Ghrelin and gastrointestinal stromal tumors

Role of the Ghrelin System in Colorectal Cancer

The ghrelin system contains several components (e.g., ghrelin with growing number of alternative peptides, growth hormone secretagogue receptors (GHS-Rs), and ghrelin-O-acyl-transferase (GOAT) and participates in regulation of a number of key processes of gastrointestinal (GI) tract cancer progression, including cell proliferation, migration, invasion, apoptosis, inflammation, and angiogenesis. However, its exact role in promoting or inhibiting cancer progression is still unclear. Colorectal cancer (CRC) is one of the most common human malignancies worldwide. Molecular studies suggest an autocrine/paracrine mechanism for the secretion of ghrelin in colorectal carcinogenesis and its contribution to its initial stages. However, the signalling pathways of CRC development involving the ghrelin system are poorly understood. Potential mechanisms of colon carcinogenesis involving components of the ghrelin system were previously described in an animal model and in in vitro studies. However, the diagnostic–prognostic role of serum ghrelin concentrations, tissue expression, or genetic changes of this system in various stages of CRC progression remains an open case. Thus, the aim of this study is to discuss the role of the ghrelin system in colon carcinogenesis, diagnostics and CRC prognostics, as well as the results of studies on the use of ghrelin and its analogues in the therapy of CRC-related syndromes (e.g., cachexia and sarcopenia).

The Incidence of Gastrointestinal Stromal Tumors in Obese Patients—A Large Single Center Experience

Background and Objectives: Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasms located mainly in the fundus (60–70%). The incidence of GIST is approximately 10 per million population per year in Europe, with a peak incidence at the age of 63. Recent studies suggest that morbidly obese patients have a higher incidence of GIST than the general population. The aim of this study was to analyze the incidence of GIST in patients undergoing laparoscopic sleeve gastrectomy (LSG) in our department. Materials and Methods: this paper present the retrospective study of prospectively collected data of 1564 patients who underwent LSG in a single large bariatric center from October 2013 to September 2021. After surgery, each sample of the resected stomach was sent for histopathological examination. For the analysis, we included patients diagnosed with GIST intraoperatively or postoperatively. Results: GISTs were found in five patients (0.31%). There were three men and two women. The mean age was 50.2 (range 32–63 ± 11.8) and the mean preoperative body mass index was 43.3 kg/m² (40–49.4 ± 3.2). In four cases, GISTs were found in the fundus (80%), and in one in the pylorus (20%). None of the tumors were larger than 7 mm in diameter and all were diagnosed as a very low-risk category. No adjuvant treatment was required. All patients achieved good or satisfactory bariatric and metabolic results. Conclusions: The incidence of GIST in our study was estimated at 0.31%. All patients had a very low-risk GIST and no recurrence until follow-up. Recent literature suggests that the risk of GIST is higher in the obese population, and therefore surgeons should be aware of the risk of incidental GIST during LSG.

GIST and Ghrelin: To Be or Not to Be?

BACKGROUND

Ghrelin is the orexigenic hormone secreted mainly by the stomach. Its involvement in neoplastic development has been studied in gastrointestinal adenocarcinomas. Our paper aims to evaluate the influence of the ghrelin axis in gastrointestinal stromal tumors (GISTs).

MATERIALS AND METHODS

The study design included two groups of patients, 46 with gastric GISTs and 30 with obesity. Archived tissue samples were evaluated for the presence of gastritis and H. pylori. Immunohistochemical expression of ghrelin and its receptor (GHS-R) was assessed.

RESULTS

All GISTs showed absent immunohistochemical expression for ghrelin, while GHS-R displayed a particular pattern, with notable differences in intensity (p = 0.0256) and percentage of stained cells (p < 0.00001) in the periphery vs. core of tumors. Positive ghrelin expression was lower in the gastric mucosa of the first group compared to the second group (p < 0.001).

CONCLUSION

The ghrelin axis can influence GISTs carcinogenesis through activation of GHS-R. A previously described direct autocrine/paracrine mechanism is not supported by our findings.

