HEF1 is a crucial mediator of the proliferative effects of prostaglandin E(2) on colon cancer cells

Prdx1 promotes the loss of primary cilia in esophageal squamous cell carcinoma

Background

Loss of primary cilia is frequently observed in tumor cells, suggesting that the absence of this organelle may promote tumorigenesis through aberrant signal transduction, the inability to exit the cell cycle, and promotion of tumor cell invasion. Primary cilia loss also occurs in esophageal squamous cell carcinoma (ESCC) cells, but the molecular mechanisms that explain how ESCC cells lose primary cilia remain poorly understood.

Methods

Inhibiting the expression of Prdx1 in the ESCC cells to detect the up-regulated genes related to cilium regeneration and down-regulated genes related to cilium disassembly by Gene chip. And, mice and cell experiments were carried to confirm the role of the HEF1-Aurora A-HDAC6 signaling axis in ESCC.

Results

In this study, we found that silencing Peroxiredoxin 1 (Prdx1) restores primary cilia formation, and over-expressing Prdx1 induces primary cilia loss in ESCC cells. We also showed that the expression of Prdx1 regulates the action of the HEF1-Aurora A-HDAC6 signaling axis to promote the disassembly of primary cilia, and suppression of Prdx1 results in decreased tumor formation and tumor mass volume in vivo.

Conclusions

These results suggest that Prdx1 is a novel regulator of primary cilia formation in ESCC cells.

Cyclooxygenase 2-Regulated Genes an Alternative Avenue to the Development of New Therapeutic Drugs for Colorectal Cancer

Colorectal cancer (CRC) is one of the most common and recurrent types of cancer, with high mortality rates. Several clinical trials and meta-analyses have determined that the use of pharmacological inhibitors of cyclooxygenase 2 (COX-2), the enzyme that catalyses the rate-limiting step in the synthesis of prostaglandins (PG) from arachidonic acid, can reduce the incidence of CRC as well as the risk of recurrence of this disease, when used together with commonly used chemotherapeutic agents. These observations suggest that inhibition of COX-2 may be useful in the treatment of CRC, although the current drugs targeting COX-2 are not widely used since they increase the risk of health complications. To overcome this difficulty, a possibility is to identify genes regulated by COX-2 activity that could give an advantage to the cells to form tumors and/or metastasize. The modulation of those genes as effectors of COX-2 may cancel the beneficial effects of COX-2 in tumor transformation and metastasis. A review of the available databases and literature and our own data have identified some interesting molecules induced by prostaglandins or COX-2 that have been also described to play a role in colon cancer, being thus potential pharmacological targets in colon cancer. Among those mPGES-1, DUSP4, and 10, Programmed cell death 4, Trop2, and many from the TGFβ and p53 pathways have been identified as genes upregulated in response to COX-2 overexpression or PGs in colon carcinoma lines and overexpressed in colon tumor tissue. Here, we review the available evidence of the potential roles of those molecules in colon cancer in the context of PG/COX signaling pathways that could be critical mediators of some of the tumor growth and metastasis advantage induced by COX-2. At the end, this may allow defining new therapeutic targets/drugs against CRC that could act specifically against tumor cells and would be effective in the prevention and treatment of CRC, lacking the unwanted side effects of COX-2 pharmacological inhibitors, providing alternative approaches in colon cancer.

E-cadherin and NEDD9 expression in primary colorectal cancer, metastatic lymph nodes and liver metastases

