Shedding light on apoptosis at subcellular membranes

The C-terminal sequences of Bcl-2 family proteins mediate interactions that regulate cell death

Programmed cell death via the both intrinsic and extrinsic pathways is regulated by interactions of the Bcl-2 family protein members that determine whether the cell commits to apoptosis via mitochondrial outer membrane permeabilization (MOMP). Recently the conserved C-terminal sequences (CTSs) that mediate localization of Bcl-2 family proteins to intracellular membranes, have been shown to have additional protein-protein binding functions that contribute to the functions of these proteins in regulating MOMP. Here we review the pivotal role of CTSs in Bcl-2 family interactions including: (1) homotypic interactions between the pro-apoptotic executioner proteins that cause MOMP, (2) heterotypic interactions between pro-apoptotic and anti-apoptotic proteins that prevent MOMP, and (3) heterotypic interactions between the pro-apoptotic executioner proteins and the pro-apoptotic direct activator proteins that promote MOMP.

Stroke in the Time of Circadian Medicine

Time-of-day significantly influences the severity and incidence of stroke. Evidence has emerged not only for circadian governance over stroke risk factors, but also for important determinants of clinical outcome. In this review, we provide a comprehensive overview of the interplay between chronobiology and cerebrovascular disease. We discuss circadian regulation of pathophysiological mechanisms underlying stroke onset or tolerance as well as in vascular dementia. This includes cell death mechanisms, metabolism, mitochondrial function, and inflammation/immunity. Furthermore, we present clinical evidence supporting the link between disrupted circadian rhythms and increased susceptibility to stroke and dementia. We propose that circadian regulation of biochemical and physiological pathways in the brain increase susceptibility to damage after stroke in sleep and attenuate treatment effectiveness during the active phase. This review underscores the importance of considering circadian biology for understanding the pathology and treatment choice for stroke and vascular dementia and speculates that considering a patient's chronotype may be an important factor in developing precision treatment following stroke.

Metal organic layers enabled cell surface engineering coupling biomembrane fusion for dynamic membrane proteome profiling

Systematically dissecting the highly dynamic and tightly communicating membrane proteome of living cells is essential for the system-level understanding of fundamental cellular processes and intricate relationship between membrane-bound organelles constructed through membrane traffic. While extensive efforts have been made to enrich membrane proteins, their comprehensive analysis with high selectivity and deep coverage remains a challenge, especially at the living cell state. To address this problem, we developed the cell surface engineering coupling biomembrane fusion method to map the whole membrane proteome from the plasma membrane to various organelle membranes taking advantage of the exquisite interaction between two-dimensional metal-organic layers and phospholipid bilayers on the membrane. This approach, which bypassed conventional biochemical fractionation and ultracentrifugation, facilitated the enrichment of membrane proteins in their native phospholipid bilayer environment, helping to map the membrane proteome with a specificity of 77% and realizing the deep coverage of the HeLa membrane proteome (5087 membrane proteins). Furthermore, membrane N-phosphoproteome was profiled by integrating the N-phosphoproteome analysis strategy, and the dynamic membrane proteome during apoptosis was deciphered in combination with quantitative proteomics. The features of membrane protein N-phosphorylation modifications and many differential proteins during apoptosis associated with mitochondrial dynamics and ER homeostasis were found. The method provided a simple and robust strategy for efficient analysis of membrane proteome, offered a reliable platform for research on membrane-related cell dynamic events and expanded the application of metal-organic layers.

StemRegenin 1 Mitigates Radiation-Mediated Hematopoietic Injury by Modulating Radioresponse of Hematopoietic Stem/Progenitor Cells

Hematopoietic injury resulting from the damage of hematopoietic stem/progenitor cells (HSPCs) can be induced by either nuclear accident or radiotherapy. Radiomitigation of HSPCs is critical for the development of medical countermeasure agents. StemRegenin 1 (SR1) modulates the maintenance and function of HSPCs under non-stress conditions. However, the impact of SR1 in radiation-induced hematopoietic injury both in vivo and in vitro remains unknown. In this study, we found that treatment with SR1 after irradiation of C57BL/6 mice significantly mitigates TBI-induced death (80% of SR1-treated mice survival vs. 30% of saline-treated mice survival) with enhanced recovery of peripheral blood cell counts, with the density and cell proliferation of bone marrow components as observed by Hematoxylin and Eosin (H&E) and Ki-67 staining. Interestingly, in vitro analysis of human HSPCs showed that SR1 enhanced the population of human HSPCs (CD34+) under both non-irradiating and irradiating conditions, and reduced radiation-induced DNA damage and apoptosis. Furthermore, SR1 attenuated the radiation-induced expression of a member of the pro-apoptotic BCL-2 family and activity of caspase-3. Overall, these results suggested that SR1 modulates the radioresponse of HSPCs and might provide a potential radiomitigator of hematopoietic injury, which contributes to increase the survival of patients upon irradiation.

STAT3 regulation of Mtb-specific T cell function in active pulmonary tuberculosis patients

BACKGROUND

Tuberculosis (TB) remains one of the most serious infectious diseases in the world. Our aim was to investigate the regulatory role of STAT3 and pSTAT3 in the regulation of T cell immunophenotype and cell function.

METHODS

Twenty-five active pulmonary tuberculosis (APTB) patients, 18 latent tuberculosis infection (LTBI) patients, and 20 healthy controls (HCs) enrolled in this study. T cell phenotype and expression of STAT3 and pSTAT3 were detected by flow cytometry.

RESULTS

Compared with HCs, the expression of pSTAT3 in CD4⁺ T and CD8⁺ T cells in peripheral blood of APTB patients was increased, and the expression was higher in pleural effusion. Multifunctional T cells that simultaneously secrete IFN-γ, TNF-α and IL-17A have higher pSTAT3 expression levels. Mtb-specific T cells from APTB patients had a higher cell frequency of the STAT3⁺ pSTAT3⁺ phenotype and a reduced cell frequency of the STAT3⁺ pSTAT3^- phenotype compared with LTBI patients. Mtb-specific T cells with STAT3⁺ pSTAT3⁺ phenotype had higher expression of PD-1 and PD-L1, while cells with STAT3⁺ pSTAT3^- phenotype had higher expression of Bcl-2.

CONCLUSIONS

STAT3 and pSTAT3 in T cells of APTB patients feature in the process of anti-apoptosis and cytokine secretion. At the same time, the higher pSTAT3 may be related to the degree of cell functional exhaustion. The pSTAT3 level of T cells is related to the infection status and may indicate the clinical activity of the disease, which provides a new idea for the clinical identification and treatment of active pulmonary tuberculosis.

Diallyl Disulfide Attenuates Methotrexate-Induced Hepatic Oxidative Injury, Inflammation and Apoptosis and Enhances its Anti-Tumor Activity

BACKGROUND

Methotrexate (MTX) is used potently for a wide range of diseases. However, hepatic intoxication by MTX hinders its clinical use.

OBJECTIVES

The present study was conducted to investigate the diallyl disulfide (DADS) ability to ameliorate MTX-induced hepatotoxicity.

