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.

Extraordinary response of metastatic pancreatic cancer to apatinib after failed chemotherapy: A case report and literature review

Chemotherapy has limited efficacy in the treatment of advanced and metastatic pancreatic cancer(PC), and has serious side effects. The development of novel effective agents, especially targeted therapy, is essential for patients with PC. We present a 58-year-old Chinese woman initially diagnosed with locally advanced PC. As the disease progressed to Stage Ⅳ, the patient was unable to tolerate chemotherapy after the fourth-line treatment. She was then treated with apatinib, a novel and highly selective tyrosine kinase inhibitor of vascular endothelial growth factor receptor-2 and achieved a progression-free-survival of 7 mo. All drug-related side effects were well controlled with medication. To the best of our knowledge, this is the first case of PC which responded to apatinib. Considering this remarkable response, apatinib may be a promising agent in the treatment of PC. We also reviewed the literature on chemotherapy and targeted therapy, especially the anti-angiogenesis therapy for patients with PC, and investigated the effect of apatinib in other solid tumors as well.

S100A4 siRNA Inhibits Human Pancreatic Cancer Cell Invasion In Vitro

Objective Pancreatic cancer is one of the most deadly cancers, which is characterized by its high metastatic potential. S100A4 is a major prometastatic protein involved in tumor invasion and metastasis which precise role in pancreatic cancer has not been fully investigated. We knocked down the S100A4 gene in the Bxpc-3 pancreatic cancer cell line via RNA interference to study the changes in cell behavior. Methods Real-time polymerase chain reaction and western blotting were used to detect mRNA and protein expression levels of S100A4, matrix metalloproteinase （MMP）-2, E-cadherin and thrombospondin （TSP）-I. Transwell chambers were used to detect the migration and invasion abilities; a cell adhesion assay was used to detect adhesion ability; colony forming efficiency was used to detect cell proliferation; flow cytometry was used to detect apoptosis. Results S100A4 mRNA expression was reduced to 17% after transfection with SIOOA4-siRNA, and protein expression had a similar trend, mRNA and protein expression of MMP-2 was reduced and that of E-cadherin and TSP-1 was elevated, indicating that S100A4 affects their expression. S100A4-silenced cells exhibited a marked decrease in migration and invasiveness and increased adhesion, whereas overall proliferation and apoptosis were not overtly altered. Conclusion S100A4 and its downstream factors play important roles in pancreatic cancer invasion, and silencing AIOOA4 can significantly contain the invasiveness of pancreatic cancer.

Apoptosis of human pancreatic cancer cells induced by Triptolide

AIM: To investigate apoptosis in human pancreatic cancer cells induced by Triptolide (TL), and the relationship between this apoptosis and expression of caspase-3' bcl-2 and bax. METHODS: Human pancreatic cancer cell line SW1990 was cultured in DMEM media for this study. MTT assay was used to determine the cell growth inhibitory rate in vitro. Flow cytometry and TUNEL assay were used to detect the apoptosis of human pancreatic cancer cells before and after TL treatment. RT-PCR was used to detect the expression of apoptosis-associated gene caspase-3' bcl-2 and bax. RESULTS: TL inhibited the growth of human pancreatic cancer cells in a dose-and time-dependent manner. TL induced human pancreatic cancer cells to undergo apoptosis with typically apoptotic characteristics. TUNEL assay showed that after the treatment of human pancreatic cancer cells with 40 ng/mL TL for 12 h and 24 h, the apoptotic rates of human pancreatic cancer cells increased significantly. RT-PCR demonstrated that caspase-3 and bax were significantly up-regulated in SW1990 cells treated with TL while bcl-2 mRNA was not. CONCLUSION: TL is able to induce the apoptosis in human pancreatic cancer cells. This apoptosis may be mediated by up-regulating the expression of apoptosis- associated caspase-3 and bax gene.

