Role of endoplasmic reticulum stress apoptosis protein in cardiac injury induced by endostar plus irradiation in rats / 中华放射肿瘤学杂志

ABSTRACT

Objective:To study the relationship between endoplasmic reticulum stress (ERS) and apoptotic protein and myocardial pathological changes in rats after endostar combined with low-dose X-ray irradiation.Methods:Forty SD rats were evenly divided into four groups: control group (intraperitoneal injection of equal volume physiological saline, once per day, 14 d), endostar group (intraperitoneal injection of endostar 6 mg/kg, once per day, 14 d), irradiation group (15 Gy divided into 3 times X-ray irradiation) and combination group (intraperitoneal injection of endostar after irradiation at the same dose and time as the endostar group). At 1 and 6 months after treatment, myocardial tissues of rats were prepared for HE staining and Masson staining to observe the myocardial histological changes. TUNEL assay was used to detect myocardial cell apoptosis, and ImageJ software was utilized to calculate myocardial collagen volume fraction (CVF). The expression levels of ERS and apoptotic protein glucose-regulated protein 78 (GRP78), protein kinase-like endoplasmic reticulum kinases (PERK), CCAAT/enhancer binding protein homologous protein (CHOP) and cysteine-containing aspartate-specific protease-12 (Caspase-12) were detected by Western blot. One-way ANOVA was conducted using GraphPad Prism 8.0.1 software, and comparison between two groups was conducted using t-test. Results:At 6 months after treatment, the myocardial interstitium in the irradiation and combination groups was widened, showing strip-like or reticular fibrosis changes, and the myocardial interstitium had diffuse collagen fiber deposition. Compared with the control group, CVF was increased significantly (both P<0.01). At 1 and 6 months after treatment, the apoptotic index of myocardial cells in the combination group was significantly higher than that in the control group ( P<0.05, <0.001). At 1 and 6 months after treatment, the expression levels of GRP78 protein in the irradiation and combination groups were increased (all P<0.01), and the expression levels of PERK and CHOP proteins in the combination group were increased compared to those in the control group (both P<0.05). At 6 months after treatment, the expression levels of PERK and CHOP proteins in the irradiation group were increased compared to those in the control group (both P<0.05). Compared with the control group, Caspase-12 expression levels at 1 and 6 months after treatment were increased in the endostar, irradiation and combination groups (all P<0.05). Conclusions:The expression levels of ERS and apoptotic proteins are related to cardiac injury caused by irradiation in rats. After low-dose X-ray combined with endostar treatment, ERS is aggravated and myocardial apoptosis is increased.