METHODS

Thirty-two rats were randomly divided into four groups: normal control, DADS (50 mg/kg/day, orally), MTX (single i.p. injection of 20 mg/kg) and DADS+MTX. Liver function biomarkers, histopathological examinations, oxidative stress, inflammation, and apoptosis biomarkers were investigated. Besides, an in vitro cytotoxic activity study was conducted to explore the modulatory effects of DADS on MTX cytotoxic activity using Caco-2, MCF-7, and HepG2 cells.

RESULTS

DADS significantly reduced the increased serum activities of ALT, AST, ALP, and LDH. These results were confirmed by the alleviation of liver histopathological changes. It restored the decreased GSH content and SOD activity, while significantly decreased MTX-induced elevations in both MDA and NO2 - contents. The hepatoprotective effects were mechanistically mediated through the up-regulation of hepatic Nrf-2 and the down-regulation of Keap-1, P38MAPK, and NF- κB expression levels. In addition, an increase in Bcl-2 level with a decrease in the expression of both Bax and caspase-3 was observed. The in vitro study showed that DADS increased MTX antitumor efficacy.

CONCLUSION

DADS potently alleviated MTX-induced hepatotoxicity through the modulation of Keap-1/Nrf-2, P38MAPK/NF-κB and apoptosis signaling pathways and effectively enhanced the MTX cytotoxic effects, which could be promising for further clinical trials.

Diallyl disulfide ameliorates methotrexate-induced nephropathy in rats: Molecular studies and network pharmacology analysis

Methotrexate (MTX) is a promising chemotherapeutic agent. Its medical use is limited by induced nephropathy. Our study was designed to explore the reno-protective effect of diallyl disulfide (DADS), an organosulfur compound of garlic oil, on MTX-induced nephropathy. Adult rats were randomly divided into 4 groups; normal control, DADS (50 mg kg^-1  day^-1 , p.o.), MTX (20 mg/kg, i.p.) and DADS+MTX. DADS significantly decreased serum creatinine, urea, uric acid, and albumin levels with an improvement of final body weight. Additionally, DADS markedly attenuated MTX-induced elevations in renal MDA and NO 2 - contents with an increase in GSH content and SOD activity. Mechanistically, DADS effectively down-regulated mRNA expression level of renal p38 and NF-κB. Additionally, DADS positively regulated the NRF2 gene with a remarkable inhibition of Keap-1 gene. Furthermore, DADS up-regulated BCL2 protein and remarkably suppressed the expression of both BAX and caspase-3 proteins. Overall, DADS has favorable renal protection against MTX-induced nephropathy via modulation of Keap-1/NRF2, p38/NF-κB, and BCL2/BAX/caspase-3 signaling. PRACTICAL APPLICATIONS: Diallyl disulfide is one of the organosulfur compounds of garlic oil. Our study demonstrated that DADS substantially alleviated the decline of kidney function and renal injury induced by MTX. The antioxidative, anti-inflammatory, and anti-apoptotic properties may constitute an important part of its therapeutic applications via regulation of p38/NF-κB, Keap-1/NRF2, and BCL2/BAX/caspase-3 signaling pathways. Therefore, DADS could be a potential therapeutic adjunct in cancer chemotherapy to decrease the associated side effects of MTX. It should be further explored clinically as a protective agent for MTX-treated cancer patients.

Neuronal cell life, death, and axonal degeneration as regulated by the BCL-2 family proteins

Axonal degeneration and neuronal cell death are fundamental processes in development and contribute to the pathology of neurological disease in adults. Both processes are regulated by BCL-2 family proteins which orchestrate the permeabilization of the mitochondrial outer membrane (MOM). MOM permeabilization (MOMP) results in the activation of pro-apoptotic molecules that commit neurons to either die or degenerate. With the success of small-molecule inhibitors targeting anti-apoptotic BCL-2 proteins for the treatment of lymphoma, we can now envision the use of inhibitors of apoptosis with exquisite selectivity for BCL-2 family protein regulation of neuronal apoptosis in the treatment of nervous system disease. Critical to this development is deciphering which subset of proteins is required for neuronal apoptosis and axon degeneration, and how these two different outcomes are separately regulated. Moreover, noncanonical BCL-2 family protein functions unrelated to the regulation of MOMP, including impacting necroptosis and other modes of cell death may reveal additional potential targets and/or confounders. This review highlights our current understanding of BCL-2 family mediated neuronal cell death and axon degeneration, while identifying future research questions to be resolved to enable regulating neuronal survival pharmacologically.

High NRBP1 expression promotes proliferation and correlates with poor prognosis in bladder cancer

Nuclear receptor binding protein 1 (NRBP1) is an evolutionarily highly conserved adaptor protein with multiple domains. Recently, its role in cancers has received increasing attention. To investigate whether NRBP1 is involved in the development of bladder cancer, we used tissue microarray and analyzed the association between the expression levels of NRBP1 and clinico-pathological features of 56 patients diagnosed with bladder cancer. Subsequently, NRBP1 was silenced using siRNA in bladder cancer cell lines T24 and 5637, and cell phenotype such as proliferation and apoptosis were observed. Further, in vivo tumor formation assay was performed. The expression of apoptosis markers was detected by Western blot. A significant positive correlation between increased NRBP1 expression and tumor stage, and lymph node metastasis was observed in 56 patients. High expression of NRBP1 was associated with poor prognosis and NRBP1 knockdown significantly inhibited cell proliferation and induced intrinsic apoptosis in vitro. Moreover, we also found that NRBP1 knockdown significantly suppress tumor growth in xenograft mouse model. Taken together, these data suggest that NRBP1 plays a critical role in the development of bladder cancer and may represent a potential target for bladder cancer treatment.

Developmental Cell Death in the Cerebral Cortex

In spite of the high metabolic cost of cellular production, the brain contains only a fraction of the neurons generated during embryonic development. In the rodent cerebral cortex, a first wave of programmed cell death surges at embryonic stages and affects primarily progenitor cells. A second, larger wave unfolds during early postnatal development and ultimately determines the final number of cortical neurons. Programmed cell death in the developing cortex is particularly dependent on neuronal activity and unfolds in a cell-specific manner with precise temporal control. Pyramidal cells and interneurons adjust their numbers in sync, which is likely crucial for the establishment of balanced networks of excitatory and inhibitory neurons. In contrast, several other neuronal populations are almost completely eliminated through apoptosis during the first two weeks of postnatal development, highlighting the importance of programmed cell death in sculpting the mature cerebral cortex.

