Mitochondrial ROS and involvement of Bcl-2 as a mitochondrial ROS regulator

Design and synthesis of novel SCM-198 analogs as cardioprotective agents: Structure-activity relationship studies and biological evaluations

SCM-198 (Leonurine) has attracted great attention due to its cardioprotective effects in myocardial infarction (MI). However, no systematic modifications and structure-activity relationship (SAR) studies could be traced so far. In this study, 35 analogs of SCM-198 were designed, synthesized and their cardioprotective effects were evaluated. The cell viability assay on cardiomyocyte cell line H9c2 challenged with H₂O₂ showed that several analogs exhibited more potent cytoprotective effects than SCM-198 at 1 μM and 10 μM concentrations. LDH release level in cells treated with 1 μM 14o was comparable with cells treated with 10 μM SCM-198. Results of Bcl-2 expression and caspase-3 activation accordingly indicated higher protective activity of 14o than SCM-198. Moreover, in a mouse model of MI, the mice pretreated with 14o had much lower infarct size compared with that of SCM-198. The mechanism study suggested that 14o improved cardiac morphology and reduced apoptosis of cardiomyocytes in the border zone of infarction, as proved by H&E and TUNEL staining.

Mitochondrial superoxide/hydrogen peroxide: An emerging therapeutic target for metabolic diseases

Mitochondria are well known for their roles as energy and metabolic factory. Mitochondrial reactive oxygen species (mtROS) refer to superoxide anion radical (^•O₂^-) and hydrogen peroxide (H₂O₂). They are byproducts of electron transport in mitochondrial respiratory chain and are implicated in the regulation of physiological and pathological signal transduction. Especially when mitochondrial ^•O₂^-/H₂O₂ production is disturbed, this disturbance is closely related to the occurrence and development of metabolic diseases. In this review, the sources of mitochondrial ^•O₂^-/H₂O₂ as well as mitochondrial antioxidant mechanisms are summarized. Furthermore, we particularly emphasize the essential role of mitochondrial ^•O₂^-/H₂O₂ in metabolic diseases. Specifically, perturbed mitochondrial ^•O₂^-/H₂O₂ regulation aggravates the progression of metabolic diseases, including diabetes, gout and nonalcoholic fatty liver disease (NAFLD). Given the deleterious effect of mitochondrial ^•O₂^-/H₂O₂ in the development of metabolic diseases, antioxidants targeting mitochondrial ^•O₂^-/H₂O₂ might be an attractive therapeutic approach for the prevention and treatment of metabolic diseases.

Akkermansia muciniphila Aspartic Protease Amuc_1434* Inhibits Human Colorectal Cancer LS174T Cell Viability via TRAIL-Mediated Apoptosis Pathway

Mucin2 (Muc2) is the main component of the intestinal mucosal layer and is highly expressed in mucous colorectal cancer. Previous studies conducted by our lab found that the recombinant protein Amuc_1434 (expressed in Escherichia coli prokaryote cell system, hereinafter termed Amuc_1434*), derived from Akkermansia muciniphila, can degrade Muc2. Thus, the main objective of this study was to explore the effects of Amuc_1434* on LS174T in colorectal cancer cells expressing Muc2. Results from this study demonstrated that Amuc_1434* inhibited the proliferation of LS174T cells, which was related to its ability to degrade Muc2. Amuc_1434* also blocked the G0/G1 phase of the cell cycle of LS174T cells and upregulated the expression of tumor protein 53 (p53), which is a cell cycle-related protein. In addition, Amuc_1434* promoted apoptosis of LS174T cells and increased mitochondrial ROS levels in LS174T cells. The mitochondrial membrane potential of LS174T cells was also downregulated by Amuc_1434*. Amuc_1434* can activate the death receptor pathway and mitochondrial pathway of apoptosis by upregulating tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL). In conclusion, our study was the first to demonstrate that the protein Amuc_1434* derived from Akkermansia muciniphila suppresses LS174T cell viability via TRAIL-mediated apoptosis pathway.

Circular RNA has_circ_0000527 participates in proliferation, invasion and migration of retinoblastoma cells via miR-646/BCL-2 axis

Retinoblastoma (RB) is one of the most common primary intraocular malignancies in children. Emerging researches have shown that circular RNAs (circRNAs) play critical roles in a variety of cancers. As a novel circRNA, the function of circ_0000527 in RB remains unknown. In this work, expression level of circ_0000527 and miR-646 in RB tissues and cell lines were detected by quantitative real-time polymerase chain reaction (qRT-PCR). RB cell lines (SO-Rb50 and WERI-Rb-1) were used as cell models in functional experiments. CCK-8 assay, TUNEL assay and transwell assay were employed to detect the biological influence of circ_0000527 and miR-646 on cancer cells in vitro. qRT-PCR, luciferase reporter assay, RIP assay and western blot were used for exploring the interactions among circ_0000527, miR-646 and BCL-2. It was demonstrated that expression level of circ_0000527 in RB samples was significantly up-regulated compared to normal tissues, while miR-646 was markedly down-regulated. Overexpression of circ_0000527 promoted the viability, migration and invasion of RB cells, while miR-646 transfection had the opposite effects. Circ_0000527 sponged miR-646 to regulate the expression of BCL-2. In conclusion, circ_0000527 could promote the development of RB by indirectly modulating BCL-2 via absorbing miR-646. SIGNIFICANCE OF THE STUDY: Expression level of circ_0000527 in RB samples was significantly up-regulated compared to normal tissues, while miR-646 was markedly down-regulated. Overexpression of circ_0000527 promoted the viability, migration and invasion of RB cells, while miR-646 transfection had the opposite effects. Circ_0000527 sponged miR-646 to regulate the expression of BCL-2.

Do genetic polymorphisms of B-cell CLL/lymphoma 2 confer susceptibility to anti-tuberculous therapy-associated drug-induced liver injury?

OBJECTIVES

The aim of this study was to identify the relationship between B-cell CLL/lymphoma 2 (BCL2) polymorphisms and susceptibility to anti-tuberculous therapy-associated drug-induced liver injury (ATT-DILI).

METHODS

A total of 746 tuberculosis (TB) patients were enrolled in this study. Twenty-one selected single nucleotide polymorphisms in BCL2 were analyzed by custom-by-design 2×48-Plex SNPscan kit. The allele and genotype frequencies between patients with and without ATT-DILI were compared using three different genetic models.

RESULTS

A total of 727/746 participants were successfully genotyped, and 112 of them were diagnosed with ATT-DILI. The A allele of rs8085707, G allele of rs76986960, and A allele of rs949037 conferred an increased risk of ATT-DILI, with estimated odd ratios (ORs) of 2.181 (95% confidence interval (CI) 1.345-3.536, p=0.001), 1.983 (95% CI 1.060-3.709, p=0.029), and 1.390 (95% CI 1.032-1.873, p=0.03), respectively. Bonferroni correction indicated that the A allele of rs8085707 was a risk factor for ATT-DILI (Bonferroni correction: p=0.026). The additive model suggested that patients with the AA genotype of rs8085707 had a significantly higher risk of ATT-DILI compared with those with the GG genotype (Bonferroni correction: p=0.036). The influence of BCL2 polymorphisms on clinical characteristics (clinical symptoms, disease subtypes, and laboratory indicators) was also identified.

CONCLUSIONS

This study is novel in suggesting an association between BCL2 polymorphisms and the risk of ATT-DILI.

Improvement of cognitive and motor performance with mitotherapy in aged mice

Changes in mitochondrial structure and function are mostly responsible for aging and age-related features. Whether healthy mitochondria could prevent aging is, however, unclear. Here we intravenously injected the mitochondria isolated from young mice into aged mice and investigated the mitotherapy on biochemistry metabolism and animal behaviors. The results showed that heterozygous mitochondrial DNA (mtDNA) of both aged and young mouse coexisted in tissues of aged mice after mitochondrial administration, and meanwhile, ATP content in tissues increased while reactive oxygen species (ROS) level reduced. Besides, the mitotherapy significantly improved cognitive and motor performance of aged mice. Our study, at the first report in aged animals, not only provides a useful approach to study mitochondrial function associated with aging, but also a new insight into anti-aging through mitotherapy.

