New aspects of regulatory signaling pathways and novel therapies in pancreatic cancer

The role of CD95 in modulating CAR T-cell therapy: Challenges and therapeutic opportunities in oncology

CAR T cell therapy has revolutionized how we deliver cancer treatment, most notably for hematologic cancers, by compelling T cells to recognize and kill tumor cells. Nevertheless, current obstacles to utilizing this therapy in solid tumors and overcoming cancer resistance include radicalization. This review discusses how CD95 modulation can boost CAR T cell efficacy. Traditionally, CD95 was known to execute apoptosis induction, but it plays a dual role in induced cell death or in supporting cancer cell survival. Recent data have demonstrated that cancer cells escape CD95-mediated apoptosis via the downregulation of CD95, caspase 8 mutation, or the expression of the inhibition protein cFLIP. Additionally, the immunosuppressive tumor microenvironment, containing CD95L expressing immune cells, explains CAR T cell therapy resistance. Furthermore, we characterize the therapeutic potential of CD95 targeted approaches, including CD95L inhibition (APG101) and alterations in CAR T cell manufacturing (tyrosine kinase inhibitors to mitigate fratricide). In this review, we highlight the importance of multi-path way strategies combining CD95 modulation with CAR T cell engineering to overcome resistance, specifically to target tumor cells better and sustain CAR T cell persistence to enhance treatment efficacy in solid tumors.

Granzymes-Their Role in Colorectal Cancer

Colorectal cancer (CRC) is among the most common malignancies worldwide. CRC is considered a heterogeneous disease due to various clinical symptoms, biological behaviours, and a variety of mutations. A number of studies demonstrate that as many as 50% of CRC patients have distant metastases at the time of diagnosis. However, despite the fact that social and medical awareness of CRC has increased in recent years and screening programmes have expanded, there is still an urgent need to find new diagnostic tools for early detection of CRC. The effectiveness of the currently used classical tumour markers in CRC diagnostics is very limited. Therefore, new proteins that play an important role in the formation and progression of CRC are being sought. A number of recent studies show the potential significance of granzymes (GZMs) in carcinogenesis. These proteins are released by cytotoxic lymphocytes, which protect the body against viral infection as well specific signalling pathways that ultimately lead to cell death. Some studies suggest a link between GZMs, particularly the expression of Granzyme A, and inflammation. This paper summarises the role of GZMs in CRC pathogenesis through their involvement in the inflammatory process. Therefore, it seems that GZMs could become the focus of research into new CRC biomarkers.

Patient-Derived Xenograft Models of Pancreatic Cancer: Overview and Comparison with Other Types of Models

Pancreatic cancer (PC) is anticipated to be second only to lung cancer as the leading cause of cancer-related deaths in the United States by 2030. Surgery remains the only potentially curative treatment for patients with pancreatic ductal adenocarcinoma (PDAC), the most common form of PC. Multiple recent preclinical studies focus on identifying effective treatments for PDAC, but the models available for these studies often fail to reproduce the heterogeneity of this tumor type. Data generated with such models are of unknown clinical relevance. Patient-derived xenograft (PDX) models offer several advantages over human cell line-based in vitro and in vivo models and models of non-human origin. PDX models retain genetic characteristics of the human tumor specimens from which they were derived, have intact stromal components, and are more predictive of patient response than traditional models. This review briefly describes the advantages and disadvantages of 2D cultures, organoids and genetically engineered mouse (GEM) models of PDAC, and focuses on the applications, characteristics, advantages, limitations, and the future potential of PDX models for improving the management of PDAC.

TRAIL mediated signaling in pancreatic cancer

Research over the years has progressively shown substantial broadening of the tumor necrosis factor alpha- related apoptosis-inducing ligand (TRAIL)-mediated signaling landscape. Increasingly it is being realized that pancreatic cancer is a multifaceted and genomically complex disease. Suppression of tumor suppressors, overexpression of oncogenes, epigenetic silencing, and loss of apoptosis are some of the extensively studied underlying mechanisms. Rapidly accumulating in vitro and in vivo evidence has started to shed light on the resistance mechanisms in pancreatic cancer cells. More interestingly a recent research has opened new horizons of miRNA regulation by DR5 in pancreatic cancer cells. It has been shown that DR5 interacts with the core microprocessor components Drosha and DGCR8, thus impairing processing of primary let-7. Xenografting DR5 silenced pancreatic cancer cells in SCID-mice indicated that there was notable suppression of tumor growth. There is a paradigm shift in our current understanding of TRAIL mediated signaling in pancreatic cancer cells that is now adding new layers of concepts into the existing scientific evidence. In this review we have attempted to provide an overview of recent advances in TRAIL mediated signaling in pancreatic cancer as evidenced byfindings of in vitro and in vivo analyses. Furthermore, we discuss nanotechnological advances with emphasis on PEG-TRAIL and four-arm PEG cross-linked hyaluronic acid (HA) hydrogels to improve availability of TRAIL at target sites.

