Advances in paraganglioma–pheochromocytoma cell lines and xenografts

This review describes human and rodent-derived cell lines and xenografts developed over the last five decades that are suitable or potentially suitable models for paraganglioma–pheochromocytoma research. We outline the strengths and weaknesses of various models and emphasize the recurring theme that, despite the major challenges involved, more effort is required in the search for valid human and animal cell models of paraganglioma–pheochromocytoma, particularly those relevant to cancers carrying a mutation in one of the succinate dehydrogenase genes. Despite many setbacks, the recent development of a potentially important new model, the RS0 cell line, gives reason for optimism regarding the future of models in the paraganglioma–pheochromocytoma field. We also note that classic approaches to cell line derivation such as SV40-mediated immortalization and newer approaches such as organoid culture or iPSCs have been insufficiently explored. As many existing cell lines have been poorly characterized, we provide recommendations for reporting of paraganglioma and pheochromocytoma cell lines, including the strong recommendation that cell lines are made widely available via the ATCC or a similar cell repository. Basic research in paraganglioma–pheochromocytoma is currently transitioning from the analysis of genetics to the analysis of disease mechanisms and the clinically exploitable vulnerabilities of tumors. A successful transition will require many more disease-relevant human and animal models to ensure continuing progress.

Anti-Tumor Activity vs. Normal Cell Toxicity: Therapeutic Potential of the Bromotyrosines Aerothionin and Homoaerothionin In Vitro

Novel strategies to treat cancer effectively without adverse effects on the surrounding normal tissue are urgently needed. Marine sponges provide a natural and renewable source of promising anti-tumor agents. Here, we investigated the anti-tumor activity of Aerothionin and Homoaerothionin, two bromotyrosines isolated from the marine demosponge Aplysina cavernicola, on two mouse pheochromocytoma cells, MPC and MTT. To determine the therapeutic window of these metabolites, we furthermore explored their cytotoxicity on cells of the normal tissue. Both metabolites diminished the viability of the pheochromocytoma cell lines significantly from a concentration of 25 µM under normoxic and hypoxic conditions. Treatment of MPC cells leads moreover to a reduction in the number of proliferating cells. To confirm the anti-tumor activity of these bromotyrosines, 3D-pheochromocytoma cell spheroids were treated with 10 µM of either Aerothionin or Homoaerothionin, resulting in a significant reduction or even complete inhibition of the spheroid growth. Both metabolites reduced viability of normal endothelial cells to a comparable extent at higher micromolar concentration, while the viability of fibroblasts was increased. Our in vitro results show promise for the application of Aerothionin and Homoaerothionin as anti-tumor agents against pheochromocytomas and suggest acceptable toxicity on normal tissue cells.

Synergistic Neuroprotective Effect of Endogenously-Produced Hydroxytyrosol and Synaptic Vesicle Proteins on Pheochromocytoma Cell Line against Salsolinol

Oxidative stress triggers a lethal cascade, leading to Parkinson’s disease by causing degeneration of dopaminergic neurons. In this study, eight antioxidants were screened for their neuroprotective effect on PC12 cells (pheochromocytoma cell line) under oxidative stress induced by salsolinol (OSibS). Hydroxytyrosol was found to be the strongest neuroprotective agent; it improved viability of PC12 cells by up to 81.69% under OSibS. Afterward, two synaptic vesicle proteins, synapsin-1 and septin-5, were screened for their neuroprotective role; the overexpression of synapsin-1 and the downregulation of septin-5 separately improved the viability of PC12 cells by up to 71.17% and 67.00%, respectively, compared to PC12 cells only treated with salsolinol (PoTwS) under OSibS. Subsequently, the PC12+syn++sep− cell line was constructed and pretreated with 100 µM hydroxytyrosol, which improved its cell viability by up to 99.03% and led to 14.71- and 6.37-fold reductions in the levels of MDA and H2O2, respectively, and 6.8-, 12.97-, 10.57-, and 7.57-fold increases in the activity of catalase, glutathione reductase, superoxide dismutase, and glutathione peroxidase, respectively, compared to PoTwS under OSibS. Finally, alcohol dehydrogenase-6 from Saccharomyces cerevisiae was expressed in PC12+syn++sep− cells to convert 3,4-dihydroxyphenylacetaldehyde (an endogenous neurotoxin) into hydroxytyrosol. The PC12+syn++sep−+ADH6+ cell line also led to 22.38- and 12.33-fold decreases in the production of MDA and H2O2, respectively, and 7.15-, 13.93-, 12.08-, and 8.11-fold improvements in the activity of catalase, glutathione reductase, superoxide dismutase, and glutathione peroxidase, respectively, compared to PoTwS under OSibS. Herein, we report the endogenous production of a powerful antioxidant, hydroxytyrosol, from 3,4-dihydroxyphenylacetaldehyde, and evaluate its synergistic neuroprotective effect, along with synapsin-1 and septin-5, on PC12 cells under OSibS.

