The Role of Gastrin and CCK Receptors in Pancreatic Cancer and other Malignancies

GPCR drug discovery: new agents, targets and indications

G protein-coupled receptors (GPCRs) form one of the largest drug target families, reflecting their involvement in numerous pathophysiological processes. In this Review, we analyse drug discovery trends for the GPCR superfamily, covering compounds, targets and indications that have reached regulatory approval or that are being investigated in clinical trials. We find that there are 516 approved drugs targeting GPCRs, making up 36% of all approved drugs. These drugs act on 121 GPCR targets, one-third of all non-sensory GPCRs. Furthermore, 337 agents targeting 133 GPCRs, including 30 novel targets, are being investigated in clinical trials. Notably, 165 of these agents are approved drugs being tested for additional indications and novel agents are increasingly allosteric modulators and biologics. Remarkably, diabetes and obesity drugs targeting GPCRs had sales of nearly US $30 billion in 2023 and the numbers of clinical trials for GPCR modulators in the metabolic diseases, oncology and immunology areas are increasing strongly. Finally, we highlight the potential of untapped target-disease associations and pathway-biased signalling. Overall, this Review provides an up-to-date reference for the drugged and potentially druggable GPCRome to inform future GPCR drug discovery and development.

The Important Role of p21-Activated Kinases in Pancreatic Exocrine Function

The p21-activated kinases (PAKs) are a conserved family of serine/threonine protein kinases, which are effectors for the Rho family GTPases, namely, Rac/Cdc42. PAKs are divided into two groups: group I (PAK1-3) and group II (PAK4-6). Both groups of PAKs have been well studied in apoptosis, protein synthesis, glucose homeostasis, growth (proliferation and survival) and cytoskeletal regulation, as well as in cell motility, proliferation and cycle control. However, little is known about the role of PAKs in the secretory tissues, including in exocrine tissue, such as the exocrine pancreas (except for islet function and pancreatic cancer growth). Recent studies have provided insights supporting the importance of PAKs in exocrine pancreas. This review summarizes the recent insights into the importance of PAKs in the exocrine pancreas by reviewing their presence and activation; the ability of GI hormones/neurotransmitters/GFs/post-receptor activators to activate them; the kinetics of their activation; the participation of exocrine-tissue PAKs in activating the main growth-signaling cascade; their roles in the stimulation of enzyme secretion; finally, their roles in pancreatitis. These insights suggest that PAKs could be more important in exocrine/secretory tissues than currently appreciated and that their roles should be explored in more detail in the future.

Pancreatic Cancer: A Review of Risk Factors

Pancreatic adenocarcinoma is one of the most lethal types of gastrointestinal cancer despite the latest medical advances. Its incidence has continuously increased in recent years in developed countries. The location of the pancreas can result in the initial symptoms of neoplasia being overlooked, which can lead to a delayed diagnosis and a subsequent reduction in the spectrum of available therapeutic options. The role of modifiable risk factors in pancreatic cancer has been extensively studied in recent years, with smoking and alcohol consumption identified as key contributors. However, the few screening programs that have been developed focus exclusively on genetic factors, without considering the potential impact of modifiable factors on disease occurrence. Thus, fully understanding and detecting the risk factors for pancreatic cancer represents an important step in the prevention and early diagnosis of this type of neoplasia. This review reports the available evidence on different risk factors and identifies the areas that could benefit the most from additional studies.

Cholelithiasis and cholecystectomy increase the risk of gastroesophageal reflux disease and Barrett's esophagus

Background

Cholelithiasis or cholecystectomy may contribute to the development of gastroesophageal reflux disease (GERD), Barrett's esophagus (BE), and esophageal adenocarcinoma (EAC) through bile reflux; however, current observational studies yield inconsistent findings. We utilized a novel approach combining meta-analysis and Mendelian randomization (MR) analysis, to assess the association between them.

Methods

The literature search was done using PubMed, Web of Science, and Embase databases, up to 3 November 2023. A meta-analysis of observational studies assessing the correlations between cholelithiasis or cholecystectomy, and the risk factors for GERD, BE, and EACwas conducted. In addition, the MR analysis was employed to assess the causative impact of genetic pre-disposition for cholelithiasis or cholecystectomy on these esophageal diseases.

Results

The results of the meta-analysis indicated that cholelithiasis was significantly linked to an elevated risk in the incidence of BE (RR, 1.77; 95% CI, 1.37-2.29; p < 0.001) and cholecystectomy was a risk factor for GERD (RR, 1.37; 95%CI, 1.09-1.72; p = 0.008). We observed significant genetic associations between cholelithiasis and both GERD (OR, 1.06; 95% CI, 1.02-1.10; p < 0.001) and BE (OR, 1.21; 95% CI, 1.11-1.32; p < 0.001), and a correlation between cholecystectomy and both GERD (OR, 1.04; 95% CI, 1.02-1.06; p < 0.001) and BE (OR, 1.13; 95% CI, 1.06-1.19; p < 0.001). After adjusting for common risk factors, such as smoking, alcohol consumption, and BMI in multivariate analysis, the risk of GERD and BE still persisted.

Conclusion

Our study revealed that both cholelithiasis and cholecystectomy elevate the risk of GERD and BE. However, there is no observed increase in the risk of EAC, despite GERD and BE being the primary pathophysiological pathways leading to EAC. Therefore, patients with cholelithiasis and cholecystectomy should be vigilant regarding esophageal symptoms; however, invasive EAC cytology may not be necessary.

CCK-8 enhances acid-sensing ion channel currents in rat primary sensory neurons

Cholecystokinin (CCK) is a peptide that has been implicated in pain modulation. Acid sensitive ion channels (ASICs) also play an important role in pain associated with tissue acidification. However, it is still unclear whether there is an interaction between CCK signaling and ASICs during pain process. Herein, we report that a functional link between them in rat dorsal root ganglion (DRG) neurons. Pretreatment with CCK-8 concentration-dependently increased acid-evoked ASIC currents. CCK-8 increased the maximum response of ASICs to acid, but did not changed their acid sensitivity. Enhancement of ASIC currents by CCK-8 was mediated by the stimulation of CCK2 receptor (CCK2R), rather than CCK1R. The enhancement of ASIC currents by CCK-8 was prevented by application of either G-protein inhibitor GDP-β-S or protein kinase C (PKC) inhibitor GF109203×, but not by protein kinase A (PKA) inhibitor H-89 or JNK inhibitor SP600125. Moreover, CCK-8 increased the number of action potentials triggered by acid stimuli by activating CCK2R. Finally, CCK-8 dose-dependently exacerbated acid-induced nociceptive behavior in rats through local CCK2R. Together, these results indicated that CCK-8/CCK2R activation enhanced ASIC-mediated electrophysiological activity in DRG neurons and nociception in rats. The enhancement effect depended on G-proteins and intracellular PKC signaling rather than PKA and JNK signaling pathway. These findings provided that CCK-8/CCK2R is an important therapeutic target for ASIC-mediated pain.

