Tetracycline-inducible protein expression in pancreatic cancer cells: Effects of CapG overexpression

AIM: To establish stable tetracycline-inducible pancreatic cancer cell lines. METHODS: Suit-2, MiaPaca-2, and Panc-1 cells were transfected with a second generation reverse tetracycline-controlled transactivator protein (rtTA2S-M2), under the control of either a cytomegalovirus (CMV) or a chicken β-actin promoter, and the resulting clones were characterised.RESULTS: Use of the chicken (β-actin) promoter proved superior for both the production and maintenance of doxycycline-inducible cell lines. The system proved versatile, enabling transient inducible expression of a variety of genes, including GST-P, CYP2E1, S100A6, and the actin capping protein, CapG. To determine the physiological utility of this system in pancreatic cancer cells, stable inducible CapG expressors were established. Overexpressed CapG was localised to the cytoplasm and the nuclear membrane, but was not observed in the nucleus. High CapG levels were associated with enhanced motility, but not with changes to the cell cycle, or cellular proliferation. In CapG-overexpressing cells, the levels and phosphorylation status of other actin-moduating proteins (Cofilin and Ezrin/Radixin) were not altered. However, preliminary analyses suggest that the levels of other cellular proteins, such as ornithine aminotransferase and enolase, are altered upon CapG induction. CONCLUSION: We have generated pancreatic-cancer derived cell lines in which gene expression is fully controllable.

In Vitro Lethal Effect of Photodynamic Therapy on Human Pancreatic Cancer Cells and Its Major Influencing Factors

OBJECTIVE To investigate the in vitro lethal effect of photo- dynamic therapy （PDT） using the photosensitizer hematoporphyrin on the human pancreatic cancer cell line Panc-1, the major influencing factors and the mechanisms of treatment. METHODS Three factors--the time needed for photosensitizer and cell incubation, the photosensitizer concentration （PhoC） and the exposure dose （ExpD）--were examined with different levels of these factors. Optical density （OD） was used as a measure of CCK-8 in the experiment, and was converted to the rate of cell survival. The separate effect of each factor on the photodynamic action was studied, and the interactions were investigated. The effects of different incubation times and PhoC levels on the fluorescence intensity （FI） of the intracellular photosensitizer were determined, and the mechanisms of these factors leading to the therapeutic effects of PDT discussed. RESULTS An increase in the photosensitizer and cell incubation time, an increase of PhoC, and enhancement of the ExpD, produced a corresponding decrease in the rate of Panc-1 cell survival after PDT （P 〈 0.05）. PDT achieved its maximum lethal effects 16 h after starting the incubation, with a PhoC of 10 mg/L and an ExpD of 20 J/cm2; at these levels a synergistic interaction between PhoC and the ExpD occurred, decreasing the cell survival rate （P 〈 0.05）. Neither simple administration of photosensitizer without ExpD （0 J/cm2） or illumination in the absence of PhoC （0 mg/L） affected the rate of cell survival （P 〉 0.05）. With an increase of PhoC and lengthening of the incubation time, the FI of the intracellular photosensitizer accordingly increased （P 〈 0.05）, and attained its maximum value at a PhoC of 10 mg/L and 36 h after the incubation. With an increase of PhoC, the FI of the photosensitizer, hematoporphyrin, in the solution increased progressively at first and then decreased （fluorescence quenching）. CONCLUSION PDT with the photosensitizer hematoporphyrin has clear lethal effects on the human pancreatic cancer cell line Panc-1, but the presence of a photosensitizer and laser irradiation by themselves do not have independent lethal effects. The three influencing factors--the time for photosensitizer and cell incuba- tion, PhoC and ExpD--correlate positively with the PDT response, within certain limits. Beyond these limits, the PDT response does not significantly increase. The main mechanism of the PDT response lies in the effect of these factors on the level of the intracellular photosensitizer and the fluorescence quenching of the photosensitizer. A synergistic effect exists between PhoC and ExpD.

