Epithelial-to-mesenchymal transition and resistance to ingenol 3-angelate, a novel protein kinase C modulator, in colon cancer cells

Repurposing of ingenol mebutate for treating human colorectal cancer by targeting S100 calcium-binding protein A4 (S100A4)

Colorectal cancer (CRC) is the world's second most common cause of cancer-related death. Novel treatments are still urgently needed. S100 calcium-binding protein A4 (S100A4) was demonstrated to be an anticancer therapeutic target. Herein, we found that higher S100A4 expression was associated with a poorer prognosis in publicly available cohorts and a Taiwanese CRC patient cohort. To identify repurposed S100A4 inhibitors, we mined the Connectivity Map (CMap) database for clinical drugs mimicking the S100A4-knockdown gene signature. Ingenol mebutate, derived from the sap of the plant Euphorbia peplus, is approved as a topical treatment for actinic keratosis. The CMap analysis predicted ingenol mebutate as a potent S100A4 inhibitor. Indeed, both messenger RNA and protein levels of S100A4 were attenuated by ingenol mebutate in human CRC cells. In addition, CRC cells with higher S100A4 expressions and/or the wild-type p53 gene were more sensitive to ingenol mebutate, and their migration and invasion were inhibited by ingenol mebutate. Therefore, our results suggest the repurposing of ingenol mebutate for treating CRC by targeting S100A4.

Ingol and Ingenol-Type Diterpenes from Euphorbia trigona Miller with Keratinocyte Inhibitory Activity

Ingenol mebutate, isolated from Euphorbia peplus, is an ingenane-type diterpenoid, primarily used for the topical treatment of actinic keratosis, a premalignant skin condition. The aim of our work was to investigate other Euphorbia species to find structurally similar diterpenes that can be used as alternatives to ingenol mebutate. Pharmacological investigation of Euphorbia candelabrum, Euphorbia cotinifolia, Euphorbia ramipressa, and Euphorbia trigona revealed the potent keratinocyte (HPV-Ker cell line) inhibitory activity of these spurge species. From the methanolic extract of the aerial parts of Euphorbia trigona Miller, the most active species, five ingol (1–5) and four ingenane-type diterpenoids (6–9) were isolated by various chromatographic separation techniques, including open column chromatography, vacuum liquid chromatography, thin-layer chromatography, and high-performance liquid chromatography. The structures of the compounds were determined by NMR spectroscopic analysis and by comparison of the assignations with the literature data. The cytotoxic activity of the compounds against keratinocytes was tested in vitro by using ingenol mebutate as a positive control. Among the isolated compounds, two ingenane derivatives (6 and 7) exhibited remarkably stronger cytotoxic activity (IC₅₀ values 0.39 μM and 0.32 μM, respectively) on keratinocytes than ingenol mebutate (IC₅₀ value 0.84 μM). These compounds could serve as starting materials for further investigations to find alternatives to Picato^® (with active substance ingenol mebutate), which was withdrawn from marketing authorization in the European Union.

Oral administration of EGCG solution equivalent to daily achievable dosages of regular tea drinkers effectively suppresses miR483-3p induced metastasis of hepatocellular carcinoma cells in mice

The effect of non-cytotoxic doses of epigallocatechin-3-gallate (EGCG) on the metastatic capability of human hepatocellular carcinoma (HCC) cells was investigated in vitro and in vivo. miR483-3p, a microRNA whose expression correlates inversely with survival and positively with disease progression in HCC patients, was found to promote HCC cell migration and invasion in vitro as well as lung metastasis in nude mice established by the tail-vein injection of HCC cells. The induction of reactive oxygen species (ROS) and downregulation of antioxidant defense factors Nrf2 and SOD2 appeared to be an important underlying mechanism and treatment with a non-cytotoxic dose of EGCG effectively reversed the miR483-3p-induced enhancement of HCC cell migration and invasion in vitro. Moreover, administration through drinking water at doses (0.1% and 0.5% EGCG solution, respectively) equivalent to the intake of regular to heavy tea drinkers could also significantly inhibit lung metastasis of HCC cells based on the estimation from the USDA Database for the Flavonoid Content of Selected Foods and FDA guidelines for the conversion of animal dose to human equivalent dose. EGCG also significantly counteracted the miR483-3p-induced alteration in the expression of epithelial-mesenchymal transition (EMT) markers, E-cadherin and vimentin, and downregulated the endogenous expression of miR483-3p in HCC cells through an epigenetic mechanism that led to the hypermethylation of the miR483-3p promoter region. The data from our study illustrate that miR483-3p promotes HCC metastasis likely through the induction of oxidative stress and uncover a novel role of EGCG for protection against miR483-3p-mediated HCC metastasis via the epigenetic modulation of miR483-3p expression. These findings therefore provide further evidence supporting that regular tea consumption may contribute to protection against miR-483-3p-induced ROS and the associated HCC progression.

Expression of epithelial-Mesenchymal transition related markers in Plasmacytoid Urothelial carcinoma of the urinary bladder

Background

Plasmacytoid urothelial carcinoma (PUC) of the urinary bladder is a variant of urothelial carcinoma that carries a poor prognosis. The epithelial-mesenchymal transition (EMT) has been demonstrated to contribute to tumor progression. As the cause of the increased aggressiveness of PUC is unknown, we investigated PUC and EMT-related marker expression.

Methods

A total of 633 bladder carcinoma cases diagnosed from 2006 to 2015 at the Nippon Medical School Hospital were analyzed. Twelve patients were found to have plasmacytoid histology and diagnosed with PUC. Slides were evaluated for percentage of plasmacytoid variant, and stained for E-cadherin, N-cadherin, Vimentin, Fibronectin and Snail expression.

Results

The incidence of PUC was 1.9% (12/633). The median patient age at diagnosis was 71 years (range, 60–80 years) and the male-female ratio was 11:1. All but three patients had stage T2b or higher. The median overall survival was 10 months. In 10/12 cases, Snail and N-cadherin were positive. Vimentin was positive in 9/12 cases. Fibronectin was positive in 8/12 cases. While E-cadherin was negative in 10/12 cases. Nine cases showed > 10% plasmacytoid component. Eight of the nine patients (88.9%) with > 10% plasmacytoid component died.

Conclusions

The results indicate that PUC may induce EMT and may be associated with high invasion.

