The essential role of evasion from cell death in cancer

Omega-3 fatty acids: molecular weapons against chemoresistance in breast cancer

Breast cancer is the most commonly diagnosed type of cancer and the leading cause of cancer-related death in women worldwide. Highly targeted therapies have been developed for different subtypes of breast cancer, including hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, triple-negative breast cancer (TNBC) and metastatic breast cancer disease are primarily treated with chemotherapy, which improves disease-free and overall survival, but does not offer a curative solution for these aggressive forms of breast cancer. Moreover, the development of chemoresistance is a major cause of therapeutic failure in this neoplasia, leading to disease relapse and patient death. In addition, chemotherapy's adverse side effects may substantially worsen health-related quality of life. Therefore, to improve the outcome of patients with breast cancer who are undergoing chemotherapy, several therapeutic options are under investigation, including the combination of chemotherapeutic drugs with natural compounds. Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs), including docosahexaenoic and eicosapentaenoic acids, have drawn attention for their antitumoral properties and their preventive activities against chemotherapy-induced toxicities in breast cancer. A literature review was conducted on PubMed using keywords related to breast cancer, omega-3, chemoresistance, and chemotherapy. This review aims to provide an overview of the molecular mechanisms driving breast cancer chemoresistance, focusing on the role of ω-3 PUFAs in these recognized cellular paths and presenting current findings on the effects of ω-3 PUFAs combined with chemotherapeutic drugs in breast cancer management.

Effects of the Supercritical Fluid Extract of Magnolia figo on Inducing the Apoptosis of Human Non-Small-Cell Lung Cancer Cells

Lung cancer has a high incidence rate worldwide, necessitating the development of new drugs. Although Magnolia figo (Lour.) DC. is known for its medicinal properties, studies on its efficacy against lung cancer are lacking. This study investigated whether the supercritical fluid extract of M. figo (FMO) can induce apoptosis in A549, a human non-small-cell lung cancer cell line. The cell viability was assessed using an MTT assay. A terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis and flow cytometry analysis were conducted. The expression of factors was assessed through Western blotting analyses. Gas chromatography-mass spectrometry (GC-MS) was performed. The results revealed that FMO treatment exhibited cytotoxicity, demonstrating dose-dependent effects. The TUNEL analysis and flow cytometry analysis revealed that FMO induced apoptosis in A549 cells. The Western blotting analysis revealed that FMO upregulated the expression of p53 and Bax protein, and downregulated the expression of Bcl-2 protein. The GC-MS analysis revealed eight components identified in FMO. These findings indicate that FMO can induce A549 apoptosis through the p53/Bcl-2/Bax pathways, confirming the apoptotic effects of M. figo on lung cancer cells. These results highlight the potential, for the first time, of M. figo as a source for developing novel drugs for lung cancer treatment.

Next-Generation Sequencing and Triple-Negative Breast Cancer: Insights and Applications

The poor survival of triple-negative breast cancer (TNBC) is due to its aggressive behavior, large heterogeneity, and high risk of recurrence. A comprehensive molecular investigation of this type of breast cancer using high-throughput next-generation sequencing (NGS) methods may help to elucidate its potential progression and discover biomarkers related to patient survival. In this review, the NGS applications in TNBC research are described. Many NGS studies point to TP53 mutations, immunocheckpoint response genes, and aberrations in the PIK3CA and DNA repair pathways as recurrent pathogenic alterations in TNBC. Beyond their diagnostic and predictive/prognostic value, these findings suggest potential personalized treatments in PD -L1-positive TNBC or in TNBC with a homologous recombination deficit. Moreover, the comprehensive sequencing of large genomes with NGS has enabled the identification of novel markers with clinical value in TNBC, such as AURKA, MYC, and JARID2 mutations. In addition, NGS investigations to explore ethnicity-specific alterations have pointed to EZH2 overexpression, BRCA1 alterations, and a BRCA2-delaAAGA mutation as possible molecular signatures of African and African American TNBC. Finally, the development of long-read sequencing methods and their combination with optimized short-read techniques promise to improve the efficiency of NGS approaches for future massive clinical use.

Potential predictive value of circulating tumor DNA (ctDNA) mutations for the efficacy of immune checkpoint inhibitors in advanced triple-negative breast cancer

Background: In recent years, tumor immunotherapy has become a viable treatment option for triple negative breast cancer (TNBC). Among these, immune checkpoint inhibitors (ICIs) have demonstrated good efficacy in advanced TNBC patients with programmed death-ligand 1 (PD-L1) positive expression. However, only 63% of PD-L1-positive individuals showed any benefit from ICIs. Therefore, finding new predictive biomarkers will aid in identifying patients who are likely to benefit from ICIs. In this study, we used liquid biopsies and next-generation sequencing (NGS) to dynamically detect changes in circulating tumor DNA (ctDNA) in the blood of patients with advanced TNBC treated with ICIs and focused on its potential predictive value.

Methods: From May 2018 to October 2020, patients with advanced TNBC treated with ICIs at Shandong Cancer Hospital were included prospectively. Patient blood samples were obtained at the pretreatment baseline, first response evaluation, and disease progression timepoints. Furthermore, 457 cancer-related genes were evaluated by NGS, and patients’ ctDNA mutations, gene mutation rates, and other indicators were determined and coupled with clinical data for statistical analysis.

Results: A total of 11 TNBC patients were included in this study. The overall objective response rate (ORR) was 27.3%, with a 6.1-month median progression-free survival (PFS) (95% confidence interval: 3.877–8.323 months). Of the 11 baseline blood samples, 48 mutations were found, with the most common mutation types being frame shift indels, synonymous single-nucleotide variations (SNVs), frame indel missenses, splicing, and stop gains. Additionally, univariate Cox regression analysis revealed that advanced TNBC patients with one of 12 mutant genes (CYP2D6 deletion and GNAS, BCL2L1, H3F3C, LAG3, FGF23, CCND2, SESN1, SNHG16, MYC, HLA-E, and MCL1 gain) had a shorter PFS with ICI treatment (p < 0.05). To some extent, dynamic changes of ctDNA might indicate the efficacy of ICIs.

Conclusion: Our data indicate that ICI efficacy in patients with advanced TNBC may be predicted by 12 mutant ctDNA genes. Additionally, dynamic alterations in peripheral blood ctDNA might be used to track the effectiveness of ICI therapy in those with advanced TNBC.

The functional role of p38 MAPK pathway in malignant brain tumors

Gliomas are extremely debilitating malignant brain tumors with very limited response to therapies. The initiation and progression of gliomas can be attributed to several molecular abnormalities, such as mutations in important regulatory networks. In this regard, the mitogen-activated protein kinases (MAPKs) arise as key signaling pathways involved in cell proliferation, survival, and differentiation. MAPK pathway has been altered in most glial tumors. In glioma cells, the activation of p38 MAPK contributes to tumor invasion and metastasis and is positively correlated with tumor grade, being considered a potential oncogenic factor contributing to brain tumorigenesis and chemotherapy resistance. Hence, a better understanding of glioma pathogenesis is essential to the advancement of therapies that provide extended life expectancy for glioma patients. This review aims to explore the role of the p38 MAPK pathway in the genesis and progression of malignant brain tumors.

