Oncofetal fibronectins in oral carcinomas:

Abstract

Different isoforms of fibronectin are derived from a single gene by alternative processing of the primary RNA transcript or by posttranslational modifications. We have previously demonstrated that an oncofetal fibronectin (FN) isoform derived by O‐glycosylation is highly associated with malignancy in breast and oral tumors. Another oncofetal FN isoform containing the ED‐B sequence is derived by alternative splicing, and FN containing ED‐B has been found to be a stromal marker of malignancies in various tissues. Here we report a comparative study by immunohistology of the distribution of the ED‐B‐containing isoform and the oncofetal FN isoform derived by O‐glycosylation, in oral squamous cell carcinomas, premalignant lesions, and normal oral mucosa. A selective expression of the ED‐B‐containing isoform was demonstrated in close relation to the invading carcinoma (38/38), whereas there was virtually no staining in submucosa underlying premalignant lesions (1/11) and normal epithelium (0/5). The ED‐B‐containing FN showed close co‐distribution and staining pattern with the oncofetal isoform derived by O‐glycosylation. These results demonstrate that accumulation of FN adjacent to oral carcinomas includes both the ED‐B‐containing isoform and the isoform derived by O‐glycosylation. Although both the change in primary structure and glycosylation of FN create conformational and immunologically detectable changes, the functional consequences in association with invasive carcinoma are poorly understood at present. Diagnostic implications especially of borderline lesions as well as evaluation of tumor aggresiveness may, however, be important.

Distribution of laminin and fibronectin isoforms in oral mucosa and oral squamous cell carcinoma

“…Mandel et al, 1994). In contrast to OSCC, breast and colon carcinomas display only focal oncofetal fibronectin deposits if at all Pujuguet et al, 1996).…”

“…Recent results have given rise to a new definition of laminin and fibronectin as molecule families (Mandel et al, 1994;Kosmehl et al, 1996). Laminin is a heterotrimeric molecule with an α, β and γ chain.…”

“…To our knowledge, a comparative study focusing on the modulation of the laminin chain pattern in fetal, normal adult, hyperproliferative, or dysplastic oral epithelium and in OSCC of different malignancy grade has not yet been conducted. Although an immunohistochemical study on the expression of so-called oncofetal fibronectins (ED-B and de novo glycosylated fibronectin) in relation to the formation of an invasive phenotype of neoplastic oral epithelium has already been published (Mandel et al, 1994), the source of the ED-B fibronectin within the carcinoma remains unclear.…”

EB-D fibronectin expression in squamous cell carcinoma of the head and neck

“…Furthermore, the generation of a mouse monoclonal antibody, BC-1, which proved to be a reliable and an easy tool to handle, has encouraged many to use it in clinical studies. 11,15,22 Thus, the aim of our work is to determine the value of this protein in patients with HNSCC.…”

“…However, studies have shown almost similar staining results using three different, 5C10, FD-6 and BC1, monoclonal antibodies. 15,16 ED-B FN, also designated as oncofetal FN, due to its presence in fetal and tumor tissues but not in their normal counterparts. 17 Using IHC technique, numerous works have shown its expression in normal proliferative endometrium, chronic inflammatory diseases and ocular angiogenesis.…”