Interleukin-32 regulates downstream molecules and promotes the invasion of pancreatic cancer cells

Pancreatic cancer is a malignant neoplasm with high invasiveness and poor prognosis. In a previous study, a highly invasive pancreatic cancer cell line was established and found to feature enhanced interleukin-32 (IL-32) expression. However, whether IL-32 promotes the invasiveness by enhancing or suppressing the expression of IL-32 through regulating downstream molecules was unclear. To investigate the effect of IL-32, cells were established with high levels of expression or downregulated IL-32; their invasive ability was measured using a real-time measurement system and the expression of some candidate downstream molecules involved in invasion was evaluated in the two cell types. The morphological changes in both cell types and the localization of IL-32 expression in pancreatic cancer tissues were studied using immunohistochemistry. Among the several splice variants of IL-32, cells transfected with the ε isoform had increased invasiveness, whereas the IL-32-suppressed cells had reduced invasiveness. Several downstream molecules, whose expression was changed in the two cell types, were monitored. Notably, changes of E-cadherin, CLDN1, CD44, CTGF and Wnt were documented. The morphologies of the two cell types differed from the original cell line. Immunohistochemically, the expression of IL-32 was observed only in tumor cells and not in normal pancreatic cells. In conclusion, IL-32 was found to promote the invasiveness of pancreatic cancer cells by regulating downstream molecules.

Anticancer Effect of Heparin-Taurocholate Conjugate on Orthotopically Induced Exocrine and Endocrine Pancreatic Cancer

Simple Summary

Pancreatic cancer has a less than 9% 5-year survival rate among patients because it is very difficult to detect and diagnose early. Combinatorial chemotherapy with surgery or radiotherapy is a potential remedy to treat pancreatic cancer. However, these strategies still have side effects such as hair loss, skin soreness and fatigue. To overcome these side effects, angiogenesis inhibitors such as sunitinib are used to deliver targeted blood vessels around tumor tissues, including pancreatic cancer tumors. It is still controversial whether antiangiogenesis therapy is sufficient to treat pancreatic cancer. So far, many scientists have not been focused on the tumor types of pancreatic cancer when they have developed antipancreatic cancer medication. Here, we used heparin–taurocholate (LHT) as an anticancer drug to treat pancreatic cancer through inhibition of angiogenic growth factors. In this study, we examined the anticancer efficacy of LHT on various types of pancreatic cancer in an orthotopic model.

Abstract

Pancreatic cancers are classified based on where they occur, and are grouped into those derived from exocrine and those derived from neuroendocrine tumors, thereby experiencing different anticancer effects under medication. Therefore, it is necessary to develop anticancer drugs that can inhibit both types. To this end, we developed a heparin–taurocholate conjugate, i.e., LHT, to suppress tumor growth via its antiangiogenic activity. Here, we conducted a study to determine the anticancer efficacy of LHT on pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine tumor (PNET), in an orthotopic animal model. LHT reduced not only proliferation of cancer cells, but also attenuated the production of VEGF through ERK dephosphorylation. LHT effectively reduced the migration, invasion and tube formation of endothelial cells via dephosphorylation of VEGFR, ERK1/2, and FAK protein. Especially, these effects of LHT were much stronger on PNET (RINm cells) than PDAC (PANC1 and MIA PaCa-2 cells). Eventually, LHT reduced ~50% of the tumor weights and tumor volumes of all three cancer cells in the orthotopic model, via antiproliferation of cancer cells and antiangiogenesis of endothelial cells. Interestingly, LHT had a more dominant effect in the PNET-induced tumor model than in PDAC in vivo. Collectively, these findings demonstrated that LHT could be a potential antipancreatic cancer medication, regardless of pancreatic cancer types.

Pyrrolidine Dithiocarbamate Facilitates Arsenic Trioxide Against Pancreatic Cancer via Perturbing Ubiquitin-Proteasome Pathway

Purpose

To investigate whether pyrrolidine dithiocarbamate (PDTC) could facilitate arsenic trioxide (ATO) to induce apoptosis in pancreatic cancer cells via perturbing ubiquitin-proteasome pathway.

