MATRIX REMODELING IN ORAL SQUAMOUS CELL CARCINOMA

鳞状细胞癌（SCC）是一种高度转移的病变，约占所有口腔癌的96%。肿瘤转移需要与细胞外基质（ECM）多种相互作用，包括细胞迁移、侵袭和基质重塑。我们的研究小组发现，ECM分子tenascin-C （TN-C）及其整合素受体alphavbeta6在口腔SCC中有新表达。TN-C是一种含有抗粘附结构域的六聚糖蛋白，据报道可促进细胞运动。据报道，阿尔法整合素亚家族也介导细胞运动。因此，TN-C和alphavbeta6的共表达为肿瘤细胞的侵袭提供了一个允许的环境。最近，其他研究表明，在一些肿瘤细胞表面发现的一种跨膜分子，细胞外基质金属蛋白酶诱导剂（EMMPRIN），可以刺激肿瘤周围成纤维细胞分泌基质金属蛋白酶（MMP）。使用人体活检标本，我们观察到与正常口腔黏膜相比，口腔发育不良和口腔鳞状细胞癌中EMMPRIN的染色增加。我们还发现了EMMPRIN作为TN-C基质沉积调制器的新作用。在EMMPRIN抗体存在的情况下，SCC细胞和瘤周成纤维细胞共培养的TN-C基质沉积被抑制，其潜在形式的MMP-2和MMP-9的分泌增加。抗emmprin抗体也会干扰体外口腔SCC细胞的运动。我们假设TN-C、EMMPRIN和alphavbeta6通过作为肿瘤细胞侵袭和基因表达的相互依赖的刺激调节剂影响口腔癌。具体目标1和2已在获资助的R-29DE11930-02A拨款中提出，并应按原建议在5年内完成。新的具体目标（黑体字）表示在第6年和第7年要做的额外工作。本提案的具体目的是：(1)确定alphavbeta6表达的改变是否会改变口腔SCC细胞的侵袭行为。(2)利用动物模型评价肿瘤侵袭不同阶段TN-C和alphabeta6的表达差异。(3)通过测定抗EMMPRIN抗体对可能与TN-C相互作用的MMPs的影响，探讨EMMPRIN在TN-C基质沉积中的作用。(4)评价过表达EMMPRIN对低侵袭性口腔SCC细胞的影响。这些实验将有助于我们了解口腔癌中ECM重塑的机制。

Squamous cell carcinoma (SCC), a highly metastatic lesion, accounts for approximately 96 percent of all oral cancers. Tumor metastasis requires multiple interactions with the extracellular matrix (ECM), including cell migration, invasion and matrix remodeling. Our group has shown that the ECM molecule tenascin-C (TN-C) and its integrin receptor, alphavbeta6, are neo-expressed in oral SCC. TN-C, a hexameric glycoprotein containing antiadhesive domains, reportedly promotes cell motility. The alphav integrin subfamily has also been reported to mediate cell motility. Coexpression of TN-C and alphavbeta6 thus provides a permissive environment for tumor cell invasion. Recently, others showed that a transmembrane molecule found on the surface of some tumor cells, extracellular matrix metalloproteinase inducer (EMMPRIN), stimulates matrix metalloproteinase (MMP) secretion by peritumor fibroblasts. Using human biopsy specimens, we observed an increase in staining for EMMPRIN in both oral dysplasia and oral SCC when compared with normal oral mucosa. We also identified a novel role for EMMPRIN as a modulator of TN-C matrix deposition. In the presence of antibodies to EMMPRIN, the deposition of TN-C matrices by cocultures of SCC cells and peritumor fibroblasts was inhibited, and their secretion of the latent forms of both MMP-2 and MMP-9 was increased. Anti-EMMPRIN antibodies also perturbed oral SCC cell motility in vitro. We hypothesize that TN-C, EMMPRIN, and alphavbeta6 influence oral cancer by acting as interdependent stimulatory modulators of tumor cell invasion and gene expression. Specific aims 1 and 2 were put forth in the funded R-29DE11930-02A grant and should be completed within the 5 years as originally proposed. The new specific aims (boldface) represent additional work to be done in years 6 and 7. The specific aims of this proposal are: (1) To determine whether alterations in the expression of alphavbeta6 will modify the invasive behavior of oral SCC cells. (2) To evaluate different stages of tumor invasion, using an animal model, for differential expression of TN-C and alphabeta6. (3) To investigate EMMPRIN's role in TN-C matrix deposition by determining the effects of anti-EMMPRIN antibodies on MMPs that may interact with TN-C. (4) To evaluate the effects of overexpressing EMMPRIN in poorly invasive oral SCC cells. These experiments should help us understand the mechanisms underlying ECM remodeling in oral cancer.