Y2 receptors decrease human pancreatic cancer growth and intracellular cyclic adenosine monophosphate levels

Neuropeptide Y Peptide Family and Cancer: Antitumor Therapeutic Strategies

Currently available data on the involvement of neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) and their receptors (YRs) in cancer are updated. The structure and dynamics of YRs and their intracellular signaling pathways are also studied. The roles played by these peptides in 22 different cancer types are reviewed (e.g., breast cancer, colorectal cancer, Ewing sarcoma, liver cancer, melanoma, neuroblastoma, pancreatic cancer, pheochromocytoma, and prostate cancer). YRs could be used as cancer diagnostic markers and therapeutic targets. A high Y1R expression has been correlated with lymph node metastasis, advanced stages, and perineural invasion; an increased Y5R expression with survival and tumor growth; and a high serum NPY level with relapse, metastasis, and poor survival. YRs mediate tumor cell proliferation, migration, invasion, metastasis, and angiogenesis; YR antagonists block the previous actions and promote the death of cancer cells. NPY favors tumor cell growth, migration, and metastasis and promotes angiogenesis in some tumors (e.g., breast cancer, colorectal cancer, neuroblastoma, pancreatic cancer), whereas in others it exerts an antitumor effect (e.g., cholangiocarcinoma, Ewing sarcoma, liver cancer). PYY or its fragments block tumor cell growth, migration, and invasion in breast, colorectal, esophageal, liver, pancreatic, and prostate cancer. Current data show the peptidergic system's high potential for cancer diagnosis, treatment, and support using Y2R/Y5R antagonists and NPY or PYY agonists as promising antitumor therapeutic strategies. Some important research lines to be developed in the future will also be suggested.

Obesity-related gut hormones and cancer: novel insight into the pathophysiology

The number of cancers attributed to obesity is increasing over time. The mechanisms classically implicated in cancer pathogenesis and progression in patients with obesity involve adiposity-related alteration of insulin, sex hormones, and adipokine pathways. However, they do not fully capture the complexity of the association between obesity-related nutritional imbalance and cancer. Gut hormones are secreted by enteroendocrine cells along the gastrointestinal tract in response to nutritional cues, and act as nutrient sensors, regulating eating behavior and energy homeostasis and playing a role in immune-modulation. The dysregulation of gastrointestinal hormone physiology has been implicated in obesity pathogenesis. For their peculiar function, at the cross-road between nutrients intake, energy homeostasis and inflammation, gut hormones might represent an important but still underestimated mechanism underling the obesity-related high incidence of cancer. In addition, cancer research has revealed the widespread expression of gut hormone receptors in neoplastic tissues, underscoring their implication in cell proliferation, migration, and invasion processes that characterize tumor growth and aggressiveness. In this review, we hypothesize that obesity-related alterations in gut hormones might be implicated in cancer pathogenesis, and provide evidence of the pathways potentially involved.

A novel CpG-methylation-based nomogram predicts survival in colorectal cancer

Aberrant DNA methylation is significantly associated with the prognosis of patients with colorectal cancer (CRC). Therefore, the aim of this study was to develop a CpG-methylation-based nomogram for prognostic prediction in CRC. First, 378 CRC patients with methylation data from The Cancer Genome Atlas were randomly divided into training cohort (n = 249) and test cohort (n = 129). A multistep screening strategy was performed to identify six CpG sites that were significantly associated with overall survival in the training cohort. Then, Cox regression modelling was performed to construct a prognostic signature based on the candidate CpG sites. The six-CpG signature successfully separated patients into high-risk and low-risk groups in both training and test cohorts, and its performance was superior to that of previously published methylation markers (P < 0.05). Furthermore, we established a prognostic nomogram incorporating this signature, TNM stage, and age. The nomogram exhibited better prediction for overall survival in comparison with the three independent prognostic factors in the training cohort (C-index: 0.798 vs 0.620 to 0.737; P < 0.001). In the test cohort, the performance of nomogram was also superior to that of the three independent prognostic factors (C-index: 0.715 vs 0.590 to 0.665; P < 0.05). Meanwhile, the calibration curves for survival probability showed good agreement between prediction by nomogram and actual observation in both training and test cohorts. Together, the present study provides a novel CpG-methylation-based nomogram as a promising predictor for overall survival of CRC patients, which may help improve decision-making regarding the personalized treatments of patients with CRC.

