title: Histochemical evidence of osteoclastic degradation of extracellular matrix in osteolytic metastasis originating from human lung small carcinoma (SBC-5) cells.
abstract: The aim of this study was to assess the dynamics of osteoclast migration and the degradation of unmineralized extracellular matrix in an osteolytic metastasis by examining a well-standardized lung cancer metastasis model of nude mice. SBC-5 human lung small carcinoma cells were injected into the left cardiac ventricle of 6-week-old BALB/c nu/nu mice under anesthesia. At 25-30 days after injection, the animals were sacrificed and their femora and/or tibiae were removed for histochemical analyses. Metastatic lesions were shown to occupy a considerable area extending from the metaphyses to the bone marrow region. Tartrate resistant acid phosphatase (TRAPase)-positive osteoclasts were found in association with an alkaline phosphatase (ALPase)-positive osteoblastic layer lining the bone surface, but could also be localized in the ALPase-negative stromal tissues that border the tumor nodules. These stromal tissues were markedly positive for osteopontin, and contained a significant number of TRAPase-positive osteoclasts expressing immunoreactivity for CD44. We thus speculated that, mediating its affinity for CD44, osteopontin may serve to facilitate osteoclastic migration after their formation associated with ALPase-positive osteoblasts. We next examined the localization of cathepsin K and matrix metallo-proteinase-9 (MMP-9) in osteoclasts. Osteoclasts adjacent to the bone surfaces were positive for both proteins, whereas those in the stromal tissues in the tumor nests showed only MMP-9 immunoreactivity. Immunoelectron microscopy disclosed the presence of MMP-9 in the Golgi apparatus and in vesicular structures at the baso-lateral cytoplasmic region of the osteoclasts found in the stromal tissue. MMP-9-positive vesicular structures also contained fragmented extracellular materials. Thus, osteoclasts appear to either select an optimized function, namely secreting proteolytic enzymes from ruffled borders during bone resorption, or recognize the surrounding extracellular matrix by mediating osteopontin/CD44 interaction, and internalize the extracellular matrices. Microsc.
authors.affiliation: Division of Oral Anatomy, Niigata University Graduate School of Medical and Dental Sciences, Niigata, 951-8514, Japan.
authors.forename: Minqi
authors.initials: M
authors.lastname: Li
authors.forename: Norio
authors.initials: N
authors.lastname: Amizuka
authors.forename: Kiichi
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Paulo H L
authors.initials: PH
authors.lastname: Freitas
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Kawano
authors.forename: Masaaki
authors.initials: M
authors.lastname: Hoshino
authors.forename: Kimimitsu
authors.initials: K
authors.lastname: Oda
authors.forename: Kayoko
authors.initials: K
authors.lastname: Nozawa-Inoue
authors.forename: Takeyasu
authors.initials: T
authors.lastname: Maeda
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D001859:Bone Neoplasms / Q000556:secondary*; D018288:Carcinoma, Small Cell / Q000473:pathology / Q000556:secondary*; D056657:Cathepsin K; D002403:Cathepsins / Q000032:analysis; D022162:Cytoplasmic Vesicles / Q000737:chemistry; D004195:Disease Models, Animal; D005109:Extracellular Matrix / Q000378:metabolism*; D005269:Femur / Q000473:pathology; D006056:Golgi Apparatus / Q000737:chemistry; D006801:Humans; D018960:Hyaluronan Receptors / Q000032:analysis; D007150:Immunohistochemistry; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000032:analysis; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016253:Microscopy, Immunoelectron; D010010:Osteoclasts / Q000378:metabolism*; D010014:Osteolysis / Q000378:metabolism / Q000473:pathology*; D053495:Osteopontin; D012795:Sialoglycoproteins / Q000032:analysis; D013977:Tibia / Q000473:pathology
chemical_list: D018960:Hyaluronan Receptors; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; D053495:Osteopontin; D000135:Acid Phosphatase; D002403:Cathepsins; C534130:CTSK protein, human; D056657:Cathepsin K; C534132:Ctsk protein, mouse; D020780:Matrix Metalloproteinase 9