In Croatia, colorectal cancer mortality rates in males are the third highest in Europe, after Hungary and Slovakia. The results for females rank Croatia in second place after Hungary. According to previous studies, the loss of E-cadherin expression and the higher expression of neural precursor cell-expressed developmentally downregulated 9 (NEDD9) are associated with a worse prognosis. The aim of the present study was to analyze the immunohistochemical expression of NEDD9 and E-cadherin as markers of metastatic potential using a tissue microarray. This retrospective study included 40 previously untreated patients, including 23 males and 17 females with a median age of 64.5 years (range 38–84), with colorectal cancer and synchronous liver metastases that underwent simultaneous colorectal and hepatic resection between January 1st 2006 and December 31st 2013, in the Clinical Hospital Center Sestre Milosrdnice (Zagreb, Croatia). The most frequent tumor stage was T3, while the most frequent nodal stage was N1. Microvascular invasion was present in 37.5% of patients, while perineural invasion was observed in 30% of patients. The immunohistochemical staining index of E-cadherin was highly positive in 87.5% samples of colorectal cancer, 67.7% of lymph nodes and 77.5% of liver metastases. In the primary tumor, highly positive NEDD9 expression was identified in 22.5% of patients. In lymph nodes, it was identified in 35.5% of patients, while in the liver, it was identified in 30% of patients. Significant positive correlations were observed between the percentage of positive lymph nodes and the immunohistochemical staining index of E-cadherin (ρ=0.372; P=0.039) and NEDD9 (ρ=0.451; P=0.011) in lymph nodes. After the conclusion of the study, 55% of the patients succumbed. No significant differences in survival rates were identified regarding the expression of E-cadherin and NEDD9 in the primary tumor, metastatic lymph nodes and liver metastases. Due to the small sample size and the negative results obtained, further research is required to implement these parameters as prognostic factors.

Identification of key genes in colorectal cancer using random walk with restart

As the most common type of cancer and the second leading cause of cancer-associated mortality, colorectal cancer (CRC) has received increasing attention. The aim of the present study was to investigate the mechanisms of CRC by analyzing the microarray dataset, GSE32323. The GSE32323 dataset was downloaded from the Gene Expression Omnibus, and included 17 pairs of matched cancer and normal colorectal tissue samples. The differentially expressed genes (DEGs) were screened using the Linear Models for Microarray Data package and a search of CRC genes, also denoted as seed genes, was performed using the Online Mendelian Inheritance in Man database. Subsequently, the protein‑protein interaction (PPI) network was downloaded from the Search Tool for the Retrieval of Interacting Genes database and the sub‑network (CRC.PPI) of the DEGs and seed genes were obtained. In addition, the top 50 nodes with highest affinity scores in the CRC.PPI were identified using random walk with restart analysis. The potential functions of the DEGs included in the top 50 nodes were analyzed using the Database for Annotation, Visualization and Integrated Discovery online tool. Using the Drug Gene Interaction database, drug‑gene interaction analysis was performed to identify antineoplastic drug interacts with genes. A total of 1,640 DEGs between the CRC and normal samples were screened. The obtained seed genes included cyclin D1 (CCND1) and aurora kinase A (AURKA). The enriched functions for the 31 DEGs in the PPI network of the top 50 nodes were predominantly associated with cell cycle. The DEGs may function in CRC by interacting with other genes in the PPI network of the top 50 nodes, for example, DEP domain‑containing MTOR‑interacting protein (DEPTOR)‑CCND1, AURKA‑breast carcinoma amplified sequence‑1 (BCAS1), CCND1‑BCAS1, CCND1‑neural precursor cell expressed developmentally downregulated 9 (NEDD9) and CCND1‑mitogen‑activated protein kinase kinase 2 (MAP2K2). Only three DEGs (CCND1, AURKA and DEPTOR) had interactions with their corresponding antineoplastic drugs. Taken together, DEPTOR, AURKA, CCND1, BCAS1, NEDD9 and MAP2K2 may act in CRC.

Downregulation of NEDD9 by apigenin suppresses migration, invasion, and metastasis of colorectal cancer cells

Apigenin is a natural flavonoid which possesses multiple anti-cancer properties such as anti-proliferation, anti-inflammation, and anti-metastasis in many types of cancers including colorectal cancer. Neural precursor cell expressed developmentally downregulated 9 (NEDD9) is a multi-domain scaffolding protein of the Cas family which has been shown to correlate with cancer metastasis and progression. The present study investigates the role of NEDD9 in apigenin-inhibited cell migration, invasion, and metastasis of colorectal adenocarcinoma DLD1 and SW480 cells. The results show that knockdown of NEDD9 inhibited cell migration, invasion, and metastasis and that overexpression of NEDD9 promoted cell migration and invasion of DLD1 cells and SW4890 cells. Apigenin treatment attenuated NEDD9 expression at protein level, resulting in reduced phosphorylations of FAK, Src, and Akt, leading to inhibition on cell migration, invasion, and metastasis of both DLD1 and SW480 cells. The present study has demonstrated that apigenin inhibits cell migration, invasion, and metastasis through NEDD9/Src/Akt cascade in colorectal cancer cells. NEDD9 may function as a biomarker for evaluation of cancer aggressiveness and for selection of therapeutic drugs against cancer progression.