Antioxidative and Neuroprotective Effects of the Cytochalasans From Endophytes

Six 10-indolyl-cytochalasans, chaetoglobosin F (1), chaetoglobosin Fex (2), chaetoglobosin E (3), cytoglobosin A (4), penochalasin C (5), and isochaetoglobosin D (6), and 2 10-phenyl-cytochalasans, cytochalasin H (7) and 18-methoxycytochalasin J (8) were isolated from 2 plant endophytes, Chaetomiun globosum WQ and Phomopsis sp. IFB-E060, respectively. These cytochalasans were investigated with radical-scavenging activity assay and hydrogen peroxide (H2O2)/ N-methyl-4-phenylpyridinium iodide (MPP+)-induced pheochromocytoma cell line 12 (PC12) cell models, respectively. Results showed that 7 compounds had antioxidative effects except 5, with scavenging 2,2-diphenyl-1-picrylhydrazyl radical effect 1 = 6= 7 > 2> 4 = 3 > 8 and scavenging 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical effect 1 = 6 = 7 > 2 > 3 > 8 > 4. They could also inhibit H2O2/MPP+-induced damage in PC12 cells by increasing cell viability and decreasing lactate dehydrogenase release. Compounds 1, 6, and 7 exhibited the strongest antioxidative potencies, which are more potent than vitamin E. Additionally, antioxidative and neuroprotective effects of 1∼8 showed some structure–activity relationship. These findings would be useful for looking for cytochalasin-related new lead compounds or drugs to prevent and treat Parkinson’s disease.

Flavonoids from the Aerial Parts of Artemisia biennis Willd

Background: The current phytochemical study was carried out on a fraction of dried polar extract of aerial parts of Artemisia biennis Willd. which was previously reported to decrease the viability of the rat pheochromocytoma cell line PC12 in cell-based antioxidant assays. Methods: A combination of solid phase extraction (SPE) and high pressure liquid chromatography (HPLC) of the hydroethanolic extract was used to purify the compounds. Structures of the isolated compounds were elucidated by spectroscopic means, including 1H-NMR and MS analyses. Results: Three isolated and identified flavonoids in this study were luteolin, kaempferol and apigenin. Conclusion: The cytotoxic potential of flavone aglycones, as the major components of selected fraction in the hydroethanolic extract of A. biennis might partly be related to the high death rate of PC12 cells.

Cytoprotective effect of Terminalia chebula Retz against Oxygen-Glucose Deprivation on Rat Pheochromocytoma Cell

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Oncometabolite induced primary cilia loss in pheochromocytoma

Primary cilia are sensory organelles involved in regulation of cellular signaling. Cilia loss is frequently observed in tumors; yet, the responsible mechanisms and consequences for tumorigenesis remain unclear. We demonstrate that cilia structure and function is disrupted in human pheochromocytomas – endocrine tumors of the adrenal medulla. This is concomitant with transcriptional changes within cilia-mediated signaling pathways that are associated with tumorigenesis generally and pheochromocytomas specifically. Importantly, cilia loss was most dramatic in patients with germline mutations in the pseudohypoxia-linked genes SDHx and VHL. Using a pheochromocytoma cell line derived from rat, we show that hypoxia and oncometabolite-induced pseudohypoxia are key drivers of cilia loss and identify that this is dependent on activation of an Aurora-A/HDAC6 cilia resorption pathway. We also show cilia loss drives dramatic transcriptional changes associated with proliferation and tumorigenesis. Our data provide evidence for primary cilia dysfunction contributing to pathogenesis of pheochromocytoma by a hypoxic/pseudohypoxic mechanism and implicates oncometabolites as ciliary regulators. This is important as pheochromocytomas can cause mortality by mechanisms including catecholamine production and malignant transformation, while hypoxia is a general feature of solid tumors. Moreover, pseudohypoxia-induced cilia resorption can be pharmacologically inhibited, suggesting potential for therapeutic intervention.