Gene expression profiling of liver metastases and tumour invasion in pancreatic cancer using an orthotopic SCID mouse model. Br J Cancer. 2007;97:1432-1440. [PMID: 17940512 PMCID: PMC2360231 DOI: 10.1038/sj.bjc.6604031]

Genetics, Genomics and Emerging Molecular Therapies of Pancreatic Cancer

The number of cases of pancreatic cancers in 2019 in Poland was 3852 (approx. 2% of all cancers). The course of the disease is very fast, and the average survival time from the diagnosis is 6 months. Only <2% of patients live for 5 years from the diagnosis, 8% live for 2 years, and almost half live for only about 3 months. A family predisposition to pancreatic cancer occurs in about 10% of cases. Several oncogenes in which somatic changes lead to the development of tumours, including genes BRCA1/2 and PALB2, TP53, CDKN2A, SMAD4, MLL3, TGFBR2, ARID1A and SF3B1, are involved in pancreatic cancer. Between 4% and 10% of individuals with pancreatic cancer will have a mutation in one of these genes. Six percent of patients with pancreatic cancer have NTRK pathogenic fusion. The pathogenesis of pancreatic cancer can in many cases be characterised by homologous recombination deficiency (HRD)-cell inability to effectively repair DNA. It is estimated that from 24% to as many as 44% of pancreatic cancers show HRD. The most common cause of HRD are inactivating mutations in the genes regulating this DNA repair system, mainly BRCA1 and BRCA2, but also PALB2, RAD51C and several dozen others.

Emerging roles for the YAP/TAZ transcriptional regulators in brain tumour pathology and targeting options

The transcriptional co-activators Yes-associated protein 1/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) have emerged as significant regulators of a wide variety of cellular and organ functions with impact in early embryonic development, especially during the expansion of the neural progenitor cell pool. YAP/TAZ signalling regulates organ size development, tissue homeostasis, wound healing and angiogenesis by participating in a complex network of various pathways. However, recent evidence suggests an association of these physiologic regulatory effects of YAP/TAZ with pro-oncogenic activities. Herein, we discuss the physiological functions of YAP/TAZ as well as the extensive network of signalling pathways that control their expression and activity, leading to brain tumour development and progression. Furthermore, we describe current targeting approaches and drug options including direct YAP/TAZ and YAP-TEA domain transcription factor (TEAD) interaction inhibitors, G-protein coupled receptors (GPCR) signalling modulators and kinase inhibitors, which may be used to successfully attack YAP/TAZ-dependent tumours.

Topology impacts TRAIL therapy: Differences in primary cancer growth and liver metastasis between orthotopic and subcutaneous xenotransplants of pancreatic ductal adenocarcinoma cells

BACKGROUND

To study novel treatment modalities for pancreatic ductal adenocarcinoma (PDAC), we need to transfer the knowledge from in vitro to in vivo. It is important to mirror the clinical characteristics of the typically local invasive growth of pancreatic cancer and the distant spread resulting in liver metastasis. Notably, for xenotransplant studies using human specimen, two models, i.e. subcutaneous (s.c.) and orthotopic (o.t.) transplantation are widely used.

METHODS

The subcutaneously and orthotopically inoculated Colo357 Bcl-xL cell-derived tumors were directly compared with and without TNF-related apoptosis inducing ligand (TRAIL) treatment. The size of primary tumors, number of liver metastasis and the histologic markers Ki67, M30, TNF-α and CD31 were assessed.

RESULTS

Upon TRAIL treatment, the primary tumors did not change their size, neither in the s.c. nor in the o.t. approaches. But when s.c. was compared to o.t., the size of the s.c. tumors was more than two-fold bigger than that of the o.t. tumors (P < 0.01). However, mice with orthotopically inoculated PDAC cells developed liver metastasis upon TRAIL treatment much more frequently (n = 13/17) than mice with subcutaneously inoculated PDAC cells (n = 1/11) (P < 0.01). As a likely driving force for this increased metastasis, a higher TNF-α staining intensity in the o.t. tumors was observed by immunohistochemistry.

CONCLUSIONS

These data from a direct side-by-side comparison underline the importance of the proper inoculation site of the PDAC cells. Local invasion and liver metastases are a hallmark of PDAC in the clinic; the o.t. model is clearly superior in reflecting this setting. Moreover, a serious side-effect of a possible new therapeutic compound became obvious only in the o.t.

MODEL

The study of stress conditions on growth and proteome of Raoultella planticola: a new emerging pathogen

All bacteria can survive and adapt to different stresses, such as fluctuations in temperature, pH oxidative, and osmotic pressure occurring in their surrounding environments. This study aims to evaluate the effects of a variety of stress conditions on the growth, and proteome of Raoultella planticola PTCC 1598. R. planticola cells were exposed to different values of temperatures, sodium chloride, pH, and hydrogen peroxide stresses. Among the stress conditions, oxidative stress, upon exposure to hydrogen peroxide (H₂O₂) at 4000 ppm concentration was selected for proteomics analysis in detail. Approximately, 1400 spots were identified in two-dimensional gel electrophoresis (2-DE). Among the identified spots, 85 spots were repeatable using 2D-Platinum software and eye confirmation and, nine protein spots were differentially expressed. Among nine proteins, six proteins identified successfully with an MASCOT score greater than 40 (p < 0.05) were 2,3-dihydroxybenzoate-2,3-dehydrogenase (oxidoreductase family), hypothetical protein G787-04832, periplasmic D-galactose-binding protein, uridine phosphorylase (glycosyltransferases), a single peptide match to cysteine-binding periplasmic protein, and NADP(H) nitroreductase. All identified proteins showed decreased level expression. Based on the obtained results, we concluded that hydrogen peroxide as an antiseptic compound could affect cell growth and proteomics of R. planticola. Therefore, we recommend using an antiseptic solution containing H₂O₂ to prevent the spread of R. planticola as a new emerging pathogen.

Organoid model: A new hope for pancreatic cancer treatment?

Pancreatic cancer is a rapidly progressing disease with a poor prognosis. We still have many questions about the pathogenesis, early diagnosis and precise treatment of this disease. Organoids, a rapidly emerging technology, can simulate the characteristics of pancreatic tumors. Using the organoid model of pancreatic cancer, we can study and explore the characteristics of pancreatic cancer, thereby effectively guiding clinical practice and improving patient prognosis. This review introduces the development of organoids, comparisons of organoids with other preclinical models and the status of organoids in basic research and clinical applications for pancreatic cancer.

Stathmin levels alter PTPN14 expression and impact neuroblastoma cell migration

BACKGROUND

Stathmin mediates cell migration and invasion in vitro, and metastasis in vivo. To investigate stathmin's role on the metastatic process, we performed integrated mRNA-miRNA expression analysis to identify pathways regulated by stathmin.

METHODS

MiRNA and gene arrays followed by miRNA-target-gene integration were performed on stathmin-depleted neuroblastoma cells (Ctrl_shRNA vs. Stmn Seq2_shRNA). The expression of the predicted target PTPN14 was evaluated by RT-qPCR, western blot and immunohistochemistry. Gene-silencing technology was used to assess the role of PTPN14 on proliferation, migration, invasion and signalling pathway.

RESULTS

Stathmin levels modulated the expression of genes and miRNA in neuroblastoma cells, leading to a deregulation of migration and invasion pathways. Consistent with gene array data, PTPN14 mRNA and protein expression were downregulated in stathmin- depleted neuroblastoma cells and xenografts. In two independent neuroblastoma cells, suppression of PTPN14 expression led to an increase in cell migration and invasion. PTPN14 and stathmin expression did not act in a feedback regulatory loop in PTPN14- depleted cells, suggesting a complex interplay of signalling pathways. The effect of PTPN14 on YAP pathway activation was cell-type dependent.

CONCLUSIONS

Our findings demonstrate that stathmin levels can regulate PTPN14 expression, which can modulate neuroblastoma cell migration and invasion.