Prostaglandin E2 promotes proliferation of skeletal muscle myoblasts via EP4 receptor activation

We recently demonstrated that conditioned media (CM) from osteocytes enhances myogenic differentiation of myoblasts, suggesting that signaling from bone may be important for skeletal muscle myogenesis. The effect of CM was closely mimicked by prostaglandin E₂ (PGE₂), a bioactive lipid mediator in various physiological or pathological conditions. PGE₂ is secreted at high levels by osteocytes and such secretion is further enhanced under loading conditions. Although four types of receptors, EP1 to EP4, mediate PGE₂ signaling, it is unknown whether these receptors play a role in myogenesis. Therefore, in this study, the expression of EPs in mouse primary myoblasts was characterized, followed by examination of their roles in myoblast proliferation by treating myoblasts with PGE₂ or specific agonists. All four PGE₂ receptor mRNAs were detectable by quantitative real-time PCR (qPCR), but only PGE₂ and EP4 agonist CAY 10598 significantly enhance myoblast proliferation. EP1/EP3 agonist 17-phenyl trinor PGE₂ (17-PT PGE₂) and EP2 agonist butaprost did not have any significant effects. Moreover, treatment with EP4 antagonist L161,982 dose-dependently inhibited myoblast proliferation. These results were confirmed by cell cycle analysis and the gene expression of cell cycle regulators. Concomitant with the inhibition of myoblast proliferation, treatment with L161,982 significantly increased intracellular reactive oxygen species (ROS) levels. Cotreatment with antioxidant N-acetyl cysteine (NAC) or sodium ascorbate (SA) successfully reversed the inhibition of myoblast proliferation and ROS overproduction caused by L161,982. Therefore, PGE₂ signaling via the EP4 receptor regulates myogenesis by promoting myoblast proliferation and blocking this receptor results in increased ROS production in myoblasts.

High expression of HEF1 predicts a poorer prognosis of hepatocellular carcinoma: A retrospective study

Human enhancer of filamentation 1 (HEF1), a scaffold protein, is highly expressed in a variety of cancer types and is involved cancer cell growth, migration and invasion. The prognostic value of HEF1 in hepatocellular carcinoma (HCC) remains to be elucidated. The aim of the present study was to assess the association between the expression of HEF1, the clinical/pathological parameters and survival in HCC. In the present study, immunohistochemistry was performed to investigate the protein expression of HEF1 in 123 hepatocellular carcinoma tissues and their adjacent normal liver tissues. Spearman's rank correlation, Kaplan-Meier plots and Cox regression model were used to analyze the data. Overexpression of HEF1 protein was observed in HCC tissue when compared with their adjacent non-malignant liver tissue. High expression of HEF1 correlated with higher advanced tumor, node, metastasis (TNM) stage and vascular invasion (P<0.05). In univariate and multivariate analysis, the expression of HEF1 was identified as an independent prognostic factor in the 123 patients with HCC. In subgroup analysis, high expression of HEF1 correlated with a poorer prognosis in advanced (TNM III+IV) stages (P<0.05). These findings demonstrated the potential value of detecting the expression of HEF1 by immunohistochemistry as a prognostic biomarker and therapeutic target for patients with HCC.

