Identification of novel isoforms of the BH3 domain protein Bim which directly activate Bax to trigger apoptosis

Kinase signalling adaptation supports dysfunctional mitochondria in disease

Mitochondria form a critical control nexus which are essential for maintaining correct tissue homeostasis. An increasing number of studies have identified dysregulation of mitochondria as a driver in cancer. However, which pathways support and promote this adapted mitochondrial function? A key hallmark of cancer is perturbation of kinase signalling pathways. These pathways include mitogen activated protein kinases (MAPK), lipid secondary messenger networks, cyclic-AMP-activated (cAMP)/AMP-activated kinases (AMPK), and Ca2+/calmodulin-dependent protein kinase (CaMK) networks. These signalling pathways have multiple substrates which support initiation and persistence of cancer. Many of these are involved in the regulation of mitochondrial morphology, mitochondrial apoptosis, mitochondrial calcium homeostasis, mitochondrial associated membranes (MAMs), and retrograde ROS signalling. This review will aim to both explore how kinase signalling integrates with these critical mitochondrial pathways and highlight how these systems can be usurped to support the development of disease. In addition, we will identify areas which require further investigation to fully understand the complexities of these regulatory interactions. Overall, this review will emphasize how studying the interaction between kinase signalling and mitochondria improves our understanding of mitochondrial homeostasis and can yield novel therapeutic targets to treat disease.

The nexus of long noncoding RNAs, splicing factors, alternative splicing and their modulations

The process of alternative splicing (AS) is widely deregulated in a variety of cancers. Splicing is dependent upon splicing factors. Recently, several long noncoding RNAs (lncRNAs) have been shown to regulate AS by directly/indirectly interacting with splicing factors. This review focuses on the regulation of AS by lncRNAs through their interaction with splicing factors. AS mis-regulation caused by either mutation in splicing factors or deregulated expression of splicing factors and lncRNAs has been shown to be involved in cancer development and progression, making aberrant splicing, splicing factors and lncRNA suitable targets for cancer therapy. This review also addresses some of the current approaches used to target AS, splicing factors and lncRNAs. Finally, we discuss research challenges, some of the unanswered questions in the field and provide recommendations to advance understanding of the nexus of lncRNAs, AS and splicing factors in cancer.

The Molecular Effects of Environmental Enrichment on Alzheimer's Disease

Environmental enrichment (EE) is an environmental paradigm encompassing sensory, cognitive, and physical stimulation at a heightened level. Previous studies have reported the beneficial effects of EE in the brain, particularly in the hippocampus. EE improves cognitive function as well as ameliorates depressive and anxiety-like behaviors, making it a potentially effective neuroprotective strategy against neurodegenerative diseases such as Alzheimer's disease (AD). Here, we summarize the current evidence for EE as a neuroprotective strategy as well as the potential molecular pathways that can explain the effects of EE from a biochemical perspective using animal models. The effectiveness of EE in enhancing brain activity against neurodegeneration is explored with a view to differences present in early and late life EE exposure, with its potential application in human being discussed. We discuss EE as one of the non pharmacological approaches in preventing or delaying the onset of AD for future research.

A photochemical-responsive nanoparticle boosts doxorubicin uptake to suppress breast cancer cell proliferation by apoptosis

In the course of chemotherapy for breast cancer, doxorubicin (DOX) is one of the most commonly prescribed agents. However, it has been recognized as clinically circumscribed on account of its poor selectivity and toxic reactions to normal tissues. Fortunately, the distinct merit of photochemical-responsive nanoparticle delivery systems to enhance cellular drugs uptake through localized concentration, adequate selective and minimizing systemic toxicity has aroused substantial interest recently. In this study, we synthesized photochemical-responsive nanoparticle by incorporating DOX, curcumin (CUR), and perfluorooctyl bromide (PFOB) into poly(lactic-co-glycolic acid) (PLGA) via double emulsification (DOX-CUR-PFOB-PLGA). The synthesized composite nanoparticles, which featured good ultrasound imaging, engendered photochemical activation for drug release when given laser irradiation. Cumulative release rates for DOX were 76.34%, and for CUR were 83.64%, respectively. Also, MCF-7 cells displayed significant intracellular DOX uptake and reactive oxygen species (ROS) levels, degraded cytoskeleton, and decreased cell growth and migration capacity. At the molecular level, cellular pAKT levels decreased, which resulted in downregulated HIF-1α and BAX/BCl-2 levels, leading to Caspase-3 activation and thus induction of apoptosis. Therefore, the photochemical-responsive nanoparticles possess the potential to elicit apoptosis in MCF-7 cells via enhanced DOX uptake.

Inflammatory Modulation of miR-155 Inhibits Doxorubicin-Induced Testicular Dysfunction via SIRT1/FOXO1 Pathway: Insight into the Role of Acacetin and Bacillus cereus Protease

Doxorubicin (DOX) is a chemotherapeutic agent that can disrupt testicular function leading to male infertility. This study examined the protective role of natural flavone, acacetin (ACA), and a protease of Bacillus cereus bacteria (B. cereus) as well as the potential role of miR-155/SIRT1/FOXO1 network in DOX-induced testicular injury. Twenty-four male Wistar rats were randomly allocated into four groups and treated as follows: Control, DOX (1 mg/kg, i.p) every other day for 21 days with a total dose equal to 10 mg/kg throughout the experiment, and pre-treated groups that received ACA (5 mg/kg/day, p.o) or B. cereus protease (36 mg/kg/day, p.o) for a week prior to DOX administration. DOX challenge reduced the testis weight coefficient, serum testosterone, and testicular 17β-hydroxysteroid dehydrogenase (17β-HSD). DOX caused a significant increase in testicular oxidative stress, inflammatory, and apoptotic markers. Aberrant testicular miR-34c, a germ-specific miRNA, and miR-155 expressions were observed, along with decreased protein expression of sirtuin1 (SIRT1) dependent forkhead box 1 (FOXO1) acetylation which induces apoptosis. Besides, abnormal histopathological architecture and a marked reduction in the testicular expression of proliferating cell nuclear antigen (PCNA) were observed. ACA or protease administration significantly improved the histopathological and immunohistochemical pictures compared with DOX alone and renovated testicular functions. Interestingly, treatment with protease was more significant than treatment with ACA in ameliorating DOX-induced testicular injury. Taken together, this study reveals the prophylactic role of these two regimens on male fertility by exhibiting antioxidant, anti-inflammatory, and anti-apoptotic effects against DOX-elicited testicular damage, possibly via modulating miR-155/SIRT1/FOXO1 network.

BidSi6 and BidEL isoforms as a potential marker for predicting colorectal adenomatous polyps

Background

As a well-known protein, Bid links the extrinsic and intrinsic apoptotic pathways and plays important roles in cell proliferation. In this study, we evaluated the expression of two isoforms of the Bid gene (BidSi6 and BidEL) in colorectal adenomatous polyps as a biomarker and investigated the relationship between their expression levels with clinicopathological factors.

Methods

The expression of BidSi6 and BidEL isoforms in 22 pairs of Adenomatous polyps and adjust non-polyp tissues was measured by qReal-Time PCR and compared with 10 normal colon tissues. ROC curve was performed to examine the diagnostic capacity. Also, sequencing was performed for molecular identification of BidSi6 isoform in adenomatous polyp.

