Phosphorylation of Bcl2 and regulation of apoptosis

Plant protein diet-induced hypoimmunity by affecting the spiral valve intestinal microbiota and bile acid enterohepatic circulation in Amur sturgeon (Acipenser schrenckii)

An 8-week growth trial was conducted to study enterohepatic recirculation of bile acid metabolism and the intestinal microbiota of Amur sturgeon (Acipenser schrenckii) fed with three diets, including 540 g/kg, 270 g/kg or 0 g/kg fishmeal, which was correspondingly replaced by a plant protein blend (named P0, P50 and P100, respectively). The diets were designed to be isonitrogenous, isoenergetic and essential nutrients balanced. With rising levels of dietary plant protein, disruption of the spiral valve intestinal microbiota and more morbidity with liver disease were observed in the P100 group, although there were no haematological abnormalities observed. An obvious bile acids enterohepatic circulation disorder was found with phenotypes of increased liver bile acids compensatory synthesis, and reduced expression of bile acid receptors (FXR and TGR5), which induced BA accumulative toxicity. Accompanied by increased oxidative stress, it further induced hepatic lesions and hypoimmunity, which were non-negligible reasons for the high mortality and low utilization ability of plant protein by Amur sturgeon.

Reactivating latent HIV with PKC agonists induces resistance to apoptosis and is associated with phosphorylation and activation of BCL2

Eradication of HIV-1 by the "kick and kill" strategy requires reactivation of latent virus to cause death of infected cells by either HIV-induced or immune-mediated apoptosis. To date this strategy has been unsuccessful, possibly due to insufficient cell death in reactivated cells to effectively reduce HIV-1 reservoir size. As a possible cause for this cell death resistance, we examined whether leading latency reversal agents (LRAs) affected apoptosis sensitivity of CD4 T cells. Multiple LRAs of different classes inhibited apoptosis in CD4 T cells. Protein kinase C (PKC) agonists bryostatin-1 and prostratin induced phosphorylation and enhanced neutralizing capability of the anti-apoptotic protein BCL2 in a PKC-dependent manner, leading to resistance to apoptosis induced by both intrinsic and extrinsic death stimuli. Furthermore, HIV-1 producing CD4 T cells expressed more BCL2 than uninfected cells, both in vivo and after ex vivo reactivation. Therefore, activation of BCL2 likely contributes to HIV-1 persistence after latency reversal with PKC agonists. The effects of LRAs on apoptosis sensitivity should be considered in designing HIV cure strategies predicated upon the "kick and kill" paradigm.

Development of Conformational Antibodies to Detect Bcl-xL's Amyloid Aggregates in Metal-Induced Apoptotic Neuroblastoma Cells

Bcl-xL, a member of the Bcl-2 family, is a pro-survival protein involved in apoptosis regulation. We have previously reported the ability of Bcl-xL to form various types of fibers, from native to amyloid conformations. Here, we have mimicked the effect of apoptosis-induced caspase activity on Bcl-xL by limited proteolysis using trypsin. We show that cleaved Bcl-xL (ΔN-Bcl-xL) forms fibers that exhibit the features of amyloid structures (BclxLcf37). Moreover, three monoclonal antibodies (mAbs), produced by mouse immunization and directed against ΔN-Bcl-xL or Bcl-xL fibers, were selected and characterized. Our results show that these mAbs specifically target ΔN-Bcl-xL in amyloid fibers in vitro. Upon metal-stress-induced apoptosis, these mAbs are able to detect the presence of Bcl-xL in amyloid aggregates in neuroblastoma SH-SY5Y cell lines. In conclusion, these specific mAbs directed against amyloidogenic conformations of Bcl-xL constitute promising tools for studying, in vitro and in cellulo, the contribution of Bcl-xL in apoptosis. These mAbs may further help in developing new diagnostics and therapies, considering Bcl-xL as a strategic target for treating brain lesions relevant to stroke and neurodegenerative diseases.

Elaeagnus angustifolia Plant Extract Inhibits Epithelial-Mesenchymal Transition and Induces Apoptosis via HER2 Inactivation and JNK Pathway in HER2-Positive Breast Cancer Cells

Elaeagnus angustifolia (EA) is a medicinal plant used for treating several human diseases in the Middle East. Meanwhile, the outcome of EA extract on HER2-positive breast cancer remains nascent. Thus, we herein investigated the effects of the aqueous EA extract obtained from the flowers of EA on two HER2-positive breast cancer cell lines, SKBR3 and ZR75-1. Our data revealed that EA extract inhibits cell proliferation and deregulates cell-cycle progression of these two cancer cell lines. EA extract also prevents the progression of epithelial-mesenchymal transition (EMT), an important event for cancer invasion and metastasis; this is accompanied by upregulations of E-cadherin and β-catenin, in addition to downregulations of vimentin and fascin, which are major markers of EMT. Thus, EA extract causes a drastic decrease in cell invasion ability of SKBR3 and ZR75-1 cancer cells. Additionally, we found that EA extract inhibits colony formation of both cell lines in comparison with their matched control. The molecular pathway analysis of HER2 and JNK1/2/3 of EA extract exposed cells revealed that it can block HER2 and JNK1/2/3 activities, which could be the major molecular pathway behind these events. Our findings implicate that EA extract may possess chemo-preventive effects against HER2-positive breast cancer via HER2 inactivation and specifically JNK1/2/3 signaling pathways.

Beyond Synthetic Lethality: Charting the Landscape of Pairwise Gene Expression States Associated with Survival in Cancer

The phenotypic effect of perturbing a gene's activity depends on the activity level of other genes, reflecting the notion that phenotypes are emergent properties of a network of functionally interacting genes. In the context of cancer, contemporary investigations have primarily focused on just one type of functional relationship between two genes-synthetic lethality (SL). Here, we define the more general concept of "survival-associated pairwise gene expression states" (SPAGEs) as gene pairs whose joint expression levels are associated with survival. We describe a data-driven approach called SPAGE-finder that when applied to The Cancer Genome Atlas (TCGA) data identified 71,946 SPAGEs spanning 12 distinct types, only a minority of which are SLs. The detected SPAGEs explain cancer driver genes' tissue specificity and differences in patients' response to drugs and stratify breast cancer tumors into refined subtypes. These results expand the scope of cancer SPAGEs and lay a conceptual basis for future studies of SPAGEs and their translational applications.

Gene therapy with apoptosis-associated speck-like protein, a newly described schwannoma tumor suppressor, inhibits schwannoma growth in vivo

BACKGROUND

We evaluated apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) as a schwannoma tumor suppressor and explored its utilization in a schwannoma gene therapy strategy that may be translated to clinical use.

METHODS

ASC protein expression and mRNA level were assessed in human schwannoma by immunohistochemistry and quantitative PCR, respectively. Methylation- specific PCR was used to assess ASC promoter methylation. The effect of ASC overexpression in schwannoma cells was evaluated through ATP-based viability, lactate dehydrogenase release, and apoptosis staining. Western blotting and colorimetric assay were used to test the effect of ASC overexpression on endogenous pro-apoptotic pathways. Bioluminescence imaging, behavioral testing, and immunohistochemistry in human xenograft and murine allograft schwannoma models were used to examine the efficacy and toxicity of intratumoral injection of adeno-associated virus (AAV) vector encoding ASC.

RESULTS

ASC expression was suppressed via promoter methylation in over 80% of the human schwannomas tested. ASC overexpression in schwannoma cells results in cell death and is associated with activation of endogenous caspase-9, caspase-3, and upregulation of BH3 interacting-domain death agonist. In a human xenograft schwannoma model, AAV1-mediated ASC delivery reduced tumor growth and resolved tumor-associated pain without detectable toxicity, and tumor control was associated with reduced Ki67 mitotic index and increased tumor-cell apoptosis. Efficacy of this schwannoma gene therapy strategy was confirmed in a murine schwannoma model.

CONCLUSION

We have identified ASC as a putative schwannoma tumor suppressor with high potential clinical utility for schwannoma gene therapy and generated a vector that treats schwannomas via a novel mechanism that does not overlap with current treatments.

GSK-J4 induces cell cycle arrest and apoptosis via ER stress and the synergism between GSK-J4 and decitabine in acute myeloid leukemia KG-1a cells

Background

GSK-J4 is the inhibitor of H3K27me3 demethylase. Recent studies demonstrated that GSK-J4 could affect the proliferation and apoptosis of a variety of cancer cells. However, the effects and underlying mechanisms of GSK-J4 on the proliferation and apoptosis of human acute myeloid leukemia (AML) KG-1a cells have not been explored thoroughly.