Upregulated PFTK1 promotes tumor cell proliferation, migration, and invasion in breast cancer

PFTK1 was a cell division cycle 2-related serine/threonine protein kinase, which was up-regulated in breast cancer tissues and breast cancer lines. And up-regulated PFTK1 was highly associated with grade, axillary lymph node status, and Ki-67. Moreover, Kaplan-Meier curve showed that up-regulated PFTK1 was related to the poor breast carcinoma patients' overall survival. Here, we first discovered and confirmed that cyclin B was a new interacting protein of PFTK1, and the complex might increase the amount of DVL2, which triggers Wnt/β-catenin signaling pathway. Furthermore, knockdown of PFTK1 attenuated cell proliferation, anchorage-independent cell growth, and cell migration and invasion by inhibiting the transcriptional activation of β-catenin for cyclin D1, MMP9, and HEF1, whereas exogenous expression of PFTK1 might promote MDA-MB-231 cells proliferation, migration, and invasion via promoting PFTK1-DVL2-β-catenin axis. Our findings supported the notion that up-regulated PFTK1 might promote breast cancer progression and metastasis by activating Wnt signaling pathway through the PFTK1-DVL2-β-catenin axis.

Preclinical and clinical studies of the NEDD9 scaffold protein in cancer and other diseases

Cancer progression requires a significant reprogramming of cellular signaling to support the essential tumor-specific processes that include hyperproliferation, invasion (for solid tumors) and survival of metastatic colonies. NEDD9 (also known as CasL and HEF1) encodes a multi-domain scaffolding protein that assembles signaling complexes regulating multiple cellular processes relevant to cancer. These include responsiveness to signals emanating from the T and B cell receptors, integrins, chemokine receptors, and receptor tyrosine kinases, as well as cytoplasmic oncogenes such as BCR-ABL and FAK- and SRC-family kinases. Downstream, NEDD9 regulation of partners including CRKL, WAVE, PI3K/AKT, ERK, E-cadherin, Aurora-A (AURKA), HDAC6, and others allow NEDD9 to influence functions as pleiotropic as migration, invasion, survival, ciliary resorption, and mitosis. In this review, we summarize a growing body of preclinical and clinical data that indicate that while NEDD9 is itself non-oncogenic, changes in expression of NEDD9 (most commonly elevation of expression) are common features of tumors, and directly impact tumor aggressiveness, metastasis, and response to at least some targeted agents inhibiting NEDD9-interacting proteins. These data strongly support the relevance of further development of NEDD9 as a biomarker for therapeutic resistance. Finally, we briefly discuss emerging evidence supporting involvement of NEDD9 in additional pathological conditions, including stroke and polycystic kidney disease.

Adaptors for disorders of the brain? The cancer signaling proteins NEDD9, CASS4, and PTK2B in Alzheimer's disease

No treatment strategies effectively limit the progression of Alzheimer's disease (AD), a common and debilitating neurodegenerative disorder. The absence of viable treatment options reflects the fact that the pathophysiology and genotypic causes of the disease are not well understood. The advent of genome-wide association studies (GWAS) has made it possible to broadly investigate genotypic alterations driving phenotypic occurrences. Recent studies have associated single nucleotide polymorphisms (SNPs) in two paralogous scaffolding proteins, NEDD9 and CASS4, and the kinase PTK2B, with susceptibility to late-onset AD (LOAD). Intriguingly, NEDD9, CASS4, and PTK2B have been much studied as interacting partners regulating oncogenesis and metastasis, and all three are known to be active in the brain during development and in cancer. However, to date, the majority of studies of these proteins have emphasized their roles in the directly cancer relevant processes of migration and survival signaling. We here discuss evidence for roles of NEDD9, CASS4 and PTK2B in additional processes, including hypoxia, vascular changes, inflammation, microtubule stabilization and calcium signaling, as potentially relevant to the pathogenesis of LOAD. Reciprocally, these functions can better inform our understanding of the action of NEDD9, CASS4 and PTK2B in cancer.

High expression of HEF1 is associated with poor prognosis in urinary bladder carcinoma

Human enhancer of filamentation 1 (HEF1) is a multidomain scaffolding protein that has been thought to play an important role in the tumor progression of various cancers. HEF1 expression has not previously been reported in urinary bladder carcinoma, and little is known about its prognostic significance. The aim of this study was to evaluate the expression patterns of HEF1 in urinary bladder carcinoma and to investigate its prognostic significance. HEF1 expression was analyzed by immunohistochemistry using tissue microarray. A significant relationship between HEF1 expression and sex, tumor size, number of tumors, invasion depth, lymph node metastasis, and distant metastasis was found, and high expression of HEF1 was associated with worse overall survival when compared to low expression of HEF1. Multivariate analysis showed that HEF1 expression was an independent prognostic factor for overall survival in urinary bladder carcinoma. We investigated HEF1 expression in urinary bladder carcinoma and found that high HEF1 expression was associated with advanced stage, large tumor size, and shortened progression-free survival. Although the biologic function of HEF1 in urinary bladder carcinoma remains unknown, the expression of HEF1 can provide new prognostic information for disease progression.

