Consequences and mechanism of aberrant splicing in African American prostate cancer disparities

摘要 在前列腺癌(PCA)风险和生存结果方面存在显著的人群(种族)差异 当前的健康统计数据。这在非洲裔美国人(AA)患者和他们的欧洲人之间尤为明显 美国(EA)同行，在那里，AA显示出1.5至2倍的PCa发病率和死亡率。我们 证明癌基因和肿瘤抑制基因发生了差异选择性的RNA剪接 在AA和EA患者的PCa标本中进行比较。差异剪接事件导致富集物和 在许多情况下，在EA癌症中没有观察到AA特异性剪接变体的产生。我们已经克隆了 磷脂酰肌醇-4，5-二磷酸3-激酶催化亚单位的AA和EA剪接变异体 (PIK3CD)和成纤维细胞生长因子受体3(FGFR3)，并分别异位导入克隆 转化成前列腺癌细胞系。与EA变异体表达系相比，AA变异体表达系数量较多 体外细胞增殖和侵袭试验中的致癌作用，并显示出更大的肿瘤生长/转移和 小分子靶向治疗在异种移植小鼠模型中的耐药性。这些发现可能部分解释了， 观察到再生障碍性贫血人群相对于其他种族群体的癌症健康差异。这一机制 负责形成AA特异性或富含mRNA的剪接变异体被假设是由于 6个关键剪接因子S在AA-PCa组织中的异常表达我们指的是这种监管失调和 相关的AA特异性剪接变异体的产生可以作为“PCA差异中的AA剪接因子编码”。 尽管取得了这些进展，但一些问题仍然没有得到解决。首先，什么是 6种剪接因子异常表达的机制(S)？第二，可以制作特定的AA 外显子跳跃导致的剪接变异体是否直接归因于6个剪接因子的失调？最后，如何 PIK3CD和FGFR3 AA特异性短变异体编码的蛋白介导更高的致癌性 前列腺癌细胞的表型？本应用程序的目标是解决这些问题，并提供 替代RNA剪接中与种群相关的差异的机制框架，预计将 促进将来识别可用药的靶标(例如，剪接因子和/或产生的剪接变异蛋白) AA肿瘤的表型和差异。

Summary There are striking population (race) disparities in prostate cancer (PCa) risk and survival outcome borne out of current health statistics. This is particularly evident between African American (AA) patients and their European American (EA) counterparts, where AAs exhibit a 1.5 to 2 fold higher risk of PCa incidence and mortality. We demonstrate that differential alternative RNA splicing takes place for oncogenes and tumor suppressor genes in PCa specimens of AA compared to EA patients. The differential splicing events result in the enrichment and in many instances generation of AA-specific splice variants not observed in EA cancers. We have cloned the AA and EA splice variant cDNAs for both phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta (PIK3CD) and fibroblast growth factor receptor 3 (FGFR3), and ectopically introduced the clones individually into PCa cell lines. Compared to the EA variant-expressing lines, the AA variant-expressing lines are more oncogenic in in vitro cell proliferation and invasion assays, and exhibit greater tumor growth/metastasis and resistance to small molecule targeted therapy in xenograft mouse models. These findings may explain, in part, the observed cancer health disparities in the AA population relative to other racial groups. The mechanism responsible for the formation of AA-specific or -enriched mRNA splice variants are hypothesized to be due to the dysregulated expression of 6 key splicing factor s in AA PCa specimens. We refer to this dysregulation and associated production of AA-specific splice variants as an “AA splicing factor code in PCa disparities.” Notwithstanding these developments, a number of questions remain unresolved. First, what is the mechanism(s) of dysregulated expression of the 6 splicing factors? Second, can the production of AA-specific splice variants via exon skipping be directly attributed to the 6 dysregulated splicing factors? Lastly, how do the encoded proteins of the AA-specific short variants of PIK3CD and FGFR3 mediate a more oncogenic phenotype in PCa cells? The objectives of this application are to address these questions, and to provide a mechanistic framework of population-related differences in alternative RNA splicing, which is anticipated to facilitate future identification of druggable targets (e.g. splicing factors and/or resulting splice variant proteins) of AA tumor phenotype and disparities.