Developing a zebrafish launchpad for CART technology

细胞毒性T淋巴细胞（ctl）是我们身体对抗癌症发展的最有效防御。在正确启动的情况下，ctl也可以攻击已建立的癌症。对于ctl来说，要摧毁它们的目标，它们必须表达一种抗原受体（所谓的t细胞受体或TCR）来识别癌细胞在MHC上表达的抗原。肿瘤可能并不总是表达抗原或可能以其他方式干扰ctl的启动。体外工程T细胞表达嵌合抗原受体（cart）代表了合成生物学的一个令人兴奋的应用，可以绕过天然ctl的局限性。CAR包括一个能够结合癌细胞表面抗原的细胞外抗原识别域（独立于MHC），融合到刺激ctl增殖和杀死靶细胞的信号分子的细胞内域（独立于辅助细胞的细胞因子刺激）。如果一个细胞谱系，比如黑素细胞的损耗是可以耐受的，那么靶向抗原甚至不需要针对癌细胞，尽管它应该是谱系限制的，以避免灾难性的器官损伤。另外，刺激和抑制受体的组合或在多个car上分配刺激信号（逻辑门控的例子）仍然可以允许相对选择性的细胞毒性反应。迄今为止，cart的临床成功仅限于几种癌症类型，特别是血液系统恶性肿瘤，但它是一种高度创新的方法，进展迅速。我们最近确定斑马鱼的黑色素瘤也受到T细胞的监视。这意味着斑马鱼的T细胞也能预防癌症。此外，t细胞信号通路的推定成分有显著的序列保守性。我们设想斑马鱼成为评估CART技术的多功能体内试管。利用高效的转基因工具和已建立的黑色素瘤模型，成功的候选人将致力于开发识别和选择性攻击黑色素瘤细胞的CART。

Cytotoxic T lymphocytes (CTLs) are our bodies' most potent defence against the development of cancer. With correct priming, CTLs can also be prompted to attack established cancers. For CTLs to destroy their targets, they must express an antigen receptor (so-called T-cell receptor or TCR) recognising an antigen expressed on MHC by cancer cells. Tumours may not always express antigens or may otherwise interfere with the priming of CTLs. T cells engineered ex vivo to express chimeric antigen receptors (CARTs) represent an exciting application of synthetic biology that can circumvent the limitations of natural CTLs. The CAR comprises an extracellular antigen recognition domain capable of binding a surface antigen on the cancer cell (independently of MHC), fused to intracellular domains of signalling molecules which stimulate CTLs to proliferate and kill target cells (independently of cytokine stimulation by helper cells). If depletion of a cell lineage, such as melanocytes, can be tolerated then the antigen targeted needn't even be specific to cancer cells although it should be lineage restricted to avoid catastrophic organ damage. Alternatively, combinations of stimulatory and inhibitory receptors or partitioning stimulatory signals over multiple CARs (examples of logical gating) can still permit a relatively selective cytotoxic response. To date, clinical success with CARTs has been limited to a few cancer types, notably haematological malignancies, but it is a highly innovative approach, progressing rapidly. We have recently determined that melanoma in zebrafish is also under surveillance by T cells. This implies that zebrafish T cells also provide protection against cancer. Furthermore, there is significant sequence conservation for putative components of T-cell signalling pathways. We envisage zebrafish becoming a versatile in vivo test-tube for evaluating CART technology. Using highly efficient transgenic tools and established melanoma models, the successful candidate will work toward developing CART that recognise and selectively attack melanoma cells.