Research Paper Volume 8, Issue 8 pp 1650—1669

Figure 9. A model depicting SDC1 upregulation in human breast stromal fibroblasts as a consequence of ionizing irradiation-mediated premature senescence and the paracrine action of invasive breast cancer cells. (A) Ionizing radiation of young (early passage) human breast stromal fibroblasts leads to premature senescence. In senescent cells, an autocrine TGF-β loop is formed leading to SDC1 overexpression via the Smad pathway. (B) The highly invasive breast cancer cell line MDA-MB-231 enhances SDC1 expression in young breast fibroblasts in a paracrine manner via the action of TGF-β. Interestingly, it further potentiates SDC1 expression in senescent cells. This indicates a synergistic effect of ionizing radiation with invasive cancer cells leading to the overexpression of SDC1, the latter known to be a poor prognostic factor in breast cancer development.