β2-adrenogenic signaling regulates NNK-induced pancreatic cancer progression via upregulation of HIF-1α

Abstract

Cigarette smoking is a risk factor for pancreatic cancer. It is suggested that 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific nitrosamine, mediates the carcinogenic action of cigarette smoking by promoting cancer growth. In the present study, we show that smoking, HIF-1α expression and β₂-adrenogenic receptor (β₂-AR) expression are negatively correlated with the overall survival of pancreatic cancer patients. Moreover, HIF-1α expression and β₂-AR expression are positively correlated with smoking status, different histological differentiation and among the tumor node metastasis (TNM) stages in pancreatic cancer patients. NNK increases HIF-1α expression in pancreatic cancer in vitro and in vivo. Furthermore, knockdown of HIF-1α and ICI118, 551 (a β₂-AR selective antagonist) abrogates NNK-induced pancreatic cancer proliferation and invasion in vitro and inhibits NNK-induced pancreatic cancer growth in vivo. However, using CoCl₂ (a HIF-1α stabilizing agent which decreases HIF-1α degradation under normoxia conditions) reverses ICI118, 551 induced effects under NNK exposure. Thus, our data indicate that β₂-AR signaling regulates NNK-induced pancreatic cancer progression via upregulation of HIF-1α. Taken together, β₂-AR signaling and HIF-1α may represent promising therapeutic targets for preventing smoking induced pancreatic cancer progression.