Ghrelin and its role in gastrointestinal tract tumors (Review)

Abstract

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.

Maternal acrylamide exposure changes intestinal epithelium, immunolocalization of leptin and ghrelin and their receptors, and gut barrier in weaned offspring

“…Ghrelin is synthetized in the stomach and throughout the whole SI and colon and released directly into the blood. The ghrelin receptor belongs to G-protein coupled receptor family and is found in many organs including the intestine 71 . For this reason it exerts local and systemic physiological processes 71 .…”

“…The ghrelin receptor belongs to G-protein coupled receptor family and is found in many organs including the intestine 71 . For this reason it exerts local and systemic physiological processes 71 . It plays a key role in appetite stimulation and worsens glucose tolerance through reduction of insulin sensitivity in rodents and humans, thus increasing plasma glucose.…”

Molecular factors, diagnosis and management of gastrointestinal tract neuroendocrine tumors: An update

“…Ghrelin is secreted mainly by enteroendocrine cells in the oxyntic glands of the stomach. Serum levels are elevated in gastrointestinal tract malignancies and may be a prognostic factor or even a therapeutic target[ 49 ].…”

Metabolic Hormones Modulate Macrophage Inflammatory Responses

“…However, the precise relationship between the ghrelin axis and cancer development remains unclear and controversial due to conflicting results observed between in vitro [ 96 ] studies involving a range of tumour cells lines and clinical studies [ 97 ]. Several recent attempts have been made recently to standardise these findings [ 95 , 98 ] leading to the hypothesis that the systemic nature of ghrelin signalling may contribute to confounding local factors that make delineating ghrelin’s direct role in cancer progression complex. Furthermore, experimental variations such as different cell lines and dosages used, add additional difficulties to interpreting the effects of ghrelin from these in vitro studies.…”