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Trypanocidal activity of the proteasome inhibitor and anti-cancer drug bortezomib.

Steverding D, Wang X - Parasit Vectors (2009)

Bottom Line: The concentrations of bortezomib required to reduce the growth rate by 50% and to kill all trypanosomes were 3.3 nM and 10 nM, respectively.However, proteasomal peptidase activities of trypanosomes exposed to bortezomib were only inhibited by 10% and 30% indicating that the proteasome is not the main target of the drug.The results suggest that bortezomib may be useful as drug for the treatment of human African trypanosomiasis.

View Article: PubMed Central - HTML - PubMed

Affiliation: BioMedical Research Centre, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich, NR4 7TJ, UK. dsteverding@hotmail.com.

ABSTRACT
The proteasome inhibitor and anti-cancer drug bortezomib was tested for in vitro activity against bloodstream forms of Trypanosoma brucei. The concentrations of bortezomib required to reduce the growth rate by 50% and to kill all trypanosomes were 3.3 nM and 10 nM, respectively. In addition, bortezomib was 10 times more toxic to trypanosomes than to human HL-60 cells. Moreover, exposure of trypanosomes to 10 nM bortezomib for 16 h was enough to kill 90% of the parasites following incubation in fresh medium. However, proteasomal peptidase activities of trypanosomes exposed to bortezomib were only inhibited by 10% and 30% indicating that the proteasome is not the main target of the drug. The results suggest that bortezomib may be useful as drug for the treatment of human African trypanosomiasis.

No MeSH data available.


Related in: MedlinePlus

Effect of pre-incubation with bortezomib on the growth of bloodstream forms of T. brucei. Trypanosomes (5 × 105/ml) were incubated in the presence (open circles) or absence (closed circles) of 10 nM bortezomib for 16 h. Thereafter, trypanosomes were diluted to a cell density of 104/ml in fresh medium and further incubated. At the indicated time points, trypanosomes were counted using a Neubauer haemocytometer. Geometric means ± SD of four experiments are shown. In control cultures, parasites died between 96 and 120 h of cultivation as has been shown previously [20]. In bortezomib-treated cultures, parasites died between 192 and 264 h of cultivation.
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Figure 3: Effect of pre-incubation with bortezomib on the growth of bloodstream forms of T. brucei. Trypanosomes (5 × 105/ml) were incubated in the presence (open circles) or absence (closed circles) of 10 nM bortezomib for 16 h. Thereafter, trypanosomes were diluted to a cell density of 104/ml in fresh medium and further incubated. At the indicated time points, trypanosomes were counted using a Neubauer haemocytometer. Geometric means ± SD of four experiments are shown. In control cultures, parasites died between 96 and 120 h of cultivation as has been shown previously [20]. In bortezomib-treated cultures, parasites died between 192 and 264 h of cultivation.

Mentions: For treatment of multiple myeloma, the recommended dose and treatment schedule of bortezomib is 1.3 mg/m2 administered as a 3 to 5 second bolus intravenous injection on days 1, 4, 8 and 11 of a three week cycle, for up to 8 cycles [18]. Pharmacokinetic/pharmacodynamic studies showed that on day 11 the mean plasma concentration of bortezomib falls from 422 nM to 10 nM within 16 h of administration of the drug [19]. As 10 nM is the MIC value of bortezomib, we wanted to investigate whether exposure of trypanosomes to 10 nM of the drug for 16 h is long enough to kill the parasites. To this end, 5 × 105 trypanosomes/ml were treated with or without 10 nM bortezomib for 16 h, then diluted to 104 cells/ml in fresh medium for further incubation and counted every 24 h using a Neubauer haemocytometer. For the first 48 h of re-incubation, the densities of cultures containing trypanosomes that had been exposed to bortezomib decreased continuously (Fig. 3). Thereafter, the numbers of trypanosomes started to increase but did not reach those of control cultures (Fig. 3). This result shows that treatment of trypanosomes with 10 nM bortezomib for 16 h leads in the killing of 90% of the parasites.


