DataSheet_1_ATF5 promotes malignant T cell survival through the PI3K/AKT/mTOR pathway in cutaneous T cell lymphoma.pdf

BackgroundsCutaneous T cell lymphoma (CTCL) is a non-Hodgkin lymphoma characterized by skin infiltration of malignant T cells. The biological overlap between malignant T cells and their normal counterparts has brought obstacles in identifying tumor-specific features and mechanisms, limiting current knowledge of CTCL pathogenesis. Transcriptional dysregulation leading to abnormal gene expression profiles contributes to the initiation, progression and drug resistance of cancer. Therefore, we aimed to identify tumor-specific transcription factor underlying CTCL pathology.
MethodsWe analyzed and validated the differentially expressed genes (DEGs) in malignant T cells based on single-cell sequencing data. Clinical relevance was evaluated based on progression-free survival and time to next treatment. To determine the functional importance, lentivirus-mediated gene knockdown was conducted in two CTCL cell lines Myla and H9. Cell survival was assessed by examining cell viability, colony-forming ability, in-vivo tumor growth in xenograft models, apoptosis rate and cell-cycle distribution. RNA sequencing was employed to investigate the underlying mechanisms.
ResultsActivating transcription factor 5 (ATF5) was overexpressed in malignant T cells and positively correlated with poor treatment responses in CTCL patients. Mechanistically, ATF5 promoted the survival of malignant T cells partially through the PI3K/AKT/mTOR pathway, and imparted resistance to endoplasmic reticulum (ER) stress-induced apoptosis.
ConclusionsThese findings revealed the tumor-specific overexpression of the transcription factor ATF5 with its underlying mechanisms in promoting tumor survival in CTCL, providing new insight into the understanding of CTCL’s pathology.

背景
皮肤T细胞淋巴瘤（Cutaneous T cell lymphoma, CTCL）是一类以恶性T细胞皮肤浸润为特征的非霍奇金淋巴瘤。恶性T细胞与其正常同源细胞之间存在生物学重叠，这为识别肿瘤特异性特征与机制带来了阻碍，限制了当前对CTCL发病机制的认知。转录调控异常导致基因表达谱异常，在癌症的发生、进展及耐药性形成中发挥关键作用。因此，本研究旨在明确CTCL发病过程中潜在的肿瘤特异性转录因子。

方法
本研究基于单细胞测序数据分析并验证了恶性T细胞中的差异表达基因（differentially expressed genes, DEGs）。基于无进展生存期与至下一次治疗时间，评估了相关分子的临床相关性。为明确其功能重要性，本研究在两种CTCL细胞系Myla与H9中开展了慢病毒介导的基因敲低实验。通过检测细胞活力、集落形成能力、异种移植模型体内肿瘤生长情况、细胞凋亡率及细胞周期分布，对细胞存活情况进行评估。同时采用RNA测序技术探究其潜在作用机制。

结果
激活转录因子5（Activating transcription factor 5, ATF5）在恶性T细胞中呈高表达，且与CTCL患者的不良治疗反应呈正相关。机制上，ATF5可部分通过PI3K/AKT/mTOR通路促进恶性T细胞存活，并赋予细胞抵抗内质网（endoplasmic reticulum, ER）应激诱导的细胞凋亡的能力。

结论
本研究结果揭示了转录因子ATF5在CTCL中的肿瘤特异性高表达及其促进肿瘤存活的潜在机制，为深入理解CTCL的病理生理过程提供了新的研究视角。