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Nanoparticulate Quillaja saponin induces apoptosis in human leukemia cell lines with a high therapeutic index.

Hu K, Berenjian S, Larsson R, Gullbo J, Nygren P, Lövgren T, Morein B - Int J Nanomedicine (2010)

Bottom Line: The toxic effect was abolished by converting QS fractions into stable nanoparticles through the binding of QS to cholesterol.The nontoxic BBE blocked the cell killing effect of KGI in a concentration-dependent manner.In conclusion, the formulation of QS into nanoparticles has the potential of becoming a new class of anticancer agents.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Sciences, Section of Virology, Uppsala University, Uppsala, Sweden.

ABSTRACT
Saponin fractions of Quillaja saponaria Molina (QS) have cytotoxic activity against cancer cells in vitro, but are too toxic to be useful in the clinic. The toxic effect was abolished by converting QS fractions into stable nanoparticles through the binding of QS to cholesterol. Two fractions of QS were selected for particle formation, one with an acyl-chain (ASAP) was used to form killing and growth-inhibiting (KGI) particles, and the other without the acyl-chain (DSAP) was used to formulate blocking and balancing effect (BBE) particles. KGI showed significant growth inhibiting and cancer cell-killing activities in nine of 10 cell lines while BBE showed that on one cell line. The monoblastoid lymphoma cell line U937 was selected for analyzing the mode of action. Low concentrations of KGI (0.5 and 2 microg/mL) induced irreversible exit from the cell cycle, differentiation measured by cytokine production, and eventually programmed cell death (apoptosis). Compared to normal human monocytes, the U937 cells were 30-fold more sensitive to KGI. The nontoxic BBE blocked the cell killing effect of KGI in a concentration-dependent manner. In conclusion, the formulation of QS into nanoparticles has the potential of becoming a new class of anticancer agents.

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Related in: MedlinePlus

ASAP in free form and formulated into KGI inhibit thymidine kinase (TK) activity. The decreased level of TK caused by KGI correlates with reduced cell growth. Both KGI and BBE can induce cytokine production but only KGI kills the cells. A) Very low or no intracellular levels of TK activity was recorded in U937 cancer cells treated with 25 and 50 μg/mL of free ASAP and KGI respectively. B) The intracellular levels of TK decreased close to 50% compared to control cells after exposure of cells synchronized in the cell cycle to KGI particles for 24 hrs. C) The number of viable cells synchronized in the cell cycle was reduced to ¼ of that of control cells after exposure to KGI for 24 hrs. D) KGI stimulates U937 cancer cells to produce IL-8 with a sharp increase at the concentrations of 0.5 to 1 μg/mL close to the IC50 of KGI while BBE stimulates production of IL-8 without killing the cells.
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f5-ijn-5-051: ASAP in free form and formulated into KGI inhibit thymidine kinase (TK) activity. The decreased level of TK caused by KGI correlates with reduced cell growth. Both KGI and BBE can induce cytokine production but only KGI kills the cells. A) Very low or no intracellular levels of TK activity was recorded in U937 cancer cells treated with 25 and 50 μg/mL of free ASAP and KGI respectively. B) The intracellular levels of TK decreased close to 50% compared to control cells after exposure of cells synchronized in the cell cycle to KGI particles for 24 hrs. C) The number of viable cells synchronized in the cell cycle was reduced to ¼ of that of control cells after exposure to KGI for 24 hrs. D) KGI stimulates U937 cancer cells to produce IL-8 with a sharp increase at the concentrations of 0.5 to 1 μg/mL close to the IC50 of KGI while BBE stimulates production of IL-8 without killing the cells.

Mentions: The effect of KGI on the cell cycle in U937 cells was analyzed by assessment of the TK-activity over time. The TK activity was correlated with the inhibition of cell-metabolism (recorded by the Alamar Blue assay), induction of cell death (measured by Trypan Blue exclusion staining) and also with apoptosis (detected by annexin V staining). In nonsynchronized cells, KGI at 2 μg/mL caused a marked reduction of TK activity after exposure of the tumor cells for 48–72 hours (Figure 5a). Reduction of the TK activity after exposure to 25 or 50 μg/mL of KGI was already evident at 24 hours. Figure 5b demonstrates that tumor cells synchronized in the cell cycle exposed to 2 μg/mL of KGI for 24 hours had reduced intracellular levels of TK compared to control cells coinciding with reduced number of viable cells (Figure 5c) indicating that the KGI-treated cells did not enter a second cycle. Corroborating these results, cell cycle analysis with flow cytometry of KGI-exposed DNA-stained cells demonstrated accumulation of cells in G1 phase in parallel with depletion of cells in S-phase (Table 1).