Results

Our results showed that BidSi6 and BidEL isoforms were significantly overexpressed in Adenomatous polyps and non-polyp adjacent tissues from the same patients compared to that in normal colon tissues, but there was no significant expression between polyps and adjust non-polyp tissues. There were no significant correlations between the expression of two isoforms and other features of clinicopathology. The area under the curve of BidSi6 and BidEL isoforms indicated powerful diagnostic capability. The phylogenetic tree was constructed based on the sequence of idSi6 isoform, and the results showed that adenomatous polyp tissue and adjust non-polyp tissue were separated from healthy colorectal tissue and reference sequence (EU678292).

Conclusions

These findings suggest that BidSi6 and BidEL isoforms can be used as new potential biomarkers in adenomatous polyps.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01282-0.

What can we learn from mice lacking pro-survival BCL-2 proteins to advance BH3 mimetic drugs for cancer therapy?

In many human cancers the control of apoptosis is dysregulated, for instance as a result of the overexpression of pro-survival BCL-2 proteins. This promotes tumorigenesis by protecting nascent neoplastic cells from stress and renders malignant cells resistant to anti-cancer agents. Therefore, several BH3 mimetic drugs targeting distinct pro-survival proteins have been developed. The BCL-2 inhibitor Venetoclax/ABT-199, has been approved for treatment of certain blood cancers and tens of thousands of patients have already been treated effectively with this drug. To advance the clinical development of MCL-1 and BCL-XL inhibitors, a more detailed understanding of their distinct and overlapping roles in the survival of malignant as well as non-transformed cells in healthy tissues is required. Here, we discuss similarities and differences in pro-survival BCL-2 protein structure, subcellular localisation and binding affinities to the pro-apoptotic BCL-2 family members. We summarise the findings from gene-targeting studies in mice to discuss the specific roles of distinct pro-survival BCL-2 family members during embryogenesis and the survival of non-transformed cells in healthy tissues in adults. Finally, we elaborate how these findings align with or differ from the observations from the clinical development and use of BH3 mimetic drugs targeting different pro-survival BCL-2 proteins.

Overcoming Steroid Resistance in Pediatric Acute Lymphoblastic Leukemia-The State-of-the-Art Knowledge and Future Prospects

Acute lymphoblastic leukemia (ALL) is the most common malignancy among children. Despite the enormous progress in ALL therapy, resulting in achieving a 5-year survival rate of up to 90%, the ambitious goal of reaching a 100% survival rate is still being pursued. A typical ALL treatment includes three phases: remission induction and consolidation and maintenance, preceded by a prednisone prephase. Poor prednisone response (PPR) is defined as the presence of ≥1.0 × 10⁹ blasts/L in the peripheral blood on day eight of therapy and results in significantly frequent relapses and worse outcomes. Hence, identifying risk factors of steroid resistance and finding methods of overcoming that resistance may significantly improve patients' outcomes. A mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK-ERK) pathway seems to be a particularly attractive target, as its activation leads to steroid resistance via a phosphorylating Bcl-2-interacting mediator of cell death (BIM), which is crucial in the steroid-induced cell death. Several mutations causing activation of MAPK-ERK were discovered, notably the interleukin-7 receptor (IL-7R) pathway mutations in T-cell ALL and rat sarcoma virus (Ras) pathway mutations in precursor B-cell ALL. MAPK-ERK pathway inhibitors were demonstrated to enhance the results of dexamethasone therapy in preclinical ALL studies. This report summarizes steroids' mechanism of action, resistance to treatment, and prospects of steroids therapy in pediatric ALL.

Understanding Suboptimal Response to Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs), as a novel class of anticancer therapy, can be more efficacious and less toxic than chemotherapy, but their clinical success is confined to certain tumor types. Elucidating their targets, mechanisms and scope of action, and potential synergism with chemotherapy and/or targeted therapies are critical to widen their clinical indications. Treatment response to an ICI targeting programmed death-1 (anti-PD-1) is sought to be understood here by conducting a preplanned correlative analysis of a phase II clinical trial in patients with small bowel adenocarcinoma (SBA). The cytolytic capacity of circulating immune cells in cancer patients using a novel ex vivo cytotoxicity assay is evaluated, and the utility of circulating biomarkers is investigated to predict and monitor the treatment effect of anti-PD-1. Baseline expression of Bim and NKG7 and upregulation of CX3CR1 in circulating T cells are associated with the clinical benefit of anti-PD-1 in patients with SBA. Overall, these findings suggest that the frequency and cytolytic capacity of circulating, effector immune cells may differentiate clinical response to ICIs, providing a strong rationale to support immune monitoring using patient peripheral blood.

Toxicological aspect of bioinsecticide pyrethrum extract and expressions of apoptotic gene levels in human hepotacellular carcinoma HepG2 cells

Pyrethrum extract (PE), an important natural bioinsecticide, is extensively used across the world to control pest insects in homes and farms. The aim of this study was to evaluate the potential cytotoxic effect of PE using MTT assay and genotoxic effect using micronucleus (MN) assay. The changes in the expressions of the apoptosis genes in mRNA levels were also investigated using Real Time qPCR analysis as well as the ratio of apoptotic/necrotic cells with AnnexinV-FITC/Propidium iodide (PI) assay in HepG2 cells. PE markedly suppressed the cell proliferation on HepG2 cells. It significantly increased the frequency of micronucleus (MN) at 500 and 1000 µg/mL. PE also induced the percentage of cell population of late apoptotic/necrotic cells (FITC + PI+) and necrotic cells (FITC- PI+) especially at 4000 μg/mL analyzed by flow cytometry. PE caused significant fold changes in the expression of several apoptotic genes including APAF1, BIK, BAX, BAD, BİD, MCL-1, CASP3, CASP1, CASP2, FAS, FADD and TNFRSF1A. In particularly, the pro-apoptotic gene Hrk (Harakiri) remarkably and dose-dependently was overexpressed of the mRNA level. As a result, PE may exhibit cyto-genotoxic effects especially at higher concentrations and lead to significant changes in the expression of mRNA levels in several apoptotic genes.Highlights [Database][Mismatch]Natural bioinsecticide PE exhibited cytotoxic effect in HepG2 cells.PE significantly induced the micronucleus (MN) frequency at 500 and 1000 µg/mL.This bioinsecticide induced cell death and it lead to significant fold changes in the expression of mRNA levels in several apoptotic genes in HepG2 cells.The highest increase of the expression of mRNA levels was determined in Hrk (Harakiri) at 4000 µg/mL.

Glycerophosphoinositol Promotes Apoptosis of Chronic Lymphocytic Leukemia Cells by Enhancing Bax Expression and Activation

An imbalance in the expression of pro- and anti-apoptotic members of the Bcl-2 family of apoptosis-regulating proteins is one of the main biological features of CLL, highlighting these proteins as therapeutic targets for treatment of this malignancy. Indeed, the Bcl-2 inhibitor Venetoclax is currently used for both first-line treatment and treatment of relapsed or refractory CLL. An alternative avenue is the transcriptional modulation of Bcl-2 family members to tilt their balance towards apoptosis. Glycerophosphoinositol (GroPIns) is a biomolecule generated from membrane phosphoinositides by the enzymes phospholipase A2 and lysolipase that pleiotropically affects key cellular functions. Mass-spectrometry analysis of GroPIns interactors recently highlighted the ability of GroPIns to bind to the non-receptor tyrosine phosphatase SHP-1, a known promoter of Bax expression, suggesting that GroPIns might correct the Bax expression defect in CLL cells, thereby promoting their apoptotic demise. To test this hypothesis, we cultured CLL cells in the presence of GroPIns, alone or in combination with drugs commonly used for treatment of CLL. We found that GroPIns alone increases Bax expression and apoptosis in CLL cells and enhances the pro-apoptotic activity of drugs used for CLL treatment in a SHP-1 dependent manner. Interestingly, among GroPIns interactors we found Bax itself. Short-term treatments of CLL cells with GroPIns induce Bax activation and translocation to the mitochondria. Moreover, GroPIns enhances the pro-apoptotic activity of Venetoclax and Fludarabine in CLL cells. These data provide evidence that GroPIns exploits two different pathways converging on Bax to promote apoptosis of leukemic cells and pave the way to new studies aimed at testing GroPIns in combination therapies for the treatment of CLL.

