknown. In the current study, high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) was used to analyze the components of BJOE. Then, the anti-leukemia effects of BJOE were examined both in vitro and in vivo using ALL Jurkat cells and the p388 mouse leukemia transplant model, respectively. The primary ALL leukemia cells were also used to confirm the anti-leukemia effects of BJOE. The apoptotic-related results indicated that BJOE induced apoptosis in Jurkat cells and were suggestive of intrinsic apoptotic induction. Moreover, BJOE inhibited Akt (protein kinase B) activation and upregulated its downstream targets p53 and FoxO1 (forkhead box gene, group O-1) to initiate apoptosis. The activation of GSK3β was also involved. Our findings demonstrate that BJOE has anti-leukemia effects on ALL cells and can induce apoptosis in Jurkat cells through the phosphoinositide3-kinase (PI3K) /Akt signaling pathway.

Rigosertib elicits potent anti-tumor responses in colorectal cancer by inhibiting Ras signaling pathway

BACKGROUND

The therapeutic potency of Rigosertib (RGS) in the treatment of the myelodysplastic syndrome has been investigated previously, but little is known about its mechanisms of action.

METHODS

The present study integrates systems and molecular biology approaches to investigate the mechanisms of the anti-tumor effects of RGS, either alone or in combination with 5-FU in cellular and animal models of colorectal cancer (CRC).

RESULTS

The effects of RGS were more pronounced in dedifferentiated CRC cell types, compared to cell types that were epithelial-like. RGS inhibited cell proliferation and cell cycle progression in a cell-type specific manner, and that was dependent on the presence of mutations in KRAS, or its down-stream effectors. RGS increased both early and late apoptosis, by regulating the expression of p53, BAX and MDM2 in tumor model. We also found that RGS induced cell senescence in tumor tissues by increasing ROS generation, and impairing oxidant/anti-oxidant balance. RGS also inhibited angiogenesis and metastatic behavior of CRC cells, by regulating the expression of CD31, E-cadherin, and matrix metalloproteinases-2 and 9.

CONCLUSION

Our findings support the therapeutic potential of this potent RAS signaling inhibitor either alone or in combination with standard regimens for the management of patients with CRC.

FLT3 tyrosine kinase inhibitors synergize with BCL-2 inhibition to eliminate FLT3/ITD acute leukemia cells through BIM activation

Tyrosine kinase inhibitors (TKIs) targeting FLT3 have shown activity but when used alone have achieved limited success in clinical trials, suggesting the need for combination with other drugs. We investigated the combination of FLT3 TKIs (Gilteritinib or Sorafenib), with Venetoclax, a BCL-2 selective inhibitor (BCL-2i), on FLT3/ITD leukemia cells. The combination of a FLT3 TKI and a BCL-2i synergistically reduced cell proliferation and enhanced apoptosis/cell death in FLT3/ITD cell lines and primary AML samples. Venetoclax also re-sensitized FLT3 TKI-resistant cells to Gilteritinib or Sorafenib treatment, mediated through MAPK pathway inhibition. Gilteritinib treatment alone dissociated BIM from MCL-1 but increased the binding of BIM to BCL-2. Venetoclax treatment enhanced the binding of BIM to MCL-1 but dissociated BIM from BCL-2. Treatment with the drugs together resulted in dissociation of BIM from both BCL-2 and MCL-1, with an increased binding of BIM to the cell death mediator BAX, leading to increased apoptosis. These findings suggest that Venetoclax mitigates the unintended pro-survival effects of FLT3 TKI mainly through the dissociation of BIM and BCL-2 and also decreased BIM expression. This study provides evidence that the addition of BCL-2i enhances the effect of FLT3 TKI therapy in FLT3/ITD AML treatment.

AKT signaling restrains tumor suppressive functions of FOXO transcription factors and GSK3 kinase in multiple myeloma

The phosphatidylinositide-3 kinases and the downstream mediator AKT drive survival and proliferation of multiple myeloma (MM) cells. AKT signaling is active in MM and has pleiotropic effects; however, the key molecular aspects of AKT dependency in MM are not fully clear. Among the various downstream AKT targets are the Forkhead box O (FOXO) transcription factors (TFs) and glycogen synthase kinase 3 (GSK3), which are negatively regulated by AKT signaling. Here we show that abrogation of AKT signaling in MM cells provokes cell death and cell cycle arrest, which crucially depends on both FOXO TFs and GSK3. Based on gene expression profiling, we defined a FOXO-repressed gene set that has prognostic significance in a large cohort of patients with MM, indicating that AKT-mediated gene activation is associated with inferior overall survival. We further show that AKT signaling stabilizes the antiapoptotic myeloid cell leukemia 1 (MCL1) protein by inhibiting FOXO- and GSK3-mediated MCL1 turnover. In concordance, abrogation of AKT signaling greatly sensitized MM cells for an MCL1-targeting BH3-mimetic, which is currently in clinical development. Taken together, our results indicate that AKT activity is required to restrain the tumor-suppressive functions of FOXO and GSK3, thereby stabilizing the antiapoptotic protein MCL1 in MM. These novel insights into the role of AKT in MM pathogenesis and MCL1 regulation provide opportunities to improve targeted therapy for patients with MM.

