Expression of heat shock protein 70 modulates the chemoresponsiveness of pancreatic cancer

Application of Quercetin in the Treatment of Gastrointestinal Cancers

Many cellular signaling pathways contribute to the regulation of cell proliferation, division, motility, and apoptosis. Deregulation of these pathways contributes to tumor cell initiation and tumor progression. Lately, significant attention has been focused on the use of natural products as a promising strategy in cancer treatment. Quercetin is a natural flavonol compound widely present in commonly consumed foods. Quercetin has shown significant inhibitory effects on tumor progression via various mechanisms of action. These include stimulating cell cycle arrest or/and apoptosis as well as its antioxidant properties. Herein, we summarize the therapeutic effects of quercetin in gastrointestinal cancers (pancreatic, gastric, colorectal, esophageal, hepatocellular, and oral).

Ferroptosis: At the Crossroad of Gemcitabine Resistance and Tumorigenesis in Pancreatic Cancer

The overall five-year survival rate of pancreatic cancer has hardly changed in the past few decades (less than 10%) because of resistance to all known therapies, including chemotherapeutic drugs. In the past few decades, gemcitabine has been at the forefront of treatment for pancreatic ductal adenocarcinoma, but more strategies to combat drug resistance need to be explored. One promising possibility is ferroptosis, a form of a nonapoptotic cell death that depends on intracellular iron and occurs through the accumulation of lipid reactive oxygen species, which are significant in drug resistance. In this article, we reviewed gemcitabine-resistance mechanisms; assessed the relationship among ferroptosis, tumorigenesis and gemcitabine resistance, and explored a new treatment method for pancreatic cancer.

Plant Polyphenols for Aging Health: Implication from Their Autophagy Modulating Properties in Age-Associated Diseases

Polyphenols are a family of naturally occurring organic compounds, majorly present in fruits, vegetables, and cereals, characterised by multiple phenol units, including flavonoids, tannic acid, and ellagitannin. Some well-known polyphenols include resveratrol, quercetin, curcumin, epigallocatechin gallate, catechin, hesperetin, cyanidin, procyanidin, caffeic acid, and genistein. They can modulate different pathways inside the host, thereby inducing various health benefits. Autophagy is a conserved process that maintains cellular homeostasis by clearing the damaged cellular components and balancing cellular survival and overall health. Polyphenols could maintain autophagic equilibrium, thereby providing various health benefits in mediating neuroprotection and exhibiting anticancer and antidiabetic properties. They could limit brain damage by dismantling misfolded proteins and dysfunctional mitochondria, thereby activating autophagy and eliciting neuroprotection. An anticarcinogenic mechanism is stimulated by modulating canonical and non-canonical signalling pathways. Polyphenols could also decrease insulin resistance and inhibit loss of pancreatic islet β-cell mass and function from inducing antidiabetic activity. Polyphenols are usually included in the diet and may not cause significant side effects that could be effectively used to prevent and treat major diseases and ailments.

Protein arginine methylation promotes therapeutic resistance in human pancreatic cancer

Pancreatic cancer is a lethal disease with limited treatment options for cure. A high degree of intrinsic and acquired therapeutic resistance may result from cellular alterations in genes and proteins involved in drug transportation and metabolism, or from the influences of cancer microenvironment. Mechanistic basis for therapeutic resistance remains unclear and should profoundly impact our ability to understand pancreatic cancer pathogenesis and its effective clinical management. Recent evidences have indicated the importance of epigenetic changes in pancreatic cancer, including posttranslational modifications of proteins. We will review new knowledge on protein arginine methylation and its consequential contribution to therapeutic resistance of pancreatic cancer, underlying molecular mechanism, and clinical application of potential strategies of its reversal.