The Anti-Proliferative Activity of the Hybrid TMS-TMF-4f Compound Against Human Cervical Cancer Involves Apoptosis Mediated by STAT3 Inactivation

We previously reported the potential anti-proliferative activity of 3-(5,6,7-trimethoxy-4-oxo-4H-chromen-2-yl)-N-(3,4,5-trimethoxyphenyl) benzamide (TMS-TMF-4f) against human cancer cells; however, the underlying molecular mechanisms have not been investigated. In the present study, TMS-TMF-4f showed the highest cytotoxicity in human cervical cancer cells (HeLa and CaSki) and low cytotoxicity in normal ovarian epithelial cells. Annexin V-FITC and propidium iodide (PI) double staining revealed that TMS-TMF-4f-induced cytotoxicity was caused by the induction of apoptosis in both HeLa and CaSki cervical cancer cells. The compound TMS-TMF-4f enhanced the activation of caspase-3, caspase-8, and caspase-9 and regulated Bcl-2 family proteins, which led to mitochondrial membrane potential (MMP) loss and resulted in the release of cytochrome c and Smac/DIABLO into the cytosol. Also, TMS-TMF-4f suppressed both constitutive and IL-6-inducible levels of phosphorylated STAT3 (p-STAT3) and associated proteins such as Mcl-1, cyclin D1, survivin, and c-Myc in both cervical cancer cells. STAT-3 overexpression completely ameliorated TMS-TMF-4f-induced apoptotic cell death and PARP cleavage. Docking analysis revealed that TMS-TMF-4f could bind to unphosphorylated STAT3 and inhibit its interconversion to the activated form. Notably, intraperitoneal administration of TMS-TMF-4f (5, 10, or 20 mg/kg) decreased tumor growth in a xenograft cervical cancer mouse model, demonstrated by the increase in TUNEL staining and PARP cleavage and the reduction in p-STAT3, Mcl-1, cyclin D1, survivin, and c-Myc expression levels in tumor tissues. Taken together, our results suggest that TMS-TMF-4f may potentially inhibit human cervical tumor growth through the induction of apoptosis via STAT3 suppression.

Targets and mechanisms of sulforaphane derivatives obtained from cruciferous plants with special focus on breast cancer - contradictory effects and future perspectives

Breast cancer is the most common type of cancer among women. Therefore, discovery of new and effective drugs with fewer side effects is necessary to treat it. Sulforaphane (SFN) is an organosulfur compound obtained from cruciferous plants, such as broccoli and mustard, and it has the potential to treat breast cancer. Hence, it is vital to find out how SFN targets certain genes and cellular pathways in treating breast cancer. In this review, molecular targets and cellular pathways of SFN are described. Studies have shown SFN inhibits cell proliferation, causes apoptosis, stops cell cycle and has anti-oxidant activities. Increasing reactive oxygen species (ROS) produces oxidative stress, activates inflammatory transcription factors, and these result in inflammation leading to cancer. Increasing anti-oxidant potential of cells and discovering new targets to reduce ROS creation reduces oxidative stress and it eventually reduces cancer risks. In short, SFN effectively affects histone deacetylases involved in chromatin remodeling, gene expression, and Nrf2 anti-oxidant signaling. This review points to the potential of SFN to treat breast cancer as well as the importance of other new cruciferous compounds, derived from and isolated from mustard, to target Keap1 and Akt, two key regulators of cellular homeostasis.

Differential redox-regulation and mitochondrial dynamics in normal and leukemic hematopoietic stem cells: A potential window for leukemia therapy

The prognosis for many patients with acute myeloid leukemia (AML) is poor, mainly due to disease relapse driven by leukemia stem cells (LSCs). Recent studies have highlighted the unique metabolic properties of LSCs, which might represent opportunities for LSC-selective targeting. LSCs characteristically have low levels of reactive oxygen species (ROS), which apparently result from a combination of low mitochondrial activity and high activity of ROS-removing pathways such as autophagy. Due to this low activity, LSCs are highly dependent on mitochondrial regulatory mechanisms. These include the anti-apoptotic protein BCL-2, which also has crucial roles in regulating the mitochondrial membrane potential, and proteins involved in mitophagy. Here we review the different pathways that impact mitochondrial activity and redox-regulation, and highlight their relevance for the functionality of both HSCs and LSCs. Additionally, novel AML therapy strategies that are based on interference with those pathways, including the promising BCL-2 inhibitor Venetoclax, are summarized.

A Novel Indolizine Derivative Induces Apoptosis Through the Mitochondria p53 Pathway in HepG2 Cells

Indolizine derivatives are a class of compounds with excellent biological activity. In this study, a series of indolizine derivatives, compound 1 (C1), compound 2 (C2), compound 3 (C3), and compound 4 (C4), were synthesized. 3-(4,5-dimethylthiazole)-2,5-diphenyltetraazolium bromide (MTT) assay was used to evaluate their cytotoxicity against HepG2 (p53-wild), A549, and HeLa cell lines. HepG2 cells apoptosis induced by C3 was determined using Hoechst staining and acridine orange/ethidium bromide staining. Cells’ apoptotic ratio was measured by Annexin V–FITC/PI double staining. Changes in mitochondrial membrane potential and intracellular reactive oxygen species (ROS) in HepG2 cells after C3 treatment were determined. Immunofluorescence staining and Western blot analysis were carried out to detect p53 levels and analyze the apoptosis-associated proteins, respectively. Moreover, the cytotoxic activity of C3 was examined in two other hepatocellular carcinoma (HCC) cell lines with different p53 status including Huh-7 cells (p53-mutant) and Hep3B cells (p53-null). The results indicated that C3 showed stronger inhibition towards HepG2 cells than other cell lines. Fluorescent staining and flow cytometry analysis confirmed that C3 induced apoptosis of HepG2 cells. C3 could also increase intracellular ROS and cause a decrease in the mitochondrial membrane potential. C3 promoted p53 activation and increased p53 accumulation in nuclei. The expression of p53 and Bax was increased with the down-regulation of Bcl-2, which promoted the release of cytochrome c and caspase-3 activation. Collectively, the study demonstrated that C3 caused HepG2 cell apoptosis via the mitochondria p53 pathway. These results inspired us to further develop indolizine derivatives as potential potent inhibitors against liver cancer.

Identification of a Novel Bcl-2 Inhibitor by Ligand-Based Screening and Investigation of Its Anti-cancer Effect on Human Breast Cancer Cells

Bcl-2 family protein is an important factor in regulating apoptosis and is associated with cancer. The anti-apoptotic proteins of Bcl-2 family, such as Bcl-2, are overexpression in numerous tumors, and contribute to cancer formation, development, and therapy resistance. Therefore, Bcl-2 is a promising target for drug development, and several Bcl-2 inhibitors are currently undergoing clinical trials. In this study, we carried out a QSAR-based virtual screening approach to develop potential Bcl-2 inhibitors from the SPECS database. Surface plasmon resonance (SPR) binding assay was performed to examine the interaction between Bcl-2 protein and the screened inhibitors. After that, we measured the anti-tumor activities of the 8 candidate compounds, and found that compound M1 has significant cytotoxic effect on breast cancer cells. We further proved that compound M1 downregulated Bcl-2 expression and activated apoptosis by inducing mitochondrial dysfunction. In conclusion, we identified a novel Bcl-2 inhibitor by QSAR screening, which exerted significant cytotoxic activity in breast cancer cells through inducing mitochondria-mediated apoptosis.