Genes encoding neuropeptide receptors are epigenetic markers in patients with head and neck cancer: a site-specific analysis

Staging and pathological grading systems are useful but imperfect predictors of recurrence in head and neck squamous cell carcinoma (HNSCC). To identify potential prognostic markers, we examined the methylation status of eight neuropeptide receptor gene promoters in 231 head and neck squamous cell carcinomas. The NPFFR1, NPFFR2, HCRTR1, HCRTR2, NPY1R, NPY2R, NPY4R, and NPY5R promoters were methylated in 80.5%, 79.2%, 67.1%, 73.2%, 35.1%, 36.4%, 38.5%, and 35.9% of the samples, respectively. In a multivariate Cox proportional hazards analysis, the odds ratio for recurrence was 2.044 (95% confidence interval [CI], 1.323–3.156; P = 0.001) when the NPY2R promoter was methylated. In patients without lymph node metastasis (n = 100), methylation of NPY2R (compared with methylation of the other seven genes) best correlated with poor disease-free survival (DFS) (odds ratio, 2.492; 95% CI, 1.190–5.215; P = 0.015). In patients with oral cancer (n = 69), methylated NPY1R and NPY2R were independent prognostic factors for poor DFS, both individually and, even more so, in combination (odds ratio, 3.90; 95% CI, 1.523–9.991; P = 0.005). Similar findings were observed for NPY2R and NPY4R in patients with oropharyngeal cancer (n = 162) (odds ratio, 5.663; 95% CI, 1.507–21.28; P = 0.010).

Neuropeptide Y: An Anti-Aging Player?

Accumulating evidence suggests that neuropeptide Y (NPY) has a role in aging and lifespan determination. In this review, we critically discuss age-related changes in NPY levels in the brain, together with recent findings concerning the contribution of NPY to, and impact on, six hallmarks of aging, specifically: loss of proteostasis, stem cell exhaustion, altered intercellular communication, deregulated nutrient sensing, cellular senescence, and mitochondrial dysfunction. Understanding how NPY contributes to, and counteracts, these hallmarks of aging will open new avenues of research on limiting damage related to aging.

Peptide YY mediates inhibition of tumor growth and inflammation

Peptide YY (PYY) orchestrates the functions of the gut and the pancreas by regulating growth, digestion and absorption. In addition to its physiological role, PYY exhibits immune and antitrophic properties in the pancreas by decreasing cytokine and amylase release. Although the exact mechanism(s) of action are still incompletely understood, PYY interacts at the acinar level with numerous intracellular transcription factors. In addition to ameliorating pancreatic inflammation, novel synthetic analogs of PYY have been developed that are potent inhibitors of pancreatic cancer proliferation, in vitro and in vivo. Additionally, PYY and its analogs have been shown to inhibit the growth of breast, esophagus, and gastric cancer in vitro. We, herein, plan to review some of the methods employed in the laboratory while investigating the utility of PYY in the treatment of inflammation and cancer.

Neuropeptide Y Y2 receptor in health and disease

We briefly survey the current knowledge and concepts regarding structure and function of the neuropeptide Y Y2 receptor and its agonists, especially as related to pharmacology of the receptor and its roles in pathological processes. Specific structural features are considered that could be responsible for the known compartmentalization and participation of the receptor in cell and tissue organization. This is further discussed in relation to changes of levels of the Y2 receptor in pathological conditions (especially in epilepsy and drug abuse), to endocytosis and recycling, and to participation in wound healing, retinopathy and angiogenesis. Properties of the receptor and of Y2 agonists are considered and reviewed in connection to the negative regulation of transmitter release, feeding, mood and social behavior. The possible involvement of the Y2 receptor in diabetes, carcinogenesis and bone formation is also reviewed.

