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Farnesyl diphosphate synthase is involved in the resistance to zoledronic acid of osteosarcoma cells.

Ory B, Moriceau G, Trichet V, Blanchard F, Berreur M, Rédini F, Rogers M, Heymann D - J. Cell. Mol. Med. (2008)

Bottom Line: Furthermore, the Zol-resistant cells were sensitive to conventional anti-cancer agents demonstrating that this resistance process is independent of the multidrug resistance phenotype.The transfection of Zol-resistant cells with FPPS siRNA strongly increased their sensitivity to Zol.This study demonstrates for the first time the induction of metabolic resistance after prolonged Zol treatment of osteosarcoma cells confirming the therapeutic potential of Zol for the treatment of bone malignant pathologies, but points out the importance of the treatment regimen may be important in terms of duration and dose to avoid the development of drug metabolic resistance.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale, ERI 7, Nantes, France.

ABSTRACT
We recently demonstrated original anti-tumor effects of zoledronic acid (Zol) on osteosarcoma cell lines independently of their p53 and Rb status. The present study investigated the potential Zol-resistance acquired by osteosarcoma cells after prolonged treatment. After 12 weeks of culture in the presence of 1 microm Zol, the effects of high doses of Zol (10-100 microm) were compared between the untreated rat (OSRGA, ROS) and human (MG63, SAOS2) osteosarcoma cells and Zol-pretreated cells in terms of cell proliferation, cell cycle analysis, migration assay and cytoskeleton organization. Long-term treatment with 1 microm Zol reduced the sensitivity of osteosarcoma cells to high concentrations of Zol. Furthermore, the Zol-resistant cells were sensitive to conventional anti-cancer agents demonstrating that this resistance process is independent of the multidrug resistance phenotype. However, as similar experiments performed in the presence of clodronate and pamidronate evidenced that this drug resistance was restricted to the nitrogen-containing bisphosphonates, we then hypothesized that this resistance could be associated with a differential expression of farnesyl diphos-phate synthase (FPPS) also observed in human osteosarcoma samples. The transfection of Zol-resistant cells with FPPS siRNA strongly increased their sensitivity to Zol. This study demonstrates for the first time the induction of metabolic resistance after prolonged Zol treatment of osteosarcoma cells confirming the therapeutic potential of Zol for the treatment of bone malignant pathologies, but points out the importance of the treatment regimen may be important in terms of duration and dose to avoid the development of drug metabolic resistance.

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Dual origin of Zol-resistance: innate and/or acquired. (A) OSRGA osteosarcoma cell lines were treated with increasing low concentration of Zol (1–104 pM) for 72 hrs. The number of viable cells was then determined using a XTT assay. Graphs represent the average values of three independent experiments performed in triplicate. Error bars represent the standard deviation. Farnesyl diphosphate synthase (FPPS) transcription level was determined by semi-quantitative RT PCR under the same conditions of Zol treatment. The 18S was used as a control. (B) Similar experiments were performed with higher concentrations of Zol (0.1–100 μM) in two OSRGA clones obtained by limiting dilution.***P < 0.001. Statistical evaluation of the data was performed using the ANOVA test. (C) Transcriptional analysis of FPPS in seven human osteosarcoma samples analyzed by semi-quantitative RT-PCR.
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fig06: Dual origin of Zol-resistance: innate and/or acquired. (A) OSRGA osteosarcoma cell lines were treated with increasing low concentration of Zol (1–104 pM) for 72 hrs. The number of viable cells was then determined using a XTT assay. Graphs represent the average values of three independent experiments performed in triplicate. Error bars represent the standard deviation. Farnesyl diphosphate synthase (FPPS) transcription level was determined by semi-quantitative RT PCR under the same conditions of Zol treatment. The 18S was used as a control. (B) Similar experiments were performed with higher concentrations of Zol (0.1–100 μM) in two OSRGA clones obtained by limiting dilution.***P < 0.001. Statistical evaluation of the data was performed using the ANOVA test. (C) Transcriptional analysis of FPPS in seven human osteosarcoma samples analyzed by semi-quantitative RT-PCR.

Mentions: To explain the origin of the Zol-resistance observed in osteosarcoma cell lines, two hypotheses can be proposed: (i) an innate resistance mechanism linked to differential levels of FPPS expression and associated with selection of a sub-population of cells expressing a higher FPPS activity, (ii) an acquired resistance mechanism linked to an increased FPPS transcription level as a feedback response to long-term, low-dose Zol treatment. To distinguish between these two hypotheses, OSRGA osteosarcoma cell lines were treated with low Zol concentrations (1–104 pM) for 72 hrs (Fig. 6A). Low concentrations of Zol induced a 60% increase of viable cells and up-modulated the expression of FPPS mRNA in a dose-dependent manner (Fig. 6A), these results support acquired resistance to Zol. Since a potential mechanism of innate resistance could be also envisaged, OSRGA cell line was cloned by limiting dilution and the expression of FPPS was analyzed by semi-quantitative RT-PCR (Fig. 6B). Several clones were isolated with heterogenous sensitivity to Zol treatment (Fig. 6B). Furthermore, the isolated clones expressed differential levels of FPPS related to their sensitivity to Zol treatment, these results support innate resistance to Zol (Fig. 6B). Similarly, we analyzed the transcriptional expression of FPPS in seven human osteosarcoma samples analyzed by semi-quantitative RT-PCR before any chemotherapy (Fig. 6C). The results revealed that a very high heterogeneity of FPPS expression inthese patients strengthening the hypothesis of innate resistance to Zol.