Detecting radio- and chemoresistant cells in 3D cancer co-cultures using chromatin biomarkers

The heterogenous treatment response of tumor cells limits the effectiveness of cancer therapy. While this heterogeneity has been linked to cell-to-cell variability within the complex tumor microenvironment, a quantitative biomarker that identifies and characterizes treatment-resistant cell populations is still missing. Herein, we use chromatin organization as a cost-efficient readout of the cells' states to identify subpopulations that exhibit distinct responses to radiotherapy. To this end, we developed a 3D co-culture model of cancer spheroids and patient-derived fibroblasts treated with radiotherapy. Using the model we identified treatment-resistant cells that bypassed DNA damage checkpoints and exhibited an aggressive growth phenotype. Importantly, these cells featured more condensed chromatin which primed them for treatment evasion, as inhibiting chromatin condensation and DNA damage repair mechanisms improved the efficacy of not only radio- but also chemotherapy. Collectively, our work shows the potential of using chromatin organization to cost-effectively study the heterogeneous treatment susceptibility of cells and guide therapeutic design.

Advances in Immunotherapeutics in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for up to 95% of all pancreatic cancer cases and is the seventh-leading cause of cancer death. Poor prognosis is a result of late presentation, a lack of screening tests and the fact some patients develop resistance to chemotherapy and radiotherapy. Novel therapies like immunotherapeutics have been of recent interest in pancreatic cancer. However, this field remains in its infancy with much to unravel. Immunotherapy and other targeted therapies have yet to yield significant progress in treating PDAC, primarily due to our limited understanding of the disease immune mechanisms and its intricate interactions with the tumour microenvironment (TME). In this review we provide an overview of current novel immunotherapies which have been studied in the field of pancreatic cancer. We discuss their mechanisms, evidence available in pancreatic cancer as well as the limitations of such therapies. We showcase the potential role of combining novel therapies in PDAC, postulate their potential clinical implications and the hurdles associated with their use in PDAC. Therapies discussed with include programmed death checkpoint inhibitors, Cytotoxic T-lymphocyte-associated protein 4, Chimeric Antigen Receptor-T cell therapy, oncolytic viral therapy and vaccine therapies including KRAS vaccines, Telomerase vaccines, Gastrin Vaccines, Survivin-targeting vaccines, Heat-shock protein (HSP) peptide complex-based vaccines, MUC-1 targeting vaccines, Listeria based vaccines and Dendritic cell-based vaccines.

Mechanisms of obesity- and diabetes mellitus-related pancreatic carcinogenesis: a comprehensive and systematic review

Research on obesity- and diabetes mellitus (DM)-related carcinogenesis has expanded exponentially since these two diseases were recognized as important risk factors for cancers. The growing interest in this area is prominently actuated by the increasing obesity and DM prevalence, which is partially responsible for the slight but constant increase in pancreatic cancer (PC) occurrence. PC is a highly lethal malignancy characterized by its insidious symptoms, delayed diagnosis, and devastating prognosis. The intricate process of obesity and DM promoting pancreatic carcinogenesis involves their local impact on the pancreas and concurrent whole-body systemic changes that are suitable for cancer initiation. The main mechanisms involved in this process include the excessive accumulation of various nutrients and metabolites promoting carcinogenesis directly while also aggravating mutagenic and carcinogenic metabolic disorders by affecting multiple pathways. Detrimental alterations in gastrointestinal and sex hormone levels and microbiome dysfunction further compromise immunometabolic regulation and contribute to the establishment of an immunosuppressive tumor microenvironment (TME) for carcinogenesis, which can be exacerbated by several crucial pathophysiological processes and TME components, such as autophagy, endoplasmic reticulum stress, oxidative stress, epithelial-mesenchymal transition, and exosome secretion. This review provides a comprehensive and critical analysis of the immunometabolic mechanisms of obesity- and DM-related pancreatic carcinogenesis and dissects how metabolic disorders impair anticancer immunity and influence pathophysiological processes to favor cancer initiation.

Elucidating the molecular determinants in the process of gastrin C-terminal pentapeptide amide end activating cholecystokinin 2 receptor by Gaussian accelerated molecular dynamics simulations

Gastrin plays important role in stimulating the initiation and development of many gastrointestinal diseases through interacting with the cholecystokinin 2 receptor (CCK2R). The smallest bioactive unit of gastrin activating CCK2R is the C-terminal tetrapeptide capped with an indispensable amide end. Understanding the mechanism of this smallest bioactive unit interacting with CCK2R on a molecular basis could provide significant insights for designing CCK2R antagonists, which can be used to treat gastrin-related diseases. To this end, we performed extensive Gaussian accelerated molecular dynamics simulations to investigate the interaction between gastrin C-terminal pentapeptide capped with/without amide end and CCK2R. The amide cap influences the binding modes of the pentapeptide with CCK2R by weakening the electrostatic attractions between the C-terminus of the pentapeptide and basic residues near the extracellular domain in CCK2R. The C-terminus with the amide cap penetrates into the transmembrane domain of CCK2R while floating at the extracellular domain without the amide cap. Different binding modes induced different conformational dynamics of CCK2R. Residue pairs in CCK2R had stronger correlated motions when binding with the amidated pentapeptide. Key residues and interactions important for CCK2R binding with the amidated pentagastrin were also identified. Our results provide molecular insights into the determinants of the bioactive unit of gastrin activating CCK2R, which would be of great help for the design of CCK2R antagonists.

CCKAR is a biomarker for prognosis and asynchronous brain metastasis of non-small cell lung cancer

Background

Non-small cell lung cancer (NSCLC) is the most common histological type of lung cancer, and brain metastasis (BM) is the most lethal complication of NSCLC. The predictive biomarkers and risk factors of asynchronous BM are still unknown.

Materials and methods

A total of 203 patients with NSCLC were enrolled into our cohort and followed up. The clinicopathological factors such as tumor size, T stage, lymphatic invasion, metastasis and asynchronous BM were investigated. CCKAR expression in NSCLC and resected BM was assessed by IHC, and CCKAR mRNAs in NSCLC and para-tumor tissues were estimated by qRT-PCR. The correlations between CCKAR expression, BM and other clinicopathological factors were assessed by chi-square test, and prognostic significance of CCKAR was estimated by univariate and multivariate analyses.

Results

CCKAR was highly expressed in NSCLC tissues compared with para-tumor tissues. CCKAR expression in NSCLC was significantly associated with asynchronous BM. The BM percentages for NSCLC patients with low and high CCKAR were surprisingly 5.2% and 66.6%, respectively. CCKAR expression and BM were unfavorable factors predicting unfavorable outcome of NSCLC. Moreover, CCKAR expression in NSCLC was an independent risk factor of asynchronous BM.

Conclusions

CCKAR is a prognostic biomarker of NSCLC. CCKAR expression in NSCLC is positively associated with asynchronous BM, and is a risk factor of asynchronous BM from NSCLC.

The Role of a Natural Amphibian Skin-Based Peptide, Ranatensin, in Pancreatic Cancers Expressing Dopamine D2 Receptors

Despite the progress in early diagnostic and available treatments, pancreatic cancer remains one of the deadliest cancers. Therefore, there is an urgent need for novel anticancer agents with a good safety profile, particularly in terms of possible side-effects. Recently dopaminergic receptors have been widely studied as they were proven to play an important role in cancer progression. Although various synthetic compounds are known for their interactions with the dopaminergic system, peptides have recently made a great comeback. This is because peptides are relatively safe, easy to correct in terms of the improvement of their physicochemical and biological properties, and easy to predict. This paper aims to evaluate the anticancer activity of a naturally existing peptide-ranatensin, toward three different pancreatic cancer cell lines. Additionally, since there is no sufficient information confirming the exact character of the interaction between ranatensin and dopaminergic receptors, we provide, for the first time, binding properties of the compound to such receptors.