The Role of Autophagy in Pancreatic Cancer: From Bench to the Dark Bedside

Pancreatic cancer is one of the deadliest cancer types urgently requiring effective therapeutic strategies. Autophagy occurs in several compartments of pancreatic cancer tissue including cancer cells, cancer associated fibroblasts, and immune cells where it can be subjected to a multitude of stimulatory and inhibitory signals fine-tuning its activity. Therefore, the effects of autophagy on pancreatic carcinogenesis and progression differ in a stage and context dependent manner. In the initiation stage autophagy hinders development of preneoplastic lesions; in the progression stage however, autophagy promotes tumor growth. This double-edged action of autophagy makes it a hard therapeutic target. Indeed, autophagy inhibitors have not yet shown survival improvements in clinical trials, indicating a need for better evaluation of existing results and smarter targeting techniques. Clearly, the role of autophagy in pancreatic cancer is complex and many aspects have to be considered when moving from the bench to the bedside.

Flavonoid-alkylphospholipid conjugates elicit dual inhibition of cancer cell growth and lipid accumulation

Cancer development is often associated with lipid metabolic reprogramming, including aberrant lipid accumulation. We create novel paradigms endowed with dual functions of anticancer activity and inhibition of lipid accumulation by conjugating the natural product quercetin and synthetic alkylphospholipid drugs, and harnessing the biomedical effects of both. These conjugates offer fresh perspectives in the search for anticancer candidates.

The Opposite Effect of L-kynurenine and Ahr Inhibitor Ch223191 on Apoptotic Protein Expression in Pancreatic Carcinoma Cells (Panc-1)

BACKGROUND

L-kynurenine, derivate of L-tryptophan, is synthetized by indoleamine 2,3-dioxygenase (IDO). The effects of L-kynurenine depend on its binding to an aryl hydrocarbon receptor (AhR).

OBJECTIVE

The aim of this study was to investigate the changes within the apoptotic pathway in PANC-1 cells subjected to L-kynurenine or L-tryptophan considering the production of anti-apoptotic proteins from the IAPs and Bcl-2 family, as well as the regulation of NF-κB signaling.

METHODS

The investigated substances were added alone or in combination with the AhR inhibitor (CH223191) to cultures of PANC-1 cells. Cytoplasmic and nuclear proteins were analyzed by immunoblotting and cells were incubated with the investigated substances to determine cytotoxicity and proliferative effects.

RESULTS

Incubation of PANC-1 cells with L-kynurenine or L-tryptophan resulted in the increase in antiapoptotic cIAP-1, cIAP-2, XIAP and Bcl-2 expression and a decrease in pro-apoptotic Bax. These changes were accompanied by the reduction of active caspases -9, -3 and PARP-1. The treatment leads to translocation and enhanced production of nuclear NF-κB p50 and Bcl-3. Incubation of the cells with AhR blocker either alone or together with L-kynurenine or L-tryptophan resulted in the opposite effect, leading to the downregulation of IAPs and Bcl-2, upregulation of Bax and caspases expression.

CONCLUSION

1) L-kynurenine and its precursor promote anti-apoptotic effects through the modulation of IDOdependent pathway and regulation of IAPs, Bcl-2 and NF-κB family members in pancreatic carcinoma cells 2) inhibition of AhR by CH223191 exerts an apoptosis-promoting effect, and this observation might suggest the potential use of this compound in pancreatic cancer therapy.

CLEC14a-HSP70-1A interaction regulates HSP70-1A-induced angiogenesis

CLEC14a (C-type lectin domain family 14 member) is a tumor endothelial cell marker protein that is known to play an important role in tumor angiogenesis, but the basic molecular mechanisms underlying this function have not yet been clearly elucidated. In this study, using various proteomic tools, we isolated a 70-kDa protein that interacts with the C-type lectin-like domain of CLEC14a (CLEC14a-CTLD) and identified it as heat shock protein 70-1A (HSP70-1A). Co-immunoprecipitation showed that HSP70-1A and CLEC14a interact on endothelial cells. In vitro binding analyses identified that HSP70-1A specifically associates with the region between amino acids 43 and 69 of CLEC14a-CTLD. Competitive blocking experiments indicated that this interacting region of CLEC14a-CTLD significantly inhibits HSP70-1A-induced extracellular signal-regulated kinase (ERK) phosphorylation and endothelial tube formation by directly inhibiting CLEC14a-CTLD-mediated endothelial cell-cell contacts. Our data suggest that the specific interaction of HSP70-1A with CLEC14a may play a critical role in HSP70-1A-induced angiogenesis and that the HSP70-1A-interacting region of CLEC14a-CTLD may be a useful tool for inhibiting HSP70-1A-induced angiogenesis.

