Figure 7.

JAK inhibition has no in vitro growth effects yet inhibits tumor growth and metastasis of 4T1 mammary cancers. (A) 4T1 breast cancer cells were grown in culture treated with JAKi (1 µM) or vehicle control. Calcein AM was performed daily (C). Extracts from these cells were analyzed for pStat3 and Stat3 by Western blot. (B) 4T1 cells were injected into the tail vein of mice (1 x 10⁵), and once BLI values reached ∼5 x 10⁶, mice were randomized to receive vehicle control (C) or JAKi (30 mg/kg twice daily). Normalized BLI signal of the mice (n = 10/group) was determined weekly. (C) 4T1 cells (2 x 10⁵) were injected into the MFP of BALB/c mice, which were randomized to receive vehicle (C) or JAKi (30 mg/kg twice daily). Normalized BLI signals of MFP (n = 10/group) were determined weekly. Tumor weight and spontaneous lung metastasis for either vehicle (C) or JAKi-treated mice were determined after 3 weeks. (D) Representative IHC images of tumors from vehicle (C) and JAKi-treated 4T1 tumor-bearing mice stained for pStat3, CD45, Meca-32, and SMA. **P < .01, *P < .05.