A high level of integrin α6 expression in human intrahepatic cholangiocarcinoma cells is associated with a migratory and invasive phenotype

Heterogeneity of Cholangiocarcinoma Immune Biology

Cholangiocarcinomas (CCAs) are aggressive tumors arising along the biliary tract epithelium, whose incidence and mortality are increasing. CCAs are highly desmoplastic cancers characterized by a dense tumor microenvironment (TME), in which each single component plays a fundamental role in shaping CCA initiation, progression and resistance to therapies. The crosstalk between cancer cells and TME can affect the recruitment, infiltration and differentiation of immune cells. According to the stage of the disease and to intra- and inter-patient heterogeneity, TME may contribute to either protumoral or antitumoral activities. Therefore, a better understanding of the effect of each immune cell subtype may open the path to new personalized immune therapeutic strategies for the management of CCA. In this review, we describe the role of immune cells in CCA initiation and progression, and their crosstalk with both cancer-associated fibroblasts (CAFs) and the cancer-stem-cell-like (CSC) niche.

Integrin alpha 6 is upregulated and drives hepatocellular carcinoma progression through integrin α6β4 complex

Integrin α6 (ITGA6) forms integrin receptors with either integrin β1 (ITGB1) or integrin β4 (ITGB4). How it functions to regulate hepatocellular carcinoma (HCC) progression is not well-elucidated. We found that ITGA6 RNA and protein expression levels are significantly elevated in human HCC tissues in comparison with paired adjacent nontumor tissues by RNA sequencing, RT-qPCR, Western blotting and immunofluorescence staining. Stable knockdown of ITGA6 with different ITGA6 shRNA expression lentivectors significantly inhibited proliferation, migration and anchorage-independent growth of HCC cell lines in vitro, and xenograft tumor growth in vivo. The inhibition of anchorage-dependent and -independent growth of HCC cell lines was also confirmed with anti-ITGA6 antibody. ITGA6 knockdown was shown to induce cell-cycle arrest at G0/G1 phase. Immunoprecipitation assay revealed apparent interaction of ITGA6 with ITGB4, but not ITGB1. Expression studies showed that ITGA6 positively regulates the expression of ITGB4 with no or negative regulation of ITGB1 expression. Finally, while high levels of ITGA6 and ITGB4 together were associated with significantly worse survival of HCC patients in TCGA data set, the association was not significant for high levels of ITGA6 and ITGB1. In conclusion, ITGA6 is upregulated in HCC tumors and has a malignant promoting role in HCC cells through integrin α6β4 complex. Thus, integrin α6β4 may be a therapeutic target for treating patients with HCC.

ITGB6-Knockout Suppresses Cholangiocarcinoma Cell Migration and Invasion with Declining PODXL2 Expression

Intrahepatic cholangiocarcinoma (iCCA) is a heterogeneous bile duct cancer with a poor prognosis. Integrin αvβ6 (β6) has been shown to be upregulated in iCCA and is associated with its subclassification and clinicopathological features. In the present study, two ITGB6-knockout HuCCT1 CCA cell lines (ITGB6-ko cells) were established using the clustered regulatory interspaced short palindromic repeats (CRISPR), an associated nuclease 9 (Cas9) system, and single-cell cloning. RNA sequencing analysis, real-time polymerase chain reaction (PCR), and immunofluorescent methods were applied to explore possible downstream factors. ITGB6-ko cells showed significantly decreased expression of integrin β6 on flow cytometric analysis. Both cell lines exhibited significant inhibition of cell migration and invasion, decreased wound-healing capability, decreased colony formation ability, and cell cycle dysregulation. RNA sequencing and real-time PCR analysis revealed a remarkable decrease in podocalyxin-like protein 2 (PODXL2) expression in ITGB6-ko cells. Colocalization of PODXL2 and integrin β6 was also observed. S100 calcium-binding protein P and mucin 1, which are associated with CCA subclassification, were downregulated in ITGB6-ko cells. These results describe the successful generation of ITGB6-ko CCA cell clones with decreased migration and invasion and downregulation of PODXL2, suggesting the utility of integrin β6 as a possible therapeutic target or diagnostic marker candidate.