Trametenolic acid B protects against cerebral ischemia and reperfusion injury through modulation of microRNA-10a and PI3K/Akt/mTOR signaling pathways

Trametenolic acid B (TAB) was a lanostane-type triterpenoid isolated from the trametes lactinea (Berk.) Pat. We have previously reported that extract from trametes lactinea (Berk.) Pat and TAB could efficiently improve learning and memory ability of the cerebral ischemia injury rats and suppress mitochondrial-mediated apoptosis in hydrogen peroxide damaged SH-SY5Y cells. However, the potential mechanisms have not been fully understood yet. The current study was to further investigate the protective effect of TAB on oxygen glucose deprivation/reoxygenation (OGD/R)-damaged SH-SY5Y cells and cerebral ischemia/reperfusion (I/R) injury rats, as well as its mechanisms involved. Cell experiments demonstrated that TAB (10, 20 and 40 μg/mL) protected OGD/R-induced SH-SY5Y cell injury by promoting cell proliferation and suppressing LDH leakage; Meanwhile, the results in vivo showed that TAB (20, 40 and 80 mg/kg) might significantly ameliorate the neurological deficit score, cerebral edema, neuronal cell loss and apoptosis, suppress cerebral infarction volume of the cerebral I/R injury rats. Further studies in vitro and in vivo indicated TAB could efficiently reduce OGD/R-damaged SH-SY5Y cell and cerebral I/R rat serum ROS, LDH and MDA levels, elevate SOD, GSH-Px and CAT activities, downregulate miR-10a mRNA and Bax, cytochrome C, cleaved-caspase-3 and cleaved-caspase-9 protein expressions, upregulate p-PIK3CA, p-Akt, p-mTOR, Bcl-2, pro-caspase-9 and pro-caspase-3 protein expressions and p-PIK3CA/PIK3CA, p-Akt/Akt, p-mTOR/mTOR ratios (P < 0.05 or P < 0.01, respectively). Our present study indicated that TAB possessed neuroprotective property against ODG/R and I/R injury by suppressing miR-10a expression, activating PI3K/Akt/mTOR signaling pathway, thereby reducing mitochondrial-mediated apoptosis, which provided a new insight for interpreting the underlying mechanisms of TAB' neuroprotective effect and a candidate agent to treat cerebral I/R injury.

The Bcl-2 inhibitor venetoclax inhibits Nrf2 antioxidant pathway activation induced by hypomethylating agents in AML

Induction of reactive oxygen species (ROS), an important process for the cytotoxicity of various acute myeloid leukemia (AML) therapies including hypomethylating agents (HMAs), concurrently activates the NF-E2-related factor 2 (Nrf2) antioxidant response pathway which in turn results in induction of antioxidant enzymes that neutralize ROS. In this study, we demonstrated that Nrf2 inhibition is an additional mechanism responsible for the marked antileukemic activity in AML seen with the combination of HMAs and venetoclax (ABT-199). HMA and venetoclax combined treatment augmented mitochondrial ROS induction and apoptosis compared with treatment HMA alone. Treatment of AML cell lines as well as primary AML cells with venetoclax disrupted HMA decitabine-increased nuclear translocation of Nrf2 and induction of downstream antioxidant enzymes including heme oxygenase-1 and NADP-quinone oxidoreductase-1. Venetoclax treatment also leads to dissociation of B-cell lymphoma 2 from the Nrf2/Keap-1 complex and targets Nrf2 to ubiquitination and proteasomal degradation. Thus, our results here demonstrated an undiscovered mechanism underlying synergistic effect of decitabine and venetoclax in AML cells, elucidating for impressive results in antileukemic activity against AML in preclinical and early clinical studies by combined treatment of these drugs.

Enhanced combination cancer therapy using lipid-calcium carbonate/phosphate nanoparticles as a targeted delivery platform

Aim: Melanoma, the most life-threatening skin cancer, requires more effective therapies. Methodology: A new folic acid (FA) receptor-targeted lipid-coated calcium carbonate/phosphate (LCCP) nanoparticle was synthesized, incorporating two often-used therapeutics, cell death siRNA and α-tocopheryl succinate. Results: The nanoparticles were spherical, with an average size of 40 nm. The nanoparticles exhibited a high gene/drug loading efficiency (60%), with folic acid-enhanced cellular uptake. The nanoparticles with both therapeutics enhanced inhibition of B16F0 melanoma cell growth, showing a moderate synergistic effect. The mechanism of the inhibition is associated with induction of cell apoptosis and cell cycle arrest at G1 phase. Conclusion: Our data indicate that lipid-coated calcium carbonate/phosphate nanoparticles are a potential platform for targeted therapy for melanoma.

Reactive Oxygen Species Are Necessary for Bleomycin A5-Induced Apoptosis and Extracellular Matrix Elimination of Nasal Polyp-Derived Fibroblasts

BACKGROUND:

The pathology of chronic rhinosinusitis with nasal polyp (CRSwNP) is characterized by the infiltration of a large number of fibroblasts, resulting in extracellular matrix (ECM) deposition. Intralesional bleomycin A5 (BLE) injection has proved to be effective and safe, providing a novel treatment for CRSwNP. However, the mechanism is not clearly understood.

OBJECTIVES:

The aim of this study is to explore the possible mechanism of BLE-induced apoptosis in nasal polyp-derived fibroblasts (NPDFs).

MATERIAL AND METHODS:

Dichloro-dihydro-fluorescein diacetate probe, cell migration assays, and cell cycle analysis were used to detect the growth characteristics and basal reactive oxygen species (ROS) traits of NPDFs. Annexin V/propidium iodide and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to detect BLE-induced apoptosis. As a control, the antioxidant glutathione (GSH) was used to abrogate ROS induced by BLE. Western blot analysis was used to evaluate the effects of BLE on apoptosis and the ECM proteins of NPDFs.

RESULTS:

The results showed that NPDFs had more active growth characteristics and higher basal ROS levels than normal nasal mucosa fibroblasts (NMFCs). NPDFs were more sensitive to BLE-induced apoptosis and ROS accumulation. GSH abrogation inhibits BLE-induced ECM degradation and apoptosis in NPDFs through a mitochondrial-mediated pathway.

CONCLUSIONS:

BLE induced NPDF apoptosis and ECM degradation through a mitochondrial-mediated pathway and in a ROS-dependent manner.

TRIM32 overexpression improves chemoresistance through regulation of mitochondrial function in non-small-cell lung cancers

Background

TRIM32 is overexpressed in several human cancers. However, its expression pattern, biological characteristics and mechanisms in human non-small cell lung cancer (NSCLC) have not been reported.

Methods

We examined TRIM32 protein in 115 cases of NSCLC specimens. TRIM32 plasmid transfection and siRNA knockdown was carried out in NSCLC cell lines. AnnexinV/PI and JC-1 staining were performed to examine the change of apoptosis and mitochondrial membrane potential. Western blot was used to detect change of downstream proteins.

Results

We found that TRIM32 protein was upregulated in 69 cases and positively correlated with advanced TNM stage. TRIM32 overexpression also correlated with poor survival of NSCLC patients. Biological assays demonstrated that TRIM32 overexpression promoted while it depletion inhibited cell growth, colony formation and invasion. In addition, TRIM32 maintained NSCLC cell viability and reduced apoptosis when treated with cisplatin. JC-1 and CellRox staining demonstrated that TRIM32 could maintain mitochondrial membrane potential and reduce Reactive Oxygen Species (ROS) production after cisplatin treatment. Western blot analysis showed that TRIM32 overexpression downregulated caspase 3 cleavage and cytochrome c release. TRIM32 also positively regulated Bcl-2 protein expression and NF-κB signaling. Inhibition of NF-κB abolished the effects of TRIM32 on Bcl-2.

Conclusion

Taken together, our results indicated that TRIM32 is overexpressed in NSCLC and regulates cisplatin resistance, possibly through NF-κB and Bcl-2.

