CES2 sustains HNF4α expression to promote pancreatic adenocarcinoma progression through an epoxide hydrolase-dependent regulatory loop

Objective

Intra-tumoral expression of the serine hydrolase carboxylesterase 2 (CES2) contributes to the activation of the pro-drug irinotecan in pancreatic ductal adenocarcinoma (PDAC). Given other potential roles of CES2, we assessed its regulation, downstream effects, and contribution to tumor development in PDAC.

Methods

Association between the mRNA expression of CES2 in pancreatic tumors and overall survival was assessed using The Cancer Genome Atlas. Cell viability, clonogenic, and anchorage-independent growth assays as well as an orthotopic mouse model of PDAC were used to evaluate the biological relevance of CES2 in pancreatic cancer. CES2-driven metabolic changes were determined by untargeted and targeted metabolomic analyses.

Results

Elevated tumoral CES2 mRNA expression was a statistically significant predictor of poor overall survival in PDAC patients. Knockdown of CES2 in PDAC cells reduced cell viability, clonogenic capacity, and anchorage-independent growth in vitro and attenuated tumor growth in an orthotopic mouse model of PDAC. Mechanistically, CES2 was found to promote the catabolism of phospholipids resulting in HNF4α activation through a soluble epoxide hydrolase (sEH)-dependent pathway. Targeting of CES2 via siRNA or small molecule inhibitors attenuated HNF4α protein expression and reduced gene expression of classical/progenitor markers and increased basal-like markers. Targeting of the CES2-sEH-HNF4α axis using small molecule inhibitors of CES2 or sEH reduced cell viability.

Conclusions

We establish a novel regulatory loop between CES2 and HNF4α to sustain the progenitor subtype and promote PDAC progression and highlight the potential utility of CES2 or sEH inhibitors for the treatment of PDAC as part of non-irinotecan-containing regimens.

Compound NSC84167 selectively targets NRF2-activated pancreatic cancer by inhibiting asparagine synthesis pathway

Nuclear factor erythroid 2-related factor 2 (NRF2) is aberrantly activated in about 93% of pancreatic cancers. Activated NRF2 regulates multiple downstream molecules involved in cancer cell metabolic reprogramming, translational control, and treatment resistance; however, targeting NRF2 for pancreatic cancer therapy remains largely unexplored. In this study, we used the online computational tool CellMinerTM to explore the NCI-60 drug databases for compounds with anticancer activities correlating most closely with the mRNA expression of NQO1, a marker for NRF2 pathway activity. Among the >100,000 compounds analyzed, NSC84167, termed herein as NRF2 synthetic lethality compound-01 (NSLC01), was one of the top hits (r = 0.71, P < 0.001) and selected for functional characterization. NSLC01 selectively inhibited the viabilities of four out of seven conventional pancreatic cancer cell lines and induced dramatic apoptosis in the cells with high NRF2 activation. The selective anticancer activity of NSLC01 was further validated with a panel of nine low-passage pancreatic patient-derived cell lines, and a significant reverse correlation between log(IC50) of NSLC01 and NQO1 expression was confirmed (r = -0.5563, P = 0.024). Notably, screening of a panel of nine patient-derived xenografts (PDXs) revealed six PDXs with high NQO1/NRF2 activation, and NSLC01 dramatically inhibited the viabilities and induced apoptosis in ex vivo cultures of PDX tumors. Consistent with the ex vivo results, NSLC01 inhibited the tumor growth of two NRF2-activated PDX models in vivo (P < 0.01, n = 7-8) but had no effects on the NRF2-low counterpart. To characterize the mechanism of action, we employed a metabolomic isotope tracer assay that demonstrated that NSLC01-mediated inhibition of de novo synthesis of multiple amino acids, including asparagine and methionine. Importantly, we further found that NSLC01 suppresses the eEF2K/eEF2 translation elongation cascade and protein translation of asparagine synthetase. In summary, this study identified a novel compound that selectively targets protein translation and induces synthetic lethal effects in NRF2-activated pancreatic cancers.

CES2 Expression in Pancreatic Adenocarcinoma Is Predictive of Response to Irinotecan and Is Associated With Type 2 Diabetes

PURPOSE

The combination chemotherapy of fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) has provided clinically meaningful improvement for pancreatic ductal adenocarcinoma (PDAC). We previously uncovered a role for the serine hydrolase carboxylesterase 2 (CES2) in mediating intratumoral activation of the prodrug irinotecan, a constituent of FOLFIRINOX. We aimed to further test the predictive value of CES2 for response to irinotecan using patient-derived xenograft (PDX) models and to elucidate the determinants of CES2 expression and response to FOLFIRINOX treatment among patients with PDAC.

