RESUMO
Most malignant neoplasms of the oral cavity are oral squamous cell carcinoma (OSCC), which is a type of highly malignant tumor with a propensity for forming distant metastases. Trophoblast cell surface antigen 2 (TROP2) is a transmembrane protein that is overexpressed in several types of tumor cells, although its role and regulatory mechanism in OSCC have not been determined. The aim of the present study was to examine the effects of TROP2 in human OSCC cell lines. The present study demonstrated that TROP2 protein expression was upregulated in OSCC cell lines. Transfection of short hairpin RNA (shRNA) targeting TROP2 (shTROP2) reduced cell proliferation, migration and invasion of OSCC cell lines, whereas overexpression of TROP2 increased proliferation, migration and invasion. shTROP2 transfection in OSCC cell lines inhibited tumor growth in OSCC mouse models. Furthermore, TROP2 expression activated the phosphoinositide 3kinase (PI3K)/Akt signaling pathway in human OSCC cells. These results suggest that TROP2 induces cell growth, migration and invasion through activation of the PI3K/Akt signaling pathway in OSCC cells.
Assuntos
Antígenos de Neoplasias/genética , Carcinoma de Células Escamosas/genética , Moléculas de Adesão Celular/genética , Proliferação de Células/genética , Neoplasias Bucais/genética , Animais , Apoptose/genética , Carcinoma de Células Escamosas/patologia , Moléculas de Adesão Celular/antagonistas & inibidores , Linhagem Celular Tumoral , Movimento Celular/genética , Xenoenxertos , Humanos , Camundongos , Neoplasias Bucais/patologia , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Metástase Neoplásica , Proteína Oncogênica v-akt/genética , Fosfatidilinositol 3-Quinases/genética , RNA Interferente Pequeno/farmacologia , Transdução de Sinais/genéticaRESUMO
Inappropriate expression of the receptor tyrosine kinase Met and its ligand hepatocyte growth factor (HGF)/scatter factor (SF) is usually associated with an aggressive solid tumor phenotype (angiogenesis, invasiveness, and metastasis) and poor clinical prognosis. We report here the design and construction of a large, human naïve antigen-binding fragment (Fab) phage-display library with a diversity of 2.0 x 109, which allows rapid isolation of antigen-specific human antibody fragments. A Fab fragment specifically against Met (designated hFab-Met-1) was successively selected from this library by using biopanning on Met-transfected cell line S114. The specificity of hFab-Met-1 was characterized by immunoprecipitation, Western blotting, and flow cytometry. The results demonstrate that hFab-Met-1 reacts with the extracellular domain of Met in its native conformation. Moreover, functional analysis by Madine-Darby canine kidney cell scattering and urokinase-type plasminogen activator assays demonstrated that hFab-Met-1 is not an agonist to HGF/Met signaling compared with a murine intact monoclonal antibody (MAb) Met5. To confirm that hFab-Met-1 interacts with Met-expressing tumors in vivo, I-125-labeled hFab-Met-1 was nuclear-imaged in a mouse xenograft of Met- and HGF/SF-expressing human leiomyosarcoma. Total body scintigrams were obtained between 1 and 48 h postinjection (PI). Tumor-associated activity was imaged as early as 1 h PI, and remained visible in some animals as late as 24 h PI. As expected, activity was highest in the kidneys in early images, whereas thyroid activity became predominant in later images. In conclusion, hFab-Met-1 interacts with Met both in vitro and in vivo, and is a promising candidate for clinical diagnosis and therapeutics.