Role of laminin and cognate receptors in cholangiocarcinoma cell migration

Extensive desmoplasia in cholangiocarcinoma (CCA) is associated with tumor aggressiveness, indicating a need for further understanding of CCA cell-matrix interaction. This study demonstrated laminin as the most potent attractant for CCA cell migration and the vast elevation of its receptor integrin β4 (ITGB4) in CCA cell lines. Besides, their high expressions in CCA tissues were correlated with lymphatic invasion and the presence of ITGB4 was also associated with short survival time. ITGB4 silencing revealed it as the receptor for laminin-induced HuCCA-1 migration, but KKU-213 utilized 37/67-kDa laminin receptor (LAMR) instead. These findings highlight the role of ITGB4 and LAMR in transducing laminin induction of CCA cell migration and the potential of ITGB4 as diagnostic and prognostic biomarkers for CCA.

Role of Cancer Stem Cells in Cholangiocarcinoma and Therapeutic Implications

Cholangiocarcinoma (CCA) is the second most common type of liver cancer, and is highly aggressive with very poor prognosis. CCA is classified into intrahepatic cholangiocarcinoma (iCCA) and extra-hepatic cholangiocarcinoma (eCCA), which is further stratified into perihilar (pCCA) and distal (dCCA). Cancer stem cells (CSCs) are a subpopulation of cancer cells capable of tumor initiation and malignant growth, and are also responsible for chemoresistance. Thus, CSCs play an important role in CCA carcinogenesis. Surface markers such as CD133, CD24, CD44, EpCAM, Sox2, CD49f, and CD117 are important for identifying and isolating CCA CSCs. CSCs are present in the tumor microenvironment (TME), termed ‘CSC niche’, where cellular components and soluble factors interact to promote tumor initiation. Epithelial-to-mesenchymal transition (EMT) is another important mechanism underlying carcinogenesis, involved in the invasiveness, metastasis and chemoresistance of cancer. It has been demonstrated that EMT plays a critical role in generating CSCs. Therapies targeting the surface markers and signaling pathways of CCA CSCs, proteins involved in TME, and immune checkpoint proteins are currently under investigation. Therefore, this review focuses on recent studies on the roles of CSCs in CCA; the possible therapeutic strategies targeting CSCs of CCA are also discussed.

In silico analysis-based identification of the target residue of integrin α6 for metastasis inhibition of basal-like breast cancer

Metastasis causes death in breast cancer patients. To inhibit breast cancer metastasis, we focused on integrin α6, a membrane protein that contributes to cell migration and metastasis. According to in silico analysis, we identified Asp-358 as an integrin α6-specific vertebrate-conserved residue and consequently as a potential therapeutic target. Because Asp-358 is located on the surface of the β propeller domain that interacts with other molecules for integrin α6 function, we hypothesized that a peptide with the sequence around Asp-358 competitively inhibits integrin α6 complex formation. We treated basal-like breast cancer cells with the peptide and observed reductions in cell migration and metastasis. The result of the immunoprecipitation assay showed that the peptide inhibited integrin α6 complex formation. Our immunofluorescence for phosphorylated paxillin, a marker of integrin-regulated focal adhesion, showed that the peptide reduced the number of focal adhesions. These results indicate that the peptide inhibits integrin α6 function. This study identified the functional residue of integrin α6 and designed the inhibitory peptide. For breast cancer patients, metastasis inhibition therapy may be developed in the future based on this study.

Tetraspanin 1 promotes epithelial-to-mesenchymal transition and metastasis of cholangiocarcinoma via PI3K/AKT signaling

BACKGROUND

Numerous studies have demonstrated that tetraspanin 1 (TSPAN1), a transmembrane protein, functions as an oncoprotein in many cancer types. However, its role and underlying molecular mechanism in cholangiocarcinoma (CCA) progression remain unclear.