Methods

The effect of GSK-J4 on cell proliferation was assessed with CCK8, while cell cycle distribution and apoptosis were analyzed using flow cytometry. The proteins related to cell cycle, cell apoptosis, endoplastic reticulum (ER) stress and PKC-α/p-Bcl2 pathway were detected by Western blotting. The expression level of PKC-α mRNA was measured by quantitative real-time PCR.ER stress inhibitor 4-phenyl butyric acid (4-PBA) was used to explore the role of ER stress in GSK-J4 induced cell-cycle arrest and cell apoptosis. The combination effects of Decitabine and GSK-J4 on KG-1a cells proliferation and apoptosis were also evaluated by CCK8, flow cytometry and immunoblot analysis.

Results

GSK-J4 reduced cell viability and arrested cell cycle progression at the S phase by decreasing the expression of CyclinD1 and CyclinA2 and increasing that of P21. Moreover, GSK-J4 enhanced the expression of apoptosis-related proteins (cle-caspase-9 and bax) and inhibited PKC-a/p-Bcl2 pathway to promote cell apoptosis. In addition, ER stress-related proteins (caspase-12, GRP78 and ATF4) were increased markedly after exposure to GSK-J4. The effects of GSK-J4 on cell cycle, apoptosis and PKC-a/p-Bcl2 pathway were attenuated after treatment with ER stress inhibitor. Furthermore, decitabine could significantly inhibit the proliferation and induce the apoptosis of KG-1a cells after combined treatment with GSK-J4.

Conclusion

Taken together, this study provided evidence that ER stress could regulate the process of GSK-J4-induced cell cycle arrest, cell apoptosis and PKC-α/p-bcl2 pathway inhibition and demonstrated a potential combinatory effect of decitabine and GSK-J4 on leukemic cell proliferation and apoptosis.

Polygonum multiflorum extract support hair growth by elongating anagen phase and abrogating the effect of androgen in cultured human dermal papilla cells

Background

Dermal papilla cells (DPCs) play a key role in hair growth among the various cell types in hair follicles. Especially, DPCs determine the fate of hair follicle such as anagen to telogen transition and play a pivotal role in androgenic alopecia (AGA). This study was performed to elucidate the hair growth promoting effects of Polygonum multiflorum extract (PM extract) in cultured human DPCs and its underlying mechanisms.

Methods

The effects of PM extract on cultured DPCs were investigated. Cell viability and mitochondrial activity were measured by CCK-8 and JC-1 analysis, respectively. Western blotting, dot blotting, ELISA analysis, immunocytochemistry and real-time PCR analysis were also performed to elucidate the changes in protein and mRNA levels induced by PM extract. 3D cultured DPC spheroids were constructed for mimicking the in vivo DPs. The hair growth stimulatory effect of PM extract was evaluated using human hair follicle organ culture model.

Results

PM extract increased the viability and mitochondrial activity in cultured human DPCs in a dose dependent manner. The expression of Bcl2, an anti-apoptotic protein expressed dominantly in anagen was significantly increased and that of BAD, a pro-apoptotic protein expressed in early catagen was decreased by PM extract in cultured DPCs and/or 3D DPC spheroid culture. PM extract also decreased the expression of catagen inducing protein, Dkk-1. Growth factors including IGFBP2, PDGF and VEGF were increased by PM extract, revealed by dot blot protein analysis. We also have found that PM extract could reverse the androgenic effects of dihydrotestosterone (DHT), the most potent androgen. Finally, PM extract prolonged the anagen of human hair follicles by inhibiting catagen entry in human hair follicle organ culture model.

Conclusion

Our data strongly suggest that PM extract could promote hair growth by elongating the anagen and/or delaying the catagen induction of hair follicles through activation of DPCs.

Cranberry extract initiates intrinsic apoptosis in HL-60 cells by increasing BAD activity through inhibition of AKT phosphorylation

Background

Cranberry has been studied as a potential anticancer agent as it is capable of inducing apoptosis within cancer cells. The aim of this study was to better define the mechanism by which cranberry triggers apoptosis in HL-60 cells.

Methods

The study was carried on cranberry extracts (CB). Anti-apoptotic B-cell lymphoma-2 (BCL-2) and pro-apoptotic BCL-2-associated death promoter death (BAD) proteins in cell lysates were detected through Western blotting techniques. Equivalent protein loading was confirmed through anti-α-tubulin antibody.

Results

The results showed that treatment of HL-60 cells with CB causes a significant increase in the levels of caspase-9 and caspases-3/7 and increased mitochondrial outer membrane permeability, leading to the release of cytochrome C and Smac. These apoptotic events were associated with a significant decrease in protein kinase B (AKT) phosphorylation, which caused significant increase in BAD de-phosphorylation and promoted a sequence of events that led to intrinsic apoptosis.

Conclusion

The study findings have described a molecular framework for CB-initiated apoptosis in HL-60 cells and suggested a direction for future in vivo studies investigating the anticancer effect of cranberry.

Rs1894720 polymorphism is associated with the risk of age-related cataract by regulating the proliferation of epithelial cells in the lens via the signalling pathway of MIAT/miR-26b/BCL2L2

INTRODUCTION

Cataracts caused by old age are one of the most frequent causes for blindness and poor vision worldwide. In this study, we aimed to clarify the possible role of rs1894720 polymorphism in the pathogenesis of age-related cataract.

MATERIAL AND METHODS

Rs1894720 polymorphism genotype was detected by TaqMan. Bioinformatics analysis, luciferase assay, real-time PCR, western blot, and protein density analysis were conducted to establish the correlations between MIAT and miR-26b as well as between BCL2L2 and miR-26b. Flow cytometry and MTT assay were also performed to observe the effect of MIAT/miR-26b/BCL2L2 signalling pathway on the status of cell apoptosis and viability.

RESULTS

MIAT functioned as an endogenous competing RNA to sponge miR-26b. In addition, BCL2L2 was identified as a target of miR-26b. Therefore, the expression of miR-26b was obviously suppressed by MIAT or anti-miR-26b, while the mRNA and protein expression of BCL2L2 was up-regulated in the presence of MIAT or anti-miR-26b. Moreover, the positive effect of MIAT on BCL2L2 expression was exerted via inhibition of the expression of miR-26b. In addition, the cells transfected with MIAT or anti-miR-26b showed suppressed expression of caspase-3 and reduced apoptosis index but higher cell viability, indicating that MIAT could suppress cell apoptosis via inhibition of miR-26b expression. Furthermore, the subjects carrying the GT and TT genotypes of single-nucleotide polymorphism (SNP) rs1894720 were associated with a higher risk of age-related cataracts, as indicated by their odds ratio (OR) and p-values.

CONCLUSIONS

Rs1894720 SNP could down-regulate the expression of MIAT, thus leading to reduced BCL2L2 expression and enhanced epithelial cell apoptosis in the lens, eventually increasing the incidence of age-related cataract.

MOP-dependent enhancement of methadone on the effectiveness of ALA-PDT for A172 cells by upregulating phosphorylated JNK and BCL2

BACKGROUND

Methadone, as a long-acting opioid analgesic, shows an ability to sensitize the treatment of ALA-PDT for glioblastoma cells (A172) in vitro by promoting apoptosis. However, the mechanisms how methadone enhances the effectiveness of ALA-PDT for tumor cells remains to be clarified.

METHODS

The expression of mu opioid receptor (MOP), apoptosis, phosphorylated c-Jun N-terminal kinase (JNK) and phosphorylated apoptosis regulator B cell lymphoma 2 (BCL2) were measured by flow cytometry. Cytotoxicity was determined using Cell Counting Kit-8 (CCK-8). A MOP antagonist, naloxone, was used to evaluate the role of MOP in the above process.

RESULTS

It was found that A172 cells show the expression of MOP and that naloxone inhibits the enhancement of the methadone effect on apoptosis following ALA-PDT (p < 0.05). Phosphorylated JNK and BCL2 induced by ALA-PDT were promoted in the presence of methadone (p < 0.05). These methadone effects were also inhibited by naloxone (p < 0.05).

CONCLUSIONS

The results suggest that apoptosis induced by ALA-PDT is enhanced by methadone, mostly MOP-mediated, through the upregulation of accumulation of phosphorylated JNK and BCL2, leading to a promotion of cytotoxicity of ALA-PDT for A172 cells.

