Exosomes: the key of sophisticated cell–cell communication and targeted metastasis in pancreatic cancer

Pancreatic cancer is one of the most common malignancies. Unfortunately, the lack of effective methods of treatment and diagnosis has led to poor prognosis coupled with a very high mortality rate. So far, the pathogenesis and progression mechanisms of pancreatic cancer have been poorly characterized. Exosomes are small vesicles secreted by most cells, contain lipids, proteins, and nucleic acids, and are involved in diverse functions such as intercellular communications, biological processes, and cell signaling. In pancreatic cancer, exosomes are enriched with multiple signaling molecules that mediate intercellular communication with control of immune suppression, mutual promotion between pancreas stellate cells and pancreatic cancer cells, and reprogramming of normal cells. In addition, exosomes can regulate the pancreatic cancer microenvironment and promote the growth and survival of pancreatic cancer. Exosomes can also build pre-metastatic micro-ecological niches and facilitate the targeting of pancreatic cancer. The ability of exosomes to load cargo and target allows them to be of great clinical value as a biomarker mediator for targeted drugs in pancreatic cancer.

Selenium Induces Pancreatic Cancer Cell Death Alone and in Combination with Gemcitabine

Survival rate for pancreatic cancer remains poor and newer treatments are urgently required. Selenium, an essential trace element, offers protection against several cancer types and has not been explored much against pancreatic cancer specifically in combination with known chemotherapeutic agents. The present study was designed to investigate selenium and Gemcitabine at varying doses alone and in combination in established pancreatic cancer cell lines growing in 2D as well as 3D platforms. Comparison of multi-dimensional synergy of combinations’ (MuSyc) model and highest single agent (HSA) model provided quantitative insights into how much better the combination performed than either compound tested alone in a 2D versus 3D growth of pancreatic cancer cell lines. The outcomes of the study further showed promise in combining selenium and Gemcitabine when evaluated for apoptosis, proliferation, and ENT1 protein expression, specifically in BxPC-3 pancreatic cancer cells in vitro.

CRISPR-Cas9 Screen Identifies DYRK1A as a Target for Radiotherapy Sensitization in Pancreatic Cancer

Although radiation therapy has recently made great advances in cancer treatment, the majority of patients diagnosed with pancreatic cancer (PC) cannot achieve satisfactory outcomes due to intrinsic and acquired radioresistance. Identifying the molecular mechanisms that impair the efficacy of radiotherapy and targeting these pathways are essential to improve the radiation response of PC patients. Our goal is to identify sensitive targets for pancreatic cancer radiotherapy (RT) using the kinome-wide CRISPR-Cas9 loss-of-function screen and enhance the therapeutic effect through the development and application of targeted inhibitors combined with radiotherapy. We transduced pancreatic cancer cells with a protein kinase library; 2D and 3D library cells were irradiated daily with a single dose of up to 2 Gy for 4 weeks for a total of 40 Gy using an X-ray generator. Sufficient DNA was collected for next-generation deep sequencing to identify candidate genes. In this study, we identified several cell cycle checkpoint kinases and DNA damage related kinases in 2D- and 3D-cultivated cells, including DYRK1A, whose loss of function sensitizes cells to radiotherapy. Additionally, we demonstrated that the harmine-targeted suppression of DYRK1A used in conjunction with radiotherapy increases DNA double-strand breaks (DSBs) and impairs homologous repair (HR), resulting in more cancer cell death. Our results support the use of CRISPR-Cas9 screening to identify new therapeutic targets, develop radiosensitizers, and provide novel strategies for overcoming the tolerance of pancreatic cancer to radiotherapy.

Optimizing the Pharmacological and Optical Dosimetry for Photodynamic Therapy with Methylene Blue and Nanoliposomal Benzoporphyrin on Pancreatic Cancer Spheroids

Photodynamic therapy (PDT) is a cancer treatment that relies on the remote-controlled activation of photocatalytic dyes (photosensitizers) in cancer tissues. To effectively treat cancer, a variety of pharmacological and optical parameters require optimization, which are dependent on the photosensitizer type. As most photosensitizers are hydrophobic molecules, nanoliposomes are frequently used to increase the biocompatibility of these therapeutics. However, as nanoliposomes can influence the therapeutic performance of photosensitizers, the most suitable treatment parameters need to be elucidated. Here, we evaluate the efficacy of PDT on spheroid cultures of PANC-1 and MIA PaCa-2 pancreatic cancer cells. Two strategies to photosensitize the pancreatic microtumors were selected, based on either nanoliposomal benzoporphyrin derivative (BPD), or non-liposomal methylene blue (MB). Using a comprehensive image-based assay, our findings show that the PDT efficacy manifests in distinct manners for each photosensitizer. Moreover, the efficacy of each photosensitizer is differentially influenced by the photosensitizer dose, the light dose (radiant exposure or fluence in J/cm2), and the dose rate (fluence rate in mW/cm2). Taken together, our findings illustrate that the most suitable light dosimetry for PDT strongly depends on the selected photosensitization strategy. The PDT dose parameters should therefore always be carefully optimized for different models of cancer.

