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Philosophical Transactions of the Royal... Feb 2019Nucleic acids are a rapidly emerging therapeutic modality with the potential to become the third major drug modality alongside antibodies and small molecules. Owing to... (Review)
Review
Nucleic acids are a rapidly emerging therapeutic modality with the potential to become the third major drug modality alongside antibodies and small molecules. Owing to the unfavourable physico-chemical characteristics of nucleic acids, such as large size and negative charge, intracellular delivery remains a fundamental challenge to realizing this potential. Delivery technologies such as lipids, polymers and peptides have been used to facilitate delivery, with many of the most successful technologies using macropinocytosis to gain cellular entry; mostly by default rather than design. Fundamental knowledge of macropinocytosis is rapidly growing, presenting opportunities to better tailor design strategies to target this pathway. Furthermore, certain types of tumour cells have been observed to have high levels of macropinocytic activity and traffic cargo to favourable destinations within the cell for endosomal release, providing unique opportunities to further use this entry route for drug delivery. In this article, we review the delivery systems reported to be taken up by macropinocytosis and what is known about the mechanisms for regulating macropinocytosis in tumour cells. From this analysis, we identify new opportunities for exploiting this pathway for the intracellular delivery of nucleic acids to tumour cells. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.
Topics: Drug Delivery Systems; Nucleic Acids; Pinocytosis; Tumor Cells, Cultured
PubMed: 30967005
DOI: 10.1098/rstb.2018.0156 -
Trends in Cancer Jan 2022Macropinocytosis, an evolutionarily conserved endocytic mechanism that mediates non-specific fluid-phase uptake, is potently upregulated by various oncogenic pathways.... (Review)
Review
Macropinocytosis, an evolutionarily conserved endocytic mechanism that mediates non-specific fluid-phase uptake, is potently upregulated by various oncogenic pathways. It is now well appreciated that high macropinocytic activity is a hallmark of many human tumors, which use this adaptation to scavenge extracellular nutrients for fueling cell growth. In the context of the nutrient-scarce tumor microenvironment, this process provides tumor cells with metabolic flexibility. However, dependence on this scavenging mechanism also illuminates a potential metabolic vulnerability. As such, there is a great deal of interest in understanding the molecular underpinnings of macropinocytosis. In this review, we will discuss the most recent advances in characterizing macropinocytosis: the pathways that regulate it, its contribution to the metabolic fitness of cancer cells, and its therapeutic potential.
Topics: Carcinogenesis; Humans; Neoplasms; Oncogenes; Pinocytosis; Tumor Microenvironment
PubMed: 34649835
DOI: 10.1016/j.trecan.2021.09.004 -
Journal of Virology Feb 2018Kaposi's sarcoma-associated herpesvirus (KSHV) infection of dermal endothelial cells begins with its binding to host cell surface receptor molecules such as heparan... (Review)
Review
Kaposi's sarcoma-associated herpesvirus (KSHV) infection of dermal endothelial cells begins with its binding to host cell surface receptor molecules such as heparan sulfate (HS), integrins (α3β1, αVβ3, and αVβ5), xCT, and EphA2 receptor tyrosine kinase (EphA2R). These initial events initiate dynamic host protein-protein interactions involving a multimolecular complex of receptors, signal molecules (focal adhesion kinase [FAK], Src, phosphatidylinositol 3-kinase [PI3-K], and RhoA-GTPase), adaptors (c-Cbl, CIB1, Crk, p130Cas, and GEF-C3G), actin, and myosin II light chain that lead to virus entry via macropinocytosis. Here we discuss how KSHV hijacks c-Cbl, an E3 ubiquitin ligase, to monoubiquitinate the receptors and actin, which acts like a marker for trafficking (similar to zip codes), resulting in the recruitment of the members of the host endosomal sorting complexes required for transport (ESCRT) Hrs, Tsg101, EAP45, and the CHMP5 and -6 proteins (zip code readers) recognizing the ubiquitinated protein and adaptor machinery to traffic through the different endosomal compartments in the cytoplasm to initiate the macropinocytic process and infection.
