Deciphering the cellular source of tumor relapse identifies CD44 as a major therapeutic target in pancreatic adenocarcinoma

An IL-1β-driven neutrophil-stromal cell axis fosters a BAFF-rich protumor microenvironment in individuals with multiple myeloma

Human bone marrow permanently harbors high numbers of neutrophils, and a tumor-supportive bias of these cells could significantly impact bone marrow-confined malignancies. In individuals with multiple myeloma, the bone marrow is characterized by inflammatory stromal cells with the potential to influence neutrophils. We investigated myeloma-associated alterations in human marrow neutrophils and the impact of stromal inflammation on neutrophil function. Mature neutrophils in myeloma marrow are activated and tumor supportive and transcribe increased levels of IL1B and myeloma cell survival factor TNFSF13B (BAFF). Interactions with inflammatory stromal cells induce neutrophil activation, including BAFF secretion, in a STAT3-dependent manner, and once activated, neutrophils gain the ability to reciprocally induce stromal activation. After first-line myeloid-depleting antimyeloma treatment, human bone marrow retains residual stromal inflammation, and newly formed neutrophils are reactivated. Combined, we identify a neutrophil-stromal cell feed-forward loop driving tumor-supportive inflammation that persists after treatment and warrants novel strategies to target both stromal and immune microenvironments in multiple myeloma.

Therapeutic Monoclonal Antibodies against Cancer: Present and Future

A series of monoclonal antibodies with therapeutic potential against cancer have been generated and developed. Ninety-one are currently used in the clinics, either alone or in combination with chemotherapeutic agents or other antibodies, including immune checkpoint antibodies. These advances helped to coin the term personalized medicine or precision medicine. However, it seems evident that in addition to the current work on the analysis of mechanisms to overcome drug resistance, the use of different classes of antibodies (IgA, IgE, or IgM) instead of IgG, the engineering of the Ig molecules to increase their half-life, the acquisition of additional effector functions, or the advantages associated with the use of agonistic antibodies, to allow a broad prospective usage of precision medicine successfully, a strategy change is required. Here, we discuss our view on how these strategic changes should be implemented and consider their pros and cons using therapeutic antibodies against cancer as a model. The same strategy can be applied to therapeutic antibodies against other diseases, such as infectious or autoimmune diseases.

Oncostatin-M and OSM-Receptor Feed-Forward Activation of MAPK Induces Separable Stem-like and Mesenchymal Programs

Patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) frequently present with advanced metastatic disease and exhibit a poor response to therapy, resulting in poor outcomes. The tumor microenvironment cytokine Oncostatin-M (OSM) initiates PDAC plasticity, inducing the reprogramming to a stem-like/mesenchymal state, which enhances metastasis and therapy resistance. Using a panel of PDAC cells driven through epithelial-mesenchymal transition (EMT) by OSM or the transcription factors ZEB1 or SNAI1, we find that OSM uniquely induces tumor initiation and gemcitabine resistance independently of its ability to induce a CD44HI/mesenchymal phenotype. In contrast, while ZEB1 and SNAI1 induce a CD44HI/mesenchymal phenotype and migration comparable with OSM, they are unable to promote tumor initiation or robust gemcitabine resistance. Transcriptomic analysis identified that OSM-mediated stemness requires MAPK activation and sustained, feed-forward transcription of OSMR. MEK and ERK inhibitors prevented OSM-driven transcription of select target genes and stem-like/mesenchymal reprogramming, resulting in reduced tumor growth and resensitization to gemcitabine. We propose that the unique properties of OSMR, which hyperactivates MAPK signaling when compared with other IL6 family receptors, make it an attractive therapeutic target, and that disrupting the OSM-OSMR-MAPK feed-forward loop may be a novel way to therapeutically target the stem-like behaviors common to aggressive PDAC.

IMPLICATIONS

Small-molecule MAPK inhibitors may effectively target the OSM/OSMR-axis that leads to EMT and tumor initiating properties that promote aggressive PDAC.

