Microarray analysis of somatostatin receptor 5-regulated gene expression profiles in murine pancreas

Racial and Gender Disparities Among Obese Patients With Pancreatic Cancer: A Trend Analysis in the United States

BACKGROUND

Pancreatic cancer (PC) is the third leading cause of cancer death. Obesity can increase the risk of PC by up to 50%. Studies have shown racial and gender disparities in PC, however, there is a paucity of such information in obese PC patients.

AIM

The aim of this study was to: (1) evaluate the incidence and prevalence of obesity among PC patients in the United States over the last 15 years, and (2) determine if variation exists in the demographic of obese PC patients over the last 15 years. It is hoped that this information could be used to assist in primary prevention and early detection of PC.

METHODS

A population-based retrospective analysis in IBM Explorys, a pooled, national, deidentified database of 63 million patients from 300 hospitals in the United States. Patient populations were identified using SNOMED and ICD codes. Cochrane-Armitage testing was performed to analyze trends in obesity among PC. Subgroup analysis for gender, age, race, and mortality rate were assessed.

RESULTS

The percentage of obese patients with PC increased over the 15-year period (2.5% to 8.5%, P <0.0001). Rates of obesity among PC patients increased among females ( P =0.0004), individuals under age 65 years ( P =0.0002), and all races, but especially for African Americans ( P =0.0007) and those in minority groups.

CONCLUSION

Awareness of disparities in PC and applying targeted care to those at increased risk are essential to improve future outcomes, including increased health care access and recruitment in research studies for minority groups.

Regulatory Mechanisms of Somatostatin Expression

Somatostatin is a peptide hormone, which most commonly is produced by endocrine cells and the central nervous system. In mammals, somatostatin originates from pre-prosomatostatin and is processed to a shorter form, i.e., somatostatin-14, and a longer form, i.e., somatostatin-28. The two peptides repress growth hormone secretion and are involved in the regulation of glucagon and insulin synthesis in the pancreas. In recent years, the processing and secretion of somatostatin have been studied intensively. However, little attention has been paid to the regulatory mechanisms that control its expression. This review provides an up-to-date overview of these mechanisms. In particular, it focuses on the role of enhancers and silencers within the promoter region as well as on the binding of modulatory transcription factors to these elements. Moreover, it addresses extracellular factors, which trigger key signaling pathways, leading to an enhanced somatostatin expression in health and disease.

Disparities in Pancreatic Cancer Treatment and Outcomes

Purpose: Pancreatic cancer remains a major health concern; in the next 2 years, it will become the second leading cause of cancer deaths in the United States. Health disparities in the treatment of pancreatic cancer exist across many disciplines, including race and ethnicity, socioeconomic status (SES), and insurance. This narrative review discusses what is known about these disparities, with the goal of highlighting targets for equity promoting interventions.

Methods: We performed a narrative review of health disparities in pancreatic cancer spanning greater than ten areas, including epidemiology, treatment, and outcome, using the PubMed NIH database from 2000 to 2019 in the Unites States.

Results: African Americans (AAs) tend to present at diagnosis with later stage disease. AAs and Hispanics have lower rates of surgical resection, are more likely to be treated at low volume hospitals, and often experience higher rates of morbidity and mortality compared to white patients, although control for confounders is often limited. Insurance and SES also factor into the delivery of treatment for pancreatic cancer.

Conclusion: Disparities by race and SES exist in the diagnosis and treatment of pancreatic cancer that are largely driven by race and SES. Improved understanding of underlying causes could inform interventions.

Closing the Disparity in Pancreatic Cancer Outcomes: A Closer Look at Nonmodifiable Factors and Their Potential Use in Treatment

OBJECTIVES

African Americans (AAs) have disproportionately higher incidence and lower survival rates from pancreatic cancer compared with whites. Historically, this disparity has been attributed to modifiable risk factors. Recent studies suggest that nonmodifiable aspects may also play an important role. We review these new contributions as potential targets for closing the disparity.

METHODS

A PubMed search was conducted to review studies of nonmodifiable elements contributing to pancreatic cancer disparities in AAs.

RESULTS

Several nonmodifiable risks are associated with the racial disparity in pancreatic cancer. SSTR5 P335L, Kaiso, and KDM4/JMJD2A demonstrate differential racial expression, increasing their potential as therapeutic targets. Many social determinants of health and their associations with diabetes, obesity, and the microbiome are partially modifiable risk factors that significantly contribute to outcomes in minorities. Barriers to progress include the low minority inclusion in research studies.

CONCLUSIONS

Genomics, epigenetics, the microbiome, and social determinants of health are components that contribute to the pancreatic cancer disparity in AAs. These factors can be researched, targeted, and modified to improve mortality rates. Closing the disparity in pancreatic cancer will require an integrated approach of personalized medicine, increased minority recruitment to studies, and advanced health care/education access.

Down-regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5: a novel mechanism for inhibition of cellular proliferation and insulin secretion by somatostatin

Somatostatin (SST) is a regulatory peptide and acts as an endogenous inhibitory regulator of the secretory and proliferative responses of target cells. SST’s actions are mediated by a family of seven transmembrane domain G protein-coupled receptors that comprise five distinct subtypes (SSTR1-5). SSTR5 is one of the major SSTRs in the islets of Langerhans. Homeodomain-containing transcription factor pancreatic and duodenal homeobox-1 (PDX-1) is essential for pancreatic development, β cell differentiation, maintenance of normal β cell functions in adults and tumorigenesis. Recent studies show that SSTR5 acts as a negative regulator for PDX-1 expression and that SSTR5 mediates somatostatin’s inhibitory effect on cell proliferation and insulin expression/excretion through down-regulating PDX-1 expression. SSTR5 exerts its inhibitory effect on PDX-1 expression at both the transcriptional level by down-regulating PDX-1 mRNA and the post-translational level by enhancing PDX-1 ubiquitination. Identification of PDX-1 as a transcriptional target for SSTR5 may help in guiding the choice of therapeutic cancer treatments.

