Restoring the switch for cancer cell death: Targeting the apoptosis signaling pathway

Propyl gallate induces human pulmonary fibroblast cell death through the regulation of Bax and caspase-3

Propyl gallate (PG) has been found to exert an inhibitory effect on the growth of different cell types, including lung cancer cells. However, little is known about the cytotoxicological effects of PG specifically on normal primary lung cells. The current study examined the cellular effects and cell death resulting from PG treatment in human pulmonary fibroblast (HPF) cells. DNA flow cytometry results demonstrated that PG (100-1,600 μM) had a significant impact on the cell cycle, leading to G1 phase arrest. Notably, 1,600 μM PG slightly increased the number of sub-G1 cells. Additionally, PG (400-1,600 μM) resulted in the initiation of cell death, a process that coincided with a loss of mitochondrial membrane potential (MMP; ΔΨm). This loss of MMP (ΔΨm) was evaluated using a FACS cytometer. In PG-treated HPF cells, inhibitors targeting pan-caspase, caspase-3, caspase-8, and caspase-9 showed no significant impact on the quantity of annexin V-positive and MMP (ΔΨm) loss cells. The administration of siRNA targeting Bax or caspase-3 demonstrated a significant attenuation of PG-induced cell death in HPF cells. However, the use of siRNAs targeting p53, Bcl-2, or caspase-8 did not exhibit any notable effect on cell death. Furthermore, none of the tested MAPK inhibitors, including MEK, c-Jun N-terminal kinase (JNK), and p38, showed any impact on PG-induced cell death or the loss of MMP (ΔΨm) in HPF cells. In conclusion, PG induces G1 phase arrest of the cell cycle and cell death in HPF cells through apoptosis and/or necrosis. The observed HPF cell death is mediated by the modulation of Bax and caspase-3. These findings offer insights into the cytotoxic and molecular effects of PG on normal HPF cells.

Novel indole Schiff base β-diiminato compound as an anti-cancer agent against triple-negative breast cancer: In vitro anticancer activity evaluation and in vivo acute toxicity study

Breast cancer is the most prevalent cancer among women globally, with triple-negative breast cancer (TNBC) associated with poor prognosis and low five-year survival rates. Schiff base compounds, known for their extensive pharmacological activities, have garnered significant attention in cancer drug research. This study aimed to evaluate the anticancer potential of a novel β-diiminato compound and elucidate its mechanism of action. The compound's effect on cell viability was assessed using MTT assays in breast cancer cell lines including MCF-7 and MDA-MB-231. Cytotoxic effects were further analyzed using trypan blue exclusion and lactate dehydrogenase (LDH) release assays. In order to assess the mechanism of inhibitory activity and mode of cell death induced by this compound, flow cytometry of cell cycle distribution and apoptosis analysis were carried out. Apoptosis incidence was initially assessed through cell and nuclear morphological changes (Hoechst 33342/Propidium iodide (PI) staining) and further confirmed by Annexin V/PI staining and flow cytometry analysis. In addition, the effect of this compound on the disruption of mitochondrial membrane potential (MMP) and generation of the reactive oxygen species (ROS) was determined using the JC-1 indicator and DCFDA dye, respectively. The results demonstrated that the 24 h treatment with β-diiminato compound significantly suppressed the viability of MDA-MB-231 and MCF-7 cancer cells in a dose-dependent manner with the IC50 value of 2.41 ± 0.29 and 3.51 ± 0.14, respectively. The cytotoxic effect of the compound was further confirmed with a dose-dependent increase in the number of dead cells and enhanced LDH level in the culture medium. This compound exerted its anti-proliferative effect by G2/M phase cell growth arrest in MDA-MB-231 breast cancer cells and induced apoptosis-mediated cell death, which involved characteristic changes in cell and nuclear morphology, phosphatidylserine externalization, mitochondrial membrane depolarization, and increased ROS level. Neither hepatotoxicity nor nephrotoxicity was detected in the biochemical and histopathological analysis confirming the safety characterization of this compound usage. Therefore, the results significantly confirmed the potential anticancer activity of a novel β-diiminato compound, as evidenced by the induction of cell cycle arrest and apoptosis, which might be driven by the ROS‑mediated mitochondrial death pathway. This compound can be a promising candidate for future anticancer drug design and TNBC treatment, and further preclinical and clinical studies are warranted.