Methods

Mass spectrometry was performed to examine the interaction between PDTC and ATO, and the data showed they could form a complex termed PDTC-ATO. Inhibiting effects on cell viability were examined by CCK-8 test, and apoptosis was examined by flow cytometry. Four treatment arms (n = 6), including the control, PDTC, ATO, and PDTC-ATO, were evaluated using BALB/c nude mouse models bearing a xenograft tumor of SW1990 human pancreatic cancer line. Western blot, immunohistochemistry assays were to detect the mechanism.

Results

The results showed that PDTC-ATO had higher inhibiting effects on proliferation of pancreatic cancer cells than ATO in vitro. In bearing-tumor mice, PDTC-ATO inhibited tumor growth by 79%, being more potent than ATO (by 46%) or PDTC (by 35%) compared to the control. Results of Western blot and immunohistochemistry showed proteasome inhibition and apoptotic cell death, together with obvious suppression of associating E3 ubiquitin ligase activity, occurred more frequently in tumors treated with PDTC-ATO than those with ATO.

Conclusion

PDTC demonstrated the function to facilitate ATO against pancreatic cancer due to forming a stable complex to perturb ubiquitin-proteasome pathway.

Selaginellin B induces apoptosis and autophagy in pancreatic cancer cells via the JAK2/STAT3 signaling pathway

Selaginella tamariscina (ST), a well-known traditional medicinal plant, has been used to treat various cancers, including pancreatic cancer. However, the underlying mechanism by which Selaginellin B, a natural pigment isolated and purified from ST, protects against pancreatic cells has yet to be fully elucidated. In the present study, the biological functions of Selaginellin B were investigated using apoptosis, migration and colony formation assays in ASPC-1 and PANC-1 cells. In addition, apoptosis-associated proteins were detected by Western blotting. Our results demonstrated that Selaginellin B induced apoptosis, as evidenced by the increased cleaved caspase-3 level and Bax/Bcl-2 ratio. Moreover, Selaginellin B led to a marked up-regulation of the ratio of LC3-II/LC3-I in ASPC-1 and PANC-1 cells, respectively. Furthermore, reverse pharmacophore screening, molecular docking and molecular dynamics simulation studies revealed that Janus kinase 2 (JAK2) may be a potential target for Selaginellin B. In summary, the results of the present research have demonstrated that Selaginellin B is an effective anticancer agent against PANC-1 and ASPC-1 cells, and the compound holds great promise for the treatment of pancreatic cancer.

Establishment of highly invasive pancreatic cancer cell lines and the expression of IL-32

Compared to tumors of other organs, pancreatic cancer is highly aggressive; with one of its biological features being that, despite a prominent fibrotic stroma, there is remarkable infiltration of tumor cells. This characteristic is considered to be the main reason for the poor prognosis of patients with pancreatic cancer. Therefore, in order to elucidate the factors that contribute to this high invasiveness, a selective invasion method was used to establish four highly invasive subclones from six human pancreatic cancer cell lines. The results demonstrated that two cell lines did not exhibit enhanced invasiveness. Microarray analysis revealed that, in the highly invasive cell lines, several genes were expressed at high levels, compared with the original cell lines. These highly expressed genes were recognized only in highly invasive cells. Among them, IL-32 was most strongly upregulated in the highly invasive cells, compared with cells with a low invasive potential, as well as the original cells. RT-qPCR and western blot analysis confirmed the high levels of expression of IL-32 in highly invasive cells at the RNA and protein levels. In addition, immunohistochemical analysis of resected surgical materials revealed that the tumor cells expressed IL-32 and, in particular, many IL-32 positive cells were seen at the invasive front of the tumor tissue. IL-32 is a cytokine that is widely involved in the development of cancer and has recently received considerable attention. This cytokine has multiple splice variants and shows a wide variety of behaviors, depending on the tumor type and primary organ. Although some hypotheses have been proposed to explain the activity of IL-32, a unified view has not been agreed. In the present study, through the establishment of highly invasive cells from pancreatic cancer and a comprehensive gene analysis, it is suggested that IL-32 may serve an important role as a molecule involved in the invasiveness of this neoplasm.

