Clinicopathological significance of hypoxia-inducible factor-1alpha expression in human pancreatic carcinoma

High hypoxia status in pancreatic cancer is associated with multiple hallmarks of an immunosuppressive tumor microenvironment

Introduction

Pancreatic ductal adenocarcinoma (PDAC), the most common form of pancreatic cancer, is a particularly lethal disease that is often diagnosed late and is refractory to most forms of treatment. Tumour hypoxia is a key hallmark of PDAC and is purported to contribute to multiple facets of disease progression such as treatment resistance, increased invasiveness, metabolic reprogramming, and immunosuppression.

Methods

We used the Buffa gene signature as a hypoxia score to profile transcriptomics datasets from PDAC cases. We performed cell-type deconvolution and gene expression profiling approaches to compare the immunological phenotypes of cases with low and high hypoxia scores. We further supported our findings by qPCR analyses in PDAC cell lines cultured in hypoxic conditions.

Results

First, we demonstrated that this hypoxia score is associated with increased tumour grade and reduced survival suggesting that this score is correlated to disease progression. Subsequently, we compared the immune phenotypes of cases with high versus low hypoxia score expression (HypoxiaHI vs. HypoxiaLOW) to show that high hypoxia is associated with reduced levels of T cells, NK cells and dendritic cells (DC), including the crucial cDC1 subset. Concomitantly, immune-related gene expression profiling revealed that compared to HypoxiaLOW tumours, mRNA levels for multiple immunosuppressive molecules were notably elevated in HypoxiaHI cases. Using a Random Forest machine learning approach for variable selection, we identified LGALS3 (Galectin-3) as the top gene associated with high hypoxia status and confirmed its expression in hypoxic PDAC cell lines.

Discussion

In summary, we demonstrated novel associations between hypoxia and multiple immunosuppressive mediators in PDAC, highlighting avenues for improving PDAC immunotherapy by targeting these immune molecules in combination with hypoxia-targeted drugs.

Correlation between hypoxia and HGF/c-MET expression in the management of pancreatic cancer

Pancreatic cancer (PC) is very deadly and difficult to treat. The presence of hypoxia has been shown to increase the probability of cancer developing and spreading. Pancreatic ductal adenocarcinoma (PDAC/PC) has traditionally viewed a highly lethal form of cancer due to its high occurrence of early metastases. Desmoplasia/stroma is often thick and collagenous, with pancreatic stellate cells as the primary source (PSCs). Cancer cells and other stromal cells interact with PSCs, promoting disease development. The hepatocyte growth factor (HGF)/c-MET pathway have been proposed as a growth factor mechanism mediating this interaction. Human growth factor (HGF) is secreted by pancreatic stellate cells (PSCs), and its receptor, c-MET, is generated by pancreatic cancer cells and endothelial cells. Hypoxia is frequent in malignant tumors, particularly pancreatic (PC). Hypoxia results from limitless tumor development and promotes survival, progression, and invasion. Hypoxic is becoming a critical driver and therapeutic target of pancreatic cancer as its hypoxia microenvironment is defined. Recent breakthroughs in cancer biology show that hypoxia promotes tumor proliferation, aggressiveness, and therapeutic resistance. Hypoxia-inducible factors (HIFs) stabilize hypoxia signaling. Hypoxia cMet is a key component of pancreatic tumor microenvironments, which also have a fibrotic response, that hypoxia, promotes and modulates. c-Met is a tyrosine-protein kinase. As describe it simply, the MET gene in humans' codes for a protein called hepatocyte growth factor receptor (HGFR). Most cancerous tumors and pancreatic cancer in particular, suffer from a lack of oxygen (PC). Due to unrestrained tumor development, hypoxia develops, actively contributing to tumor survival, progression, and invasion. As the processes by which hypoxia signaling promotes invasion and metastasis become clear, c-MET has emerged as an important determinant of pancreatic cancer malignancy and a potential pharmacological target. This manuscript provides the most current findings on the role of hypoxia and HGF/c-MET expression in the treatment of pancreatic cancer.

Enamine N-Oxides: Synthesis and Application to Hypoxia-Responsive Prodrugs and Imaging Agents

Tumor hypoxia induces the large-scale adaptive reprogramming of cancer cells, promoting their transformation into highly invasive and metastatic species that lead to highly negative prognoses for cancer patients. We describe the synthesis and application of a hypoxia-responsive trigger derived from previously inaccessible enamine N-oxide structures. Hypoxia-dependent reduction of this motif by hemeproteins results in the concomitant activation of a caged molecule and a latent electrophile. We exploit the former in a hypoxia-activated prodrug application using a caged staurosporine molecule as a proof-of-principle. We demonstrate the latter in in vivo tumor labeling applications with enamine-N-oxide-modified near-infrared probes. Hypoxia-activated prodrug development has long been complicated by the heterogeneity of tumor hypoxia in patients. The dual drug release and imaging modalities of the highly versatile enamine N-oxide motif present an attractive opportunity for theranostic development that can address the need not only for new therapeutics but paired methods for patient stratification.

HIF-1α-Mediated Telomerase Reverse Transcriptase Activation Inducing Autophagy Through Mammalian Target of Rapamycin Promotes Papillary Thyroid Carcinoma Progression During Hypoxia Stress

Background: It is important to properly understand the molecular mechanisms of aggressive tumors among papillary thyroid carcinomas (PTCs) that are often the most indolent. Hypoxia inducible factor-1α (HIF-1α), induced by hypoxia, plays pivotal roles in the development and metastasis of the many tumors, including PTCs. Upregulation of telomerase reverse transcriptase (TERT) activity is found in highly invasive PTCs. Further, previous studies have reported that autophagy serves as a protective mechanism to facilitate PTC cell survival. We, therefore, hypothesized that there was a link between HIF-1α, TERT, and autophagy in promoting PTC progression. Methods: Immunohistochemistry staining was conducted to evaluate the expressions of HIF-1α, TERT, and autophagy marker, LC3-II, in matched PTC tumors and corresponding nontumor tissues. Two PTC cell lines (TPC-1 and BCPAP) were used in subsequent cytological function studies. Cell viability, proliferation, apoptosis, migration, and invasion were assessed during hypoxia, genetic enhancement and inhibition of TERT, and chemical and genetic inhibition of autophagy. The protein expression levels of the corresponding biomarkers were determined by Western blotting, and autophagy flow was detected. We characterized the molecular mechanism of PTC cell progression. Results: The protein expression levels of HIF-1α, TERT, and LC3-II were upregulated in PTCs and were significantly correlated with high tumor-node-metastasis stage. Further, an in vitro study indicated that HIF-1α induced by hypoxia functioned as a transcriptional activator by binding with sequences potentially located in the TERT promoter and was positively correlated with the malignant behavior of PTC cell lines. Overexpression of TERT inhibited the kinase activity of mammalian target of rapamycin (mTOR), resulting in the activation of autophagy. Functionally, TERT-induced autophagy provided a survival advantage to PTC cells during hypoxia stress. Conclusions: We identified a novel molecular mechanism involving the HIF-1α/TERT axis, which promoted PTC progression by inducing autophagy through mTOR during hypoxia stress. These findings may provide a basis for the new treatment of aggressive PTCs.

