Surgical and medical therapy for pancreatic carcinoma

Riluzole regulates pancreatic cancer cell metabolism by suppressing the Wnt-β-catenin pathway

Most cancer cells rely on aerobic glycolysis to support uncontrolled proliferation and evade apoptosis. However, pancreatic cancer cells switch to glutamine metabolism to survive under hypoxic conditions. Activation of the Wnt/β-catenin pathway induces aerobic glycolysis by activating enzymes required for glucose metabolism and regulating the expression of glutamate transporter and glutamine synthetase. The results demonstrate that riluzole inhibits pancreatic cancer cell growth and has no effect on human pancreatic normal ductal epithelial cells. RNA-seq experiments identified the involvement of Wnt and metabolic pathways by riluzole. Inhibition of Wnt-β-catenin/TCF-LEF pathway by riluzole suppresses the expression of PDK, MCT1, cMyc, AXIN, and CyclinD1. Riluzole inhibits glucose transporter 2 expression, glucose uptake, lactate dehydrogenase A expression, and NAD + level. Furthermore, riluzole inhibits glutamate release and glutathione levels, and elevates reactive oxygen species. Riluzole disrupts mitochondrial homeostasis by inhibiting Bcl-2 and upregulating Bax expression, resulting in a drop of mitochondrial membrane potential. Finally, riluzole inhibits pancreatic cancer growth in KPC (Pdx1-Cre, LSL-Trp53R172H, and LSL-KrasG12D) mice. In conclusion, riluzole can inhibit pancreatic cancer growth by regulating glucose and glutamine metabolisms and can be used to treat pancreatic cancer.

Ethanol exposure of human pancreatic normal ductal epithelial cells induces EMT phenotype and enhances pancreatic cancer development in KC (Pdx1-Cre and LSL-KrasG12D ) mice

Alcohol is a risk factor for pancreatic cancer. However, the molecular mechanism by which chronic alcohol consumption influences pancreatic cancer development is not well understood. We have recently demonstrated that chronic ethanol exposure of pancreatic normal ductal epithelial cells (HPNE) induces cellular transformation by generating cancer stem cells (CSCs). Here, we examined whether chronic ethanol treatment induces epithelial–mesenchymal transition in HPNE cells and promotes pancreatic cancer development in KC (Pdx1‐Cre, and LSL‐Kras^G12D) mice. Our data demonstrate that chronic ethanol exposure of HPNE cells induces SATB2 gene and those cells became highly motile. Ethanol treatment of HPNE cells results in downregulation of E‐Cadherin and upregulation of N‐Cadherin, Snail, Slug, Zeb1, Nanog and BMI‐1. Suppression of SATB2 expression in ethanol‐transformed HPNE cells inhibits EMT phenotypes. KC mice fed with an ethanol‐containing diet show enhanced pancreatic cancer growth and development than those fed with a control diet. Pancreas isolated from KC mice fed with an ethanol‐containing diet show higher expression of stem cell markers (CD133, CD44, CD24), pluripotency‐maintaining factors (cMyc, KLF4, SOX‐2, and Oct‐4), N‐Cadherin, EMT‐transcription factors (Snail, Slug, and Zeb1), and lower expression of E‐cadherin than those isolated from mice fed with a control diet. Furthermore, pancreas isolated from KC mice fed with an ethanol‐containing diet show higher expression of inflammatory cytokines (TNF‐α, IL‐6, and IL‐8) and PTGS‐2 (COX‐2) gene than those isolated from mice fed with a control diet. These data suggest that chronic alcohol consumption may contribute to pancreatic cancer development by generating inflammatory signals and CSCs.

Pancreatic-cancer-cell-derived trefoil factor 2 impairs maturation and migration of human monocyte-derived dendritic cells in vitro

Pancreatic cancer is a challenging disease with a high mortality rate. While the importance of crosstalk between cancer and immune cells has been well documented, the understanding of this complex molecular network is incomplete. Thus, identification of the secreted proteins contributing to the immunosuppressive microenvironment in pancreatic cancer is crucial for effective diagnosis and/or therapy. We utilized a public microarray dataset (GSE16515) from the Gene Expression Omnibus database to identify genes for secreted proteins in pancreatic cancer. RT-PCR and ELISA of the pancreatic cancer cell lines validated the cellular origin of the selected genes. For functional assay of the selected proteins, we utilized human-monocyte-derived dendritic cells (DCs). From the list of the secreted proteins, trefoil factor 2 (TFF2) was further examined as a potential chemokine/cytokine. While TFF2 did not significantly affect the phenotypic maturation and the allostimulatory capacity of DCs, TFF2 preferentially attracted immature (but not mature) DCs and inhibited their endocytic activity. Our data suggest that TFF2 from pancreatic cancer cells may attract immature DCs and affect the initial stage of DC maturation, thereby contributing to the induction of immune tolerance against pancreatic cancer.