Propyl gallate induces cell death in human pulmonary fibroblast through increasing reactive oxygen species levels and depleting glutathione

Propyl gallate (PG) exhibits an anti-growth effect on various cell types. The present study investigated the impact of PG on the levels of reactive oxygen species (ROS) and glutathione (GSH) in primary human pulmonary fibroblast (HPF) cells. Moreover, the effects of N-acetyl cysteine (NAC, an antioxidant), L-buthionine sulfoximine (BSO, a GSH synthesis inhibitor), and small interfering RNA (siRNAs) against various antioxidant genes on ROS and GSH levels and cell death were examined in PG-treated HPF cells. PG (100-800 μM) increased the levels of total ROS and O2·- at early time points of 30-180 min and 24 h, whereas PG (800-1600 μM) increased GSH-depleted cell number at 24 h and reduced GSH levels at 30-180 min. PG downregulated the activity of superoxide dismutase (SOD) and upregulated the activity of catalase in HPF cells. Treatment with 800 μM PG increased the number of apoptotic cells and cells that lost mitochondrial membrane potential (MMP; ΔΨm). NAC treatment attenuated HPF cell death and MMP (ΔΨm) loss induced by PG, accompanied by a decrease in GSH depletion, whereas BSO exacerbated the cell death and MMP (ΔΨm) loss without altering ROS and GSH depletion levels. Furthermore, siRNA against SOD1, SOD2, or catalase attenuated cell death in PG-treated HPF cells, whereas siRNA against GSH peroxidase enhanced cell death. In conclusion, PG induced cell death in HPF cells by increasing ROS levels and depleting GSH. NAC was found to decrease HPF cell death induced by PG, while BSO enhanced cell death. The findings shed light on how manipulating the antioxidant system influence the cytotoxic effects of PG in HPF cells.

Ebselen Inhibits the Growth of Lung Cancer Cells via Cell Cycle Arrest and Cell Death Accompanied by Glutathione Depletion

Ebselen is a glutathione (GSH) peroxidase (GPx) mimic originally developed to reduce reactive oxygen species (ROS). However, little is known about its cytotoxicological effects on lung cells. Therefore, this study aimed to investigate the effects of Ebselen on the cell growth and cell death of A549 lung cancer cells, Calu-6 lung cancer cells, and primary normal human pulmonary fibroblast (HPF) cells in relation to redox status. The results showed that Ebselen inhibited the growth of A549, Calu-6, and HPF cells with IC50 values of approximately 12.5 μM, 10 μM, and 20 μM, respectively, at 24 h. After exposure to 15 μM Ebselen, the proportions of annexin V-positive cells were approximately 25%, 65%, and 10% in A549, Calu-6, and HPF cells, respectively. In addition, Ebselen induced arrest at the S phase of the cell cycle in A549 cells and induced G2/M phase arrest in Calu-6 cells. Treatment with Ebselen induced mitochondrial membrane potential (MMP; ΔΨm) loss in A549 and Calu-6 cells. Z-VAD, a pan-caspase inhibitor, did not decrease the number of annexin V-positive cells in Ebselen-treated A549 and Calu-6 cells. Intracellular ROS levels were not significantly changed in the Ebselen-treated cancer cells at 24 h, but GSH depletion was efficiently induced in these cells. Z-VAD did not affect ROS levels or GSH depletion in Ebselen-treated A549 or Ebselen-treated Calu-6 cells. In conclusion, Ebselen inhibited the growth of lung cancer and normal fibroblast cells and induced cell cycle arrest and cell death in lung cancer cells with GSH depletion.

Tempol Inhibits the Growth of Lung Cancer and Normal Cells through Apoptosis Accompanied by Increased O2•- Levels and Glutathione Depletion

Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) is a stable, cell-permeable redox-cycling nitroxide water-soluble superoxide dismutase (SOD) mimetic agent. However, little is known about its cytotoxic effects on lung-related cells. Thus, the present study investigated the effects of Tempol on cell growth and death as well as changes in reactive oxygen species (ROS) and glutathione (GSH) levels in Calu-6 and A549 lung cancer cells, normal lung WI-38 VA-13 cells, and primary pulmonary fibroblast cells. Results showed that Tempol (0.5~4 mM) dose-dependently inhibited the growth of lung cancer and normal cells with an IC50 of approximately 1~2 mM at 48 h. Tempol induced apoptosis in lung cells with loss of mitochondrial membrane potential (MMP; ∆Ψm) and activation of caspase-3. There was no significant difference in susceptibility to Tempol between lung cancer and normal cells. Z-VAD, a pan-caspase inhibitor, significantly decreased the number of annexin V-positive cells in Tempol-treated Calu-6, A549, and WI-38 VA-13 cells. A 2 mM concentration of Tempol increased ROS levels, including O2•- in A549 and WI-38 VA-13 cells after 48 h, and specifically increased O2•- levels in Calu-6 cells. In addition, Tempol increased the number of GSH-depleted cells in Calu-6, A549, and WI-38 VA-13 cells at 48 h. Z-VAD partially downregulated O2•- levels and GSH depletion in Tempol-treated these cells. In conclusion, treatment with Tempol inhibited the growth of both lung cancer and normal cells via apoptosis and/or necrosis, which was correlated with increased O2•- levels and GSH depletion.

