Few genes are associated with the capability of pancreatic ductal adenocarcinoma cells to grow in the liver of nude rats

A subgroup of lactosyl-Sepharose binding proteins requires calcium for affinity and galactose for anti-proliferation

Lactosyl-Sepharose binding proteins (LSBPs) were recently described in human pancreatic ductal adenocarcinoma (PDAC) Suit2-007 cells regarding their lectin-like properties and role in metastasis. This study further investigated how calcium and galactose influence the binding of LSBPs to the lactosyl resin as well as their anti-proliferative effect in Suit2-007 cells. Altered binding of LSBPs to the lactosyl resin was evaluated by affinity chromatography and mass spectrometry. Calcium binding EF-hand proteins were aligned and identified with a motif derived from the Uniprot protein database. The antiproliferative effects of LSBPs and monosaccharides were determined by MTT assay. In addition, LSBPs and galactose effects were investigated by chip array and tumor take in nude rats. LSBPs reduced Suit2-007 cells' proliferation with an IC₅₀ of 125 μg/mL. Coincubation of LSBPs with EGTA decreased the number of LSBPs binding to the lactosyl resin by ~50%. Ca²⁺ -sensitive LSBPs included subgroups of galactose-sensitive (10%) and EF-hand calcium binding motifs containing (2.5%) proteins. In vitro, the combination of LSBPs with monosaccharides including galactose synergistically decreased cell proliferation compared to single agents (p < 0.05). In addition, LSBPs in combination with galactose prevented the tumor growth of Suit2-007 cells in nude rats, as opposed to single treatments. At mRNA level, the combination treatment modulated 5% of Ca²⁺ -sensitive LSBPs and downregulated 216 genes, 18% of which were up-regulated during PDAC progression. This study highlights the importance of calcium and galactose in modulating the affinity and anti-proliferative activity of LSBPs and their potential application as therapeutic agents for metastatic PDAC.

Riproximin Exhibits Diversity in Sugar Binding, and Modulates some Metastasis-Related Proteins with Lectin like Properties in Pancreatic Ductal Adenocarcinoma

Riproximin (Rpx) is a type II ribosome-inactivating protein with specific anti-proliferative activity. It was purified from Ximenia americana by affinity chromatography using a resin coupled with lactosyl residues. The same technique facilitated isolation of proteins with lectin-like properties from human Suit2-007 and rat ASML pancreatic cancer cells, which were termed lactosyl-sepharose binding proteins (LSBPs). The role of these proteins in cancer progression was investigated at mRNA level using chip array data of Suit2-007 and ASML cells re-isolated from nude rats. These data compared significant mRNA expression changes when relating primary (pancreas) and metastatic (liver) sites following orthotopic and intraportal implantation of Pancreatic Ductal Adenocarcinoma (PDAC) cells, respectively. The affinity of Rpx to 13 simple sugar structures was modeled by docking experiments, the ranking of which was principally confirmed by NMR-spectroscopy. In addition, Rpx and LSBPs were evaluated for anti-proliferative activity and their cellular uptake was assessed by fluorescence microscopy. From 13 monosaccharides evaluated, open-chain rhamnose, β-d-galactose, and α-l-galactopyranose showed the highest affinities for site 1 of Rpx’s B-chain. NMR evaluation yielded a similar ranking, as galactose was among the best binders. Both, Rpx and LSBPs reduced cell proliferation in vitro, but their anti-proliferative effects were decreased by 15–20% in the presence of galactose. The program “Ingenuity Pathway Analysis” identified 2,415 genes showing significantly modulated mRNA expression following exposure of Suit2-007 cells to Rpx in vitro. These genes were then matched to those 1,639 genes, which were significantly modulated in the rat model when comparing primary and metastatic growth of Suit2-007 cells. In this overlap analysis, LSBP genes were considered separately. The potential suitability of Rpx for treating metastatic Suit2-007 PDAC cells was reflected by those genes, which were modulated by Rpx in a way opposite to that observed in cancer progression. Remarkably, these were 14% of all genes modulated during cancer progression, but 71% of the respective LSBP gene subgroup. Based on these findings, we predict that Rpx has the potential to treat PDAC metastasis by modulating genes involved in metastatic progression, especially by targeting LSBPs.