Generation and application of patient-derived xenograft models in pancreatic cancer research

OBJECTIVE

Pancreatic ductal adenocarcinoma cancer (PDAC) is one of the leading causes of cancer-related death worldwide. Hence, the development of effective anti-PDAC therapies is urgently required. Patient-derived xenograft (PDX) models are useful models for developing anti-cancer therapies and screening drugs for precision medicine. This review aimed to provide an updated summary of using PDX models in PDAC.

DATA SOURCES

The author retrieved information from the PubMed database up to June 2019 using various combinations of search terms, including PDAC, pancreatic carcinoma, pancreatic cancer, patient-derived xenografts or PDX, and patient-derived tumor xenografts or PDTX.

STUDY SELECTION

Original articles and review articles relevant to the review's theme were selected.

RESULTS

PDX models are better than cell line-derived xenograft and other models. PDX models consistently demonstrate retained tumor morphology and genetic stability, are beneficial in cancer research, could enhance drug discovery and oncologic mechanism development of PDAC, allow an improved understanding of human cancer cell biology, and help guide personalized treatment.

CONCLUSIONS

In this review, we outline the status and application of PDX models in both basic and pre-clinical pancreatic cancer researches. PDX model is one of the most appropriate pre-clinical tools that can improve the prognosis of patients with pancreatic cancer in the future.

Pancreatic stellate cells activated by mutant KRAS-mediated PAI-1 upregulation foster pancreatic cancer progression via IL-8

Background: The dense fibrotic stroma enveloping pancreatic tumors is a major cause of drug resistance. Pancreatic stellate cells (PSCs) in the stroma can be activated to induce intra-tumor fibrosis and worsen patient survival; however, the molecular basics for the regulation of PSC activation remains unclear.

Methods: The in vitro coculture system was used to study cancer cell-PSC interactions. Atomic force microscopy was used to measure the stiffness of tumor tissues and coculture gels. Cytokine arrays, qPCR, and Western blotting were performed to identify the potential factors involved in PSC activation and to elucidate underlying pathways.

Results: PSC activation characterized by α-SMA expression was associated with increased pancreatic tumor stiffness and poor prognosis. Coculture with cancer cells induced PSC activation, which increased organotypic coculture gel stiffness and cancer cell invasion. Cancer cells-derived PAI-1 identified from coculture medium could activate PSCs, consistent with pancreatic cancer tissue microarray analysis showing a strong positive correlation between PAI-1 and α-SMA expression. Suppression by knocking down PAI-1 in cancer cells demonstrated the requirement of PAI-1 for coculture-induced PSC activation and gel stiffness. PAI-1 could be upregulated by KRAS in pancreatic cancer cells through ERK. In PSCs, inhibition of LRP-1, ERK, and c-JUN neutralized the effect of PAI-1, suggesting the contribution of LRP-1/ERK/c-JUN signaling. Furthermore, activated PSCs might exacerbate malignant behavior of cancer cells via IL-8 because suppression of IL-8 signaling reduced pancreatic tumor growth and fibrosis in vivo.

Conclusions: KRAS-mutant pancreatic cancer cells can activate PSCs through PAI-1/LRP-1 signaling to promote fibrosis and cancer progression.

miR‑381 functions as a tumor suppressor by targeting ETS1 in pancreatic cancer

Increasing evidence shows that microRNA (miR)-381 is involved in the carcinogenesis and biologic progression of various types of cancer in humans. However, its potential biologic role and mechanism in pancreatic cancer remain to be elucidated. In the present study, the expression and functional role of miR-381 in pancreatic cancer were investigated. It was found that miR-381 was significantly downregulated in pancreatic cancer tissues and cell lines. The biological functions of miR-381 were examined by measuring cell proliferation, migration, invasion and apoptosis in vitro and in vivo. The miR-381 target gene and signaling pathway were identified by luciferase activity assay and western blot assay. In vitro experiments confirmed that the enforced expression of miR-381 markedly suppressed cell proliferation, migration and invasion, and induced apoptosis in pancreatic cancer cells. By contrast, silencing the expression of miR-381 had the opposite effect. In addition, miR-381 inhibited xenograft tumor growth in vivo. Furthermore, ETS1 was identified as a direct target of miR-381, and western blot analysis showed that miR-381 negatively modulated the expression of ETS1. It was also demonstrated that miR-381 serves a key role in pancreatic cancer cells through regulating the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway. In conclusion, the data obtained suggested that miR-381 mediated cell proliferation, migration and invasion by targeting ETS1, partly through PI3K/AKT/mTOR signaling pathway. These results provide novel insights into understanding the potential effects and molecular mechanism of miR-381 on pancreatic cancer. miR-381 may serve as a novel potential marker for pancreatic cancer treatment in the future.

MicroRNA‑584 directly targets CCND1 and inhibits cell proliferation and invasion in pancreatic cancer

Multiple previous studies have demonstrated that the dysregulation of microRNAs (miRNAs) is implicated in the occurrence and development of pancreatic cancer. Therefore, a further characterisation of deregulated miRNAs in pancreatic cancer may provide novel insight into the oncogenesis and progression of pancreatic cancer, which may facilitate the identification of effective therapeutic targets for treating patients with this disease. In the present study, reverse transcription‑quantitative polymerase chain reaction analysis demonstrated that the expression level of miRNA‑584‑5p (miR‑584) was significantly decreased in pancreatic cancer tissues and cell lines. It was demonstrated that restoration of miR‑584 expression significantly suppressed the proliferative and invasive ability of pancreatic cancer cells. Bioinformatics analysis predicted that cyclin D1 (CCND1) was a putative target of miR‑584. Subsequent experiments demonstrated that CCND1 was a direct target gene of miR‑584 in pancreatic cancer cells. Furthermore, the inhibition of CCND1 mimicked the suppressive effect of miR‑584 overexpression in pancreatic cancer cells. The restoration of CCND1 expression significantly abolished the inhibitory effects of miR‑584 overexpression on pancreatic cancer cells. Collectively, the present results demonstrated that miR‑584 inhibited the development of pancreatic cancer by directly targeting CCND1, suggesting that this miRNA may represent a potential therapeutic target for this fatal disease.

Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification

Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.

Panbinostat decreases cFLIP and enhances killing of cancer cells by immunotoxin LMB-100 by stimulating the extrinsic apoptotic pathway

LMB-100 (RG7787) is a recombinant immunotoxin, which kills mesothelin-expressing cancer cells and now being evaluated in phase 1 trials. To enhance the anti-tumor activity of LMB-100, we have searched for agents, already approved for cancer therapy, that can be combined with LMB-100 to increase its efficacy. Panbinostat is a pan-histone deacetylase inhibitor that is used to treat multiple myeloma. We incubated different types of cancer cells with panbinostat and LMB-100 and found that they interacted synergistically to cause cell death. We found that panbinostat and the combination increased levels of mRNAs encoding TNF/TNFR family members, as well as BNIP3L and CASP-9, and markedly decreased mRNA levels for c-FLIP and BID. Western blots confirmed a fall in levels of cFLIP protein and a rise in BNIP3L and caspase-9. The combination also increased levels of cleaved BID (t-BID), cleaved-capsase-3 and −8 and PARP. To assess the importance of the fall in cFLIP levels, we treated cells with the cFLIP inhibitor, Rocaglamide, and found it also enhanced killing of tumor cells by LMB-100. LMB-100, which activates the intrinsic pathway of apoptosis, and panbinostat, which activates the extrinsic pathway, work in a synergistic manner to kill cancer cell lines.

Inflammatory cytokines and angiogenic factors as potential biomarkers in South African pancreatic ductal adenocarcinoma patients: A preliminary report

BACKGROUND/OBJECTIVES

Several studies have investigated the association of differentially expressed cytokines with pancreatic ductal adenocarcinoma (PDAC), but none in African countries. This study aimed at investigating T-helper (Th) cell and angiogenic markers as diagnostic or prognostic biomarkers for PDAC in Black South Africans.

