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Dual role of Sp3 transcription factor as an inducer of apoptosis and a marker of tumour aggressiveness.

Essafi-Benkhadir K, Grosso S, Puissant A, Robert G, Essafi M, Deckert M, Chamorey E, Dassonville O, Milano G, Auberger P, Pagès G - PLoS ONE (2009)

Bottom Line: The ambiguous role of transcription factor Sp3 for tumour progression is still debated since it was described as a transcriptional repressor or activator.Progression coincides with re-accumulation of the full length form of Sp3.The presence of high levels of the full-length form of Sp3 indicates a poor prognosis for overall survival of patients with head and neck tumours.

View Article: PubMed Central - PubMed

Affiliation: University of Nice-Sophia Antipolis, Institute of Developmental Biology and Cancer Research UMR CNRS 6543, Centre Antoine Lacassagne, Nice, France.

ABSTRACT

Background: The ambiguous role of transcription factor Sp3 for tumour progression is still debated since it was described as a transcriptional repressor or activator. Here we tried to decipher the molecular mechanisms implicated in Sp3 accumulation observed in aggressive tumours.

Methodology: We generated normal and tumour cell lines conditionally expressing Sp3. Cell growth was analyzed in vitro and after inoculation in nude mice. Apoptosis was assessed by pan- caspase activity assays, by counting fragmented nuclei and by determination of caspase 9 cleavage. Gene expression was determined by quantitative PCR. Cleavage by different caspases was performed after in vitro translation of the Sp3 cDNA in the presence of [S(35)] labelled methionine. Different tumour cell lines and head and neck tumour samples were tested for the presence of Sp3 by western blots. Correlation between Sp3 expression and overall survival has been statistically determined.

Principal findings: Conditional over-expression of Sp3 induces apoptosis and modifies expression of genes implicated in the regulation of cell cycle and pro and anti apoptotic genes. Sp3 over-expression strongly reduces the development of tumours in nude mice confirming its pro-apoptotic potential in vivo. However, cells can survive to apoptosis through selective Sp3 cleavage by caspase. Sp3 induction in established tumours resulted in transient regression then progression. Progression coincides with re-accumulation of the full length form of Sp3. Sp3 is over-expressed in tumour cell lines of different origins. The presence of high levels of the full-length form of Sp3 indicates a poor prognosis for overall survival of patients with head and neck tumours.

Conclusions: Full length Sp3 accumulation highlights bypass of tumour cell apoptotic capacities and is indicative of head and neck tumours aggressiveness.

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Related in: MedlinePlus

Gene expression profile in cells with conditional Sp3 expression.Expression of 88 pro- and anti-apoptotic genes was tested in LS174 cells conditionally expressing Sp3 (S27) by real time PCR. The variations of the significantly modified genes (* p<0.05) are represented. The mean fold increase±SD of three independent experiments performed in triplicate, is plotted.
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pone-0004478-g004: Gene expression profile in cells with conditional Sp3 expression.Expression of 88 pro- and anti-apoptotic genes was tested in LS174 cells conditionally expressing Sp3 (S27) by real time PCR. The variations of the significantly modified genes (* p<0.05) are represented. The mean fold increase±SD of three independent experiments performed in triplicate, is plotted.

Mentions: The involvement of Sp3 in cell death was further evaluated by testing the expression of different specific transcripts involved in apoptosis and survival. We focused on a limited number of major pro- or anti-apoptotic genes (88) (File S1). Of these, 11 were up-regulated and only one (Bcl-2) was down-regulated. Figure 4 shows that both pro- (TGF β, GADD45, MyD88, DR3, Puma, Fas caspase 9) and anti-apoptotic (Egr-1, IEX-1, STAT-5, Bcl2) genes were modulated by Sp3. p21/WAF1 is not directly implicated in apoptosis but regulates cell cycle. Regulation of p21/WAF1 by Sp3 has already been described [13]. It suggests that the decrease in cell number observed in figure 2 is a combination of Sp3-induced apoptosis and cell cycle arrest. Since p27 expression is induced upon Sp3 down-regulation by siRNA [14] we have tested its amounts in both R443 and LS74 cells upon Sp3 induction. No modifications were observed in both cell lines (File S2). This complex set of regulated genes may explain the contradictory functions of Sp3 in the regulation of cell death and cell growth.


