Kisspeptin Effect on Endothelial Monocyte Activating Polypeptide II (EMAP-II)-Associated Lymphocyte Cell Death and Metastases in Colorectal Cancer Patients

Martha Stathaki,Manoussos M Konstantoulakis,Michael Koutsilieris,Athanasios Armakolas,Loukas Kaklamanis,Andreas Dimakakos,George Zografos,Ioannis Vlachos

doi:10.2119/molmed.2013.00151

Abstract

Kisspeptin is an antimetastatic agent in some cancers that has also been associated with lymphoid cell apoptosis, a phenomenon favoring metastases. Our aim was to determine the association of kisspeptin with lymphocyte apoptosis and the presence of metastases in colorectal cancer patients. Blood was drawn from 69 colon cancer patients and 20 healthy volunteers. Tissue specimens from healthy and pathological tissue were immunohistochemically analyzed for kisspeptin and endothelial monocyte activating polypeptide II (EMAP-II) expression. Blood EMAP-II and soluble Fas ligand (sFasL) levels were examined by an enzyme-linked immunosorbent assay method. The kisspeptin and EMAP-II expression and secretion levels in the DLD-1 and HT-29 colon cancer cell lines were examined by quantitative real-time polymerase chain reaction, Western analysis and enzyme-linked immunosorbent assay, whereas lymphocyte viability was assessed by flow cytometry. The effect of kisspeptin on the viability of colon cancer cells was examined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]. Exogenous, synthetic and naturally produced, kisspeptin induces through the G-protein-coupled receptor 54 (GPR54; also known as the kisspeptin receptor) the EMAP-II expression and secretion in colon cancer cell lines, inducing in vitro lymphocyte apoptosis, as verified by the use of an anti-EMAP-II antibody. These results were reversed with the use of kisspeptin inhibitors and by kisspeptin-silencing experiments. Tumor kisspeptin expression was associated with the tumor EMAP-II expression (p < 0.001). Elevated kisspeptin and EMAP-II expression in colon cancer tissues was associated with lack of metastases (p < 0.001) in colon cancer patients. These data indicate the antimetastatic effect of tumor-elevated kisspeptin in colon cancer patients that may be mediated by the effect of kisspeptin on EMAP-II expression in colon cancer tumors in patients with normal serum EMAP-II levels. These findings provide new insight into the role of kisspeptin in the context of metastases in colon cancer patients.

Highlights

Colorectal cancer displays a large percentage of possibility to metastasize to the liver, if left untreated
Recent evidence suggests that tumor secretion of molecules that are implicated in promoting apoptosis in the patients’ blood may result in increased apoptosis of peripheral lymphocytes [8,9]
On the basis of this finding, we examined the direct effects of exogenous kisspeptin on normal lymphocytes for 24 and 48 h

Summary

Introduction

Colorectal cancer displays a large percentage of possibility to metastasize to the liver, if left untreated. Colon cancer patients with metastases (stage IV) have a 6% 5-year survival rate [1,2,3,4,5]. The communication and interaction mechanisms between cancer cells and the patient’s organ systems seem to be of critical importance in determining both the pathogenesis and the prognosis of the disease. The tumor’s displayed ability to concurrently evade immunological response and metastasize is attributed to disturbances in the longevity of immunocytes, but is due to the cancer cells releasing mediator molecules that promote immunosuppression [6,7]. Cancer-allocated increased apoptosis of circulating lymphocytes is the most common cancerassociated symptom in patients with malignant neoplasms. Recent evidence suggests that tumor secretion of molecules that are implicated in promoting apoptosis (soluble Fas ligand [sFasL], endothelial monocyte activating polypeptide II [EMAP-II]) in the patients’ blood may result in increased apoptosis of peripheral lymphocytes [8,9]

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