Significance of caveolin-1 regulators in pancreatic cancer

Caveolin-1 is a scaffold protein on the cell membrane. As the main component of caveolae, caveolin-1 is involved in many biological processes that include substance uptake and transmembrane signaling. Many of these processes and thus caveolin-1 contribute to cell transformation, tumorigenesis, and metastasis. Of particular interest are the dual rolesof tumor suppressor and oncogene that caveolin-1 appear to play in different malignancies, including pancreatic cancer. Therefore, analyzing caveolin-1 regulators and understanding their mechanisms of actionis key to identifying novel diagnostic and therapeutic tools for pancreatic cancer. This review details the mechanisms of action of caveolin-1 regulators and the potential significance for pancreatic cancer treatment.

Glycogen synthase kinase 3β inhibition sensitizes pancreatic cancer cells to gemcitabine

BACKGROUND

Pancreatic cancer is obstinate and resistant to gemcitabine, a standard chemotherapeutic agent for the disease. We previously showed a therapeutic effect of glycogen synthase kinase-3β (GSK3β) inhibition against gastrointestinal cancer and glioblastoma. Here, we investigated the effect of GSK3β inhibition on pancreatic cancer cell sensitivity to gemcitabine and the underlying molecular mechanism.

METHODS

Expression, phosphorylation, and activity of GSK3β in pancreatic cancer cells (PANC-1) were examined by Western immunoblotting and in vitro kinase assay. The combined effect of gemcitabine and a GSK3β inhibitor (AR-A014418) against PANC-1 cells was examined by isobologram and PANC-1 xenografts in mice. Changes in gene expression in PANC-1 cells following GSK3β inhibition were studied by cDNA microarray and reverse transcription (RT)-PCR.

RESULTS

PANC-1 cells showed increased GSK3β expression, phosphorylation at tyrosine 216 (active form), and activity compared with non-neoplastic HEK293 cells. Administration of AR-A014418 at pharmacological doses attenuated proliferation of PANC-1 cells and xenografts, and significantly sensitized them to gemcitabine. Isobologram analysis determined that the combined effect was synergistic. DNA microarray analysis detected GSK3β inhibition-associated changes in gene expression in gemcitabine-treated PANC-1 cells. Among these changes, RT-PCR and Western blotting showed that expression of tumor protein 53-induced nuclear protein 1, a gene regulating cell death and DNA repair, was increased by gemcitabine treatment and substantially decreased by GSK3β inhibition.

CONCLUSIONS

The results indicate that GSK3β inhibition sensitizes pancreatic cancer cells to gemcitabine with altered expression of genes involved in DNA repair. This study provides insight into the molecular mechanism of gemcitabine resistance and thus a new strategy for pancreatic cancer chemotherapy.

Small molecule inhibitors of bcl-2 family proteins for pancreatic cancer therapy

Pancreatic cancer (PC) has a complex etiology and displays a wide range of cellular escape pathways that allow it to resist different treatment modalities. Crucial signaling molecules that function downstream of the survival pathways, particularly at points where several of these pathways crosstalk, provide valuable targets for the development of novel anti-cancer drugs. Bcl-2 family member proteins are anti-apoptotic molecules that are known to be overexpressed in most cancers including PC. The anti-apoptotic machinery has been linked to the observed resistance developed to chemotherapy and radiation and therefore is important from the targeted drug development point of view. Over the past ten years, our group has extensively studied a series of small molecule inhibitors of Bcl-2 against PC and provide solid preclinical platform for testing such novel drugs in the clinic. This review examines the efficacy, potency, and function of several small molecule inhibitor drugs targeted to the Bcl-2 family of proteins and their preclinical progress against PC. This article further focuses on compounds that have been studied the most and also discusses the anti-cancer potential of newer class of Bcl-2 drugs.

Sequential or simultaneous placement of self-expandable metallic stents for palliation of malignant biliary and duodenal obstruction due to unresectable pancreatic head carcinoma

BACKGROUND

Pancreatic cancer is generally not amenable to curative resection, and self-expanding metallic stents have been used to relieve obstruction of bile duct and duodenum in patients with unresectable pancreatic cancer. However, both relative experience with sequential or simultaneous endoscopic stents placement in biliary and duodenal stricture and long-term efficacy of these stents are limited. The aim of this study was to present our experience on the effectiveness of this form of endoscopic treatment.