Proton Pump Inhibitors Use and the Risk of Pancreatic Cancer: Evidence from Eleven Epidemiological Studies, Comprising 1.5 Million Individuals

Previous epidemiological studies have shown that proton pump inhibitor (PPI) may modify the risk of pancreatic cancer. We conducted an updated systematic review and meta-analysis of observational studies assessing the effect of PPI on pancreatic cancer. PubMed, Embase, Scopus, and Web of Science were searched for studies published between 1 January 2000, and 1 May 2022. We only included studies that assessed exposure to PPI, reported pancreatic cancer outcomes, and provided effect sizes (hazard ratio or odds ratio) with 95% confidence intervals (CIs). We calculated an adjusted pooled risk ratio (RR) with 95%CIs using the random-effects model. Eleven studies (eight case-control and three cohorts) that reported 51,629 cases of pancreatic cancer were included. PPI was significantly associated with a 63% increased risk of pancreatic cancer (RRadj. 1.63, 95%CI: 1.19-2.22, p = 0.002). Subgroup analysis showed that the pooled RR for rabeprazole and lansoprazole was 4.08 (95%CI: 0.61-26.92) and 2.25 (95%CI: 0.83-6.07), respectively. Moreover, the risk of pancreatic cancer was established for both the Asian (RRadj. 1.37, 95%CI: 0.98-1.81) and Western populations (RRadj.2.76, 95%CI: 0.79-9.56). The findings of this updated meta-analysis demonstrate that the use of PPI was associated with an increased risk of pancreatic cancer. Future studies are needed to improve the quality of evidence through better verification of PPI status (e.g., patient selection, duration, and dosages), adjusting for possible confounders, and ensuring long-term follow-up.

Cholecystokinin receptor antagonist suppresses melanoma growth by inducing apoptosis of tumor cells

Melanoma is a malignant skin tumor with high metastatic activity. Although melanoma has been well-studied, its cellular kinetics remain elusive. The cholecystokinin (CCK) receptor is expressed in various types of tumors because CCK promotes the survival and proliferation of tumor cells. Thus, we hypothesized that the growth of melanoma was positively regulated by signals from the CCK receptor and sought to investigate whether CCK receptor antagonists affect the growth of melanoma cells expressing CCK receptor. Immunohistochemically, the CCK receptor A is expressed in the clinical specimens of melanoma. CCK receptor antagonists decreased the viability of melanoma cells by suppressing cell division and promoting apoptosis. CCK receptor antagonists also decreased the mitochondrial membrane potential through enhanced gene expression of the proapoptotic protein, Bcl2-associated X, and tumor suppressor, p53, suggesting that the antagonist induced the apoptosis of melanoma cells in a mitochondria-dependent manner. In addition, a caspase 3 inhibitor, Z-DEVD-FMK, partially blocked the antiviability of the antagonist, indicating that caspase 3 is involved in antagonist-induced apoptosis. Notably, tumor growth was attenuated when a CCK receptor antagonist was locally administered to the melanoma-bearing mice. Therefore, our study suggests the therapeutic potential of CCK receptor antagonists in the treatment of skin cancer.

Pancreas and Adverse Drug Reactions: A Literature Review

Adverse drug reactions (ADRs) affecting the pancreas are a heterogeneous group of side effects that cause damage to pancreatic cells. Various mechanisms such as hypersensitization, sphincter of Oddi constriction, direct cytotoxic and metabolic effects on pancreatic cells, and dose-dependent idiosyncrasy lead to intrapancreatic activation of pancreatic enzymes resulting in drug-induced acute pancreatitis. Several medications have been linked with the development of pancreatic cancer. Pancreatic cancer may result from proinflammatory, proliferative, and antiapoptotic effects. Diabetogenic effect of drugs, which is understood as impairment of insulin secretion, may occur due to direct destruction of β cells, systemic toxicity affecting pancreatic islets and cell membrane glucose transporters, induction of Th1-type autoimmune response, and impairment of voltage-gated calcium channels in β cells, endoplasmic reticulum stress, and insulin signaling. A better understanding of ADRs that affect the pancreas may contribute to improving the awareness of clinicians and patients and reducing potential harmful side effects of implemented therapies.

Use of Proton Pump Inhibitors and Risk of Pancreatic Cancer: A Nationwide Case-Control Study Based on the French National Health Data System (SNDS)

BACKGROUND

Only a few studies investigated the association between proton pump inhibitor (PPI) use and pancreatic cancer, with inconsistent results. Moreover, these studies had a number of methodologic limitations. Our objective was to assess this association in a nationwide case-control study.

METHODS

We used the French National Health Data System (SNDS), covering 99% of the French population since 2006. Incident cases of pancreatic cancer, identified between 2014 and 2018, were matched with up to four controls on year of birth, sex, frequency of hospitalization within 8 years prior to index date, and department of residence. Associations between PPIs and pancreatic cancer were estimated using conditional logistic regression models adjusted for sociodemographic characteristics, risk factors of pancreatic cancer (including diabetes mellitus, tobacco-related diseases, and morbid obesity), and other comorbidities.

RESULTS

A total of 23,321 cases of pancreatic cancer (mean age, 69.8 years; 51.7% males) and 75,937 matched controls were included. Overall, 77.8% of cases and 75.5% of controls were PPI ever users. Ever (vs. never) PPI use was associated with an increased risk of pancreatic cancer [adjusted OR (aOR) = 1.05, 95% confidence interval (CI), 1.01-1.09]. A dose-response relationship was observed [1-30 cumulative defined daily dose (cDDD): aOR = 0.92, 95% CI, 0.87-0.97; 31-180 cDDD: aOR = 1.05, 95% CI, 1.00-1.11; 181-1,080 cDDD: aOR = 1.18, 95% CI, 1.12-1.24; >1,080 cDDD: aOR = 1.17, 95% CI, 1.10-1.23].

CONCLUSIONS

On the basis of these findings, a slight increase in the risk of pancreatic cancer associated with high cumulative doses of PPIs cannot be excluded.

IMPACT

Given the overuse of PPIs, efforts should be continued to limit treatments to appropriate indications and durations.

Gastrin producing syngeneic mesenchymal stem cells protect non-obese diabetic mice from type 1 diabetes

Progressive destruction of pancreatic islet β-cells by immune cells is a primary feature of type 1 diabetes (T1D) and therapies that can restore the functional β-cell mass are needed to alleviate disease progression. Here, we report the use of mesenchymal stromal/stem cells (MSCs) for the production and delivery of Gastrin, a peptide hormone that is produced by intestinal cells and foetal islets and can increase β-Cell mass, to promote protection from T1D. A single injection of syngeneic MSCs that were engineered to express Gastrin (Gastrin-MSCs) caused a significant delay in hyperglycaemia in non-obese diabetic (NOD) mice compared to engineered control-MSCs. Similar treatment of early-hyperglycaemic mice caused the restoration of euglycemia for a considerable duration, and these therapeutic effects were associated with the protection of, and/or higher frequencies of, insulin-producing islets and less severe insulitis. While the overall immune cell phenotype was not affected profoundly upon treatment using Gastrin-MSCs or upon in vitro culture, pancreatic lymph node cells from Gastrin-MSC treated mice, upon ex vivo challenge with self-antigen, showed a Th2 and Th17 bias, and diminished the diabetogenic property in NOD-Rag1 deficient mice suggesting a disease protective immune modulation under Gastrin-MSC treatment associated protection from hyperglycaemia. Overall, this study shows the potential of production and delivery of Gastrin in vivo, by MSCs, in protecting insulin-producing β-cells and ameliorating the disease progression in T1D.

