胰岛因子1（ISL1）在非霍奇金淋巴瘤诊断中的作用及其分子机制研究

Non-Hodgkin's lymphoma (NHL) is a heterogeneous class of cancers displaying a diverse range of biological phenotypes, clinical behaviours and prognoses. Even though complete response rates of 40-50% with chemotherapy can be attained, a substantial proportion of patients relapse, resulting in 3-year overall survival rates of about 30%. High mortality in lymphoma is in part driven by the inherent genetic heterogeneity and instability of the tumour cells. Successful treatment of NHL will thus require generation new diagnostic molecular marker to identify accuratelly the malignancy and chemoresistance in NHL. Aberrant expression of Insulin enhancer binding protein-1 (ISL-1) has been recently found in some types of human cancers. However, how ISL-1 exerts the role in tumor development, to date, is not clear. In the previous study, we found aberrant expression of ISL-1 in 80% of human non-hodgkin lymphoma (NHL) samples we examined compared with that in normal lymph nodes or HL samples. The expression level of ISL-1 exhibited great heterogeneity, and was found to be positive correlation to the malignancy and chemoresistance in NHL. ISL1 facilitated the G1/S cell cycle transition of Raji, Jurkat and Ly3 cells, promoted proliferation rate in vitro and enhances xenografted lymphoma development in vivo of these cells. Further investigation revealed that ISL-1 was able to activate the c-Myc expression, c-Myc and ISL-1 also showed a positive feedback in NHL cells. ISL1 could also promote chemoresistance with the protein degradation of p53. Furthermore, the signaling inhibitors targeting JAK1-STAT3 or c-Jun N-terminal kinase (JNK) could inhibit ISL-1 expression in NHL cells.In the present study, we will to prove whether ISL1 will to be suitable to develop as a tumor signature to distinguish the malignancy and prognosis chemoresistance in NHL. Moreover, we hope to provide the evidences that ISL-1 is tightly linked to NHL proliferation and malignancy by promoting c-Myc transcription, to NHL anti-apoptosis and chemoresistance by increasing p53 degradation and its aberrant expression could be regulated by JAK1-STAT3 or JNK signaling activation. These results will suggest that targeting ISL-1 may offer a new promising approach for NHL therapy.

寻找能够前瞻性地鉴别非霍奇金淋巴瘤(NHL)恶性程度、预后和化疗敏感性差异的分子标志物一直是NHL基础和临床研究的核心目标之一。我们在预实验中发现胰岛因子1(ISL1)在80%的NHL中出现了异常表达。ISL1的表达强度还与NHL肿瘤恶性程度和化疗药物耐药性呈正相关。本课题将通过对临床标本的检测和细胞、动物模型的建立，探讨ISL1是否可以作为NHL诊断的生物标志分子，即能够用来鉴别肿瘤的恶性程度、预后和对化疗药物的敏感性差异。同时我们也将探讨在NHL细胞中，ISL1异常表达的分子机制以及其生物学功能与作为肿瘤标志物之间的内在关联：JNK和STAT3信号通路的激活可能导致了ISL1出现异常高表达，而ISL1促进细胞增殖、对抗化疗药物引起的细胞凋亡，是其作为肿瘤标志物发挥作用的分子机制。本课题的完成，可为NHL的辅助诊断和治疗提供新的生物标志分子，为NHL的靶向治疗提供新的线索。

寻找能够前瞻性地鉴别非霍奇金淋巴瘤(NHL)恶性程度、预后和化疗敏感性差异的分子标志物一直是NHL基础和临床研究的核心目标之一。我们首先通过收集临床病历资料，统计学分析以及免疫组化证实胰岛因子1(ISL1)在80%的NHL中出现了异常表达且其表达强度还与NHL肿瘤恶性程度、TNM分期和预后呈正相关。接着通过NOD/SCID鼠成瘤实验、以及在人NHL细胞系中，检测ISL1对细胞增殖率、细胞周期和克隆形成率的影响，发现ISL1可以促进肿瘤细胞的增殖。利用RT-PCR、western-blot、荧光素酶报告、凝胶阻滞（EMSA）、ChIP实验确定ISL1通过增强下游靶基因c-Myc的表达从而促进细胞增殖的调控方式。同时我们过表达ISL1或抑制内源性ISL1后，检测阿霉素和环磷酰胺对上述细胞杀伤能力的改变以及细胞的凋亡率变化，并在NOD/SCID鼠成瘤后进行验证，结果提示ISL1可能是通过抑制化疗药物引起的细胞凋亡来提高NHL肿瘤耐药性，机制是ISL1能够促进p53蛋白的降解而发挥上述抗凋亡作用。我们也探讨了NHL细胞中，ISL1异常表达的分子机制以及其生物学功能与作为肿瘤标志物之间的内在关联：在NHL中JNK和STAT3信号通路的异常激活导致ISL1出现异常高表达，在ISL1的启动子区存在p-STAT3/p-c-Jun/c-Myc/ISL-1转录激活性复合体，从而使ISL1形成了自身的正反馈调节环路，促进ISL-1表达增加。而ISL1促进细胞增殖、对抗化疗药物引起的细胞凋亡，是其作为肿瘤标志物发挥作用的分子机制。本课题的完成，可为NHL的辅助诊断和治疗提供新的生物标志分子，为NHL的靶向治疗提供新的线索。