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3,3'-Diindolylmethane (DIM) and its ring-substituted halogenated analogs (ring-DIMs) induce differential mechanisms of survival and death in androgen-dependent and -independent prostate cancer cells.

Goldberg AA, Draz H, Montes-Grajales D, Olivero-Verbél J, Safe SH, Sanderson JT - Genes Cancer (2015)

Bottom Line: Cyclosporin A, an inhibitor of the mitochondrial permeability transition pore, inhibited ring-DIM-mediated cell death, and salubrinal, an inhibitor of ER stress, inhibited cell death mediated only by 4,4'-dihaloDIMs. We found that although salubrinal did not inhibit the onset of ER stress, it prevented 4,4'-dibromoDIM mediated loss of MMP.Salubrinal potentiated cell death in response to 7,7'-dihaloDIMs and DIM, and this effect concurred with increased loss of MMP.Inhibition of autophagy with bafilomycin A1, 3-methyladenine or by LC3B gene silencing sensitized LNCaP and C42B, but not ATG5-deficient DU145 cells to ring-DIM- and DIM-mediated cell death.

View Article: PubMed Central - PubMed

Affiliation: INRS-Institut Armand-Frappier, Laval, Québec, Canada ; Critical Care Division and Meakins-Christie Laboratories, Faculty of Medicine, McGill University, Montreal, Quebec H3A 1A1, Canada.

ABSTRACT
We recently reported that novel ring-substituted analogs of 3,3'-diindolylmethane (ring-DIMs) induce apoptosis and necrosis in androgen-dependent and -independent prostate cancer cells. In this paper, we have focused on the mechanism(s) associated with ring-DIM-mediated cell death, and on identifying the specific intracellular target(s) of these compounds. The 4,4'- and 7,7'-dichloroDIMs and 4,4'- and 7,7'-dibromoDIMs induced the death of LNCaP, C42B and DU145 prostate cancer cells, but not that of immortalized normal human prostate epithelial (RWPE-1) cells. Ring-DIMs caused the early loss of mitochondrial membrane potential (MMP) and decreased mitochondrial ATP generation in prostate cancer cells. Cyclosporin A, an inhibitor of the mitochondrial permeability transition pore, inhibited ring-DIM-mediated cell death, and salubrinal, an inhibitor of ER stress, inhibited cell death mediated only by 4,4'-dihaloDIMs. We found that although salubrinal did not inhibit the onset of ER stress, it prevented 4,4'-dibromoDIM mediated loss of MMP. Salubrinal potentiated cell death in response to 7,7'-dihaloDIMs and DIM, and this effect concurred with increased loss of MMP. Using in silico 3-D docking affinity analysis, we identified Ca2+/calmodulin-dependent kinase II (CaMKII) as a potential direct target for the most toxic ring-DIM, 4,4'-dibromoDIM. An inhibitor of CaMKII, KN93, but not its inactive analog KN92, abrogated cell death mediated by 4,4'-dibromoDIM. The ring-DIMs induced ER stress and autophagy, but these processes were not necessary for ring-DIM-mediated cell death. Inhibition of autophagy with bafilomycin A1, 3-methyladenine or by LC3B gene silencing sensitized LNCaP and C42B, but not ATG5-deficient DU145 cells to ring-DIM- and DIM-mediated cell death. We propose that autophagy induced by the ring-DIMs and DIM has a cytoprotective function in prostate cancer cells.

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Related in: MedlinePlus

Ring-DIMs kill LNCaP and C42B prostate cancer cells, but not RPWE-1 immortalized normal prostate epithelial cellsThe percentage of intact LNCaP (A) and C42B (B) cells that do not have fragmented nuclei, condensed chromatin or propidium iodide staining was determined after a 24 hour exposure to increasing concentrations of 4,4′-Br2DIM, 7,7′-Br2DIM, 4,4′-Cl2DIM, 7,7′-Cl2DIM or DIM. (C) Percentage of intact RWPE-1 cells after a 48 hour exposure to the ring-DIMs or DIM.
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Figure 1: Ring-DIMs kill LNCaP and C42B prostate cancer cells, but not RPWE-1 immortalized normal prostate epithelial cellsThe percentage of intact LNCaP (A) and C42B (B) cells that do not have fragmented nuclei, condensed chromatin or propidium iodide staining was determined after a 24 hour exposure to increasing concentrations of 4,4′-Br2DIM, 7,7′-Br2DIM, 4,4′-Cl2DIM, 7,7′-Cl2DIM or DIM. (C) Percentage of intact RWPE-1 cells after a 48 hour exposure to the ring-DIMs or DIM.

Mentions: We tested the ability of the ring-DIMs to kill prostate cancer cells that express a DHT-responsive AR (LNCaP), a constitutively active AR (C42B) and cells lacking AR (DU145). In LNCaP and C42B cells, 4,4′-Br2DIM (IC50 = 13.1 μM, 16.7 μM, respectively), 4,4′-Cl2DIM (IC50 = 20.2 μM, 29.3), 7,7′-Br2DIM (IC50 = 19.5 μM, 25.3 μM) and 7,7′-Cl2DIM (IC50 = 15.8 μM, 25.7 μM) were all significantly more potent at killing cells than DIM (IC50 = 23.3, 46.1 μM), (Fig. 1A, B). The most cytotoxic ring-DIM, 4,4′-Br2DIM, killed AR-negative DU145 cells with the same potency as C42B cells with an IC50 of 20 μM (Supplementary Fig. S1A). At concentrations that were toxic to the prostate cancer cells neither the ring-DIMs nor DIM induced cell death in RWPE-1 cells (Fig. 1C).