Simultaneous targeting of PD-1 and IL-2Rβγ with radiation therapy inhibits pancreatic cancer growth and metastasis

In pancreatic ductal adenocarcinoma (PDAC) patients, we show that response to radiation therapy (RT) is characterized by increased IL-2Rβ and IL-2Rγ along with decreased IL-2Rα expression. The bispecific PD1-IL2v is a PD-1-targeted IL-2 variant (IL-2v) immunocytokine with engineered IL-2 cis targeted to PD-1 and abolished IL-2Rα binding, which enhances tumor-antigen-specific T cell activation while reducing regulatory T cell (Treg) suppression. Using PD1-IL2v in orthotopic PDAC KPC-driven tumor models, we show marked improvement in local and metastatic survival, along with a profound increase in tumor-infiltrating CD8+ T cell subsets with a transcriptionally and metabolically active phenotype and preferential activation of antigen-specific CD8+ T cells. In combination with single-dose RT, PD1-IL2v treatment results in a robust, durable expansion of polyfunctional CD8+ T cells, T cell stemness, tumor-specific memory immune response, natural killer (NK) cell activation, and decreased Tregs. These data show that PD1-IL2v leads to profound local and distant response in PDAC.

Patient-specific modeling of stroma-mediated chemoresistance of pancreatic cancer using a three-dimensional organoid-fibroblast co-culture system

BACKGROUND

Cancer-associated fibroblasts (CAFs) are considered to play a fundamental role in pancreatic ductal adenocarcinoma (PDAC) progression and chemoresistance. Patient-derived organoids have demonstrated great potential as tumor avatars for drug response prediction in PDAC, yet they disregard the influence of stromal components on chemosensitivity.

METHODS

We established direct three-dimensional (3D) co-cultures of primary PDAC organoids and patient-matched CAFs to investigate the effect of the fibroblastic compartment on sensitivity to gemcitabine, 5-fluorouracil and paclitaxel treatments using an image-based drug assay. Single-cell RNA sequencing was performed for three organoid/CAF pairs in mono- and co-culture to uncover transcriptional changes induced by tumor-stroma interaction.

RESULTS

Upon co-culture with CAFs, we observed increased proliferation and reduced chemotherapy-induced cell death of PDAC organoids. Single-cell RNA sequencing data evidenced induction of a pro-inflammatory phenotype in CAFs in co-cultures. Organoids showed increased expression of genes associated with epithelial-to-mesenchymal transition (EMT) in co-cultures and several potential receptor-ligand interactions related to EMT were identified, supporting a key role of CAF-driven induction of EMT in PDAC chemoresistance.

CONCLUSIONS

Our results demonstrate the potential of personalized PDAC co-cultures models not only for drug response profiling but also for unraveling the molecular mechanisms involved in the chemoresistance-supporting role of the tumor stroma.

Pancreatic Tumor Microenvironment Factor Promotes Cancer Stemness via SPP1-CD44 Axis

BACKGROUND & AIMS

Tumor-microenvironment factors and cancer stem cells (CSCs) play a critical role in the aggressiveness of pancreatic cancer (PC). However, the degree to which tumor-microenvironment factors promote stemness remains unexplored. Here, we examined whether cancer-associated fibroblasts (CAFs) promote CSC features in PC.

METHODS

PC cells were treated long-term (30, 60, and 90 days) with conditioned media (CM)-derived from normal human fibroblasts (NFs) and CAFs. The stemness features of tumorsphere formation and stemness populations, along with CSCs markers, were analyzed using 2-dimensional and 3-dimensional sodium alginate bead-based co-culture models. Immunohistochemistry and immunofluorescence staining were performed for CSCs and fibroblast markers in autochthonous KrasG12D/+; Trp53R172H/+; Pdx1-Cre mice and human pancreatic tumors. Polymerase chain reaction array and gene knockdown were performed to identify the mechanism of stemness enrichment.

RESULTS

Long-term treatment of PC cells with CAF-CM enriched stemness, as indicated by significantly higher CD44+, ALDH+, and AF+ populations in PC cells. Increased tumorsphere formation and elevated CSC, self-renewal, and drug-resistance markers in CAF-CM-treated PC cells were observed. In addition, CAFs co-cultured with PC cells in the 3-dimensional model showed a substantial increase in stemness features. CD44 and α-smooth muscle actin were positively correlated and their expressions progressively increased from the early to late stages of KrasG12D/+; Trp53R172H/+; Pdx1-Cre mouse and human pancreatic tumors. Osteopontin/secreted phosphoprotein 1 was identified as the top differentially overexpressed gene in CAF-CM-treated PC cells and knockdown of osteopontin/secreted phosphoprotein 1 significantly reduced stemness characteristics in CAF-CM-treated PC cells.

CONCLUSIONS

Our data uncovered novel insight into the interplay between CAF and enrichment of stemness population through the osteopontin/secreted phosphoprotein 1-CD44 axis in PC.