METHODS

We conducted a prospective, case-control study comprising of 34 PDAC patients and 27 control participants with either critical limb ischemia, abdominal aortic aneurysm or other abdominal pathology from causes other than pancreatic disease. Plasma levels of IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, IL-17A, VEGF, sVEGF-R1, FGF, PIGF, PDGF and P-selectin were measured using commercially available cytometric bead array, ELISA and multi-analyte Luminex kits.

RESULTS

Significantly higher levels of IFN-γ (p < 0.001), TNF (p < 0.001), IL-2 (p = 0.001), IL-4 (p < 0.01), IL-10 (p < 0.01), IL-17A (p < 0.01), PlGF (p < 0.0001) and basic FGF (p < 0.0001) were found in cases compared to control participants. PDAC patients with irresectable tumours had higher levels of VEGF (p = 0.02) and IL-6 (p = 0.01). A univariate analysis showed significant associations between IFN-γ, TNF, IL-10, -4, -2, basic FGF, PlGF and PDAC. In a multivariate logistic regression model, basic FGF (p = 0.002) and PlGF (p = 0.007) were independent risk factors for PDAC with a combined sensitivity of 71% and specificity of 100%.

CONCLUSION

Our preliminary data suggests a potential role for basic FGF and PlGF as diagnostic, and VEGF and IL-6 as prognostic biomarkers of PDAC in Black South African patients.

MicroRNA-148a Suppresses the Proliferation and Migration of Pancreatic Cancer Cells by Down-regulating ErbB3

OBJECTIVES

ErbB3 (HER3) has been associated with pancreatic cancer progression, but little is known about its regulatory mechanisms. We investigated whether microRNAs (miRNAs) regulate levels of ErbB3 in pancreatic cancer cells.

METHODS

We used bioinformatic analyses to search for miRNAs that can potentially target ERBB3. Furthermore, the biological consequences of the targeting of ERBB3 by miR-148a were examined by cell proliferation and migration assays in vitro.

RESULTS

We identified an inverse correlation between miR-148a and ErbB3 protein levels in pancreatic cancer tissue samples and cell lines. We identified that miR-148a directly recognizes the 3'-UTR of the ErbB3 transcript and regulates ErbB3 expression. We demonstrated that the repression of ERBB3 by miR-148a suppressed the proliferation and migration of pancreatic cancer cells. In PANC-1 pancreatic cancer cells, the repression of ErbB3 by miR-148a inhibited the phosphorylation of ERK1/2 and AKT, which eventually repressed the proliferation and migration of these cells.

CONCLUSIONS

Taken together, the present study provides the first evidence that miR-148a plays a significant role in the suppression of pancreatic tumorigenesis via the inhibition of ErbB3 translation.

Reduced Expression of Histone Methyltransferases KMT2C and KMT2D Correlates with Improved Outcome in Pancreatic Ductal Adenocarcinoma

Genes encoding the histone H3 lysine 4 methyltransferases KMT2C and KMT2D are subject to deletion and mutation in pancreatic ductal adenocarcinoma (PDAC), where these lesions identify a group of patients with a more favorable prognosis. In this study, we demonstrate that low KMT2C and KMT2D expression in biopsies also defines better outcome groups, with median survivals of 15.9 versus 9.2 months (P = 0.029) and 19.9 versus 11.8 months (P = 0.001), respectively. Experiments with eight human pancreatic cell lines showed attenuated cell proliferation when these methyltransferases were depleted, suggesting that this improved outcome may reflect a cell-cycle block with diminished progression from G0-G1 RNA-seq analysis of PDAC cell lines following KMT2C or KMT2D knockdown identified 31 and 124 differentially expressed genes, respectively, with 19 genes in common. Gene-set enrichment analysis revealed significant downregulation of genes related to cell-cycle and growth. These data were corroborated independently by examining KMT2C/D signatures extracted from the International Cancer Genome Consortium and The Cancer Genome Atlas datasets. Furthermore, these experiments highlighted a potential role for NCAPD3, a condensin II complex subunit, as an outcome predictor in PDAC using existing gene expression series. Kmt2d depletion in KC/KPC cell lines also led to an increased response to the nucleoside analogue 5-fluorouracil, suggesting that lower levels of this methyltransferase may mediate the sensitivity of PDAC to particular treatments. Therefore, it may also be therapeutically beneficial to target these methyltransferases in PDAC, especially in those patients demonstrating higher KTM2C/D expression. Cancer Res; 76(16); 4861-71. ©2016 AACR.

Advances in understanding the molecular mechanism of pancreatic cancer metastasis

BACKGROUND

Pancreatic cancer (PC) is usually diagnosed at the late-stage and therefore, has widespread metastasis and a very high mortality rate. The mechanisms underlying PC metastasis are not well understood. Recent advances in genomic sequencing have identified groups of gene mutations that affect PC metastasis, but studies elucidating their roles are lacking. The present review was to investigate the molecular mechanisms of PC metastasis.

DATA SOURCES

Relevant articles on PC metastasis were searched in MEDLINE via PubMed prior to April 2015. The search was limited in English publications.

RESULTS

PC metastatic cascades are multi-factorial events including both intrinsic and extrinsic elements. This review highlights the most important genetic alterations and other mechanisms that account for PC invasion and metastasis, with particular regard to epithelial-mesenchymal transition, inflammation, stress response, and circulating tumor cells.

CONCLUSIONS

Analyses of relevant gene functions and signaling pathways are needed to establish the gene regulatory network and to define the pivotal modulators. Another promising area of study is the genotyping and phenotyping of circulating tumor cells, which could lead to a new era of personalized therapy by identifying specific markers and targets.

The Regulatory Role of KIBRA and PTPN14 in Hippo Signaling and Beyond

The Hippo signaling pathway regulates cellular proliferation and survival, thus exerting profound effects on normal cell fate and tumorigenesis. Pivotal effectors of this pathway are YAP/TAZ, transcriptional co-activators whose dysfunction contributes to the development of cancer. Complex networks of intracellular and extracellular signaling pathways that modulate YAP and TAZ activities have recently been identified. Among them, KIBRA and PTPN14 are two evolutionarily-conserved and important YAP/TAZ upstream regulators. They can negatively regulate YAP/TAZ functions separately or in concert. In this review, we summarize the current and emerging regulatory roles of KIBRA and PTPN14 in the Hippo pathway and their functions in cancer.

Targeting IL-17B-IL-17RB signaling with an anti-IL-17RB antibody blocks pancreatic cancer metastasis by silencing multiple chemokines

Pancreatic cancer has an extremely high mortality rate due to its aggressive metastatic nature. Resolving the underlying mechanisms will be crucial for treatment. Here, we found that overexpression of IL-17B receptor (IL-17RB) strongly correlated with postoperative metastasis and inversely correlated with progression-free survival in pancreatic cancer patients. Consistently, results from ex vivo experiments further validated that IL-17RB and its ligand, IL-17B, plays an essential role in pancreatic cancer metastasis and malignancy. Signals from IL-17B-IL-17RB activated CCL20/CXCL1/IL-8/TFF1 chemokine expressions via the ERK1/2 pathway to promote cancer cell invasion, macrophage and endothelial cell recruitment at primary sites, and cancer cell survival at distant organs. Treatment with a newly derived monoclonal antibody against IL-17RB blocked tumor metastasis and promoted survival in a mouse xenograft model. These findings not only illustrate a key mechanism underlying the highly aggressive characteristics of pancreatic cancer but also provide a practical approach to tackle this disease.