PYY and the pancreas: inhibition of tumor growth and inflammation

Peptide YY (PYY) orchestrates function of the gut and pancreas by regulating growth, digestion and absorption. In addition to its physiological role, PYY exhibits immune and antitrophic properties in the pancreas by decreasing cytokine and amylase release. Although the exact mechanism(s) of action are still not fully understood, PYY interacts at the acinar level with numerous intracellular transcription factors. In addition to ameliorating pancreatic inflammation, novel synthetic analogs of PYY have been developed that are potent inhibitors in the proliferation of pancreatic cancer. The present paper reviews our current findings with PYY and examines the therapeutic implications of its utility in treating inflammation and cancer.

Neuropeptide Y in neural crest-derived tumors: effect on growth and vascularization

Neuropeptide Y (NPY) is a sympathetic neurotransmitter recently found to be a potent growth and angiogenic factor. The peptide and its receptors are abundant in neural crest-derived tumors, such as sympathetic neuroblastomas and pheochromocytomas, as well as parasympathetic Ewing's sarcoma family of tumors. NPY regulates their growth directly, by an autocrine activation of tumor cell proliferation or apoptosis, and indirectly, by its angiogenic activity. The overall effect of the peptide on tumor growth depends on a balance between these processes and the type of receptors expressed in the tumor cells. Thus, NPY and its receptors may become targets for the treatment of neural tumors, directed against both tumor cell proliferation and angiogenesis.

Differential effects of neuropeptide Y on the growth and vascularization of neural crest-derived tumors

Neuropeptide Y (NPY) is a sympathetic neurotransmitter recently found to be potently angiogenic and growth promoting for endothelial, vascular smooth muscle and neuronal cells. NPY and its cognate receptors, Y1, Y2 and Y5, are expressed in neural crest-derived tumors; however, their role in regulation of growth is unknown. The effect of NPY on the growth and vascularization of neuroendocrine tumors was tested using three types of cells: neuroblastoma, pheochromocytoma, and Ewing's sarcoma family of tumors (ESFT). The tumors varied in expression of NPY receptors, which was linked to differential functions of the peptide. NPY stimulated proliferation of neuroblastoma cells via Y2/Y5Rs and inhibited ESFT cell growth by Y1/Y5-mediated apoptosis. In both tumor types, NPY receptor antagonists altered basal growth levels, indicating a regulatory role of autocrine NPY. In addition, the peptide released from the tumor cells stimulated endothelial cell proliferation, which suggests its paracrine angiogenic effects. In nude mice xenografts, exogenous NPY stimulated growth of neuroblastoma tumors, whereas it increased apoptosis and reduced growth of ESFT. However, in both tumors, NPY treatment led to an increase in tumor vascularization. Taken together, this is the first report of NPY being a growth-regulatory factor for neuroendocrine tumors, acting both by autocrine activation of tumor cell proliferation or apoptosis and by angiogenesis. NPY and its receptors may become targets for novel approaches in the treatment of these diseases, directed against both tumor cell proliferation and angiogenesis.

Peptide YY inhibits the growth of Barrett's esophageal adenocarcinoma in vitro

BACKGROUND

Peptide YY (PYY) is an endogenous gut hormone that inhibits the growth of certain cancers. Adenocarcinoma of the esophagus usually arises from Barrett's esophagus. We hypothesized that treatment of Barrett's adenocarcinoma with PYY would result in decreased proliferation.

METHODS

Barrett's cancer cell lines (BIC and SEG-1) were treated with PYY (3-36) at 500 pmol/mL. Viability was measured by MTT at 24 and 72 hours. Apoptosis and necrosis was evaluated by flow cytometry.

RESULTS

PYY reduced proliferation in SEG-1 cells at 24 hours (21.2% +/- 3.4%, P <0.001) and 72 hours (14.2% +/- 6.2%, P <0.001). In the BIC cells, growth was inhibited by 7.9% +/- 7.0%, P = 0.021 after 72 hours. PYY increased late apoptotic activity in SEG-1 cells by 31%, P = 0.014.

CONCLUSIONS

This is the first report of antiproliferative effects of PYY against Barrett's carcinoma in vitro. Reductions in cell growth appear to be mediated by proapoptotic mechanisms. Further investigation of PYY in the treatment of Barrett's adenocarcinoma is warranted.

