u-0126 and Colorectal-Neoplasms

5-Fluorouracil (5-Fu) is the first-line chemotherapeutic option for colorectal cancer. However, its efficacy is inhibited by drug resistance. Cytokines play an important role in tumor drug resistance, even though their mechanisms are largely unknown. Using a cytokine array, we established that tissue inhibitor metalloproteinase 2 (TIMP-2) is highly expressed in 5-Fu resistant colorectal cancer patients. Analysis of samples from 84 patients showed that elevated TIMP-2 expression levels in colorectal patients were correlated with poor prognostic outcomes. In a 5-Fu-resistant patient-derived xenograft (PDX) model, TIMP-2 was also found to be highly expressed. We established an autocrine mechanism through which elevated TIMP-2 protein levels sustained colorectal cancer cell resistance to 5-Fu by constitutively activating the ERK/MAPK signaling pathway. Inhibition of TIMP-2 using an anti-TIMP-2 antibody or ERK/MAPK inhibition by U0126 suppressed TIMP-2 mediated 5-Fu-resistance in CRC patients. In conclusion, a novel TIMP-2-ERK/MAPK mediated 5-Fu resistance mechanism is involved in colorectal cancer. Therefore, targeting TIMP-2 or ERK/MAPK may provide a new strategy to overcome 5-Fu resistance in colorectal cancer chemotherapy.

Topics: Aged; Animals; Butadienes; Cell Survival; Colorectal Neoplasms; Cytokines; Drug Resistance, Neoplasm; Extracellular Signal-Regulated MAP Kinases; Female; Fluorouracil; Gene Expression Regulation, Neoplastic; Humans; Male; MAP Kinase Signaling System; Mice; Mice, Nude; Middle Aged; Neoplasms, Experimental; Nitriles; Tissue Inhibitor of Metalloproteinase-2; Transcriptome; Young Adult

Curcumin, a major yellow pigment and spice in turmeric and curry, has been demonstrated to have an anticancer effect in human clinical trials. Mutation of KRAS has been shown in 35%-45% of colorectal cancer, and regorafenib has been approved by the US FDA to treat patients with colorectal cancer. Synthetic lethality is a type of genetic interaction between two genes such that simultaneous perturbations of the two genes result in cell death or a dramatic decrease of cell viability, while a perturbation of either gene alone is not lethal. Here, we reveal that curcumin significantly enhanced the growth inhibition of regorafenib in human colorectal cancer HCT 116 cells (KRAS mutant) to a greater extent than in human colorectal cancer HT-29 cells (KRAS wild-type), producing an additive or synergistic effect in HCT 116 cells and causing an antagonistic effect in HT-29 cells. Flow cytometric analysis showed that the addition of curcumin elevated apoptosis and greatly increased autophagy in HCT 116 cells but not in HT-29 cells. Mechanistically, curcumin behaved like MEK-specific inhibitor (U0126) to enhance regorafenib-induced growth inhibition, apoptosis and autophagy in HCT 116 cells. Our data suggest that curcumin may target one more gene other than mutant KRAS to enhance regorafenib-induced growth inhibition (synthetic lethality) in colorectal cancer HCT 116 cells, indicating a possible role of curcumin in regorafenib-treated KRAS mutant colorectal cancer.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Butadienes; Colorectal Neoplasms; Curcumin; Gene Expression Regulation, Neoplastic; HCT116 Cells; HT29 Cells; Humans; MAP Kinase Kinase Kinases; Mutation; Nitriles; Phenylurea Compounds; Protein Kinase Inhibitors; Proto-Oncogene Proteins p21(ras); Pyridines

Mitogen‑activated protein kinase kinase (MEK) small molecule inhibitors have been investigated in preclinical or clinical trials for the treatment of cancer. In the present study the genetic test results of 120 patients with colorectal cancer (CRC) were screened and the mutation rate of MEK1 was identified to be 1.67%. MEK inhibition by U0126 significantly decreased the growth of SW48 cells that harbored the MEK1 Q56P mutation, although it did not evidently affect the growth of NCI‑H508 cells with MEK1 wild‑type. In addition, U0126 increased the sensitivity of SW48 cells to 5‑fluorouracil (5‑FU) and oxaliplatin by producing more γH2AX foci and decreasing the expression of excision repair cross‑complementation group 1 and thymidylate synthase. The results suggested that MEK inhibitors in combination with oxaliplatin/5‑FU may offer an improved therapeutic effect in patients with MEK‑mutant CRC.

