Gastrin: From Physiology to Gastrointestinal Malignancies

Abetted by widespread usage of acid-suppressing proton pump inhibitors (PPIs), the mitogenic actions of the peptide hormone gastrin are being revisited as a recurring theme in various gastrointestinal (GI) malignancies. While pathological gastrin levels are intricately linked to hyperplasia of enterochromaffin-like cells leading to carcinoid development, the signaling effects exerted by gastrin on distinct cell types of the gastric mucosa are more nuanced. Indeed, mounting evidence suggests dichotomous roles for gastrin in both promoting and suppressing tumorigenesis. Here, we review the major upstream mediators of gastrin gene regulation, including inflammation secondary to Helicobacter pylori infection and the use of PPIs. We further explore the molecular biology of gastrin in GI malignancies, with particular emphasis on the regulation of gastrin in neuroendocrine neoplasms. Finally, we highlight tissue-specific transcriptional targets as an avenue for targetable therapeutics.

Genome analysis identifies differences in the transcriptional targets of duodenal versus pancreatic neuroendocrine tumours

Objective

Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) encompass a diverse group of neoplasms that vary in their secretory products and in their location within the gastrointestinal tract. Their prevalence in the USA is increasing among all adult age groups.

Aim

To identify the possible derivation of GEP-NETs using genome-wide analyses to distinguish small intestinal neuroendocrine tumours, specifically duodenal gastrinomas (DGASTs), from pancreatic neuroendocrine tumours.

Design

Whole exome sequencing and RNA-sequencing were performed on surgically resected GEP-NETs (discovery cohort). RNA transcript profiles available in the Gene Expression Omnibus were analysed using R integrated software (validation cohort). Digital spatial profiling (DSP) was used to analyse paraffin-embedded GEP-NETs. Human duodenal organoids were treated with 5 or 10 ng/mL of tumor necrosis factor alpha (TNFα) prior to qPCR and western blot analysis of neuroendocrine cell specification genes.

Results

Both the discovery and validation cohorts of small intestinal neuroendocrine tumours induced expression of mesenchymal and calcium signalling pathways coincident with a decrease in intestine-specific genes. In particular, calcium-related, smooth muscle and cytoskeletal genes increased in DGASTs, but did not correlate with MEN1 mutation status. Interleukin 17 (IL-17) and tumor necrosis factor alpha (TNFα) signalling pathways were elevated in the DGAST RNA-sequencing. However, DSP analysis confirmed a paucity of immune cells in DGASTs compared with the adjacent tumour-associated Brunner’s glands. Immunofluorescent analysis showed production of these proinflammatory cytokines and phosphorylated signal transducer and activator of transcription 3 (pSTAT3) by the tumours and stroma. Human duodenal organoids treated with TNFα induced neuroendocrine tumour genes, SYP, CHGA and NKX6.3.

Conclusions

Stromal–epithelial interactions induce proinflammatory cytokines that promote Brunner’s gland reprogramming.

Optimizing Nutrition Education in WIC: Findings From Focus Groups With Arizona Clients and Staff

OBJECTIVE

To understand staff and clients' experiences with delivering and receiving nutrition education in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).

METHODS

Focus groups involving WIC staff, clients, and former clients in Arizona. Client and staff perceptions of WIC nutrition education, preferences, and suggestions for improvement were examined. Transcripts were analyzed using a deductive thematic approach to identify emerging themes.

RESULTS

Findings from 10 focus groups with 25 WIC staff and 29 clients suggested that existing materials were time-consuming and unresponsive to client needs, and additional resources were needed to engage children while parents were in session; new delivery formats for nutrition education, including videos and interactive demonstrations focused on child-friendly preparations of WIC foods, were preferred.

CONCLUSIONS AND IMPLICATIONS

Collaboration among existing nutrition education programs, including Supplemental Nutrition Assistance Program-Education, Expanded Food and Nutrition Education Program, community gardens, and Head Start, can complement and enhance WIC nutrition educations in this region.