Fraction B From Catfish Epidermal Secretions Kills Pancreatic Cancer Cells, Inhibits CD44 Expression and Stemness, and Alters Cancer Cell Metabolism

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer related death in western countries. The successful treatment of PDAC remains limited. We investigated the effect of Fraction B, which is a fraction purified from catfish (Arius bilineatus, Val.) skin secretions containing proteins and lipids, on PDAC biology both in-vivo and in-vitro. We report here that Fraction B potently suppressed the proliferation of both human and mouse pancreatic cancer cells in vitro and significantly reduced the growth of their relevant xenograft (Panc02) and orthotopic tumors (human Panc-1 cells) (p < 0.05). The Reverse Phase Protein Array (RPPA) data obtained from the tumor tissues derived from orthotopic tumor bearing mice treated with Fraction B showed that Fraction B altered the cancer stem cells related pathways and regulated glucose and glutamine metabolism. The down-regulation of the cancer stem cell marker CD44 expression was further confirmed in Panc-1 cells. CBC and blood chemistry analyses showed no systemic toxicity in Fraction B treated Panc-1 tumor bearing mice compared to that of control group. Our data support that Fraction B is a potential candidate for PDAC treatment.

The multiple myeloma microenvironment is defined by an inflammatory stromal cell landscape

Progression and persistence of malignancies are influenced by the local tumor microenvironment, and future eradication of currently incurable tumors will, in part, hinge on our understanding of malignant cell biology in the context of their nourishing surroundings. Here, we generated paired single-cell transcriptomic datasets of tumor cells and the bone marrow immune and stromal microenvironment in multiple myeloma. These analyses identified myeloma-specific inflammatory mesenchymal stromal cells, which spatially colocalized with tumor cells and immune cells and transcribed genes involved in tumor survival and immune modulation. Inflammatory stromal cell signatures were driven by stimulation with proinflammatory cytokines, and analyses of immune cell subsets suggested interferon-responsive effector T cell and CD8⁺ stem cell memory T cell populations as potential sources of stromal cell-activating cytokines. Tracking stromal inflammation in individuals over time revealed that successful antitumor induction therapy is unable to revert bone marrow inflammation, predicting a role for mesenchymal stromal cells in disease persistence.

Crosstalk between MMP-13, CD44, and TWIST1 and its role in regulation of EMT in patients with esophageal squamous cell carcinoma

Matrix metalloproteinases (MMPs) play key roles in epithelial-mesenchymal transition (EMT) for the development of cancer cell invasion and metastasis. MMP-13 is an extracellular matrix (ECM)-degrading enzyme that plays crucial roles in angiogenesis, cell cycle regulation, niche maintenance, and transforming squamous epithelial cells in various tissues. CD44, a transmembrane glycoprotein expressed on esophageal tumor cells, is required for EMT induction and invasion in esophageal squamous cell carcinoma (ESCC). The transcription factor TWIST1, as EMT and stemness marker, regulates MMPs expression and is identified as the downstream target of CD44. In this study, we aimed to investigate the probable interplay between the expression of key genes contributing to ESCC development, including MMP-13, TWIST1, and CD44 with clinical features for introducing novel diagnostic and therapeutic targets in the disease. The gene expression profiling of MMP-13, TWIST1, and CD44 was performed using quantitative real-time PCR in tumor tissues from 50 ESCC patients compared to corresponding margin non-tumoral tissues. Significant overexpression of MMP-13, CD44S, CD44V3, CD44V6, and TWIST1 were observed in 74%, 36%, 44%, 44%, and 52% of ESCC tumor samples, respectively. Overexpression of MMP-13 was associated with stage of tumor progression, metastasis, and tumor location (P < 0.05). There was a significant correlation between TWIST1 overexpression and grade (P < 0.05). Furthermore, overexpression of CD44 variants was associated with stage of tumor progression, grade, tumor invasion, and location (P < 0.05). The results indicated the significant correlation between concomitant expression of MMP-13/TWIST1, TWIST1/CD44, and CD44/MMP-13 with each other in a variety of clinicopathological traits, including depth of tumor invasion, tumor location, stage of tumor, and lymph node involvement in ESCC tissue samples (P < 0.05). Collectively, our results indicate that the TWIST1-CD44-MMP-13 axis is involved in tumor aggressiveness, proposing these genes as regulators of EMT, diagnostic markers, and therapeutic targets in ESCC.