KAI1 is a potential target for anti-metastasis in pancreatic cancer cells

AIM: To investigate whether KAI1, as a metastasis suppressor gene, is associated with invasive and metastatic ability of pancreatic cancer cells.METHODS: KAI1 gene was transfected into pancreatic cancer cell line MiaPaCa Ⅱ by liposomes selected with G418. Expression of transfected cells was measured by Western blotting, immunofluorescence and immunocytochemistry. Tumor cell invasion and metastatic ability were detected through gelatinase activity and reconstituted basement membrane (Matrigel) assay. pCMV-KAI1 was directly injected into the heterotopic human pancreatic adenocarcinoma successfully established in the groin of BALB/C nude mice, by subcutaneous injection of MiaPaCa Ⅱ pancreatic cancer cells. The statistical analysis between groups was determined by Student's two tailed t test.RESULTS: By Western blotting, MiaPaCa Ⅱ cells transfected by KAI1 gene indicated KAI1 expression at approximately 29.1 kDa. Cytoplasm staining was positive and uniformly spread in transfected cancer cells, using immunohistochemistry and immunofluorescence. The most obvious difference was present after 30 h (MiaPaca Ⅱ 43.6 ± 9.42, pCMV-MiaPaca Ⅱ 44.8 ± 8.56, pCMV-KAI1-MiaPaca Ⅱ 22.0 ± 4.69, P < 0.05). Gelatinolysis revealed a wider and clearer band of gelatinolytic activity in non-transfected than in transfected cells (MiaPaCa Ⅱ cells 30.8 ± 0.57, transfected cells 28.1 ± 0.65, P < 0.05). In vivo tumor growth rates of KAI1 transfectants with KAI1-Lipofectamine 1.22 ± 0.31 in A group were lower than control 4.61 ± 1.98 and pCMV-KAI 11.67 ± 0.81. Analyses of metastases with and without KAI1 transfection in mice were different in liver and lung between controls 1.62 ± 0.39, 0.45 ± 0.09, pCMV-KAI 1.01 ± 0.27, 0.33 ± 0.09 and KAI1-Lipofectamine 0.99 ± 0.21, 0.30 ± 0.09 respectively (P < 0.05).CONCLUSION: High expression of KAI1 gene was found in transfected MiaPaCa Ⅱ human pancreatic cancer cells with lower metastatic ability. KAI1 gene plays an important role in inhibiting metastasis of pancreatic cancer after direct injection into pancreatic adenocarcinoma. These results show that the suppressed invasion and motor function of pancreatic cancer cells may be a key reason why the KAI1 gene controls pancreatic cancer cell metastasis.

Pancreatic stellate cells promote proliferation and invasiveness of human pancreatic cancer cells via galectin-3

AIM: To investigate the role of pancreatic stellate cells (PSCs) and galectin-3 (GAL-3) in the proliferation and infiltration of pancreatic cancer cell line SW1990. METHODS: Human pancreatic cancer cell line SW1990 and PSCs were cultured in vitro . Supernatant fluid of cultured PSCs and SW1990 cells was collected. Expression of GAL-3 in SW1990 cells and PSCs was detected by ELISA, RT-PCR and Western blotting. Proliferation of cultured PSCs and SW1990 cells was measured by 3-(4, 5-methylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. Infiltration of SW1990 cells was detected by a cell infiltration kit. RESULTS: SW1990 cells expressed GAL-3 and this was up-regulated by the supernatant fluid of cultured PSCs. PSCs did not express GAL-3. SW1990 cells stimulated proliferation of PSCs via GAL-3. GAL-3 antibody inhibited SW1990 cell proliferation, while the supernatant fluid of PSCs stimulated proliferation of SW1990 cells through interaction with GAL-3 protein. The supernatant fluid of PSCs enhanced the invasiveness of SW1990 cells through interaction with GAL-3. CONCLUSION: GAL-3 and PSCs were involved in the proliferation and infiltration process of pancreatic cancer cells.

