P1.03-03 Inhibition of H1299 Lung Cancer Cell Proliferation and Survival by Rosemary Extract Is Associated with AMPK Activation

Abstract

Non-small cell lung cancer (NSCLC) represents around 80% of all lung cancer cases and is characterized by low survival rates due to chemotherapy and radiation resistance. New treatments to inhibit NSCLC cell proliferation and survival are urgently needed. The energy sensor AMP-activated protein kinase (AMPK) is a serine/threonine kinase that plays a critical role in cancer cell metabolism, proliferation and survival. Activated AMPK leads to downstream inhibition of the mammalian target of rapamycin (mTOR) and p70S6K resulting in inhibition of protein synthesis and proliferation. Compounds of plant origin have attracted scientific attention for use as agents for cancer prevention and treatment. Rosemary extract (RE) has been shown to have anti-cancer effects. The objectives of the present study were to examine the effects of RE on H1299 human NSCLC cell proliferation and survival, and to investigate its effects on AMPK and its downstream signaling pathways which regulate cell growth and survival. Cell proliferation was measured using the crystal violet assay, clonogenic assays were performed to examine the effects of RE on cell survival and immunoblotting with specific antibodies was performed to examine signaling events. RE dose-dependently inhibited H1299 cell proliferation and survival. Maximum inhibition of H1299 cell proliferation (30.7±3.0% of control, p<0.001) was seen with 25μg/mL of RE. In addition, significant inhibition (42.3±1.9 % of control, p<0.001) of cell survival was seen with 2.5 μg/mL RE while 10 μg/mL RE caused near complete inhibition of survival (0.8±0.6% of control, p<0.001). AMPK phosphorylation levels were significantly increased by RE treatment. Our data indicate that treatment with RE significantly inhibits NSCLC cell proliferation and survival. AMPK phosphorylation/activation is significantly increased by RE treatment and the effects on signaling molecules downstream of AMPK are under investigation. Overall, our data suggest that RE may have potent anticancer properties in NSCLC and warrants further investigation.