Cross Talk Between Cellular Redox State and the Antiapoptotic Protein Bcl-2

SIGNIFICANCE

B cell lymphoma-2 (Bcl-2) was discovered over three decades ago and is the prototype antiapoptotic member of the Bcl-2 family that comprises proteins with contrasting effects on cell fate. First identified as a consequence of chromosomal translocation (t 14:18) in human lymphoma, subsequent studies have revealed mutations and/or gene copy number alterations as well as post-translational modifications of Bcl-2 in a variety of human cancers. The canonical function of Bcl-2 is linked to its ability to inhibit mitochondrial membrane permeabilization, thereby regulating apoptosome assembly and activation by blocking the cytosolic translocation of death amplification factors. Of note, the identification of specific domains within the Bcl-2 family of proteins (Bcl-2 homology domains; BH domains) has not only provided a mechanistic insight into the various interactions between the member proteins but has also been the impetus behind the design and development of small molecule inhibitors and BH3 mimetics for clinical use. Recent Advances: Aside from its role in maintaining mitochondrial integrity, recent evidence provides testimony to a novel facet in the biology of Bcl-2 that involves an intricate cross talk with cellular redox state. Bcl-2 overexpression modulates mitochondrial redox metabolism to create a "pro-oxidant" milieu, conducive for cell survival. However, under states of oxidative stress, overexpression of Bcl-2 functions as a redox sink to prevent excessive buildup of reactive oxygen species, thereby inhibiting execution signals. Emerging evidence indicates various redox-dependent transcriptional changes and post-translational modifications with different functional outcomes.

CRITICAL ISSUES

Understanding the complex interplay between Bcl-2 and the cellular redox milieu from the standpoint of cell fate signaling remains vital for a better understanding of pathological states associated with altered redox metabolism and/or aberrant Bcl-2 expression.

FUTURE DIRECTIONS

Based on its canonical functions, Bcl-2 has emerged as a potential druggable target. Small molecule inhibitors of Bcl-2 and/or other family members with similar function, as well as BH3 mimetics, are showing promise in the clinic. The emerging evidence for the noncanonical activity linked to cellular redox metabolism provides a novel avenue for the design and development of diagnostic and therapeutic strategies against cancers refractory to conventional chemotherapy by the overexpression of this prosurvival protein.

Origin and Consequences of Necroinflammation

When cells undergo necrotic cell death in either physiological or pathophysiological settings in vivo, they release highly immunogenic intracellular molecules and organelles into the interstitium and thereby represent the strongest known trigger of the immune system. With our increasing understanding of necrosis as a regulated and genetically determined process (RN, regulated necrosis), necrosis and necroinflammation can be pharmacologically prevented. This review discusses our current knowledge about signaling pathways of necrotic cell death as the origin of necroinflammation. Multiple pathways of RN such as necroptosis, ferroptosis, and pyroptosis have been evolutionary conserved most likely because of their differences in immunogenicity. As the consequence of necrosis, however, all necrotic cells release damage associated molecular patterns (DAMPs) that have been extensively investigated over the last two decades. Analysis of necroinflammation allows characterizing specific signatures for each particular pathway of cell death. While all RN-pathways share the release of DAMPs in general, most of them actively regulate the immune system by the additional expression and/or maturation of either pro- or anti-inflammatory cytokines/chemokines. In addition, DAMPs have been demonstrated to modulate the process of regeneration. For the purpose of better understanding of necroinflammation, we introduce a novel classification of DAMPs in this review to help detect the relative contribution of each RN-pathway to certain physiological and pathophysiological conditions.

Dihydroartemisinin potentiates antitumor activity of 5-fluorouracil against a resistant colorectal cancer cell line

Although the combination of chemotherapy and surgical resection has effectively increased the survival rate of colorectal cancer patients in recent decades, acquired drug resistance is still a problem that leads to treatment failure. Dihydroartemisinin (DHA), a semisynthetic derivative of artemisinin, has recently been reported to show anticancer effects against numerous types of cancer, including colorectal cancer. This study showed that DHA exerted a strong anticancer effect against several colorectal cancer cell lines. We also found that p53 knockout colorectal cancer HCT116 cells (HCT116 TP53^-/-) were not sensitive to 5-fluorouracil (5-FU) treatment, unlike wild-type HCT116 cells. Interestingly, co-treatment with DHA could effectively restore the anticancer effect of 5-FU against HCT116 TP53^-/- cells, which manifested as the inhibition of proliferation and induction of reactive oxygen species (ROS)-mediated apoptosis and was accompanied by the upregulation of B-cell lymphoma 2 (BCL-2) and downregulation of the BCL-2-associated X protein (BAX). These findings suggested that DHA could effectively sensitize cells to 5-FU through ROS-mediated apoptosis and the alteration of the BCL-2/BAX expression ratio, which indicated that this may be one of the mechanisms of the DHA-promoted 5-FU anticancer effect.

Eukaryotic cell survival mechanisms: Disease relevance and therapeutic intervention

Cell responds to stress by activating various modes of stress responses which aim for minimal damage to cells and speedy recovery from the insults. However, unresolved stresses exceeding the tolerance limit lead to cell death (apoptosis, autophagy etc.) that helps to get rid of damaged cells and protect cell integrity. Furthermore, aberrant stress responses are the hallmarks of several pathophysiologies (neurodegeneration, metabolic diseases, cancer etc.). The catastrophic remodulation of stress responses is observed in cancer cells in favor of their uncontrolled growth. Whereas pro-survival stress responses redirected to death signaling provokes excessive cell death in neurodegeneration. Clear understanding of such mechanistic link to disease progression is required in order to modulate these processes for new therapeutic targets. The current review explains this with respect to novel drug discoveries and other breakthroughs in therapeutics.

Gallic Acid Protects 6-OHDA Induced Neurotoxicity by Attenuating Oxidative Stress in Human Dopaminergic Cell Line

Gallic acid is one of the most important polyphenolic compounds, which is considered an excellent free radical scavenger. 6-Hydroxydopamine (6-OHDA) is a neurotoxin, which has been implicated in mainly Parkinson's disease (PD). In this study, we investigated the molecular mechanism of the neuroprotective effects of gallic acid on 6-OHDA induced apoptosis in human dopaminergic cells, SH-SY5Y. Our results showed that 6-OHDA induced cytotoxicity in SH-SY5Y cells was suppressed by pre-treatment with gallic acid. The percentage of live cells (90%) was high in the pre-treatment of gallic acid when compared with 6-OHDA alone treated cell line. Moreover, gallic acid was very effective in attenuating the disruption of mitochondrial membrane potential, elevated levels of intracellular ROS and apoptotic cell death induced by 6-OHDA. Gallic acid also lowered the ratio of the pro-apoptotic Bax protein and the anti-apoptotic Bcl-2 protein in SH-SY5Y cells. 6-OHDA exposure was up-regulated caspase-3 and Keap-1 and, down-regulated Nrf2, BDNF and p-CREB, which were sufficiently reverted by gallic acid pre-treatment. These findings indicate that gallic acid is able to protect the neuronal cells against 6-OHDA induced injury and proved that gallic acid might potentially serve as an agent for prevention of several human neurodegenerative diseases caused by oxidative stress and apoptosis.

IGF-1 protects SH-SY5Y cells against MPP+-induced apoptosis via PI3K/PDK-1/Akt pathway

Insulin-like growth factor (IGF)-1 is a well-known anti-apoptotic pro-survival factor and phosphatidylinositol-3-kinase (PI3K)/Akt pathway is linked to cell survival induced by IGF-1. It is also reported that Akt signaling is modulated by 3-phosphoinositide-dependent kinase-1 (PDK1). In the current study, we investigated whether the anti-apoptotic effect of IGF-1 in SH-SY5Y cells exposed to 1-methyl-4-phenylpyridinium (MPP⁺) is associated with the activity of PI3K/PDK1/Akt pathway. Treatment of cells with IGF-1 inhibited MPP⁺-induced apoptotic cell death. IGF-1-induced activation of Akt and the protective effect of IGF-1 on MPP⁺-induced apoptosis were abolished by chemical inhibition of PDK1 (GSK2334470) or PI3K (LY294002). The phosphorylated levels of Akt and PDK1 were significantly suppressed after MPP⁺ exposure, while IGF-1 treatment completely restored MPP+-induced reductions in phosphorylation. IGF-1 protected cells from MPP⁺ insult by suppressing intracellular reactive oxygen species (ROS) production and malondialdehyde levels and increasing superoxide dismutase activity. Mitochondrial ROS levels were also increased during MPP⁺ exposure, which were attenuated by IGF-1 treatment. In addition, IGF-1-treated cells showed increased activities of succinate dehydrogenase and citrate synthase, stabilization of mitochondrial transmembrane potential, increased ratio of Bcl-2 to Bax, prevention of cytochrome c release and inhibition of caspase-3 activation with PARP cleavage. Furthermore, the protective effects of IGF-1 on oxidative stress and mitochondrial dysfunction were attenuated when cells were preincubated with GSK2334470 or LY294002. Our data suggest that IGF-1 protects SH-SY5Y cells against MPP⁺-associated oxidative stress by preserving mitochondrial integrity and inhibiting mitochondrial apoptotic cascades via the activation of PI3K/PDK1/Akt pathway.

