Cancer cells hijack fibroblast cell bodies for invasion through 3D matrices in the matrigel dam assay.

A & B. Primary human fibroblasts were pre-labeled by DiI (red) and MDA-MB-231 (A) or BT549 cells (B) were pre-labeled by DiD (blue). Cells were cocultured for overnight before fixation for IF staining. Cadherin-11 protein was stained by the specific monoclonal primary antibody (clone 16A) followed by the secondary antibody staining (green). Purple arrows are pointing to the cadherin-11 AJs between cancer cells and fibroblasts. Confocal Z-stacks were scanned from the top of the cell to the bottom of the cell. All 2-D images shown were from 3-D Z-stacks maximum projections. C. The schematic to describe the cell invasion assay. D. Fibroblasts and MDA-MB-231 cells were pre-labeled as before. Fibroblasts alone (middle panels), MDA-MB-231 alone (right panels) or Fibroblasts and MDA-MB-231 (left panels) together in a 1:1 ratio were subjected to the cell invasion assay as described in (C). The whole cell population invasion displacements on the X-axis with a direction to the left were labeled between the yellow lines of 0 hr and 16 hr. The green fluorescence from the matrigel was omitted to clearly visualize the cells. Size bar, 100 μm. E, F & G. Cell invasion speed (Distance/time), invasion velocity (Displacement on the X-axis/time) and invasion persistence (Displacement/Distance) were quantitated. *, P < 0.05. H. Time-lapse zoom-in panels from Video 3. Green arrows are pointing at one cancer cell that was invading back-n-forth by attaching to and sliding on the cell bodies of fibroblasts. The red channel imaging offsets were elevated to visualize the long but thin invasive protrusions of fibroblasts. Size bar, 100 μm. I. Cropped and zoom-in panels from (H) to present the details of the invasive protrusions of fibroblasts (yellow arrow heads).

Cancer cells hijack fibroblast cell bodies for invasion through 3D matrices in the spheroid assay and the microfluidic assay.

A. The schematic explaining the invasion quantitation for the spheroid invasion assay. Invasion ratio was calculated by the area of the protrusion divided by the area of the core. B. Primary human fibroblasts were pre-labeled by DiI (red) and BT549 cells were pre-labeled by DiO (green). BT549 alone spheroid (top left), fibroblasts alone spheroid (top right), or BT549 and fibroblasts coculture (1:1) spheroid (bottom panels) were subjected to the 3D spheroid cell invasion assay. Total cell numbers maintained the same in every spheroid. Confocal Z-stacks were scanned from the top of the spheroid to the bottom. All 2-D images shown were from 3-D Z-stacks maximum projections. C. Quantitation for images as in (B). Experiments were repeated 6 times (n=6). *, P < 0.05. D. The schematic describing the microfluidic invasion assay. E. Time-lapse panels from Video 5. Primary human fibroblasts were pre-labeled by DiI (red) and MDA-MB-231 cells were pre-labeled by DiO (green).

The cancer cell hijacking fibroblast invasion is cadherin-11 dependent.

A. Primary human fibroblasts were pre-labeled by DiI (red) and BT549 cells were pre-labeled by DiO (green). BT549 alone spheroid with negative control siRNA or CDH11 siRNA (top panels), and fibroblasts alone spheroid with negative control siRNA or CDH11 siRNA (bottom panels) were subjected to the 3D spheroid cell invasion assay. B. Quantitation for images as in (A). Experiments were repeated 6 times (n=6). *, P < 0.05. C. BT549 and fibroblasts coculture (1:1) spheroid with negative control siRNA or CDH11 siRNA were subjected to the 3D spheroid cell invasion assay. D, E & F. Quantitation for images as in (C). Experiments were repeated 6 times (n=6). *, P < 0.05. Total cell numbers maintained the same in every spheroid. Confocal Z-stacks were scanned from the top of the spheroid to the bottom. All 2-D images shown were from 3-D Z-stacks maximum projections.

Cadherin-11 is specifically expressed in triple negative breast cancer cells (TNBCs) and its high expression is associated with poor clinical outcome in breast cancer patients.