Omega-3 Fatty Acids Prevent Early Pancreatic Carcinogenesis via Repression of the AKT Pathway

Pancreatic cancer remains a daunting foe despite a vast number of accumulating molecular analyses regarding the mutation and expression status of a variety of genes. Indeed, most pancreatic cancer cases uniformly present with a mutation in the KRAS allele leading to enhanced RAS activation. Yet our understanding of the many epigenetic/environmental factors contributing to disease incidence and progression is waning. Epidemiologic data suggest that diet may be a key factor in pancreatic cancer development and potentially a means of chemoprevention at earlier stages. While diets high in ω3 fatty acids are typically associated with tumor suppression, diets high in ω6 fatty acids have been linked to increased tumor development. Thus, to better understand the contribution of these polyunsaturated fatty acids to pancreatic carcinogenesis, we modeled early stage disease by targeting mutant KRAS to the exocrine pancreas and administered diets rich in these fatty acids to assess tumor formation and altered cell-signaling pathways. We discovered that, consistent with previous reports, the ω3-enriched diet led to reduced lesion penetrance via repression of proliferation associated with reduced phosphorylated AKT (pAKT), whereas the ω6-enriched diet accelerated tumor formation. These data provide a plausible mechanism underlying previously observed effects of fatty acids and suggest that administration of ω3 fatty acids can reduce the pro-survival, pro-growth functions of pAKT. Indeed, counseling subjects at risk to increase their intake of foods containing higher amounts of ω3 fatty acids could aid in the prevention of pancreatic cancer.

Chronic ethanol exposure of human pancreatic normal ductal epithelial cells induces cancer stem cell phenotype through SATB2

The incidence of pancreatic cancer is on the rise. Risk factors for pancreatic cancer include alcohol toxicity and metabolic conditions such as obesity, hypertension, dyslipidaemia, insulin resistance and type 2 diabetes. However, the molecular mechanism by which chronic alcohol consumption contributes to pancreatic cancer is not well understood. The purpose of the study was to demonstrate the effects of long-term chronic ethanol exposure on the transformation of human pancreatic normal ductal epithelial (HPNE) cells. Our data showed that ethanol-transformed HPNE cells were more progressively transformed exhibiting spheroids and colonies, and anchorage-independent growth. These transformed cells contained high levels of reactive oxygen species and induced SATB2 expression. Furthermore, during ethanol-induced cellular transformation, cells gained the phenotypes of cancer stem cells (CSCs) by expressing pluripotency maintaining factors (Oct4, Sox2, cMyc and KLF4) and stem cell markers (CD24, CD44 and CD133). Ethanol-induced SATB2 can bind to the promoters of KLF4, Oct4, cMyc, Sox2, Bcl-2 and XIAP genes. Suppression of SATB2 expression in ethanol-transformed HPNE cells inhibited cell proliferation, colony formation and markers of CSCs and pluripotency. These data suggest that chronic alcohol consumption may contribute toward the development of pancreatic cancer by converting HPNE cells to cancer stem-like cells.

An Array of Bioactive Compounds From Australian Eucalypts and Their Relevance in Pancreatic Cancer Therapeutics

Pancreatic cancer (PC) is one of the most devastating human cancers, and despite the significant advances in the current therapeutic options, the overall survival rate for PC has remained static for the past 50 years. Plant-derived bioactive compounds play a vital role in cancer therapeutics by providing new lead compounds for future drug development. Therefore, the isolation, characterization, and identification of new bioactive compounds for the prevention and treatment of cancer continue to be an important aspect of natural product research. Many in vitro and in vivo studies published in the last few decades have established strong links between the phytochemical profile of eucalypts and anticancer activity. However, only a small number of these reports have attempted to demonstrate a relationship between the biological activity of eucalypt extracts and PC. This review focuses on potential anti-PC effects of an array of bioactive compounds present in various species of eucalypts. It also highlights the necessity for further in vitro and in vivo studies to develop a complete understanding of the potential this group of plants has for the development of potent and specific chemotherapeutic drugs for PC.

Sanguinarine inhibits pancreatic cancer stem cell characteristics by inducing oxidative stress and suppressing sonic hedgehog-Gli-Nanog pathway

Sonic hedgehog pathway is highly activated in pancreatic cancer stem cells (CSC) which play crucial roles in cancer initiation, progression and metastasis. However, the molecular mechanisms by which sanguinarine regulates pancreatic CSC characteristics is not well understood. The objectives of this study were to examine the molecular mechanisms by which sanguinarine regulates pancreatic CSC characteristics. Sanguinarine inhibited cell proliferation and colony formation and induced apoptosis through oxidative damage. Sanguinarine inhibited self-renewal capacity of pancreatic CSCs isolated from human and KrasG12D mice. Furthermore, sanguinarine suppressed epithelial-mesenchymal transition (EMT) by up-regulating E-cadherin and inhibiting N-cadherin. Significant decrease in expression level of Snail, Slug and Zeb1 corroborated the suppression of EMT in sanguinarine treated pancreatic CSCS. The ability of sanguinarine to inhibit pluripotency maintaining factors and CSC markers suggest that sanguinarine can be an effective agent for inhibiting pancreatic cancer growth and development by targeting CSCs. Furthermore, sanguinarine inhibited Shh-Gli pathway leading to modulation of Gli target genes in pancreatic CSCs. Chromatin immunoprecipitation assay demonstrated that Nanog directly binds to promoters of Cdk2, Cdk6, FGF4, c-Myc and Oct4, and sanguinarine inhibits the binding of Nanog with these genes, suggesting the direct involvement of Nanog in cell cycle, pluripotency and self-renewal. To further investigate the role of Shh-Gli-Nanog pathway, we regulated Shh signaling either by Shh protein or Nanog overexpression. Enforced activation of Shh or overexpression of Nanog counteracted the inhibitory effects of sanguinarine on pancreatic CSC proliferation, suggesting the actions of sanguinarine are mediated, at least in part, through Shh-Gli-Nanog pathway. Our studies suggest that sanguinarine can be used for the treatment and/or prevention of pancreatic cancer by targeting CSCs.

