Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the protein kinases responsible for myosin regulatory light chain (LC20) phosphorylation and regulation of myosin light chain phosphatase (MLCP) activity during microcystin (phosphatase inhibitor)-induced contraction at low Ca2+ concentrations of rat ileal smooth muscle stretched in the longitudinal axis. Application of 1 microM microcystin induced LC20 diphosphorylation and contraction of beta-escin-permeabilized rat ileal smooth muscle at pCa 9. The PKC inhibitor GF-109203x, the MEK inhibitor PD-98059, and the p38 MAPK inhibitor SB-203580 significantly reduced this contraction. These inhibitory effects were abolished when the microcystin concentration was increased to 10 muM, indicating that application of these kinase inhibitors generated an increase in MLCP activity. GF-109203x and PD-98059, but not SB-203580, significantly decreased the phosphorylation level of the myosin-targeting subunit of MLCP, MYPT1, at Thr-697 (rat sequence) during microcystin-induced contraction at pCa 9. On the other hand, SB-203580, but not GF-109203x or PD-98059, significantly reduced the phosphorylation level of the PKC-potentiated phosphatase inhibitor of 17 kDa (CPI-17). A zipper-interacting protein kinase (ZIPK) inhibitor (SM1 peptide) and a Rho-associated kinase inhibitor (Y-27632) had little effect on microcystin-induced contraction at pCa 9. In conclusion, PKC, ERK1/2, and p38 MAPK pathways facilitate microcystin-induced contraction at low Ca2+ concentrations by contributing to the inhibition of MLCP activity either through phosphorylation of MYPT1 or CPI-17 [probably mediated by integrin-linked kinase (ILK)]. ILK and not ZIPK is likely to be the protein kinase responsible for LC20 diphosphorylation during microcystin-induced contraction of rat ileal smooth muscle at pCa 9, similar to its recently described role in vascular smooth muscle. The negative regulation of MLCP by PKC and MAPKs during microcystin-induced contraction at pCa 9, which is not observed in vascular smooth muscle, may be unique to phasic smooth muscle.
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PMID:Characterization of protein kinase pathways responsible for Ca2+ sensitization in rat ileal longitudinal smooth muscle. 1765 44

Combining immunotherapy with targeted therapy blocking oncogenic BRAFV600 may result in improved treatments for advanced melanoma. In this study, we developed a BRAFV600E-driven murine model of melanoma, SM1, which is syngeneic to fully immunocompetent mice. SM1 cells exposed to the BRAF inhibitor vemurafenib (PLX4032) showed partial in vitro and in vivo sensitivity resulting from the inhibition of MAPK pathway signaling. Combined treatment of vemurafenib plus adoptive cell transfer therapy with lymphocytes genetically modified with a T-cell receptor (TCR) recognizing chicken ovalbumin (OVA) expressed by SM1-OVA tumors or pmel-1 TCR transgenic lymphocytes recognizing gp100 endogenously expressed by SM1 resulted in superior antitumor responses compared with either therapy alone. T-cell analysis showed that vemurafenib did not significantly alter the expansion, distribution, or tumor accumulation of the adoptively transferred cells. However, vemurafenib paradoxically increased mitogen-activated protein kinase (MAPK) signaling, in vivo cytotoxic activity, and intratumoral cytokine secretion by adoptively transferred cells. Taken together, our findings, derived from 2 independent models combining BRAF-targeted therapy with immunotherapy, support the testing of this therapeutic combination in patients with BRAFV600 mutant metastatic melanoma.
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PMID:BRAF inhibitor vemurafenib improves the antitumor activity of adoptive cell immunotherapy. 2269 52

The BRAF mutant, BRAF(V600E), is expressed in nearly half of melanomas, and oral BRAF inhibitors induce substantial tumor regression in patients with BRAF(V600E) metastatic melanoma. The inhibitors are believed to work primarily by inhibiting BRAF(V600E)-induced oncogenic MAPK signaling; however, some patients treated with BRAF inhibitors exhibit increased tumor immune infiltration, suggesting that a combination of BRAF inhibitors and immunotherapy may be beneficial. We used two relatively resistant variants of Braf(V600E)-driven mouse melanoma (SM1 and SM1WT1) and melanoma-prone mice to determine the role of host immunity in type I BRAF inhibitor PLX4720 antitumor activity. We found that PLX4720 treatment downregulated tumor Ccl2 gene expression and decreased tumor CCL2 expression in both Braf(V600E) mouse melanoma transplants and in de novo melanomas in a manner that was coincident with reduced tumor growth. While PLX4720 did not directly increase tumor immunogenicity, analysis of SM1 tumor-infiltrating leukocytes in PLX4720-treated mice demonstrated a robust increase in CD8(+) T/FoxP3(+)CD4(+) T cell ratio and NK cells. Combination therapy with PLX4720 and anti-CCL2 or agonistic anti-CD137 antibodies demonstrated significant antitumor activity in mouse transplant and de novo tumorigenesis models. These data elucidate a role for host CCR2 in the mechanism of action of type I BRAF inhibitors and support the therapeutic potential of combining BRAF inhibitors with immunotherapy.
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PMID:Host immunity contributes to the anti-melanoma activity of BRAF inhibitors. 2659 10

Combining immunotherapy and BRAF targeted therapy may result in improved antitumor activity with the high response rates of targeted therapy and the durability of responses with immunotherapy. However, the first clinical trial testing the combination of the BRAF inhibitor vemurafenib and the CTLA4 antibody ipilimumab was terminated early because of substantial liver toxicities. MEK [MAPK (mitogen-activated protein kinase) kinase] inhibitors can potentiate the MAPK inhibition in BRAF mutant cells while potentially alleviating the unwanted paradoxical MAPK activation in BRAF wild-type cells that lead to side effects when using BRAF inhibitors alone. However, there is the concern of MEK inhibitors being detrimental to T cell functionality. Using a mouse model of syngeneic BRAF(V600E)-driven melanoma, SM1, we tested whether addition of the MEK inhibitor trametinib would enhance the antitumor activity of combined immunotherapy with the BRAF inhibitor dabrafenib. Combination of dabrafenib and trametinib with pmel-1 adoptive cell transfer (ACT) showed complete tumor regression, increased T cell infiltration into tumors, and improved in vivo cytotoxicity. Single-agent dabrafenib increased tumor-associated macrophages and T regulatory cells (Tregs) in tumors, which decreased with the addition of trametinib. The triple combination therapy resulted in increased melanosomal antigen and major histocompatibility complex (MHC) expression and global immune-related gene up-regulation. Given the up-regulation of PD-L1 seen with dabrafenib and/or trametinib combined with antigen-specific ACT, we tested the combination of dabrafenib, trametinib, and anti-PD1 therapy in SM1 tumors, and observed superior antitumor effect. Our findings support the testing of triple combination therapy of BRAF and MEK inhibitors with immunotherapy in patients with BRAF(V600E) mutant metastatic melanoma.
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PMID:Improved antitumor activity of immunotherapy with BRAF and MEK inhibitors in BRAF(V600E) melanoma. 2581 51