Effect of Z-360, a novel orally active CCK-2/gastrin receptor antagonist on tumor growth in human pancreatic adenocarcinoma cell lines in vivo and mode of action determinations in vitro

Focus on Pancreatic Cancer Microenvironment

Pancreatic ductal adenocarcinoma remains one of the most lethal solid tumors due to its local aggressiveness and metastatic potential, with a 5-year survival rate of only 13%. A robust connection between pancreatic cancer microenvironment and tumor progression exists, as well as resistance to current anticancer treatments. Pancreatic cancer has a complex tumor microenvironment, characterized by an intricate crosstalk between cancer cells, cancer-associated fibroblasts and immune cells. The complex composition of the tumor microenvironment is also reflected in the diversity of its acellular components, such as the extracellular matrix, cytokines, growth factors and secreted ligands involved in signaling pathways. Desmoplasia, the hallmark of the pancreatic cancer microenvironment, contributes by creating a dense and hypoxic environment that promotes further tumorigenesis, provides innate systemic resistance and suppresses anti-tumor immune invasion. We discuss the complex crosstalk among tumor microenvironment components and explore therapeutic strategies and opportunities in pancreatic cancer research. Better understanding of the tumor microenvironment and its influence on pancreatic cancer progression could lead to potential novel therapeutic options, such as integration of immunotherapy and cytokine-targeted treatments.

Nonpeptidic Z360-Analogs Tagged with Trivalent Radiometals as Anti-CCK2R Cancer Theranostic Agents: A Preclinical Study

(1) Background: Theranostic approaches in the management of cholecystokinin subtype 2 receptor (CCK₂R)-positive tumors include radiolabeled gastrin and CCK motifs. Moving toward antagonist-based CCK₂R-radioligands instead, we herein present three analogs of the nonpeptidic CCK₂R-antagonist Z360, GAS1/2/3. Each was conjugated to a different chelator (DOTA, NODAGA or DOTAGA) for labeling with medically relevant trivalent radiometals (e.g., Ga-68, In-111, Lu-177) for potential use as anti-CCK₂R cancer agents; (2) Methods: The in vitro properties of the thee analogs were compared in stably transfected HEK293-CCK₂R cells. Biodistribution profiles were compared in SCID mice bearing twin HEK293-CCK₂R and wtHEK293 tumors; (3) Results: The GAS1/2/3 analogs displayed high CCK₂R-affinity (lower nM-range). The radioligands were fairly stable in vivo and selectively targeted the HEK293-CCK₂R, but not the CCK₂R-negative wtHEK293 tumors in mice. Their overall pharmacokinetic profile was found strongly dependent on the radiometal-chelate. Results could be visualized by SPECT/CT for the [¹¹¹In]In-analogs; (4) Conclusions: The present study highlighted the high impact of the radiometal-chelate on the end-pharmacokinetics of a new series of Z360-based radioligands, revealing candidates with promising properties for clinical translation. It also provided the impetus for the development of a new class of nonpeptidic radioligands for CCK₂R-targeted theranostics of human cancer.

Efficient Synthesis of Polysubstituted 1,5-Benzodiazepinone Dipeptide Mimetics via an Ugi-4CR-Ullmann Condensation Sequence

An efficient three-step synthesis towards 3-amino-1,4-benzodiazepin-2-one derivatives is presented. The versatile Ugi-4-component reaction (Ugi-4CR) and Boc deprotection is followed by a ligand-free Ullmann condensation. This protocol allows the rapid construction of a diverse array of substituted 1,5-benzodiazepinones. Since Ugi-based products are typically limited by their ‘inert’ C-terminal amides, the use of a convertible (‘cleavable’) isocyanide was envisaged and resulted in building blocks that can be made SPPS compatible. To demonstrate the potential of this novel synthetic route, the design and preparation of novel phenylurea-1,5-benzodiazepin-4(5H)-one dipeptide mimetics with potential CCK2-antagonist properties is reported.