METHODS

In the present study, the expression of TSPAN1 in human CCA and adjacent nontumor tissues was examined using real-time PCR, western blot and immunohistochemistry. The effect of TSPAN1 on proliferation and metastasis was evaluated by functional assays both in vitro and in vivo. A luciferase reporter assay was performed to investigate the interaction between microRNA-194-5p (miR-194-5p) and TSPAN1 3'-untranslated region. Co-immunoprecipitation (co-IP) was used to confirm the interaction between TSPAN1 protein and integrin α6β1 and western blot was used to explore TSPAN1 mechanism.

RESULTS

We found that TSPAN1 was frequently upregulated in CCA and high levels of TSPAN1 correlated with TNM stage, especially metastasis in CCA. TSPAN1 overexpression promoted CCA growth, metastasis, and induced epithelial-to-mesenchymal transition (EMT), while its silencing had the opposite effect both in vitro and in vivo. To explore the differential expression of TSPAN1, we screened miR-194-5p as the upstream regulator of TSPAN1. A combination of high-level TSPAN1 and low-level miR-194-5p predicted poor prognosis in patients with CCA. Furthermore, in accordance with the functional characteristics of the TSPAN superfamily, we proved that TSPAN1 interacted with integrin α6β1 to amplify the phosphoinositide-3-kinase (PI3K)/AKT/glycogen synthase kinase (GSK)-3β/Snail family transcriptional repressor (Snail)/phosphatase and tensin homolog (PTEN) feedback loop.

CONCLUSION

The results indicate that TSPAN1 could be a potential therapeutic target for CCA.

Targeting the PI3K/AKT/mTOR pathway in biliary tract cancers: A review of current evidences and future perspectives

Biliary tract cancers (BTCs) are a group of invasive neoplasms, with increasing incidence and dismal prognosis. In advanced disease, the standard of care is represented by first-line chemotherapy with cisplatin and gemcitabine. In subsequent lines, no clear recommendations are currently available, highlighting the need for novel therapeutic approaches. The PI3K/AKT/mTOR pathway is a core regulator of cell metabolism, growth and survival, and is involved in BTCs carcinogenesis and progression. Mutations, gene copy number alterations and aberrant protein phosphorylation of PI3K, AKT, mTOR and PTEN have been thoroughly described in BTCs and correlate with poor survival outcomes. Several pre-clinical evidences state the efficacy of PI3K/AKT/mTOR pathway inhibitors in BTCs, both in vitro and in vivo. In the clinical setting, initial studies with rapamycin analogs have shown interesting activity with an acceptable toxicity profile. Novel strategies evaluating AKT and PI3K inhibitors have risen serious safety concerns, pointing out the need for improved patient selection and increased target specificity for the clinical development of these agents, both alone and in combination with chemotherapy. This review extensively describes the role of the PI3K/AKT/mTOR pathway in BTCs and examines the rationale of its targeting in these tumors, with particular focus on clinical activity, toxicities and perspectives on further development of PI3K/AKT/mTOR pathway inhibitors.

Identification of integrin drug targets for 17 solid tumor types

Integrins are contributors to remodeling of the extracellular matrix and cell migration. Integrins participate in the assembly of the actin cytoskeleton, regulate growth factor signaling pathways, cell proliferation, and control cell motility. In solid tumors, integrins are involved in promoting metastasis to distant sites, and angiogenesis. Integrins are a key target in cancer therapy and imaging. Integrin antagonists have proven successful in halting invasion and migration of tumors. Overexpressed integrins are prime anti-cancer drug targets. To streamline the development of specific integrin cancer therapeutics, we curated data to predict which integrin heterodimers are pausible therapeutic targets against 17 different solid tumors. Computational analysis of The Cancer Genome Atlas (TCGA) gene expression data revealed a set of integrin targets that are differentially expressed in tumors. Filtered by FPKM (Fragments Per Kilobase of transcript per Million mapped reads) expression level, overexpressed subunits were paired into heterodimeric protein targets. By comparing the RNA-seq differential expression results with immunohistochemistry (IHC) data, overexpressed integrin subunits were validated. Biologics and small molecule drug compounds against these identified overexpressed subunits and heterodimeric receptors are potential therapeutics against these cancers. In addition, high-affinity and high-specificity ligands against these integrins can serve as efficient vehicles for delivery of cancer drugs, nanotherapeutics, or imaging probes against cancer.