Expression of p53, p16 and COX-2 in pancreatic cancer with tissue microarray

BACKGROUND: Pancreatic cancer development and progression is driven by the accumulation of genetic changes. In this study we constructed tissue microarray containing specimens from pancreatic cancer, adjacent non-cancer tissue and normal tissue to survey the expression of p53, p16 and cyclooxyganase-2 (COX-2). METHODS: Tissue microarray containing 337 specimens from different stages of pancreatic cancer, adjacent noncancer tissue and normal tissues was constructed, and the expression of p53, p16 and COX-2 was assayed by immunohistochemistry to consecutive formalin-fixed tissue microarray sections. RESULTS: The expression of p53, p16 and COX-2 was significantly higher in tumorous tissues than in non-tumorons ones. A significant relationship was observed between p53 and COX-2, or p16 and COX-2. But no obvious correlation was seen between p53 and p16 expressions. Logistic regression analysis showed p53 and COX-2 as dependent predictors in pancreatic carcinogenesis, and a reciprocal relationship to neoplastic progression between p53 and COX-2. CONCLUSION: Combination analysis of p53 and COX-2 may be useful in predicting pancreatic carcinogenesis.

Expression of cell cycle regulator p57^(kip2), cyclinE protein and proliferating cell nuclear antigen in human pancreatic cancer: An immunohistochemical study

AIM： To investigate the effects of p57^kip2, cyclinE protein and proliferating cell nuclear antigen （PCNA） on occurrence and progression of human pancreatic cancer. METHODS： The expression of p57^kip2, cyclinE protein and PCNA in tumor tissues and adjacent tissues from 32 patients with pancreatic cancer was detected by SP immunohistochemical technique. RESULTS： The positive expression rate of p57^kip2 protein in tumor tissues was 46.9%, which was lower than that in adjacent pancreatic tissues （χ^2 = 5.317, P〈0.05）. p57^kip2 protein positive expression remarkably correlated with tumor cell differentiation （P〈0.05）, but not with lymph node metastasis （P〉0.05）. The positive expression rate of cyclinE protein in tumor tissues was 68.8%, which was higher than that in adjacent pancreatic tissues （χ^2 = 4.063, P〈0.05）. CyclinE protein positive expression significantly correlated with tumor cell differentiation and lymph node metastasis （P〈0.05）. The positive expression rate of PCNA in the tumor tissues was 71.9%, which was higher than that in adjacent pancreatic tissues （χ^2 = 5.189, P〈0.05）. PCNA positive expression remarkably correlated with tumor cell differentiation and lymph node metastasis （P〈0.05）. CONCLUSION： The decreased expression of p57^kip2 and/or overexpression of cyclinE protein and PCNA may contribute to the occurrence and progression of pancreatic cancer. p57^kip2, cyclinE protein, and PCNA play an important role in occurrence and progression of pancreatic cancer.

Clinicopathological significance of p53 and mdm2 protein expression in human pancreatic cancer

AIM: To study the clinicopathological significance of p53 and mdm2 protein expression in human pancreatic cancer. METHODS: To investigate the expression of p53 and mdm2 in pancreatic cancer by immunohistochemistry, and the relationships between the p53 and mdm2 protein expression and clinicopathological parameters in pancreatic cancer.RESULTS: The positive expression of p53 protein was found in 40 of 59 patients (67.8%) and that of mdm2 protein in 17 of 59 patients (28.8%). No obvious relationships were found between p53 as well as mdm2 expression and sex, tumor site, TNM staging and histological differentiation. p53 expression was increased in patients younger than 65 years old, while mdm2 had no relationship with age. The survival time of the patients with the positive expression of p53 and mdm2 proteins was obviously shorter than the other groups. CONCLUSION: Both p53 and mdm2 presented relatively high expression in human pancreatic cancer. The overexpression of p53 and mdm2 might reflect the malignant proliferation of pancreatic cancer and their co-expression might be helpful to evaluate the prognosis of the patients with pancreatic cancer.