METHODS

PDXs were engrafted subcutaneously into nude mice and treated for 4 weeks with either saline control or irinotecan. CES2 and hepatocyte nuclear factor 4 alpha (HNF4A) expression in PDAC tissues was evaluated by immunohistochemical and Western blot analysis. Kaplan-Meier and Cox regression analyses were applied to assess the association between overall survival and hemoglobin A1C (HbA1C) levels in patients who underwent neoadjuvant FOLFIRINOX treatment.

RESULTS

High CES2 activity in PDAC PDXs was associated with increased sensitivity to irinotecan. Integrated gene expression, proteomic analyses, and in vitro genetic experiments revealed that nuclear receptor HNF4A, which is upregulated in diabetes, is the upstream transcriptional regulator of CES2 expression. Elevated CES2 protein expression in PDAC tissues was positively associated with a history of type 2 diabetes (odds ratio, 4.84; P = .02). High HbA1C levels were associated with longer overall survival in patients who received neoadjuvant FOLFIRINOX treatment (P = .04).

CONCLUSION

To our knowledge, we provide, for the first time, evidence that CES2 expression is associated with a history of type 2 diabetes in PDAC and that elevated HbA1C, by predicting tumor CES2 expression, may represent a novel marker for stratifying patients most likely to respond to FOLFIRINOX therapy.

CRS/HIPEC with Major Organ Resection in Peritoneal Mesothelioma Does not Impact Major Complications or Overall Survival: A Retrospective Cohort Study of the US HIPEC Collaborative

INTRODUCTION

CRS/HIPEC is thought to confer a survival advantage for patients with malignant peritoneal mesothelioma (MPM). However, the impact of nonperitoneal organ resection is not clearly defined. We evaluated the impact of major organ resection (MOR) on postoperative outcomes and overall survival (OS).

PATIENTS AND METHODS

The US HIPEC collaborative database (2000-2017) was reviewed for MPM patients who underwent CRS/HIPEC. MOR was defined as total or partial resection of diaphragm, stomach, spleen, pancreas, small bowel, colon, rectum, kidney, ureter, bladder, and/or uterus. MOR was categorized as 0, 1, or 2+ organs.

RESULTS

A total of 174 patients were identified. Median PCI was 16 (3-39). The distribution of patients with MOR-0, MOR-1, and MOR-2+ was 94, 45, and 35 patients, respectively. MOR-1 and MOR-2+ groups had a higher frequency of any complication compared with MOR-0 (57.8%, 74.3%, and 48.9%, respectively, p = 0.035), but Clavien 3/4 complications were similar. Median length of stay was slightly higher in the MOR-1 and MOR-2+ groups (10 and 11 days) compared with the MOR-0 cohort (9 days, p = 0.005). Incomplete cytoreduction, ASA class 4, and male gender were associated with increased mortality on unadjusted analysis; however, their impact on OS was attenuated on multivariable analysis. MOR was not associated with OS based on these data (MOR-1: HR 1.67, 95% CI 0.59-4.74; MOR-2+ : HR 0.77, 95% CI 0.22-2.69).

CONCLUSIONS

MOR was not associated with an increase in major complications or worse OS in patients undergoing CRS/HIPEC for MPM and should be considered, if necessary, to achieve complete cytoreduction for MPM patients.

Neutrophil to lymphocyte ratio, not platelet to lymphocyte or lymphocyte to monocyte ratio, is predictive of patient survival after resection of early-stage pancreatic ductal adenocarcinoma

Background

NLR, PLR, and LMR have been associated with pancreatic ductal adenocarcinoma (PDAC) survival. Prognostic value and optimal cutpoints were evaluated to identify underlying significance in surgical PDAC patients.

Methods

NLR, PLR, and LMR preoperative values were available for 277 PDAC patients who underwent resection between 2007 and 2015. OS, RFS, and survival probability estimates were calculated by univariate, multivariable, and Kaplan-Meier analyses. Continuous and dichotomized ratio analysis determined best-fit cutpoints and assessed ratio components to determine primary drivers.

Results

Elevated NLR and PLR and decreased LMR represented 14%, 50%, and 50% of the cohort, respectively. OS (P = .002) and RFS (P = .003) were significantly decreased in resected PDAC patients with NLR ≥5 compared to those with NLR < 5. Optimal prognostic OS and RFS cutpoints for NLR, PLR, and LMR were 4.8, 192.6, and 1.7, respectively. Lymphocytes alone were the primary prognostic driver of NLR, demonstrating identical survival to NLR.

