Resistance Of Pancreatic Adenocarcinoma Research Articles

Abstract 4613: Tumor-derived interleukin 35 facilitates the gemcitabine resistance in pancreatic adenocarcinoma by mediating the dissemination of chemoresistance among PDAC cells

Abstract Rapid drug resistance after chemotherapy is a key cause of treatment failure in human pancreatic ductal adenocarcinoma (PDAC). Here, we found that tumor-derived interleukin 35 (IL-35) mediated the rapid resistance of PDAC to gemcitabine (GEM). The role of IL-35 in GEM resistance was determined by molecular and cell biology approaches in PDAC cells and in patient-derived tumor xenograft (PDX) models. We used whole genome RNA sequencing, molecular cloning and other molecular biological methods to study the molecular mechanism of IL-35 mediated GEM resistance. An anti-IL-35 neutralizing antibody was used in mouse models to investigate the feasibility of targeting IL-35 to overcome drug resistance in pancreatic cancer. We observed the phenomenon that GEM resistance could spread from GEM resistant PDAC cells to GEM sensitive ones. The results of sequencing and experiments confirmed that the IL-35 secretion is responsible for the dissemination of chemoresistance. IL-35 secreted from GEM resistant cells activated the IL35 expression in GEM sensitive cells and upregulated SOD2 expression via GP130-STAT1 signaling, which scavenges reactive oxygen species (ROS) and then leads to GEM resistance.Furthermore, we found that a neutralizing antibody against IL-35 significantly enhanced the tumor suppressive effect of GEM. These findings collectively reveal that IL-35 plays crucial roles in mediating GEM resistance in pancreatic cancer. Moreover, IL-35 might serve as a promising therapeutic target for combating PDAC chemoresistance. Citation Format: Chongbiao Huang, Huizhi Sun, Antao Chang, Jihui Hao. Tumor-derived interleukin 35 facilitates the gemcitabine resistance in pancreatic adenocarcinoma by mediating the dissemination of chemoresistance among PDAC cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4613.

Tumor-derived interleukin 35 mediates the dissemination of gemcitabine resistance in pancreatic adenocarcinoma.

Rapid development of drug resistance after chemotherapy is a major cause of treatment failure in individuals with pancreatic ductal adenocarcinoma (PDAC). In this study, we illustrate that tumor-derived interleukin 35 (IL-35) mediates the accelerated resistance of PDAC to gemcitabine (GEM). We observe that GEM resistance can spread from GEM-resistant PDAC cells to GEM-sensitive cells, and that IL-35 is responsible for the propagation of chemoresistance, which is supported by sequencing and experimental data. Additionally, we discover that GEM-resistant cells have significantly higher levels of IL-35 expression. Mechanistically, aberrantly expressed IL-35 triggers transcriptional activation of SOD2 expression via GP130-STAT1 signaling, scavenging reactive oxygen species (ROS) and leading to GEM resistance. Furthermore, GEM treatment stimulates IL-35 expression through activation of the NF-κB pathway, resulting in acquired chemoresistance. In the mouse model, a neutralizing antibody against IL-35 enhances the tumor suppressive effect of GEM. Collectively, our data suggests that IL-35 is critical in mediating GEM resistance in pancreatic cancer, and therefore could be a valuable therapeutic target in overcoming PDAC chemoresistance.

ATF3-induced activation of NF-κB pathway results in acquired PARP inhibitor resistance in pancreatic adenocarcinoma

ATF3-induced activation of NF-κB pathway results in acquired PARP inhibitor resistance in pancreatic adenocarcinoma

ITGB5 promotes innate radiation resistance in pancreatic adenocarcinoma by promoting DNA damage repair and the MEK/ERK signaling pathway.

Pancreatic adenocarcinoma (PAAD) is one of the most aggressive digestive system tumors in the world, with a low early diagnosis rate and a high mortality. Integrin beta 5 (ITGB5) is demonstrated to be a potent tumor promoter in several carcinomas. However, it is unknown whether ITGB5 participates in the occurrence and development of PAAD. In this study, we confirmed a high expression of ITGB5 in PAAD and its role in promoting invasiveness and transitivity in PAAD. Besides, the knockdown of ITGB5 increased cell sensitivity to radiation by promoting DNA damage repair and the MEK/ERK signaling pathway. Collectively, these results show that ITGB5 plays an essential role in pancreatic cancer growth and survival.