Ghrelin and its role in gastrointestinal tract tumors (Review)

Ghrelin, an orexigenic hormone, is a peptide that binds to the growth hormone secretagogue receptor; it is secreted mainly by enteroendocrine cells in the oxyntic glands of the stomach. Ghrelin serves a role in both local and systemic physiological processes, and is implicated in various pathologies, including neoplasia, with tissue expression in several types of malignancies in both in vitro and in vivo studies. However, the precise implications of the ghrelin axis in metastasis, invasion and cancer progression regulation has yet to be established. In the case of gastrointestinal (GI) tract malignancies, ghrelin has shown potential to become a prognostic factor or even a therapeutic target, although data in the literature are inconsistent and unsystematic, with reports untailored to a specific histological subtype of cancer or a particular localization. The evaluation of immunohistochemical expression shows a limited outlook owing to the low number of cases analyzed, and in vivo analyses have conflicting data regarding differences in ghrelin serum levels in patients with cancer. The aim of this review was to examine the relationship between ghrelin and GI tract malignancies to demonstrate the inconsistencies in current results and to highlight its clinical significance in the outcome of these patients.

An Unexpected Finding of Gastrointestinal Stromal Tumors During Laparoscopic Sleeve Gastrectomy; How to Deal? How Much Safety Margin Needed?

Background: There is an increasing incidence of coincidental gastric gastrointestinal stromal tumors (GIST) during a laparoscopic sleeve gastrectomy (LSG). Resection with negative margin R0 is the safest and most proper treatment. Objectives: The incidence of GIST in patients undergoing LSG and resection with a 1- to 2-cm safety margin was validated and analyzed. The primary endpoint is that can simultaneous excision be oncologically adequate or not? How much GIST is supposed to be far from a staple line? Methods: The present prospective study included 338 patients with body mass index (BMI) ≥ 35. All patients underwent LSG without known history or imaging reveal GIST. Resection was done with a safety margin of 1 to 2 cm away from the stapled margin and, then, sent for histopathology and immunohistochemically staining. Results: A total of 17 patients (5%) had coincidental GIST. The size was T1 in 88.2% of patients; 16 patients were staged as IA according to the American Joint Committee on Cancer (AJCC TNM). Safety margin was ≤ 1 cm for 3 patients to avoid incorporation in staple line and 14 patients (82.3%) had 2 cm safety margin. Resection margin in biopsy revealed positive resection margin R1 for 2 patients, whose safety margin was only 1 cm or less. A total of 15 patients had a negative margin (R0), whose safety margin was 2 cm. Conclusions: Any incidental GIST can be removed safely during LSG as long as it is far from the staple line with at least a 2-cm safety margin and negative resection margins without changing the procedure. Margins less than 1 cm are associated with adverse prognostic factors.

Pretreatment of ghrelin protects H9c2 cells against hypoxia/reoxygenation-induced cell death via PI3K/AKT and AMPK pathways

Ghrelin has been widely recognized as a key peptide in the cardiovascular system. This study detected the potential of ghrelin in MI management and tried to decode one of the possible underlying mechanisms. H9c2 cells were pretreated with ghrelin and were subjected to hypoxia/reoxygenation (H/R). CCK-8, flow cytometry, Western blot and LDH analysis were conducted to assess the changes in cell survival. LY294002 and Compound C were used to treat H9c2 cells for blocking PI3K/AKT and AMPK pathways, respectively. Ghrelin expression in H9c2 cells was suppressed by siRNA-mediated silencing to see the effects of endogenous ghrelin. We found that, following H/R, H9c2 cells viability was decreased, CyclinD1 and CDK4 were down-regulated, apoptosis was induced, the release of LDH was enhanced, and the expression levels of Cox-2 and iNOS were up-regulated. Ghrelin protected H9c2 cells against H/R induced these alterations. Besides, ghrelin activated PI3K/AKT and AMPK pathways even in H/R-stimulated cells. The protective effects of ghrelin against H/R-induced cell damage were all attenuated by the addition of LY294002 or Compound C. Moreover, endogenous inhibition of ghrelin significantly induced cell death of H9c2 cells. In conclusion, this study demonstrated that ghrelin pretreatment protected H9c2 cells against H/R-induced cell damage, possibly via PI3K/AKT and AMPK pathways.