Autofluorescence Imaging of Treatment Response in Neuroendocrine Tumor Organoids

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) account for roughly 60% of all neuroendocrine tumors. Low/intermediate grade human GEP-NETs have relatively low proliferation rates that animal models and cell lines fail to recapitulate. Short-term patient-derived cancer organoids (PDCOs) are a 3D model system that holds great promise for recapitulating well-differentiated human GEP-NETs. However, traditional measurements of drug response (i.e., growth, proliferation) are not effective in GEP-NET PDCOs due to the small volume of tissue and low proliferation rates that are characteristic of the disease. Here, we test a label-free, non-destructive optical metabolic imaging (OMI) method to measure drug response in live GEP-NET PDCOs. OMI captures the fluorescence lifetime and intensity of endogenous metabolic cofactors NAD(P)H and FAD. OMI has previously provided accurate predictions of drug response on a single cell level in other cancer types, but this is the first study to apply OMI to GEP-NETs. OMI tested the response to novel drug combination on GEP-NET PDCOs, specifically ABT263 (navitoclax), a Bcl-2 family inhibitor, and everolimus, a standard GEP-NET treatment that inhibits mTOR. Treatment response to ABT263, everolimus, and the combination were tested in GEP-NET PDCO lines derived from seven patients, using two-photon OMI. OMI measured a response to the combination treatment in 5 PDCO lines, at 72 h post-treatment. In one of the non-responsive PDCO lines, heterogeneous response was identified with two distinct subpopulations of cell metabolism. Overall, this work shows that OMI provides single-cell metabolic measurements of drug response in PDCOs to guide drug development for GEP-NET patients.

GSK-3β Can Regulate the Sensitivity of MIA-PaCa-2 Pancreatic and MCF-7 Breast Cancer Cells to Chemotherapeutic Drugs, Targeted Therapeutics and Nutraceuticals

Glycogen synthase kinase-3 (GSK-3) is a regulator of signaling pathways. KRas is frequently mutated in pancreatic cancers. The growth of certain pancreatic cancers is KRas-dependent and can be suppressed by GSK-3 inhibitors, documenting a link between KRas and GSK-3. To further elucidate the roles of GSK-3β in drug-resistance, we transfected KRas-dependent MIA-PaCa-2 pancreatic cells with wild-type (WT) and kinase-dead (KD) forms of GSK-3β. Transfection of MIA-PaCa-2 cells with WT-GSK-3β increased their resistance to various chemotherapeutic drugs and certain small molecule inhibitors. Transfection of cells with KD-GSK-3β often increased therapeutic sensitivity. An exception was observed with cells transfected with WT-GSK-3β and sensitivity to the BCL2/BCLXL ABT737 inhibitor. WT-GSK-3β reduced glycolytic capacity of the cells but did not affect the basal glycolysis and mitochondrial respiration. KD-GSK-3β decreased both basal glycolysis and glycolytic capacity and reduced mitochondrial respiration in MIA-PaCa-2 cells. As a comparison, the effects of GSK-3 on MCF-7 breast cancer cells, which have mutant PIK3CA, were examined. KD-GSK-3β increased the resistance of MCF-7 cells to chemotherapeutic drugs and certain signal transduction inhibitors. Thus, altering the levels of GSK-3β can have dramatic effects on sensitivity to drugs and signal transduction inhibitors which may be influenced by the background of the tumor.

Proteomic Resistance Biomarkers for PI3K Inhibitor in Triple Negative Breast Cancer Patient-Derived Xenograft Models

Simple Summary

The objective of this study is to identify potential proteomic biomarkers in triple negative breast cancer (TNBC) that associate with response to PI3K inhibitors which are in clinical trials. We tested a panel of TNBC patient-derived xenograft (PDX) models for their tumor growth response to a pan-PI3K inhibitor, BKM120. Proteomic analyses by reverse phase protein array (RPPA) of 182 markers were performed on baseline and post short-term treatment PDX samples, to correlate with tumor growth response. We identified several baseline and treatment induced proteomic biomarkers in association with resistance. These results provide important insights for the development of PI3K inhibitors in TNBC.

Abstract

PI3K pathway activation is frequently observed in triple negative breast cancer (TNBC). However, single agent PI3K inhibitors have shown limited anti-tumor activity. To investigate biomarkers of response and resistance mechanisms, we tested 17 TNBC patient-derived xenograft (PDX) models representing diverse genomic backgrounds and varying degrees of PI3K pathway signaling activities for their tumor growth response to the pan-PI3K inhibitor, BKM120. Baseline and post-treatment PDX tumors were subjected to reverse phase protein array (RPPA) to identify protein markers associated with tumor growth response. While BKM120 consistently reduced PI3K pathway activity, as demonstrated by reduced levels of phosphorylated AKT, percentage tumor growth inhibition (%TGI) ranged from 35% in the least sensitive to 84% in the most sensitive model. Several biomarkers showed significant association with resistance, including elevated baseline levels of growth factor receptors (EGFR, pHER3 Y1197), PI3Kp85 regulatory subunit, anti-apoptotic protein BclXL, EMT (Vimentin, MMP9, IntegrinaV), NFKB pathway (IkappaB, RANKL), and intracellular signaling molecules including Caveolin, CBP, and KLF4, as well as treatment-induced increases in the levels of phosphorylated forms of Aurora kinases. Interestingly, increased AKT phosphorylation or PTEN loss at baseline were not significantly correlated to %TGI. These results provide important insights into biomarker development for PI3K inhibitors in TNBC.