Galeterone and its analogs inhibit Mnk-eIF4E axis, synergize with gemcitabine, impede pancreatic cancer cell migration, invasion and proliferation and inhibit tumor growth in mice

Survival rate for pancreatic cancer (pancreatic ductal adenocarcinoma, PDAC) is poor, with about 80% of patients presenting with the metastatic disease. Gemcitabine, the standard chemotherapeutic agent for locally advanced and metastatic PDAC has limited efficacy, attributed to innate/acquired resistance and activation of pro-survival pathways. The Mnk1/2-eIF4E and NF-κB signaling pathways are implicated in PDAC disease progression/metastasis and also associated with gemcitabine-induced resistance in PDAC. Galeterone (gal), a multi-target, agent in phase III clinical development for prostate cancer has also shown effects on the aforementioned pathways. We show for the first time, that gal/analogs (VNPT55, VNPP414 and VNPP433-3β) profoundly inhibited cell viability of gemcitabine-naive/resistance PDAC cell lines and strongly synergized with gemcitabine in gemcitabine-resistant PDAC cells. In addition, to inducing G1 cell cycle arrest, gal/analogs induced caspase 3-mediated cell-death of PDAC cells. Gal/analogs caused profound downregulation of Mnk1/2, peIF4E and NF-κB (p-p65), metastatic inducing factors (N-cadherin, MMP-1/-2/-9, Slug, Snail and CXCR4) and putative stem cell factors, (β-Catenin, Nanog, BMI-1 and Oct-4). Gal/analog also depleted EZH2 and upregulated E-Cadherin. These effects resulted in significant inhibition of PDAC cell migration, invasion and proliferation. Importantly, we also observed strong MiaPaca-2 tumor xenograft growth inhibition (61% to 92%). Collectively, these promising findings strongly support further development of gal/analogs as novel therapeutics for PDAC.

Deferasirox, a novel oral iron chelator, shows antiproliferative activity against pancreatic cancer in vitro and in vivo

Background

Iron is essential for cell replication, metabolism and growth. Because neoplastic cells have high iron requirements due to their rapid proliferation, iron depletion may be a novel therapeutic strategy for cancer. Deferasirox (DFX), a novel oral iron chelator, has been successful in clinical trials in iron-overload patients and has been expected to become an anticancer agent. However, no studies have investigated the effects of DFX on pancreatic cancer. This study aimed to elucidate the effects of DFX against pancreatic cancer.

Methods

The effects of DFX on cell cycle, proliferation, and apoptosis were examined in three human pancreatic cancer cell lines: BxPC-3, HPAF-II, and Panc 10.05. The effect of orally administered DFX on the growth of BxPC-3 pancreatic cancer xenografts was also examined in nude mice. Additionally, microarray analysis was performed using tumors excised from xenografts.

Results

DFX inhibited pancreatic cancer cell proliferation in a dose-dependent manner. A concentration of 10 μM DFX arrested the cell cycle in S phase, whereas 50 and 100 μM DFX induced apoptosis. In nude mice, orally administered DFX at 160 and 200 mg/kg suppressed xenograft tumor growth with no serious side effects (n = 5; average tumor volumes of 674 mm³ for controls vs. 327 mm³ for 160 mg/kg DFX, p <0.05; average tumor volumes of 674 mm³ for controls vs. 274 mm³ for 200 mg/kg DFX, p <0.05). Importantly, serum biochemistry analysis indicated that serum levels of ferritin were significantly decreased by the oral administration of 160 or 200 mg/kg DFX (n = 5; average serum ferritin of 18 ng/ml for controls vs. 9 ng/ml for 160 mg/kg DFX, p <0.05; average serum ferritin of 18 ng/ml for controls vs. 10 ng/ml for 200 mg/kg DFX, p <0.05). Gene expression analysis revealed that most genes in pancreatic adenocarcinoma signaling, especially transforming growth factor-ß1 (TGF-ß1), were downregulated by DFX.

Conclusions

DFX has potential as a therapeutic agent for pancreatic cancer. Iron depletion was essential for the antiproliferative effect of DFX in a preclinical model, and DFX acted through the suppression of TGF-ß signaling.

Embelin suppresses growth of human pancreatic cancer xenografts, and pancreatic cancer cells isolated from KrasG12D mice by inhibiting Akt and Sonic hedgehog pathways

Pancreatic cancer is a deadly disease, and therefore effective treatment and/or prevention strategies are urgently needed. The objectives of this study were to examine the molecular mechanisms by which embelin inhibited human pancreatic cancer cell growth in vitro, and xenografts in Balb C nude mice, and pancreatic cancer cell growth isolated from Kras^G12D transgenic mice. XTT assays were performed to measure cell viability. AsPC-1 cells were injected subcutaneously into Balb c nude mice and treated with embelin. Cell proliferation and apoptosis were measured by Ki67 and TUNEL staining, respectively. The expression of Akt, and Sonic Hedgehog (Shh) and their target gene products were measured by the immunohistochemistry, and Western blot analysis. The effects of embelin on pancreatic cancer cells isolated from 10-months old Kras^G12D mice were also examined. Embelin inhibited cell viability in pancreatic cancer AsPC-1, PANC-1, MIA PaCa-2 and Hs 766T cell lines, and these inhibitory effects were blocked either by constitutively active Akt or Shh protein. Embelin-treated mice showed significant inhibition in tumor growth which was associated with reduced expression of markers of cell proliferation (Ki67, PCNA and Bcl-2) and cell cycle (cyclin D1, CDK2, and CDK6), and induction of apoptosis (activation of caspase-3 and cleavage of PARP, and increased expression of Bax). In addition, embelin inhibited the expression of markers of angiogenesis (COX-2, VEGF, VEGFR, and IL-8), and metastasis (MMP-2 and MMP-9) in tumor tissues. Antitumor activity of embelin was associated with inhibition of Akt and Shh pathways in xenografts, and pancreatic cancer cells isolated from Kras^G12D mice. Furthermore, embelin also inhibited epithelial-to-mesenchymal transition (EMT) by up-regulating E-cadherin and inhibiting the expression of Snail, Slug, and ZEB1. These data suggest that embelin can inhibit pancreatic cancer growth, angiogenesis and metastasis by suppressing Akt and Shh pathways, and can be developed for the treatment and/or prevention of pancreatic cancer.

