Curcumin induces apoptosis and inhibits the growth of adrenocortical carcinoma: Identification of potential candidate genes and pathways by transcriptome analysis

Adrenocortical carcinoma (ACC) is an endocrine tumour with high malignancy, high invasiveness and poor prognosis. Curcumin, a major component in turmeric, has been reported to have good efficacy and biological safety in treating cancer. However, the role and mechanism of curcumin in ACC have not yet been fully investigated and were thus the focus of this study. In vitro, ACC SW-13 and NCI-H295R cells were treated with curcumin and their viability, migration and invasion were assessed by CCK-8 and Transwell assays. Apoptosis was detected via flow cytometry and western blotting. High-throughput sequencing and comprehensive bioinformatics analyses were performed to elucidate the molecular processes underlying curcumin activity. In vivo, SW-13 cells were injected into nude mice, and the tumour volumes and weights were observed after 2 weeks of curcumin treatment. Organelle changes were observed by electron microscopy, and potential candidate genes and pathways were analysed by RT-qPCR and western blotting. The role of the CHOP target gene in curcumin-induced ACC cell apoptosis was verified via lentiviral transfection experiments. Curcumin inhibited the viability, migration and invasion, and induced the apoptosis of ACC cells. Transcriptome sequencing analysis showed that curcumin treatment markedly changed the gene expression levels. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses showed that the MAPK and endoplasmic reticulum (ER) stress pathways were the predominant pathways associated with curcumin-induced apoptosis of ACC cells. Subsequent in vivo and in vitro results demonstrated that the JNK, p38 MAPK and ER stress pathways were activated in curcumin-treated ACC cells, and that C/EBP homologous protein induction was responsible for curcumin-induced apoptosis of ACC cells. In summary, curcumin induced ACC cell apoptosis and inhibited tumour growth by activating the JNK, p38 MAPK and ER stress pathways. Thus, curcumin may be a potential therapeutic drug for ACC.