Disrupting glutamine metabolic pathways to sensitize gemcitabine-resistant pancreatic cancer

Pancreatic cancer is a lethal disease with poor prognosis. Gemcitabine has been the first line systemic treatment for pancreatic cancer. However, the rapid development of drug resistance has been a major hurdle in gemcitabine therapy leading to unsatisfactory patient outcomes. With the recent renewed understanding of glutamine metabolism involvement in drug resistance and immuno-response, we investigated the anti-tumor effect of a glutamine analog (6-diazo-5-oxo-L-norleucine) as an adjuvant treatment to sensitize chemoresistant pancreatic cancer cells. We demonstrate that disruption of glutamine metabolic pathways improves the efficacy of gemcitabine treatment. Such a disruption induces a cascade of events which impacts glycan biosynthesis through Hexosamine Biosynthesis Pathway (HBP), as well as cellular redox homeostasis, resulting in global changes in protein glycosylation, expression and functional effects. The proteome alterations induced in the resistant cancer cells and the secreted exosomes are intricately associated with the reduction in cell proliferation and the enhancement of cancer cell chemosensitivity. Proteins associated with EGFR signaling, including downstream AKT-mTOR pathways, MAPK pathway, as well as redox enzymes were downregulated in response to disruption of glutamine metabolic pathways.

Mortalin expression in pancreatic cancer and its clinical and prognostic significance

Mortalin, an essential mitochondrial chaperone protein, is involved in the tumorigenesis of a number of malignancies. This study aimed to investigate the expression of Mortalin in pancreatic ductal adenocarcinoma (PDAC) cells and to determine its clinicopathological and prognostic significance. The localization of Mortalin protein was detected in BXPC-3 PDAC cells using immunofluorescence. Immunohistochemistry was also used to detect Mortalin expression in well-defined tissues obtained from 106 PDAC patients and 46 corresponding nontumor pancreatic tissues. Clinicopathological parameters and overall survival data were collected and compared between different Mortalin statuses. The results of immunohistochemistry and immunofluorescence showed that Mortalin was primarily present in the cytoplasm of PDAC cells. The ratio of strong positive staining for Mortalin was higher in PDAC tissues (55.66%; 59/106) than in normal adjacent tissues (23.91%; 11/46). Positive relationships between Mortalin expression and clinical stage, perineural invasion, lymph node metastasis, and lower overall survival were observed. Multivariate Cox regression analysis identified Mortalin as a significant independent prognostic factor, in addition to location, clinical stage, and perineural invasion, for survival of PDAC patients. Therefore, we present strong evidence that Mortalin may function as a practical marker to predict prognosis and as a potential therapeutic target in PDAC treatment.

Triptolide reduces the viability of osteosarcoma cells by reducing MKP-1 and Hsp70 expression

Osteosarcoma is the most common type of malignant bone tumor found in adolescents and young adults. The aim of the present study was to determine whether triptolide, a diterpene epoxide extracted from the Tripterygium plant, was able effectively decrease the viability of osteosarcoma cells. The underlying molecular mechanisms are also investigated. The human osteosarcoma cell lines U-2 OS and MG-63 were used in this study. The U-2 OS and MG-63 cells were treated with 0, 5, 10, 25 or 50 nM triptolide. Cells treated with dimethyl sulfoxide only were used as the no drug treatment control. A commercial MTT kit was used to determine the effects of triptolide on cells. Mitogen-activated protein kinase phosphatase-1 (MKP-1) is frequently overexpressed in tumor tissues, possibly related to the failure of a number of chemotherapeutics. Heat shock protein 70 (Hsp70) is a chaperone molecule that is able to increase drug resistance. The protein expression levels of MKP-1 and Hsp70 were determined using western blot analysis. The results indicate that triptolide effectively reduced the viability of the osteosarcoma cells. Furthermore, triptolide was found to effectively reduce MKP-1 expression and Hsp70 levels. Further analysis showed that triptolide reduced MKP-1 mRNA expression in the U-2 OS and MG-63 cells. Triptolide reduced Hsp70 mRNA expression levels in U-2 OS and MG-63 cells. These results suggest that triptolide effectively decreases the viability of osteosarcoma cells. These effects may be associated with the decreased expression of MKP-1 and Hsp70 levels. These results suggest that triptolide may be used in the treatments of osteosarcoma.