Topics: Aged; Antineoplastic Combined Chemotherapy Protocols; Butadienes; Cell Line, Tumor; Cell Survival; Colorectal Neoplasms; DNA-Binding Proteins; Drug Synergism; Endonucleases; Female; Fluorouracil; Gene Expression Regulation, Neoplastic; Histones; Humans; Male; MAP Kinase Kinase 1; Middle Aged; Mutation; Neoplasm Grading; Neoplasm Metastasis; Neoplasm Staging; Nitriles; Oxaliplatin; Signal Transduction; Thymidylate Synthase

Topics: Animals; Apoptosis; Butadienes; Cell Cycle Checkpoints; Cell Line, Tumor; Colorectal Neoplasms; ets-Domain Protein Elk-1; Humans; Isothiocyanates; MAP Kinase Signaling System; Nitriles; Phosphorylation; Rats; Receptors, TNF-Related Apoptosis-Inducing Ligand; Signal Transduction; Transcription Factor CHOP; Tumor Suppressor Protein p53

Baicalein, a naturally occurring flavonoid isolated from the roots of Scutellaria baicalensis, is historically and widely used as anti-inflammatory and anticancer therapy. Nevertheless, the anti-metastatic effect and underlying molecular mechanisms of baicalein on colorectal carcinoma (CRC) remain unclear. The aim of the present study was, therefore, to invastigate the anti-metastatic activity of baicalein and related mechanism(s) on CRC cells. In this study, we observed that baicalein treatment inhibited proliferation, as well as migration and invasion of HT-29 and DLD1 cells. Baicalein decreased the expression of the matrix metalloproteinases-2 (MMP-2) and MMP-9 in a dose-dependent manner. Also, baicalein treatment significantly reduced phosphorylation of extracellular signal regulated kinases (ERK). Furthermore, in DLD1 cells, MEK1 overexpression partially blocked the anti-metastatic effects of baicalein. Combined treatment with an ERK inhibitor (U0126) and baicalein led to the synergistic reduction of MMP-2/9 expression; and the invasive capabilities of DLD1 cells were also inhibited markedy. Finally, intragastric administration of baicalein inhibited CRC xenograft growth in vivo and suppressed the phosphorylation of ERK and the expression of MMP-2/9 in tumor tissues. Consequently, baicalein suppresses CRC cell invasion via inhibition of the ERK signaling pathways, indicating that baicalein is a potential agent for CRC treatment.

Topics: Animals; Butadienes; Cell Line, Tumor; Cell Movement; Cell Proliferation; Colorectal Neoplasms; Dose-Response Relationship, Drug; Drug Synergism; Flavanones; Gene Expression Regulation, Neoplastic; HT29 Cells; Humans; MAP Kinase Signaling System; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Neoplasm Invasiveness; Neoplasm Metastasis; Nitriles; Phosphorylation; Xenograft Model Antitumor Assays

Colorectal cancer (CRC) cells have been previously observed to be resistant to paclitaxel‑induced apoptosis by activation of the mitogen‑activated protein/extracellular signal‑regulated kinase (MEK)/ERK signaling pathway and increased expression of glucose‑regulated protein 78 (GRP78). Caffeine, the most widely used neuroactive compound, has antiproliferative activity and the ability to induce cell cycle arrest and apoptosis. In the current study, the effect of concomitant use of caffeine on paclitaxel‑induced apoptosis in CRC cells was investigated. The results revealed that treatment of Colo205 cells with varying caffeine concentrations did not induce apoptosis. Pretreatment of CRC cells with caffeine significantly inhibited paclitaxel‑induced cytotoxicity by increasing the levels of the antiapoptotic Bcl‑2 family member, Mcl‑1. This effect was inhibited by pretreatment of Colo205 cells with the MEK‑ERK chemical inhibitor, U0126. In addition to GRP78, these results indicated that Mcl‑1 may be a downstream target of the MEK‑ERK signaling pathway. Moreover, administration of caffeine may decrease chemotherapeutic responses to paclitaxel by the MEK‑ERK mediated upregulation of Mcl‑1. In conclusion, coadministration of cell cycle‑modifying agents, including caffeine should be avoided in CRC patients treated with paclitaxel.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Butadienes; Caffeine; Cell Line, Tumor; Cell Survival; Colorectal Neoplasms; Endoplasmic Reticulum Chaperone BiP; Extracellular Signal-Regulated MAP Kinases; Heat-Shock Proteins; Humans; Mitogen-Activated Protein Kinases; Myeloid Cell Leukemia Sequence 1 Protein; Nitriles; Paclitaxel; Signal Transduction; Up-Regulation