Snail contributes to the maintenance of stem cell-like phenotype cells in human pancreatic cancer

Snail, a potent repressor of E-cadherin expression, plays a key role in epithelial-to-mesenchymal transition (EMT) in epithelial cancer. Recently, EMT and stemness programs are found linked together. In the current study, the expression of Snail and its contribution to cancer stem cell (CSC) marker expression, invasiveness, self-renewal, clonogenicity, and tumorigenicity of pancreatic cancer cells were studied. Our results showed that Snail was highly expressed in CSC^high cell line Panc-1. Stable, short hairpin RNA (shRNA)-mediated Snail knockdown decreased invasion in Panc-1 cells, in line with increased E-cadherin expression and its translocation from the nucleus to the membrane. Snail silencing in Panc-1 also inhibited CSC marker ALDH expression, together with decreased sphere and colony forming capacity, which was highly consistent with the expression of stem cell associated transcription factors like Sox2 and Oct4. In mouse xenograft models, knockdown of Snail led to a reduced number of tumor-bearing mice and a reduced average size of tumors, which had a stronger membrane staining of E-cadherin and lighter staining of Oct4. Collectively, these findings implicate Snail is required for the maintenance of stem cell-like phenotype in pancreatic cancer, and inhibition of Snail could be an efficient strategy to treat pancreatic cancer by targeting CSCs.

CA 125 concentration in portal blood as a predictor of resectability in pancreatic tumor

AIM OF THE STUDY

Pancreatic cancer is one of the most frequent cancers in the world. Only 20% of patients seem to have disease confined to the pancreas, but in only every second case the tumor turns out to be resectable during surgery. Tumor markers may be a useful tool in differentiating benign from malignant pancreatic tumors and in clinical staging. The purpose of the study is to assess CA 125 utility as a predictor of resectability in pancreatic tumor.

MATERIAL AND METHODS

66 patients were operated on for pancreatic tumor between October 2010 and July 2012. CA 125 concentration was measured in peripheral and portal blood. 57 patients were diagnosed with malignant and 9 with inflammatory tumor. Seven patients had metastases to the liver. Radical surgery was performed in 34 patients.

RESULTS

Significantly higher CA 125 concentration in portal blood was found in the pancreatic cancer than in the inflammatory tumor group (36.5 ±99.6 vs. 16.4 ±26.5; p < 0.05). CA 125 concentration in peripheral blood and in portal blood as well of patients with malignant pancreatic tumors and with metastases to the liver was significantly higher than in the group without metastases (146.15 ±256.1 vs. 18.5 ±17.5; p < 0.01 and 147.5 ±261.2 vs. 19.7 ±24.3; p < 0.05, respectively). CA 125 values in the group without metastases to the liver and in the case of radical surgery were significantly higher in portal than in peripheral blood (19.7 ±24.3 vs. 18.5 ±17.5; p < 0.001 and 13.2 ±15.0 vs. 13.0 ±15.2; p < 0.001, respectively).

CONCLUSIONS

Determination of CA 125 concentration in peripheral blood and in portal blood as well might be a useful tool in differentiating between malignant and inflammatory pancreatic tumors and when decisions on surgery extensiveness are being made.

Hedgehog signaling pathway regulates human pancreatic cancer cell proliferation and metastasis

Pancreatic cancer is one of the most aggressive and devastating malignancies. The Hedgehog (Hh) pathway has been reported to play an important role in pancreatic cancer development and progression. The aim of this study was to examine the activation of the Hh pathway in human pancreatic cancer tissue samples and pancreatic cancer cell lines, and the molecular mechanisms involved in the Hh pathway mediated effects on pancreatic cancer cell proliferation and invasion. The expression levels of Hh molecules in human pancreatic cancer tissue samples and pancreatic cancer cell lines were evaluated using RT-PCR. The role of the Hh pathway in cell proliferation and invasion was evaluated using flow cytometry, MTT, colony formation assays and transwell invasion assays, and the expression of cancer stem cell markers and epithelial-mesenchymal transition (EMT) were evaluated using flow cytometry and RT-PCR. Tumorigenicity assays were used to further investigate the role of the Hh pathway in vivo. Hh molecules were highly expressed in human pancreatic cancer tissue samples and pancreatic cancer cell lines. Inhibition of the Hh pathway notably decreased cell proliferation and induced apoptosis through inhibition of the PI3K/AKT pathway and cancer stem cells. Furthermore, inhibition of the Hh signaling pathway significantly inhibited EMT by suppressing the activation of transcription factors Snail and Slug, which are correlated with significantly reduced pancreatic cancer cell invasion, suggesting that the Hh signaling pathway is involved in early metastasis. These results indicate that activation of the Hh pathway is a common event. Inhibition of the Hh pathway may be a potential molecular target of new therapeutic strategies for pancreatic cancer.