Extracellular vesicles of cannabis with high CBD content induce anticancer signaling in human hepatocellular carcinoma

Plant-derived extracellular vesicles (EVs) have been the topic of interest in recent years due to their proven therapeutic properties. Intact or manipulated plant EVs have shown antioxidant, anti-inflammatory, and anti-cancerous activities as a result of containing bioactive metabolites and other endogenous molecules. Less is known about the EV efficacy with high levels of bioactive secondary metabolites derived from medicinal or non-edible plants. Numerous data suggest the functionality of Cannabis sativa extract and its phytocannabinoids in cancer treatment. Here, two chemotypes of cannabis with different levels of D-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) were selected. EVs were isolated from each chemotype via differential ultracentrifugation. HPLC analysis was illustrative of the absence of THC in EVs derived from both plants. Therefore, two types of EVs were classified according to their CBD content into high- (H.C-EVs) and low-CBD EVs (L.C-EVs). Electron microscopy and DLS showed both cannabis-derived EVs (CDEVs) can be considered as exosome-like nanovesicles. Cytotoxicity assay showed that H.C-EVs strongly decreased the viability of two hepatocellular carcinoma (HCC) cell lines, HepG2 and Huh-7, in a dose and time-dependent manner compared with L.C-EVs. H.C-EVs had no significant effect on HUVECs normal cell growth. The finding showed that the H.C-EVs arrested the G0/G1 phase in the cell cycle and significantly induced cell death by activating mitochondrial-dependent apoptosis signaling pathways in both HCC cell lines. Altogether, the current study highlights that CDEVs can be an ideal natural vehicle for bioactive phytocannabinoids and a promising strategy in cancer management.

Protective effects of Persea americana fruit and seed extracts against chemically induced liver cancer in rats by enhancing their antioxidant, anti-inflammatory, and apoptotic activities

This study aims to explore the chemopreventive mechanisms of hydroethanolic extracts from avocado (Persea Americana) in diethylnitrosamine (DEN)/2-acetylaminofluorene (2AAF)-induced hepatocarcinogenesis. Chemical induction of hepatocarcinogenesis was induced by intraperitoneal injection of DEN at 150 mg/kg body weight (b.w.) twice a week for a fortnight, followed by oral administration of 2AAF at 20 mg/kg b.w. four times a week for 3 weeks. Rats administered DEN/2AAF were orally treated with hydroethanolic extracts of avocado fruits and seeds at a dose of 50 mg/kg b.w. every other day for 20 weeks. Moreover, rats administered DEN/2AAF and treated with avocado extracts revealed a marked decrease in liver enzyme activities, total bilirubin levels, and elevated liver tumor markers, but revealed an increase in total protein and albumin levels. The hepatocytes with hyperchromatic and bile duct cystadenoma observed in the liver of rats administered DEN/2AAF were reduced due to treatment with avocado extracts. Furthermore, the treatments prevented the elevation of lipid peroxidation levels and ameliorated the lowered glutathione peroxidase, glutathione-S-transferase, superoxide dismutase activities, and glutathione content in the liver tissues. Also, antigen Ki-67, cyclooxygenase-2, and nuclear factor kappa-B expression levels were decreased, but of the suppressor proteins p53 and BAX levels were increased in the liver of rats administered DEN/2AAF and treated with avocado extracts. In conclusion, the current results demonstrated that avocado extracts could abate hepatocarcinogenesis in rats administered DEN/2AAF through activation of antioxidant, anti-inflammatory, and apoptotic properties.

Theranostic Interpolation of Genomic Instability in Breast Cancer

Breast cancer is a diverse disease caused by mutations in multiple genes accompanying epigenetic aberrations of hazardous genes and protein pathways, which distress tumor-suppressor genes and the expression of oncogenes. Alteration in any of the several physiological mechanisms such as cell cycle checkpoints, DNA repair machinery, mitotic checkpoints, and telomere maintenance results in genomic instability. Theranostic has the potential to foretell and estimate therapy response, contributing a valuable opportunity to modify the ongoing treatments and has developed new treatment strategies in a personalized manner. “Omics” technologies play a key role while studying genomic instability in breast cancer, and broadly include various aspects of proteomics, genomics, metabolomics, and tumor grading. Certain computational techniques have been designed to facilitate the early diagnosis of cancer and predict disease-specific therapies, which can produce many effective results. Several diverse tools are used to investigate genomic instability and underlying mechanisms. The current review aimed to explore the genomic landscape, tumor heterogeneity, and possible mechanisms of genomic instability involved in initiating breast cancer. We also discuss the implications of computational biology regarding mutational and pathway analyses, identification of prognostic markers, and the development of strategies for precision medicine. We also review different technologies required for the investigation of genomic instability in breast cancer cells, including recent therapeutic and preventive advances in breast cancer.

8-Formylophiopogonanone B induces ROS-mediated apoptosis in nasopharyngeal carcinoma CNE-1 cells

Cancer is one of the leading causes of death in the world. It is very important to find drugs with high efficiency, low toxicity, and low side effects for the treatment of cancer. Flavonoids and their derivatives with broad biological functions have been recognized as anti-tumor chemicals. 8-Formylophiopogonanone B (8-FOB), a naturally existed homoisoflavonoids with rarely known biological functions, needs pharmacological evaluation. In order to explore the possible anti-tumor action of 8-FOB, we used six types of tumor cells to evaluate in vitro effects of this agent on cell viability and tested the effects on clone formation ability, scratching wound-healing, and apoptosis. In an attempt to elucidate the mechanism of pharmacological action, we examined 8-FOB-induced intracellular oxidative stress and -disrupted mitochondrial function. Results suggested that 8-FOB could suppress tumor cell viability, inhibit cell migration and invasion, induce apoptosis, and elicit intracellular ROS production. Among these six types of tumor cells, the nasopharyngeal carcinoma CNE-1 cells were the most sensitive cancer cells to 8-FOB treatment. Intracellular ROS production played a pivotal role in the anti-tumor action of 8-FOB. Our present study is the first to document that 8-FOB has anti-tumor activity in vitro and increases intracellular ROS production, which might be responsible for its anti-tumor action. The anti-tumor pharmacological effect of 8-FOB is worthy of further investigation.

Relevance of Circulating Nucleosomes, HMGB1 and sRAGE for Prostate Cancer Diagnosis

BACKGROUND/AIM

Evasion from cell death occurs in prostate cancer (PCa). We verified whether serum levels of cell death markers can have diagnostic value in PCa.

PATIENTS AND METHODS

A total of 233 men scheduled for prostate biopsy [prostate specific antigen (PSA) level: 2-10 ng/ml] were enrolled. Serum nucleosomes, nucleosomes containing the H3 histone (H3), high mobility group box 1 (HMGB1), and soluble receptor for advanced glycation end products (sRAGE) were analyzed by enzyme immunoassays.

RESULTS

There were no differences (p>0.05) in nucleosomes, H3, and sRAGE levels between patients with and without PCa or clinically significant PCa (csPCa). HMGB1 had lower levels in PCa patients (p=0.023) and was a predictor of PCa (p=0.047), but not of csPCa (p=0.180).

