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Fig. 5 | Breast Cancer Research

Fig. 5

From: OSM potentiates preintravasation events, increases CTC counts, and promotes breast cancer metastasis to the lung

Fig. 5

Reduced tumor cell oncostatin M (OSM) expression increases survival in a 4T1.2-shOSM mouse model of tumor resection. a Timeline shows orthotopic mouse mammary tumor cell injection at day 0, resection at day 14, and final day of killing per group (ranging from 35 to 72 days). Kaplan-Meier survival analysis following tumor resection showed that mice bearing 4T1.2-shOSM1 or 4T1.2-shOSM2 tumors had significantly increased survival compared with mice with control 4T1.2-shLacZ tumors. *p < 0.05 by log-rank test. b Timeline shows intracardiac mammary tumor cell injection at day 0 and final day of killing (days 21 to 22). Kaplan-Meier survival analysis showed no difference in survival between mice injected with control 4T1.2-shLacZ and those injected with 4T1.2-shOSM2 cells. c Blood was collected from wild-type and OSM-knockout (OSM-KO) animals with 4T1.2-shOSM2 or control tumors, and circulating tumor cell (CTC) counts were assessed via a colony-forming assay. Representative image depicts higher numbers of colonies that formed from the blood collected from wild-type mice with control tumors. d Left: Quantification of the colony-forming assay showed that wild-type animals bearing 4T1.2-shOSM2 tumors had a 15-fold lower number of CTCs than the animals bearing control 4T1.2-shLacZ tumors. Furthermore, OSM-KO mice with 4T1.2-shLacZ tumors had 10-fold less CTCs than wild-type mice bearing the same cells. Right: Wild-type mice bearing 4T1.2-shOSM2 tumors had a 2.5-fold lower number of lung metastases than mice with control 4T1.2-shLacZ tumors. OSM-KO mice bearing 4T1.2-shLacZ or 4T1.2-shOSM2 tumors had 2- to 2.5-fold less lung metastases than wild-type mice (4T1.2-shLacZ, n = 8–9; 4T1.2-shOSM1, n = 7; 4T1.2-shOSM2, n = 9–12). Data are expressed as mean ± SEM. *p < 0.05 and ***p < 0.001 by one-way analysis of variance with Tukey’s multiple comparisons test

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