Xenografts Derived From Patients' Ascites Recapitulate the Gemcitabine Resistance Observed in Pancreatic Cancer Patients

OBJECTIVES

Most patient-derived pancreatic ductal adenocarcinoma (PDAC) xenografts have been established from surgical specimens of patients who have not received chemotherapy. However, xenografts have rarely been established from chemotherapy-resistant, advanced PDACs, because such cases are usually inoperable. The purpose of this study is to establish patient-derived xenografts using PDAC cells refractory to chemotherapy.

METHODS

Clinical PDAC cells obtained from ascites of patients who had received continuous chemotherapy were implanted into the flanks of immunocompromised mice. Growth and histological features of the xenografts with and without gemcitabine treatment were then analyzed.

RESULTS

Ascites-derived PDAC cells were successfully expanded through serial xenograft passage without changes in histological appearance. While treatment with gemcitabine substantially inhibited the growth of all PDAC xenografts tested, the tumor volume gradually increased, and the tumors showed marked regrowth even under continued gemcitabine treatment. These findings are consistent with the actual clinical course of the corresponding patients for each xenograft.

CONCLUSIONS

Ascites-derived xenograft models represent a valuable experimental system for testing the efficacy of currently available therapeutic compounds on chemotherapy-resistant PDAC cells and for elucidation of the mechanisms underlying chemotherapy resistance.

Novel prognostic markers within the CD44-stromal ligand network in pancreatic cancer

The dense stroma in pancreatic cancer tumours is rich in secreted extracellular matrix proteins and proteoglycans. Secreted hyaluronan, osteopontin and type IV collagen sustain oncogenic signalling by interactions with CD44s and its variant isoform CD44v6 on cancer cell membranes. Although well established in animal and in vitro models, this oncogenic CD44-stromal ligand network is less explored in human cancer. Here, we use a pancreatic cancer tissue microarray from 69 primary tumours and 37 metastatic lymph nodes and demonstrate that high tumour cell expression of CD44s and, surprisingly, low stromal deposition of osteopontin correlate with poor survival independent of established prognostic factors for pancreatic cancer. High stromal expression of hyaluronan was a universal trait of both primary tumours and metastatic lymph nodes. However, hyaluronan species of different molecular mass are known to function differently in pancreatic cancer biology and immunohistochemistry cannot distinguish between them. Using gas-phase electrophoretic molecular mobility analysis, we uncover a shift towards high molecular mass hyaluronan in pancreatic cancer tissue compared to normal pancreas and at a transcriptional level, we find that hyaluronan synthesising HAS2 correlates positively with CD44. The resulting prediction that high molecular mass hyaluronan would then correlate with poor survival in pancreatic cancer was confirmed in serum samples, where we demonstrate that hyaluronan >27 kDa measured before surgery is an independent predictor of postoperative survival. Our findings confirm the prognostic value of CD44 tissue expression and highlight osteopontin tissue expression and serum high molecular mass hyaluronan as novel prognostic markers in pancreatic cancer.

Bitter melon juice exerts its efficacy against pancreatic cancer via targeting both bulk and cancer stem cells

Pancreatic cancer (PanC) is one of the deadliest malignancies worldwide and frontline treatment with gemcitabine becomes eventually ineffective due to increasing PanC resistance, suggesting additional approaches are needed to manage PanC. Recently, we have shown the efficacy of bitter melon juice (BMJ) against PanC cells, including those resistant to gemcitabine. As cancer stem cells (CSCs) are actively involved in PanC initiation, progression, relapse and drug-resistance, here we assessed BMJ ability in targeting pancreatic cancer-associated cancer stem cells (PanC-CSCs). We found BMJ efficacy against CD44+ /CD24+ /EpCAMhigh enriched PanC-CSCs in spheroid assays; BMJ also increased the sensitivity of gemcitabine-resistant PanC-CSCs. Exogenous addition of BMJ to PanC-CSC generated spheroids (not pre-exposed to BMJ) also significantly reduced spheroid number and size. Mechanistically, BMJ effects were associated with a decrease in the expression of genes and proteins involved in PanC-CSC renewal and proliferation. Specifically, immunofluorescence staining showed that BMJ decreases protein expression/nuclear localization of CSC-associated transcription factors SOX2, OCT4 and NANOG, and CSC marker CD44. Immunohistochemical analysis of MiaPaCa2 xenografts from BMJ treated animals also showed a significant decrease in the levels of CSC-associated transcription factors. Together, these results show BMJ potential in targeting PanC-CSC pool and associated regulatory pathways, suggesting the need for further investigation of its efficacy against PanC growth and progression including gemcitabine-resistant PanC.

