scholarly journals Vitamin C functions as double-edge sword on cancer progression depending on ERK activation or inhibition mediated by its receptor SVCT2

2022 ◽  
Author(s):  
Yian Guan ◽  
Bingxue Chen ◽  
Yongyan Wu ◽  
Zhuo Han ◽  
Hongyu Xu ◽  
...  
Keyword(s):  
Vitamin C ◽  
Cancer Progression ◽  
Feedback Inhibition ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Janus Kinase ◽  
High Dose ◽  
Erk Activation ◽  
Double Edge Sword ◽  
Cancer Phenotypes

The effect of Vitamin C (Vc) in oncotherapy was controversial for decades. And hyperactivation of extracellular signal-regulated kinase (ERK) drove tumorigenesis. Herein, we demonstrated that Vc activated ERK through sodium-dependent Vc transporter 2 (SVCT2), while high-dose Vc resulted in persistent ERK feedback inhibition following activation. Extracellular Vc binding to SVCT2 initiated ERK activation, then transmembrane transport of Vc induced dimerization of SVCT2. Activated ERK phosphorylated protein tyrosine phosphatase non-receptor type 12 (PTPN12) at Ser434 and inhibited PTPN12 activity, thus enhancing phosphorylation of Janus kinase 2 (JAK2), which phosphorylated growth factor receptor bound protein 2 (GRB2) at Tyr160 to promote GRB2 dimers dissociation and recruitment of GRB2 to SVCT2, leading to further ERK activation. Different cancers have different sensitivities to Vc, the dose effects of Vc on cancer phenotypes depended on that ERK was activated or inhibited. These findings suggest SVCT2 is a Vc receptor mediating the ERK-PTPN12-JAK2-GRB2-ERK positive feedback loop and a potential target for oncotherapy.

Discovery of novel non-peptide thrombopoietin mimetic compounds that induce megakaryocytopoiesis

2008 ◽  
Vol 28 (5) ◽  
pp. 275-285 ◽  
Author(s):  
Noriko Yamane ◽  
Koji Takahashi ◽  
Yoshikazu Tanaka ◽  
Kazue Kato ◽  
Masami Takayama ◽  
...  
Keyword(s):  
Cell Line ◽  
Bone Marrow Cells ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Janus Kinase ◽  
Parent Cell ◽  
Tyrosine Kinase 2 ◽  
Thrombopoietin Receptor ◽  
Src Homology ◽  
Thrombopoietin Mimetic

We have identified a series of novel non-peptide compounds that activate the thrombopoietin-dependent cell line Ba/F3-huMPL. The compounds stimulated proliferation of Ba/F3-huMPL in the absence of other growth factors, but did not promote proliferation of the thrombopoietin-independent parent cell line Ba/F3. The thrombopoietin-mimetic compounds elicited signal-transduction responses comparable with recombinant human thrombopoietin, such as tyrosine phosphorylation of the thrombopoietin receptor, JAK (Janus kinase) 2, Tyk2 (tyrosine kinase 2), STAT (signal transducer and activator of transcription) 3, STAT5, MAPKs (mitogen-activated protein kinases), PLCγ (phospholipase Cγ), Grb2 (growth-factor-receptor-bound protein 2), Shc (Src homology and collagen homology), Vav, Cbl and SHP-2 (Src homology 2 domain-containing protein tyrosine phosphatase 2) and increased the number of CD41+ cells (megakaryocyte lineage) in cultures of human CD34+ bone-marrow cells (haematopoietic stem cells). These findings suggest that this series of compounds are novel agonists of the human thrombopoietin receptor and are possible lead compounds for the generation of anti-thrombocytopaenia drugs.

scholarly journals Activated STAT5 proteins induce activation of the PI 3-kinase/Akt and Ras/MAPK pathways via the Gab2 scaffolding adapter

2005 ◽  
Vol 390 (1) ◽  
pp. 359-366 ◽  
Author(s):  
Rémy Nyga ◽  
Christian Pecquet ◽  
Noria Harir ◽  
Haihua Gu ◽  
Isabelle Dhennin-Duthille ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Janus Kinase ◽  
Scaffolding Protein ◽  
Regulatory Subunit ◽  
Growth And Survival ◽  
Mapk Pathways ◽  
Mitogen Activated Protein ◽  
Phosphoinositide 3 Kinase

