Gene expression data of diagnostic childhood T-ALL samples and human thymocytes. Homo sapiens

Lymphotoxin-mediated activation of the lymphotoxin-β receptor (LTβR) has been implicated in several physiological and pathological processes, including lymphoid organ development, T-cell maturation, and solid and hematopoietic malignancies. Its role in T-cell acute lymphoblastic leukemia (T-ALL) or other T-cell malignancies has remained however to be investigated. Here we show that the genes encoding lymphotoxin (LT)-α and LTβ were expressed in T-ALL patient samples, more abundantly in the TAL/LMO molecular subtype, and in the TEL-JAK2 mouse model of cortical/mature T-ALL. Surface LTα1β2 protein was detected in primary mouse T-ALL cells, but only upon phorbol ester stimulation or absence of microenvironmental LTβR interaction. Indeed, in contrast to leukemic cells collected from transplanted Ltbr–/– mice or from co-cultures with Ltbr–/– mouse embryonic fibroblasts (MEF), those collected from Ltbr+/+ mice or from Ltbr+/+ MEF co-cultures presented no surface LT expression. Supporting the notion that LT signaling plays a role in T-ALL, inactivation of the Ltbr gene in mice resulted in a statistically significant delay in TEL-JAK2-induced leukemia onset. Expression of the Lta and Ltb genes was found to be increased at the early asymtptomatic stages of TEL-JAK2 T-ALL, when only low proportions of malignant thymocytes are present in normal sized thymus. Interestingly, young asymptomatic TEL-JAK2;Ltbr–/– mice presented significantly less leukemic thymocytes than TEL-JAK2;Ltbr+/+ mice. Together, these data indicate that early lymphotoxin expression by T-ALL cells activates LTβR signaling in thymic stromal cells, thus promoting leukemogenesis. Overall design: Primary T-ALL samples were obtained at diagnosis from bone marrow and/or peripheral blood with high leukemia involvement (>85%), and enriched by density centrifugation over Ficoll-Paque (GE Healthcare). Microarray analysis were performed on samples from patients with newly diagnosed T-ALL accrued from 2000 to 2013 at Centro Infantil Boldrini, Campinas, Brazil. Thymic samples, obtained from children undergoing cardiac surgery, were gently minced in culture medium and subsequently subjected to density centrifugation.

淋巴毒素介导的淋巴毒素β受体（LTβR）激活已被证实参与多种生理及病理过程，包括淋巴器官发育、T细胞成熟，以及实体瘤和造血系统恶性肿瘤。然而其在T细胞急性淋巴细胞白血病（T-ALL）或其他T细胞恶性肿瘤中的作用仍有待研究。本研究证实，编码淋巴毒素（LT）-α与LTβ的基因在T-ALL患者样本中存在表达，且在TAL/LMO分子亚型以及皮质/成熟T-ALL的TEL-JAK2小鼠模型中表达更为丰富。在原代小鼠T-ALL细胞中可检测到表面LTα1β2蛋白，但仅在佛波酯刺激或缺乏微环境LTβR相互作用的情况下才可检出。确实，与从Ltbr–/–小鼠移植获得的白血病细胞，或与Ltbr–/–小鼠胚胎成纤维细胞（MEF）共培养得到的白血病细胞不同，从Ltbr+/+小鼠或与Ltbr+/+ MEF共培养得到的白血病细胞无表面LT表达。为支持LT信号通路在T-ALL中发挥作用这一观点，小鼠中Ltbr基因的缺失可显著延迟TEL-JAK2诱导的白血病发病时间。研究发现，在TEL-JAK2 T-ALL的早期无症状阶段——此时正常大小的胸腺中仅存在低比例的恶性胸腺细胞——Lta与Ltb基因的表达水平升高。有趣的是，年轻无症状的TEL-JAK2;Ltbr–/–小鼠的白血病胸腺细胞数量显著低于TEL-JAK2;Ltbr+/+小鼠。综上，本研究数据表明，T-ALL细胞早期表达的淋巴毒素可激活胸腺基质细胞中的LTβR信号通路，从而促进白血病发生。整体实验设计：原代T-ALL样本采集自巴西坎皮纳斯市Centro Infantil Boldrini在2000年至2013年间招募的新诊断T-ALL患者，均为骨髓和/或外周血白血病浸润比例>85%的病例，经聚蔗糖-泛影葡胺（Ficoll-Paque，GE Healthcare）密度梯度离心富集后进行基因芯片分析。此外，从接受心脏手术的儿童体内获取胸腺样本，将其轻柔剪碎置于培养基中后，同样经密度梯度离心处理。