Modulation of the Endothelin System in Colorectal Cancer Liver Metastasis: Influence of Epigenetic Mechanisms?

Targeting of endothelin system genes is a promising strategy in cancer therapy. The modulation of these genes was explored in a model of colorectal cancer (CRC) liver metastasis and in a panel of CRC tumor cell lines that were exposed to the demethylating agent decitabine. The CC531 rat model mimicking CRC liver metastasis was used for tumor cell re-isolation and analysis of the endothelin system genes and DNA methyltransferases (DNMTs) by microarray. To mimic the effects caused by methylation changes, a panel of seven CRC cell lines was treated with the demethylating agent decitabine. Three genes of the endothelin system were potently modulated at messenger RNA (mRNA) level in rat CC531 cells during liver colonization. The concomitant decrease of two DNMTs suggested an influence from altered methylation. Changes in gene expression were also accomplished by exposure of CRC cells to the demethylating agent decitabine, when using daily low concentrations for 3 days, with minimal cytotoxic effects. Sensitive human SW480 cells showed an almost 100fold upregulation of endothelin-1 mRNA compared to untreated cells. This, however, was different in LS174T cells, which showed no significant increase in gene expression although the methylation levels were significantly decreased at a variety of corresponding loci. We suggest that the mechanism induced by methylation on gene expression in metastatic CRC cells can be compromised. The results question the overall success of treating metastatic CRC by methylation inhibitors.

The CCR5 antagonist maraviroc causes remission of pancreatic cancer liver metastasis in nude rats based on cell cycle inhibition and apoptosis induction

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease, and novel therapeutic strategies are urgently needed. Recently, expression of the C-C chemokine receptor 5 (CCR5) and its ligands has been found to play an important role in cancer progression and metastasis. In this study, we blocked the CCR5 receptor by the FDA approved antagonist maraviroc (MVC) in Suit2-007 and MIA-PaCa-2 human PDAC cells. The treatment significantly inhibited their proliferation and induced apoptosis of exposed cells as evidenced by caspases activation and increased Bax levels. Moreover, MVC inhibited the cell cycle by down regulating the proteins of the complexes of cyclin dependent kinase (CDK) 4/6 - Cyclin D and CDK2 - Cyclin E, as well as by increasing the protein levels of CDK inhibitors p18, p21 and p27. In line with this, MVC caused significant retardation of Suit2-007 cells growing in a PDAC liver metastasis xenograft model (p < 0.05). These results suggest that maraviroc could be a promising treatment strategy for PDAC patients with liver metastases.

A six-mRNA prognostic model to predict survival in head and neck squamous cell carcinoma

BACKGROUND

Transcriptional dysregulation is one of the most important features of cancer genesis and progression. Applying gene expression dysregulation information to predict the development of cancers is useful for cancer diagnosis. However, previous studies mainly focused on the relationship between a single gene and cancer. Prognostic prediction using combined gene models remains limited.

MATERIALS AND METHODS

Gene expression profiles were downloaded from The Cancer Genome Atlas and the data sets were randomly divided into training data sets and test data sets. A six-gene signature associated with head and neck squamous cell carcinoma (HNSCC) and overall survival (OS) was identified according to a training cohort by using weighted gene correlation network analysis and least absolute shrinkage and selection operator Cox regression. The test data set and gene expression omnibus (GEO) data set were used to validate this signature.

