Inactivation of uPA and its receptor uPAR by 3,3′-diindolylmethane (DIM) leads to the inhibition of prostate cancer cell growth and migration.
Ahmad A, Kong D, Sarkar SH, Wang Z, Banerjee S, Sarkar FH.
Department of Pathology, Barbara Ann Karmanos Cancer Center, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

3,3′-Diindolylmethane (DIM) has been studied for its putative anti-cancer properties, especially against prostate cancer; however, its exact mechanism of action remains unclear. We recently provided preliminary data suggesting down-regulation of uPA during DIM (a clinically active DIM)-induced inhibition of invasion and angiogenesis in prostate cancer cells. Since the expression and activation of uPA plays an important role in tumorigenicity, and high endogenous levels of uPA and uPAR are found in advanced metastatic cancers, we investigated their role in DIM-mediated inhibition of prostate cancer cell growth and motility. Using PC3 cells, we found that DIM treatment as well as the silencing of uPA and uPAR by siRNAs led to the inhibition of cell growth and motility. Conversely, over-expression of uPA/uPAR in LNCaP and C4-2B cells resulted in increased cell growth and motility, which was effectively inhibited by DIM. Moreover, we found that uPA as well as uPAR induced the production of VEGF and MMP-9, and that the down-regulation of uPA/uPAR by siRNAs or DIM treatment resulted in the inhibition of VEGF and MMP-9 secretion, which could be responsible for the observed inhibition of cell migration. Interestingly, silencing of uPA/uPAR led to decreased sensitivity to DIM, indicating the important role of uPA/uPAR in DIM-mediated regulation of prostate cancer cell growth and migration. Our data suggest that chemopreventive and/or therapeutic activity of DIM is in part due to down-regulation of uPA-uPAR leading to reduced production of VEGF/MMP-9, which ultimately leads to the inhibition of cell growth and migration of aggressive prostate cancer cells.