CD44 overexpression related to lymph node metastasis and poor prognosis of pancreatic cancer

BACKGROUND

CD44 has recently been reported as a biomarker for pancreatic cancer. However, the predictive value of CD44 in pancreatic cancer remains controversial. Therefore, we performed this meta-analysis to evaluate the association between the expression of CD44 and clinicopathological features, and the outcome of pancreatic cancer patients.

MATERIALS AND METHOD

A comprehensive literature search was performed using PubMed, Embase, and Chinese National Knowledge Infrastructure. The statistical analysis was conducted using Stata software.

RESULTS

A total of nine studies including 583 cases were included in this meta-analysis. The meta-analysis indicated that CD44 overexpression was associated with poor five-year overall survival rate (OR 0.52; 95% CI 0.30, 0.91; P = 0.02), more lymph node invasion (OR 3.14 (positive vs. negative); 95% CI 1.47, 6.73; P = 0.003), more advanced T stage (OR 2.4 (T3,4 vs. T1,2); 95% CI 1.28, 4.52; P = 0.007), and more advanced TNM stage (OR 4.53 (III~IV vs. I~II); 95% CI 1.46, 14.08; P = 0.01). However, CD44 overexpression was not associated with other clinicopathological features, such as tumor size, differentiation, and distance metastasis.

CONCLUSIONS

The current evidence suggests that CD44 is an efficient prognostic factor in pancreatic cancer.

Photodynamic Priming Mitigates Chemotherapeutic Selection Pressures and Improves Drug Delivery

Physiologic barriers to drug delivery and selection for drug resistance limit survival outcomes in cancer patients. In this study, we present preclinical evidence that a subtumoricidal photodynamic priming (PDP) strategy can relieve drug delivery barriers in the tumor microenvironment to safely widen the therapeutic window of a nanoformulated cytotoxic drug. In orthotopic xenograft models of pancreatic cancer, combining PDP with nanoliposomal irinotecan (nal-IRI) prevented tumor relapse, reduced metastasis, and increased both progression-free survival and 1-year disease-free survival. PDP enabled these durable improvements by targeting multiple tumor compartments to (i) increase intratumoral drug accumulation by >10-fold, (ii) increase the duration of drug exposure above a critical therapeutic threshold, and (iii) attenuate surges in CD44 and CXCR4 expression, which mediate chemoresistance often observed after multicycle chemotherapy. Overall, our results offer preclinical proof of concept for the effectiveness of PDP to minimize risks of tumor relapse, progression, and drug resistance and to extend patient survival.Significance: A biophysical priming approach overcomes key treatment barriers, significantly reduces metastases, and prolongs survival in orthotopic models of human pancreatic cancer. Cancer Res; 78(2); 558-71. ©2017 AACR.

TNFα and TGFβ-1 synergistically increase the cancer stem cell properties of MiaPaCa-2 cells

Increased serum concentrations of tumor necrosis factor α (TNFα) and transforming growth factor β-1 (TGFβ-1) in the blood of patients with pancreatic cancer (PC) have previously been demonstrated. In addition, exogenous exposure to these cytokines promotes various cancer cell invasive and cancer stem cell (CSC) phenotypes. However, their importance in pancreatic CSCs remains elusive. In the present study, the effects of TNFα and TGFβ-1 on the human PC cell line MiaPaCa-2 were examined. Using flow cytometry, it was revealed that TNFα and TGFβ-1 synergistically increase cluster of differentiation (CD) 44v6, CD133 and ATP-binding cassette transporter G2 (ABCG2) expressing populations in adherent tumor cell culture conditions. Furthermore, a similar trend was observed in cells pretreated with these cytokines grown in sphere forming culture conditions. Similar to previous studies, TNFα treatment increased the proportion of epidermal growth factor receptor (EGFR) expressing cells in adherent culture, and this data was further supported by the results of the sphere formation assay, in which the subculture with a high proportion of EGFR expressing cells exhibited the most efficient sphere forming ability. However, the proportion of vascular endothelial growth factor receptor 1 (VEGFR1) expressing cells did not increase upon treatment with these cytokines individually or in combination. This data was subsequently supported by the results of the wound healing assay in which cytokine treatment did not increase the migration of cells. The MTT cell proliferation and cytotoxicity assay revealed that TNFα + TGFβ-1 treatment significantly increased cell proliferation and daunorubicin resistance, but not gemcitabine resistance. In conclusion, the data of the current study provide a mechanistic association between TNFα, TGFβ-1 and the CSC properties of MiaPaCa-2 cells. In addition, it suggests that targeting TNFα and TGFβ-1 is beneficial for improving the therapeutic efficacy of treatments for patients with PC.