RESULTS

We identified six candidate genes, namely, FOXL2NB, PCOLCE2, SPINK6, ULBP2, KCNJ18, and RFPL1, and, using a six-gene model, predicted the risk of death of head and neck squamous cell carcinoma in The Cancer Genome Atlas. At a selected cutoff, patients were clustered into low- and high-risk groups. The OS curves of the two groups of patients had significant differences, and the time-dependent receiver operating characteristics of OS, disease-specific survival (DSS), and progression-free survival (PFS) were as high as 0.766, 0.731, and 0.623, respectively. Then, the test data set and the GEO data set were used to evaluate our model, and we found that the OS time in the high-risk group was significantly shorter than in the low-risk group in both data sets, and the receiver operating characteristics of test data set were 0.669, 0.675, and 0.614, respectively. Furthermore, univariate and multivariate Cox regression analyses showed that the risk score was independent of clinicopathological features.

CONCLUSION

The six-gene model could predict the OS of HNSCC patients and improve therapeutic decision-making.

Inhibition of cell proliferation, migration and colony formation of LS174T Cells by carbonic anhydrase inhibitor

Background

Metastasis is the leading cause of cancer deaths. Migration of tumor cells is an important stage in metastasis. Therefore, recent studies have focused on clarifying migration and migration-dependent cell functions such as angiogenesis, wound healing, and invasion.

Objectives

In the present study, we aimed to investigate the effect of acetazolamide, which is a classical carbonic anhydrase inhibitor, on the cell viability, migration, and colony forming capacity of human LS174T colorectal cancer cells.

Methods

Three different cell culture techniques (MTT test, wound healing and clonogenic assay) were performed in this in vitro study on colorectal cancer cells.

Results

Acetazolamide reduced the cell viability, migration and colony formation ability of cells depending on dose. There was no significant difference between the cells treated with acetazolamide with 1 µM dose and the control. However, it can be concluded that acetazolamide exerts its effect on human colorectal cancer cells at 10-1000 µM concentrations.

Conclusion

Acetazolamide was observed to significantly inhibit the cell viability, colony forming capacity, and migration ability in the culture medium of LS174T cells. This inhibitor effect of acetazolamide was observed to be dependent on the concentration in medium.

Pancreatic carcinoma cells colonizing the liver modulate the expression of their extracellular matrix genes

Liver is the main target of pancreatic ductal adenocarcinoma (PDAC) metastasis. Here, a rat model was used for analysing gene expression modulations during liver colonization. ASML PDAC cells were injected to isogenic rats and re-isolated at various stages of liver colonization for RNA isolation or re-cultivation. Microarrays were used for analysing mRNA and miRNA profiles of expres­sion. The results were partially confirmed by (q) RT-PCR and western blot. Selected genes were knocked down by siRNA transfection and the resulting cell behaviour was analysed. The ratio of up- and down regulated genes decreased from 20:1 (early stage) to 1.2:1 (terminal stage). Activation of cancer relevant gene categories varied between stages of liver colonization, with a nadir in the intermediate stage. The cells' environment triggered up to hundredfold changed expression for collagens, matrix metalloproteinases and chemokines. These modulations in mRNA expression were related to respective changes at miRNA levels. Gene expression knockdown of Mmp2 and Ccl20, which were highly modulated in vivo, was correlated with reduced prolif­eration and migration in vitro. Thus, target genes and temporal alterations in expression were identified, which can serve as basis for future therapeutic or diagnostic purposes.

The expression of genes contributing to pancreatic adenocarcinoma progression is influenced by the respective environment

Pancreatic adenocarcinoma is a highly aggressive malignancy with dismal prognosis and limited curative options. We investigated the influence of organ environments on gene expression in RNU rats by orthotopic and intraportal infusion of Suit2-007luc cells into the pancreas, liver and lung respectively. Tumor tissues from these sites were analyzed by chip array and histopathology. Generated data was analyzed by Chipster and Ingenuity Pathway Analysis (±1.5 expression fold change and p<0.05). Further analysis of functional annotations derived from IPA, was based on selected genes with significant modulation of expression. Comparison of groups was performed by creating ratios from the mean expression values derived from pancreas and respective in vitro values, whereas those from liver and lung were related to pancreas, respectively. Genes of interest from three functional annotations for respective organs were identified by exclusion-overlap analyses. From the resulting six genes, transglutaminase2 (TGM2) was further investigated by various assays. Its knockdown with siRNA induced dose dependent inhibitory and stimulatory effects on cell proliferation and cell migration, respectively. DNA fragmentation indicated apoptotic cell death in response to TGM2 knockdown. Cell cycle analysis by FACS showed that TGM2 knockdown induced G1/S blockade. Therefore, TGM2 and its associated genes may be promising therapeutic targets.