Navitoclax combined with Alpelisib effectively inhibits Merkel cell carcinoma cell growth in vitro

Background:

Merkel cell carcinoma (MCC) is a highly malignant skin cancer. Despite major treatment improvements during the last decade, up to 50% of patients do not respond to therapy or develop recurrent disease. For these patients, alternative treatment options are urgently needed. Here, we assessed the efficacy of the combination of the BCL-2 inhibitor Navitoclax and the PI3K p110α inhibitor Alpelisib in MCC cell lines.

Methods:

The expression of BCL-2 was assessed by immunohistochemistry in MCC and MCC cell lines. Treatment with Navitoclax and Alpelisib alone and in combination was performed on four MCC cell lines. The decrease of cell viability during treatment was assessed by XTT assay and visualized for the combinations by 3D combinatorial index plotting. The increase of apoptotic cells was determined by cleaved PARP Western blotting and Annexin V staining.

Results:

Some 94% of MCCs and all three MCPyV-positive cell lines showed BCL-2 expression. Navitoclax monotreatment was shown to be highly effective when treating BCL-2-positive cell lines (IC₅₀-values ranging from 96.0 to 323.0 nM). The combination of Alpelisib and Navitoclax resulted in even stronger synergistic and prolonged inhibitions of MCC cell viability through apoptosis up to 4 days.

Discussion:

Our results show that the anti-apoptotic BCL-2 is frequently expressed in MCC and MCC cell lines. Inhibition of BCL-2 by Navitoclax in combination with Alpelisib revealed a strong synergy and prolonged inhibition of MCC cell viability and induction of apoptosis. The combination of Navitoclax and Alpelisib is a novel potential treatment option for MCC patients.

Targeting Bcl-2 Proteins in Acute Myeloid Leukemia

B cell lymphoma 2 (BCL-2) family proteins play an important role in intrinsic apoptosis. Overexpression of BCL-2 proteins in acute myeloid leukemia can circumvent resistance to apoptosis and chemotherapy. Considering this effect, the exploration of anti-apoptotic BCL-2 inhibitors is considered to have tremendous potential for the discovery of novel pharmacological modulators in cancer. This review outlines the impact of BCL-2 family proteins on intrinsic apoptosis and the development of acute myeloid leukemia (AML). Furthermore, we will also review the new combination therapy with venetoclax that overcomes resistance to venetoclax and discuss biomarkers of treatment response identified in early-phase clinical trials.

miRNA Modulation and Antitumor Activity by the Extra-Virgin Olive Oil Polyphenol Oleacein in Human Melanoma Cells

Extra-virgin olive oil (EVOO) polyphenols contribute to Mediterranean diet health-promoting properties. One of the most abundant secoiridoid present in EVOO, Oleacein (OA), demonstrated anticancer activity against several tumors. Nevertheless, its role against melanoma has not still investigated. This study aimed at determining in vitro the antimelanoma activity of OA and the relative mechanism of action. OA induced cell growth inhibition in 501Mel melanoma cells with an IC50 in the low micromolar range of concentrations. Moreover, an OA concentration approximating the IC50 induced G1/S phase arrest, DNA fragmentation, and downregulation of genes encoding antiapoptotic (BCL2 and MCL1) and proproliferative (c-KIT, K-RAS, PIK3R3, mTOR) proteins, while increased transcription levels of the proapoptotic protein BAX. Concordantly, OA increased the levels of miR-193a-3p (targeting MCL1, c-KIT and K-RAS), miR-193a-5p (targeting PIK3R3 and mTOR), miR-34a-5p (targeting BCL2 and c-KIT) and miR-16-5p (miR-16-5p targeting BCL2, K-RAS and mTOR), while decreased miR-214-3p (targeting BAX). These modulatory effects might contribute to the inhibition of 501Mel melanoma cell growth observed after treatment with an olive leaves-derived formulation rich in OA, with potential application against in situ cutaneous melanoma. Altogether, these results demonstrate the ability of OA to contrast the proliferation of cutaneous melanoma cells through the transcriptional modulation of relevant genes and microRNAs, confirming the anticancer potential of EVOO and suggesting OA as a chemopreventive agent for cancer disease therapy.