Systematic exploration of the underlying mechanism of gemcitabine resistance in pancreatic adenocarcinoma.

Resistance to gemcitabine is the main challenge of chemotherapy for pancreatic ductal adenocarcinoma (PDAC). Hence, the development of a response signature to gemcitabine is essential for precision therapy of PDAC. However, existing quantitative signatures of gemcitabine are susceptible to batch effects and variations in sequencing platforms. Therefore, based on within‐sample relative expression ordering of pairwise genes, we developed a transcriptome‐based gemcitabine signature consisting of 28 gene pairs (28‐GPS) that could predict response to gemcitabine for PDAC at the individual level. The 28‐GPS was superior to previous quantitative signatures in terms of classification accuracy and prognostic performance. Resistant samples classified by 28‐GPS showed poorer overall survival, higher genomic instability, lower immune infiltration, higher metabolic level and higher‐fidelity DNA damage repair compared with sensitive samples. In addition, we found that gemcitabine combined with phosphoinositide 3‐kinase (PI3K) inhibitor may be an alternative treatment strategy for PDAC. Single‐cell analysis revealed that cancer cells in the same PDAC sample showed both the characteristics of sensitivity and resistance to gemcitabine, and the activation of the TGFβ signalling pathway could promote progression of PDAC. In brief, 28‐GPS could robustly determine whether PDAC is resistant or sensitive to gemcitabine, and may be an auxiliary tool for clinical treatment.

High Insulin Resistance in Pancreatic Adenocarcinoma

Abstract Introduction: Diabetes mellitus and obesity is associated with increased risk of pancreatic cancer which has been postulated to be due to pancreatic beta cell dysfunction and increased insulin resistance. Pancreatic cancer also exerts its effect on pancreatic beta cells, reducing insulin secretion, affecting glucose uptake and increasing insulin resistance. We present a case of pancreatic adenocarcinoma with severe insulin resistance and uncontrolled diabetes which reversed after tumor removal. Clinical Description: 79 year old male patient with no prior diagnosis of diabetes, history of hypertension, atrial fibrillation, cerebrovascular accident got admitted to the hospital with painless jaundice, dark colored urine and pruritus for a month. He also endorsed polyuria, polydipsia and weight loss for 2 months. He underwent Magnetic Resonance Cholangiopancreatography and was diagnosed with a 2.8 cm pancreatic head mass, consistent with adenocarcinoma along with intraductal papillary mucinous neoplasm. He was diagnosed with new onset of diabetes, A1c 12.6% during that hospitalization. He weighed about 75 kg and height 170cm (BMI 26.6). Labs showed normal renal function, deranged liver enzymes with direct hyperbilirubinemia, elevated transaminases and alkaline phosphatase. C-peptide level was 1.2 ng/ml for a blood glucose of 197 mg/dl. He was discharged on once daily insulin Glargine 25 units and mealtime insulin Lispro 10 units three times a day (TID) requiring 0.7 units/kg. During follow-up, his insulin requirement started to increase despite proper insulin injection technique and medication compliance. He required glargine 150 units/day and U500 insulin 50 units TID requiring about 4 units/kg. He underwent Whipple’s procedure, partial pancreas resection after a month of his diagnosis. Patient was started on clear liquid diet and his blood glucose started to get better on post-op day 1 with just correctional insulin. He was discharged on Repaglinide 0.5mg TID with each meal and all his insulin was discontinued. His blood glucose was in range of 80 to 160 mg/dl with Repaglinide during clinical follow-up with regular diabetic diet. His severe insulin resistance got reversed after the resection of pancreatic neoplasm. Conclusion: The pathogenesis of pancreatic cancer associated diabetes has not been studied well. Basic science research found that adrenomedullin, an amionopeptide, is up-regulated in patients with pancreatic cancer and causes insulin resistance in β Cells. Cancer theories also found about metabolic reprogramming and metabolic cross talk happens between pancreatic cancer and peripheral tissue, inhibiting cellular glucose intake and inducing insulin resistance. More research is required to understand these paraneoplastic phenomenon caused by diabetogenic tumor-secreted product in pancreatic cancer associated diabetes.

