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)的多种相互作用，包括细胞迁移、侵袭和基质重塑。我们的研究小组发现，细胞外基质分子TN-C及其整合素受体αvbeta6在口腔鳞状细胞癌中有新的表达。TN-C是一种含有抗黏附结构域的六聚体糖蛋白，据报道它能促进细胞运动。据报道，αv整合素亚家族也参与了细胞运动的调节。因此，TN-C和αvbeta6的共同表达为肿瘤细胞的侵袭提供了允许的环境。最近，另有研究表明，一些肿瘤细胞表面的跨膜分子--细胞外基质金属蛋白酶诱导物(EMMPRIN)能刺激瘤周成纤维细胞分泌基质金属蛋白酶(MMP)。使用人类活检标本，我们观察到与正常口腔粘膜相比，EMMPRIN在口腔异型增生和口腔鳞癌中的染色增加。我们还确定了EMMPRIN作为TN-C基质沉积的调制器的新作用。在EMMPRIN抗体的存在下，SCC细胞和瘤周成纤维细胞共培养的TN-C基质沉积受到抑制，其分泌的潜伏型基质金属蛋白酶-2和基质金属蛋白酶-9增加。在体外，抗EMMPRIN抗体也干扰口腔鳞癌细胞的运动。我们假设TN-C、EMMPRIN和Alphavbeta6作为相互依赖的肿瘤细胞侵袭和基因表达的刺激调节因子影响口腔癌。具体目标1和2是在R-29DE11930-02a赠款中提出的，应在最初提议的5年内完成。新的具体目标(粗体)代表了在第6年和第7年要做的额外工作。这项提案的具体目标是：(1)确定alphavbeta6表达的变化是否会改变口腔SCC细胞的侵袭行为。(2)用动物模型评价肿瘤侵袭不同阶段TN-C和α-β6的差异表达。(3)通过检测抗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)探讨过表达EMMPRIN对低侵袭性口腔鳞癌细胞的影响。这些实验应该有助于我们理解口腔癌细胞外基质重塑的机制。

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.