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Stimulation of Toll-like receptor-1/2 combined with Velcade increases cytotoxicity to human multiple myeloma cells.

Abdi J, Mutis T, Garssen J, Redegeld F - Blood Cancer J (2013)

Bottom Line: This effect was not related to a decreased adhesion of the cells to fibronectin, but TLR1/2 activation stimulated the caspase-3 activity in Velcade-treated myeloma cells, which may be responsible for the enhanced cell death.Inhibitors of NF-κB and MAPK reduced the stimulatory effect.These findings indicate that TLR activation of MM cells could bypass protective effects of cell adhesion and suggest that TLR signaling may also have antitumorigenic potential.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Science, Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.

ABSTRACT
An increasing body of evidence supports the important role of adhesion to bone marrow microenvironment components for survival and drug resistance of multiple myeloma (MM) cells. Previous studies suggested that stimulation of Toll-like receptors by endogenous ligands released during inflammation and tissue damage may be pro-tumorigenic, but no studies have been performed in relation to modulation of cell adhesion and drug cytotoxicity. Here, we investigated the effect of TLR1/2 activation on adhesion of human myeloma cells to fibronectin, and their sensitivity to the proteasome inhibitor Velcade. It was found that TLR1/2 activation with Pam3CSK4 increased the cytotoxicity of Velcade in L363, OPM-2 and U266 human myeloma cells. This effect was not related to a decreased adhesion of the cells to fibronectin, but TLR1/2 activation stimulated the caspase-3 activity in Velcade-treated myeloma cells, which may be responsible for the enhanced cell death. Inhibitors of NF-κB and MAPK reduced the stimulatory effect. These findings indicate that TLR activation of MM cells could bypass protective effects of cell adhesion and suggest that TLR signaling may also have antitumorigenic potential.

No MeSH data available.


Related in: MedlinePlus

Stimulation of TLR1/2 by Pam3CSK4 in combination with Velcade results in increased cell death of HMCLs. HMCLs were treated with Pam3CSK4 or solvent (control) for 24 h, exposed to different concentrations of Velcade for 1 h, washed and seeded in uncoated or FN-coated 96-well plates. Cells were incubated for 72 h, and at the last 4 h XTT containing PMS was added. IC50 for Velcade were determined from the concentration-cell death curves. L363: IC50 (control, non-adhered)=6.8 μℳ, IC50 (control, adhered)=13.3 μℳ; IC50 (+Pam3, non-adhered=1.0 μℳ), IC50 (+Pam3, adhered)=3.5 μℳ; OPM-2: IC50 (control, non-adhered)=2.75 μℳ, IC50 (control, adhered)=6.55 μℳ; IC50 (+Pam3, non-adhered=0.06 μℳ), IC50 (+Pam3, adhered)=0.288 μℳ; U266: IC50 (control, non-adhered)=2.35 μℳ, IC50 (control, adhered)=5.49 μℳ, IC50 (+Pam3, non-adhered=1.45 μℳ), IC50 (+Pam3, adhered)=0.88 μℳ. Data represent calculated mean±s.e.m. of two separate experiments with duplicate measurements in each.
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fig2: Stimulation of TLR1/2 by Pam3CSK4 in combination with Velcade results in increased cell death of HMCLs. HMCLs were treated with Pam3CSK4 or solvent (control) for 24 h, exposed to different concentrations of Velcade for 1 h, washed and seeded in uncoated or FN-coated 96-well plates. Cells were incubated for 72 h, and at the last 4 h XTT containing PMS was added. IC50 for Velcade were determined from the concentration-cell death curves. L363: IC50 (control, non-adhered)=6.8 μℳ, IC50 (control, adhered)=13.3 μℳ; IC50 (+Pam3, non-adhered=1.0 μℳ), IC50 (+Pam3, adhered)=3.5 μℳ; OPM-2: IC50 (control, non-adhered)=2.75 μℳ, IC50 (control, adhered)=6.55 μℳ; IC50 (+Pam3, non-adhered=0.06 μℳ), IC50 (+Pam3, adhered)=0.288 μℳ; U266: IC50 (control, non-adhered)=2.35 μℳ, IC50 (control, adhered)=5.49 μℳ, IC50 (+Pam3, non-adhered=1.45 μℳ), IC50 (+Pam3, adhered)=0.88 μℳ. Data represent calculated mean±s.e.m. of two separate experiments with duplicate measurements in each.

Mentions: To investigate the effect of TLR-1/2 activation on cell adhesion-mediated drug resistance, Pam3CSK4-stimulated HMCLs were incubated in uncoated vs FN-coated plates, and then exposed to different concentrations of Velcade. In line with previous studies,12, 13 the IC50 of Velcade was higher for cells adhered to FN compared to that for non-adhered cells, suggesting the induction of a cell adhesion-mediated drug resistance (Figure 2). Although TLR-1/2 activation by Pam3CSK4 induced some toxicity, combination of Pam3CSK4+Velcade increased the cell death in all cell lines, as illustrated by a lower IC50 for Velcade compared with control-treated conditions (Figure 2).


