A small molecule screen identified N-Acetyl-L-cysteine for promoting ex vivo growth of single circulating tumor cell

CTCs contain a small subset of metastatic precursors that can form metastases in secondary organs, and provide a resource to identify mechanisms underlying metastasis-initiating properties. Despite technological advancements that allow for highly sensitive approaches of detection and isolation, CTCs are very rare and often present as single cells, posing an extreme challenge for ex vivo expansion after isolation. Here, using previously established patient-derived CTC lines, we performed a small molecule drug screening to identify compounds that can improve ex vivo culture efficiency for single CTCs. We found that N-acetylcysteine (NAC) and other antioxidants can promote ex vivo expansion of single CTCs, facilitating subsequent functional analyses. Overall design: single CTCs from the BRx68 were treated with various compounds as listed below for either 6 or 13 days and RNA sequencing analyses were performed to investigate the effects of the compounds on cells gene expression over time.