β4 and β6 Integrin Expression Is Associated with the Subclassification and Clinicopathological Features of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a heterogeneous group of cancers of the intrahepatic biliary tract. However, few studies have evaluated integrin expression according to an ICC subgroup. We immunohistochemically investigated α6β4 (β4) and αvβ6 (β6) integrin expressions in 48 ICCs, and evaluated their relationship with clinical and pathological parameters and ligand expression, as well as transforming growth factor (TGF)-β1. β4 and β6 expressions were detected in 46 (96%) and 35 (73%) ICC cases, respectively. We classified ICC into negative, low (β4, 29 cases; β6, 36 cases), or high (β4, 19 cases; β6, 12 cases) integrin expression groups. β4 and β6 integrin levels were higher in the non-peripheral central localization type ICC than in the peripheral localization type; they were also higher in the periductal-infiltrating or intraductal-growth types than in the mass-forming type ICC; lastly, they were higher in the well-differentiated type than in the poorly-differentiated type ICC. High expression was related to bile duct invasion. In addition, β4 and β6 expressions were associated with mucin production and the expression of cytoplasmic epithelial membrane antigen, laminin-5, and tenascin-C. TGF-β1 was correlated with β6 expression and poor overall survival. These results suggest that integrin expression is associated with subclassification and clinicopathological features of ICC through the coincident expression of their ligands and TGF-β1.

Clonorchis sinensis excretory-secretory products promote the migration and invasion of cholangiocarcinoma cells by activating the integrin β4-FAK/Src signaling pathway

Cholangiocarcinoma (CCA) is a slow-growing but highly metastatic cancer. Its metastatic potential largely explains its high mortality rate. A recognized risk factor for CCA development is infection with the liver flukes Opisthorchis viverrini and Clonorchis sinensis. We previously reported that the excretory-secretory products (ESPs) of C. sinensis promoted the three-dimensional aggregation and invasion of CCA cells. In the present study, a quantitative real-time PCR array of extracellular matrix (ECM) and adhesion molecules was used to examine the regulatory mechanism of ESP-mediated CCA cell migration and invasion. In particular, the expression levels of integrin α isoforms and β4 were upregulated in response to ESPs. Increased expression of integrin β4 was probably correlated with activation of focal adhesion kinase (FAK) and the steroid receptor coactivator (Src) family kinase and the subsequent activation of two downstream focal adhesion molecules, paxillin and vinculin. Moreover, inhibition of FAK/Src activation reduced paxillin and vinculin phosphorylation and attenuated ESP-induced CCA cell migration and invasion. These findings suggest that the integrin β4-FAK/Src signaling axis may play a crucial role in clonorchiasis-associated CCA metastasis during tumor progression.

TNF-alpha stimulation increases dental pulp stem cell migration in vitro through integrin alpha-6 subunit upregulation

OBJECTIVE

The dissemination of stem cells into tissues requiring inflammatory and reparative response is fundamentally dependent upon their chemotactic migration. Expression of TNF-α is up regulated in inflamed pulps. Dental pulp cells are also known to express integrin α6 subunit. Expression of integrin subunit α6 has been linked to the acquisition of migratory potential in a wide variety of cell types in both pathological and physiological capacities. Therefore, in this study we examined the effects of a pleiotropic cytokine TNF-α on the migration of hDPSCs and investigated its relationship with expression of integrin α6 in hDPSCs during chemotactic migration.

DESIGN

hDPSC cultures were established. Protein expression profile of α6 integrin subunit was determined. Effect of exogenous TNF-α (50ng/mL) on hDPSCs' migration potential was evaluated by transwell inserts and in vitro scratch assay. Upregulation/downregulation of TNF-α mediated migration was assayed in presence/absence of integrin α6 respectively. To suppress integrin α6 expression, cells were transfected with integrin α6 siRNA and then cell migration and cytoskeletal changes were evaluated.

RESULTS

Our results showed significant increase of hDPSCs' migration after stimulation with TNF-α. By knockdown of integrin α6, which is upregulated by TNF-α, we observed a decrease in the TNF-α directed chemotaxis of hDPSCs.