Sonic hedgehog signaling inhibition provides opportunities for targeted therapy by sulforaphane in regulating pancreatic cancer stem cell self-renewal

Dysregulation of the sonic hedgehog (Shh) signaling pathway has been associated with cancer stem cells (CSC) and implicated in the initiation of pancreatic cancer. Pancreatic CSCs are rare tumor cells characterized by their ability to self-renew, and are responsible for tumor recurrence accompanied by resistance to current therapies. The lethality of these incurable, aggressive and invasive pancreatic tumors remains a daunting clinical challenge. Thus, the objective of this study was to investigate the role of Shh pathway in pancreatic cancer and to examine the molecular mechanisms by which sulforaphane (SFN), an active compound in cruciferous vegetables, inhibits self-renewal capacity of human pancreatic CSCs. Interestingly, we demonstrate here that Shh pathway is highly activated in pancreatic CSCs and plays important role in maintaining stemness by regulating the expression of stemness genes. Given the requirement for Hedgehog in pancreatic cancer, we investigated whether hedgehog blockade by SFN could target the stem cell population in pancreatic cancer. In an in vitro model, human pancreatic CSCs derived spheres were significantly inhibited on treatment with SFN, suggesting the clonogenic depletion of the CSCs. Interestingly, SFN inhibited the components of Shh pathway and Gli transcriptional activity. Interference of Shh-Gli signaling significantly blocked SFN-induced inhibitory effects demonstrating the requirement of an active pathway for the growth of pancreatic CSCs. SFN also inhibited downstream targets of Gli transcription by suppressing the expression of pluripotency maintaining factors (Nanog and Oct-4) as well as PDGFRα and Cyclin D1. Furthermore, SFN induced apoptosis by inhibition of BCL-2 and activation of caspases. Our data reveal the essential role of Shh-Gli signaling in controlling the characteristics of pancreatic CSCs. We propose that pancreatic cancer preventative effects of SFN may result from inhibition of the Shh pathway. Thus Sulforaphane potentially represents an inexpensive, safe and effective alternative for the management of pancreatic cancer.

EGCG inhibits growth of human pancreatic tumors orthotopically implanted in Balb C nude mice through modulation of FKHRL1/FOXO3a and neuropilin

Human pancreatic cancer is currently one of the fourth leading causes of cancer-related mortality with a 5-year survival rate of less than 5 %. Since pancreatic carcinoma is largely refractory to conventional therapies, there is a strong medical need for the development of novel and innovative cancer preventive strategies. The forkhead transcription factors of the O class (FOXO) play a major role in cell proliferation, angiogenesis, metastasis, and tumorigenesis. The objectives of this study were to examine whether FKHRL1/FOXO3a modulates antitumor activity of (-)-epigallocatechin-3-gallate (EGCG), an active ingredient in green tea, in pancreatic cancer model in vivo. PANC-1 cells were orthotopically implanted into Balb c nude mice and gavaged with EGCG after tumor formation. Cell proliferation and apoptosis were measured by Ki67 and TUNEL staining, respectively. The expression of PI3K, AKT, ERK, and FOXO3a/FKHRL1 and its target genes were measured by the western blot analysis and/or q-RT-PCR. FOXO-DNA binding was measured by gel shift assay. EGCG-treated mice showed significant inhibition in tumor growth which was associated with reduced phosphorylation of ERK, PI3K, AKT, and FKHRL1/FOXO3a, and modulation of FOXO target genes. EGCG induced apoptosis by upregulating Bim and activating caspase-3. EGCG modulated markers of cell cycle (p27/KIP1), angiogenesis (CD31, VEGF, IL-6, IL-8, SEMA3F, and HIF1α), and metastasis (MMP2 and MMP7). The inhibition of VEGF by EGCG was associated with suppression of neuropilin. EGCG inhibited epithelial-mesenchymal transition by upregulating the expression of E-cadherin and inhibiting the expression of N-cadherin and Zeb1. These data suggest that EGCG inhibits pancreatic cancer orthotopic tumor growth, angiogenesis, and metastasis which are associated with inhibition of PI3K/AKT and ERK pathways and activation of FKHRL1/FOXO3a. As a conclusion, EGCG can be used for the prevention and/or treatment of pancreatic cancer.

Grape proanthocyanidin inhibit pancreatic cancer cell growth in vitro and in vivo through induction of apoptosis and by targeting the PI3K/Akt pathway

Pancreatic cancer is an aggressive malignancy that is frequently diagnosed at an advanced stage with poor prognosis. Here, we report the chemotherapeutic effects of bioactive proanthocyanidins from grape seeds (GSPs) as assessed using In Vitro and In Vivo models. Treatment of human pancreatic cancer cells (Miapaca-2, PANC-1 and AsPC-1) with GSPs In Vitro reduced cell viability and increased G2/M phase arrest of the cell cycle leading to induction of apoptosis in a dose- and time-dependent manner. The GSPs-induced apoptosis of pancreatic cancer cells was associated with a decrease in the levels of Bcl-2 and Bcl-xl and an increase in the levels of Bax and activated caspase-3. Treatment of Miapaca-2 and PANC-1 cells with GSPs also decreased the levels of phosphatidylinositol-3-kinase (PI3K) and phosphorylation of Akt at ser(473). siRNA knockdown of PI3K from pancreatic cancer cells also reduced the phosphorylation of Akt. Further, dietary administration of GSPs (0.5%, w/w) as a supplemented AIN76A control diet significantly inhibited the growth of Miapaca-2 pancreatic tumor xenografts grown subcutaneously in athymic nude mice, which was associated with: (i) inhibition of cell proliferation, (ii) induction of apoptosis of tumor cells, (iii) increased expression of Bax, reduced expression of anti-apoptotic proteins and activation of caspase-3-positive cells, and (iv) decreased expression of PI3K and p-Akt in tumor xenograft tissues. Together, these results suggest that GSPs may have a potential chemotherapeutic effect on pancreatic cancer cell growth.