Topics: Endosomal Sorting Complexes Required for Transport; Endothelial Cells; Herpesviridae Infections; Herpesvirus 8, Human; Humans; Pinocytosis; Proto-Oncogene Proteins c-cbl; Signal Transduction; Ubiquitination; Virus Internalization
PubMed: 29167336
DOI: 10.1128/JVI.01376-17 -
Journal of Virology Feb 2017Viral entry represents the first step of every viral infection and is a determinant for the host range and disease potential of a virus. Here, we review the latest... (Review)
Review
Viral entry represents the first step of every viral infection and is a determinant for the host range and disease potential of a virus. Here, we review the latest developments on cell entry of the highly pathogenic Old World arenavirus Lassa virus, providing novel insights into the complex virus-host cell interaction of this important human pathogen. We will cover new discoveries on the molecular mechanisms of receptor recognition, endocytosis, and the use of late endosomal entry factors.
Topics: Animals; Dystroglycans; Endocytosis; Endosomes; Host-Pathogen Interactions; Humans; Lassa Fever; Lassa virus; Lysosomal-Associated Membrane Protein 1; Pinocytosis; Receptors, Virus; Viral Tropism; Virus Internalization
PubMed: 27928003
DOI: 10.1128/JVI.01902-16 -
Frontiers in Pharmacology 2021Qingfei Paidu decoction (QPD) and Xuanfei Baidu decoction (XBD) are two typical traditional Chinese medicines with proven efficacy for the treatment of SARS-CoV-2,...
Traditional Chinese Medicine, Qingfei Paidu Decoction and Xuanfei Baidu Decoction, Inhibited Cytokine Production NF-κB Signaling Pathway in Macrophages: Implications for Coronavirus Disease 2019 (COVID-19) Therapy.
Qingfei Paidu decoction (QPD) and Xuanfei Baidu decoction (XBD) are two typical traditional Chinese medicines with proven efficacy for the treatment of SARS-CoV-2, although the underlying mechanism is not well defined. Blunted immune response and enhanced production of pro-inflammatory cytokines (cytokine storm) are two main features observed in patients infected with SARS-CoV-2. Analysis based on network pharmacology has revealed that both QPD and XBD played an important role in the regulation of host immunity. We therefore investigated the role of QPD and XBD in the modulation of innate immunity , focusing on the type 1 interferon (IFN) signaling pathway in A549 cells and pro-inflammatory cytokine production in macrophages. A549 cells were treated with QPD or XBD and the production of endogenous IFNα and IFNβ as well as the expression levels of some interferon-stimulated genes (ISGs) were detected by reverse transcriptase-quantitative PCR (RT-qPCR). Macrophages derived from THP-1 cells were treated with QPD or XBD and their pro-inflammatory cytokine expression levels were measured by RT-qPCR, 6 h post LPS stimulation. In addition, the expression levels of some pro-inflammatory cytokines were further analyzed by ELISA. The effect of QPD and XBD on the NF-κB signaling pathway and the pinocytosis activity of THP-1-derived macrophages were evaluated by Western blot and neutral red uptake assay, respectively. Although QPD and XBD showed very little effect on the type 1 IFN signaling pathway in A549 cells, either QPD or XBD markedly inhibited the production of pro-inflammatory markers including interleukin-6, tumor necrosis factor-α, monocyte chemotactic protein-1, and chemokine ligand 10 in THP-1-derived M1 macrophages. In addition, the phosphorylation of IκBα and NF-κB p65 during the process of macrophage polarization was significantly suppressed following QPD or XBD treatment. QPD and XBD also suppressed the pinocytosis activity of macrophages. QPD and XBD have been shown to have robust anti-inflammatory activities . Our study demonstrated that both QPD and XBD decreased pro-inflammatory cytokine expression, inhibited the activation of the NF-κB signaling pathway, and blunted pinocytosis activity in THP-1-derived macrophages.
PubMed: 34764867
DOI: 10.3389/fphar.2021.722126 -
Cancer Research Aug 2018Macropinocytosis has emerged as an important pathway of protein acquisition in cancer cells, particularly in tumors with activated Ras such as pancreatic and colon...
