High-fat diet feeding and palmitic acid increase CRC growth in \u03b22AR-dependent manner

Sarwat Fatima,Zhaoxiang Bian,Rui-Hong Gong,Weixiong Zhang,Hiu Yee Kwan,Chunhua Huang,Alan H M Ho,Tao Su,Jing Cai,Hoi Leong Xavier Wong,Minting Chen,Min Huang,Xianjing Hu

doi:10.1038/s41419-019-1958-6

Abstract

Epidemiology studies indicate that consumption of high-fat diet (HFD) is directly associated with the development of colorectal cancer (CRC). However, the exact component in HFD and the mechanism underlying its effect on CRC growth remained unclear. Our study shows that HFD feeding increases β2AR expression in the xenograft tissues of CRC-bearing mouse model; the elevated β2AR expression is reduced when HFD is replaced by control diet, which strongly suggests an association between HFD feeding and β2AR expression in CRC. HFD feeding increases palmitic acid and stearic acid levels in CRC; however, only palmitic acid increases β2AR expression, which is dependent upon Sp1. β2AR plays the dominant role in promoting CRC cell proliferation among all the β-AR subtypes. More importantly, knockout of β2AR or knockdown of Sp1 abolishes the palmitic acid increased CRC cell proliferation, suggesting palmitic acid increases CRC cell proliferation in β2AR-dependent manner. HFD or palmitic acid-rich diet (PAD) also fails to increase the tumor growth in xenograft mouse models bearing β2AR-knockout CRC cells. β2AR promotes CRC growth by increasing the phosphorylation of HSL at the residue S552. The phosphorylated and activated HSL (S552) changes the metabolic phenotype of CRC and increases energy production, which promotes CRC growth. Our study has revealed the unique tumorigenic properties of palmitic acid in promoting CRC growth, and have delineated the underlying mechanism of action. We are also the first to report the linkage between HFD feeding and β-adrenergic signaling pathway in relation to CRC growth.

Highlights

Colorectal cancer (CRC) is one of the most common cancers in the world and presents one of the highest rates of morbidity and mortality worldwide[1]
high-fat diet (HFD) feeding increases β2-adrenergic receptor (β2AR) expression in CRC To explore the mechanism of action underlying how HFD promotes CRC growth, we first established a HFDassociated CRC xenograft mouse model
We found that β2-adrenergic receptor (β2AR) mRNA expression in the xenograft tissues of the HFDgroup were significantly higher than those in the control diet (CD) group (Fig. 1b)

Summary

Introduction

Colorectal cancer (CRC) is one of the most common cancers in the world and presents one of the highest rates of morbidity and mortality worldwide[1]. Epidemiology studies indicate that consumption of the western-style diet is directly associated with the development of CRC3; in which high-fat diet (HFD) contributes to 80% of the CRC cases[4]. Experimental studies only show that consumption of HFD will favor lipid oxidation which yields the products 4-hydroxynonenal and oxysterols that are the risk factors for inflammation and CRC development[5]. Another study shows that the saturated fat in HFD induces bile secretion into the intestine, which selects the gut microbes population and alters the bile acid pool.

Methods

Results

Conclusion