Activation of PERK Contributes to Apoptosis and G2/M Arrest by Microtubule Disruptors in Human Colorectal Carcinoma Cells ‡

Microtubule-targeting agents (MTAs) are widely used in cancer chemotherapy, but the therapeutic responses significantly vary among different tumor types. Protein kinase RNA-like endoplasmic reticular (ER) kinase (PERK) is an ER stress kinase, and the role of PERK in the anticancer effects of MTAs is still undefined. In the present study, taxol (TAX) and nocodazole (NOC) significantly induced apoptosis with increased expression of phosphorylated PERK (pPERK; Tyr980) in four human colon cancer cell lines, including HCT-15, COLO205, HT-20, and LOVO cells. Induction of G₂/M arrest by TAX and NOC with increases in phosphorylated Cdc25C and cyclin B1 protein were observed in human colon cancer cells. Application of the c-Jun N-terminal kinase (JNK) inhibitors SP600125 (SP) and JNK inhibitor V (JNKI) significantly reduced TAX- and NOC-induced apoptosis and G₂/M arrest of human colon cancer cells. Interestingly, TAX- and NOC-induced pPERK (Tyr980) protein expression was inhibited by adding the JNK inhibitors, SP and JNKI, and application of the PERK inhibitor GSK2606414 (GSK) significantly reduced apoptosis and G₂/M arrest by TAX and NOC, with decreased pPERK (Tyr980) and pJNK, phosphorylated Cdc25C, and Cyc B1 protein expressions in human colon cancer cells. Decreased viability by TAX and NOC was inhibited by knockdown of PERK using PERK siRNA in COLO205 and HCT-15 cells. Disruption of the mitochondrial membrane potential and an increase in B-cell lymphoma-2 (Bcl-2) protein phosphorylation (pBcl-2; Ser70) by TAX and NOC were prevented by adding the PERK inhibitor GSK and JNK inhibitor SP and JNKI. A cross-activation of JNK and PERK by TAX and NOC leading to anti-CRC actions including apoptosis and G₂/M arrest was first demonstrated herein.

The landscape of tiered regulation of breast cancer cell metabolism

Altered metabolism is a hallmark of cancer, but little is still known about its regulation. In this study, we measure transcriptomic, proteomic, phospho-proteomic and fluxomics data in a breast cancer cell-line (MCF7) across three different growth conditions. Integrating these multiomics data within a genome scale human metabolic model in combination with machine learning, we systematically chart the different layers of metabolic regulation in breast cancer cells, predicting which enzymes and pathways are regulated at which level. We distinguish between two types of reactions, directly and indirectly regulated. Directly-regulated reactions include those whose flux is regulated by transcriptomic alterations (~890) or via proteomic or phospho-proteomics alterations (~140) in the enzymes catalyzing them. We term the reactions that currently lack evidence for direct regulation as (putative) indirectly regulated (~930). Many metabolic pathways are predicted to be regulated at different levels, and those may change at different media conditions. Remarkably, we find that the flux of predicted indirectly regulated reactions is strongly coupled to the flux of the predicted directly regulated ones, uncovering a tiered hierarchical organization of breast cancer cell metabolism. Furthermore, the predicted indirectly regulated reactions are predominantly reversible. Taken together, this architecture may facilitate rapid and efficient metabolic reprogramming in response to the varying environmental conditions incurred by the tumor cells. The approach presented lays a conceptual and computational basis for mapping metabolic regulation in additional cancers.

JNK and phosphorylated Bcl-2 predict multiple sclerosis clinical activity and glatiramer acetate therapeutic response

In this study, we investigated the role of JNK and phospho-Bcl-2 as possible biomarkers of multiple sclerosis (MS) relapse and of glatiramer acetate (GA) therapeutic response in relapsing-remitting MS patients. We enrolled a cohort of 15 GA-treated patients and measured the expression of JNK1, JNK2, phospho-JNK and phospho-Bcl-2 through Western blotting of lysates from peripheral blood mononuclear cells collected at 0, 3, 6, and 12 months after initiating GA therapy. We found significantly higher levels of JNK1 p54 and JNK2 p54 and significantly lower levels of p-Bcl-2 in relapse patients and in GA non-responders. By using receiver operating characteristic analysis, we found that the probability of accurately detecting relapse and response to GA was: 92% and 75.5%, respectively, for JNK1 p54 and 86% and 94.6%, respectively, for p-Bcl-2. Our data suggest that JNK1 and p-Bcl-2 could serve as potential biomarkers for MS relapse and the therapeutic response to GA.

Exploring the Conformational Space of Bcl-2 Protein Variants: Dynamic Contributions of the Flexible Loop Domain and Transmembrane Region

Members of the Bcl-2 protein family regulate apoptosis through interactions with several proteins. A critical intrinsically disordered region (IDR) present in some members of the Bcl-2 family is essential for their function. Also, the structural and conformational plasticity of disordered regions is essential for the regulation of the Bcl-2 protein’s activity. Further, some proteins of the family contain transmembrane-helical regions, which anchor them into organelle membranes. Bcl-2, the archetypical member of the family, is characterized by an IDR labeled as a flexible loop domain (FLD) and a transmembrane domain (TMD). Another member of this family is the Bcl-2A1 protein, containing a TMD but lacking the FLD. To our knowledge, this is the first report which characterizes the individual and simultaneous dynamical contributions of FLD and TMD in Bcl-2 and Bcl-2A1 using molecular dynamics simulations (MDS). We examined the conformational spaces of Bcl-2, Bcl-2A1, and two artificial constructs lacking the TMD (Bcl-2ΔTM and Bcl-2A1ΔTM). As the results show, FLD and TMD stabilized each protein independently when they are present. When they coincided, such as in Bcl-2, an additive stabilizing effect is observed. This information is crucial for understanding the structural mechanisms of interaction in the Bcl-2 family.

Molecular and expression characteristics of resistin (RETN) and its effects on the differentiation of intramuscular preadipocyte in goat

Resistin (RETN) is a hormone secreted by adipocytes, which plays an important role in glucose and lipid metabolism. The aim of this study is to clone and obtain the full length open reading frame (ORF) of goat RETN gene sequence, and to reveal its molecular and expression characteristics. Simultaneously, we explore its effect on the differentiation of intramuscular preadipocytes in goat. The full length ORF sequence of goat RETN gene was cloned by RT-PCR technique, and bioinformatics analysis was performed though relevant biological softwares. In this study, the expression of RETN mRNA in goat tissues and intramuscular preadipocytes during differentiation was detected by qPCR technique. Furthermore, RNA interference was used to explore the effects of RETN on intramuscular preadipocytes differentiation in goat. The results showed that the cloned goat RETN gene sequence was 428 bp in length, of which the ORF was 330 bp, encoding 109 amino acids. Sequence analysis revealed that it had 12 phosphorylation sites and an O-glycosylation site, and its protein contained a signal peptide sequence. Also, the RETN gene is expressed in goat various analyzed tissues, and the results showed that the expression of RETN gene in lung tissue was higher than that in other analyzed tissues of goat (p < .01). Moreover, the expression level of RETN gene in the goat's intramuscular preadipocytes decreased first and then increased, and reached the highest on the fifth day, which was significantly higher than that of undifferentiated intramuscular preadipocytes (p < .001). After transfecting intramuscular preadipocyte with siRNA, we found that the mRNA level of RETN was significantly down-regulated by 70% and 87% (p < .01). Oil red O staining results showed that the interference of RETN gene can promote the differentiation of intramuscular preadipocytes. After knockdown of RETN with siRNA, the PPARγ, AP2, C/EBPα, C/EBPβ and SREBP1 genes were significantly up-regulated (p < .01). Thus, it can be inferred that RETN inhibits the differentiation of goat intramuscular preadipocytes, probably through regulating the expression of C/EBPα, C/EBPβ, PPARγ, AP2 and SREBP-1 genes.

Cancer Metabolism and the Evasion of Apoptotic Cell Death

Cellular growth and proliferation depend upon the acquisition and synthesis of specific metabolites. These metabolites fuel the bioenergy, biosynthesis, and redox potential required for duplication of cellular biomass. Multicellular organisms maintain tissue homeostasis by balancing signals promoting proliferation and removal of cells via apoptosis. While apoptosis is in itself an energy dependent process activated by intrinsic and extrinsic signals, whether specific nutrient acquisition (elevated or suppressed) and their metabolism regulates apoptosis is less well investigated. Normal cellular metabolism is regulated by lineage specific intrinsic features and microenvironment driven extrinsic features. In the context of cancer, genetic abnormalities, unconventional microenvironments and/or therapy engage constitutive pro-survival signaling to re-program and rewire metabolism to maintain survival, growth, and proliferation. It thus becomes particularly relevant to understand whether altered nutrient acquisition and metabolism in cancer can also contribute to the evasion of apoptosis and consequently therapy resistance. Our review attempts to dissect a causal relationship between two cancer hallmarks, i.e., deregulated cellular energetics and the evasion of programmed cell death with primary focus on the intrinsic pathway of apoptosis.

