Use Of P38 Inhibitors Research Articles

Activation of p38α stress-activated protein kinase drives the formation of the pre-metastatic niche in the lungs.

Primary tumor-derived factors (TDFs) act upon normal cells to generate a pre-metastatic niche, which promotes colonization of target organs by disseminated malignant cells. Here we report that TDFs-induced activation of the p38α kinase in lung fibroblasts plays a critical role in the formation of a pre-metastatic niche in the lungs and subsequent pulmonary metastases. Activation of p38α led to inactivation of type I interferon signaling and stimulation of expression of fibroblast activation protein (FAP). FAP played a key role in remodeling of the extracellular matrix as well as inducing the expression of chemokines that enable lung infiltration by neutrophils. Increased activity of p38 in normal cells was associated with metastatic disease and poor prognosis in human melanoma patients whereas inactivation of p38 suppressed lung metastases. We discuss the p38α-driven mechanisms stimulating the metastatic processes and potential use of p38 inhibitors in adjuvant therapy of metastatic cancers.

Inhibition of MAPK P38 Decreases Hyperglycemia-Induced Nephrin Endocytosis and Protects Against Proteinuria

Diabetic nephropathy is the leading cause of end stage renal disease. In diabetes albuminuria is an early sign of a leaky renal filter and leads to an accelerated loss of renal function. Despite intensive research there is still no specific antiproteinuric therapy available. Thus, deeper understanding of the molecular mechanisms of albuminuria is desirable. MAPK p38 signaling has been shown to be involved in the development of hyperglycemia-induced albuminuria; however, it remains unclear how increased p38 activity leads to loss of albumin in the urine. We recently demonstrated that acute hyperglycemia triggers endocytosis of nephrin, the key molecule of the slit diaphragm, and induces albuminuria. Here, we identify p38 as pivotal regulator of hyperglycemia-induced nephrin endocytosis and proteinuria. Activated p38 phosphorylates the nephrin c-terminus at serine 1146, facilitating the interaction of PKCα with nephrin. PKCα phosphorylates nephrin at threonine residues 1120 and 1125, mediating the binding of β-arrestin2 to nephrin. β-arrestin2 triggers endocytosis of nephrin by coupling it to the endocytotic machinery, leading to a leaky glomerular filter. Pharmacological inhibition of p38 preserves nephrin surface expression and significantly attenuates albuminuria. Our data highlight the pivotal role of p38 in the genesis of diabetic proteinuria and the potential use of p38 inhibitors to slow down progression of kidney disease in patients with proteinuria.

Identification of p38 MAPK as a novel therapeutic target for Friedreich\u2019s ataxia

Friedreich ataxia (FRDA) is an autosomal recessive neuro- and cardio-degenerative disorder caused by decreased expression of frataxin, a protein that localizes to mitochondria and is critical for iron-sulfur-cluster (ISC) assembly. There are no proven effective treatments for FRDA. We previously screened a random shRNA library and identified a synthetic shRNA (gFA11) that reverses the growth defect of FRDA cells in culture. We now report that gFA11 decreases cytokine secretion in primary FRDA fibroblasts and reverts other changes associated with cell senescence. The gene-expression profile induced by gFA11 is remarkably similar to the gene-expression profile induced by the p38 MAPK inhibitor SB203580. We found that p38 phosphorylation, indicating activation of the p38 pathway, is higher in FRDA cells than in normal control cells, and that siRNA knockdown of frataxin in normal fibroblasts also increases p38 phosphorylation. Treatment of FRDA cells with p38 inhibitors recapitulates the reversal of the slow-growth phenotype induced by clone gFA11. These data highlight the involvement of the p38 MAPK pathway in the pathogenesis of FRDA and the potential use of p38 inhibitors as a treatment for FRDA.

MiR-214 suppresses the osteogenic differentiation of bone marrow-derived mesenchymal stem cells and these effects are mediated through the inhibition of the JNK and p38 pathways.

