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Introduction to Cancer, Conventional Therapies, and Bionano-Based Advanced Anticancer Strategies
Published in D. Sakthi Kumar, Aswathy Ravindran Girija, Bionanotechnology in Cancer, 2023
It is a self-digestion process, which is also another source of cell death. It is the process where it removes and degrades the damaged cellular constituents by which a small portion of cellular components are isolated from the rest of the cell to form a double layered vesicle called autophagosome. Autophagosome further fuses with lysosome having low pH (acidic) and later endosome to form autolysosome. When autophagy and lysosome degradation is disturbed, Cathespin B is released from lysosome to trigger mitochondrial permeabalization and caspase activation. Cathespin D is translocated from lysosome to cytosol, which is responsible for Bax activation and apoptotic induced factor release. In addition, caspase cleave autophagy relative proteins, such as Beclin1, Bcl-2, P53, and UV-irradiation resistance gene (UVRAG), are several tumor proteins that regulate autophagy.
Nanoparticle–Based RNA (siRNA) Combination Therapy Toward Overcoming Drug Resistance in Cancer
Published in Loutfy H. Madkour, Nanoparticle-Based Drug Delivery in Cancer Treatment, 2022
Autophagy is considered to be a cytoprotective process involved in the normal turnover of long-lived proteins and whole organelles to maintain a healthy cellular status [157]. However, recent data strongly demonstrate that autophagy is intimately linked to apoptosis or necrosis and serves both pro-survival and pro-death functions. Autophagy regulation requires an orchestrated interplay between many signaling molecules, including mammalian target of rapamycin (mTOR) kinase, which has the most potent impact on autophagy [158,159]. Once activated, mTOR inhibits autophagy via the phosphorylation of autophagy-related proteins. AMP activated protein kinase (AMPK) activation can lead to autophagy by negatively regulating mTOR [160,161]. The tumor suppressor protein p53 can trigger autophagy by phosphorylating AMPK and further inhibiting the mTOR signaling pathway [160]. Beclin-1 also plays a critical role in autophagosome formation and crosstalk between autophagy and apoptosis [161]. The BH3 domain-mediated binding of Beclin-1 to B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma-extra large (Bcl-XL) inhibits autophagy. However, the c-Jun N-terminal kinase (JNK) 1- or extracellular signal-regulated kinase (ERK)-mediated phosphorylation of Bcl-2 or death-associated protein kinase-mediated phosphorylation of Beclin-1 induces the dissociation of the Beclin-1–Bcl-2/Bcl-XL complex, thus inhibiting autophagy [161–165]. Intracellular calcium ions (Ca2+) can regulate the activation of JNK and the apoptotic signaling pathway [166].
Metals, Metal Oxides, and Their Composites—Safety and Health Awareness
Published in Vijay B. Pawade, Paresh H. Salame, Bharat A. Bhanvase, Multifunctional Nanostructured Metal Oxides for Energy Harvesting and Storage Devices, 2020
There are several examples in the literature about the effect of size on toxicity of Au NPs. It is observed that there is a high toxicity of Au NPs having a size of the order of 1.4 nm in Au55 nanoclusters toward several cancer and healthy cells in humans. The greater toxicity is attributed to the perfect match between the size and the principle groove in DNA. Au NPs with sizes of 0.8, 1.2, 1.4, and 1.8 nm containing clusters of 8, 35, 55, and 150 Au atoms, respectively, and 15-nm NPs are capped with triphenylphosphine and its derivatives and studied. It was observed that the clusters containing NPs with size 1.4 nm were highly cytotoxic with half of maximum inhibitory concentration (IC50) varying between 30 and 46 μM [351]. The 15-nm NPs were noncytotoxic even at concentration 100 times more than IC50 for the smaller clusters. Thus, it can be said that the 1.4 nm NPs led to cell necrosis following 12 h incubation while the 1.2 nm ones led to apoptosis. Furthermore, it is understood that Au NPs may affect autophagy, a lysosome-based degradative pathway, and are instrumental in maintaining cellular homeostasis. Intracellular matter is surrounded by double-membrane vesicles referred to as autophagosomes during this process. Au NPs enhance the piling up of autophagosomes in cells due to stifling autophagy flux than induces autophagy [352].