Dual role of Sp3 transcription factor as an inducer of apoptosis and a marker of tumour aggressiveness.

Essafi-Benkhadir K, Grosso S, Puissant A, Robert G, Essafi M, Deckert M, Chamorey E, Dassonville O, Milano G, Auberger P, Pagès G - PLoS ONE (2009)

Gene expression profile in cells with conditional Sp3 expression.Expression of 88 pro- and anti-apoptotic genes was tested in LS174 cells conditionally expressing Sp3 (S27) by real time PCR. The variations of the significantly modified genes (* p<0.05) are represented. The mean fold increase±SD of three independent experiments performed in triplicate, is plotted.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2636865&req=5

pone-0004478-g004: Gene expression profile in cells with conditional Sp3 expression.Expression of 88 pro- and anti-apoptotic genes was tested in LS174 cells conditionally expressing Sp3 (S27) by real time PCR. The variations of the significantly modified genes (* p<0.05) are represented. The mean fold increase±SD of three independent experiments performed in triplicate, is plotted.
Mentions: The involvement of Sp3 in cell death was further evaluated by testing the expression of different specific transcripts involved in apoptosis and survival. We focused on a limited number of major pro- or anti-apoptotic genes (88) (File S1). Of these, 11 were up-regulated and only one (Bcl-2) was down-regulated. Figure 4 shows that both pro- (TGF β, GADD45, MyD88, DR3, Puma, Fas caspase 9) and anti-apoptotic (Egr-1, IEX-1, STAT-5, Bcl2) genes were modulated by Sp3. p21/WAF1 is not directly implicated in apoptosis but regulates cell cycle. Regulation of p21/WAF1 by Sp3 has already been described [13]. It suggests that the decrease in cell number observed in figure 2 is a combination of Sp3-induced apoptosis and cell cycle arrest. Since p27 expression is induced upon Sp3 down-regulation by siRNA [14] we have tested its amounts in both R443 and LS74 cells upon Sp3 induction. No modifications were observed in both cell lines (File S2). This complex set of regulated genes may explain the contradictory functions of Sp3 in the regulation of cell death and cell growth.

Bottom Line: The ambiguous role of transcription factor Sp3 for tumour progression is still debated since it was described as a transcriptional repressor or activator.Progression coincides with re-accumulation of the full length form of Sp3.The presence of high levels of the full-length form of Sp3 indicates a poor prognosis for overall survival of patients with head and neck tumours.

View Article: PubMed Central - PubMed

Affiliation: University of Nice-Sophia Antipolis, Institute of Developmental Biology and Cancer Research UMR CNRS 6543, Centre Antoine Lacassagne, Nice, France.

ABSTRACT

Background: The ambiguous role of transcription factor Sp3 for tumour progression is still debated since it was described as a transcriptional repressor or activator. Here we tried to decipher the molecular mechanisms implicated in Sp3 accumulation observed in aggressive tumours.

Methodology: We generated normal and tumour cell lines conditionally expressing Sp3. Cell growth was analyzed in vitro and after inoculation in nude mice. Apoptosis was assessed by pan- caspase activity assays, by counting fragmented nuclei and by determination of caspase 9 cleavage. Gene expression was determined by quantitative PCR. Cleavage by different caspases was performed after in vitro translation of the Sp3 cDNA in the presence of [S(35)] labelled methionine. Different tumour cell lines and head and neck tumour samples were tested for the presence of Sp3 by western blots. Correlation between Sp3 expression and overall survival has been statistically determined.

Principal findings: Conditional over-expression of Sp3 induces apoptosis and modifies expression of genes implicated in the regulation of cell cycle and pro and anti apoptotic genes. Sp3 over-expression strongly reduces the development of tumours in nude mice confirming its pro-apoptotic potential in vivo. However, cells can survive to apoptosis through selective Sp3 cleavage by caspase. Sp3 induction in established tumours resulted in transient regression then progression. Progression coincides with re-accumulation of the full length form of Sp3. Sp3 is over-expressed in tumour cell lines of different origins. The presence of high levels of the full-length form of Sp3 indicates a poor prognosis for overall survival of patients with head and neck tumours.

Conclusions: Full length Sp3 accumulation highlights bypass of tumour cell apoptotic capacities and is indicative of head and neck tumours aggressiveness.

Show MeSH
Related in: MedlinePlus