CONCLUSION

In patients with critical PSA levels between 2-10 ng/ml, HMGB1 had some diagnostic value for overall PCa detection, but it was not predictive of csPCa. Nucleosomes, H3 and sRAGE did not discriminate between PCa or csPCa and controls.

Overexpression of GRP78/BiP in P-Glycoprotein-Positive L1210 Cells is Responsible for Altered Response of Cells to Tunicamycin as a Stressor of the Endoplasmic Reticulum

P-glycoprotein (P-gp, ABCB1 member of the ABC (ATP-binding cassette) transporter family) localized in leukemia cell plasma membranes is known to reduce cell sensitivity to a large but well-defined group of chemicals known as P-gp substrates. However, we found previously that P-gp-positive sublines of L1210 murine leukemia cells (R and T) but not parental P-gp-negative parental cells (S) are resistant to the endoplasmic reticulum (ER) stressor tunicamycin (an N-glycosylation inhibitor). Here, we elucidated the mechanism of tunicamycin resistance in P-gp-positive cells. We found that tunicamycin at a sublethal concentration of 0.1 µM induced retention of the cells in the G1 phase of the cell cycle only in the P-gp negative variant of L1210 cells. P-gp-positive L1210 cell variants had higher expression of the ER stress chaperone GRP78/BiP compared to that of P-gp-negative cells, in which tunicamycin induced larger upregulation of CHOP (C/EBP homologous protein). Transfection of the sensitive P-gp-negative cells with plasmids containing GRP78/BiP antagonized tunicamycin-induced CHOP expression and reduced tunicamycin-induced arrest of cells in the G1 phase of the cell cycle. Taken together, these data suggest that the resistance of P-gp-positive cells to tunicamycin is due to increased levels of GRP78/BiP, which is overexpressed in both resistant variants of L1210 cells.

Adenosine Signaling in Glioma Cells

Purines and pyrimidines are fundamental signaling molecules in controlling the survival and proliferation of astrocytes, as well as in mediating cell-to-cell communication between glial cells and neurons in the healthy brain. The malignant transformation of astrocytes towards progressively more aggressive brain tumours (from astrocytoma to anaplastic glioblastoma) leads to modifications in both the survival and cell death pathways which overall confer a growth advantage to malignant cells and resistance to many cytotoxic stimuli. It has been demonstrated, however, that, in astrocytomas, several purinergic (in particular adenosinergic) pathways controlling cell survival and death are still effective and, in some cases, even enhanced, providing invaluable targets for purine-based chemotherapy, that still represents an appropriate pharmacological approach to brain tumours. In this chapter, the current knowledge on both receptor-mediated and receptor-independent adenosine pathways in astrocytomas will be reviewed, with a particular emphasis on the most promising targets which could be translated from in vitro studies to in vivo pharmacology. Additionally, we have included new original data from our laboratory demonstrating a key involvement of MAP kinases in the cytostastic and cytotoxic effects exerted by an adenosine analogue, 2-CdA, which with the name of Cladribine is already clinically utilized in haematological malignancies. Here we show that 2-CdA can activate multiple intracellular pathways leading to cell cycle block and cell death by apoptosis of a human astrocytoma cell line that bears several pro-survival genetic mutations. Although in vivo data are still lacking, our results suggest that adenosine analogues could therefore be exploited to overcome resistance to chemotherapy of brain tumours.

The CUL5 ubiquitin ligase complex mediates resistance to CDK9 and MCL1 inhibitors in lung cancer cells

Overexpression of anti-apoptotic proteins MCL1 and Bcl-xL are frequently observed in many cancers. Inhibitors targeting MCL1 are in clinical development, however numerous cancer models are intrinsically resistant to this approach. To discover mechanisms underlying resistance to MCL1 inhibition, we performed multiple flow-cytometry based genome-wide CRISPR screens interrogating two drugs that directly (MCL1i) or indirectly (CDK9i) target MCL1. Remarkably, both screens identified three components (CUL5, RNF7 and UBE2F) of a cullin-RING ubiquitin ligase complex (CRL5) that resensitized cells to MCL1 inhibition. We find that levels of the BH3-only pro-apoptotic proteins Bim and Noxa are proteasomally regulated by the CRL5 complex. Accumulation of Noxa caused by depletion of CRL5 components was responsible for re-sensitization to CDK9 inhibitor, but not MCL1 inhibitor. Discovery of a novel role of CRL5 in apoptosis and resistance to multiple types of anticancer agents suggests the potential to improve combination treatments.

Algae metabolites: from in vitro growth inhibitory effects to promising anticancer activity

Covering: 1957 to 2017 Algae constitute a heterogeneous group of eukaryotic photosynthetic organisms, mainly found in the marine environment. Algae produce numerous metabolites that help them cope with the harsh conditions of the marine environment. Because of their structural diversity and uniqueness, these molecules have recently gained a lot of interest for the identification of medicinally useful agents, including those with potential anticancer activities. In the current review, which is not a catalogue-based one, we first highlight the major biological events that lead to various types of cancer, including metastatic ones, to chemoresistance, thus to any types of current anticancer treatment relating to the use of chemotherapeutics. We then review algal metabolites for which scientific literature reports anticancer activity. Lastly, we focus on algal metabolites with promising anticancer activity based on their ability to target biological characteristics of cancer cells responsible for poor treatment outcomes. Thus, we highlight compounds that have, among others, one or more of the following characteristics: selectivity in reducing the proliferation of cancer cells over normal ones, potential for killing cancer cells through non-apoptotic signaling pathways, ability to circumvent MDR-related efflux pumps, and activity in vivo in relevant pre-clinical models.

Targeting prostate cancer cell proliferation, stemness and metastatic potential using Costus speciosus derived phytochemicals

Prostate cancer is still at the forefront causes of cancer-related morbidity and mortality in men throughout the globe. The disease is initiated and fostered by a subset of cancer stem cells (CSCs). Costus speciosus is an oriental herb used in traditional medicine and is a source of bioactive compounds with known pharmacological activities. The present study aims to evaluate the anticancer property of varied extracts isolated from C. speciosus against the human prostate cancer PC-3 cells. Extracts derived from C. speciosus were analyzed by chromatography-mass spectrometry and their effects on the proliferation, migration, invasion, apoptosis and cell cycle distribution of PC-3 cells were investigated. Results showed that crude hexane extract of C. speciosus (CHECS) inhibited proliferation, clonogenic and metastatic potential of PC-3 cells. It induced apoptosis in PC-3 cells associated with generation of reactive oxygen species (ROS), reduction of GSH and permeabilization of mitochondrial and lysosomal membranes, induction of caspase-9/-3 activity and PARP-1 cleavage, DNA damage and an increase in ratio of Bax/Bcl-2 proteins. CHECS induced G0/G1 and G2/M arrest in PC-3 cells and targeted PC-3 prostaspheres. These findings indicate that phytochemicals of CHECS exhibit potential for natural therapeutic product development for prostate cancer.

