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Pseudomonas aeruginosa exotoxin A reduces chemoresistance of oral squamous carcinoma cell via inhibition of heat shock proteins 70 (HSP70).

Park SR, Lee KD, Kim UK, Gil YG, Oh KS, Park BS, Kim GC - Yonsei Med. J. (2010)

Bottom Line: On the other hand, PEA significantly decreased the viability of YD-9 cells by deteriorating the HSP70-relating protecting system through inhibition of HSP70 expression and inducing apoptosis in YD-9 cells.While p53, p21, and E2F-1 were upregulated, cdk2 and cyclin B were downregulated by PEA treatment, suggesting that PEA caused cell cycle arrest at the G2/M checkpoint.Therefore, these results indicate that PEA reduced the chemoresistance through inhibition of HSP70 expression and also induced apoptosis in chemoresistant YD-9 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Anatomy, School of Dentistry, Research Institute for Oral Biotechnology, Pusan National University, Yangsan, Korea.

ABSTRACT

Purpose: Oral squamous carcinoma (OSCC) cells exhibit resistance to chemotherapeutic agent-mediated apoptosis in the late stage of malignancy. Increased levels of heat shock proteins 70 (HSP70) in cancer cells are known to confer resistance to apoptosis. Since recent advances in the understanding of bacterial toxins have produced new strategies for the treatment of cancers, we investigated the effect of Pseudomonas aeruginosa exotoxin A (PEA) on HSP70 expression and induction of apoptosis in chemoresistant OSCC cell line (YD-9).

Materials and methods: The apoptotic effect of PEA on chemoresistant YD-9 cells was confirmed by MTT, Hoechst and TUNEL stains, DNA electrophoresis, and Western blot analysis.

Results: While YD-9 cells showed high resistance to chemotherapeutic agents such as etoposide and 5-fluorouraci (5-FU), HSP70 antisense oligonucelotides sensitized chemoresistant YD-9 cells to etoposide and 5-FU. On the other hand, PEA significantly decreased the viability of YD-9 cells by deteriorating the HSP70-relating protecting system through inhibition of HSP70 expression and inducing apoptosis in YD-9 cells. Apoptotic manifestations were evidenced by changes in nuclear morphology, generation of DNA fragmentation, and activation of caspases. While p53, p21, and E2F-1 were upregulated, cdk2 and cyclin B were downregulated by PEA treatment, suggesting that PEA caused cell cycle arrest at the G2/M checkpoint.

Conclusion: Therefore, these results indicate that PEA reduced the chemoresistance through inhibition of HSP70 expression and also induced apoptosis in chemoresistant YD-9 cells.

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Related in: MedlinePlus

Restoration of sensitivity to etoposide and 5-FU by inhibition of HSP70. (A) After incubation with HSP70 antisense oligonucleotide for 24 hours as described in the material and methods section, YD-9 cells were treated with various concentrations of etoposide and 5-FU. (B) After incubation with 15 nM PEA for 24 hours, YD-9 cells were treated with various concentrations of etoposide and 5-FU. Cell viabilities were determined by an MTT assay. Four independent assays were performed and data shown are the mean ± SD of the means obtained from triplicates of each assay.
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Figure 3: Restoration of sensitivity to etoposide and 5-FU by inhibition of HSP70. (A) After incubation with HSP70 antisense oligonucleotide for 24 hours as described in the material and methods section, YD-9 cells were treated with various concentrations of etoposide and 5-FU. (B) After incubation with 15 nM PEA for 24 hours, YD-9 cells were treated with various concentrations of etoposide and 5-FU. Cell viabilities were determined by an MTT assay. Four independent assays were performed and data shown are the mean ± SD of the means obtained from triplicates of each assay.

Mentions: To examine if HSP70 plays any role in chemoresistance of YD-9 cells to anti-cancer drugs such as etoposide and 5-FU, HSP70 antisense oligonucleotide was administered to YD-9 cells. The treatment of HSP70 antisense oligonucleotide significantly increased the sensitivity of the cells to these anti-cancer drugs compared to anti-cancer drug treatment alone (Fig. 3A). We further confirmed the inhibitory effect of PEA on chemoresistance of YD-9 cells to etoposide and 5-FU. The treatment of YD-9 cells with etoposide and 5-FU, following incubation in 1.5 nM PEA for 24 hours, significantly decreased the viability of YD-9 cells compared to anti-cancer drug treatment alone (Fig. 3B).


