Genome-wide analysis of the formation and mutagenesis of atypical UV photoproducts in skin cancer

皮肤癌中非典型紫外线光产物的形成和诱变的全基因组分析

• 批准号: 10179949
• 负责人: STEVEN A ROBERTS
• 金额: $ 41.69万
• 依托单位: WASHINGTON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2026-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10179949
• 关键词: Acute; Adenine; BRAF gene; Bioinformatics; Bulla; Bypass; Cells; Characteristics; Cleaved cell; Clinical; Cutaneous Melanoma; Cytidine; Cytosine; DNA Damage; DNA biosynthesis; DNA-Directed DNA Polymerase; Data; Deamination; Deoxyribonuclease I; Dinucleoside Phosphates; Disease Progression; Epidemiology; Etiology; Exposure to; Genetic Transcription; Genome; Genomics; High-Throughput Nucleotide Sequencing; Human; In Vitro; Incidence; Induced Mutation; Lesion; Light; Link; Location; Maps; Methods; Molecular; Mutagenesis; Mutation; Nucleotide Excision Repair; Nucleotides; Oncogenic; Physiological; Play; Polymerase; Proto-Oncogenes; Pyrimidine Dimers; Rad30 protein; Rare Lesion; Recurrence; Reporter; Resolution; Role; Skin; Skin Cancer; Somatic Mutation; Sunburn; Sunlight; Thymine; UV Mutagenesis; UV Radiation Exposure; UV induced; UVA induced; Ultraviolet B Radiation; Ultraviolet Rays; Yeasts; base; density; driver mutation; experimental study; genome sequencing; genome-wide; genome-wide analysis; insight; melanoma; melanomagenesis; novel; regional difference; repaired; response; skin organogenesis; tumor; tumor progression; ultraviolet; ultraviolet damage; ultraviolet lesions; whole genome

Abstract: Exposure to solar ultraviolet (UV) light creates DNA damage that induces high levels of somatic mutations in human skin cancers like melanoma. UV light most commonly causes cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs) at dipyrimidine sequences (i.e., TT, TC, CT, and CC). Deamination of cytidines in these lesions or mutagenic bypass leads to their frequent conversion to mutations. As a result, UV- exposed cells and skin cancers are dominated by C to T and CC to TT substitutions in dipyrimidine sequences that collectively constitute a UV mutation signature. Surprisingly, many driver mutations that contribute to melanoma progression have sequence context and substitution characteristics that do not conform to the canonical UV mutation signature. For example, the most common melanoma driver mutation, BRAF V600E, involves a T to A substitution in a GTG sequence context. This difference in mutation characteristics between most UV-induced mutations and melanoma driver mutations has led to the hypothesis that UV light induces melanomagenesis by mechanisms other than the induction of mutations. However, we have recently provided experimental evidence of mutations caused by rare, non-canonical UV lesions in whole genome sequenced yeast and bioinformatics evidence of similar lesions in human clinical skin cancers. These lesions are likely bulky photoproducts formed at TA, CA, and AC dinucleotides. Strikingly, the mutations associated with these atypical UV photoproducts have identical characteristics to many recurrent driver mutations in melanoma, suggesting that these rare lesions may play a significant role in causing skin cancer. The objective of this proposal is to better define the characteristics of atypical UV photoproducts and their contribution to cancer progression. In Aim I, we will utilize CPD and 6-4PP photolyases expressed in yeast to assign UV-induced mutation classes to their corresponding lesion types as well as assess the ability of physiological UVB light to induce mutation classes associated with atypical UV photoproducts in yeast and human cells. In Aim II, we will analyze the genome-wide distribution of atypical TA photoproducts using a novel high throughput sequencing method, called UVDE-seq. We will also characterize the formation of putative CA and AC photoproducts and their contribution to oncogenic BRAF mutations. Finally, Aim III will identify DNA polymerases involved in the error-free and error-prone bypass of TA and AC photoproducts. Successful completion of these aims will provide new insights into the molecular causes of skin cancer, and thereby define a new paradigm of UV mutagenesis that could potentially explain the epidemiological association of acute UV exposure with increased melanoma incidence.

抽象的： 暴露于太阳紫外线 (UV) 光下会造成 DNA 损伤，从而诱发高水平的体细胞突变 人类皮肤癌，如黑色素瘤。紫外线最常引起环丁烷嘧啶二聚体 (CPD) 以及二嘧啶序列（即 TT、TC、CT 和 CC）处的 6-4 个光产物 (6-4PP)。脱氨作用 这些病变中的胞苷或诱变旁路导致它们频繁转化为突变。结果，紫外线 暴露的细胞和皮肤癌主要是二嘧啶序列中的 C 到 T 和 CC 到 TT 替换 共同构成了紫外线突变特征。令人惊讶的是，许多驱动突变导致 黑色素瘤进展具有不符合的序列背景和替代特征 典型的紫外线突变特征。例如，最常见的黑色素瘤驱动突变 BRAF V600E， 涉及 GTG 序列上下文中的 T 到 A 替换。这种突变特征的差异 大多数紫外线诱导的突变和黑色素瘤驱动突变导致了这样的假设：紫外线诱导突变 通过诱导突变以外的机制发生黑色素瘤。不过，我们最近提供了 全基因组测序中罕见的非典型紫外线损伤引起突变的实验证据 酵母和生物信息学证据表明人类临床皮肤癌中有类似病变。这些病变很可能 在 TA、CA 和 AC 二核苷酸处形成大量光产物。引人注目的是，与这些相关的突变 非典型紫外线光产物与黑色素瘤中许多反复出现的驱动突变具有相同的特征， 表明这些罕见病变可能在导致皮肤癌中发挥重要作用。此举的目的 该提案旨在更好地定义非典型紫外线光产品的特征及其对癌症的贡献 进展。在目标 I 中，我们将利用酵母中表达的 CPD 和 6-4PP 光裂合酶来分配 UV 诱导的 突变类别及其相应的病变类型，并评估生理 UVB 光的能力 诱导与酵母和人体细胞中非典型紫外线光产物相关的突变类别。在目标二中，我们将 使用新型高通量测序分析非典型 TA 光产物的全基因组分布 方法，称为 UVDE-seq。我们还将描述假定的 CA 和 AC 光产物的形成以及 他们对致癌 BRAF 突变的贡献。最后，Aim III 将鉴定参与 DNA 聚合酶 无错和易错绕过 TA 和 AC photoproducts。成功完成这些目标将 为皮肤癌的分子原因提供新的见解，从而定义紫外线的新范例 突变可能可能解释急性紫外线暴露与流行病学的关联 黑色素瘤发病率增加。