Activating mutations in ALK provide a therapeutic target in neuroblastoma

Top Cited Papers
Open Access
Publisher Website
Google Scholar
Abstract
Neuroblastoma is the most common childhood cancer. There is a strong familial association and it was predicted over 30 years ago that there was a genetic element to the disease. Four groups now report the identification of mutations in the tyrosine kinase receptor ALK (anaplastic lymphoma kinase) in neuroblastoma patients. ALK acts as a neuroblastoma predisposition gene, and somatic point mutations occur in sporadic neuroblastoma cases. These mutations promote ALK's kinase activity and can transform cells and display tumorigenic activity in vivo. ALK inhibitors decrease neuroblastoma cell proliferation, so have potential as anticancer drugs. This is one of four papers in this issue that identifies mutations in the tyrosine kinase receptor ALK in neuroblastoma, the most frequent childhood cancer. ALK is found to be a neuroblastoma predisposition gene and somatic points mutations were found in sporadic cases of neuroblastoma. These mutations lead the ALK kinase activation and are able to transform cells and display tumourigenic activity in vivo. ALK inhibitors decrease neuroblastoma cell proliferating and are potential anti-cancer drugs for the treatment of neuroblastoma. Neuroblastoma, an embryonal tumour of the peripheral sympathetic nervous system, accounts for approximately 15% of all deaths due to childhood cancer1. High-risk neuroblastomas are rapidly progressive; even with intensive myeloablative chemotherapy, relapse is common and almost uniformly fatal2,3. Here we report the detection of previously unknown mutations in the ALK gene, which encodes a receptor tyrosine kinase, in 8% of primary neuroblastomas. Five non-synonymous sequence variations were identified in the kinase domain of ALK, of which three were somatic and two were germ line. The most frequent mutation, F1174L, was also identified in three different neuroblastoma cell lines. ALK complementary DNAs encoding the F1174L and R1275Q variants, but not the wild-type ALK cDNA, transformed interleukin-3-dependent murine haematopoietic Ba/F3 cells to cytokine-independent growth. Ba/F3 cells expressing these mutations were sensitive to the small-molecule inhibitor of ALK, TAE684 (ref. 4). Furthermore, two human neuroblastoma cell lines harbouring the F1174L mutation were also sensitive to the inhibitor. Cytotoxicity was associated with increased amounts of apoptosis as measured by TdT-mediated dUTP nick end labelling (TUNEL). Short hairpin RNA (shRNA)-mediated knockdown of ALK expression in neuroblastoma cell lines with the F1174L mutation also resulted in apoptosis and impaired cell proliferation. Thus, activating alleles of the ALK receptor tyrosine kinase are present in primary neuroblastoma tumours and in established neuroblastoma cell lines, and confer sensitivity to ALK inhibition with small molecules, providing a molecular rationale for targeted therapy of this disease.