Monitoring Epithelial-Mesenchymal Transition of Pancreatic Cancer Cells via Investigation of Mitochondrial Dysfunction

In this protocol, we introduced a method of measuring mitochondrial dysfunction to confirm the epithelial-mesenchymal transition (EMT) in pancreatic cancer cells under a hypoxic environment. There are many expertized and complicated methods to verify EMT. However, our methods have indicated that EMT can be identified by examining changes in reactive oxygen species (ROS) generation and membrane potential in mitochondria. To demonstrate whether the changes in the indicators of mitochondrial dysfunction are correlative to EMT, cell morphology, and expression of E-cadherin and N-cadherin were additionally observed. The results verified that a decrease in membrane potential and an increase in ROS in mitochondria were associated with EMT of pancreatic cancer cells. This protocol would be useful as a basis for providing an additional indicator for changes in the tumor microenvironment of pancreatic cancer cells relating to EMT under a hypoxic environment.

Monitoring Epithelial-Mesenchymal Transition of Pancreatic Cancer Cells via Investigation of Mitochondrial Dysfunction

In this protocol, we introduced a method of measuring mitochondrial dysfunction to confirm the epithelial–mesenchymal transition (EMT) in pancreatic cancer cells under a hypoxic environment. There are many expertized and complicated methods to verify EMT. However, our methods have indicated that EMT can be identified by examining changes in reactive oxygen species (ROS) generation and membrane potential in mitochondria. To demonstrate whether the changes in the indicators of mitochondrial dysfunction are correlative to EMT, cell morphology, and expression of E-cadherin and N-cadherin were additionally observed. The results verified that a decrease in membrane potential and an increase in ROS in mitochondria were associated with EMT of pancreatic cancer cells. This protocol would be useful as a basis for providing an additional indicator for changes in the tumor microenvironment of pancreatic cancer cells relating to EMT under a hypoxic environment.

Effect of baicalin on proliferation and apoptosis in pancreatic cancer cells

BACKGROUND AND OBJECTIVES

Pancreatic cancer is one of the most lethal cancer types. Pancreatic cancer is highly malignant and characterized by rapid and uncontrolled growth. This study was designed to investigate the effect of baicalin on proliferation and apoptosis in pancreatic cancer cells.

METHODS

CCK-8 assay and Clone formation assay were performed to detect the effect of baicalin on proliferation in pancreatic cancer cells. Cell invasion and migration were all assessed with Wound healing assay and Transwell invasion assay. Flow Cytometry Analysis and DAPI staining were performed to detect the effect of baicalin on apoptosis in pancreatic cancer cells. Furthermore, proliferation-associated protein and apoptosis-related protein were detected to evaluate the cell proliferation and apoptosis levels. P-JNK protein, t-JNK protein, Foxo1 protein and BIM protein were examined by western blot to verify whether baicalin could regulate the proliferation and apoptosis via the JNK/Foxo1/BIM signaling pathway in pancreatic cancer cells.

RESULTS

The cell proliferation level was significantly decreased while the cell apoptosis level was significantly increased in pancreatic cancer SW1990 cells treated with baicalin. As the same, baicalin downregulated the ability of invasion and migration in pancreatic cancer SW1990 cells.

CONCLUSION

Baicalin might inhibit cell proliferation and promote cell apoptosis via JNK/Foxo1/BIM signaling pathway in pancreatic cancer SW1990 cells.

Contribution of equilibrative nucleoside transporters 1 and 2 to gemcitabine uptake in pancreatic cancer cells