Gastrin/CCK-B Receptor Signaling Promotes Cell Invasion and Metastasis by Upregulating MMP-2 and VEGF Expression in Gastric Cancer

Accumulated evidence suggests that a functional loop composed of gastrin and cholecystokinin B receptor (CCK-BR) may exist in gastric carcinogenesis. However, this suggestion is not completely supported due to a lack of direct evidence, and the underlying mechanism is not completely understood. Here, we evaluated the effects of gastrin/CCK-BR signaling on the cell growth, invasion, and expression of MMP-2 and VEGF, as well as xenograft growth in vivo. Furthermore, we detected gastrin mRNA content in human gastric cancer tissues, metastatic lymph nodes, and adjacent nontumor tissues. We found that the forced gastrin could promote the proliferation, migration, and invasion of gastric cancer cells by upregulating the expression of MMP-2 and VEGF. Blocking gastrin/CCK-BR signal using either Proglumide, a CCK-BR antagonist, or shRNA against GASTRIN significantly inhibited the gastrin-promoting effects. In vivo study revealed that the tumor growth in nude mice inoculated with gastrin-overexpressed cells was significantly faster than control cells. The gastrin mRNA content in metastatic lymph nodes was higher in patients with gastric cancer than in primary gastric cancer and adjacent nontumor tissues. In conclusion, we provided direct evidence and possible mechanism of gastrin/CCK-BR signaling in the initiation and progression of gastric cancer.

Elucidating Gold-MnO2 Core-Shell Nanoenvelope for Real Time SERS-Guided Photothermal Therapy on Pancreatic Cancer Cells

Pancreatic cancer represents one of the most aggressive in nature with a miserable prognosis that warrants efficient diagnostic and therapeutic interventions. Herein, a MnO₂ overlaid gold nanoparticle (AuNPs) based photothermal theranostic nanoenvelope (PTTNe:MnO₂@AuNPs) was fabricated to substantiate surface-enhanced Raman spectroscopy (SERS) guided real-time monitoring of photothermal therapy (PTT) in pancreatic cancer cells. A sharp enhancement of the fingerprint Raman signature of MnO₂ at 569 cm^-1 exhibited as a marker peak for the first time to elucidate the intracellular PTT event. In this strategic design, the leftover bare AuNPs after the degradation of the MnO₂ layer from the nanoenvelope in the presence of intracellular H₂O₂ enabled real-time tracking of biomolecular changes of Raman spectral variations during PTT. Moreover, the surface of the as-synthesized nanoenvelope was functionalized with a pancreatic cancer cell targeting peptide sequence for cholecystokinin fashioned the PTTNe with admirable stability and biocompatibility. Finally, the precise cell death mechanism was explicitly assessed by SERS spectral analysis as a complementary technique. This targeted phototheranostic approach demonstrated in pancreatic cancer cells presented a therapeutically viable prototype for futuristic personalized cancer nanomedicine.

Emerging trends of receptor-mediated tumor targeting peptides: A review with perspective from molecular imaging modalities

Natural peptides extracted from natural components such are known to have a relatively short in-vivo half-life and can readily metabolize by endo- and exo-peptidases. Fortunately, synthetic peptides can be easily manipulated to increase in-vivo stability, membrane permeability and target specificity with some well-known natural families. Many natural as well as synthetic peptides target to their endogenous receptors for diagnosis and therapeutic applications. In order to detect these peptides externally, they must be modified with radionuclides compatible with single photon emission computed tomography (SPECT) or positron emission tomography (PET). Although, these techniques mainly rely on physiological changes and have profound diagnostic strength over anatomical modalities such as MRI and CT. However, both SPECT and PET observed to possess lack of anatomical reference frame which is a key weakness of these techniques, and unfortunately, cannot be available freely in most clinical centres especially in under-developing countries. Hence, it is need of the time to design and develop economic, patient friendly and versatile strategies to grapple with existing problems without any hazardous side effects. Optical molecular imaging (OMI) has emerged as a novel technique in field of medical science using fluorescent probes as imaging modality and has ability to couple with organic drugs, small molecules, chemotherapeutics, DNA, RNA, anticancer peptide and protein without adding chelators as necessary for radionuclides. Furthermore, this review focuses on difference in imaging modalities and provides ample knowledge about reliable, economic and patient friendly optical imaging technique rather radionuclide-based imaging techniques.

Diagnostic and therapeutic potencies of miR-18a-5p in mixed-type gastric adenocarcinoma

Mixed-type gastric adenocarcinoma (by Lauren Classification) has poor clinical outcomes with few targeted treatment options. The primary objective of this study was to find the prognostic factors, accurate treatment approaches, and effective postoperative adjuvant therapy strategies for patients with mixed-type gastric adenocarcinoma (GA). A microRNA sequencing data set and the corresponding clinical parameters of patients with gastric cancer were obtained from The Cancer Genome Atlas. Differentially expressed microRNAs (DEMs) of diffuse- and intestinal-type GA were, respectively, determined. Kaplan-Meier and log-rank tests were subsequently carried out to evaluate the prognostic relevance of each DEM. To study the common factors between diffuse- and intestinal-type GA, a pathway enrichment analysis was performed on the target genes of identified DEMs using the PANTHER database. After data preprocessing, we analyzed a total of 230 samples from 210 patients with GA. Eighty-six DEMs in diffuse-type GA samples and 59 DEMs in intestinal-type GA samples were, respectively, identified (p  2.0). The Kaplan-Meier survival method further screened out six prognosis-related DEMs for diffuse-type GA and seven prognosis-related DEMs for intestinal-type GA (p < 0.05). MiR-18a-5p was found to be the only common prognosis-related DEM between diffuse- and intestinal-type GA. The common signaling pathways further revealed that target genes of miR-18a-5p are involved in mixed-type GA progression. This study suggests that miR-18a-5p acts as a potential target for treatment, and common signal pathways provide a rich basis to seek reliable and effective molecular targets for the diagnosis, clinical treatment, and postoperative adjuvant therapy strategy of mixed-type GA.

Knockdown of Gastrin Promotes Apoptosis of Gastric Cancer Cells by Decreasing ROS Generation

Overexpressed gastrin is reported to promote oncogenesis and development of gastric cancer by inhibiting apoptosis of cancer cells; however, the underlying mechanism remains unclear. Our study is aimed at revealing the mechanism underlying the effect of gastrin on apoptosis of gastric cancer cells. Gastrin-interfering cell line was constructed by stably transfecting gastrin-specific pshRNA plasmid to gastric cancer cell line BGC-823. Then, differentially expressed proteins between untreated BGC-823 and gastrin-interfering BGC-823 cell lines were detected by the iTRAQ technique. GO and KEGG analysis was used to analyze the differentially expressed genes that code these differentially expressed proteins. The Annexin V-FITC staining assay was used to detect gastric cancer cell apoptosis. The DCFH-DA fluorescent probe staining assay was used to measure intracellular ROS. Mitochondrial membrane potential was detected by flow cytometry. Western blot was used to analyze the mitochondria respiratory chain proteins and apoptosis-related proteins. A total of 107 differentially expressed proteins were identified by iTRAQ. GO and KEGG analysis showed that proteins coded by the corresponding differentially expressed genes were mainly enriched in the mitochondrial oxidative respiratory chain, and the expression of three proteins (COX17, COX5B, ATP5J) was upregulated. The three proteins with higher scores were verified by Western blot. The apoptosis rate of the gastrin knockdown cancer cell was significantly increased; meanwhile, gastrin knockdown leads to increase of membrane potential and decrease of intracellular ROS production. Additionally, Bax was significantly increased, whereas NF-κB-p65 and Bcl-2 were downregulated after knockdown of gastrin. Concomitantly, pretreatment with NAC reversed the effect of gastrin on the Bax and Bcl-2 expression. Gastrin promotes the production of ROS from mitochondria, activates NF-κB, and inhibits apoptosis via modulating the expression level of Bcl-2 and Bax.

