High-fat diet induced leptin and Wnt expression: RNA-sequencing and pathway analysis of mouse colonic tissue and tumors

Abstract

Obesity, an immense epidemic affecting approximately half a billion adults, has doubled in prevalence in the last several decades. Epidemiological data support that obesity, due to intake of a high-fat, western diet, increases the risk of colon cancer; however, the mechanisms underlying this risk remain unclear. Here, utilizing next generation RNA sequencing, we aimed to determine the high-fat diet (HFD) mediated expression profile in mouse colon and the azoxymethane/dextran sulfate sodium model of colon cancer. Mice on HFD had significantly higher colonic inflammation, tumor burden, and a number of differentially expressed transcripts compared to mice on regular diet (RD). We identified 721 transcripts differentially expressed in mouse HFD colon that were in a shared pattern with colonic tumors (RD and HFD). Importantly, in mouse colon, HFD stimulated an expression signature strikingly similar to human colon cancer, especially those with inflammatory microsatellite instability. Furthermore, pathway analysis of these transcripts demonstrated their association with active inflammation and colon cancer signaling, with leptin and Wnt as the top two transcripts elevated in mouse HFD colon shared with tumors. Moreover, in mouse colon, HFD-stimulated tumorigenic Wnt pathway activation was further validated by upregulation of β-catenin transcriptional targets. Finally, in human colon cancer, upregulation of leptin pathway members was shown with a large network of dysregulated transcripts being linked with worse overall survival.

Switching to a Healthy Diet Prevents the Detrimental Effects of Western Diet in a Colitis-Associated Colorectal Cancer Model

“…Feeding the mice the WD perturbed the regeneration process, mainly in the ascending colon by reducing proliferation and expression of Wnt target genes. These findings were unexpected, as several studies reported the opposite [61,62]. Nevertheless, in a recent study in DSS-treated mice, reduced mucosal proliferation promoted the development of colonic dysplasia [63].…”

Autophagy inhibition in 3T3-L1 adipocytes breaks the crosstalk with tumor cells by suppression of adipokine production

“…The RNA-Seq study by Mangiola et al (2018) suggests that periprostatic adipose tissue from patients with high-risk prostate cancer has a distinct transcriptional signature, which was confirmed by qPCR in an expanded cohort. In particular, Leptin and Wnt have been demonstrated as the top two transcripts elevated in mouse high fat diet colon shared with tumors, using next generation RNA sequencing and pathway analysis (Penrose et al 2017).…”

In colonic ρ0 (rho0) cells reduced mitochondrial function mediates transcriptomic alterations associated with cancer

“…RNA isolation, cDNA synthesis, sequencing, differential expression testing, and pathway analysis were performed as described before [ 21 , 43 ]. Sequencing data for this study is available through NCBI's Sequence Read Archive (SRA) with accession number SRP093357.…”

“…Total RNA was extracted with QIAzol Lysis Reagent (Qiagen) followed by reverse transcription employing the SuperScript First-Strand Synthesis System (Thermo Fisher Scientific) and Oligo-dT12-18 primers according to the standard protocol [ 21 , 43 ]. The following primers were used for quantification of cDNA specifically binding FLRT3 (FLRT3-FOR 5′-GGTATTGCGGGTGCAAGATG-3′, FLRT3-REV 5′-GCCATCCCACGAACCTTTTC-3′), DGKI (DGKI- FOR 5′-CAGGTCTCGTACAGGAAAGCA-3′, DGKI REV-5′-ACTCCACTCCAAAGTCGCTC-3′), IFI16 (IFI16-FOR 5′-GAAGTGCCAGCGTAACTCCT-3′, IFI16-REV 5′-ACCTCAAACACCCCATTCACA-3′), and HPRT1 (HPRT1-FOR 5′-GACCAGTCAACAGGGGACAT-3′, HPRT1-REV 5′-AACACTTCGTGGGGTCCTTTTC-3′).…”