Isobavachalcone Induces Multiple Cell Death in Human Triple-Negative Breast Cancer MDA-MB-231 Cells

Standardized treatment guidelines and effective drugs are not available for human triple-negative breast cancer (TNBC). Many efforts have recently been exerted to investigate the efficacy of natural compounds as anticancer agents owing to their low toxicity. However, no study has examined the effects of isobavachalcone (IBC) on the programmed cell death (PCD) of human triple-negative breast MDA-MB-231 cancer cells. In this study, IBC substantially inhibited the proliferation of MDA-MB-231 cells in concentration- and time-dependent manners. In addition, we found that IBC induced multiple cell death processes, such as apoptosis, necroptosis, and autophagy in MDA-MB-231 cells. The initial mechanism of IBC-mediated cell death in MDA-MB-231 cells involves the downregulation of Akt and p-Akt-473, an increase in the Bax/Bcl-2 ratio, and cleaved caspases-3 induced apoptosis; the upregulation of RIP3, p-RIP3 and MLKL induced necroptosis; as well as a simultaneous increase in LC3-II/I ratio induced autophagy. In addition, we observed that IBC induced mitochondrial dysfunction, thereby decreasing cellular ATP levels and increasing reactive oxygen species accumulation to induce PCD. These results suggest that IBC is a promising lead compound with anti-TNBC activity.

The Anti-Apoptotic Effects of Caspase Inhibitors in Propyl Gallate-Treated Lung Cancer Cells Are Related to Changes in Reactive Oxygen Species and Glutathione Levels

Propyl gallate [3,4,5-trihydroxybenzoic acid propyl ester; PG] exhibits an anti-growth effect in various cells. In this study, the anti-apoptotic effects of various caspase inhibitors were evaluated in PG-treated Calu-6 and A549 lung cancer cells in relation to reactive oxygen species (ROS) and glutathione (GSH) levels. Treatment with 800 μM PG inhibited the proliferation and induced the cell death of both Calu-6 and A549 cells at 24 h. Each inhibitor of pan-caspase, caspase-3, caspase-8, and caspase-9 reduced the number of dead and sub-G1 cells in both PG-treated cells at 24 h. PG increased ROS levels, including O₂^∙−, in both lung cancer cell lines at 24 h. Generally, caspase inhibitors appeared to decrease ROS levels in PG-treated lung cancer cells at 24 h and somewhat reduced O₂^∙− levels. PG augmented the number of GSH-depleted Calu-6 and A549 cells at 24 h. Caspase inhibitors did not affect the level of GSH depletion in PG-treated A549 cells but differently and partially altered the depletion level in PG-treated Calu-6 cells. In conclusion, PG exhibits an anti-proliferative effect in Calu-6 and A549 lung cancer cells and induced their cell death. PG-induced lung cancer death was accompanied by increases in ROS levels and GSH depletion. Therefore, the anti-apoptotic effects of caspase inhibitors were, at least in part, related to changes in ROS and GSH levels.

Anticancer activities of Brachydin C in human prostate tumor cells (DU145) grown in 2D and 3D models: stimulation of cell death and downregulation of metalloproteinases in spheroids

Brachydin C (BrC) has demonstrated in vitro cytotoxic and antiproliferative effects in prostate cancer cells. In the present study, we compare the anticancer effects of BrC in DU145 cells grown in common bidimensional cultures (2D) and multicellular tumor spheroids (MCTS), often denominated 3D in vitro models, that can better mimic the microenvironment of tissues. BrC IC₅₀ values obtained in the resazurin assay after 24 h of treatment were 47.31 μM (2D) and 229.8 μM (3D) and these cytotoxic effects were time dependent only in 3D. BrC (5 to 60 μM) interfered with the growth of MCTS and reduced cell viability after 11 days of treatment, a result that is not attributable to oxidative stress evaluated using the CM-H₂ DCFDA probe. BrC (6.0 μM) impaired horizontal (wound healing) and vertical cell migration and invasion (transwell assay) in 2D and BrC (5.0 to 60 μM) in 3D (ECM Gel®). BrC modulated the expression of genes BIRC5, TNF-α, CASP3, NKX3.1, MMP9, MMP11, CDH1, and ITGAM and downregulated proteins CASP7, BAX, and TNF-α in western blotting analysis. In conclusion, BrC stimulated cell death and decreased epithelial-mesenchymal transition. Furthermore, DU145 MCTS displayed higher resistance to BrC- induced cell death than 2D cultures, a difference that should be considered in future approaches in prostatic cancer studies.

