Potential role of the bitter taste receptor T2R14 in the prolonged survival and enhanced chemoresponsiveness induced by apigenin

Abstract

Bitter taste receptors (T2Rs) are G protein-coupled receptors originally detected in the gustatory system. More recently, T2Rs have been shown to be expressed in extra-oral cells eliciting non-gustatory functions. Emerging evidence has suggested a potential role for T2R signaling in diverse pathophysiological conditions, including cancer. The aim of the present study was to evaluate the expression of T2R14 in pancreatic ductal adenocarcinoma (PDAC) and to assess its involvement in the anticancer effects induced by apigenin, a natural ligand of T2R14. For this purpose, T2R14 expression was explored in PDAC tumor tissue and tumor-derived cell lines. Using the cell lines expressing the highest levels of T2R14, its effects on chemoresponsiveness and migration upon activation with apigenin were investigated in vitro. To the best of our knowledge, the present study was the first to confirm the expression of the T2R family member T2R14 in PDAC. Patients with relatively high levels of T2R14 expression exhibited significantly prolonged overall survival compared with that of patients with low T2R14 expression. Furthermore, novel functions for apigenin were revealed; notably, apigenin was shown to elicit cytotoxic, anti-migratory and chemosensitizing effects to 5-fluoruracil (5-FU) and to 5-FU, leucovorin, irinotecan and oxaliplatin in pancreatic cancer cells. In conclusion, the present study extended the evidence for the anticancer effects of apigenin and strongly indicated the functional relevance of T2R14 in PDAC, even though their respective underlying pathways appear to be independent of each other.

Inhibiting a promiscuous GPCR: iterative discovery of bitter taste receptor ligands

“…Extra-oral expression of TAS2R14 has been confirmed in different tissues, including heart, lungs, thyroid gland and the brain [17][18][19][20] and linked with several physiological and pathological conditions [21]. For example, TAS2R14 in the human placental tissue has been suggested as contributor to the immunological regulation at the maternal-fetal interface [22]; activation of TAS2R14 expressed within the airway smooth muscle induces significant bronchodilation; increased TAS2R14 expression was associated with worse survival in adrenocortical carcinoma and esophageal adenocarcinoma [23], but prolonged overall survival in pancreatic ductal adenocarcinoma [24]. To unravel the physiological roles of TAS2Rs and TAS2R14 in particular, antagonists are of great importance.…”

Intracellular binding pocket revealed in the human bitter taste receptor TAS2R14

“…TAS2R14 overexpression was also documented in several types of cancer ( 12, 16 ), and its stimulation was shown to elicit anti-proliferative and pro-apoptotic effects in multiple cancer cell lines ( 17–19 ). In addition, individuals diagnosed with pancreatic adenocarcinoma that have elevated TAS2R14 expression levels show an extended overall survival compared to those with lower expression of the receptor ( 19 ). These findings highlight TAS2R14 as a broadly-tuned receptor that responds to a large variety of ligands, and underscore potential therapeutic applications that go beyond bitter sensing.…”

“…Polymorphisms in the TAS2R14 gene were associated with cardiac physiology (13) and male infertility (15). TAS2R14 overexpression was also documented in several types of cancer (12,16), and its stimulation was shown to elicit anti-proliferative and proapoptotic effects in multiple cancer cell lines (17)(18)(19). In addition, individuals diagnosed with pancreatic adenocarcinoma that have elevated TAS2R14 expression levels show an extended overall survival compared to those with lower expression of the receptor (19).…”