Pancreatic cancer: Current research and future directions. Biochim Biophys Acta Rev Cancer. 2016;1865:123-132. [PMID: 26794394 DOI: 10.1016/j.bbcan.2016.01.001]

A recombinantly tailored β-defensin that displays intensive macropinocytosis-mediated uptake exerting potent efficacy against K-Ras mutant pancreatic cancer

K-Ras mutant pancreatic cancer cells display intensive macropinocytosis, indicating that this process may be exploited in the design of anticancer targeted therapies. In this study, we constructed a macropinocytosis-oriented recombinantly tailored defensin (DF-HSA) which consists of human β-defensin-2 (DF) and human serum albumin (HSA). The macropinocytosis intensity and cytotoxicity of DF-HSA were investigated in K-Ras mutant MIA PaCa-2 cells and wild-type BxPC-3 cells. As found, the DF-HSA uptake in MIA PaCa-2 cells was much higher than that in wild-type BxPC-3 cells. Correspondingly, the cytotoxicity of DF-HSA to MIA PaCa-2 cells was more potent than that to BxPC-3 cells. In addition, the cytotoxicity of DF-HSA was much stronger than that of β-defensin HBD2. DF-HSA suppressed cancer cell proliferation and induced mitochondrial pathway apoptosis. Notably, DF-HSA significantly inhibited the growth of human pancreatic carcinoma MIA PaCa-2 xenograft in athymic mice at well tolerated dose. By in vivo imaging, DF-HSA displayed a prominent accumulation in the tumor. The study indicates that the recombinantly tailored β-defensin can intensively enter into the K-Ras mutant pancreatic cancer cells through macropinocytosis-mediated process and exert potent therapeutic efficacy against the pancreatic carcinoma xenograft. The novel format of β-defensin may play an active role in macropinocytosis-mediated targeting therapy.

Design and Synthesis of Novel Reactive Oxygen Species Inducers for the Treatment of Pancreatic Ductal Adenocarcinoma

Altering redox homeostasis provides distinctive therapeutic opportunities for the treatment of pancreatic cancer. Quinazolinediones (QDs) are novel redox modulators that we previously showed to induce potent growth inhibition in pancreatic ductal adenocarcinoma (PDAC) cell lines. Our lead optimization campaign yielded QD325 as the most potent redox modulator candidate inducing substantial reactive oxygen species (ROS) in PDAC cells. Nascent RNA sequencing following treatments with the QD compounds revealed induction of stress responses in nucleus, endoplasmic reticulum, and mitochondria of pancreatic cancer cells. Furthermore, the QD compounds induced Nrf2-mediated oxidative stress and unfolded protein responses as demonstrated by dose-dependent increases in RNA synthesis of representative genes such as NQO1, HMOX1, DDIT3, and HSPA5. At higher concentrations, the QDs blocked mitochondrial function by inhibiting mtDNA transcription and downregulating the mtDNA-encoded OXPHOS enzymes. Importantly, treatments with QD325 were well tolerated in vivo and significantly delayed tumor growth in mice. Our study supports the development of QD325 as a new therapeutic in the treatment of PDAC.

Downregulation of miR‑29b targets DNMT3b to suppress cellular apoptosis and enhance proliferation in pancreatic cancer

As one of the most aggressive types of tumor, pancreatic cancer is a principal cause of tumor‑associated mortality. Negative associations between microRNA‑29 (miR‑29) and DNA methyltransferases (DNMT) 3a and 3b have been demonstrated to be associated with the carcinogenesis of a number of types of cancer; however, this has not been completely elucidated in pancreatic cancer. In the present study, pancreatic cancer tissues (n=15) and corresponding paracancerous tissues (n=15) were obtained and the results of reverse transcription‑quantitative polymerase chain reaction analysis indicated decreased expression of miR‑29b and enhanced mRNA expression of DNMT3b in pancreatic cancer tissues, compared with the corresponding paracancerous tissues. Increased protein expression of DNMT3b was demonstrated by western blotting and immunohistochemistry. In addition, the negative association between miR‑29b and DNMT3b was noted in pancreatic cancer tissues, and luciferase reporter assays confirmed that miR‑29b was able to directly target DNMT3b in vitro. Notably, miR‑29b overexpression was able to decrease cell viability and to promote the apoptosis by targeting DNMT3b, and the knockdown of DNMT3b exhibited consistent results in vitro and in vivo. The results of the present study suggested that miR‑29b, as a tumor suppressor, may be a novel target for the development of treatments for pancreatic cancer.

