Establishment and characterization of novel highly aggressive HER2-positive and triple-negative breast cancer cell lines

Breast cancer cell lines are widely used as an in vitro system with which to study the mechanisms underlying biological and chemotherapeutic resistance. In the present study, two novel breast cancer cell lines designated as PC-B-142CA and PC-B-148CA were successfully established from HER2-positive and triple-negative (TN) breast cancer tissues. The cell lines were characterized by cytokeratin (CK), α-smooth muscle actin (α-SMA), fibroblast-activation protein (FAP) and programmed death-ligand 1 (PD-L1). Cell proliferation was assessed using a colony formation assay, an MTS assay, 3-dimensional (3-D) spheroid and 3-D organoid models. Wound healing and Transwell migration assays were used to explore the cell migration capability. The responses to doxorubicin (DOX) and paclitaxel (PTX) were evaluated by 3-D spheroids. The results showed that the PC-B-142CA and PC-B-148CA cell lines were α-SMA-negative, FAP-negative, CK-positive and PD-L1-positive. Both cell lines were adherent with the ability of 3-D-multicellular spheroid and organoid formations; invadopodia were found in the spheroids/organoids of only PC-B-148CA. PC-B-142CA had a faster proliferative but lower metastatic rate compared to PC-B-148CA. Compared to MDA-MB-231, a commercial TN breast cancer cell line, PC-B-148CA had a similar CD44⁺/CD24^- stemness property (96.90%), whereas only 8.75% were found in PC-B-142CA. The mutations of BRCA1/2, KIT, PIK3CA, SMAD4, and TP53 were found in PC-B-142CA cells related to the resistance of several drugs, whereas PC-B-148CA had mutated BRCA2, NRAS and TP53. In conclusion, PC-B-142CA can serve as a novel HER2-positive breast cancer cell line for drug resistance studies; while PC-B-148CA is a novel TN breast cancer cell line suitable for metastatic and stemness-related properties.