Inhibition of sonic hedgehog pathway and pluripotency maintaining factors regulate human pancreatic cancer stem cell characteristics

Activation of the sonic hedgehog (SHh) pathway is required for the growth of numerous tissues and organs and recent evidence indicates that this pathway is often recruited to stimulate growth of cancer stem cells (CSCs) and to orchestrate the reprogramming of cancer cells via epithelial mesenchymal transition (EMT). The objectives of this study were to examine the molecular mechanisms by which (-)-epigallocatechin-3-gallate (EGCG), an active compound in green tea, inhibits self-renewal capacity of pancreatic CSCs and synergizes with quercetin, a major polyphenol and flavonoid commonly detected in many fruits and vegetables. Our data demonstrated that EGCG inhibited the expression of pluripotency maintaining transcription factors (Nanog, c-Myc and Oct-4) and self-renewal capacity of pancreatic CSCs. Inhibition of Nanog by shRNA enhanced the inhibitory effects of EGCG on self-renewal capacity of CSCs. EGCG inhibited cell proliferation and induced apoptosis by inhibiting the expression of Bcl-2 and XIAP and activating caspase-3. Interestingly, EGCG also inhibited the components of SHh pathway (smoothened, patched, Gli1 and Gli2) and Gli transcriptional activity. Furthermore, EGCG inhibited EMT by inhibiting the expression of Snail, Slug and ZEB1, and TCF/LEF transcriptional activity, which correlated with significantly reduced CSC's migration and invasion, suggesting the blockade of signaling involved in early metastasis. Furthermore, combination of quercetin with EGCG had synergistic inhibitory effects on self-renewal capacity of CSCs through attenuation of TCF/LEF and Gli activities. Since aberrant SHh signaling occurs in pancreatic tumorigenesis, therapeutics that target SHh pathway may improve the outcomes of patients with pancreatic cancer by targeting CSCs.

Resveratrol inhibits pancreatic cancer stem cell characteristics in human and KrasG12D transgenic mice by inhibiting pluripotency maintaining factors and epithelial-mesenchymal transition

BACKGROUND

Cancer stem cells (CSCs) can proliferate and self-renew extensively due to their ability to express anti-apoptotic and drug resistant proteins, thus sustaining tumor growth. Therefore, the strategy to eradicate CSCs might have significant clinical implications. The objectives of this study were to examine the molecular mechanisms by which resveratrol inhibits stem cell characteristics of pancreatic CSCs derived from human primary tumors and Kras(G12D) transgenic mice.

METHODOLOGY/PRINCIPAL FINDINGS

Human pancreatic CSCs (CD133(+)CD44(+)CD24(+)ESA(+)) are highly tumorigenic and form subcutaneous tumors in NOD/SCID mice. Human pancreatic CSCs expressing high levels of CD133, CD24, CD44, ESA, and aldehyde dehydrogenase also express significantly more Nanog, Oct-4, Notch1, MDR1 and ABCG2 than normal pancreatic tissues and primary pancreatic cancer cells. Similarly, CSCs from Kras(G12D) mice express significantly higher levels of Nanog and Oct-4 than pancreatic tissues from Pdx-Cre mice. Resveratrol inhibits the growth (size and weight) and development (PanIN lesions) of pancreatic cancer in Kras(G12D) mice. Resveratrol inhibits the self-renewal capacity of pancreatic CSCs derived from human primary tumors and Kras(G12D) mice. Resveratrol induces apoptosis by activating capase-3/7 and inhibiting the expression of Bcl-2 and XIAP in human CSCs. Resveratrol inhibits pluripotency maintaining factors (Nanog, Sox-2, c-Myc and Oct-4) and drug resistance gene ABCG2 in CSCs. Inhibition of Nanog by shRNA enhances the inhibitory effects of resveratrol on self-renewal capacity of CSCs. Finally, resveratrol inhibits CSC's migration and invasion and markers of epithelial-mesenchymal transition (Zeb-1, Slug and Snail).

CONCLUSIONS/SIGNIFICANCE

These data suggest that resveratrol inhibits pancreatic cancer stem cell characteristics in human and Kras(G12D) transgenic mice by inhibiting pluripotency maintaining factors and epithelial-mesenchymal transition. In conclusion, resveratrol can be used for the management of pancreatic cancer.

Sulforaphane synergizes with quercetin to inhibit self-renewal capacity of pancreatic cancer stem cells

According to the cancer stem cell hypothesis, the aggressive growth and early metastasis of cancer may arise through dysregulation of self-renewal of stem cells. The objectives of this study were to examine the molecular mechanisms by which sulforaphane (SFN, an active compound in cruciferous vegetables) inhibits self-renewal capacity of pancreatic cancer stem cells (CSCs), and synergizes with quercetin, a major polyphenol and flavonoid commonly detected in many fruits and vegetables. Our data demonstrated that SFN inhibited self-renewal capacity of pancreatic CSCs. Inhibition of Nanog by lentiviral-mediated shRNA expression enhanced the inhibitory effects of sulforaphane on self-renewal capacity of CSCs. SFN induced apoptosis by inhibiting the expression of Bcl-2 and XIAP, phosphorylation of FKHR, and activating caspase-3. Moreover, SFN inhibited expression of proteins involved in the epithelial-mesenchymal transition (beta-catenin, vimentin, twist-1, and ZEB1), suggesting the blockade of signaling involved in early metastasis. Furthermore, the combination of quercetin with SFN had synergistic effects on self-renewal capacity of pancreatic CSCs. These data suggest that SFN either alone or in combination with quercetin can eliminate cancer stem cell-characteristics.