Macropinocytosis has emerged as an important pathway of protein acquisition in cancer cells, particularly in tumors with activated Ras such as pancreatic and colon cancer. Macropinocytosis is also the route of entry of Bacillus Calmette-Guerin (BCG) and other microbial therapies of cancer. Despite this important role in tumor biology and therapy, the full mechanisms by which cancer cells can activate macropinocytosis remain incompletely defined. Using BCG uptake to assay macropinocytosis, we executed a genome-wide shRNA screen for macropinocytosis activators and identified Wnt pathway activation as a strong driver of macropinocytosis. Wnt-driven macropinocytosis was downstream of the β-catenin-dependent canonical Wnt pathway, was PAK1 dependent, and supported albumin-dependent growth in Ras-WT cells. In cells with activated Ras-dependent macropinocytosis, pharmacologic or genetic inhibition of Wnt signaling suppressed macropinocytosis. In a mouse model of Wnt-driven colonic hyperplasia via silencing, Wnt-activated macropinocytosis stimulated uptake of luminal microbiota, a process reversed by topical pharmacologic inhibition of macropinocytosis. Our findings indicate that Wnt pathway activation drives macropinocytosis in cancer, and its inhibition could provide a therapeutic vulnerability in Wnt-driven intestinal polyposis and cancers with Wnt activation. The Wnt pathway drives macropinocytosis in cancer cells, thereby contributing to cancer growth in nutrient-deficient conditions and, in the context of colon cancer, to the early phases of oncogenesis. .
Topics: Adenomatous Polyposis Coli Protein; Animals; Cell Line, Tumor; Gene Silencing; Genome, Human; Humans; Mice; Mycobacterium bovis; Neoplasms; Pinocytosis; RNA, Small Interfering; Wnt Signaling Pathway; beta Catenin
PubMed: 29871936
DOI: 10.1158/0008-5472.CAN-17-3199 -
British Journal of Cancer Sep 2016Cancer is fundamentally a disease of uncontrolled cell proliferation. Tumour metabolism has emerged as an exciting new discipline studying how cancer cells obtain the... (Review)
Review
Cancer is fundamentally a disease of uncontrolled cell proliferation. Tumour metabolism has emerged as an exciting new discipline studying how cancer cells obtain the necessary energy and cellular 'building blocks' to sustain growth. Glucose and glutamine have long been regarded as the key nutrients fuelling tumour growth. However, the inhospitable tumour microenvironment of certain cancers, like pancreatic cancer, causes the supply of these nutrients to be chronically insufficient for the demands of proliferating cancer cells. Recent work has shown that cancer cells are able to overcome this nutrient insufficiency by scavenging alternative substrates, particularly proteins and lipids. Here, we review recent work identifying the endocytic process of macropinocytosis and subsequent lysosomal processing as an important substrate-acquisition route. In addition, we discuss the impact of hypoxia on fatty acid metabolism and the relevance of exogenous lipids for supporting tumour growth as well as the routes by which tumour cells can access these lipids. Together, these cancer-specific scavenging pathways provide a promising opportunity for therapeutic intervention.
Topics: Animals; Autophagy; Cell Division; Cell Hypoxia; Energy Metabolism; Fatty Acids; Humans; Lipid Metabolism; Macromolecular Substances; Metabolomics; Neoplasm Proteins; Neoplasms; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Pinocytosis; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases
PubMed: 27537393
DOI: 10.1038/bjc.2016.256 -
Frontiers in Nutrition 2020Desert truffles have high nutritional value and grow wild in the Mediterranean basin and Western Asia. Although, many studies were performed to evaluate truffles...