Role of gastrointestinal hormones in the proliferation of normal and neoplastic tissues

Gastrointestinal (GI) hormones are chemical messengers that regulate the physiological functions of the intestine and pancreas, including secretion, motility, absorption, and digestion. In addition to these well-defined physiological effects, GI hormones can stimulate proliferation of the nonneoplastic intestinal mucosa and pancreas. Furthermore, in an analogous fashion to breast and prostate cancer, certain GI cancers possess receptors for GI hormones; growth can be altered by administration of these hormones or by blocking their respective receptors. The GI hormones that affect proliferation, either stimulatory or inhibitory, include gastrin, cholecystokinin, gastrin-releasing peptide, neurotensin, peptide YY, glucagon-like peptide-2, and somatostatin. The effects of these peptides on normal and neoplastic GI tissues will be described. Also, future perspectives and potential therapeutic implications will be discussed.

Inhibition of pancreatic cancer cell growth and induction of apoptosis with novel therapies directed against protein kinase A

BACKGROUND

Pancreatic cancer is the most lethal abdominal malignancy. Expression of the RIalpha subunit of protein kinase A (PKA) has been associated with neoplastic transformation and mitogenic signaling. The effect of PKA inhibition on pancreatic cancer cell growth and apoptosis is unknown. In pancreatic cancer cells, we sought to determine (1) whether inhibition of PKA can inhibit growth or induce apoptosis, and (2) whether growth can be inhibited by silencing of RIalpha expression.

METHODS

Human pancreatic cancer cells (PANC-1, MIA PaCa-2, and SUIT-2) were treated with inhibitors of PKA (H89 or PKI) and cell growth, kinase activity, and induction of apoptosis measured. Small inhibitory RNA (siRNA) directed against the RIalpha subunit was synthesized and transfected into PANC-1 cells.

RESULTS

H89 decreased PKA activity and inhibited pancreatic cancer cell growth. Apoptosis was also induced by H89 in PANC-1 and MIA PaCa-2 cells. PANC-1 cells express high levels of the RIalpha subunit; transfection of siRNA decreased RIalpha protein expression and inhibited growth.

CONCLUSIONS

Inhibition of PKA in pancreatic cancer cells induces growth arrest and apoptosis; similar effects are noted in cells with siRNA used to block RIalpha expression. Inhibition of PKA may represent a novel therapeutic strategy for the adjuvant treatment of pancreatic cancer.

Selective cyclooxygenase-2 inhibitor rofecoxib (Vioxx) induces expression of cell cycle arrest genes and slows tumor growth in human pancreatic cancer

Recent studies indicate that cyclooxygenase-2 (COX-2) is overexpressed in pancreatic adenocarcinoma and may play a critical role in this rapidly progressing form of cancer. A human pancreatic adenocarcinoma cell line, Mia PaCa-2, was incubated for 18 hours with 5 micromol/L of rofecoxib (Vioxx), a selective COX-2 inhibitor. Total RNA was isolated and gene expression analyzed by DNA microarray chips. In a separate experiment, athymic mice were orthotopically injected with 7.5 x 10(5) Mia PaCa-2 cells through a minilaparotomy. After 1 month, laparotomy was repeated to measure tumor size, and mice were randomized to receive reformulated rodent chow containing either 12.5 mg/kg/day of rofecoxib or no drug for 21 days. Tumor growth was assessed by comparing volume before and after treatment. In vitro, rofecoxib decreased gene expression of cyclin D1/PRAD1, a key component of cell cycle progression, while increasing expression of several cell cycle arrest genes, including p21/WAF1, p33/ING, GADD34, and GADD45 (P < 0.05). In vivo, tumor growth was significantly reduced in treated vs. control mice (P < 0.05). No systemic toxicity was observed in mice receiving rofecoxib. These data suggest that rofecoxib slows the growth of human pancreatic cancer through changes in gene expression that favor cell cycle arrest.

Clinical potentials of neuropeptide Y family of hormones

Neuropeptide Y (NPY) family of hormones exhibits a wide spectrum of central and peripheral activities mediated by six G-protein coupled receptor subtypes denoted as Y1, Y2, Y3, Y4, Y5, and y6. Investigations to date have implicated NPY in the pathophysiology of a number of diseases including feeding disorders, seizures, anxiety, diabetes, hypertension, congestive heart failure and intestinal disorders. These observations suggest that long-acting, potent NPY receptor selective agonists and antagonists developed could be used to treat a variety of diseases. These possibilities are discussed in this paper.