Insulin Promotes Proliferative Vitality and Invasive Capability of Pancreatic Cancer Cells via Hypoxia-inducible Factor 1α Pathway

This study examined whether insulin-stimulated hypoxia-inducible factor 1α(HIF-1α) expression plays a crucial role in promoting the proliferative vitality and invasive capability in human pancreatic cancer cells.PANC-1 cells were divided into three groups:Control group,insulin group and insulin+YC-1(a pharmacological inhibitor of HIF-1α) group in terms of different treatments.Cells in the insulin group or insulin+YC-1 group were treated with insulin(0.1,1,10 and 100 nmol/L) alone or combined with 3-(5’-hydroxymethyl-2’-furyl)-1-benzyl indazole(YC-1,0.1,1,10 and 100 μmol/L).HIF-1α mRNA and protein expression in PANC-1 cells was determined by real-time RT-PCR and Western blotting respectively.Cell proliferation and invasion were measured by using growth curve and invasion assay,respectively.Western blot analysis demonstrated that insulin dose-dependently increased the HIF-1α protein expression,and YC-1 could dose-dependently block this effect.However,neither insulin nor YC-1 altered HIF-1α mRNA levels in PANC-1 cells.Moreover,insulin could enhance the proliferation and invasion of PANC-1 cells,while YC-1 could weaken this effect.It was concluded that the malignant proliferation and local invasion of pancreatic cancer cells may be related to high-insulin microenvironment.The tumor biological behavior change resulting from high-insulin microenvironment may be associated with the increased expression of HIF-1α protein.

WNT5A modulates cell cycle progression and contributes to the chemoresistance in pancreatic cancer cells

BACKGROUND： Although there are many studies on the mechanism of chemoresistance in cancers, studies on the relations between WNT5 A and chemoresistance in pancreatic cancer are rare. The present study was to examine the role of WNT5 A in the regulation of cell cycle progression and in chemoresistance in pancreatic cancer tissues and cell lines.METHODS： Fresh pancreatic cancer and paracarcinoma tissues were obtained from 32 patients. The expressions of WNT5 A,AKT/p-AKT and Cyclin D1 were detected by immunohistochemistry,and the correlation between WNT5 A expression and clinicopathological characteristics was analyzed. The relationship between WNT5 A expression and gemcitabine resistance was studied in PANC-1 and MIAPaCa2 cell lines. The effect of WNT5 A on the regulation of cell cycle and gemcitabine cytotoxicity were investigated. The associations among the expressions of p-AKT,Cyclin D1 and WNT5 A were also analyzed in cell lines and the effect of WNT5 A on restriction-point（R-point） progression was evaluated.RESULTS： WNT5 A, p-AKT and Cyclin D1 were highly expressed in pancreatic cancer tissues, and the WNT5 A expression was correlated with the TNM stages. In vitroWNT5 A expression was associated with gemcitabine chemoresistance. The percentage of cells was increased in G0/G1 phase and decreased in S phase after knockdown of WNT5 A in PANC-1. WNT5 A promoted Cyclin D1 expression through phosphorylation of AKT which consequently enhanced G1-S transition and gemcitabine resistance. Furthermore, WNT5 A enhanced the cell cycle progression toward R-point through regulation ofretinoblastoma protein（pRb） and pRb-E2 F complex formation.CONCLUSIONS： WNT5 A induced chemoresistance by regulation of G1-S transition in pancreatic cancer cells. WNT5 A might serve as a predictor of gemcitabine response and as a potential target for tumor chemotherapy.

Neamine Inhibits Growth of Pancreatic Cancer Cells In Vitro and In Vivo

Neamine, a non-toxic derivative of neomycin, has recently been shown to have antitumor activities in various types of cancers. However, its effect on pancreatic cancer is still unknown. The study aimed to investigate its antitumor activity on pancreatic cancer and the underlying mechanisms. MTT assay was used to observe the effect of neamine on angiogenin（ANG）-induced As PC-1 cell proliferation. Tissue microassay and immunofluorescence staining were used to detect the expression of ANG and its nuclear translocation, respectively. Tumor xenografts were established by subcutaneous inoculation of As PC-1 pancreatic cancer cells into the right flanks of nude mice, and neamine was injected subcutaneously. Immunohistochemistry was done to observe the expression of ANG, CD31 and Ki-67 in tumor xenografts. It was found that neamine blocked the nuclear translocation of ANG effectively and inhibited ANG-induced As PC-1 cell proliferation in a dose-dependent manner. Neamine had anti-tumor effects on As PC-1 xenograft models. Consistently, neamine reduced the expression levels of ANG, Ki-67 and CD31 in tumor xenografts. It was concluded that neamine may be a promising agent for treatment of pancreatic cancer.