Involvement of eicosanoids in the pathogenesis of pancreatic cancer: the roles of cyclooxygenase-2 and 5-lipoxygenase

The interplay between inflammation and cancer progression is a growing area of research. A combination of clinical, epidemiological, and basic science investigations indicate that there is a relationship between inflammatory changes in the pancreas and neoplastic progression. Diets high in ω-6 polyunsaturated fatty acids provide increased substrate for arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) to form eicosanoids. These eicosanoids directly contribute to pancreatic cancer cell proliferation. Both COX-2 and 5-LOX are upregulated in multiple cancer types, including pancreatic cancer. In vitro studies using pancreatic cancer cell lines have demonstrated upregulation of COX-2 and 5-LOX at both the mRNA and protein levels. When COX-2 and 5-LOX are blocked via a variety of mechanisms, cancer cell proliferation is abrogated both in vitro and in vivo. The mechanism of COX-2 has been shown to include effects on apoptosis as well as angiogenesis. 5-LOX has been implicated in apoptosis. The use of COX-2 and 5-LOX inhibitors in clinical studies in patients with pancreatic cancer has been limited. Patient enrollment has been restricted to those with advanced disease which makes evaluation of these drugs as chemopreventive agents difficult. COX-2 and 5-LOX expression have been shown to be present during the early neoplastic changes of pancreatic cancer, well before progression to invasive disease. This indicates that the ideal role for these interventions is early in the disease process as preventive agents, perhaps in patients with chronic pancreatitis or hereditary pancreatitis.

Clinicopathological significance of Bcl-2 and Bax protein expression in human pancreatic cancer

AIM: To assess the clinicopathological significance of the expression of the apoptosis-inhibitory Bcl-2 protein (pBcl-2) and the apoptosis-promoting Bax protein (pBax) in human invasive ductal carcinomas (IDCs) of the pancreas. METHODS: Fifty-nine surgical specimens of IDCs of the pancreas were stained immunohistochemically to detect pBcl-2 and pBax expressions whose correlation to tumor classification, staging, and prognosis was analyzed by univariate and multivariate analyses. RESULTS: The expression of pBcl-2 and pBax was detected in 21 of 59 (35.6%) and in 29 of 59 (49.2%) patients with IDCs of the pancreas, respectively. Neither pBcl-2 nor pBax alone was correlated to TIMM staging and differentiation degree of IDCs of the pancreas according to univariate analysis. By Mantel-Cox test, the median survival time after surgery for pBcl-2(+) and pBcl-2(-) groups were 14.3 and 7.3 mo, respectively (x^2=9.357, P=0.002) and that for pBax(+) and pBax(-) groups were 12.9 and 10.2 mo, respectively (x^2=0.285, P＞0.05). Contingency coefficient between pBcl-2 and pBax expression was 0.298, indicating that there was correlation between them (x^2=5.74, P＜0.05). The median survival time after surgery for pBcl-2(+)pBax(+) and pBcl-2(+)pBax(-) groups were 14.3 and 14.1 mo, respectively, and that for pBcl-2 (-)pBax(+) and pBcl-2(-)pBax(-) groups were 5.9 and 9.9 mo, respectively. There was a significant difference between pBd-2(+)pBax(+) and pBd-2(-)pBax(+) (x^2=5.06, P＜0.05), such was the case for pBcl-2(+)pBax(+) and pBd-2(-)pBax(-) (x~ 2=7.18, P＜0.01). Cox proportional hazards model for multivariate analysis was applied, indicating that pBcl-2, TNM staging, age and pBax were high risk factors of post-surgical survival time. CONCLUSION: Both pBcl-2 and pBax have high expression in IDCs of the pancreas, indicating that co-expression of pBcl-2 and pBax is a good indicator of favorable prognosis in IDCs of the pancreas.

Nuclear receptors and pathogenesis of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a median overall survival time of 5 mo and the five years survival less than 5%, a rate essentially unchanged over the course of the years. A well defined progression model of accumulation of genetic alterations ranging from single point mutations to gross chromosomal abnormalities has been introduced to describe the origin of this disease. However, due to the its subtle nature and concurring events PDAC cure remains elusive. Nuclear receptors (NR) are members of a large superfamily of evolutionarily conserved ligand-regulated DNA-binding transcription factors functionally involved in important cellular functions ranging from regulation of metabolism, to growth and development. Given the nature of their ligands, NR are very tempting drug targets and their pharmacological modulation has been widely exploited for the treatment of metabolic and inflammatory diseases. There are now clear evidences that both classical ligand-activated and orphan NR are involved in the pathogenesis of PDAC from its very early stages; nonetheless many aspects of their role are not fully understood. The purpose of this review is to highlight the striking connections that link peroxisome proliferator activated receptors, retinoic acid receptors, retinoid X receptor, androgen receptor, estrogen receptors and the orphan NR Nur, chicken ovalbumin upstream promoter transcription factor II and the liver receptor homologue-1 receptor to PDAC development, connections that could lead to the identification of novel therapies for this disease.