Pathological validation and prognostic potential of quantitative MRI in the characterization of pancreas cancer: preliminary experience

Patient stratification based on biological variation in pancreatic ductal adenocarcinoma (PDAC) subtypes could help to improve clinical outcome. However, noninvasive assessment of the entire tumor microenvironment remains challenging. In this study, we investigate the biological basis of dynamic contrast-enhanced (DCE), intravoxel incoherent motion (IVIM), and R2*-derived magnetic resonance imaging (MRI) parameters for the noninvasive characterization of the PDAC tumor microenvironment and evaluate their prognostic potential in PDAC patients. Patients diagnosed with treatment-naïve resectable PDAC underwent MRI. After resection, a whole-mount tumor slice was analyzed for collagen fraction, vessel density, and hypoxia and matched to the MRI parameter maps. MRI parameters were correlated to immunohistochemistry-derived tissue characteristics and evaluated for prognostic potential. Thirty patients were included of whom 21 underwent resection with whole-mount histology available in 15 patients. DCE Ktrans and ve , ADC, and IVIM D correlated with collagen fraction. DCE kep and IVIM f correlated with vessel density and R2* with tissue hypoxia. Based on MRI, two main PDAC phenotypes could be distinguished; a stroma-high phenotype demonstrating high vessel density and high collagen fraction and a stroma-low phenotype demonstrating low vessel density and low collagen fraction. Patients with the stroma-high phenotype (high kep and high IVIM D, n = 8) showed longer overall survival (not reached vs. 14 months, P = 0.001, HR = 9.1, P = 0.004) and disease-free survival (not reached vs. 2 months, P < 0.001, HR 9.3, P = 0.003) compared to the other patients (n = 22). Median follow-up was 41 (95% CI: 36-46) months. MRI was able to accurately characterize tumor collagen fraction, vessel density, and hypoxia in PDAC. Based on imaging parameters, a subgroup of patients with significantly better prognosis could be identified. These first results indicate that stratification-based MRI-derived biomarkers could help to tailor treatment and improve clinical outcome and warrant further research.

Clinical and Pre-Clinical Evidence of Carbonic Anhydrase IX in Pancreatic Cancer and Its High Expression in Pre-Cancerous Lesions

Hypoxia is a common phenomenon that occurs in most solid tumors. Regardless of tumor origin, the evolution of a hypoxia-adapted phenotype is critical for invasive cancer development. Pancreatic ductal adenocarcinoma is also characterized by hypoxia, desmoplasia, and the presence of necrosis, predicting poor outcome. Carbonic anhydrase IX (CAIX) is one of the most strict hypoxia regulated genes which plays a key role in the adaptation of cancer cells to hypoxia and acidosis. Here, we summarize clinical data showing that CAIX expression is associated with tumor necrosis, vascularization, expression of Frizzled-1, mucins, or proteins involved in glycolysis, and inevitably, poor prognosis of pancreatic cancer patients. We also describe the transcriptional regulation of CAIX in relation to signaling pathways activated in pancreatic cancers. A large part deals with the preclinical evidence supporting the relevance of CAIX in processes leading to the aggressive behavior of pancreatic tumors. Furthermore, we focus on CAIX occurrence in pre-cancerous lesions, and for the first time, we describe CAIX expression within intraductal papillary mucinous neoplasia. Our review concludes with a detailed account of clinical trials implicating that treatment consisting of conventionally used therapies combined with CAIX targeting could result in an improved anti-cancer response in pancreatic cancer patients.

Weak HIF-1alpha expression indicates poor prognosis in resectable pancreatic ductal adenocarcinoma

BACKGROUND

HIF-1alpha and CAIX proteins are commonly expressed under hypoxic conditions, but other regulatory factors have been described as well. Pancreatic ductal adenocarcinoma (PDAC) is characterized by hypoxia and strong stromal reaction and has a dismal prognosis with the currently available treatment modalities.

METHODS

We investigated the expression and prognostic role of HIF-1alpha and CAIX in PDAC series from Northern Finland (n = 69) using immunohistochemistry.

RESULTS

In our PDAC cases, 95 and 85% showed HIF-1alpha and CAIX expression, respectively. Low HIF-1alpha expression correlated with poor prognosis, and multivariate analysis identified weak HIF-1alpha intensity as an independent prognostic factor for PDAC-specific deaths (HR 2.176, 95% CI 1.216-3.893; p = 0.009). There was no correlation between HIF-1alpha and CAIX expression levels, and the latter did not relate with survival.

CONCLUSIONS

Our findings are in contrast with previous research by finding an association between low HIF-1alpha and poor prognosis. The biological mechanisms remain speculative, but such an unexpected relation with prognosis and absence of correlation between HIF-1alpha and CAIX suggests that the prognostic association of HIF-1alpha may not directly be linked with hypoxia. Accordingly, the role of HIF-1alpha might be more complex than previously thought and the use of this marker as a hypoxia-related prognostic factor should be addressed with caution.

Smart Magnetic Nanoaptamer: Construction, Subcellular Distribution, and Silencing HIF for Cancer Gene Therapy

Attenuating the expression of HIF-1α (hypoxic inducible factor) by siRNA has an effect on the proliferation of hypoxia cancers. Mitochondria targeting siRNA may silence the level of HIF-1α for cancer gene therapy. A GAG-rich DNA was conjugated to GC-rich DNA for the synthesis of functional magnetic nanoaptamer (DNA-Fe₃O₄) to keep the innate character of the targeting aptamer. The DNA-Fe₃O₄ can load the hydrophobic dye (BODIPY-OCH₃) by the GC-rich sequences, resulting in fluorescent nanoaptamer (BFe@DNA). Self-assembly of BFe@DNA with target aptamer resulted in the formation of BFe@DNA_H. Subcellular fluorescence imaging results confirm that BFe@DNA_H can accumulate in MCF-7 cells and selectively target mitochondrion. In particular, BFe@DNA_H can transport siRNA to breast cancer cells or tissues for the attenuation of HIF-1α and ATP and the inhibition on growth of cancer cells in vivo. Therefore, BFe@DNA_H is a smart nanoaptamer platform for the development of subcellular imaging agents and gene therapy.

Expression of Hypoxia-Associated Protein HIF-1α in Follicular Thyroid Cancer is Associated with Distant Metastasis

Follicular thyroid carcinomas (FTCs) are the second most common malignant neoplasia of the thyroid and in general its prognosis is quite favorable. However, the occurrence of metastases or non-responsiveness to radioiodine therapy worsens the prognosis considerably. We evaluated immunohistochemically the expression of hypoxia-associated proteins by hypoxia-induced factor 1α (HIF-1α), the stroma-remodeling marker Tenascin C, as well as markers for the epithelial-mesenchymal transition (EMT), namely E-cadherin and slug in a series of 59 sporadic FTCs. In addition, various clinicopathologic parameters were assessed like TNM-staging, age, tumor size as well as tumor characteristics like desmoplasia, necrosis, and calcification. Overexpression of HIF-1α was seen in 29 of 59 tumors (49.2%) including 21 (35.6%) FTC with strong expression of tumor cell groups. HIF-1α correlated significantly with metastasis (p < 0.001; Mann-Whitney U test), degree of desmoplasia (p = 0.042, Kruskal-Wallis test), tenascin C expression (p = 0.042, Kruskal-Wallis test), calcification (p < 0.025, Kruskal-Wallis test), necrosis (p = 0.002), age (p = 0.011, Kruskal-Wallis test) and tumor stage UICC (p = 0.022, Kruskal-Wallis test). Furthermore, metastasis was associated with the degree of desmoplasia (p = 0.014; Fisher's exact test), calcification (p = 0.008, Fisher's exact test), necrosis (p = 0.042, Fisher's exact test), tumor size (p = 0.015, Mann-Whitney U test), and age (p = 0.001, Mann-Whitney U test). In a Cox proportional hazards model, only metastasis remained as an independent risk factor for overall survival (hazard rate: 10.2 [95% CI, 02.19 to 47.26]; p = 0.003). Our data suggest that HIF-1α plays a critical role in the remodeling of the extracellular matrix as well as metastasizing process of follicular thyroid carcinoma and targeting hypoxia-associated and -regulated proteins may be considered as potential targets for personalized medicine.

