Pyridoxine Preferentially Induces Auditory Neuropathy Through Mitochondrial Dysfunction and Endoplasmic Reticulum Stress-Mediated Apoptosis

2019 ◽  
Vol 128 (6_suppl) ◽  
pp. 117S-124S ◽  
Author(s):  
Channy Park ◽  
Hyewon Lim ◽  
Sung K. Moon ◽  
Raekil Park

Objectives: Auditory neuropathy due to toxicity mechanism of pyridoxine has not yet been fully documented. Therefore, the present study explored a direct mechanism underlying the effects of pyridoxine on auditory neuropathy in organ of Corti (OC) explants ex vivo and cochlear neuroblast cell line, VOT-33 in vitro. Methods: Primary OC explants containing spiral ganglion neurons and cultured VOT-33 cells were treated with pyridoxine. Results: In nerve fiber of primary OC explants, pyridoxine decreased staining for NF200, a neuro-cytoskeletal protein. We also found that pyridoxine-induced VOT-33 apoptosis, as indicated by accumulation of the sub-G0/G1 fraction, caspase-3 activation, and PARP cleavage. In addition, pyridoxine induced reactive oxygen species (ROS) generation and alteration of mitochondrial membrane potential transition (MPT), including Bcl-2 family protein expression and consequently Ca2+ accumulation and changes of endoplasmic reticulum (ER) stress-related protein expression such as phospho-PERK, caspase-12, Grp78, and CHOP. Conclusion: Pyridoxine preferentially induced severe cell death on nerve fiber in primary OC explants and markedly increased apoptotic cell death via mitochondria-mediated ER stress in VOT-33 cells.

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Leonid Minasyan ◽  
Parameswaran G. Sreekumar ◽  
David R. Hinton ◽  
Ram Kannan

Age-related macular degeneration (AMD) is the leading cause of severe and irreversible vision loss and is characterized by progressive degeneration of the retina resulting in loss of central vision. The retinal pigment epithelium (RPE) is a critical site of pathology of AMD. Mitochondria and the endoplasmic reticulum which lie in close anatomic proximity to each other are targets of oxidative stress and endoplasmic reticulum (ER) stress, respectively, and contribute to the progression of AMD. The two organelles exhibit close interactive function via various signaling mechanisms. Evidence for ER-mitochondrial crosstalk in RPE under ER stress and signaling pathways of apoptotic cell death is presented. The role of humanin (HN), a prominent member of a newly discovered family of mitochondrial-derived peptides (MDPs) expressed from an open reading frame of mitochondrial 16S rRNA, in modulation of ER and oxidative stress in RPE is discussed. HN protected RPE cells from oxidative and ER stress-induced cell death by upregulation of mitochondrial GSH, inhibition of ROS generation, and caspase 3 and 4 activation. The underlying mechanisms of ER-mitochondrial crosstalk and modulation by exogenous HN are discussed. The therapeutic use of HN and related MDPs could potentially prove to be a valuable approach for treatment of AMD.


2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Xuan Yuan ◽  
Defang Li ◽  
Hong Zhao ◽  
Jiangtao Jiang ◽  
Penglong Wang ◽  
...  

Licochalcone A (LCA), a licorice chalconoid, is considered to be a bioactive agent with chemopreventive potential. This study investigated the mechanisms involved in LCA-induced apoptosis in human bladder cancer T24 cells. LCA significantly inhibited cells proliferation, increased reactive oxygen species (ROS) levels, and caused T24 cells apoptosis. Moreover, LCA induced mitochondrial dysfunction, caspase-3 activation, and poly-ADP-ribose polymerase (PARP) cleavage, which displayed features of mitochondria-dependent apoptotic signals. Besides, exposure of T24 cells to LCA triggered endoplasmic reticulum (ER) stress; as indicated by the enhancement in 78 kDa glucose-regulated protein (GRP 78), growth arrest and DNA damage-inducible gene 153/C/EBP homology protein (GADD153/CHOP) expression, ER stress-dependent apoptosis is caused by the activation of ER-specific caspase-12. All the findings from our study suggest that LCA initiates mitochondrial ROS generation and induces oxidative stress that consequently causes T24 cell apoptosis via the mitochondria-dependent and the ER stress-triggered signaling pathways.