Caspase 8 Expression Patterns in Meningiomas: A Tissue Microarray Digital Image Analysis

Background: Caspases (cysteine-aspartic proteases) represent a family of enzymes that critically influence cell homeostasis by being involved in inflammation and apoptosis mechanisms. Meningiomas demonstrate the most common intracranial primary central nervous system tumors in adults worldwide.

Aim: Our purpose was to explore the role of caspase 8 expression in meningiomas’ pathological features.

Materials and methods: A total of 50 meningioma cases were included in the study, comprising a broad spectrum of histopathological sub-types. An immunohistochemistry assay was applied on tissue microarray cores followed by digital image analysis.

Results: Overexpression of caspase 8 protein was observed in 21/50 (42%) cases, whereas the rest of them (29/50, 58%) demonstrated moderate to low levels of the molecule. Caspase 8 overall expression was statistically significantly correlated to grade of the examined tumors and to mitotic index (p=0.001,p=0.002, respectively).

Conclusions: Caspase 8 aberrant expression is observed in meningiomas associated with their differentiation grade and mitotic activity. Targeted therapeutic strategies focused on enhancing caspase 8 expression and also inducing the overall apoptotic activity should be a very promising approach in rationally handling sub-groups of meningioma patients.

Evaluation of the expression of necroptosis pathway mediators and its association with tumor characteristics in functional and non-functional pituitary adenomas

BACKGROUND

Pituitary adenomas impose a burden of morbidity on patients and characterizing the molecular mechanisms underlying its pathogenesis received remarkable attention. Despite the appealing role of necroptosis as an alternative cell death pathway in cancer pathogenesis, its relevance to pituitary adenoma pathogenesis has yet to be determined that is perused in the current study.

METHODS

The total number of 109 specimens including pituitary adenomas and cadaveric healthy pituitary tissues were enrolled in the current study. Tumor and healthy pituitary tissues were subjected to RNA extraction and gene analysis using Real-Time PCR. The expression levels of necroptosis markers (RIP1K, RIP3K and, MLKL) and their association with the patient's demographic features were evaluated, also the protein level of MLKL was assessed using immunohistochemistry in tissues.

RESULTS

Based on our data, the remarkable reduction in RIP3K and MLKL expression were detected in nonfunctional and GH-secreting pituitary tumors compared to pituitary normal tissues. Invasive tumors revealed lower expression of RIP3K and MLKL compared to non-invasive tumors, also the attenuated level of MLKL was associated with the tumor size in invasive NFPA. The simultaneous down-regulation of MLKL protein in pituitary adenoma tissues was observed which was in line with its gene expression. While, RIP1K over-expressed significantly in both types of pituitary tumors which showed no significant correlation with patient's age, gender and tumor size in GHPPA and NFPA group. Notably, MLKL and RIP3K gene expression was significantly correlated in the GHPPA group.

CONCLUSIONS

According to our data, the reduced expression of necroptosis mediators (RIP3K, MLKL) in pituitary adenoma reinforces the hypothesis that the necroptosis pathway can be effective in regulating the proliferation and growth of pituitary tumor cells and tumor recurrence.

Mechanism of interaction between autophagy and apoptosis in cancer

The mechanisms of two programmed cell death pathways, autophagy, and apoptosis, are extensively focused areas of research in the context of cancer. Both the catabolic pathways play a significant role in maintaining cellular as well as organismal homeostasis. Autophagy facilitates this by degradation and elimination of misfolded proteins and damaged organelles, while apoptosis induces canonical cell death in response to various stimuli. Ideally, both autophagy and apoptosis have a role in tumor suppression, as autophagy helps in eliminating the tumor cells, and apoptosis prevents their survival. However, as cancer proceeds, autophagy exhibits a dual role by enhancing cancer cell survival in response to stress conditions like hypoxia, thereby promoting chemoresistance to the tumor cells. Thus, any inadequacy in either of their levels can lead to tumor progression. A complex array of biomarkers is involved in maintaining coordination between the two by acting as either positive or negative regulators of one or both of these pathways of cell death. The resulting crosstalk between the two and its role in influencing the survival or death of malignant cells makes it quintessential, among other challenges facing chemotherapeutic treatment of cancer. In view of this, the present review aims to highlight some of the factors involved in maintaining their diaphony and stresses the importance of inhibition of cytoprotective autophagy and deletion of the intermediate pathways involved to facilitate tumor cell death. This will pave the way for future prospects in designing drug combinations facilitating the synergistic effect of autophagy and apoptosis in achieving cancer cell death.