Hepatic arterial infusion (HAI) chemotherapy is expected to be a more effective and safer method to treat the hepatic metastasis of pancreatic cancer than intravenous (iv) administration because of higher tumor exposure and lower systemic exposure. To clarify the uptake mechanism of nucleoside anticancer drugs, including gemcitabine (GEM), in pancreatic cancer, we investigated the uptakes of radiolabeled uridine (a general substrate of nucleoside transporters) and GEM in pancreatic cancer cell lines MIA-PaCa2 and As-PC1. Uridine uptake was inhibited by non-labeled GEM and also by S-(4-nitrobenzyl)-6-thioinosine (NBMPR; an inhibitor of equilibrative nucleoside transporters, ENTs) in a concentration-dependent manner, suggesting that ENTs contribute to uridine uptake in pancreatic cancer cells. As for GEM, saturable uptake was mediated by high- and low-affinity components with K_m values of micromolar and millimolar orders, respectively. Uptake was inhibited in a concentration-dependent manner by NBMPR and was sodium ion-independent. Moreover, the concentration dependence of uptake in the presence of 0.1 μM NBMPR showed a single low-affinity site. These results indicated that the high- and low-affinity sites correspond to hENT1 and hENT2, respectively. The results indicated that at clinically relevant hepatic concentrations of GEM in GEM-HAI therapy, the metastatic tumor exposure of GEM is predominantly determined by hENT2 under unsaturated conditions, suggesting that hENT2 expression in metastatic tumor would be a candidate biomarker for indicating anticancer therapy with GEM-HAI.

Assessment of Anticancer Drug Effects on Pancreatic Cancer Cells under Glucose-Depleted Conditions Using Intracellular and Extracellular Amino Acid Metabolomics

Previously, we developed a method to evaluate states of cells treated with anticancer drugs via the comprehensive analysis of amino acids, termed amino acid metabolomics. In the present study, we evaluated the effects of the anticancer drugs, gemcitabine hydrochloride and pyrvinium pamoate, on the proliferation of a pancreatic cancer cell line (PANC-1) under hypoglycemic conditions using amino acid metabolomics. Intracellular and extracellular amino acid profiles of PANC-1 were determined by hydrophilic interaction chromatography-tandem mass spectrometry with simple pretreatment. Changes to the drugs' anticancer effects resulting from glucose starvation conditions were presented in score plots obtained from principal component analyses. In particular, the analysis of intracellular amino acids was found to be the superior approach because the results allowed a clearer assessment of the cell state. Further, orthogonal partial least squares discriminant analysis was performed to search for amino acid candidates that discriminate with anticancer drug-treated PANC-1 cells. We identified several amino acids that might be able to distinguish the drug-treated group from the control group. These results might provide a better understanding of the mechanisms underlying cell responses such as drug resistance or austerity. The present study is the first to evaluate the efficacy of anticancer drugs under glucose starvation based on the analysis of the variation of extracellular and intracellular amino acid profiles in vitro.

Synthesis of 2-Substituted Benzothiazole Derivatives and Their In Vitro Anticancer Effects and Antioxidant Activities Against Pancreatic Cancer Cells

Pancreatic cancer is one of the deadliest malignancies characterized by strong resistance to almost all chemotherapeutic agents and radiotherapy. In this study, we aimed to investigate the anticancer effect, enzymatic antioxidant activity [superoxide dismutase (SOD), glutathione peroxidase (GPx)] and total antioxidant capacity (TAC) of synthesized benzothiazole compounds against adenocarcinoma cancer cells (PANC-1). 2-((1S,2S)-2-((E)-4-nitrostyryl)cyclopent-3-en-1-yl)benzo[d]thiazole and 2-((1S,2S)-2-((E)-4-fluorostyryl) cyclopent-3-en-1-yl)benzo[d]thiazole containing 2-substituted benzothiazole group were synthesized in two steps. PANC-1 cells were treated with different concentrations of benzothiazole compounds (5, 25, 50. 75 and 100 μM) for 48 h and their cytotoxicity effects were determined by the MTT assay. To determine whether these compounds induced apoptosis, PANC-1 cells were treated with increasing concentrations of the synthetic products. Our study showed that the synthesized compounds have antiproliferative effects against PANC-1 cells and reduced cell viability. These compounds induced apoptosis of pancreatic cancer cells and at the same time reduced the activity of SOD and GPx and reduced TAC. On the basis of these findings, these synthesized benzothiazole compounds may be considered as a potential therapeutic drug against human PANC-1 cancer cells.