PATIENTS AND METHODS

We performed a retrospective review of all patients undergoing sequential or simultaneous biliary and duodenal stent placement for biliary and symptomatic duodenal obstruction due to unresectable pancreatic head carcinomas in 4 tertiary endoscopic centers. Data were collected from endoscopy and outpatient clinic reports, x-rays, and telephone calls. All patients were followed until their death. Endpoints included technical and clinical success, stent long-term patency, and survival.

RESULTS

Thirty-nine patients with unresectable pancreatic head cancer were included. Biliary or duodenal stenting was unsuccessful in 7 patients (17.9%). The remaining 32 patients (median age: 77 y; range: 52 to 82 y), with locally advanced (n=21) or metastatic disease (n=11), were studied. Twenty-one patients (65.6%) received at least first-line chemotherapy. Overall median survival was 9 months (range: 2 to 22 mo), being higher in locally advanced (median survival: 11.5 mo, range: 4 to 22 mo) than metastatic disease (median survival: 3 mo, range: 2 to 5.5 mo) (P<0.001). Median duodenal and biliary patency was 3 months (range: 1 to 12 mo) and 9 months (range: 2 to 22 mo), respectively (P<0.05). Nine of 32 patients (28.1%) required reintervention for recurrent symptoms. No major complications or death occurred in relation to endoscopic treatment.

CONCLUSIONS

Placement of self-expandable metal stents is a safe and efficacious palliation method for biliary and duodenal obstruction due to unresectable pancreatic head carcinoma. The majority of patients do not require reintervention and those who require can usually be managed nonoperatively.

Knockdown of snail sensitizes pancreatic cancer cells to chemotherapeutic agents and irradiation

The prognosis of patients with pancreatic cancer remains poor; only patients with small tumors and complete resection have a chance of a complete cure. Pancreatic cancer responds poorly to conventional therapies, including chemotherapy and irradiation. Snail is a transcription factor that has been associated with anti-apoptotic and chemoresistant properties in pancreatic cancer cells. In this study, we investigated whether knockdown of Snail suppresses growth of and/or sensitizes pancreatic cancer cells to chemotherapeutic agents and irradiation through induction of apoptosis. An adeno-associated virus vector was used to deliver Snail siRNA and knockdown Snail expression in untreated pancreatic cancer cells and in pancreatic cancer cells treated with chemotherapeutic agents or γ-irradiation. Our data indicate that our adeno-associated virus vector can efficiently deliver Snail siRNA into PANC-1 cells both in vitro and in vivo, resulting in the knockdown of Snail expression at the mRNA and protein levels. We further show that knockdown of Snail expression results in potent growth suppression of pancreatic cancer cells and suppresses xenograft tumor growth in vivo through induction of apoptosis. Finally, knockdown of Snail expression significantly sensitizes pancreatic cancer cells to chemotherapeutic agents and γ-irradiation through induction of apoptosis. In conclusion, our findings indicate that Snail is an important modulator of therapeutic responses of pancreatic cancer cells and is potentially useful as a sensitizer in pancreatic cancer therapy.

Effects of thymoquinone in the expression of mucin 4 in pancreatic cancer cells: implications for the development of novel cancer therapies

Pancreatic cancer is one of the most lethal cancers in the world, as it continues to be resistant to any therapeutic approaches. The high molecular weight glycoprotein mucin 4 (MUC4) is aberrantly expressed in pancreatic cancer and contributes to the regulation of differentiation, proliferation, metastasis, and the chemoresistance of pancreatic cancer cells. The absence of its expression in the normal pancreatic ductal cells makes MUC4 a promising target for novel cancer therapeutics. Natural products have been widely investigated as potential candidates in cancer therapies, and thymoquinone (TQ), extracted from the seeds of Nigella sativa, has shown excellent antineoplastic properties in some systems. In the present study, we evaluated the effect of TQ on pancreatic cancer cells and specifically investigated its effect on MUC4 expression. The MUC4-expressing pancreatic cancer cells FG/COLO357 and CD18/HPAF were incubated with TQ, and in vitro functional assays were done. The results obtained indicate that treatment with TQ downregulated MUC4 expression through the proteasomal pathway and induced apoptosis in pancreatic cancer cells by the activation of c-Jun NH(2)-terminal kinase and p38 mitogen-activated protein kinase pathways. In agreement with previous studies, the decrease in MUC4 expression correlated with an increase in apoptosis, decreased motility, and decreased migration of pancreatic cancer cells. MUC4 transient silencing studies showed that c-Jun NH(2)-terminal kinase and p38 mitogen-activated protein kinase pathways are activated in pancreatic cancer cells, indicating that the activation of these pathways by TQ is directly related to the MUC4 downregulation induced by the drug. Overall, TQ has potential for the development of novel therapies against pancreatic cancer.

