5594

MAPK1

mitogen-activated protein kinase 1;MAPK1;mitogen-activated protein kinase 1

MAP kinase 1|MAP kinase 2|MAP kinase isoform p42|MAPK 2|extracellular signal-regulated kinase 2|mitogen-activated protein kinase 2|protein tyrosine kinase ERK2

22q11.21

protein-coding

The role of CTGF/CCN2 in osteolytic metastasis by breast cancer cells and its mechanism of action were studied. Osteolytic metastasis accompanied by CCN2 and PTHrP overproduction was efficiently inhibited by an anti-CCN2 antibody. Furthermore, we found that CCN2 was induced by PTHrP through PKA-, PKC-, and ERK-mediated pathways therein. INTRODUCTION: Connective tissue growth factor (CTGF/CCN2) is a mediator of local angiogenesis induced by breast cancer, but its role in osteolytic metastasis has not been evaluated. PTH-related peptide (PTHrP) is another critical factor in the development of the osteolytic metastasis. Using both in vivo and in vitro approaches, we studied whether/how neutralization of CCN2 prevented bone metastasis and how PTHrP signaling is related. MATERIALS AND METHODS: A mouse model of bone metastasis by human breast cancer cell line MDA231 was treated with a CCN2-neutralizing antibody, and osteolytic bone metastases were assessed on radiographs and immunohistochemistry. Ccn2 gene expression and transcription were examined by Northern blot and luciferase analysis. Immunoblot analysis and kinase inhibitors were used to identify the signaling pathways implicated. Anti-angiogenic/osteoclastogenic effects of ccn2 downregulation were also evaluated. RESULTS: Treatment of mice with a CCN2-neutralizing antibody greatly decreased osteolytic bone metastasis, microvasculature, and osteoclasts involved. The antibody also suppressed the growth of subcutaneous tumor in vivo and proliferation and migration of human umbilical vein endothelial cells (HUVECs) in vitro. Downregulation of ccn2 also repressed osteoclastogenesis. CCN2 expression was specifically observed in cancer cells producing PTHrP and type I PTH/PTHrP receptor (PTH1R) invaded the bone marrow, and PTHrP strongly upregulated ccn2 in MDA231 cells in vitro. Activation of protein kinase C (PKC) and protein kinase A (PKA) was necessary and sufficient for the stimulation of ccn2 by PTHrP. Indeed, inhibition of the extracellular signal-regulated kinase (ERK1/2), PKC, or PKA by specific inhibitors counteracted the stimulation of ccn2 expression. Incubation of MDA231 cells with PTHrP induced the activation of ERK1/2. Consistent with these findings, inhibition of PKC prevented PTHrP-induced ERK1/2 activation, whereas 12-O-tetradecanoylphorbol13-acetate (TPA), a stimulator of PKC, upregulated it. CONCLUSIONS: CCN2 was critically involved in osteolytic metastasis and was induced by PKA- and PKC-dependent activation of ERK1/2 signaling by PTHrP. Thus, CCN2 may be a new molecular target for anti-osteolytic therapy to shut off the PTHrP-CCN2 signaling pathway.

The present study aims to determine the role of gamma-aminobutyric acid (GABA) signaling molecules in breast cancer metastasis. Our results reveal that GABAergic system exists in breast cancer cells. Both the GABA synthetic enzyme. (GAD65/67) and GABAB receptor are expressed in 4T1 mouse breast cancer cells, MCF-7 human breast cancer cells and human breast cancer tissue. Baclofen, a GABABR agonist, significantly promoted 4T1 cells invasion and migration in vitro and metastasis in vivo, an event that was attenuated by GABABR antagonist CGP55845. Baclofen-induced breast cancer metastasis was mediated by ERK1/2 pathway.

