Ghrelin and obestatin expression in serous ovarian tumours

Expression of adipokine ghrelin and ghrelin receptor in human colorectal adenoma and correlation with the grade of dysplasia

BACKGROUND

Ghrelin is an adipokine that plays an important role in energy balance. Expression of ghrelin and ghrelin receptor has been investigated in different tissues and tumors. Studies regarding expression of ghrelin and ghrelin receptor in colorectal tumors are scarce and no data on expression of ghrelin and its receptor in colorectal adenomas has been published. Ghrelin and ghrelin receptor were highly expressed in colon carcinoma cells while expression was decreased in less differentiated tumors, presuming that ghrelin might be important in early phases of tumorigenesis.

AIM

To investigate the expression of ghrelin and ghrelin receptor in human colorectal adenomas and adjacent colorectal tissue.

METHODS

In this prospective study (conducted from June 2015 until May 2019) we included 92 patients (64 male and 28 female) who underwent polypectomy for colorectal adenomas in the Department of Gastroenterology and Hepatology, “Sestre milosrdnice” Clinical Hospital Center in Zagreb, Croatia. After endoscopic removal of colorectal adenoma, an additional sample of colon mucosa in the proximity of the adenoma was collected for pathohistological analysis. Adenomas were graded according to the stage of dysplasia, and ghrelin and ghrelin receptor expression were determined immunohistochemically in both adenoma and adjacent colon tissue using the polyclonal antibody for ghrelin (ab150514, ABCAM Inc, Cambridge, United States) and ghrelin receptor (ab48285, ABCAM Inc, Cambridge, United States). Categorical and nominal variables were described through frequencies and proportions and the difference between specific groups were analyzed with Fisher’s and Fisher-Freeman-Halton’s method respectively. Spearman's rank correlation coefficient was determined for correlation of expression of ghrelin and ghrelin receptor in adenoma and adjacent colon tissue with the grade of adenoma dysplasia.

RESULTS

Among 92 patients with colorectal adenoma 43 had adenomas with high-grade dysplasia (46.7%). High expression of ghrelin was 7 times more common in high-grade adenoma compared to low-grade adenomas (13.95% to 2.04%, P = 0.048), while the expression of ghrelin in adjacent colon tissue was low. We found no correlation between ghrelin receptor expression in adenoma and adjacent colon tissue and the grade of colorectal adenoma dysplasia. The most significant correlation was found between ghrelin and ghrelin receptor expression in adenomas with high-grade dysplasia (rho = 0.519, P < 0.001).

CONCLUSION

Ghrelin and ghrelin receptor are expressed in colorectal adenoma and adjacent tissue with ghrelin expression being more pronounced in high grade dysplasia as a possible consequence of increased local synthesis.

Can Estradiol and Ghrelin Play a Protective Role in Epithelial Ovarian Cancer Incidence in Postmenopausal Women?

OBJECTIVE

The present study aimed to investigate the association between estradiol, n-octanoylated, des-octanoylated, total ghrelin, and ghrelin/des-octanoylated ghrelin ratio levels along with pathological parameters and epithelial ovarian cancer (EOC) odds in postmenopausal women.

MATERIALS AND METHODS

A case-control study was carried out on 45 patients with EOC and 33 age-matched postmenopausal women as the control group. Plasma levels of estradiol, n-octanoylated, des-octanoylated, and total ghrelin were measured by ELISA method.

RESULTS

Estradiol's plasma levels were significantly higher in patients with EOC than in control women (p <0.001). Although the ratio levels of n-octanoylated, des-octanoylated, total ghrelin, and ghrelin/des-octanoylated ghrelin were not associated with EOC in logistic regression models, estradiol levels were significantly related to the increase in EOC odds (OR: 1.083, 95% CI: 1.037-1.13, p <0.001). However, estradiol levels in the two first quartiles (Q₁, Q₂) were associated with decreased odds of EOC (OR: 0.011, 95% CI: 0.001-0.118, p <0.001, and OR: 0.030, 95% CI: 0.003-0.284, p = 0.002, respectively). For those patients in the third quartile of plasma des-octanoylated and total ghrelin compared to those in the highest (Q4), the multivariate odds ratios of EOC were respectively 0.192 and 0.25.

CONCLUSION

In conclusion, higher concentrations of des-octanoylated and total ghrelin might be associated with the decreased EOC odds. Furthermore, the findings suggest that high levels of estradiol might be a potential odds factor in EOC, however, lower estradiol levels may have a protective effect on EOC development.

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.

Effects of Ghrelin on the Apoptosis of Rheumatoid Arthritis Fibroblast-Like Synoviocyte MH7A Cells

Ghrelin is a circulating peptide hormone, which involved in promoting feeding and regulating energy metabolism in human and rodents. Abnormal synovial hyperplasia is the most important pathologic hallmark of rheumatoid arthritis (RA), which is characterised by tumor-like expansion. Existing studies indicated that there may exist some relation between the decreased ghrelin and the abnormally proliferating synovial cells in RA. Therefore, the aim of this study is to explore the apoptotic effects of ghrelin on MH7A synovial cells in vitro. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate the effects of ghrelin on the viability of MH7A cells. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling (TUNEL) and flow cytometry were used to test the apoptotic effects of ghrelin. At last, Western blot and real-time PCR were performed to explore the expression of caspases-8, -9, and -3 after the treatment of ghrelin. MTT experiments showed that ghrelin could inhibit viability of MH7A cells. The results of flow cytometry and TUNEL showed that ghrelin could induce apoptosis of MH7A synovial cells. Western blot showed that expression of cleaved-caspases-8, -9, and -3 were increased in ghrelin stimulation group compared with the control group, while expression of pro-caspases-8, -9, and -3 had no significant difference. In mRNA levels, ghrelin can decrease pro-caspases-8, -9, and -3 mRNA expression, which confirmed the results of protein levels. Then these apoptotic effects were significantly reversed by [D-Lys₃] GHRP-6 (ghrelin receptor antagonist). This study found that ghrelin can induce apoptosis of MH7A cells through caspase signaling pathways.

Ghrelin attenuates the growth of HO-8910 ovarian cancer cells through the ERK pathway

Ovarian cancer is one of the most common causes of death from gynecologic tumors and is an important public health issue. Ghrelin is a recently discovered bioactive peptide that acts as a natural endogenous ligand of the growth hormone secretagogue receptor (GHSR). Several studies have identified the protective effects of ghrelin on the mammalian reproductive system. However, little research has been done on the effects of ghrelin on ovarian cancer cells, and the underlying mechanisms of these effects. We sought to understand the potential involvement of mitogen-activated protein kinases (MAPKs) in ghrelin-mediated inhibition of growth of the ovarian line HO-8910. We applied different concentrations of ghrelin and an inhibitor of the ghrelin receptor (D-Lys3-GHRP-6) to HO-8910 cells and observed the growth rate of cells and changes in phosphorylation of the MAPKs ERK1/2, JNK and p38. We discovered that ghrelin-induced apoptosis of HO-8910 cells was though phosphorylated ERK1/2, and that this phosphorylation (as well as p90rsk phosphorylation) was mediated by the GHSR. The ERK1/2 pathway is known to play an essential part in the ghrelin-mediated apoptosis of HO-8910 cells. Hence, our study suggests that ghrelin inhibits the growth of HO-8910 cells primarily through the GHSR/ERK pathway.