Circular RNA and Chemerin in Blood of Breast Cancer Patients

Breast cancer is the most common cancer among women and despite advances in therapy over the past few decades, drug resistance, recurrence, metastasis and the heterogeneity of the cancer continue to be a problem in successful management of the diseases(Hong et al ,2019) .

Circular RNAs (CircRNAs) are single-stranded, covalently closed RNA molecules that are ubiquitous across species ranging from viruses to mammals(Zhou et al 3 .,2020). circRNAs can be divided into two categories including coding and noncoding circRNAs(Li et al., 2019) A new subtype of RNAs is circular RNAs, single-strand RNA molecules with less than 100 to more than 4,000 nucleotides (Lu et al., 2016) and a covalently closedloop structure. These molecules are produced through a backsplicing mechanism, in which the downstream 5'-end of the splice donor joins the upstream 3'-end splice acceptor and forms a product with a circular structure (wang et al., 2017).

Chemerin is a leukocyte chemoattractant widely expressed in many tissues and is known to recruit innate leukocytes.

Recently, more and more studies focus on the relationship between chemerin and cancers and found that chemerin acts an essential role in cancers.(Shin et al,2018) Chemerin expression is different depending on the tumor type (Zhang Y et al, 2013) the clinical significance of chemerin in breast cancer has been only reported by a very limited number of studies (EL Sagheer et al,2018).