Conclusions

NLR is a significant predictor of OS and RFS, with lymphocytes alone as its primary driver; we identified optimal cutpoints that may direct future investigation of their prognostic value. This study contributes to the growing evidence of immune system influence on outcomes in early-stage pancreatic cancer.

Stellate Cells in the Tumor Microenvironment

As tumor microenvironments share many of the same qualities as chronic wounds, attention is turning to the wound-repair cells that support the growth of cancerous cells. Stellate cells are star-shaped cells that were first discovered in the perisinusoidal spaces in the liver and have been found to support wound healing by the secretion of growth factors and extracellular matrix. They have since been also found to serve a similar function in the pancreas. In both organs, the wound-healing process may become dysregulated and lead to pathological fibrosis (also known as cirrhosis in the liver). In recent years there has been increasing attention paid to the role of these cells in tumor formation and progression. They may be a factor in initiating the first steps of carcinogenesis such as with liver cirrhosis and hepatocellular carcinoma and also contribute to continued tumor growth, invasion, metastasis, evasion of the immune system, and resistance to chemotherapy, in cancers of both the liver and pancreas. In this chapter we aim to review the structure and function of hepatic and pancreatic stellate cells and their contributions to the tumor microenvironment in their respective cancers and also discuss potential new targets for cancer therapy based on our new understanding of these vital components of the tumor stroma.

Estimation of hepatocellular carcinoma mortality using aspartate aminotransferase to platelet ratio index

BACKGROUND

Hepatocellular carcinoma (HCC) patients with cirrhosis are high-risk for invasive procedures. Identification of those at risk may prevent complications and allow more informed decision-making. The aspartate aminotransferase (AST) to platelet ratio index (APRI) is a measure of cirrhosis that we hypothesize predicts survival and may estimate HCC mortality.

METHODS

Institutional retrospective study of all HCC patients. Demographics and labs [bilirubin, international normalized ratio (INR), creatinine, AST and platelets] were recorded at the date-of-diagnosis to calculate APRI and the Model for End-Stage Liver Disease score (MELD). Poor survival was defined as death within 30-days from diagnosis. Models were created to determine predictors of death within 30-days and overall survival.

RESULTS

A total of 829 patients comprised this study and <30-day death was observed in 111 patients (17%). Mean APRI and MELD scores were higher in the <30-day death group. APRI [odds ratio (OR) 1.45, 95% confidence interval (CI): 1.07-1.96] and MELD (OR 1.21, 95% CI: 1.14-1.28) were predictive of <30-day death. Stratified by stage, APRI [hazard ratio (HR) 1.12, 95% CI: 1.01-1.24] and MELD (HR 1.07, 95% CI: 1.05-1.09) were associated with overall survival. Inclusion of APRI and MELD components in the Cox regression resulted in the best fit (c-index =0.67).

CONCLUSIONS

The APRI is an innovative marker of cirrhosis and survival for HCC patients. APRI provides additional prognostic information regarding the severity of cirrhosis and external validation is needed to determine clinical utility.

Fibrocytes in the Tumor Microenvironment

Tumors have long been compared to chronic wounds that do not heal, since they share many of the same molecular and cellular processes. In normal wounds, healing processes lead to restoration of cellular architecture, while in malignant tumors, these healing processes become dysregulated and contribute to growth and invasion of neoplastic cells into the surrounding tissues. Fibrocytes are fibroblast-like cells that differentiate from bone marrow-derived CD14+ circulating monocytes and aid wound healing. Although most monocytes will differentiate into macrophages after extravasating into a tissue, signals present in a wound environment can cause some monocytes to differentiate into fibrocytes. The fibrocytes secrete matrix proteins and inflammatory cytokines, activate local fibroblasts to proliferate and increase extracellular matrix production, and promote angiogenesis, and because fibrocytes are contractile, they also help wound contraction. There is now emerging evidence that fibrocytes are present in the tumor microenvironment, attracted by the chronic tissue damage and cytokines from both cancer cells and other immune cells. Fibrocytes may aid in the survival and spread of neoplastic cells, so these wound-healing cells may be a promising target for anticancer research in future studies.

Surrogate indicators of quality are associated with survival following surgical treatment for hepatocellular carcinoma

INTRODUCTION

Quality/core measures have been collected for over 10 years. Studies have demonstrated hospital performance is related to postoperative outcomes. We hypothesize that hospital quality measures are associated with long-term survival following surgical resection for hepatocellular carcinoma (HCC).

METHODS

The National Cancer Data Base was queried for all HCC cases. Individual hospitals were deidentified. Quality markers were defined as hospital-specific median length of stay (LOS), 30-day mortality rate and readmit rate. A Cox regression stratified by stage estimated survival. To minimize confounding, a landmark analysis was estimated for patients that survived greater than 30 days.