Designing a bio-inspired biomimetic in vitro system for the optimization of ex vivo studies of pancreatic cancer

Pancreatic cancer is one of the most aggressive and lethal human malignancies. Drug therapies and radiotherapy are used for treatment as adjuvants to surgery, but outcomes remain disappointing. Advances in tissue engineering suggest that 3D cultures can reflect the in vivo tumor microenvironment and can guarantee a physiological distribution of oxygen, nutrients, and drugs, making them promising low-cost tools for therapy development. Here, we review crucial structural and environmental elements that should be considered for an accurate design of an ex vivo platform for studies of pancreatic cancer. Furthermore, we propose environmental stress response biomarkers as platform readouts for the efficient control and further prediction of the pancreatic cancer response to the environmental and treatment input.

Dual oxidase 2 and pancreatic adenocarcinoma: IFN-γ-mediated dual oxidase 2 overexpression results in H2O2-induced, ERK-associated up-regulation of HIF-1α and VEGF-A

Several NADPH oxidase family members, including dual oxidase 2 [DUOX2], are expressed in human tumors, particularly gastrointestinal cancers associated with long-standing chronic inflammation. We found previously that exposure of pancreatic ductal adenocarcinoma cells to the pro-inflammatory cytokine IFN-γ increased DUOX2 expression (but not other NADPH oxidases) leading to long-lived H2O2 production. To elucidate the pathophysiology of DUOX2-mediated H2O2 formation in the pancreas further, we demonstrate here that IFN-γ-treated BxPC-3 and CFPAC-1 pancreatic cancer cells (known to increase DUOX2 expression) produce significant levels of intracellular oxidants and extracellular H2O2 which correlate with concomitant up-regulation of VEGF-A and HIF-1α transcription. These changes are not observed in the PANC-1 line that does not increase DUOX2 expression following IFN-γ treatment. DUOX2 knockdown with short interfering RNA significantly decreased IFN-γ-induced VEGF-A or HIF-1α up-regulation, as did treatment of pancreatic cancer cells with the NADPH oxidase inhibitor diphenylene iodonium, the multifunctional reduced thiol N-acetylcysteine, and the polyethylene glycol-modified form of the hydrogen peroxide detoxifying enzyme catalase. Increased DUOX2-related VEGF-A expression appears to result from reactive oxygen-mediated activation of ERK signaling that is responsible for AP-1-related transcriptional effects on the VEGF-A promoter. To clarify the relevance of these observations in vivo, we demonstrate that many human pre-malignant pancreatic intraepithelial neoplasms and frank pancreatic cancers express substantial levels of DUOX protein compared to histologically normal pancreatic tissues, and that expression of both DUOX2 and VEGF-A mRNAs is significantly increased in surgically-resected pancreatic cancers compared to the adjacent normal pancreas.

Hypoxia-induced endoplasmic reticulum stress characterizes a necrotic phenotype of pancreatic cancer

Stromal fibrosis and tissue necrosis are major histological sequelae of hypoxia. The hypoxia-to-fibrosis sequence is well-documented in pancreatic ductal adenocarcinoma (PDAC). However, hypoxic and necrotic PDAC phenotypes are insufficiently characterized. Recently, reduction of tuberous sclerosis expression in mice together with oncogenic Kras demonstrated a rapidly metastasizing phenotype with histologically eccentric necrosis, transitional hypoxia and devascularisation. We established cell lines from these tumors and transplanted them orthotopically into wild-type mice to test their abilities to recapitulate the histological features of the primary lesions. Notably, the necrotic phenotype was reproduced by only a subset of cell lines while others gave rise to dedifferentiated tumors with significantly reduced necrosis. In vitro analysis of the necrotic tumor-inducing cell lines revealed that these cells released a significant amount of vascular endothelial growth factor A (VEGFA). However, its release was not further increased under hypoxic conditions. Defective hypoxia-induced VEGFA secretion was not due to impaired VEGFA transcription or hypoxia-inducible factor 1-alpha activation, but rather a result of hypoxia-induced endoplasmic reticulum (ER) stress. We thus identified hypoxia-induced ER stress as an important pathway in PDACs with tissue necrosis and rapid metastasis.

SNAIL gene inhibited by hypoxia-inducible factor 1α (HIF-1α) in epithelial ovarian cancer

The aim of this study was to investigate the relationship between HIF-1α and SNAIL gene expression in the epithelial ovarian cancer (EOC) cell line. EOC cells were treated with hypoxia, hypoxia combined with rapamycin, and control. The expression of HIF-1α and E-cad were assessed by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. The gene expression of SNAIL was studied by RT-PCR and real-time PCR. RNA interference technology was used to determine the relationship between HIF-1α and SNAIL. The present study indicated that the HIF-1α protein was expressed and increased in EOC cell line. SNAIL mRNA was found to increase and E-cad expression decreased with the time of hypoxia prolonged. Hypoxia increased invasion abilities of EOC cell line, but compared with cells exposed to hypoxia, the change of invasive ability of cells with rapamycin had no effect. The expression of HIF-1α protein and SNAIL mRNA could be inhibited gradually by rapamycin. siRNA of HIF-1α could suppress the expression of SNAIL while siRNA of SNAIL had no influence on HIF-1α protein expression. HIF-1α may be the upstream of the SNAIL gene in EOC. Our data suggested that HIF-1α might be an upregulator of the SNAIL gene and HIF-1α-SNAIL-E-cad pathway may play an important role in EOC invasion and metastasis.

PKM2 promotes tumor angiogenesis by regulating HIF-1α through NF-κB activation

BACKGROUND

Initially identified as a molecule that regulates the final step of glycolysis, the M2 isoform of pyruvate kinase (PKM2) was recently reported to have a central role in the metabolic reprogramming of cancer cells as well as participating in cell cycle progression and gene transcription. Despite intensive efforts, the intricate molecular mechanisms through which PKM2 regulates tumor progression remain elusive.

METHODS

The proliferation and apoptosis of various pancreatic cancer cells using lentiviral-mediated PKM2 abrogation were assessed in vitro via Western blot and flow cytometric assay while the in vivo experiments involved tumor xenograft on chicken chorionallantoic membranes and immunohistochemistry on human tissue specimens. In order to decipher the molecular mechanism of HIF-1α and p65/RelA regulation by PKM2 in cancer cells cultivated in hypoxic atmosphere or normoxia we involved various biochemical assays such as Western blotting, immunoprecipitation, reporter gene assay and ELISA.

RESULTS

Strong expression of PKM2 was observed in 68 % of human pancreatic adenocarcinoma specimens and almost all analyzed pancreatic cancer cell lines. Abrogation of PKM2 resulted in impaired proliferation and augmented apoptosis in vitro as well as impaired tumor growth and decreased blood vessel formation in vivo. Furthermore, deletion of PKM2 negatively impacted hypoxia-induced HIF-1α accumulation and promoter activity ultimately resulting in impaired secretion of VEGF.

CONCLUSIONS

Our study suggests that in hypoxic pancreatic tumors PKM2 interferes both with NF-κB/p65 and HIF-1α activation that ultimately triggers VEGF-A secretion and subsequent blood vessel formation.

Expression and significance of HIF-1α and HIF-2α in pancreatic cancer

The expression levels of hypoxia-inducible factor 1alpha (HIF-1α) and HIF-2α in pancreatic cancer (PC) and their association with clinicopathologic characteristics were investigated in order to elucidate their roles in the development of PC. HIF-1α 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-1α 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 tissues (P<0.05). HIF-1α staining was weakly positive in most cancer tissues and strongly positive in adjacent pancreas tissues (P<0.05). Clinicopathologic analysis revealed that relatively strong HIF-1α expression 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 survival 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-1α(high)/HIF-2α(low) group showed a shorter survival time than the HIF-1α(low)/HIF-2α(high) group. In conclusion, 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.