The Role of Platelet-Derived ADP and ATP in Promoting Pancreatic Cancer Cell Survival and Gemcitabine Resistance

Platelets have been demonstrated to be vital in cancer epithelial-mesenchymal transition (EMT), an important step in metastasis. Markers of EMT are associated with chemotherapy resistance. However, the association between the development of chemoresistance, EMT, and the contribution of platelets to the process, is still unclear. Here we report that platelets regulate the expression of (1) human equilibrative nucleoside transporter 1 (hENT1) and (2) cytidine deaminase (CDD), markers of gemcitabine resistance in pancreatic cancer. Human ENT1 (hENT1) is known to enable cellular uptake of gemcitabine while CDD deactivates gemcitabine. Knockdown experiments demonstrate that Slug, a mesenchymal transcriptional factor known to be upregulated during EMT, regulates the expression of hENT1 and CDD. Furthermore, we demonstrate that platelet-derived ADP and ATP regulate Slug and CDD expression in pancreatic cancer cells. Finally, we demonstrate that pancreatic cancer cells express the purinergic receptor P2Y₁₂, an ADP receptor found mainly on platelets. Thus ticagrelor, a P2Y₁₂ inhibitor, was used to examine the potential therapeutic effect of an ADP receptor antagonist on cancer cells. Our data indicate that ticagrelor negated the survival signals initiated in cancer cells by platelet-derived ADP and ATP. In conclusion, our results demonstrate a novel role of platelets in modulating chemoresistance in pancreatic cancer. Moreover, we propose ADP/ATP receptors as additional potential drug targets for treatment of pancreatic cancer.

Opioid Tripeptides Hybridized with trans-1-Cinnamylpiperazine as Proliferation Inhibitors of Pancreatic Cancer Cells in Two- and Three-Dimensional in vitro Models

According to the World Health Organization, the mortality rate among patients with pancreatic cancer will increase in the upcoming years. Gemcitabine is the first choice for treatment of pancreatic malignancy, but increasing resistance to this drug is decreasing its overall efficacy. Studies on new therapies that target metabolic pathways, growth factor inhibitors, and tumor stroma or tumor stem cells are currently underway in many research groups. Herein we report the bioactive properties (cytotoxicity and hemolytic activity) of synthetic peptidomimetics containing an opioid tripeptide fragment (Tyr-R¹ -R² -; where R¹ is d-Ala or d-Thr, and R² is Phe or Trp) hybridized with trans-1-cinnamylpiperazine. These compounds are stable in plasma up to 96 h and exhibit low hemotoxicity and good inhibitory effects on cancer cell growth in two- and three-dimensional in vitro models of pancreatic cancer.

Plasma exosome miR-196a and miR-1246 are potential indicators of localized pancreatic cancer

Patients with localized pancreatic cancer (stage I and stage IIA) have a much higher survival rate than those presenting at later stages, yet early detection remains a challenge to this malignancy. The aim of this study was to evaluate whether exosome miRNA signatures are indicative of localized pancreatic cancer. Exosomes were collected from the conditioned media of pancreatic cancer cell lines and plasma samples of localized pancreatic cancer patients (Stage I-IIA, n=15), and healthy subjects (n=15). Cellular and exosome miRNAs from pancreatic cancer cell lines were profiled by next-generation small RNA sequencing. Plasma exosome miRNA expression was analyzed by qRT-PCR. We found that certain miRNAs, such as miR-196a and miR-1246, are highly enriched in pancreatic cancer exosomes. Consistently, plasma exosome miR-196a and miR-1246 levels were significantly elevated in pancreatic cancer patients as compared to healthy subjects. An analysis of the cancer subtypes indicated that plasma exosome miR-196a is a better indicator of pancreatic ductal adenocarcinoma (PDAC), whereas plasma exosome miR-1246 is significantly elevated in patients with intraductal papillary mucinous neoplasms (IPMN). In contrast, there were no differences in the plasma exosome miR-196a and miR-1246 levels between patients with pancreatic neuroendocrine tumors (NET) and healthy subjects. In conclusion, we demonstrate that certain miRNA species, such as miR-196a and miR-1246, are highly enriched in pancreatic cancer exosomes and elevated in plasma exosomes of patients with localized pancreatic cancer.

Pancreatic Ductal Adenocarcinoma: Current and Evolving Therapies

Pancreatic ductal adenocarcinoma (PDAC), which constitutes 90% of pancreatic cancers, is the fourth leading cause of cancer-related deaths in the world. Due to the broad heterogeneity of genetic mutations and dense stromal environment, PDAC belongs to one of the most chemoresistant cancers. Most of the available treatments are palliative, with the objective of relieving disease-related symptoms and prolonging survival. Currently, available therapeutic options are surgery, radiation, chemotherapy, immunotherapy, and use of targeted drugs. However, thus far, therapies targeting cancer-associated molecular pathways have not given satisfactory results; this is due in part to the rapid upregulation of compensatory alternative pathways as well as dense desmoplastic reaction. In this review, we summarize currently available therapies and clinical trials, directed towards a plethora of pathways and components dysregulated during PDAC carcinogenesis. Emerging trends towards targeted therapies as the most promising approach will also be discussed.