Evaluation of the Mitochondria-Related Redox and Bioenergetics Effects of Gastrodin in SH-SY5Y Cells Exposed to Hydrogen Peroxide

Mitochondrion is the main site of ATP production in animal cells and also orchestrates signaling pathways associated with cell survival and death. Mitochondrial dysfunction has been linked to bioenergetics and redox impairment in human diseases, such as neurodegeneration and cardiovascular disease. Protective agents able to attenuate mitochondrial impairment are of pharmacological interest. Gastrodin (GAS; 4-hydroxybenzyl alcohol 4-O-beta-D-glucoside) is a phenolic glucoside obtained from the Chinese herbal medicine Gastrodia elata Blume and exhibits antioxidant, anti-inflammatory, and antiapoptotic effects in several cell types. GAS is able to cross the blood-brain barrier, reducing the impact of different stressors on the cognition of experimental animals. In the present work, we investigated whether GAS would protect mitochondria of human SH-SY5Y neuroblastoma cells against an exposure to a pro-oxidant agent. The cells were treated with GAS at 25 μM for 30 min before the administration of hydrogen peroxide (H₂O₂) at 300 μM for an additional 3 or 24 h, depending on the assay. We evaluated both mitochondrial redox state and function parameters and analyzed the mechanism by which GAS protected mitochondria in this experimental model. Silencing of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor suppressed the GAS-induced mitochondrial protection seen here. Moreover, Nrf2 knockdown abrogated the effects of GAS on cell viability, indicating a potential role for Nrf2 in both mitochondrial and cellular protection promoted by GAS. Further research would be necessary to investigate whether GAS would be able to induce similar effects in in vivo experimental models.

Inhibition of Rac1 ameliorates neuronal oxidative stress damage via reducing Bcl-2/Rac1 complex formation in mitochondria through PI3K/Akt/mTOR pathway

Although the neuroprotective effects of Rac1 inhibition have been reported in various cerebral ischemic models, the molecular mechanisms of action have not yet been fully elucidated. In this study, we investigated whether the inhibition of Rac1 provided neuroprotection in a diabetic rat model of focal cerebral ischemia and hyperglycemia-exposed PC-12 cells. Intracerebroventricular administration of lentivirus expressing the Rac1 small hairpin RNA (shRNA) and specific Rac1 inhibitor NSC23766 not only decreased the infarct volumes and improved neurologic deficits with a correlated significant activation of mitochondrial DNA specific proteins, such as OGG1 and POLG, but also elevated Bcl-2 S70 phosphorylation in mitochondria. Furthermore, the levels of p-PI3K, p-Akt and p-mTOR increased, while 8-OHdG, ROS production and Bcl-2/Rac1 complex formation in mitochondria reduced in both Rac1-shRNA- and NSC23766-treated rats. Moreover, to confirm our in vivo observations, inhibition of Rac1 activity by NSC23766 suppressed the interactions between Bcl-2 and Rac1 in the mitochondria of PC-12 cells cultured in high glucose conditions and protected PC-12 cells from high glucose-induced neurotoxicity. More importantly, these beneficial effects of Rac1 inhibition were abolished by PI3K inhibitor LY294002. In contrast to NSC23766 treatment, LY294002 had little effect on the decrement of p-PTEN level. Taken together, these findings revealed novel neuroprotective roles of Rac1 inhibition against cerebral ischemic reperfusion injury in vivo and high glucose-induced neurotoxicity in PC-12 cells in vitro, by reducing Bcl-2/Rac1 complex formation in mitochondria through the activation of PI3K/Akt/mTOR survival pathway.

Beta-mangostin from Cratoxylum arborescens activates the intrinsic apoptosis pathway through reactive oxygen species with downregulation of the HSP70 gene in the HL60 cells associated with a G0/G1 cell-cycle arrest

Xanthones are phytochemical compounds found in a number of fruits and vegetables. Characteristically, they are noted to be made of diverse properties based on their biological, biochemical, and pharmacological actions. Accordingly, the apoptosis mechanisms induced by beta-mangostin, a xanthone compound isolated from Cratoxylum arborescens in the human promyelocytic leukemia cell line (HL60) in vitro, were examined in this study. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was done to estimate the cytotoxicity effect of β-mangostin on the HL60 cell line. Acridine orange/propidium iodide and Hoechst 33342 dyes and Annexin V tests were conducted to detect the apoptosis features. Caspase-3 and caspase-9 activities; reactive oxygen species; real-time polymerase chain reaction for Bcl-2, Bax, caspase-3, and caspase-9 Hsp70 genes; and western blot for p53, cytochrome c, and pro- and cleavage-caspase-3 and caspase-9 were assessed to examine the apoptosis mechanism. Cell-cycle analysis conducted revealed that β-mangostin inhibited the growth of HL60 at 58 µM in 24 h. The administration of β-mangostin with HL60 caused cell morphological changes related to apoptosis which increased the number of early and late apoptotic cells. The β-mangostin-catalyzed apoptosis action through caspase-3, caspase-7, and caspase-9 activation overproduced reactive oxygen species which downregulated the expression of antiapoptotic genes Bcl-2 and HSP70. Conversely, the expression of the apoptotic genes Bax, caspase-3, and caspase-9 were upregulated. Meanwhile, at the protein level, β-mangostin activated the formation of cleaved caspase-3 and caspase-9 and also upregulated the p53. β-mangostin arrested the cell cycle at the G0/G1 phase. Overall, the results for β-mangostin showed an antiproliferative effect in HL60 via stopping the cell cycle at the G0/G1 phase and prompted the intrinsic apoptosis pathway.

Hypercaloric Diet Establishes Erectile Dysfunction in Rat: Mechanisms Underlying the Endothelial Damage

Obesity is characterized by an excessive increase in body mass, leading to endothelial damage that may favor the development of erectile dysfunction (ED). ED is defined as the inability to achieve or maintain a penile erection long enough to have a sexual intercourse. In this context, different ED models were developed, however the high price of special animals or the long period to establish the disease has limited studies in this field. Therefore, this study proposed to establish and characterize a novel model of ED in rats associated to a hypercaloric diet consumption. Animals were randomly divided into control group (CG), which received a standard diet, and obese group (OG), fed with a hypercaloric diet during 8 weeks. Rat's erectile function was evaluated in vivo and in vitro. Food and caloric intake of OG were reduced compared to CG, due to an increased diet energy efficiency. However, OG presented an increased body mass, inguinal, retroperitoneal and epididymal adipose tissues, as well as body adiposity index at the end of experimental protocol. In erectile function analysis, there was a decrease in the number and the latency of penile erections in OG. Additionally, the contractile reactivity of corpus cavernosum was increased in OG, favoring penile detumescence and related to a reduced nitric oxide bioavailability and an increased in contractile prostaglandins levels as a consequence of endothelial damage. Moreover, the endothelium-relaxation reactivity of corpus cavernosum was attenuated in OG associated to the oxidative stress. Thus, it was provided a model for advances in sexual dysfunction field and drug discovery for ED treatment.