Inhibition of PI3K/AKT and MAPK/ERK pathways causes activation of FOXO transcription factor, leading to cell cycle arrest and apoptosis in pancreatic cancer

Background

Mammalian forkhead members of the class O (FOXO) transcription factors, including FOXO1, FOXO3a, and FOXO4, are implicated in the regulation of several biological processes, including the stress resistance, metabolism, cell cycle, apoptosis and DNA repair. The objectives of this study were to examine the molecular mechanisms by which FOXO transcription factors induced cell cycle arrest and apoptosis and enhanced anti-proliferative effects of sulforaphane (SFN, an active compound in cruciferous vegetables) in pancreatic cancer cells.

Results

Our data demonstrated that SFN inhibited cell proliferation and colony formation, and induced apoptosis through caspase-3 activation in pancreatic cancer cells. The inhibition of PI3K/AKT and MEK/ERK pathways activated FOXO transcription factors. SFN inhibited phosphorylation of AKT and ERK, and activated FOXO transcription factors, leading to cell cycle arrest and apoptosis. Phosphorylation deficient mutants of FOXO proteins enhanced FOXO transcriptional activity, and further enhanced SFN-induced FOXO activity and apoptosis. SFN induced the expression of p21^/CIP1 and p27^/KIP1, and inhibited the expression of cyclin D1.

Conclusion

These data suggest that inhibition of PI3K/AKT and ERK pathways acts together to activate FOXO transcription factor and enhances SFN-induced FOXO transcriptional activity, leading to cell cycle arrest and apoptosis.

The epigenetic regulators Bmi1 and Ring1B are differentially regulated in pancreatitis and pancreatic ductal adenocarcinoma

Chronic pancreatitis and pancreatic ductal adenocarcinoma (PDAC) are associated with major changes in cell differentiation. These changes may be at the basis of the increased risk for PDAC among patients with chronic pancreatitis. Polycomb proteins are epigenetic silencers expressed in adult stem cells; up-regulation of Polycomb proteins has been reported to occur in a variety of solid tumours such as colon and breast cancer. We hypothesized that Polycomb might play a role in preneoplastic states in the pancreas and in tumour development/progression. To test these ideas, we determined the expression of PRC1 complex proteins (Bmi1 and Ring1b) during pancreatic development and in pancreatic tissue from mouse models of disease: acute and chronic pancreatic injury, duct ligation, and in K-Ras(G12V) conditional knock-in and caerulein-treated K-Ras(G12V) mice. The study was extended to human pancreatic tissue samples. To obtain mechanistic insights, Bmi1 expression in cells undergoing in vitro exocrine cell metaplasia and the effects of Bmi1 depletion in an acinar cancer cell line were studied. We found that Bmi1 and Ring1B are expressed in pancreatic exocrine precursor cells during early development and in ductal and islet cells-but not acinar cells-in the adult pancreas. Bmi1 expression was induced in acinar cells during acute injury, in acinar-ductal metaplastic lesions, as well as in pancreatic intraepithelial neoplasia (PanIN) and PDAC. In contrast, Ring1B expression was only significantly and persistently up-regulated in high-grade PanINs and in PDAC. Bmi1 knockdown in cultured acinar tumour cells led to changes in the expression of various digestive enzymes. Our results suggest that Bmi1 and Ring1B are modulated in pancreatic diseases and could contribute differently to tumour development.

Can preoperative CA19-9 and CEA levels predict the resectability of patients with pancreatic adenocarcinoma?

BACKGROUND

We aimed to explore the predictive ability of preoperative carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) levels for assessing tumor resectability (R0 resection) in patients with pancreatic adenocarcinoma.

METHODS

The present study included 72 patients who had been treated surgically for potentially resectable pancreatic adenocarcinoma and 42 patients who had been treated surgically for palliation (bypass surgery) at our institution. Pancreatic adenocarcinoma was histologically confirmed by pathological examination of the resected specimen or, if unresected, by intraoperative biopsy.

RESULTS

For resectable disease, the mean and median values of CA19-9 were significantly lower than for R1/2 or unresectable disease. The best cut-off points for CEA, CA19-9, and tumor size to predict resectability were 2.47 ng/mL, 92.77 U/mL and 11.85 cm(3), respectively. A CA19-9 > or = 92.77 U/mL and both tumor markers no less than the cut-off levels predicted the possibility of R1/2 or unresectability with 90.6% and 88.6% accuracy, respectively. However, either tumor marker or both tumor markers less than the cut-off levels predicted the probability of R0 resection only with 27.1% and 40.6% accuracy, respectively. The independent contributing factors to resectability (R0 resection) by multivariate regression analysis were a CA 19-9 < 92.77 U/mL, a tumor size < 11.85 cm(3), and a less advanced AJCC stage.