Proteomic Characterization of Colorectal Cancer Cells versus Normal-Derived Colon Mucosa Cells: Approaching Identification of Novel Diagnostic Protein Biomarkers in Colorectal Cancer

In the western world, colorectal cancer (CRC) is the third most common cause of cancer-related deaths. Survival is closely related to the stage of cancer at diagnosis striking the clinical need for biomarkers capable of early detection. To search for possible biological parameters for early diagnosis of CRC we evaluated protein expression for three CREC (acronym: Cab45, reticulocalbin, ERC-55, calumenin) proteins: reticulocalbin, calumenin, and ERC-55 in a cellular model consisting of a normal derived colon mucosa cell line, NCM460, and a primary adenocarcinoma cell line of the colon, SW480. Furthermore, this cellular model was analyzed by a top-down proteomic approach, 2-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for novel putative diagnostic markers by identification of differentially expressed proteins between the two cell lines. A different colorectal carcinoma cell line, HCT 116, was used in a bottom-up proteomic approach with label-free quantification (LFQ) LC-MS/MS. The two cellular models gave sets of putative diagnostic CRC biomarkers. Various of these novel putative markers were verified with increased expression in CRC patient neoplastic tissue compared to the expression in a non-involved part of the colon, including reticulocalbin, calumenin, S100A6 and protein SET. Characterization of these novel identified biological features for CRC patients may have diagnostic potential and therapeutic relevance in this malignancy characterized by a still unmet clinical need.

Roles of S100 family members in drug resistance in tumors: Status and prospects

Chemotherapy and targeted therapy can significantly improve survival rates in cancer, but multiple drug resistance (MDR) limits the efficacy of these approaches. Understanding the molecular mechanisms underlying MDR is crucial for improving drug efficacy and clinical outcomes of patients with cancer. S100 proteins belong to a family of calcium-binding proteins and have various functions in tumor development. Increasing evidence demonstrates that the dysregulation of various S100 proteins contributes to the development of drug resistance in tumors, providing a basis for the development of predictive and prognostic biomarkers in cancer. Therefore, a combination of biological inhibitors or sensitizers of dysregulated S100 proteins could enhance therapeutic responses. In this review, we provide a detailed overview of the mechanisms by which S100 family members influence resistance of tumors to cancer treatment, with a focus on the development of effective strategies for overcoming MDR.

PKCε regulates Rho GTPases and actin cytoskeleton reorganization in non-small cell lung cancer cells

Oncogenic protein kinase C epsilon (PKCε) promotes the formation of membrane ruffles and motility in non-small cell lung cancer (NSCLC) cells. We found that PKCε is down-regulated when NSCLC cells undergo epithelial-to-mesenchymal transition (EMT) in response to TGF-β, thus becoming dispensable for migration and invasion in the mesenchymal state. PKCε silencing or inhibition leads to stress fibre formation, suggesting that this kinase negatively regulates RhoA activity. Ruffle formation induced by PKCε activation in the epithelial state is dependent on PI3K, but does not involve the PI3K-dependent Rac-GEFs Ect2, Trio, Vav2 or Tiam1, suggesting alternative Rac-GEFs as mediators of this response. In the proposed model, PKCε acts as a rheostat for Rho GTPases that differs in the epithelial and mesenchymal states.

Effects of HMGA2 siRNA and doxorubicin dual delivery by chitosan nanoparticles on cytotoxicity and gene expression of HT-29 colorectal cancer cell line

Objective

Over-expressions of HMGA2, vimentin and MMP-9 and downregulation of E-cadherin occur on colorectal cancer cells followed by a reduction in let-7 as a regulatory factor. In this study, we first used carboxymethyl dextran (CMD)–chitosan nanoparticles (ChNPs) platform to encapsulate HMGA2 siRNA and doxorubicin (DOX), and then, we evaluated the efficacy of the simultaneous delivery of siRNA/drug on viability and gene expression of HT-29 cell lines.

Methods

ChNPs characteristics were determined by a dynamic light scattering and zeta sizer. Morphology of loaded ChNPs was assessed by scanning electron microscopy, and Fourier transform infrared spectroscopy was used to confirm the conjugation of ChNP/siRNA/DOX/CMD. Cell viability and relative mRNA expression were evaluated by MTT assay and real-time PCR, respectively.

Key finding

The prepared ChNPs had high efficiency for siRNA and drug encapsulation (78% and 75%) and were stable against serum and heparin. ChNP/siRNA/DOX/CMD was more effective to induce tumour cell death and also could significantly reduce the expressions of HMGA2, vimentin as well as MMP-9 and increase E-cadherin expression.

Conclusion

In conclusion, our results revealed that dual delivery of a key gene siRNA and appropriate anticancer drug have great impact on the treatment of colorectal cancer.

Involvement of FoxQ1 in NSCLC through regulating EMT and increasing chemosensitivity

Forkhead box Q1 (FoxQ1) is a member of the forkhead transcription factor family. High expression of FoxQ1 has been associated with several cancers including non-small cell lung cancer (NSCLC), but its role in the development of NSCLC is not clear. In this study, we investigated the effect of FoxQ1 up-regulated and down-regulated in vitro and in vivo, and the role of FoxQ1 in regulating epithelial-mesenchymal transition (EMT) in NSCLC, providing evidence that FoxQ1 could be a potential therapeutic target in NSCLC. NSCLC cells with silenced FoxQ1 had decreased cell proliferation, migration and invasion in cell culture and delayed growth of xenograft tumors in mice compared with corresponding control cells. The NSCLC cells downregulated for FoxQ1 induced the expression of apoptosis-associated proteins and reduction of anti-apoptotic protein expression. Downregulation of FoxQ1 promoted the expression of epithelial markers and decreased several mesenchymal markers in vitro and in vivo. In addition, FoxQ1 was associated with resistance to conventional chemotherapeutic agents. In contrast, FoxQ1 overexpressed elicited converse effects on these phenotypes in vitro and in vivo. Our findings define a key role for FoxQ1 in regulating EMT and increasing chemosensitivity in NSCLC.

Ingenol Mebutate Signals via PKC/MEK/ERK in Keratinocytes and Induces Interleukin Decoy Receptors IL1R2 and IL13RA2

Squamous cell carcinoma (SCC) is the second most common human skin cancer and the second leading cause of skin cancer-related death. Recently, a new compound, ingenol mebutate, was approved for treatment of actinic keratosis, a precursor of SCC. As the mechanism of action is poorly understood, we have further investigated the mechanism of ingenol mebutate-induced cell death. We elucidate direct effects of ingenol mebutate on primary keratinocytes, patient-derived SCC cells, and a SCC cell line. Transcriptional profiling followed by pathway analysis was performed on ingenol mebutate-treated primary keratinocytes and patient-derived SCC cells to find key mediators and identify the mechanism of action. Activation of the resulting pathways was confirmed in cells and human skin explants and supported by a phosphorylation screen of treated primary cells. The necessity of these pathways was demonstrated by inhibition of certain pathway components. Ingenol mebutate inhibited viability and proliferation of all keratinocyte-derived cells in a biphasic manner. Transcriptional profiling identified the involvement of PKC/MEK/ERK signaling in the mechanism of action and inhibition of this signaling pathway rescued ingenol mebutate-induced cell death after treatment with 100 nmol/L ingenol mebutate, the optimal concentration for the first peak of response. We found the interleukin decoy receptors IL1R2 and IL13RA2 induced by ingenol mebutate in a PKC/MEK/ERK-dependent manner. Furthermore, siRNA knockdown of IL1R2 and IL13RA2 partially rescued ingenol mebutate-treated cells. In conclusion, we have shown that ingenol mebutate-induced cell death is mediated through the PKCδ/MEK/ERK pathway, and we have functionally linked the downstream induction of IL1R2 and IL13RA2 expression to the reduced viability of ingenol mebutate-treated cells.