NEDD9 overexpression correlates with poor prognosis in gastric cancer

In this study, the expression of neural precursor cell expressed developmentally downregulated 9 (NEDD9) in benign and malignant gastric tissues was investigated, and the significance of NEDD9 in gastric cancer prognosis was explored. Immunohistochemistry was used to detect NEDD9 expression in gastric cancer, nontumor gastric, and normal gastric tissues. The relationship between NEDD9 expression in gastric cancer tissues and the clinicopathologic factors was examined using the Mann-Whitney U test. The two factors between NEDD9 expression and tumor node metastasis (TNM) stage in gastric cancer patients were analyzed by Spearman rank correlation analysis. The Kaplan-Meier method and log-rank test were used to compare the overall survival of NEDD9 negative, weak positive expression, and strong positive expression group. NEDD9 expression rates were significantly higher (P < 0.001) in gastric cancer tissues (162 out of 187, 86.6 %) compared with normal (2 out of 11, 18.2 %) and nontumor (11 out of 58, 19.0 %) gastric tissues. The upregulated NEDD9 expression in gastric cancer tissue was significantly correlated with high preoperative CEA level (P = 0.044), poor differentiation (P = 0.007), tissue invasion (P = 0.015), present lymph node metastasis (P < 0.001), and high TNM stage (P < 0.001). NEDD9 expression was positively correlated with clinical TNM stage. Advancing clinical TNM stage corresponded with higher NEDD9 expression (r s = 0.289, P < 0.001). The overall 5-year survival of gastric cancer patients with strong positive NEDD9 expression was significantly shorter compared with the survival of NEDD9 negative and weakly positive expression group. NEDD9 may be used as a biomarker in the clinical setting to predict the prognosis of gastric cancer patients.

KIF3a promotes proliferation and invasion via Wnt signaling in advanced prostate cancer

Aberrant activation of the Wnt/β-catenin signaling pathway is a critical event in advanced prostate cancer, but the genetic alterations that activate the Wnt signaling pathway in many other cancers are rarely observed in prostate cancer. Other molecular mechanisms that regulate the Wnt signaling pathway in prostate cancer remain to be identified. Here, it is demonstrated that KIF3a, a subunit of kinesin-II motor protein, functions as an agonist of the Wnt signaling pathway in prostate cancer. KIF3a is upregulated in the majority of human prostate cancer cell lines and primary tumor biopsies. The expression levels of KIF3a correlate with a higher Gleason score, tumor-node-metastasis stage, and metastatic status of prostate cancer. Moreover, exogenous expression of KIF3a promoted cell growth in the benign prostate cells, whereas silencing KIF3a in cancer cells decreased cell proliferation, anchorage-independent cell growth, and cell migration/invasion. Mechanistically, KIF3a increases CK1-dependent DVL2 phosphorylation and β-catenin activation in prostate cancer cells, leading to transactivation of the Wnt-signaling target genes such as cyclin D1, HEF1, and MMP9. These findings support the notion that upregulation of KIF3a is causal of aberrant activation of Wnt signaling in advanced prostate cancer through the KIF3a-DVL2-β-catenin axis.

IMPLICATIONS

Inactivation of KIF3a may improve survival of patients with advanced prostate cancer in which Wnt signaling is activated.