Targeting the Cholecystokinin Receptor: A Novel Approach for Treatment and Prevention of Hepatocellular Cancer

Hepatocellular carcinoma (HCC) is the fastest growing cancer worldwide in part due to the obesity epidemic and fatty liver disease, particularly nonalcoholic steatohepatitis (NASH). Chronic inflammation with the release of cytokines and chemokines with activation of hepatic stellate cells results in changes of the liver extracellular matrix (ECM) that predisposes to the development of HCC. Blood levels of the gastrointestinal peptide cholecystokinin (CCK) are increased in humans and mice consuming a high-fat diet. We found that the CCK-B receptor (CCK-BR) expression increased in the livers of mice with NASH. Treatment of mice with a CCK-BR antagonist, proglumide, prevented NASH, lowered hepatic inflammatory cytokines and chemokines, reduced oxidative stress, decreased F4/80⁺ hepatic macrophages, and prevented HCC. CCK-AR and CCK-BR expression was increased in both murine and human HCC cell lines compared with that of normal liver, and CCK stimulated the growth of wild-type and CCK-A receptor knockout HCC cells in vitro, but not CCK-BR knockout cells suggesting that the CCK-BR mediates proliferation. Proglumide therapy significantly reduced growth by 70% and 73% in mice bearing Dt81Hepa1-6 or in RIL-75 HCC tumors, respectively. IHC of a human liver tissue array with a selective CCK-BR antibody revealed staining of human HCC and no staining in normal liver. PREVENTION RELEVANCE: This investigation demonstrates the role of the gastrointestinal peptide cholecystokinin (CCK) in hepatocellular carcinoma (HCC) and how CCK-BR blockade reverses the premalignant state of the hepatic extracellular matrix hence, rendering it less susceptible to the development of HCC. Thereby, CCK-BR blockade is a novel approach for the prevention/treatment of HCC.

Comparative analysis of three data mining techniques in diagnosis of lung cancer

There is a lot of abnormal information in the development of lung cancer, and how to extract useful knowledge is urgent from massive information. Data mining technology has become a popular tool for medical classification and prediction. However, each technology has its advantage and disadvantage, and several data mining methods will be applied to conduct the in-depth analysis step by step. And the prediction results of different models are compared. A total of 180 lung cancer patients and 243 lung benign individuals were collected from the First Affiliated Hospital of Zhengzhou University from October 2014 to March 2016, and the prediction models based on epidemiological data, clinical features and tumor markers were developed by artificial neural network (ANN), decision tree C5.0 and support vector machine (SVM). The results showed that there were significant differences between the lung cancer group and the lung benign group in terms of seven tumor markers and 10 epidemiological and clinical indicators. The accuracy rates of ANN, C5.0 and SVM were 76.47, 89.92 and 85.71%, respectively. The results of receiver operating characteristic curve (ROC) curve revealed the area under the ROC curve (AUC) of ANN was 0.811 (0.770-0.847), the AUC of C5.0 was 0.897 (0.864-0.924) and the AUC of SVM was 0.878 (0.843-0.908). It was shown that the decision tree C5.0 model has the least error rate and highest accuracy, and it could be used to diagnose lung cancer.

Does the Use of Proton Pump Inhibitors Increase the Risk of Pancreatic Cancer? A Systematic Review and Meta-Analysis of Epidemiologic Studies

Background: One of the most frequently used medications for treating gastrointestinal disorders is proton pump inhibitor (PPI), which reportedly has potential adverse effects. Although the relationship between the use of PPIs and the risk of pancreatic cancer has been extensively investigated, the results remain inconsistent. Hence, this meta-analysis aimed to evaluate such relationship. Methods: We searched for literature and subsequently included 10 studies (seven case–control and three cohort studies; 948,782 individuals). The pooled odds ratio (OR) and 95% confidence intervals (CI) for pancreatic cancer were estimated using a random-effects model. We also conducted sensitivity analysis and subgroup analysis. Results: The pooled OR of the meta-analysis was 1.698 (95% CI: 1.200–2.402, p = 0.003), with a substantial heterogeneity (I² = 98.75%, p < 0.001). Even when studies were excluded one by one, the pooled OR remained statistically significant. According to the stratified subgroup analyses, PPI use, and pancreatic cancer incidence were positively associated, regardless of the study design, quality of study, country, and PPI type. Conclusion: PPI use may be associated with the increased risk of pancreatic cancer. Hence, caution is needed when using PPIs among patients with a high risk of pancreatic cancer.

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.

Group II p21-activated kinase, PAK4, is needed for activation of focal adhesion kinases, MAPK, GSK3, and β-catenin in rat pancreatic acinar cells

PAK4 is the only member of the Group II p21-activated kinases (PAKs) present in rat pancreatic acinar cells and is activated by gastrointestinal hormones/neurotransmitters stimulating PLC/cAMP and by various pancreatic growth factors. However, little is known of the role of PAK4 activation in cellular signaling cascades in pancreatic acinar cells. In the present study, we examined the role of PAK4's participation in five different cholecystokinin-8 (CCK-8)-stimulated signaling pathways (PI3K/Akt, MAPK, focal adhesion kinase, GSK3, and β-catenin), which mediate many of its physiological acinar-cell effects, as well as effects in pathophysiological conditions. To define PAK4's role, the effect of two different PAK4 inhibitors, PF-3758309 and LCH-7749944, was examined under experimental conditions that only inhibited PAK4 activation and not activation of the other pancreatic PAK, Group I PAK2. The inhibitors' effects on activation of these five signaling cascades by both physiological and pathophysiological concentrations of CCK, as well as by 12-O-tetradecanoylphobol-13-acetate (TPA), a PKC-activator, were examined. CCK/TPA activation of focal adhesion kinases(PYK2/p125^FAK) and the accompanying adapter proteins (paxillin/p130^CAS), Mek1/2, and p44/42, but not c-Raf or other MAPKs (JNK/p38), were mediated by PAK4. Activation of PI3K/Akt/p70s6K was independent of PAK4, whereas GSK3 and β-catenin stimulation was PAK4-dependent. These results, coupled with recent studies showing PAK4 is important in pancreatic fluid/electrolyte/enzyme secretion and acinar cell growth, show that PAK4 plays an important role in different cellular signaling cascades, which have been shown to mediate numerous physiological and pathophysiological processes in pancreatic acinar cells.NEW & NOTEWORTHY In pancreatic acinar cells, cholecystokinin (CCK) or 12-O-tetradecanoylphobol-13-acetate (TPA) activation of focal adhesion kinases (p125^FAK,PYK2) and its accompanying adapter proteins, p130CAS/paxillin; Mek1/2, p44/42, GSK3, and β-catenin are mediated by PAK4. PI3K/Akt/p70s6K, c-Raf, JNK, or p38 pathways are independent of PAK4 activation.