3,3'-Diindolylmethane (DIM) and its ring-substituted halogenated analogs (ring-DIMs) induce differential mechanisms of survival and death in androgen-dependent and -independent prostate cancer cells.

Goldberg AA, Draz H, Montes-Grajales D, Olivero-Verbél J, Safe SH, Sanderson JT - Genes Cancer (2015)

Ring-DIMs kill LNCaP and C42B prostate cancer cells, but not RPWE-1 immortalized normal prostate epithelial cellsThe percentage of intact LNCaP (A) and C42B (B) cells that do not have fragmented nuclei, condensed chromatin or propidium iodide staining was determined after a 24 hour exposure to increasing concentrations of 4,4′-Br2DIM, 7,7′-Br2DIM, 4,4′-Cl2DIM, 7,7′-Cl2DIM or DIM. (C) Percentage of intact RWPE-1 cells after a 48 hour exposure to the ring-DIMs or DIM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482247&req=5

Figure 1: Ring-DIMs kill LNCaP and C42B prostate cancer cells, but not RPWE-1 immortalized normal prostate epithelial cellsThe percentage of intact LNCaP (A) and C42B (B) cells that do not have fragmented nuclei, condensed chromatin or propidium iodide staining was determined after a 24 hour exposure to increasing concentrations of 4,4′-Br2DIM, 7,7′-Br2DIM, 4,4′-Cl2DIM, 7,7′-Cl2DIM or DIM. (C) Percentage of intact RWPE-1 cells after a 48 hour exposure to the ring-DIMs or DIM.
Mentions: We tested the ability of the ring-DIMs to kill prostate cancer cells that express a DHT-responsive AR (LNCaP), a constitutively active AR (C42B) and cells lacking AR (DU145). In LNCaP and C42B cells, 4,4′-Br2DIM (IC50 = 13.1 μM, 16.7 μM, respectively), 4,4′-Cl2DIM (IC50 = 20.2 μM, 29.3), 7,7′-Br2DIM (IC50 = 19.5 μM, 25.3 μM) and 7,7′-Cl2DIM (IC50 = 15.8 μM, 25.7 μM) were all significantly more potent at killing cells than DIM (IC50 = 23.3, 46.1 μM), (Fig. 1A, B). The most cytotoxic ring-DIM, 4,4′-Br2DIM, killed AR-negative DU145 cells with the same potency as C42B cells with an IC50 of 20 μM (Supplementary Fig. S1A). At concentrations that were toxic to the prostate cancer cells neither the ring-DIMs nor DIM induced cell death in RWPE-1 cells (Fig. 1C).

Bottom Line: Cyclosporin A, an inhibitor of the mitochondrial permeability transition pore, inhibited ring-DIM-mediated cell death, and salubrinal, an inhibitor of ER stress, inhibited cell death mediated only by 4,4'-dihaloDIMs. We found that although salubrinal did not inhibit the onset of ER stress, it prevented 4,4'-dibromoDIM mediated loss of MMP.Salubrinal potentiated cell death in response to 7,7'-dihaloDIMs and DIM, and this effect concurred with increased loss of MMP.Inhibition of autophagy with bafilomycin A1, 3-methyladenine or by LC3B gene silencing sensitized LNCaP and C42B, but not ATG5-deficient DU145 cells to ring-DIM- and DIM-mediated cell death.

View Article: PubMed Central - PubMed

Affiliation: INRS-Institut Armand-Frappier, Laval, Québec, Canada ; Critical Care Division and Meakins-Christie Laboratories, Faculty of Medicine, McGill University, Montreal, Quebec H3A 1A1, Canada.

ABSTRACT
We recently reported that novel ring-substituted analogs of 3,3'-diindolylmethane (ring-DIMs) induce apoptosis and necrosis in androgen-dependent and -independent prostate cancer cells. In this paper, we have focused on the mechanism(s) associated with ring-DIM-mediated cell death, and on identifying the specific intracellular target(s) of these compounds. The 4,4'- and 7,7'-dichloroDIMs and 4,4'- and 7,7'-dibromoDIMs induced the death of LNCaP, C42B and DU145 prostate cancer cells, but not that of immortalized normal human prostate epithelial (RWPE-1) cells. Ring-DIMs caused the early loss of mitochondrial membrane potential (MMP) and decreased mitochondrial ATP generation in prostate cancer cells. Cyclosporin A, an inhibitor of the mitochondrial permeability transition pore, inhibited ring-DIM-mediated cell death, and salubrinal, an inhibitor of ER stress, inhibited cell death mediated only by 4,4'-dihaloDIMs. We found that although salubrinal did not inhibit the onset of ER stress, it prevented 4,4'-dibromoDIM mediated loss of MMP. Salubrinal potentiated cell death in response to 7,7'-dihaloDIMs and DIM, and this effect concurred with increased loss of MMP. Using in silico 3-D docking affinity analysis, we identified Ca2+/calmodulin-dependent kinase II (CaMKII) as a potential direct target for the most toxic ring-DIM, 4,4'-dibromoDIM. An inhibitor of CaMKII, KN93, but not its inactive analog KN92, abrogated cell death mediated by 4,4'-dibromoDIM. The ring-DIMs induced ER stress and autophagy, but these processes were not necessary for ring-DIM-mediated cell death. Inhibition of autophagy with bafilomycin A1, 3-methyladenine or by LC3B gene silencing sensitized LNCaP and C42B, but not ATG5-deficient DU145 cells to ring-DIM- and DIM-mediated cell death. We propose that autophagy induced by the ring-DIMs and DIM has a cytoprotective function in prostate cancer cells.

No MeSH data available.


Related in: MedlinePlus