The FOXO3/PGC-1β signaling axis is essential for cancer stem cell properties of pancreatic ductal adenocarcinoma

In 95% of patients with pancreatic ductal adenocarcinoma, recurrence is observed following chemotherapy. Findings from several studies have indicated that cancer stem cells (CSCs) are resistant to anticancer agents and may be involved in cancer recurrence and metastasis. The CD44 protein is a major CSC marker, and CD44 also plays an indispensable role in the CSC properties in several cancers, including pancreatic cancer; however, no clinical approach exists to inhibit CD44 activity. Here, we have performed knock-in/knockdown experiments, and we demonstrate that the forkhead box O3 (FOXO3)/liver kinase B1 (LKB1)/AMP-activated protein kinase/peroxisome proliferator-activated receptor-γ co-activator-1β (PGC-1β)/pyruvate dehydrogenase-A1 pathway is essential for CD44 expression and CSC properties. We observed that patients exhibiting high pyruvate dehydrogenase-A1 expression have a poor prognosis. Systemic PGC-1β knock-out mice are fertile and viable and do not exhibit an overt phenotype under normal conditions. This suggests that cGMP induction and PGC-1β inhibition represent potential strategies for treating patients with pancreatic ductal adenocarcinoma.

The Aurora-A-Twist1 axis promotes highly aggressive phenotypes in pancreatic carcinoma

We uncovered a crucial role for the Aurora kinase A (AURKA)-Twist1 axis in promoting epithelial-to-mesenchymal transition (EMT) and chemoresistance in pancreatic cancer. Twist1 is the first EMT-specific target of AURKA that was identified using an innovative screen. AURKA phosphorylates Twist1 at three sites, which results in its multifaceted regulation - AURKA inhibits its ubiquitylation, increases its transcriptional activity and favors its homodimerization. Twist1 reciprocates and prevents AURKA degradation, thereby triggering a feedback loop. Ablation of either AURKA or Twist1 completely inhibits EMT, highlighting both proteins as central players in EMT progression. Phosphorylation-dead Twist1 serves as a dominant-negative and fully reverses the EMT phenotype induced by Twist1, underscoring the crucial role of AURKA-mediated phosphorylation in mediating Twist1-induced malignancy. Likewise, Twist1-overexpressing BxPC3 cells formed large tumors in vivo, whereas expression of phosphorylation-dead Twist1 fully abrogated this effect. Furthermore, immunohistochemical analysis of pancreatic cancer specimens revealed a 3-fold higher level of Twist1 compared to that seen in healthy normal tissues. This is the first study that links Twist1 in a feedback loop with its activating kinase, which indicates that concurrent inhibition of AURKA and Twist1 will be synergistic in inhibiting pancreatic tumorigenesis and metastasis.

FOXO3 is essential for CD44 expression in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal types of cancer and the 5-year survival rate is only 5%. Several studies have suggested that cancer stem cells (CSCs) are thought to be involved in recurrence and metastasis and so it is essential to establish an approach targeting CSCs. Here we have demonstrated that cyclic guanosine monophosphate (cGMP) suppressed CD44 expression and the properties of CSCs in PDAC. Microarray analysis suggested that cGMP inhibited Forkhead box O3 (FOXO3), which is known as a tumor suppressor. Surprisingly, our data demonstrated that FOXO3 is essential for CD44 expression and the properties of CSCs. Our data also indicated that patients with high FOXO3 activation signatures had poor prognoses. This evidence suggested that cGMP induction and FOXO3 inhibition could be ideal candidates for pancreatic CSC.

CD44 Expression Level and Isoform Contributes to Pancreatic Cancer Cell Plasticity, Invasiveness, and Response to Therapy

PURPOSE

A subpopulation of pancreatic ductal adenocarcinoma (PDAC) cells is thought to be inherently resistant to chemotherapy or to give rise to tumor cells that become resistant during treatment. Here we determined the role of CD44 expression and its isoforms as a marker and potential target for tumor cells that give rise to invasive and gemcitabine-resistant tumors.

