RESUMO
It has recently been proposed that gastrointestinal stromal tumors (GISTs) originate from stem cells that differentiate toward a phenotype of interstitial cells of Cajal (ICCs). Nestin is a newly identified intermediate filament protein, and is predominantly expressed in immature cells, such as neuroectodermal stem cells and skeletal muscle progenitor cells, and tumors originating from these cells. In this study, we examined, using immunohistochemistry, the nestin expression in GISTs and ICCs to clarify the origin of GISTs. Strong immunoreactivity for nestin was observed in all 18 GISTs, and its expression was confirmed by Western blot and Northern blot analyses. In contrast, three leiomyomas and a schwannoma that developed in the gastrointestinal tract showed no apparent immunoreactivity for nestin. Among 17 mesenchymal tumors (seven leiomyosarcomas, five malignant peripheral nerve sheath tumors, and five fibrosarcomas) that occurred in sites other than the gastrointestinal tract, only two malignant peripheral nerve sheath tumors were moderately immunoreactive for nestin. Furthermore, with fluorescence double immunostaining of the normal small intestine, nestin expression was demonstrated in ICCs. These results show that nestin may be a useful marker for diagnosis of GISTs, and support the current hypothesis that GISTs are tumors of stem cells that differentiate toward an ICC phenotype.
Assuntos
Biomarcadores Tumorais/metabolismo , Neoplasias Gastrointestinais/metabolismo , Proteínas de Filamentos Intermediários/biossíntese , Intestino Delgado/metabolismo , Neoplasias de Tecido Conjuntivo/metabolismo , Proteínas do Tecido Nervoso , Adulto , Idoso , Biomarcadores Tumorais/genética , Feminino , Neoplasias Gastrointestinais/patologia , Expressão Gênica , Humanos , Imuno-Histoquímica , Proteínas de Filamentos Intermediários/genética , Proteínas de Filamentos Intermediários/imunologia , Intestino Delgado/patologia , Masculino , Pessoa de Meia-Idade , Nestina , RNA Mensageiro/biossínteseRESUMO
Tympanosclerosis is a condition leading to a calcification process in the middle ear, and often develops after chronic inflammation of the middle ear. Since osteopontin (OPN) has been shown to participate in the pathological calcification, we here investigated whether OPN is involved in the process of calcification in tympanosclerosis. The tympanic membrane and middle ear mucosa, obtained from patients of tympanosclerosis and chronic otitis media, were histologically classified depending on the calcification degree. In hyalinized tissues with macroscopic calcification and fibrous tissues with microscopic calcification, OPN was immunohistochemically found in the calcification sites. In inflammatory tissues with microscopic calcification, OPN was also found in the calcifying foci, and many OPN mRNA-expressing cells, determined by in situ hybridization, located around their foci. Moreover, immunohistochemical double staining of OPN and CD68 showed that the OPN-expressing cells were CD68-positive, indicating these cells were macrophages. In inflammatory tissues without calcification, immunohistochemistry of CD68 and in situ hybridization of OPN mRNA revealed that most OPN mRNA-expressing cells were CD68-positive. The expression of OPN mRNA in inflammatory tissues was also shown by reverse transcriptase polymerase chain reaction. These results suggest that OPN secreted by exudate macrophages might be an important regulator in the calcification of tympanosclerosis.
Assuntos
Orelha Média/metabolismo , Orelha Média/patologia , Macrófagos/metabolismo , Otite Média/metabolismo , Otite Média/patologia , Sialoglicoproteínas/genética , Sialoglicoproteínas/metabolismo , Adolescente , Adulto , Idoso , Sequência de Bases , Pré-Escolar , Primers do DNA/genética , Feminino , Expressão Gênica , Humanos , Hibridização In Situ , Masculino , Pessoa de Meia-Idade , Mucosa/metabolismo , Mucosa/patologia , Osteopontina , Otite Média/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Esclerose , Membrana Timpânica/metabolismo , Membrana Timpânica/patologiaRESUMO
Osteoprotegerin (OPG) and osteoclast differentiation factor (ODF) are crucial regulators of osteoclastogenesis. To determine the biological role of interleukin (IL)-18 produced by stromal/osteoblastic cells in osteoclastogenesis, we examined the effects of IL-18 on the OPG and ODF mRNA levels in these cells. When bone marrow stromal ST2 cells, osteoblastic MC3T3-E1 cells, and mouse calvarial osteoblasts were stimulated with IL-18, the expression of OPG mRNA, but not ODF mRNA, was transiently increased, its expression reaching a maximal level at 3 h after the beginning of the culture. In accordance with this observation, all these cells expressed the mRNAs of two IL-18 receptor components and MyD88, an adapter molecule involved in IL-18 signaling. Moreover, in these cells, mitogen-activated protein kinase was phosphorylated after stimulation with IL-18. These results suggest that stromal/osteoblastic cells are IL-18-responsive cells and that IL-18 may inhibit osteoclastogenesis by up-regulating OPG expression, without stimulation of ODF production, in stromal/osteoblastic cells.