CONCLUSION

In this study, we show that activation of integrin α6 brought about by TNF-α led to an increase in migratory activity in DPSCs in vitro thus describing a novel association between a cytokine TNF-α and α6 chain of an adhesion receptor integrin in regulating migration of hDPSCs.

WAVE3 Induces EMT and Promotes Migration and Invasion in Intrahepatic Cholangiocarcinoma

BACKGROUND

Wiskott-Aldrich syndrome protein family verprolin-homologous protein 3 (WAVE3) plays a critical role in cancer progression and metastasis. However, the specific role of WAVE3 in intrahepatic cholangiocarcinoma (ICC) has not been studied.

AIMS

This study aimed to explore the role and mechanism of WAVE3 in the progression and metastasis of ICC.

METHODS

The expression of WAVE3 in ICC tissues and adjacent non-cancerous tissues was detected by immunohistochemistry. Western blot analysis was utilized to detect the expression of WAVE3 in ICC cells. A transwell assay was used to assess the potential for migration and invasion. The expression of WAVE3 in CC-LP-1 cells was knocked down by small interfering RNA (siRNA) interference.

RESULTS

The expression of WAVE3 in ICC tissues was significantly higher than that in adjacent non-cancerous tissues. The overall survival was lower in the subgroup of ICC patients with higher WAVE3 expression compared to the subgroup with a lower level of WAVE3 expression. WAVE3 expression was an adverse prognostic factor for ICC patients. CC-LP-1 cells expressed higher levels of WAVE3 protein compared to RBE cells and human intrahepatic biliary epithelial cells, which correlated with greater migration and invasion capabilities compared with the RBE cells. After the transfection of CC-LP-1 cells with WAVE3 siRNA, the level of WAVE3 protein was significantly decreased, accompanied by a marked reduction in migration, invasion and proliferation. Moreover, after the knockdown of WAVE3 expression in CC-LP-1 cells, the protein levels of Slug and Vimentin were significantly decreased, while that of E-cadherin was significantly increased.

CONCLUSIONS

WAVE3 may represent a new adverse prognostic factor for patients with ICC. This protein enhances migration and invasion capabilities in ICC, most likely through the induction of an epithelial-mesenchymal transition.

Tumor Microenvironment Versus Cancer Stem Cells in Cholangiocarcinoma: Synergistic Effects?

Cholangiocarcinoma (CCAs) may be defined as tumors that derived from the biliary tree with the differentiation in the biliary epithelial cells. This tumor is malignant, extremely aggressive with a poor prognosis. It can be treated surgically and its pathogenesis is poorly understood. The tumor microenvironment (TME) is a very important factor in the regulation of tumor angiogenesis, invasion, and metastasis. Besides cancer stem cells (CSCs) can modulate tumor growth, stroma formation, and migratory capability. The initial stage of tumorigenesis is characterized by genetic mutations and epigenetic alterations due to intrinsic factors which lead to the generation of oncogenes thus inducing tumorigenesis. CSCs may result from precancerous stem cells, cell de-differentiation, normal stem cells, or an epithelial-mesenchymal transition (EMT). CSCs have been found in the cancer niche, and EMT may occur early within the tumor microenvironment. Previous studies have demonstrated evidence of cholangiocarcinoma stem cells (CD133, CD24, EpCAM, CD44, and others) and the presence of these markers has been associated with malignant potential. The interaction between TME and cholangiocarcinoma stem cells via signaling mediators may create an environment that accommodates tumor growth, yielding resistance to cytotoxic insults (chemotherarapeutic). While progress has been made in the understanding of the mechanisms, the interactions in the tumorigenic process still remain a major challenge. Our review, addresses recent concepts of TME-CSCs interaction and will emphasize the importance of early detection with the use of novel diagnostic mechanisms such as CCA-CSC biomarkers and the importance of tumor stroma to define new treatments. J. Cell. Physiol. 231: 768-776, 2016. © 2015 Wiley Periodicals, Inc.