EXPERIMENTAL DESIGN

RT-PCR, Western blotting, and DNA sequencing was used to determine CD44 isoform and expression levels. Flow cytometry was used to sort cells on the basis of their CD44 expression level. CD44 expression was knocked down using shRNA. Tumorigenic properties were determined by clonogenic and Matrigel assays, IHC, tumor growth in vivo using luciferase imaging and by tumor weight.

RESULTS

We identified an invasive cell population that gives rise to gemcitabine-resistant tumors. These cancer cells express a high level of CD44 standard isoform and have an EMT phenotype (CD44s/EMT). In vivo, CD44s/EMT engraft and expand rapidly and give rise to tumors that express high levels of CD44 isoforms that contain multiple exon variants. CD44low-expressing cells show continued sensitivity to gemcitabine in vivo and knockdown of CD44 in CD44s/EMT cells increases sensitivity to gemcitabine and decreases invasiveness.

CONCLUSIONS

PDAC cells expressing high levels of CD44s with a mesenchymal-like phenotype were highly invasive and developed gemcitabine resistance in vivo Thus, initial targeting CD44 or reversing the CD44high phenotype may improve therapeutic response. Clin Cancer Res; 22(22); 5592-604. ©2016 AACR.

Cancer stem cell mediated acquired chemoresistance in head and neck cancer can be abrogated by aldehyde dehydrogenase 1 A1 inhibition

Chemoresistance leading to disease relapse is one of the major challenges to improve outcome in head and neck cancers. Cancer Stem Cells (CSCs) are increasingly being implicated in chemotherapy resistance, this study investigates the correlation between CSC behavior and acquired drug resistance in in vitro cell line models. Cell lines resistant to Cisplatin (Cal-27 CisR, Hep-2 CisR) and 5FU (Cal-27 5FUR) with high Resistance Indices (RI) were generated (RI ≥ 3) by short-term treatment of head and neck squamous cell carcinoma (HNSCC) cell lines with chemotherapeutic drugs (Cisplatin, Docetaxel, 5FU), using a dose-incremental strategy. The cell lines (Cal-27 DoxR, Hep-2 DoxR, Hep-2 5FUR) that showed low RI, nevertheless had a high cross resistance to Cisplatin/5FU (P < 0.05). Cal-27 CisR and DoxR showed 12-14% enrichment of CD44+ cells, while CisR/5FUR showed 4-6% increase in ALDH1A1+ cells as compared to parental cells (P < 0.05). Increased expression of stem cell markers (CD44, CD133, NOTCH1, ALDH1A1, OCT4, SOX2) in these cell lines, correlated with enhanced spheroid/colony formation, migratory potential, and increased in vivo tumor burden (P < 0.05). Inhibition of ALDH1A1 in Cal-27 CisR led to down regulation of the CSC markers, reduction in migratory, self-renewal and tumorigenic potential (P < 0.05) accompanied by an induction of sensitivity to Cisplatin (P < 0.05). Further, ex vivo treatment of explants (n = 4) from HNSCC patients with the inhibitor (NCT-501) in combination with Cisplatin showed a significant decrease in proliferating cells as compared to individual treatment (P = 0.001). This study hence suggests an ALDH1A1-driven, CSC-mediated mechanism in acquired drug resistance of HNSCC, which may have therapeutic implications. © 2016 Wiley Periodicals, Inc.

Heterogeneity of metastatic pancreatic adenocarcinoma: Lung metastasis show better prognosis than liver metastasis-a case control study

The prognosis of metastatic pancreatic ductal adenocarcinoma (PDAC) is grim, with a median overall survival of under 1 year. In our clinical practice, we observed a few cases of isolated lung metastases from PDAC with unusually long outcomes. We compared these cases in a case-control study of lung-only vs. liver-only metastases from PDAC.From our database, we found 37 cases of lung-only metastases and paired them with 37 cases of liver-only metastases by age, tumor location and treatment.The lung-only group differed significantly from the liver-only group with respect to the following parameters: female predominance, more metachronous cases, fewer nodules per patient, and smaller increases in tumor markers. Local invasion parameters (i.e., arterial or venous involvement) were not significantly different. The outcomes were significantly different, with a median overall survival from the occurrence of metastases of 20.8 vs. 9.1 months and a median progression-free survival of 11 vs. 3.5 months.In conclusion, this case-control study seemed to confirm that lung-only PDAC metastases have prognoses different from those of liver-only metastases. A better understanding of the mechanisms underlying these differences will help identify abnormalities associated with tumor aggressiveness.