The active forms of STAT5A (signal transducer and activator of transcription 5A) and STAT5B are able to relieve the cytokine dependence of haematopoietic cells and to induce leukaemia in mice. We have demonstrated previously that activation of the PI3K (phosphoinositide 3-kinase) signalling cascade plays a major role in cell growth and survival induced by these proteins. Interaction between STAT5 and p85, the regulatory subunit of the PI3K, has been suggested to be required for this activation. We show in the present study that the scaffolding protein Gab2 [Grb2 (growth-factor-receptor-bound protein 2)-associated binder-2] is an essential component of this interaction. Gab2 is persistently tyrosine-phosphorylated in Ba/F3 cells expressing caSTAT5 (constitutively activated STAT5), independent of JAK2 (Janus kinase 2) activation where it interacts with STAT5, p85 and Grb2, but not with Shp2 [SH2 (Src homology 2)-domain-containing tyrosine phosphatase] proteins. Interaction of STAT5 with Gab2 was also observed in Ba/F3 cells stimulated with interleukin-3 or expressing the oncogenic fusion protein Tel–JAK2. The MAPKs (mitogen-activated protein kinases) ERK1 (extracellular-signal-regulated kinase 1) and ERK2 were constitutively activated in the caSTAT5-expressing cells and were found to be required for caSTAT5-induced cell proliferation. Overexpression of Gab2-3YF, a mutant of Gab2 incapable of binding PI3K, inhibited the proliferation and survival of caSTAT5-expressing cells as well as ERK1/2 and Akt/protein kinase B phosphorylation. Taken together, our results indicate that Gab2 is required for caSTAT5-induced cell proliferation by regulating both the PI3K/Akt and the Ras/MAPK pathways.

Liver Histological Improvement After Administration of High-Dose Vitamin C in Guinea Pig with Nonalcoholic Steatohepatitis

2018 ◽  
Vol 88 (5-6) ◽  
pp. 263-269
Author(s):  
Seong-Hoon Park ◽  
A Lum Han ◽  
Na-Hyung Kim ◽  
Sae-Ron Shin
Keyword(s):  
Liver Biopsy ◽  
Vitamin C ◽  
Nonalcoholic Steatohepatitis ◽  
Guinea Pigs ◽  
Normal Diet ◽  
High Dose ◽  
Biochemical Tests ◽  
Deficient Diet ◽  
Histological Improvement ◽  
Vit C

Abstract. Background: Vitamin C is a strong antioxidant, and the health effects of vitamin C megadoses have not been validated despite the apparent health benefits. Therefore, the present study sought to confirm the effects of vitamin C megadoses. Materials and Methods : Four groups of six guinea pigs were used. Each group was fed one of the following diets for three weeks: normal diet, methionine choline-deficient diet, methionine choline-deficient diet + vitamin C megadose (MCD + vit C 2.5 g/kg/day), and methionine-choline deficient diet + ursodeoxycholic acid (MCD + UDCA 30 mg/kg/day). The MCD diet was given to induce nonalcoholic steatohepatitis, and UDCA was used to treat nonalcoholic steatohepatitis. Three weeks after initial diet administration, the results of biochemical tests and liver biopsy were compared between the groups. Results: The cytoplasm state was similar in the MCD + vit C and MCD + UDCA groups, exhibiting clearing of the cytoplasm and ballooning degeneration. However, macrovesicular steatosis was not observed in the MCD + vit C group. Aspartate transaminase and alanine transaminase were elevated significantly following vitamin C administration. Conclusions: The present study confirmed that alone vitamin C megadoses are potential remedies for nonalcoholic steatohepatitis, based on the liver biopsy results of guinea pigs that were unable to synthesize vitamin C.

scholarly journals Betulin, a Newly Characterized Compound in Acacia auriculiformis Bark, Is a Multi-Target Protein Kinase Inhibitor

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4599
Author(s):  
Augustine Ahmadu ◽  
Claire Delehouzé ◽  
Anas Haruna ◽  
Lukman Mustapha ◽  
Bilqis Lawal ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Kinase Inhibitor ◽  
Glycogen Synthase ◽  
Growth Factor Receptor ◽  
Binding Pocket ◽  
Stem Bark ◽  
Janus Kinase ◽  
Myelogenous Leukemia ◽  
Acacia Auriculiformis

