Figure 1. B7-H3 expression on tumorigenic cancer initiating cells isolated from human cancer cell lines.

High ALDH activity (ALDH^bright cells) is used as a marker to identify cancer initiating cells (CICs). Immunodeficient NOD/SCID mice were challenged with 500 ALDH^bright and ALDH^neg cells sorted from a (A) HNSCC or (B) PDAC cell line. In both models, tumors developed only in anatomic sites injected with ALDH^bright cells, but not ALDH^neg tumor cells. CICs from HNSCC (JHU029) and PDAC (PDAC3) human cell lines stained with the B7-H3-specific mAb 376.96 demonstrate high B7-H3 expression (C). ALDH: aldehyde dehydrogenase; HNSCC: head and neck squamous cell cancer; PDAC: pancreatic ductal adenocarcinoma. ALDH^bright cells are identified as those ALDH⁺ cells with twice the mean fluorescence intensity of the ALDH⁺ population.