BH3-Mimetic Drugs: Blazing the Trail for New Cancer Medicines

Defects in apoptotic cell death can promote cancer and impair responses of malignant cells to anti-cancer therapy. Pro-survival BCL-2 proteins prevent apoptosis by keeping the cell death effectors, BAX and BAK, in check. The BH3-only proteins initiate apoptosis by neutralizing the pro-survival BCL-2 proteins. Structural analysis and medicinal chemistry led to the development of small-molecule drugs that mimic the function of the BH3-only proteins to kill cancer cells. The BCL-2 inhibitor venetoclax has been approved for treatment of refractory chronic lymphocytic leukemia and this drug and inhibitors of pro-survival MCL-1 and BCL-XL are being tested in diverse malignancies.

The proliferation of colorectal cancer cells is suppressed by silencing of EIF3H

Colorectal cancer is one of the most common causes of cancer-related deaths worldwide. Eukaryotic translation initiation factor 3, subunit H (EIF3H) is a subunit of EIF3, which is involved in mRNA recruitment and ribosomal complex disassembly and is known to be a driver of cell proliferation and survival in cancer. To investigate its function in colorectal cancer, the Oncomine database was used to evaluate the expression of EIF3H in human colorectal cancer and normal tissues. Then, we constructed a Lentivirus shorthair EIF3H vector (Lv-shEIF3H) to silence EIF3H expression in the colorectal cancer cell lines HCT116 and SW1116. We observed impaired cell growth and colony formation in these silenced cell lines. In addition, we showed that EIF3H knock-down led to cell apoptosis. In conclusion, EIF3H plays key roles in the apoptosis in colorectal cancer cells, which suggests EIF3H as a potential diagnostic biomarker in colorectal cancer.

The impact of phosphatases on proliferative and survival signaling in cancer

The dynamic and stringent coordination of kinase and phosphatase activity controls a myriad of physiologic processes. Aberrations that disrupt the balance of this interplay represent the basis of numerous diseases. For a variety of reasons, early work in this area portrayed kinases as the dominant actors in these signaling events with phosphatases playing a secondary role. In oncology, these efforts led to breakthroughs that have dramatically altered the course of certain diseases and directed vast resources toward the development of additional kinase-targeted therapies. Yet, more recent scientific efforts have demonstrated a prominent and sometimes driving role for phosphatases across numerous malignancies. This maturation of the phosphatase field has brought with it the promise of further therapeutic advances in the field of oncology. In this review, we discuss the role of phosphatases in the regulation of cellular proliferation and survival signaling using the examples of the MAPK and PI3K/AKT pathways, c-Myc and the apoptosis machinery. Emphasis is placed on instances where these signaling networks are perturbed by dysregulation of specific phosphatases to favor growth and persistence of human cancer.

Long noncoding RNA MIAT regulates apoptosis and the apoptotic response to chemotherapeutic agents in breast cancer cell lines

The long noncoding RNA myocardial infarction associated transcript (MIAT) is involved in a number of diseases, including myocardial infarction and diabetic retinopathy. Emerging evidence suggests that MIAT expression levels are increased in different type of cancers, including breast cancer. In the present study, we further evaluated the role of MIAT in breast cancer and investigated the consequences of its silencing on breast cancer response to chemotherapeutic agents. Expression levels of MIAT mRNA in breast cancer were determined using TissueScan™ Breast Cancer cDNA Arrays. Breast cancer cell lines were transfected with MIAT specific siRNAs, with silencing confirmed using RT-qPCR and the effects on breast cancer cell survival and response to different apoptotic stimuli determined. MIAT transcript levels were significantly elevated in breast cancer samples. Such increase was specific to the early stages of the disease, ER, PR +ve, HER –ve, and triple negative breast cancer samples. Silencing of MIAT induced growth arrest and increased basal apoptosis. Reduced levels of MIAT augmented the apoptotic response of breast cancer cells to a wide range of apoptotic stimuli. Our results also showed that MIAT down-regulation was associated with a decrease in OCT4 mRNA, suggesting the existence of a MIAT/OCT4 regulatory loop, similar to that observed in malignant mature B cells. Taken together with the recent demonstration of oncogene characteristics, our observations suggest that MIAT plays an important role in breast tumorigenesis. Strategies to decrease MIAT expression levels may improve sensitivity to therapy in breast cancer by enhancing the apoptotic responses to conventional chemotherapies.

Knockdown of ribosomal protein S15A inhibits proliferation of breast cancer cells through induction of apoptosis in vitro

To explore the role of ribosomal protein S15A (RPS15A) in breast cancer. The Oncomine database was used to compare the expression of RPS15A in human breast cancer tissues and normal tissues. RPS15A in breast cancer cell line ZR-75-30 and BT474 was specifically knocked down using lentivirus-mediated short hairpin RNAs (shRNAs). RPS15A knockdown efficiency was validated by quantitative polymerase chain reaction and western blot analysis. Subsequently, the functional effects of RPS15A on proliferation of breast cancer cells were investigated by MTT, colony formation and flow cytometry assays. Functional analysis indicated that RPS15A knockdown could inhibit cell proliferation, induced cell cycle arrest and apoptosis. Mechanism analysis revealed RPS15A mediated apoptosis via activating of caspase-3 and PARP cleavage, upregulating of Bad and BAX and downregulating of Bcl-2. Our preliminary study highlighted the importance of RPS15A in breast cancer growth. The inhibition of RPS15A may be a promising therapeutic target for breast cancer treatment.

Learning on the Fly: The Interplay between Caspases and Cancer

The ease of genetic manipulation, as well as the evolutionary conservation of gene function, has placed Drosophila melanogaster as one of the leading model organisms used to understand the implication of many proteins with disease development, including caspases and their relation to cancer. The family of proteases referred to as caspases have been studied over the years as the major regulators of apoptosis: the most common cellular mechanism involved in eliminating unwanted or defective cells, such as cancerous cells. Indeed, the evasion of the apoptotic programme resulting from caspase downregulation is considered one of the hallmarks of cancer. Recent investigations have also shown an instrumental role for caspases in non-lethal biological processes, such as cell proliferation, cell differentiation, intercellular communication, and cell migration. Importantly, malfunction of these essential biological tasks can deeply impact the initiation and progression of cancer. Here, we provide an extensive review of the literature surrounding caspase biology and its interplay with many aspects of cancer, emphasising some of the key findings obtained from Drosophila studies. We also briefly describe the therapeutic potential of caspase modulation in relation to cancer, highlighting shortcomings and hopeful promises.

MCL-1 is a prognostic indicator and drug target in breast cancer

Analysis of publicly available genomic and gene expression data demonstrates that MCL1 expression is frequently elevated in breast cancer. Distinct from other pro-survival Bcl-2 family members, the short half-life of MCL-1 protein led us to investigate MCL-1 protein expression in a breast cancer tissue microarray and correlate this with clinical data. Here, we report associations between high MCL-1 and poor prognosis in specific subtypes of breast cancer including triple-negative breast cancer, an aggressive form that lacks targeted treatment options. Deletion of MCL-1 in the mammary epithelium of genetically engineered mice revealed an absolute requirement for MCL-1 in breast tumorigenesis. The clinical applicability of these findings was tested through a combination of approaches including knock-down or inhibition of MCL-1 to show triple-negative breast cancer cell line dependence on MCL-1 in vitro and in vivo. Our data demonstrate that high MCL-1 protein expression is associated with poor outcome in breast cancer and support the therapeutic targeting of MCL-1 in this disease.