Integrins αvβ6, α6β4 and α3β1 are down-regulated in cholangiolocellular carcinoma but not cholangiocarcinoma

AIM

The aim of this study was to evaluate integrin expression and immunolocalization of the extracellular matrix proteins in cholangiolocellular carcinoma (CoCC).

METHODS

Tissue specimens of 23 CoCC, 28 cholangiocarcinomas (CCC), 42 hepatocellular carcinomas (HCC) and 11 classical type combined hepatocellular cholangiocarcinomas (CHC) were immunostained for β6, β4 and α3 integrins, fibronectin and laminin. ITGB6, B4 and A3 mRNA levels in six HCC cell lines, five CCC cell lines and two CHC cell lines were quantified by quantitative reverse transcription polymerase chain reaction.

RESULTS

Little or no positivity for β6, β4 and α3 integrins was shown in 91%, 91% and 52% of CoCC and 100%, 98% and 81% of HCC, respectively, according to immunostaining, whereas intense positive staining for these integrins was demonstrated in 64%, 96% and 75% of CCC, respectively. There was a close correlation between β4 and α3 integrin expression and intracytoplasmic laminin in CoCC, CCC and HCC, but not between β6 expression and its ligand, fibronectin. Integrin mRNA levels were increased in four of five CCC cell lines, but nearly undetectable in five of six HCC cell lines and one CHC cell line. Tubular differentiation of a CHC cell line cultured in collagen gel matrix induced upregulation of these integrins.

CONCLUSION

Our results first indicated downregulation of αvβ6, α6β4 and α3β1 integrins in CoCC, in contrast to its high expression in CCC, suggesting a diagnostic value of integrins in the differential diagnosis of CoCC and CCC, as well as a useful inducible marker of the intermediate features of CoCC.

Histone Demethylases in Colon Cancer

Cell growth and proliferation are controlled through different posttranslational modifications including demethylation, a process regulated by regulated by the demethylase enzymes. This review focuses on our current understanding of functional and therapeutic potentials of histone demethylases in colon cancer. Colon cancer is the third most common malignancy worldwide and the second leading cause of cancer deaths in the United States. The key protein families responsible for demethylation of histones, histone demethylases, have emerged as new therapeutic targets in different cancer types including colon cancer. These families are of great interest as potential novel biomarkers for diagnosis and targets for therapy and prevention of colon cancer. In this manuscript, we will discuss our current understanding of the histone demethylase family, and the role they play as epigenetic activators or repressors of different genes in colon cancer.

Review to better understand the macroscopic subtypes and histogenesis of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma is macroscopically classified into three subtypes, mass-forming-type, periductal infiltrating-type, and intraductal growth-type. Each subtype should be preoperatively differentiated to perform the valid surgical resection. Recent researches have revealed the clinical, radiologic, pathobiological characteristics of each subtype. We reviewed recently published studies covering various aspects of intrahepatic cholangiocarcinoma (ICC), focusing especially on the macroscopic subtypes and stem cell features to better understand the pathophysiology of ICC and to establish the valid therapeutic strategy.

Aberrant expression and altered cellular localization of desmosomal and hemidesmosomal proteins are associated with aggressive clinicopathological features of oral squamous cell carcinoma

Disruption of cell adhesion plays a central role in dedifferentiation, invasion, and metastasis of various cancers. The desmosome and hemidesmosome are anchoring junctions that control cell-cell and cell-matrix adhesion, respectively. To clarify their contributions in mediating the biological properties of oral cancer, we immunohistochemically examined the expression of desmoglein 1 (DSG1), DSG2, DSG3, desmocollin 2 (DSC2), integrin beta 4 (ITGB4), laminin gamma chain 2 (LAMC2), and collagen type 17 alpha 1 (COL17A1) in 51 cases of oral squamous cell carcinoma. On normal oral epithelial cells, DSG1, DSG3, DSC2, and COL17A1 were expressed on the plasma membrane, while ITGB4 and mature LAMC2 were present at the basement membrane. In cancer, the expression of DSG1, DSG3, DSC2, and COL17A1 decreased and internalized to the cytoplasm. Cytoplasmic expression of DSG2, ITGB4, and LAMC2 was induced in the cancer cells facing to the stroma. We scored immunohistochemical expression and correlated this to clinicopathological parameters including histologic differentiation, pattern of invasion, and presence of lymph node metastasis. Decrease of DSG3 and DSC2 expression correlated with a more aggressive cancer phenotype: less differentiated and more invasive histologic features and a higher incidence of nodal metastasis. Lower COL17A1 and higher LAMC2 expression were also associated with a more aggressive phenotype. The present study demonstrates that aberrant expression and altered cellular localization of desmosomal and hemidesmosomal proteins are associated with aggressive clinicopathological features of oral cancer. This reinforces the notion that disturbance of the keratin-associated anchoring junctions confers aggressive features to cancer cells.

