To investigate the preventive and therapeutic effects of Tanshinone ⅡA on radiation-induced heart disease (RIHD) through the regulation of the phosphoinositide 3-kinase/AKT/mechanistic target of rapamycin (PI3K/AKT/mTOR) signaling pathway, and to elucidate its underlying mechanisms based on animal and cellular experiments, thereby providing a theoretical foundation for developing targeted clinical prevention and treatment strategies.

In animal experiments, SPF-grade rats and mice were respectively divided into blank control group, model group and experimental group. A single dose of X-ray irradiation (25 Gy for rats, 20 Gy for mice) was administered to establish the RIHD model. The blank control group received normal feeding. The model group received normal feeding after modeling. The experimental group received daily intraperitoneal injections of Tanshinone ⅡA sulfonate sodium injection (1 mg/10 g body weight) for one week following modeling. In cell experiments, H9C2 cardiomyocytes were divided into normal cell group, injury-induced group and a drug-treated group. A radiation-induced RIHD cell model was established. The normal cell group was cultured under standard conditions. The injury-induced group was cultured normally after modeling. The drug-treated group was administered Tanshinone ⅡA sulfonate sodium (1μL·mL^-1 culture medium) immediately after modeling. Body weight changes and myocardial histopathological characteristics were dynamically monitored. Transcriptome sequencing was performed on cardiac apex tissues from both rats and mice for joint analysis, aiming to screen for common differentially expressed genes and enriched pathways. Cell viability was assessed using the cell counting kit-8 (CCK-8) assay. Cell membrane damage was evaluated by the lactate dehydrogenase (LDH) release assay. The expression levels of key genes in PI3K/AKT/mTOR pathway, including angiopoietin-2 (ANGPT2) and cyclin D1 (CCND1), as well as the protein levels of phosphorylated phosphoinositide 3-kinase (P-PI3K) and phosphorylated AKT serine/threonine kinase (P-AKT) were detected using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting, respectively.

Animal experiments showed that after the intervention, the body weights of rats in the blank control group, model group and experimental group were (434.37±8.52), (341.61±8.73) and (410.13±10.05) g, respectively; the body weights of mice were (30.97±0.89), (26.24±0.86) and (30.96±0.87) g, respectively; AST levels were (159.92±3.83), (171.04±2.63) and (149.63±10.55) U·L^-1, respectively; CK-MB levels were (219.00±5.83),(455.42±32.76) and (248.36±15.25) U·L^-1, respectively; LDH levels were (677.20±21.22),(864.63±6.39) and (635.77±22.72) U·L^-1, respectively; BNP levels were (29.37±6.04),(241.69±12.75) and (134.23±13.57) pg·mL^-1, respectively; GSH levels were (160.73±4.65), (330.38±9.41) and (116.71±11.29) U·L^-1, respectively. All the aforementioned indicators in model group showed statistically significant differences compared to blank control group, and all indicators in the experimental group showed statistically significant differences compared to model group (all P<0.001). In the cell experiments, joint transcriptome analysis revealed that 72% of homologous differentially expressed genes (624 in rats, 341 in mice) exhibited consistent expression trends in both species. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis indicated that ANGPT2, CCND1, THBS1, COL4A1, FN1 and COL4A2 were primarily enriched in the PI3K/AKT/mTOR pathway (all P<0.05), and PCR validation confirmed this consistent trend. In vitro experiments confirmed that the cell viabilities in normal cell group, injury-induced group and drug-treated group were (118.40±8.63)%, (73.10±6.12)% and (91.57±8.08)%, respectively. The differences between injury-induced group and normal cell group, as well as between drug-treated group and injury-induced group, were statistically significant (both P<0.001). The LDH release levels in injury-induced group and drug-treated group were (1.03±0.02) and (0.77±0.01)-fold that of normal cell group, respectively. The difference between the drug-treated group and the injury-induced group was statistically significant (P<0.001). The relative expression levels of P-PI3K in normal cell group, injury-induced group and drug-treated group were 0.92±0, 0.76±0.01 and 0.85±0.02, respectively; the relative expression levels of P-AKT were 0.79±0.01, 0.70±0.01 and 0.76±0.01, respectively. The differences between the injury-induced group and the normal cell group, as well as between the drug-treated group and the injury-induced group were statistically significant (all P<0.05).

Tanshinone ⅡA mitigates radiation-induced cardiac injury by activating the PI3K/AKT/mTOR signaling pathway, upregulating key phosphorylated proteins (p-PI3K and p-AKT), reducing radiation toxicity and enhancing cellular viability.