The transcription factor E2F4 controls proliferation of normal and cancerous intestinal epithelial cells. E2F4 localization in normal human intestinal epithelial cells (HIEC) is cell cycle-dependent, being cytoplasmic in quiescent differentiated cells but nuclear in proliferative cells. However, the intracellular signaling mechanisms regulating such E2F4 localization remain unknown.. Treatment of quiescent HIEC with serum induced ERK1/2 activation, E2F4 phosphorylation, E2F4 nuclear translocation and G1/S phase transition while inhibition of MEK/ERK signaling by U0126 prevented these events. Stimulation of HIEC with epidermal growth factor (EGF) also led to the activation of ERK1/2 but, in contrast to serum or lysophosphatidic acid (LPA), EGF failed to induce E2F4 phosphorylation, E2F4 nuclear translocation and G1/S phase transition. Furthermore, Akt and GSK3β phosphorylation levels were markedly enhanced in serum- or LPA-stimulated HIEC but not by EGF. Importantly, E2F4 phosphorylation, E2F4 nuclear translocation and G1/S phase transition were all observed in response to EGF when GSK3 activity was concomitantly inhibited by SB216763. Finally, E2F4 was found to be overexpressed, phosphorylated and nuclear localized in epithelial cells from human colorectal adenomas exhibiting mutations in APC and KRAS or BRAF genes, known to deregulate GSK3/β-catenin and MEK/ERK signaling, respectively.. The present results indicate that MEK/ERK activation and GSK3 inhibition are both required for E2F4 phosphorylation as well as its nuclear translocation and S phase entry in HIEC. This finding suggests that dysregulated E2F4 nuclear localization may be an instigating event leading to hyperproliferation and hence, of tumor initiation and promotion in the colon and rectum.

Topics: Adenoma; Butadienes; Cell Cycle; Cell Line; Cell Proliferation; Cells, Cultured; Colorectal Neoplasms; E2F4 Transcription Factor; Enzyme Inhibitors; Epidermal Growth Factor; Glycogen Synthase Kinase 3; Humans; Intestinal Mucosa; Lysophospholipids; MAP Kinase Signaling System; Mitogens; Nitriles; Phosphorylation; Transcription, Genetic

Results from clinical trials involving resistance to molecularly targeted therapies have revealed the importance of rational single-agent and combination treatment strategies. In this study, we tested the efficacy of a type 1 insulin-like growth factor receptor (IGF1R)/insulin receptor (IR) tyrosine kinase inhibitor, OSI-906, in combination with a mitogen-activated protein (MAP)-ERK kinase (MEK) 1/2 inhibitor based on evidence that the MAP kinase pathway was upregulated in colorectal cancer cell lines that were resistant to OSI-906.. The antiproliferative effects of OSI-906 and the MEK 1/2 inhibitor U0126 were analyzed both as single agents and in combination in 13 colorectal cancer cell lines in vitro. Apoptosis, downstream effector proteins, and cell cycle were also assessed. In addition, the efficacy of OSI-906 combined with the MEK 1/2 inhibitor selumetinib (AZD6244, ARRY-142886) was evaluated in vivo using human colorectal cancer xenograft models.. The combination of OSI-906 and U0126 resulted in synergistic effects in 11 of 13 colorectal cancer cell lines tested. This synergy was variably associated with apoptosis or cell-cycle arrest in addition to molecular effects on prosurvival pathways. The synergy was also reflected in the in vivo xenograft studies following treatment with the combination of OSI-906 and selumetinib.. Results from this study demonstrate synergistic antiproliferative effects in response to the combination of OSI-906 with an MEK 1/2 inhibitor in colorectal cancer cell line models both in vitro and in vivo, which supports the rational combination of OSI-906 with an MEK inhibitor in patients with colorectal cancer. Clin Cancer Res; 19(22); 6219-29. ©2013 AACR.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzimidazoles; Butadienes; Caspase 3; Caspase 7; Cell Cycle; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Drug Resistance, Neoplasm; Enzyme Inhibitors; Female; Humans; Imidazoles; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Mice; Mice, Nude; Neoplasm Transplantation; Nitriles; Protein Kinase Inhibitors; Pyrazines; Receptor, IGF Type 1; Receptor, Insulin; Signal Transduction; Transplantation, Heterologous