Permanent Photodynamic Activation of the Cholecystokinin 2 Receptor

The cholecystokinin 2 receptor (CCK2R) is expressed in the central nervous system and peripheral tissues, playing an important role in higher nervous and gastrointestinal functions, pain sensation, and cancer growth. CCK2R is reversibly activated by cholecystokinin or gastrin, but whether it can be activated permanently is not known. In this work, we found that CCK2R expressed ectopically in CHO-K1 cells was permanently activated in the dark by sulfonated aluminum phthalocyanine (SALPC / AlPcS4, 10-1,000 nM), as monitored by Fura-2 fluorescent calcium imaging. Permanent CCK2R activation was also observed with AlPcS2, but not PcS4. CCK2R previously exposed to SALPC (3 and 10 nM) was sensitized by subsequent light irradiation (> 580 nm, 31.5 mW·cm-2). After the genetically encoded protein photosensitizer mini singlet oxygen generator (miniSOG) was fused to the N-terminus of CCK2R and expressed in CHO-K1 cells, light irradiation (450 nm, 85 mW·cm-2) activated in-frame CCK2R (miniSOG-CCK2R), permanently triggering persistent calcium oscillations blocked by the CCK2R antagonist YM 022 (30 nM). From these data, it is concluded that SALPC is a long-lasting CCK2R agonist in the dark, and CCK2R is photogenetically activated permanently with miniSOG as photosensitizer. These properties of SALPC and CCK2R could be used to study CCK2R physiology and possibly for pain and cancer therapies.

The current status of anti-GPCR drugs against different cancers

G protein coupled receptors (GPCRs) have emerged as the most potential target for a number of drug discovery programs ranging from control of blood pressure, diabetes, cure for genetic diseases to treatment of cancer. A panel of different ligands including hormones, peptides, ions and small molecules is responsible for activation of these receptors. Molecular genetics has identified key GPCRs, whose mutations or altered expressions are linked with tumorgenicity. In this review, we discussed recent advances regarding the involvement of GPCRs in the development of cancers and approaches to manipulating the mechanism behind GPCRs involved tumor growth and metastasis to treat different types of human cancer. This review provides an insight into the current scenario of GPCR-targeted therapy, progress to date and the challenges in the development of anticancer drugs.

Gastric Peptides-Gastrin and Somatostatin

Gastric acid secretion (i) facilitates digestion of protein as well as absorption of micronutrients and certain medications, (ii) kills ingested microorganisms, including Helicobacter pylori, and (iii) prevents bacterial overgrowth and enteric infection. The principal regulators of acid secretion are the gastric peptides gastrin and somatostatin. Gastrin, the major hormonal stimulant for acid secretion, is synthesized in pyloric mucosal G cells as a 101-amino acid precursor (preprogastrin) that is processed to yield biologically active amidated gastrin-17 and gastrin-34. The C-terminal active site of gastrin (Trp-Met-Asp-Phe-NH₂ ) binds to gastrin/CCK₂ receptors on parietal and, more importantly, histamine-containing enterochromaffin-like (ECL) cells, located in oxyntic mucosa, to induce acid secretion. Histamine diffuses to the neighboring parietal cells where it binds to histamine H₂ -receptors coupled to hydrochloric acid secretion. Gastrin is also a trophic hormone that maintains the integrity of gastric mucosa, induces proliferation of parietal and ECL cells, and is thought to play a role in carcinogenesis. Somatostatin, present in D cells of the gastric pyloric and oxyntic mucosa, is the main inhibitor of acid secretion, particularly during the interdigestive period. Somatostatin exerts a tonic paracrine restraint on gastrin secretion from G cells, histamine secretion from ECL cells, and acid secretion from parietal cells. Removal of this restraint, for example by activation of cholinergic neurons during ingestion of food, initiates and maximizes acid secretion. Knowledge regarding the structure and function of gastrin, somatostatin, and their respective receptors is providing novel avenues to better diagnose and manage acid-peptic disorders and certain cancers. Published 2020. Compr Physiol 10:197-228, 2020.

Vaccine against gastrin, a polyclonal antibody stimulator, decreases pancreatic cancer metastases

Growth of pancreatic cancer is stimulated by gastrin in both a paracrine and an autocrine fashion. Traditional therapies have not significantly improved survival, and recently pancreatic cancer has been deemed a "cold" tumor due to its poor response to immunotherapy. Strategies to improve survival of pancreatic cancer are desperately needed. In the current investigation, we studied the effects of an anti-gastrin cancer vaccine, polyclonal antibody stimulator (PAS; formerly called G17DT and Gastrimmune), used alone or in combination with a programmed cell death receptor (PD)-1 immune checkpoint antibody on pancreatic cancer growth, metastases, and the tumor microenvironment (TME). Immune-competent female C57BL/6 mice bearing syngeneic orthotopic murine pancreatic cancer treated with PAS had significantly smaller tumors and fewer metastases. Examination of the TME demonstrated decreased fibrosis with fewer M2 and more M1 tumor-associated macrophages. Expression of the E-cadherin gene was significantly increased and expression of the TGFβR2 gene was decreased compared with controls. Mice treated with PAS or the combination of PAS and PD-1 antibody exhibited significantly less tumor expression of phospho-paxillin, the focal adhesion protein β-catenin, and matrix metalloproteinase-7. This study suggests that inhibition of the cancer-promoting effects of gastrin in pancreatic cancer can decrease metastases by altering the TME and decreasing pathways that activate the epithelial mesenchymal transition. The PAS vaccine appears to change the TME, making it more susceptible to therapy with an immune checkpoint antibody. This novel combination of two immunotherapies may improve survival of pancreatic cancer by decreasing both tumor growth and metastasis formation.NEW & NOTEWORTHY Survival from advanced pancreatic cancer is poor, in part due to dense fibrosis of the tumor microenvironment, increased number of M2-polarized macrophages that promote angiogenesis and invasion, and lack of "target-specific" therapy. Herein, we report that a tumor vaccine that selectively targets gastrin decreases pancreatic cancer growth and metastases. Furthermore, the gastrin vaccine polyclonal antibody stimulator alters the tumor microenvironment rendering it more responsive to immunotherapy with a programmed cell death receptor-1 immune checkpoint antibody.