Comparative analysis of clinicopathological correlations of cyclooxygenase-2 expression in resectable pancreatic cancer

AIM:To perform a comparative analysis of clinicopathological correlations of cyclooxygenase2 (COX2) expression in pancreatic cancer, examined by monoclonal and polyclonal antibodies.METHODS: The COX2 expression in 85 resection specimens of pancreatic ductal adenocarcinoma was immunohistochemically examined using both monoclonal and polyclonal antibodies. The final immunoscores were obtained by multiplying the percentage of positive cells with the numeric score reflecting the staining intensity.COX2 expression levels were classified into three categories (0, 1+, and 2+) and the clinicopathological correlations were statistically evaluated and analyzed.RESULTS: The positive tumor expression rates of COX2 were 80.5% using monoclonal antibody and 69.4% using polyclonal antibody. In the KaplanMeier analysis, no significant correlations were found between levels of COX2 expression and overall survival (OS), but trends to longer OS were found in COX2 negative cases using monoclonal antibody. Significantly longer disease free survival was revealed in COX2 negative cases using monoclonal antibody (P = 0.019). No correlations between COX2 expression levels and grade (G), tumor (T) status and nodal (N) status were demonstrated. Low histological grade showed a strong association with a longer OS (P < 0.001). Correlation of survival and T status revealed a shorter OS in T3 tumors, but the results reached only marginal statistical significance (P = 0.070). In the multivariate Cox proportional hazards regression model, histological grade, T and N status remained valuable predictors of a worse survival with borderline significance for T [hazards ratio (HR) = 4.18 for G (if G = 3, P < 0.001); HR = 1.64 for T (if T = 3, P = 0.065); HR = 2.53 for N (if N = 1, P = 0.006)]. Higher grade, T or N status was associated with a worse OS. CONCLUSION: The immunohistochemically assessed level of COX2 expression does not seem to represent a valuable independent prognostic factor and is not superior to the conventional prognostic factors.

Embryonic stem cell factors and pancreatic cancer

Pancreatic ductal adenocarcinoma(PDAC),the most common type of pancreatic tumor,is a highly aggressive human cancer with the lowest five-year survival rate of any human maligancy primarily due to its earlymetastasis and lack of response to chemotherapy and radiation.Recent research suggests that PDAC cells comprise a hierarchy of tumor cells that develop around a population of cancer stem cells(CSCs),a small and distinct population of cancer cells that mediates tumoregenesis,metastasis and resistance to standard treatments.Thus,CSCs could be a target for more effective treatment options.Interestingly,pancreatic CSCs are subject to regulation by some of key embryonic stem cell(ESC)transctiption factors abberently expressed in PDAC,such as SOX2,OCT4 and NANOG.ESC transcription factors are important DNA-binding proteins present in both embryonic and adult somatic cells.The critical role of these factors in reprogramming processes makes them essential not only for embryonic development but also tumorigenesis.Here we provide an overview of stem cell transcription factors,particularly SOX2,OCT4,and NANOG,on their expression and function in pancreatic cancer.In contrast to embryonic stem cells,in which OCT4 and SOX2 are tightly regulated and physically interact to regulate a wide spectrum of target genes,de novo SOX2 expression alone in pancreatic cancer cells is sufficient to promote self-renewal,dedifferentiation and imparting stemness characteristics via impacting specific cell cycle regulatory genes and epithelial-mesnechymal transtion driver genes.Thus,targeting ESC factors,particularly SOX2,could be a worthy strategy for pancreatic cancer therapy.

