The Endoplasmic Reticulum Stress Response Mediates Shikonin-Induced Apoptosis of 5-Fluorouracil–Resistant Colorectal Cancer Cells
10.4062/biomolther.2021.118
- Author:
Mei Jing PIAO
1
;
Xia HAN
;
Kyoung Ah KANG
;
Pincha Devage Sameera MADUSHAN FERNANDO
;
Herath Mudiyanselage Udari LAKMINI HERATH
;
Jin Won HYUN
Author Information
1. Department of Biochemistry, Jeju National University College of Medicine, Jeju 63243, Republic of Korea
- Publication Type:Original Article
- From:Biomolecules & Therapeutics
2022;30(3):265-273
- CountryRepublic of Korea
- Language:English
-
Abstract:
Resistance to chemotherapeutic drugs is a significant problem in the treatment of colorectal cancer, resulting in low response rates and decreased survival. Recent studies have shown that shikonin, a naphthoquinone derivative, promotes apoptosis in colon cancer cells and cisplatin-resistant ovarian cells, raising the possibility that this compound may be effective in drug-resistant colorectal cancer. The aim of this study was to characterize the molecular mechanisms underpinning shikonin-induced apoptosis, with a focus on endoplasmic reticulum (ER) stress, in a 5-fluorouracil–resistant colorectal cancer cell line, SNU-C5/5-FUR. Our results showed that shikonin significantly increased the proportion of sub-G1 cells and DNA fragmentation and that shikonin-induced apoptosis is mediated by mitochondrial Ca 2+ accumulation. Shikonin treatment also increased the expression of ER-related proteins, such as glucose regulatory protein 78 (GRP78), phospho-protein kinase RNA-like ER kinase (PERK), phospho-eukaryotic initiation factor 2 (eIF2α), phospho-phosphoinositol-requiring protein-1 (IRE1), spliced X-box–binding protein-1 (XBP-1), cleaved caspase-12, and C/EBP-homologous protein (CHOP). In addition, siRNA-mediated knockdown of CHOP attenuated shikonininduced apoptosis, as did the ER stress inhibitor TUDCA. These data suggest that ER stress is a key factor mediating the cytotoxic effect of shikonin in SNU-C5/5-FUR cells. Our findings provide an evidence for a mechanism in which ER stress leads to apoptosis in shikonin-treated SNU-C5/5-FUR cells. Our study provides evidence to support further investigations on shikonin as a therapeutic option for 5-fluorouracil–resistant colorectal cancer.