Targeting PI3K/Akt/mTOR in AML: Rationale and Clinical Evidence

Acute myeloid leukemia (AML) is a highly heterogeneous hematopoietic malignancy characterized by excessive proliferation and accumulation of immature myeloid blasts in the bone marrow. AML has a very poor 5-year survival rate of just 16% in the UK; hence, more efficacious, tolerable, and targeted therapy is required. Persistent leukemia stem cell (LSC) populations underlie patient relapse and development of resistance to therapy. Identification of critical oncogenic signaling pathways in AML LSC may provide new avenues for novel therapeutic strategies. The phosphatidylinositol-3-kinase (PI3K)/Akt and the mammalian target of rapamycin (mTOR) signaling pathway, is often hyperactivated in AML, required to sustain the oncogenic potential of LSCs. Growing evidence suggests that targeting key components of this pathway may represent an effective treatment to kill AML LSCs. Despite this, accruing significant body of scientific knowledge, PI3K/Akt/mTOR inhibitors have not translated into clinical practice. In this article, we review the laboratory-based evidence of the critical role of PI3K/Akt/mTOR pathway in AML, and outcomes from current clinical studies using PI3K/Akt/mTOR inhibitors. Based on these results, we discuss the putative mechanisms of resistance to PI3K/Akt/mTOR inhibition, offering rationale for potential candidate combination therapies incorporating PI3K/Akt/mTOR inhibitors for precision medicine in AML.

Generation and characterization of U937-TR: a platform cell line for inducible gene expression in human macrophages

Monocytes and macrophages are involved in a wide range of biological processes and parasitic diseases. The characterization of the molecular mechanisms governing such processes usually requires precise control of the expression of genes of interest. We implemented a tetracycline-controlled gene expression system in the U937 cell line, one of the most used in vitro models for the research of human monocytes and macrophages. Here we characterized U937-derived cell lines in terms of phenotypic (morphology and marker expression) and functional (capacity for phagocytosis and for Leishmania parasite hosting) changes induced by phorbol-12-myristate-13-acetate (PMA). Finally, we provide evidence of tetracycline-inducible and reversible Lamin-A gene silencing of the PMA-differentiated U937-derived cells.

Selective inhibition of interleukin-1 receptor-associated kinase 1 ameliorates lipopolysaccharide-induced sepsis in mice

Interleukin-1 receptor-associated kinases (IRAKs), particularly IRAK1 and IRAK4, are important in transducing signal from Toll-like receptor 4. We interrogated if a selective inhibition of IRAK1 could alleviate lipopolysaccharide (LPS)-induced sepsis. In this study, we tested the impact of a novel selective IRAK1 inhibitor Jh-X-119-01 on LPS-induced sepsis in mice. Survival at day 5 was 13.3% in control group where septic mice were treated by vehicle, while the values were 37.5% (p = 0.046, vs. control) and 56.3% (p = 0.003, vs. control) for 5 mg/kg and 10 mg/kg Jh-X-119-01-treated mice. Jh-X-119-01 alleviated lung injury and reduced production of TNFα and IFNγ in peritoneal macrophages. Jh-X-119-01 decreased phosphorylation of NF-κB and mRNA levels of IL-6 and TNFα in LPS-treated macrophages in vitro. Jh-X-119-01 selectively inhibited IRAK1 phosphorylation comparing with a non-selective IRAK1/4 inhibitor which simultaneously inhibited phosphorylation of IRAK1 and IRAK4. Both Jh-X-119-01 and IRAK1/4 inhibitor increased survival of septic mice, but Jh-X-119-01-treated mice had higher blood CD11b⁺ cell counts than IRAK1/4 inhibitor-treated ones [24 h: (1.18 ± 0.26) × 10⁶/ml vs. (0.79 ± 0.20) × 10⁶/ml, p = 0.001; 48 h: (1.00 ± 0.30) × 10⁶/ml vs. (0.67 ± 0.23) × 10⁶/ml, p = 0.042]. IRAK1/4 inhibitor induced more apoptosis of macrophages than Jh-X-119-01 did in vitro. IRAK1/4 inhibitor decreased protein levels of anti-apoptotic BCL-2 and MCL-1 in RAW 264.7 and THP-1 cells, an effect not seen in Jh-X-119-01-treated cells. In conclusion, Jh-X-119-01 selectively inhibited activation of IRAK1 and protected mice from LPS-induced sepsis. Jh-X-119-01 showed less toxicity on macrophages comparing with a non-selective IRAK1/4 inhibitor.

Non-Thermal Plasma Induces Antileukemic Effect Through mTOR Ubiquitination

Non-thermal plasma (NTP) has been studied as a novel therapeutic tool for cancer that does not damage healthy cells. In this study, we show that NTP-treated solutions (NTS) can induce death in various leukemia cells through mechanistic target of rapamycin (mTOR) ubiquitination. Previously, we manufactured and demonstrated the efficacy of NTS in solid cancers. NTS did not exhibit any deleterious side effects, such as acute death or weight loss in nude mice. In the present study, NTS induced cell death in myeloid leukemia cells, including acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). We found that mTOR was downregulated in NTS-treated cells via the ubiquitin-proteasome system (UPS). We also identified ‘really interesting new gene’ finger protein 126 (RNF126) as a novel binding protein for mTOR through protein arrays and determined the role of E3 ligase in NTS-induced mTOR ubiquitination. NTS-derived reactive oxygen species (ROS) affected RNF126 expression and lysosomal dysfunction. These findings suggest that NTS has potential antileukemic effects through RNF126-mediated mTOR ubiquitination with no deleterious side effects. Thus, NTS may represent a new therapeutic method for chemotherapy-resistant leukemia.

Cell Death Pathways in Lymphoid Malignancies

PURPOSE OF REVIEW

This review highlights the importance of the Bcl-2 family members in lymphoma cell survival and discusses the approaches to modulate their function, directly or indirectly, to advance lymphoma therapeutics.