Decreased expression of DAB2IP in pancreatic cancer with wild-type KRAS

BACKGROUND: KRAS mutation plays an important role in the pathogenesis of pancreatic cancer. However, the role of wild-type KRAS in the progression of pancreatic cancer remains unknown. The present study was to investigate the expression of the Ras GTPase activating protein (DAB2IP) in pancreatic cancer and its clinical significance. METHODS: The expression of DAB2IP in pancreatic cancer cell lines and normal human pancreatic ductal epithelial cells was analyzed by Western blotting and realtime quantitative reverse transcription-PCR (qRT-PCR). The KRAS mutational types of pancreatic cancer tissues obtained from pancreatic cancer patients (n=20) were also analyzed. Subsequently, DAB2IP expression was detected in pancreatic cancer tissues, adjacent and normal pancreatic tissues (n=2) by immunohistochemistry, and the relationship between DAB2IP expression and the clinical characteristics of patients was evaluated. RESULTS: Western blotting and qRT-PCR results showed that DAB2IP expression in pancreatic cancer cells with wild-type KRAS was lower than that in those with mutation-type KRAS and normal human pancreatic ductal epithelial cells (P【0.05). Immunohistochemistry showed that DAB2IP expression was lower in pancreatic cancer tissues than that in adjacent and normal pancreatic tissues (Z=-4.000, P=0.000). DAB2IP expression was lower in pancreatic cancer patients with the wild-type KRAS gene than that in those with KRAS mutations (WilcoxonW=35.000, P=0.042). Furthermore,DAB2IP expression in patients with perineurial invasion was lower than that in those without invasion (WilcoxonW=71.500, P=0.028). DAB2IP expression was lower in patients with more advanced stage than that in those with early clinical stage (WilcoxonW=54.000, P=0.002). CONCLUSIONS: DAB2IP expression was reduced in patients with pancreatic cancer compared with those with no cancer. DAB2IP expression was correlated with the KRAS gene, perineurial invasion and clinical stage of the disease. Our data indicated that DAP2IP expression can be used as a potential prognostic indicator and a promising molecular target for therapeutic intervention in patients with pancreatic cancer.

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.

MiR-301a transcriptionally activated by HIF-2αpromotes hypoxiainduced epithelial-mesenchymal transition by targeting TP63 in pancreatic cancer

BACKGROUND Pancreatic cancer(PC)is one of the deadliest cancers worldwide.PC metastasis involves a complex set of events,including epithelial-mesenchymal transition(EMT),that increase tumor cell invasiveness.Recent evidence has shown that hypoxia is a major EMT regulator in pancreatic cancer cells and facilitates metastasis;however,the mechanisms remain elusive.AIM To investigate the role of miR-301a in hypoxia-induced EMT in PC cells.METHODS Real-time PCR and Western blot analysis were used to detect the expression of miR-301a and EMT markers in PDAC cells cultured in hypoxic and normoxic conditions.Western blot analysis was used to detect the expression of EMT markers in PDAC cells with miR-301a overexpression.Wound healing assay and Transwell assay were used to detect the migration capabilities of PDAC cells with miR-301a overexpression and knockout.Luciferase assay was used to detect the miR-301a promoter and the 3’untranslated region activity of TP63.Orthotopic PC mouse models were used to study the role of miR-301a in metastasis of PDAC cells in vivo.In situ hybridization assay was used to detect the expression of miR-301a in PDAC patient samples(adjacent paratumor and paired tumor tissues).RESULTS Hypoxic environment could directly promote the EMT of PC cells.The expression level of miR-301a was increased in a HIF2αdependent manner in hypoxia-cultured CFPAC-1 and BxPC-3 cells.Overexpression of miR-301a enhanced the hypoxia-induced EMT of PC cells,while knocking out miR-301a result in the suppression of hypoxia-induced EMT.TP63 was a direct target of miR-301a and involved in the metastatic process of PC cells.Furthermore,miR-301a upregulation facilitated PDAC distant metastasis and lymph node metastasis in vivo.Additionally,miR-301a overexpression was indicative of aggressive clinicopathological behaviors and poor prognosis.CONCLUSION The newly identified HIF-2α-miR301a-TP63 signaling pathway may play a crucial role in hypoxia-induced EMT in PDAC cells.