Type 2 diabetes induced microbiome dysbiosis is associated with therapy resistance in pancreatic adenocarcinoma

Resistance to therapy is one of the major factors that contribute to dismal survival statistics in pancreatic cancer. While there are many tumor intrinsic and tumor microenvironment driven factors that contribute to therapy resistance, whether pre-existing metabolic diseases like type 2 diabetes (T2D) contribute to this has remained understudied. It is well accepted that hyperglycemia associated with type 2 diabetes changes the gut microbiome. Further, hyperglycemia also enriches for a “stem-like” population within the tumor. In the current study, we observed that in a T2D mouse model, the microbiome changed significantly as the hyperglycemia developed in these animals. Our results further showed that, tumors implanted in the T2D mice responded poorly to gemcitabine/paclitaxel (Gem/Pac) standard of care compared to those in the control group. A metabolomic reconstruction of the WGS of the gut microbiota further revealed that an enrichment of bacterial population involved in drug metabolism in the T2D group. Additionally, we also observed an increase in the CD133+ tumor cells population in the T2D model. These observations indicated that in an animal model for T2D, microbial dysbiosis is associated with increased resistance to chemotherapeutic compounds.

Ursolic acid promotes apoptosis, autophagy, and chemosensitivity in gemcitabine-resistant human pancreatic cancer cells.

Gemcitabine (GEM) resistance in pancreatic adenocarcinoma mediated by the receptor for advanced glycation end products (RAGE) has been demonstrated. Therefore, investigating the safety and the potential of new auxiliary methods for pancreatic cancer treatment is urgent. Ursolic acid (UA), a natural pentacyclic triterpenoid found in apple peels, rosemary, and thyme, has been reported to have anticancer capacity. This study aimed to reveal the underlying mechanisms of UA in cell death and drug enhancement, especially in GEM-resistant pancreatic cancer cells. First, GEM-resistant cells (MIA Paca-2GEMR cells) were established by incrementally increasing GEM culture concentrations. UA treatment reduced cell viability through cell cycle arrest and endoplasmic reticulum (ER) stress, resulting in apoptosis and autophagy in a dose-dependent manner in MIA Paca-2 and MIA Paca-2GEMR cells. High RAGE expression in MIA Paca-2GEMR cells was suppressed by UA treatment. Interestingly, knocking down RAGE expression showed similar UA-induced effects in both cell lines. Remarkably, UA had a drug-enhancing effect by decreasing cell viability and increasing cell cytotoxicity when combined with GEM treatment. In conclusions, UA triggered ER stress, subsequently regulating apoptosis- and autophagy-related pathways and increasing GEM chemosensitivity in pancreatic cancer cells by inhibiting the expression of RAGE.

Role of hepatocyte nuclear factor 4 alpha in cell proliferation and gemcitabine resistance in pancreatic adenocarcinoma

BackgroundHepatocyte nuclear factor 4α (HNF4α) is a tissue-specific transcription factor that regulates the expression of numerous genes in hepatocytes and pancreatic β cells. HNF4α has been reported to affect cell proliferation and chemoresistance in several cancers. However, the role of HNF4α in pancreatic adenocarcinoma (PDAC) has not been studied extensively and remains unclear.MethodsBy utilizing immunohistochemical (IHC) staining, we measured the expression of HNF4α in PDAC tissues. By silencing HNF4α in PDAC cell lines, we assessed the impact of HNF4α on pancreatic cancer cell proliferation and gemcitabine sensitivity. We used CCK8 and colony formation assays to examine the effect of HNF4α on cell proliferation. A flow cytometry assay was used to assess cell apoptosis. The expression of gemcitabine-related genes was detected by quantitative real‑time PCR (qRT-PCR) and Western blotting. IHC was utilized to assess the correlation between HNF4α and human equilibrative nucleoside transporter 1 (hENT1) expression in PDAC patients. Chromatin immunoprecipitation (ChIP) and dual‑luciferase reporter assays were used to confirm that hENT1 is a target gene of HNF4α.ResultsIncreased HNF4α expression was detected in PDAC tissues; patients with higher HNF4α expression displayed worse prognosis. To elucidate the function of HNF4α, we examined its role in pancreatic cancer cell proliferation, apoptosis and gemcitabine resistance. In HNF4α-silenced Capan-1 and MiaPaCa-2 cells, we observed decreased cell proliferation and increased sensitivity to gemcitabine compared to those of controls. The mechanism of HNF4α in gemcitabine-related chemosensitivity was then explored. In response to HNF4α silencing, the expression levels of gemcitabine-related proteins, hENT1 and deoxycytidine kinase (dCK) were significantly increased. Additionally, hENT1 was negatively correlated with HNF4α in PDAC tissue samples. Moreover, we identified hENT1 as a downstream target of HNF4α.ConclusionHNF4α is a prognostic marker for overall survival, is required for pancreatic cancer cell proliferation and promotes resistance to gemcitabine by downregulating hENT1. Therefore, targeting HNF4α might reverse gemcitabine resistance and provide novel treatment strategies for PDAC.