3'-hydroxy-4'-methoxy-β-methyl-β-nitrostyrene inhibits tumorigenesis in colorectal cancer cells through ROS-mediated DNA damage and mitochondrial dysfunction

The β-nitrostyrene family has been shown to suppress cell proliferation and induce apoptosis in types of various cancers. However, the mechanisms underlying the anticancer effects of β-nitrostyrenes in colorectal cancer remain poorly understood. In this study, we synthesized a β-nitrostyrene derivative, CYT-Rx20 (3'-hydroxy-4'-methoxy-β-methyl-β-nitrostyrene), and investigated its anticancer activities in human colorectal cancer cells both in vitro and in vivo. Our findings showed that treatment with CYT-Rx20 reduced cell viability and induced DNA damage in colorectal cancer cells. In addition, CYT-Rx20 induced cell cycle arrest of colorectal cancer cells at the G2/M phase and upregulated the protein expression of phospho-ERK, cyclin B1, phospho-cdc2 (Tyr15), aurora A, and aurora B, while it downregulated the expression of cdc25A and cdc25C. Furthermore, we found that CYT-Rx20 caused accumulation of intracellular reactive oxygen species (ROS) and reduction of mitochondrial membrane potential. The effects of CYT-Rx20 on cell viability, DNA damage, and mitochondrial membrane potential were reversed by pretreatment with the thiol antioxidant N-acetyl-L-cysteine (NAC), suggesting that ROS-mediated DNA damage and mitochondrial dysregulation play a critical role in these events. Finally, the nude mice xenograft study showed that CYT-Rx20 significantly reduced tumor growth of implanted colorectal cancer cells accompanied by elevated protein expression of aurora A, aurora B, γH2AX, phosphor-ERK, and MDA in the tumor tissues. Taken together, these results suggest that CYT-Rx20 may potentially be developed as a novel β-nitrostyrene-based anticancer agent for colorectal cancer.

Mdivi-1 Protects Adult Rat Hippocampal Neural Stem Cells against Palmitate-Induced Oxidative Stress and Apoptosis

Palmitate concentrations in type 2 diabetic patients are higher than in healthy subjects. The prolonged elevation of plasma palmitate levels induces oxidative stress and mitochondrial dysfunction in neuronal cells. In this study, we examined the role of mdivi-1, a selective inhibitor of mitochondrial fission protein dynamin-regulated protein 1 (Drp1), on the survival of cultured hippocampal neural stem cells (NSCs) exposed to high palmitate. Treatment of hippocampal NSCs with mdivi-1 attenuated palmitate-induced increase in cell death and apoptosis. Palmitate exposure significantly increased Drp1 protein levels, which were prevented by pretreatment of cells with mdivi-1. We found that cytosolic Drp1 was translocated to the mitochondria when cells were exposed to palmitate. In contrast, palmitate-induced translocation of Drp1 was inhibited by mdivi-1 treatment. We also investigated mdivi-1 regulation of apoptosis at the mitochondrial level. Mdivi-1 rescued cells from palmitate-induced lipotoxicity by suppressing intracellular and mitochondrial reactive oxygen species production and stabilizing mitochondrial transmembrane potential. Mdivi-1-treated cells showed an increased Bcl-2/Bax ratio, prevention of cytochrome c release, and inhibition of caspase-3 activation. Our data suggest that mdivi-1 protects hippocampal NSCs against lipotoxicity-associated oxidative stress by preserving mitochondrial integrity and inhibiting mitochondrial apoptotic cascades.

Sanggenon C induces apoptosis of colon cancer cells via inhibition of NO production, iNOS expression and ROS activation of the mitochondrial pathway

Sanggenon C is a well-known, major active agent of the flavonoid derivative of benzopyrone with valuable biological properties, including anticancer, anti-inflammatory, antimicrobial, antiviral, antithrombotic, and immune-modulatory activities. In this study, we investigated the molecular mechanisms by which sanggenon C mediated the induction of cell death in colorectal cancer cells (CRC). Treatment of colorectal cancer cells (LoVo, HT-29 and SW480) with sanggenon C (0, 5, 10, 20, 40 and 80 µM) resulted in inhibited proliferation of colon cancer cells. In addition, Sanggenon C (10, 20, 40 µM) induces apoptosis of HT-29 colon cancer cells as well as the increased ROS generation. Furthermore, treatment with sanggenon C increased the level of intracellular Ca²⁺ and ATP, while inhibited the nitric oxide production via inhibiting inducible nitric oxide synthase expression. This resulted in the activation of mitochondrial apoptosis pathway as evidenced by the decrease in Bcl-2 protein expression. Consistently, the anti-growth and pro-apoptosis effects of sanggenon C on xenograft colon tumor were further confirmed in vivo. Collectively, our results demonstrated sanggenon C induced apoptosis of colon cancer cells by increased reactive oxygen species generation and decreased nitric oxide production, which is associated with inhibition of inducible nitric oxide synthase expression and activation of mitochondrial apoptosis pathway.

Naringenin Attenuates H2O2-Induced Mitochondrial Dysfunction by an Nrf2-Dependent Mechanism in SH-SY5Y Cells

Mitochondria are the major site of ATP production in mammalian cells. Furthermore, these organelles are a source and a target of reactive oxygen species (ROS), such as radical anion superoxide (O₂^-·) and hydrogen peroxide (H₂O₂). The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is the master regulator of the mammalian redox biology and controls the expression of antioxidant and phase II detoxifying enzymes in several cell types. Naringenin (NGN, 5,7-dihydroxy-2-(4-hydroxyphenyl)-2,3-dihydrochromen-4-one), a flavanone, exhibits cytoprotective effects by acting as an antioxidant and anti-inflammatory agent. NGN is a potent activator of Nrf2. Nonetheless, it was not examine yet whether NGN would induce mitochondrial protection in cells under redox stress. Therefore, we investigate here whether Nrf2 would be involved in the mitochondrial protection elicited by NGN in SH-SY5Y cells exposed to H₂O₂. We observed that a pretreatment with NGN at 80 µM for 2 h reduced the levels of lipid peroxidation, protein carbonylation, and protein nitration in the membranes of mitochondria obtained from H₂O₂-treated SH-SY5Y cells. Additionally, NGN prevented the H₂O₂-induced impairment in the function of the enzymes aconitase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. The activites of the complexes I and V, as well as the production of ATP, were restored by NGN. NGN also suppressed the H₂O₂-induced mitochondria-related apoptosis. Interestingly, NGN promoted an increase in the levels of both total and mitochondrial glutathione (GSH). Silencing of Nrf2 abolished the protective effects induced by NGN. Overall, NGN induced mitochondrial protection by an Nrf2-dependent mechanism in H₂O₂-treated SH-SY5Y cells.

Novel roles of folic acid as redox regulator: Modulation of reactive oxygen species sinker protein expression and maintenance of mitochondrial redox homeostasis on hepatocellular carcinoma

We provide herein several lines of evidence to substantiate that folic acid (or folate) is a micronutrient capable of functioning as a novel redox regulator on hepatocellular carcinoma. First, we uncovered that folate deficiency could profoundly downregulate two prominent anti-apoptotic effectors including survivin and glucose-regulated protein-78. Silencing of either survivin or glucose-regulated protein-78 via small interfering RNA interfering technique established that both effectors could serve as reactive oxygen species sinker proteins. Second, folate deficiency-triggered oxidative-nitrosative stress could strongly induce endoplasmic reticulum stress that in turn could provoke cellular glutathione depletion through the modulation of the following two crucial events: (1) folate deficiency could strongly inhibit Bcl-2 expression leading to severe suppression of the mitochondrial glutathione pool and (2) folate deficiency could also profoundly inhibit two key enzymes that governing cellular glutathione redox regulation including γ-glutamylcysteinyl synthetase heavy chain, a catalytic enzyme for glutathione biosynthesis, and mitochondrial isocitrate dehydrogenase 2, an enzyme responsible for providing nicotinamide adenine dinucleotide phosphate necessary for regenerating oxidized glutathione disulfide back to glutathione via mitochondrial glutathione reductase. Collectively, we add to the literature new data to strengthen the notion that folate is an essential micronutrient that confers a novel role to combat reactive oxygen species insults and thus serves as a redox regulator via upregulating reactive oxygen species sinker proteins and averting mitochondrial glutathione depletion through proper maintenance of redox homeostasis via positively regulating glutathione biosynthesis, glutathione transporting system, and mitochondrial glutathione recycling process.

