Syndecan-1 deficiency promotes tumor growth in a murine model of colitis-induced colon carcinoma

<div><p>Syndecan-1 (Sdc1) is an important member of the cell surface heparan sulfate proteoglycan family, highly expressed by epithelial cells in adult organisms. Sdc1 is involved in the regulation of cell migration, cell-cell and cell-matrix interactions, growth-factor, chemokine and integrin activity, and implicated in inflammatory responses and tumorigenesis. Gastrointestinal tract represents an important anatomic site where loss of Sdc1 expression was reported both in inflammation and malignancy. However, the biological significance of Sdc1 in chronic colitis-associated tumorigenesis has not been elucidated. To the best of our knowledge, this study is the first to test the effects of Sdc1 loss on colorectal tumor development in inflammation-driven colon tumorigenesis. Utilizing a mouse model of colitis-related colon carcinoma induced by the carcinogen azoxymethane (AOM), followed by the inflammatory agent dextran sodium sulfate (DSS), we found that Sdc1 deficiency results in increased susceptibility to colitis-associated tumorigenesis. Importantly, colitis-associated tumors developed in Sdc1-defficient mice were characterized by increased local production of IL-6, activation of STAT3, as well as induction of several STAT3 target genes that act as important effectors of colonic tumorigenesis. Altogether, our results highlight a previously unknown effect of Sdc1 loss in progression of inflammation-associated cancer and suggest that decreased levels of Sdc1 may serve as an indicator of colon carcinoma progression in the setting of chronic inflammation.</p></div

Calcium flux experiments.

<p>Calcium flux experiments using the dye Fluo-4 in combination with structured illumination fluorescence microscopy: Representative microscopy images of the cells before and after the stimulation with the different treatments. From each experiment images with the maximum fluorescence signal after stimulation are shown. (a) Panel with the controls. (b) Panel with the nanoformulations. (c) Fluorescence intensity over time after stimulation with the different treatments (Scale bar = 200 μM). NC: nanocapsules (images in (a) and (b) have been contrast enhanced for better visualization in the print version).</p

Migration patterns of MDCK-C7 cells.

<p>Migration patterns of MDCK-C7 cells after treatment with nanocapsules and free capsaicin: (a) Representative migration tracks. End times of the tracking experiment are given below the headlines as the cells moved out of the observed field of view at different time points due to different migration speeds. (b) Migration speed as an end point measurement. (c) Directness as an end point measurement. (d) Accumulated distance over time for all the treatments. (e) Euclidean distance over time for all the treatments. Mean values ± SD. Statistical test: Kruskal-Wallis test (n = 3; 10 cells per measurement), * p < 0.05, *** p < 0.001, **** p < 0.0001). NC: nanocapsules.</p

Analysis of global morphology changes in confluent cell layers.

<p>Analysis of global morphology changes in confluent cell layers by histogram-based evaluation of quantitative DHM phase contrast images at different time points (red: t₁, purple: t₂, blue: t_3; t₁ < t₂ < t₃). An increase of the cell layer surface roughness Δ<i>d</i> (a) causes a shift of the histogram (b) and the average phase contrast (vertical lines in (b)) towards higher phase values.</p

Analysis of cell morphology by digital holographic microscopy.

<p>Analysis of cell morphology by evaluation of quantitative phase images retrieved with digital holographic microscopy: (a) Histograms of quantitative DHM phase contrast images at different time points for control cells and cells treated with capsaicin and the different nanoformulations. (b) Average phase contrast for all treatments plotted over time with a linear fit. (c) Slopes and Y-intercepts retrieved by the linear fits from (b). Mean values ± SD (<i>n = 3</i>).</p

Fluorescence microscopy.

<p>Representative images of MDCK cells with actin or ZO-1 staining. (Nuclei: blue, ZO-1: green, Actin: red, NC: nanocapsules) (images have been contrast enhanced for better visualization in the print version)”.</p