Pathology reporting of pancreatic cancer following neoadjuvant therapy: challenges and uncertainties

An increasing number of studies investigate the use of neoadjuvant treatment for ductal adenocarcinoma of the pancreas. While a strong rationale supports this approach, study results are difficult to interpret and compare due to marked variance in multiple aspects of study design and performance. Divergence in pathology examination and reporting as a cause for heterogeneity and incomparability of study results has not been brought into this discussion yet, despite the fact that several key outcome measures for neoadjuvant treatment are pathology-based. This article discusses areas of controversy and difficulty regarding the evaluation of the extent of residual tumour tissue, grading of tumour regression and assessment of the margins, and explains the important clinical implications of the present uncertainty and divergence in pathology practice.

Vascular endothelial growth factor accelerates establishment of a model of hepatic metastasis in Walker-256 tumor-bearing rats

BACKGROUND

Animal models of secondary liver cancer are limited by the time required for the development of hepatic metastases. The authors administered vascular endothelial growth factor (VEGF) to stimulate tumor growth in a model of hepatic metastasis.

METHODS

A 0.5 to 1.0 mm³ Walker-256 carcinosarcoma tumor tissue was implanted into the livers of 45 Sprague-Dawley rats, randomly assigned to 3 equal groups to receive daily injections (0.1 mL), for 1 week, of either normal saline (control group), 20 mg/L VEGF (VEGF-20 group) or 40 mg/L VEGF (VEGF-40 group). Tumor growth was assessed by magnetic resonance imaging after 3, 7 and 14 days, and overall survival was recorded.

RESULTS

Three days after implantation, no tumors were detected by magnetic resonance imaging in the control group. In contrast, tumors were observed in 50% of rats in the VEGF-20 group and 66.7% of rats in the VEGF-40 group (P < 0.05). By day 7, tumors were detected in 92.8% of rats in the VEGF-20 group, 86.7% of rats in the VEGF-40 group, but only 21.4% of rats in the control group (P < 0.05). Tumor size increased progressively, reaching 1.81 ± 0.08, 2.51 ± 0.12 and 2.67 ± 0.10 cm³ in the control, VEGF-20 and VEGF-40 groups, respectively, 14 days after implantation of tumor tissue. Median survival times were significantly shorter in the VEGF-40 group (15 days) than in the control and VEGF-20 groups (27 and 25, respectively) (both P < 0.05).

CONCLUSIONS

Daily VEGF injection (20 mg/L, 1 week) accelerates tumorigenesis without compromising survival, potentially extending the period in which experiments can be conducted in this model.

miR-193b directly targets STMN1 and uPA genes and suppresses tumor growth and metastasis in pancreatic cancer

Pancreatic cancer has the poorest prognosis among all cancer types, due to its late diagnosis and the lack of effective therapies. Therefore, identification of novel gene targets, which are differentially expressed in pancreatic cancer and functionally involved in the malignant phenotype, is critical to achieve early diagnosis and develop effective therapeutic strategies. microRNAs (miRNAs) are small non-coding RNAs, which negatively regulate the expression of their targets. Due to their various targets, miRNAs play a key role in a number of physiological processes and in oncogenesis. Therefore, investigating the role of miRNAs in tumor may contribute to the development of new diagnostic and therapeutic tools for various types of cancer, including pancreatic cancer. Here, we investigated the role of miR-193b in pancreatic cancer. Our data showed that the expression of miR-193b is markedly decreased in pancreatic cancer tissues compared to adjacent healthy tissues. The Panc-1 cell line transfected with the miR‑193b exhibited significantly decreased proliferative, migratory, and invasive ability compared to untransfected cells. Moreover, miR-193b inhibited the expression of stathmin 1 (STMN1) and urokinase-type plasminogen activator (uPA) in Panc-1 cells. These data suggest that miR-193b acts as a tumor suppressor in pancreatic cancer. Therefore, miR-193b may constitute a promising therapeutic agent for the suppression of pancreatic cancer cell growth and metastasis.

PTPN14 forms a complex with Kibra and LATS1 proteins and negatively regulates the YAP oncogenic function

The Hippo signaling pathway regulates cellular proliferation and survival, thus exerting profound effects on normal cell fate and tumorigenesis. Pivotal effectors of this pathway are YAP/TAZ, transcriptional co-activators whose dysfunction contributes to epithelial-to-mesenchymal transition and malignant transformation. Therefore, it is of great importance to decipher the mechanisms underlying the regulations of YAP/TAZ at various levels. Here we report that non-receptor tyrosine phosphatase 14 (PTPN14) interacts with the Kibra protein. The interaction between PTPN14 and Kibra is through the PPXY domain of PTPN14 and WW domain of Kibra. PTPN14 and Kibra can induce the LATS1 activation independently and cooperatively. Interestingly, activation of LATS1 by PTPN14 is dependent on the C terminus of PTPN14 and independent of the upstream mammalian STE20-like kinase (MST) proteins. Furthermore, we demonstrate that PTPN14 increases the LAST1 protein stability. Last, overexpression of Kibra rescues the increased cell migration and aberrant three-dimensional morphogenesis induced by knockdown of PTPN14, and this rescue is mediated through the activation of the upstream LATS1 kinase and subsequent cytoplasmic sequestration of YAP. In summary, our results indicate a potential regulatory role of PTPN14 in the Hippo pathway and demonstrate another layer of regulation in the YAP oncogenic function.

Reverse-phase protein array analysis to identify biomarker proteins in human pancreatic cancer

BACKGROUND

Pancreatic cancer is the fourth leading cause of cancer death in the United States. The high mortality rate of patients with pancreatic cancer is primarily due to the difficulty of early diagnosis and a lack of effective therapies. There is an urgent need to discover novel molecular targets for early diagnosis and new therapeutic approaches to improve the clinical outcome of this deadly disease.

AIM

We utilized the reverse-phase protein assay (RPPA) to identify differentially expressed biomarker proteins in tumors and matched adjacent, normal-appearing tissue samples from 15 pancreatic cancer patients.

METHODS

The antibody panel used for the RPPA included 130 key proteins involved in various cancer-related pathways. The paired t test was used to determine the significant differences between matched pairs, and the false discovery rate-adjusted p values were calculated to take into account the effect of multiple comparisons.

RESULTS

After correcting for multiple comparisons, we found 19 proteins that had statistically significant differences in expression between matched pairs. However, only four (AKT, β-catenin, GAB2, and PAI-1) of them met the conservative criteria (both a q value <0.05 and a fold-change of ≥3/2 or ≤2/3) to be considered differentially expressed. Overexpression of AKT, β-catenin, and GAB2 in pancreatic cancer tissues identified by RPPA has also been further confirmed by western blot analysis. Further analysis identified several significantly associated canonical pathways and overrepresented network functions.

CONCLUSION

GAB2, a newly identified protein in pancreatic cancer, may provide additional insight into this cancer's pathogenesis. Future studies in a larger population are warranted to further confirm our results.

Src activity is increased in gastrointestinal stromal tumors--analysis of associations with clinical and other molecular tumor characteristics

BACKGROUND

Increased activity of Src has been found in several human cancers, and often is associated with poor clinical outcome. The present study aimed to determine whether Src activity is increased in gastrointestinal stromal tumors (GIST), and whether it correlates with established tumor or patient characteristics and prognosis.

METHODS

Tumor/normal tissues of 29 patients were analyzed for Src activity/protein with kinase assays, and for VEGF/VEGFR with immunohistochemical staining.

RESULTS

Src activity was higher in tumor than in normal tissues (P = 0.093). However, when imatinib responders were excluded from the analyses, it was significantly higher in the tumor tissue (P = 0.017). Additionally, it was higher in primary compared to recurrent tumors or metastasis (P = 0.04). Univariate survival analysis showed a longer overall survival for patients with high Src activity (P = 0.038). In multivariate analysis, the response to imatinib treatment was the only survival-influencing factor (P = 0.072).

CONCLUSIONS

Src activity is increased in GIST. In contrast to most other tumor entities, it does not correlate with poor clinical outcome, but decreases during the progression from primary tumor to recurrence and metastasis, especially under therapy with imatinib. Additionally, our results show that higher Src activity is associated with longer overall survival.