The purpose of this work is to investigate the protein kinase inhibitory activity of constituents from Acacia auriculiformis stem bark. Column chromatography and NMR spectroscopy were used to purify and characterize betulin from an ethyl acetate soluble fraction of acacia bark. Betulin, a known inducer of apoptosis, was screened against a panel of 16 disease-related protein kinases. Betulin was shown to inhibit Abelson murine leukemia viral oncogene homolog 1 (ABL1) kinase, casein kinase 1ε (CK1ε), glycogen synthase kinase 3α/β (GSK-3 α/β), Janus kinase 3 (JAK3), NIMA Related Kinase 6 (NEK6), and vascular endothelial growth factor receptor 2 kinase (VEGFR2) with activities in the micromolar range for each. The effect of betulin on the cell viability of doxorubicin-resistant K562R chronic myelogenous leukemia cells was then verified to investigate its putative use as an anti-cancer compound. Betulin was shown to modulate the mitogen-activated protein (MAP) kinase pathway, with activity similar to that of imatinib mesylate, a known ABL1 kinase inhibitor. The interaction of betulin and ABL1 was studied by molecular docking, revealing an interaction of the inhibitor with the ABL1 ATP binding pocket. Together, these data demonstrate that betulin is a multi-target inhibitor of protein kinases, an activity that can contribute to the anticancer properties of the natural compound and to potential treatments for leukemia.

scholarly journals Protective effects and mechanisms of high-dose vitamin C on sepsis-associated cognitive impairment in rats

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ning Zhang ◽  
Wei Zhao ◽  
Zhen-Jie Hu ◽  
Sheng-Mei Ge ◽  
Yan Huo ◽  
...  
Keyword(s):  
Vitamin C ◽  
Escape Latency ◽  
Morris Water Maze Test ◽  
Protective Mechanism ◽  
High Dose ◽  
Maze Test ◽  
Tnf Α ◽  
Histopathologic Changes ◽  
High Dose Vitamin ◽  
Necrosis Factor

AbstractSepsis survivors present long-term cognitive deficits. The present study was to investigate the effect of early administration of high-dose vitamin C on cognitive function in septic rats and explore its possible cerebral protective mechanism. Rat sepsis models were established by cecal ligation and puncture (CLP). Ten days after surgery, the Morris water maze test was performed to evaluate the behavior and cognitive function. Histopathologic changes in the hippocampus were evaluated by nissl staining. The inflammatory cytokines, activities of antioxidant enzymes (superoxide dismutase or SOD) and oxidative products (malondialdehyde or MDA) in the serum and hippocampus were tested 24 h after surgery. The activity of matrix metalloproteinase-9 (MMP-9) and expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1(HO-1) in the hippocampus were measured 24 h after surgery. Compared with the sham group in the Morris water maze test, the escape latency of sepsis rats was significantly (P = 0.001) prolonged in the navigation test, whereas the frequency to cross the platform and the time spent in the target quadrant were significantly (P = 0.003) reduced. High-dose vitamin C significantly decreased the escape latency (P = 0.01), but increased the time spent in the target quadrant (P = 0.04) and the frequency to cross the platform (P = 0.19). In the CLP+ saline group, the pyramidal neurons were reduced and distributed sparsely and disorderly, the levels of inflammatory cytokines of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 in the serum and hippocampus were significantly increased (P = 0.000), the blood brain barrier (BBB) permeability in the hippocampus was significantly (P = 0.000) increased, the activities of SOD in the serum and hippocampus were significantly (P = 0.000 and P = 0.03, respectively) diminished while the levels of MDA in the serum and hippocampus were significantly (P = 0.007) increased. High-dose vitamin C mitigated hippocampus histopathologic changes, reduced systemic inflammation and neuroinflammation, attenuated BBB disruption, inhibited oxidative stress in brain tissue, and up-regulated the expression of nuclear and total Nrf2 and HO-1. High-dose vitamin C significantly (P < 0.05) decreased the levels of tumor necrosis factor- (TNF)-α, interleukin-6 (IL-6), MDA in the serum and hippocampus, and the activity of MMP-9 in the hippocampus, but significantly (P < 0.05) increased the levels of SOD, the anti-inflammatory cytokine (IL-10) in the serum and hippocampus, and nuclear and total Nrf2, and HO-1 in the hippocampus. In conclusion, high-dose vitamin C can improve cognition impairment in septic rats, and the possible protective mechanism may be related to inhibition of inflammatory factors, alleviation of oxidative stress, and activation of the Nrf2/HO-1 pathway.

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