Ginsenoside Rg5 induces apoptosis in human esophageal cancer cells through the phosphoinositide‑3 kinase/protein kinase B signaling pathway

The role of ginsenoside in the prevention of cancer has been well established. Ginsenoside Rg5 is one of the main components isolated from red ginseng, which has been demonstrated to have anti-tumor effects by inhibiting cell proliferation and causing DNA damage. However, the role of ginsenoside Rg5 and its molecular mechanisms remain unclear in human esophageal cancer. In the present study, Rg5 was investigated as a novel drug for the chemotherapy of esophageal cancer in in vitro experiments. Esophageal cancer Eca109 cells were exposed to various concentrations of ginsenoside Rg5 (0–32 µΜ) for 24 h. Subsequent cell proliferation assays demonstrated that treatment with ginsenoside Rg5 resulted in the dose-dependent inhibition of proliferation, while a significant increase in apoptotic rate and increased activities of caspase-3, −8 and −9 were observed. In addition, the mitochondrial membrane potential was decreased and the cytoplasmic free calcium level increased following treatment with ginsenoside Rg5. Furthermore, the expression of B-cell lymphoma 2 and phosphorylated-protein kinase B (p-Akt) decreased. The specific phosphoinositide-3 kinase (PI3K) inhibitor LY294002 promoted this effect, while insulin-like growth factor-1, a specific PI3K activator, inhibited this action. Taken together, the results suggested that ginsenoside Rg5 may have a tumor-suppressive effect on esophageal cancer by promoting apoptosis and may be associated with the downregulation of the PI3K/Akt signaling pathway.

Bim escapes displacement by BH3-mimetic anti-cancer drugs by double-bolt locking both Bcl-XL and Bcl-2

Tumor initiation, progression and resistance to chemotherapy rely on cancer cells bypassing programmed cell death by apoptosis. We report that unlike other pro-apoptotic proteins, Bim contains two distinct binding sites for the anti-apoptotic proteins Bcl-XL and Bcl-2. These include the BH3 sequence shared with other pro-apoptotic proteins and an unexpected sequence located near the Bim carboxyl-terminus (residues 181-192). Using automated Fluorescence Lifetime Imaging Microscopy - Fluorescence Resonance Energy Transfer (FLIM-FRET) we show that the two binding interfaces enable Bim to double-bolt lock Bcl-XL and Bcl-2 in complexes resistant to displacement by BH3-mimetic drugs currently in use or being evaluated for cancer therapy. Quantifying in live cells the contributions of individual amino acids revealed that residue L185 previously thought involved in binding Bim to membranes, instead contributes to binding to anti-apoptotic proteins. This double-bolt lock mechanism has profound implications for the utility of BH3-mimetics as drugs. ​.

Cleavage of GSDME by caspase-3 determines lobaplatin-induced pyroptosis in colon cancer cells

Pyroptosis, a form of programmed cell death (PCD), has garnered increasing attention as it relates to innate immunity and diseases. However, the involvement of pyroptosis in the mechanism by which lobaplatin acts against colorectal cancer (CRC) is unclear. Our study revealed that treatment with lobaplatin reduced the viability of HT-29 and HCT116 cells in a dose-dependent manner. Morphologically, HT-29 and HCT116 cells treated with lobaplatin exhibited microscopic features of cell swelling and large bubbles emerging from the plasma membrane, and transmission electron microscopy (TEM) revealed multiple pores in the membrane. GSDME, rather than GSDMD, was cleaved in lobaplatin-induced pyroptosis in HT-29 and HCT116 cells due to caspase-3 activation. Knocking out GSDME switched lobaplatin-induced cell death from pyroptosis to apoptosis but did not affect lobaplatin-mediated inhibition of growth and tumour formation of HT-29 and HCT116 cells in vivo and in vitro. Further investigation indicates that lobaplatin induced reactive oxygen species (ROS) elevation and JNK phosphorylation. NAC, a ROS scavenger, completely reversed the pyroptosis of lobaplatin-treated HT-29 and HCT116 and JNK phosphorylation. Activated JNK recruited Bax to mitochondria, and thereby stimulated cytochrome c release to cytosol, followed by caspase-3/-9 cleavage and pyroptosis induction. Therefore, in colon cancer cells, GSDME mediates lobaplatin-induced pyroptosis downstream of the ROS/JNK/Bax-mitochondrial apoptotic pathway and caspase-3/-9 activation. Our study indicated that GSDME-dependent pyroptosis is an unrecognized mechanism by which lobaplatin eradicates neoplastic cells, which may have important implications for the clinical application of anticancer therapeutics.

Effects of nuclear respiratory factor‑1 on apoptosis and mitochondrial dysfunction induced by cobalt chloride in H9C2 cells

Hypoxia-induced apoptosis occurs in various diseases. Cobalt chloride (CoCl₂) is a hypoxia mimic agent that is frequently used in studies investigating the mechanisms of hypoxia. Nuclear respiratory factor-1 (NRF-1) is a transcription factor with an important role in the expression of mitochondrial respiratory and mitochondria-associated genes. However, few studies have evaluated the effects of NRF-1 on apoptosis, particularly with regard to damage caused by CoCl₂. In the present study, the role of NRF-1 in mediating CoCl₂-induced apoptosis was investigated using cell viability analysis, flow cytometry, fluorescence imaging, western blotting analysis, energy metabolism analysis and reverse transcription-quantitative polymerase chain reaction. The present results revealed that the apoptosis caused by CoCl₂ could be alleviated by NRF-1. Furthermore, overexpression of NRF-1 increased the expression of B-cell lymphoma-2, hypoxia inducible factor-1α and NRF-2. Also, cell damage induced by CoCl₂ may be associated with depolarization of mitochondrial membrane potential, and NRF-1 suppressed this effect. Notably, the oxygen consumption rate (OCR) was reduced in CoCl₂-treated cells, whereas overexpression of NRF-1 enhanced the OCR, suggesting that NRF-1 had protective effects. In summary, the present study demonstrated that NRF-1 protected against CoCl₂-induced apoptosis, potentially by strengthening mitochondrial function to resist CoCl₂-induced damage to H9C2 cells. The results of the present study provide a possible way for the investigation of myocardial diseases.

Hepatoprotective effect of rhein against methotrexate-induced liver toxicity

The purpose of this study was to investigate the protective effect of rhein, a major metabolite of diacerein, on methotrexate (MTX)-induced hepatotoxicity and clarify the pharmacological mechanism. Rhein significantly reduced the elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) caused by MTX in rat serum and improved liver morphological damage induced by MTX. Moreover, rhein increased the cell survival rate and reduced the number of apoptosis cells in MTX-treated normal human hepatocyte (L02 cells). Rhein treatment in rats up-regulated nuclear factor erythroid 2-related factor 2 (Nrf2), B-cell lymphoma-2 (Bcl-2), heme oxygenase 1 (HO-1) and glutamate-cysteine ligase catalytic subunit (GCLC), and down-regulated Bcl-2 associated x (Bax) in mRNA and protein levels. Furthermore, rhein treatment further decreased protein expression of nuclear factor-kappa B (NF-κB), tumor necrosis factor alpha (TNF-α) and cysteine aspartic acid specific protease 3 (Caspase-3), increased protein expression of B-cell lymphoma-extra large (Bcl-xl), and reduced mRNA expression of Bcl-2 homologous antagonist/killer (Bak) in MTX-treated rat liver in vivo. However, the protein expression changes of Nrf2, HO-1, GCLC, Bcl-2, Bcl-xl and Bax could be abrogated by Nrf2 antagonist brusatol. In addition, protective effect of rhein against MTX-mediated liver damage could also be suppressed by Nrf2 siRNA in L02 cells. Taken together, these findings suggested that rhein ameliorated liver damage mediated by MTX through acting on Nrf2-HO-1 pathway. NF-κB, TNF-α, Caspase-3 and Bcl-2 family were also participated in the protection. As effectively hepatoprotective ability of rhein, it would raise an important issue for patients orally receiving MTX treatment together with diacerein/rhein.