Chloroquine sensitizes MDA-MB-231 cells to osimertinib through autophagy-apoptosis crosstalk pathway

Background: Triple-negative breast cancer (TNBC) is a breast cancer that tests negative for estrogen receptor (ER), progesterone receptors, and human epidermal growth factor receptors 2 (HER2). It is aggressive and invasive in nature and lacks targeted therapy. Purpose: The EGFR is frequently overexpressed in TNBC, and the EGFR-overexpressing TNBC presumably escapes EGFR inhibitor therapy by upregulating autophagy and inhibiting apoptosis. Methods: To parse the autophagy-apoptosis crosstalk pathway as a potential targeted therapy in TNBC, the activity of an EGFR inhibitor, osimertinib, alone and in combination with an autophagy inhibitor, chloroquine, was examined in EGFR-overexpressing TNBC cell line, MDA-MB-231. The nature of interaction between both drugs at various concentrations was determined by calculating combination indexes (CI) using CompuSyn software. Temporal changes in the expression of the autophagy marker, LC3B-II, and several apoptosis signaling molecules were measured using Western blot and luminex assay with MAGPIX® after exposure to drugs. A synergistic interaction (CI <1) was identified with combinations of 4-6.5 μM osimertinib with 30-75 μM chloroquine. Results: A combination of osimertinib (6 μM) with chloroquine (30 μM) resulted in a 6-fold increase of LC3B-II relative to control compared to 2.5-fold increase for either drug alone. The caspase-3 expression increased 2-fold compared to a 0.5-fold decrease with chloroquine and 1.5-fold increase with osimertinib. Conclusion: Our results indicate that inhibition of the autophagic flux via chloroquine improves the effectiveness of osimertinib in TNBC cancer cells, warranting further investigations of this combination in vivo.

Human SP-D Acts as an Innate Immune Surveillance Molecule Against Androgen-Responsive and Androgen-Resistant Prostate Cancer Cells

Surfactant Protein D (SP-D), a pattern recognition innate immune molecule, has been implicated in the immune surveillance against cancer. A recent report showed an association of decreased SP-D expression in human prostate adenocarcinoma with an increased Gleason score and severity. In the present study, the SP-D expression was evaluated in primary prostate epithelial cells (PrEC) and prostate cancer cell lines. LNCaP, an androgen dependent prostate cancer cell line, exhibited significantly lower mRNA and protein levels of SP-D than PrEC and the androgen independent cell lines (PC3 and DU145). A recombinant fragment of human SP-D, rfhSP-D, showed a dose and time dependent binding to prostate cancer cells via its carbohydrate recognition domain. This study, for the first time, provides evidence of significant and specific cell death of tumor cells in rfhSP-D treated explants as well as primary tumor cells isolated from tissue biopsies of metatstatic prostate cancer patients. Viability of PrEC was not altered by rfhSP-D. Treated LNCaP (p53+/+) and PC3 (p53 -/-) cells exhibited reduced cell viability in a dose and time dependent manner and were arrested in G2/M and G1/G0 phase of the cell cycle, respectively. rfhSP-D treated LNCaP cells showed a significant upregulation of p53 whereas a significant downregulation of pAkt was observed in both PC3 and LNCaP cell lines. The rfhSP-D-induced apoptosis signaling cascade involved upregulation of Bax:Bcl2 ratio, cytochrome c and cleaved products of caspase 7. The study concludes that rfhSP-D induces apoptosis in prostate tumor explants as well as in androgen dependent and independent prostate cancer cells via p53 and pAkt pathways.

Stressing the Role of DNA as a Drug Carrier: Synthesis of DNA-Drug Conjugates through Grafting Chemotherapeutics onto Phosphorothioate Oligonucleotides

To stress the role of deoxyribonucleic acid (DNA) as a drug carrier, an efficient conjugation strategy in which chemotherapeutics can be grafted onto a phosphorothiolated DNA backbone through the reaction between the phosphorothioate group (PS) and a benzyl bromide group is proposed. As a proof of concept, benzyl-bromide-modified paclitaxel (PTX) is employed to graft onto the DNA backbone at the PS modification sites. Due to the easy preparation of phosphorothiolated DNA at any desired position during its solid-phase synthesis, diblock DNA strands containing both normal phosphodiester segment (^PO DNA) and phosphorothiolate segment (^PS DNA) are directly grafted with a multitude of PTXs without using complicated and exogenous linkers. Then, the resulting amphiphilic ^PO DNA-blocked-(^PS DNA-grafted PTX) conjugates (^PO DNA-b-(^PS DNA-g-PTX)) assemble into PTX-loaded spherical nucleic acid (SNA)-like micellar nanoparticles (PTX-SNAs) with a high drug loading ratio up to ≈53%. Importantly, the ^PO DNA segment maintains its molecular recognition property and biological functions, which allows the as-prepared PTX-SNAs to be further functionalized with tumor-targeting aptamers, fluorescent probe strands, or antisense sequences. These multifunctional PTX-SNAs demonstrate active tumor-targeting delivery, efficient inhibition of tumor growth, and the reversal of drug resistance both in vitro and in vivo for comprehensive antitumor therapy.

Shedding Light on the Interaction of Human Anti-Apoptotic Bcl-2 Protein with Ligands through Biophysical and in Silico Studies

Bcl-2 protein is involved in cell apoptosis and is considered an interesting target for anti-cancer therapy. The present study aims to understand the stability and conformational changes of Bcl-2 upon interaction with the inhibitor venetoclax, and to explore other drug-target regions. We combined biophysical and in silico approaches to understand the mechanism of ligand binding to Bcl-2. Thermal shift assay (TSA) and urea electrophoresis showed a significant increase in protein stability upon venetoclax incubation, which is corroborated by molecular docking and molecular dynamics simulations. An 18 °C shift in Bcl-2 melting temperature was observed in the TSA, corresponding to a binding affinity multiple times higher than that of any other reported Bcl-2 inhibitor. This protein-ligand interaction does not implicate alternations in protein conformation, as suggested by SAXS. Additionally, bioinformatics approaches were used to identify deleterious non-synonymous single nucleotide polymorphisms (nsSNPs) of Bcl-2 and their impact on venetoclax binding, suggesting that venetoclax interaction is generally favored against these deleterious nsSNPs. Apart from the BH3 binding groove of Bcl-2, the flexible loop domain (FLD) also plays an important role in regulating the apoptotic process. High-throughput virtual screening (HTVS) identified 5 putative FLD inhibitors from the Zinc database, showing nanomolar affinity toward the FLD of Bcl-2.

Systems analysis of phosphorylation-regulated Bcl-2 interactions establishes a model to reconcile the controversy over the significance of Bcl-2 phosphorylation

BACKGROUND AND PURPOSE

The biological significance of the multi-site phosphorylation of Bcl-2 at its loop region (T69, S70 and S87) has remained controversial for decades. This is a major obstacle for understanding apoptosis and anti-tumour drug development.

EXPERIMENTAL APPROACH

We established a mathematical model into which a phosphorylation and de-phosphorylation process of Bcl-2 was integrated. Paclitaxel-treated breast cancer cells were used as experimental models. Changes in the kinetics of binding with its critical partners, induced by phosphorylation of Bcl-2 were experimentally obtained by surface plasmon resonance, using a phosphorylation-mimicking mutant EEE-Bcl-2 (T69E, S70E and S87E).

KEY RESULTS

Mathematical simulations combined with experimental validation showed that phosphorylation regulates Bcl-2 with different dynamics depending on the extent of Bcl-2 phosphorylation and the phosphorylated Bcl-2-induced changes in binding kinetics. In response to Bcl-2 homology 3 (BH3)-only protein Bmf stress, Bcl-2 phosphorylation switched from diminishing to enhancing the Bcl-2 anti-apoptotic ability with increased phosphorylation of Bcl-2, and the turning point was 50% Bcl-2 phosphorylation induced by 0.2 μM paclitaxel treatment. In contrast, Bcl-2 phosphorylation enhanced the anti-apoptotic ability of Bcl-2 towards other BH3-only proteins Bim, Bad and Puma, throughout the entire phosphorylation procedure.