Aquaporins (AQPs) are a family of small, integral membrane proteins that have been shown to play an important role in tumor development and metastasis. Several studies have demonstrated that expression of AQP3 contributes to the enhanced migration of epithelial cells and is related to differentiation, metastasis and vascular invasion in lung and gastric cancer. Therefore, we investigated whether AQP3 could enhance human colorectal carcinoma cell migration and we examined the role of AQP3 in the prognosis of colorectal carcinoma. Our results showed that human epidermal growth factor (hEGF) increased the expression of AQP3 and, subsequently, the migration ability of human colorectal carcinoma cells HCT116 in a dose- and time-dependent manner. The enhanced migration ability of HCT116 cells was blocked by the AQP3 inhibitor, CuSO(4). Overexpression of AQP3 induced by hEGF was inhibited by a PI3K/AKT inhibitor, LY294002, but the ERK inhibitor U0126 had a minor effect on the hEGF-induced AQP3 upregulation. Immunohistochemical staining of the cancer tissues and corresponding normal tissues showed that AQP3 expression in cancer tissue was higher compared to that in normal tissue. The expression intensity of AQP3 was associated with the differentiation, lymph node and distant metastasis of colorectal carcinoma patients. Our results suggest that AQP3 overexpression could facilitate colorectal carcinoma cell migration and AQP3 may be considered a potential indicator and therapeutic target for colon tumor metastasis and prognosis.

Topics: Adult; Aged; Aged, 80 and over; Analysis of Variance; Aquaporin 3; Butadienes; Carcinoma; Cell Movement; Chi-Square Distribution; Chromones; Colorectal Neoplasms; Copper Sulfate; Enzyme Inhibitors; Epidermal Growth Factor; ErbB Receptors; Female; HCT116 Cells; Humans; Lymphatic Metastasis; Male; MAP Kinase Signaling System; Middle Aged; Morpholines; Nitriles; Phosphatidylinositol 3-Kinases; Prognosis; Proto-Oncogene Proteins c-akt; Up-Regulation

The mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway has a master control role in various cancer-related biological processes as cell growth, proliferation, differentiation, migration, and apoptosis. It also regulates many transcription factors that control microRNAs (miRNAs) and their biosynthetic machinery. To investigate on the still poorly characterised global involvement of miRNAs within the pathway, we profiled the expression of 745 miRNAs in three colorectal cancer (CRC) cell lines after blocking the pathway with three different inhibitors. This allowed the identification of two classes of post-treatment differentially expressed (DE) miRNAs: (1) common DE miRNAs in all CRC lines after treatment with a specific inhibitor (class A); (2) DE miRNAs in a single CRC line after treatment with all three inhibitors (class B). By determining the molecular targets, biological roles, network position of chosen miRNAs from class A (miR-372, miR-663b, miR-1226*) and class B (miR-92a-1*, miR-135b*, miR-720), we experimentally demonstrated that they are involved in cell proliferation, migration, apoptosis, and globally affect the regulation circuits centred on MAPK/ERK signaling. Interestingly, the levels of miR-92a-1*, miR-135b*, miR-372, miR-720 are significantly higher in biopsies from CRC patients than in normal controls; they also are significantly higher in CRC patients with mutated KRAS than in those with wild-type genotypes (Wilcoxon test, p < 0.05): the latter could be a downstream effect of ERK pathway overactivation, triggered by KRAS mutations. Finally, our functional data strongly suggest the following miRNA/target pairs: miR-92a-1*/PTEN-SOCS5; miR-135b*/LATS2; miR-372/TXNIP; miR-663b/CCND2. Altogether, these results contribute to deepen current knowledge on still uncharacterized features of MAPK/ERK pathway, pinpointing new oncomiRs in CRC and allowing their translation into clinical practice and CRC therapy.