EBV and Apoptosis: The Viral Master Regulator of Cell Fate?

Epstein-Barr virus (EBV) was first discovered in cells from a patient with Burkitt lymphoma (BL), and is now known to be a contributory factor in 1-2% of all cancers, for which there are as yet, no EBV-targeted therapies available. Like other herpesviruses, EBV adopts a persistent latent infection in vivo and only rarely reactivates into replicative lytic cycle. Although latency is associated with restricted patterns of gene expression, genes are never expressed in isolation; always in groups. Here, we discuss (1) the ways in which the latent genes of EBV are known to modulate cell death, (2) how these mechanisms relate to growth transformation and lymphomagenesis, and (3) how EBV genes cooperate to coordinately regulate key cell death pathways in BL and lymphoblastoid cell lines (LCLs). Since manipulation of the cell death machinery is critical in EBV pathogenesis, understanding the mechanisms that underpin EBV regulation of apoptosis therefore provides opportunities for novel therapeutic interventions.

MicroRNA-148a promotes apoptosis and suppresses growth of breast cancer cells by targeting B-cell lymphoma 2

MicroRNAs (miRNAs) contribute toward tumorigenesis through the modulation of tumor-related genes. MiR-148a has been characterized as a tumor-suppressing miRNA and its downregulation has been reported in tumors of a variety of cancers. However, the functional role of miR-148a in breast cancer is not yet fully understood. Using both in-vitro and in-vivo models, we confirmed that miR-148a acts to inhibit the proliferation of breast cancer cells. Through the use of bioinformatic approaches in miRNA target prediction, we determined that B-cell lymphoma 2 (BCL-2) is a likely target of miR-148a. The overexpression and tumorigenic effects of BCL-2 have already been confirmed in cancerous tumors of the breast. A dual-luciferase assay was performed to confirm that miR-148a targets the 3'-untranslated region of BCL-2. In this study, we first characterized the downregulation of miR-148a in breast cancer tissues. We then found that restoring expression of miR-148a suppressed the expression of BCL-2 at the level of both mRNA and protein. Upregulation of miR-148a caused a subsequent reduction of proliferation and an increase in apoptosis. In conclusion, we have confirmed the role of miR-148a as a pivotal regulator in breast cancer through its targeting of BCL-2. This evidence strongly suggests that miR-148a could prove to be a novel therapeutic target in breast cancer.

Residential traffic noise exposure and vestibular schwannoma - a Danish case-control study

BACKGROUND

Few risk factors for sporadic vestibular schwannoma (VS) are known. Several studies have proposed an increased risk with occupational noise exposure, whereas no studies have investigated residential traffic noise exposure as a risk factor. The present study investigated if residential traffic noise was associated with vestibular schwannoma in a large, population-based Danish case-control study.

MATERIAL AND METHODS

We identified 1454 VS cases, age above 30 years at diagnosis, between 1990 and 2007. For each case, we selected two random population controls, matched on sex and year of birth. Road and railway traffic noise at the residence was calculated for all present and historical addresses between 1987 and index date. Associations between traffic noise and risk for VS were estimated using conditional logistic regression, adjusted for education, disposable personal income, cohabitation status, railway noise exposure, municipal population density, and municipal income.

RESULTS

A two-year time-weighted mean road traffic noise exposure was associated with an adjusted odds ratio of 0.92 (0.82-1.03) for developing VS, per 10 dB increment. There was no clear trend in categorical analyses. Similarly, linear and categorical analyses of residential railway noise did not suggest an association. We found no interaction with demographics, year of diagnosis, individual and municipal socioeconomic variables, and railway noise exposure. The results did not differ by tumor side, spread or size.

CONCLUSIONS

The present study does not suggest an association between residential traffic noise and VS.

Assessing the anticancer effects associated with food products and/or nutraceuticals using in vitro and in vivo preclinical development-related pharmacological tests

This review is part of a special issue entitled "Role of dietary pattern, foods, nutrients and nutraceuticals in supporting cancer prevention and treatment" and describes a pharmacological strategy to determine the potential contribution of food-related components as anticancer agents against established cancer. Therefore, this review does not relate to chemoprevention, which is analysed in several other reviews in the current special issue, but rather focuses on the following: i) the biological events that currently represent barriers against the treatment of certain types of cancers, primarily metastatic cancers; ii) the in vitro and in vivo pharmacological pre-clinical tests that can be used to analyse the potential anticancer effects of food-related components; and iii) several examples of food-related components with anticancer effects. This review does not represent a catalogue-based listing of food-related components with more or less anticancer activity. By contrast, this review proposes an original pharmacological strategy that researchers can use to analyse the potential anticancer activity of any food-related component-e.g., by considering the crucial characteristics of cancer biological aggressiveness. This review also highlights that cancer patients undergoing chemotherapy should restrict the use of "food complements" without supervision by a medical nutritionist. By contrast, an equilibrated diet that includes the food-related components listed herein would be beneficial for cancer patients who are not undergoing chemotherapy.

Marine Terpenoid Diacylguanidines: Structure, Synthesis, and Biological Evaluation of Naturally Occurring Actinofide and Synthetic Analogues

A new diacylguanidine, actinofide (1), has been isolated from the marine mollusk Actinocyclus papillatus. The structure, exhibiting a guanidine moiety acylated by two terpenoid acid units, has been established by spectroscopic methods and secured by synthesis. Following this, a series of structural analogues have been synthesized using the same procedure. All of the compounds have been evaluated in vitro for the growth inhibitory activity against a variety of cancer cell lines.

Angiotensin II receptor blockers induce autophagy in prostate cancer cells

Angiotensin II receptor blockers (ARBs) are anti-hypertensive drugs that competitively inhibit the binding of angiotensin II to its receptor, resulting in blood vessel dilation and the reduction of blood pressure. These antagonists are also known as sartans, and are a group of pharmaceuticals that possess tetrazole or imidazole groups. In the present study, the anticancer and antimetastatic effects of the ARBs fimasartan, losartan, eprosartan and valsartan on the human prostate cancer PC-3, DU-145 and LNCap-LN3 cell lines were investigated in vitro. The proliferation of the prostate cancer cells was inhibited following treatment with 100 µM ARB. In particular, treatment with fimasartan resulted in marked anti-proliferative activity compared with the other ARBs. With respect to the molecular mechanism of the growth inhibition exhibited by the ARBs, 3-methyladenin (3-MA), an autophagy inhibitor, was revealed to increase the survival rate of PC-3 cells when cell death inhibitors were pretreated with fimasartan. In addition, the ARBs induced autophagy with increased expression levels of autophagy protein (Atg) 5-12, Atg 16-like-1, beclin-1 and microtubule-associated protein 1A/1B-light chain 3 (LC3). Notably, the enhanced expression of LC3-II (a 6.7-fold increase at 72 h) was observed in PC3 cells treated with fimasartan. This was supported by the observation of the time-dependent accumulation of LC3-positive foci in PC-3. In addition, a migration assay indicated that the ARBs induced anti-metastatic effects in PC-3 and DU-145 cells. The aforementioned results suggest that ARBs may induce autophagy-associated cell death and anti-metastatic activity in prostate cancer cells. Thus, ARBs may be a potential medication for patients with prostate cancer and hypertension.