Attribution of Ghrelin to Cancer; Attempts to Unravel an Apparent Controversy

Ghrelin is an endogenous peptide hormone mainly produced in the stomach. It has been known to regulate energy homeostasis, stimulate secretion of growth hormone, and mediate many other physiologic effects. Various effects attributed to ghrelin contribute to many aspects of cancer development and progression. Accordingly, a large body of evidence has emerged about the association of ghrelin with several types of cancer in scales of cell-line, animal, and human studies. However, existing data are controversial. This controversy occurs in two main domains: one is the controversial results in local effects of ghrelin on different types of human cancer cell-lines; the second is the apparent disagreement in the results of in-vitro and clinical studies that investigated ghrelin association to one type of cancer. These inconsistencies have hampered the indications to consider ghrelin as a potential tumor biomarker or therapeutic agent in cancer patients. Previous studies have reviewed different parts of current literature about the ghrelin-cancer relationship. Although they have highlighted these controversial results in various ways, no specific recommendations have been given to address it. In this study, we comprehensively reviewed in-vitro, in-vivo, and clinical studies and attempted to use the following approaches to unravel the inconsistencies detected: (a) to distinguish local and systemic effects of ghrelin in interpreting its summary clinical role in each cancer; (b) scrutinizing factors that regulate local effects of ghrelin and could justify different effects of ghrelin on different cancer cell-lines. These approaches could have notable implications for future in-vitro and clinical studies.

Distribution Patterns of Cocaine- and Amphetamine-Regulated Transcript- and/or Galanin-Containing Neurons and Nerve Fibers Located in the Human Stomach Wall Affected by Tumor

The aim of the study was to investigate the distribution patterns of cocaine- and amphetamine-regulated transcript- (CART-) and galanin-immunoreactive (GAL-IR) neuronal structures in the human stomach wall, focusing on differences observed in regions directly affected by the cancer process, and those from the surgical margin. Samples from the stomach wall were collected from 10 patients (3 women and 7 men, the mean age 67.0 ± 11.9). Next, triple-immunofluorescence staining was used to visualize the changes in the frequency of neurons inside myenteric plexi and intramural fibers containing CART and/or GAL, as well as protein gene product 9.5 (as panneuronal marker). Tumor into the stomach wall caused a decrease in the number of CART-positive (+) nerve fibers in the longitudinal (LML) and circular muscle layers (CML). Notable changes in the dense network of CART+/GAL+ nerve fibers (an increase) were observed in the LML and lamina muscularis mucosae (LMM) within carcinoma-affected areas of the human stomach. Additionally, an elevated number of these nerve fibers from LMM were accompanied by an increase in the number of fibers containing GAL in the vicinity of the neoplastic proliferation. Obtained results suggest that a carcinoma invasion may affect the innervation pattern of the human stomach wall and their function(s).

MiR-374b Promotes Proliferation and Inhibits Apoptosis of Human GIST Cells by Inhibiting PTEN through Activation of the PI3K/Akt Pathway

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumors of the gastrointestinal (GI) tract. In order to investigate a new treatment fot GIST, we hypothesized the effect of miR-374b targeting PTEN gene-mediated PI3K/Akt signal transduction pathway on proliferation and apoptosis of human gastrointestinal stromal tumor (GIST) cells. We obtained GIST tissues and adjacent normal tissues from 143 patients with GIST to measure the levels of miR-374b, PTEN, PI3K, Akt, caspase9, Bax, MMP2, MMP9, ki67, PCNA, P53 and cyclinD1. Finally, cell viability, cell cycle and apoptosis were detected. According to the KFGG analysis of DEGs, PTEN was involved in a variety of signaling pathways and miRs were associated with cancer development. The results showed that MiR-374b was highly expressed, while PTEN was downregulated in the GIST tissues. The levels of miR-374b, PI3K, AKT and PTEN were related to tumor diameter and pathological stage. Additionally, miR-374b increased the mRNA and protein levels of PI3K, Akt, MMP2, MMP9, P53 and cyclinD1, suggesting that miR-374b activates PI3K/Akt signaling pathway in GIST-T1 cells. Moreover, MiR-374b promoted cell viability, migration, invasion, and cell cycle entry, and inhibited apoptosis in GIST cells. Taken together, the results indicated that miR-374b promotes viability and inhibits apoptosis of human GIST cells by targeting PTEN gene through the PI3K/Akt signaling pathway. Thus, this study provides a new potential target for GIST treatment.

Protective effects of brain-gut peptides against intestinal barrier injury and mechanisms involved

Brain-gut peptides, a group of small molecule polypeptides, have been found to distribute widely in the brain and the gastrointestinal system and act as both neurotransmitters and hormones. Intestinal barrier injury has a serious impact on the prognosis of critical diseases. Brain-gut peptides can modulate tight junction proteins, promote epithelial cell proliferation, and inhibit apoptosis and inflammatory cytokines, thus playing an important role in the maintenance of intestinal barrier and mucosal immunity. In this review, we discuss the protective effects of brain-gut peptides against intestinal barrier injury and the underlying mechanisms.