Pharmaceuticals that contain polycyclic hydrocarbon scaffolds

This review comprehensively explores approved pharmaceutical compounds that contain polycyclic scaffolds and the properties that these skeletons convey.

Targeting TRAF3 Downstream Signaling Pathways in B cell Neoplasms

B cell neoplasms comprise >50% of blood cancers. However, many types of B cell malignancies remain incurable. Identification and validation of novel genetic risk factors and oncogenic signaling pathways are imperative for the development of new therapeutic strategies. We and others recently identified TRAF3, a cytoplasmic adaptor protein, as a novel tumor suppressor in B lymphocytes. We found that TRAF3 inactivation results in prolonged survival of mature B cells, which eventually leads to spontaneous development of B lymphomas in mice. Corroborating our findings, TRAF3 deletions and inactivating mutations frequently occur in human B cell chronic lymphocytic leukemia, splenic marginal zone lymphoma, mantle cell lymphoma, multiple myeloma, Waldenström’s macroglobulinemia, and Hodgkin lymphoma. In this context, we have been investigating TRAF3 signaling mechanisms in B cells, and are developing new therapeutic strategies to target TRAF3 downstream signaling pathways in B cell neoplasms. Here we discuss our new translational data that demonstrate the therapeutic potential of targeting TRAF3 downstream signaling pathways in B lymphoma and multiple myeloma.

Prognostic significance of the epithelial-to-mesenchymal transition markers e-cadherin, vimentin and twist in bladder cancer

OBJECTIVE

The goal of this study was to utilize long-term patient follow-up to determine whether epithelial-to-mesenchymal transition (EMT)-related markers can predict bladder cancer patient survival and progression of disease.

MATERIALS AND METHODS

This study included 121 patients with bladder cancer. Sixty-four of these patients presented with non-muscle invasive (NMI, stage T1) bladder cancer and 57 with muscle invasive (MI, stage T2, T3). The patients were diagnosed and treated between May 1998 and July 2012. The EMT markers E-cadherin, Twist, and Vimentin were detected via immunohistochemistry. Univariate and multivariate/Cox analyses were then utilized to determine whether these EMT markers could be useful prognostic markers for predicting bladder cancer patient outcomes.

RESULTS

Analysis of the 121 bladder cancer patients in this study revealed that the frequency of E-cadherin expression was 59.5% (72/121), Twist was 54.5% (66/121), and Vimentin was 24.8% (30/121). Twist and Vimentin were found to have statistically significant correlations with grade, recurrence, and progression but not with stage, whereas E-cadherin was associated with stage but not with the other parameters. In the univariate analysis, grade (p = 0.02) was the only significant predictor for progression-free survival (PFS). Stage, grade, and expression of E-cadherin, Vimentin and Twist were included in the multivariate analysis of predicting PFS. In this analysis, grade (p = 0.01) and Vimentin expression (p = 0.001) were found to be significant prognostic factors in predicting PFS.

CONCLUSIONS

Grade and Vimentin are potential independent indicators in predicting bladder cancer progression and survival.

Targeting tight junctions during epithelial to mesenchymal transition in human pancreatic cancer

Pancreatic cancer continues to be a leading cause of cancer-related death worldwide and there is an urgent need to develop novel diagnostic and therapeutic strategies to reduce the mortality of patients with this disease. In pancreatic cancer, some tight junction proteins, including claudins, are abnormally regulated and therefore are promising molecular targets for diagnosis, prognosis and therapy. Claudin-4 and -18 are overexpressed in human pancreatic cancer and its precursor lesions. Claudin-4 is a high affinity receptor of Clostridium perfringens enterotoxin (CPE). The cytotoxic effects of CPE and monoclonal antibodies against claudin-4 are useful as novel therapeutic tools for pancreatic cancer. Claudin-18 could be a putative marker and therapeutic target with prognostic implications for patients with pancreatic cancer. Claudin-1, -7, tricellulin and marvelD3 are involved in epithelial to mesenchymal transition (EMT) of pancreatic cancer cells and thus might be useful as biomarkers during disease. Protein kinase C is closely related to EMT of pancreatic cancer and regulates tight junctions of normal human pancreatic duct epithelial cells and the cancer cells. This review focuses on the regulation of tight junctions via protein kinase C during EMT in human pancreatic cancer for the purpose of developing new diagnostic and therapeutic modalities for pancreatic cancer.

OTX008, a selective small-molecule inhibitor of galectin-1, downregulates cancer cell proliferation, invasion and tumour angiogenesis

BACKGROUND

Galectin-1 (Gal1), a carbohydrate-binding protein is implicated in cancer cell proliferation, invasion and tumour angiogenesis. Several Gal1-targeting compounds have recently emerged. OTX008 is a calixarene derivative designed to bind the Gal1 amphipathic β-sheet conformation. Our study contributes to the current understanding of the role of Gal1 in cancer progression, providing mechanistic insights into the anti-tumoural activity of a novel small molecule Gal1-inhibitor.

METHODS

We evaluated in vitro OTX008 effects in a panel of human cancer cell lines. For in vivo studies, an ovarian xenograft model was employed to analyse the antitumour activity. Finally, combination studies were performed to analyse potential synergistic effects of OTX008.

RESULTS

In cultured cancer cells, OTX008 inhibited proliferation and invasion at micromolar concentrations. Antiproliferative effects correlated with Gal1 expression across a large panel of cell lines. Furthermore, cell lines expressing epithelial differentiation markers were more sensitive than mesenchymal cells to OTX008. In SQ20B and A2780-1A9 cells, OTX008 inhibited Gal1 expression and ERK1/2 and AKT-dependent survival pathways, and induced G2/M cell cycle arrest through CDK1. OTX008 enhanced the antiproliferative effects of Semaphorin-3A (Sema3A) in SQ20B cells and reversed invasion induced by exogenous Gal1. In vivo, OTX008 inhibited growth of A2780-1A9 xenografts. OTX008 treatment was associated with downregulation of Gal1 and Ki67 in treated tumours, as well as decreased microvessel density and VEGFR2 expression. Finally, combination studies showed OTX008 synergy with several cytotoxic and targeted therapies, principally when OTX008 was administered first.

CONCLUSION

This study provides insights into the role of Gal1 in cancer progression as well as OTX008 mechanism of action, and supports its further development as an anticancer agent.