RECENT FINDINGS

The balance of cell death versus survival is ultimately leveraged at the mitochondria. Mitochondrial outer membrane permeabilization (MOMP) is the critical event that governs the release of pro-apoptotic molecules from the intermembrane mitochondrial space. MOMP is achieved through the coordinated actions of pro- and anti-apoptotic Bcl-2 family member proteins. Recognition of functional alterations among the Bcl-2 family member proteins led to identification of tractable targets to combat hematologic malignancies. A new class of drugs, termed BH3 mimetics, was introduced in the clinic. Venetoclax, a Bcl-2 inhibitor, received regulatory approvals in therapy of chronic lymphocytic leukemia and acute myeloid leukemia. Alternative pro-survival Bcl-2 family proteins, in particular Mcl-1, have been successfully targeted in preclinical studies using novel-specific BH3 mimetics. Finally, anti-apoptotic Bcl-2 family members may be targeted indirectly, via interference with the pro-survival signaling pathways, e.g., phosphoinotiside-3 kinase, B-cell receptor signaling, and NF-κB.

Transcriptional Silencing of MCL-1 Through Cyclin-Dependent Kinase Inhibition in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the most common adult acute leukemia. Survival remains poor, despite decades of scientific advances. Cytotoxic induction chemotherapy regimens are standard-of-care for most patients. Many investigations have highlighted the genomic heterogeneity of AML, and several new targeted therapeutic options have recently been approved. Additional novel therapies are showing promising clinical results and may rapidly transform the therapeutic landscape of AML. Despite the emerging clinical success of B-cell lymphoma (BCL)-2 targeting in AML and a large body of preclinical data supporting myeloid leukemia cell (MCL)-1 as an attractive therapeutic target for AML, MCL-1 targeting remains relatively unexplored, although novel MCL-1 inhibitors are under clinical investigation. Inhibitors of cyclin-dependent kinases (CDKs) involved in the regulation of transcription, CDK9 in particular, are being investigated in AML as a strategy to target MCL-1 indirectly. In this article, we review the basis for CDK inhibition in oncology with a focus on relevant preclinical mechanism-of-action studies of CDK9 inhibitors in the context of their therapeutic potential specifically in AML.

Formononetin attenuates monocrotaline‑induced pulmonary arterial hypertension via inhibiting pulmonary vascular remodeling in rats

Pulmonary arterial hypertension (PAH) is a life‑threatening disease induced by the excessive proliferation and reduced apoptosis of pulmonary artery smooth muscle cells (PASMCs). Formononetin (FMN) is a natural isoflavone with numerous cardioprotective properties, which can inhibit the proliferation and induce the apoptosis of tumor cells; however, whether FMN has a therapeutic effect on PAH remains unclear. In the present study, PAH was induced in rats with monocrotaline (MCT, 60 mg/kg); rats were then administered FMN (10, 30 or 60 mg/kg/day). At the end of the experiment, hemodynamic changes, right ventricular hypertrophy and lung morphological characteristics were evaluated. α‑smooth muscle actin (α‑SMA), proliferating cell nuclear antigen (PCNA), and TUNEL were detected by immunohistochemical staining. The expression of PCNA, Bcl‑2‑associated X protein (Bax), Bcl‑2 and, cleaved caspase‑3, and activation of AKT and ERK were examined by western blot analysis. The results demonstrated that FMN significantly ameliorated the right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling induced by MCT. FMN also attenuated MCT‑induced increased expression of α‑SMA and PCNA. The ratio of Bax/Bcl‑2 and cleaved caspase‑3 expression increased in rat lung tissue in response to FMN treatment. Furthermore, reduced phosphorylation of AKT and ERK was also observed in FMN‑treated rats. Therefore, FMN may provide protection against MCT‑induced PAH by preventing pulmonary vascular remodeling, potentially by suppressing the PI3K/AKT and ERK pathways in rats.

The role of exosomes and MYC in therapy resistance of acute myeloid leukemia: Challenges and opportunities

Acute myeloid leukemia (AML) is caused by abnormal production of white blood cells, red blood cells or platelets. The leukemia cells communicate with their microenvironment through nano-vesicle exosomes that are 30-100 nm in diameter. These nano-vesicles are released from body fluids upon fusion of an endocytic compartment with the cell membrane. Exosomes function as cargo to deliver signaling molecules to distant cells. This allows cross-talk between hematopoietic cells and other distant target cell environments. Exosomes support leukemia growth by acting as messengers between tumor cells and the microenvironment as well as inducing oncogenic factors such as c-Myc. Exosomes have also been used as biomarkers in the clinical diagnosis of leukemia. Glycogen synthase kinase-3 (GSK-3) and protein phosphatase 2A (PP2A) are two crucial signaling molecules involved in the AML pathogenesis and MYC stability. GSK-3 is a serine/threonine protein kinase that coordinates with over 40 different proteins during physiological/pathological conditions in blood cells. The dysregulation in GSK-3 has been reported during hematological malignancies. GSK-3 acts as a tumor suppressor by targeting c-MYC, MCL-1 and β-catenin. Conversely, GSK-3 can also act as tumor promoter in some instances. The pharmacological modulators of GSK-3 such as ABT-869, 6-Bromoindirubin-3'-oxime (BIO), GS-87 and LY2090314 have shown promise in the treatment of hematological malignancy. PP2A is a heterotrimeric serine/threonine phosphatase involved in the regulation of hematological malignancy. PP2A-activating drugs (PADs) can effectively antagonize leukemogenesis. The discovery of exosomes, kinase inhibitors and phosphatase activators have provided new hope to the leukemia patients. This review discusses the role of exosomes, GSK-3 and PP2A in the pathogenesis of leukemia. We provide evidence from both preclinical and clinical studies.