[99mTc]Tc-DGA1, a Promising CCK2R-Antagonist-Based Tracer for Tumor Diagnosis with Single-Photon Emission Computed Tomography

Radiolabeled gastrin analogues have been proposed for theranostics of cholecystokinin subtype 2 receptor (CCK₂R)-positive cancer. Peptide radioligands based on other receptor antagonists have displayed superior pharmacokinetics and higher biosafety than agonists. Here, we present DGA1, a derivative of the nonpeptidic CCK₂R antagonist Z-360 carrying an acyclic tetraamine, for [^99mTc]Tc labeling. Preclinical comparison of [^99mTc]Tc-DGA1 with [^99mTc]Tc-DG2 (CCK₂R-agonist reference) was conducted in HEK293-CCK₂R/CCK_2i4svR cells and mice models, qualifying [^99mTc]Tc-DGA1 for further study in patients with CCK₂R-positive tumors and single-photon emission computed tomography/CT.

CCK2R antagonists: from SAR to clinical trials

The widespread involvement of the cholecystokinin-2/gastrin receptor (CCK₂R) in multiple (patho)physiological processes has propelled extensive searches for nonpeptide small-molecule CCK₂R antagonists. For the past three decades, considerable research has yielded numerous chemically heterogeneous compounds. None of these entered into the clinic, mainly because of inadequate biological effects. However, it appears that the ultimate goal of a clinically useful CCK₂R antagonist is now just around the corner, with the most promising compounds, netazepide and nastorazepide, now in Phase II clinical trials. Here, we illustrate the structure-activity relationships (SARs) of stablished CCK₂R antagonists of various structural classes, and the most recent proof-of-concept studies where new applicabilities of CCK₂R antagonists as visualizing agents are presented.

KRAS, YAP, and obesity in pancreatic cancer: A signaling network with multiple loops

Pancreatic ductal adenocarcinoma (PDAC) continues to be a lethal disease with no efficacious treatment modalities. The incidence of PDAC is expected to increase, at least partially because of the obesity epidemic. Increased efforts to prevent or intercept this disease are clearly needed. Mutations in KRAS are initiating events in pancreatic carcinogenesis supported by genetically engineered mouse models of the disease. However, oncogenic KRAS is not entirely sufficient for the development of fully invasive PDAC. Additional genetic mutations and/or environmental, nutritional, and metabolic stressors, e.g. inflammation and obesity, are required for efficient PDAC formation with activation of KRAS downstream effectors. Multiple factors "upstream" of KRAS associated with obesity, including insulin resistance, inflammation, changes in gut microbiota and GI peptides, can enhance/modulate downstream signals. Multiple signaling networks and feedback loops "downstream" of KRAS have been described that respond to obesogenic diets. We propose that KRAS mutations potentiate a signaling network that is promoted by environmental factors. Specifically, we envisage that KRAS mutations increase the intensity and duration of the growth-promoting signaling network. As the transcriptional activator YAP plays a critical role in the network, we conclude that the rationale for targeting the network (at different points), e.g. with FDA approved drugs such as statins and metformin, is therefore compelling.

A randomized phase II study of gemcitabine plus Z-360, a CCK2 receptor-selective antagonist, in patients with metastatic pancreatic cancer as compared with gemcitabine plus placebo

Background

We investigated the efficacy and safety of 60, 120, or 240 mg of Z-360, which is a highly potent cholecystokinin2-receptor-selective antagonist, combined with gemcitabine in patients with metastatic pancreatic cancer.

Methods

Patients were randomly assigned in a 1:1:1:1 ratio to one of four treatment groups. Patients received 1000 mg/m² gemcitabine for each cycle and Z-360 tablets of 60 mg (GZ 60 mg group), 120, 240 mg or placebo tablets (Gem group) orally twice daily. The primary endpoint was overall survival (OS).

Results

The median OS was 1.3 months longer in the GZ 60 mg group compared with the Gem group (8.5 vs. 7.2 months) and the risk of death was reduced by 19% compared with the Gem group, although there were no statistically significant differences. The study treatments were well tolerated.