Topics: Apoptosis; Blotting, Western; Butadienes; Caco-2 Cells; Cell Movement; Cell Survival; Colorectal Neoplasms; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; HCT116 Cells; Humans; In Vitro Techniques; MicroRNAs; Mitogen-Activated Protein Kinases; Nitriles; Pyrazoles; Pyridazines; Transcriptome

Colon carcinomas frequently contain activating mutations in the K-ras proto-oncogene. K-ras itself is a poor drug target and drug development efforts have mostly focused on components of the classical Ras-activated MEK/ERK pathway. Here we have studied whether endogenous oncogenic K-ras affects the dependency of colorectal tumor cells on MEK/ERK signaling.. K-ras mutant colorectal tumor cell lines C26, HCT116 and L169 were used. K-ras or components of the MEK/ERK and p38 pathway were suppressed by RNA interference (RNAi). MEK was inhibited by U0126. p38 was inhibited by SB203850.. MEK inhibition, or suppression of MEK1/2 or ERK1/2 by RNA interference, reduced the proliferation rate of all colorectal cancer cell lines. However, cell proliferation returned to normal after two weeks of chronic inhibition, despite the continued suppression of MEK or ERK. In contrast, K-ras-suppressed tumor cells entered an irreversible senescent-like state following ERK pathway inhibition. MEK inhibition or ERK1/2 suppression caused activation of p38alpha in a K-ras-dependent manner. Inhibition or suppression of p38alpha prevented the recovery of K-ras mutant tumor cells during prolonged MEK inhibition.. Oncogenic K-ras activates p38alpha to maintain cell proliferation during MEK inhibition. MEK-targeting therapeutics can create an acquired tumor cell dependency on p38alpha.

Topics: Butadienes; Cell Proliferation; Cellular Senescence; Colorectal Neoplasms; Drug Design; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Neoplastic; Genes, ras; Growth Inhibitors; HCT116 Cells; Humans; Nitriles; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Mas; RNA, Small Interfering; Signal Transduction; Transcriptional Activation

Among the most harmful of all genetic abnormalities that appear in colorectal cancer (CRC) development are mutations of KRAS and its downstream effector BRAF as they result in abnormal extracellular signal-related kinase (ERK) signaling. In a previous report, we had shown that expression of a constitutive active mutant of MEK1 (caMEK) in normal rat intestinal epithelial cells (IECs) induced morphological transformation associated with epithelial to mesenchymal transition, growth in soft agar, invasion and metastases in nude mice. Results from microarrays comparing control to caMEK-expressing IECs identified the gene encoding for serpinE2, a serine protease inhibitor, as a potential target of activated MEK1.. 1- RT-PCR and western blot analyses confirmed the strong up-regulation of serpinE2 expression and secretion by IECs expressing oncogenic MEK, Ras or BRAF. 2- Interestingly, serpinE2 mRNA and protein were also markedly enhanced in human CRC cells exhibiting mutation in KRAS and BRAF. 3- RNAi directed against serpinE2 in caMEK-transformed rat IECs or in human CRC cell lines HCT116 and LoVo markedly decreased foci formation, anchorage-independent growth in soft agarose, cell migration and tumor formation in nude mice. 4- Treatment of CRC cell lines with U0126 markedly reduced serpinE2 mRNA levels, indicating that expression of serpinE2 is likely dependent of ERK activity. 5- Finally, Q-PCR analyses demonstrated that mRNA levels of serpinE2 were markedly increased in human adenomas in comparison to healthy adjacent tissues and in colorectal tumors, regardless of tumor stage and grade.. Our data indicate that serpinE2 is up-regulated by oncogenic activation of Ras, BRAF and MEK1 and contributes to pro-neoplastic actions of ERK signaling in intestinal epithelial cells. Hence, serpinE2 may be a potential therapeutic target for colorectal cancer treatment.

Topics: Animals; Blotting, Western; Butadienes; Cell Line, Tumor; Colorectal Neoplasms; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; HCT116 Cells; Humans; In Vitro Techniques; MAP Kinase Kinase 1; Mice; Mice, Nude; Nitriles; Oligonucleotide Array Sequence Analysis; Proto-Oncogene Proteins B-raf; ras Proteins; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Serpin E2; Signal Transduction

