Endothelin-1 as a Mediator of Heme Oxygenase-1-Induced Stemness in Colorectal Cancer: Influence of p53.

Sandra Ríos-Arrabal,Ángel Carazo,Julia Escudero-Feliu,Jorge Casado,Sara Moreno-Sanjuan,Michela Verbeni,Jose D Puentes-Pardo,María García-Costela,Alicia Martín-Lagos Maldonado,Carlos Cano,Ágata Szuba,Cristina González-Puga,Josefa León

doi:10.3390/jpm11060509

Abstract

Heme oxygenase-1 (HO-1) is an antioxidant protein implicated in tumor progression, metastasis, and resistance to therapy. Elevated HO-1 expression is associated with stemness in several types of cancer, although this aspect has not yet been studied in colorectal cancer (CRC). Using an in vitro model, we demonstrated that HO-1 overexpression regulates stemness and resistance to 5-FU treatment, regardless of p53. In samples from CRC patients, HO-1 and endothelin converting enzyme-1 (ECE-1) expression correlated significantly, and p53 had no influence on this result. Carbon monoxide (CO) activated the ECE-1/endothelin-1 (ET-1) pathway, which could account for the protumoral effects of HO-1 in p53 wild-type cells, as demonstrated after treatment with bosentan (an antagonist of both ETRA and ETRB endothelin-1 receptors). Surprisingly, in cells with a non-active p53 or a mutated p53 with gain-of-function, ECE-1-produced ET-1 acted as a protective molecule, since treatment with bosentan led to increased efficiency for spheres formation and percentage of cancer stem cells (CSCs) markers. In these cells, HO-1 could activate or inactivate certain unknown routes that could induce these contrary responses after treatment with bosentan in our cell model. However more research is warranted to confirm these results. Patients carrying tumors with a high expression of both HO-1 and ECE-1 and a non-wild-type p53 should be considered for HO-1 based-therapies instead of ET-1 antagonists-based ones.

Highlights

Worldwide, colorectal cancer (CRC) annually affects more than one million men and women and causes more than half a million deaths [1]
In order to investigate whether heme oxygenase-1 (HO-1) conferred stem cell properties on CRC cells, we used the pCMV6-HMOX1 plasmid to transiently overexpress HO-1 in HCT-116, HCT-116 p53 null, and HT-29 cells
In HT-29 cells, the percentage of ALDH1+ cells was lower in pCMV6-HMOX1 versus mock transfected cells at 72 h after transfection, whereas the percentage of this subpopulation was similar in control and HO-1 overexpressing cells at 96 h (Figure 1c)

Summary

Introduction

Colorectal cancer (CRC) annually affects more than one million men and women and causes more than half a million deaths [1]. Tumor heterogeneity associated with changes in gene expression or in epigenetics supports the existence of therapy-resistant cancer cells. These cells, usually called cancer stem cells (CSCs) or tumor-initiating cells (TICs), represent a small fraction within the cancer and are responsible for initiating, maintaining, and developing cancer growth [3]. HO-1 is a protein sensitive to oxidative stress, growth factors, pathogen-associated molecular patterns (PAMPs), cytokines, metalloporphyrins, heme, and heavy metals. In some cell types and under certain circumstances, it may amplify intracellular oxidative stress and exacerbate the disease process [9]

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