Conclusions

In this Phase II study, no statistically significant differences between the GZ groups and Gem group were detected in any analysis. However, Z-360 in dose of 60 mg tends to improve OS in patients with metastatic pancreatic cancer with low toxic effect. Further exploratory trials with other agents such as gemcitabine plus nab-paclitaxel might be beneficial.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-017-3351-4) contains supplementary material, which is available to authorized users.

Small Molecules for Active Targeting in Cancer

For the purpose of this review, active targeting in cancer research encompasses strategies wherein a ligand for a cell surface receptor expressed on tumor cells is used to deliver a cytotoxic or imaging cargo. This area of research is more than two decades old, but in those 20 and more years, how many receptors have been studied extensively? What kinds of the ligands are used for active targeting? Are they mostly naturally occurring molecules such as folic acid, or synthetic substances developed in campaigns for medicinal chemistry efforts? This review outlines the most important receptor or ligand combinations that have been used in active targeting to answer these questions, and therefore to address the most important one of all: is research in active targeting affording diminishing returns, or is this an area for which the potential far exceeds progress made so far?

Selective Tumor Targeting of Desacetyl Vinblastine Hydrazide and Tubulysin B via Conjugation to a Cholecystokinin 2 Receptor (CCK2R) Ligand

As the delivery of selectively targeted cytotoxic agents via antibodies or small molecule ligands to malignancies has begun to show promise in the clinic, the need to identify and validate additional cellular targets for specific therapeutic delivery is critical. Although a multitude of cancers have been targeted using the folate receptor, PSMA, bombesin receptor, somatostatin receptor, LHRH, and α_vβ₃, there is a notable lack of specific small molecule ligand/receptor pairs to cellular targets found within cancers of the GI tract. Because of the selective GI tract expression of the cholecystokinin 2 receptor (CCK2R), we undertook the creation of conjugates that would deliver microtubule-disrupting drugs to malignancies through the specific targeting of CCK2R via a high affinity small molecule ligand. The cytotoxic activity of these conjugates were shown to be receptor mediated in vitro and in vivo with xenograft mouse models exhibiting delayed growth or regression of tumors that expressed CCK2R. Overall, this work demonstrates that ligands to CCK2R can be used to create selectively targeted therapeutic conjugates.

Evaluation of a nonpeptidic ligand for imaging of cholecystokinin 2 receptor-expressing cancers

Tumor-specific targeting ligands were recently exploited to deliver both imaging and therapeutic agents selectively to cancer tissues in vivo. Because the cholecystokinin 2 receptor (CCK2R) is overexpressed in various human cancers (e.g., lung, medullary thyroid, pancreatic, colon, and gastrointestinal stromal tumors) but displays limited expression in normal tissues, natural ligands of CCK2R were recently explored for use in the imaging of CCK2R-expressing cancers. Unfortunately, the results from these studies revealed not only that the peptidic CCK2R ligands were unstable in vivo but also that the ligands that mediated good uptake by tumor tissues also promoted a high level of retention of the radioimaging agent in the kidneys, probably because of capture of the conjugates by peptide-scavenging receptors. In an effort to reduce the normal organ retention of CCK2R-targeted drugs, we synthesized a nonpeptidic ligand of CCK2R and examined its specificity for CCK2R both in vitro and in vivo.

METHODS

Nonpeptidic agonists and antagonists of CCK2R described in the literature were evaluated for their affinities and specificities for CCK2R. Z-360, a benzodiazepine-derived CCK2R antagonist with subnanomolar affinity, was selected for complexation to (99m)Tc via multiple spacers. After synthesis and purification, 4 complexes with different physicochemical properties were evaluated for binding to CCK2R-transfected HEK 293 cells. The best conjugate, termed CRL-3-(99m)Tc, was injected into mice bearing CCK2R tumor xenografts and examined by γ scintigraphy and SPECT/CT. The uptake of the conjugate in various organs was also quantified by tissue resection and γ counting.

RESULTS

CRL-3-(99m)Tc was shown to bind with low nanomolar affinity to CCK2R in vitro and was localized to tumor tissues in athymic nu/nu mice implanted with CCK2R-expressing tumors. At 4 h after injection, tumor uptake was measured at 12.0 ± 2.0 percentage injected dose per gram of tissue.