Trypanocidal activity of the proteasome inhibitor and anti-cancer drug bortezomib.

Steverding D, Wang X - Parasit Vectors (2009)

Effect of pre-incubation with bortezomib on the growth of bloodstream forms of T. brucei. Trypanosomes (5 × 105/ml) were incubated in the presence (open circles) or absence (closed circles) of 10 nM bortezomib for 16 h. Thereafter, trypanosomes were diluted to a cell density of 104/ml in fresh medium and further incubated. At the indicated time points, trypanosomes were counted using a Neubauer haemocytometer. Geometric means ± SD of four experiments are shown. In control cultures, parasites died between 96 and 120 h of cultivation as has been shown previously [20]. In bortezomib-treated cultures, parasites died between 192 and 264 h of cultivation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2714034&req=5

Figure 3: Effect of pre-incubation with bortezomib on the growth of bloodstream forms of T. brucei. Trypanosomes (5 × 105/ml) were incubated in the presence (open circles) or absence (closed circles) of 10 nM bortezomib for 16 h. Thereafter, trypanosomes were diluted to a cell density of 104/ml in fresh medium and further incubated. At the indicated time points, trypanosomes were counted using a Neubauer haemocytometer. Geometric means ± SD of four experiments are shown. In control cultures, parasites died between 96 and 120 h of cultivation as has been shown previously [20]. In bortezomib-treated cultures, parasites died between 192 and 264 h of cultivation.
Mentions: For treatment of multiple myeloma, the recommended dose and treatment schedule of bortezomib is 1.3 mg/m2 administered as a 3 to 5 second bolus intravenous injection on days 1, 4, 8 and 11 of a three week cycle, for up to 8 cycles [18]. Pharmacokinetic/pharmacodynamic studies showed that on day 11 the mean plasma concentration of bortezomib falls from 422 nM to 10 nM within 16 h of administration of the drug [19]. As 10 nM is the MIC value of bortezomib, we wanted to investigate whether exposure of trypanosomes to 10 nM of the drug for 16 h is long enough to kill the parasites. To this end, 5 × 105 trypanosomes/ml were treated with or without 10 nM bortezomib for 16 h, then diluted to 104 cells/ml in fresh medium for further incubation and counted every 24 h using a Neubauer haemocytometer. For the first 48 h of re-incubation, the densities of cultures containing trypanosomes that had been exposed to bortezomib decreased continuously (Fig. 3). Thereafter, the numbers of trypanosomes started to increase but did not reach those of control cultures (Fig. 3). This result shows that treatment of trypanosomes with 10 nM bortezomib for 16 h leads in the killing of 90% of the parasites.

Bottom Line: The concentrations of bortezomib required to reduce the growth rate by 50% and to kill all trypanosomes were 3.3 nM and 10 nM, respectively.However, proteasomal peptidase activities of trypanosomes exposed to bortezomib were only inhibited by 10% and 30% indicating that the proteasome is not the main target of the drug.The results suggest that bortezomib may be useful as drug for the treatment of human African trypanosomiasis.

View Article: PubMed Central - HTML - PubMed

Affiliation: BioMedical Research Centre, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich, NR4 7TJ, UK. dsteverding@hotmail.com.

ABSTRACT
The proteasome inhibitor and anti-cancer drug bortezomib was tested for in vitro activity against bloodstream forms of Trypanosoma brucei. The concentrations of bortezomib required to reduce the growth rate by 50% and to kill all trypanosomes were 3.3 nM and 10 nM, respectively. In addition, bortezomib was 10 times more toxic to trypanosomes than to human HL-60 cells. Moreover, exposure of trypanosomes to 10 nM bortezomib for 16 h was enough to kill 90% of the parasites following incubation in fresh medium. However, proteasomal peptidase activities of trypanosomes exposed to bortezomib were only inhibited by 10% and 30% indicating that the proteasome is not the main target of the drug. The results suggest that bortezomib may be useful as drug for the treatment of human African trypanosomiasis.

No MeSH data available.


Related in: MedlinePlus