P38 MAPK Protein Phosphorylation Research Articles

Suppression of cathepsin a inhibits growth, migration, and invasion by inhibiting the p38 MAPK signaling pathway in prostate cancer

Prostate cancer has the highest incidence among men in advanced countries, as well as a high mortality rate. Despite the efforts of numerous researchers to identify a gene-based therapeutic target as an effective treatment of prostate cancer, there is still a need for further research. The cathepsin gene family is known to have a close correlation with various cancer types and is highly expressed across these cancer types. This study aimed at investigating the correlation between the cathepsin A (CTSA) gene and prostate cancer. Our findings indicated a significantly elevated level of CTSA gene expression in the tissues of patients with prostate cancer when compared with normal prostate tissues. Furthermore, the knockdown of the CTSA gene in the representative prostate cancer cell lines PC3 and DU145 led to reduced proliferation and a marked reduction in anchorage-independent colony formation, which was shown to be caused by cell cycle arrest in the S phase. In addition, CTSA gene-knockdown prostate cancer cell lines showed a substantial decrease in migration and invasion, as well as a decrease in the marker genes that promote epithelial mesenchymal transition (EMT). Such phenotypic changes in prostate cancer cell lines through CTSA gene suppression were found to be mainly caused by reduced p38 MAPK protein phosphorylation; i.e. the inactivation of the p38 MAPK cell signaling pathway. Tumorigenesis was also found to be inhibited in CTSA gene-knockdown prostate cancer cell lines when a xenograft assay was carried out using Balb/c nude mice, and the p38 MAPK phosphorylation was inhibited in tumor tissues. Thus, the CTSA gene is presumed to play a key role in human prostate cancer tissues through high-level expression, and the suppression of the CTSA gene leads to the inhibition of prostate cancer cell proliferation, colony formation, and metastasis. The mechanism, by which these effects occur, was demonstrated to be the inactivation of the p38 MAPK signaling pathway.

Crotalus neutralising factor and its role in human leukocyte modulation.

Crotalus neutralising factor (CNF) is an endogenous γ-type phospholipase A2 (PLA2) inhibitor that inhibits the toxic action of crotoxin, a neurotoxin present in Crotalus durissus terrificus venom. However, its effects on the activation and modulation of immune cells, which play a major role in the development of inflammation, is not known. The objective of the present study was to assess the effects of CNF on human leukocyte modulation in vitro by analysing the following parameters: cell viability, phagocytic capacity, lipid droplet formation, reactive oxygen species production, nitric oxide production, p38 MAPK activation, and cytosolic PLA2 (cPLA2) gene expression. Neutrophils and peripheral blood mononuclear cells from healthy donors were isolated via the density gradient method, resuspended in RPMI medium, and incubated with RPMI (negative control), LPS, or PMA (positive control) or CNF (sample test) at a concentration of 50 μg/mL. Results showed that CNF was not toxic to human neutrophils after 48 and 72 h of incubation. CNF treatment induced an increase in PBMCs and neutrophil phagocytic capacity, as well as the formation of lipid droplets within these cells after 1 h of incubation. However, CNF did not induce the formation of reactive oxygen and nitric oxide species. Moreover, CNF induced p38 MAPK protein phosphorylation and cPLA2 gene expression in neutrophils. The data obtained herein showed that CNF action modulates human leukocytes, CNF activates important signalling pathways for human leukocytes, and it is pro-inflammatory. These findings also complement previous studies on CNF action on human peripheral blood leukocyte function.