Nanoparticulate Quillaja saponin induces apoptosis in human leukemia cell lines with a high therapeutic index.

Hu K, Berenjian S, Larsson R, Gullbo J, Nygren P, Lövgren T, Morein B - Int J Nanomedicine (2010)

ASAP in free form and formulated into KGI inhibit thymidine kinase (TK) activity. The decreased level of TK caused by KGI correlates with reduced cell growth. Both KGI and BBE can induce cytokine production but only KGI kills the cells. A) Very low or no intracellular levels of TK activity was recorded in U937 cancer cells treated with 25 and 50 μg/mL of free ASAP and KGI respectively. B) The intracellular levels of TK decreased close to 50% compared to control cells after exposure of cells synchronized in the cell cycle to KGI particles for 24 hrs. C) The number of viable cells synchronized in the cell cycle was reduced to ¼ of that of control cells after exposure to KGI for 24 hrs. D) KGI stimulates U937 cancer cells to produce IL-8 with a sharp increase at the concentrations of 0.5 to 1 μg/mL close to the IC50 of KGI while BBE stimulates production of IL-8 without killing the cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2819906&req=5

f5-ijn-5-051: ASAP in free form and formulated into KGI inhibit thymidine kinase (TK) activity. The decreased level of TK caused by KGI correlates with reduced cell growth. Both KGI and BBE can induce cytokine production but only KGI kills the cells. A) Very low or no intracellular levels of TK activity was recorded in U937 cancer cells treated with 25 and 50 μg/mL of free ASAP and KGI respectively. B) The intracellular levels of TK decreased close to 50% compared to control cells after exposure of cells synchronized in the cell cycle to KGI particles for 24 hrs. C) The number of viable cells synchronized in the cell cycle was reduced to ¼ of that of control cells after exposure to KGI for 24 hrs. D) KGI stimulates U937 cancer cells to produce IL-8 with a sharp increase at the concentrations of 0.5 to 1 μg/mL close to the IC50 of KGI while BBE stimulates production of IL-8 without killing the cells.
Mentions: The effect of KGI on the cell cycle in U937 cells was analyzed by assessment of the TK-activity over time. The TK activity was correlated with the inhibition of cell-metabolism (recorded by the Alamar Blue assay), induction of cell death (measured by Trypan Blue exclusion staining) and also with apoptosis (detected by annexin V staining). In nonsynchronized cells, KGI at 2 μg/mL caused a marked reduction of TK activity after exposure of the tumor cells for 48–72 hours (Figure 5a). Reduction of the TK activity after exposure to 25 or 50 μg/mL of KGI was already evident at 24 hours. Figure 5b demonstrates that tumor cells synchronized in the cell cycle exposed to 2 μg/mL of KGI for 24 hours had reduced intracellular levels of TK compared to control cells coinciding with reduced number of viable cells (Figure 5c) indicating that the KGI-treated cells did not enter a second cycle. Corroborating these results, cell cycle analysis with flow cytometry of KGI-exposed DNA-stained cells demonstrated accumulation of cells in G1 phase in parallel with depletion of cells in S-phase (Table 1).

Bottom Line: The toxic effect was abolished by converting QS fractions into stable nanoparticles through the binding of QS to cholesterol.The nontoxic BBE blocked the cell killing effect of KGI in a concentration-dependent manner.In conclusion, the formulation of QS into nanoparticles has the potential of becoming a new class of anticancer agents.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Sciences, Section of Virology, Uppsala University, Uppsala, Sweden.

ABSTRACT
Saponin fractions of Quillaja saponaria Molina (QS) have cytotoxic activity against cancer cells in vitro, but are too toxic to be useful in the clinic. The toxic effect was abolished by converting QS fractions into stable nanoparticles through the binding of QS to cholesterol. Two fractions of QS were selected for particle formation, one with an acyl-chain (ASAP) was used to form killing and growth-inhibiting (KGI) particles, and the other without the acyl-chain (DSAP) was used to formulate blocking and balancing effect (BBE) particles. KGI showed significant growth inhibiting and cancer cell-killing activities in nine of 10 cell lines while BBE showed that on one cell line. The monoblastoid lymphoma cell line U937 was selected for analyzing the mode of action. Low concentrations of KGI (0.5 and 2 microg/mL) induced irreversible exit from the cell cycle, differentiation measured by cytokine production, and eventually programmed cell death (apoptosis). Compared to normal human monocytes, the U937 cells were 30-fold more sensitive to KGI. The nontoxic BBE blocked the cell killing effect of KGI in a concentration-dependent manner. In conclusion, the formulation of QS into nanoparticles has the potential of becoming a new class of anticancer agents.

Show MeSH
Related in: MedlinePlus