Cancer wars: natural products strike back

Natural products have historically been a mainstay source of anticancer drugs, but in the 90's they fell out of favor in pharmaceutical companies with the emergence of targeted therapies, which rely on antibodies or small synthetic molecules identified by high throughput screening. Although targeted therapies greatly improved the treatment of a few cancers, the benefit has remained disappointing for many solid tumors, which revitalized the interest in natural products. With the approval of rapamycin in 2007, 12 novel natural product derivatives have been brought to market. The present review describes the discovery and development of these new anticancer drugs and highlights the peculiarities of natural product and new trends in this exciting field of drug discovery.

Abnormal expression of EMT-related proteins, S100A4, vimentin and E-cadherin, is correlated with clinicopathological features and prognosis in HCC

We determined the expression of epithelial-mesenchymal transition (EMT) indicator proteins, E-cadherin (E-cad), vimentin (VIM), mucin 1 (MUC1) and S100 calcium-binding protein A4 (S100A4) in hepatocellular carcinoma (HCC) patient tissue samples. We also investigated the relationship between the expression of these proteins and clinicopathologic factors in HCC. Finally, we assessed the potential value of these markers as prognostic indicators of survival in HCC patients. The expression of E-cad, VIM, MUC1 and S100A4 EMT indicator proteins was assessed in tissue microarray HCC tissue sections and corresponding peritumoral normal tissues by immunohistochemistry. In addition, the expression for the four EMT indicator proteins was correlated with clinicopathological features of HCC and patient outcome. Comparison of clinicopathological characteristics and immunohistochemistry by χ(2) analysis revealed that downregulation of E-cad in HCC was significantly associated with later TNM cancer stage (P = 0.012), gross classification (P = 0.018), regional lymph node metastasis (P = 0.036) and liver cirrhosis (P = 0.028). Increased S100A4 expression in HCC was significantly associated with differentiation (P = 0.032), tumor with a complete fibrous capsule (P = 0.031) and portal vein invasion (P = 0.038). High VIM expression in HCC was significantly associated with high serum α-fetoprotein levels (P = 0.016). We also observed that low E-cad expression was significantly associated with overexpression of VIM (P = 0.001). Kaplan-Meier survival and Cox regression analysis revealed that low E-cad expression (HR = 0.164, 95 % CI 0.072 to 0.373, P < 0.001) and high serum α-fetoprotein levels (HR = 2.202, 95 % CI 1.054 to 4.598, P = 0.036) were independent prognostic factors in HCC. Our study demonstrates that high S100A4 and VIM expression and low E-cad expression correlate with an aggressive, malignant phenotype in HCC. These results also support a role for E-cad as a prognostic factor in HCC.

Architecture of epigenetic reprogramming following Twist1-mediated epithelial-mesenchymal transition

Background

Epithelial-mesenchymal transition (EMT) is known to impart metastasis and stemness characteristics in breast cancer. To characterize the epigenetic reprogramming following Twist1-induced EMT, we characterized the epigenetic and transcriptome landscapes using whole-genome transcriptome analysis by RNA-seq, DNA methylation by digital restriction enzyme analysis of methylation (DREAM) and histone modifications by CHIP-seq of H3K4me3 and H3K27me3 in immortalized human mammary epithelial cells relative to cells induced to undergo EMT by Twist1.

Results

EMT is accompanied by focal hypermethylation and widespread global DNA hypomethylation, predominantly within transcriptionally repressed gene bodies. At the chromatin level, the number of gene promoters marked by H3K4me3 increases by more than one fifth; H3K27me3 undergoes dynamic genomic redistribution characterized by loss at half of gene promoters and overall reduction of peak size by almost half. This is paralleled by increased phosphorylation of EZH2 at serine 21. Among genes with highly altered mRNA expression, 23.1% switch between H3K4me3 and H3K27me3 marks, and those point to the master EMT targets and regulators CDH1, PDGFRα and ESRP1. Strikingly, Twist1 increases the number of bivalent genes by more than two fold. Inhibition of the H3K27 methyltransferases EZH2 and EZH1, which form part of the Polycomb repressive complex 2 (PRC2), blocks EMT and stemness properties.

Conclusions

Our findings demonstrate that the EMT program requires epigenetic remodeling by the Polycomb and Trithorax complexes leading to increased cellular plasticity. This suggests that inhibiting epigenetic remodeling and thus decrease plasticity will prevent EMT, and the associated breast cancer metastasis.

Epithelial-mesenchymal Transition and Cell Invasion

Epithelial-mesenchymal transition (EMT) is a complex process in which epithelial cells acquire the characteristics of invasive mesenchymal cells. EMT has been implicated in cancer progression and metastasis as well as the formation of many tissues and organs during development. Epithelial cells undergoing EMT lose cell-cell adhesion structures and polarity, and rearrange their cytoskeletons. Several oncogenic pathways such as transforming growth factor (TGF) -β, Wnt, and Notch signaling pathways, have been shown to induce EMT. These pathways have activated transcription factors including Snail, Slug, and the ZEB family which work as transcriptional repressors of E-cadherin, thereby making epithelial cells motile and resistant to apoptosis. Mounting evidence shows that EMT is associated with cell invasion and tumor progression.In this review, we summarize the characteristic features of EMT, pathways leading to EMT, and the role of EMT in cell invasion. Three topics are addressed in this review: (1) Definition of EMT, (2) Signaling pathways leading to EMT, (3) Role of EMT in cell invasion. Understanding the role of EMT in cell invasion will provide valuable information for establishing strategies to develop anti-metastatic therapeutics which modulate malignant cellular processes mediated by EMT.

N-benzyladriamycin-14-valerate (AD 198) exhibits potent anti-tumor activity on TRAF3-deficient mouse B lymphoma and human multiple myeloma

Background

TRAF3, a new tumor suppressor identified in human non-Hodgkin lymphoma (NHL) and multiple myeloma (MM), induces PKCδ nuclear translocation in B cells. The present study aimed to evaluate the therapeutic potential of two PKCδ activators, N-Benzyladriamycin-14-valerate (AD 198) and ingenol-3-angelate (PEP005), on NHL and MM.

Methods

In vitro anti-tumor activities of AD 198 and PEP005 were determined using TRAF3^-/- mouse B lymphoma and human patient-derived MM cell lines as model systems. In vivo therapeutic effects of AD 198 were assessed using NOD SCID mice transplanted with TRAF3^-/- mouse B lymphoma cells. Biochemical studies were performed to investigate signaling mechanisms induced by AD 198 or PEP005, including subcellular translocation of PKCδ.

Results

We found that AD 198 exhibited potent in vitro and in vivo anti-tumor activity on TRAF3^-/- tumor B cells, while PEP005 displayed contradictory anti- or pro-tumor activities on different cell lines. Detailed mechanistic investigation revealed that AD 198 did not affect PKCδ nuclear translocation, but strikingly suppressed c-Myc expression and inhibited the phosphorylation of ERK, p38 and JNK in TRAF3^-/- tumor B cells. In contrast, PEP005 activated multiple signaling pathways in these cells, including PKCδ, PKCα, PKCϵ, NF-κB1, ERK, JNK, and Akt. Additionally, AD198 also potently inhibited the proliferation/survival and suppressed c-Myc expression in TRAF3-sufficient mouse and human B lymphoma cell lines. Furthermore, we found that reconstitution of c-Myc expression conferred partial resistance to the anti-proliferative/apoptosis-inducing effects of AD198 in human MM cells.