Pancreatic Microtumors: A Novel 3D Ex Vivo Testing Platform.

The tumor microenvironment plays a vital role in therapeutic resistance in pancreatic adenocarcinoma. We have created a 3D model to study the tumor microenvironment ex vivo that integrates tumor cells with tumor associated macrophages (TAMs) and cancer associated fibroblasts (CAFs). The microtumor model recreates the complex histology of a primary tumor and can be analyzed histologically or with viability assays for therapeutic testing. Microtumors demonstrate increased resistance to gemcitabine when compared to tumor cells alone in a 3D spheroid, highlighting the contribution of TAMs and CAFs when designing models for therapeutic testing.

Transfer of miRNA in Macrophage-Derived Exosomes Induces Drug Resistance in Pancreatic Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is known for its resistance to gemcitabine, which acts to inhibit cell growth by termination of DNA replication. Tumor-associated macrophages (TAM) were recently shown to contribute to gemcitabine resistance; however, the exact mechanism of this process is still unclear. Using a genetic mouse model of PDAC and electron microscopy analysis, we show that TAM communicate with the tumor microenvironment via secretion of approximately 90 nm vesicles, which are selectively internalized by cancer cells. Transfection of artificial dsDNA (barcode fragment) to murine peritoneal macrophages and injection to mice bearing PDAC tumors revealed a 4-log higher concentration of the barcode fragment in primary tumors and in liver metastasis than in normal tissue. These macrophage-derived exosomes (MDE) significantly decreased the sensitivity of PDAC cells to gemcitabine, in vitro and in vivo This effect was mediated by the transfer of miR-365 in MDE. miR-365 impaired activation of gemcitabine by upregulation of the triphospho-nucleotide pool in cancer cells and the induction of the enzyme cytidine deaminase; the latter inactivates gemcitabine. Adoptive transfer of miR-365 in TAM induced gemcitabine resistance in PDAC-bearing mice, whereas immune transfer of the miR-365 antagonist recovered the sensitivity to gemcitabine. Mice deficient of Rab27 a/b genes, which lack exosomal secretion, responded significantly better to gemcitabine than did wildtype. These results identify MDE as key regulators of gemcitabine resistance in PDAC and demonstrate that blocking miR-365 can potentiate gemcitabine response.Significance: Harnessing macrophage-derived exosomes as conveyers of antagomiRs augments the effect of chemotherapy against cancer, opening new therapeutic options against malignancies where resistance to nucleotide analogs remains an obstacle to overcome. Cancer Res; 78(18); 5287-99. ©2018 AACR.