Codon Usage Analysis of Pro-Apoptotic Bim Gene Isoforms

Background: Bim is a Bcl-2 homology 3 (BH3)-only proteins, a group of pro-apoptotic proteins involved in physiological and pathological conditions. Both the overexpression and under-expression of Bim protein are associated with the diseased condition, and various isoforms of Bim protein are present with differential apoptotic potential. Objective: The present study attempted to envisage the association of various molecular signatures with the codon choices of Bim isoforms. Methods: Molecular signatures like composition, codon usage, nucleotide skews, the free energy of mRNA transcript, physical properties of proteins, codon adaptation index, relative synonymous codon usage, and dinucleotide odds ratio were determined and analyzed for their associations with codon choices of Bim gene. Results: Skew analysis of the Bim gene indicated the preference of C nucleotide over G, A, and T and preference of G over T and A nucleotides was observed. An increase in C content at the first and third codon position increased gene expression while it decreased at the second codon position. Compositional constraints on nucleotide C at all three codon positions affected gene expression. The analysis revealed an exceptionally high usage of CpC dinucleotide in all the envisaged 31 isoforms of Bim. We correlated it with the requirement of rapid demethylation machinery to fine-tune the Bimgene expression. Also, mutational pressure played a dominant role in shaping codon usage bias in Bim isoforms. Conclusion: An exceptionally high usage of CpC dinucleotide in all the envisaged 31 isoforms of Bim indicates a high order selectional force to fine tune Bim gene expression.

Systems biology under heat stress in Indian cattle

Transcriptome profiling of Vrindavani and Tharparkar cattle (n = 5 each) revealed that more numbers of genes were dysregulated in Vrindavani than in Tharparkar. A contrast in gene expression was observed with 18.9 % of upregulated genes in Vrindavani downregulated in Tharparkar and 17.8% upregulated genes in Tharparkar downregulated in Vrindavani. Functional annotation of genes differentially expressed in Tharparkar and Vrindavani revealed that the systems biology in Tharparkar is moving towards counteracting the effects due to heat stress. Unlike Vrindavani, Tharparkar is not only endowed with higher expression of the scavengers (UBE2G1, UBE2S, and UBE2H) of misfolded proteins but also with protectors (VCP, Serp1, and CALR) of naïve unfolded proteins. Further, higher expression of the antioxidants in Tharparkar enables it to cope up with higher levels of free radicals generated as a result of heat stress. In this study, we found relevant genes dysregulated in Tharparkar in the direction that can counter heat stress.

Verticillin A increases the BIMEL/MCL-1 ratio to overcome ABT-737-resistance in human colon cancer cells by targeting the MEK/ERK pathway

ABT-737, a small molecule BH-3 mimetic, is less effective against human colon cancers due to its resistance. Verticillin A is a natural compound, which was previously purified from verticillium-infected mushrooms. Hence, we aimed at overcoming the ABT737 resistance observed in CRC tumors by combining Verticillin A with ABT-737 and figuring out the potential mechanism. In this study, we observed that Verticillin A could sensitize colon cancer to ABT-737-induced cell death through induction of mitochondrial-dependent apoptosis. Verticillin A could significantly increase the BIMEL/MCL-1 ratio to overcome ABT737 resistance through the suppression of the MEK/ERK pathway. In addition, up-regulation of BIM protein levels to activate BAX translocation results in apoptosis induction. Altogether, our work suggested the potential application of Verticillin A as a MEK inhibitor in BH3-mimetic-based therapy.

Contribution of Yeast Studies to the Understanding of BCL-2 Family Intracellular Trafficking

BCL-2 family members are major regulators of apoptotic cell death in mammals. They form an intricate regulatory network that ultimately regulates the release of apoptogenic factors from mitochondria to the cytosol. The ectopic expression of mammalian BCL-2 family members in the yeast Saccharomyces cerevisiae, which lacks BCL-2 homologs, has been long established as a useful addition to the available models to study their function and regulation. In yeast, individual proteins can be studied independently from the whole interaction network, thus providing insight into the molecular mechanisms underlying their function in a living context. Furthermore, one can take advantage of the powerful tools available in yeast to probe intracellular trafficking processes such as mitochondrial sorting and interactions/exchanges between mitochondria and other compartments, such as the endoplasmic reticulum that are largely conserved between yeast and mammals. Yeast molecular genetics thus allows the investigation of the role of these processes on the dynamic equilibrium of BCL-2 family members between mitochondria and extramitochondrial compartments. Here we propose a model of dynamic regulation of BCL-2 family member localization, based on available evidence from ectopic expression in yeast.

SPZ1 promotes deregulation of Bim to boost apoptosis resistance in colorectal cancer

Colorectal cancer (CRC) is the third most common malignancies in adults. Similar to other solid tumors, CRC cells show increased proliferation and suppressed apoptosis during the development and progression of the disease. Previous studies have shown that a novel tumor oncogene, spermatogenic basic helix-loop-helix transcription factor zip 1 (SPZ1), can promote proliferation. However, it is unclear whether SPZ1 plays a role in suppressing apoptosis, and the molecular mechanism behind SPZ1's suppression of apoptosis in CRC remains unclear. Here, we found that silencing endogenous SPZ1 inhibits cell growth and induces apoptosis, and overexpression of SPZ1 promotes cell growth. These findings were corroborated by in vitro and in vivo studies. Interestingly, SPZ1 overexpressing cells were resistant to 5-fluorouracil, a drug commonly used to treat cancer. Moreover, knocking down SPZ1 led to the activation of caspase through the deregulation of Bim by ERK1/2, we found that CRC tissues had significantly higher SPZ1 and lower Bim expression, and SPZ1HBimL were associated with advanced clinical stage of CRC. Collectively, our findings demonstrate that SPZ1 contributes to tumor progression by limiting apoptosis. SPZ1 reduces apoptosis by altering the stability of Bim, suggesting SPZ1 may serve as a biomarker and therapeutic target for CRC.

Long Non-coding RNAs (lncRNAs), A New Target in Stroke

Stroke has become the most disabling and the second most fatal disease in the world. It has been a top priority to reveal the pathophysiology of stroke at cellular and molecular levels. A large number of long non-coding RNAs (lncRNAs) are identified to be abnormally expressed after stroke. Here, we summarize 35 lncRNAs associated with stroke, and clarify their functions on the prognosis through signal transduction and predictive values as biomarkers. Changes in the expression of these lncRNAs mediate a wide range of pathological processes in stroke, including apoptosis, inflammation, angiogenesis, and autophagy. Based on the exploration of the functions and mechanisms of lncRNAs in stroke, more timely, accurate predictions and more effective, safer treatments for stroke could be developed.

