CD109 is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein whose expression is up-regulated in squamous cell carcinomas (SCCs) of the lung, esophagus, and uterus. The purpose of this study was to evaluate CD109 expression in oral tumors, including premalignant lesions, and to assess the clinical application of CD109 in oral cancer. CD109 expression in oral normal and tumor tissues from 124 patients was examined by immunohistochemical staining with anti-CD109 antibody, and significant relations between clinical features and CD109 expression were statistically assessed. We found that high levels of CD109 expression were frequently detected in SCCs and premalignant lesions of the oral cavity, but not in normal squamous epithelia. The CD109 expression level was higher in well-differentiated SCCs than in poorly differentiated SCCs. Furthermore, premalignant lesions highly expressing CD109 showed higher risk to progress to SCCs. Oral SCC cell lines overexpressing CD109 exhibited accelerated cell growth in vitro compared with control cell lines. In addition, overexpression of CD109 impaired the transforming growth factor (TGF)-b1-mediated suppression of cell growth. These findings suggest that CD109 plays a role in the development of oral cancers, and is a useful prognostic marker to predict malignant transformation of premalignant lesions. (Cancer Sci 2008; 99: 1916-1923 U p-regulation or down-regulation of the expression of some genes, including oncogenes and tumor suppressor genes, trigger the development of human tumors; the products of these genes are potentially good molecular targets for cancer diagnosis and treatment. In oral cancers, despite the ease of clinical examination, most cancer patients are diagnosed with advanced-stage cancer and are difficult to treat because of the anatomic location of the lesions or because the treatment would impact on the patients' quality of life. Therefore, early diagnosis of high-risk premalignant lesions is most important for good prognosis.CD109 is a glycosylphosphatidylinositol (GPI)-anchored cellsurface glycoprotein and is a member of the α2-macroglobulin-C3, C4, and C5 family of thioester-containing proteins.(1-3) The CD109 protein was first identified as a cell-surface antigen detected by a monoclonal antibody raised against the primitive lymphoid/ myeloid cell line KG1a.(1) It has been reported that CD109 is expressed on a subset of fetal and adult CD34 + bone marrow mononuclear cells, mesenchymal stem cell subsets, phytohemagglutinin (PHA)-activated T lymphoblasts, thrombin-activated platelets, leukemic megakaryoblasts, endothelial cells, and some human tumor cell lines, but not on fresh peripheral leukocytes and normal bone marrow leukocytes.(1,2,4,5) It was also shown that CD109 carries the biallelic platelet-specific alloantigen Gov, which is implicated in refractoriness to platelet transfusion, post-transfusion purpura, and neonatal alloimmune thrombocytopenia. We identified CD109 as a gene up-regulated in cells overexpressing oncogenic RET tyrosine kinas...

CD109 is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein, whose expression is upregulated in squamous cell carcinomas of the lung, esophagus, uterus and oral cavity. CD109 negatively regulates transforming growth factor (TGF)-b signaling in keratinocytes by directly modulating receptor activity. In this study, we further characterized CD109 regulation of TGF-b signaling and cell proliferation. We found that CD109 is produced as a 205 kDa glycoprotein, which is then processed in the Golgi apparatus into 180 kDa and 25 kDa proteins by furin (furinase). 180 kDa CD109 associated with GPI-anchored 25 kDa CD109 on the cell surface and was also secreted into the culture medium. To investigate whether furinase cleavage of CD109 is necessary for its biological activity, we mutated arginine 1273 in the CD109 furinase cleavage motif (amino acid 1270-RRRR-1273) to serine (R1273S). Interestingly, CD109 R1273S neither significantly impaired TGF-b signaling nor affected TGF-b-mediated suppression of cell growth, although it was expressed on the cell surface as a 205 kDa protein. Consistent with this finding, the 180 kDa and 25 kDa CD109 complex, but not CD109 R1273S, associated with the type I TGF-b receptor. These findings indicate that processing of CD109 into 180 kDa and 25 kDa proteins by furin, followed by complex formation with the type I TGF-b receptor is required for the regulation of TGF-b signaling in cancer cells and keratinocytes.

CD109, a glycosylphosphatidylinositol-anchored glycoprotein, is highly expressed in several types of human cancer tissues, in particular, squamous cell carcinomas. In normal human tissues, human CD109 expression is limited to certain cell types including myoepithelial cells of the mammary, lacrimal, salivary, and bronchial glands and basal cells of the prostate and bronchial epithelium. Although CD109 has been reported to negatively regulate transforming growth factor-β signaling in keratinocytes in vitro, its physiologic role in vivo remains largely unknown. To investigate the function of CD109 in vivo, we generated CD109-deficient (CD109(-/-)) mice. Although CD109(-/-) mice were born normally, transient impairment of hair growth was observed. At histologic analysis, kinked hair shafts, ectatic hair follicles with an accumulation of sebum, and persistent hyperplasia of the epidermis and sebaceous glands were observed in CD109(-/-) mice. Immunohistochemical analysis revealed thickening of the basal and suprabasal layers in the epidermis of CD109(-/-) mice, which is where endogenous CD109 is expressed in wild-type mice. Although CD109 was reported to negatively regulate transforming growth factor-β signaling, no significant difference in levels of Smad2 phosphorylation was observed in the epidermis between wild-type and CD109(-/-) mice. Instead, Stat3 phosphorylation levels were significantly elevated in the epidermis of CD109(-/-) mice compared with wild-type mice. These results suggest that CD109 regulates differentiation of keratinocytes via a signaling pathway involving Stat3.

CD109 is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein, which is a member of the a2-macroglobulin/ C3, C4, C5 family of thioester-containing proteins. It has been reported that CD109 is expressed in a subset of hematopoietic cells, endothelial cells and several kinds of human tumors. Herein it is reported that the CD109 protein is preferentially expressed in lung squamous cell carcinomas compared with other types of lung carcinoma including adenocarcinomas, large cell carcinomas and small cell carcinomas. Immunohistochemical staining of surgically resected lung specimens using an anti-CD109 antibody detected CD109 expression in basal cells of bronchial and bronchiolar epithelia and myoepithelial cells of bronchial secretary glands, but not in bronchial and bronchiolar apical epithelial cells and alveolar epithelial cells. Furthermore, the CD109 immunoreactivity was observed in squamous cell carcinomas at a high frequency compared with other types of lung carcinoma. Although the detailed function of CD109 protein is unclear, these results suggest that CD109 expression may play a role in the development of lung squamous cell carcinoma.

The CD109 gene encodes a glycosylphosphatidylinositol (GPI)-anchored cell surface protein. Herein it is shown that CD109 is highly expressed in myoepithelial cells of mammary, salivary, and lacrimal glands; and in prostate basal cells. The anti-CD109 antibody generated by the authors was available for formalin-fixed paraffin section, and it strongly stained myoepithelial cells and basal cells but not ductal, acinar, and secretory cells in these glands. CD109 expression was negative in examined breast ductal carcinomas and prostate adenocarcinomas. These findings indicate that CD109 is a useful marker for the diagnosis of invasive breast and prostate carcinomas.