NEDD9 overexpression is associated with the progression of and an unfavorable prognosis in epithelial ovarian cancer

Neural precursor cell-expressed, developmentally down-regulated 9 (NEDD9), a scaffolding protein, has been identified as a prometastatic and poor prognostic gene in multiple malignant tumors. However, the potential role of the NEDD9 protein in epithelial ovarian cancer (EOC) remains unclear. In the present study, we investigated the expression of NEDD9 and the correlation between NEDD9 expression and prognosis in EOC. NEDD9 expression was detected in 129 archived EOC specimens by immunohistochemical staining and in 28 freshly frozen EOC specimens by Western blotting. The expression of NEDD9 was evaluated in ovarian cancer cell lines by Western blotting and immunofluorescence. The association between the expression of NEDD9 and prognosis was determined by survival analysis. Results suggested that NEDD9 was overexpressed in EOC specimens compared with noninvasive epithelial ovarian tumors and normal ovarian specimens. A high level of NEDD9 expression significantly correlated with advanced-stage tumors (International Federation of Gynecology and Obstetrics classes III-IV, P < .001), high-grade carcinoma (grades 2-3, P < .001), and suboptimal primary cytoreductive surgery (residual disease <1cm, P = .021). The expression level of NEDD9 varied in ovarian cancer cell lines. Multivariate analysis indicated that NEDD9 overexpression (P = .033), advanced stage (P < .001), and high-grade carcinoma (P = .01) were independent predictors of poor survival. In conclusion, NEDD9 is overexpressed and associated with an unfavorable prognosis in EOC. NEDD9 overexpression is an independent factor of poor prognosis and may serve as a potential biomarker in EOC.

HEF1 promotes epithelial mesenchymal transition and bone invasion in prostate cancer under the regulation of microRNA-145

The principal problem arising from prostate cancer (PCa) is its propensity to metastasize to bones, and it's crucial to understand the mechanism of tumor progression to metastasis in order to develop therapies that may reduce the morbidity and mortality of PCa patients. Although we had identified that microRNA(miR)-145 could repress bone metastasis of PCa via regulating epithelial-mesenchymal transition (EMT) in previous study, it is still unknown how miR-145 regulated EMT. In the present study, we constructed a luciferase reporter system and identified HEF1 as a direct target of miR-145. More importantly, HEF1 was shown to promote migration, invasion and EMT of PC-3 cells, a human PCa cell line originated from a bone metastatic PCa specimen. And HEF1 was also shown to partially mediate miR-145 suppression of EMT and invasion. Furthermore, inhibition of HEF1 repressed bone invasion of PC-3 cells in vivo. Expression of HEF1 was negatively correlated with miR-145 in primary PCa and bone metastatic specimens, but HEF1 was higher in samples which were more likely to commit to bone metastasis or those with higher free prostate-specific antigen (fPSA) levels and Gleason scores. Taken together, these findings indicate that HEF1 promotes EMT and bone invasion in prostate cancer by directly targeted by miR-145, and miR-145 suppresses EMT and invasion, at least in part, through repressing HEF1.

Impact of the integrin signaling adaptor protein NEDD9 on prognosis and metastatic behavior of human lung cancer

PURPOSE

In a substantial population of non-small cell lung cancer (NSCLC), expression and activation of EGF receptor (EGFR) have been reported and is regarded as a novel molecular target. A growing body of evidence has shown the signaling crosstalk between EGFR and integrins in cellular migration and invasion. NEDD9 is an integrin signaling adaptor protein composed of multiple domains serving as substrate for a variety of tyrosine kinases. In the present study, we aimed at elucidating a role of NEDD9 in the signaling crosstalk between EGFR and integrins.

EXPERIMENTAL DESIGN

Using NSCLC cell lines, we conducted immunoblotting and cellular migration/invasion assay in vitro. Next, we analyzed metastasis assays in vivo by the use of xenograft transplantation model. Finally, we retrospectively evaluated clinical samples and records of patients with NSCLCs.

RESULTS

We showed that tyrosine phosphorylation of NEDD9 was reduced by the inhibition of EGFR in NSCLC cell lines. Overexpression of constitutively active EGFR caused tyrosine phosphorylation of NEDD9 in the absence of integrin stimulation. By gene transfer and gene knockdown, we showed that NEDD9 plays a pivotal role in cell migration and invasion of those cells in vitro. Furthermore, overexpression of NEDD9 promoted lung metastasis of an NSCLC cell line in NOD/Shi-scid, IL-2Rγ(null) mice (NOG) mice. Finally, univariate and multivariate Cox model analysis of NSCLC clinical specimens revealed a strong correlation between NEDD9 expression and recurrence-free survival as well as overall survival.