Schistosoma japonicum Infection Promotes the Response of Tfh Cells Through Down-Regulation of Caspase-3-Mediating Apoptosis

CD4⁺ T follicular helper (Tfh) cells, a new subset of immune cells, have been demonstrated to be involved in granulomatous responses to Schistosoma japonicum (S. japonicum) infection. However, the role and underlying mechanisms of Tfh cell aggregation in S. japonicum infection remain incompletely understood. In this study, we provide evidence that S. japonicum infection enhances the accumulation of Tfh cells in the spleen, lymph nodes, and peripheral blood of C57BL/6 mice. Infection-induced Tfh cells exhibited more potent effects directly on B cell responses than the control Tfh cells (P < 0.05). Furthermore, reduced apoptosis of Tfh cells was found both in S. japonicum infected mice and in soluble egg antigen (SEA) treated Tfh cells (P < 0.05). Mechanistic studies reveal that caspase-3 is the primary drivers of down-regulated apoptotic Tfh cell death in S. japonicum infection. In summary, this study demonstrates that Tfh cell accumulation might have an impact on the generation of immune responses in S. japonicum infection, and caspase-3 signaling mediated apoptosis down-regulation might responsible for the accumulation of Tfh cell in this course.

Targeting Leukemia Stem Cell-Niche Dynamics: A New Challenge in AML Treatment

One of the most urgent needs in AML is to improve the disease cure rate as relapse still occurs in 60–80% of patients. Recent evidence suggests that dismal clinical outcomes may be improved by a better definition of the tight interaction between the AML cell population and the bone marrow (BM) microenvironment (“the niche”); the latter has been progressively highlighted to have an active role in the disease process. It has now been well established that the leukemic population may misinterpret niche-derived signals and remodel the niche, providing a shelter to AML cells and protecting them from the cytotoxic effects of chemoradiotherapy. Novel imaging technological advances and preclinical disease models have revealed that, due to the finite number of BM niches, leukemic stem cells (LSCs) and normal hematopoietic stem cells (HSCs) compete for the same functional areas. Thus, the removal of LSCs from the BM niche and the promotion of normal HSC engraftment should be the primary goals in antileukemic research. In addition, it is now becoming increasingly clear that AML-niche dynamics are disease stage specific. In AML, the niche has been linked to disease pathogenesis in the preleukemic stage, the niche becomes permissive once leukemic cells are established, and the niche is transformed into a self-reinforcing structure at a later disease stage. These concepts have been fostered by the demonstration that, in unrelated AML types, endosteal vessel loss occurs as a primary AML-induced niche alteration, and additional AML-induced alterations of the niche and normal hematopoiesis evolve focally and in parallel. Obviously, this endosteal vessel loss plays a fundamental role in AML pathogenesis by causing excessive vascular permeability, hypoxia, altered perfusion, and reduced drug delivery. Each of these alterations may be effectively targeted by various therapeutic procedures, but preservation of endosteal vessel integrity might be the best option for any future antileukemic treatment.

The concept of leukaemic stem cells in acute myeloid leukaemia 25 years on: hitting a moving target

The concept of leukaemic stem cells (LSCs) was experimentally suggested 25 years ago through seminal data from John Dick's group, who showed that a small fraction of cells from acute myeloid leukaemia (AML) patients were able to be adoptively transferred into immunodeficient mice. The initial estimation of the frequency was 1:250 000 leukaemic cells, clearly indicating the difficulties ahead in translating knowledge on LSCs to the clinical setting. However, the field has steadily grown in interest, expanse and importance, concomitantly with the realisation of the molecular background for AML culminating in the sequencing of hundreds of AML genomes. The literature is now ripe with contributions describing how different molecular aberrations are more or less specific for LSCs, as well as reports showing selectivity in targeting LSCs in comparison to normal haematopoietic stem and progenitor cells. However, we argue here that these important data have not yet been fully realised within the clinical setting. In this clinically focused review, we outline the difficulties in identifying and defining LSCs at the individual patient level, with special emphasis on intraclonal heterogeneity. In addition, we suggest areas of future focus in order to realise the concept as real-time benefit for AML patients.