A. CDH11 (Cadherin-11), ESR1(Estrogen Receptor 1), PGR (Progesterone Receptor) & ERBB2 (Receptor tyrosine-protein kinase erbB-2) expression data in breast cancer cell lines from CCLE (Cancer Cell Line Encyclopedia, The Broad Institute of MIT & Harvard) were plotted into a heat map. B. Kaplan-Meier analysis for breast cancer patients stratified by CDH11 expression for 1075 patients from The Human Protein Atlas database. C-E. Kaplan-Meier plots of overall survival (C, n=626), relapse-free survival (D, n=1764) and distant metastasis free survival (E, n=664) of breast cancer patients in relation to CDH11 expression according to The KM-plotter database. F. Kaplan-Meier plots of distant metastasis free survival (n=68) of ER negative breast cancer patients in relation to CDH11 expression according to The KM-plotter database.

Fibroblasts regulate tumor homing, growth and local invasion in triple negative breast cancer with fibroblast co-implantation xenograft mouse models.

1 × 106 of cancer cells with/without 1 × 106 of primary human fibroblast cells were implanted into the left fourth mammary fat pad of NOD/SCID (for MDA-MB-231, 5A-5E), or NOG (for PDX5993, 5F) mice. A. Comparison of bioluminescence intensity in NOD/SCID mice at 2 to 11 weeks after implantation between the MDA-MB-231-Luc cells only implantation group (MDA-luc only, blue) and the MDA-MB-231-Luc cells with primary human fibroblasts co-implantation group (MDA-luc w/Fibroblast, red). B. Representative in vivo bioluminescence images from (A) in the early stage (3 weeks, left panel) and the late stage (11 weeks, right panel) post implantation. C. Fibroblasts supported tumor formation at 11 weeks after implantation. Tumors with total bioluminescence above 1 × 108 photons/s were considered as successful growth. D. Fibroblasts stimulated tumor local invasion as quantified by the total area of the visualized bioluminescence from MDA-MB-231-luc cells in vivo with or without fibroblast co-implantation. E. Comparison of tumor volume in NOD/SCID mice at 2 to 11 weeks after implantation between the MDA-MB-231-Luc cells only implantation group and the MDA-MB-231-Luc cells with primary human fibroblasts co-implantation group. F. Comparison of tumor volume in NOG mice at 3 and 4 weeks after implantation of patient-derived triple negative breast cancer cell xenograft PDX5993 with or without primary human fibroblast co-implantation. Data were presented as mean ± SD. n=8 in (A-E). n=4 in (F). P values were determined by two-tailed Student’s t tests (NS, not significant; *, 0.01 < p < 0.05; **, p < 0.01).

Silencing of cadherin-11 in primary human fibroblasts suppresses tumor progression in the triple negative breast cancer with fibroblast co-implantation xenograft mouse model.

A. Primary human fibroblasts were transduced by GIPZ lentiviral CDH11 shRNA or non-silencing shRNA with a GFP reporter. Stable transductant cells were sorted out by FACS based on the GFP signal. Silencing of CDH11 in these cells was then quantified by RT-qPCR. B. Effect of CDH11 silencing in human fibroblasts on cancer cell growth in the cancer with fibroblast co-implantation xenograft mouse model. 1 × 106 of MDA-MB-231-luc cells mixed with 1 × 106 of stable non-silencing (blue) or CHD11 silencing (red) primary human fibroblasts were co-implanted into the left fourth mammary fat pad of NOD/SCID mice. The bioluminescence of the MDA-MB-231-Luc cells were measured every 2 weeks. C. Representative in vivo bioluminescence images from (B) at 14 weeks after cancer with fibroblast co-implantation. D. Comparison of tumor volume in mice co-implanted with MDA-MB-231-luc cells and non-silencing or CDH11 silencing primary human fibroblasts. Data were presented as mean ± SD (n=8). P values were determined by two-tailed Student’s t tests (NS, not significant; *, 0.01 < p < 0.05).

Overexpression of cadherin-11 in 4T1 mouse triple negative breast cancer cells to enhance their adhesions to mouse fibroblasts promotes tumor invasion, growth and distal metastasis.