Comparison of endoscopic ultrasound, computed tomography and magnetic resonance imaging in assessment of detailed structures of pancreatic cystic neoplasms

AIM

To evaluate the advantages of endoscopic ultrasound (EUS) in the assessment of detailed structures of pancreatic cystic neoplasms (PCNs) compared to computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS

All patients with indeterminate PCNs underwent CT, MRI, and EUS. The detailed information, including size, number, the presence of a papilla/nodule, the presence of a septum, and the morphology of the pancreatic duct of PCNs were compared among the three imaging modalities. The size of each PCN was determined using the largest diameter measured. A cyst consisting of several small cysts was referred to as a mother-daughter cyst. Disagreement among the three imaging modalities regarding the total number of mother cysts resulted in the assumption that the correct number was the one in which the majority of imaging modalities indicated.

RESULTS

A total of 52 females and 16 males were evaluated. The median size of the cysts was 42.5 mm by EUS, 42.0 mm by CT and 38.0 mm by MRI; there was no significant difference in size as assessed among the three imaging techniques. The diagnostic sensitivity and ability of EUS to classify PCNs were 98.5% (67/68) and 92.6% (63/68), respectively. These percentages were higher than those of CT (73.1%, P < 0.001; 17.1%, P < 0.001) and MRI (81.3%, P = 0.001; 20.3%, P < 0.001). EUS was also able to better assess the number of daughter cysts in mother cysts than CT (P = 0.003); however, there was no significant difference between EUS and MRI in assessing mother-daughter cysts (P = 0.254). The papilla/nodule detection rate by EUS was 35.3% (24/68), much higher than those by CT (5.8%, 3/52) and MRI (6.3%, 4/64). The detection rate of the septum by EUS was 60.3% (41/68), which was higher than those by CT (34.6%, 18/52) and by MRI (46.9%, 30/64); the difference between EUS and CT was significant (P = 0.02). The rate of visualizing the pancreatic duct using EUS was 100%, whereas using CT and MRI it was less than 10%.

CONCLUSION

EUS helps visualize the detailed structures of PCNs and has many advantages over CT and MRI. EUS is valuable in the diagnosis and assessment of PCNs.

High toll-like receptor (TLR) 9 expression is associated with better prognosis in surgically treated pancreatic cancer patients

Pancreatic cancer remains one of the deadliest malignancies in the world. Inflammatory response and tumor environment are thought to play a major role in its pathogenesis. Knowledge on TLR expression and impact on patient survival in pancreatic cancer is limited. The study's aim was to clarify the role of different TLRs in pancreatic cancer. TLR2, TLR4, and TLR9 expression was investigated in 65 surgically resected pancreatic ductal adenocarcinoma specimens by immunohistochemistry. The association between TLR expression, clinical parameters, and local inflammatory response to the tumor was assessed using chi-square test. Relation between patient survival and TLR expression was calculated with multivariable Cox regression, adjusted for age, sex, and tumor stage. We found TLR2, TLR4, and TLR9 to be expressed in pancreatic cancer. There was no association between TLR expression and tumor stage, tumor size, lymph node metastasis, or tumor necrosis. Contrary to our initial hypothesis, high cytoplasmic TLR9 expression was associated with longer patient survival, and multivariate analysis identified low TLR9 expression as an independent risk factor for cancer-specific death (HR 3.090, 95% CI 1.673-5.706). The results suggest that high TLR9 expression in pancreatic ductal adenocarcinoma indicates improved prognosis. The prognostic effect of TLR9 might be associated with bacterial exposure, but this needs further evidence.

Oncologic Photodynamic Therapy: Basic Principles, Current Clinical Status and Future Directions

Photodynamic therapy (PDT) is a clinically approved cancer therapy, based on a photochemical reaction between a light activatable molecule or photosensitizer, light, and molecular oxygen. When these three harmless components are present together, reactive oxygen species are formed. These can directly damage cells and/or vasculature, and induce inflammatory and immune responses. PDT is a two-stage procedure, which starts with photosensitizer administration followed by a locally directed light exposure, with the aim of confined tumor destruction. Since its regulatory approval, over 30 years ago, PDT has been the subject of numerous studies and has proven to be an effective form of cancer therapy. This review provides an overview of the clinical trials conducted over the last 10 years, illustrating how PDT is applied in the clinic today. Furthermore, examples from ongoing clinical trials and the most recent preclinical studies are presented, to show the directions, in which PDT is headed, in the near and distant future. Despite the clinical success reported, PDT is still currently underutilized in the clinic. We also discuss the factors that hamper the exploration of this effective therapy and what should be changed to render it a more effective and more widely available option for patients.