Maslinic acid potentiates the anti-tumor activity of tumor necrosis factor alpha by inhibiting NF-kappaB signaling pathway

Background

Tumor necrosis factor alpha (TNFα) has been used to treat certain tumors in clinic trials. However, the curative effect of TNFα has been undermined by the induced-NF-κB activation in many types of tumor. Maslinic acid (MA), a pharmacological safe natural product, has been known for its important effects as anti-oxidant, anti-inflammatory, and anti-viral activities. The aim of this study was to determine whether MA potentiates the anti-tumor activity of TNFα though the regulation of NF-κB activation.

Results

In this study, we demonstrate that MA significantly enhanced TNFα-induced inhibition of pancreatic cancer cell proliferation, invasion, and potentiated TNFα-induced cell apoptosis by suppressing TNFα-induced NF-κB activation in a dose- and time-dependent manner. Addition of MA inhibited TNFα-induced IκBα degradation, p65 phosphorylation, and nuclear translocation. Furthermore, MA decreased the expression levels of NF-κB-regulated genes, including genes involved in tumor cell proliferation (Cyclin D1, COX-2 and c-Myc), apoptosis (Survivin, Bcl-2, Bcl-xl, XIAP, IAP-1), invasion (MMP-9 and ICAM-1), and angiogenesis (VEGF). In athymic nu/nu mouse model, we further demonstrated that MA significantly suppressed pancreatic tumor growth, induced tumor apoptosis, and inhibited NF-κB-regulated anti-apoptotic gene expression, such as Survivin and Bcl-xl.

Conclusions

Our data demonstrate that MA can potentiate the anti-tumor activities of TNFα and inhibit pancreatic tumor growth and invasion by activating caspase-dependent apoptotic pathway and by suppressing NF-κB activation and its downstream gene expression. Therefore, MA together with TNFα could be new promising agents in the treatment of pancreatic cancer.

PKC Delta (PKCdelta) promotes tumoral progression of human ductal pancreatic cancer

OBJECTIVE

Our objective was to study the role of protein kinase C delta (PKCdelta) in the progression of human pancreatic carcinoma.

METHODS

Protein kinase C delta expression in human ductal carcinoma (n = 22) was studied by immunohistochemistry. We analyzed the effect of PKCdelta overexpression on in vivo and in vitro properties of human ductal carcinoma cell line PANC1.

RESULTS

Human ductal carcinomas showed PKCdelta overexpression compared with normal counterparts. In addition, in vitro PKCdelta-PANC1 cells showed increased anchorage-independent growth and higher resistance to serum starvation and to treatment with cytotoxic drugs. Using pharmacological inhibitors, we determined that phosphatidylinositol-3-kinase and extracellular receptor kinase pathways were involved in the proliferation of PKCdelta-PANC1. Interestingly, PKCdelta-PANC1 cells showed a less in vitro invasive ability and an impairment in their ability to migrate and to secrete the proteolytic enzyme matrix metalloproteinase-2. In vivo experiments indicated that PKCdelta-PANC1 cells were more tumorigenic, as they developed tumors with a significantly lower latency and a higher growth rate with respect to the tumors generated with control cells. Besides, only PKCdelta-PANC1 cells developed lung metastasis.

CONCLUSION

Our results showed that the overexpression of PKCdelta in PANC1 cells induced a more malignant phenotype in vivo, probably through the modulation of cell proliferation and survival, involving phosphatidylinositol-3-kinase and extracellular receptor kinase signaling pathways.

Advances in pancreatic cancer detection

Pancreatic cancer represents a major challenge for research studies and clinical management. No specific tumor marker for the diagnosis of pancreatic cancer exists. Therefore, extensive genomic, transcriptomic, and proteomic studies are being developed to identify candidate markers for use in high-throughput systems capable of large cohort screening. Understandably, the complex pathophysiology of pancreatic cancer requires sensitive and specific biomarkers that can improve both early diagnosis and therapeutic monitoring. The lack of a single diagnostic marker makes it likely that only a panel of biomarkers is capable of providing the appropriate combination of high sensitivity and specificity. Biomarker discovery using novel technology can improve prognostic upgrading and pinpoint new molecular targets for innovative therapy.