Mining for Candidate Genes Related to Pancreatic Cancer Using Protein-Protein Interactions and a Shortest Path Approach

Pancreatic cancer (PC) is a highly malignant tumor derived from pancreas tissue and is one of the leading causes of death from cancer. Its molecular mechanism has been partially revealed by validating its oncogenes and tumor suppressor genes; however, the available data remain insufficient for medical workers to design effective treatments. Large-scale identification of PC-related genes can promote studies on PC. In this study, we propose a computational method for mining new candidate PC-related genes. A large network was constructed using protein-protein interaction information, and a shortest path approach was applied to mine new candidate genes based on validated PC-related genes. In addition, a permutation test was adopted to further select key candidate genes. Finally, for all discovered candidate genes, the likelihood that the genes are novel PC-related genes is discussed based on their currently known functions.

Quercetin Enhances Chemosensitivity to Gemcitabine in Lung Cancer Cells by Inhibiting Heat Shock Protein 70 Expression

Quercetin is a bioflavonoid known for antioxidation and antiproliferation activities. We demonstrated that quercetin inhibited cancer cell growth and sensitized cancer cells to gemcitabine treatment by promoting apoptosis via inhibiting heat shock protein 70 expression. Our results suggest that quercetin might have potential to increase sensitivity to chemotherapy and that heat shock protein 70 could be a new target for lung cancer treatment.

BACKGROUND

Quercetin is a bioflavonoid with antiproliferative and proapoptotic activity in various cancer cells. However, little is known about the mechanism by which quercetin inhibits cancer growth or its potential role as a chemosensitizer in lung cancer cells. We investigated whether quercetin-induced inhibition of heat shock protein 70 (HSP70) is involved in its anticancer activity and whether it could modulate the responsiveness of lung cancer cells to chemotherapy.

MATERIALS AND METHODS

Various concentrations of quercetin and gemcitabine, either alone or in combination, were applied to lung cancer cells (A549 and H460 cells). We evaluated cell viability with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide salt assay, apoptotic activity by determining caspase-3 and caspase-9 activities, and HSP70 expression using Western blot analysis after treatment.

RESULTS

Quercetin reduced cell viability and suppressed HSP70 expression in both cell lines dose-dependently. Adding a fixed quercetin dose enhanced gemcitabine-induced cell death, which was related to increased caspase-3 and caspase-9 activities. Combination treatment with quercetin and gemcitabine downregulated HSP70 expression more prominently than treatment with quercetin or gemcitabine alone.

CONCLUSION

Quercetin-induced HSP70 inhibition was involved in growth inhibition and sensitization to chemotreatment in lung cancer cells. Quercetin might have potential as a chemosensitizer in lung cancer treatment.

Biomarkers in bile-complementing advanced endoscopic imaging in the diagnosis of indeterminate biliary strictures

Biliary strictures present a diagnostic challenge and a conundrum, particularly when an initial work up including abdominal imaging and endoscopic retrograde cholangiopancreatography based sampling are non-diagnostic. Advances in endoscopic imaging have helped us diagnose these strictures better. However, even with modern technology, some strictures remain a diagnostic challenge. The proximity of bile fluid to the bile duct epithelia makes it an attractive option to investigate for bio-markers, which might be representative of the functions/abnormal changes taking place in the biliary system. A number of biomarkers in bile have been discovered recently in approaching biliary strictures with their potential future diagnostic utility, further supported by the immunohistochemical analysis of the resected tissue specimens. Novel biliary biomarkers especially carcinoembryonic cell adhesion molecule 6 and neutrophil gelatinase-associated lipocalin seem promising in differentiating malignant from benign biliary strictures. Recent developments in lipidomic profiling of bile are also very promising. Biliary biomarkers appear to complement endoscopic imaging in diagnosing malignant etiologies of biliary stricture. Future studies addressing these biomarkers need to be incorporated to the current endoscopic techniques to determine the best approach in determining the etiology of biliary strictures.