transforming-growth-factor-beta and Pharyngeal-Neoplasms

Podoplanin, a transmembrane sialomucin-like glycoprotein, is known to express at high frequency in oral squamous cell carcinomas (OSCC) and possess metastasis-promoting activity such as increased invasion and platelet-aggregating activity. However, the regulatory mechanism of podoplanin expression in OSCC remains unknown.. In the present study, we investigated the podoplanin expression in both clinical specimens from total 80 patients (50 OSCC and 30 pharyngeal SCC) and in 4 OSCC cell lines in vitro.. Immunohistochemical analysis of surgically resected specimens of OSCC revealed podoplanin expression in 70% of OSCC cases with localization primarily in the basal layer of squamous cancer nest and the expression was inversely correlated with squamous cell differentiation. In vitro analysis of OSCC cell lines revealed 36 that podoplanin expression was decreased in response to the squamous cell differentiation (Cytokeratin 10 expression as a marker) induced by treatment with histone deacetylase (HDAC) inhibitors such as sodium butyrate and trichostatin. Furthermore, transforming growth factor-β (TGF-β) significantly enhanced podoplanin expression in OSCC cell lines in line with increased phosphorylation of Smad2. A TGF-β type I receptor inhibitor (SB431542) significantly inhibited such induction of podoplanin expression by TGF-β at both the protein and mRNA level. However, in a subset of OSCC cell line, its expression was only weakly dependent on TGF-β and squamous differentiation.. These results suggest that regulation of podoplanin is not simple, but in the majority of OSCC cell lines, its expression is positively and negatively regulated by TGF-β receptor/Smad signaling pathway and epigenetic mechanism leading to squamous differentiation, respectively.

Topics: Adult; Aged; Aged, 80 and over; Animals; Benzamides; Biomarkers, Tumor; Butyrates; Carcinoma, Squamous Cell; Cell Differentiation; Cell Line, Tumor; Dioxoles; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Immunohistochemistry; Keratin-10; Lymphatic Metastasis; Male; Membrane Glycoproteins; Mice; Mice, Nude; Middle Aged; Mouth Neoplasms; Neoplasm Invasiveness; Pharyngeal Neoplasms; Signal Transduction; Smad2 Protein; Tongue Neoplasms; Transforming Growth Factor beta

The alpha(v)beta(6) integrin is up-regulated on epithelial malignancies and has been implicated in various aspects of cancer progression. Immunohistochemical analysis of alpha(v)beta(6) expression in 10 human tumor types showed increased expression relative to normal tissues. Squamous carcinomas of the cervix, skin, esophagus, and head and neck exhibited the highest frequency of expression, with positive immunostaining in 92% (n = 46), 84% (n = 49), 68% (n = 56), and 64% (n = 100) of cases, respectively. We studied the role of alpha(v)beta(6) in Detroit 562 human pharyngeal carcinoma cells in vitro and in vivo. Prominent alpha(v)beta(6) expression was detected on tumor xenografts at the tumor-stroma interface resembling the expression on human head and neck carcinomas. Nonetheless, coculturing cells in vitro with matrix proteins did not up-regulate alpha(v)beta(6) expression. Detroit 562 cells showed alpha(v)beta(6)-dependent adhesion and activation of transforming growth factor-beta (TGF-beta) that was inhibited >90% with an alpha(v)beta(6) blocking antibody, 6.3G9. Although both recombinant soluble TGF-beta receptor type-II (rsTGF-beta RII-Fc) and 6.3G9 inhibited TGF-beta-mediated Smad2/3 phosphorylation in vitro, there was no effect on proliferation. Conversely, in vivo, 6.3G9 and rsTGF-beta RII-Fc inhibited xenograft tumor growth by 50% (n = 10, P < 0.05) and >90% (n = 10, P < 0.001), respectively, suggesting a role for the microenvironment in this response. However, stromal collagen and smooth muscle actin content in xenograft sections were unchanged with treatments. Although further studies are required to consolidate in vitro and in vivo results and define the mechanisms of tumor inhibition by alpha(v)beta(6) antibodies, our findings support a role for alpha(v)beta(6) in human cancer and underscore the therapeutic potential of function blocking alpha(v)beta(6) antibodies.

Topics: Animals; Antibodies, Monoclonal; Carcinoma, Squamous Cell; Cell Proliferation; Cells, Cultured; Disease Progression; Female; Humans; Immunoglobulin Fc Fragments; Integrin alpha5; Mice; Mice, Nude; Mink; Pharyngeal Neoplasms; Protein Isoforms; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Recombinant Fusion Proteins; Signal Transduction; Smad Proteins; Transforming Growth Factor beta; Xenograft Model Antitumor Assays