The expression of aplysia ras homolog I (ARHI) and its inhibitory effect on cell biological behavior in esophageal squamous cell carcinoma

Background

Aplysia ras homolog I (ARHI) is a Ras-related maternally imprinted tumor suppressor gene. Loss of ARHI expression contributes to the malignant progression of various tumors. However, reports on the clinical implications and functional role of ARHI expression in esophageal squamous cell carcinoma (ESCC) are limited. This study examined the role of ARHI in ESCC.

Methods

In total, 81 patients diagnosed with ESCC based on histopathological evaluations who were subjected to surgical resection were included in the study. ARHI expression was analyzed by immunohistochemistry and western blotting, examining the correlations between ARHI expression and patient clinicopathological features. The functional effects of ARHI overexpression were examined using a Cell Counting Kit-8 assay, flow cytometry, a Transwell assay, wound healing, and western blotting in the ECA109 cell line.

Results

ARHI was highly expressed in 27.5% (22/81) of ESCC specimens (adjacent noncancerous tissues, 85.2%, 69/81; P<0.05). The ARHI expression level was significantly lower in patients with lymph node metastasis than in patients without (P<0.05). A Kaplan–Meier survival analysis showed that patients with low ARHI expression had shorter survival than patients with high expression (P<0.05), and a multivariate Cox analysis revealed that ARHI is an independent predictor of overall survival (P=0.029). Finally, overexpression of ARHI in ESCC cells indicates that ARHI suppresses proliferative capacity, invasive capacity, and cell cycle progression and may also suppress epithelial–mesenchymal transition and induce apoptosis and autophagy.

Conclusion

ARHI may be a prognostic biomarker and a potential therapeutic target in ESCC.

Anti-hepatocarcinogenic and Anti-oxidant Effects of Mangrove Plant Scyphiphora hydrophyllacea

CONTEXT

Scyphiphora hydrophyllacea is a shrub mangrove plant of the family Rubiaceae and not yet been studied for anti-hepatocarcinogenic effects.

OBJECTIVES

We investigated possible in vitro anti-hepatocarcinogenic and antioxidant properties of S. hydrophyllacea.

MATERIALS AND METHODS

Dried leaves of S. hydrophyllacea were sequentially extracted into hexane, chloroform, ethyl acetate, and methanol and tested for cytotoxicity on HepG2 cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and sulforhodamine B assays, and for antioxidant activities by the free radical 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) assays. Total phenolic and flavonoid contents were estimated in all four extracts. The hexane and chloroform extracts were tested for pro-apoptotic properties in HepG2 cells, and bioactive components were identified by gas chromatography-mass spectrometry (GC-MS) analysis.

RESULTS

The hexane and chloroform extracts showed dose-dependent and time-dependent cytotoxic effects. Morphological changes observed under fluorescence microscope related to apoptosis, and significant (P < 0.001) increases in caspase 3 and 9 levels were observed in hexane and chloroform extract-treated cells. Slight DNA fragmentation was observed only in response to the chloroform extract. mRNA expressions of p53 and Bax were significantly upregulated by low doses of hexane and chloroform extracts. Highest antioxidant activity was observed in the methanol extract. GC-MS profiles identified 24 and four major compounds in the hexane and chloroform extracts, respectively. These included some known anticancer compounds such as lupeol.

CONCLUSION

Cytotoxicity, antioxidant effects, and apoptosis-related changes exerted by hexane and chloroform extracts of S. hydrophyllacea concluded that these two extracts are good source for isolation of possible anticarcinogenic compounds.

SUMMARY

The hexane and chloroform extracts of Scyphiphora hydrophyllacea showed dose-dependent and time-dependent cytotoxic effects.Morphological changes related to apoptosis and significant (P < 0.001) increases in caspase 3 and 9 levels were observed in hexane and chloroform extract-treated cells.mRNA expressions of p53 and Bax were significantly upregulated by low doses of hexane and chloroform extracts.Highest antioxidant activity was observed in the methanol extract.GC-MS profiles identified 24 and four major compounds in the hexane and chloroform extracts, respectively. Abbreviation used: DPPH: 1,1-diphenyl-2-picryl-hydrazyl, ABTS: 2,2'-azinobis-3-ethylbenzthiazoline-6-sulfonic acid, GC-MS: gas chromatography-mass spectrometry, DNA: deoxyribonucleic acid, HCC: Hepatocellular carcinoma, GAE: gallic acid equivalents, SRB: sulforhodamine B, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, AO/EB: acridine orange/ethidium bromide, GAPDH: Glyceraldehyde 3-phosphate dehydrogenase, IC50: half maximal inhibitory concentration; QE: quercetin equivalents, HE: hexane extract, CE: chloroform extract, EAE: ethyl acetate extract, ME: methanolic extract, TPC: total polyphenol content, TFC: total flavonoid content, ANOVA: Analysis of variance.

Expanding the Cancer Arsenal with Targeted Therapies: Disarmament of the Antiapoptotic Bcl-2 Proteins by Small Molecules

A hallmark of cancer is the evasion of apoptosis, which is often associated with the upregulation of the antiapoptotic members of the Bcl-2 family of proteins. The prosurvival function of the antiapoptotic Bcl-2 proteins is manifested by capturing and neutralizing the proapoptotic Bcl-2 proteins via their BH3 death domains. Accordingly, strategies to antagonize the antiapoptotic Bcl-2 proteins have largely focused on the development of low-molecular-weight, synthetic BH3 mimetics ("magic bullets") to disrupt the protein-protein interactions between anti- and proapoptotic Bcl-2 proteins. In this way, apoptosis has been reactivated in malignant cells. Moreover, several such Bcl-2 family inhibitors are presently being evaluated for a range of cancers in clinical trials and show great promise as new additions to the cancer armamentarium. Indeed, the selective Bcl-2 inhibitor venetoclax (Venclexta) recently received FDA approval for the treatment of a specific subset of patients with chronic lymphocytic leukemia. This review focuses on the major developments in the field of Bcl-2 inhibitors over the past decade, with particular emphasis on binding modes and, thus, the origins of selectivity for specific Bcl-2 family members.

Chemokine Receptor Signaling and the Hallmarks of Cancer

The chemokines are a family of chemotactic cytokines that mediate their activity by acting on seven-transmembrane-spanning G protein-coupled receptors. Both the ability of the chemokines and their receptors to form homo- and heterodimers and the promiscuity of the chemokine-chemokine receptor interaction endow this protein family with enormous signaling plasticity and complexity that are not fully understood at present. Chemokines were initially identified as essential regulators of homeostatic and inflammatory trafficking of innate and adaptive leucocytes from lymphoid organs to tissues. Chemokines also mediate the host response to cancer. Nevertheless, chemokine function in this response is not limited to regulating leucocyte infiltration into the tumor microenvironment. It is now known that chemokines and their receptors influence most-if not all-hallmark processes of cancer; they act on both neoplastic and untransformed cells in the tumor microenvironment, including fibroblasts, endothelial cells (blood and lymphatic), bone marrow-derived stem cells, and, obviously, infiltrating leucocytes. This review begins with an overview of chemokine and chemokine receptor structure, to better define how chemokines affect the proliferation, survival, stemness, and metastatic potential of neoplastic cells. We also examine the main mechanisms by which chemokines regulate tumor angiogenesis and immune cell infiltration, emphasizing the pro- and antitumorigenic activity of this protein superfamily in these interrelated processes.

