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In Vitro Apoptotic Effects of Farnesyltransferase blockade in Acute Myeloid Leukemia Cells

View Article: PubMed Central - PubMed

ABSTRACT

Farnesyltransferase inhibitors (FTIs) are a class of oral anti-cancer drugs currently tested in phase I-II clinical trials for treatment of hematological malignancies. The in vitro effects of various FTIs (alpha-hydroxyfarnesylphosphonic acid, manumycin-A and SCH66336) were tested on CD34+ KG1a cell line and in primary acute myeloid leukemia (AML) cells from 64 patients. By cell viability and clonogeneic methylcellulose assays, FTIs showed a significant inhibitory activity in CD34+ KG1a and primary bone marrow (BM) leukemic cells from 56% of AML patients. FTIs also induced activation of caspase-3 and Fas-independent apoptosis, confirmed by the finding that inhibition of caspase-8 was not associated with the rescue of FTI-treated cells. We concluded that other cellular events induced by FTIs may trigger activation of caspase-3 and subsequent apoptosis, but the expression of proapoptotic molecules, as Bcl-2 and Bcl-XL, and antiapoptotic, as Bcl-X(s), were not modified by FTIs. By contrast, expression of inducible nitric oxide synthase (iNOS) was increased in FTI-treated AML cells. Our results suggest a very complex mechanism of action of FTIs that require more studies for a better clinical use of the drugs alone or in combination in the treatment of hematological malignancies.

No MeSH data available.


Related in: MedlinePlus

FTI-induced inhibition of AML cell proliferation is partly related to apoptosis.Agarose gel stained with ethidium bromide after electrophoresis of low molecular weight DNA from 12 representative BM AML patients exposed for 48 h to FTIs at the IC50 (A). A representative flow cytometric detection of apoptic hypodiploid DNA peak stained with PI from BM AML patient exposed to SCH (B). Percentages of viable cells and apoptotic cells simultaneously measured from 10 representative BM AML patients after exposure for 48 h to FTIs (C). Cumulative percentage of mean inhibition of cell viability and apoptotic cells, as well as statistical analysis, are reported in the corresponding results section. Abbreviations, see text.
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f2-tm-15-22: FTI-induced inhibition of AML cell proliferation is partly related to apoptosis.Agarose gel stained with ethidium bromide after electrophoresis of low molecular weight DNA from 12 representative BM AML patients exposed for 48 h to FTIs at the IC50 (A). A representative flow cytometric detection of apoptic hypodiploid DNA peak stained with PI from BM AML patient exposed to SCH (B). Percentages of viable cells and apoptotic cells simultaneously measured from 10 representative BM AML patients after exposure for 48 h to FTIs (C). Cumulative percentage of mean inhibition of cell viability and apoptotic cells, as well as statistical analysis, are reported in the corresponding results section. Abbreviations, see text.

Mentions: To define whether the FTI-mediated growth inhibition of primary AML cells was associated to apoptosis, BM AML cells sensitive to FTI inhibition were exposed for 48 h to FTIs at IC50. By LMW DNA fragmentation analysis, AML cells showed the characteristic DNA ladder suggestive of apoptosis (Fig. 2A). Flow cytometric detection of apoptotic hypodiploid DNA peak derived from treated BM AML cells confirmed the FTI-enhanced apoptotic cytotoxic effect (Fig. 2B). Indeed, percentages of apoptotic AML cells were significantly lower than those with cytolysis measured by cell viability assay (mean % ± SEM of cytolysis, 55.7±10; p=0.03). The parallel measurement of the number of apoptotic AML cells and viable cells from 10 AML patients carried by flow cytometry and cell viability assays showed that the percentages of apoptotic AML cells were significantly lower than those undergoing cytolysis (mean % ± SEM of apoptotic and viable AML cells, 32 ± 7 vs 51 ± 11, respectively; p = 0.03) (Fig. 2C).