A. CDH11 stable overexpression in 4T1 cells (4T1-CDH11) was quantified by RT-qPCR against CDH11 expression levels in 4T1 wildtype cells (4T1-WT). B. 4T1-WT cells or 4T1-CDH11 cells were pre-labeled by DiD (red). NIH3T3 mouse fibroblasts were pre-labeled by DiO (green). 4T1 alone spheroids (top panels), or 4T1 and NIH3T3 coculture (1:1) spheroids (bottom panels) were subjected to the 3D spheroid cell invasion assay as in Figure 2B. Total cell numbers maintained the same in every spheroid. Confocal Z-stacks were scanned from the top of the spheroid to the bottom. All 2-D images shown were from 3-D Z-stacks maximum projections. C. Quantitation for images as in (B). Experiments were repeated 5 times (n=5). NS, not significant; *, P < 0.05. D. Comparison of tumor volume in BALB/c mice implanted with 4T1-WT cells or 4T1-CDH11 cells. 1 × 106 of 4T1 cells were implanted into the left fourth mammary fat pad in BALB/c mice. Data were presented as mean ± SD (n=8). E. Comparison of 4T1-WT cell and 4T1-CDH11 cell proliferation in 2D culture in vitro. Same number of cells (46,000 cells) of each group were seeded in one well of a 6-well plate. Cell number was counted at 24 hrs, 48 hrs & 72 hrs (n=3 for each cell group at each time point) after cell seeding. NS, not significant. Note all cells were still not confluent at 72 hrs in each well of a 6-well plate. F. Kaplan-Meier survival curve of BALB/c mice implanted with either 4T1-WT cells or 4T1-CDH11 cells as in (D), n=8. G. micro-MRI imaging of tumor-bearing BALB/c mice from (D) on the 21st day after implantation of 4T1-WT cells or 4T1-CDH11 cells. Multiple distal metastatic sites in the dorsal neck region lymph nodes (denoted by small arrows) were detected in mice with 4T1-CDH11 tumors. Large arrowheads denote the original tumors at the left fourth mammary fat pad. micro-MRI image Z-stacks were scanned from the dorsal side to the ventral side of the mice. Single plane image section across the dorsal neck region lymph nodes from two representative mice from each group is shown. No distal metastasis was detected in any mice with 4T1-WT tumors in all micro-MRI image Z-stacks.

Strong immune rejection against tumor implants is detected in BALB/c mice implanted with 4T1-luc cells but is prevented by cadherin-11 overexpression in 4T1-luc cell implants.

1 × 106 of 4T1 mouse triple negative breast cancer cells expressing firefly luciferase with or without CDH11 overexpression were implanted into the left fourth mammary fat pad of immunocompetent BALB/c mice (A-C) or NOD/SCID mice (E-G). A. Comparison of whole tumor growth volume between the 4T1-WT-luc cells implantation group and the 4T1-CDH11-luc cells implantation group in BALB/c mice. B. Comparison of cancer growth (as detected by the firefly luciferase bioluminescence) between the 4T1-WT-luc cells implantation group and the 4T1-CDH11-luc cells implantation group at 4 weeks after implantation in BALB/c mice. Data were presented as mean ± SD (n=7). C. Representative in vivo bioluminescence images from (B). D. Comparison of 4T1-WT-luc cell and 4T1-CDH11-luc cell proliferation in 2D culture in vitro. Same number of cells (46,000 cells) of each group were seeded in one well of a 6-well plate. Cell number was counted at 24 hrs, 48 hrs & 72 hrs (n=3 for each cell group at each time point) after cell seeding. NS, not significant. Note all cells were still not confluent at 72 hrs in each well of a 6-well plate. E. Comparison of whole tumor growth volume between the 4T1-WT-luc cells implantation group and the 4T1-CDH11-luc cells implantation group in NOD/SCID mice. F. Comparison of cancer growth (as detected by the firefly luciferase bioluminescence) between the 4T1-WT-luc cells implantation group and the 4T1-CDH11-luc cells implantation group at 4 weeks after implantation in NOD/SCID mice. Data were presented as mean ± SD (n=5). G. Representative in vivo bioluminescence images from (F).