Phase II clinical trials of mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitors are ongoing and ERK1/2 activation is frequently used as a biomarker. In light of the mutational activation of BRAF and KRAS in colorectal cancer, inhibitors of the Raf-MEK-ERK mitogen-activated protein kinase are anticipated to be promising. Previous studies in pancreatic cancer have found little correlation between BRAF/KRAS mutation status and ERK1/2 activation, suggesting that identifying biomarkers of MEK inhibitor response may be more challenging than previously thought. The purpose of this study was to evaluate the effectiveness of MEK inhibitor therapy for colorectal cancer and BRAF/KRAS mutation status and ERK1/2 activation as biomarkers for MEK inhibitor therapy. First, we found that MEK inhibitor treatment impaired the anchorage-independent growth of nearly all KRAS/BRAF mutant, but not wild-type, colorectal cancer cells. There was a correlation between BRAF, but not KRAS, mutation status and ERK1/2 activation. Second, neither elevated ERK1/2 activation nor reduction of ERK1/2 activity correlated with MEK inhibition of anchorage-independent growth. Finally, we validated our cell line observations and found that ERK1/2 activation correlated with BRAF, but not KRAS, mutation status in 190 patient colorectal cancer tissues. Surprisingly, we also found that ERK activation was elevated in normal colonic epithelium, suggesting that normal cell toxicity may be a complication for colorectal cancer treatment. Our results suggest that although MEK inhibitors show promise in colorectal cancer, KRAS/BRAF mutation status, but not ERK activation as previously thought, may be useful biomarkers for MEK inhibitor sensitivity.

Topics: Biomarkers, Tumor; Butadienes; Cell Proliferation; Colorectal Neoplasms; Enzyme Inhibitors; Humans; Immunoenzyme Techniques; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mutation; Nitriles; Proto-Oncogene Proteins; Proto-Oncogene Proteins B-raf; Proto-Oncogene Proteins p21(ras); ras Proteins; Tissue Array Analysis; Tumor Cells, Cultured

CXCL12 and CXCR4 signaling plays critical roles in development, homeostasis, and tumor metastasis. Previously, we have shown that epigenetic silencing of CXCL12 in colorectal and mammary carcinomas promotes metastasis. Anoikis is an essential process of colonic epithelial turnover and limits the metastatic progression of carcinoma. We sought to determine the role for anoikis in limiting tumor metastasis following reexpression of CXCL12 in human colorectal carcinoma cells.. Tumor formation and metastasis of colonic carcinoma cells was monitored using in vivo bioluminescence imaging. Anoikis was defined by using caspase-3/7, focal adhesion kinase (FAK) and p130Cas cleavage, DNA fragmentation, and cell survival assays. Phosphorylation of extracellular-regulated kinase-1/2 (ERK1/2) was monitored by immunoblot and immunohistochemistry, and activity was inhibited by using U0126.. Constitutive expression of CXCL12 in human colorectal carcinoma cells reduced orthotopic tumor formation and inhibited metastasis in severe combined immunodeficient mice. Further, CXCL12 expression induced apoptosis specifically in nonadherent colorectal carcinoma cells. Apoptotic cell death was preceded by hypophosphorylation and cleavage of FAK and p130Cas, leading to increased cellular detachment in culture, and depended on alterations in the extracellular matrix. Similar to in vivo colonic epithelium, CXCL12-induced anoikis of carcinoma cells depended on basal ERK1/2 activation.. These data significantly expand the current paradigm of chemokine signaling in carcinogenesis by showing that endogenous CXCL12, in marked contrast to exogenous ligand, inhibits tumor metastasis through increased anoikis. Altered ERK1/2 signaling provides a mechanism for the dichotomy between the physiologic and pathophysiologic roles of CXCL12-CXCR4 signaling in the intestinal epithelium.

Topics: Animals; Anoikis; Autocrine Communication; Butadienes; Caspase 3; Caspase 7; Cell Adhesion; Cell Survival; Chemokine CXCL12; Colorectal Neoplasms; Crk-Associated Substrate Protein; DNA Fragmentation; Focal Adhesion Protein-Tyrosine Kinases; Focal Adhesions; HCT116 Cells; HT29 Cells; Humans; Immunoblotting; Immunohistochemistry; Luminescent Measurements; Mice; Mice, SCID; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neoplasm Metastasis; Nitriles; Phosphorylation; Protein Kinase Inhibitors; Signal Transduction; Time Factors; Transfection