PINK1 Protects Auditory Hair Cells and Spiral Ganglion Neurons from Cisplatin-induced Ototoxicity via Inducing Autophagy and Inhibiting JNK Signaling Pathway

Phosphatase and tensin homologue (PTEN)-induced putative kinase 1 (PINK1) gene encodes a serine/threonine kinase, which acts as a molecular sensor of mitochondrial health necessary for mitochondrial quality control. The present study was designed to examine whether PINK1 expressed in C57BL/6 murine cochlea and HEI-OC1 cells and, if so, to investigate the possible mechanisms underlying the action of PINK1 in cisplatin-induced death of sensory hair cells (HCs) and spiral ganglion neurons (SGNs) in vitro. The expression pattern of PINK1, formation of parkin particles, and autophagy were determined by immunofluorescent staining. The expressions of PINK1, LC3B, cleaved-caspase 3 and p-JNK were measured by Western blotting. The levels of reactive oxygen species (ROS) were evaluated by DCFH-DA and Mito-Sox Red staining. The mitochondrial membrane potential was detected by Tetramethylrhodamine methyl ester perchlorate (TMRM) and Rhodamine 123. Cell viability and apoptosis were examined by CCK8 assay, TUNEL staining and Annexin V Apoptosis Detection Kit, respectively. We found that PINK1 was widely expressed in the cytoplasm in HCs, SGNs, stria vascularis of C57BL/6 cochlea and HEI-OC1 cells and, notably, the expression level in cochlear HCs and SGNs of postnatal day 4 (P4) mice was higher than that in adult mice. Moreover, treatment with 30 μM cisplatin elicited the formation of ROS, which, in turn, led to PINK1 activation, parkin recruitment, autophagy formation and JNK pathway relevant to apoptosis in HEI-OC1 cells, HCs, and SGNs. Meanwhile, co-treatment with ROS scavenger N-acetyl-L-cysteine (NAC) or H₂O₂ consumer catalase-polyethylene glycol (PEG-catalase) inhibited parkin recruitment, alleviated autophagy formation, and mitigated JNK pathway related apoptosis. In addition, PINK1 silencing resulted in a lower level of autophagy, but, a higher mortality in HEI-OC1 cells treated with cisplatin. Taken together, data from this work reveal that PINK1 possesses the protective effect via induction of autophagy and resistance of apoptosis under cisplatin stimulus in sensory HCs and SGNs, implying that PINK1 might serve as an important regulator of cisplatin-elicited ototoxicity.

Usnic Acid Induces Cycle Arrest, Apoptosis, and Autophagy in Gastric Cancer Cells In Vitro and In Vivo

Background

Usnic acid (UA), a secondary metabolite, is mainly derived from certain lichen species. Growing evidence suggests that UA has antitumor, anti-oxidative, anti-inflammatory, and other activities in a variety of cancer cells. However, the antitumor effect of UA in gastric cancer cells (GC) is unclear. The aim of this investigation was to assess the antitumor effect of UA in GC cells in vitro and in vivo, and to explore the underlying mechanisms.

Material/Methods

Cell proliferation was measured by CCK8 assay, the arrest of cell cycle was assessed by flow cytometry, and cellular apoptosis was observed via Hoechst 33258 staining assay. Expression levels of apoptosis-related proteins (activated caspase-3 and PARP, Bax, Bcl2) and autophagy-associated proteins (LC3-II and p62) were verified through Western blot analysis. H&E staining and immunohistochemistry were carried out in the subcutaneously implanted BGC823 tumor model in a nude mouse experiment.

Results

In vitro, we demonstrated that UA was significantly effective in inducing morphological changes, inhibiting the cell proliferation dose- and time-dependently, arresting the cell cycle phase, promoting cancer cellular apoptosis, and inducing autophagy activity. In vivo, compared to mice treated with 5-FU alone, UA treatment was significantly more effective in suppressing the tumor growth without affecting body weight, and in regulating the amount of Bax and Bcl2 in tumor tissues.

Conclusions

UA induces cell cycle arrest and autophagy and exerts anti-proliferative and apoptotic effects by modulating expression of apoptosis-related proteins in stomach neoplasm cells, and has a better antitumor effect compared to 5-Fu in the xenograft model.

Mitochondria are transported along microtubules in membrane nanotubes to rescue distressed cardiomyocytes from apoptosis

Membrane nanotubes (MNTs) act as “highways” between cells to facilitate the transfer of multiple signals and play an important role in many diseases. Our previous work reported on the transfer of mitochondria via MNTs between cardiomyocytes (CMs) and cardiac myofibroblasts (MFs); however, the elucidation of the underlying mechanism and pathophysiological significance of this transfer requires additional study. In this study, we determined that the mean movement velocity of mitochondria in MNTs between CMs and MFs was approximately 17.5 ± 2.1 nm/s. Meanwhile, treatment with microtubule polymerisation inhibitors nocodazole or colcemid in cell culture decreased mitochondrial velocity, and knockdown of the microtubule motor protein kinesin family member 5B (KIF5B) led to a similar effect, indicating that mitochondrial movement was dependent on microtubules and the motor protein KIF5B. Furthermore, we showed that hypoxia/reoxygenation-induced CM apoptosis was attenuated by coculture with intact or hypoxia/reoxygenation-treated MFs, which transferred mitochondria to CMs. This rescue was prevented either by separating the cells using Transwell culture or by impairing mitochondrial transfer with nocodazole or colcemid treatment. In conclusion, as a novel means of intercellular communication, MNTs rescue distressed CMs from apoptosis by transporting mitochondria along microtubules via KIF5B.

Paeoniflorin reduces neomycin-induced ototoxicity in hair cells by suppression of reactive oxygen species generation and extracellularly regulated kinase signalization

The present study was designed to investigate the effect of paeoniflorin (PF) on neomycin-induced ototoxicity in hair cells (HCs). Here, we took advantage of C57BL/6 mice and cochlear explants culture to determine the role of PF in vivo and in vitro. We demonstrated that neomycin exposure induced severe hearing loss and HC damage, which was mediated by activated mitochondrial apoptosis pathway, promoted extracellular signal-regulated kinase (ERK) signaling as well as enhanced reactive oxygen species (ROS) generation in HCs. Interestingly, we found that PF pretreatment significantly alleviated neomycin-induced hearing loss, attenuated HC injury and decreased HC apoptosis caused by neomycin. Mechanistic studies revealed that PF could decrease cellular ROS levels, suppress the activation of ERK signaling and, subsequently, mitigate the imbalance of mitochondrial apoptotic pathway, thus protecting HCs from neomycin-induced apoptosis. This study indicates that PF may serve as an antioxidative and anti-apoptotic agent to prevent hearing loss caused by neomycin.

