Kirenol Inhibits B[a]P-Induced Oxidative Stress and Apoptosis in Endothelial Cells via Modulation of the Nrf2 Signaling Pathway.

Peramaiyan Rajendran,Abdullah M. Alzahrani,Vishnu Priya Veeraraghavan,Emad A. Ahmed,Albino Carrizzo

doi:10.1155/2021/5585303

Abstract

Atherosclerosis is a persistent inflammatory disorder specified by the dysfunction of the arteries, the world's leading cause of cardiovascular diseases. We sought to determine the effectiveness of KRL in B[a]P-induced oxidative stress and programmed cell death in endothelial cells. Western blotting, real-time PCR, DCFH2-DA, and TUNEL staining were performed to detect pPI3K, pAKT, Nrf2, HO-1, NQO-1, Bcl2, Bax, and caspase-3 on the HUVECs. Through the pretreatment of KRL, a drastic enhancement was observed in the cell viability of HUVECs, whereas DNA damage and generation of reactive oxygen species induced by B[a]P was suppressed. KRL's potential use as an antioxidant was observed to have a direct correlation with an antioxidant gene's augmented expression and the nuclear translocation activation of Nrf2, even during the event when B[a]P was found to be absent. In addition, this study proved that the signaling cascades of PI3K/AKT mediated Nrf2 translocation. Activation of suppressed nuclear Nrf2 and reduced antioxidant genes across cells interacting with an LY294002 confirmed this phenomenon. In addition, knockdown of Nrf2 by Nrf2-siRNA transfection abolished the protective effects of KRL on HUVECs cells against oxidative damage. Finally, the expression of apoptotic proteins also supported the hypothesis that KRL may inhibit endothelial dysfunction. This study showed that KRL potentially prevents B[a]P-induced redox imbalance in the vascular endothelium by inducing the Nrf2 signaling via the PI3K/AKT pathway.

Highlights

As pervasive environmental carcinogens, heterocyclic aromatic hydrocarbons cause genetic damage and endowed with a strongly bioaccumulation attribute
This study used the following antibodies: antibodies against pAKT, AKT, pPI3K, phosphatidylinositol 3-kinase (PI3K), BCL2, BAX, heme oxygenase-1 (HO-1), NQO-1, pNrf2, actin, and lamin B1 derived from Invitrogen, Waltham, MA-based Thermo Fisher Scientific, Inc., LY294002 (L9908)
For ascertaining whether the pathway’s activation by KRL played an important role in ensuring HUVECs cells’ survival rate by modulating the expression of HO-1, we examined the kind of impact of LY294002 had on the protein expression of the aforementioned protein signals

Summary

Introduction

Heterocyclic aromatic hydrocarbons cause genetic damage and endowed with a strongly bioaccumulation attribute. As a PAH (polyaromatic hydrocarbon), benzo[a]pyrene (B[a]P) finds itself in first class of carcinogens issued by the International Agency for Research on Cancer. 9.20 ng/day is the maximum exposure of people to this PAH [1]. According to a vast body of scholarly research, one of the strongest causes of vascular inflammation is oxidative stress [4]. Previous literature in animal models clearly illustrated that direct exposure to B[a]P can cause including cancers and pulmonary, neurodegenerative, and cardiovascular diseases [2, 5,6,7]. Atherosclerosis is thought, at least in part, to be an inflammatory mechanism caused by free radicals [8, 9].

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