Genomic copy number imbalances associated with bone and non-bone metastasis of early-stage breast cancer

The aim of this study is to identify and validate copy number aberrations in early-stage primary breast tumors associated with bone or non-bone metastasis. Whole-genome molecular inversion probe arrays were used to evaluate copy number imbalances (CNIs) in breast tumors from 960 early-stage patients with information about site of metastasis. The CoxBoost algorithm was used to select metastasis site-related CNIs and to fit a Cox proportional hazards model. Gains at 1q41 and 1q42.12 and losses at 1p13.3, 8p22, and Xp11.3 were significantly associated with bone metastasis. Gains at 2p11.2, 3q21.3-22.2, 3q27.1, 10q23.1, and 14q13.2-3 and loss at 7q21.11 were associated with non-bone metastasis. To examine the joint effect of CNIs and clinical predictors, patients were stratified into three risk groups (low, intermediate, and high) based on the sum of predicted linear hazard ratios. For bone metastasis, the hazard (95 % confidence interval) for the low-risk group was 0.32 (0.11-0.92) compared to the intermediate-risk group and 2.99 (1.74-5.11) for the high-risk group. For non-bone metastasis, the hazard for the low-risk group was 0.34 (0.17-0.66) and 2.33 (1.59-3.43) for the high-risk group. The prognostic value of loss at 8p22 for bone metastasis and gains at 10q23.1 for non-bone metastasis, and gain at 11q13.5 for both bone and non-bone metastases were externally validated in 335 breast tumors pooled from four independent cohorts. Distinct CNIs are independently associated with bone and non-bone metastasis for early-stage breast cancer patients across cohorts. These data warrant consideration for tailoring surveillance and management of metastasis risk.

Adipose tissue-derived stem cells promote pancreatic cancer cell proliferation and invasion

To explore the effects of adipose tissue-derived stem cells (ADSCs) on the proliferation and invasion of pancreatic cancer cells in vitro and the possible mechanism involved, ADSCs were cocultured with pancreatic cancer cells, and a cell counting kit (CCK-8) was used to detect the proliferation of pancreatic cancer cells. ELISA was used to determine the concentration of stromal cell-derived factor-1 (SDF-1) in the supernatants. RT-PCR was performed to detect the expression of the chemokine receptor CXCR4 in pancreatic cancer cells and ADSCs. An in vitro invasion assay was used to measure invasion of pancreatic cancer cells. SDF-1 was detected in the supernatants of ADSCs, but not in pancreatic cancer cells. Higher CXCR4 mRNA levels were detected in the pancreatic cancer cell lines compared with ADSCs (109.3±10.7 and 97.6±7.6 vs 18.3±1.7, respectively; P<0.01). In addition, conditioned medium from ADSCs promoted the proliferation and invasion of pancreatic cancer cells, and AMD3100, a CXCR4 antagonist, significantly downregulated these growth-promoting effects. We conclude that ADSCs can promote the proliferation and invasion of pancreatic cancer cells, which may involve the SDF-1/CXCR4 axis.

Macrophages mediate gemcitabine resistance of pancreatic adenocarcinoma by upregulating cytidine deaminase

Resistance to pharmacologic agents used in chemotherapy is common in most human carcinomas, including pancreatic ductal adenocarcinoma (PDA), which is resistant to almost all drugs, including gemcitabine, a nucleoside analog used as a first-line treatment. Poor survival rates of PDA patients have, therefore, not changed much over 4 decades. Recent data indicated that tumor-associated macrophages (TAMs), which are abundant in the microenvironment of several tumors, including PDA, secrete pro-tumorigenic factors that contribute to cancer progression and dissemination. In this study, we show for the first time that TAMs can also induce chemoresistance of PDA by reducing gemcitabine-induced apoptosis. Macrophages co-cultured with cancer cells or TAM-conditioned medium significantly reduced apoptosis and activation of the caspase-3 pathway during gemcitabine treatment. In vivo PDA models of mice, which have reduced macrophage recruitment and activation, demonstrated improved response to gemcitabine compared with controls. Similarly, inhibition of monocytes/macrophages trafficking by a CSF1-receptor antagonist GW2580 augmented the effect of gemcitabine in a transgenic mouse PDA model that was resistant to gemcitabine alone. Analysis of multiple proteins involved in gemcitabine delivery and metabolism revealed that TAMs induced upregulation of cytidine deaminase (CDA), the enzyme that metabolizes the drug following its transport into the cell. Decreasing CDA expression by PDA cells blocked the protective effect of TAMs against gemcitabine. These results provide the first evidence of a paracrine effect of TAMs, which mediates acquired resistance of cancer cells to chemotherapy. Modulation of macrophage trafficking or inhibition of CDA may offer a new strategy for augmenting the response of PDA to chemotherapy.

Melatonin inhibits the expression of vascular endothelial growth factor in pancreatic cancer cells

OBJECTIVE

To investigate the effects of melatonin on cellular proliferation and endogenous vascular endothelial growth factor (VEGF) expression in pancreatic carcinoma cells (PANC-1).

METHODS

PANC-1 cells were cultured for this study. The secreted VEGF concentration in the culture medium was determined using ELISA method, VEGF production in the tumor cells was detected by immunocytochemistry, and VEGF mRNA expression was determined by RT-PCR.

RESULTS

Higher melatonin concentrations significantly inhibited cellular proliferation, with 1 mmol/L concentration exhibiting the highest inhibitory effect (P<0.01). VEGF concentrations in the cell culture supernatants and intra-cellules were all significantly reduced after melatonin (1 mmol/L) incubation (P<0.05). VEGF mRNA expression decreased markedly in a time-dependent manner during the observation period (P<0.05).

CONCLUSIONS

High melatonin concentrations markedly inhibited the proliferation of pancreatic carcinoma cells. The endogenous VEGF expression was also suppressed by melatonin incubation.

miR-148b functions as a tumor suppressor in pancreatic cancer by targeting AMPKα1

miRNAs are small noncoding RNAs that participate in a variety of biologic processes, and dysregulation of miRNA is always associated with cancer development and progression. Aberrant expression of miR-148b has been found in some types of cancer, but its expression and potential biologic role in pancreatic cancer are still largely unknown. In this study, our data showed that miR-148b was significantly downregulated in 48 pairs of human pancreatic cancer tissues and five cell lines. Furthermore, the deregulated miR-148b was correlated with increased tumor size, late tumor-node-metastasis stage, lymphatic invasion, distant metastasis, and worse prognosis in pancreatic cancer. Functional studies indicated overexpression of miR-148b dramatically suppressed the growth of cancer cells, attributable to induction of apoptosis and cell-cycle arrest at S-phase. Meanwhile, miR-148b remarkably inhibited invasion and enhanced chemosensitivity of pancreatic cancer cells. Moreover, ectopic expression of miR-148b was able to inhibit tumorigenicity in nude mice. Further studies revealed that AMPKα1 might be the direct target gene of miR-148b, and overexpressed AMPKα1 inversely correlated with miR-148b in pancreatic cancer. Silencing of AMPKα1 with RNA interference inhibited the growth of pancreatic cancer cells in vitro and in vivo and also induced apoptosis, cell-cycle arrest, and inhibited invasion of cancer cells, which is consistent with the effects of miR-148b overexpression. In conclusion, miR-148b can inhibit cell proliferation, invasion, and enhance chemosensitivity of pancreatic cancer by targeting AMPKα1. Our present results implicate the potential effects of miR-148b on prognosis and treatment of pancreatic cancer.

Evaluation of the Metabolic Response to Cyclopamine Therapy in Pancreatic Cancer Xenografts Using a Clinical PET-CT System

OBJECTIVES

We analyzed the effects of anti-hedgehog signaling on the (18)F-FDG uptake of pancreatic cancer xenografts (PCXs) using a clinically implemented positron emission tomography (PET)-computer tomography (CT) scanner with high-resolution reconstruction.