Peptide YY and cancer: current findings and potential clinical applications

Peptide YY (PYY) is a naturally occurring gut hormone with mostly inhibitory actions on multiple tissue targets. PYY has been identified in several carcinoid tumors and a decreased expression of PYY may be relevant to the development and progression of colon adenocarcinoma. Treatment with PYY decreases growth in pancreatic and breast tumors, most likely through a reduction in intracellular cAMP. In cancer patients, PYY may also improve malnutrition that results from iatrogenic causes or cachexia associated with advanced disease. PYY plays a significant role in multiple aspects of cancer from regulation of cell growth to potential therapeutic applications.

Vascular endothelial growth factor is increased in ascites from metastatic pancreatic cancer

INTRODUCTION

Vascular endothelial growth factor (VEGF) is an angiogenic factor that increases vascular permeability. VEGF stimulates capillary formation and has mitogenic effects on vascular endothelial cells. The development of malignant ascites causes significant morbidity. We hypothesized that increased levels of VEGF play a role in the development of malignant ascites in patients with pancreatic cancer.

METHODS

Athymic mice underwent orthotopic implantation of human pancreatic ductal adenocarcinoma tumors (250,000 cells) into the body of the pancreas. Tumors were allowed to grow for 12 weeks, at which time ascites develops in 50% of mice. Paracentesis was performed on mice with noticeable ascites. Saline lavage was performed in mice with equivalent pancreatic tumor masses without ascites and served as control. Both ascites and tumor masses were harvested for VEGF protein quantitation by ELISA.

RESULTS

VEGF protein levels were elevated in malignant ascites by 15-fold compared to control mice with equivalent tumors (N = 6, P < 0.001, t test). VEGF levels were slightly higher in the primary tumor masses harvested from mice without ascites. Mice with ascites also had metastatic nodules throughout the abdominal cavity.

CONCLUSIONS

We are reporting for the first time that VEGF levels are increased in the ascites of nude mice with orthotopically transplanted human pancreatic cancers. VEGF increases vascular permeability and allows for extrapancreatic seeding of tumors. Irrespective of primary tumor size, intraperitoneal VEGF levels are increased when ascites and extrapancreatic nodules are present, while a paradoxical decrease is observed in VEGF levels of primary tumors.

Hypericin and photodynamic therapy decreases human pancreatic cancer in vitro and in vivo

BACKGROUND

The treatment of pancreatic cancer has remained dismal despite advances in medical and surgical care. Recent preclinical data have revealed that hypericin, a photochemical dye, is activated by green light and generates toxic radical species in tumors. We hypothesized that interstitial hypericin and laser phototherapy would decrease pancreatic cancer growth.

METHODS

MiaPaCa-2 and PANC-1 cells were grown in tissue culture. In vitro experiments were performed with addition of 10 microg of hypericin/500,000 cancer cells. Cells were incubated with hypericin for 2 h. Cells were then exposed to KTP532 green laser light for 1 min at 0.6 W using a cylindrical diffuser tip. Cell growth was measured by MTT assay 24 h after laser treatment, N = 12. MiaPaCa-2 cells were implanted subcutaneously and orthotopically in pancreas of nude mice. After 5 weeks, both tumors were injected with 100 microg of hypericin followed by insertion of a cylindrical diffuser tip into the tumor center. Mice received 200J KTP laser light at 1.0 W in two sites. Tumors were measured before and 4 weeks after laser treatment.

RESULTS

Both in vitro and in vivo mice data showed a significant decrease in growth of pancreatic cancer. Pancreatic cancer cell growth was suppressed by 66.1 +/- 0.2%, n = 12, P < 0.01, ANOVA. Subcutaneous shoulder tumors were suppressed by 91.2 +/- 2.3%, n = 12, P < 0.001, and orthotopically grown pancreatic tumors were suppressed by 42.2 +/- 8.1%, n = 12, P < 0.05, compared to pretreatment sizes. Data expressed as percentage reduction vs paired controls in the MTT assay and vs pre-photodynamic therapy in mice experiments. Paired Student's t tests were performed vs pretreatment sizes.