CONCLUSIONS AND IMPLICATIONS

The model could accurately predict the effects of anti-tumour drugs that involve the Bcl-2 family pathway, as shown with ABT-199 or etoposide.

UNBS5162 inhibits colon cancer growth via suppression of PI3K/Akt signaling pathway

Colon cancer is a common cause of cancer-related death worldwide. However, the underlying mechanism of tumor progression of colon cancer remains far from being elucidated. In the present study, we report the role of UNBS5162 in colon cancer. UNBS5162 is a naphthalimide that can intercalate into DNA and suppress the expression level of CXCL chemokines. Here, we investigated its effect on cell proliferation, mobility and apoptosis in HCT116 cells, and explored the underlying mechanism. A CCK8 assay revealed that UNBS5162 can block the proliferation of colon cancer cells. Base on a Transwell assay, we showed that cell migration and invasion ability of HCT116 cells are inhibited by UNBS5162. In addition, Annexin V-FITC/PI assay and Western blot analysis were performed to detect whether UNBS5162 could induce cell apoptosis. The results indicated that UNBS5162 increases the number of apoptotic cells remarkably. Furthermore, Western blot analysis demonstrated that UNBS5162 down-regulates the expression level of Bcl2, and up-regulates that of Bax as well as the level of activated Caspase-3. Moreover, we examined the impact of UNBS5162 on PI3K/Akt signaling pathway. UNBS5162 substantially inhibited the phosphorylation of Akt and its downstream effector mTOR, and reduced the expression of p-70. Taken together, these results suggest that UNBS5162 should be considered as a potent therapeutic anticancer agent that targets the PI3K/AKT signaling pathway.

The rise of apoptosis: targeting apoptosis in hematologic malignancies

Dysregulation of the B-cell leukemia/lymphoma-2 (BCL-2) family of proteins of the intrinsic apoptotic pathway is fundamental to the pathophysiology of many hematologic malignancies. The BCL-2 family consists of regulatory proteins that either induce apoptosis (proapoptotic) or inhibit it (prosurvival). BCL-2, myeloid cell leukemia-1, and B-cell lymphoma–extra large are prosurvival proteins that are prime targets for anticancer therapy, and molecules targeting each are in various stages of preclinical and clinical development. The US Food and Drug Administration (FDA)-approved BCL-2 inhibitor venetoclax was first proven to be highly effective in chronic lymphocytic leukemia and some B-cell non-Hodgkin lymphoma subtypes. Subsequently, venetoclax was found to be active clinically against a diverse array of hematologic malignancies including multiple myeloma, acute myeloid leukemia, myelodysplastic syndrome, acute lymphoblastic leukemia, and others. Here, we give a brief introduction to BCL-2 family biology and the mechanism of action of BCL-2 Homology 3 (BH3) mimetics, and provide an overview of the clinical data for therapeutically targeting prosurvival proteins in hematologic malignancies, with a focus on BCL-2 inhibition. To prioritize novel agent combinations and predict responders, we discuss the utility of functional assays such as BH3 profiling. Finally, we provide a perspective on how therapies targeting BCL-2 family proteins may be optimally implemented into future therapeutic regimens for hematologic malignancies.

STAT3 inhibition induces Bax-dependent apoptosis in liver tumor myeloid-derived suppressor cells

Immunosuppressive myeloid-derived suppressor cells (MDSC) subvert antitumor immunity and limit the efficacy of chimeric antigen receptor T cells (CAR-T). Previously, we reported that the GM-CSF/JAK2/STAT3 axis drives liver-associated MDSC (L-MDSC) proliferation and blockade of this axis rescued antitumor immunity. We extended these findings in our murine liver metastasis (LM) model, by treating tumor-bearing mice with STAT3 inhibitors (STATTIC or BBI608) to further our understanding of how STAT3 drives L-MDSC suppressive function. STAT3 inhibition caused significant reduction of tumor burden as well as L-MDSC frequencies due to decrease in pSTAT3 levels. L-MDSC isolated from STATTIC or BBI608-treated mice had significantly reduced suppressive function. STAT3 inhibition of L-MDSC was associated with enhanced antitumor activity of CAR-T. Further investigation demonstrated activation of apoptotic signaling pathways in L-MDSC following STAT3 inhibition as evidenced by an upregulation of the pro-apoptotic proteins Bax, cleaved caspase-3, and downregulation of the anti-apoptotic protein Bcl-2. Accordingly, there was also a decrease of pro-survival markers, pErk and pAkt, and an increase in pro-death marker, Fas, with activation of downstream JNK and p38 MAPK. These findings represent a previously unrecognized link between STAT3 inhibition and Fas-induced apoptosis of MDSCs. Our findings suggest that inhibiting STAT3 has potential clinical application for enhancing the efficacy of CAR-T cells in LM through modulation of L-MDSC.

Cytotoxic Constituents from the Sclerotia of Poria cocos against Human Lung Adenocarcinoma Cells by Inducing Mitochondrial Apoptosis

Previous studies have revealed the antitumor potential of Poria cocos Wolf against a broad spectrum of cancers. However, the biological activity of P. cocos against lung cancer, which is known as the leading cause of cancer mortality worldwide, and its underlying chemical and molecular basis, remain to be investigated. We aimed to evaluate the in vitro cytotoxicity of P. cocos toward human lung adenocarcinoma cells with different p53 statuses, to identify the bioactive constituents of P. cocos, and explicate the molecular mechanisms underlying the cytotoxicity of these constituents in human lung adenocarcinoma cells. An EtOH extract of the sclerotia of P. cocos exhibited cytotoxicity toward four human lung cancer cell lines: A549, H1264, H1299, and Calu-6, regardless of their p53 status. Chemical investigation of the extract resulted in the isolation of two triterpenoids, dehydroeburicoic acid monoacetate (1) and acetyl eburicoic acid (4); a sterol, 9,11-dehydroergosterol peroxide (2); and a diterpenoid, dehydroabietic acid (3). All of the isolated compounds were cytotoxic to the lung adenocarcinoma cell lines, exhibiting IC₅₀ values ranging from 63.6 μM to 171.0 μM at 48 h of treatment. The cytotoxicity of the extract and the isolated compounds were found to be mediated by apoptosis, and accompanied by elevated Bax expression and/or Bcl-2 phosphorylation along with caspase-3 activation. Our data demonstrate that the sclerotium of P. cocos and its four bioactive constituents (1⁻4) exert cytotoxicity against human lung adenocarcinoma cells, regardless of their p53 status, by inducing apoptosis associated with mitochondrial perturbation, and proposing the potential to employ P. cocos in the treatment of lung cancer.

MDA-9/Syntenin regulates protective autophagy in anoikis-resistant glioma stem cells

Glioma stem cells (GSCs) comprise a small subpopulation of glioblastoma multiforme cells that contribute to therapy resistance, poor prognosis, and tumor recurrence. Protective autophagy promotes resistance of GSCs to anoikis, a form of programmed cell death occurring when anchorage-dependent cells detach from the extracellular matrix. In nonadherent conditions, GSCs display protective autophagy and anoikis-resistance, which correlates with expression of melanoma differentiation associated gene-9/Syntenin (MDA-9) (syndecan binding protein; SDCBP). When MDA-9 is suppressed, GSCs undergo autophagic death supporting the hypothesis that MDA-9 regulates protective autophagy in GSCs under anoikis conditions. MDA-9 maintains protective autophagy through phosphorylation of BCL2 and by suppressing high levels of autophagy through EGFR signaling. MDA-9 promotes these changes by modifying FAK and PKC signaling. Gain-of-function and loss-of-function genetic approaches demonstrate that MDA-9 regulates pEGFR and pBCL2 expression through FAK and pPKC. EGFR signaling inhibits autophagy markers (ATG5, Lamp1, LC3B), helping to maintain protective autophagy, and along with pBCL2 maintain survival of GSCs. In the absence of MDA-9, this protective mechanism is deregulated; EGFR no longer maintains protective autophagy, leading to highly elevated and sustained levels of autophagy and consequently decreased cell survival. In addition, pBCL2 is down-regulated in the absence of MDA-9, leading to cell death in GSCs under conditions of anoikis. Our studies confirm a functional link between MDA-9 expression and protective autophagy in GSCs and show that inhibition of MDA-9 reverses protective autophagy and induces anoikis and cell death in GSCs.