BACKGROUND: Phosphatase of regenerating liver-3 (PRL-3) plays a causative role in tumor metastasis, but the underlying mechanisms are not well understood. In our previous study, we observed that PRL-3 could decrease tyrosine phosphorylation of integrin beta1 and enhance activation of ERK1/2 in HEK293 cells. Herein we aim to explore the association of PRL-3 with integrin beta1 signaling and its functional implications in motility, invasion, and metastasis of colon cancer cell LoVo. METHODS: Transwell chamber assay and nude mouse model were used to study motility and invasion, and metastsis of LoVo colon cancer cells, respectively. Knockdown of integrin beta1 by siRNA or lentivirus were detected with Western blot and RT-PCR. The effect of PRL-3 on integrin beta1, ERK1/2, and MMPs that mediate motility, invasion, and metastasis were measured by Western blot, immunofluorencence, co-immunoprecipitation and zymographic assays. RESULTS: We demonstrated that PRL-3 associated with integrin beta1 and its expression was positively correlated with ERK1/2 phosphorylation in colon cancer tissues. Depletion of integrin beta1 with siRNA, not only abrogated the activation of ERK1/2 stimulated by PRL-3, but also abolished PRL-3-induced motility and invasion of LoVo cells in vitro. Similarly, inhibition of ERK1/2 phosphorylation with U0126 or MMP activity with GM6001 also impaired PRL-3-induced invasion. In addition, PRL-3 promoted gelatinolytic activity of MMP2, and this stimulation correlated with decreased TIMP2 expression. Moreover, PRL-3-stimulated lung metastasis of LoVo cells in a nude mouse model was inhibited when integrin beta1 expression was interfered with shRNA. CONCLUSION: Our results suggest that PRL-3s roles in motility, invasion, and metastasis in colon cancer are critically controlled by the integrin beta1-ERK1/2-MMP2 signaling.

Pak1 has been reported to be overexpressed in colorectal cancer, but the role of Pak1 in colorectal cancer remains unclear. In this study, Pak1 expression and activity were associated with aggressive behavior of colorectal cancer. Overexpression of Pak1 increased colorectal cancer cell motility and invasion, whereas down-regulation of Pak1 expression or activity reduced colorectal cancer cell migration and invasion. In addition, activated Pak1 inhibited stress fiber and focal adhesion complex formation in colorectal cancer cells and led to formation of motile phenotypes. Importantly, activated Pak1 elicited phosphorylation of FAK at Ser-910 via an ERK-dependent pathway in colorectal cancer cell lines and clinical samples. In conclusion, our results suggest that activated Pak1 regulates colorectal cancer metastasis requiring an ERK-dependent phosphorylation of FAK at Ser-910.

Growth and inflammatory factors are associated with poor prognosis in gastric adenocarcinoma (GA); however, the additive effects of growth and inflammatory factors in GA remain unclear. In this study, we investigated the ability of epidermal growth factor (EGF) and interleukin (IL-1beta) to activate extracellular signal-regulated kinase (ERK)1/2 in GA cells, and correlated the relationships between their roles with the metastatic potential both in GA cells and GA tissues. The effects of EGF, IL-1beta and EGF plus IL-1beta in AGS and MKN-45 GA cells were examined using western blotting, Transwell migration and invasion assays, immunocytochemical staining and an activator protein (AP)-1 luciferase reporter gene assay, and was further characterized in GA tissues by immunohistochemistry. The results exhibited that EGF and IL-1beta additively activated ERK1/2, increased migration and invasion than either EGF or IL-1beta alone in AGS and MKN-45 cells. The mechanisms were involved in upregulating MMP-9 expression through increasing AP-1 transcriptional activity via ERK1/2 pathway; these effects were dose-dependently inhibited by silencing ERK1/2 or using U0126. In vivo data also confirmed that the overexpression of p-ERK1/2 in GA tissues correlated well with the EGF, IL-1beta, EGF plus IL-1beta, and was associated with metastasis, which was well correlation with the expression of MMP-9 and c-fos (AP-1). The results demonstrate that growth and inflammatory factors play an important role in metastasis of GA by additively activating ERK-1/2 and AP-1, and upregulating MMP-9. As both cytokines contribute to the migration and invasion of GA cells, EGF/IL-1beta/ERK1/2 pathways may be key pathways closely associated with GA progression.