Small extracellular vesicles: from mediating cancer cell metastasis to therapeutic value in pancreatic cancer

Pancreatic cancer is a highly malignant tumor and, is extremely difficult to diagnose and treat. Metastasis is one of the critical steps in the development of cancer and uses cell to cell communication to mediate changes in the microenvironment. Small extracellular vesicles (sEVs)-carry proteins, nucleic acids and other bioactive substances, and are important medium for communication between cells. There are two primary steps in sVEs-mediated metastasis: communication between pancreatic cancer cells and their surrounding microenvironment; and the communication between primary tumor cells and distant organ cells in distant organs that promotes angiogenesis, reshaping extracellular matrix, forming immunosuppressive environment and other ways to form appropriate pre-metastasis niche. Here, we explore the mechanism of localization and metastasis of pancreatic cancer and use sEVs as early biomarkers for the detection and treatment of pancreatic cancer. Graphical Abstract

IGF-1 Conjugated Sub-5 nm Ultrafine Iron Oxide Nanoparticle Enhances Targeted Drug Delivery and Efficacy of DNA Topoisomerase Inhibitor SN38 for Pancreatic Cancer: An in Vitro Study

Background Pancreatic cancer remains one of the most lethal cancers largely due to the inefficient delivery of therapeutics. Nanomaterials have been extensively investigated as drug delivery platforms, showing improved drug pharmacodynamics and pharmacokinetics. However, their applications in pancreatic cancer have not yet been successful due to limited tumor delivery caused by dense tumor stroma and distorted tumor vasculatures. Meanwhile, smaller-sized nanomaterials have shown improved tumor delivery and retention in various tumors, including pancreatic tumors, suggesting their potential in enhancing drug delivery. Methods An ultrafine iron oxide nanoparticle (uIONP) was used to encapsulate 7-ethyl-10-hydroxyl camptothecin (SN38), the water-insoluble active metabolite of chemotherapy drug irinotecan for treating pancreatic cancer in clinic. Insulin-like growth factor 1 (IGF-1) was conjugated to uIONP as a ligand for targeting pancreatic cancer and stromal cells overexpressing IGF-1 receptor (IGF1R). The SN38 loading and release profile were characterized. The cancer cell targeting and induced apoptosis by developed nano-formulationIGF1-uIONP/SN38 were also investigated. Results IGF1-uIONP/SN38 demonstrated stable drug loading in physiological pH with the loading efficiency of 68.2 ± 3.5% (SN38/Fe, wt%) and <7% release for 24 hours. In tumor-interstitial- and lysosomal-mimicking pH (6.5 and 5.5), 52.2 and 91.3% of encapsulated SN38 were released over 24 hours. The IGF1-uIONP/SN38 exhibited specific receptor-mediated cell targeting and cytotoxicity to MiaPaCa-2 cells with IC50 of 11.8 ± 2.3 nM, but not to HEK293 human embryonic kidney cells. Conclusion The IGF1-uIONP significantly improved the delivery of SN38 to targeted pancreatic cancer cells, holding the potential for in vivo theranostic applications.

Astragaloside-IV Inhibits Pancreatic Cancer Cell Proliferation in Vitro and in Vivo by Inducing Cell Cycle Arrest and Apoptosis

Astragaloside IV (AS-IV) or 3-O-β-D-xylopyranosyl-6-O-β-D-glucopyranosylcyl-cloastragenol is a bioactive saponin extract from the root of Astragalus membranaceus. It has been proven to have an anti-tumor effect in a variety of tumors by inducing cell apoptosis and inhibiting cell proliferation. Its effects on pancreatic cancer have not been investigated. This study investigated the effects of AS-IV on proliferation, apoptosis and migration of pancreatic cancer cells in vitro and in vivo and explored its underlying mechanism. Pancreatic cancer cell lines SW1990 and Panc-1were treated with different doses of AS-IV. Plate clonality, CCK-8, EDU and flow cytometry were used to explore the effect of AS-IV on pancreatic cancer cell proliferation and cell cycle in vitro. Wound healing was used to investigate the effects of AS-IV on pancreatic cell migration. The protein expression levels of Bax/Bcl2, caspase3/7, cyclin D1, cyclin E and CDK4 were analyzed by western blotting. The results showed that AS-IV significantly inhibited tumor cell proliferation and cell cycle, induced apoptosis both in vitro and vivo on a dose-dependent basis and significantly inhibited the growth of pancreatic cell xenograft tumor in nude mice. Wound healing assays indicated that AS-IV also inhibited the migration of pancreatic cancer cells in a dose-dependent manner. This research confirmed that AS-IV inhibited pancreatic cancer cell proliferation by blocking the cell cycle and inducing apoptosis. It was hypothesized from this experiment that the potential mechanism of AS-IV inducing apoptosis of pancreatic cancer cells may be understood by activating the Bcl2/Bax/Caspase-3/Caspase-7 signaling pathway.