Kinetic Heterogeneity of Cancer Cell Fractional Killing

Lethal drugs can induce incomplete cell death in a population of cancer cells, a phenomenon referred to as fractional killing. Here, we show that high-throughput population-level time-lapse imaging can be used to quantify fractional killing in response to hundreds of different drug treatments in parallel. We find that stable intermediate levels of fractional killing are uncommon, with many drug treatments resulting in complete or near-complete eradication of all cells, if given enough time. The kinetics of fractional killing over time vary substantially as a function of drug, drug dose, and genetic background. At the molecular level, the antiapoptotic protein MCL1 is an important determinant of the kinetics of fractional killing in response to MAPK pathway inhibitors but not other lethal stimuli. These studies suggest that fractional killing is governed by diverse lethal stimulus-specific mechanisms.

Bax functions as coelomocyte apoptosis regulator in the sea cucumber Apostichopus japonicus

Bcl-2-associated X (Bax) belongs to the Bcl-2 protein family and its pro-apoptotic function has been confirmed in many vertebrate species. However, the functional role of Bax in apoptosis in invertebrates is limited. Here, a Bax homologue (AjBax) in Apostichopus japonicas was cloned and characterized, and its pro-apoptotic function explored. In healthy sea cucumbers, AjBax was expressed in coelomocyte with the highest levels. AjBax mRNA and protein levels were significantly induced in coelomocytes post Vibrio splendidus challenge in vivo and LPS-exposed in vitro. Moreover, siRNA-mediated AjBax knockdown in coelomocyte significantly decreased AjBax mRNA and protein levels as well as the apoptosis levels of coelomocyte. Furthermore, AjBax protein levels and coelomocyte apoptosis levels could be partially recovered to their original levels after supplementation with recombinant AjBax. Our results support that AjBax has a similar function to Bax proteins in vertebrates and that it may serve as a pro-apoptotic regulator in sea cucumbers.

Extract of Lactobacillus plantarum strain 06CC2 induces JNK/p38 MAPK pathway-mediated apoptosis through endoplasmic reticulum stress in Caco2 colorectal cancer cells

Colorectal cancer is a multi-factorial disease involving genetic, environmental and lifestyle risk factors. In recent years, many changes in the bacterial composition of the intestinal microflora have been reported in colorectal cancer, suggesting the involvement of the intestinal microflora in the development and progression of colorectal cancer. Along with these reports, research on lactic acid bacteria that have a beneficial effect on the human body for the purpose of improving the intestinal environment and treating intestinal diseases has advanced. Among these studies, biogenics (defined as a component derived from lactic acid bacteria that acts directly on diseases regardless of the state of intestinal microflora) is a recent concept derived from the work on probiotics. Based on this concept, it is important to evaluate the effectiveness of various components derived from lactic acid bacteria in the treatment to diseases from and apply them in prevention and treatment. In this study, we investigated the antitumor effect of an extract obtained from Lactobacillus plantarum strain 06CC2 on colorectal cancer cells. In in vitro experiments, the extract derived from Lactobacillus plantarum 06CC2 significantly suppressed the proliferation of Caco2 colorectal cancer cells in comparison to control and non-cancer cells. Furthermore, we found that endoplasmic reticulum stress and the JNK/p38 MAPK signaling system are involved in the induction of apoptosis. These findings indicate the direct antitumor effect of the Lactobacillus plantarum 06CC2 extract on Caco2 colorectal cancer cells, and that this extract may have potential application as a biogenics.

•

An extract of Lactobacillus plantarum strain 06CC2 (LP06CC2) significantly suppressed colorectal cancer cell proliferation.

•

LP06CC2 induced mitochondrial-mediated apoptosis in Caco2 colorectal cancer cells.

•

LP06CC2 activated JNK/p38 MAPK signaling via endoplasmic reticulum stress.

Emerging targets in cancer drug resistance

Drug resistance is a complex phenomenon that frequently develops as a failure to chemotherapy during cancer treatment. Malignant cells increasingly generate resistance to various chemotherapeutic drugs through distinct mechanisms and pathways. Understanding the molecular mechanisms involved in drug resistance remains an important area of research for identification of precise targets and drug discovery to improve therapeutic outcomes. This review highlights the role of some recent emerging targets and pathways which play critical role in driving drug resistance.

DNA methylation and chromatin modifiers in colorectal cancer

Colorectal carcinogenesis is a multistep process involving the accumulation of genetic alterations over time that ultimately leads to disease progression and metastasis. Binding of transcription factors to gene promoter regions alone cannot explain the complex regulation pattern of gene expression during this process. It is the chromatin structure that allows for a high grade of regulatory flexibility for gene expression. Posttranslational modifications on histone proteins such as acetylation, methylation, or phosphorylation determine the accessibility of transcription factors to DNA. DNA methylation, a chemical modification of DNA that modulates chromatin structure and gene transcription acts in concert with these chromatin conformation alterations. Another epigenetic mechanism regulating gene expression is represented by small non-coding RNAs. Only very recently epigenetic alterations have been included in molecular subtype classification of colorectal cancer (CRC). In this chapter, we will provide examples of the different epigenetic players, focus on their role for epithelial-mesenchymal transition and metastatic processes and discuss their prognostic value in CRC.

Erianin, a novel dibenzyl compound in Dendrobium extract, inhibits bladder cancer cell growth via the mitochondrial apoptosis and JNK pathways

Erianin, a component extracted from the traditional Chinese herbal medicine Dendrobium, has shown significant anti-tumour activity in various cancers but not in bladder cancer. In this study, we assessed the effects of Erianin on bladder cancer growth and elucidated the related mechanisms. First, Erianin was synthesized with high yields, and markedly suppressed EJ and T24 cell proliferation. It induced G2/M-phase arrest in vitro. Furthermore, Erianin triggered apoptosis via caspase cascades activation and the mitochondrial-mediated apoptotic pathway. Bim up-regulation and Bcl-2 down-regulation as the symbol of apoptosis which were found to play the dominant role in the effects of Erianin. We further showed that JNK pathway activation is necessary for the Erianin-mediated anti-proliferation and apoptotic response. Finally, Erianin exhibited anti-tumour activity and induced apoptosis in tumour tissue in vivo. Collectively, these results suggest that Erianin induced cell cycle G2/M-phase arrest and apoptosis via the JNK signalling pathway in bladder cancer, indicating the potential usefulness of Erianin for the therapy of bladder cancer.

Synthesis and biological evaluation of N-biphenyl-nicotinic based moiety compounds: A new class of antimitotic agents for the treatment of Hodgkin Lymphoma

We previously demonstrated that some N-biphenylanilides caused cell-cycle arrest at G2/M transition in breast cancer cells. Among them we choose three derivatives, namely PTA34, PTA73 and RS35 for experimentation in solid tumor cell lines, classical Hodgkin Lymphoma (cHL) cell lines and bona fide normal cell lines. Almost all tumor cells were sensitive to compounds in the nanomolar range whereas, they were not cytotoxic to normal ones. Interestingly the compounds caused a strong G2/M phase arrest in cHL cell lines, thus, here we investigated whether they affected the integrity of microtubules in such cells. We found that they induced a long prometaphase arrest, followed by induction of apoptosis which involved mitochondria. PTA73 and RS35 induced the mitotic arrest through the fragmentation of microtubules which prevented the kinethocore-mitotic spindle interaction and the exit from mitosis. PTA34 is instead a tubulin-targeting agent because it inhibited the tubulin polymerization as vinblastine. As such, PTA34 maintained the Cyclin B1-CDK1 regulatory complex activated during the G2/M arrest while inducing the inactivation of Bcl-2 through phosphorylation in Ser70, the degradation of Mcl-1 and a strong activation of BIML and BIMS proapoptotic isoforms. In addition PTA34 exerted an antiangiogenic effect by suppressing microvascular formation.