Des-gamma-carboxy prothrombin (DCP), an aberrant prothrombin produced by hepatocellular carcinoma (HCC) cells, has been shown to be associated with the biological malignant potential of HCC. The aim of this study was to evaluate the effect of DCP on HCC cell growth and metastasis, and to explore the underlying molecular mechanisms. DCP significantly stimulated HCC cell growth, as measured by cell counting kit-8 assay. Transwell chamber assay showed that DCP increased HCC cell migration through reconstituted extracellular matrix (Matrigel). Gelatin zymography assay and Western blot analysis demonstrated that DCP increased the secretion and expression of matrix metalloproteinase (MMP)-2 and MMP-9 in the supernatant of cultured HCC cells and on tumour cell membranes. DCP was found to bind to the cell surface receptor Met, resulting in Met phosphorylation and subsequent activation of the epidermal growth factor receptor (EGFR). Western blot analysis demonstrated that DCP stimulated a sequential kinase phosphorylation cascade including ERK1/2, MEK1/2 and c-Raf, indicating activation of the extracellular signal-regulated kinase/mitogen activated protein kinase (ERK1/2 MAPK) signalling pathway. Furthermore, blocking ERK1/2 MAPK activation with ERK1/2 inhibitor PD98059 essentially abolished the DCP-induced MMP-2 and MMP-9 activity, confirming the signalling pathway of DCP stimulation. Taken together, these results suggested that DCP stimulates HCC growth and promotes HCC metastasis by increasing the activity of MMP-2 and MMP-9 through activation of the ERK1/2 MAPK signalling pathway.

AIM: To investigate the role of Hedgehog (Hh) signaling pathway in the invasion and metastasis of human hepatocellular carcinoma (HCC). METHODS: Eighty six HCC tissues samples and HCC cell line Bel-7402 were examined. The protein expression of sonic hedgehog (Shh), nuclear glioma-associated oncogene-1 (Gli1), MMP-9 and p-ERK1/2 in HCC was analyzed using immunohistochemistry and Western blot analysis. Boyden chamber assay and wound-healing assay were used to quantify the invasion and metastasis of Bel-7402 cells. RESULTS: In 86 HCC tissue samples, the positive ratio of Shh and nucleus Gli1 was 67.44% (58/86) and 60.47% (52/86), respectively; the expression of nucleus Gli1 was correlated with the tumor pathological grade (P=0.034), and with the ability of the tumor to invade and metastasize (P=0.001); the expression of nucleus Gli1 was also correlated with p-ERK1/2 (P=0.031) and with MMP-9 (P=0.034). Neither Shh, nor nucleus Gli1 was observed in normal liver tissue. KAAD-cyclopamine (KAAD-cyc), a specific inhibitor of the Hh pathway, at the concentrations of 1 and 4 mumol/L inhibited the invasion and migration of Bel-7402 cells and decreased the expression of Gli1 in nucleus and MMP-9, p-ERK1/2 proteins in Bel-7402 cells. On the other hand, Shh, a ligand of the Hh pathway, at the concentration of 0.5 mug/mL produced opposite effects. The MAPK pathway inhibitors U0126 and PD98059 at the concentrations of 5 and 10 mumol/L inhibited invasion and metastasis of Bel-7402 cells induced by Shh, and decreased the expression of p-ERK1/2 and MMP-9. However, U0126 and PD98059 had no effect on the expression of Gli1. CONCLUSION: Hh signaling pathway mediates invasion and metastasis of human HCC by up-regulating the protein expression of MMP-9 via ERK pathway.

tumor cells often use developmental processes to progress toward advanced disease. The E-box transcription factor TWIST1 is essential to epithelial-mesenchymal transition (EMT) and cell migration in the developing neural crest. In melanoma, which derives from the neural crest cell lineage, enhanced TWIST1 expression has been linked to worse clinical prognosis. However, mechanisms underlying TWIST1 expression and whether aberrant TWIST1 levels promote steps in melanoma progression remain unknown. Here, we report that elevated TWIST1 mRNA/protein expression is dependent on extracellular signal-regulated kinase (ERK)1/2 signaling, which is hyperactive in the majority of melanomas. We show that TWIST1 protein levels are especially high in melanoma cell lines generated from invasive, premetastatic stage tumors. Furthermore, TWIST1 expression is required and sufficient to promote invasion through Matrigel and spheroid outgrowth in three-dimensional dermal-mimetic conditions. Alterations to spheroid outgrowth were not as a result of altered cell death, cell-cycle profile, or paradigm EMT protein changes. Importantly, we identify matrix metalloproteinase-1 (MMP-1) as a novel downstream target of TWIST1. We have determined that TWIST1 acts, in a dose-dependent manner, as a mediator between hyperactive ERK1/2 signaling and regulation of MMP-1 transcription. Together, these studies mechanistically show a previously unrecognized interplay between ERK1/2, TWIST1, and MMP-1 that is likely significant in the progression of melanoma toward metastasis.

