Functional characterization of 2q22.1 deletion in oral squamous cell carcinoma

项目摘要/摘要 口腔鳞状细胞癌(OSCC)影响全球约350,000名患者。主要原因 OSCC的致病因素包括吸烟、饮用酒精饮料和感染高危人群 乳头瘤病毒(HPV)。目前，为患者提供的治疗方式主要包括手术、放射治疗、 化疗和免疫治疗。尽管有现有的临床干预措施，但这种疾病的死亡率 保持在20%左右，对于级别较高的肿瘤来说更大。口腔鳞状细胞癌的遗传异质性 具有很高的点突变和体细胞拷贝数变异(CNV)。类似的CNV模式有 通常见于其他鳞状细胞癌，如肺、宫颈和 食管。CNV也有很高的倾向与肿瘤的失活突变共存 抑制基因。然而，尽管有发现记录了各种基因组座位的存在，但 拷贝数改变，这些CNV在口腔鳞癌发生中的作用机制尚未得到证实 下定决心。口腔鳞状细胞癌早期和最常见的基因改变包括肿瘤抑制基因的丢失 CDKN2A(位于9p)和TP53突变(位于17p)。此外，世界上最大的 口腔鳞癌肿瘤中常见的缺失部位位于2q22.1。此删除操作完全包含在 低密度脂蛋白受体相关蛋白1B基因LRP1B被认为是一种肿瘤 在其他癌症中是抑制者，但在口腔鳞癌中尚未表现出特征。尽管在这个位置发生了缺失 这种基因中的点突变失活并不常见，这种情况比人们预料的要频繁得多。 此外，LRP1B在口腔角质形成细胞中不表达，这提出了一个问题，即为什么该基因座的缺失 尽管缺乏基因表达，但发生的频率如此之高。这表明这些删除是通过 独立于干扰LRP1B功能的机制。因此，我假设染色体 2q22.1上的缺失通过基因内元件的改变在口腔鳞癌进展中起驱动事件的作用 在肿瘤抑制中的作用。这项提议将通过三个具体目标解决我的假设：1)确定 2q22.1染色体缺失对角质形成细胞体外致瘤行为的影响 2q22.1缺失下游导致肿瘤行为的机制，以及3)识别最小的 负责观察到的表型变化的临界区。这些目标将通过使用 结合生化和分子生物学技术在患者样本中观察到的缺失 野生型角质形成细胞，并评估它们在肿瘤形成行为中的作用。这次调查的结果 将用于开发新的治疗应用，以抑制口腔鳞癌和潜在的各种 起源于鳞状上皮的其他癌症。

PROJECT SUMMARY/ABSTRACT Oral squamous cell carcinoma (OSCC) affects approximately 350,000 patients worldwide. The primary causes of OSCC include smoking, consumption of alcoholic beverages, and infections with high-risk human papillomaviruses (HPV). Currently, the main therapeutic modalities offered to patients include surgery, radiation, chemotherapy, and immunotherapy. Despite the existing clinical interventions, the mortality for this disease remains approximately 20% and is greater for higher grade tumors. OSCC tumors are genetically heterogenous with a high rate of point mutations and somatic copy number variations (CNVs). Similar CNV patterns are commonly observed in other squamous cell carcinomas such as those arising from the lung, cervix, and esophagus. The CNVs also have a high propensity for co-occurring with inactivating mutations of tumor suppressor genes. However, despite discoveries documenting the presence of various genomic loci undergoing copy number alterations, the mechanistic contributions of these CNVs to OSCC carcinogenesis have yet to be determined. The early and most frequent genetic alterations in OSCC include loss of tumor suppressors CDKN2A (residing at 9p) in conjunction with mutations in TP53 (residing at 17p). Additionally, one of the most commonly deleted sites within OSCC tumors is located at 2q22.1. This deletion is entirely contained within the low-density lipoprotein receptor-related protein 1B gene, LRP1B, which has been implicated as a tumor suppressor in other cancers but has not been characterized in OSCC. Although deletions at this locus occur more frequently than would be expected by chance, inactivating point mutations within this gene are not common. Moreover, LRP1B is not expressed in oral keratinocytes, raising the question as to why the deletions at this locus occur at such a high frequency, despite the lack of gene expression. This suggests these deletions act by a mechanism that is independent of interfering with LRP1B function. Therefore, I hypothesize that chromosomal deletions at 2q22.1 act as driver events in OSCC progression via alteration of intragenic elements that function in tumor suppression. This proposal will address my hypothesis via three specific aims: 1) Determine the impact of 2q22.1 chromosomal deletions on the tumorigenic behavior of keratinocytes in vitro, 2) Identify mechanisms downstream of 2q22.1 deletion responsible for tumorigenic behavior, and 3) Identify the minimal critical region responsible for the observed phenotypic changes. These aims will be achieved utilizing a combination of biochemical and molecular biology techniques to create the deletions observed in patient samples in wild type keratinocytes and assess their contribution to tumorigenic behavior. Outcomes from this investigation will be used in the development of novel therapeutic applications for suppression of OSCC and potentially various other cancers that originate from the squamous epithelium.