Sab concentrations indicate chemotherapeutic susceptibility in ovarian cancer cell lines

The occurrence of chemotherapy-resistant tumors makes ovarian cancer (OC) the most lethal gynecological malignancy. While many factors may contribute to chemoresistance, the mechanisms responsible for regulating tumor vulnerability are under investigation. Our analysis of gene expression data revealed that Sab, a mitochondrial outer membrane (MOM) scaffold protein, was down-regulated in OC patients. Sab-mediated signaling induces cell death, suggesting that this apoptotic pathway is diminished in OC. We examined Sab expression in a panel of OC cell lines and found that the magnitude of Sab expression correlated to chemo-responsiveness; wherein, OC cells with low Sab levels were chemoresistant. The Sab levels were reflected by a corresponding amount of stress-induced c-Jun N-terminal kinase (JNK) on the MOM. BH3 profiling and examination of Bcl-2 and BH3-only protein concentrations revealed that cells with high Sab concentrations were primed for apoptosis, as determined by the decrease in pro-survival Bcl-2 proteins and an increase in pro-apoptotic BH3-only proteins on mitochondria. Furthermore, overexpression of Sab in chemoresistant cells enhanced apoptotic priming and restored cellular vulnerability to a combination treatment of cisplatin and paclitaxel. Contrariwise, inhibiting Sab-mediated signaling or silencing Sab expression in a chemosensitive cell line resulted in decreased apoptotic priming and increased resistance. The effects of silencing on Sab on the resistance to chemotherapeutic agents were emulated by the silencing or inhibition of JNK, which could be attributed to changes in Bcl-2 protein concentrations induced by sub-chronic JNK inhibition. We propose that Sab may be a prognostic biomarker to discern personalized treatments for OC patients.

Senescence marker protein 30 protects intestinal epithelial cells against inflammation-induced cell death by enhancing Nrf2 activity

Senescence marker protein 30 (SMP30) is a calcium-binding protein whose expression decreases during senescence. SMP30 deficiency increases susceptibility to cytokine-induced apoptosis in the liver and to radiation-induced apoptosis in the small intestine. Furthermore, colonic epithelial cell death is associated with the severity of colitis. Therefore, in the present study, we investigated the function of SMP30 during intestinal inflammation. In SMP30 deficient mice, colitis was significantly exacerbated as demonstrated by increased mortality (p = 0.001), body weight loss (p = 0.0105 at day 8), rectal bleeding (p = 0.0047 at day 8) and diarrhea (p = 0.0030 at day 8), histological scores (ulcers, p = 0.0002; edema, p = 0.0125; leukocyte infiltration, p = 0.0016) and productions of pro-inflammatory cytokines (IL-1α, p = 0.0452; IL-6, p = 0.0074; G-CSF, p = 0.0036). In addition, greater proportions of apoptotic cells and lower levels of anti-apoptotic marker proteins (total PARP-1 and Bcl-2) were observed in the inflamed intestines of SMP30 deficient mice than in wild type controls. In vitro experiments on colonic epithelial cells showed that stable SMP30 expression inhibited but that SMP30 siRNA expression increased TNF-α-induced apoptosis. SMP30 inhibition decreased Nrf2 mRNA expression levels (p < 0.0001), but SMP30 overexpression increased Nrf2 mRNA expression levels (p = 0.0495). The underlying mechanism by which SMP30 protected cells appeared to be by inhibiting Nrf2 ubiquitination and Keap1 expression, and thus enhancing Nrf2 activity. Moreover, SMP30 deficiency increased the incidence of colitis-associated colon cancer as determined by increased mortality (p = 0.0572) and average polyp number (p = 0.0277). Collectively, these findings suggest that SMP30 protects intestinal epithelial cells from apoptosis and this can contribute to amelioration of colitis and colitis-associated colon cancer.

Efficacy of an HSP90 inhibitor, ganetespib, in preclinical thyroid cancer models

Heat shock protein 90 is a molecular chaperon that maintains the correct folding and function of multiple client proteins. The inhibition of heat shock protein 90, which leads to the simultaneous degradation of multiple proteins involved in oncogenic signaling pathways, has revealed an innovative strategy to treat a variety of cancer types. We evaluated the therapeutic effects of ganetespib, a heat shock protein 90 inhibitor, in treating thyroid cancer. Ganetespib effectively inhibited cell proliferation in a dose-dependent manner in eight cell lines originating from four major histologic types of thyroid cancer (papillary, follicular, anaplastic and medullary). Ganetespib decreased cyclin-dependent kinase 1 and arrested cell cycle progression in G2/M phase. The expression of proteins involved in RAS/RAF/ERK and PI3K/AKT/mTOR signaling pathways was also inhibited. The RET level was decreased in a medullary thyroid cancer cell line. Ganetespib increased Bim expression, activated caspase-3 and induced apoptosis. In vivo, ganetespib retarded the tumor growth of anaplastic and medullary thyroid cancer xenografts with acceptable safety profiles. These findings indicate that ganetespib has potential in the treatment of patients with thyroid cancer.

Erythropoietin drives breast cancer progression by activation of its receptor EPOR

Breast cancer is a leading cause of cancer-related deaths. Anemia is common in breast cancer patients and can be treated with blood transfusions or with recombinant erythropoietin (EPO) to stimulate red blood cell production. Clinical studies have indicated decreased survival in some groups of cancer patients treated with EPO. Numerous tumor cells express the EPO receptor (EPOR), posing a risk that EPO treatment would enhance tumor growth, but the mechanisms involved in breast tumor progression are poorly understood.

Here, we have examined the functional role of the EPO-EPOR axis in pre-clinical models of breast cancer. EPO induced the activation of PI3K/AKT and MAPK pathways in human breast cancer cell lines. EPOR knockdown abrogated human tumor cell growth, induced apoptosis through Bim, reduced invasiveness, and caused downregulation of MYC expression. EPO-induced MYC expression is mediated through the PI3K/AKT and MAPK pathways, and overexpression of MYC partially rescued loss of cell proliferation caused by EPOR downregulation. In a xenotransplantation model, designed to simulate recombinant EPO therapy in breast cancer patients, knockdown of EPOR markedly reduced tumor growth.

Thus, our experiments in vitro and in vivo demonstrate that functional EPOR signaling is essential for the tumor-promoting effects of EPO and underline the importance of the EPO-EPOR axis in breast tumor progression.

Upregulation of SIRT1 inhibits H2O2‑induced osteoblast apoptosis via FoxO1/β‑catenin pathway

Osteoporosis is a disease that significantly influences life expectancy and quality in humans. Oxidative stress may stimulate bone marrow osteoclast differentiation and inhibit osteoblast (OB) differentiation. OB proliferation and differentiation are affected by the forkhead box O (FoxO)1/β‑catenin signaling pathway. The osteogenic differentiation of mesenchymal stem cells (MSCs) may be promoted by silent information regulator type‑1 [sirtuin (SIRT)1]. However, the molecular mechanism of SIRT1 regulation of osteogenic differentiation of MSCs remains unclear, and further elucidation is needed. The present study investigated the role of SIRT1 in the FoxO1/β‑catenin signaling pathway in oxidative stress and its mechanism in the osteoblastic progenitor cell line (MC3T3‑E1). The results demonstrated that OB apoptosis and elevated oxidative stress in cells were simulated by H2O2, which was inhibited by moderate SIRT1 overexpression through reducing the oxidative stress. Further studies revealed that FOXO1 and β‑catenin pathway activity was downregulated by SIRT1 and eventually resulted in inhibition of target genes, including the proapoptotic gene B cell lymphoma‑2 interacting mediator of cell death, DNA repair gene growth arrest and DNA damage inducible protein 45 and the OB differentiation suppressor gene peroxisome proliferator activated receptor (PPAR)‑γ. Furthermore, β‑catenin and PPAR‑γ were inhibited by SIRT1. Overall, the results of the present study suggest that moderate overexpression of SIRT1 (~3‑fold of normal level) may directly or indirectly inhibit apoptosis of OBs via the FOXO1 and β‑catenin signaling pathway.