RESULTS

A total of 16 202 HCC patients underwent surgical resection and 996 (6.1%) died within 30 days following surgery. Calculated by unique hospital, median 30-day death rate was 4.6% (interquartile range [IQR]: 1.2% to 7.6%). Thirty-day readmit rate was 2.6% (IQR: 0% to 5.9%) and median LOS was 8.0 days (IQR: 6.5 to 9.2). In the multivariate Cox regression, 30-day death rate (hazard ratio [HR], 1.89; 95% confidence interval [CI]: 1.32 to 2.71) and longer LOS (HR, 1.02; 95% CI: 1.01 to 1.02) were associated with worse survival. Higher 30-day readmission rate was associated with improved survival (HR, 0.61; 95% CI, 0.38 to 0.97).

CONCLUSIONS

Hospital-level surrogate markers of surgical quality appear to be significantly associated with HCC survival following resection. Patients treated in higher 30-day mortality centers, experienced worse outcomes. Individual hospitals should critically review disease-specific outcomes following resection to identify areas for improvement.

Prolonged exposure to extracellular lumican restrains pancreatic adenocarcinoma growth

We previously demonstrated that pancreatic stellate cells within pancreatic ductal adenocarcinoma (PDAC) stroma secrete lumican and its presence is associated with prolonged survival of patients with localized PDAC. Here, we observed that extracellular lumican decreases PDAC tumour cell growth in xenograft and syngeneic orthotopic animal models, and induces growth inhibition of low-passage human PDAC cells in a species-specific manner. PDAC cells grown in variant culture conditions and exposed to extracellular lumican display typical characterizations of cancer cell in a quiescent state, such as growth inhibition, apoptosis, G0/G1 arrest and chemoresistance. Importantly, extracellular lumican is associated with diminished ERK1/2 phosphorylation and increased p38 phosphorylation within PDAC cells. We further demonstrated that extracellular lumican physically binds with EGFR to trigger EGFR internalization and downregulation of EGFR and its downstream signal molecule ERK. Lumican enhances casitas B-lineage lymphoma expression, which stabilized the TGFβ Type II receptor sensitizing PDAC cells to TGFβ-mediated activation of p38 and SMAD signals. These provide a mechanism for the shift in signalling and phenotypic changes we observed after prolonged exposure to lumican. Together, our findings demonstrate that stromal lumican restrains PDAC cell growth through mediating cell entry into a quiescent state.

Generation of patient-derived xenografts from fine needle aspirates or core needle biopsy

BACKGROUND

Patient-derived xenografts have recently become a powerful tool for cancer research and may be used to guide personalized therapy. Thus far, patient-derived xenografts have been grown from tumor tissue obtained after operative resection; however, many cancer patients never undergo operative intervention for a variety of reasons. We hypothesized that xenograft tumors could be grown from smaller volumes of patient tissue, such as those obtained during diagnostic biopsies.

METHODS

Surgical specimens were obtained after resection of primary or metastatic lesions of the following cancers: pancreatic carcinoma, non-small cell lung cancer, bladder (urothelial) carcinoma, and melanoma. At least 10 cases of each cancer were included in this study. To mimic clinical biopsies, small fragments of the surgical specimens were biopsied with a 22-gauge needle, and the needle contents were injected subcutaneously in immunocompromised mice. The tumor fragment from which the biopsy was taken was also implanted subcutaneously in the contralateral side of the same mouse as a control.

RESULTS

Success rates of the traditional method of xenograft implantation ranged from 27.3%-70%. Success rates of the fine needle aspirate technique ranged from 0%-36.4%. An attempt to engraft a percutaneous core needle liver biopsy of a metastatic pancreatic adenocarcinoma also was successful.

CONCLUSION

We have found that it is possible to engraft fine needle aspirates and core biopsies of solid tumors in order to generate patient-derived xenografts. This may open up xenografting to a wider cancer patient population than previously possible.