Pseudomonas aeruginosa exotoxin A reduces chemoresistance of oral squamous carcinoma cell via inhibition of heat shock proteins 70 (HSP70).

Park SR, Lee KD, Kim UK, Gil YG, Oh KS, Park BS, Kim GC - Yonsei Med. J. (2010)

Restoration of sensitivity to etoposide and 5-FU by inhibition of HSP70. (A) After incubation with HSP70 antisense oligonucleotide for 24 hours as described in the material and methods section, YD-9 cells were treated with various concentrations of etoposide and 5-FU. (B) After incubation with 15 nM PEA for 24 hours, YD-9 cells were treated with various concentrations of etoposide and 5-FU. Cell viabilities were determined by an MTT assay. Four independent assays were performed and data shown are the mean ± SD of the means obtained from triplicates of each assay.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2908850&req=5

Figure 3: Restoration of sensitivity to etoposide and 5-FU by inhibition of HSP70. (A) After incubation with HSP70 antisense oligonucleotide for 24 hours as described in the material and methods section, YD-9 cells were treated with various concentrations of etoposide and 5-FU. (B) After incubation with 15 nM PEA for 24 hours, YD-9 cells were treated with various concentrations of etoposide and 5-FU. Cell viabilities were determined by an MTT assay. Four independent assays were performed and data shown are the mean ± SD of the means obtained from triplicates of each assay.
Mentions: To examine if HSP70 plays any role in chemoresistance of YD-9 cells to anti-cancer drugs such as etoposide and 5-FU, HSP70 antisense oligonucleotide was administered to YD-9 cells. The treatment of HSP70 antisense oligonucleotide significantly increased the sensitivity of the cells to these anti-cancer drugs compared to anti-cancer drug treatment alone (Fig. 3A). We further confirmed the inhibitory effect of PEA on chemoresistance of YD-9 cells to etoposide and 5-FU. The treatment of YD-9 cells with etoposide and 5-FU, following incubation in 1.5 nM PEA for 24 hours, significantly decreased the viability of YD-9 cells compared to anti-cancer drug treatment alone (Fig. 3B).

Bottom Line: On the other hand, PEA significantly decreased the viability of YD-9 cells by deteriorating the HSP70-relating protecting system through inhibition of HSP70 expression and inducing apoptosis in YD-9 cells.While p53, p21, and E2F-1 were upregulated, cdk2 and cyclin B were downregulated by PEA treatment, suggesting that PEA caused cell cycle arrest at the G2/M checkpoint.Therefore, these results indicate that PEA reduced the chemoresistance through inhibition of HSP70 expression and also induced apoptosis in chemoresistant YD-9 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Anatomy, School of Dentistry, Research Institute for Oral Biotechnology, Pusan National University, Yangsan, Korea.

ABSTRACT

Purpose: Oral squamous carcinoma (OSCC) cells exhibit resistance to chemotherapeutic agent-mediated apoptosis in the late stage of malignancy. Increased levels of heat shock proteins 70 (HSP70) in cancer cells are known to confer resistance to apoptosis. Since recent advances in the understanding of bacterial toxins have produced new strategies for the treatment of cancers, we investigated the effect of Pseudomonas aeruginosa exotoxin A (PEA) on HSP70 expression and induction of apoptosis in chemoresistant OSCC cell line (YD-9).

Materials and methods: The apoptotic effect of PEA on chemoresistant YD-9 cells was confirmed by MTT, Hoechst and TUNEL stains, DNA electrophoresis, and Western blot analysis.

Results: While YD-9 cells showed high resistance to chemotherapeutic agents such as etoposide and 5-fluorouraci (5-FU), HSP70 antisense oligonucelotides sensitized chemoresistant YD-9 cells to etoposide and 5-FU. On the other hand, PEA significantly decreased the viability of YD-9 cells by deteriorating the HSP70-relating protecting system through inhibition of HSP70 expression and inducing apoptosis in YD-9 cells. Apoptotic manifestations were evidenced by changes in nuclear morphology, generation of DNA fragmentation, and activation of caspases. While p53, p21, and E2F-1 were upregulated, cdk2 and cyclin B were downregulated by PEA treatment, suggesting that PEA caused cell cycle arrest at the G2/M checkpoint.

Conclusion: Therefore, these results indicate that PEA reduced the chemoresistance through inhibition of HSP70 expression and also induced apoptosis in chemoresistant YD-9 cells.

Show MeSH
Related in: MedlinePlus