Nurse-like cells promote CLL survival through LFA-3/CD2 interactions

In the tumoral micro-environment (TME) of chronic lymphocytic leukemia (CLL), nurse-like cells (NLC) are tumor-associated macrophages which play a critical role in the survival and chemoresistance of tumoral cells. This pro-survival activity is known to involve soluble factors, but few data are available on the relative role of cells cross-talk. Here, we used a transcriptome-based approach to systematically investigate the expression of various receptor/ligand pairs at the surface of NLC/CLL cells. Their relative contribution to CLL survival was assessed both by fluorescent microscopy to identify cellular interactions and by the use of functional tests to measure the impact of uncoupling these pairs with blocking monoclonal antibodies. We found for the first time that lymphocyte function-associated antigen 3 (LFA-3), expressed in CLL at significantly higher levels than in healthy donor B-cells, and CD2 expressed on NLC, were both key for the specific pro-survival signals delivered by NLC. Moreover, we found that NLC/CLL interactions induced the shedding of soluble LFA-3. Importantly, in an exploratory cohort of 60 CLL patients receiving frontline immunochemotherapy, increased levels of soluble LFA-3 were found to correlate with shorter overall survival. Altogether, these data suggest that LFA-3/CD2 interactions promote the survival of CLL cells in the tumor microenvironment.

5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells

Plants of the Amaryllidaceae family produce a large variety of alkaloids and non-basic secondary metabolites, many of which are investigated for their promising anticancer activities. Of these, crinine-type alkaloids based on the 5,10b-ethanophenanthridine ring system were recently shown to be effective at inhibiting proliferation of cancer cells resistant to various pro-apoptotic stimuli and representing tumors with dismal prognoses refractory to current chemotherapy, such as glioma, melanoma, non-small-cell lung, esophageal, head and neck cancers, among others. Using this discovery as a starting point and taking advantage of a concise biomimetic route to the crinine skeleton, a collection of crinine analogues were synthetically prepared and evaluated against cancer cells. The compounds exhibited single-digit micromolar activities and retained this activity in a variety of drug-resistant cancer cell cultures. This investigation resulted in the discovery of new bicyclic ring systems with significant potential in the development of effective clinical cancer drugs capable of overcoming cancer chemotherapy resistance.

Influence of doxorubicin on apoptosis and oxidative stress in breast cancer cell lines

Breast cancer is one of the leading causes of mortality among women worldwide due to aggressive behavior, early metastasis, resistance to existing chemotherapeutic agent and high mortality rate. Doxorubicin (Dox) is a powerful antitumoral drug. It is one of the most active agents for treatment of breast cancer. The aim of the present study was to evaluate the influence of Dox in apoptosis and oxidative stress in the breast cancer cell lines MCF-10F, MCF-7 and MDA-MB-231. These studies showed that Dox decreased anti-apoptotic Bcl-2 protein expression and affected oxidative stress by increasing hydrogen peroxide production and simultaneously decreasing NF-κB gene and protein expression in MCF-7, a tumorigenic triple-positive cell line. Results also indicated that Dox induced apoptosis by upregulating Bax, caspase-8 and caspase-3 and downregulation of Bcl-2 protein expression. On the contrary, ROS damage decreased by increasing SOD2 gene and protein expression and hydrogen peroxide production with parallel NF-κB protein expression decrease in MDA-MB-231, a tumorigenic triple-negative breast cancer cell line. It can be concluded that Dox activated apoptosis by inducing proteolytic processing of Bcl-2 family, caspases and simultaneously decreased oxidative stress by influencing ROS damage in MCF-7 and MDA-MB-231 cell lines.

RIP1 and RIP3 complex regulates radiation-induced programmed necrosis in glioblastoma

Radiation-induced necrosis (RN) is a relatively common side effect of radiation therapy for glioblastoma. However, the molecular mechanisms involved and the ways RN mechanisms differ from regulated cell death (apoptosis) are not well understood. Here, we compare the molecular mechanism of cell death (apoptosis or necrosis) of C6 glioma cells in both in vitro and in vivo (C6 othotopically allograft) models in response to low and high doses of X-ray radiation. Lower radiation doses were used to induce apoptosis, while high-dose levels were chosen to induce radiation necrosis. Our results demonstrate that active caspase-8 in this complex I induces apoptosis in response to low-dose radiation and inhibits necrosis by cleaving RIP1 and RI. When activation of caspase-8 was reduced at high doses of X-ray radiation, the RIP1/RIP3 necrosome complex II is formed. These complexes induce necrosis through the caspase-3-independent pathway mediated by calpain, cathepsin B/D, and apoptosis-inducing factor (AIF). AIF has a dual role in apoptosis and necrosis. At high doses, AIF promotes chromatinolysis and necrosis by interacting with histone H2AX. In addition, NF-κB, STAT-3, and HIF-1 play a crucial role in radiation-induced inflammatory responses embedded in a complex inflammatory network. Analysis of inflammatory markers in matched plasma and cerebrospinal fluid (CSF) isolated from in vivo specimens demonstrated the upregulation of chemokines and cytokines during the necrosis phase. Using RIP1/RIP3 kinase specific inhibitors (Nec-1, GSK'872), we also establish that the RIP1-RIP3 complex regulates programmed necrosis after either high-dose radiation or TNF-α-induced necrosis requires RIP1 and RIP3 kinases. Overall, our data shed new light on the relationship between RIP1/RIP3-mediated programmed necrosis and AIF-mediated caspase-independent programmed necrosis in glioblastoma.

Subunit composition of VRAC channels determines substrate specificity and cellular resistance to Pt-based anti-cancer drugs

Although platinum‐based drugs are widely used chemotherapeutics for cancer treatment, the determinants of tumor cell responsiveness remain poorly understood. We show that the loss of subunits LRRC8A and LRRC8D of the heteromeric LRRC8 volume‐regulated anion channels (VRACs) increased resistance to clinically relevant cisplatin/carboplatin concentrations. Under isotonic conditions, about 50% of cisplatin uptake depended on LRRC8A and LRRC8D, but neither on LRRC8C nor on LRRC8E. Cell swelling strongly enhanced LRRC8‐dependent cisplatin uptake, bolstering the notion that cisplatin enters cells through VRAC. LRRC8A disruption also suppressed drug‐induced apoptosis independently from drug uptake, possibly by impairing VRAC‐dependent apoptotic cell volume decrease. Hence, by mediating cisplatin uptake and facilitating apoptosis, VRAC plays a dual role in the cellular drug response. Incorporation of the LRRC8D subunit into VRAC substantially increased its permeability for cisplatin and the cellular osmolyte taurine, indicating that LRRC8 proteins form the channel pore. Our work suggests that LRRC8D‐containing VRACs are crucial for cell volume regulation by an important organic osmolyte and may influence cisplatin/carboplatin responsiveness of tumors.