CONCLUSION

Because the uptake of CRL-3-(99m)Tc by nonmalignant tissues was negligible and retention in the kidneys was only transient, we suggest that CRL-3-(99m)Tc may be a useful radioimaging agent for the detection, sizing, and monitoring of CCK2R-expressing tumors.

Evaluation of a cholecystokinin 2 receptor-targeted near-infrared dye for fluorescence-guided surgery of cancer

Surgical resection of malignant disease remains one of the most effective tools for treating cancer. Tumor-targeted near-infrared dyes have the potential to improve contrast between normal and malignant tissues, thereby enabling surgeons to more quantitatively resect malignant disease. Because the cholecystokinin 2 receptor (CCK2R and its tumor-specific splice variant CCK2i4svR) is overexpressed in cancers of the lungs, colon, thyroid, pancreas, and stomach, but absent or inaccessible to parenterally administered drugs in most normal tissues, we have undertaken to design a targeting ligand that can deliver attached near-infrared dyes to CCK2R+ tumors. We report here the synthesis and biological characterization of a CCK2R-targeted conjugate of the near-infrared dye, LS-288 (CRL-LS288). We demonstrate that CRL-LS288 binds selectively to CCK2R+ cancer cells with low nanomolar affinity (Kd = 7 × 10(-9) M). We further show that CRL-LS288 localizes primarily to CCK2R-expressing HEK 293 murine tumor xenografts and that dye uptake in these xenografts is significantly reduced when CCK2R are blocked by preinjection of excess ligand (CRL) or when mice are implanted with CCK2R-negative tumors. Because CRL-LS288 is also found to reveal the locations of distant tumor metastases, we suggest that CRL-LS288 has the potential to facilitate intraoperative identification of malignant disease during a variety of cancer debulking surgeries.

High expression of gastrin receptor protein in injured mucosa of Helicobacter pylori-positive gastritis

BACKGROUND AND AIM

Gastrin is a growth factor for the gastric epithelial cells. However, it is unknown how gastric receptor (GR) expression is regulated in the gastric mucosa. We studied GR expression using a newly raised antibody and investigated the relationship between GR expression and gastritis.

METHODS

Gastric receptor expression in 63 human gastric mucosa was studied. Helicobacter pylori infection and histological gastritis status were evaluated in gastric biopsy samples. In gastric ulcer cases, additional biopsy specimens were taken from injured mucosa. Fasting sera were collected and serum gastrin level evaluated. MKN-28 cells were cultured at various pH conditions, and the change in GR expression was determined.

RESULTS

Gastric receptor expression was detected in the foveolar epithelium of the gastric mucosa, and its expression was stronger in patients infected with H. pylori. In particular, higher expression was detected in regenerating injured mucosa. There was no association between gastritis score/serum gastrin level and GR expression in H. pylori-positive cases. In MKN-28 cells, GR protein expression was lower in neutral conditions than in acidic or alkaline conditions.

CONCLUSION

Gastric mucosal injury with H. pylori infection destroys the pH barrier on the foveolar epithelium and may induce GR expression through pH changes.

Cholecystokinin and gastrin receptors targeting in gastrointestinal cancer

Cholecystokinin and Gastrin are amongst the first gastrointestinal hormone discovered. In addition to classical actions (contraction of gallbladder, growth and secretion in the stomach and pancreas), these also act as growth stimulants for gastrointestinal malignancies and cell lines. Growth of these tumours is inhibited by antagonists of the cholecystokinin and gastrin receptors. These receptors provides most promising approach in clinical oncology and several specific radiolabelled ligands have been synthesized for specific tumour targeting and therapy of tumours overexpressing these receptors. Therefore, definition of the molecular structure of the receptor involved in the autocrine/paracrine loop may contribute to novel therapies for gastrointestinal cancer. Hence, this review tries to focus on the role and distribution of these hormones and their receptors in gastrointestinal cancer with a brief talk about the clinical trial using available agonist and antagonist in gastrointestinal cancers.