Therapeutic potential of a 2,2’-bipyridine-based vanadium(IV) complex on HepG2 cells: cytotoxic effects and molecular targeting
Published in Egyptian Journal of Basic and Applied Sciences, 2023
Eman Salah El-Shafey, Eslam Samy Elsherbiny
Autophagy (type II cell death) is a cellular degradation route that depends on lysosomal degradation system in its activity and is triggered as a response to a diversity of ecological and cellular strains [9,10]. Generally, autophagic machinery is accomplished by a series of proteins that are encoded by autophagy-related Genes (ATGs) [11]. The mammalian ATG proteins are intricate in triggering diverse steps during autophagosome formation. Moreover, LC3 is involved in autophagosome formation and considered as the extensively utilized marker to monitor autophagy [12]. Numerous signaling networks (e.g. mTOR, insulin pathways) and the ER stress response mediated the basic elementary implicated in the autophagic machinery [13]. The double-edged role of autophagy is mediated by diverse mechanisms that control either cellular survival or cellular death [14]. However, extensive diversity of pathophysiological conditions including cancers is dependent on impairment of the autophagic function [15].
A review of microalgal cell wall composition and degradation to enhance the recovery of biomolecules for biofuel production
Published in Biofuels, 2023
Syafiqah Md Nadzir, Norjan Yusof, Norazela Nordin, Azlan Kamari, Mohd Zulkhairi Mohd Yusoff
In contrast, paraptosis is a non-apoptotic form of PCD accompanied by endoplasmic reticulum and mitochondrial dilation, chromatin spotting without DNA fragmentation, significant cytoplasmic swelling and vacuolation, and alternative caspase activation [127]. It is mediated by mitogen-activated protein kinases and differs significantly from apoptosis due to the absence of caspase activity [128]. Another non-apoptotic form of PCD, depending on the presence of iron, is ferroptosis. It is associated with lipid peroxidation and accumulation of ROS [129]. Iron molecules induce harmful lipid accumulation by ROS, which is mediated by inhibition of cysteine import and glutathione depletion [130]. Autophagy, in contrast, is a type of PCD marked by a rise in the number of autophagosomes, autolysosomes, and small lytic vacuoles. It is a catabolic process induced by the autophagy gene (atg) that degrades long-lived organelles and proteins. Autophagy can be used to selectively degrade organelles such as mitochondria (mitophagy) and ribosomes (ribophagy), as well as misfolded and aggregated proteins [131,132]. The early stage of autophagy consists of the induction and formation of autophagosomes, whereas the late stage includes the fusion of autophagosomes and lysosomes, followed by degradation of the fusion complex and reformation of lysosomes [133].
Exenatide promotes the autophagic function in the diabetic hippocampus: a review
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Eman Mohammed Elsaeed, Ahmed Gamal Abdelghafour Hamad, Omnia S. Erfan, Mona A. El-Shahat, Fathy Abd Elghany Ebrahim
Another marker of autophagy is p62, which is located on chromosome 5 and expressed in all tissues. It is an adaptor protein with an LC3-interacting region; thus, it undergoes degradation with LC3 present in the inner membrane of the autophagosome. It has a role in nucleation induction of the autophagosome membrane, followed by recruitment of ubiquitylated proteins and degradation through autophagy [17, 25, 26]. Consequently, autophagy activation is accompanied by a decrease in the p62 level [19]. To sum up, autophagy activation can be detected by analysis of LC3 and p62 in tandem, where it is anticipated to have an increased ratio of LC3-II to LC3-I and a reduction in p62 protein level [27].