Figure 4.

Irradiation sensitizes CSCs to NK cell attack in vitro and in vivo. (A, B) CSC frequency of indicated tumor cell lines, as assessed by ALDH activity, following 24 h incubation under the indicated treatment conditions. (C, D) CSC frequency of indicated primary tumor sample as assessed by flow cytometric analysis of CD24⁺/CD44⁺/ALDH bright (C) or ALDH bright (D) remaining following 24 h incubation under the indicated treatment conditions. (E–I) Numbers of CSCs remaining from experiments described in C and D. (H) Numbers of non-CSCs in primary pancreatic tumor sample, FPA2, after RT and with/without NK co-culture. (J) Frequency of CSCs (ALDH bright) remaining from patient-derived xenografts of the leiomyosarcoma, PDX-SA4, as assessed using flow cytometry, 5 d after the indicated treatments in vivo. (K) expression of CSCs as assessed by flow cytometric analysis of ALDH expression or CD24⁻CD44⁺ expression on patient-derived xenografts of the mammary carcinoma, PDX-BR1, 5 d after the indicated treatments in vivo. Statistical significance was determined by one-way ANOVA with a Bonferroni post-test where *p ≤ 0.05; **p ≤ 0.01, ***p ≤ 0.001, and ****p ≤ 0.0001.