Somatic mutations in CCK2R alter receptor activity that promote oncogenic phenotypes

The roles of cholecystokinin 2 receptor (CCK2R) in numerous physiologic processes in the gastrointestinal tract and central nervous system are well documented. There has been some evidence that CCK2R alterations play a role in cancers, but the functional significance of these alterations for tumorigenesis is unknown. We have identified six mutations in CCK2R among a panel of 140 colorectal cancers and 44 gastric cancers. We show that these mutations increase receptor activity, activate multiple downstream signaling pathways, increase cell migration, and promote angiogenesis. Our findings suggest that somatic mutations in CCK2R may promote tumorigenesis through deregulated receptor activity and highlight the importance of evaluating CCK2R inhibitors to block both the normal and mutant forms of the receptor.

Current knowledge on pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer death with a median survival of 6 months and a dismal 5-year survival rate of 3-5%. The development and progression of pancreatic cancer are caused by the activation of oncogenes, the inactivation of tumor suppressor genes, and the deregulation of many signaling pathways. Therefore, the strategies targeting these molecules as well as their downstream signaling could be promising for the prevention and treatment of pancreatic cancer. However, although targeted therapies for pancreatic cancer have yielded encouraging results in vitro and in animal models, these findings have not been translated into improved outcomes in clinical trials. This failure is due to an incomplete understanding of the biology of pancreatic cancer and to the selection of poorly efficient or imperfectly targeted agents. In this review, we will critically present the current knowledge regarding the molecular, biochemical, clinical, and therapeutic aspects of pancreatic cancer.

CCK-2/gastrin receptor signaling pathway is significant for gemcitabine-induced gene expression of VEGF in pancreatic carcinoma cells

AIMS

As activation and overexpression of the cholecystokinin-2 (CCK-2)/gastrin receptor can lead to carcinogenesis, it has been explored as a therapeutic target in pancreatic cancer. We demonstrated that Z-360, a CCK-2/gastrin receptor antagonist, combined with gemcitabine prolonged survival and reduced gemcitabine-induced vascular endothelial growth factor (VEGF) expression in a pancreatic carcinoma orthotopic xenograft mouse. In this study, we investigated the role of the CCK-2/gastrin signaling pathway on gemcitabine-induced VEGF expression in PANC-1 human pancreatic carcinoma cells.

MAIN METHODS

In PANC-1 cells treated with Z-360, anti-gastrin IgG or kinase inhibitors, the gene expression levels were analyzed by quantitative real-time RT-PCR, and the protein levels of Akt and phosphorylated Akt (p-Akt) in cellular extracts were measured by ELISA.

KEY FINDINGS

Gemcitabine-induced expression of VEGF and hypoxia-inducible factor-1 alpha (HIF-1 alpha) were suppressed by the treatment with an anti-gastrin antibody. In addition, VEGF and HIF-1 alpha gene expression was inhibited by treatment with an inhibitor of phosphatidylinositol 3-kinase (PI3K), which is involved in the downstream signaling pathway of the CCK-2/gastrin receptor, and was also suppressed by treatment with Z-360. Moreover, although Akt phosphorylation was increased by treatment with gemcitabine, this elevation was partially, but significantly, inhibited by an exposure of Z-360.

SIGNIFICANCE

Gemcitabine might induce gene expression of VEGF via the PI3K/Akt signaling pathway in the downstream of the CCK-2/gastrin receptor. The suppression of the CCK-2/gastrin signaling pathway by treatment with Z-360 could be a useful approach for potentiating prolonged survival of pancreatic cancer patients receiving gemcitabine therapy.

Z-360, a novel therapeutic agent for pancreatic cancer, prevents up-regulation of ephrin B1 gene expression and phosphorylation of NR2B via suppression of interleukin-1 β production in a cancer-induced pain model in mice

BACKGROUND

Z-360 is an orally active cholecystokinin-2 (CCK2)/gastrin receptor antagonist currently under development as a therapeutic drug for pancreatic cancer. It was previously reported that Z-360 treatment in combination with gemcitabine prolonged the survival period in a lethal pancreatic cancer xenograft model in mice. In a phase Ib/IIa clinical study, Z-360 treatment displayed a trend of reduced pain in patients with advanced pancreatic cancer in combination with gemcitabine including analgesics such as opioids. Here, we investigated the mechanism of analgesic action of Z-360 in a severe cancer-induced pain model in mice, which is considered to be opioid-resistant, by examining ephrin B1 gene expression, N-methyl-D-aspartate receptor NR2B subunit phosphorylation, and interleukin-1β (IL-1β) production.