Targeting the Myeloid Lineages and the Immune Microenvironment in Myelodysplastic Syndromes: Novel and Evolving Therapeutic Strategies

OBJECTIVE

To discuss the recent and emerging data for novel targeted therapies in myelodysplastic syndromes (MDS).

DATA SOURCES

A literature search from January 2015 to June 2021 was performed using the key terms targeted therapies, myelodysplastic syndromes, DNA repair, erythroid differentiation therapy, epigenetic inhibitors, signal transduction inhibitors, and apoptosis-inducing agents.

STUDY SELECTION AND DATA EXTRACTION

Relevant clinical trials and articles in the English language were identified and reviewed.

DATA SYNTHESIS

MDS are a heterogeneous group of malignant blood disorders affecting the bone marrow (BM), ultimately leading to BM failure, acute leukemia, and death. Selection of treatment is influenced by the severity of symptoms, cytopenia, cytogenetics, prognostic category, medical fitness, and patient preferences. Although current therapies such as erythropoiesis stimulating agents (ESAs) and hypomethylating agents (HMAs) help improve anemia and reduce transfusion burden, limited treatment options exist when patients experience treatment failure to ESAs or HMA. Recent regulatory approval of luspatercept, which targets the erythroid differentiation pathway, represents a major therapeutic advance in the management of anemia in MDS patients who are refractory to ESAs. Many investigational targeted therapies that aim at the myeloid lineage signaling pathway and the immune microenvironment are in active development.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This nonexhaustive review summarizes and describes the recent data for targeted therapies for MDS.

CONCLUSION

The development of novel and investigational therapeutic agents continues to contribute to an improved understanding of tumor biology. The precise therapeutic role and timing of these agents remain to be elucidated.

Tempol differently affects cellular redox changes and antioxidant enzymes in various lung-related cells

Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) is a potential redox agent in cells. The present study investigated changes in cellular reactive oxygen species (ROS) and glutathione (GSH) levels and in antioxidant enzymes, in Tempol-treated Calu-6 and A549 lung cancer cells, normal lung WI-38 VA-13 cells, and primary pulmonary fibroblasts. Results demonstrated that Tempol (0.5–4 mM) either increased or decreased general ROS levels in lung cancer and normal cells at 48 h and specifically increased O₂^•− levels in these cells. In addition, Tempol differentially altered the expression and activity of antioxidant enzymes such as superoxide dismutase, catalase, and thioredoxin reductase1 (TrxR1) in A549, Calu-6, and WI-38 VA-13 cells. In particular, Tempol treatment increased TrxR1 protein levels in these cells. Tempol at 1 mM inhibited the growth of lung cancer and normal cells by about 50% at 48 h but also significantly induced cell death, as evidenced by annexin V-positive cells. Furthermore, down-regulation of TrxR1 by siRNA had some effect on ROS levels as well as cell growth inhibition and death in Tempol-treated or -untreated lung cells. In addition, some doses of Tempol significantly increased the numbers of GSH-depleted cells in both cancer cells and normal cells at 48 h. In conclusion, Tempol differentially increased or decreased levels of ROS and various antioxidant enzymes in lung cancer and normal cells, and induced growth inhibition and death in all lung cells along with an increase in O₂^•− levels and GSH depletion.

BAX and SMAC regulate bistable properties of the apoptotic caspase system

The initiation of apoptosis is a core mechanism in cellular biology by which organisms control the removal of damaged or unnecessary cells. The irreversible activation of caspases is essential for apoptosis, and mathematical models have demonstrated that the process is tightly regulated by positive feedback and a bistable switch. BAX and SMAC are often dysregulated in diseases such as cancer or neurodegeneration and are two key regulators that interact with the caspase system generating the apoptotic switch. Here we present a mathematical model of how BAX and SMAC control the apoptotic switch. Formulated as a system of ordinary differential equations, the model summarises experimental and computational evidence from the literature and incorporates the biochemical mechanisms of how BAX and SMAC interact with the components of the caspase system. Using simulations and bifurcation analysis, we find that both BAX and SMAC regulate the time-delay and activation threshold of the apoptotic switch. Interestingly, the model predicted that BAX (not SMAC) controls the amplitude of the apoptotic switch. Cell culture experiments using siRNA mediated BAX and SMAC knockdowns validated this model prediction. We further validated the model using data of the NCI-60 cell line panel using BAX protein expression as a cell-line specific parameter and show that model simulations correlated with the cellular response to DNA damaging drugs and established a defined threshold for caspase activation that could distinguish between sensitive and resistant melanoma cells. In summary, we present an experimentally validated dynamic model that summarises our current knowledge of how BAX and SMAC regulate the bistable properties of irreversible caspase activation during apoptosis.