Pancreatic cancer stem cells:Perspectives on potential therapeutic approaches of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma is one of the most aggressive solid tumours of the pancreas, characterised by a fve-year survival rate less than 8%. Recent reports that pancreatic cancer stem cells （PCSCs） contribute to the tumorigenesis, progression, and chemoresistance of pancreatic cancer have prompted the investigation of new therapeutic approaches able to directly target PCSCs. In the present paper the non-cancer related drugs that have been proposed to target CSCs that could potentially combat pancreatic cancer are revi-ewed and evaluated. The role of some pathways and deregulated proteins in PCSCs as new therapeutic tar-gets are also discussed with a focus on selected speci-fic inhibitors. Finally, advances in the development of nanoparticles for targeting PCSCs and site-specifc drug delivery are highlighted, and their limitations considered.

Therapeutic options for the management of pancreatic cancer

Since its initial characterization, pancreatic ductal adenocarcinoma has remained one of the most devastating and difficult cancers to treat. Pancreatic cancer is the fourth leading cause of death in the United States, resulting in an estimated 38460 deaths annually. With few screening tools available to detect this disease at an early stage, 94% of patients will die within five years of diagnosis. Despite decades of research that have led to a better understanding of the molecular and cellular signaling pathways in pancreatic cancer cells, few effective therapies have been developed to target these pathways. Other treatment options have included more sophisticated pancreatic cancer surgeries and combination therapies. While outcomes have improved modestly for these patients, more effective treatments are desperately needed. One of the greatest challenges in the future of treating this malignancy will be to develop therapies that target the tumor microenvironment and surrounding pancreatic cancer stem cells in addition to pancreatic cancer cells. Recent advances in targeting pancreatic stellate cells and the stroma have encouraged researchers to shift their focus to the role of desmoplasia in pancreatic cancer pathobiology in the hopes of developing newer-generation therapies. By combining novel agents with current cytotoxic chemotherapies and radiation therapy and personalizing them to each patient based on specific biomarkers, the goal of prolonging a patient&#x02019;s life could be achieved. Here we review the most effective therapies that have been used for the treatment of pancreatic cancer and discuss the future potential of therapeutic options.

KAI1 inhibits HGF-induced invasion of pancreatic cancer by sphingosine kinase activity

BACKGROUND:KAI1/CD82 has been reported to attenuate the process of metastases in a variety of tumors;however,its mechanism of action in invasion has not been fully elucidated. The present study aimed to investigate the importance of KAI1 in invasion and its correlation with activation of sphingosine kinase(SPK)in human pancreatic cancer PANC1 and Miapaca-2 cell lines. METHODS:The expression of KAI1 in PANC1 and Miapaca-2 cells,which was mediated by recombinant adenovirus(Ad-KAI1), was assessed by a flow cytometer and Western blotting.After successful infection was established,in vitro growth curve and invasive ability in Boyden Chamber assay were studied.The presence of KAI1 correlating with c-Met and SPK was detected by co-immunoprecipitation and[γ-32P]ATP incorporation. RESULTS:KAI1 genes had no significant effects on the curve representing cell growth.After infection with the KAI1 gene,decreased invasive ability in the Boyden Chamber assay was observed in PANC1 and Miapaca-2 cells that were induced by hepatocyte growth factor.Over-expression of KAI1 in the cells led to the deactivation of SPK and a decreased level of intracellular sphingosine-1-phosphate.No correlation was observed between c-Met and KAI1 during co-immunoprecipitation. CONCLUSION:The results of this study for the first time demonstrated a regulatory role for KAI1 in SPK activation, which leads to decreased invasive ability in disease progression of human pancreatic cancer.