Targeting reactive oxygen species in development and progression of pancreatic cancer

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDA) is characterized by expression of oncogenic KRas which drives all aspects of tumorigenesis. Oncogenic KRas induces the formation of reactive oxygen species (ROS) which have been implicated in initiation and progression of PDA. To facilitate tumor promoting levels and to avoid oncogene-induced senescence or cytotoxicity, ROS homeostasis in PDA cells is balanced by additional up-regulation of antioxidant systems. Areas covered: We examine the sources of ROS in PDA, the mechanisms by which ROS homeostasis is maintained, and the biological consequences of ROS in PDA. Additionally, we discuss the potential mechanisms for targeting ROS homoeostasis as a point of therapeutic intervention. An extensive review of the relevant literature as it relates to the topic was conducted using PubMed. Expert commentary: Even though oncogenic mutations in the KRAS gene have been detected in over 95% of human pancreatic adenocarcinoma, targeting its gene product, KRas, has been difficult. The dependency of PDA cells on balancing ROS homeostasis could be an angle for new prevention or treatment strategies. These include use of antioxidants to prevent formation or progression of precancerous lesions, or methods to increase ROS in tumor cells to toxic levels.

Application of glycoscience to the early detection of pancreatic cancer

The prognosis of pancreatic cancer is extremely poor compared to other cancers. One of the reasons for this is the difficulty of early diagnosis. Surveillance using cancer biomarkers and image diagnosis can enable early detection and has improved the prognosis of hepatocellular carcinoma in Japan. However, it is very difficult to detect pancreatic cancer at an early stage using cancer biomarkers and image diagnosis alone. Fucosylation is one of the most important types of glycosylation involved in cancer and inflammation. We have developed a novel glycocancer biomarker, fucosylated haptoglobin (Fuc-Hpt), and have investigated its usefulness for the diagnosis of pancreatic cancer over approximately 10 years. Recently, we also found that most pancreatic tissues surrounding pancreatic cancer exhibit chronic pancreatitis with fibrosis and/or fatty degeneration. Certain forms of chronic pancreatitis might indicate high risk for the development of pancreatic cancer. In this review, we provide a historical summary of our research on Fuc-Hpt as a cancer biomarker, and discuss a potential early detection system for pancreatic cancer.

Profile of MMP and TIMP Expression in Human Pancreatic Stellate Cells: Regulation by IL-1α and TGFβ and Implications for Migration of Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma is characterized by a prominent fibroinflammatory stroma with both tumor-promoting and tumor-suppressive functions. The pancreatic stellate cell (PSC) is the major cellular stromal component and the main producer of extracellular matrix proteins, including collagens, which are degraded by metalloproteinases (MMPs). PSCs interact with cancer cells through various factors, including transforming growth factor (TGF)β and interleukin (IL)-1α. The role of TGFβ in the dual nature of tumor stroma, i.e., protumorigenic or tumor suppressive, is not clear. We aimed to investigate the roles of TGFβ and IL-1α in the regulation of MMP profiles in PSCs and the subsequent effects on cancer cell migration. Human PSCs isolated from surgically resected specimens were cultured in the presence of pancreatic cancer cell lines, as well as IL-1α or TGFβ. MMP production and activities in PSCs were quantified by gene array transcripts, mRNA measurements, fluorescence resonance energy transfer-based activity assay, and zymography. PSC-conditioned media and pancreatic cancer cells were included in a collagen matrix cell migration model. We found that production of IL-1α by pancreatic cancer cells induced alterations in MMP and tissue inhibitors of matrix metalloproteinase (TIMP) profiles and activities in PSCs, upregulated expression and activation of MMP1 and MMP3, and enhanced migration of pancreatic cancer cells in the collagen matrix model. TGFβ counteracted the effects of IL-1α on PSCs, reestablished PSC MMP and TIMP profiles and activities, and inhibited migration of cancer cells. This suggests that tumor TGFβ has a role as a suppressor of stromal promotion of tumor progression through alterations in PSC MMP profiles with subsequent inhibition of pancreatic cancer cell migration.

Modelling of pancreatic ductal adenocarcinoma in vitro with three-dimensional microstructured hydrogels

Development of a novelin vitro3D model of pancreas cancer based on microstructured polyelectrolyte complex (mPEC) hydrogel.