Preclinical Evaluation of Sequential Combination of Oncolytic Adenovirus Delta-24-RGD and Phosphatidylserine-Targeting Antibody in Pancreatic Ductal Adenocarcinoma

Delta-24-RGD (DNX-2401) is a conditional replication-competent oncolytic virus engineered to preferentially replicate in and lyse tumor cells with abnormality of p16/RB/E2F pathway. In a phase I clinical trial, Delta-24-RGD has shown favorable safety profile and promising clinical efficacy in brain tumor, which prompted us to evaluate its anticancer activity in pancreatic ductal adenocarcinoma (PDAC), which also has high frequency of homozygous deletion and promoter methylation of CDKN2A encoding the p16 protein. Our results demonstrate that Delta-24-RGD can induce dramatic cytotoxicity in a subset of PDAC cell lines with high cyclin D1 expression. Induction of autophagy and apoptosis by Delta-24-RGD in sensitive PDAC cells was confirmed with LC3B-GFP autophagy reporter and acridine orange staining as well as Western blotting analysis of LC3B-II expression. Notably, we found that Delta-24-RGD induced phosphatidylserine exposure in infected cells independent of cells' sensitivity to Delta-24-RGD, which renders a rationale for combination of Delta-24-RGD viral therapy and phosphatidylserine targeting antibody for PDAC. In a mouse PDAC model derived from a liver metastatic pancreatic cancer cell line, Delta-24-RGD significantly inhibited tumor growth compared with control (P < 0.001), and combination of phosphatidylserine targeting antibody 1N11 further enhanced its anticancer activity (P < 0.01) possibly through inducing synergistic anticancer immune responses. Given that these 2 agents are currently in clinical evaluation, our study warrants further clinical evaluation of this novel combination strategy in pancreatic cancer therapy. Mol Cancer Ther; 16(4); 662-70. ©2016 AACR.

Ex Vivo Testing of Patient-Derived Xenografts Mirrors the Clinical Outcome of Patients with Pancreatic Ductal Adenocarcinoma

PURPOSE

Translation of the patient-derived xenograft (PDX) model into a method for practical personalized cancer treatment is prevented by the intense resources and time necessary to generate and test each tumorgraft. We aimed to develop a high-throughput ex vivo drug testing approach that can be used for personalized cancer treatment design.

EXPERIMENTAL DESIGN

We developed a unique ex vivo live tissue sensitivity assay (LTSA), in which precision-cut and uniform small tissue slices derived from pancreatic ductal adenocarcinoma PDX tumors were arrayed in a 96-well plate and screened against clinically relevant regimens within 3 to 5 days. The correlation between the sensitivities of tissue slices to the regimens and patients' clinical responses and outcome were statistically analyzed. The results of LTSA assay were further confirmed with biochemical methods in vitro and animal PDX model in vivo RESULTS: The ex vivo tissue slices remain viable for at least 5 days, and the tumor parenchyma, including stroma, vascular structures, and signaling pathways, are all retained. The sensitivities of the ex vivo tissue slices to gemcitabine and irinotecan was consistent with the clinical responses and outcomes of the patients from whom the tumorgrafts were derived (r = 0.77; P = 0.0002). Retrospective analysis showed that the patients who received LTSA-sensitive regimens had remarkably longer progression-free survival than patients who received LTSA-resistant regimens (16.33 vs. 3.8 months; n = 18, P = 0.011).

CONCLUSIONS

The results from these PDX and LTSA methods reflect clinical patients' responses and could be used as a personalized strategy for improving systemic therapy effectiveness in patients with pancreatic cancer. Clin Cancer Res; 22(24); 6021-30. ©2016 AACR.

Transforming Growth Factor-β Limits Secretion of Lumican by Activated Stellate Cells within Primary Pancreatic Adenocarcinoma Tumors

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is lethal cancer whose primary tumor is characterized by dense composition of cancer cells, stromal cells, and extracellular matrix (ECM) composed largely of collagen. Within the PDAC tumor microenvironment, activated pancreatic stellate cells (PSC) are the dominant stromal cell type and responsible for collagen deposition. Lumican is a secreted proteoglycan that regulates collagen fibril assembly. We have previously identified that the presence of lumican in the ECM surrounding PDAC cells is associated with improved patient outcome after multimodal therapy and surgical removal of localized PDAC.

EXPERIMENTAL DESIGN

Lumican expression in PDAC from 27 patients was determined by IHC and quantitatively analyzed for colocalization with PSCs. In vitro studies examined the molecular mechanisms of lumican transcription and secretion from PSCs (HPSCs and HPaSteC), and cell adhesion and migration assays examined the effect of lumican on PSCs in a collagen-rich environment.

RESULTS

Here we identify PSCs as a significant source of extracellular lumican production through quantitative IHC analysis. We demonstrate that the cytokine, TGF-β, negatively regulates lumican gene transcription within HPSCs through its canonical signaling pathway and binding of SMAD4 to novel SBEs identified within the promoter region. In addition, we found that the ability of HPSCs to produce and secrete extracellular lumican significantly enhances HPSCs adhesion and mobility on collagen.

CONCLUSIONS

Our results demonstrate that activated pancreatic stellate cells within PDAC secrete lumican under the negative control of TGF-β; once secreted, the extracellular lumican enhances stellate cell adhesion and mobility in a collagen-rich environment. Clin Cancer Res; 22(19); 4934-46. ©2016 AACR.