Formaldehyde induces the apoptosis of BMCs of BALB/c mice via the PTEN/PI3K/Akt signal transduction pathway

The International Agency for Research on Cancer has classified formaldehyde (FA) as a leukemogen to humans in 2012; however, the underlying mechanism remains unclear. Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor‑suppressor gene and can negatively regulate the phosphoinositide 3‑kinase (PI3K)/protein kinase B (Akt) signal transduction pathway, which is associated with cell proliferation, apoptosis and carcinogenesis. To determine the association between FA and the PTEN/PI3K/Akt signal transduction pathway, flow cytometry, reverse transcription‑quantitative polymerase chain reaction, western blotting and immunohistochemical analysis were conducted. Bone marrow cells were obtained from BALB/c mice, divided into the control (untreated cells) and FA groups, which were treated with various doses of FA (50, 100 and 200 µmol/l). Following treatment with FA for 24 h, cell viability, the cell cycle, apoptosis, and the expression of PTEN, PI3K and Akt, as well as the protein expression of B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X (Bax), and Caspases‑3 and ‑9 were examined. Furthermore, 10 µmol/PI3K inhibitor (LY294002) was applied to inhibit the PTEN/PI3K/Akt signal transduction pathway and 100 µmol/l FA was selected for treatment; alteration in the cell cycle were analyzed. The results demonstrated that FA could suppress cell viability, and downregulate PTEN and Bcl‑2; the expression of PI3K, Akt, Bax, and Caspases‑3 and ‑9 were upregulated. Additionally, FA was reported to induce cell cycle arrest at the G0/G1 phase and apoptosis. Following the application of LY294002 to inhibit the PTEN/PI3K/Akt signal transduction pathway, the numbers of cells arrested in the G0/G1 phase were significantly increased in the PI3K inhibitor group compared with the control (P<0.01); however, no significant change in the number of G0/G1 cells compared with FA group was observed (P>0.05). The results of the present study suggested that the PTEN/PI3K/Akt signal transduction pathway served an important role in the process of FA‑induced apoptosis, which may be associated with regulating the cell cycle; thus, cell proliferation may be affected.

Determinants of Ion-Transporter Cancer Cell Death

Recently, we showed that synthetic anion transporters DSC4P-1 and SA-3 had activity related to cancer cell death. They were found to increase intracellular chloride and sodium ion concentrations. They were also found to induce apoptosis (DSC4P-1) and both induce apoptosis and inhibit autophagy (SA-3). However, determinants underlying these phenomenological findings were not elucidated. The absence of mechanistic understanding has limited the development of yet-improved systems. Here, we show that three synthetic anion transporters, DSC4P-1, SA-3, and 8FC4P, induce osmotic stress in cells by increasing intracellular ion concentrations. This triggers the generation of reactive oxygen species via a sequential process and promotes caspase-dependent apoptosis. In addition, two of the transporters, SA-3 and 8FC4P, induce autophagy by increasing the cytosolic calcium ion concentration promoted by osmotic stress. However, they eventually inhibit the autophagy process as a result of their ability to disrupt lysosome function through a transporter-mediated decrease in a lysosomal chloride ion concentration and an increase in the lysosomal pH.

Camel Whey Protein Disrupts the Cross-Talk Between PI3K and BCL-2 Signals and Mediates Apoptosis in Primary Acute Myeloid Leukemia Cells

In the present study, we investigated the impact of camel whey protein (CWP) on the survival of primary acute myeloid leukemia (AML) cells that were isolated from 20 patients diagnosed with AML. We found that CWP induced apoptosis in the primary AML cells without affecting the normal PBMCs that were isolated from healthy individuals, as determined by PI/annexin V double staining followed by flow-cytometry analysis. Furthermore, we demonstrated that these primary AML cells exhibited aberrant phosphorylation of AKT, mTOR and STAT3. Treatment of AML cells with CWP mediated significant reduction in the phosphorylation of AKT, mTOR and STAT3. Additionally, we demonstrated that blockade of PI3K/AKT signaling pathway by wortmannin (WM) impaired the expression of Bcl-2 and Bcl_XL in the primary AML cells, suggesting an essential cross-talk between PI3K and Bcl-2 that maintains the survival of AML cells. In this context, treatment of AML cells with CWP disrupted the PI3K/Bcl-2 cross-talk; significantly downregulated the expression of anti-apoptotic Bcl-2 family members Bcl-2 and Bcl_XL; markedly upregulated the expression of the pro-apoptotic Bcl-2 family members Bak and Bax; and subsequently sensitized tumor cells to growth arrest. Our data revealed the therapeutic potential of CWP and the underlying mechanisms against leukemia.

lncRNA GHET1 knockdown suppresses breast cancer activity in vitro and in vivo

Long non-coding RNA gastric carcinoma high-expressed transcript 1 (lncRNA GHET1) is highly expressed in many tumors. The aim of the present study was to determine whether GHET1 inhibition decreases growth and metastasis of MCF-7 breast cancer cells by modulating epidermal growth factor receptor (EGFR) expression. In vitro, lncRNA GHET1 knockdown suppressed cell proliferation, migration, and invasion and enhanced cell apoptosis by maintaining MCF-7 cells in the G1 phase of the cell cycle. Furthermore, lncRNA GHET1 knockdown reduced the expression of EGFR and related proteins. Treatment of mice with a GHET1 inhibitor prevented tumor growth in vivo. The results indicate that lncRNA GHET1 inhibition directly suppresses EGFR expression, significantly inhibiting the downstream PI3K/AKT/Cyclin D1/MMP2/9 pathway. This mechanism may underlie the suppression of breast cancer cell activities including proliferation, migration, and invasion. In conclusion, lncRNA GHET1 knockdown suppresses tumor growth and metastasis by suppressing the activity of EGFR and downstream pathways.