Molecular Mechanisms of the Action of Myricetin in Cancer

Natural compounds, such as paclitaxel and camptothecin, have great effects on the treatment of tumors. Such natural chemicals often achieve anti-tumor effects through a variety of mechanisms. Therefore, it is of great significance to conduct further studies on the anticancer mechanism of natural anticancer agents to lay a solid foundation for the development of new drugs. Myricetin, originally isolated from Myrica nagi, is a natural pigment of flavonoids that can inhibit the growth of cancer cells (such as liver cancer, rectal cancer, skin cancer and lung cancer, etc.). It can regulate many intracellular activities (such as anti-inflammatory and blood lipids regulation) and can even be bacteriostatic. The purpose of this paper is to outline the molecular pathways of the anticancer effects of myricetin, including the effect on cancer cell death, proliferation, angiogenesis, metastasis and cell signaling pathway.

Bcl‑2 family: Novel insight into individualized therapy for ovarian cancer (Review)

Chemoresistance to platinum‑based chemotherapy for ovarian cancer in the advanced stage remains a formidable concern clinically. Increasing evidence has revealed that apoptosis represents the terminal events of the anti‑tumor mechanisms of a number of chemical drugs and has a close association with chemoresistance in ovarian cancer. The B‑cell lymphoma‑2 (Bcl‑2) family plays a crucial role in apoptosis and has a close association with chemoresistance in ovarian cancer. Some drugs that target Bcl‑2 family members have shown efficacy in overcoming the chemoresistance of ovarian cancer. A BH3 profiling assay was found to be able to predict how primed a cell is when treated with antitumor drugs. The present review summarizes the role of the Bcl‑2 family in mediating cell death in response to antitumor drugs and novel drugs that target Bcl‑2 family members. The application of the new functional assay, BH3 profiling, is also discussed herein. Furthermore, the present review presents the hypothesis that targeting Bcl‑2 family members may prove to be helpful for the individualized therapy of ovarian cancer in clinical practice and in laboratory research.

Striatin translocates to the cytosol of apoptotic cells and is proteolytically cleaved in a caspase 3-dependent manner

Striatin (STRN) is a multivalent protein holding great therapeutic potentials in view of its interaction with dynamic partners implicated in apoptosis. Although striatin-3 and striatin-4, that share high structural similarities with STRN, have been linked to apoptosis, the dynamics of STRN in apoptotic cells remain unclear. Herein, we report that the amount of STRN (110 kDa) is reduced in apoptotic cells, in response to various chemotherapeutic agents, thereby yielding a major polypeptide fragment at ~65 kDa, and three minor products at lower molecular weights. While STRN siRNA reduced the 65 kDa derivative fragment, the overexpression of a Myc-tagged STRN precipitated a novel fragment that was detected slightly higher than 65 kDa (due to the Myc-DDK tag on the cleaved fragment), confirming the cleavage of STRN during apoptosis. Interestingly, STRN cleavage was abrogated by the general caspase inhibitor Z-VAD.fmk. Cell fractionation revealed that the STRN pool, mainly distributed in the non-cytosolic fragment of naïve cells, translocates to the cytosol where it is proteolytically cleaved during apoptosis. Interestingly, the ectopic expression of caspase 3 in MCF-7 cells (deprived of caspase 3) induced STRN cleavage under apoptotic conditions. Inhibition of caspase 3 (Ac-DEVD-CHO) conferred a dose-dependent protection against the proteolytic cleavage of STRN. Collectively, our data provide cogent proofs that STRN translocates to the cytosol where it undergoes proteolytic cleavage in a caspase 3-dependent manner during apoptosis. Thus, this study projects the cleavage of STRN as a novel marker for apoptosis to serve pharmacological strategies targeting this particular form of cell death.

