Fig. 1. LMSCs acquire increased metastasis-promoting ability along with tumor progression.

A H&E staining of lung sections from MMTV-PyMT mice at different tumor stages, adenoma (A), pre-metastatic (PM), and metastatic (M) stage. Scale bar represents 100 μm. The images were representative of those generated from five mice in each group. B Single-cell suspensions prepared from lung tissues of MMTV-PyMT mice at various time points were enumerated and analyzed by flow cytometry for CD45⁺ immune cells and 7AAD⁻ Lineage⁻ Sca1⁺ CD44⁺ LMSCs. n = 5, 5, 4, and 4 mice. C PM- or M-LMSCs promote lung metastasis in MMTV-PyMT mice. PBS or A-, PM-, and M-LMSCs (1 × 10⁵) were administered into MMTV-PyMT mice at the adenoma stage. Five weeks later, lung metastatic nodules (LMNs) were counted. n = 6 mice per group. D PM- or M-LMSCs promote lung colonization of intravenously injected 4T1 breast cancer cells. 4T1 cells were co-administered with WT-LMSCs from FVB or A-, PM-, and M-LMSCs from MMTV-PyMT mice at a 1 : 5 ratio (1 × 10⁴ LMSCs and 5 × 10⁴ 4T1 cells) into BALB/c mice by intravenous injection. After 14 days, LMNs were counted. From left to right: n = 5, 10, 10, 8, and 9 mice. E PM- or M-LMSCs promote lung metastasis of 4T1 cells implanted in fat pad. 4T1 cells (4 × 10⁵) were implanted into fat pads of BALB/c mice. After 10 days, WT-LMSCs or A-, PM-, and M-LMSCs (1 × 10⁵) were injected into these tumor-bearing mice by intravenous injection, respectively. LMNs were counted on day 30. n = 8 mice per group. All the data are presented as mean values ± SD. ns, not significant; p < 0.05, significant, using a one-way ANOVA with Sidak’s post test. Source data are provided as a Source Data file for Fig. 1B–E.