METHODS

PCXs from two pancreatic cancer cell lines were developed subcutaneously in nude mice and injected intraperitoneally with a low dose of cyclopamine for 1 week. (18)F-FDG PET-CT was performed using a new-generation clinical PET-CT scanner with minor modifications of the scanning protocol to adapt for small-animal imaging. The data set was reconstructed and quantified using a three-dimensional workstation.

RESULTS

MiaPaCa-2 cells, which respond to cyclopamine, showed decreased (18)F-FDG uptake without a change in tumor size. For hip tumors, the maximum standardized uptake value (SUV(max)) was reduced by -24.5 ± 9.2%, the average SUV (SUV(avg)) by -33.5 ± 7.0%, and the minimum SUV (SUV(min)) by -54.4 ± 11.5% (P < .05). For shoulder tumors, SUV(max) was reduced by -14.7 ± 7.5%, SUV(avg) by -12.6 ± 6.3, and SUV(min) by -30.3 ± 16.7% (P < .05). Capan-1 cells, which do not respond to cyclopamine, did not show significant SUV changes.

CONCLUSIONS

The new generations of clinically implemented PET-CT scanners with high-resolution reconstruction detect a minimal response of PCX to low-dose short-term cyclopamine therapy without changes in tumor size and offer potential for preclinical translational imaging.

S100P is a metastasis-associated gene that facilitates transendothelial migration of pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is the 5th most common cause of cancer death in the UK and the 4th in the US. The vast majority of deaths following pancreatic cancer are due to metastatic spread, hence understanding the metastatic process is vital for identification of critically needed novel therapeutic targets. An enriched set of 33 genes differentially expressed in common between primary PDAC and liver metastases, when compared to normal tissues, was obtained through global gene expression profiling. This metastasis-associated gene set comprises transcripts from both cancer (S100P, S100A6, AGR2, etc.) and adjacent stroma (collagens type I, III, and V, etc.), thus reinforcing the concept of a continuous crosstalk between the two compartments in both primary tumours and their metastases. The expression of S100P, SFN, VCAN and collagens was further validated in additional primary PDACs and matched liver metastatic lesions, while the functional significance of one of the most highly expressed genes, S100P, was studied in more detail. We show that this protein increases the transendothelial migration of PDAC cancer cells in vitro, which was also confirmed in vivo experiments using a zebrafish embryo model. Thus S100P facilitates cancer cell intravasation/extravasation, critical steps in the hematogenous dissemination of pancreatic cancer cells.

Molecular markers associated with outcome and metastasis in human pancreatic cancer

Background

Pancreatic ductal adenocarcinoma (PDAC) is a heterogeneous cancer in which differences in survival rates might be related to a variety in gene expression profiles. Although the molecular biology of PDAC begins to be revealed, genes or pathways that specifically drive tumour progression or metastasis are not well understood.

Methods

We performed microarray analyses on whole-tumour samples of 2 human PDAC subpopulations with similar clinicopathological features, but extremely distinct survival rates after potentially curative surgery, i.e. good outcome (OS and DFS > 50 months, n = 7) versus bad outcome (OS < 19 months and DFS < 7 months, n = 10). Additionally, liver- and peritoneal metastases were analysed and compared to primary cancer tissue (n = 11).

Results

The integrin and ephrin receptor families were upregulated in all PDAC samples, irrespective of outcome, supporting an important role of the interaction between pancreatic cancer cells and the surrounding desmoplastic reaction in tumorigenesis and cancer progression. Moreover, some components such as ITGB1 and EPHA2 were upregulated in PDAC samples with a poor outcome, Additionally, overexpression of the non-canonical Wnt/β-catenin pathway and EMT genes in PDAC samples with bad versus good outcome suggests their contribution to the invasiveness of pancreatic cancer, with β-catenin being also highly upregulated in metastatic tissue.

Conclusions

Components of the integrin and ephrin pathways and EMT related genes, might serve as molecular markers in pancreatic cancer as their expression seems to be related with prognosis.

A novel animal model for in vivo study of liver cancer metastasis

AIM: To establish an animal model with human hepatocyte-repopulated liver for the study of liver cancer metastasis.

METHODS: Cell transplantation into mouse livers was conducted using alpha-fetoprotein (AFP)-producing human gastric cancer cells (h-GCCs) and h-hepatocytes as donor cells in a transgenic mouse line expressing urokinase-type plasminogen activator (uPA) driven by the albumin enhancer/promoter crossed with a severe combined immunodeficient (SCID) mouse line (uPA/SCID mice). Host mice were divided into two groups (A and B). Group A mice were transplanted with h-GCCs alone, and group B mice were transplanted with h-GCCs and h-hepatocytes together. The replacement index (RI), which is the ratio of transplanted h-GCCs and h-hepatocytes that occupy the examined area of a histological section, was estimated by measuring h-AFP and h-albumin concentrations in sera, respectively, as well as by immunohistochemical analyses of h-AFP and human cytokeratin 18 in histological sections.

RESULTS: The h-GCCs successfully engrafted, repopulated, and colonized the livers of mice in group A (RI = 22.0% ± 2.6%). These mice had moderately differentiated adenocarcinomatous lesions with disrupted glandular structures, which is a characteristics feature of gastric cancers. The serum h-AFP level reached 211.0 ± 142.2 g/mL (range, 7.1-324.2 g/mL). In group B mice, the h-GCCs and h-hepatocytes independently engrafted, repopulated the host liver, and developed colonies (RI = 12.0% ± 6.8% and 66.0% ± 12.3%, respectively). h-GCC colonies also showed typical adenocarcinomatous glandular structures around the h-hepatocyte-colonies. These mice survived for the full 56 day-study and did not exhibit any metastasis of h-GCCs in the extrahepatic regions during the observational period. The mice with an h-hepatocyte-repopulated liver possessed metastasized h-GCCs and therefore could be a useful humanized liver animal model for studying liver cancer metastasis in vivo.

CONCLUSION: A novel animal model of human liver cancer metastasis was established using the uPA/SCID mouse line. This model could be useful for in vivo testing of anti-cancer drugs and for studying the mechanisms of human liver cancer metastasis.

YAP modifies cancer cell sensitivity to EGFR and survivin inhibitors and is negatively regulated by the non-receptor type protein tyrosine phosphatase 14

The Yes-associated protein (YAP) is a transcriptional factor involved in tissue development and tumorigenesis. Although YAP has been recognized as a key element of the Hippo signaling pathway, the mechanisms that regulate YAP activities remain to be fully characterized. In this study, we demonstrate that the non-receptor type protein tyrosine phosphatase 14 (PTPN14) functions as a negative regulator of YAP. We show that YAP forms a protein complex with PTPN14 through the WW domains of YAP and the PPXY motifs of PTPN14. In addition, PTPN14 inhibits YAP-mediated transcriptional activities. Knockdown of YAP sensitizes cancer cells to various anti-cancer agents, such as cisplatin, the EGFR tyrosine kinase inhibitor erlotinib, and the small-molecule antagonist of survivin, S12. YAP-targeted modalities may be used in combination with other cancer drugs to achieve maximal therapeutic effects.

PTPN14 interacts with and negatively regulates the oncogenic function of YAP

The Hippo signaling pathway regulates cellular proliferation and survival, thus exerting profound effects on normal cell fate and tumorigenesis. The pivotal effector of this pathway is YAP, a transcriptional co-activator amplified in mouse and human cancers where it promotes epithelial-to-mesenchymal transition and malignant transformation. Here, we report a novel regulatory mechanism for the YAP oncogenic function via direct interaction with non-receptor tyrosine phosphatase 14 (PTPN14) through the WW domain of YAP and the PPxY domain of PTPN14. We also found that YAP is a direct substrate of PTPN14. In addition, luciferase reporter assay showed that the inhibition of the YAP transcriptional co-activator function by PTPN14 is mediated through their protein interactions and may result from an increase in the inactive cytoplasmic form of YAP. Last, knockdown of PTPN14 induces the nuclear retention of YAP and increases the YAP-dependent cell migration. In summary, our results indicate a potential regulatory role of PTPN14 on YAP and demonstrate a novel mechanism in YAP regulation.