Novel cell membrane cation transporter associated with platinum therapy resistance in pancreatic adenocarcinoma identified through CRISPR/Cas9 loss-of- function screen

Background: Platinum agents form the backbone of chemotherapy regimens for pancreatic cancer. However, the biologic mechanisms of platinum resistance remain poorly understood. Utilizing a new biologic approach, we performed a loss of function, unbiased, genome-wide screen to identify genes associated with platinum resistance. Methods: The novel CRISPR/Cas9 technology was used to inactivate 20,000 genes in the MiaPaCa2 pancreatic cancer cell line. Each gene was targeted with 6 guide RNAs (sgRNA) delivered by lentiviral transduction. After puromycin selection, 2 replicates of cells were intermittently treated with 5uM cisplatin for 24 hours over 4 weeks. A second set of replicates served as non-treatment control. Finally, genomic DNA was extracted from surviving cells, guide sequences amplified and sequenced. MAGeCK analysis identified significantly enriched guides in the treated cells. Results: Multiple genes were identified that, when lost, confer resistance to platinum agents (p- value <0.05). Amongst known mediators of chemoresistance such as Keap1 and 4 members of the STAGA chromatin modifying complex: USP22, TADA1, TAF5L and TAF6L, the loss of the cation transporter MAGT1 was associated with platinum resistance. sgRNA knock-out of these genes when compared to cisplatin treated non-target controls validated the screening results. Conclusion: Our chemotherapy investigation platform identified a novel role for the membrane magnesium cation transporter, MAGT1, which has been associated with X-linked immunodeficiency, but never implicated in platinum resistance hitherto. Our findings nominate MAGT1 as a candidate biomarker for response to platinum therapy and open new avenues of mechanistic investigation into platinum action, including the cellular mechanisms of platinum drugs uptake and the interplay between intracellular magnesium level and platinum cytotoxicity.

Pancreatic cancer: Intra-tumour bacteria promote gemcitabine resistance in pancreatic adenocarcinoma.

Pancreatic cancer: Intra-tumour bacteria promote gemcitabine resistance in pancreatic adenocarcinoma

Image-based detection and targeting of therapy resistance in pancreatic adenocarcinoma

Pancreatic intraepithelial neoplasia (PanIN) is a premalignant lesion that can progress to pancreatic ductal adenocarcinoma, a highly lethal malignancy marked by its late stage at clinical presentation and profound drug resistance1. The genomic alterations that commonly occur in pancreatic cancer include activation of KRAS2 and inactivation of p53, and SMAD42-4. To date, however, it has been challenging to target these pathways therapeutically; thus the search for other key mediators of pancreatic cancer growth remains an important endeavor. Here we show that the stem cell determinant Musashi (Msi) is a critical element of pancreatic cancer progression in both genetic models and patient derived xenografts. Specifically, we developed Msi reporter mice that allowed image based tracking of stem cell signals within cancers, revealing that Msi expression rises as PanIN progresses to adenocarcinoma, and that Msi-expressing cells are key drivers of pancreatic cancer: they preferentially harbor the capacity to propagate adenocarcinoma, are enriched in circulating tumor cells, and are markedly drug resistant. This population could be effectively targeted by deletion of either Msi1 or Msi2, which led to a striking defect in PanIN progression to adenocarcinoma and an improvement in overall survival. Msi inhibition also blocked the growth of primary patient-derived tumors, suggesting that this signal is required for human disease. To define the translational potential of this work we developed antisense oligonucleotides against Msi; these showed reliable tumor penetration, uptake and target inhibition, and effectively blocked pancreatic cancer growth. Collectively, these studies highlight Msi reporters as a unique tool to identify therapy resistance, and define Msi signaling as a central regulator of pancreatic cancer.

Ipilimumab and gemcitabine for advanced pancreas cancer: A phase Ib study .

e15747Background: Resistance of pancreatic adenocarcinoma (PDA) to therapy remains a challenge. One factor of the barrier is the T-lymphocyte driven inflammatory response seen in PDA. The CTLA-4 T-...

Slug-dependent upregulation of L1CAM is responsible for the increased invasion potential of pancreatic cancer cells following long-term 5-FU treatment.

