STING Expression and TNBC Sensitivity

Example 3

STING protein expression was measured in different breast cancer cell subtypes by western blot analysis on protein extracts from the breast cancer cell lines. Western results are shown in FIGS. 22A and 22C. STING protein levels are shown relative to β-actin control protein levels. Genotypes of the cell lines (ER+/−, PR+/−, and HER2+/−) are shown in FIG. 22B. The data presented herein demonstrates that STING levels are generally increased in TNBC (Triple Negative Breast Cancer) and luminal B cancer cell subtypes.

TNBC cell lines were also assayed for their responsiveness to the STING agonist AduroS100. Cells were treated with AduroS100 or a control and CXCL10 levels secreted into the supernatant were measured. As is shown in FIG. 22D, all TNBC cell lines showed elevated levels of the CXCL10 chemokine when treated with AduroS100 relative to a control, indicating that TNBC cells are responsive to treatment with a STING agonist, regardless of STING levels.