Targeting cancer cell metabolism in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second leading cause of cancer death by 2030. Current therapeutic options are limited, warranting an urgent need to explore innovative treatment strategies. Due to specific microenvironment constraints including an extensive desmoplastic stroma reaction, PDAC faces major metabolic challenges, principally hypoxia and nutrient deprivation. Their connection with oncogenic alterations such as KRAS mutations has brought metabolic reprogramming to the forefront of PDAC therapeutic research. The Warburg effect, glutamine addiction, and autophagy stand as the most important adaptive metabolic mechanisms of cancer cells themselves, however metabolic reprogramming is also an important feature of the tumor microenvironment, having a major impact on epigenetic reprogramming and tumor cell interactions with its complex stroma. We present a comprehensive overview of the main metabolic adaptations contributing to PDAC development and progression. A review of current and future therapies targeting this range of metabolic pathways is provided.

High nuclear hypoxia-inducible factor 1 alpha expression is a predictor of distant recurrence in patients with resected pancreatic adenocarcinoma

PURPOSE

To evaluate nuclear hypoxia-inducible factor 1α (HIF-1α) expression as a prognostic factor for distant recurrence (DR) and local recurrence (LR) after pancreatic adenocarcinoma resection.

METHODS AND MATERIALS

Tissue specimens were collected from 98 patients with pancreatic adenocarcinoma who underwent resection without neoadjuvant therapy between January 2000 and December 2011. Local recurrence was defined as radiographic or pathologic evidence of progressive disease in the pancreas, pancreatic bed, or associated nodal regions. Distant recurrence was defined as radiographically or pathologically confirmed recurrent disease in other sites. Immunohistochemical staining was performed and scored by an independent pathologist blinded to patient outcomes. High HIF-1α overall expression score was defined as high percentage and intensity staining and thus score >1.33. Univariate analysis was performed for HIF-1α score with LR alone and with DR. Multivariate logistic regression was used to determine predictors of LR and DR.

RESULTS

Median follow-up time for all patients was 16.3 months. Eight patients (8%) demonstrated isolated LR, 26 patients (26.5%) had isolated DR, and 13 patients had both LR and DR. Fifty-three patients (54%) had high HIF-1α expression, and 45 patients (46%) had low HIF-1α expression. High HIF-1α expression was significantly associated with DR (P=.03), and low HIF-1α expression was significantly associated with isolated LR (P=.03). On multivariate logistic regression analysis, high HIF-1α was the only significant predictor of DR (odds ratio 2.46 [95% confidence interval 1.06-5.72]; P=.03). In patients with a known recurrence, an HIF-1α score ≥2.5 demonstrated a specificity of 100% for DR.

CONCLUSIONS

High HIF-1α expression is a significant predictor of distant failure versus isolated local failure in patients undergoing resection of pancreatic adenocarcinoma. Expression of HIF-1α may have utility in determining candidates for adjuvant local radiation therapy and systemic chemotherapy.

Combining clinicopathological predictors and molecular biomarkers in the oncogenic K-RAS/Ki67/HIF-1α pathway to predict survival in resectable pancreatic cancer

BACKGROUND

The dismal prognosis of patients diagnosed with pancreatic cancer points to our limited arsenal of effective anticancer therapies. Oncogenic K-RAS hyperactivation is virtually universal in pancreatic cancer, that confers drug resistance, drives aggressive tumorigenesis and rapid metastasis. Pancreatic tumours are often marked by hypovascularity, increased hypoxia and ineffective drug delivery. Thus, biomarker discovery and developing innovative means of countervailing oncogenic K-RAS activation are urgently needed.

METHODS

Tumour specimens from 147 pancreatic cancer patients were analysed by immunohistochemical (IHC) staining and tissue microarray (TMA). Statistical correlations between selected biomarkers and clinicopathological predictors were examined to predict survival.

RESULTS

We find that heightened hypoxia response predicts poor clinical outcome in resectable pancreatic cancer. SIAH is a tumour-specific biomarker. The combination of five biomarkers (EGFR, phospho-ERK, SIAH, Ki67 and HIF-1α) and four clinicopathological predictors (tumour size, pathological grade, margin and lymph node status) predict patient survival post surgery in pancreatic cancer.

CONCLUSIONS

Combining five biomarkers in the K-RAS/Ki67/HIF-1α pathways with four clinicopathological predictors may assist to better predict survival in resectable pancreatic cancer.

Correlation between tumor size and blood volume in lung tumors: a prospective study on dual-energy gemstone spectral CT imaging

The purpose of this study was to investigate the relationship between tumor size and blood volume for patients with lung tumors, using dual-energy computed tomography (DECT) and a gemstone spectral imaging (GSI) viewer. During the period from March 2011 to March 2013, 50 patients with 57 medically inoperable lung tumors underwent DECT before stereotactic body radiotherapy (SBRT) of 50-60 Gy in 5-6 fractions. DECT was taken for pretreatment evaluation. The region-of-interest for a given spatial placement of the tumors was set, and averages for CT value, water density and iodine density were compared with tumor size. The average values for iodine density in tumors of ≤ 2 cm, 2-3 cm, and >3 cm maximum diameter were 24.7, 19.6 and 16.0 (100 µg/cm(3)), respectively. The average value of the iodine density was significantly lower in larger tumors. No significant correlation was detected between tumor size and average CT value or between tumor size and average water density. Both the average water density and the average CT value were affected by the amount of air in the tumor, but the average iodine density was not affected by air in the tumor. The average water density and the average CT value were significantly correlated, but the average iodine density and the average CT value showed no significant correlation. The blood volume of tumors can be indicated by the average iodine density more accurately than it can by the average CT value. The average iodine density as assessed by DECT might be a non-invasive and quantitative assessment of the radio-resistance ascribable to the hypoxic cell population in a tumor.

The impact of hypoxia in pancreatic cancer invasion and metastasis

Intratumoral hypoxia is a common feature of solid tumors. Recent advances in cancer biology indicate that hypoxia is not only a consequence of unrestrained tumor growth, but also plays an active role in promoting tumor progression, malignancy, and resistance to therapy. Hypoxia signaling is mediated by the hypoxia-inducible factors (HIFs), which are not only stabilized under hypoxia, but also by activated oncogenes or inactivated tumor suppressors under normoxia. Hypoxia is a prominent feature of the tumor microenvironment of pancreatic tumors, also characterized by the presence of a fibrotic reaction that promotes, and is also modulated by, hypoxia. As the mechanisms by which hypoxia signaling impacts invasion and metastasis in pancreatic cancer are being elucidated, hypoxia is emerging as a key determinant of pancreatic cancer malignancy as well as an important target for therapy. Herein we present an overview of recent advances in the understanding of the impact that hypoxia has in pancreatic cancer invasion and metastasis.

Molecular mechanisms underlying chronic inflammation-associated cancers

Although it is now accepted that chronic inflammation plays an essential role in tumorigenesis, the underlying molecular mechanisms linking inflammation and cancer remain to be fully explored. Inflammatory mediators present in the tumor microenvironment, including cytokines and growth factors, as well as reactive oxygen species (ROS) and reactive nitrogen species (RNS), have been implicated in the etiology of inflammation-associated cancers. Epithelial NADPH oxidase (Nox) family proteins, which generate ROS regulated by cytokines, are upregulated during chronic inflammation and cancer. ROS serve as effector molecules participating in host defense or as chemo-attractants recruiting leukocytes to wounds, thereby influencing the inflammatory reaction in damaged tissues. ROS can alter chromosomal DNA, leading to genomic instability, and may serve as signaling molecules that affect tumor cell proliferation, survival, metabolism, angiogenesis, and metastasis. Targeting Noxs and their downstream signaling components may be a promising approach to pre-empting inflammation-related malignancies.