SRp55 Regulates a Splicing Network That Controls Human Pancreatic β-Cell Function and Survival

Progressive failure of insulin-producing β-cells is the central event leading to diabetes, but the signaling networks controlling β-cell fate remain poorly understood. Here we show that SRp55, a splicing factor regulated by the diabetes susceptibility gene GLIS3, has a major role in maintaining the function and survival of human β-cells. RNA sequencing analysis revealed that SRp55 regulates the splicing of genes involved in cell survival and death, insulin secretion, and c-Jun N-terminal kinase (JNK) signaling. In particular, SRp55-mediated splicing changes modulate the function of the proapoptotic proteins BIM and BAX, JNK signaling, and endoplasmic reticulum stress, explaining why SRp55 depletion triggers β-cell apoptosis. Furthermore, SRp55 depletion inhibits β-cell mitochondrial function, explaining the observed decrease in insulin release. These data unveil a novel layer of regulation of human β-cell function and survival, namely alternative splicing modulated by key splicing regulators such as SRp55, that may cross talk with candidate genes for diabetes.

Role of microRNAs in the resistance of colorectal cancer to chemoradiotherapy

Colorectal cancer (CRC) is among the main tumor-related causes of death worldwide. The fact that the majority of the patients develop resistance to chemoradiotherapy (CRT) is a major obstacle for the treatment of CRC. In order to develop more effective treatment strategies, it is crucial to elucidate the mechanisms underlying the development of resistance to CRT. Several studies have recently indicated the regulatory effects of microRNAs (miRNAs) in response to antitumor agents. For example, miR-34a attenuates the chemoresistance of colon cancer to 5-FU by inhibiting E2F3 and SIRT1. The miR-34a mimic MRX34 is the first synthetic miRNA to have been entered into clinical trials. miR-21 prevents tumor cell stemness, invasion and drug resistance, which are required for the development of CRC. These findings suggest that miRNAs represent a focus in the research of novel cancer treatments aimed at sensitizing cancer cells to chemotherapeutic drugs. The aim of the present study was to review the functions of miRNAs and investigate the roles of miRNAs in CRC radioresistance or chemoresistance. Furthermore, the potential of including miRNAs in therapeutic strategies and using them as molecular biomarkers for predicting radiosensitivity and chemosensitivity was discussed.

N-terminal acetylation modulates Bax targeting to mitochondria

The pro-apoptotic Bax protein is the main effector of mitochondrial permeabilization during apoptosis. Bax is controlled at several levels, including post-translational modifications such as phosphorylation and S-palmitoylation. However, little is known about the contribution of other protein modifications to Bax activity. Here, we used heterologous expression of human Bax in yeast to study the involvement of N-terminal acetylation by yNaa20p (yNatB) on Bax function. We found that human Bax is N-terminal (Nt-)acetylated by yNaa20p and that Nt-acetylation of Bax is essential to maintain Bax in an inactive conformation in the cytosol of yeast and Mouse Embryonic Fibroblast (MEF) cells. Bax accumulates in the mitochondria of yeast naa20Δ and Naa25^-/- MEF cells, but does not promote cytochrome c release, suggesting that an additional step is required for full activation of Bax. Altogether, our results show that Bax N-terminal acetylation by NatB is involved in its mitochondrial targeting.

JNK-signaling: A multiplexing hub in programmed cell death

Jun N-terminal kinases or JNKs have been shown to be involved in a wide array of signaling events underlying tumorigenesis and tumor progression. Through its interaction with a diverse set of signaling proteins and adaptors, JNKs regulate cell proliferation, invasive migration, therapy resistance, and programmed cell death. JNKs have been shown to play a role in apoptotic as well as non-apoptotic programmed cell death mechanisms including those of necroptosis, ferroptosis, pyroptosis, and autophagy. Most of the tumorigenic regulatory functions of JNKs can be related to their ability to module cell death via these programmed cell death mechanisms. JNKs stimulate or inhibit cell death in a context-dependent manner by stimulating the expression of specific genes as well as by modulating the activities of pro- and anti-apoptotic proteins through distinct phosphorylation events. This review summarizes our current understanding of the role of JNK in programmed cell death and its impact on cancer growth, progression, and therapy.

BH3-only protein BIM: An emerging target in chemotherapy

BH3-only proteins constitute major proportion of pro-apoptotic members of B-cell lymphoma 2 (Bcl-2) family of apoptotic regulatory proteins and participate in embryonic development, tissue homeostasis and immunity. Absence of BH3-only proteins contributes to autoimmune disorders and tumorigenesis. Bim (Bcl-2 Interacting Mediator of cell death), most important member of BH3-only proteins, shares a BH3-only domain (9-16 aa) among 4 domains (BH1-BH4) of Bcl-2 family proteins and highly pro-apoptotic in nature. Bim initiates the intrinsic apoptotic pathway under both physiological and patho-physiological conditions. Reduction in Bim expression was found to be associated with tumor promotion and autoimmunity, while overexpression inhibited tumor growth and drug resistance as cancer cells suppress Bim expression and stability. Apart from its role in normal homeostasis, Bim has emerged as a central player in regulation of tumorigenesis, therefore gaining attention as a plausible target for chemotherapy. Regulation of Bim expression and stability is complicated and regulated at multiple levels viz. transcriptional, post-transcriptional, post-translational (preferably by phosphorylation and ubiquitination), epigenetic (by promoter acetylation or methylation) including miRNAs. Furthermore, control over Bim expression and stability may be exploited to enhance chemotherapeutic efficacy, overcome drug resistance and select anticancer drug regimen as various chemotherapeutic agents exploit Bim as an executioner of cell death. Owing to its potent anti-tumorigenic activity many BH3 mimetics e.g. ABT-737, ABT-263, obatoclax, AT-101and A-1210477 have been developed and entered in clinical trials. It is more likely that in near future strategies commanding Bim expression and stability ultimately lead to Bim based therapeutic regimen for cancer treatment.

A dynamical framework for complex fractional killing

When chemotherapy drugs are applied to tumor cells with the same or similar genotypes, some cells are killed, while others survive. This fractional killing contributes to drug resistance in cancer. Through an incoherent feedforward loop, chemotherapy drugs not only activate p53 to induce cell death, but also promote the expression of apoptosis inhibitors which inhibit cell death. Consequently, cells in which p53 is activated early undergo apoptosis while cells in which p53 is activated late survive. The incoherent feedforward loop and the essential role of p53 activation timing makes fractional killing a complex dynamical challenge, which is hard to understand with intuition alone. To better understand this process, we have constructed a representative model by integrating the control of apoptosis with the relevant signaling pathways. After the model was trained to recapture the observed properties of fractional killing, it was analyzed with nonlinear dynamical tools. The analysis suggested a simple dynamical framework for fractional killing, which predicts that cell fate can be altered in three possible ways: alteration of bifurcation geometry, alteration of cell trajectories, or both. These predicted categories can explain existing strategies known to combat fractional killing and facilitate the design of novel strategies.