Astaxanthin prevents ischemia-reperfusion injury of the steatotic liver in mice

Steatosis has a low tolerance against ischemia-reperfusion injury (IRI). To prevent IRI in the steatotic liver, we attempted to elucidate the protective effect of astaxanthin (ASTX) in the steatotic liver model by giving mice a methionine and choline-deficient high fat (MCDHF) diet. Levels of lipid peroxidation and apoptosis, the expression of inflammatory cytokines and heme oxygenase (HO)-1, in the liver were assessed. Reactive oxygen species (ROS), inflammatory cytokines, apoptosis-related proteins and members of the signaling pathway were also examined in isolated Kupffer cells and/or hepatocytes from the steatotic liver. ASTX decreased serum ALT and AST levels, the amount of TUNEL, F4/80, or 4HNE-positive cells and the mRNA levels of inflammatory cytokines in MCDHF mice by IRI. Moreover, HO-1 and HIF-1α, phosphorylation of Akt and mTOR expressions were increased by ASTX. The inflammatory cytokines produced by Kupffer, which were subjected to hypoxia and reoxygenation (HR), were inhibited by ASTX. Expressions of Bcl-2, HO-1 and Nrf2 in hepatocytes by HR were increased, whereas Caspases activation, Bax and phosphorylation of ERK, MAPK, and JNK were suppressed by ASTX. Pretreatment with ASTX has a protective effect and is a safe therapeutic treatment for IRI, including for liver transplantation of the steatotic liver.

Calcium-sensing receptor antagonist NPS2390 attenuates neuronal apoptosis though intrinsic pathway following traumatic brain injury in rats

Traumatic brain injury (TBI) initiates a complex cascade of neurochemical and signaling changes that leads to neuronal apoptosis, which contributes to poor outcomes for patients with TBI. Previous study indicates that calcium-sensing receptor (CaSR) activation contributes to neuron death in focal cerebral ischemia-reperfusion mice, however, its role in neuronal apoptosis after TBI is not well-established. Using a controlled cortical impact model in rats, the present study was designed to determine the effect of CaSR inhibitor NPS2390 upon neuronal apoptosis after TBI. Rats were randomly distributed into three groups undergoing the sham surgery or TBI procedure, and NPS2390 (1.5 mg/kg) was infused subcutaneously at 30 min and 120 min after TBI. All rats were sacrificed at 24 h after TBI. Our data indicated that NPS2390 significantly reduced the brain edema and improved the neurological function after TBI. In addition, NPS2390 decreased caspase-3 levels and the number of apoptotic neurons. Furthermore, NPS2390 up-regulated anti-apoptotic protein Bcl-2 expression and down-regulated pro-apoptotic protein Bax, and reduced subsequent release of cytochrome c into the cytosol. In summary, this study indicated that inhibition of CaSR by NPS2390 attenuates neuronal apoptosis after TBI, in part, through modulating intrinsic apoptotic pathway.

NLRX1 accelerates cisplatin-induced ototoxity in HEI-OC1 cells via promoting generation of ROS and activation of JNK signaling pathway

Nucleotide-binding domain and leucine-rich-repeat-containing family member X1 (NLRX1), located in mitochondria, can recognize cytoplasmic pattern recognition receptors and is tightly related to reactive oxygen species (ROS) production, mitochondrial function, apoptosis and inflammation. The present study was designed to explore whether NLRX1 expresses in HEI-OC1 cells and, if so, to investigate the possible correlations between NLRX1 and cisplatin-induced ototoxity in vitro. Here, we report that NLRX1 was specifically localized to mitochondria in the cytoplasm of HEI-OC1 cells and its expression was increased concurrent with the increase of ROS production and occurrence of apoptosis in HEI-OC1 cells in response to cisplatin stimulus. NLRX1 overexpression led to a higher apoptosis in HEI-OC1 cells treated with cisplatin, whereas, NLRX silencing decreased cisplatin induced apoptosis. Mechanistic studies showed that NLRX1 activated mitochondrial apoptosis pathway as well as promoted ROS generation and JNK activation. Either inhibition of ROS generation or JNK signaling significantly prevented NLRX1-mediated mitochondrial apoptosis in HEI-OC1cells. In addition, NLRX1 expression was confirmed in cochlear explants. The findings from this work reveal that NLRX1 sensitizes HEI-OC1 cells to cisplatin-induced apoptosis via activation of ROS/JNK signaling pathway, suggesting that NLRX1 acts as an important regulator of the cisplatin-elicited ototoxity.

Gambogenic acid synergistically potentiates bortezomib-induced apoptosis in multiple myeloma

Background: Although the introduction of protease inhibitor bortezomib (BTZ) and immunomodulatory agent lenalidomide has led to improved outcomes in patients with multiple myeloma (MM), the disease remains incurable. Gambogenic acid (GNA), a polyprenylated xanthone isolated from the traditional Chinese medicine gamboge, has been reported to have potent antitumor activity and can effectively inhibit the survival and proliferation of cancer. In this study, we hypothesized that GNA could synergistically potentiate BTZ-induced apoptosis of MM cells and that combining BTZ and GNA may provide a more effective approach to treat MM. Hence, we investigate the in vitro and in vivo effects of BTZ and GNA, alone or in combination, against myeloma MM.1S cells.

Methods: Cell counting kit-8 (CCK-8) assay, combination index (CI) isobologram, flow cytometry, western blot, xenograft tumor models, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and immunochemistry were used in this study.

Results: The results showed that BTZ and GNA combination treatment resulted in a strong synergistic action against the MM.1S cell line. Increased G2/M phase cells were triggered by BTZ, GNA and the combined treatment. The combined treatment could induce more markedly apoptosis of MM.1S cells via the activation of PARP cleavage, P53, Caspase-3 cleavage and Bax and inhibition of Bcl-2 expression. An increased antitumor effects of combination therapy of BTZ and GNA on MM.1S xenograft models were observed, and combining BTZ and GNA was found to be superior to a single agent.

Conclusions: Our data support that a synergistic antitumor activity exists between BTZ and GNA, and provide a rationale for successful utilization of dual BTZ and GNA in MM chemotherapy in the future.

Ferulic acid promoting apoptosis in human osteosarcoma cell lines

OBJECTIVE

To explore the promoting apoptosis and antitumor activities of ferulic acid (FA) in human osteosarcoma and its potential mechanism.

METHODS

The SaOS-2 and MG63 osteosarcoma cell lines were opted to experiment and these cells were, respectively, cultured with various concentrations of FA (0 μM, 10 μM, 20 μM, 40 μM) for 72 hours at 37°C. The viabilities of the FA treated cells were monitored by MTT. Apoptosis cells were evaluated using annexin V/PI by flow cytometry. Apoptosis proteins caspase-3, procaspase-3, Bcl-2 and Bax were detected by western blot. Expressions of apoptotic genes Bcl-2 and Bax were quantified by qPCR.

RESULTS

The cell viabilities were critically declined in the concentration-dependent manner in FA groups (P < 0.01). The apoptosis cells were increased proportionately with the concentration of FA (P < 0.05). The procaspase-3 protein contents, and Bcl-2 mRNA and protein contents were significantly decreased while caspase-3 protein contents, and Bax mRNA and protein contents were concomitantly increased in the concentration-dependent manner in FA groups (P < 0.05). The response to FA by the SaOS-2 osteosarcoma cell was similar with the MG63 osteosarcoma cell (P > 0.05).

