ROLE OF GKLF IN EPITHELIAL DYSPLASIA

描述：（改编自研究者摘要）隐性遗传 肿瘤抑制基因的改变经常激活野生型 型等位基因的转化癌基因的下游功能， 生化途径在正常上皮中，但在高度发育异常的 在上皮中，这些癌基因的表达仅限于特定的隔室。 GKLF是癌中的一种主要转化活性， 在复层鳞状上皮的分化细胞层中。在 发育不良上皮，表达大大增加，并存在于所有 细胞层，表明基底细胞层中的抑制可能丢失 在肿瘤进展的早期。GKLF表达持续上调 在口腔鳞状细胞癌的发展过程中， 原位杂交在三分之二的乳腺癌中的应用GKLF的强化表达 在转基因小鼠皮肤的基底细胞层中， 发育不良，包括顶部-基底极化丧失和角化过度。在 RK 3E上皮细胞，GKLF特异性抑制整合素的表达 基底膜成分胶原蛋白和层粘连蛋白的受体。表达 玻连蛋白/纤连蛋白受体组分aV的表达不受GKLF的抑制。 与这些结果一致，GKLF转化细胞表现出明显的 与胶原蛋白或层粘连蛋白的附着率降低，但保留或 增加与细胞外基质组分玻连蛋白的附着， 纤连蛋白。这些结果确定GKLF作为一个候选的决定因素， 通过调节整合素功能来调节发育异常表型。通过激活 GKLF的表达，肿瘤细胞可以获得正常的性质， 分化上皮细胞，释放基底膜的能力， 并附着到细胞外基质的其它成分上。在第一个目标中， 在这项提案中，Ruppert博士将描述GKLF转基因小鼠皮肤的特征， 在人类肿瘤病变中发现的分子改变，包括 整合素表达。在第二个目标中，他还将测试小鼠的 易患肿瘤形成，并使用诱导系统来测试 在异型增生上皮和肿瘤中下调GKLF的作用。在 第三个目标，他将使用RK 3E细胞进一步表征 通过GKLF调节整合素表达，并确定频率和 乳腺癌和口腔肿瘤中GKLF激活的时间。

DESCRIPTION: (Adapted from the investigator's abstract) Recessive genetic alterations in tumor suppressor genes frequently activate expression of wild type alleles of transforming oncogenes that function downstream in a biochemical pathway. In normal epithelium, but not in highly dysplastic epithelium, expression of these oncogenes is limited to specific compartments. GKLF is a major transforming activity in carcinomas that is normally expressed in the differentiating cell layers of stratified squamous epithelium. In dysplastic epithelium, expression is greatly increased and is present in all cell layers, suggesting that suppression in the basal cell layer may be lost early during tumor progression. GKLF expression is consistently upregulated during progression of oral squamous cell carcinoma, and is detected by mRNA in situ hybridization in two-thirds of breast cancers. Enforced expression of GKLF in the basal cell layer of transgenic mouse skin induces features of epithelium dysplasia, including loss of apical-basal polarization and hyperkeratosis. In RK3E epithelial cells, GKLF specifically inhibits expression of integrin receptors for the basement membrane components collagen and laminin. Expression of the vitronectin/fibronectin receptor component aV was not inhibited by GKLF. Consistent with these results, GKLF-transformed cells exhibited a markedly reduced rate of attachment to the collagen or laminin, but retained or increased attachment to the extracellular matrix components vitronectin and fibronectin. These results identify GKLF as a candidate determinant of the dysplastic phenotype through regulation of integrin function. By activating expression of GKLF, tumor cells may acquire a property of normal differentiating epithelial cells, the ability to release the basement membrane and attach to other components of the extracellular matrix. In the first aim of this proposal, Dr. Ruppert will characterize GKLF transgenic mouse skin for molecular alterations found in human neoplastic lesions, including loss of integrin expression. In the second aim, he will also test mice for predisposition to tumor formation, and use an inducible system to test the effects of downregulating GKLF in dysplastic epithelium and tumors. In the third aim he will use RK3E cells to further characterize the mechanism of regulation of integrin expression by GKLF, and to determine the frequency and timing of GKLF activation in breast cancers and oral tumors.