Differential transmission of the molecular signature of RBSP3, LIMD1 and CDC25A in basal/ parabasal versus spinous of normal epithelium during head and neck tumorigenesis: A mechanistic study

Head and neck squamous cell carcinoma (HNSCC) is a global disease and mortality burden, necessitating the elucidation of its molecular progression for effective disease management. The study aims to understand the molecular profile of three candidate cell cycle regulatory genes, RBSP3, LIMD1 and CDC25A in the basal/ parabasal versus spinous layer of normal oral epithelium and during head and neck tumorigenesis. Immunohistochemical expression and promoter methylation was used to determine the molecular signature in normal oral epithelium. The mechanism of alteration transmission of this profile during tumorigenesis was then explored through additional deletion and mutation in HPV/ tobacco etiological groups, followed byclinico-pathological correlation. In basal/parabasal layer, the molecular signature of the genes was low protein expression/ high promoter methylation of RBSP3, high expression/ low methylation of LIMD1 and high expression of CDC25A. Dysplastic epithelium maintained the signature of RBSP3 through high methylation/ additional deletion with loss of the signatures of LIMD1 and CDC25A via deletion/ additional methylation. Similarly, maintenance and / or loss of signature in invasive tumors was by recurrent deletion/ methylation. Thus, differential patterns of alteration of the genes might be pre-requisite for the development of dysplastic and invasive lesions. Etiological factors played a key role in promoting genetic alterations and determining prognosis. Tobacco negative HNSCC patients had significantly lower alterations of LIMD1 and CDC25A, along with better survival among tobacco negative/ HPV positive patients. Our data suggests the necessity for perturbation of normal molecular profile of RBSP3, LIMD1 and CDC25A in conjunction with etiological factors for head and neck tumorigenesis, implying their diagnostic and prognostic significance.

头颈部鳞状细胞癌（Head and neck squamous cell carcinoma, HNSCC）是一类造成全球疾病负担与死亡负担的恶性肿瘤，阐明其分子进展机制对于实现有效的疾病管理至关重要。本研究旨在探究三个候选细胞周期调控基因RBSP3、LIMD1及CDC25A在正常口腔上皮的基底层/副基底层与棘层中的分子特征，以及其在头颈部肿瘤发生过程中的变化规律。研究通过免疫组化表达检测与启动子甲基化分析，明确了正常口腔上皮中的分子特征谱；随后针对人乳头瘤病毒（HPV）与烟草相关的病因学分组，通过额外的缺失与突变检测，探究了该特征谱在肿瘤发生过程中的改变传递机制，并开展了临床病理相关性分析。
在基底层/副基底层中，三个基因的分子特征谱表现为：RBSP3蛋白低表达、启动子高甲基化；LIMD1蛋白高表达、启动子低甲基化；CDC25A蛋白高表达。异型增生上皮通过高甲基化/额外缺失保留了RBSP3的特征谱，同时通过缺失/额外甲基化丢失了LIMD1与CDC25A的特征谱。类似地，侵袭性肿瘤中特征谱的维持或丢失，同样通过反复出现的缺失与甲基化改变实现。
由此可见，这些基因的差异化改变模式，或许是异型增生与侵袭性病变发生发展的先决条件。病因因素在促进遗传改变与决定患者预后方面发挥关键作用：无烟草接触史的HNSCC患者，其LIMD1与CDC25A的基因改变发生率显著更低；且在无烟草接触史、HPV阳性的患者中，生存率更佳。本研究数据表明，RBSP3、LIMD1及CDC25A的正常分子特征谱出现异常改变，并与病因因素共同作用可促进头颈部肿瘤的发生，这提示这三个基因具有重要的诊断与预后价值。