CONCLUSION

Ferulic acid could significantly descend osteosarcoma cell viability through the promoting apoptosis pathway in which FA activates both caspase-3 and Bax and inactivates Bcl-2.

[Effect and Mechanism of Radiosensitization of Poly (ADP-Ribose) Polymerase Inhibitor n Lewis Cells and Xenografts]

背景与目的

受电离辐射的肿瘤细胞DNA损伤主要为单链断裂(single strand break, SSB)与双链断裂(double strand break, DSB)，其中SSBs发生的频率数十倍于DSBs，而SSBs多能通过聚腺苷二磷酸核糖聚合酶[Poly(ADP-Ribose) polymerase, PARP]等因子进行修复。相关新药Olaparib(PARP1/PARP2/PARP3抑制剂)靶向作用于细胞SSBs损伤修复，其联合化疗的临床研究取得令人鼓舞结果。本实验旨在研究Olaparib对Lewis肺癌细胞及移植瘤放疗增敏作用，初步探讨其可能机制。

方法

采用MTT法检测Olaparib对Lewis细胞10%抑制浓度(10% inhibitory concentration, IC₁₀)值，克隆形成实验验证Olaparib联合放疗的体外增敏作用；成瘤小鼠分为空白对照、Olaparib、放疗(radiotherapy, RT, 2 Gy×5 d)、Olaparib+RT组，动态测量各组移植瘤体积变化；流式细胞术比较各组细胞体外凋亡率，TUNEL法比较移植瘤细胞凋亡；Western blot检测各组DNA损伤相关蛋白γH2AX，凋亡相关蛋白Bax/Bcl-2、Caspase-3表达。

结果

Olaparib对Lewis细胞IC₁₀值为4.4 μmol/L，克隆形成实验测得Olaparib放疗增敏比为1.211；移植瘤初体积(处理前)增长4倍所需天数，Olaparib+RT组显著高于单纯RT组(P < 0.001)；流式及TUNEL法检测Lewis细胞体内外凋亡率均Olaparib+RT组高于RT组(P < 0.05)；Olaparib+RT组细胞及移植瘤中γH2AX、Bax、Caspase-3显著高于RT组，Bcl-2显著低于RT组(均P < 0.05)。

结论

Olaparib对Lewis肺癌细胞及移植瘤起到显著放疗增敏作用，其机制可能与增加受照肿瘤细胞DNA双链断裂形成，上调Bax/Bcl-2促凋亡体系蛋白有关。

Hyperlipidemia and the development of diabetic retinopathy: Comparison between type 1 and type 2 animal models

AIM

In the pathogenesis of diabetic retinopathy, reactive oxygen species (ROS) are elevated in the retina and the mitochondria are damaged, resulting in accelerated apoptosis. Dyslipidemia is also considered as one of the major factors in its development, and our aim is to investigate the compounding effect of hyperlipidemia in retinopathy.

METHODS

Retinal ROS, mitochondrial damage and vascular pathology were investigated in Zucker diabetic fatty rats (ZDF, type 2 diabetes model), during the age that spans from hyperlipidemia/pre-hyperglycemia (6weeks), to severe hyperglycemia/moderate hyperlipidemia (~12weeks), and ultimately to severe hyperglycemia/hyperlipidemia (20-40weeks). For comparison, retina from streptozotocin-induced Wistar rats (type 1 diabetic for 10-40weeks) was analyzed.

RESULTS

Compared to age-matched lean rats, despite increased retinal cytosolic ROS in 6-week-old ZDF rats, mitochondrial dysfunction and DNA damage were not detected, and in 12-week-old ZDF rats, retinal mitochondria were dysfunctional, but mtDNA damage and vascular pathology (cell apoptosis and degenerative capillaries) were not detectable. Retina from 20-week-old ZDF rats (hyperglycemic for 14weeks or less) had significant mitochondrial dysfunction, mtDNA damage and vascular pathology, and similar abnormalities were observed in 40-week-old ZDF rats. Although retinal mitochondrial dysfunction was observed in Wistar rats diabetic for 20weeks, mtDNA damage and vascular pathology were not detectable till the duration of diabetes was further extended.

CONCLUSIONS

Hyperlipidemia, in a hyperglycemic milieu, potentiates mitochondrial damage and augments the development of retinopathy. Control of dyslipidemia in pre-diabetic patients may prevent/delay the development and the progression of this devastating disease.

Interplay Between Gemcitabine and Erlotinib Over Pancreatic Adenocarcinoma Cells

OBJECTIVES

Pancreatic ductal adenocarcinoma remains as a chemoresistant disease with the poorest prognosis. Gemcitabine has been the standard treatment during the last decade. Erlotinib, a tyrosine kinase inhibitor, in combination with gemcitabine produces a small increase in survival. However, these results remain insufficient. The aim of this study was to investigate the molecular interplay in vitro between them regarding their effects over cytotoxicity, proliferation, apoptosis, and invasion.

METHODS

Using the human pancreatic cancer cell lines Panc-1 and BxPC-3 in vitro, the effects of gemcitabine and erlotinib therapy on growth, proliferation, and invasion were tested by cytotoxicity, cell cycle, and Annexin V-Fluorescein Isothiocyanate analysis, reverse transcription polymerase chain reaction, protein expression, and Chip assays.

RESULTS

Therapy decreased cell proliferation causing G0/G1 phase cell cycle arrest with induction of apoptosis in the Panc-1 cell line. This blockade was associated with increased p27 expression. Besides, treatments enhanced the nuclear factor-κB (NF-κB) pathway and the binding of NF-κB to the promoters of genes related to the proliferation and the evasion of apoptosis.

CONCLUSIONS

Our data suggest that, although gemcitabine and erlotinib exert antiproliferative effects over pancreatic cancer cell lines, the gemcitabine-induced activation of NF-κB expression and its DNA-binding activities are important drawbacks of this treatment against pancreatic cancer.

Thirty years of BCL-2: translating cell death discoveries into novel cancer therapies

The 'hallmarks of cancer' are generally accepted as a set of genetic and epigenetic alterations that a normal cell must accrue to transform into a fully malignant cancer. It follows that therapies designed to counter these alterations might be effective as anti-cancer strategies. Over the past 30 years, research on the BCL-2-regulated apoptotic pathway has led to the development of small-molecule compounds, known as 'BH3-mimetics', that bind to pro-survival BCL-2 proteins to directly activate apoptosis of malignant cells. This Timeline article focuses on the discovery and study of BCL-2, the wider BCL-2 protein family and, specifically, its roles in cancer development and therapy.

