EFFECTS OF TOBACCO-INDUCED EPITHELIAL CANCERS MEDIATED BY STROMAL FIBROBLASTS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。吸烟会增加患口腔癌和呼吸道癌的风险。尽管香烟烟雾和无烟烟草提取物含有多种化合物，可诱导潜在的致癌突变，但人们对慢性烟草使用者肿瘤发生的机制知之甚少。在这里，我们研究无烟烟草提取物(STE)对人类皮肤和口腔成纤维细胞的影响。我们发现，STE以剂量依赖的方式增加细胞内的活性氧水平，氧化DNA损伤和DNA双链断裂。长期暴露于STE可诱导成纤维细胞发生类似衰老的生长停滞，并伴随着显著的分泌表型变化。利用STE暴露的成纤维细胞和永生化的非致瘤角质形成细胞(部分转化的上皮细胞)的共培养，我们进一步证明了STE修饰的成纤维细胞分泌的因子改变了部分转化的上皮细胞的增殖和侵袭能力，但不改变它们的正常上皮细胞。此外，STE暴露的成纤维细胞导致部分转化的上皮细胞失去E-钙粘素和ZO-1(细胞极化标志)以及总蛋白(角质化标志)的表达，这些变化表明上皮功能受损，通常与恶变有关。综上所述，我们的结果提示成纤维细胞可能通过促进上皮细胞的恶性转化间接促进烟草致癌。因此，烟草不仅可能引发诱变，还可能通过基质介导的致癌前组织微环境促进突变细胞的生长。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Tobacco use increases the risk of developing cancers of the oral cavity and respiratory tract. Although cigarette smoke and smokeless tobacco extract contain multiple compounds that can induce potentially oncogenic mutations, little is known about the mechanisms by which tumors develop in chronic tobacco users. Here, we examine the effects of smokeless tobacco extracts (STE) on human skin and oral fibroblasts. We show that STE elevated the levels of intracellular reactive oxygen, oxidative DNA damage and DNA double-strand breaks in a dose-dependent manner. Extended exposure to STE induced fibroblasts to undergo a senescence-like growth arrest, with striking accompanying changes in the secretory phenotype. Using co-cultures of STE-exposed fibroblasts and immortalized but non-tumorigenic keratinocytes (partially transformed epithelial cells), we further show that factors secreted by STE-modified fibroblasts alter the proliferation and invasiveness of partially transformed epithelial cells, but not their normal counterparts. In addition, STE-exposed fibroblasts caused partially transformed epithelial cells to lose expression of E-cadherin and ZO-1 (markers of cell polarization), as well as of involucrin (marker of keratinization), changes that are indicative of compromised epithelial function and commonly associated with malignant transformation. Together, our results suggest that fibroblasts may contribute to tobacco-induced carcinogenesis indirectly by promoting malignant transformation of epithelial cells. Thus, tobacco may not only initiate mutagenic changes, but also promote growth of mutant cells by creating procarcinogenic tissue microenvironment mediated by the stroma.