Antioxidants ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 117
Author(s):  
Phuong Linh Nguyen ◽  
Chang Hoon Lee ◽  
Heesoon Lee ◽  
Jungsook Cho

Chemotherapy has been a standard intervention for a variety of cancers to impede tumor growth, mainly by inducing apoptosis. However, development of resistance to this regimen has led to a growing interest and demand for drugs targeting alternative cell death modes, such as paraptosis. Here, we designed and synthesized a novel derivative of a pyrazolo[3,4-h]quinoline scaffold (YRL1091), evaluated its cytotoxic effect, and elucidated the underlying molecular mechanisms of cell death in MDA-MB-231 and MCF-7 breast cancer (BC) cells. We found that YRL1091 induced cytotoxicity in these cells with numerous cytoplasmic vacuoles, one of the distinct characteristics of paraptosis. YRL1091-treated BC cells displayed several other distinguishing features of paraptosis, excluding autophagy or apoptosis. Briefly, YRL1091-induced cell death was associated with upregulation of microtubule-associated protein 1 light chain 3B, downregulation of multifunctional adapter protein Alix, and activation of extracellular signal-regulated kinase 1/2 and c-Jun N-terminal kinase. Furthermore, the production of reactive oxygen species (ROS) and newly synthesized proteins were also observed, subsequently causing ubiquitinated protein accumulation and endoplasmic reticulum (ER) stress. Collectively, these results indicate that YRL1091 induces paraptosis in BC cells through ROS generation and ER stress. Therefore, YRL1091 can serve as a potential candidate for the development of a novel anticancer drug triggering paraptosis, which may provide benefit for the treatment of cancers resistant to conventional chemotherapy.


Cancers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 4173
Author(s):  
Faustino Mollinedo ◽  
Consuelo Gajate

Pancreatic ductal adenocarcinoma (PDAC), the most common malignancy of the pancreas, shows a dismal and grim overall prognosis and survival rate, which have remained virtually unchanged for over half a century. PDAC is the most lethal of all cancers, with the highest mortality-to-incidence ratio. PDAC responds poorly to current therapies and remains an incurable malignancy. Therefore, novel therapeutic targets and drugs are urgently needed for pancreatic cancer treatment. Selective induction of apoptosis in cancer cells is an appealing approach in cancer therapy. Apoptotic cell death is highly regulated by different signaling routes that involve a variety of subcellular organelles. Endoplasmic reticulum (ER) stress acts as a double-edged sword at the interface of cell survival and death. Pancreatic cells exhibit high hormone and enzyme secretory functions, and thereby show a highly developed ER. Thus, pancreatic cancer cells display a prominent ER. Solid tumors have to cope with adverse situations in which hypoxia, lack of certain nutrients, and the action of certain antitumor agents lead to a complex interplay and crosstalk between ER stress and autophagy—the latter acting as an adaptive survival response. ER stress also mediates cell death induced by a number of anticancer drugs and experimental conditions, highlighting the pivotal role of ER stress in modulating cell fate. The alkylphospholipid analog prototype edelfosine is selectively taken up by tumor cells, accumulates in the ER of a number of human solid tumor cells—including pancreatic cancer cells—and promotes apoptosis through a persistent ER-stress-mediated mechanism both in vitro and in vivo. Here, we discuss and propose that direct ER targeting may be a promising approach in the therapy of pancreatic cancer, opening up a new avenue for the treatment of this currently incurable and deadly cancer. Furthermore, because autophagy acts as a cytoprotective response to ER stress, potentiation of the triggering of a persistent ER response by combination therapy, together with the use of autophagy blockers, could improve the current gloomy expectations for finding a cure for this type of cancer.


2019 ◽  
Vol 19 (9) ◽  
pp. 1184-1195
Author(s):  
Didem Karakas ◽  
Buse Cevatemre ◽  
Arzu Y. Oral ◽  
Veysel T. Yilmaz ◽  
Engin Ulukaya