Clinicopathological significance of hypoxia-inducible factor-1 alpha polymorphisms in cancers: evidence from a meta-analysis

The associations between hypoxia-inducible factor-1 alpha (HIF-1α) and clinicopathological characteristics of cancers have been evaluated in various studies, with the conflicting results. Therefore, we conducted a meta-analysis by combining available data to derive a more precise estimation of the association. PubMed, Embase, and China National Knowledge Infrastructure (CNKI) were searched until February 2013 to identify eligible studies. A total of 25 studies were included, with all studies investigating the role of HIF-1α C1772T polymorphism in clinicopathological parameters in cancers while 17 of them investigating HIF-1α G1790A polymorphism only. Results suggested that HIF-1α C1772T polymorphism was associated with histological grade of cancer (T/T + C/T vs. C/C, grade 3 vs. grade 2: OR = 1.51, 95% CI = 1.08-2.13; grade 2 vs. grade 1: OR = 0.67, 95% CI = 0.46-0.97) and increased risk of lymph node metastasis (T/T + C/T vs. C/C: OR = 1.38, 95% CI = 1.13-1.68). HIF-1α G1790A polymorphism was found to be associated with increased risk of larger tumor size (G/G + G/A vs. A/A: OR = 1.64, 95% CI = 1.04-2.58) and borderline significant risk of lymph node metastasis (G/G + G/A vs. A/A: OR = 1.33, 95% CI = 1.00-1.78). Therefore, HIF-1α polymorphisms could be a potential prognostic factor for cancer. Further studies with larger data set and well-designed models are required to validate our findings.

Experimental studies on treatment of pancreatic cancer with double-regulated duplicative adenovirus AdTPHre-hEndo carrying human endostatin gene

BACKGROUND

Gene-virus targeted therapy is a promising new method of treating pancreatic cancer. To increase the efficacy and decrease the side-effect, we constructed a conditionally replicative adenovirus (CRAd) expressing human endostatin, with a human Telomoerase Reverse Transcriptase (hTERT) promoter for the regulation of the early stage of adenovirus expression of gene E1a and a Hypoxia Response Element (HRE) promoter to regulate the gene E1b.

METHODS

A gene recombination technique was adopted to construct and generate the adenovirus AdTPHre-hEndo. Pancreatic cancer cells were studied both in vitro and in vivo. Western blotting was adopted to observe the expressions of protein E1A and E1B; duplication assay was applied to observe the selective duplication capability of recombinant cells. MTT assay was applied to measure the lethal effects of virus on pancreatic cancer cells, and ELISA was adopted to detect the human endostatin gene expression. A pancreatic cancer transplantation tumor model of nude mice was constructed to observe the antitumor effects of the virus.

RESULTS

Double-regulated duplicative adenovirus AdTPHre-hEndo genes were successfully constructed. Duplication and lethal assays proved that AdTPHre-hEndo could replicate specifically in pancreatic cancer cells and kill them. The endostatin expression in a cultured supernatant from tumor cells was significantly higher than that obtained from non-duplicative adenovirus vectors carrying that gene. The animal experiment demonstrated that AdTPHre-hEndo has a high capability to limit pancreatic cancer growth.

CONCLUSIONS

AdTPHre-hEndo has a special ability to duplicate and kill pancreatic cancer cells in in vitro and in vivo experiments, thus providing a new gene-virus-based treatment system for pancreatic cancer.

The pancreas cancer microenvironment

Pancreatic ductal adenocarcinoma (PDA) is a common and lethal malignancy resulting in more than 250,000 deaths per year worldwide. Despite extensive efforts, cytotoxic and targeted therapies have provided only limited efficacy for patients with PDA to date. One contributing factor to the failure of systemic therapies may be the abundant tumor stromal content that is the characteristic of PDA. The PDA stroma, aptly termed the tumor microenvironment, occupies the majority of the tumor mass, and consists of a dynamic assortment of extracellular matrix components and nonneoplastic cells including fibroblastic, vascular, and immune cells. Recent work has revealed that the PDA stroma supports tumor growth and promotes metastasis and simultaneously serves as a physical barrier to drug delivery. Accordingly, methods that alter stromal composition or function, for instance interference with the vasculature via Notch/Hedgehog pathway inhibition or relief of vascular compression by hyaluronidase, are under active investigation. Here, we will review our current understanding of the PDA tumor microenvironment, and highlight opportunities for further exploration that may benefit patients.

The novel hypoxic cytotoxin, TX-2098 has antitumor effect in pancreatic cancer; possible mechanism through inhibiting VEGF and hypoxia inducible factor-1α targeted gene expression

Tumor hypoxia has been considered to be a potential therapeutic target, because hypoxia is a common feature of solid tumors and is associated with their malignant phenotype. In the present study, we investigated the antitumor effect of a novel hypoxic cytotoxin, 3-[2-hydroxyethyl(methyl)amino]-2-quinoxalinecarbonitrile 1,4-dioxide (TX-2098) in inhibiting the expression of hypoxia inducible factor-1α (HIF-1α), and consequently vascular endothelial cell growth factor (VEGF) expression in pancreatic cancer. The antitumor effects of TX-2098 under hypoxia were tested against various human pancreatic cancer cell lines using WST-8 assay. VEGF protein induced pancreatic cancer was determined on cell-free supernatant by ELISA. Moreover, nude mice bearing subcutaneously (s.c.) or orthotopically implanted human SUIT-2 were treated with TX-2098. Tumor volume, survival and expression of HIF-1 and associated molecules were evaluated in treatment versus control groups. In vitro, TX-2098 inhibited the proliferation of various pancreatic cancer cell lines. In s.c model, tumors from nude mice injected with pancreatic cancer cells and treated with TX-2098 showed significant reductions in volume (P<0.01 versus control). Quantitative real-time reverse transcription-PCR analysis revealed that TX-2098 significantly inhibited mRNA expression of the HIF-1 associated molecules, VEGF, glucose transporter 1 and Aldolase A (P<0.01 versus control). These treatments also prolong the survival in orthotopic models. These results suggest that the effect of TX-2098 in pancreatic cancer might be correlated with the expression of VEGF and HIF-1 targeted molecules.

Tumour necrosis is a postoperative prognostic marker for pancreatic cancer patients with a high interobserver reproducibility in histological evaluation

Background:

Tumour necrosis reflects the presence of hypoxia, which can be indicative of an aggressive tumour phenotype. The aim of this study was to investigate whether histological necrosis is a useful predictor of outcome in patients with pancreatic ductal carcinoma (PDC).

Methods:

We reviewed histopathological findings in 348 cases of PDC in comparison with clinicopathological information. We counted small necrotic foci (micronecrosis) as necrosis, in addition to massive necrosis that had been only defined as necrosis in previous studies. The reproducibility of identifying histological parameters was tested by asking five independent observers to blindly review 51 examples of PDC.

Results:

Both micronecrosis and massive necrosis corresponded to hypoxic foci expressing carbonic anhydrase IX detected by immunohistochemistry. Multivariate survival analysis showed that histological necrosis was an independent predictor of poor outcome in terms of both disease-free survival (DFS) and disease-specific survival (DSS) of PDC patients. In addition, metastatic status, and lymphatic, venous, and intrapancreatic neural invasion were independent prognostic factors for shorter DFS and metastatic status, margin status, lymphatic invasion, and intrapancreatic neural invasion were independent prognostic factors for DSS. The interobserver reproducibility of necrosis identification among the five independent observers was ‘almost perfect’ (κ-value of 0.87).

