CAL-51 Cells

The CAL-51 cell line is a human breast adenocarcinoma model established from a malignant pleural effusion of a patient with advanced breast cancer. Characterized by epithelial morphology and a normal diploid karyotype, CAL-51 is particularly notable for its triple-negative breast cancer (TNBC) profile, lacking estrogen receptor (ER), progesterone receptor (PR), and HER2 expression. The absence of these markers, commonly used as therapeutic targets, makes CAL-51 a valuable model for studying TNBC, an aggressive subtype of breast cancer with limited treatment options. CAL-51’s tumorigenicity in immunocompromised mice and growth in soft agar demonstrate its malignant potential, making it suitable for in vitro and in vivo cancer research.
CAL-51 has also shown utility in studies investigating SARS-CoV-2 infection mechanisms. High expression of cellular entry factors ACE2 and TMPRSS2, along with neuropilin-1 (NRP1), renders CAL-51 permissive to SARS-CoV-2, facilitating viral entry and replication in cell culture. This makes CAL-51 a suitable model for exploring viral pathogenesis, as well as testing antiviral compounds and neutralizing antibodies targeted at SARS-CoV-2. Experiments demonstrate that therapeutic antibodies can block SARS-CoV-2 entry effectively in CAL-51 cells, highlighting its relevance as a model system for COVID-19 research and potential therapeutic evaluation.
In cancer research, CAL-51 is particularly useful for examining tumor heterogeneity, especially through its subpopulations of stem-like cancer cells known as side populations (SP), which express high levels of the ABCG2 transporter. SP cells in CAL-51 exhibit enhanced drug resistance and potential self-renewal, characteristics relevant to studies on cancer stem cell behavior and treatment resistance. As such, CAL-51 is a versatile model contributing to both cancer and viral infection studies, supporting research into challenging therapeutic areas such as TNBC and SARS-CoV-2.