Farnesyl diphosphate synthase is involved in the resistance to zoledronic acid of osteosarcoma cells.

Ory B, Moriceau G, Trichet V, Blanchard F, Berreur M, Rédini F, Rogers M, Heymann D - J. Cell. Mol. Med. (2008)

Dual origin of Zol-resistance: innate and/or acquired. (A) OSRGA osteosarcoma cell lines were treated with increasing low concentration of Zol (1–104 pM) for 72 hrs. The number of viable cells was then determined using a XTT assay. Graphs represent the average values of three independent experiments performed in triplicate. Error bars represent the standard deviation. Farnesyl diphosphate synthase (FPPS) transcription level was determined by semi-quantitative RT PCR under the same conditions of Zol treatment. The 18S was used as a control. (B) Similar experiments were performed with higher concentrations of Zol (0.1–100 μM) in two OSRGA clones obtained by limiting dilution.***P < 0.001. Statistical evaluation of the data was performed using the ANOVA test. (C) Transcriptional analysis of FPPS in seven human osteosarcoma samples analyzed by semi-quantitative RT-PCR.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4401135&req=5

fig06: Dual origin of Zol-resistance: innate and/or acquired. (A) OSRGA osteosarcoma cell lines were treated with increasing low concentration of Zol (1–104 pM) for 72 hrs. The number of viable cells was then determined using a XTT assay. Graphs represent the average values of three independent experiments performed in triplicate. Error bars represent the standard deviation. Farnesyl diphosphate synthase (FPPS) transcription level was determined by semi-quantitative RT PCR under the same conditions of Zol treatment. The 18S was used as a control. (B) Similar experiments were performed with higher concentrations of Zol (0.1–100 μM) in two OSRGA clones obtained by limiting dilution.***P < 0.001. Statistical evaluation of the data was performed using the ANOVA test. (C) Transcriptional analysis of FPPS in seven human osteosarcoma samples analyzed by semi-quantitative RT-PCR.
Mentions: To explain the origin of the Zol-resistance observed in osteosarcoma cell lines, two hypotheses can be proposed: (i) an innate resistance mechanism linked to differential levels of FPPS expression and associated with selection of a sub-population of cells expressing a higher FPPS activity, (ii) an acquired resistance mechanism linked to an increased FPPS transcription level as a feedback response to long-term, low-dose Zol treatment. To distinguish between these two hypotheses, OSRGA osteosarcoma cell lines were treated with low Zol concentrations (1–104 pM) for 72 hrs (Fig. 6A). Low concentrations of Zol induced a 60% increase of viable cells and up-modulated the expression of FPPS mRNA in a dose-dependent manner (Fig. 6A), these results support acquired resistance to Zol. Since a potential mechanism of innate resistance could be also envisaged, OSRGA cell line was cloned by limiting dilution and the expression of FPPS was analyzed by semi-quantitative RT-PCR (Fig. 6B). Several clones were isolated with heterogenous sensitivity to Zol treatment (Fig. 6B). Furthermore, the isolated clones expressed differential levels of FPPS related to their sensitivity to Zol treatment, these results support innate resistance to Zol (Fig. 6B). Similarly, we analyzed the transcriptional expression of FPPS in seven human osteosarcoma samples analyzed by semi-quantitative RT-PCR before any chemotherapy (Fig. 6C). The results revealed that a very high heterogeneity of FPPS expression inthese patients strengthening the hypothesis of innate resistance to Zol.

Bottom Line: Furthermore, the Zol-resistant cells were sensitive to conventional anti-cancer agents demonstrating that this resistance process is independent of the multidrug resistance phenotype.The transfection of Zol-resistant cells with FPPS siRNA strongly increased their sensitivity to Zol.This study demonstrates for the first time the induction of metabolic resistance after prolonged Zol treatment of osteosarcoma cells confirming the therapeutic potential of Zol for the treatment of bone malignant pathologies, but points out the importance of the treatment regimen may be important in terms of duration and dose to avoid the development of drug metabolic resistance.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale, ERI 7, Nantes, France.

ABSTRACT
We recently demonstrated original anti-tumor effects of zoledronic acid (Zol) on osteosarcoma cell lines independently of their p53 and Rb status. The present study investigated the potential Zol-resistance acquired by osteosarcoma cells after prolonged treatment. After 12 weeks of culture in the presence of 1 microm Zol, the effects of high doses of Zol (10-100 microm) were compared between the untreated rat (OSRGA, ROS) and human (MG63, SAOS2) osteosarcoma cells and Zol-pretreated cells in terms of cell proliferation, cell cycle analysis, migration assay and cytoskeleton organization. Long-term treatment with 1 microm Zol reduced the sensitivity of osteosarcoma cells to high concentrations of Zol. Furthermore, the Zol-resistant cells were sensitive to conventional anti-cancer agents demonstrating that this resistance process is independent of the multidrug resistance phenotype. However, as similar experiments performed in the presence of clodronate and pamidronate evidenced that this drug resistance was restricted to the nitrogen-containing bisphosphonates, we then hypothesized that this resistance could be associated with a differential expression of farnesyl diphos-phate synthase (FPPS) also observed in human osteosarcoma samples. The transfection of Zol-resistant cells with FPPS siRNA strongly increased their sensitivity to Zol. This study demonstrates for the first time the induction of metabolic resistance after prolonged Zol treatment of osteosarcoma cells confirming the therapeutic potential of Zol for the treatment of bone malignant pathologies, but points out the importance of the treatment regimen may be important in terms of duration and dose to avoid the development of drug metabolic resistance.

Show MeSH
Related in: MedlinePlus