PGE2 signaling and its biosynthesis-related enzymes in cholangiocarcinoma progression

Prostaglandin E2 (PGE2) involves in progression of various chronic inflammation-related cancers including cholangiocarcinoma (CCA). This study aimed to determine the role of PGE2 signaling, its biosynthesis-related enzymes in a clinical prognosis, and their targeted inhibition in CCA progression. The immunohistochemical staining of cyclooxygenase (COX)-1, COX-2, mPGES-1, EP1, and EP4 was examined in CCA tissues, and their expressions were compared with clinicopathological parameters. The effect of PGE2 on levels of its signaling molecules was examined in CCA cell lines using proteome profiler array. The suppression of mPGES-1 using a small-molecule inhibitor (CAY10526) and small interfering RNA (siRNA) was determined for growth and migration ability in CCA cells. The results indicated that strong expressions of COX-1, COX-2, mPGES-1, EP1, and EP4 were found in CCA tissues as 87.5, 47.5, 52.5, 55, and 80 % of frequencies, respectively. High mPGES-1 expression was significantly correlated with tumor stages III-IV (p = 0.001), lymph node metastasis (p = 0.004), shorter survival (p = 0.009), and prognostic indicator of CCA patients (HR = 2.512, p = 0.041). Expressions of COX-1, COX-2, and EP receptors did not correlate with data tested from patients. PGE2 markedly enhanced protein levels of integrinα6, VE-cadherin, Jagged1, and Notch3, and CAY10526 suppressed those protein levels as well as PGE2 production in CCA cells. CAY10526 and siRNA mPGES-1 markedly suppressed mPGES-1 protein levels, growth, and migration abilities of CCA cell lines. In conclusion, PGE2 signaling strongly promotes CCA progression. Therefore, inhibition of PGE2 synthesis by suppression of its biosynthesis-related enzymes could be useful for prevention and treatment of CCA.

LSD1-mediated epigenetic modification contributes to proliferation and metastasis of colon cancer

BACKGROUND

Emerging evidence has demonstrated that lysine-specific demethylase 1 (LSD1) has an important role in many pathological processes of cancer cells, such as carcinogenesis, proliferation and metastasis. In this study, we characterised the role and molecular mechanisms of LSD1 in proliferation and metastasis of colon cancer.

METHODS

We evaluated the correlation of LSD1, CDH-1 and CDH-2 with invasiveness of colon cancer cells, and investigated the roles of LSD1 in proliferation, invasion and apoptosis of colon cancer cells. We further investigated the mechanisms of LSD1-mediated metastasis of colon cancer.

RESULTS

Lysine-specific demethylase 1 was upregulated in colon cancer tissues, and the high LSD1 expression was significantly associated with tumour-node-metastasis (TNM) stages and distant metastasis. Functionally, inhibition of LSD1 impaired proliferation and invasiveness, and induced apoptosis of colon cancer cells in vitro. The LSD1 physically interacted with the promoter of CDH-1 and decreased dimethyl histone H3 lysine 4 (H3K4) at this region, downregulated CDH-1 expression, and consequently contributed to colon cancer metastasis.

CONCLUSION

Lysine-specific demethylase 1 downregulates the expression of CDH-1 by epigenetic modification, and consequently promotes metastasis of colon cancer cells. The LSD1 antagonists might be a useful strategy to suppress metastasis of colon cancer.