Selective inhibition of BCL-2 is a promising target in patients with high-risk myelodysplastic syndromes and adverse mutational profile

Somatic mutations in genes such as ASXL1, RUNX1, TP53 or EZH2 adversely affect the outcome of patients with myelodysplastic syndromes (MDS). Since selective BCL-2 inhibition is a promising treatment strategy in hematologic malignancies, we tested the therapeutic impact of ABT-199 on MDS patient samples bearing an adverse mutational profile. By gene expression, we found that the level of pro-apoptotic BIM significantly decreased during MDS disease progression in line with an acquired resistance to cell death. Supporting the potential for ABT-199 treatment in MDS, high-risk MDS patient samples specifically underwent cell death in response to ABT-199 even when harbouring mutations in ASXL1, RUNX1, TP53 or EZH2. ABT-199 effectively targeted the stem- and progenitor compartment in advanced MDS harbouring mutations in ASXL1, RUNX1, TP53 or EZH2 and even proved effective in patients harbouring more than one of the defined high-risk mutations. Moreover, we utilized the protein abundance of BCL-2 family members in primary patient samples using flow cytometry as a biomarker to predict ABT-199 treatment response. Our data demonstrate that ABT-199 effectively induces apoptosis in progenitors of high-risk MDS/sAML despite the presence of adverse genetic mutations supporting the notion that pro-apoptotic intervention will hold broad therapeutic potential in high-risk MDS patients with poor prognosis.

An oral quinoline derivative, MPT0B392, causes leukemic cells mitotic arrest and overcomes drug resistant cancer cells

Despite great advances in the treatment of acute leukemia, a renaissance of current chemotherapy needs to be improved. The present study elucidates the underlying mechanism of a new synthetic quinoline derivative, MPT0B392 (B392) against acute leukemia and its potential anticancer effect in drug resistant cells. B392 caused mitotic arrest and ultimately led to apoptosis. It was further demonstrated to be a novel microtubule-depolymerizing agent. The effects of oral administration of B392 showed relative potent anti-leukemia activity in an in vivo xenograft model. Further investigation revealed that B392 triggered induction of the mitotic arrest, followed by mitochondrial membrane potential loss and caspases cleavage by activation of c-Jun N-terminal kinase (JNK). In addition, B392 enhanced the cytotoxicity of sirolimus in sirolimus-resistant acute leukemic cells through inhibition of Akt/mTOR pathway and Mcl-1 protein expression, and also was active in the p-glycoprotein (p-gp)-overexpressing National Cancer Institute/Adriamycin-Resistant cells with little susceptibility to p-gp. Taken together, B392 has potential as an oral mitotic drug and adjunct treatment for drug resistant cancer cells.

Novel angiotensin receptor blocker, azilsartan induces oxidative stress and NFkB-mediated apoptosis in hepatocellular carcinoma cell line HepG2

Overexpression of renin angiotensin system (RAS) components and nuclear factor-kappa B (NF-kB) has a key role in various cancers. Blockade of RAS and NF-kB pathway has been suggested to reduce cancer cell proliferation. This study aimed to investigate the role of angiotensin II and NF-kB pathway in liver hepatocellular carcinoma cell line (HepG2) proliferation by using azilsartan (as a novel Ag II antagonist) and Bay 11-7082 (as NF-kB inhibitor). HepG2 cells were treated with different concentrations of azilsartan and Bay 11-7082. Cytotoxicity was determined after 24, 48, and 72?h by MTT assay. Reactive oxygen spices (ROS) generation and cytochrome c release were measured following azilsartan and Bay11- 7082 treatment. Apoptosis was analyzed qualitatively by DAPI staining and quantitatively through flow cytometry methodologies and Bax and Bcl-2 mRNA and protein levels were assessed by real time PCR and ELISA methods, respectively. The cytotoxic effects of different concentration of azilsartan and Bay11- 7082 on HepG2 cells were observed as a reduction in cell viability, increased ROS formation, cytochrome c release and apoptosis induction. These effects were found to correlate with a shift in Bax level and a downward trend in the expression of Bcl-2. These findings suggest that azilsartan and Bay11- 7082 in combination or alone have strong potential as an agent for prevention or treatment of liver cancer after further studies.

Systems pharmacological analysis of mitochondrial cardiotoxicity induced by selected tyrosine kinase inhibitors

Tyrosine kinase inhibitors (TKIs) are targeted therapies rapidly becoming favored over conventional cytotoxic chemotherapeutics. Our study investigates two FDA approved TKIs, DASATINIB; indicated for IMATINIB-refractory chronic myeloid leukemia, and SORAFENIB; indicated for hepatocellular carcinoma and advanced renal cell carcinoma. Limited but crucial evidence suggests that these agents can have cardiotoxic side effects ranging from hypertension to heart failure. A greater understanding of the underlying mechanisms of this cardiotoxicity are needed as concerns grow and the capacity to anticipate them is lacking. The objective of this study was to explore the mitochondrial-mediated cardiotoxic mechanisms of the two selected TKIs. This was achieved experimentally using immortalized human cardiomyocytes, AC16 cells, to investigate dose- and time-dependent cell killing, along with measurements of temporal changes in key signaling proteins involved in the intrinsic apoptotic and autophagy pathways upon exposure to these agents. Quantitative systems pharmacology (QSP) models were developed to capture the toxicological response in AC16 cells using protein dynamic data. The developed QSP models captured well all the various trends in protein signaling and cellular responses with good precision on the parameter estimates, and were successfully qualified using external data sets. An interplay between the apoptotic and autophagic pathways was identified to play a major role in determining toxicity associated with the investigated TKIs. The established modeling platform showed utility in elucidating the mechanisms of cardiotoxicity of SORAFENIB and DASATINIB. It may be useful for other small molecule targeted therapies demonstrating cardiac toxicities, and may aid in informing alternate dosing strategies to alleviate cardiotoxicity associated with these therapies.

PP2A as the Main Node of Therapeutic Strategies and Resistance Reversal in Triple-Negative Breast Cancer

Triple negative breast cancer (TNBC), is defined as a type of tumor lacking the expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). The ER, PR and HER2 are usually the molecular therapeutic targets for breast cancers, but they are ineffective for TNBC because of their negative expressions, so chemotherapy is currently the main treatment strategy in TNBC. However, drug resistance remains a major impediment to TNBC chemotherapeutic treatment. Recently, the protein phosphatase 2A (PP2A) has been found to regulate the phosphorylation of some substrates involved in the relevant target of TNBC, such as cell cycle control, DNA damage responses, epidermal growth factor receptor, immune modulation and cell death resistance, which may be the effective therapeutic strategies or influence drug sensitivity to TNBCs. Furthermore, PP2A has also been found that could induce ER re-expression in ER-negative breast cancer cells, and which suggests PP2A could promote the sensitivity of tamoxifen to TNBCs as a resistance reversal agent. In this review, we will summarize the potential therapeutic value of PP2A as the main node in developing targeting agents, disrupting resistance or restoring drug sensitivity in TNBC.

Under ambient UVA exposure, pefloxacin exhibits both immunomodulatory and genotoxic effects via multiple mechanisms

Pefloxacin (PFLX) is an antibiotic, which shows broad spectrum antimicrobial activities. It is an important derivative of fluoroquinolones (FLQs) group. Ultraviolet radiation (200-400nm) causes major problem for living being which comes at the earth surface naturally through sunlight and increasing regularly due to ozone depletion. PFLX was photodegraded in 5h and forms photoproduct under UVA exposure. At the non photocytotoxic dose PFLX, shows reduced phagocytosis activity, NO (nitric oxide) production, large vacuole formation and down regulated IL-6, TNF-α and IL-1 in BALB/c macrophages at both genes and proteins levels. At higher doses (photocytotoxic doses), PFLX induced a concentration dependent decrease in cell viability of human keratinocyte cell line (HaCaT) and peritoneal macrophages of BALB/c mice. Our molecular docking suggests that PFLX binds only to the cleaved DNA in the DNA-human TOP2A complex. Topoisomerase assay confirmed that PFLX inhibits human topoisomerase by forming an adduct with DNA. Photosensitized PFLX also caused intracellular ROS mediated DNA damage and formation of micronuclei and cyclobutane pyrimidine dimers (CPDs). Increase intracellular ROS leads to apoptosis which was proved through lysosomal destabilization and reduced mitochondrial membrane potential (MMP). Our present study shows that ambient UVA exposure in the presence of PFLX caused immunomodulatory as well as photogenotoxic effects. Therefore, patients under PFLX drug treatment should avoid sunlight exposure, especially during peak hours for their photosafety.