BACKGROUND: Many members of the ETS-domain transcription factor family are important drivers of tumourigenesis. In this context, their activation by Ras-ERK pathway signaling is particularly relevant to the tumourigenic properties of many ETS-domain transcription factors. The PEA3 subfamily of ETS-domain transcription factors have been implicated in tumour metastasis in several different cancers. RESULTS: Here, we have studied the expression of the PEA3 subfamily members PEA3/ETV4 and ER81/ETV1 in oesophageal adenocarcinomas and determined their role in oesophageal adenocarcinoma cell function. PEA3 plays an important role in controlling both the proliferation and invasive properties of OE33 oesophageal adenocarcinoma cells. A key target gene is MMP-1. The ERK MAP kinase pathway activates PEA3 subfamily members and also plays a role in these PEA3 controlled events, establishing the ERK-PEA3-MMP-1 axis as important in OE33 cells. PEA3 subfamily members are upregulated in human adenocarcinomas and expression correlates with MMP-1 expression and late stage metastatic disease. Enhanced ERK signaling is also more prevalent in late stage oesophageal adenocarcinomas. CONCLUSIONS: This study shows that the ERK-PEA3-MMP-1 axis is upregulated in oesophageal adenocarcinoma cells and is a potentially important driver of the metastatic progression of oesophageal adenocarcinomas.

Prostate cancer cell migration is an essential event both in the progression of prostate cancer and in the steps leading to metastasis. We report here that lysophosphatidic acid (LPA), a potent bioactive phospholipid, induces prostate cancer PC3 cell migration via the activation of the LPA(1) receptor, which is linked to a PTX-sensitive activation mechanism of the mitogen-activated protein kinases (MAPK). Our results demonstrate that parallel activation of ERK1/2 and p38, but not JNK, is responsible for LPA-stimulated PC3 cell migration. Furthermore, using small interfering RNA (siRNA) technology, and overexpressing dominant-negative mutants of p38 MAPK isotypes of alpha, beta, gamma and delta, we have identified that the activation of ERK2 (p42) and p38alpha, but not of ERK1 and the other isoforms of p38 MAPK, is required for LPA-induced migration. Our study provides the first evidence for a functional role of p42 and p38alpha in LPA-induced mammalian cell migration, and also demonstrates, for the first time, that the receptor LPA(1) mediates prostate cancer cell migration. The results of the present study suggest that LPA, the receptor LPA(1), ERK2 and p38alpha are important regulators for prostate cancer cell invasion and thus could play a significant role in the development of metastasis.

Lung metastasis is one of the important characteristics of salivary adenoid cystic carcinoma (SACC). Although activation of extracellular signal-regulated kinase 1/2 (ERK1/2) pathway may be associated with cancer progression in some malignant tumors, its roles in lung metastasis of SACC remains unclear. We examined the expression of activated ERK1/2 in SACC-LM with high lung-metastatic rate and SACC-83 with low lung-metastatic rate, as well as in the tissues from lung-metastatic and non-metastatic groups of SACC patients. Western blot analysis indicated that SACC-LM exhibited higher expression of activated ERK1/2 than SACC-83. Similarly, immunohistochemistry showed that expression of activated ERK1/2 was detected in 73% (8/11) of the primary tissues from SACC patients with lung metastasis, while only 25% (3/12) of the primary tissues from SACC patients without lung metastasis (P<0.05). Furthermore, we examined the effects of U0126, a specific inhibitor of mitogen activated protein kinase kinase (MEK or MAPKK), on migration and invasion in SACC-LM cells, showing U0126 not only inactivated ERK1/2, but also inhibited migration and invasion of SACC-LM. The present findings suggested that the elevated expression of activated ERK1/2 may play a role in lung metastasis of salivary adenoid cystic carcinoma.