RARRES2 functions as a tumor suppressor by promoting beta-catenin phosphorylation/degradation and inhibiting p38 phosphorylation in adrenocortical carcinoma
ONCOGENE
Authors: Liu-Chittenden, Y.; Jain, M.; Gaskins, K.; Wang, S.; Merino, M. J.; Kotian, S.; Gara, S. Kumar; Davis, S.; Zhang, L.; Kebebew, E.
Abstract
Tumor suppressor genes and the immune system are critical players in inhibiting cancer initiation and/or progression. However, little is known about whether a tumor suppressor gene can function through both immune-dependent and - independent mechanisms. Retinoic acid receptor responder 2 (RARRES2) is transcriptionally downregulated in multiple cancer types. Previous studies suggested that it can serve as an immune-dependent tumor suppressor by acting as a chemoattractant to recruit anticancer immune cells expressing its receptor, the chemerin chemokine receptor 1 (CMKLR1), to sites of tumor. In this study, we investigated the role of RARRES2 in adrenocortical carcinoma (ACC), a rare lethal malignancy in which aberrant Wnt/beta-catenin signaling is frequently detected. We show that RARRES2 expression is downregulated in ACC as compared with normal and benign adrenocortical tissues, which is a result of CpG hypermethylation. Despite minimal CMKLR1 expression and lack of phenotypic tumor-suppressive effect with exogenous RARRES2 treatment, RARRES2 overexpression in ACC cell lines not only reduced cell proliferation, cell invasion and tumorigenicity in vitro, but also inhibited tumor growth in vivo in two immunodeficient mouse xenograft models. Mechanistically, RARRES2 overexpression in ACC cells inhibited Wnt/beta-catenin pathway activity by promoting beta-catenin phosphorylation and degradation, it also inhibited the phosphorylation of p38 mitogen-activated protein kinase. Thus our study identifies RARRES2 as a novel tumor suppressor for ACC, which can function through an immune-independent mechanism.
Changes of Chemerin Production in Obese Patients with Different States of Carbohydrate Metabolism
BIOCHEMISTRY MOSCOW-SUPPLEMENT SERIES B-BIOMEDICAL CHEMISTRY
Authors: Vasilenko, M. A.; Kirienkova, E. V.; Skuratovskaia, D. A.; Zatolokin, P. A.; Mironyuk, N. I.; Litvinova, L. S.
Abstract
Chemerin is an adipose tissue mediator involved in the regulation of many processes, including lipogenesis, inflammatory responses, etc. The role of chemerin in the development of insulin resistance still needs better understanding. The aim of the study was to investigate chemerin production in obese patients with different states of carbohydrate metabolism. The study included 155 patients with diagnosed obesity and 34 patients with overweight. The control group 1 consisted of 43 conditionally healthy donors without obesity. For comparison of the research data on evaluation of tissue-specific mRNA expression of the genes IL-6, TNF-alpha, RARRES2, (encoding IL-6, TNF-alpha, and chemerin, respectively) control group 2 consisting of 30 non-obese was also included into this study. The relative level of mRNA expression of the genes IL-6, TNF-alpha and RARRES2 (encoding IL-6, TNF-alpha and chemerin, respectively) was carried out using real time PCR. Concentrations of IL-6, TNF-alpha, and chemerin were measured in serum/plasma using an enzyme-linked immunosorbent assay (ELISA). Significant differences were found in the plasma level of chemerin and tissue-specific patterns of RARRES2 gene expression in obese patients; these changes depended on the degree of obesity and the state of carbohydrate metabolism. Opposite associations between RARRES2 gene expression and expression TNF-alpha and IL-6 genes have been recognized in adipose tissues of different localization: in obese patients (BMI <= 40 kg/m(2)) without type 2 diabetes mellitus (DM2) they were negative, while in obese patients with DM2 diabetes they were positive. The recognized correlations between the plasma content of chemerin and the expression level of its gene in biopsies with various parameters of carbohydrate and lipid metabolism, and proinflammatory molecules indicate chemerin involvement in metabolic and immune processes in obesity.