Insights into Effects/Risks of Chronic Hypergastrinemia and Lifelong PPI Treatment in Man Based on Studies of Patients with Zollinger-Ellison Syndrome

The use of proton pump inhibitors (PPIs) over the last 30 years has rapidly increased both in the United States and worldwide. PPIs are not only very widely used both for approved indications (peptic ulcer disease, gastroesophageal reflux disease (GERD), Helicobacter pylori eradication regimens, stress ulcer prevention), but are also one of the most frequently off-label used drugs (25–70% of total). An increasing number of patients with moderate to advanced gastroesophageal reflux disease are remaining on PPI indefinitely. Whereas numerous studies show PPIs remain effective and safe, most of these studies are <5 years of duration and little data exist for >10 years of treatment. Recently, based primarily on observational/epidemiological studies, there have been an increasing number of reports raising issues about safety and side-effects with very long-term chronic treatment. Some of these safety issues are related to the possible long-term effects of chronic hypergastrinemia, which occurs in all patients taking chronic PPIs, others are related to the hypo-/achlorhydria that frequently occurs with chronic PPI treatment, and in others the mechanisms are unclear. These issues have raised considerable controversy in large part because of lack of long-term PPI treatment data (>10–20 years). Zollinger–Ellison syndrome (ZES) is caused by ectopic secretion of gastrin from a neuroendocrine tumor resulting in severe acid hypersecretion requiring life-long antisecretory treatment with PPIs, which are the drugs of choice. Because in <30% of patients with ZES, a long-term cure is not possible, these patients have life-long hypergastrinemia and require life-long treatment with PPIs. Therefore, ZES patients have been proposed as a good model of the long-term effects of hypergastrinemia in man as well as the effects/side-effects of very long-term PPI treatment. In this article, the insights from studies on ZES into these controversial issues with pertinence to chronic PPI use in non-ZES patients is reviewed, primarily concentrating on data from the prospective long-term studies of ZES patients at NIH.

Use of proton pump inhibitors and the risk of hepatocellular carcinoma: A systematic review and meta-analysis

BACKGROUND

Worldwide, proton pump inhibitors (PPIs) are commonly used for the treatment of peptic ulcer and gastro-esophageal reflux disease. Recently, concern has arisen over the potential association between PPIs and hepatocellular carcinoma (HCC). The aim of the current study was to evaluate the influence of PPI use on the risk of HCC, through a systematic review and meta-analysis.

METHODS

A review of all English-language literature was conducted, using the subject search terms: "hepatocellular carcinoma", "liver cancer", "hepatic tumor", and "proton pump inhibitor" in the major medical databases. A meta-analysis of the qualifying publications was then performed.

RESULTS

A total of five studies, which had shown that PPIs were associated with HCC (crude risk ratio [RR] = 2.27, 95% confidence interval [CI]: 1.44-3.57; p < 0.01) when an unadjusted RR were adopted, were eligible for meta-analysis. It was observed that the cumulative dose of PPIs may increase the risk of HCC in a linear model (p < 0.01). However, when using data that were adjusted by comorbidities and concurrent medications, the association between PPIs and HCC became insignificant (adjusted RR = 1.62, 95% CI: 0.89-2.93; p = 0.11) and this result was consistent in the sensitivity analysis.

CONCLUSION

The current meta-analysis has shown that PPI use does not significantly increase the risk of HCC after adjusting for confounding factors. However, further studies are warranted to verify the association between PPIs and HCC in special populations, such as viral or alcoholic liver diseases.

Endogenous Gastrin Collaborates With Mutant KRAS in Pancreatic Carcinogenesis

OBJECTIVE

The KRAS gene is the most frequently mutated gene in pancreatic cancer, and no successful anti-Ras therapy has been developed. Gastrin has been shown to stimulate pancreatic cancer in an autocrine fashion. We hypothesized that reactivation of the peptide gastrin collaborates with KRAS during pancreatic carcinogenesis.

METHODS

LSL-Kras; P48-Cre (KC) mutant KRAS transgenic mice were crossed with gastrin-KO (GKO) mice to develop GKO/KC mice. Pancreata were examined for 8 months for stage of pancreatic intraepithelial neoplasia lesions, inflammation, fibrosis, gastrin peptide, and microRNA expression. Pancreatic intraepithelial neoplasias from mice were collected by laser capture microdissection and subjected to reverse-phase protein microarray, for gastrin and protein kinases associated with signal transduction. Gastrin mRNA was measured by RNAseq in human pancreatic cancer tissues and compared to that in normal pancreas.

RESULTS

In the absence of gastrin, PanIN progression, inflammation, and fibrosis were significantly decreased and signal transduction was reversed to the canonical pathway with decreased KRAS. Gastrin re-expression in the PanINs was mediated by miR-27a. Gastrin mRNA expression was significantly increased in human pancreatic cancer samples compared to normal human pancreas controls.

CONCLUSIONS

This study supports the mitogenic role of gastrin in activation of KRAS during pancreatic carcinogenesis.

Prospective Evaluation of Results of Reoperation in Zollinger-Ellison Syndrome

OBJECTIVE

To determine the role of reoperation in patients with persistent or recurrent Zollinger-Ellison Syndrome (ZES).

BACKGROUND

Approximately, 0% to 60% of ZES patients are disease-free (DF) after an initial operation, but the tumor may recur.

METHODS

A prospective database was queried.

RESULTS

A total of 223 patients had an initial operation for possible cure of ZES and then were subsequently evaluated serially with cross sectional imaging-computed tomography, magnetic resonance imaging, ultrasound, more recently octreoscan-and functional studies for ZES activity. The mean age at first surgery was 49 years and with an 11-year mean follow-up 52 patients (23%) underwent reoperation when ZES recurred with imageable disease. Results in this group are analyzed in the current report. Reoperation occurred on a mean of 6 years after the initial surgery with a mean number of reoperations of 1 (range 1-5). After reoperation 18/52 patients were initially DF (35%); and after a mean follow-up of 8 years, 13/52 remained DF (25%). During follow-up, 9/52 reoperated patients (17%) died, of whom 7 patients died a disease-related death (13%). The overall survival from first surgery was 84% at 20 years and 68% at 30 years. Multiple endocrine neoplasia type 1 status did not affect survival, but DF interval and liver metastases did.

CONCLUSIONS

These results demonstrate that a significant proportion of patients with ZES will develop resectable persistent or recurrent disease after an initial operation. These patients generally have prolonged survival after reoperation and 25% can be cured with repeat surgery, suggesting all ZES patients postresection should have systematic imaging, and if tumor recurs, advise repeat operation.

Proton Pump Inhibitor Use is Associated With Risk of Pancreatic Cancer: A Nested Case-Control Study

Purpose:

To investigate the use of proton pump inhibitors (PPIs) and the risk of pancreatic cancer.

Methods:

A nested case–control analysis was conducted. Patients with pancreas cancer were matched with controls by propensity score. Univariate and multivariate logistic regression models were used to determine whether PPIs use affected the risk of pancreas cancer. Dose effect was analyzed based on the cumulative defined daily dose (DDD), which was calculated using the total supply of PPIs to individual patients in terms of days and quantity.

Results:

A total of 1087 patients with pancreas cancer were matched with 1087 control patients from the database. The overall adjusted odds ratio (OR) of PPI use associated with pancreas cancer was 1.69 (95% confidence interval [CI], 1.44-2.05). Dose analysis by cumulative DDD, based on all types of PPI combined, revealed a lower adjusted OR of 0.92 (95% CI, 0.64-1.33) for those on <30 cumulative DDD compared with those on ≥150 cumulative DDD, whose adjusted OR was 2.19 (95% CI, 1.68-2.85). Compared with PPI nonusers, the risks of pancreas cancer were: OR 0.89 (95% CI, 0.62-1.27) for patients using PPI <30 days and 2.22 (95% CI, 1.68-2.94) for ≥150 days.

Conclusions:

Risk of pancreas cancer was associated with PPI use in patients with peptic ulcer diseases or gastroesophageal reflux disease.