Conclusions

AD 198 and PEP005 have differential effects on malignant B cells through distinct biochemical mechanisms. Our findings uncovered a novel, PKCδ-independent mechanism of the anti-tumor effects of AD 198, and suggest that AD 198 has therapeutic potential for the treatment of NHL and MM involving TRAF3 inactivation or c-Myc up-regulation.

Polycationic calixarene PTX013, a potent cytotoxic agent against tumors and drug resistant cancer

Previously, we reported on the anti-tumor activities of two designed calix[4]arene-based topomimetics (PTX008 and PTX009) of the amphipathic, angiostatic peptide Anginex. Here, we chemically modified the hydrophobic and hydrophilic faces of PTX008 and PTX009, and discovered new calixarene compounds that are more potent, cytotoxic anti-tumor agents. One of them, PTX013, is particularly effective at inhibiting the growth of several human cancer cell lines, as well as drug resistant cancer cells. Mechanistically, PTX013 induces cell cycle arrest in sub-G1 and G0/G1 phases of e.g. SQ20B cells, a radio-resistant human head and neck carcinoma model. In the syngeneic B16F10 melanoma tumor mouse model, PTX013 (0.5 mg/Kg) inhibits tumor growth by about 50-fold better than parent PTX008. A preliminary pharmacodynamics study strongly suggests that PTX013 exhibits good in vivo exposure and a relatively long half-life. Overall, this research contributes to the discovery of novel therapeutics as potentially useful agents against cancer in the clinic.

Endothelin 1 in cancer: biological implications and therapeutic opportunities

Activation of autocrine and paracrine signalling by endothelin 1 (ET1) binding to its receptors elicits pleiotropic effects on tumour cells and on the host microenvironment. This activation modulates cell proliferation, apoptosis, migration, epithelial-to-mesenchymal transition, chemoresistance and neovascularization, thus providing a strong rationale for targeting ET1 receptors in cancer. In this Review, we discuss the advances in our understanding of the diverse biological roles of ET1 in cancer and describe the latest preclinical and clinical progress that has been made using small-molecule antagonists of ET1 receptors that inhibit ET1-driven signalling.

Ingenol Mebutate: A Promising Treatment for Actinic Keratoses and Nonmelanoma Skin Cancers

Background:

A new treatment for actinic keratoses, ingenol mebutate, was recently approved by the US Food and Drug Administration.

Objective:

To review the mechanisms of action, efficacy and safety data, and practical recommendations for ingenol mebutate.

Methods:

The PubMed and clinicaltrials.gov databases were searched in March/April 2012 using the terms PEP005, ingenol mebutate, and ingenol 3-angelate. The abstracts from the Annual Scientific Meeting of the Australian College of Dermatologists (2009–2011) and the Annual Meeting of the American Academy of Dermatology (2009–2012) were also searched.

Results:

Due to its multiple mechanisms of action, ingenol mebutate treatment resulted in short- and long-term efficacy similar to other topical treatments for actinic keratoses in a shorter period of 2 or 3 days. This short therapy would reduce the duration of adverse events. Premarketing trials for treatment of nonmelanoma skin cancers also showed promising results for ingenol mebutate.

Conclusion:

Ingenol mebutate is a convenient, safe, and effective intervention for precancerous and cancerous skin conditions.

Predictive factors of sensitivity to elisidepsin, a novel Kahalalide F-derived marine compound

Elisidepsin (PM02734, Irvalec^®) is a synthetic marine-derived cyclic peptide of the Kahalalide F family currently in phase II clinical development. Elisidepsin was shown to induce rapid oncosis in ErbB3-expressing cells. Other predictive factors of elisidepsin sensitivity remained unknown. A panel of 23 cancer cell lines of different origin was assessed for elisidepsin cytotoxicity and correlated with mutational state, mRNA and protein expression of selected genes. Elisidepsin showed potent and broad cytotoxic effects in our cancer cell line panel, being active at concentrations ranging from 0.4 to 2 μM that may be relevant for clinical settings. We have shown that elisidepsin is more active in cells harboring epithelial phenotype with high E-cadherin and low vimentin expression. In addition, high ErbB3 and Muc1 expression was correlated with sensitivity to elisidepsin, whereas the presence of KRAS activating mutations was associated with resistance. In DU-PM cells with acquired resistance to elisidepsin, ErbB3 expression was decreased, while Bcl2 was increased. DU-PM cells displayed higher sensitivity to ErbB1-inhibitors suggesting possible cross-talk of ErbB1 and ErbB3 signaling pathways. Combinations of elisidepsin with lapatinib and several chemotherapies including 5-FU and oxaliplatin resulted in synergistic effects that offer the potential of clinical use of elisidepsin in combination settings.

Protein kinase Cα inhibitor protects against downregulation of claudin-1 during epithelial-mesenchymal transition of pancreatic cancer

Protein kinase Cα (PKCα) is highly expressed in pancreatic cancer. However, the effects of PKCα on Snail and claudin-1, which play crucial roles in epithelial cell polarity during epithelial-mesenchymal transition (EMT), remain unclear. In this study, we investigated the mechanisms of regulation of Snail and claudin-1 via a PKCα signal pathway during EMT in pancreatic cancer cells and in normal human pancreatic duct epithelial cells (HPDEs). By immunostaining, overexpression of PKCα and downregulation of claudin-1 were observed in poorly differentiated human pancreatic cancer tissues and the pancreatic cancer cell line PANC-1. Treatment with the PKCα inhibitor Gö6976 transcriptionally decreased Snail and increased claudin-1 in PANC-1 cells. The PKCα inhibitor prevented upregulation of Snail and downregulation of claudin-1 during EMT induced by transforming growth factor-β1 (TGF-β1) treatment and under hypoxia in PANC-1 cells. The effects of the PKCα inhibitor were in part regulated via an extracellular signal-regulated kinase (ERK) signaling pathway. The PKCα inhibitor also prevented downregulation of the barrier function and fence function during EMT in well-differentiated pancreatic cancer cell line HPAC. In normal HPDEs, the PKCα inhibitor transcriptionally induced not only claudin-1 but also claudin-4, -7 and occludin without a change of Snail. Treatment with the PKCα inhibitor in normal HPDEs prevented downregulation of claudin-1 and occludin by TGF-β1 treatment and enhanced upregulation of claudin-1, -4, -7 and occludin under hypoxia. These findings suggest that PKCα regulates claudin-1 via Snail- and mitogen-activated protein kinase/ERK-dependent pathways during EMT in pancreatic cancer. Thus, PKCα inhibitors may be potential therapeutic agents against the malignancy of human pancreatic cancer cells.