Negative regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5

Somatostatin receptor subtype 5 (SSTR5) mediates the inhibitory effect of somatostatin and its analogs on insulin expression/secretion and islet cell proliferation. We provide biochemical and genetic evidence that SSTR5 exerted its physiological actions via down-regulating pancreatic and duodenal homeobox-1 (PDX-1), a β-cell-specific homeodomain-containing transcription factor. Cotransfection of SSTR5 with PDX-1 resulted in dose-dependent inhibition of PDX-1 expression in human embryonic kidney 293 cells. SSTR5 agonist RPL-1980 inhibited PDX-1 expression and abolished glucagon-like peptide 1-stimulated PDX-1 expression in mouse insulinoma β-TC-6 cells. SSTR5 knockdown by short hairpin RNA led to increased PDX-1 expression that was accompanied by enhanced insulin secretion stimulated by high glucose in β-TC6 cells and alternated expressions of cell cycle proteins that favor cell proliferation in mouse insulinoma MIN6 cells. Quantitative RT-PCR analysis showed that cotransfected SSTR5 inhibited PDX-1 mRNA expression, whereas knockdown of SSTR5 increased PDX-1 mRNA expression. In addition, we found that cotransfected wild-type SSTR5 increased PDX-1 ubiquitination in human embryonic kidney 293 cells, whereas SSTR5 P335L, a hypofunctional single nucleotide polymorphism of SSTR5, inhibited PDX-1 ubiquitination. SSTR5 knockout resulted in increased expression of PDX-1, insulin, and proliferating cell nuclear antigen in the islets of sstr(-/-) mice. Immunohistochemistry analysis showed that SSTR5 P335L was associated with elevated expression of PDX-1 in human pancreatic neuroendocrine tumor. Taken together, our studies demonstrated that SSTR5 is a negative regulator for PDX-1 expression and that SSTR5 may mediate the inhibitory effects of somatostatin and its analogs on insulin expression/secretion and cell proliferation via down-regulating PDX-1 at both transcriptional and posttranslational levels.

Functional genomics of endothelial cells treated with anti-angiogenic or angiopreventive drugs

Angiogenesis is a highly regulated physiological process that has been studied in considerable detail given its importance in several chronic pathologies. Many endogenous factors and hormones intervene in the regulation of angiogensis and classical as well as targeted drugs have been developed for its control. Angiogenesis inhibition has come off the bench and entered into clinical application for cancer therapy, particularly for metastatic disease. While the clinical benefit is currently in terms of months, preclinical data suggest that novel drugs and drug combinations could lead to substantial improvement. The many targets of endogenous angiogenesis inhibitors reflect the complexity of the process; in contrast, current clinical therapies mainly target the vascular endothelial growth factor system. Cancer chemopreventive compounds can retard tumor insurgence and delay or prevent metastasis and many of these molecules hinder angiogenesis, a mechanism that we termed angioprevention. Angiopreventive drugs appear to prevalently act through the inhibition of the pro-inflammatory and anti-apoptotic player NFkappaB, thus contrasting inflammation dependent angiogenesis. Relatively little is known concerning the effects of these angiogenesis inhibitors on gene expression of endothelial cells, the main target of many of these molecules. Here we provide an exhaustive list of anti-angiogenic molecules, and summarize their effects, where known, on the transcriptome and functional genomics of endothelial cells. The regulation of specific genes can be crucial to preventive or therapeutic intervention. Further, novel targets might help to circumvent resistance to anti-angiogenic therapy. The studies we review are relevant not only to cancer but also to other chronic degenerative diseases involving endothelial cells, such as cardiovascular disorders, diabetes, rheumatoid arthritis and retinopaties, as well as vessel aging.

The role(s) of somatostatin, structurally related peptides and somatostatin receptors in the gastrointestinal tract: a review

Extensive functional and morphological research has demonstrated the pivotal role of somatostatin (SOM) in the regulation of a wide variety of gastrointestinal activities. In addition to its profound inhibitory effects on gastrointestinal motility and exocrine and endocrine secretion processes along the entire gastrointestinal tract, SOM modulates several organ-specific activities. In contrast to these well-known SOM-dependent effects, knowledge on the SOM receptors (SSTR) involved in these effects is much less conclusive. Experimental data on the identities of the SSTRs, although species- and tissue-dependent, point towards the involvement of multiple receptor subtypes in the vast majority of gastrointestinal SOM-mediated effects. Recent evidence demonstrating the role of SOM in intestinal pathologies has extended the interest of gastrointestinal research in this peptide even further. More specifically, SOM is supposed to suppress intestinal inflammatory responses by interfering with the extensive bidirectional communication between mucosal mast cells and neurons. This way, SOM not only acts as a powerful inhibitor of the inflammatory cascade at the site of inflammation, but exerts a profound antinociceptive effect through the modulation of extrinsic afferent nerve fibres. The combination of these physiological and pathological activities opens up new opportunities to explore the potential of stable SOM analogues in the treatment of GI inflammatory pathologies.