CONCLUSION

Both in vitro and in vivo results revealed a significant decrease in pancreatic cancer cell growth. Laser or dye alone had no effect, indicating that intratumor hypericin and laser therapy may prove useful in unresectable pancreatic cancer.

Peptide YY and vitamin E inhibit hormone-sensitive and -insensitive breast cancer cells

We have shown that peptide YY, an endogenous gut hormone, and vitamin E succinate (VES) inhibit pancreatic cancer cell growth in vitro. We hypothesized that PYY and VES would inhibit breast cancer cell viability regardless of the hormone receptor status. Human breast ZR-75 ductal carcinoma (estrogen receptor negative) and MCF-7 adenocarcinoma (estrogen receptor positive) cells were cultured and exposed to VES (10 pg/ml), PYY (500 pmol), or both agents together. MTT assay was performed at 24, 48, and 72 h to evaluate cell viability. At every time interval, PYY and VES significantly inhibited cell growth compared to control. The effects of PYY were similar in magnitude to those of VES. Combining the agents resulted in a significant additive inhibition of growth with the greatest effect seen at 72 h. We have shown that PYY and vitamin E inhibit in vitro growth of breast cancer cells with variable hormone receptor status. When used in combination, the agents have a significant increase in effect. Further studies are ongoing to define the mechanism of action of these agents and to translate the experiments to an in vivo model.

Peptide YY augments gross inhibition by vitamin E succinate of human pancreatic cancer cell growth

BACKGROUND

Vitamin E succinate (VES) significantly inhibits cell growth in vitro in breast, prostate, and skin cancer cell lines. Our study demonstrated similar inhibitory effects on Mia PaCa-2 pancreatic cancer cells at the same concentration of VES (10 pg/ml). Peptide YY (PYY) also inhibits pancreatic cancer cell growth in vitro. We observed a significant additive effect on growth inhibition in Mia PaCa cells treated with both VES and PYY.

METHODS

Human pancreatic ductal adenocarcinoma Mia PaCa-2 cells were cultured and treated once with either 10 pg/ml of VES or 500 pmols of PYY or with both agents together. The control group received an equivalent volume of solvents. MTT assay was performed at 24, 48, and 72 h to evaluate cell viability.

RESULTS

Pancreatic cancer cell growth was reduced in all groups treated with PYY and VES. Student's t test was used to analyze the data for each treatment group. At 72 h, both PYY and vitamin E significantly inhibited cell growth compared to control. Combining the agents resulted in a dramatic additive inhibition of growth.

CONCLUSION

PYY and vitamin E both inhibit growth of pancreatic cancer cells in vitro with a significant increase in effect when used in combination.

Peptide YY inhibits growth of human breast cancer in vitro and in vivo

BACKGROUND

Hormonal manipulation is important in the treatment of breast cancer. Gastrointestinal hormones may have antiproliferative effects on malignancies arising outside the gastrointestinal tract. Peptide YY (PYY) suppresses growth of, and levels of, intracellular cyclic adenosine monophosphate (cAMP) in pancreatic adenocarcinoma. We hypothesized that PYY would inhibit growth of breast cancer.

MATERIALS AND METHODS

MCF-7 human breast infiltrative ductal carcinoma cells in 96-well plates were treated with PYY at 1.25 pmol/mcl. Control wells received an equal volume of bovine serum albumin to mimic experimental conditions. In vitro survival was determined by MTT assays, which reflect cell viability by measuring mitochondrial NADH-dependent dehydrogenase activity. MCF-7 cells in six-well plates were treated with PYY or albumin as described above. Intracellular cAMP levels in cell lysates were determined with a tritiated cAMP assay. One million MCF-7 cells were injected into mammary fat pads of 20 female athymic nude mice. Pellets releasing PYY at 400 pmol/kg/h were placed subcutaneously in 10 mice 24 h prior to cell inoculation. Tumors were harvested after 21 days, weighed, and measured with vernier calipers.

