Limits...
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.

Show MeSH

Related in: MedlinePlus

Western blot analysis of cell cycle regulation proteins in YD-9 cells treated with 15 nM PEA. YD-9 cells were treated with 15 nM PEA for the indicated time. Total cellular lysate proteins were resolved by SDS-PASE, transferred to nitrocellulose membranes, and probed for p53, p21, cdk1, and cyclin B.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2908850&req=5

Figure 7: Western blot analysis of cell cycle regulation proteins in YD-9 cells treated with 15 nM PEA. YD-9 cells were treated with 15 nM PEA for the indicated time. Total cellular lysate proteins were resolved by SDS-PASE, transferred to nitrocellulose membranes, and probed for p53, p21, cdk1, and cyclin B.

Mentions: We then investigated if PEA could modulate cell cycle regulatory proteins. We examined changes in protein levels using antibodies against key players in G2/M cell cycle regulation. Western blot analysis demonstrated that p53 increased at 8 and 16 hours after incubation with PEA, and then decreased. The expression of p21 increased after incubation with PEA, whereas the expression of cdk1 and cyclin B decreased in a time-dependent manner (Fig. 7).


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)

Western blot analysis of cell cycle regulation proteins in YD-9 cells treated with 15 nM PEA. YD-9 cells were treated with 15 nM PEA for the indicated time. Total cellular lysate proteins were resolved by SDS-PASE, transferred to nitrocellulose membranes, and probed for p53, p21, cdk1, and cyclin B.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Western blot analysis of cell cycle regulation proteins in YD-9 cells treated with 15 nM PEA. YD-9 cells were treated with 15 nM PEA for the indicated time. Total cellular lysate proteins were resolved by SDS-PASE, transferred to nitrocellulose membranes, and probed for p53, p21, cdk1, and cyclin B.
Mentions: We then investigated if PEA could modulate cell cycle regulatory proteins. We examined changes in protein levels using antibodies against key players in G2/M cell cycle regulation. Western blot analysis demonstrated that p53 increased at 8 and 16 hours after incubation with PEA, and then decreased. The expression of p21 increased after incubation with PEA, whereas the expression of cdk1 and cyclin B decreased in a time-dependent manner (Fig. 7).

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