Conclusion:

Histological necrosis is a simple, accurate, and reproducible predictor of postoperative outcome in PDC patients.

Insulin promotes proliferative vitality and invasive capability of pancreatic cancer cells via hypoxia-inducible factor 1alpha pathway

This study examined whether insulin-stimulated hypoxia-inducible factor 1alpha (HIF-1alpha) 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-1alpha) 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 micromol/L). HIF-1alpha 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-1alpha protein expression, and YC-1 could dose-dependently block this effect. However, neither insulin nor YC-1 altered HIF-1alpha 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-1alpha protein.

Suppression of growth of pancreatic cancer cell and expression of vascular endothelial growth factor by gene silencing with RNA interference

OBJECTIVE

To explore the anti-angiogenesis and tumor cell growth suppressive effects resulted from gene silencing by RNAi in BxPC-3 human pancreatic cancer cells.

METHODS

The designation and transfection of vascular endothelial growth factor (VEGF)-siRNA lentivirus was carried out in vitro. Real-time PCR and western blot were conducted to measure the expression levels of VEGF mRNA and protein. Flow cytometry was employed to evaluate cell apoptosis and cell death. A lactate dehydrogenase (LDH) assay was used to assess the cytotoxicity of VEGF-siRNA. A 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to picture the cellular growth. For the in vivo study, BxPC-3 cells were injected subcutaneously into nude mice to form xenografts. The mice were divided into three groups according to the intervention used. The control group, the negative control group and the knockdown group of mice were injected with saline, an empty lentivirus vehicle and lentivirus carrying VEGF-siRNA, respectively. None of the mice died during the study. When these mice were killed, the xenografts were collected and the tumor sizes of the different groups were compared. Finally, immunohistochemistry was used to assess the VEGF expression level and microvascular density.

RESULTS

After the transfection of VEGF-siRNA lentivirus, the cellular expression of VEGF mRNA decreased to 50% of the control and the VEGF protein in the BxPC-3 cells decreased to 30% of the control. Apoptosis and cell death increased after transfection of the VEGF-siRNA lentivirus. The LDH assay showed high cytotoxicity induced by VEGF-siRNA lentivirus transfection. The MTT assay showed slower cellular growth in the knockdown cells. Tumor growth suppression was observed in nude mice that had received the VEGF-siRNA lentivirus transfection, and the tumor sizes of the xenografts in this group were clearly smaller than those in other two groups. VEGF expression and microvascular density were significantly decreased.

CONCLUSION

Vascular endothelial growth factor gene silencing via VEGF-siRNA can effectively inhibit the production of VEGF and exert an anti-angiogenesis and tumor cell growth suppressive effect both in vitro and in vivo.

Hypoxia stimulates pancreatic stellate cells to induce fibrosis and angiogenesis in pancreatic cancer

Pancreatic cancer is characterized by excessive desmoplastic reaction and by a hypoxic microenvironment within the solid tumor mass. Chronic pancreatitis is also characterized by fibrosis and hypoxia. Fibroblasts in the area of fibrosis in these pathological settings are now recognized as activated pancreatic stellate cells (PSCs). Recent studies have suggested that a hypoxic environment concomitantly exists not only in pancreatic cancer cells but also in surrounding PSCs. This study aimed to clarify whether hypoxia affected the cell functions in PSCs. Human PSCs were isolated and cultured under normoxia (21% O(2)) or hypoxia (1% O(2)). We examined the effects of hypoxia and conditioned media of hypoxia-treated PSCs on cell functions in PSCs and in human umbilical vein endothelial cells. Hypoxia induced migration, type I collagen expression, and vascular endothelial growth factor (VEGF) production in PSCs. Conditioned media of hypoxia-treated PSCs induced migration of PSCs, which was inhibited by anti-VEGF antibody but not by antibody against hepatocyte growth factor. Conditioned media of hypoxia-treated PSCs induced endothelial cell proliferation, migration, and angiogenesis in vitro and in vivo. PSCs expressed several angiogenesis-regulating molecules including VEGF receptors, angiopoietin-1, and Tie-2. In conclusion, hypoxia induced profibrogenic and proangiogenic responses in PSCs. In addition to their established profibrogenic roles, PSCs might play proangiogenic roles during the development of pancreatic fibrosis, where they are subjected to hypoxia.

Inhibition of protein synthesis by imexon reduces HIF-1alpha expression in normoxic and hypoxic pancreatic cancer cells

Hypoxia-inducing factor-1 alpha (HIF-1alpha), is a major survival factor for tumor cells growing in a low oxygen environment. The anti-cancer agent imexon binds thiols and causes accumulation of reactive oxygen species (ROS) in pancreatic cancer cells. Unlike many cytotoxic agents, imexon is equi-cytotoxic in human MiaPaCa-2 and Panc-1 cells grown in normoxic (21% O(2)) and hypoxic (1% O(2)) conditions. Western blot analyses of imexon-treated cells demonstrated that imexon reduces HIF-1alpha protein levels in both normoxic and hypoxic conditions in a time- and concentration-dependant fashion. Gemcitabine did not similarly affect HIF-1alpha levels. Imexon did not reduce transcription of new HIF-1alpha mRNA, but did reduce the synthesis of new proteins, including HIF-1alpha, measured by (35)S methionine/cysteine (Met/Cys) incorporation. Concurrently, the half-life of existing HIF-1alpha protein was increased by imexon, in association with a marked inhibition of chymotryptic activity in the 20S proteasome. The inhibition of HIF-1alpha translation was not specific, rather it was part of a general decrease in protein translation caused by imexon. This inhibitory effect on translation did not involve phosphorylation of eukaryotic initiation factor-2alpha (eIF-2alpha) and was not closely correlated to cell growth inhibition by imexon, suggesting that mechanisms other than protein synthesis inhibition contribute to the drug's cytotoxic effects. In summary, imexon blocks the translation of new proteins, including HIF-1alpha, and this effect overcomes an increase in the stability of preformed HIF-1alpha due to proteasome inhibition by imexon. Because net HIF-1alpha levels are reduced by imexon, combination studies with other drugs affected by HIF-1alpha survival signaling are warranted.

MicroRNA expression and identification of putative miRNA targets in ovarian cancer

Background

MicroRNAs (miRNAs) represent a class of small non-coding RNAs that control gene expression by targeting mRNAs and triggering either translation repression or RNA degradation. Emerging evidence suggests the potential involvement of altered regulation of miRNA in the pathogenesis of cancers, and these genes are thought to function as both tumor suppressors and oncogenes.

Methodology/Principal Findings

Using microRNA microarrays, we identify several miRNAs aberrantly expressed in human ovarian cancer tissues and cell lines. miR-221 stands out as a highly elevated miRNA in ovarian cancer, while miR-21 and several members of the let-7 family are found downregulated. Public databases were used to reveal potential targets for the highly differentially expressed miRNAs. In order to experimentally identify transcripts whose stability may be affected by the differentially expressed miRNAs, we transfected precursor miRNAs into human cancer cell lines and used oligonucleotide microarrays to examine changes in the mRNA levels. Interestingly, there was little overlap between the predicted and the experimental targets or pathways, or between experimental targets/pathways obtained using different cell lines, highlighting the complexity of miRNA target selection.

Conclusion/Significance

Our results identify several differentially expressed miRNAs in ovarian cancer and identify potential target transcripts that may be regulated by these miRNAs. These miRNAs and their targets may have important roles in the initiation and development of ovarian cancer.