Tumour growth is more dispersed in pancreatic head cancers than in rectal cancer: implications for resection margin assessment

AIMS

The UK definition of microscopic resection margin involvement (R1) in pancreatic head cancer, based on tumour lying <1 mm from the margin, has been adopted from rectal cancer, but has never been validated. The aim of this study was to assess the adequacy of the R1 definition for pancreatic head cancers by comparing the growth patterns of rectal (RC), pancreatic (PC), ampullary (AC) and distal bile duct (DBC) adenocarcinomas.

METHODS AND RESULTS

Distances between tumour cells and tumour cell density in the tumour centre and periphery were quantified by Minimum Spanning Tree (MST) analysis in 10 cases of the four cancer groups. In RC, the MST distance was similar throughout the entire width of the tumour, whereas in PC, DBC and AC it was significantly larger at the periphery than at the tumour centre (P ≤ 0.003). While results were similar for PC and DBC, however, distances at the centre and periphery of both cancers were larger compared to AC (P ≤ 0.046). Tumour cell density dropped at the periphery of PC to 31% of that at the centre, compared to 83% in RC (P < 0.0002).

CONCLUSIONS

Tumour growth in pancreatic head cancers is more dispersed than in RC, particularly in the tumour periphery. Revision of the R1 definition for pancreatic head cancer may therefore need to be considered.

Mouse models of pancreatic cancer

Pancreatic cancer is one of the most lethal of human malignancies ranking 4th among cancer-related death in the western world and in the United States, and potent therapeutic options are lacking. Although during the last few years there have been important advances in the understanding of the molecular events responsible for the development of pancreatic cancer, currently specific mechanisms of treatment resistance remain poorly understood and new effective systemic drugs need to be developed and probed. In vivo models to study pancreatic cancer and approach this issue remain limited and present different molecular features that must be considered in the studies depending on the purpose to fit special research themes. In the last few years, several genetically engineered mouse models of pancreatic exocrine neoplasia have been developed. These models mimic the disease as they reproduce genetic alterations implicated in the progression of pancreatic cancer. Genetic alterations such as activating mutations in KRas, or TGFb and/or inactivation of tumoral suppressors such as p53, INK4A/ARF BRCA2 and Smad4 are the most common drivers to pancreatic carcinogenesis and have been used to create transgenic mice. These mouse models have a spectrum of pathologic changes, from pancreatic intraepithelial neoplasia to lesions that progress histologically culminating in fully invasive and metastatic disease and represent the most useful preclinical model system. These models can characterize the cellular and molecular pathology of pancreatic neoplasia and cancer and constitute the best tool to investigate new therapeutic approaches, chemopreventive and/or anticancer treatments. Here, we review and update the current mouse models that reproduce different stages of human pancreatic ductal adenocarcinoma and will have clinical relevance in future pancreatic cancer developments.

Melatonin prevents human pancreatic carcinoma cell PANC-1-induced human umbilical vein endothelial cell proliferation and migration by inhibiting vascular endothelial growth factor expression

Melatonin is an important natural oncostatic agent, and our previous studies have found its inhibitory action on tumor angiogenesis, but the mechanism remains unclear. It is well known that vascular endothelial growth factor (VEGF) plays key roles in tumor angiogenesis and has become an important target for antitumor therapy. Pancreatic cancer is a representative of the most highly vascularized and angiogenic solid tumors, which responds poorly to chemotherapy and radiation. Thus, seeking new treatment strategies targeting which have anti-angiogenic capability is urgent in clinical practice. In this study, a co-culture system between human umbilical vein endothelial cells (HUVECs) and pancreatic carcinoma cells (PANC-1) was used to investigate the direct effect of melatonin on the tumor angiogenesis and its possible action on VEGF expression. We found HUVECs exhibited an increased cell proliferation and cell migration when co-cultured with PANC-1 cells, but the process was prevented when melatonin added to the incubation medium. Melatonin at concentrations of 1 μm and 1 mm inhibited the cell proliferation and migration of HUVECs and also decreased both the VEGF protein secreted to the cultured medium and the protein produced by the PANC-1 cells. In addition, the VEGF mRNA expression was also down-regulated by melatonin. Taken together, our present study shows that melatonin at pharmacological concentrations inhibited the elevated cell proliferation and cell migration of HUVECs stimulated by co-culturing them with PANC-1 cells; this was associated with a suppression of VEGF expression in PANC-1 cells.

Gene expression signature of advanced pancreatic ductal adenocarcinoma using low density array on endoscopic ultrasound-guided fine needle aspiration samples

AIMS

The purpose of this study was to investigate the clinical feasibility and utility of low-density array analysis on samples obtained from endoscopic ultrasound-guided fine needle aspiration biopsy in locally advanced and/or metastatic pancreatic ductal adenocarcinoma and chronic pancreatitis.

PATIENTS AND METHODS

In this prospective multicenter study, we quantified candidate gene expression in biopsies sampled from 44 locally advanced and/or metastatic pancreatic carcinoma and from 17 pseudotumoural chronic pancreatitis using dedicated low-density array microfluidic plates.

RESULTS

We first demonstrated that 18S gene expression is stable and comparable in normal pancreas and pancreatic cancer tissues. Next, we found that eight genes (S100P, PLAT, PLAU, MSLN, MMP-11, MMP-7, KRT7, KRT17) were significantly over expressed in pancreatic cancer samples when compared to pseudotumoural chronic pancreatitis (p value ranging from 0.0007 to 0.0215): Linear discriminative analysis identified S100P, PLAT, MSLN, MMP-7, KRT7 as highly explicative variables. The area under receiver operating curve establishes the clinical validity of the potential diagnostic markers identified in this study (values ranging from 0.69 to 0.76). In addition, combination of S100P and KRT7 gave better diagnosis performances (Area Under Receiver Operating Curve 0.81, sensitivity 81%, specificity 77%).

CONCLUSION

We demonstrate that molecular studies on EUS-guided FNA material are feasible for the identification and quantification of markers in PDAC patients diagnosed with non-resectable tumours. Using low-density array, we isolated a molecular signature of advanced pancreatic carcinoma including mostly cancer invasion-related genes. This work stems for the use of novel biomarkers for the molecular diagnosis of patient with solid pancreatic masses.

The oncogenetic role of microRNA-31 as a potential biomarker in oesophageal squamous cell carcinoma

miR-31 (microRNA-31) is frequently altered in numerous cancers. The aim of the present study was to investigate the role of miR-31 in ESCC (oesophageal squamous cell carcinoma). We measured miR-31 in 45 paired ESCC tissues and 523 serum samples using real-time RT (reverse transcription)-PCR. The serum samples were divided into a discovery group (120 ESCCs and 121 normal controls), a validation group (81 ESCCs and 81 controls), and a final group comprising six other common tumours (colorectal, liver, cervical, breast, gastric and lung cancers; total n=120). A Mann-Whitney U test and Wilcoxon matched-pairs test were used for the statistics. miR-31 was up-regulated in 77.8% of the ESCC tissues. Serum miR-31 levels in ESCC patients were significantly higher than in normal controls (P<0.001). It yielded an ROC (receiver operating characteristic) AUC (area under the curve) of 0.902 [95% CI (confidence interval), 0.857-0.936] in the discovery group and a similar result in the validation group [ROC AUC, 0.888 (95% CI, 0.819-0.939)]. Patients with high-levels of serum miR-31 also had a poorer prognosis in relapse-free survival (P=0.001) and tumour-specific survival (P=0.005). In vitro studies showed that miR-31 promoted ESCC colony formation, migration and invasion. Luciferase reporter and Western blot assays confirmed that three tumour suppressor genes, namely EMP1 (epithelial membrane protein 1), KSR2 (kinase suppressor of ras 2) and RGS4 (regulator of G-protein signalling 4), were targeted by miR-31. We conclude that miR-31 plays oncogenetic functions and can serve as a potential diagnostic and prognostic biomarker for ESCC.