Prognostic value of the chemokine receptor CXCR4 and epithelial-to-mesenchymal transition in patients with squamous cell carcinoma of the mobile tongue

OBJECTIVE

The aim of this study was to evaluate the expression and the prognostic value of chemokine receptor 4 (CXCR4), its cognate ligand the CXCL12, and markers of epithelial-to-mesenchymal transition (EMT) in squamous cell carcinoma (SCC) of the mobile tongue.

PATIENTS AND METHODS

Patients with primary SCC of the mobile tongue who underwent surgery in our center were screened retrospectively. Patients without prior treatment, who had pre-surgery TNM staging and available tumor samples, were eligible. Protein expression of CXCL12, CXCR4, CA9, E-cadherin, and vimentin was determined by immunohistochemical staining, scored, and correlated with clinical and pathological parameters and overall survival. Multivariate and Cox proportional hazards analyses were performed.

RESULTS

Among 160 patients treated and screened, 47 were analyzed. CXCR4 and CXCL12 expression was high in tumor cells. CXCR4 expression in primary tumor samples was significantly higher in patients with high-grade tumors, lymph node metastases, and microscopic nerve invasion (p ≤ 0.05). There was a non-significant trend towards a correlation between high CXCL12 expression and pathologic tumor stage (p=0.07). Tumors with high CXCR4 expression correlated with poor overall survival (hazard ratio=3.6, 95% confidence interval 1.3-9.7; p=0.011), notably in the CXCR4(high)/vimentin-positive subgroup. Vimentin-positive tumors, characterizing EMT, were associated with lower survival (hazard ratio=4.5, 95% confidence interval 1.6-12.3; p=0.0086). Multivariate analysis confirmed vimentin (but not CXCR4) expression as an independent prognostic factor of poor overall survival (p=0.016).

CONCLUSION

Our results suggest that CXCR4 is a marker of tumor aggressiveness and vimentin is an important and independent prognostic factor in patients with SCC of the mobile tongue.

FoxQ1 overexpression influences poor prognosis in non-small cell lung cancer, associates with the phenomenon of EMT

Background

We determined the expression of forkhead box Q1 (FoxQ1), E-cadherin (E-cad), Mucin 1 (MUC1), vimentin (VIM) and S100 calcium binding protein A4 (S100A4), all epithelial-mesenchymal transition (EMT) indicator proteins in non-small cell lung cancer (NSCLC) tissue samples. We also investigated the relationship between these five proteins expression and other clinicopathologic factors in NSCLC. Finally, we assessed the potential value of these markers as prognostic indicators of survival in NSCLC's patients.

Methods

Quantitative real-time PCR and immunohistochemistry were used to characterize the expression of the FoxQ1 mRNA and protein in NSCLC. Expression of transcripts and translated products for the other four EMT indicator proteins was assessed by immunohistochemistry in the same clinical NSCLC samples.

Results

FoxQ1 mRNA and protein were up-regulated in NSCLC compared with normal tissues (P = 0.015 and P<0.001, respectively). Expression of FoxQ1 in adenocarcinoma was higher than in squamous cell carcinoma (P = 0.005), and high expression of FoxQ1 correlated with loss of E-cad expression (P = 0.012), and anomalous positivity of VIM (P = 0.024) and S100A4 (P = 0.004). Additional survival analysis showed that high expression of FoxQ1 (P = 0.047) and E-cad (P = 0.021) were independent prognostic factors.

Conclusion

FoxQ1 maybe plays a specific role in the EMT of NSCLC, and could be used as a prognostic factor for NSCLC.

Antitumor agent calixarene 0118 targets human galectin-1 as an allosteric inhibitor of carbohydrate binding

Calix[4]arene compound 0118 is an angiostatic agent that inhibits tumor growth in mice. Although 0118 is a topomimetic of galectin-1-targeting angiostatic amphipathic peptide Anginex, we had yet to prove that 0118 targets galectin-1. Galectin-1 is involved in pathological disorders like tumor endothelial cell adhesion and migration and therefore presents a relevant target for therapeutic intervention against cancer. Here, (15)N-(1)H HSQC NMR spectroscopy demonstrates that 0118 indeed targets galectin-1 at a site away from the lectin's carbohydrate binding site and thereby attenuates lactose binding to the lectin. Flow cytometry and agglutination assays show that 0118 attenuates binding of galectin-1 to cell surface glycans, and the inhibition of cell proliferation by 0118 is found to be correlated with the cellular expression of the lectin. In general, our data indicate that 0118 targets galectin-1 as an allosteric inhibitor of glycan/carbohydrate binding. This work contributes to the clinical development of antitumor calixarene compound 0118.

Immunohistochemical expression of Annexin A2 and S100A proteins in patients with bulky stage IB-IIA cervical cancer treated with neoadjuvant chemotherapy

OBJECTIVE

Abnormal expression of Annexin A2 and S100A proteins has been reported to induce sensitivity/resistance to chemotherapy in a variety of cancers. The aim of this study was to evaluate the significance of Annexin A2 and S100A protein expression to predict response to neoadjuvant chemotherapy and prognostic significance of these protein expressions in bulky stage IB-IIA cervical cancer patients.

METHODS

Paired tumor samples (pre- and post-chemotherapy) were obtained from 68 patients who were treated with cisplatin-based neoadjuvant chemotherapy and radical hysterectomy at our hospital from 2006 to 2011. The expression of Annexin A2 and S100A proteins was analyzed by immunohistochemistry.

RESULTS

Thirty-six patients were identified as chemotherapy-response and 32 were non-response. (a). Protein expression in tumor cells: (1). Exposure of tumor cells to chemotherapy results in a change of Annexin A2 and S100A expression (P<0.05). (2). Annexin A2, S100A8 and S100A9 protein expression correlates with tumor response to chemotherapy (P<0.05). (b). Protein expression in stromal cells: (1). Expression of Annexin A2, S100A8 and S100A9 was increased, but S100A2 and S100A4 was decreased after exposure to chemotherapy (P<0.05). (2). Only S100A4 expression was associated with response to chemotherapy (P<0.05). Multivariate analysis revealed that tumor size (P=0.022), differentiation (P=0.000), Annexin A2 expression in stromal cells (P=0.009), and S100A8 expression in tumor cells (P=0.008) were independent prognostic factors for progression-free survival of cervical cancer patients.

CONCLUSIONS

Expression of some of the measured proteins in tumor and stromal cells correlates with chemotherapy exposure, response to therapy, and progression-free survival.