Breast Cancer Chemotherapeutic Options: A General Overview on the Preclinical Validation of a Multi-Target Ruthenium(III) Complex Lodged in Nucleolipid Nanosystems

In this review we have showcased the preclinical development of original amphiphilic nanomaterials designed for ruthenium-based anticancer treatments, to be placed within the current metallodrugs approach leading over the past decade to advanced multitarget agents endowed with limited toxicity and resistance. This strategy could allow for new options for breast cancer (BC) interventions, including the triple-negative subtype (TNBC) with poor therapeutic alternatives. BC is currently the second most widespread cancer and the primary cause of cancer death in women. Hence, the availability of novel chemotherapeutic weapons is a basic requirement to fight BC subtypes. Anticancer drugs based on ruthenium are among the most explored and advanced next-generation metallotherapeutics, with NAMI-A and KP1019 as two iconic ruthenium complexes having undergone clinical trials. In addition, many nanomaterial Ru complexes have been recently conceived and developed into anticancer drugs demonstrating attractive properties. In this field, we focused on the evaluation of a Ru(III) complex-named AziRu-incorporated into a suite of both zwitterionic and cationic nucleolipid nanosystems, which proved to be very effective for the in vivo targeting of breast cancer cells (BBC). Mechanisms of action have been widely explored in the context of preclinical evaluations in vitro, highlighting a multitarget action on cell death pathways which are typically deregulated in neoplasms onset and progression. Moreover, being AziRu inspired by the well-known NAMI-A complex, information on non-nanostructured Ru-based anticancer agents have been included in a precise manner.

Integrating Ligand and Target-Driven Based Virtual Screening Approaches With in vitro Human Cell Line Models and Time-Resolved Fluorescence Resonance Energy Transfer Assay to Identify Novel Hit Compounds Against BCL-2

Antiapoptotic members of B-cell leukemia/lymphoma-2 (BCL-2) family proteins are one of the overexpressed proteins in cancer cells that are oncogenic targets. As such, targeting of BCL-2 family proteins raises hopes for new therapeutic discoveries. Thus, we used multistep screening and filtering approaches that combine structure and ligand-based drug design to identify new, effective BCL-2 inhibitors from a small molecule database (Specs SC), which includes more than 210,000 compounds. This database is first filtered based on binary “cancer-QSAR” model constructed with 886 training and 167 test set compounds and common 26 toxicity quantitative structure-activity relationships (QSAR) models. Predicted non-toxic compounds are considered for target-driven studies. Here, we applied two different approaches to filter and select hit compounds for further in vitro biological assays and human cell line experiments. In the first approach, a molecular docking and filtering approach is used to rank compounds based on their docking scores and only a few top-ranked molecules are selected for further long (100-ns) molecular dynamics (MD) simulations and in vitro tests. While docking algorithms are promising in predicting binding poses, they can be less prone to precisely predict ranking of compounds leading to decrease in the success rate of in silico studies. Hence, in the second approach, top-docking poses of each compound filtered through QSAR studies are subjected to initially short (1 ns) MD simulations and their binding energies are calculated via molecular mechanics generalized Born surface area (MM/GBSA) method. Then, the compounds are ranked based on their average MM/GBSA energy values to select hit molecules for further long MD simulations and in vitro studies. Additionally, we have applied text-mining approaches to identify molecules that contain “indol” phrase as many of the approved drugs contain indole and indol derivatives. Around 2700 compounds are filtered based on “cancer-QSAR” model and are then docked into BCL-2. Short MD simulations are performed for the top-docking poses for each compound in complex with BCL-2. The complexes are again ranked based on their MM/GBSA values to select hit molecules for further long MD simulations and in vitro studies. In total, seven molecules are subjected to biological activity tests in various human cancer cell lines as well as Time-Resolved Fluorescence Resonance Energy Transfer (TR-FRET) assay. Inhibitory concentrations are evaluated, and biological activities and apoptotic potentials are assessed by cell culture studies. Four molecules are found to be limiting the proliferation capacity of cancer cells while increasing the apoptotic cell fractions.

Comprehensive gene expression analysis after ERH gene knockdown in human bladder cancer T24 cell lines

INTRODUCTION

In this article, we utilized Ingenuity® Pathway Analysis (IPA®) bioinformatics analysis software and Metascape® bioinformatics analysis website tools to analyse the possible mechanism of ERH affecting tumourigenesis (proliferation and apoptosis) in bladder cancer (BC) T24 cells.

METHODS

The ERH gene was knocked down, and BC T24 cells were divided into ERH normal and knockdown groups. Affymetrix® gene expression microarrays were performed to obtain a differentially expressed gene list (DEGL) between the 2 groups. IPA® data analyses contain five modules: disease and function analysis, upstream analysis, regulator effects analysis, canonical pathway analysis and molecular network analysis. The results of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were analysed by Metascape®.