Background:Prostate cancer is one of the most common cancer types and it is the sixth leading cause of cancer-related death in men worldwide. Even though novel treatment modalities have been developed, it still a lifethreatening disease. Therefore novel compounds are needed to improve the overall survival.Methods:In our study, it was aimed to evaluate the anti-cancer activity of newly synthesized Platinum (II) [Pt(II)] complex on DU145, LNCaP and PC-3 prostate cancer cell lines. The cytotoxic activity of Pt(II) complex was tested by SRB and ATP cell viability assays. To detect the mode of cell death; fluorescent staining, flow cytometry and western blot analyses were performed.Results:The Pt(II) complex treatment resulted in a decrease in cell viability and increasing levels of apoptotic markers (pyknotic nuclei, annexin-V, caspase 3/7 activity) and a decrease in mitochondrial membrane potential in a dose dependent manner. Among cell types, tested PC-3 cells were found to be more sensitive to Pt(II) complex, demonstrating elevation of DNA damage in this cell line. In addition, Pt(II) complex induced Endoplasmic Reticulum (ER) stress by triggering ROS generation. More importantly, pre-treatment with NAC alleviated Pt(II) complex-mediated ER stress and cell death in PC-3.Conclusion:These findings suggest an upstream role of ROS production in Pt(II) complex-induced ER stressmediated apoptotic cell death. Considering the ROS-mediated apoptosis inducing the effect of Pt(II) complex, it warrants further evaluation as a novel metal-containing anticancer drug candidate.


2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Marianna Holczer ◽  
Boglárka Besze ◽  
Veronika Zámbó ◽  
Miklós Csala ◽  
Gábor Bánhegyi ◽  
...  

The maintenance of cellular homeostasis is largely dependent on the ability of cells to give an adequate response to various internal and external stimuli. We have recently proposed that the life-and-death decision in endoplasmic reticulum (ER) stress response is defined by a crosstalk between autophagy, apoptosis, and mTOR-AMPK pathways, where the transient switch from autophagy-dependent survival to apoptotic cell death is controlled by GADD34. The aim of the present study was to investigate the role of epigallocatechin-3-gallate (EGCG), the major polyphenol of green tea, in promoting autophagy-dependent survival and to verify the key role in connecting GADD34 with mTOR-AMPK pathways upon prolonged ER stress. Our findings, obtained by using HEK293T cells, revealed that EGCG treatment is able to extend cell viability by inducing autophagy. We confirmed that EGCG-induced autophagy is mTOR-dependent and PKA-independent; furthermore, it also required ULK1. We show that pretreatment of cells with EGCG diminishes the negative effect of GADD34 inhibition (by guanabenz or siGADD34 treatment) on autophagy. EGCG was able to delay apoptotic cell death by upregulating autophagy-dependent survival even in the absence of GADD34. Our data suggest a novel role for EGCG in promoting cell survival via shifting the balance of mTOR-AMPK pathways in ER stress.


Reproduction ◽  
2020 ◽  
Vol 160 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Marta Almada ◽  
Lia Costa ◽  
Bruno Fonseca ◽  
Patrícia Alves ◽  
Jorge Braga ◽  
...  

Proliferation, differentiation and apoptosis of trophoblast cells are required for normal placental development. Impairment of those processes may lead to pregnancy-related diseases. Disruption of endoplasmic reticulum (ER) homeostasis has been associated with several reproductive pathologies including recurrent pregnancy loss and preeclampsia. In the unfolded protein response (UPR), specific ER-stress signalling pathways are activated to restore ER homeostasis, but if the adaptive response fails, apoptosis is triggered. Protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1) and Activating transcription factor 6 (ATF6) are central players in UPR and in ER-stress-induced apoptosis, as well as downstream transcription factors, as C/EBP homologous protein (CHOP). Our previous studies have shown that the endocannabinoid 2-arachidonoylglycerol (2-AG) modulates trophoblast cell turnover. Nevertheless, the role of ER-stress on 2-AG induced apoptosis and cannabinoid signalling in trophoblast has never been addressed. In this work, we used BeWo cells and human primary cytotrophoblasts isolated from term-placenta. The expression of ER-stress markers was analysed by qRT-PCR and Western blotting. ROS generation was assessed by fluorometric methods, while apoptosis was detected by the evaluation of caspase -3/-7 activities and Poly (ADP-ribose) polymerase (PARP) cleavage. Our findings indicate that 2-AG is able to induce ER-stress and apoptosis. Moreover, the eukaryotic initiation factor 2 (eIF2α)/CHOP pathway involved in ER-stress-induced apoptosis is triggered through a mechanism dependent on cannabinoid receptor CB2 activation. The results bring novel insights on the importance of ER-stress and cannabinoid signalling on 2-AG mechanisms of action in placenta.


PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e86753 ◽  
Author(s):  
Xiuli Lu ◽  
Yang Li ◽  
Weiqi Wang ◽  
Shuchao Chen ◽  
Ting Liu ◽  
...  

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