Abstract 201: Tribble 3 as integrator of metabolic stresses during lung cancer progression

Abstract

Abstract Introduction: Tribbles pseudokinase 3 (TRIB3) has been identified as a stress related gene. Recent studies reported the increased expression of TRIB3 in cancers and its correlation with the poor prognosis in cancer patients. However, other studies suggest TRIB3 as a tumor suppressor due to its inhibitory activities toward PI3K/Akt and Mek-Erk signaling. In the present study, we aim to investigate the expression of TRIB3 in lung cancer cells and whether it plays a role in lung cancer progression and responses toward chemotherapy. Methods: TRIB3 expression was determined by RT-PCR and Western blot. A lentiviral vector was used to overexpress TRIB3 in lung cancer cells. Small hairpin RNA constructs targeting TRIB3 were used to deplete TRIB3 expression. A CRISPR-CAS9 construct with guiding sequence matching to TRIB3 gene was used to knock out its expression. Cell proliferation, survival, and migration were determined using standard techniques. Results: Through in silico analyses, we found that high level of TRIB3 RNA was associated with poor survival of lung cancer patients. In lung cancer cells (NCI-H358), TRIB3 expression was markedly stimulated during metabolic stresses or ER stresses. Overexpression of TRIB3 in cells led to decreased cell proliferation and increased arrest at G0/G1 phase, even when the cells were not under overt metabolic stresses. RT-qPCR analyses of cell cycle proteins revealed an upregulation of p27, a CDK inhibitor, in cells overexpressing TRIB3. Overexpression of TRIB3 reduced Akt phosphorylation at threonine 308. Depletion or knockout of TRIB3 led to increased cell growth but cells became more sensitive to stressors, leading to increased apoptotic cell death. Conclusion: Our study reveals complex roles of TRIB3 in lung cancer progression. Induced by metabolic stresses, TRIB3 can block cell cycle progression through p27 in adaptive responses. Further studies are needed to determine whether and how TRIB3 functions as a metabolic gatekeeper during lung cancer progression. Citation Format: Abeer Almiman, Jamila Adom, Yande Guo, Jiuhui Wang, Daotai Nie. Tribble 3 as integrator of metabolic stresses during lung cancer progression. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 201.