Signaling pathways involved in the regulation of the GPRC5A gene in T84 cells

MORI, CONSUELO; VALDIVIESO, ANGEL GABRIEL; CLAUZURE, MARIÁNGELES; MASSIP-COPIZ, MARÍA M; SANTA COLOMA, TOMAS A

Mar del Plata

Congreso; LXIII Reunión Anual de la Sociedad Argentina de Investigación Clínica - SAIC.; 2018

Sociedad Argentina de Investigación Clínica

The G protein-coupled receptor 5A (GPRC5A), also known as Retinoic acid-induced gene 3 (RAI3) or Retinoic acid-induced gene 1 (RAIG1). GPRC5A was first cloned in our laboratory with the name PEG-1 (phorbol ester induced gene-1), because it was found to be a 12-O-tetradecanoyl phorbol 13-acetate (TPA)-inducible gene. TPA, also called phorbol 12-myristate 13-acetate (PMA), is a small molecule drug that activates the signal transduction enzyme protein kinase C (PKC) by directly binding to its C1 domains. Commonly, TPA is employed as a tumor-promoting agent. GPRC5A dysregulation is associated to diverse types of cancer in humans and it was originally reported as a tumor suppressor in non-small cell lung carcinoma and in oral squamous cell carcinoma. In contrast, it has also been reported that GPRC5A could act as an oncogene in breast cancer, colorectal cancer and pancreatic cancer. This dual behavior makes GPRC5A an interesting gene to study. However, little is known about the function of this protein and its regulation. The aim of this work was studying the regulation of GPRC5A in human colon cancer. To determine the signaling pathways involved in this regulation, T84 cells (human colon adenocarcinoma cells) were stimulated with TPA for 4 h, in presence or absence of different pathway inhibitors, and the gene expression was analyzed by real-time PCR. PKC, PKA, MEK inhibitors and BAPTA treatment (intracellular calcium chelator) decreased significantly the GPRC5A mRNA expression. On the contrary, the SGK1, NF-kB, JNK and P38 inhibitors increased significantly GPRC5A mRNA levels. Interestingly, the AKT inhibitor in absence of TPA stimulation increased significantly the GPRC5A expression but did not show effect in presence of TPA. In conclusion, GPRC5A is regulated by multiple common pathways. Supported by PIP 2015-2017, PUE 22920160100129CO, and PICT-2015-1031 to AGV.