RESULTS

PYY reduced in vitro growth by 40% (P < 0.001). Intracellular cAMP levels in PYY-treated cells were 62.4% less than those of controls (P < 0.001). Tumors from control mice weighed twice as much as those from PYY-treated mice (P < 0.006); volume of PYY-exposed tumors was one-third that of controls (P < 0.005).

CONCLUSIONS

PYY inhibits growth of breast cancer in vitro and in vivo and may be of benefit in the treatment of this malignancy. The reduction in intracellular cAMP levels may contribute to the observed suppression of cell proliferation.

Gastrointestinal hormones as potential adjuvant treatment of exocrine pancreatic adenocarcinoma

CONCLUSION

Gastrointestinal hormones and their antagonists can alter the growth of pancreatic adenocarcinoma in vitro and in vivo. The potential clinical benefit of this approach deserves further study.

BACKGROUND

Epithelial cell growth is normally under hormonal control. Hormones also affect the growth of many epithelial cancers, and this fact is used to modify tumor growth. Pancreatic epithelial cell growth is under the influence of gastrointestinal hormones. This article reviews experiments designed to determine the effect of gastrointestinal hormones on the growth of pancreatic adenocarcinoma.

METHODS

Eighty-eight articles were identified from a Medline search using the terms pancreatic adenocarcinoma and the individual names of gastrointestinal hormones. The experimental design and results of these studies are reviewed.

RESULTS

In general, somatostatin, vasoactive intestinal polypeptide, pancreatic polypeptide, and pancreastatin inhibit pancreatic adenocarcinoma growth. Cholecystokinin, secretin, bombesin, gastrin, EGF, TGF-alpha, insulin, and IGF-1 have a growth-promoting effect.

Proteinase-activated receptor-2-mediated signaling and inhibition of DNA synthesis in human pancreatic cancer cells

CONCLUSION

Proteinase-activated receptor-2 (PAR-2)-mediated effects contribute to the intracellular signaling network in pancreatic tumor cells. A role of PAR-2 as negative regulator in human pancreatic tumor growth might be implied.

BACKGROUND

Using the human pancreatic tumor cell line MIA PaCa-2, we evaluated cellular effects of trypsin and the PAR-2-activating peptide SLIGRL on [Ca2+]i mobilization, Ins(1,4,5)P3 level, and protein kinase (PKC) activation. Furthermore, PAR-2 involvement in the regulation of cell proliferation has been estimated by measurement of [3H]thymidine incorporation in MIA PaCa-2 cells.

RESULTS

Trypsin and the PAR-2 synthetic peptide agonist SLIGRL induced [Ca2+]i mobilization, transient increase in inositol (1,4,5) triphosphate level, and PKC translocation in MIA PaCa-2 cells. In addition, SLIGRL induced a decrease in DNA synthesis in MIA PaCa-2 cells.

Adjuvant hormonal treatment with peptide YY or its analog decreases human pancreatic carcinoma growth

BACKGROUND

Recent studies have revealed decreased pancreatic cancer cell growth upon administration of peptide YY (PYY). We examined whether adjuvant treatment with PYY or its synthetic analog, BIM-43004, would decrease human pancreatic adenocarcinoma growth.

MATERIALS AND METHODS

Human pancreatic ductal adenocarcinomas, MiaPaCa-2 and BxPC-3, were cultured and assessed for growth by MTT assay. Pancreatic cancer cells received 500 pmol of PYY or BIM-43004 for 24 hours prior to 5-fluorouracil (5-FU; 10 micrograms/mL) and leucovorin (40 micrograms/mL) administration. Cell membrane epidermal growth factor (EGF) receptors were analyzed by Western blotting after exposure to peptides and chemotherapy.

RESULTS

Cancer cell growth was reduced in all groups receiving hormonal pretreatment (23% PYY/5-FU/leucovorin versus control; 27% BIM-43004/5-FU/leucovorin versus control) as compared with groups receiving 5-FU and leucovorin only (16% versus control). The EGF receptor expression was reduced by 30% in cells treated with PYY/5-FU/leucovorin and by 45% in cells treated with BIM/5-FU/leucovorin as compared with control cells without treatment.

CONCLUSION

Human pancreatic cancer cell growth is further decreased when pretreated with PYY or its synthetic analog prior to chemotherapy.