Vascular endothelial growth factor plays a key role in human colorectal carcinoma invasion and metastasis. However, the regulation mechanism remains unknown. Recent studies have shown that several cytokines can regulate the expression of vascular endothelial growth factor in tumor cells. In this study, we investigated whether hepatocyte growth factor can regulate the expression of vascular endothelial growth factor in colorectal carcinoma cells.. Hepatocyte growth factor and vascular endothelial growth factor in human serum were measured by ELISA. The mRNA level of vascular endothelial growth factor was analyzed by reverse transcription-PCR. Western blot assay was performed to evaluate levels of c-Met and several other proteins involved in the MAPK and PI3K signaling pathways in colorectal carcinoma cells.. Serum hepatocyte growth factor and vascular endothelial growth factor were significantly increased in colorectal carcinoma subjects. In vitro extraneous hepatocyte growth factor markedly increased protein and mRNA levels of vascular endothelial growth factor in colorectal carcinoma cells. Hepatocyte growth factor induced phosphorylation of c-Met, ERK1/2 and AKT in a dose-dependent manner. Specific inhibitors on MEK and PI3K inhibited the hepatocyte growth factor-induced expression of vascular endothelial growth factor in colorectal carcinoma cells.. This present study indicates that hepatocyte growth factor upregulates the expression of vascular endothelial growth factor in colorectal carcinoma cells via the MEK/ERK and PI3K/AKT signaling pathways.

Topics: Butadienes; Cell Line, Tumor; Chromones; Colorectal Neoplasms; Gene Expression Regulation; Hepatocyte Growth Factor; Humans; MAP Kinase Signaling System; Morpholines; Nitriles; Phosphatidylinositol 3-Kinases; Phosphorylation; Proto-Oncogene Proteins c-met; RNA, Messenger; Signal Transduction; Vascular Endothelial Growth Factor A

Several mitogen-activated protein kinase (MAPK) signaling inhibitors are currently undergoing clinical trial as part of novel mechanism-based anticancer treatment strategies. This study was aimed at detecting biomarkers of MAPK signaling inhibition in human breast and colon carcinoma cells using magnetic resonance spectroscopy. We investigated the effect of the prototype MAPK kinase inhibitor U0126 on the (31)P-MR spectra of MDA-MB-231, MCF-7 and Hs578T breast, and HCT116 colon carcinoma cells. Treatment of MDA-MB-231 cells with 50 micromol/L U0126 for 2, 4, 8, 16, 24, 32, and 40 hours caused inhibition of extracellular signal-regulated kinases (ERK1/2) phosphorylation from 2 hours onwards. (31)P-MR spectra of extracted cells indicated that this was associated with a significant drop in phosphocholine levels to 78 +/- 8% at 8 hours, 74 +/- 8% at 16 hours, 66 +/- 7% at 24 hours, 71 +/- 10% at 32 hours, and 65 +/- 10% at 40 hours post-treatment. In contrast, the lower concentration of 10 micromol/L U0126 for 40 hours had no significant effect on either P-ERK1/ 2 or phosphocholine levels in MDA-MB-231 cells. Depletion of P-ERK1/2 in MCF-7 and Hs578T cells with 50 micromol/L U0126 also produced a drop in phosphocholine levels to 51 +/- 17% at 40 hours and 23 +/- 12% at 48 hours, respectively. Similarly, in HCT116 cells, inhibition with 30 micromol/L U0126 caused depletion of P-ERK1/2 and a decrease in phosphocholine levels to 80 +/- 9% at 16 hours and 61 +/- 4% at 24 hours post-treatment. The reduction in phosphocholine in MDA-MB-231 and HCT116 cells correlated positively with the drop in P-ERK1/2 levels. Our results show that MAPK signaling inhibition with U0126 is associated with a time-dependent decrease in cellular phosphocholine levels. Thus, phosphocholine has potential as a noninvasive pharmacodynamic marker for monitoring MAPK signaling blockade.

Topics: Biomarkers, Tumor; Breast Neoplasms; Butadienes; Cell Line, Tumor; Colorectal Neoplasms; Enzyme Inhibitors; HCT116 Cells; Humans; Magnetic Resonance Spectroscopy; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Nitriles; Phosphorylcholine