Extracellular lumican augments cytotoxicity of chemotherapy in pancreatic ductal adenocarcinoma cells via autophagy inhibition

Lumican, an extracellular matrix proteoglycan overexpressed by pancreatic stellate cells (PSCs) and pancreatic ductal adenocarcinoma cells (PDACs), drives the formation of a tumor-specific microenvironment. We recently showed that extracellular lumican inhibits pancreatic cancer cell growth and is associated with prolonged survival after surgery. Here we investigated the role of extracellular lumican in chemotherapy-mediated cancer therapy. Lumican secretion was increased by chemotherapeutic agents in PDAC, and especially in PSCs, and appeared to be linked to the extent of cells' response to chemotherapy-induced growth inhibition. In multiple PDAC models, including cell lines, patient-derived xenografts and lumican knockout mice, lumican significantly increased antitumor effect of chemotherapy. This effect was associated with DNA damage, apoptosis and inhibition of cell viability, glucose consumption, lactate production and vascular endothelial growth factor secretion. In PDAC cells, chemotherapeutic agents triggered autophagosome formation and increased LC3 expression through the reactive oxygen species-mediated AMP-activated kinase (AMPK) signaling pathway. Inhibition of gemcitabine-induced autophagy in cancer cells by treatment with AMPK inhibitor compound C, lysosomal inhibitor chloroquine or autophagy inhibitor 3MA enhanced gemcitabine-induced apoptosis, suggesting that autophagy is a protective cellular response to gemcitabine treatment. Importantly, lumican dramatically decreased AMPK activity, inhibiting chemotherapy-induced autophagy in both in vitro and in vivo PDAC models. Co-treatment of PDAC cells with lumican and gemcitabine increased mitochondrial damage, reactive oxygen species (ROS) production and cytochrome c release, indicating that lumican-induced disruption of mitochondrial function may be the mechanism of sensitization to gemcitabine. Together, our findings demonstrate that extracellular lumican augments cytotoxicity of chemotherapy in PDAC cells through inhibition of chemotherapeutic agent-induced autophagy.

Auranofin to prevent progression of pancreatic ductal adenocarcinoma

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Background: Auranofin, an FDA anti-rheumatic agent shown to have anticancer properties for lung and ovarian cancer has never been studied for pancreatic cancer. We hypothesize that Auranofin may prevent pancreatic ductal adenocarcinoma (PDAC) progression by induction of apoptosis. Methods: We performed in vitro and in vivo studies using human PDAC cell lines and patient-derived xenografts (PDX) to assess Auranofin anticancer activity. Sensitivity to the compound was determined based on IC50s. Western blot assay was used to interrogate mechanisms of apoptosis, autophagy, and resistance. Two PDAC orthotopic mouse models were designed to determine optimal dose (survival), and antitumor effect (non-survival). Results: We found more than half of PDAC cell lines (10/18) to be sensitive to Auranofin based on IC50s below 5µM. Ex vivo tissue growth inhibition greater than 44% was observed for 13 PDX tissue cases treated with 10 µM Auranofin. Treatment with low-dose Auranofin (0.5-1µM) was found to induce PARP cleavage and LC3B expression among sensitive cell lines when compared to control (0.1% DMSO). High Txnrd1 and low Nrf2 expression was observed for resistant cell lines. Survival study using MiaPaCa-2 Luc+ showed 15mg/kg IP as the optimal dose due to absence of gross solid organ metastasis up to 13 weeks post-treatment (median survival 8 and 12, respectively; p = 0.0953). Non-survival study using MDA-Patc53 Luc+ showed a decreased tumor bioluminescence (p = 0.1097) and a 9-fold decrease in mean tumor progression from baseline (p = 0.1640) 3 weeks post-treatment. Conclusions: We have demonstrated that Auranofin prevents PDAC progression using two animal models. In vitro studies suggest apoptosis and autophagy as possible mechanisms of action, and Txnrd1 as a biomarker of resistance. This study altogether demonstrates both primary and metastatic antitumor effect of Auranofin for PDAC, which could represent an advantageous therapeutic approach for a broad selection of patients in both neoadjuvant and adjuvant settings.

