Decreased concentrations of intracellular signaling proteins in colon cancer patients with BRAF mutations

Dorte Aa Olsen,Anders Jakobsen,Jonna S Madsen,Ivan Brandslund,Rikke F Andersen,Caroline E B Thomsen

doi:10.1038/s41598-020-77109-8

Dorte Aa Olsen, Anders Jakobsen + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-77109-8

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Abstract

The activation of intracellular signaling pathways plays a critical role in cancer pathogenesis. The current study aims to quantify intracellular signaling proteins in localized colon cancer tissue to investigate the prognostic value of these biomarkers and elucidate their possible relations to mutation status. Colon cancer tissue and autologous reference tissue were collected from 176 patients who underwent colon cancer surgery. Assays were developed to quantify ERK, AKT and cyclin d using single-molecule array technology. KRAS/BRAF/PIK3CA mutation status was determined using droplet digital PCR. Patients with BRAF mutations had decreased concentrations of ERK (p = 0.0003), AKT (p = 0.0001) and cyclin d (p = 0.003), while no significant differences were found between patients with KRAS mutations and wild-type patients. None of the investigated proteins were associated with disease-free survival or overall survival when all patients were included. However, when patients were stratified according to mutation status, significant correlations with overall survival were seen for patients with BRAF mutations and AKT (p = 0.002) or ERK (p = 0.03) and for KRAS mutations and cyclin d (p = 0.01). Conclusions: A strong correlation exists between intracellular signaling protein concentrations and mutational BRAF status. Overall survival in colon cancer patients depends on both gene mutation status and signaling protein concentrations.

Highlights

Abbreviations Simoa Single molecule array SβG Streptavidin-β-galactosidase RGP Resorufin-β-d-galactopyranoside AEB Average number of enzymes per bead
Autologous reference tissue and cancer tissue. total protein levels of ERK (tERK), phosphorylated ERK (pERK), tAKT, phosphorylated AKT (pAKT) and cyclin d were measured in both autologous reference tissue and colon cancer tissue (Fig. 2; Table 2)
Both pERK and tERK were found to be down-regulated in cancer tissue (p = 0.001), while pAKT, tAKT and cyclin d showed no differences between the tissues

Summary

Introduction

Abbreviations Simoa Single molecule array SβG Streptavidin-β-galactosidase RGP Resorufin-β-d-galactopyranoside AEB Average number of enzymes per bead. The intracellular signaling network of the epidermal growth factor receptor (EGFR) consists of two key signal pathways: the mitogen-activated protein kinase (MAPK), termed RAS/RAF/MEK/ERK, and the phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (AKT) pathways. These signal pathways interact in a complex and coordinated manner to regulate all stimulated cellular processes and have been described in d etail[1,2]. Both ERK and AKT activate more than 100 downstream proteins from the cytosol to the nucleus, including transcription factors, protein kinases, phosphatases and cytoskeletal elements. It is important to detect such mutations at an early, pre-treatment phase to predict whether patients will benefit from the treatment or only experience its side effects

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