Protein kinase Cα inhibitor enhances the sensitivity of human pancreatic cancer HPAC cells to Clostridium perfringens enterotoxin via claudin-4

Protein kinase C (PKC) is overexpressed in cancer, including pancreatic cancer, compared with normal tissue. Moreover, PKCα is considered one of the biomarkers for the diagnosis of cancers. In several human cancers, the claudin tight junction molecules are abnormally regulated and are thus promising molecular targets for diagnosis and therapy with Clostridium perfringens enterotoxin (CPE). In order to investigate the changes of tight junction functions of claudins via PKCα activation in pancreatic cancer cells, the well-differentiated human pancreatic cancer cell line HPAC, with its highly expressed tight junction molecules and well-developed barrier function, was treated with the PKC activator 12-O-tetradecanoylphorbol 13-acetate (TPA). Treatment with TPA modified the activity of phosphoPKCα and caused an increase of the Snail family members Snail, Slug and Smad-interacting protein 1 and a decrease of E-cadherin. In HPAC cells treated with TPA, downregulation of claudin-1 and mislocalization of claudin-4 and occludin around the nuclei were observed, together with a decrease in the numbers of tight junction strands and an increase in phosphorylation of claudin-4. The barrier function and the cytotoxicity of CPE were significantly decreased on TPA treatment. All such changes after TPA treatment were prevented by inhibitors of panPKC and PKCα. These findings suggest that, in human pancreatic cancer cells, PKCα activation downregulates tight junction functions as a barrier and as a receptor of CPE via the modification of claudin-1 and -4 during epithelial to mesenchymal transition-like changes. PKCα inhibitors might represent potential therapeutic agents against human pancreatic cancer cells by use of CPE cytotoxicity via claudin-4.

The H4 histamine receptor agonist, clobenpropit, suppresses human cholangiocarcinoma progression by disruption of epithelial mesenchymal transition and tumor metastasis

Cholangiocarcinoma (CCA) is a biliary cancer arising from damaged bile ducts. Epithelial-mesenchymal transition (EMT) occurs as epithelial cells begin to resemble mesenchymal cells leading to increased invasion potential as the extracellular matrix (ECM) degrades. Histamine exerts its effects by way of four receptors (H1-H4 HRs). Clobenpropit, a potent H4HR agonist, inhibits mammary adenocarcinoma growth. We have shown that (1) cholangiocytes and CCA cells express H1-H4 HRs and (2) the H3HR decreases CCA proliferation. We evaluated the effects of clobenpropit on CCA proliferation, invasion, EMT phenotypes, and ECM degradation. In vitro, we used CCA cell lines to study proliferation, signaling pathways, and the morphological invasive potential. Gene and protein expression of the hepatobiliary epithelial markers CK-7, CK-8, and CK-19, the focal contact protein paxillin, and the mesenchymal markers fibronectin, s100A4, and vimentin were evaluated. Cell invasion across an ECM layer was quantitated and matrix metalloproteinase-1, -2, -3, -9, and -11 gene and protein expression was examined. Evaluation of the specific role of H4HR was performed by genetic knockdown of the H3HR and overexpression of H4HR. Proliferation was evaluated by proliferating cellular nuclear antigen immunoblotting. In vivo, xenograft tumors were treated with either vehicle or clobenpropit for 39 days. Tumor volume was recorded every other day. Clobenpropit significantly decreased CCA proliferation by way of a Ca(2+) -dependent pathway and altered morphological development and invasion. Loss of H3HR expression or overexpression of H4HR significantly decreased CCA proliferation. In vivo, clobenpropit inhibited xenograft tumor growth compared with controls.

CONCLUSION

Modulation of H4HR by clobenpropit disrupts EMT processes, ECM breakdown, and invasion potential and decreases tumor growth. Interruption of tumorigenesis and invasion by histamine may add to therapeutic advances for CCAs.

Epithelial-to-mesenchymal transition and acquired resistance to sunitinib in a patient with hepatocellular carcinoma

BACKGROUND & AIMS

Based on the success of sorafenib, several anti-angiogenic therapies are currently evaluated in advanced hepatocellular carcinomas. Few biological data are currently available from patients that may help understanding mechanisms of acquired resistance to these drugs. Herein, we report translational data from a post-treatment surgical specimen in a patient who experienced acquired resistance to sunitinib.

METHODS

Clinical, radiological, and pathological data were collected before treatment, under treatment, and at the time of tumor progression. In addition, a biomolecular analysis was performed at the time of progression.

RESULTS

In this patient with non-alcoholic steatohepatitis, initial response to sunitinib was followed by tumor progression within 6 months of treatment, requesting salvage surgical resection. Surprisingly, pathological examination on post-treatment specimens revealed the presence of two juxtaposed tissue components containing either sarcomatoid-like mesenchymal cells or well- to moderately-differentiated hepatocellular carcinoma cells. Cancer cells retain a high α-fetoprotein expression in both components. However, while cells from carcinoma expressed E-cadherin but no vimentin, cancer cells from the mesenchymal component highly expressed vimentin and lost E-cadherin protein expression as measured by immunostaining. HMGA2 and Ki67 mRNA were also expressed at higher levels in mesenchymal than in carcinoma cells.

CONCLUSION

This case report suggests the occurrence of an epithelial-to-mesenchymal transition in discrete areas of hepatocellular carcinomas developing resistance to sunitinib.

Acquisition of chemoresistance and EMT phenotype is linked with activation of the endothelin A receptor pathway in ovarian carcinoma cells

PURPOSE

Emerging evidence suggests molecular and phenotypic association between chemoresistance and epithelial-mesenchymal transition (EMT) in cancer. Endothelin-1 (ET-1)/endothelin A receptor (ET(A)R) axis is implicated in the pathobiology of epithelial ovarian cancer (EOC) by driving tumor-promoting effects, including EMT. Here, we analyzed how ET(A)R regulates chemoresistance and EMT in EOC.

EXPERIMENTAL DESIGN

The effects of ET-1 axis on cell proliferation, drug-induced apoptosis, invasiveness, and EMT were analyzed in cultured EOC cells sensitive and resistant to cisplatinum and taxol. Tumor growth in response to ET(A)R antagonist was examined in EOC xenografts. ET(A)R expression was examined in 60 human EOC tumors by immunohistochemistry and correlated with chemoresistance and EMT.

RESULTS

In resistant EOC cells ET-1 and ET(A)R are upregulated, paralleled by enhanced mitogen activated protein kinase (MAPK) and Akt phosphorylation and cell proliferation. Moreover, in these cells the expression of E-cadherin transcriptional repressors, including Snail, Slug, and Twist, as well as of mesenchymal markers, such as vimentin and N-cadherin, were upregulated and linked with enhanced invasive behavior. Interestingly, ET(A)R blockade with zibotentan, a specific ET(A)R antagonist, or its silencing, downregulated Snail activity, restored drug sensitivity to cytotoxic-induced apoptosis, and inhibited the invasiveness of resistant cells. In vivo, zibotentan inhibited tumor growth of sensitive and resistant EOC xenografts, and sensitized to chemotherapy. Analysis of EOC human tissues revealed that ET(A)R is overexpressed in resistant tumors and is associated with EMT phenotype.