BCL2-BH4 antagonist BDA-366 suppresses human myeloma growth

Multiple myeloma (MM) is a heterogeneous plasma cell malignancy and remains incurable. B-cell lymphoma-2 (BCL2) protein correlates with the survival and the drug resistance of myeloma cells. BH3 mimetics have been developed to disrupt the binding between BCL2 and its pro-apoptotic BCL2 family partners for the treatment of MM, but with limited therapeutic efficacy. We recently identified a small molecule BDA-366 as a BCL2 BH4 domain antagonist, converting it from an anti-apoptotic into a pro-apoptotic molecule. In this study, we demonstrated that BDA-366 induces robust apoptosis in MM cell lines and primary MM cells by inducing BCL2 conformational change. Delivery of BDA-366 substantially suppressed the growth of human MM xenografts in NOD-scid/IL2Rγnull mice, without significant cytotoxic effects on normal hematopoietic cells or body weight. Thus, BDA-366 functions as a novel BH4-based BCL2 inhibitor and offers an entirely new tool for MM therapy.

A2B adenosine receptor agonist induces cell cycle arrest and apoptosis in breast cancer stem cells via ERK1/2 phosphorylation

PURPOSE

It has been reported that cancer stem cells (CSCs) may play a crucial role in the development, recurrence and metastasis of breast cancer. Targeting signaling pathways in CSCs is considered to be a promising strategy for the treatment of cancer. Here, we investigated the role of the A2B adenosine receptor (A2BAR) and its associated signaling pathways in governing the proliferation and viability of breast cancer cell line derived CSCs.

METHODS

CSCs were isolated from the breast cancer cell lines MCF-7 and MDA-MB-231 using a mammosphere assay. The effect of the A2BAR agonist BAY606583 on cell proliferation was evaluated using XTT and mammosphere formation assays, respectively. Apoptosis was assessed using Annexin-V staining and cell cycle analyses were performed using flow cytometry. The expression levels of Bax, Bcl-2, cyclin-D1, CDK-4 and (phosphorylated) ERK1/2 were assessed using Western blotting.

RESULTS

Our data revealed that the breast cancer cell line derived mammospheres were enriched for CSCs. We also found that A2BAR stimulation with its agonist BAY606583 inhibited mammosphere formation and CSC viability. In addition, we found that the application of BAY606583 led to CSC cell cycle arrest and apoptosis through the cyclin-D1/Cdk-4 and Bax/Bcl-2 pathways, respectively. Notably, we found that BAY606583 significantly down-regulated ERK1/2 phosphorylation in the breast cancer cell line derived CSCs.

CONCLUSIONS

From our results we conclude that A2BAR induces breast CSC cell cycle arrest and apoptosis through downregulation of the ERK1/2 cascade. As such, A2BAR may be considered as a novel target for the treatment of breast cancer.

Drug-resistance in doxorubicin-resistant FL5.12 hematopoietic cells: elevated MDR1, drug efflux and side-population positive and decreased BCL2-family member expression

Chemotherapeutic drug treatment can result in the emergence of drug-resistant cells. By culturing an interleukin-3 (IL-3)-dependent cell line, FL5.12 cells in the presence of the chemotherapeutic drug doxorubicin, we isolated FL/Doxo cells which are multi-drug resistant. Increased levels of drug efflux were detected in FL/Doxo cells which could be inhibited by the MDR1 inhibitor verapamil but not by the MRP1 inhibitor MK571. The effects of TP53 and MEK1 were examined by infection of FL/Doxo cells with retroviruses encoding either a dominant negative TP-53 gene (FL/Doxo+ TP53 (DN) or a constitutively-activated MEK-1 gene (FL/Doxo + MEK1 (CA). Elevated MDR1 but not MRP1 mRNA transcripts were detected by quantitative RT-PCR in the drug-resistant cells while transcripts encoding anti-apoptotic genes such as: BCL2, BCLXL and MCL1 were observed at higher levels in the drug-sensitive FL5.12 cells. The percentage of cells that were side-population positive was increased in the drug-resistant cells compared to the parental line. Drug-resistance and side-positive population cells have been associated with cancer stem cells (CSC). Our studies suggest mechanisms which could allow the targeting of these molecules to prevent drug-resistance.

The tumor suppressor phosphatase PP2A-B56α regulates stemness and promotes the initiation of malignancies in a novel murine model

Protein phosphatase 2A (PP2A) is a ubiquitously expressed Serine-Threonine phosphatase mediating 30–50% of protein phosphatase activity. PP2A functions as a heterotrimeric complex, with the B subunits directing target specificity to regulate the activity of many key pathways that control cellular phenotypes. PP2A-B56α has been shown to play a tumor suppressor role and to negatively control c-MYC stability and activity. Loss of B56α promotes cellular transformation, likely at least in part through its regulation of c-MYC. Here we report generation of a B56α hypomorph mouse with very low B56α expression that we used to study the physiologic activity of the PP2A-B56α phosphatase. The predominant phenotype we observed in mice with B56α deficiency in the whole body was spontaneous skin lesion formation with hyperproliferation of the epidermis, hair follicles and sebaceous glands. Increased levels of c-MYC phosphorylation on Serine62 and c-MYC activity were observed in the skin lesions of the B56α^hm/hm mice. B56α deficiency was found to increase the number of skin stem cells, and consistent with this, papilloma initiation was accelerated in a carcinogenesis model. Further analysis of additional tissues revealed increased inflammation in spleen, liver, lung, and intestinal lymph nodes as well as in the skin lesions, resembling elevated extramedullary hematopoiesis phenotypes in the B56α^hm/hm mice. We also observed an increase in the clonogenicity of bone marrow stem cells in B56α^hm/hm mice. Overall, this model suggests that B56α is important for stem cells to maintain homeostasis and that B56α loss leading to increased activity of important oncogenes, including c-MYC, can result in aberrant cell growth and increased stem cells that can contribute to the initiation of malignancy.

Endoplasmic reticulum stress-mediated autophagy activation attenuates fumonisin B1 induced hepatotoxicity in vitro and in vivo

Although pathological characteristics of fumonisin B1 are known to induce hepatic injury over prolonged periods, the cellular defense mechanisms against the detrimental effects of FB1 are still unknown. The underlying mechanisms of FB1 toxicity are thought to be related with the inhibition of ceramide synthase, causing an accumulation of sphingoid bases, which in turn cause development of oxidative stress. Herein, we investigated whether autophagy, a cellular defense mechanism, protects liver cells from FB1 exposure. To accomplish this, we utilized HepG2 cells and a mouse model to study the effects of FB1 in the autophagy pathway. FB1 was capable of inducing autophagy via the generation of ROS, induction of endoplasmic reticulum stress, phosphorylation of JNK, suppression of mTOR and activation of LC3I/II in HepG2 cells and mice livers. Treatment of HepG2 cells with the ROS scavenger N-acetyl-l-cysteine alleviated ER stress stimulation and induced HepG2 cell death. Moreover, suppression of autophagy with 3-Methyladenine enhanced HepG2 cells apoptosis. Concurrently, four consecutive days exposure of mice livers to FB1 altered the levels of sphingoid bases, hepatic enzymes and induced histopathological changes. Moreover, the expression levels of major ER stress and autophagy-related markers such as PERK, IRE1-α, and LC3I/II also increased. Autophagy activation protected HepG2 cells and mice livers from the lethal effects of FB1. Hence, these findings specify that, the compounds that modify autophagy might be useful therapeutic agents for treatment of patients with FB1 induced liver ailments.

HSP90 inhibitor (NVP-AUY922) enhances the anti-cancer effect of BCL-2 inhibitor (ABT-737) in small cell lung cancer expressing BCL-2

Small cell lung cancer (SCLC) cannot be efficiently controlled using existing chemotherapy and radiotherapy approaches, indicating the need for new therapeutic strategies. Although ABT-737, a B-cell lymphoma-2 (BCL-2) inhibitor, exerts anticancer effects against BCL-2-expressing SCLC, monotherapy with ABT-737 is associated with limited clinical activity because of the development of resistance and toxicity. Here, we examined whether combination therapy with ABT-737 and heat shock protein 90 (HSP90) inhibitor NVP-AUY922 exerted synergistic anticancer effects on SCLC. We found that the combination of ABT-737 and NVP-AUY922 synergistically induced the apoptosis of BCL-2-expressing SCLC cells. NVP-AUY922 downregulated the expression of AKT and ERK, which activate MCL-1 to induce resistance against ABT-737. The synergistic effect was also partly due to blocking NF-κB activation, which induces anti-apoptosis protein expressions. However, interestingly, targeting BCL-2 and MCL-1 or BCL2 and NF-κB did not induce the cytotoxicity. In conclusion, our study showed that combination of BCL2 inhibitor with HSP90 inhibitor increased activity in in vitro and in vivo study in only BCL-2 expressing SCLC compared to either single BCL2 inhibitor or HSP inhibitor. The enhanced activity might be led by blocking several apoptotic pathways simultaneously rather than a specific pathway.

