Natural compounds are recently booming as promising immunomodulatory anticancer agents in several cancers including breast cancer (BC). Recently, our group has shown the anticancer activity of several phytoconstiuents through repressing several oncogenic signals. Yet, unraveling their regulatory effect at the immune synapse is still a virgin field. The immune suppressive tumor microenvironment (TME) represents the rate limiting step in the success of any immunotherapeutic approach. Thus our aim is to identify a natural compound to trim the immune suppressive TME through its regulatory effect on a recent class of complex regulators known as competing endogenous RNAs. Ursolic acid (UA) is a phytoconstituent that is abundant in rosemary. Its anticancer activity has been confirmed. Yet, the molecular mechanisms behind it is still unraveled. In this study, we intended to investigate the anti-cancer and immunological effects of UA on BC through the regulation of a pool of ceRNAs and immune suppressive cytokines at the TME of BC cells.
Computational target prediction analysis was performed. UA was isolated from rosemary. MDA-MB-231 cells were treated with different concentrations of UA (20-100μM). IC50 value was calculated using dose response curve. MTT, colony forming assay and Scratch assay were performed. Total RNA was extracted and quantified by qRT-PCR. IL-10 anf TNF-α Elisa Kits were used.
In-silico, miR-17-5p, MALAT-1 and H19 were found to target the immune suppressive cytokines IL-10 and TNF-α with high binding scores. UA resulted in a dose- and time-dependent repression of several BC hallmarks such as cellular viability, clonogenicity and migration capacity. Molecularly, UA was found to alter the ceRNAs network through inducing miR-17-5p and MALAT1 levels in treated cells compared to vehicle control BC cells. Yet, H19 was found to be repressed. At the Immune synapse, UA was found to repress IL-10 and TNF-α mRNA and protein levels.
This study crystallizes a novel mechanism of Rosemary and UA as promising immunoregulatory anticancer agents at the BC immune synapse through altering H19/MALAT-1/miR-17-5p circuit and the immune suppressive cytokines: IL-10 and TNF-α.
German University in Cairo.
Has not received any funding.
All authors have declared no conflicts of interest.