Novel therapeutic targets for pancreatic cancer

Pancreatic cancer has become the fourth leading cause of cancer death in the last two decades. Only 3%-15% of patients diagnosed with pancreatic cancer had 5 year survival rate. Drug resistance, high metastasis, poor prognosis and tumour relapse contributed to the malignancies and difficulties in treating pancreatic cancer. The current standard chemotherapy for pancreatic cancer is gemcitabine, however its efficacy is far from satisfactory, one of the reasons is due to the complex tumour microenvironment which decreases effective drug delivery to target cancer cell. Studies of the molecular pathology of pancreatic cancer have revealed that activation of KRAS, overexpression of cyclooxygenase-2, inactivation of p16INK4A and loss of p53 activities occurred in pancreatic cancer. Co-administration of gemcitabine and targeting the molecular pathological events happened in pancreatic cancer has brought an enhanced therapeutic effectiveness of gemcitabine. Therefore, studies looking for novel targets in hindering pancreatic tumour growth are emerging rapidly. In order to give a better understanding of the current findings and to seek the direction in future pancreatic cancer research; in this review we will focus on targets suppressing tumour metastatsis and progression, KRAS activated downstream effectors, the relationship of Notch signaling and Nodal/Activin signaling with pancreatic cancer cells, the current findings of non-coding RNAs in inhibiting pancreatic cancer cell proliferation, brief discussion in transcription remodeling by epigenetic modifiers (e.g., HDAC, BMI1, EZH2) and the plausible therapeutic applications of cancer stem cell and hyaluronan in tumour environment.

TRAIL-induced expression of uPA and IL-8 strongly enhanced by overexpression of TRAF2 and Bcl-xL in pancreatic ductal adenocarcinoma cells

BACKGROUND:The death ligand,tumor necrosis factor(TNF)related apoptosis-inducing ligand(TRAIL),induces apoptosis and non-apoptotic signaling in some tumor cells.The purpose of this study was to investigate the roles of the pro-apoptotic TRAIL receptors,TRAIL-R1 and TRAIL-R2,as well as Bcl-xL and TRAF2 in TRAIL-induced expression of the pro-inflammatory cytokine IL-8 and the invasion-promoting protein urokinase(uPA) in pancreatic ductal adenocarcinoma(PDAC) cells.METHODS:Colo357wt,Colo357/TRAF2,Colo357/Bcl-xL,Panc89 and PancTuI cells were stimulated with TRAIL and uPA and IL-8 expression was detected using real-time PCR.Antagonistic,receptor-specific antibodies were used to investigate the effects of TRAIL-R1 or TRAIL-R2 inhibition.RESULTS:Dose-dependent increases in uPA and IL-8 expression were detected following TRAIL stimulation in PDAC cells.These effects were inhibited when TRAIL-R1 but not TRAIL-R2 was blocked.Overexpression of TRAF2 or Bcl-xL strongly increased TRAIL-mediated upregulation of uPA and IL-8.CONCLUSIONS:In PDAC cells,TRAIL strongly induced uPA and IL-8 via TRAIL-R1.This response was further enhanced in cells overexpressing TRAF2 and Bcl-xL.Therefore,inhibition of the non-apoptotic "side-effects" of TRAIL treatments by inactivation of TRAF2 and Bcl-xL might represent additional relevant strategies for the treatment of pancreatic cancer.

Cis-hydroxyproline-induced inhibition of pancreatic cancer cell growth is mediated by endoplasmic reticulum stress

AIM： To investigate the biological effects of cishydroxyproline （CHP） on the rat pancreatic carcinoma cell line DSL6A, and to examine the underlying molecular mechanisms. METHODS： The effect of CHP on DSL6A cell proliferation was assessed by using BrdU incorporation. The expression of focal adhesion kinase （FAK） was characterized by Western blotting and immunofluorescence. Induction of endoplasmic reticulum （ER） stress was investigated by using RT-PCR and Western blotting for the glucose-related protein-78 （GRP78） and growth arrest and DNA inducible gene （GADD153）. Cell viability was determined through measuring the metabolic activity based on the reduction potential of DSL6A cells. Apoptosis was analyzed by detection of caspase-3 activation and cleavage of poly（ADP-ribose） polymerase （PARP） as well as DNA laddering. RESULTS： In addition to inhibition of proliferation, incubation with CHP induced proteolytic cleavage of FAK and a delocalisation of the enzyme from focal adhesions, followed by a loss of cell adherence. Simultaneously, we could show an increased expression of GRP78 and GADD153, indicating a CHP-mediated activation of the ER stress cascade in the DSL6A cell line. Prolonged incubation of DSL6A cells with CHP finally resulted in apoptotic cell death. Beside L-proline, the inhibition of intracellular proteolysis by addition of a broad spectrum protease inhibitor could abolish the effects of CHP on cellular functions and the molecular processes. In contrast, impeding the activity of apoptosis-executing caspases had no influence on CHP-mediated cell damage.CONCLUSION： Our data suggest that the initiation of ER stress machinery by CliP leads to an activation of intracellular proteolytic processes, including caspaseindependent FAK degradation, resulting in damaging pancreatic carcinoma cells.