Galectin-3 Binding Protein Secreted by Breast Cancer Cells Inhibits Monocyte-Derived Fibrocyte Differentiation

To metastasize, tumor cells often need to migrate through a layer of collagen-containing scar tissue which encapsulates the tumor. A key component of scar tissue and fibrosing diseases is the monocyte-derived fibrocyte, a collagen-secreting profibrotic cell. To test the hypothesis that invasive tumor cells may block the formation of the fibrous sheath, we determined whether tumor cells secrete factors that inhibit monocyte-derived fibrocyte differentiation. We found that the human metastatic breast cancer cell line MDA-MB-231 secretes activity that inhibits human monocyte-derived fibrocyte differentiation, whereas less aggressive breast cancer cell lines secrete less of this activity. Purification indicated that Galectin-3 binding protein (LGALS3BP) is the active factor. Recombinant LGALS3BP inhibits monocyte-derived fibrocyte differentiation, and immunodepletion of LGALS3BP from MDA-MB 231 conditioned media removes the monocyte-derived fibrocyte differentiation-inhibiting activity. LGALS3BP inhibits the differentiation of monocyte-derived fibrocytes from wild-type mouse spleen cells, but not from SIGN-R1(-/-) mouse spleen cells, suggesting that CD209/SIGN-R1 is required for the LGALS3BP effect. Galectin-3 and galectin-1, binding partners of LGALS3BP, potentiate monocyte-derived fibrocyte differentiation. In breast cancer biopsies, increased levels of tumor cell-associated LGALS3BP were observed in regions of the tumor that were invading the surrounding stroma. These findings suggest LGALS3BP and galectin-3 as new targets to treat metastatic cancer and fibrosing diseases.

Two-dimensional culture of human pancreatic adenocarcinoma cells results in an irreversible transition from epithelial to mesenchymal phenotype

Many commercially available cell lines have been in culture for ages, acquiring phenotypes that differ from the original cancers from which these cell lines were derived. Therefore, research on new cell lines could improve the success rates of translational research in cancer. We have developed methods for the isolation and culture of human pancreatic ductal adenocarcinoma (PDAC) cells from murine xenografts of human PDAC. We hypothesize that phenotypes of PDAC cells are modified by in vitro culture conditions over time and by in vivo implantation. Patient-derived xenografts were created in immunodeficient mice using surgically resected tumor specimens. These murine xenografts were then used to establish human PDAC cell lines in culture. Earlier (<5) passage and later (>20) passage cell lines were evaluated separately regarding proliferation, cell cycle, genetic mutations, invasiveness, chemosensitivity, tumorigenesis, epithelial-mesenchymal transition (EMT) status, and proteomics. Later passage cells accelerated their doubling time and colony formation, and were more concentrated in the G0/G1 phase and less in the G2/M checkpoint phase. Later passage cells were more sensitive to gemcitabine and 5-fluorouracil than earlier passage cells, but all four new cell lines were more chemo-resistant compared with commercial ATCC cell lines. EMT induction was observed when establishing and passaging cell lines in vitro and furthermore by growing them as subcutaneous tumors in vivo. This study demonstrates a novel approach to the establishment of PDAC cell lines and observes a process by which newly established cell lines undergo phenotypic changes during in vitro culture and in vivo tumorigenesis. This may help explain differences of treatment effects often observed between experiments conducted in vitro, in vivo, and in human clinical trials.

Extracellular lumican inhibits pancreatic cancer cell growth and is associated with prolonged survival after surgery

PURPOSE

To evaluate the relevance between lumican expression patterns and the clinical course of patients with pancreatic ductal adenocarcinoma (PDAC), and to investigate the role of lumican in PDAC progression.

EXPERIMENTAL DESIGN

One hundred thirty-one patient tumors were chosen for tissue microarray staining, and Cox regression analysis was used to test the associations between lumican expression and clinical, pathologic, and oncologic outcomes in all patients. Primary PDAC cells and recombinant human lumican protein were used to establish a working model to mimic the in vivo interactions between stromal lumican and PDAC cells. Using this model, we tested the effects of lumican on EGFR signaling via Akt and hypoxia-inducible factor-1α (HIF1α) and its subsequent influence on glucose consumption, lactate production, intracellular ATP, and apoptotic cell death.

RESULTS

Lumican was present in the stroma surrounding PDAC cells in roughly one-half of primary tumors and the direct xenografts. Patients with stromal lumican were associated with a profound reduction in metastatic recurrence after surgery and 3-fold longer survival than patients without stromal lumican. In PDAC cells, extracellular lumican reduced EGFR expression and phosphorylation through enhanced dimerization and internalization of EGFR and the resultant inhibition of Akt kinase activity. Lumican also reduced HIF1α expression and activity via Akt. PDAC cells with enhanced HIF1α activity were resistant to lumican-induced inhibition of glucose consumption, lactate production, intracellular ATP, and apoptosis.

CONCLUSIONS

There is a positive association between stromal lumican in primary PDAC tumors and prolonged survival after tumor resection. Lumican plays a restrictive role in EGFR-expressing pancreatic cancer progression.