Ginsenoside Rg3 induces apoptosis in human multiple myeloma cells via the activation of Bcl-2-associated X protein

Ginsenoside Rg3 is one of the main constituents isolated from Panax ginseng, and exhibits cytotoxic effects against cancer cells. The present study aimed to investigate the effects of ginsenoside Rg3 on human multiple myeloma cells, and determine the underlying molecular mechanisms. The cells were exposed to ginsenoside Rg3 at various concentrations (0‑80 µM) for 48 h. A subsequent cell proliferation assay demonstrated that treatment with ginsenoside Rg3 resulted in a dose‑dependent inhibition of the proliferation of U266 and RPMI8226 cells. Furthermore, exposure to ginsenoside Rg3 led to a marked increase in the rate of apoptosis in the U266 cells, coupled with increased caspase‑3 activity. The ginsenoside Rg3‑treated cells also exhibited an elevation in the expression of B‑cell lymphoma 2‑associated X protein (Bax), a pro‑apoptotic protein. Notably, knockdown of Bax protected the U266 cells from Rg3‑induced apoptosis. Overall, these findings suggested that ginsenoside Rg3 induced apoptosis in multiple myeloma cells, at least partially, through upregulation of the expression of Bax.

Regulation of mitochondrial nutrient and energy metabolism by BCL-2 family proteins

Cells have evolved a highly integrated network of mechanisms to coordinate cellular survival/death, proliferation, differentiation, and repair with metabolic states. It is therefore not surprising that proteins with canonical roles in cell death/survival also modulate nutrient and energy metabolism and vice versa. The finding that many BCL-2 (B cell lymphoma 2) proteins reside at mitochondria or can translocate to this organelle has long motivated investigation into their involvement in normal mitochondrial physiology and metabolism. These endeavors have led to the discovery of homeostatic roles for BCL-2 proteins beyond apoptosis. We predominantly focus on recent findings that link select BCL-2 proteins to carbon substrate utilization at the level of mitochondrial fuel choice, electron transport, and metabolite import independent of their cell death regulatory function.

Xerophilusin B induces cell cycle arrest and apoptosis in esophageal squamous cell carcinoma cells and does not cause toxicity in nude mice

Esophageal cancer is the eighth most common cancer in the world and ranks as the sixth leading cause of cancer-related mortality. Esophageal cancer has a poor prognosis partially due to its low sensitivity to chemotherapy agents, and the development of new therapeutic agents is urgently needed. Here, the antitumor activity of a natural ent-kaurane diterpenoid, xerophilusin B (1), which was isolated from Isodon xerophilus, a perennial herb frequently used in Chinese folk medicine for tumor treatment, was investigated. Compound 1 exhibited antiproliferative effects against esophageal squamous cell carcinoma (ESCC) cell lines in a time- and dose-dependent manner with lower toxicity against normal human and murine cell lines. In vivo studies demonstrated that 1 inhibited tumor growth of a human esophageal tumor xenograft in BALB/c nude mice without significant secondary adverse effects, indicating its safety in treating ESCC. Furthermore, 1 induced G2/M cell cycle arrest and promoted apoptosis through mitochondrial cytochrome c-dependent activation of the caspase-9 and caspase-3 cascade pathway in ESCC cell lines. In conclusion, the observations herein reported showed that 1 is a potential chemotherapeutic agent for ESCC and merits further preclinical and clinical investigation for cancer drug development.

Lipid-dependent bimodal MCL1 membrane activity

Increasing evidence indicates that the mitochondrial lipid membrane environment directly modulates the BCL2 family protein function, but the underlying mechanisms are still poorly understood. Here, we used minimalistic reconstituted systems to examine the influence of mitochondrial lipids on MCL1 activity and conformation. Site-directed mutagenesis and fluorescence spectroscopic analyses revealed that the BCL2 homology region of MCL1 (MCL1ΔNΔC) inhibits permeabilization of MOM-like membranes exclusively via canonical BH3-into-groove interactions with both cBID-like activators and BAX-like effectors. Contrary to currently popular models, MCL1ΔNΔC did not require becoming embedded into the membrane to inhibit membrane permeabilization, and interaction with cBID was more productive for MCL1ΔNΔC inhibitory activity than interaction with BAX. We also report that membranes rich in cardiolipin (CL), but not phosphatidylinositol (PI), trigger a profound conformational change in MCL1ΔNΔC leading to membrane integration and unleashment of an intrinsic lipidic pore-forming activity of the molecule. Cholesterol (CHOL) reduces both the conformational change and the lipidic pore-forming activity of MCL1ΔNΔC in CL-rich membranes, but it does not affect the interaction of MCL1ΔNΔC with proapoptotic partners in MOM-like liposomes. In addition, we identified MCL1α5 as the minimal domain of the protein responsible for its membrane-permeabilizing function both in model membranes and at the mitochondrial level. Our results provide novel mechanistic insight into MCL1 function in the context of a membrane milieu and add significantly to a growing body of evidence supporting an active role of mitochondrial membrane lipids in BCL2 protein function.

Imaging cellular distribution of Bcl inhibitors using small molecule drug conjugates

Overexpression of anti-apoptotic proteins such as Bcl-2 is a cellular mechanism to evade apoptosis; consequently, Bcl-2 inhibitors are being developed as anticancer agents. In this work, we have synthesized a fluorescent version of ABT-199 in an effort to visualize a drug surrogate by high resolution imaging. We show that this fluorescent conjugate has comparable Bcl-2 binding efficacy and cell line potency to the parent compound and can be used as an imaging agent in several cancer cell types. We anticipate that this agent will be a valuable tool for studying the single-cell distribution and pharmacokinetics of ABT-199 as well the broader group of BH3-mimetics.

The evolving small-molecule fluorescent-conjugate toolbox for Class A GPCRs

The past decade has witnessed fluorescently tagged drug molecules gaining significant attraction in their use as pharmacological tools with which to visualize and interrogate receptor targets at the single-cell level. Additionally, one can generate detailed pharmacological information, such as affinity measurements, down to almost single-molecule detection limits. The now accepted utilization of fluorescence-based readouts in high-throughput/high-content screening provides further evidence that fluorescent molecules offer a safer and more adaptable substitute to radioligands in molecular pharmacology and drug discovery. One such drug-target family that has received considerable attention are the GPCRs; this review therefore summarizes the most recent developments in the area of fluorescent ligand design for this important drug target. We assess recently reported fluorescent conjugates by adopting a receptor-family-based approach, highlighting some of the strengths and weaknesses of the individual molecules and their subsequent use. This review adds further strength to the arguments that fluorescent ligand design and synthesis requires careful planning and execution; providing examples illustrating that selection of the correct fluorescent dye, linker length/composition and geographic attachment point to the drug scaffold can all influence the ultimate selectivity and potency of the final conjugate when compared with its unlabelled precursor. When optimized appropriately, the resultant fluorescent conjugates have been successfully employed in an array of assay formats, including flow cytometry, fluorescence microscopy, FRET and scanning confocal microscopy. It is clear that fluorescently labelled GPCR ligands remain a developing and dynamic research arena.

