TY - JOUR

T1 - Sensitization to the lysosomal cell death pathway upon immortalization and transformation.

AU - Fehrenbacher, Nicole

AU - Gyrd-Hansen, Mads

AU - Poulsen, Birgit

AU - Felbor, Ute

AU - Kallunki, Tuula

AU - Boes, Marianne

AU - Weber, Ekkehard

AU - Leist, Marcel

AU - Jäättelä, Marja

N1 - Keywords: Animals; Antineoplastic Agents; Apoptosis; Caspase 3; Caspases; Cathepsin B; Cathepsin D; Cathepsins; Cell Transformation, Neoplastic; Cysteine Endopeptidases; Cytochromes c; Drug Resistance, Neoplasm; Embryo, Mammalian; Enzyme Activation; Enzyme Inhibitors; Fibroblasts; Genes, ras; Genes, src; Lysosomes; Mice; Mice, Inbred C57BL; Mice, Knockout; NIH 3T3 Cells; RNA Interference; Signal Transduction; Transfection; Tumor Necrosis Factor-alpha

PY - 2004

Y1 - 2004

N2 - Tumorigenesis is associated with several changes that alter the cellular susceptibility to programmed cell death. Here, we show that immortalization and transformation sensitize cells in particular to the cysteine cathepsin-mediated lysosomal death pathway. Spontaneous immortalization increased the susceptibility of wild-type murine embryonic fibroblasts (MEFs) to tumor necrosis factor (TNF)-mediated cytotoxicity >1000-fold, whereas immortalized MEFs deficient for lysosomal cysteine protease cathepsin B (CathB) retained the resistant phenotype of primary cells. This effect was specific for cysteine cathepsins, because also lack of cathepsin L (a lysosomal cysteine protease), but not that of cathepsin D (a lysosomal aspartyl protease) or caspase-3 (the major executioner protease in classic apoptosis) inhibited the immortalization-associated sensitization of MEFs to TNF. Oncogene-driven transformation of immortalized MEFs was associated with a dramatic increase in cathepsin expression and additional sensitization to the cysteine cathepsin-mediated death pathway. Importantly, exogenous expression of CathB partially reversed the resistant phenotype of immortalized CathB-deficient MEFs, and the inhibition of CathB activity by pharmacological inhibitors or RNA interference attenuated TNF-induced cytotoxicity in immortalized and transformed wild-type cells. Thus, tumorigenesis-associated changes in lysosomes may counteract cancer progression and enhance therapeutic responses by sensitizing cells to programmed cell death.

AB - Tumorigenesis is associated with several changes that alter the cellular susceptibility to programmed cell death. Here, we show that immortalization and transformation sensitize cells in particular to the cysteine cathepsin-mediated lysosomal death pathway. Spontaneous immortalization increased the susceptibility of wild-type murine embryonic fibroblasts (MEFs) to tumor necrosis factor (TNF)-mediated cytotoxicity >1000-fold, whereas immortalized MEFs deficient for lysosomal cysteine protease cathepsin B (CathB) retained the resistant phenotype of primary cells. This effect was specific for cysteine cathepsins, because also lack of cathepsin L (a lysosomal cysteine protease), but not that of cathepsin D (a lysosomal aspartyl protease) or caspase-3 (the major executioner protease in classic apoptosis) inhibited the immortalization-associated sensitization of MEFs to TNF. Oncogene-driven transformation of immortalized MEFs was associated with a dramatic increase in cathepsin expression and additional sensitization to the cysteine cathepsin-mediated death pathway. Importantly, exogenous expression of CathB partially reversed the resistant phenotype of immortalized CathB-deficient MEFs, and the inhibition of CathB activity by pharmacological inhibitors or RNA interference attenuated TNF-induced cytotoxicity in immortalized and transformed wild-type cells. Thus, tumorigenesis-associated changes in lysosomes may counteract cancer progression and enhance therapeutic responses by sensitizing cells to programmed cell death.

U2 - 10.1158/0008-5472.CAN-04-1427

DO - 10.1158/0008-5472.CAN-04-1427

M3 - Journal article

C2 - 15289336

VL - 64

SP - 5301

EP - 5310

JO - Cancer Research

JF - Cancer Research

SN - 0008-5472

IS - 15

ER -