Pancreatic cancer: from molecular signature to target therapy

Pancreatic adenocarcinoma is a leading cause of cancer death in western countries. The treatment of advanced disease with gemcitabine has only a modest activity on survival with a favourable impact on quality of life. However, recent data support the evidence that the combination of gemcitabine with erlotinib, capecitabine or platinum compounds could be more active than gemcitabine alone in advanced pancreatic cancer. New therapeutic strategies, particularly using molecular target agents, are under evaluation. A number of molecular mechanisms responsible of transformation and progression of pancreatic cancer have been identified, opening the possibility to identify also possible pharmacological targets. A promising approach is the pharmacological inhibition of tumor angiogenesis with anti-vascular endothelial growth factor (VEGF) agents, such as bevacizumab, cyclooxygenase-2 inhibitors (celecoxib), thalidomide and others. Also epidermal growth factor receptor (EGFR) plays an important role in progression of pancreatic cancer. Erlotinib, an oral available anti-EGFR compound, was the first agent capable to significantly improve overall survival in a phase III trial, leading to its approval by Food and Drug Administration (FDA) in combination with gemcitabine as first-line therapy. Ongoing studies are exploring the role of targeted therapy in the adjuvant setting. However, despite these promising results, several questions remain to be resolved, including the rational selection of the patients who are more likely to obtain benefit of target therapy, the choice of the optimal therapeutic schedule of therapy, the clinical setting of choice, and the management of the toxicity.

Expression of hypoxia-inducible factor-1alpha, histone deacetylase 1, and metastasis-associated protein 1 in pancreatic carcinoma: correlation with poor prognosis with possible regulation

OBJECTIVES

Hypoxia-inducible factor 1alpha (HIF-1alpha) is a transcription factor that plays an important role in tumor growth and metastasis. Inhibition of histone deacetylase shows a marked inhibition of HIF-1alpha expression; however, the association between HIF-1alpha and histone deacetylase 1 (HDAC1), metastasis-associated protein 1 (MTA1) is not fully understood.

METHODS

Hypoxia-inducible factor 1alpha, HDAC1, and MTA1 expressions were detected by immunohistochemistry in 39 pancreatic carcinoma patients. The correlations between the expression of HIF-1alpha, HDAC1, or MTA1 and clinical features and the prognosis were analyzed.

RESULTS

Hypoxia-inducible factor 1alpha, HDAC1, and MTA1 positive stainings were found in 41%, 56%, and 31%, respectively. There was no correlation between HIF-1alpha, HDAC1, or MTA1 expression levels and any clinical parameters. The survival rate for patients with HIF-1alpha and HDAC1-positive stainings were significantly lower than for patients with HIF-1alpha and HDAC1-negative stainings. The MTA1 overexpression group did not have a significantly lower prognosis than the MTA1 underexpression group. The survival rate for the HDAC1(+)/MTA1(2-3) group was significantly lower than for the other groups.

CONCLUSIONS

These results suggest that HIF-1alpha expression may be regulated through HDAC1/MTA1, which is associated with a poor prognosis for pancreatic carcinoma and indicates that HIF-1alpha and HDAC1/MTA1 are a promising therapeutic target in pancreatic carcinoma treatment.

Identification of thioredoxin-interacting protein 1 as a hypoxia-inducible factor 1alpha-induced gene in pancreatic cancer

OBJECTIVE

To investigate the expression of thioredoxin-interacting protein (TXNIP) during hypoxia and its dependency on hypoxia-inducible factor 1alpha (HIF-1alpha) in pancreatic cancer cell lines.

METHODS

MiaPaCa-2 pancreatic cancer cells were transiently transfected with siRNA to HIF-1alpha and TXNIP protein measured after growth in normoxia or hypoxia. In addition, HIF-1alpha dependency was assessed by transiently transfecting MiaPaCa-2 pancreatic cancer cells with HIF-1alpha with a mutated oxygen degradation domain resulting in stable HIF-1alpha expression in normoxic conditions. Panc-1 pancreatic cancer cells with low endogenous TXNIP expression were stably transfected with TXNIP, and cell survival and response to platinum cancer agents were tested. Quantitative immunohistochemistry was utilized to measure the expression of TXNIP and thioredoxin 1 in human pancreatic cancer tissues.

RESULTS

Thioredoxin-interacting protein was induced during hypoxia in pancreatic cancer cells in a HIF-1alpha-dependent manner. Overexpression of TXNIP in the Panc-1 cells resulted in a higher basal apoptosis and increased sensitivity to cisplatin and oxaliplatin. A negative correlation was observed between TXNIP and thioredoxin 1 expression in human pancreatic cancer tissues.

CONCLUSIONS

Thioredoxin-interacting protein, a putative tumor suppressor gene, is induced in response to hypoxia in a HIF-1alpha-dependent manner in pancreatic cancer cells, resulting in increased apoptosis and increased sensitivity to platinum anticancer therapy. Increased TXNIP may be a mechanism to counterbalance the prosurvival effects of HIF-1alpha.

Evaluation of HIF-1 inhibitors as anticancer agents

Hypoxia-inducible factor 1 (HIF-1) regulates the transcription of many genes involved in key aspects of cancer biology, including immortalization, maintenance of stem cell pools, cellular dedifferentiation, genetic instability, vascularization, metabolic reprogramming, autocrine growth factor signaling, invasion/metastasis, and treatment failure. In animal models, HIF-1 overexpression is associated with increased tumor growth, vascularization, and metastasis, whereas HIF-1 loss-of-function has the opposite effect, thus validating HIF-1 as a target. In further support of this conclusion, immunohistochemical detection of HIF-1alpha overexpression in biopsy sections is a prognostic factor in many cancers. A growing number of novel anticancer agents have been shown to inhibit HIF-1 through a variety of molecular mechanisms. Determining which combination of drugs to administer to any given patient remains a major obstacle to improving cancer treatment outcomes.

Hypoxia and angiogenesis in pancreatic cancer

BACKGROUND

Pancreatic cancer remains one of the most lethal of all solid tumours of the gastrointestinal tract. It is characterized by late diagnosis, aggressive local invasion, early metastasis and resistance to chemoradiotherapy. Increasing knowledge regarding the molecular events behind the growth and invasion of pancreatic cancer may lead to new targets for intervention.

METHODS

A search of Pubmed and Medline databases was undertaken using the keywords pancreatic cancer, gastrointestinal cancer, hypoxia, angiogenesis and anti-angiogenesis therapy.

RESULTS

Hypoxia is the driving force behind angiogenesis in pancreatic cancers. Research into angiogenesis has shown many different sites that can be targeted by agents such as tyrosine kinase inhibitors.

CONCLUSION

Anti-angiogenic therapy could be an important adjunct to conventional chemotherapy treatment of gastrointestinal neoplasia.

Tumor-stromal cell interaction under hypoxia increases the invasiveness of pancreatic cancer cells through the hepatocyte growth factor/c-Met pathway

The hypoxic environment in tumor is reported to play an important role in pancreatic cancer progression. The interaction between stromal and cancer cells also contributes to the malignant behavior of pancreatic cancer. In the present study, we investigated whether hypoxic stimulation affects stromal as well as pancreatic cancer cells. Our findings demonstrated that hypoxia remarkably elevated the HIF-1alpha expression in both pancreatic cancer (PK8) and fibroblast cells (MRC5). Hypoxic stimulation accelerated the invasive activity of PK8 cells, and invasiveness was thus further accelerated when the hypoxic PK8 cells were cultured with conditioned medium prepared from hypoxic MRC5 cells (hypoxic conditioned medium). MMP-2, MMP-7, MT1-MMP and c-Met expressions were increased in PK8 cells under hypoxia. Hypoxic stimulation also increased the hepatocyte growth factor (HGF) secretion from MRC5 cells, which led to an elevation of c-Met phosphorylation in PK8 cells. Conversely, the elevated cancer invasion, MMP activity and c-Met phosphorylation of PK8 cells were reduced by the removal of HGF from hypoxic conditioned medium. In immunohistochemical study, the HIF-1alpha expression was observed in surrounding stromal as well as pancreatic cancer cells, thus indicating hypoxia exists in both of cancer and stromal cells. Moreover, the stromal HGF expression was found to significantly correlate with not only the stromal HIF-1alpha expression but also the c-Met expression in cancer cells. These results indicate that the hypoxic environment within stromal as well as cancer cells activates the HGF/c-Met system, thereby contributing to the aggressive invasive features of pancreatic cancer.