Desert truffles have high nutritional value and grow wild in the Mediterranean basin and Western Asia. Although, many studies were performed to evaluate truffles nutritious values and phytochemical composition, studies are limited to evaluate their anticancer and/ or immunomodulatory effects. Our study was conducted to evaluate the anticancer and immunomodulatory effects of (desert truffle). Different solvent extracts were prepared from the truffle and MTT assay was used to measure their anticancer activity against cancer cell lines (T47D, MCF-7, MDA-MB231, HCT-116, and Hela). Total phenolic content in each extract was determined by using Folin-Ciocalteu reagent and qualitative phytochemical screening was performed using standard methods. The degree of apoptosis induction (using caspase 3 assay) and vascular endothelial growth factor expression were detected using standard kits. Also, ELISA was used to measure levels of IFN-γ, IL-2, IL-4, and IL-10 secreted by splenocytes after treatment with the extracts. The effect of the extracts on splenocytes proliferation was measured using MTT assay. Macrophage function was evaluated using nitro blue tetrazolium assay and pinocytosis function was evaluated using neutral red method. Terpenoids, phytosterols, and carbohydrates were present in all the solvent extracts, while tannins, alkaloids and flavonoids were detected only in aqueous/methanol and aqueous extracts. The highest total phenolic content was observed in aqueous and aqueous methanol extracts. The growth of cancer cell lines was inhibited by extracts in a dose dependent manner. N-hexane extract was the most potent against most cell lines. Aqueous/methanol extract showed high apoptosis induction and angiogenesis suppression effects. An increase in TH1 cytokines (IFN-γ, IL-2) level and a decrease in TH2 cytokine (IL-4) level were evident after lymphocytes stimulation by aqueous/methanol, n-hexane and ethyl acetate extracts of . Ethyl acetate extract of were the most potent extracts to stimulate lymphocytes proliferation while all other extracts showed moderate stimulation. Aqueous/methanol extract was the most active extract to stimulate phagocytosis. Ethyl acetate extract was the most active extract to stimulate pinocytosis. The use of provides variable health benefits. N-hexane, ethyl acetate, and aqueous/methanol extracts exhibited anticancer activities and are potent stimulators of innate and acquired immunity. Further testing is needed to identify the biologically active compounds and detect them quantitatively using GC-MS analysis.
PubMed: 32322585
DOI: 10.3389/fnut.2020.00038 -
The Biochemical Journal Feb 2018In a role distinct from and perhaps more ancient than that in signal transduction, PIP3 and Ras help to spatially organize the actin cytoskeleton into macropinocytic...
In a role distinct from and perhaps more ancient than that in signal transduction, PIP3 and Ras help to spatially organize the actin cytoskeleton into macropinocytic cups. These large endocytic structures are extended by actin polymerization from the cell surface and have at their core an intense patch of active Ras and PIP3, around which actin polymerizes, creating cup-shaped projections. We hypothesize that active Ras and PIP3 self-amplify within macropinocytic cups, in a way that depends on the structural integrity of the cup. Signalling that triggers macropinocytosis may therefore be amplified downstream in a way that depends on macropinocytosis. This argument provides a context for recent findings that signalling to Akt (an effector of PIP3) is sensitive to cytoskeletal and macropinocytic inhibitors.
Topics: Actin Cytoskeleton; Cell Membrane; Dictyostelium; Humans; Pinocytosis; Proto-Oncogene Proteins c-akt; Signal Transduction
PubMed: 29444849
DOI: 10.1042/BCJ20170785 -
Prion Mar 2016Temporal and spatial patterns of pathological changes such as loss of neurons and presence of pathological protein aggregates are characteristic of neurodegenerative... (Review)
Review
Temporal and spatial patterns of pathological changes such as loss of neurons and presence of pathological protein aggregates are characteristic of neurodegenerative diseases such as Amyotrophic Lateral Sclerosis, Frontotemporal Dementia, Alzheimer's disease and Parkinson's disease. These patterns are consistent with the propagation of protein misfolding and aggregation reminiscent of the prion diseases. There is a surge of evidence that suggests that large protein aggregates of a range of proteins are able to enter cells via macropinocytosis. Our recent work suggests that this process is activated by the binding of aggregates to the neuron cell surface. The current review considers the potential role of cell surface receptors in the triggering of macropinocytosis by protein aggregates and the possibility of utilizing macropinocytosis pathways as a therapeutic target.
Topics: Animals; Humans; Neurodegenerative Diseases; Neurons; Pinocytosis; Protein Aggregation, Pathological; Protein Folding
PubMed: 26963158
DOI: 10.1080/19336896.2016.1141860