Circular RNAs as miRNA sponges in triple-negative breast cancer: a systematic review

iNtroDUctioN: triple-negative breast cancer (tNBc), characterized by a lack of receptors for estrogen (er), progesterone (Pr), and human epidermal growth factor 2 (Her2), is one of the worst prognoses of all breast cancer subtypes and is the most common cancer with the highest morbidity and mortality among women. Due to the absence of druggable molecular targets, its treatment options are very limited. circrNas represent attractive candidate diagnostic biomarkers for tNBc due to their natural characteristics such as a widespread existence, ease of detection, high stability, and a variety of regulatory functions. the aim of this review is to summarize all of the circrNas that have been investigated in the context of tNBc and to discuss the impact of circrNas on key cellular processes by acting as microrNa sponges for target mirNas in tNBc. eViDeNce acQUiSitioN: PubMed and Scopus were searched for all relevant published literature using the terms (circrNa or �circular rNa�) aND (cancer or carcinoma or tumor or neoplas* or tumour or malignan*) aND (�triple negative� or �triple-negative� or �tNBc�). eViDeNce SYNtHeSiS: the literature search yielded 33 articles; of these, only 13 eligible studies were included for systematic review. this study identifies a stable class of abundant circRNAs in TNBC that could be used to distinguish patients from controls with high sensitivity and specificity. Deaths from TNBC are among the leading causes of cancer death among females in over 100 countries, and there is an emphasis on the identification of earlier and less-invasive stages of the disease to achieve better clinical outcomes. coNclUSioNS: the results of this review seem to suggest that circrNas acting as mirNa sponges may present potential for use in targeted cancer treatment by modulating the expression of key oncogenes and tumor-suppressor genes. Because of their high stability, circrNas have been detected in clinical blood samples, saliva and exosomes, suggesting their promising prospects as biomarkers in the diagnosis of tNBc. © 2020 Edizioni Minerva Medica