CONCLUSIONS

Our data provide the first evidence that blockade of ET(A)R-driven EMT can overcome chemoresistance and inhibit tumor progression, improving the outcome of EOC patients' treatment.

Evidence for mesenchymal-like sub-populations within squamous cell carcinomas possessing chemoresistance and phenotypic plasticity

Variable drug responses among malignant cells within individual tumors may represent a barrier to their eradication using chemotherapy. Carcinoma cells expressing mesenchymal markers resist conventional and epidermal growth factor receptor (EGFR)-targeted chemotherapy. Here we evaluated whether mesenchymal-like subpopulations within human squamous cell carcinomas (SCCs) with predominantly epithelial features contribute to overall therapy resistance. We identified a mesenchymal-like subset expressing low E-cadherin (Ecad-lo) and high vimentin (Vim-hi) within upper aerodigestive tract SCCs. This subset was both isolated from cell lines and identified in xenografts and primary clinical specimens. The Ecad-lo subset contained more low-turnover cells, correlating with resistance to the conventional chemotherapeutic paclitaxel in vitro. Epidermal growth factor (EGF) induced less stimulation of the MAP kinase and PI3-kinase pathways in Ecad-lo cells, which was likely due to lower EGFR expression in this subset and correlated with in vivo resistance to the EGFR-targeted antibody cetuximab. The Ecad-lo and high E-cadherin (Ecad-hi) subsets were dynamic in phenotype, showing the capacity to repopulate each other from single cell clones. Taken together, these results provide evidence for a low-turnover, mesenchymal-like subpopulation in SCCs with diminished EGFR pathway function and intrinsic resistance to conventional and EGFR-targeted chemotherapies.

Epithelial-to-mesenchymal transition and oncogenic Ras expression in resistance to the protein kinase Cbeta inhibitor enzastaurin in colon cancer cells

Identifying molecular factors of sensitivity and resistance of cancer cells to enzastaurin, a drug inhibiting protein kinase C (PKC) beta, remains a major challenge to improve its clinical development. Investigating the cellular effects of enzastaurin in a panel of 20 human cancer cell lines, we found that most cells displaying oncogenic K-Ras mutations also display resistance to enzastaurin. Wild-type (WT) K-Ras cancer cells displaying high sensitivity to enzastaurin also expressed high mRNA levels of epithelial markers, such as E-cadherin (CDH1), and low mRNA expressions of mesenchymal markers, such as vimentin, N-cadherin (CDH2), and other genes frequently expressed in mesenchymal transition such as ZEB1, TWIST, SLUG, SNAIL, and TGFbeta. WT K-Ras enzastaurin-resistant cells also expressed high levels of mesenchymal markers. Based on this observation, the effects of enzastaurin were investigated in epithelial colon COLO205-S cells that expressed WT Ras/Raf and its derived COLO205-R mesenchymal counterpart selected for resistance to most PKC modulators and displaying oncogenic K-Ras (G13D/exon 2). In COLO205-S cells, inhibition of phosphorylated PKCbeta led to the inactivation of AKT and glycogen synthase kinase 3beta and was associated with apoptosis without significant effect on cell cycle progression. In COLO205-R cells, enzastaurin induced mainly necrosis at high concentrations. In COLO205-R cells, a strong activation of extracellular signal-regulated kinase 1/2 possibly due to oncogenic K-Ras was predominantly associated with transcription of potent antiapoptotic genes, such as BCL2, GADD45B, and CDKN1A, as well as the multidrug resistance gene ABCB1. From this study, colon cancer cells undergoing apoptosis under enzastaurin exposure seem to frequently express a WT Ras and an epithelial phenotype.

The protein kinase C agonist PEP005 (ingenol 3-angelate) in the treatment of human cancer: a balance between efficacy and toxicity

The diterpene ester ingenol-3-angelate (referred to as PEP005) is derived from the plant Euphorbia peplus. Crude euphorbia extract causes local toxicity and transient inflammation when applied topically and has been used in the treatment of warts, skin keratoses and skin cancer. PEP005 is a broad range activator of the classical (α, β, γ) and novel (δ, ε, η, θ) protein kinase C isoenzymes. Direct pro-apoptotic effects of this drug have been demonstrated in several malignant cells, including melanoma cell lines and primary human acute myelogenous leukemia cells. At micromolar concentrations required to kill melanoma cells this agent causes PKC-independent secondary necrosis. In contrast, the killing of leukemic cells occurs in the nanomolar range, requires activation of protein kinase C δ (PKCδ) and is specifically associated with translocation of PKCδ from the cytoplasm to the nuclear membrane. However, in addition to this pro-apoptotic effect the agent seems to have immunostimulatory effects, including: (i) increased chemokine release by malignant cells; (ii) a general increase in proliferation and cytokine release by activated T cells, including T cells derived from patients with chemotherapy-induced lymphopenia; (iii) local infiltration of neutrophils after topical application with increased antibody-dependent cytotoxicity; and (iv) development of specific anti-cancer immune responses by CD8(+) T cells in animal models. Published studies mainly describe effects from in vitro investigations or after topical application of the agent, and careful evaluation of the toxicity after systemic administration is required before the possible use of this agent in the treatment of malignancies other than skin cancers.

Induction of epithelial mesenchimal transition and vasculogenesis in the lenses of Dbl oncogene transgenic mice

Background

The Dbl family of proteins represents a large group of proto-oncogenes involved in cell growth regulation. The numerous domains that are present in many Dbl family proteins suggest that they act to integrate multiple inputs in complicated signaling networks involving the Rho GTPases. Alterations of the normal function of these proteins lead to pathological processes such as developmental disorders and neoplastic transformation. We generated transgenic mice introducing the cDNA of Dbl oncogene linked to the metallothionein promoter into the germ line of FVB mice and found that onco-Dbl expression in mouse lenses affected proliferation, migration and differentiation of lens epithelial cells.

Results

We used high density oligonucleotide microarray to define the transcriptional profile induced by Dbl in the lenses of 2 days, 2 weeks, and 6 weeks old transgenic mice. We observed modulation of genes encoding proteins promoting epithelial-mesenchymal transition (EMT), such as down-regulation of epithelial cell markers and up-regulation of fibroblast markers. Genes encoding proteins involved in the positive regulation of apoptosis were markedly down regulated while anti-apoptotic genes were strongly up-regulated. Finally, several genes encoding proteins involved in the process of angiogenesis were up-regulated. These observations were validated by histological and immunohistochemical examination of the transgenic lenses where vascularization can be readily observed.

Conclusion

Onco-Dbl expression in mouse lens correlated with modulation of genes involved in the regulation of EMT, apoptosis and vasculogenesis leading to disruption of the lens architecture, epithelial cell proliferation, and aberrant angiogenesis. We conclude that onco-Dbl has a potentially important, previously unreported, capacity to dramatically alter epithelial cell migration, replication, polarization and differentiation and to induce vascularization of an epithelial tissue.