Aim: To understand the epigenetic role of curcumin, a natural polyphenolic compound extracted from the spice Curcuma longa in inducing cytotoxicity in two molecularly distinct ovarian cancer cell lines: PA1 and A2780.
Materials and methods: An integrated mRNA-miRNA sequence analysis was performed to determine the curcumin-induced mRNA-miRNA regulatory networks in the induction of cytotoxicity. The miRNA-mRNA pathways, the miRNAs and their targets implicated in apoptosis, autophagy, DNA damage, and stemness markers were validated. Gene/miRNA expressions were validated using qPCR and protein expressions by western blotting. Curcumin-induced oncogenic /tumor-suppressor miRNAs were profiled utilising the oncomiRdb database. Similarly, the expressions of oncogenes/tumor suppressor genes were profiled and correlated with the TCGA ovarian cancer dataset. A dual luciferase assay was performed to investigate the interaction of miR-199a-5p to its direct target, DDR1.
Key findings: The expression of several miRNAs demonstrated an inverse correlation with their respective direct targets. In curcumin-treated PA1 cells, miR-335-5p target ATG5 (autophagic), and OCT4 (pluripotent gene) were downregulated, miR-32a target PTEN (tumor suppressor) was upregulated, miR-1285 target P53 (tumor suppressor) was upregulated, and both miR-182-5p and miR-503-3p target BCL2, were down-regulated. Contrastingly, in curcumin-treated A2780 cells, miR-181a-3p target ATG5, miR-30a-5p, and miR-216a target BECN1 (autophagic) were upregulated, and miR-129a-5p target BCL2 were downregulated. The reversal of the oncomiR/TSmiR profile revealed suppression of oncogenic processes by curcumin. Curcumin treatment induced a moderate cisplatin-sensitisation effect and impaired epithelial-to-mesenchymal transition (EMT) characteristics. Curcumin also regulated the miR-199a-5p/DDR1 axis with a decrease in collagen deposition.
Significance: The activity of curcumin is cell-type specific. Distinct miRNA regulatory networks were activated to induce multiple modes of cellular cytotoxicity in these ovarian cancer cells. This study further highlights the molecular mechanism of curcumin action in ovarian cancers establishing its candidacy as a promising drug candidate.
Keywords: Cisplatin; Curcumin; DDR; EMT; MicroRNA; Transcriptomics.
Copyright © 2023. Published by Elsevier Inc.