Genistein potentiates the antitumor effect of 5-Fluorouracil by inducing apoptosis and autophagy in human pancreatic cancer cells

BACKGROUND

Although 5-fluorouracil (5-FU)-based combination chemotherapy (i.e. FOLFIRINOX) has demonstrated effectiveness against pancreatic cancer, novel therapeutic strategies must be developed to increase the therapeutic window of these cytotoxic agents. Genistein is a soy-derived isoflavone with pleiotropic biological effects that can enhance the antitumor effect of chemotherapeutic agents.

MATERIALS AND METHODS

To understand how genistein potentiates the antitumor effects of 5-FU, we examined apoptosis and autophagy in MIA PaCa-2 human pancreatic cancer cells and their derived xenografts. Apoptosis was evaluated using DNA fragmentation assays, and western blots of poly(ADP ribose)polymerase and caspase-3. Meanwhile, autophagy was evaluated using western blots of microtubule-associated protein light chain 3 (LC3)-I/II, fluorescent microscopy observation of green fluorescent protein-LC3B puncta formation, and acidic vesicular organelle formation using acridine orange staining. Tumors from animal treatment studies were examined for apoptosis and autophagy using the TdT-mediated dUTP nick-end labeling assay and immunohistochemical staining of LC3B, respectively.

RESULTS

We observed that genistein increased 5-FU-induced cell death through increased apoptosis, as well as autophagy. The increased autophagy was accompanied by decreased B-cell lymphoma 2 (Bcl2) and increased beclin-1 protein levels. Animal treatment studies supported these observations. The combination of 5-FU and genistein significantly reduced final xenograft tumor volume when compared to 5-FU-alone by inducing apoptosis as well as autophagy.

CONCLUSION

Genistein can potentiate the antitumor effect of 5-FU by inducing apoptotic as well as autophagic cell death. These results demonstrate the potential of genistein as an adjuvant therapeutic agent against pancreatic cancer.

A serum amyloid P-binding hydrogel speeds healing of partial thickness wounds in pigs

During wound healing, some circulating monocytes enter the wound, differentiate into fibroblast-like cells called fibrocytes, and appear to then further differentiate into myofibroblasts, cells that play a key role in collagen deposition, cytokine release, and wound contraction. The differentiation of monocytes into fibrocytes is inhibited by the serum protein serum amyloid P (SAP). Depleting SAP at a wound site thus might speed wound healing. SAP binds to some types of agarose in the presence of Ca(2+). We found that human SAP binds to an agarose with a K(D) of 7 x 10(-8) M and a B(max) of 2.1 microg SAP/mg wet weight agarose. Mixing this agarose 1 : 5 w/v with 30 microg/mL human SAP (the average SAP concentration in normal serum) in a buffer containing 2 mM Ca(2+) reduced the free SAP concentration to approximately 0.02 microg/mL, well below the concentration that inhibits fibrocyte differentiation. Compared with a hydrogel dressing and a foam dressing, dressings containing this agarose and Ca(2+) significantly increased the speed of wound healing in partial thickness wounds in pigs. This suggests that agarose/Ca(2+) dressings may be beneficial for wound healing in humans.

Reduction of bleomycin-induced pulmonary fibrosis by serum amyloid P

Fibrotic diseases such as scleroderma, severe chronic asthma, pulmonary fibrosis, and cardiac fibrosis kill tens of thousands of people each year in the U.S. alone. Growing evidence suggests that in fibrotic lesions, a subset of blood monocytes enters the tissue and differentiates into fibroblast-like cells called fibrocytes, causing tissue dysfunction. We previously found that a plasma protein called serum amyloid P (SAP) inhibits fibrocyte differentiation in vitro. Bleomycin treatment is a standard model for pulmonary fibrosis, and causes an increase in collagen, fibrocytes, and leukocytes in the lungs, and a decrease in peripheral blood hemoglobin oxygen saturation. We find that injections of rat SAP in rats reduce all of the above bleomycin-induced changes, suggesting that the SAP injections reduced the bleomycin-induced pulmonary fibrosis. We repeated these studies in mice, and find that injections of murine SAP decrease bleomycin-induced pulmonary fibrosis. To confirm the efficacy of SAP treatment, we used a delayed treatment protocol using SAP from day 7 to 13 only, and then measured fibrosis at day 21. Delayed SAP injections also reduce the bleomycin-induced decrease in peripheral blood hemoglobin oxygen saturation, and an increase in lung collagen, leukocyte infiltration, and fibrosis. Our data suggest the possibility that SAP may be useful as a therapy for pulmonary fibrosis in humans.