Peptides derived from the transmembrane domain of Bcl-2 proteins as potential mitochondrial priming tools

The Bcl-2 family of proteins is crucial for apoptosis regulation. Members of this family insert through a specific C-terminal anchoring transmembrane domain (TMD) in the mitochondrial outer membrane where they hierarchically interact to determine cell fate. While the mitochondrial membrane has been proposed to actively participate in these protein-protein interactions, the influence of the TMD in the membrane-mediated interaction is poorly understood. Synthetic peptides (TMD-pepts) corresponding to the putative TMD of antiapoptotic (Bcl-2, Bcl-xL, Bcl-w, and Mcl-1) and pro-apoptotic (Bax, Bak) members were synthesized and characterized. TMD-pepts bound more efficiently to mitochondria-like bilayers than to plasma membrane-like bilayers, and higher binding correlated with greater membrane perturbation. The Bcl-2 TMD peptides promoted mitochondrial outer membrane permeabilization (MOMP) and cytochrome c release from isolated mitochondria and different cell lines. TMD-pepts exhibited nonapoptotic pro-death activity when apoptosis stimuli were absent. In addition, the peptides enhanced the apoptotic pathway induced by chemotherapeutic agents in cotreatment. Overall, the membrane perturbation effects of the TMD-pepts observed in the present study open the way for their use as new chemical tools to sensitize tumor cells to chemotherapeutic agents, in accordance with the concept of mitochondria priming.

Up-regulation of eEF1A2 promotes proliferation and inhibits apoptosis in prostate cancer

BACKGROUND

eEF1A2 is a protein translation factor involved in protein synthesis, which possesses important function roles in cancer development. This study aims at investigating the expression pattern of eEF1A2 in prostate cancer and its potential role in prostate cancer development.

METHODS

We examined the expression level of eEF1A2 in 30 pairs of prostate cancer tissues by using RT-PCR and immunohistochemical staining (IHC). Then we applied siRNA specifically targeting eEF1A2 to down-regulate its expression in DU-145 and PC-3 cells. Flow cytometer was used to explore apoptosis and Western-blot was used to detect the pathway proteins of apoptosis.

RESULTS

Our results showed that the expression level of eEF1A2 in prostate cancer tissues was significantly higher compared to their corresponding normal tissues. Reduction of eEF1A2 expression in DU-145 and PC-3 cells led to a dramatic inhibition of proliferation accompanied with enhanced apoptosis rate. Western blot revealed that apoptosis pathway proteins (caspase3, BAD, BAX, PUMA) were significantly up-regulated after suppression of eEF1A2. More importantly, the levels of eEF1A2 and caspase3 were inversely correlated in prostate cancer tissues.

CONCLUSION

Our data suggests that eEF1A2 plays an important role in prostate cancer development, especially in inhibiting apoptosis. So eEF1A2 might serve as a potential therapeutic target in prostate cancer.

Patients with tuberculosis disease have Mycobacterium tuberculosis-specific CD8 T cells with a pro-apoptotic phenotype and impaired proliferative capacity, which is not restored following treatment

CD8 T cells play a critical role in control of chronic viral infections; however, the role of these cells in containing persistent bacterial infections, such as those caused by Mycobacterium tuberculosis (Mtb), is less clear. We assessed the phenotype and functional capacity of CD8 T cells specific for the immunodominant Mtb antigens CFP-10 and ESAT-6, in patients with pulmonary tuberculosis (TB) disease, before and after treatment, and in healthy persons with latent Mtb infection (LTBI). In patients with TB disease, CFP-10/ESAT-6-specific IFN-γ+ CD8 T cells had an activated, pro-apoptotic phenotype, with lower Bcl-2 and CD127 expression, and higher Ki67, CD57, and CD95 expression, than in LTBI. When CFP-10/ESAT-6-specific IFN-γ+ CD8 T cells were detectable, expression of distinct combinations of these markers was highly sensitive and specific for differentiating TB disease from LTBI. Successful treatment of disease resulted in changes of these markers, but not in restoration of CFP-10/ESAT-6-specific CD8 or CD4 memory T cell proliferative capacity. These data suggest that high mycobacterial load in active TB disease is associated with activated, short-lived CFP-10/ESAT-6-specific CD8 T cells with impaired functional capacity that is not restored following treatment. By contrast, LTBI is associated with preservation of long-lived CFP-10/ESAT-6-specific memory CD8 T cells that maintain high Bcl-2 expression and which may readily proliferate.

Vandetanib-induced phototoxicity in human keratinocytes NCTC-2544

The phototoxicity of the new anticancer drug vandetanib was evaluated using human keratinocyte cell line, NCTC-2544. This study was started since many clinical cases of vandetanib photosensitizing reactions were recently reported in literature. Vandetanib induces a clear drop in human keratinocytes viability after cell irradiation in concentration and UV-A dose dependent mode. Since vandetanib can photolyze with the formation of two main photoproducts after UV-A exposure, the contribution of these new species was also evaluated. These two photoproducts did not have a main role in the phototoxicity of their parent drug. In our opinion, the main hypothesis for the vandetanib phototoxic potential is the formation of a very reactive specie, such as an aryl radical, which can react promptly with different targets inside the cells. In fact, a massive DNA photodamage was detected both in the in vitro DNA photocleavage experiments, and in cells. Moreover, vandetanib was able to photoinduce lipid peroxidation and protein oxidations. Vandetanib photoinduced cell death by apoptosis with the involvement of mitochondria and lysosomes.

Gypenoside attenuates hepatic ischemia/reperfusion injury in mice via anti-oxidative and anti-apoptotic bioactivities

Gynostemma pentaphyllum is a traditional Chinese medicine that has previously been used for the treatment of chronic inflammation, hyperlipidemia and liver disease. Gypenoside (GP), the predominant component of Gynostemma pentaphyllum, exhibits a therapeutic effect on chronic hepatic injury, fibrosis and fatty liver disease via its anti-inflammatory and anti-oxidant activity. However, the effect of GP on ischemia/reperfusion (I/R)-induced hepatic injury has, to the best of our knowledge, not previously been investigated. In the present study, a hepatic I/R-injury model was successfully established using C57BL/6 mice. In the treatment group, 50 mg/kg GP was administered orally 1 h prior to ischemia. Following hepatic I/R, the levels of hepatic lipid peroxidation and serum alanine aminotransferase increased, while the ratio of hepatic glutathione (GSH):oxidized GSH was reduced, which was effectively attenuated by pretreatment with GP. Furthermore, an increased protein expression of heme oxygenase-1 in the liver tissues of the I/R mice was attenuated by the administration of GP. In addition, the present study indicated that treatment with GP suppressed the I/R-induced increase in the pro-apoptotic protein levels of Bax and cytochrome c and the activity of caspase-3/8, as well as the I/R-induced decrease in the levels of anti-apoptotic protein Bcl-2. In conclusion, the present study indicated that GP effectively protected against I/R-induced hepatic injury via its anti-oxidative and anti-apoptotic bioactivity.

Control of apoptosis by the BCL-2 protein family: implications for physiology and therapy

The BCL-2 protein family determines the commitment of cells to apoptosis, an ancient cell suicide programme that is essential for development, tissue homeostasis and immunity. Too little apoptosis can promote cancer and autoimmune diseases; too much apoptosis can augment ischaemic conditions and drive neurodegeneration. We discuss the biochemical, structural and genetic studies that have clarified how the interplay between members of the BCL-2 family on mitochondria sets the apoptotic threshold. These mechanistic insights into the functions of the BCL-2 family are illuminating the physiological control of apoptosis, the pathological consequences of its dysregulation and the promising search for novel cancer therapies that target the BCL-2 family.