Caspase-3/MAPK pathways as main regulators of the apoptotic effect of the phyto-mediated synthesized silver nanoparticle from dried stem of Eleutherococcus senticosus in human cancer cells

Siberian ginseng (Eleutherococcus senticosus) was used for the synthesis of an ecofriendly silver nanoparticle (Sg-AgNP), which has exhibited antibacterial, antioxidant effect and lower cytotoxicity to normal cells in comparison to human cancer cells. Although, the potential anticancer activity of Sg-AgNP has not been determined. In this study, two cancer cell lines were used to evaluate the cytotoxicity and apoptotic effect of Sg-AgNP along with the determination of the role of the Caspase-3 / p38 MAPK pathways. Results shown that Sg-AgNP reduced the cell viability of colon cancer cells HT29 and lung cancer cells A549. The cytotoxic effect was higher than the effect exhibited by a commercial silver nanoparticle and Cisplatin. Reactive oxygen species were observed to be superior in both cell lines in the presence of Sg-AgNPs than c-AgNPs and Cisplatin. It was observed an activation of MAPK14 gene and phosphorylation of p38 MAPK protein in both cell lines induced by Sg-AgNPs treatment. Furthermore, induction of morphological changes in the nucleus was done by Sg-AgNPs at 10 μg/mL in both cell lines. On the other hands, the activation of CASP3 gene and Caspase-3 protein was observed in HT29 cells but only at protein level in A549 cells. These results, suggest that Sg-AgNPs anticancer potential activity might be linked to the induction of apoptosis though the generation of ROS by activation of the Caspase-3/p38 MAPK pathway.

Kolaviron and Garcinia kola Seed Extract Protect Against Ischaemia/Reperfusion Injury on Isolated Rat Heart.

The incidence of cardiovascular diseases and its associated complications have increased greatly in the past three decades. The purpose of this study was to evaluate the acute cardioprotective effects of Garcinia kola (GK) seed extract and Kolaviron (KV) and determine mechanisms of action involving RISK signalling pathways. Male Wistar rats were used in this study. Hearts were excised and mounted on the Langendorff perfusion system. The control, group 1 was perfused with dimethyl sulfoxide (DMSO), group II with KV and group III with GK respectively. Western blot analyses were performed on frozen heart tissues. Isolated rat hearts perfused with KV and GK attenuated apoptotic pathways with significant reduction in p38 MAPK protein phosphorylation, as well as reduction in total caspase 3, cleaved caspase 3 (Asp 175) and PARP cleavage. KV and GK also down-regulated p-JNK1 (Tyr 185) and p-JNK 2 (Thr 183) protein expression at the 10 min reperfusion time ponit. Cardioprotection was achieved in part, by enhancement of the reperfusion injury signalling kinase (RISK) pathway; as evidenced by significant increases in protein expresion of Akt/PKB and p-Akt/PKB (Ser 473) in KV and GK respectively. KV and GK supplementation led to significant increases in the expressions of survival proteins. It is noteworthy that both KV and GK supplementation offered cardioprotection in ischaemic/reperfusion injury rat heart model. In all, GK showed better cardioprotective effect that KV.

IRF3 is an important molecule in the UII/UT system and mediates immune inflammatory injury in acute liver failure.

The urotensin II/urotensin receptor (UII/UT) system can mediate inflammatory liver injury in acute liver failure (ALF); however; the related mechanism is not clear. In this study, we confirmed that lipopolysaccharide/D-galactosamine (LPS/D-GalN) induced up-regulation of liver interferon regulatory factor 3 (IRF3) in ALF mice, whereas the UT antagonist urantide inhibited the up-regulated liver IRF3. LPS stimulation induced IRF3 transcription and nuclear translocation and promoted the secretion of interleukin-6 (IL-6), interferon (IFN)-β, and IFN-γ in Kupffer cells (KCs); these effects in LPS-stimulated KCs were inhibited by urantide. Knockdown of IRF3 using an adenovirus expressing an IRF3 shRNA inhibited IFN-β transcription and secretion as well as tumor necrosis factor (TNF)-α and IL-1β secretion from LPS-stimulated KCs; additionally, IL-10 transcription and secretion were promoted in response to LPS. However, LPS-stimulated TNF-α and IL-1β mRNA was not affected in the KCs. The IRF3 shRNA also did not have a significant effect on the NF-κB p65 subunit and p38MAPK protein phosphorylation levels in the nuclei of LPS-stimulated KCs. Therefore, IRF3 expression and activation depended on the signal transduction of the UII/UT system, and played important roles in UII/UT-mediated immune inflammatory injury in the liver but did not affect NF-κB and p38 MAPK activity.