The E2F activators control multiple mitotic regulators and maintain genomic integrity through Sgo1 and BubR1

The E2F1, E2F2, and E2F3a transcriptional activators control proliferation. However, how the E2F activators regulate mitosis to maintain genomic integrity is unclear. Centrosome amplification (CA) and unregulated spindle assembly checkpoint (SAC) are major generators of aneuploidy and chromosome instability (CIN) in cancer. Previously, we showed that overexpression of single E2F activators induced CA and CIN in mammary epithelial cells, and here we show that combined overexpression of E2F activators did not enhance CA. Instead, the E2F activators elevated expression of multiple mitotic regulators, including Sgo1, Nek2, Hec1, BubR1, and Mps1/TTK. cBioPortal analyses of the TCGA database showed that E2F overexpression in lobular invasive breast tumors correlates with overexpression of multiple regulators of chromosome segregation, centrosome homeostasis, and the SAC. Kaplan-Meier plots identified correlations between individual or combined overexpression of E2F1, E2F3a, Mps1/TTK, Nek2, BubR1, or Hec1 and poor overall and relapse-free survival of breast cancer patients. In MCF10A normal mammary epithelial cells co-overexpressing E2Fs, transient Sgo1 knockdown induced CA, high percentages of premature sister chromatid separation, chromosome losses, increased apoptosis, and decreased cell clonogenicity. BubR1 silencing resulted in chromosome losses without CA, demonstrating that Sgo1 and BubR1 maintain genomic integrity through two distinct mechanisms. Our results suggest that deregulated activation of the E2Fs in mammary epithelial cells is counteracted by activation of a Sgo1-dependent mitotic checkpoint.

Targeting the Akt, GSK-3, Bcl-2 axis in acute myeloid leukemia

Over the last few decades, there has been significant progress in the understanding of the pathogenetic mechanisms of the Acute Myeloid Leukemia (AML). However, despite important advances in elucidating molecular mechanisms, the treatment of AML has not improved significantly, remaining anchored at the standard chemotherapy regimen "3 + 7", with the prognosis of patients remaining severe, especially for the elderly and for those not eligible for transplant procedures. The biological and clinical heterogeneity of AML represents the major obstacle that hinders the improvement of prognosis and the identification of new effective therapeutic approaches. To date, abundant information has been collected on the genetic and molecular alterations of AML carrying prognostic significance. However, not enough is known on how AML progenitors regulate proliferation and survival by redundant and cross-talking signal transduction pathways (STP). Furthermore, it remains unclear how such complicated network affects prognosis and therapeutic treatment options, although many of these molecular determinants are potentially attractive for their druggable characteristics. In this review, some of the key STP frequently deregulated in AML, such as PI3k/Akt/mTOR pathway, GSK3 and components of Bcl-2 family of proteins, are summarized, highlighting in addition their interplay. Based on this information, we reviewed new targeted therapeutic approaches, focusing on the aberrant networks that sustain the AML blast proliferation, survival and drug resistance, aiming to improve disease treatment. Finally, we reported the approaches aimed at disrupting key signaling cross-talk overcoming resistances based on the combination of different targeting therapeutic strategies.

PP2A inhibition from LB100 therapy enhances daunorubicin cytotoxicity in secondary acute myeloid leukemia via miR-181b-1 upregulation

Patients with secondary acute myeloid leukemia (sAML) arising from myelodysplastic syndromes have a poor prognosis marked by an increased resistance to chemotherapy. An urgent need exists for adjuvant treatments that can enhance or replace current therapeutic options. Here we show the potential of LB100, a small-molecule protein phosphatase 2 A (PP2A) inhibitor, as a monotherapy and chemosensitizing agent for sAML using an in-vitro and in-vivo approach. We demonstrate that LB100 decreases cell viability through caspase activation and G2/M cell-cycle arrest. LB100 enhances daunorubicin (DNR) cytotoxicity resulting in decreased xenograft volumes and improved overall survival. LB100 profoundly upregulates miR-181b-1, which we show directly binds to the 3′ untranslated region of Bcl-2 mRNA leading to its translational inhibition. MiR-181b-1 ectopic overexpression further diminishes Bcl-2 expression leading to suppression of sAML cell growth, and enhancement of DNR cytotoxicity. Our research highlights the therapeutic potential of LB100, and provides new insights into the mechanism of LB100 chemosensitization.

Fas Receptor Activation by Endogenous Opioids Is A New Mechanism for Cardiomyopathy in Cirrhotic Rats

BACKGROUND

Cirrhosis, a common consequence of chronic liver inflammation is associated with various cardiovascular dysfunctions which are called cirrhotic cardiomyopathy (CC). Among the various possible causes of CC, apoptosis is considered to have a pivotal role.

OBJECTIVES

To explore the contribution of endogenous opioids in the apoptosis process in a rat model of CC.

MATERIAL AND METHODS

Four genes were selected to cover both intrinsic and extrinsic pathways of apoptosis. Cardiac samples from 4 groups of rats were evaluated. Two groups were cirrhotic through bile duct ligation (BDL) receiving either naltrexone (BDL-naltrexone) or saline (BDL-saline), two others were normal rats as sham groups receiving either naltrexone (sham-naltrexone) or saline (sham-saline). Expression level of BCL2, Caspase3, Fas and FasL was explored in all groups using reverse transcriptase real-time PCR.

RESULTS

BDL-saline group showed significant over-expression of BCL2, caspase3 and Fas. BCL2 expression was 1.44 (P < 0.001) and caspasse3 was 1.35 (P < 0.001) times higher than sham-saline group, Fas was also overexpressed 1.3 (P < 0.001) times higher than BDL-naltrexone group and 1.91 (P < 0.001) compared to sham-naltrexone group. Caspase3 expression was 1.35 (P < 0.001) folds higher than sham-naltrexone group. The expression pattern of FasL revealed no statistically significant change among study groups.

CONCLUSION

Fas molecule enrollment during CC is a novel finding. Fas molecule is activated during cirrhosis through elevated levels of endogenous opioids. This pathway is one of the leading causes of CC. Our findings also demonstrated the protective role of naltrexone as opioids antagonist on cardiomyocytes in a rat model of CC.

Novel prosurvival function of Yip1A in human cervical cancer cells: constitutive activation of the IRE1 and PERK pathways of the unfolded protein response

Cancer cells are under chronic endoplasmic reticulum (ER) stress due to hypoxia, low levels of nutrients, and a high metabolic demand for proliferation. To survive, they constitutively activate the unfolded protein response (UPR). The inositol-requiring protein 1 (IRE1) and protein kinase RNA-like ER kinase (PERK) signaling branches of the UPR have been shown to have cytoprotective roles in cancer cells. UPR-induced autophagy is another prosurvival strategy of cancer cells, possibly to remove misfolded proteins and supply nutrients. However, the mechanisms by which cancer cells exploit the UPR and autophagy machinery to promote survival and the molecules that are essential for these processes remain to be elucidated. Recently, a multipass membrane protein, Yip1A, was shown to function in the activation of IRE1 and in UPR-induced autophagy. In the present study, we explored the possible role of Yip1A in activation of the UPR by cancer cells for their survival, and found that depletion of Yip1A by RNA interference (RNAi) induced apoptotic cell death in HeLa and CaSki cervical cancer cells. Intriguingly, Yip1A was found to activate the IRE1 and PERK pathways of the UPR constitutively in HeLa and CaSki cells. Yip1A mediated the phosphorylation of IRE1 and also engaged in the transcription of PERK. The activation of these signaling pathways upregulated the expression of anti-apoptotic proteins and autophagy-related proteins. These events might enhance resistance to apoptosis and promote cytoprotective autophagy in HeLa and CaSki cells. The present study is the first to uncover a key prosurvival modulator, Yip1A, which coordinates IRE1 signaling with PERK signaling to support the survival of HeLa and CaSki cervical cancer cells.