Utilizing Peptide Ligand GPCRs to Image and Treat Pancreatic Cancer

It is estimated that early detection of pancreatic ductal adenocarcinoma (PDAC) could increase long-term patient survival by as much as 30% to 40% (Seufferlein, T. et al., Nat. Rev. Gastroenterol. Hepatol.2016, 13, 74–75). There is an unmet need for reagents that can reliably identify early cancerous or precancerous lesions through various imaging modalities or could be employed to deliver anticancer treatments specifically to tumor cells. However, to date, many PDAC tumor-targeting strategies lack selectivity and are unable to discriminate between tumor and nontumor cells, causing off-target effects or unclear diagnoses. Although a variety of approaches have been taken to identify tumor-targeting reagents that can effectively direct therapeutics or imaging agents to cancer cells (Liu, D. et al., J. Controlled Release2015, 219, 632–643), translating these reagents into clinical practice has been limited, and it remains an area open to new methodologies and reagents (O’Connor, J.P. et al., Nat. Rev. Clin. Oncol. 2017, 14, 169–186). G protein–coupled receptors (GPCRs), which are key target proteins for drug discovery and comprise a large proportion of currently marketed therapeutics, hold significant promise for tumor imaging and targeted treatment, particularly for pancreatic cancer.

Peptides for optical medical imaging and steps towards therapy

Optical medical imaging is a rapidly growing area of research and development that offers a multitude of healthcare solutions both diagnostically and therapeutically. In this review, some of the most recently described peptide-based optical probes are reviewed with a special emphasis on their in vivo use and potential application in a clinical setting.

New Insights in the Design of Bioactive Peptides and Chelating Agents for Imaging and Therapy in Oncology

Many synthetic peptides have been developed for diagnosis and therapy of human cancers based on their ability to target specific receptors on cancer cell surface or to penetrate the cell membrane. Chemical modifications of amino acid chains have significantly improved the biological activity, the stability and efficacy of peptide analogues currently employed as anticancer drugs or as molecular imaging tracers. The stability of somatostatin, integrins and bombesin analogues in the human body have been significantly increased by cyclization and/or insertion of non-natural amino acids in the peptide sequences. Moreover, the overall pharmacokinetic properties of such analogues and others (including cholecystokinin, vasoactive intestinal peptide and neurotensin analogues) have been improved by PEGylation and glycosylation. Furthermore, conjugation of those peptide analogues to new linkers and bifunctional chelators (such as AAZTA, TETA, TRAP, NOPO etc.), produced radiolabeled moieties with increased half life and higher binding affinity to the cognate receptors. This review describes the most important and recent chemical modifications introduced in the amino acid sequences as well as linkers and new bifunctional chelators which have significantly improved the specificity and sensitivity of peptides used in oncologic diagnosis and therapy.

Curcumin suppresses gastric cancer by inhibiting gastrin-mediated acid secretion

Hyperacidity in the stomach is known to promote the progression of gastric cancer. The plant-derived chemotherapeutic curcumin is used to treat gastric cancer. The objective of this study was to investigate whether curcumin regulates gastrin-mediated acid secretion in suppressing gastric cancer. Gastric cancer cells were treated with 25 μm curcumin, followed by Annexin V/propidium iodide double-staining assay to evaluate cell apoptosis. Western blot analysis was used to analyze caspase-3 expression in response to curcumin treatment. Gastrin levels in culture medium were also monitored. Mice bearing gastric cancers were treated with curcumin, followed by analysis of tumor caspase-3 expression, gastric acid pH, and gastric secretion in serum. Curcumin prominently inhibited gastric cancer cell proliferation and promoted cell apoptosis. Caspase-3 was upregulated by curcumin treatment. Curcumin also reduced gastrin secretion. Curcumin dramatically inhibited tumor growth, increased gastric pH, and reduced gastric secretion. In gastric cancer, curcumin suppresses gastrin-mediated acid secretion, which inhibits gastric cancer progression.

Identification of potent cholecystokinin-B receptor antagonists: synthesis, molecular modeling and anti-cancer activity against pancreatic cancer cells

Advanced malignant stages of pancreatic cancer have poor prognosis and very few treatment strategies are available. Pancreatic cancer is known to possess unique growth-related receptors that when activated, stimulate tumour proliferation. Gastrin and its related peptide cholecystokinin (CCK) are also significantly involved in the growth of this cancer type as well as other malignancies through activation of the cholecystokinin-B receptor (CCK-BR). New treatment strategies with CCK-BR antagonists are being suggested that suppress the growth promoting effects of gastrin. In this paper, we report the development of two series of quinazolinone derivatives incorporating hydrazinecarbothioamide (compounds 3a-g) and the hydrazino group (compounds 4a-e) as linkers for developing CCK-BR antagonists. The affinities of the compounds were determined using docking into the CCK-BR homology modeled structure. The compounds were tested for in vitro CCK-BR binding and gastric acid secretion in an isolated lumen-perfused mouse stomach assay. The compounds exhibited CCK-BR binding activity (IC₅₀) in the range of 0.2-975 nM and showed good gastric acid secretion inhibitory activity. Molecular modeling of the compounds was done and pharmacophore mapping results showed good prediction of in vitro activity which correlated well with the experimental antagonistic activity. The compounds were further tested for their cytotoxicity on CCK-BR expressing pancreatic cancer cells. The results of the study provided two potent CCK-BR antagonists which also possess good to moderate growth inhibitory activities against pancreatic cancer cells.

Gastrin and Gastric Cancer

Gastric cancer is the third leading cause of cancer-related mortality worldwide. Despite progress in understanding its development, challenges with treatment remain. Gastrin, a peptide hormone, is trophic for normal gastrointestinal epithelium. Gastrin also has been shown to play an important role in the stimulation of growth of several gastrointestinal cancers including gastric cancer. We sought to review the role of gastrin and its pathway in gastric cancer and its potential as a therapeutic target in the management of gastric cancer. In the normal adult stomach, gastrin is synthesized in the G cells of the antrum; however, gastrin expression also is found in many gastric adenocarcinomas of the stomach corpus. Gastrin's actions are mediated through the G-protein-coupled receptor cholecystokinin-B (CCK-B) on parietal and enterochromaffin cells of the gastric body. Gastrin blood levels are increased in subjects with type A atrophic gastritis and in those taking high doses of daily proton pump inhibitors for acid reflux disease. In experimental models, proton pump inhibitor-induced hypergastrinemia and infection with Helicobacter pylori increase the risk of gastric cancer. Understanding the gastrin:CCK-B signaling pathway has led to therapeutic strategies to treat gastric cancer by either targeting the CCK-B receptor with small-molecule antagonists or targeting the peptide with immune-based therapies. In this review, we discuss the role of gastrin in gastric adenocarcinoma, and strategies to block its effects to treat those with unresectable gastric cancer.

Pancreatic Cancer: Current Progress and Future Challenges

Pancreatic ductal adenocarcinoma (PDAC), the most common form of pancreatic cancer, remains one of the highly lethal malignancies. The highly refractory nature of clinically advanced disease and lack of a reliable biomarker for early detection are major obstructions in improving patient outcome. The recent efforts, however, in understanding the pancreatic tumor biology have resulted in the recognition of novel addictions as well as vulnerabilities of tumor cells and are being assessed for their clinical potential. This special issue highlights some of the recent progress, complexity and challenges towards improving disease outcome in patients with this lethal malignancy.