Effect of osmotic stress on the expression of TRPV4 and BKCa channels and possible interaction with ERK1/2 and p38 in cultured equine chondrocytes

The metabolic activity of articular chondrocytes is influenced by osmotic alterations that occur in articular cartilage secondary to mechanical load. The mechanisms that sense and transduce mechanical signals from cell swelling and initiate volume regulation are poorly understood. The purpose of this study was to investigate how the expression of two putative osmolyte channels [transient receptor potential vanilloid 4 (TRPV4) and large-conductance Ca(2+)-activated K(+) (BKCa)] in chondrocytes is modulated in different osmotic conditions and to examine a potential role for MAPKs in this process. Isolated equine articular chondrocytes were subjected to anisosmotic conditions, and TRPV4 and BKCa channel expression and ERK1/2 and p38 MAPK protein phosphorylation were investigated using Western blotting. Results indicate that the TRPV4 channel contributes to the early stages of hypo-osmotic stress, while the BKCa channel is involved in responding to elevated intracellular Ca(2+) and mediating regulatory volume decrease. ERK1/2 is phosphorylated by hypo-osmotic stress (P < 0.001), and p38 MAPK is phosphorylated by hyperosmotic stress (P < 0.001). In addition, this study demonstrates the importance of endogenous ERK1/2 phosphorylation in TRPV4 channel expression, where blocking ERK1/2 by a specific inhibitor (PD98059) prevented increased levels of the TRPV4 channel in cells exposed to hypo-osmotic stress and decreased TRPV4 channel expression to below control levels in iso-osmotic conditions (P < 0.001).

Isoquercitrin inhibits the progression of liver cancer in vivo and in vitro via the MAPK signalling pathway.

Liver cancer is a malignant tumour with high morbidity and fatality rates that is common worldwide. At present, the clinical approaches to treating primary liver cancer include partial hepatectomy, systemic or local chemotherapy, radiotherapy, radiofrequency ablative surgery and liver transplantation. However, all of these approaches have shortcomings, including poor prognosis and numerous side-effects. A large number of studies have proven that many effective ingredients in traditional Chinese medicine, particularly the flavonoid compounds extracted from plants, have achieved breakthroughs in terms of enhancing the effects and reducing the toxicity of chemotherapy and radiotherapy, preventing tumour metastasis and relapse after surgery, alleviating the clinical symptoms of advanced tumours, improving the quality of life of the patient with tumours and extending patient long‑term survival. The purpose of the present study was to investigate the impact of isoquercitrin, the flavonoid from Bidens bipinnata L. extract, on the progression of liver cancer and to achieve a deeper understanding of the biological characteristics of isoquercitrin's involvement in the progression of liver cancer. In the in vitro experiments, isoquercitrin was found to strongly inhibit the proliferation of human liver cancer cells, promote the apoptosis of human liver cancer cells, and block the cell cycle in the G1 phase. Isoquercitrin activated caspase-3, -8 and -9, inhibited the expression level of ERK and p38MAPK protein phosphorylation, and promoted the phosphorylation of JNK. Additionally, isoquercitrin reduced the expression level of PKC in human liver cancer cells. In the in vivo experiments, isoquercitrin was also found to significantly inhibit the growth of transplanted tumours in nude mice. The present study confirmed that isoquercitrin could inhibit the progression of human liver cancer in vivo and in vitro, and the molecular mechanism of isoquercitrin may be closely associated with the MAPK and PKC signalling pathways.