One size does not fit all for pancreatic cancers: A review on rare histologies and therapeutic approaches

Exocrine pancreatic neoplasms represent up to 95%of pancreatic cancers(PCs)and are widely recognized among the most lethal solid cancers,with a very poor 5-year survival rate of 5%-10%.The remaining<5%of PCs are neuroendocrine tumors that are usually characterized by a better prognosis,with a median overall survival of 3.6 years.The most common type of PC is pancreatic ductal adenocarcinoma(PDAC),which accounts for roughly 85%of all exocrine PCs.However up to 10%of exocrine PCs have rare histotypes,which are still poorly understood.These subtypes can be distinguished from PDAC in terms of pathology,imaging,clinical presentation and prognosis.Additionally,due to their rarity,any knowledge regarding these specific histotypes is mostly based on case reports and a small series of retrospective analyses.Therefore,treatment strategies are generally deduced from those used for PDAC,even if these patients are often excluded or not clearly represented in clinical trials for PDAC.For these reasons,it is essential to collect as much information as possible on the management of PC,as assimilating it with PDAC may lead to the potential mistreatment of these patients.Here,we report the most significant literature regarding the epidemiology,typical presentation,possible treatment strategies,and prognosis of the most relevant histotypes among rare PCs.

THE CYTOTOXIC EFFECTS OF CRUDE BILE ON HUMAN PANCREATIC CANCER CELL LINES

Objective To identify effects of bile acids on pancreatic cancer, The ultrastructure and growth of PANC-1 and MIA PaCa-2 cell lines in crude bile modified medium were studied. Methods The growth of PANC-1 and MIA PaCa-2 cells in RPMI 164o with or without 1%, 2% and 4% of the purified crude bile (containing total bile acids 1o. 17mmol/L) was assessed for 2, 4, 6, 8d by using MTT assay to determine inhibitory rate- The cell surface and intracellular ultrastructure of PANC-1 cells was investigated by SEM and TEM at 24h and 48h, respectively. Results The proliferation of both cell lines in bile treated medium were greatly retarded (P <o. oo1). The inhibitory rate of 1 %, 2% and 4% bile on Panc-1 cells in 4d were 38%, 6o% and 66%, respectively (P <o. o5), on MIA PaCa-2 cells at 4d were 28%, 39% and 52%, respectively (P <o. o5). The ceIls grown in bile for 48h lost their microvilli, their mitochondria and other organelles became vacuolated. Conclusion The bile acids in bile has cytotoxicity on PANC-1 and MIAPACA-2 cells, which may inhiblt pancreatic cancer progress in patients clinically.

Low molecular weight heparin suppresses lymphatic endothelial cell proliferation induced by vascular endothelial growth factor C in vitro

Background Pancreatic cancer is one of the most aggressive human malignancies. Lymphangiogenesis plays an important role in lymph node metastasis of many solid tumors. It is well known that low molecular weight heparins （LMWHs） can inhibit cell growth, cell invasion and angiogenesis, which are key processes in tumor progression. Methods We measured the expression of vascular endothelial growth factor C （VEGF-C） in pancreatic cancer cells （PANC-1） using reverse transcription-polymerase chain reaction （RT-PCR） and Western blotting. We used an in vitro assay to evaluate the anti-lymphangiogenic effect of an LMWH, Fragmin, on human lymphatic endothelial cell （HLEC） proliferation. Results Fragmin at a low concentration can effectively inhibits HLEC proliferation induced by VEGF-C. VEGF-C secreted by PANC-1 cells stimulated HLEC proliferation. Low concentration LMWH suppressed HLEC proliferation induced by VEGF-C but did not affect proliferation or VEGF-C expression of PANC-1 cells, whereas high concentrations of LMWH inhibited PANC-1 cell proliferation. Conclusions These results suggest that VEGF-C released by cancer cells plays an important role in promoting HLEC proliferation. The LMWH Fragmin has anti-lymphangiogenic effects and may inhibit lymphatic metastasis in pancreatic cancer.