In this study, we sought to investigate the expression of microRNA (miR)-214 on the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and explore the possible underlying mechanisms. We found that the overexpression of miR-214 effectively promoted the adipocyte differentiation of BMSCs in vitro, reduced alkaline phosphatase (ALP) activity and the gene expression of collagen type I (Col I), osteocalcin (OCN) and osteopontin (OPN) in the BMSCs. We further found that the overexpression of miR-214 suppressed the protein expression of fibroblast growth factor (FGF), phosphorylated c-Jun N-terminal kinase (p-JNK) and phosphorylated p38 (p-p38) in the BMSCs. The downregulation of miR-214 promoted the osteogenic differentiation of BMSCs, and increased ALP activity and Col I, OCN and OPN gene expression in the BMSCs. It also increased FGF p-JNK and p-p38 protein expression in the BMSCs. The use of JNK inhibitor (SP600125) enhanced the inhibitory effects of miR-214 overexpression on osteogenic differentiation, ALP activity, and Col I, OCN and OPN gene expression in the BMSCs. Lastly, the use of p38 inhibitor (SB202190) also enhanced the inhibitory effects of miR-214 overexpression on ALP activity, and Col I, OCN and OPN gene expression in the BMSCs. These results provide a mechanism responsible for the suppressive effects of miR-214 on the osteogenic differentiation of BMSCs involving the inhibition of the JNK and p38 pathways.

Abstract 3162: NOD1 augments cancer cell metastatic potential through p38 MAP kinase activation

Abstract INTRODUCTION: Strong clinical evidence demonstrates a link between acute bacterial infection and metastasis. We and others have shown that activation of certain membrane pattern recognition receptors (PRRs), such as Toll-like receptors, on cancer cells can be implicated in this process. There is emerging data that a cytoplasmic PRR, the nucleotide oligomerization domain receptor 1 (NOD1), may also play an important and complementary role in the immune response to bacterial infection, however its role in cancer progression is entirely unknown. We sought to determine the influence of NOD1 activation on metastasis. METHODS: NOD1 expression in human and murine colon (HT29, MC38) and lung (A549, H59) cancer cells were confirmed using flow cytometry (FC) and immunoblotting (WB). A series of in vitro and in vivo functional assays, including adhesion, migration and hepatic intravital microscopy (IVM), was conducted to assess the effect of NOD1 activation and inhibition. C12-iE-DAP, a highly selective NOD1 ligand derived from gram-negative bacterial wall, was used to simulate NOD1-activation under infectious condition. ML130, a specific NOD1 inhibitor, was used to block C12-iE-DAP activation. Stable knockdown (KD) of NOD1 in HT29 and A549 cells were constructed with shRNA lentiviral transduction and the functional assays were thus repeated. The predominant signaling pathway, downstream cytokines and cell adhesion molecules of NOD1-activation were identified using WB in the presence of kinase inhibitors. RESULTS: WB and FC showed abundant NOD1 expression in all tested cell lines. Cancer cells stimulated with C12-iE-DAP doubled the in vitro adhesion to collagen I, IV and fibronectin, as well as in vitro migration, an effect completely attenuated with ML130 inhibition and NOD1 knockdown. Using a murine hepatic adhesion assay under IVM, we observed a doubling in the amount of in vivo capture of cancer cells within hepatic sinusoids of C57BL6 mice in the C12-iE-DAP group compared to control, an effect again abrogated by ML130 inhibition and NOD1 knockdown. Immunoblotting using HT29 cells under a panel of kinase inhibitors revealed that NOD1 activation is p38 dependent. Subsequently, the use of p38 inhibitor, BIRB0796, abolished C12-iE-DAP mediated adhesion to collagen I and fibronectin. Using human cytokine quantification array, we determined that NOD1 activation led to increase in IL-8, 15, MCP1 and RANTES, all of which have been shown to link to cancer progression or to chemoattract neutrophils, which we have recently shown to mediate metastasis. CONCLUSION: Our data demonstrate that NOD1 activation by the gram-negative bacterial wall component, C12-iE-DAP is important in enhancing the metastatic potential of cancer cells, and its mechanism is dependent on p38 activation and the upregulation of downstream cytokines. This is the first study to implicate NOD1 in metastasis, and thus identify this receptor as a putative therapeutic target. Citation Format: Henry Jiang, Sara Najmeh, Julie Berube, Arielle Leone, Paul Savage, Betty Giannias, France Bourdeau, Simon Rousseau, Morag Park, Lorenzo Edwin Ferri. NOD1 augments cancer cell metastatic potential through p38 MAP kinase activation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3162. doi:10.1158/1538-7445.AM2015-3162

The p38 mitogen-activated protein kinase cascade modulates T helper type 17 differentiation and functionality in multiple sclerosis.