RESULTS

The results of the gene expression profiling chip and the DEGL showed that 344 genes were upregulated and 254 genes were downregulated. The IPA® and Metascape® pathway analyses showed that the ERH gene may affect proliferation and apoptosis by affecting the apoptosis, cell cycle, Toll-like receptor (TLR), NF-κB or TGF-beta signalling pathways. Upstream analysis determined that the ERH gene may regulate TNF and NK-κB in the BC T24 cell lines. The ERH gene may be involved in the "cell death and survival" molecular network in BC T24 cells. ERH may be a regulator of KITLG through TNF.

CONCLUSIONS

The ERH gene may affect apoptosis through the TLR, NF-κB, TNF or TGF-beta signalling pathways in BC T24 cells, and may be a regulator of KITLG to ultimately activate the growth of malignant tumours.

Apoptosis Induction by Pseudorabies Virus via Oxidative Stress and Subsequent DNA Damage Signaling

BACKGROUND

Pseudorabies virus (PRV) infection induces apoptosis in swine cells both in vitro and in vivo; however, the mechanism associated with host-cell signaling has not been studied. This study investigated the role of free radicals caused by cellular oxidative stress after viral infection and examined whether the DNA damage response plays an important role in PRV-induced apoptosis.

METHODS

Several apoptosis assays and western blotting confirmed PRV-induced apoptosis. PRV-mediated oxidative stress was evaluated by reactive oxygen species (ROS) assay.

RESULTS

Our results showed that PRV caused apoptosis in a porcine kidney cell line, PK15, and induced expressions of proapoptotic Bcl family proteins in a dose- and time-dependent manner. Expressions of specific DNA damage sensors and phosphorylation of histone H2AX were also significantly increased, which subsequently activated the expressions of checkpoint kinase 1/2 and proapoptotic p53. Caffeine, a known DNA damage inhibitor, was found to inhibit caspase-3 activation and protect cells from PRV-induced apoptosis. Additionally, the antioxidant N-acetyl-L-cysteine was shown to prevent the production of cellular ROS, protecting DNA from cleavage.

CONCLUSIONS

Our results confirmed that oxidative stress and free radicals arising from PRV infection cause DNA damage, which consequently triggers apoptosis.

Association of autoimmunity and cancer: An emphasis on proteolytic enzymes

Cancer and autoimmune diseases are the two devastating conditions that together constitute a leading health problem worldwide. The rising burden of these disorders in the developing world demands a multifaceted approach to address the challenges it poses. Understanding the root causes and specific molecular mechanisms by which the progression of the diseases takes place is need of the hour. A strong inflammatory background and common developmental pathways, such as activation of immune cells, proliferation, increased cell survival and migration which are controlled by growth factors and inflammatory cytokines have been considered as the critical culprits in the progression and complications of these disorders. Enzymes are the potential immune modulators which regulate various inflammatory events and can break the circulating immune complexes via macrophages production. In the current manuscript, we have uncovered the possible role of proteolytic enzymes in the pathogenesis and progression of cancer and autoimmune diseases. In the light of the available scientific literature, we advocate in-depth comprehensive studies which will shed light towards the role of proteolytic enzymes in the modulation of inflammatory responses in cancer and autoimmune diseases together.

Concomitance of downregulated active caspase-3 and upregulated X-chromosome linked inhibitor of apoptosis protein as a sensitive diagnostic approach for breast cancer

We aimed to explore the efficacy of active caspase-3 and X-chromosome linked inhibitor of apoptosis protein (XIAP) as diagnostic markers for breast cancer. Furthermore, we examined the relationship between the examined parameters and clinicopathological factors. The current study involved 96 patients diagnosed with breast cancer and 40 patients had benign breast diseases. The expression of active caspase-3 was analyzed by both ELISA and Western blot, whereas the expression of XIAP was determined by ELISA in cell lysates. Active caspase-3 was significantly downregulated, while XIAP was markedly upregulated in patients with breast cancer in comparison to benign group. A significant negative correlation was observed between active caspase-3 and XIAP in breast cancer patients. Low active caspase-3 expression was associated with high grade, whereas, the high XIAP level was correlated with poorly differentiated tumors and late tumor stages. The sensitivity and specificity were 73.96% and 80.0% for active caspase-3, and, 70.83% and 82.5% for XIAP. A combination of active caspase-3 and XIAP provided a promising sensitivity of 88.54% and specificity of 90.0%. Our data indicate that active caspase-3 and XIAP could be substantial diagnostic markers for breast cancer patients.