Bromodomain‑containing protein 7 sensitizes breast cancer cells to paclitaxel by activating Bcl2‑antagonist/killer protein

Our previous study demonstrated that bromodomain‑containing protein 7 (BRD7) inhibits cell proliferation and tumor growth, restoring the expression of B‑cell lymphoma 2 antagonist/killer (Bak) sensitized breast cancer cells to paclitaxel. However, the association between BRD7 and paclitaxel sensitization, as well as BRD7 and Bak in breast cancer remains unknown. In the present study, immunochemical staining was performed to measure the expression of BRD7 and Bak in breast cancer tissues. Cell Counting Kit‑8 assay, flow cytometry and tumor xenograft procedures were performed to evaluate the biological role of BRD7 and Bak in breast cancer cells. Western blotting, reverse transcription‑quantitative polymerase chain reaction, chromatin immunoprecipitation and luciferase reporter assays were also performed. BRD7 was positively correlated with Bak levels in breast cancer tissues, and the survival rate of patients with low Bak and BRD7 expression was significantly lower than that of patients with high Bak and BRD7 expression. In addition, BRD7 activated Bak promoter activity and induced Bak expression in an indirect manner. Furthermore, ectopic expression of BRD7 inhibited cell proliferation, tumor growth and sensitized cancer cells to paclitaxel, while knockdown of Bak abolished BRD7‑mediated inhibitory effects on cell proliferation and paclitaxel sensitization in breast cancer cells whether in vitro and in vivo. The results demonstrated that BRD7 inhibits cell proliferation and sensitizes breast cancer cells to paclitaxel by activating Bak; they also provide promising targets for the diagnosis and treatment of breast cancer.

Camalexin Induces Apoptosis via the ROS-ER Stress-Mitochondrial Apoptosis Pathway in AML Cells

Camalexin is a phytoalexin that accumulates in various cruciferous plants upon exposure to environmental stress and plant pathogens. It was shown that camalexin has potent antitumor properties, but its underlying mechanisms are still elusive. In the present study, we evaluated the effects of camalexin on human leukemic cells and normal polymorph nuclear cells. CCK-8 assay was used to determine cell viability after camalexin treatment. Apoptosis, intracellular reactive oxygen species (ROS) levels, and loss of mitochondrial membrane potential (MMP) were measured by flow cytometry. The activity of SOD, catalase, and ratio of GSH/GSSG were assayed. ER stress and apoptotic signaling pathway was examined by Western blot. Xenograft mice were used to verify the effect of camalexin in vivo. Our results indicated that camalexin inhibited viability of leukemic but not normal polymorph nuclear cells. Furthermore, camalexin induces apoptosis via the mitochondrial pathway in a caspase-dependent manner. We also observed ER stress is located upstream of apoptosis induced by camalexin. Besides, ROS levels, SOD activity, CAT activity, and GSSG levels were significantly enhanced while the GSH level was decreased after treatment of camalexin. In addition, the generation of ROS is critical for the ER stress and apoptosis induced by camalexin. Finally, administration of camalexin suppresses xenograft tumor graft growth without obvious toxicity. Taken together, this study indicates that camalexin exerts antitumor effects against leukemia cells via the ROS-ER stress-mitochondrial apoptosis pathway.

Cyclocarya paliurus Leaves Tea Improves Dyslipidemia in Diabetic Mice: A Lipidomics-Based Network Pharmacology Study

Hyperlipidemia and hepatic steatosis afflict over 75% of patients with type 2 diabetes, causing diabetic dyslipidemia. Cyclocarya paliurus (CP) leaf is a herbal tea which has long been consumed by the Chinese population, particularly people suffering from obesity and diabetes. CP appears to exhibit a hypolipidemic effect in lipid loaded mice (Kurihara et al., 2003), although the detailed mechanisms and active ingredients for this hypolipidemic effect have not yet been answered. In this study, we investigated the beneficial effects of CP and predicted the mechanisms by utilizing lipidomics, serum-pharmacochemistry and network pharmacology approaches. Our results revealed that serum and hepatic levels of total triglyceride (TG), total cholesterol (T-CHO), low-density lipoproteins (LDL) and high-density lipoproteins (HDL), as well as 30 lipids including cholesterol ester (CE), diglyceride (DG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), and sphingomyelin (SM) in CP-treated mice were improved in comparison with untreated diabetic mice. In parallel, 14 phytochemical compounds of CP were determined in mice serum after CP administration. Mechanistically, the network pharmacology analysis revealed the predicted targets of CP’s active ingredients ALOX12, APP, BCL2, CYP2C9, PTPN1 and linked lipidome targets PLD2, PLA2G(s), and PI3K(s) families could be responsible for the CP effects on diabetic dyslipidemia. In conclusion, this study revealed the beneficial effects of CP on diabetic dyslipidemia are achieved by reducing accumulation of hepatic lipid droplets and regulating circulatory lipids in diabetic mice, possibly through PI3K signaling and MAPK signaling pathways. GRAPHICAL ABSTRACT