BackgroundPancreatic adenocarcinoma is a lethal disease with 5-year survival of less than 5%. 5-fluorouracil (5-FU) is a principal first-line therapy, but treatment only extends survival modestly and is seldom curative. Drug resistance and disease recurrence is typical and there is a pressing need to overcome this. To investigate acquired 5-FU resistance in pancreatic adenocarcinoma, we established chemoresistant monoclonal cell lines from the Panc 03.27 cell line by long-term exposure to increasing doses of 5-FU.Results5-FU-resistant cell lines exhibited increased expression of markers associated with multidrug resistance explaining their reduced sensitivity to 5-FU. In addition, 5-FU-resistant cell lines showed alterations typical for an epithelial-to-mesenchymal transition (EMT), including upregulation of mesenchymal markers and increased invasiveness. Microarray analysis revealed the L1CAM pathway as one of the most upregulated pathways in the chemoresistant clones, and a significant upregulation of L1CAM was seen on the RNA and protein level. In pancreatic cancer, expression of L1CAM is associated with a chemoresistant and migratory phenotype. Using esiRNA targeting L1CAM, or by blocking the extracellular part of L1CAM with antibodies, we show that the increased invasiveness observed in the chemoresistant cells functionally depends on L1CAM. Using esiRNA targeting β-catenin and/or Slug, we demonstrate that in the chemoresistant cell lines, L1CAM expression depends on Slug rather than β-catenin.ConclusionOur findings establish Slug-induced L1CAM expression as a mediator of a chemoresistant and migratory phenotype in pancreatic adenocarcinoma cells.

Abstract 1962: Macrophages mediate gemcitabine resistance of pancreatic adenocarcinoma by up-regulating cytidine deaminase

Abstract Resistance to pharmacologic agents used in chemotherapy is common in most human carcinomas, including pancreatic ductal adenocarcinoma (PDA), which is resistant to almost all drugs, including gemcitabine, a nucleoside analog used as first-line treatment. Poor survival rates of PDA patients have, therefore, not changed much over 4 decades. Recent data indicated that tumor-associated macrophages (TAMs), which are abundant in the microenvironment of several tumors, including PDA, secrete pro-tumorigenic factors which contribute to cancer progression and dissemination. In this study, we show for the first time that TAMs can also induce chemoresistance of PDA by reducing gemcitabine-induced apoptosis. Macrophages co-cultured with cancer cells or TAMs conditioned medium significantly reduced apoptosis and activation of the caspase-3 pathway during gemcitabine treatment. In vivo PDA models of mice, which have reduced macrophage recruitment and activation, demonstrated improved response to gemcitabine compared to controls. Similarly, inhibition of monocytes/macrophages trafficking by a CSF1-receptor antagonist GW2580 augmented the effect of gemcitabine in a transgenic mouse PDA model that was resistant to gemcitabine alone. Analysis of multiple proteins involved in gemcitabine delivery and metabolism revealed that TAMs induced upregulation of cytidine deaminase (CDA), the enzyme that metabolizes the drug following its transport into the cell. Decreasing CDA expression by PDA cells blocked the protective effect of TAMs against gemcitabine. These results provide the first evidence of a paracrine effect of TAMs, which mediates acquired resistance of cancer cells to chemotherapy. Modulation of macrophage trafficking or inhibition of CDA may offer a new strategy for augmenting the response of PDA to chemotherapy. Citation Format: Moran Amit, Noam Weizman1, Yoav Binenbaum, Ayelet Shabtay-Orbach, Richard J. Wong, Ziv Gil. Macrophages mediate gemcitabine resistance of pancreatic adenocarcinoma by up-regulating cytidine deaminase. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1962. doi:10.1158/1538-7445.AM2014-1962

Association of ALDH-expressing cancer stem cells with survival in patients with resected pancreatic adenocarcinoma treated with adjuvant chemoradiation.