DEC2 expression antagonizes cisplatin‑induced apoptosis in human esophageal squamous cell carcinoma

Differentiated embryonic chondrocyte expressed gene 1 (DEC1) and differentiated embryonic chondrocyte expressed gene 2 (DEC2) belong to the Hairy/Enhancer of Split subfamily of basic helix-loop-helix factors. Previous studies have demonstrated that DEC proteins are involved in the regulation of circadian rhythms, response to hypoxia, and tumorigenesis. However, the roles of DEC1 and DEC2 in apoptosis of esophageal carcinoma remain unclear. In the present study, alterations in expression of apoptosis-related markers in human esophageal squamous cell carcinoma TE-11 cells treated with cisplatin were examined by western blot, while overall cell viability and apoptosis were analyzed by MTS assay and hematoxylin and eosin staining, respectively. Following cisplatin treatment, expression of DEC2 was downregulated, whereas expression of DEC1 was upregulated. DEC2 overexpression during cisplatin treatment markedly inhibited expression of the pro-apoptotic factor Bim and slightly increased the anti-apoptotic factor Bcl-xL. However, overexpression of DEC1 during cisplatin treatment failed to affect expression of these markers. Additionally, overexpression of DEC2 improved cell viability and decreased cell apoptosis induced by cisplatin. These results suggested that DEC2 exhibits anti-apoptotic effects in TE-11 esophageal squamous cell carcinoma cells. Inhibiting DEC2 may therefore have therapeutic potential for the treatment of esophageal cancer, in combination with cisplatin.

HCMV activation of ERK-MAPK drives a multi-factorial response promoting the survival of infected myeloid progenitors

Viral binding and entry provides the first trigger of a cell death response and thus how human cytomegalovirus (HCMV) evades this - particularly during latent infection where a very limited pattern of gene expression is observed - is less well understood. It has been demonstrated that the activation of cellular signalling pathways upon virus binding promotes the survival of latently infected cells by the activation of cell encoded anti-apoptotic responses. In CD34+ cells, a major site of HCMV latency, ERK signalling is important for survival and we now show that the activation of this pathway impacts on multiple aspects of cell death pathways. The data illustrate that HCMV infection triggers activation of pro-apoptotic Bak which is then countered through multiple ERK-dependent functions. Specifically, ERK promotes ELK1 mediated transcription of the key survival molecule MCL-1, along with a concomitant decrease of the pro-apoptotic BIM and PUMA proteins. Finally, we show that the elimination of ELK-1 from CD34+ cells results in elevated Bak activation in response to viral infection, resulting in cell death. Taken together, these data begin to shed light on the poly-functional response elicited by HCMV via ERK-MAPK to promote cell survival.

Aberrant splicing and drug resistance in AML

The advent of next-generation sequencing technologies has unveiled a new window into the heterogeneity of acute myeloid leukemia (AML). In particular, recurrent mutations in spliceosome machinery and genome-wide aberrant splicing events have been recognized as a prominent component of this disease. This review will focus on how these factors influence drug resistance through altered splicing of tumor suppressor and oncogenes and dysregulation of the apoptotic signaling network. A better understanding of these factors in disease progression is necessary to design appropriate therapeutic strategies recognizing specific alternatively spliced or mutated oncogenic targets.

Molecular cloning, characterization and expression analysis of (B-cell lymphoma-2 associated X protein) Bax in the orange-spotted grouper (Epinephelus coioides) after the Vibrio alginolyticus challenge

Bax is a pro-apoptotic member of Bcl-2 like superfamily, playing an important role in regulating the apoptosis. In this study, the full-length Bax (EcBax) was obtained, containing a 5'UTR of 64 bp, an ORF of 579 bp and a 3'UTR of 1021 bp. The EcBax gene encoded a polypeptide of 192 amino acids with an estimated molecular mass of 21.55 KDa and a predicted isoelectric point (pI) of 6.75. The deduced amino acid sequence analysis showed that EcBax comprised the conserved residues and the characteristic domains known to the critical function of Bax. qRT-PCR analysis revealed that EcBax mRNA was broadly expressed in all of the examined tissues, while the highest expression level was observed in blood, followed by the expression in liver, gill, spleen, kidney, heart, muscle and intestine. A sharp increase of EcBax expression was observed in the vibrio challenge group by comparing with those in the control. Subcellular localization analysis revealed that EcBax was predominantly localized in the cytoplasm. EcBax exerted a regulatory role in modulating the mitochondrial membrane potential, promoting the cytochrome c release, and then activating the downstream caspase signaling. Moreover, the overexpression of EcBax can decrease the cell viability and antagonize NF-kB, AP-1, Stat3 promoter activity in Hela cells. These results indicate that EcBax containing the conserved domain of pro-apoptotic member of Bcl-2 family may disrupt the mammalian signaling and play a regulative role in the apoptotic process.

Induction of Apoptosis by the Nonstructural Protein 4 and 10 of Porcine Reproductive and Respiratory Syndrome Virus

Infection by most viruses triggers apoptosis in host cells, and viruses manipulate this cell response to promote viral replication, virus spread, and cell killing. Porcine reproductive and respiratory syndrome virus (PRRSV) has been shown to induce apoptosis both in vitro and in vivo, while the regulatory roles of PRRSV-encoded products in apoptosis are not fully understood. In the present study, we first showed a biphasic apoptosis regulation by a highly pathogenic PRRSV strain JXwn06. It was indicated that PRRSV infection delays apoptosis at early infection but activates apoptosis at late infection in MARC-145 cells. In PRRSV-infected MARC-145 cells, procaspase-8, -9 and -12 were activated at late infection, demonstrating the involvements of death receptor pathway, mitochondrial pathway and endoplasmic reticulum (ER) stress pathway in inducing apoptosis. PRRSV was also shown to induce a similar apoptosis process in pulmonary alveolar macrophages (PAMs) with an early initiation. Next, the PRRSV-encoded apoptosis inducers were screened, indicating that the nonstructural protein (Nsp) 4 and Nsp10 of PRRSV are pro-apoptotic. In the presence of Nsp4, it was confirmed that procaspase-8, -9 and -12 were cleaved, and Nsp4 facilitates the cleavage of procaspase-9 by activating B-cell lymphoma 2 interacting mediator of cell death (Bim), a pro-apoptotic protein. In addition, Nsp4 was shown to induce the degradation of an anti-apoptotic protein, B-cell lymphoma-extra large (Bcl-xL). Nsp10 was shown to activate procaspase-8 and -9 but procaspase-12 and to upregulate the expression of BH3-only pro-apoptotic protein BH3 interacting-domain death agonist (Bid) and its active form, truncated Bid (tBid). Clearly, the participation of both activated caspase-8 and Bid is required for Nsp10-induced apoptosis, indicating a crosstalk between extrinsic- and mitochondria-dependent pathways. Together, our findings suggest that PRRSV infection regulates apoptosis in a two-phase manner and activates all three apoptotic pathways; the Nsp4 and Nsp10 of PRRSV function as apoptosis inducers with different molecular basis.