Inhibition of p38 MAPK during cellular activation modulate gene expression of head kidney leukocytes isolated from Atlantic salmon ( Salmo salar) fed soy bean oil or fish oil based diets

Head kidney leukocytes isolated from Atlantic salmon fed either a diet based on fish oil (FO) or soy bean oil (VO) were used in order to evaluate if different lipid sources could contribute to cellular activation of the salmon innate immune system. A specific inhibitor of p38 MAPK, SB202190, was used to investigate the effect of lipopolysaccharide (LPS) signalling in the head kidney leukocytes. The results show that LPS up regulate IL- 1β, TNF- α, Cox2 expression in leukocytes isolated from fish fed either diet. The p38 MAPK inhibitor, SB202190, reduced the LPS induced expression of these genes in both dietary groups. In LPS stimulated leukocytes isolated from VO fed fish, SB202190 showed a clear dose dependent inhibitory effect on IL- 1β, TNF- α and Cox2 expression. This effect was also observed for Cox2 in leukocytes isolated from FO fed fish. Furthermore, there was a stronger mean induction of Cox2 in LPS stimulated leucocytes isolated from the VO-group compared to LPS stimulated leukocytes isolated from the FO-group. In both dietary groups, LPS stimulation of salmon head kidney leukocytes increased the induction of CD83, a dendrite cell marker, while the inhibitor reduced CD83 expression in the VO fed fish only. The inhibitor also clearly reduced hsp27 expression in VO fed fish. Indicating a p38 MAPK feedback loop, LPS significantly inhibited the expression of p38MAPK itself in both diets, while SB202190 increased p38MAPK expression especially in the VO diet group. hsp70 expression was not affected by any treatment or feed composition. There were also differences in p38MAPK protein phosphorylation comparing treatment groups but no obvious difference comparing the two dietary groups. The results indicate that dietary fatty acids have the ability to modify signalling through p38 MAPK which may have consequences for the fish’s ability to handle infections and stress. Signalling through p38MAPK is ligand dependent and affects gene and protein expression differently.

Protective effect of resveratrol against LPS-induced extracellular lipoperoxidation in AR42J cells partly via a Myd88-dependent signaling pathway

Lipopolysaccharides (LPS) are major components of the cell wall of Gram negative bacteria implicated in the pathogenesis of bacterial infection. Resveratrol is a polyphenolic phytoalexin exhibiting antioxidant and anti-inflammatory properties. We investigated the protective effects of this natural compound on LPS-induced proinflammatory effect using non-myeloid AR42J pancreatic cells. We found that LPS dose-dependently increased extracellular malondialdehyde (MDA) and nitric oxide without affecting their intracellular level whereas resveratrol abolished all these deleterious effects. LPS increased CD14 expression; IRAK1 and a phosphorylated form of p38 MAPK protein. Resveratrol counteracted LPS effect by decreasing CD14 and IRAK1 expression but unexpectedly increased the p38 MAPK protein phosphorylation. Altogether, our data highlighted the functionality of the TLR4–Myd88 signaling pathway in LPS pro-oxidant effect using non-myeloid cells. They further suggested that resveratrol exerted antioxidant properties either by a Myd88-dependent way not involving IRAK1 or by a TRIF dependent pathway.

Morphine upregulates functional expression of neurokinin‐1 receptor in neurons

Neuronkinin-1 receptor (NK-1R), the neuropeptide substance P (SP) preferring receptor, is highly expressed in areas of the central nervous system (CNS) that are especially implicated in depression, anxiety, and stress. Repeated exposure to opioids may sensitize neuronal systems involved in stress response. We examined the effects of morphine, the principal metabolite of heroin, on the functional expression of NK-1R in the cortical neurons. NK-1R and mu-opioid receptor (MOR) are co-expressed in the cortical neurons. Morphine enhanced NK-1R expression in the cortical neurons at both the mRNA and protein levels. The upregulated NK-1R by morphine had functional activity, because morphine-treated cortical neurons had greater SP-induced Ca(2+) mobilization than untreated neurons. Blocking opioid receptors on the cortical neurons by naltrexone or CTAP (a mu-opioid receptor antagonist) abolished the morphine action. Investigation of the mechanism(s) responsible for the morphine action showed that morphine activated NK-1R promoter and induced the phosphorylation of p38 MAPK protein in the cortical neurons. These in vitro data provide a plausible cellular mechanism for opioid-mediated neurological disorders.