Fig. 3: TMEM activity-MRI corresponds to metastatic dissemination endpoints in a mouse model of spontaneous breast carcinoma (MMTV-PyMT; a–k) and a breast cancer patient-derived xenograft (HT17; a′–h′), and is suppressed by the specific TMEM doorway inhibitor, rebastinib.

a–a′ Experimental strategy and mouse cohort composition for syngeneic (A) and xenogeneic (A′) mouse models of breast carcinoma. PyMT polyoma middle-T antigen, CTC circulating tumor cell, SCID severe combined immunodeficiency, FVB friend virus B. b–b′ Representative TMEM Activity-MRI maps of mammary carcinoma tumors by magnetic resonance imaging (MRI) from PyMT (B) and HT17 (B′) mice treated with rebastinib (second column) or vehicle control (first column). Scale = 1 mm. c–c′ Quantification of TMEM-mediated vascular opening events (TMEM doorway activity), assessed via TMEM Activity-MRI assay, in PyMT (c) and HT17 (c′) mice. Mann–Whitney U-test. d–d′ Binarized images of extravascular dextran in mammary carcinoma tumors from PyMT (d) and HT17 (d′) mice treated with rebastinib (second column) or vehicle control (first column). Scale = 20 um. e-e′ Quantification of TAVO events (a.k.a. TMEM activity), assessed via the TMEM activity-dextran assay, in PyMT (e) and HT17 (e′) mice. Mann–Whitney U-test. f–f′ Correlation of TMEM doorway activity scores, as quantified with the TMEM activity-dextran and TMEM activity-MRI assays, in PyMT (f) and HT17 (f′) mice, treated with either rebastinib or vehicle control. Spearman’s rank correlation coefficient. g–g′ Circulating tumor cell (CTC) counts in PyMT (g) and HT17 (g′) mice treated with either rebastinib or vehicle control. Mann–Whitney U-test. h–h′ Correlation of TMEM activity-MRI score with circulating tumor cells (CTCs) in PyMT (h) and HT17 (h′) mice, treated with either rebastinib or vehicle control. Spearman’s rank correlation coefficient. i Multichannel immunofluorescence of disseminated tumor cells (DTCs) in MMTV-PyMT mice treated with either rebastinib (right panel) or vehicle control (left panel), as assessed by co-staining of the PyMT antigen, Pancytokeratin (PanCK) and DAPI. Magnified inserts show individual fluorescent channels for the cells outlined with squared boxes in the main images. Scale = 40 um. j Quantification of disseminated tumor cells (DTCs) in MMTV-PyMT mice, treated with either rebastinib or vehicle control. Mann– Whitney U-test. k Correlation of TMEM activity-MRI score with disseminated tumor cells (DTCs) in PyMT mice, treated with either rebastinib or vehicle control. Spearman’s rank correlation coefficient. Error bars: standard deviation (SD).