MicroRNA-9 Mediates the Cell Apoptosis by Targeting Bcl2l11 in Ischemic Stroke

Ischemic strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain and accounts for about 87 % of all cases. During the cerebral ischemia, most of the neurons undergo the necrosis and apoptosis upon the exposure to the dramatic blood flow reduction. Although, it is known that both the intrinsic and extrinsic pathways are involved in the neuronal apoptosis of ischemic brain injury. The complex underlying mechanisms remains less known. MicroRNAs are a class of endogenous small non-coding RNAs and the role of miRNAs in the pathophysiology of stroke has been studied. In this study, we found that miR-9 is downregulated in the mice with middle cerebral artery occlusion (MCAO) brain and oxygen-glucose deprivation (OGD) neurons. Application of miR-9 gamer could restore the neurological scores and reduces the infarct volume, brain water content, and the behavioral impairments. Moreover, upregulation of miR-9 suppresses the neuronal apoptosis in MCAO brain and OGD neurons. Furthermore, we identified that Bcl2l11 as the direct target of miR-9 and manipulation of miR-9 induces the corresponding changing of Bcl2l11 protein level. Finally, we found that the protein level of Bcl2l11 is increased in the MCAO brain and OGD neurons. Our study demonstrated the critical role of miR-9 in the neuronal apoptosis of ischemic brain injury.

Evidence for microRNA-31 dependent Bim-Bax interaction preceding mitochondrial Bax translocation during radiation-induced apoptosis

Downregulation of microRNA-31 has been linked with enhanced stress resistance, while its overexpression leads to cell death. In this study, we found mediatory role of microRNA-31 in γ-radiation-induced apoptosis in a model insect cell line Sf9 carrying well-conserved apoptotic machinery. Mature microRNA-31 is perfectly conserved amongst insects; hence we used biotinylated probes designed from Bombyx mori sequence for its successful detection in Sf9 cells. Target identification using Bombyx mori 3′UTRs predicted miR-31′s potential role in Lepidopteran apoptosis, which prompted us to investigate alterations in its expression during radiation-induced cell death. We found significant overexpression of Sf-miR-31 following lethal dose (1,000Gy–3,000Gy) irradiation. Its mediatory role was finally confirmed as antisense-microRNA-31 could successfully inhibit radiation-induced cytochrome-c release, caspase-3 activation and apoptosis. While Bax/Bcl-2 expression remained unchanged, lethal radiation doses induced Bim overexpression and direct Bim-Bax interaction (co-immunoprecipitation) which is not yet unequivocally demonstrated during apoptosis. Quite important, these events were found to be dependent on radiation-induced miR-31 overexpression, as antisense-miR-31 inhibited both the responses and resulted in significant inhibition of cell death. Pro-apoptotic role of miR-31 was further confirmed when miR-31 mimic induced apoptosis involving similar Bim/Bax alterations. Therefore, our study reveals an important mediatory role of miR-31 in radiation-induced cell death.

Direct Activation of Bax Protein for Cancer Therapy

Bax, a central cell death regulator, is an indispensable gateway to mitochondrial dysfunction and a major proapoptotic member of the B-cell lymphoma 2 (Bcl-2) family proteins that control apoptosis in normal and cancer cells. Dysfunction of apoptosis renders the cancer cell resistant to treatment as well as promotes tumorigenesis. Bax activation induces mitochondrial membrane permeabilization, thereby leading to the release of apoptotic factor cytochrome c and consequently cancer cell death. A number of drugs in clinical use are known to indirectly activate Bax. Intriguingly, recent efforts demonstrate that Bax can serve as a promising direct target for small-molecule drug discovery. Several direct Bax activators have been identified to hold promise for cancer therapy with the advantages of specificity and the potential of overcoming chemo- and radioresistance. Further investigation of this new class of drug candidates will be needed to advance them into the clinic as a novel means to treat cancer.

Regulation of Bim in Health and Disease

The BH3-only Bim protein is a major determinant for initiating the intrinsic apoptotic pathway under both physiological and pathophysiological conditions. Tight regulation of its expression and activity at the transcriptional, translational and post-translational levels together with the induction of alternatively spliced isoforms with different pro-apoptotic potential, ensure timely activation of Bim. Under physiological conditions, Bim is essential for shaping immune responses where its absence promotes autoimmunity, while too early Bim induction eliminates cytotoxic T cells prematurely, resulting in chronic inflammation and tumor progression. Enhanced Bim induction in neurons causes neurodegenerative disorders including Alzheimer's, Parkinson's and Huntington's diseases. Moreover, type I diabetes is promoted by genetically predisposed elevation of Bim in β-cells. On the contrary, cancer cells have developed mechanisms that suppress Bim expression necessary for tumor progression and metastasis. This review focuses on the intricate network regulating Bim activity and its involvement in physiological and pathophysiological processes.

Reversion of left ventricle remodeling in spontaneously hypertensive rats by valsartan is associated with the inhibition of caspase-3, -8 and -9 activities

The development of hypertension is closely associated with cardiac hypertrophy and apoptosis, and caspase-3, -8 and -9 are key enzymes of apoptosis. The aim of the present study was to evaluate the effects of valsartan on left ventricle hypertrophy and myocardial apoptosis in spontaneously hypertensive rats (SHRs) and to explore the mechanisms for valsartan against apoptosis. A total of 15 SHRs (16 weeks old) were randomly divided into two groups. The SHRs in the valsartan (n=8) and SHR groups (n=7) were fed with valsartan and distilled water for 8 weeks, respectively. Wistar-Kyoto rats (n=8) were the control group. At the end of the experiments, blood pressure, parameters regarding hypertrophy, apoptosis and activities of caspase-3, -8 and -9 were measured. The results showed that valsartan significantly reduced systolic blood pressure and left ventricular hypertrophy, improved left ventricular remodeling, attenuated the myocardial damage and apoptosis, and decreased the activities of caspase-3, -8 and -9 in SHRs. In conclusion, valsartan is able to reverse hypertension-induced left ventricle remodeling, which is associated with, at least in part, its inhibitory effect on myocardial apoptosis in the death receptor-mediated extrinsic, as well as the mitochondrial-mediated intrinsic pathways.

Gamma-aminobutyric acid induces tumor cells apoptosis via GABABR1·β-arrestins·JNKs signaling module

Gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter in central nervous system, has yet been found to widely exist in tumor tissues to regulate tumor cells growth. However, the function of GABA on inducing tumor cells apoptosis and the potential mechanism are still unclear. In order to detect whether GABA via GABAB receptor GABABR1 would activate c-Jun N-terminal kinases (JNKs) to promote tumor cells apoptosis, co-immunoprecipitation assay was used to investigate the association of β-arrestins with GABABR1 and JNKs in the different four cancer cell lines. Our observation demonstrated that β-arrestins, in addition to their role in G protein-coupled receptors desensitization, had an additional function as adapter proteins to recruit JNKs to GABABR1, thereby conferring distinct enzymatic activities upon the receptor, which may trigger JNKs signal pathway involved in the regulation of cellular growth. Activated JNKs subsequently phosphorylated downstream c-Jun to transcribe a wide variety of pro-apoptotic genes. Additionally, GABA up-regulated the ratio of pro-apoptotic protein Bax to anti-apoptotic protein Bcl-2, and thus facilitated caspase-3 cleavage, leading to tumor cells apoptosis in a mitochondrial-dependent pathway. In contrast, GABABR antagonist CGP35348 reversed GABA-induced JNKs phosphorylation and its downstream proteins activation, which consequently restrained tumor cells apoptosis. Taken together, our study suggested that GABA via its receptor GABABR1 recruited β-arrestins to facilitate the activation of JNKs cascade, resulting in tumor cells growth inhibition.