Current status of mucins in the diagnosis and therapy of cancer

Mucins are the most abundant high molecular weight glycoproteins in mucus. Their nature and glycosylation content dictates the biochemical and biophysical properties of viscoelastic secretions, pointing out an important role in diverse biological functions, such as differentiation, cell adhesions, immune responses, and cell signaling. Mucins are expressed in tubular organs by specialized epithelial cells in the body. Their aberrant expression is well documented in a variety of inflammatory or malignant diseases. From a prognosis point of view, their expression and alterations in glycosylation are associated with the development and progression of malignant diseases. Therefore, mucins can be used as valuable markers to distinguish between normal and disease conditions. Indeed, this alteration in glycosylation patterns generates several epitopes in the oligosaccharide side chains that can be used as diagnostic and/or prognostic markers. Furthermore, these characteristic tumor-associated epitopes are extensively used as appropriate immunotargets of malignant epithelial cells. Therefore, in an effort to detect and treat cancer at the earliest stage possible, mucins are analyzed as potential markers of disease for diagnosis, progression, and for therapeutic purposes. In this review, we focused on the current status of the distribution of mucins in normal and pathologic conditions and their clinical use both in cancer diagnosis and therapeutics treatments.

Biomarkers in the diagnosis and early detection of pancreatic cancer

BACKGROUND

Pancreatic cancer, owing to its raising incidence and aggressiveness, is a major challenge, both for research and for clinical management. As pancreatic cancer has a complex pathophysiology, in addition to improving the methods of early diagnosis, sensitive and specific biomarkers are a prerequisite.

OBJECTIVE

As there is no specific tumor marker for pancreatic cancer diagnosis, extensive genomics/transcriptomics and proteomics studies have been developed with the aim of finding candidate markers and contributing to high-throughput systems for large cohort screening.

METHODS

A literature review was done to study these biomarkers in relation to diagnosis, prognosis and therapy targets in pancreatic cancer.

RESULTS/CONCLUSION

For early diagnosis improvement, only a panel of soluble biomarkers could provide the appropriate combination between high sensitivity and specificity. Prognostic upgrading would benefit from biomarker discovery and validation performed on tumor tissue. New technology could delineate molecular targets for innovative therapy in pancreatic cancer.

Prognostic signature for pancreatic cancer: are we close?

Pancreatic cancer is a deadly disease with an annual incidence rate nearly equal to its mortality rate. Incremental improvement in outcome has been seen in the last 25 years, illustrating the critical need for novel approaches and intensive research investment. Expression profiling of pancreatic cancers has led to an explosion of informative gene-expression changes and the identification of new diagnostic and prognostic markers. However, the search for genes that are of functional significance in these large datasets continues to be much more challenging. One approach to focusing on genes or pathways that are likely to be more biologically relevant is to study those that are of prognostic significance. This review will therefore focus on the advantages of a prognostic gene signature for pancreatic cancer, the advances that have been made thus far, the approaches used and the challenges that remain.

Prevention and treatment of pancreatic cancer by curcumin in combination with omega-3 fatty acids

Pancreatic cancer BxPC-3 cells were exposed to curcumin, docosahexaenoic acid (DHA), or combinations of both and analyzed for proliferation and apoptosis. Pancreatic tumor xenografts were established by injecting BxPC-3 cells into each flank of nude mice. After the tumors reached a size of approximately 190-200 mm(3), animals were fed diets with or without 2,000 ppm curcumin in 18% corn oil or 15% fish oil + 3% corn oil for 6 more wk before assessing the tumor volume and expression of inducible nitric oxide synthase (iNOS), cyclooxygeanse-2 (COX-2), 5-lipoxinase (5-LOX), and p21. A synergistic effect was observed on induction of apoptosis (approximately sixfold) and inhibition of cell proliferation (approximately 70%) when cells were treated with curcumin (5 microM) together with the DHA (25 microM). Mice fed fish oil and curcumin showed a significantly reduced tumor volume, 25% (P < 0.04) and 43% (P < 0.005), respectively, and importantly, a combination of curcumin and fish oil diet showed > 72% (P < 0.0001) tumor volume reduction. Expression and activity of iNOS, COX-2, and 5-LOX are downregulated, and p21 is upregulated in tumor xenograft fed curcumin combined with fish oil diet when compared to individual diets. The preceding results evidence for the first time that curcumin combined with omega-3 fatty acids provide synergistic pancreatic tumor inhibitory properties.