Autoimmune pancreatitis and pancreatic cancer:Epidemiological aspects and immunological considerations

Ordinary chronic pancreatitis is a well-known risk factor for pancreatic cancer,whereas such an association with autoimmune pancreatitis(AIP)is widely debated.Due to the rarity of the latter disorder,there are few specific clinical and epidemiological studies investigating the relation between AIP and pancreatic cancer,which do not seem to support it.However,these studies are affected by several limitations and,therefore,a link between AIP(and,specifically,type 1 AIP)and pancreatic cancer cannot be ruled out definitively on this basis.Moreover,several immunopathological aspects of type 1 AIP and,in general,immunoglobulin G4-related disease can create an immunological context that may impair the tumoral immunosurveillance and promote the pancreatic carcinogenesis and its progression.In detail,Th2 immunological dominance,type 2 macrophage polarization and basophil infiltration observed in type 1 AIP,may play a permissive role in creating a favorable immunological environment for pancreatic carcinogenesis,in addition to the immunosuppressive therapies that can be used in these patients.

αV integrin:A new gastrin target in human pancreatic cancer cells

AIM： To analyse αv integrin expression induced by gas- trin in pancreatic cancer models.METHODS： αv integrin mRNA expression in human pan- creatic cancer cells was analysed using a ＂cancer genes＂ array and confirmed by real-time reverse transcription- polymerase chain reaction （PCR）. Western blotting and semi-quantitative immunohistochemistry were used to examine protein levels in human pancreatic cancer cell lines and pancreatic tissues, respectively, The role of αv integrin on gastrin-induced cell adhesion was examined using blocking anti-αv integrin monoclonal antibodies. Adherent cells were quantified by staining with crystal violet.RESULTS： Using a ＂cancer genes＂ array we identi- fied c^v integrin as a new gastrin target gene in human pancreatic cancer cells. A quantitative real-time PCR approach was used to confirm αv integrin gene expression. We also demonstrate that Src family kinases and the PI 3-kinase, two signalling pathways specifically activated by the CCK-2 receptor （CCK2R）, are involved in gastrin-mediated αv integrin expression. In contrast, inhibition of the ERK pathway was without any effect on αv integrin expression induced by gastrin. Our results also show that gastrin modulates cell adhesion via αv integrins. Indeed, in vitro adhesion assays performed on fibronectin show that gastrin significantly increases adhesion of pancreatic cancer cells. The use of blocking anti-αv integrin monoclonal antibodies completely reversed the increase in cell-substrate adhesion induced by gastrin. In addition, we showed in vivo that the targeted CCK2R expression in the pancreas of Elas-CCK2 mice, leads to the overexpression of αv integrin. This process may contribute to pancreatic turnout development observed in these transgenic animals.CONCLUSION： αv integrin is a new gastrin target in pancreatic cancer models and contributes to gastrin effects on cell adhesion.

Promising xenograft animal model recapitulating the features of human pancreatic cancer

BACKGROUND Multiple sites of metastasis and desmoplastic reactions in the stroma are key features of human pancreatic cancer(PC).There are currently no simple and reliable animal models that can mimic these features for accurate disease modeling.AIM To create a new xenograft animal model that can faithfully recapitulate the features of human PC.METHODS Interleukin 2 receptor subunit gamma(IL2RG)gene knockout Syrian hamster was created and characterized.A panel of human PC cell lines were transplanted into IL2RG knockout Syrian hamsters and severe immune-deficient mice subcutaneously or orthotopically.Tumor growth,local invasion,remote organ metastasis,histopathology,and molecular alterations of tumor cells and stroma were compared over time.RESULTS The Syrian hamster with IL2RG gene knockout(named ZZU001)demonstrated an immune-deficient phenotype and function.ZZU001 hamsters faithfully recapitulated most features of human PC,in particular,they developed metastasis at multiple sites.PC tissues derived from ZZU001 hamsters displayed desmoplastic reactions in the stroma and epithelial to mesenchymal transition phenotypes,whereas PC tissues derived from immune-deficient mice did not present such features.CONCLUSION ZZU001 hamsters engrafted with human PC cells are a superior animal model compared to immune-deficient mice.ZZU001 hamsters can be a valuable animal model for better understanding the molecular mechanism of tumorigenesis and metastasis and the evaluation of new drugs targeting human PC.

