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Restoration of transforming growth factor-beta signaling enhances radiosensitivity by altering the Bcl-2/Bax ratio in the p53 mutant pancreatic cancer cell line MIA PaCa-2.

Abstract

In this study, we investigated whether lack of transforming growth factor beta (TGF-beta) type II receptor (RII) expression and loss of TGF-beta signaling played a role in radiation resistance of pancreatic cancer cells MIA PaCa-2 that possess a mutated p53 gene. Transfection of this cell line with a RII cDNA led to a stimulation of the transcriptional activity of p3TP-Lux, a TGF-beta-responsive reporter construct. The RII transfectants (MIA PaCa-2/RII) showed a significant increase in sensitivity to radiation when compared with MIA PaCa-2/vector cells. The increase in sensitivity to radiation was reversed by neutralizing antibodies to TGF-beta, indicating that these changes were dependent on TGF-beta signaling. Compared with MIA PaCa-2/vector cells, MIA PaCa-2/RII cells showed a greater than 3-fold increase in apoptosis after radiation. Enhanced radiation sensitivity of MIA PaCa-2/RII cells was associated with an induction of Bax mRNA and protein that was followed by a release of cytochrome c and activation of caspase-3 and poly(ADP-ribose) polymerase cleavage after radiation exposure. Overexpression of Bcl-x(L) or treatment with antisense oligodeoxynucleotides targeted against Bax significantly inhibited radiation-induced apoptosis in MIA PaCa-2/RII but not in MIA PaCa-2/Vector cells, suggesting that Bax induction is necessary for radiation-induced TGF-beta signaling-mediated apoptosis. Thus, restoration of TGF-beta signaling sensitized these cells to ionizing radiation, although these cells possess a mutated p53 gene. In addition, disruption of RII function by dominant negative mutant of RII inhibited the radiation-induced TGF-beta signaling and apoptosis in primary cultures of mouse embryonic fibroblasts. Together, these observations imply that RII is an important component of radiation-induced TGF-beta signaling, and loss of function of RII may enhance resistance to radiation-induced apoptosis.

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  • Authors+Show Affiliations

    ,

    Department of Radiation Medicine, Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA.

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    Source

    The Journal of biological chemistry 277:3 2002 Jan 18 pg 2234-46

    MeSH

    Apoptosis
    Caspase 3
    Caspases
    Cyclin-Dependent Kinase Inhibitor p21
    Cyclins
    Cytochrome c Group
    Humans
    Mutation
    Pancreatic Neoplasms
    Proto-Oncogene Proteins
    Proto-Oncogene Proteins c-bcl-2
    RNA, Messenger
    Radiation Tolerance
    Receptors, Transforming Growth Factor beta
    Signal Transduction
    Transfection
    Transforming Growth Factor beta
    Tumor Cells, Cultured
    Tumor Suppressor Protein p53
    bcl-2-Associated X Protein

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't
    Research Support, U.S. Gov't, P.H.S.

    Language

    eng

    PubMed ID

    11694525

    Citation

    Ahmed, Mansoor M., et al. "Restoration of Transforming Growth Factor-beta Signaling Enhances Radiosensitivity By Altering the Bcl-2/Bax Ratio in the P53 Mutant Pancreatic Cancer Cell Line MIA PaCa-2." The Journal of Biological Chemistry, vol. 277, no. 3, 2002, pp. 2234-46.
    Ahmed MM, Alcock RA, Chendil D, et al. Restoration of transforming growth factor-beta signaling enhances radiosensitivity by altering the Bcl-2/Bax ratio in the p53 mutant pancreatic cancer cell line MIA PaCa-2. J Biol Chem. 2002;277(3):2234-46.
    Ahmed, M. M., Alcock, R. A., Chendil, D., Dey, S., Das, A., Venkatasubbarao, K., ... Freeman, J. W. (2002). Restoration of transforming growth factor-beta signaling enhances radiosensitivity by altering the Bcl-2/Bax ratio in the p53 mutant pancreatic cancer cell line MIA PaCa-2. The Journal of Biological Chemistry, 277(3), pp. 2234-46.
    Ahmed MM, et al. Restoration of Transforming Growth Factor-beta Signaling Enhances Radiosensitivity By Altering the Bcl-2/Bax Ratio in the P53 Mutant Pancreatic Cancer Cell Line MIA PaCa-2. J Biol Chem. 2002 Jan 18;277(3):2234-46. PubMed PMID: 11694525.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Restoration of transforming growth factor-beta signaling enhances radiosensitivity by altering the Bcl-2/Bax ratio in the p53 mutant pancreatic cancer cell line MIA PaCa-2. AU - Ahmed,Mansoor M, AU - Alcock,Rachael A, AU - Chendil,Damodaran, AU - Dey,Swatee, AU - Das,Anindita, AU - Venkatasubbarao,Kolaparthi, AU - Mohiuddin,Mohammed, AU - Sun,LuZhe, AU - Strodel,William E, AU - Freeman,James W, Y1 - 2001/11/01/ PY - 2001/11/6/pubmed PY - 2002/2/14/medline PY - 2001/11/6/entrez SP - 2234 EP - 46 JF - The Journal of biological chemistry JO - J. Biol. Chem. VL - 277 IS - 3 N2 - In this study, we investigated whether lack of transforming growth factor beta (TGF-beta) type II receptor (RII) expression and loss of TGF-beta signaling played a role in radiation resistance of pancreatic cancer cells MIA PaCa-2 that possess a mutated p53 gene. Transfection of this cell line with a RII cDNA led to a stimulation of the transcriptional activity of p3TP-Lux, a TGF-beta-responsive reporter construct. The RII transfectants (MIA PaCa-2/RII) showed a significant increase in sensitivity to radiation when compared with MIA PaCa-2/vector cells. The increase in sensitivity to radiation was reversed by neutralizing antibodies to TGF-beta, indicating that these changes were dependent on TGF-beta signaling. Compared with MIA PaCa-2/vector cells, MIA PaCa-2/RII cells showed a greater than 3-fold increase in apoptosis after radiation. Enhanced radiation sensitivity of MIA PaCa-2/RII cells was associated with an induction of Bax mRNA and protein that was followed by a release of cytochrome c and activation of caspase-3 and poly(ADP-ribose) polymerase cleavage after radiation exposure. Overexpression of Bcl-x(L) or treatment with antisense oligodeoxynucleotides targeted against Bax significantly inhibited radiation-induced apoptosis in MIA PaCa-2/RII but not in MIA PaCa-2/Vector cells, suggesting that Bax induction is necessary for radiation-induced TGF-beta signaling-mediated apoptosis. Thus, restoration of TGF-beta signaling sensitized these cells to ionizing radiation, although these cells possess a mutated p53 gene. In addition, disruption of RII function by dominant negative mutant of RII inhibited the radiation-induced TGF-beta signaling and apoptosis in primary cultures of mouse embryonic fibroblasts. Together, these observations imply that RII is an important component of radiation-induced TGF-beta signaling, and loss of function of RII may enhance resistance to radiation-induced apoptosis. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/11694525/Restoration_of_transforming_growth_factor_beta_signaling_enhances_radiosensitivity_by_altering_the_Bcl_2/Bax_ratio_in_the_p53_mutant_pancreatic_cancer_cell_line_MIA_PaCa_2_ L2 - http://www.jbc.org/cgi/pmidlookup?view=long&pmid=11694525 DB - PRIME DP - Unbound Medicine ER -