262 Background: We and others have identified aldehyde dehydrogenase (ALDH) activity as a marker of pancreatic cancer stem cells (or tumor-initiating cells). The presence of cancer stem cells (CSCs) has been associated with decreased survival and treatment resistance in pancreatic adenocarcinoma. We investigate the role of ALDH expression in predicting survival and patterns of disease recurrence in patients treated with chemoradiation (CRT) following pancreatectomy. Methods: Tissue microarrays using surgical specimens from 1998 to 2002 were stained for ALDH1 and scored as ALDH-positive or ALDH-negative by two expert pancreatic pathologists blinded to patient outcomes. Physician documentation and radiology reports were used to determine follow-up information. Time to local failure (TLF), time to distant metastases (TDM), progression-free survival (PFS), and overall survival (OS) were analyzed using SPSS software. Results: Previously we found that ALDH expression was associated with worse OS in a cohort of 269 patients with resected pancreatic adenocarcinoma (Rasheed, JNCI 2009). From this cohort, adjuvant treatment information was available for 87 patients with ALDH-negative tumors (48.6%) and 41 patients with ALDH-positive tumors (45.6%). In patients treated with adjuvant CRT, median overall survival was superior in the ALDH-negative cohort vs. the ALDH-positive cohort, 26.3 months vs. 18.2 months (p=0.011). Further, in patients treated with adjuvant CRT, ALDH-negative patients had statistically greater TLF, TDM, and PFS than their ALDH-positive counterparts (see table). On multivariate analysis, ALDH positive tumor staining (HR 1.94, p=0.004) and tumor grade (HR 1.54, p=0.041) predicted lower OS, and ALDH positive tumor staining (HR 1.83, p=0.008), tumor grade (HR 1.52, p=0.038), and tumor size &gt;3 cm (HR 1.65, p=0.023) predicted decreased PFS. Conclusions: This study suggests that adjuvant CRT improves TLF, TDM, PFS, and OS in patients with localized pancreatic adenocarcinoma not enriched with ALDH-expressing CSCs. Laboratory studies will help elucidate the mechanisms of treatment resistance in ALDH expressing CSCs.

ALDH-Expressing Cancer Stem Cells Are Associated With Inferior Survival in Patients With Resected Pancreatic Adenocarcinoma Treated With Adjuvant Chemoradiation

We and others previously identified aldehyde dehydrogenase (ALDH) activity as a marker of pancreatic cancer stem cells (or tumor-initiating cells). The presence of cancer stem cells (CSCs) have been associated with decreased survival and treatment resistance in pancreatic adenocarcinoma. In this study we investigate the role of ALDH expression in predicting survival and patterns of disease recurrence in patients treated with chemoradiation (CRT) following pancreatectomy.

Abstract LB-349: Tumor associated macrophages mediate gemcitabine resistance of pancreatic adenocarcinoma by upregulating cytidine deaminase.

Abstract Resistance to pharmacologic agents used in chemotherapy is a common phenomenon in most human carcinomas. Pancreatic ductal adenocarcinoma (PDA) is such a tumor, which is resistant to almost all drugs, including gemcitabine, a new nucleoside analog used as first-line treatment. For this reason the poor survival of patients with PDA have not change much during the last 4 decades. Recent data indicated that tumor-associated macrophages (TAMs) which are abundant in the microenvironment of several tumors, including PDA, secrete pro-tumorigenic factors which contribute to cancer progression and dissemination. In this study, we show for the first time that TAMs can also induce chemoresistance of PDA by reducing gemcitabine-induced apoptosis. Macrophages co-cultures with cancer cells or TAMs conditioned medium significantly reduced the levels of cleaved caspase-3 and caspase-3 during gemcitabine treatment. An in vivo PDA model of CCR2-deficient mice, which have reduced macrophage recruitment and activation, demonstrated improved response to gemcitabine compared to wild-types. Similarly, inhibition of monocytes/macrophages trafficking by a CSF1-receptors antagonist augmented the effect of gemcitabine in a transgenic mouse model of PDA that was resistant to gemcitabine alone. Analysis of multiple proteins involved in gemcitabine delivery and metabolism revealed that TAMs induced upregulation of cytidine deaminase (CDA), the enzyme that metabolizes the active form of the drug. Decreasing of CDA expression by PDA cells blocked the protective effect of TAMs against gemcitabine. Taken together, our results identify a paracrine effect of TAMs on PDA cells, which mediates acquire resistance of cancer cells to chemotherapy. Modulation of macrophage trafficking or inhibition of CDA may offer a new strategy for augmenting the response of PDA to chemotherapy. Citation Format: Yoav Binenboum, Noam Weissman, Yakov Kerlin, Ayelet Shabtai, Moran Amit, Ziv Gil. Tumor associated macrophages mediate gemcitabine resistance of pancreatic adenocarcinoma by upregulating cytidine deaminase. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-349. doi:10.1158/1538-7445.AM2013-LB-349 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.