TY - JOUR T1 - Identification of Breast Cancer Stem Cells Using a Newly Developed Long-acting Fluorescence Probe, C5S-A, Targeting ALDH1A1 JF - Anticancer Research JO - Anticancer Res SP - 1199 LP - 1205 DO - 10.21873/anticanres.15586 VL - 42 IS - 3 AU - AOI OKAMOTO AU - YOHEI FUNAKOSHI AU - MASAHIRO OE AU - RYO TAKAI AU - HIROTAKA SUTO AU - YOSHIAKI NAGATANI AU - MEIKO NISHIMURA AU - YOSHINORI IMAMURA AU - TOMONARI KUNIHISA AU - NAOMI KIYOTA AU - KOJI MIKI AU - KOUICHI OHE AU - HIROKAZU TANINO AU - HIRONOBU MINAMI Y1 - 2022/03/01 UR - http://ar.iiarjournals.org/content/42/3/1199.abstract N2 - Background/Aim: Aldehyde dehydrogenase (ALDH) 1A1 is a well-known marker for cancer stem cells (CSCs), characterized by self-renewal capacity and multidrug resistance in breast cancer. We developed a near-infrared turn-on fluorescence probe for ALDH1A1, C5S-A, which is suitable for observing and analyzing viable cells. Here, we demonstrated the utility of C5S-A in CSC research using breast cancer cell lines. Materials and Methods: To evaluate concordance between C5S-A and conventional stem cell markers, breast cancer cells sorted for ALDEFLUOR-positive cells and for CD44+/CD24– cell populations were stained with C5S-A. Tumorigenicity of C5S-A-positive cells was examined by mammosphere formation assay and subcutaneous transplantation to immunodeficient mice. Additionally, to determine how long fluorescence from a single staining remained observable, we cultured breast cancer cells for 5 days after C5S-A staining. We then evaluated whether C5S-A-positive cells possessed resistance to cytotoxic drugs by chronological imaging. Results: C5S-A staining showed good concordance with conventional breast CSC markers, and good utility for research into CSC characteristics in breast cancer cell lines, including tumorigenesis. Additionally, C5S-A was observable for more than 3 days with a single staining. Using this property, we then confirmed that C5S-A-positive cells possessed resistance to cytotoxic drugs, which is one of the characteristics of CSCs. Conclusion: We showed that C5S-A is suitable for CSC research using breast cancer cell lines, and confirmed its utility in observing cells over time. ER -