Constitutive activation of mitogen-activated protein kinase (MAPK) pathway is implicated in a variety of human malignancies especially those that carry Ras mutations and is currently exploited as a cancer therapeutic target. The variability of response by cancer cells to the inhibition of the Ras/MAPK pathway both in vivo and in vitro, however, suggests that the genetic background of the tumor cell may modulate the effectiveness of this directed therapeutic. In a panel of colorectal cancer cell lines that carry Ras mutations and have constitutively active MEK/MAPK, we found that inhibition of the MAPK upstream kinase MEK by the small molecular MEK inhibitor U0126 induced cell death only in p53 wild-type cells. By contrast, p53-deficient cells were not affected by blocking the MEK/MAPK pathway. Using isogenic colon cancer cell lines and RNA interference, we show that loss of p53 significantly reduces MAPK phosphorylation and renders cells resistant to U0126 treatment. These findings reveal a critical role for p53 in MAPK-driven cell survival and place p53 upstream in the control cascade of MAPK activity. The therapeutic implication of these observations is that MAPK inhibitors will be most beneficial as a therapeutic agent in p53 normal colon cancers where constitutively active MAPK resulting from a Ras mutation is required for cell survival.

Topics: Apoptosis; Butadienes; Colorectal Neoplasms; Humans; Mitogen-Activated Protein Kinases; Mutation; Nitriles; ras Proteins; Tumor Suppressor Protein p53

Mutations in oncogenic Ras contribute to colorectal tumorigenesis. Loss of the cell adhesion protein E-cadherin is associated with tumor invasion and metastasis.. Expression of oncogenic Ras was induced in intestinal epithelial cells. Changes in cell morphology, E-cadherin protein expression, and E-cadherin localization were examined by light microscopy, Western blot, and immunofluorescence respectively. Expression of E-cadherin in human colorectal tumors was examined by immunohistochemistry.. Induction of oncogenic Ras results in an epithelial to mesenchymal transformation with loss of membranous E-cadherin expression and mis-localization to the cytoplasm. Removal of Ras stimulus or blockade of the MAP kinase pathway allowed reversion to a normal cellular phenotype and return of E-cadherin to the cell membrane. Loss of or decreased expression of E-cadherin was observed in seven of eight colorectal tumors.. Oncogenic Ras contributes to malignant transformation and altered E-cadherin expression in intestinal epithelial cells. Similar dysregulation of E-cadherin is found in human colorectal tumors. Ras effects on E-cadherin are critical to malignant transformation in our in-vitro model and may be an important event in human colorectal tumors.

Topics: Animals; Blotting, Western; Butadienes; Cadherins; Cells, Cultured; Colorectal Neoplasms; Enzyme Inhibitors; Epithelial Cells; Genes, ras; Humans; Intestinal Mucosa; Mitogen-Activated Protein Kinase Kinases; Mutation; Nitriles; Rats

Nonsteroidal antiinflammatory drugs (NSAIDs) can prevent colorectal tumorigenesis in humans and in rodents. In vitro and in vivo studies indicate that one of their principal antineoplastic avenues is the induction of apoptosis. We have shown previously that NS-398, which selectively inhibits cyclooxygenase-2 (COX-2) over cyclooxygenase-1, induces apoptosis of colorectal tumour cells and elevates COX-2 protein expression. Here, we have determined that the extracellular signal-regulated kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway mediates these effects of NS-398. Treatment of HT29 colorectal carcinoma cells with 75 microM NS-398 caused activation of ERK-1/-2 but not of the p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases. This was apparent at 24 hr and maintained at 72 hr. U0126, a specific inhibitor of the ERK-activating kinases MEK-1/-2, prevented the activation of ERK induced by NS-398 and blocked the increase in COX-2 protein expression seen when HT29 cells were treated with NS-398 alone. The activation of ERK by NS-398 preceded and accompanied a decrease in attached cell yield and an increase in apoptosis. U0126 dose-dependently protected HT29 cells from these antiproliferative effects of NS-398, indicating an antiproliferative role for sustained ERK-1/-2 activation in response to this NSAID. These results point to a key role for the MEK/ERK signalling pathway in mediating the effects of a COX-2-selective NSAID on colorectal carcinoma cells.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Butadienes; Cell Division; Colorectal Neoplasms; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dose-Response Relationship, Drug; Enzyme Inhibitors; Humans; Isoenzymes; JNK Mitogen-Activated Protein Kinases; MAP Kinase Kinase Kinase 1; Membrane Proteins; Mitogen-Activated Protein Kinases; Nitriles; Nitrobenzenes; Prostaglandin-Endoperoxide Synthases; Protein Serine-Threonine Kinases; Signal Transduction; Sulfonamides; Time Factors; Tumor Cells, Cultured