Transplantation and Damage-Associated Molecular Patterns (DAMPs)

Upon solid organ transplantation and during cancer immunotherapy, cellular stress responses result in the release of damage-associated molecular patterns (DAMPs). The various cellular stresses have been characterized in detail over the last decades, but a unifying classification based on clinically important aspects is lacking. Here, we provide an in-depth review of the most recent literature along with a unifying concept of the danger/injury model, suggest a classification of DAMPs, and review the recently elaborated mechanisms that result in the emission of such factors. We further point out the differences in DAMP responses including the release following a heat shock pattern, endoplasmic reticulum stress, DNA damage-mediated DAMP release, and discuss the diverse pathways of regulated necrosis in this respect. The understanding of various forms of DAMPs and the consequences of their different release patterns are prerequisite to associate serum markers of cellular stresses with clinical outcomes.

Hypericin in the Dark: Foe or Ally in Photodynamic Therapy?

Photosensitizers (PSs) in photodynamic therapy (PDT) are, in most cases, administered systemically with preferential accumulation in malignant tissues; however, exposure of non-malignant tissues to PS may also be clinically relevant, when PS molecules affect the pro-apoptotic cascade without illumination. Hypericin (Hyp) as PS and its derivatives have long been studied, regarding their photodynamic and photocytotoxic characteristics. Hyp and its derivatives have displayed light-activated antiproliferative and cytotoxic effects in many tumor cell lines without cytotoxicity in the dark. However, light-independent effects of Hyp have emerged. Contrary to the acclaimed Hyp minimal dark cytotoxicity and preferential accumulation in tumor cells, it was recently been shown that non-malignant and malignant cells uptake Hyp at a similar level. In addition, Hyp has displayed light-independent toxicity and anti-proliferative effects in a wide range of concentrations. There are multiple mechanisms underlying Hyp light-independent effects, and we are still missing many details about them. In this paper, we focus on Hyp light-independent effects at several sub-cellular levels—protein distribution and synthesis, organelle ultrastructure and function, and Hyp light-independent effects regarding reactive oxygen species (ROS). We summarize work from our laboratories and that of others to reveal an intricate network of the Hyp light-independent effects. We propose a schematic model of pro- and anti-apoptotic protein dynamics between cell organelles due to Hyp presence without illumination. Based on our model, Hyp can be explored as an adjuvant therapeutic drug in combination with chemo- or radiation cancer therapy.

Ghrelin gene products rescue cultured adult rat hippocampal neural stem cells from high glucose insult

Adult hippocampal neurogenesis is decreased in type 2 diabetes, and this impairment appears to be important in cognitive dysfunction. Previous studies suggest that ghrelin gene products (acylated ghrelin (AG), unacylated ghrelin (UAG) and obestatin (OB)) promote neurogenesis. Therefore, we hypothesize that ghrelin gene products may reduce the harmful effects of high glucose (HG) on hippocampal neural stem cells (NSCs). The aim of this study was to investigate the role of these peptides on the survival of cultured hippocampal NSCs exposed to HG insult. Treatment of hippocampal NSCs with AG, UAG or OB inhibited HG-induced cell death and apoptosis. Exposure of cells to the growth hormone secretagogue receptor 1a antagonist abolished the protective effects of AG against HG toxicity, whereas those of UAG or OB were preserved. All three peptides attenuated HG-induced decrease in BrdU-labeled and phosphohistone-H3-labeled cells. We also investigated the effects of ghrelin gene products on the regulation of apoptosis at the mitochondrial level. AG, UAG or OB rescued hippocampal NSCs from HG insult by inhibiting intracellular and mitochondrial reactive oxygen species generation and stabilizing mitochondrial transmembrane potential. In addition, cells treated with ghrelin gene products showed an increased Bcl-2 and decreased Bax levels, thereby increasing the Bcl-2/Bax ratio, inhibiting cytochrome c release and preventing caspase-3 activation. Finally, AG-, UAG- or OB-mediated protection was dependent on the activities of adenosine monophosphate-activated protein kinase/uncoupling protein 2 pathway. Our data indicate that ghrelin gene products may act as survival factors that preserve mitochondrial function and inhibit oxidative stress-induced apoptosis.

Normal Hematopoietic Progenitor Subsets Have Distinct Reactive Oxygen Species, BCL2 and Cell-Cycle Profiles That Are Decoupled from Maturation in Acute Myeloid Leukemia

In acute myeloid leukemia (AML) quiescence and low oxidative state, linked to BCL2 mitochondrial regulation, endow leukemic stem cells (LSC) with treatment-resistance. LSC in CD34+ and more mature CD34- AML have heterogeneous immunophenotypes overlapping with normal stem/progenitor cells (SPC) but may be differentiated by functional markers. We therefore investigated the oxidative/reactive oxygen species (ROS) profile, its relationship with cell-cycle/BCL2 for normal SPC, and whether altered in AML and myelodysplasia (MDS). In control BM (n = 24), ROS levels were highest in granulocyte-macrophage progenitors (GMP) and CD34- myeloid precursors but megakaryocyte-erythroid progenitors had equivalent levels to CD34+CD38low immature-SPC although they were ki67high. BCL2 upregulation was specific to GMPs. This profile was also observed for CD34+SPC in MDS-without-excess-blasts (MDS-noEB, n = 12). Erythroid CD34- precursors were, however, abnormally ROS-high in MDS-noEB, potentially linking oxidative stress to cell loss. In pre-treatment AML (n = 93) and MDS-with-excess-blasts (MDS-RAEB) (n = 14), immunophenotypic mature-SPC had similar ROS levels to co-existing immature-SPC. However ROS levels varied between AMLs; Flt3ITD+/NPM1wild-type CD34+SPC had higher ROS than NPM1mutated CD34+ or CD34- SPC. An aberrant ki67lowBCL2high immunophenotype was observed in CD34+AML (most prominent in Flt3ITD AMLs) but also in CD34- AMLs and MDS-RAEB, suggesting a shared redox/pro-survival adaptation. Some patients had BCL2 overexpression in CD34+ ROS-high as well as ROS-low fractions which may be indicative of poor early response to standard chemotherapy. Thus normal SPC subsets have distinct ROS, cell-cycle, BCL2 profiles that in AML /MDS-RAEB are decoupled from maturation. The combined profile of these functional properties in AML subpopulations may be relevant to differential treatment resistance.

Cell Death and Heart Failure in Obesity: Role of Uncoupling Proteins

Metabolic diseases such as obesity, metabolic syndrome, and type II diabetes are often characterized by increased reactive oxygen species (ROS) generation in mitochondrial respiratory complexes, associated with fat accumulation in cardiomyocytes, skeletal muscle, and hepatocytes. Several rodents studies showed that lipid accumulation in cardiac myocytes produces lipotoxicity that causes apoptosis and leads to heart failure, a dynamic pathological process. Meanwhile, several tissues including cardiac tissue develop an adaptive mechanism against oxidative stress and lipotoxicity by overexpressing uncoupling proteins (UCPs), specific mitochondrial membrane proteins. In heart from rodent and human with obesity, UCP2 and UCP3 may protect cardiomyocytes from death and from a state progressing to heart failure by downregulating programmed cell death. UCP activation may affect cytochrome c and proapoptotic protein release from mitochondria by reducing ROS generation and apoptotic cell death. Therefore the aim of this review is to discuss recent findings regarding the role that UCPs play in cardiomyocyte survival by protecting against ROS generation and maintaining bioenergetic metabolism homeostasis to promote heart protection.

Breast Cancer: A Molecular and Redox Snapshot

SIGNIFICANCE

Breast cancer is a unique disease characterized by heterogeneous cell populations causing roadblocks in therapeutic medicine, owing to its complex etiology and primeval understanding of the biology behind its genesis, progression, and sustenance. Globocan statistics indicate over 1.7 million new breast cancer diagnoses in 2012, accounting for 25% of all cancer morbidities.