Expression and Significance of HIF-1α and HIF-2α in Pancreatic Cancer

Summary： The expression levels of hypoxia-inducible factor lalpha （HIF-lct） and HIF-2a in pancreatic cancer （PC） and their association with clinicopathologic characteristics were investigated in order to elucidate their roles in the development of PC. HIF-1 α and HIF-2α mRNA levels in 20 patients with PC were detected by quantitative real-time polymerase chain reaction. The expression of HIF-1α and HIF-2α protein in samples from other 90 patients with PC was measured by immunohistochemistry. Correlations between the expression of HIF-1 α or HIF-2α and clinicopathologica features and prognosis were analyzed. The expression of both HIF-1α and HIF-2α mRNA was up-regulated in most cancer tis- sues （P〈0.05）. HIF-1α staining was weakly positive in most cancer tissues and strongly positive in ad- jacent pancreas tissues （P〈0.05）. Clinicopathologic analysis revealed that relatively strong HIF-1α ex- pression in cancer tissues was related to greater invasion （P〈0.05）, higher tumor pathologic stage （P〈0.05）, higher American Joint Committee on Cancer （AJCC） stage （P〈0.05） and shorter overall sur- vival time （P〈0.05）. Conversely, HIF-2α staining was strongly positive in most cancer tissues and weakly positive in adjacent pancreas tissues. Clinicopathologic analysis revealed that relatively strong HIF-2α expression in cancer tissues was related to less invasion （P〈0.05）, lower tumor pathologic stage （P〈0.05）, lower AJCC stage （P〈0.05） and longer overall survival time （P〈0.05）. Moreover, the HIF-1αhigh/HIF-2αlow group showed a shorter survival time than the HIF-1αlow/HIF-2αhigh group. In con- clusion, although HIF-1α and HIF-2α mRNA expression patterns are the same, their protein expression patterns are significantly different and they play different roles in PC. Combined analysis of HIF-1α and HIF-2α expression might be useful to predict the prognosis of patients with PC.

Apolipoprotein E2 inhibits mitochondrial apoptosis in pancreatic cancer cells through ERK1/2/CREB/BCL-2 signaling

Background: Apolipoprotein E2(ApoE2) is a pleiotropic protein that influences several aspects of cancer metabolism and development. Evading apoptosis is a vital factor for facilitating cancer cell growth. However, the role and mechanism of ApoE2 in regulating cell apoptosis of pancreatic cancer remain unclear. Methods: In this study, we firstly detected the m RNA and protein expressions of ApoE2 in PANC-1 and Capan-2 cells by real-time polymerase chain reaction and Western blotting. We then performed TUNEL and flow cytometric analyses to explore the role of recombinant human ApoE2, p CMV6-ApoE2 and si ApoE2 in the apoptosis of PANC-1 and Capan-2 cells. Furthermore, we investigated the molecular mechanism through which ApoE2 affected apoptosis in PANC-1 cells using immunofluorescence, immunoprecipitation, Western blotting and co-immunoprecipitation analysis. Results: ApoE2 phosphorylated ERK1/2 and inhibited pancreatic cancer cell apoptosis. In addition, our data showed that ApoE2/ERK1/2 altered the expression and mitochondrial localization of BCL-2 via activating CREB. ApoE2/ERK1/2/CREB also increased the total BCL-2/BAX ratio, inhibited the opening of the mitochondrial permeability transition pore and the depolarization of mitochondrial transmembrane potential, blocked the leakage of cytochrome-c and the formation of the apoptosome, and consequently, suppressed mitochondrial apoptosis. Conclusions: ApoE2 regulates the mitochondrial localization and expression of BCL-2 through the activation of the ERK1/2/CREB signaling cascade to evade the mitochondrial apoptosis of pancreatic cancer cells. ApoE2 may be a distinct prognostic marker and a potential therapeutic target for pancreatic cancer.