The PTB-Associated Splicing Factor/Peroxisome Proliferator-Activated Receptor Gamma Axis Regulates Autophagosome Formation in Human Pancreatic Cancer Cells

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor that plays a major regulatory role in metabolic function. It is overexpressed in many types of cancer cells, suggesting that regulation of PPARγ may also affect carcinogenesis. Our previous study suggested that PTB-associated splicing factor (PSF) is a PPARγ-interacting protein and growth regulator of colon cancer cells. In addition, PSF has been shown to be involved in several important regulatory steps of cancer cell proliferation. In this study, we aimed to investigate the relationships between PSF and PPARγ in pancreatic cancer by evaluating the effects of PSF expression in pancreatic cancer cell lines. PSF expression affected the expression of PPARγ, and knockdown of PSF using specific small-interfering RNA (siRNA) significantly suppressed the proliferation of pancreatic cancer cells. Furthermore, PSF knockdown induced cell growth inhibition and autophagosome formation through inhibition of PPARγ. Interestingly, Panc-1 cells were more susceptible to PSF knockdown-induced autophagy than MIA-PaCa-2 cells. Thus, our data indicated that PSF was an important regulator of autophagy and played critical roles in the survival and growth of pancreatic cancer cells. The PSF-PPARγ axis may play a role in the control of pancreatic cancer pathogenesis. This study is the first to describe the effects of PSF on pancreatic cancer cell growth and autophagy associated with PPARγ.

Designing protease sensors for real-time imaging of trypsin activation in pancreatic cancer cells

Acute pancreatitis is a serious and potentially fatal disease caused by intracellular trypsinogen activation. Although protease detection has been greatly facilitated by the development of protease probes capable of monitoring protease activation and inhibition, real-time quantitative measurement of protease activity in living cells remains a challenge, and the identification of the cellular compartment for trypsinogen activation is inconclusive. Here we report a novel strategy for developing trypsin sensors by grafting an enzymatic cleavage site into a sensitive location for optical change of chromophore in a single enhanced green fluorescent protein (EGFP). Our designed trypsin sensor exhibits rapid kinetic responses for protease activation and inhibition with a large ratiometric optical signal change. In addition, it has strong specificity, as enzymatic cleavage is not observed with other proteases such as thrombin, cathepsin B, tryptase, and tissue plasminogen activator. Moreover, the developed trypsin sensor allows us for the first time to observe, in real time, trypsinogen activation by caerulein in the pancreatic cancer cell line, MIA PaCa-2 without zymogen granules. These developed protease sensors will facilitate improved understanding of mechanisms and locations of protease activation and further provide screening of protease inhibitors with therapeutic effects.

Telomerase reverse transcriptase and telomeric-repeat binding factor protein 1 as regulators of telomerase activity in pancreatic cancer cells

Telomerase adds hexameric repeats of 5'-TTAGGG-3' termed telomeres to ends of chromosomal DNA. This enzyme has been implicated in cellular immortalization and cellular senescence. Recently, a number of relevant genes have been cloned, including these encoding three major components of human telomerase: human telomerase RNA component (hTR), human telomerase reverse transcriptase (hTERT), and telomerase-associated protein-1 (TEP1). Also important are genes encoding human telomeric-repeat binding factor protein (TRF) 1 and 2. To clarify mechanisms regulating telomerase activity, we studied telomerase activity, the telomeric restriction fragment (TRF) length and gene expression of these telomerase components and the telomeric-repeat binding factor proteins in sequential observation following X-irradiation of cultured pancreatic cancer cells. We previously reported that PANC-1 cells are better able to tolerate thermal stress, antineoplastic drugs, and exposure to tumour necrosis factor than MIAPaCa-2 cells. MIAPaCa-2 and PANC-1 cells were exposed to X-irradiation, their telomerase activity was increased at 2 days and then decreased gradually. Of the three telomerase components, only hTERT mRNA expression showed parallel changes. TRF length was stable just before and after X-irradiation. Among binding factor proteins, TRF1 mRNA showed reciprocal changes possibly directed toward maintaining a stable telomere length. In this study, our results demonstrate that not only hTERT but also TRF1 are important regulator of telomerase activity.