CONCLUSION

Our data thus suggest that NEDD9 is a promising biomarker for the prognosis of NSCLCs and its expression can promote NSCLC metastasis.

Eicosanoid signalling pathways in the development and progression of colorectal cancer: novel approaches for prevention/intervention

Arachidonic acid metabolism through cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P-450 epoxygenase (EPOX) pathways leads to the generation of biologically active eicosanoids, including prostanoids, leukotrienes, hydroxyeicosatetraenoic acid, epoxyeicosatrienoic acid and hydroperoxyeicosatetraenoic acids. Eicosanoid expression levels vary during tumor development and progression of a range of malignancies, including colorectal cancer. The actions of these autocoids are also directly influenced by diet, as demonstrated by recent evidence for omega-3 fatty acids in colorectal cancer (CRC) prevention and/or treatment. Eicosanoids regulate CRC development and progression, while inhibition of these pathways has generally been shown to inhibit tumor growth/progression. A progressive sequence of colorectal cancer development has been identified, ranging from normal colon, to colitis, dysplasia, and carcinoma. While both COX and LOX inhibition are both promising candidates for colorectal cancer prevention and/or treatment, there is an urgent need to understand the mechanisms through which these signalling pathways mediate their effects on tumorigenesis. This will allow identification of safer, more effective strategies for colorectal cancer prevention and/or treatment. In particular, binding to/signalling through prostanoid receptors have recently been the subject of considerable interest in this area. In this review, we discuss the role of the eicosanoid signalling pathways in the development and progression of colorectal cancer. We discuss the effects of the eicosanoids on tumor cell proliferation, their roles in cell death induction, effects on angiogenesis, migration, invasion and their regulation of the immune response. Signal transduction pathways involved in these processes are also discussed. Finally, novel approaches targeting these arachidonic acid-derived eicosanoids (using pharmacological or natural agents) for chemoprevention and/or treatment of colorectal cancer are outlined.

Histone deacetylase inhibition in colorectal cancer cells reveals competing roles for members of the oncogenic miR-17-92 cluster

Diet-derived butyrate, a histone deacetylase inhibitor (HDI), decreases proliferation and increases apoptosis in colorectal cancer (CRC) cells via epigenetic changes in gene expression. Other HDIs such as suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA) have similar effects. This study examined the role of microRNAs (miRNAs) in mediating the chemo-protective effects of HDIs, and explored functions of the oncogenic miR-17-92 cluster. The dysregulated miRNA expression observed in HT29 and HCT116 CRC cells could be epigenetically altered by butyrate, SAHA and TSA. These HDIs decreased expression of miR-17-92 cluster miRNAs (P < 0.05), with a corresponding increase in miR-17-92 target genes, including PTEN, BCL2L11, and CDKN1A (P < 0.05). The decrease in miR-17-92 expression may be partly responsible for the anti-proliferative effects of HDIs, with introduction of miR-17-92 cluster miRNA mimics reversing this effect and decreasing levels of PTEN, BCL2L11, and CDKN1A (P < 0.05). The growth effects of HDIs may be mediated by changes in miRNA activity, with down-regulation of the miR-17-92 cluster a plausible mechanism to explain some of the chemo-protective effects of HDIs. Of the miR-17-92 cluster miRNAs, miR-19a and miR-19b were primarily responsible for promoting proliferation, while miR-18a acted in opposition to other cluster members to decrease growth. NEDD9 and CDK19 were identified as novel miR-18a targets and were shown to be pro-proliferative genes, with RNA interference of their transcripts decreasing proliferation in CRC cells. This is the first study to identify competing roles for miR-17-92 cluster members, in the context of HDI-induced changes in CRC cells.