Regulation of angiogenesis by hypoxia-inducible factor 1

Hypoxia is an imbalance between oxygen supply and demand that occurs in cancer and in ischemic cardiovascular disease. Hypoxia-inducible factor 1 (HIF-1) was originally identified as the transcription factor that mediates hypoxia-induced erythropoietin expression. More recently, the delineation of molecular mechanisms of angiogenesis has revealed a critical role for HIF-1 in the regulation of angiogenic growth factors. In this review, we discuss the role of HIF-1 in developmental, adaptive and pathological angiogenesis. In addition, potential therapeutic interventions involving modulation of HIF-1 activity in ischemic cardiovascular disease and cancer will be discussed.

Effect of antisense hypoxia-inducible factor 1alpha on progression, metastasis, and chemosensitivity of pancreatic cancer

OBJECTIVES

The aim of the study was to observe the effect of antisense hypoxia-inducible factor 1alpha (HIF-1alpha) on progression, metastasis, and chemosensitivity of pancreatic cancer.

METHODS

BxPc-3 cells transfected with antisense HIF-1alpha plasmid were exposed to 0.5% O2 for 4 hours. Expressions of HIF-1alpha, survivin, and beta1 integrin were detected by reverse transcriptase -polymerase chain reaction and Western blotting. Growth inhibition rates and apoptosis rates of BxPc-3 cells under different dosages of chemotherapy agents (5-fluorouracil, doxorubicin, and gemcitabine) were measured by MTT colorimetric assay and flow cytometry. The migration of BxPc-3 cells was assayed using transwell cell culture chambers. Subcutaneous transplantation of BxPc-3 cells in nude mice for 8 weeks was to assess progression and metastasis of pancreatic cancer.

RESULTS

Expression of HIF-1alpha was obviously down-regulated, and at the same time, survivin and beta1-integrin expressions were markedly down-regulated in the experimental group (P < 0.05). Higher dosages (100, 200, and 400 mg/L of 5-fluorouracil; 0.05, 0.075, and 0.1 mg/L of doxorubicin; and 10(-9), 10(-8), and 10(-7) mol/L of gemcitabine) caused a greater increase of inhibition in the experimental group than in control (P < 0.05). The number of migrated BxPc-3 cells in the experimental group was far less than in control (P < 0.05). In vivo, the tumor size and weight in the experimental group were significantly lower than those in control (P < 0.05).

CONCLUSION

Our data demonstrate that antisense HIF-1alpha inhibits expressions of survivin and beta1 integrin, enhancing apoptosis in human pancreatic cancer cells and restraining the progression and metastasis of pancreatic cancer. Therefore, HIF-1alpha may play a very important role in progression, metastasis, and chemosensitivity of human pancreatic cancer. Blocking HIF-1alpha in pancreatic cancer cells may offer an avenue for gene therapy.

Suppressed MKP-1 is an independent predictor of outcome in patients with hepatocellular carcinoma

OBJECTIVE

An increase in the activity of mitogen-activated protein kinases (MAPKs) has been correlated with a more malignant phenotype in several tumor models in vivo. This study was designed to clarify the expression of MKP-1 in surgically resected hepatocellular carcinoma (HCC).

METHODS

We reviewed the cases of 77 patients who had undergone initial liver resection for HCC without preoperative treatment. Immunohistochemical analysis of MKP-1 was performed on paraffin-embedded tissues. The correlation between MKP-1 expression and clinical outcome was investigated.

RESULTS

Tumor cells were immunohistochemically stained for MKP-1 expression, and the same levels as in normal hepatocytes were detected in 66 (85%) of 77 HCC patients, being decreased in 11 (15%) HCCs. Decreased MKP-1 expression significantly correlated with serum alpha-fetoprotein levels and tumor size (p<0.05). The disease-free survival rates in MKP-1-negative and -positive patients were 0 and 31.0% at 5 years, respectively (p<0.01). The survival rates after a surgical resection in MKP-1-negative and -positive patients were 18.2 and 65.5% at 5 years, respectively (p<0.01).

CONCLUSIONS

The MKP-1 expression in HCC was an independent prognostic factor for outcome in HCC patients. In the future, it will be useful to explore whether the phosphatase expression might account for the response to HCC treatments targeting at MAPK activation.

Expression of hypoxia-inducible factors is correlated with the presence of a fibrotic focus and angiogenesis in pancreatic ductal adenocarcinomas

AIMS

To study the expression of hypoxia-regulated markers in pancreatic ductal adenocarcinomas (PA) in relationship to the presence of a fibrotic focus, angiogenesis quantification and clinical outcome.

METHODS AND RESULTS

The expression of hypoxia-inducible factor (HIF)-1alpha, HIF-2alpha, carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) was immunohistochemically detected in 50 PA and correlated with tumour characteristics, microvascular density (MVD) and survival. HIF-1alpha was expressed within tumour cells in 68%, HIF-2alpha in 46%, CA9 in 78% and VEGF in 52% of the cases. Stromal expression was also noted for HIF-2alpha and CA9 in, respectively, 42% and 48% of the cases. Tumour CA9 expression was associated with that of VEGF (P=0.004) and that of stromal HIF-2alpha (P=0.013), with the presence of a fibrotic focus (P=0.046) and with an increased MVD (P=0.034). Tumour VEGF expression correlated with the presence of a fibrotic focus (P=0.039) and a greater MVD (P=0.047). Both the presence of a fibrotic focus (P=0.0002) and high tumour CA9 expression (P=0.029) were associated with reduced overall survival.

CONCLUSION

The strong association of the presence of a fibrotic focus with CA9 expression and lower survival demonstrates that hypoxia-driven angiogenesis plays an important role in the progression of PA.

The hypoxia-inducible factor and tumor progression along the angiogenic pathway

The hypoxia-inducible factor (HIF) is a transcription factor that plays a key role in the response of cells to oxygen levels. HIF is a heterodimer of alpha- and beta-subunits where the alpha-subunit is translated constitutively but has a very short half-life under normal oxygen concentrations. Negative regulation of the half-life and activity of the alpha-subunit is dependent on its posttranslational hydroxylation by hydroxylases that are dependent on oxygen for activity. Thus under low oxygen (hypoxic) conditions the hydroxylases are inactive and the alpha-subunit is stable and able to interact with the beta-subunit to bind and induce transcription of target genes. Hypoxic conditions are encountered in development and in disease states such as cancer. Tumors that have outstripped their blood supply become hypoxic and express high levels of HIF. HIF in turn targets genes that induce survival, glycolysis, and angiogenesis, a form of neovascularization, which ensures the tumor with a continued supply of oxygen and nutrients for further growth.

Genomics of pancreatic cancer: does it make any improvement in diagnosis, prognosis and therapy?

Pancreatic cancer (PanC) is an extremely lifethreatening neoplasm due to its late discovery, rapid progression and resistance to chemo- and radiotherapy. In the past years a significant research attention turned to this cancer. Extensive genomic analysis of PanC revealed numerous alterations, however, none of them emerged yet as a key regulator of tumor progression. Our increasing knowledge on the molecular targets in various cancer types started to change their management. Examples of success of the molecular therapies (in CML, GIST, NSCLC) may initiate more activity in pancreatic cancer as well.

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