Stimulation of Toll-like receptor-1/2 combined with Velcade increases cytotoxicity to human multiple myeloma cells.

Abdi J, Mutis T, Garssen J, Redegeld F - Blood Cancer J (2013)

Stimulation of TLR1/2 by Pam3CSK4 in combination with Velcade results in increased cell death of HMCLs. HMCLs were treated with Pam3CSK4 or solvent (control) for 24 h, exposed to different concentrations of Velcade for 1 h, washed and seeded in uncoated or FN-coated 96-well plates. Cells were incubated for 72 h, and at the last 4 h XTT containing PMS was added. IC50 for Velcade were determined from the concentration-cell death curves. L363: IC50 (control, non-adhered)=6.8 μℳ, IC50 (control, adhered)=13.3 μℳ; IC50 (+Pam3, non-adhered=1.0 μℳ), IC50 (+Pam3, adhered)=3.5 μℳ; OPM-2: IC50 (control, non-adhered)=2.75 μℳ, IC50 (control, adhered)=6.55 μℳ; IC50 (+Pam3, non-adhered=0.06 μℳ), IC50 (+Pam3, adhered)=0.288 μℳ; U266: IC50 (control, non-adhered)=2.35 μℳ, IC50 (control, adhered)=5.49 μℳ, IC50 (+Pam3, non-adhered=1.45 μℳ), IC50 (+Pam3, adhered)=0.88 μℳ. Data represent calculated mean±s.e.m. of two separate experiments with duplicate measurements in each.
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fig2: Stimulation of TLR1/2 by Pam3CSK4 in combination with Velcade results in increased cell death of HMCLs. HMCLs were treated with Pam3CSK4 or solvent (control) for 24 h, exposed to different concentrations of Velcade for 1 h, washed and seeded in uncoated or FN-coated 96-well plates. Cells were incubated for 72 h, and at the last 4 h XTT containing PMS was added. IC50 for Velcade were determined from the concentration-cell death curves. L363: IC50 (control, non-adhered)=6.8 μℳ, IC50 (control, adhered)=13.3 μℳ; IC50 (+Pam3, non-adhered=1.0 μℳ), IC50 (+Pam3, adhered)=3.5 μℳ; OPM-2: IC50 (control, non-adhered)=2.75 μℳ, IC50 (control, adhered)=6.55 μℳ; IC50 (+Pam3, non-adhered=0.06 μℳ), IC50 (+Pam3, adhered)=0.288 μℳ; U266: IC50 (control, non-adhered)=2.35 μℳ, IC50 (control, adhered)=5.49 μℳ, IC50 (+Pam3, non-adhered=1.45 μℳ), IC50 (+Pam3, adhered)=0.88 μℳ. Data represent calculated mean±s.e.m. of two separate experiments with duplicate measurements in each.
Mentions: To investigate the effect of TLR-1/2 activation on cell adhesion-mediated drug resistance, Pam3CSK4-stimulated HMCLs were incubated in uncoated vs FN-coated plates, and then exposed to different concentrations of Velcade. In line with previous studies,12, 13 the IC50 of Velcade was higher for cells adhered to FN compared to that for non-adhered cells, suggesting the induction of a cell adhesion-mediated drug resistance (Figure 2). Although TLR-1/2 activation by Pam3CSK4 induced some toxicity, combination of Pam3CSK4+Velcade increased the cell death in all cell lines, as illustrated by a lower IC50 for Velcade compared with control-treated conditions (Figure 2).

Bottom Line: This effect was not related to a decreased adhesion of the cells to fibronectin, but TLR1/2 activation stimulated the caspase-3 activity in Velcade-treated myeloma cells, which may be responsible for the enhanced cell death.Inhibitors of NF-κB and MAPK reduced the stimulatory effect.These findings indicate that TLR activation of MM cells could bypass protective effects of cell adhesion and suggest that TLR signaling may also have antitumorigenic potential.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Science, Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.

ABSTRACT
An increasing body of evidence supports the important role of adhesion to bone marrow microenvironment components for survival and drug resistance of multiple myeloma (MM) cells. Previous studies suggested that stimulation of Toll-like receptors by endogenous ligands released during inflammation and tissue damage may be pro-tumorigenic, but no studies have been performed in relation to modulation of cell adhesion and drug cytotoxicity. Here, we investigated the effect of TLR1/2 activation on adhesion of human myeloma cells to fibronectin, and their sensitivity to the proteasome inhibitor Velcade. It was found that TLR1/2 activation with Pam3CSK4 increased the cytotoxicity of Velcade in L363, OPM-2 and U266 human myeloma cells. This effect was not related to a decreased adhesion of the cells to fibronectin, but TLR1/2 activation stimulated the caspase-3 activity in Velcade-treated myeloma cells, which may be responsible for the enhanced cell death. Inhibitors of NF-κB and MAPK reduced the stimulatory effect. These findings indicate that TLR activation of MM cells could bypass protective effects of cell adhesion and suggest that TLR signaling may also have antitumorigenic potential.

No MeSH data available.


Related in: MedlinePlus