RESULTS

In a mouse model of cancer-induced pain, ephrin B1 gene expression in dorsal root ganglia (DRGs) and the phosphorylation of NR2B in the spinal cord were induced. Z-360 treatment inhibited both ephrin B1 gene expression and the phosphorylation of NR2B. In addition, IL-1β production increased in the cancer-inoculated hind paw of mice, but could be suppressed by treatment with Z-360. Moreover, we observed that the CCK1 receptor antagonist devazepide similarly suppressed up-regulation of ephrin B1 gene expression and IL-1β production, and that the intraperitoneal injection of sulfated CCK-8 induced the production of IL-1β in the cancer-inoculated region.

CONCLUSIONS

We have identified a novel pain cascade, in which IL-1β production in cancer-inoculated regions induces ephrin B1 gene expression in DRGs and then ephrin B1 enhances the tyrosine phosphorylation of NR2B via Eph B receptor in the spinal cord. Notably, Z-360 relieves cancer-induced pain by preventing this pain cascade through the suppression of IL-1β production, likely via the blockade of CCK1 receptor. The pre-clinical results presented here support the analgesic action of Z-360 in pancreatic cancer patients with severe, opioid-resistant pain. Pre-clinical and clinical results have demonstrated that Z-360 combined with gemcitabine represents a promising pancreatic cancer therapy approach with characteristic analgesic effects in addition to the prolongation of survival.

Pharmacological evaluation of analgesic effects of the cholecystokinin2 receptor antagonist Z-360 in mouse models of formalin- and cancer-induced pain

Z-360, a novel cholecystokinin(2) (CCK(2)) receptor antagonist, has been developed as a therapeutic drug for pancreatic cancer and showed pain relief action in phase Ib/IIa clinical trial. This study was attempted to elucidate the analgesic efficacy of Z-360 in mice. Oral administration of Z-360 (30-300 mg/kg) showed a dose-dependent inhibitory effect on the late phase of nociceptive responses to formalin. YF476, another CCK(2) receptor antagonist, was without effects at 1 and 10 mg/kg. In contrast, the CCK(1) receptor antagonist devazepide inhibited the nociceptive responses to formalin. In a mouse model of cancer pain, significant anti-allodynic effect of Z-360 was observed after single and repeated oral administration of 100 and 300 mg/kg doses. Anti-allodynic effect was also observed after repeated administration of devazepide. Combined single treatment with morphine and Z-360 caused an increase inhibition of pain-related responses in the pain models produced by formalin and cancer. Although Z-360 has lower affinity for CCK(1) receptor than for CCK(2) receptor, Z-360 exhibited an inhibitory effect on sulfated CCK-8-induced gallbladder emptying, a CCK(1) receptor-mediated effect, at a dose of 100 mg/kg. These results suggest that Z-360 inhibits inflammatory and cancer pain probably through the blockade of CCK(1) receptors. Z-360 is expected to become a useful drug for the pancreatic cancer with analgesic effects as well as the prolongation of survival.

Z-360, a novel cholecystokinin-2/gastrin receptor antagonist, inhibits gemcitabine-induced expression of the vascular endothelial growth factor gene in human pancreatic cancer cells

Z-360 is a novel cholecystokinin (CCK)-2/gastrin receptor antagonist that is being developed for the treatment of pancreatic adenocarcinoma in combination with gemcitabine. A previous study shows that the co-administration of Z-360 with gemcitabine significantly prolonged the survival of mice with orthotopically implanted human pancreatic adenocarcinoma cell lines. To clarify the therapeutic effects of Z-360 in combined with gemcitabine, we analyzed gene expression. When gemcitabine was administered, CCK-2/gastrin receptor expression was induced in an orthotropic xenograft model; the result indicating that Z-360 could act on gemcitabine-sensitive cells. Both in vitro and in vivo studies showed that gemcitabine increased the expression of vascular endothelial growth factor A (VEGFA), a prognostic factor for survival in pancreatic cancer, while Z-360 suppressed this induction of VEGFA gene expression. These results help to explain how Z-360 prolongs survival when used in combination with gemcitabine.