NEDD9 is a positive regulator of epithelial-mesenchymal transition and promotes invasion in aggressive breast cancer

Epithelial to mesenchymal transition (EMT) plays an important role in many biological processes. The latest studies revealed that aggressive breast cancer, especially the triple-negative breast cancer (TNBC) subtype was frequently associated with apparent EMT, but the mechanisms are still unclear. NEDD9/HEF1/Cas-L is a member of the Cas protein family and was identified as a metastasis marker in multiple cancer types. In this study, we wished to discern the role of NEDD9 in breast cancer progression and to investigate the molecular mechanism by which NEDD9 regulates EMT and promotes invasion in triple-negative breast cancer. We showed that expression of NEDD9 was frequently upregulated in TNBC cell lines, and in aggressive breast tumors, especially in TNBC subtype. Knockdown of endogenous NEDD9 reduced the migration, invasion and proliferation of TNBC cells. Moreover, ectopic overexpression of NEDD9 in mammary epithelial cells led to a string of events including the trigger of EMT, activation of ERK signaling, increase of several EMT-inducing transcription factors and promotion of their interactions with the E-cadherin promoter. Data presented in this report contribute to the understanding of the mechanisms by which NEDD9 promotes EMT, and provide useful clues to the evaluation of the potential of NEDD9 as a responsive molecular target for TNBC chemotherapy.

HEF1, a novel target of Wnt signaling, promotes colonic cell migration and cancer progression

Misregulation of the canonical Wnt/β-catenin pathway and aberrant activation of Wnt signaling target genes are common in colorectal cancer (CRC) and contribute to cancer progression. Altered expression of human enhancer of filamentation 1 (HEF1; also known as NEDD9 or Cas-L) has been implicated in progression of melanoma, breast, and CRC. However, the regulation of HEF1 and the role of HEF1 in CRC tumorigenesis are not fully understood. We here identify HEF1 as a novel Wnt signaling target. The expression of HEF1 was upregulated by Wnt-3a, β-catenin, and Dvl2 in a dose-dependent manner, and was suppressed following β-catenin downregulation by shRNA. In addition, elevated HEF1 mRNA and protein levels were observed in CRC cell lines and primary tumor tissues, as well as in the colon and adenoma polyps of Apc(Min/+) mice. Moreover, HEF1 levels in human colorectal tumor tissues increased with the tumor grade. Chromatin immunoprecipitation (ChIP) assays and promoter analyses revealed three functional T-cell factor (TCF)-binding sites in the promoter of HEF1 responsible for HEF1 induction by Wnt signaling. Ectopic expression of HEF1 increased cell proliferation and colony formation, while downregulation of HEF1 in SW480 cells by shRNA had the opposite effects and inhibited the xenograft tumor growth. Furthermore, overexpression of HEF1 in SW480 cells promoted cell migration and invasion. Together, our results determined a novel role of HEF1 as a mediator of the canonical Wnt/β-catenin signaling pathway for cell proliferation, migration, and tumorigenesis, as well as an important player in colorectal tumorigenesis and progression. HEF1 may represent an attractive candidate for drug targeting in CRC.

Human enhancer of filamentation 1 Is a mediator of hypoxia-inducible factor-1alpha-mediated migration in colorectal carcinoma cells

Human enhancer of filamentation 1 (HEF1; also known as NEDD9 or Cas-L) is a scaffolding protein that is implicated in regulating diverse cellular processes, such as cellular attachment, motility, cell cycle progression, apoptosis, and inflammation. Here, we identify HEF1 as a novel hypoxia-inducible factor-1alpha (HIF-1alpha)-regulated gene and reveal that HEF1 mediates hypoxia-induced migration of colorectal carcinoma cells. HEF1 is highly expressed in cultured colorectal carcinoma cells exposed to hypoxia and in the hypoxic areas of human colorectal cancer (CRC) specimens. Moreover, our data show that HIF-1alpha mediates the effects of hypoxia on induction of HEF1 expression via binding to a hypoxia-responsive element of the HEF1 promoter. Importantly, the induction of HEF1 expression significantly enhances hypoxia-stimulated HIF-1alpha transcriptional activity by modulating the interaction between HIF-1alpha and its transcriptional cofactor p300. Inhibition of HEF1 expression also reduced the levels of hypoxia-inducible genes, including those that regulate cell motility. Cell migration was reduced dramatically following knockdown of HEF1 expression under hypoxic conditions. Thus, this positive feedback loop may contribute to adaptive responses of carcinoma cells encountering hypoxia during cancer progression.