The α2δ1 subunit of the voltage-gated calcium channel as a potential candidate for breast cancer tumor initial cells biomarker

The voltage-gated calcium channel subunit alpha 2 delta 1 (α2δ1) is a functional tumor initial cells (TICs) marker for some solid cancer cells. This study aimed to investigate whether α2δ1 can be used as a potential TIC marker for breast cancer cells.α2δ1+ and α2δ1- cells were identified and sorted from the breast cancer cell lines MDA-MB-231, MDA-MB-435s and ZR-75-1 by Immunofluorescence (IF) and Fluorescent-activated cell sorting (FACS) analyses. Spheroid formation in vitro and tumorigenesis in NOD/SCID mice were assessed to determine the self-renewal and serial transplantation abilities of these cells. Using a lentivirus infection system for α2δ1 in breast cancer cell lines, we determined the mRNA levels of stemnessassociated genes by quality real-time PCR (qRT-PCR). Boyden chamber and wounding assays were further performed to detect the migration of α2δ1 overexpression cells. Bioinformatics explored the relationship of molecular classification of breast cancer and drug resistance.α2δ1 presents on the cytomembrane of breast cancer cells, with a positive rate of 1.5-3%. The α2δ1+ cells in breast cancer cell lines have a stronger self-renewal ability and tumor initiating properties in vitro and in vivo. Overexpressing α2δ1 successfully enhanced the sphere-forming efficiency, and upregulated the expression of stemness-associated genes, and increased cell migration. However, seldom significant was available between estrogen receptor +/- (ER+/-), progesterone receptor (PR+/-), and Her2+/-.Breast cancer cells positive for the α2δ1 charactered tumor initiation, and α2δ1 is a potential TIC marker for breast cancer that further promotes the migration.