Effects of lorglumide on growth and invasion of human pancreatic cancer cell line Mia PaCa-2 in vitro through the cholecystokinin-cholecystokinin-1 receptor pathway

BACKGROUND

Cholecystokinin (CCK) has been found to be a growth stimulant through its special receptor pathway, especially for gastrointestinal malignancies. Although the CCK-1 receptor has been shown to be highly expressed in resected human pancreatic cancer samples, its role is less clear.

OBJECTIVE

The aim of this in vitro study was to investigate the CCK-1 receptor expression and the function of the CCK-CCK-1 receptor pathway in the human pancreatic adenocarcinoma cell line, Mia PaCa-2.

METHODS

The expression of the CCK-1 receptor in Mia PaCa-2 cells was detected by reverse-transcriptase polymerase chain reaction and flow cytometry. CCK-1 receptor agonist CCK-8S (the major transmitter form of CCK) and antagonist lorglumide were cultured respectively with Mia PaCa-2. Three groups were created for this study: CCK-8S group (Mia PaCa-2 cells treated with CCK-8S), lorglumide group (Mia PaCa-2 cells treated with lorglumide), and the control group (Mia PaCa-2 cells alone). Investigators were blinded to group designation. 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry were used to detect the cell growth, cell cycle, and apoptosis. Apoptosis index rate was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling. Cell invasion ability was observed by invasion assay. Expression of matrix metalloproteinase-2 (MMP-2) was measured by Western blotting.

RESULTS

Mia PaCa-2 cells were found to express the CCK-1 receptor. Compared with the control group (70.2% [1.5%]), CCK-8S was associated with significant mean (SD) cell proliferation (85.1% [1.7%]; P = 0.039), and the ratio in the S stage of the cell cycle increased significantly (50.5% [1.7%] vs 42.2% [1.4%]; P = 0.021). CCK-8S was also associated with increased Mia PaCa-2 cell invasion ability (123.8 [1.7] vs 102.1 [5.8]; P = 0.005 vs control). Compared with the control group, lorglumide was associated with significantly inhibited cell growth (52.1% [1.8%]; P = 0.002) and cell invasion (77.6% [1.2%]; P = 0.003). Lorglumide also induced G0/G1 cell cycle arrest and apoptosis (27.1% [3-5%] vs 3-7% [0.6%]; P = 0.003 vs control). The change of invasion ability appeared to be mediated by MMP-2 expression, which was upregulated by CCK-8S and downregulated by lorglumide.

CONCLUSION

The findings of this in vitro study suggest that CCK may exert a trophic action on the Mia PaCa-2 cell line, while lorglumide inhibited the cell growth and invasion.

Pancreatic cancer: molecular pathogenesis and new therapeutic targets

Patients with pancreatic cancer normally present with advanced disease that is lethal and notoriously difficult to treat. Survival has not improved dramatically despite routine use of chemotherapy and radiotherapy; this situation signifies an urgent need for novel therapeutic approaches. Over the past decade, a large number of studies have been published that aimed to target the molecular abnormalities implicated in pancreatic tumor growth, invasion, metastasis, angiogenesis and resistance to apoptosis. This research is of particular importance, as data suggest that a large number of genetic alterations affect only a few major signaling pathways and processes involved in pancreatic tumorigenesis. Although laboratory results of targeted therapies have been impressive, until now only erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has demonstrated modest survival benefit in combination with gemcitabine in a phase III clinical trial. Whilst the failures of targeted therapies in the clinical setting are discouraging, lessons have been learnt and new therapeutic targets that hold promise for the future management of the disease are continuously emerging. This Review describes some of the important developments and targeted agents for pancreatic cancer that have been tested in clinical trials.