Figure 5.

Mast cell deficiency protects mice from Lewis lung adenocarcinoma growth in the skin and its metastasis to the alveolar regions.

C57BL/6 controls (cKit^Wt/Wt and Cpa3.Cre^−/- littermate controls, as well as Lyz2.Cre mice), cKit^Wsh/Wt, cKit^Wsh/Wsh, and Cpa3.Cre mice, all on the C57BL/6 background (n = 13, 7, 7, and 6, respectively), received 10⁶ subcutaneous Lewis lung carcinoma cells (LLC), were followed for one month by weekly measurement of three vertical primary tumor diameters (δ) and calculation of primary flank tumor volume (V = πδ³/6) and were sacrificed for primary tumor and spontaneous lung metastasis analyses at one month post-LLC cells. A Schematic time-course of the experiment with boxes representing one week. B Data summary of primary subcutaneous tumor volume expressed as percentage of C57BL/6 controls (mean±SEM) with two-way ANOVA P value. * and ***: P< 0.05 and P< 0.001, respectively, for comparison with C57BL/6 controls by Bonferroni post-tests. C Data summary of absolute lung metastasis volume (burden) per lung. D-J Toluidine blue-counterstained primary LLC tumor sections of C57BL/6 control mice (n = 10) labeled for proliferating cell nuclear antigen (PCNA), a technique that allows simultaneous visualization and quantification of proliferating cells (brown), mast cells (purple), and nuclei (blue). Shown are representative mast cell hotspot (D; dashed line) and areas of such hotspots featuring mast cells in close association/contact with proliferating tumor cells (E-J; arrows). K-N Data summary of percentage of PCNA+ primary tumor cells (K), primary tumor mast cell density (L), percentage of PCNA+ cells in mast cell hotspots versus mast cell-devoid areas of primary tumors of C57BL/6 mice (M), and correlation of these two parameters in mast cell hotspots of primary tumors of C57BL/6 mice (N). (K, L) n = 10, 7, 7, and 6, respectively. (M) n = 10 C57BL/6 mice. (N) n = 2 hotspots from each of 10 C57BL/6 mice. Data information: (C, K, L, M) Data are shown as Tukey’s whiskers (boxes: interquartile range; bars: 50% extreme quartiles), raw data points (dots), and Kruskal–Wallis ANOVA (C, K, L) and Mann–Whitney u-test (M) P values. *, **, and ***: P< 0.05, P< 0.01, and P< 0.001, respectively, for comparison with C57BL/6 controls or as indicated by Dunn’s post-tests. Only statistically significant differences are indicated. (N) Shown are data points, Pearson correlation P value and coefficient, and linear regression line and formula.