The p38 mitogen-activated protein kinase cascade is required for the induction of a T helper type 17 (Th17) -mediated autoimmune response, which underlies the development and progression of several autoimmune diseases, such as experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis (MS). However, the contribution of p38 phosphorylation to human Th cell differentiation has not been clarified. Here we demonstrate that the p38 signalling pathway is implicated in the generation of Th17 lymphocytes from human CD4(+) CD27(+) CD45RA(+) naive T cells, both in healthy donors and in patients affected by the relapsing-remitting form of MS. Our data also indicate that p38 activation is essential for interleukin-17 release from central memory lymphocytes and committed Th17 cell clones. Furthermore, CD4(+) T cells isolated from individuals with relapsing-remitting MS display an altered responsiveness of the p38 cascade, resulting in increased p38 phosphorylation upon stimulation. These findings suggest that the p38 signalling pathway, by modulating the Th17 differentiation and response, is involved in the pathogenesis of MS, and open new perspectives for the use of p38 inhibitors in the treatment of Th17-mediated autoimmune diseases.

Role of p38 inhibition in cardiac ischemia/reperfusion injury

The p38 mitogen-activated protein kinases (p38s) are Ser/Thr kinases that are activated as a result of cellular stresses and various pathological conditions, including myocardial ischemia/reperfusion. p38 activation has been shown to accentuate myocardial injury and impair cardiac function. Inhibition of p38 activation and its activity has been proposed to be cardioprotective by slowing the rate of myocardial damage and improving cardiac function. The growing body of evidence on the use of p38 inhibitors as therapeutic means for responding to heart problems is controversial, since both beneficial as well as a lack of protective effects on the heart have been reported. In this review, the outcomes from studies investigating the effect of p38 inhibitors on the heart in a wide range of study models, including in vitro, ex vivo, and in vivo models, are discussed. The correlations of experimental models with practical clinical usefulness, as well as the need for future studies regarding the use of p38 inhibitors, are also addressed.

ERK1/2 and p38α/β Signaling in Tumor Cell Quiescence: Opportunities to Control Dormant Residual Disease

Systemic minimal residual disease after primary tumor treatment can remain asymptomatic for decades. This is thought to be due to the presence of dormant disseminated tumor cells (DTC) or micrometastases in different organs. DTCs lodged in brain, lungs, livers, and/or bone are a major clinical problem because they are the founders of metastasis, which ultimately kill cancer patients. The problem is further aggravated by our lack of understanding of DTC biology. In consequence, there are almost no rational therapies to prevent dormant DTCs from surviving and expanding. Several cancers, including melanoma as well as breast, prostate, and colorectal carcinomas, undergo dormant periods before metastatic recurrences develop. Here we review our experience in studying the cross-talk between ERK1/2 and p38α/β signaling in models of early cancer progression, dissemination, and DTC dormancy. We also provide some potential translational and clinical applications of these findings and describe how some currently used therapies might be useful to control dormant disease. Finally, we draw caution on the use of p38 inhibitors currently in clinical trials for different diseases as these may accelerate metastasis development.

Abstract 405: Deficiency of p38α MAPK in Macrophages Promotes Apoptosis and Plaque Necrosis in Advanced Murine Atherosclerotic Lesions

Endoplasmic reticulum (ER) stress occurs in macrophage-rich areas of advanced atheroscle-rotic lesions and contributes to macrophage apoptosis and subsequent plaque necrosis. Therefore, signaling pathways that alter ER stress-induced apoptosis may affect the development of advanced atherosclerosis. Here we show that Western diet-fed Apoe −/− mice deficient in macrophage p38α MAPK have a marked increase in apoptosis and plaque necrosis. We found a significant increase in the mean necrotic area in the p38α-deficient lesions (46,700 μm 2 versus 18,965 μm 2 in the control mice, p < 0.008). Quantification of the data revealed an approximate 51% increase in the percent of apoptotic cells in the p38α-deficient lesions. The macrophage-p38α-deficient lesions also exhibited a 30% decrease in collagen content and a 40% decrease in fibrous cap thickness. Consistent with our in vivo data, we found that ER stress-induced apoptosis in cultured macrophages was markedly accelerated under conditions of p38 inhibition, and this effect was further enhanced in the setting of insulin resistance. Mechanistic experiments revealed that p38 inhibition causes suppression of the pro-survival Akt pathway in vitro and in vivo . We found that inhibition of Akt with LY294002 enhances apoptosis under conditions of ER stress. Furthermore, expression of a constitutively active Akt, myristoylated-Akt, blocked the enhancement of apoptosis that occurred with p38 inhibition, but did not inhibit apoptosis induced by ER stress itself. In view of clinical trials exploring the use of p38 inhibitors in inflammatory diseases, our results raise the possibility that these drugs may promote plaque progression in subjects with advanced atherosclerotic lesions. This research has received full or partial funding support from the American Heart Association, AHA Founders Affiliate (Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, Vermont).