Modelling genetic and clinical heterogeneity in epithelial ovarian cancers

The biology underlying early-stage epithelial ovarian cancer (EOC) development is poorly understood. Identifying biomarkers associated with early-stage disease could have a significant impact on reducing mortality. Here, we describe establishment of a three-dimensional (3D) in vitro genetic model of EOC initiation and early-stage neoplastic progression. Normal primary ovarian epithelial (POE) cells, immortalized using hTERT (immortalised ovarian epithelial [IOE] cells), were partially transformed by overexpressing the CMYC oncogene (IOE(CMYC) cells). Subsequent expression of mutant alleles of KRAS (KRAS(G12V)) or BRAF (BRAF(V600E)) created double-mutant lines (IOE(CMYC.KRAS) and IOE(CMYC.BRAF)). The transformed phenotype of IOE(CMYC) cells was further enhanced in concert with KRAS(G12V)/BRAF(V600E) expression, as in vitro analyses indicated that IOE(CMYC) cells had undergone morphological and phenotypic changes characteristic of neoplastic progression. When cultured as 3D spheroids, IOE cells underwent growth arrest, reminiscent of nonproliferative, unstimulated POE in vivo. In contrast, IOSE(CMYC+BRAF/KRAS) cells formed highly proliferative, poly-aggregate spheroid structures, showing increased expression of the Wilms tumour 1 tumourigenic marker and MIB1 proliferation marker. Transcriptomic analyses identified different gene expression profiles between the different cell lines and novel candidate genes (e.g. RGS4, CTGF and THBS1) that are somatically altered in EOCs. Gene expression signatures were compared with signatures from primary EOCs; tumours with IOE(CMYC) 'like' signatures were more likely to be high grade (P = 0.018); tumours with BRAF signatures were associated with improved relapse-free survival (P = 0.003). In conclusion, we have established in vitro 3D models of early-stage EOCs, which reflect genetic and phenotypic heterogeneity of the disease. Molecular genetic characteristics of these models correlated with molecular and clinical features of primary EOCs.

Transient gene silencing of galectin-3 suppresses pancreatic cancer cell migration and invasion through degradation of β-catenin

Pancreatic cancer is a leading cause of cancer-related mortality and often has a poor prognosis because of its late diagnosis, aggressive local invasion, early metastasis and poor response to chemotherapy. The chemotherapeutic agent gemcitabine is effective for treating advanced pancreatic cancer, but its efficacy remains less than satisfactory. It is expected that further investigation of pancreatic cancer cell invasion and development of strategies to block this process should improve the disease prognosis. In this study, we tested our hypothesis that galectin-3 (gal-3), a multifunctional member of the β-galactoside-binding protein family, may regulate pancreatic cancer cell motility and silencing of it inhibit cell motility. Previous studies demonstrated that this protein is associated with tumor cell adhesion, proliferation, differentiation, angiogenesis, apoptosis and metastasis. Here, we used gal-3 small interfering RNA (siRNA) to silence its expression in various pancreatic cancer cell lines to determine whether gal-3 regulates cell proliferation, migration and invasion in vitro. We found that silencing gal-3 reduced cellular migration and invasion, but failed to affect proliferation. In gal-3 siRNA-transfected cells, we detected a decrease in β-catenin expression, an important signal for cancer cell invasion, which was caused by downregulation of phosphorylated Akt and GSK-3β. We also found that matrix metalloproteinase (MMP)-2 expression was reduced by gal-3 silencing. These results indicate that gal-3-mediated invasion via MMP-2 regulated by β-catenin degradation is initiated by Akt phosphorylation in pancreatic cancer cells. Our results suggest that gal-3 can be a novel therapeutic target in pancreatic cancer.

Chemokines in tumor-associated angiogenesis

Tumor growth is dependent on several key factors. Apart from immune escape and an efficient blockade of apoptotic signals, tumors require oxygen and nutrients to grow past a diameter of 2 microm. Therefore, it is of vital importance for the tumor to facilitate tumor-associated angiogenesis, e.g., the de novo formation of new blood vessels. In addition to established and key angiogenic factors, such as vascular endothelial growth factor, chemokines, a superfamily of cytokine-like proteins that bind to seven transmembrane-spanning G-protein-coupled receptors, have been associated with angiogenesis under homeostatic conditions. Chemokines were initially identified as key factors that control the directional migration of leukocytes, stem cells and cancer cells in vitro and which critically regulate their trafficking in vivo. Recently their role in establishing a favorable microenvironment for tumor-associated angiogenesis, a process that requires complex bidirectional interactions of the tumor and associated vessels, has been the focus of research. Chemokine-promoted angiogenesis not only facilitates tumor growth by supplying nutrients and oxygen but it is also a prerequisite to tumor metastasis. Hence, the pharmacologic control of tumor angiogenesis presents a promising strategy for novel anticancer therapeutics. Here, we discuss the current pathogenetic concepts of tumor-associated angiogenesis in the context of chemokines and their receptors and highlight promising therapeutic strategies.

BNIP3 subfamily BH3-only proteins: mitochondrial stress sensors in normal and pathological functions

The BNIP3 subfamily of BH3-only proteins consists of BNIP3 and BNIP3-like (BNIP3L) proteins. These proteins form stable homodimerization complexes that localize to the outer membrane of the mitochondria after cellular stress. This promotes either apoptotic or non-apoptotic cell death such as autophagic cell death. Although the mammalian cells contain both members of this subfamily, the genome of Caenorhabditis elegans codes for a single BNIP3 ortholog, ceBNIP3, which shares homology in the transmembrane (TM) domain and in a conserved region close to the BH3 domain of mammalian BNIP3 protein. The cell death activities of BNIP3 and BNIP3L are determined by either the BH3 domain or the C-terminal TM domain. The TM domain of BNIP3 is unique, as it is capable of autonomous stable dimerization and contributes to mitochondrial localization of BNIP3. In knockout mouse models, BNIP3L was shown to be essential for normal erythrocyte differentiation and hematopoietic homeostasis, whereas BNIP3 plays a role in cellular responses to ischemia/reperfusion injury in the heart. Both BNIP3 and BNIP3L play a role in cellular responses to stress. Under hypoxia, both BNIP3 and BNIP3L expression levels are elevated and contribute to hypoxia-induced cell death. In addition, these proteins play critical roles in disease states. In heart disease, both BNIP3 and BNIP3L play a critical role in cardiomyocyte cell death following ischemic and non-ischemic injuries. In cancer, expression of BNIP3 and BNIP3L is downregulated by promoter hypermethylation or by homozygous deletion of the gene locus in certain cancers, whereas their expression was increased in other cancers. In addition, BNIP3 expression has been correlated with poor prognosis in some cancers. The results reviewed here suggest that BNIP3 and BNIP3L may be novel therapeutic targets for intervention because of their pathological roles in regulating cell death in disease states.

Prognostic signature for pancreatic cancer: are we close?

Pancreatic cancer is a deadly disease with an annual incidence rate nearly equal to its mortality rate. Incremental improvement in outcome has been seen in the last 25 years, illustrating the critical need for novel approaches and intensive research investment. Expression profiling of pancreatic cancers has led to an explosion of informative gene-expression changes and the identification of new diagnostic and prognostic markers. However, the search for genes that are of functional significance in these large datasets continues to be much more challenging. One approach to focusing on genes or pathways that are likely to be more biologically relevant is to study those that are of prognostic significance. This review will therefore focus on the advantages of a prognostic gene signature for pancreatic cancer, the advances that have been made thus far, the approaches used and the challenges that remain.