In Vitro Apoptotic Effects of Farnesyltransferase blockade in Acute Myeloid Leukemia Cells
FTI-induced inhibition of AML cell proliferation is partly related to apoptosis.Agarose gel stained with ethidium bromide after electrophoresis of low molecular weight DNA from 12 representative BM AML patients exposed for 48 h to FTIs at the IC50 (A). A representative flow cytometric detection of apoptic hypodiploid DNA peak stained with PI from BM AML patient exposed to SCH (B). Percentages of viable cells and apoptotic cells simultaneously measured from 10 representative BM AML patients after exposure for 48 h to FTIs (C). Cumulative percentage of mean inhibition of cell viability and apoptotic cells, as well as statistical analysis, are reported in the corresponding results section. Abbreviations, see text.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120747&req=5

f2-tm-15-22: FTI-induced inhibition of AML cell proliferation is partly related to apoptosis.Agarose gel stained with ethidium bromide after electrophoresis of low molecular weight DNA from 12 representative BM AML patients exposed for 48 h to FTIs at the IC50 (A). A representative flow cytometric detection of apoptic hypodiploid DNA peak stained with PI from BM AML patient exposed to SCH (B). Percentages of viable cells and apoptotic cells simultaneously measured from 10 representative BM AML patients after exposure for 48 h to FTIs (C). Cumulative percentage of mean inhibition of cell viability and apoptotic cells, as well as statistical analysis, are reported in the corresponding results section. Abbreviations, see text.
Mentions: To define whether the FTI-mediated growth inhibition of primary AML cells was associated to apoptosis, BM AML cells sensitive to FTI inhibition were exposed for 48 h to FTIs at IC50. By LMW DNA fragmentation analysis, AML cells showed the characteristic DNA ladder suggestive of apoptosis (Fig. 2A). Flow cytometric detection of apoptotic hypodiploid DNA peak derived from treated BM AML cells confirmed the FTI-enhanced apoptotic cytotoxic effect (Fig. 2B). Indeed, percentages of apoptotic AML cells were significantly lower than those with cytolysis measured by cell viability assay (mean % ± SEM of cytolysis, 55.7±10; p=0.03). The parallel measurement of the number of apoptotic AML cells and viable cells from 10 AML patients carried by flow cytometry and cell viability assays showed that the percentages of apoptotic AML cells were significantly lower than those undergoing cytolysis (mean % ± SEM of apoptotic and viable AML cells, 32 ± 7 vs 51 ± 11, respectively; p = 0.03) (Fig. 2C).

View Article: PubMed Central - PubMed

ABSTRACT

Farnesyltransferase inhibitors (FTIs) are a class of oral anti-cancer drugs currently tested in phase I-II clinical trials for treatment of hematological malignancies. The in vitro effects of various FTIs (alpha-hydroxyfarnesylphosphonic acid, manumycin-A and SCH66336) were tested on CD34+ KG1a cell line and in primary acute myeloid leukemia (AML) cells from 64 patients. By cell viability and clonogeneic methylcellulose assays, FTIs showed a significant inhibitory activity in CD34+ KG1a and primary bone marrow (BM) leukemic cells from 56% of AML patients. FTIs also induced activation of caspase-3 and Fas-independent apoptosis, confirmed by the finding that inhibition of caspase-8 was not associated with the rescue of FTI-treated cells. We concluded that other cellular events induced by FTIs may trigger activation of caspase-3 and subsequent apoptosis, but the expression of proapoptotic molecules, as Bcl-2 and Bcl-XL, and antiapoptotic, as Bcl-X(s), were not modified by FTIs. By contrast, expression of inducible nitric oxide synthase (iNOS) was increased in FTI-treated AML cells. Our results suggest a very complex mechanism of action of FTIs that require more studies for a better clinical use of the drugs alone or in combination in the treatment of hematological malignancies.

No MeSH data available.


Related in: MedlinePlus