CONCLUSION

The present study demonstrates that preoperative serum CA19-9 and CEA levels can be used for the prediction of resectability (R0 resection) in patients with pancreatic adenocarcinoma, which may enable a simple and cost-effective exclusion of such patients who are unlikely to benefit from surgery.

Patients with pancreatic adenocarcinoma benefit from staging laparoscopy

BACKGROUND

Unnecessary laparotomy in patients with advanced pancreatic cancer may both compromise the quality of life and delay the initiation of more appropriate therapy. Very often, peritoneal small liver metastases and true local status cannot be fully determined without surgery. Laparoscopy may spare laparotomy and decrease morbidity for patients with nonresectable advanced disease. The aim of this study was to determine the impact of laparoscopy in patients with potentially resectable adenocarcinoma of the pancreas.

MATERIALS AND METHODS

We reviewed the records of patients undergoing pancreatic surgery at the University of Nebraska Medical Center from October 2001 to April 2005. A total of 59 patients were included in the study. All patients were staged radiographically with a high resolution helical computed tomography scan and their tumors were considered resectable. Thirty-seven patients underwent staging laparoscopy while 22 proceeded directly to laparotomy.

RESULTS

Of the 37 patients who underwent laparoscopic staging, 9 (24.3%) were detected to have metastatic disease or advanced tumor; the remaining 28 (75.7%) patients with negative laparoscopy proceeded to laparotomy. Of those, 24 patients (85.7%) underwent pancreatic resection with curative intent, while 4 patients had metastatic or locally advanced disease at subsequent laparotomy which was missed on staging laparoscopy (false negative rate of 14.3%). Of the 22 patients who proceeded directly to laparotomy, 16 (72.7%) received curative Whipple resection and 6 (27.3%) were found to have advanced disease and received bypass procedures or biopsy alone.

CONCLUSION

These findings suggest that staging laparoscopy is beneficial in a significant proportion of patients deemed resectable by routine noninvasive preoperative studies. We plan to add intraoperative laparoscopic ultrasound to our staging protocol in order to decrease the false negative rate.

In vitro modeling of human pancreatic duct epithelial cell transformation defines gene expression changes induced by K-ras oncogenic activation in pancreatic carcinogenesis

Genetic analysis of pancreatic ductal adenocarcinomas and their putative precursor lesions, pancreatic intraepithelial neoplasias (PanIN), has shown a multistep molecular paradigm for duct cell carcinogenesis. Mutational activation or inactivation of the K-ras, p16(INK4A), Smad4, and p53 genes occur at progressive and high frequencies in these lesions. Oncogenic activation of the K-ras gene occurs in >90% of pancreatic ductal carcinoma and is found early in the PanIN-carcinoma sequence, but its functional roles remain poorly understood. We show here that the expression of K-ras(G12V) oncogene in a near diploid HPV16-E6E7 gene immortalized human pancreatic duct epithelial cell line originally derived from normal pancreas induced the formation of carcinoma in 50% of severe combined immunodeficient mice implanted with these cells. A tumor cell line established from one of these tumors formed ductal cancer when implanted orthotopically. These cells also showed increased activation of the mitogen-activated protein kinase, AKT, and nuclear factor-kappaB pathways. Microarray expression profiling studies identified 584 genes whose expression seemed specifically up-regulated by the K-ras oncogene expression. Forty-two of these genes have been reported previously as differentially overexpressed in pancreatic cancer cell lines or primary tumors. Real-time PCR confirmed the overexpression of a large number of these genes. Immunohistochemistry done on tissue microarrays constructed from PanIN and pancreatic cancer samples showed laminin beta3 overexpression starting in high-grade PanINs and occurring in >90% of pancreatic ductal carcinoma. The in vitro modeling of human pancreatic duct epithelial cell transformation may provide mechanistic insights on gene expression changes that occur during multistage pancreatic duct cell carcinogenesis.

Meta-analysis of randomised adjuvant therapy trials for pancreatic cancer

The aim of this study was to investigate the worldwide evidence of the roles of adjuvant chemoradiation and adjuvant chemotherapy on survival in potentially curative resected pancreatic cancer. Five randomised controlled trials of adjuvant treatment in patients with histologically proven pancreatic ductal adenocarcinoma were identified, of which the four most recent trials provided individual patient data (875 patients). This meta-analysis includes previously unpublished follow-up data on 261 patients. The pooled estimate of the hazard ratio (HR) indicated a 25% significant reduction in the risk of death with chemotherapy (HR=0.75, 95% confidence interval (CI): 0.64, 0.90, P-values_stratified (P_strat)=0.001) with median survival estimated at 19.0 (95% CI: 16.4, 21.1) months with chemotherapy and 13.5 (95% CI: 12.2, 15.8) without. The 2- and 5-year survival rates were estimated at 38 and 19%, respectively, with chemotherapy and 28 and 12% without. The pooled estimate of the HR indicated no significant difference in the risk of death with chemoradiation (HR=1.09, 95% CI: 0.89, 1.32, P_strat=0.43) with median survivals estimated at 15.8 (95% CI: 13.9, 18.1) months with chemoradiation and 15.2 (95% CI: 13.1, 18.2) without. The 2- and 5-year survival rates were estimated at 30 and 12%, respectively, with chemoradiation and 34 and 17% without. Subgroup analyses estimated that chemoradiation was more effective and chemotherapy less effective in patients with positive resection margins. These results show that chemotherapy is effective adjuvant treatment in pancreatic cancer but not chemoradiation. Further studies with chemoradiation are warranted in patients with positive resection margins, as chemotherapy appeared relatively ineffective in this patient subgroup.