title: Sensitization to the lysosomal cell death pathway by oncogene-induced down-regulation of lysosome-associated membrane proteins 1 and 2.
abstract: Expression and activity of lysosomal cysteine cathepsins correlate with the metastatic capacity and aggressiveness of tumors. Here, we show that transformation of murine embryonic fibroblasts with v-H-ras or c-src(Y527F) changes the distribution, density, and ultrastructure of the lysosomes, decreases the levels of lysosome-associated membrane proteins (LAMP-1 and LAMP-2) in an extracellular signal-regulated kinase (ERK)- and cathepsin-dependent manner, and sensitizes the cells to lysosomal cell death pathways induced by various anticancer drugs (i.e., cisplatin, etoposide, doxorubicin, and siramesine). Importantly, K-ras and erbb2 elicit a similar ERK-mediated activation of cysteine cathepsins, cathepsin-dependent down-regulation of LAMPs, and increased drug sensitivity in human colon and breast carcinoma cells, respectively. Notably, reconstitution of LAMP levels by ectopic expression or by cathepsin inhibitors protects transformed cells against the lysosomal cell death pathway. Furthermore, knockdown of either lamp1 or lamp2 is sufficient to sensitize the cells to siramesine-induced cell death and photo-oxidation-induced lysosomal destabilization. Thus, the transformation-associated ERK-mediated up-regulation of cysteine cathepsin expression and activity leads to a decrease in the levels of LAMPs, which in turn contributes to the enhanced sensitivity of transformed cells to drugs that trigger lysosomal membrane permeabilization. These data indicate that aggressive cancers with high cysteine cathepsin levels are especially sensitive to lysosomal cell death pathways and encourage the further development of lysosome-targeting compounds for cancer therapy.
authors.affiliation: Apoptosis Department and Centre for Genotoxic Stress Response, Institute for Cancer Biology, Danish Cancer Society, Copenhagen, Denmark.
authors.forename: Nicole
authors.initials: N
authors.lastname: Fehrenbacher
authors.forename: Lone
authors.initials: L
authors.lastname: Bastholm
authors.forename: Thomas
authors.initials: T
authors.lastname: Kirkegaard-Sørensen
authors.forename: Bo
authors.initials: B
authors.lastname: Rafn
authors.forename: Trine
authors.initials: T
authors.lastname: Bøttzauw
authors.forename: Christina
authors.initials: C
authors.lastname: Nielsen
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Weber
authors.forename: Senji
authors.initials: S
authors.lastname: Shirasawa
authors.forename: Tuula
authors.initials: T
authors.lastname: Kallunki
authors.forename: Marja
authors.initials: M
authors.lastname: Jäättelä
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002403:Cathepsins / Q000378:metabolism; D002450:Cell Communication; D002463:Cell Membrane Permeability; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011905:Genes, ras / Q000502:physiology; D006801:Humans; D052118:Lysosomal-Associated Membrane Protein 1 / Q000235:genetics / Q000378:metabolism*; D052119:Lysosomal-Associated Membrane Protein 2 / Q000235:genetics / Q000378:metabolism*; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D034622:RNA Interference
chemical_list: D000970:Antineoplastic Agents; D052118:Lysosomal-Associated Membrane Protein 1; D052119:Lysosomal-Associated Membrane Protein 2; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D002403:Cathepsins; D016283:Proto-Oncogene Proteins p21(ras)