Extended Data Figure 1: Breast tumours are frequently innervated by sensory nerves.
(a) We previously uncovered a requirement for endothelial-derived SLIT2 (ecSLIT2) in metastasis15.
(b) Quantification of ecSLIT2 expression in poorly vs highly metastatic breast tumour models. ****p < 0.0001, Mann-Whitney test. Mean ± SD.
(c-d) Quantification of total (c) and CGRP+ sensory (d) innervation in 4T1 tumours grown in ecSLIT2 knockout (endothelial-specific depletion of SLIT2) mice. **** p < 0.0001, *p = 0.0489, t-test. Mean ± SD.
(e) Quantification of innervation in SLIT2-knockout mammary tumours in Slit2fl/fl; MMTV-PyMT; MMTV-Cre mice. nsp = 0.6414, Mann-Whitney test. Mean ± SD.
(f) Kaplan-Meier plots showing distant metastasis-free survival (DMFS) of breast cancer patients sorted by the median expression level of βIII-tubulin (mRNA, protein) or PGP9.5 (mRNA) of their tumours. The x-axes were set to have >10 surviving patients in each arm.
(f) Nerve bundle abundance in highly metastatic primary tumours relative to corresponding isogenic poorly metastatic tumours. Between 4 and 8 tumours were analysed per group. **p (67NR vs 4T1) = 0.001, **p (4T07 vs 4T1) = 0.0019, nsp (67NR vs 4T07) = 0.9095, ANOVA; **p (EO771 Par vs LM2) = 0.0065, *p (HCC1806 Par vs LM2) = 0.0159, Mann-Whitney test. Mean ± SD.
(g) Expression of pan-neuronal βIII-tubulin in 67NR vs 4T1 primary tumours, stroma-depleted primary tumour organoids, or cell lines. **p = 0.0048, t-test. Mean ± SD. MW: βIII-tubulin (50 kDa).
(h) Liver metastasis from a 4T1 tumour-bearing mouse immuno-stained for nerve fibres. r = 3/group.
(i) Retrograde tracing of DRG neurons innervating abdominal mammary glands of wild-type mice. Mean ± SEM.
(k-l) Sensory, CGRP+ innervation observed within the normal murine mammary gland (k), murine models of breast cancer (l), and primary human tumours (l). r = 3 tumours/ group.