RECENT ADVANCES

Despite these dismal statistics, the introduction of molecular gene signature platforms, progressive therapeutic approaches in diagnosis, and management of breast cancer has led to more effective treatment strategies and control measures concurrent with an equally reassuring decline in the mortality rate.

CRITICAL ISSUES

However, an enormous body of research in this area is requisite as high mortality associated with metastatic and/or drug refractory tumors continues to present a therapeutic challenge. Despite advances in systemic chemotherapy, the median survival of patients harboring metastatic breast cancers continues to be below 2 years.

FUTURE DIRECTIONS

Hence, a massive effort to scrutinize and evaluate chemotherapeutics on the basis of the molecular classification of these cancers is undertaken with the objective to devise more attractive and feasible approaches to treat breast cancers and improve patients' quality of life. This review aims to summarize the current understanding of the biology of breast cancer as well as challenges faced in combating breast cancer, with special emphasis on the current battery of treatment strategies. We will also try and gain perspective from recent encounters on novel findings responsible for the progression and metastatic transformation of breast cancer cells in an endeavor to develop more targeted treatment options. Antioxid. Redox Signal. 25, 337-370.

MUC1-C Stabilizes MCL-1 in the Oxidative Stress Response of Triple-Negative Breast Cancer Cells to BCL-2 Inhibitors

Aberrant expression of myeloid cell leukemia-1 (MCL-1) is a major cause of drug resistance in triple-negative breast cancer (TNBC) cells. Mucin 1 (MUC1) is a heterodimeric oncoprotein that is aberrantly overexpressed in most TNBC. The present studies show that targeting the oncogenic MUC1 C-terminal subunit (MUC1-C) in TNBC cells with silencing or pharmacologic inhibition with GO-203 is associated with downregulation of MCL-1 levels. Targeting MUC1-C suppresses the MEK → ERK and PI3K → AKT pathways, and in turn destabilizes MCL-1. The small molecules ABT-737 and ABT-263 target BCL-2, BCL-XL and BCL-w, but not MCL-1. We show that treatment with ABT-737 increases reactive oxygen species and thereby MUC1-C expression. In this way, MUC1-C is upregulated in TNBC cells resistant to ABT-737 or ABT-263. We also demonstrate that MUC1-C is necessary for the resistance-associated increases in MCL-1 levels. Significantly, combining GO-203 with ABT-737 is synergistic in inhibiting survival of parental and drug resistant TNBC cells. These findings indicate that targeting MUC1-C is a potential strategy for reversing MCL-1-mediated resistance in TNBC.

Oncostatic-Cytoprotective Effect of Melatonin and Other Bioactive Molecules: A Common Target in Mitochondrial Respiration

For several years, oncostatic and antiproliferative properties, as well as thoses of cell death induction through 5-methoxy-N-acetiltryptamine or melatonin treatment, have been known. Paradoxically, its remarkable scavenger, cytoprotective and anti-apoptotic characteristics in neurodegeneration models, such as Alzheimer’s disease and Parkinson’s disease are known too. Analogous results have been confirmed by a large literature to be associated to the use of many other bioactive molecules such as resveratrol, tocopherol derivatives or vitamin E and others. It is interesting to note that the two opposite situations, namely the neoplastic pathology and the neurodegeneration, are characterized by deep alterations of the metabolome, of mitochondrial function and of oxygen consumption, so that the oncostatic and cytoprotective action can find a potential rationalization because of the different metabolic and mitochondrial situations, and in the effect that these molecules exercise on the mitochondrial function. In this review we discuss historical and general aspects of melatonin, relations between cancers and the metabolome and between neurodegeneration and the metabolome, and the possible effects of melatonin and of other bioactive molecules on metabolic and mitochondrial dynamics. Finally, we suggest a common general mechanism as responsible for the oncostatic/cytoprotective effect of melatonin and of other molecules examined.

Relationship between Oxidative Stress, Circadian Rhythms, and AMD

This work reviews concepts regarding oxidative stress and the mechanisms by which endogenous and exogenous factors produce reactive oxygen species (ROS). It also surveys the relationships between oxidative stress, circadian rhythms, and retinal damage in humans, particularly those related to light and photodamage. In the first section, the production of ROS by different cell organelles and biomolecules and the antioxidant mechanisms that antagonize this damage are reviewed. The second section includes a brief review of circadian clocks and their relationship with the cellular redox state. In the third part of this work, the relationship between retinal damage and ROS is described. The last part of this work focuses on retinal degenerative pathology, age-related macular degeneration, and the relationships between this pathology, ROS, and light. Finally, the possible interactions between the retinal pigment epithelium (RPE), circadian rhythms, and this pathology are discussed.

Chronic aerobic swimming exercise promotes functional and morphological changes in rat ileum

In the present study, we evaluated the influence of chronic swimming aerobic exercise on the contractile reactivity, lipid peroxidation and tissue morphology of small intestine from rats. We showed that, accordingly to the time of exercise, the rat ileum has its contractile reactivity reduced, in addition to the increased lipid peroxidation followed by its reestablishment to basal levels, as well as the augmented longitudinal smooth muscle layer thickness together with the reduced circular thickness.

Several studies have reported the gastrointestinal (GI) effects promoted by the physical exercise. Thus, we aimed to evaluate the influence of swimming exercise on the contractile reactivity, lipid peroxidation and morphology of rat ileum. Wistar rats were divided into sedentary (SED) and groups exercised for two (EX2), four (EX4), six (EX6) or eight (EX8) weeks, 5 days/week. Animals were killed; the ileum was removed and suspended in organ baths where the isotonic contractions were recorded. Lipid peroxidation was evaluated by MDA (malondialdehyde) measurement with TBARS (thiobarbituric acid reactive substances) assay and morphology by histological staining. Cumulative concentration-response curves to KCl were attenuated, as the E_max values were changed from 100% (SED) to 63.1±3.9 (EX2), 48.8±3.8 (EX4), 19.4±1.8 (EX6) and 59.4±2.8% (EX8). Similarly, cumulative concentration-response curves to carbamylcholine hydrochloride (CCh) were attenuated, as the E_max values were changed from 100% (SED) to 74.1±5.4 (EX2), 75.9±5.2 (EX4) and 62.9±4.6 (EX6), but not in the EX8 (89.7±3.4%). However, CCh potency was increased in this latter, as the EC₅₀ was altered from 1.0±0.1×10⁻⁶ (SED) to 2.1±0.4×10⁻⁷ (EX8). MDA concentration was altered only in EX4 (44.3±4.4) compared with SED (20.6±3.6 μmol/l). Circular layer was reduced in SED when compared with the exercised groups. Conversely, longitudinal layer was increased. In conclusion, chronic swimming exercise reduces the ileum contraction, equilibrates the oxidative damage and promotes changes in tissue size to establish an adaptation to the exercise.

Sigma-1 receptor directly interacts with Rac1-GTPase in the brain mitochondria

BACKGROUND

Small Rho-GTPases are critical mediators of neuronal plasticity and are involved in the pathogenesis of several psychiatric and neurological disorders. Rac-GTPase forms a multiprotein complex with upstream and downstream regulators that are essential for the spatiotemporal transmission of Rac signaling. The sigma-1 receptor (Sig1R) is a ligand-regulated membrane protein chaperone, and multiprotein complex assembly is essential to sigma-receptor function.

RESULTS

Using immunoprecipitation techniques, we have shown that in mitochondrial membranes Sig1R could directly interact with Rac1. Besides Rac1, the Sig1R forms complexes with inositol 1,4,5-trisphosphate receptor and Bcl2, suggesting that mitochondrial associated membranes (MAM) are involved in this macromolecular complex formation. Assembly of this complex is ligand-specific and depends on the presence of sigma agonist/antagonist, as well as on the presence of GTP/GDP. Treatment of mitochondrial membranes with (+)-pentazocine leads to the (+)-pentazocine-sensitive phosphorylation of Bad and the pentazocine-sensitive NADPH-dependent production of ROS.

CONCLUSION

We suggest that Sig1R through Rac1 signaling induces mild oxidative stress that possibly is involved in the regulation of neuroplasticity, as well as in the prevention of apoptosis and autophagy.