New dimension in therapeutic targeting of BCL-2 family proteins

Proteins of the BCL-2 family control the mitochondrial pathway of apoptosis. Targeting these proteins proves to be an attractive strategy for anticancer therapy. The biological context is based on the fact that BH3-only members of the family are specific antagonists of prosurvival members. This prompted the identification of "BH3 mimetic" compounds. These small peptides or organic molecules indeed mimic the BH3 domain of BH3-only proteins: by selectively binding and antagonizing prosurvival proteins, they can induce apoptosis in malignant cells. Some small-molecule inhibitors of prosurvival proteins have already entered clinical trials in cancer patients and two of them have shown significant therapeutic effects. The latest developments in the field of targeting BCL-2 family proteins highlight several new antagonists of prosurvival proteins as well as direct activators of proapoptotic proteins. These compounds open up novel prospects for the development of BH3 mimetic anticancer drugs.

A Maltose-Binding Protein Fusion Construct Yields a Robust Crystallography Platform for MCL1

Crystallization of a maltose-binding protein MCL1 fusion has yielded a robust crystallography platform that generated the first apo MCL1 crystal structure, as well as five ligand-bound structures. The ability to obtain fragment-bound structures advances structure-based drug design efforts that, despite considerable effort, had previously been intractable by crystallography. In the ligand-independent crystal form we identify inhibitor binding modes not observed in earlier crystallographic systems. This MBP-MCL1 construct dramatically improves the structural understanding of well-validated MCL1 ligands, and will likely catalyze the structure-based optimization of high affinity MCL1 inhibitors.

Control of mitochondrial integrity in ageing and disease

Various molecular and cellular pathways are active in eukaryotes to control the quality and integrity of mitochondria. These pathways are involved in keeping a 'healthy' population of this essential organelle during the lifetime of the organism. Quality control (QC) systems counteract processes that lead to organellar dysfunction manifesting as degenerative diseases and ageing. We discuss disease- and ageing-related pathways involved in mitochondrial QC: mtDNA repair and reorganization, regeneration of oxidized amino acids, refolding and degradation of severely damaged proteins, degradation of whole mitochondria by mitophagy and finally programmed cell death. The control of the integrity of mtDNA and regulation of its expression is essential to remodel single proteins as well as mitochondrial complexes that determine mitochondrial functions. The redundancy of components, such as proteases, and the hierarchies of the QC raise questions about crosstalk between systems and their precise regulation. The understanding of the underlying mechanisms on the genomic, proteomic, organellar and cellular levels holds the key for the development of interventions for mitochondrial dysfunctions, degenerative processes, ageing and age-related diseases resulting from impairments of mitochondria.

Induction of apoptosis in pancreatic cancer cells by vesicular stomatitis virus

Effective oncolytic virus (OV) therapy is dependent on the ability of replication-competent viruses to kill infected cancer cells. We previously showed that human pancreatic ductal adenocarcinoma (PDAC) cell lines are highly heterogeneous in their permissiveness to vesicular stomatitis virus (VSV), in part due to differences in type I interferon (IFN) signaling. Here, using 10 human PDAC cell lines and three different VSV recombinants (expressing ΔM51 or wild type matrix protein), we examined cellular and viral factors affecting VSV-mediated apoptosis activation in PDACs. In most cell lines, VSVs activated both extrinsic and intrinsic apoptosis pathways, and VSV-ΔM51 primarily activated the type II extrinsic pathway. In cells with defective IFN signaling, all VSV recombinants induced robust apoptosis, whereas VSV-ΔM51 was a more effective apoptosis activator in PDACs with virus-inducible IFN signaling. Three cell lines constitutively expressing high levels of IFN-stimulated genes (ISGs) were resistant to apoptosis under most experimental conditions, even when VSV replication levels were dramatically increased by Jak inhibitor I treatment. Two of these cell lines also poorly activated apoptosis when treated with Fas activating antibody, suggesting a general defect in apoptosis.

Apoptosis resistance, mitotic catastrophe, and loss of ploidy control in Burkitt lymphoma

Resistance to cell death is the major cause of chemotherapy failure in most kinds of cancers, including Burkitt lymphoma (BL). When analyzing therapy resistance in Burkitt lymphoma (BL), we discovered a link between apoptosis resistance and ploidy control. We therefore studied systematically a panel of 15 BL lines for apoptosis induction upon treatment with microtubule inhibitors and compared three types of microtubule toxins, i.e., paclitaxel, nocodazole and vincristine. We found an inverse relationship between apoptosis sensitivity and ploidy control. Thus, cells resistant to paclitaxel- or nocodazole-induced apoptosis underwent mitotic catastrophe and developed polyploidy (>4N). Mechanistically, apoptosis resistance was linked to failure of caspase activation, which was most pronounced in cells lacking the pro-apoptotic multidomain Bcl-2 homologs Bax and Bak. Pharmacological caspase inhibition promoted polyploidy upon exposure to paclitaxel and nocodazole supporting the relationship between resistance to apoptosis and polyploidization. Of note, vincristine induced persistent mitotic arrest but no loss of ploidy control. Considering targets to facilitate Bax/Bak-independent cell death and to avoid drug-induced mitotic catastrophe and consecutive mitotic catastrophe should be of great importance to overcome therapy resistance and therapy-related events that result in ploidy changes and tumor progression.

KEY MESSAGE

Inverse relation of apoptosis and polyploidy induction by paclitaxel or nocodazole in BL. Resistant cells undergo mitotic catastrophe and develop polyploidy. Lack of Bax/Bak confers resistance and leads to induction of polyploidy in BL. Intact apoptosis response protects from polyploidy as a result of mitotic catastrophe.

Design, synthesis and evaluation of marinopyrrole derivatives as selective inhibitors of Mcl-1 binding to pro-apoptotic Bim and dual Mcl-1/Bcl-xL inhibitors

Inhibition of anti-apoptotic Mcl-1 is a promising anticancer strategy to overcome the survival and chemoresistance of a broad spectrum of human cancers. We previously reported on the identification of a natural product marinopyrrole A (1) that induces apoptosis in Mcl-1-dependent cells through Mcl-1 degradation. Here, we report the design and synthesis of novel marinopyrrole-based analogs and their evaluation as selective inhibitors of Mcl-1 as well as dual Mcl-1/Bcl-xL inhibitors. The most selective Mcl-1 antagonists were 34, 36 and 37 with 16-, 13- and 9-fold more selectivity for disrupting Mcl-1/Bim over Bcl-xL/Bim binding, respectively. Among the most potent dual inhibitors is 42 which inhibited Mcl-1/Bim and Bcl-xL/Bim binding 15-fold (IC50 = 600 nM) and 33-fold (500 nM) more potently than (±)-marinopyrrole A (1), respectively. Fluorescence quenching, NMR analysis and molecular docking indicated binding of marinopyrroles to the BH3 binding site of Mcl-1. Several marinopyrroles potently decreased Mcl-1 cellular levels and induced caspase 3 activation in human breast cancer cells. Our studies provide novel "lead" marinopyrroles for further optimization as selective Mcl-1 inhibitors and dual Mcl-1 and Bcl-xL inhibitors.