Role of hyaluronan in pancreatic cancer biology and therapy: Once again in the spotlight

Pancreatic ductal adenocarcinoma (PDAC) remains the most deadly disease worldwide, with the lowest survival rate among all cancer types. Recent evidence suggests that hyaluronan (HA), a major component of ECM, provides a favorable microenvironment for cancer progression. Pancreatic ductal adenocarcinoma is typically characterized by a dense desmoplastic stroma containing a large amount of HA. Accumulation of HA promotes tumor growth in mice and correlates with poor prognosis in patients with PDAC. Because HA is involved in various malignant behaviors of cancer (such as increased cell proliferation, migration, invasion, angiogenesis, and chemoresistance), inhibiting HA synthesis/signaling or depleting HA in tumor stroma could represent a promising therapeutic strategy against PDAC. In this review article, we summarize our current understanding of the role of HA in the progression of PDAC and discuss possible therapeutic approaches targeting HA.

Biomarkers and Targeted Therapy in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) constitutes 90% of pancreatic cancers. PDAC is a complex and devastating disease with only 1%-3% survival rate in five years after the second stage. Treatment of PDAC is complicated due to the tumor microenvironment, changing cell behaviors to the mesenchymal type, altered drug delivery, and drug resistance. Considering that pancreatic cancer shows early invasion and metastasis, critical research is needed to explore different aspects of the disease, such as elaboration of biomarkers, specific signaling pathways, and gene aberration. In this review, we highlight the biomarkers, the fundamental signaling pathways, and their importance in targeted drug delivery for pancreatic cancers.

Targeting CD44 as a novel therapeutic approach for treating pancreatic cancer recurrence

Pancreatic ductal adenocarcinoma (PDAC) is an extraordinarily lethal disease, which, despite a more or less efficient chemotherapeutic treatment, systematically displays a rapid and uncontrolled progression towards a fatal recurrence. Determining which cells give rise to such tumor recurrence is thus crucial before an improved therapeutics outcome can be envisaged for patients with PDAC. In this regard, we recently reported that following a standard chemotherapy for PDAC, a heterogeneous subpopulation of CD44+ cells proliferates and is responsible for tumor recurrence, as shown by almost all recurrent tumor cells becoming CD44+. We designed a strategy to eliminate these cells based on a weekly administration of an anti-CD44 monoclonal antibody to human PDAC-derived xenografts in mice. We demonstrate that xenografts, which were unresponsive to gemcitabine treatment, are however sensitive to this strategy. In conclusion, CD44 represents an efficient therapeutic target in patients with recurrent PDAC.

Cytotoxicity of gemcitabine-loaded thermosensitive liposomes in pancreatic cancer cell lines

Gemcitabine (GEM) is currently the standard option for the treatment of pancreatic cancer but its short half-life and rapid metabolism has caused for new modality for delivery of GEM. The purpose of this study was to formulate GEM loaded PEGylated thermosensitive liposomal nanoparticles (GEM-TSLnps) to increase residence time and deliver high payload of GEM to pancreatic cancer cells using mild hyperthermia (mHT). The GEM-TSLnps were formulated by thin film hydration. The cytotoxic effects of GEM and GEM-TSLnps were evaluated against human pancreatic cancer cell lines. In vitro release of GEM by TSLnps was determined at temperatures from 26°C through to 50°C. Cell viability studies, clonogenic assay, flow cytometry and confocal imaging were performed on pancreatic cancer cell lines using GEM and GEM-TSLnps + mHT. The GEM-TSLnp size was determined to be 216.10 ± 0.57 nm with entrapment efficiency of 41.10 ± 2.0%. GEM release from TSLnps was sharply increased at 42°C (60%) than at 37°C (25%), (p<0.01). In vitro cytotoxicity of GEM-TSLnps + mHT treated pancreatic cancer cell lines was significantly higher than GEM treated. The IC50 values for PANC-1, MiaPaCa-2 and BxPC-3 cells GEM-TSLnps + mHT treated were 1.2 to 3.5 fold-higher than GEM treated. Among the cell lines, GEM-TSLnps + mHT treated PANC-1 and MiaPaCa-2 cells show significantly reduced reproductive viability compared with the GEM treated cells. Flow cytometric and confocal images revealed high Rho-TSLnps cellular uptake. Our findings suggest that GEMTSLnps+ mHT can significantly enhance cytotoxic effect of GEM and could serve as a new chemotherapy modality for delivering GEM.