The ribosome inhibiting protein riproximin shows antineoplastic activity in experimental pancreatic cancer liver metastasis

Pancreatic ductal adenocarcinoma (PDAC) has one of the poorest prognoses of all malignancy types. To improve the survival of patients with PDAC, the development of novel anticancer agents is warranted. Riproximin (Rpx) is a newly identified plant lectin, which was isolated from Ximenia americana. The ribosome inactivating protein of type II exhibits potent anticancer activity as recently demonstrated. The rat PDAC cell line ASML was used for in vitro and in vivo studies. The antiproliferative effect of Rpx was assessed using an MTT assay. The modulation of proteins involved in apoptosis was evaluated using western blotting. Tumor-bearing nude rats were treated with Rpx, gemcitabine (GEM) or dinaline (DIN) as single agents, or a combination of Rpx with GEM, or DIN. Rpx was administered intraperitoneally at doses of 1.7–5.4 µg/kg, three times/week, GEM was administered intravenously (50 mg/kg/week) and DIN perorally (10 mg/kg, 5 times/week). Rpx inhibited ASML cell proliferation at IC₅₀-values of 0.8–172 pM, caused apoptosis and reduced tumor growth significantly by 90% (P<0.05). The survival rate of rats was significantly increased (21.8 days for Rpx treated vs. 17.6 days for control rats; P=0.05). Higher doses of Rpx caused no further reduction in tumor size when compared with the low dose of Rpx or a combination of Rpx with GEM, or DIN. The standard drug GEM alone was less effective compared with Rpx. In addition, DIN was ineffective, and in combination, reduced the activity of Rpx. These results suggest that Rpx has an evident potential for use in pancreatic cancer treatment. Further experiments are required in order to elucidate its affinity for certain cancer cells and to optimize the combination therapy with other antineoplastic agents.

Investigation of Metastasis-Related Genes: A Rat Model Mimicking Liver Metastasis of Colorectal Carcinoma

Liver is the main target of colorectal cancer (CRC) metastasis. Currently, the number of reports is small, which describe changes in gene expression supporting liver metastasis. Here, a rat model was used for analyzing mRNA modulations during liver colonization and compared with available literature. In the model, CC531 rat CRC cells were injected via a mesenteric vein into isogenic WAG/Rij rats and re-isolated at early, intermediate, advanced, and terminal stages of liver colonization. These cells were used for RNA isolation. Microarrays were used for analyzing mRNA profiles of expression. The number of deregulated genes is comparatively large and only part of it has been studied so far. As reported to date, claudins and insulin-like growth factor-binding proteins (IGFBPs) were found to be deregulated. The fact that the chosen method is efficient is confirmed by the study of claudins and IGFBPs, which show altered expression in the initial stages of liver colonization and then return to normalcy. In addition, cadherin was described to be downregulated in epithelial-mesenchymal transition models. It can, therefore, be concluded that the models used are helpful in finding genes, which are instrumental for metastatic liver colonization.

