ALK基因编码一种受体酪氨酸激酶(eceptor tyrosine kinase ,RTK),为跨膜蛋白,属于胰岛素受体超家族,在大脑发育与及特定的神经元中起重要作用。最初在间变性大细胞淋巴瘤(anaplastic large cell lymphoma, ALCL)发现ALK-NPM1融合蛋白,目前已在其它肿瘤中包括神经母细胞瘤和非小细胞肺癌,发现该基因出现突变、扩增或者重排,其中染色体重排最为常见,导致ALK与其他基因产生融合,包括ALK(2号染色体)/EML4(2号染色体),ALK / RANBP2(2号染色体),ALK /ATIC(2号染色体),ALK / TFG(3号染色体),ALK / NPM1(5号染色体),ALK / SQSTM1(5号染色体),ALK / KIF5B(10号染色体),ALK / CLTC(17号染色体),ALK / TPM4(19号染色体),和ALK / MSN(X染色体)。
EML4-ALK变异体2包括ALK激酶域(外显子20-29)与EML4外显子1-20的融合。变体2具有胞质分布,在NSCLC中约占EML4-ALK融合的10%。尽管特异性变异体的报道并不一致,但单例NSCLC对环唑天宁治疗有反应,并有一种来源不明的分化恶性肿瘤的报道。在体外,该变异体对TAE684和环唑替尼抑制ALK的敏感性高于EML4-ALK变异体1(E13;A20)、3A(E6;A20)和3B(E6ins33;A20)。据报道,该变异体在细胞中的稳定性不如其他变异体,可能是hsp90的客户蛋白。沿着这些线,变异体显示了对hsp90抑制的临床前敏感性。
EML4-ALK variant 2 consists of a fusion of the ALK kinase domain (exons 20-29) with EML4 exons 1-20. Variant 2 has cytoplasmic distribution and makes up ~10% of EML4-ALK fusions found in NSCLC,. Although the specific variant is not consistently reported, single cases demonstrating response to crizotinib treatment in NSCLC and a differentiated malignant neoplasm of unknown origin have been reported. In vitro, this variant has shown greater sensitivity to ALK inhibition with TAE684 and crizotinib than the EML4-ALK variants 1 (E13;A20), 3a (E6;A20) and 3b (E6ins33;A20). The variant was reported to be less stable in cells than other variants, and may be a client protein of Hsp90. Along these lines the variant has shown preclinical sensitivity to Hsp90 inhibition.
| Chr. | Start | Stop | Ref. s | Var. Bases |
| 2 | 42396490 | 42552694 | C | T |
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| ENST00000318522.5 | ||||
| Chr. | Start | Stop | Transcript |
| 2 | 29415640 | 29446394 | ENST00000389048.3 |