SIBLINGs and SPARC families: Their emerging roles in pancreatic cancer

Pancreatic cancer has a considerably poor prognosis with a 5-year survival probability of less than 5% when all stages are combined. Pancreatic cancer is characterized by its dense stroma, which is involved in the critical interplay with the tumor cells throughout tumor progression and furthermore, creates a barrier restricting efficient penetration of therapeutics. Alterations in a large number of genes are reflected by a limited number of signaling pathways, which are potential targets. Understanding more about the molecular basis of this devastating cancer type regarding tumor microenvironment, distinct subpopulations of cells, epithelial-to-mesenchymal transition and inflammation will lead to the development of various targeted therapies for controlling tumor growth and metastasis. In this complex scenario of pancreatic cancer, especially members of the “small integrin binding ligand N-linked glycoproteins” (SIBLINGs) and “secreted protein acidic and rich in cysteine” (SPARC) families have emerged due to their prominent roles in properties including proliferation, differentiation, apoptosis, adhesion, migration, angiogenesis, wound repair and regulation of extracellular matrix remodeling. SIBLINGs consist of five members, which include osteopontin (OPN), bone sialoprotein, dentin matrix protein 1, dentin sialophosphoprotein and matrix extracellular phosphoglycoprotein. The SPARC family of modular extracellular proteins is comprised of SPARC/osteonectin (ON) and SPARC-like 1 (hevin); secreted modular calcium binding proteins; testicans and follistatin-like protein. In this review, we especially focus on OPN and ON, elaborating on their special and growing importance in pancreatic cancer diagnosis and prognosis.

Riproximin's activity depends on gene expression and sensitizes PDAC cells to TRAIL

Riproximin (Rpx) is a type II ribosome inactivating protein, which was investigated for its activity in pancreatic ductal adenocarcinoma (PDAC) in a panel of 17 human and rat PDAC cell lines and in rat pancreatic cancer liver metastasis. Cytotoxicity in response to Rpx was determined by MTT assay, apoptosis by flow cytometry and qRT-PCR for apoptosis related genes, and the modulation of the transcriptome was monitored by micro array analysis. The combination effect of Rpx and TRAIL was assessed by MTT assay. Rpx showed high but varying cytotoxicity in PDAC cells. Based on overall gene expression, the sensitivity of these cells was linked to genes involved in apoptosis. Furthermore, based on the affinity of Rpx for CEA, the expression of carcinoembryonic antigen-related cell adhesion molecule (CEACAM) genes was significantly related to Rpx's cytotoxicity in cells with CEACAM gene expression. Exposure of Suit2-007 cells to Rpx induced the mRNA expression of members of signaling pathways initiating from most death receptors, and down modulation of TRAIL. Apoptosis was increased as shown by FACS analysis. Combination of Rpx with TRAIL resulted in a synergistic cytotoxic effect in human Suit2-007 and rat ASML cells, as evidenced by a 6-fold lower tumor cell survival than expected from an additive combination effect. Treatment of BDX rats bearing intra-portally implanted Suit2-007 cells showed a highly significant anticancer effect and indicated an application of Rpx against pancreatic cancer metastasis to the liver. These data favor further evaluation of Rpx as anticancer agent in PDAC.

Metastasis-related processes show various degrees of activation in different stages of pancreatic cancer rat liver metastasis

BACKGROUND

Most pancreatic ductal adenocarcinoma (PDAC) patients who undergo tumor resection will develop postoperative liver metastasis within the first 2 years. Our hypothesis was that, during liver colonization, the temporal modulation of processes related to metastasis will change in a specific manner and that information on these changes might be used for new therapeutic approaches.

MATERIAL AND METHODS

PDAC rat ASML cells were inoculated into the liver of BDX rats and re-isolated after different time periods of liver colonization (early, intermediate, advanced, and terminal). The total RNA of these samples was used to evaluate the expression profiles of more than 23,000 genes by chip array analysis.

RESULTS

Depending on the time span following re-isolation, 7-15% of all known genes were deregulated. These genes were assigned to metastasis-related processes during the 4 stages of colonization. Except for apoptosis, all other processes were not activated in the early and middle colonization stages. In the terminal phase of liver colonization, cell proliferation, cell homing, cell movement, and vasculogenesis were significantly activated.

CONCLUSION

We hypothesize that targeting the relatively few deregulated genes in the early stage of liver colonization could ultimately improve the survival of PDAC patients.