專題：Nature報導
正常人類細胞含有來自雙親中每一方的全套染色體，但在某些癌症中，部分特定染色體的兩個版本都來自同一親代——該現象被稱為「獲得性單親二體」。對來自從患有髓樣腫瘤的患者取來的超過200份骨髓樣本的基因組DNA所做研究，發現11號染色體的一部分的兩個版本都遺傳自單親的發生率較高，該部分含有腫瘤抑制因子C-CBL的一個功能獲得性突變，它使成纖維細胞發生癌變，使造血幹細胞對細胞因子刺激更敏感。這些數據支持這樣一個觀點：c-Cbl是一個腫瘤抑制基因，癌症中所發生的突變能夠以功能獲得性方式發揮作用，正如以前對腫瘤抑制基因p53所發現的那樣。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 460, 904-908 (13 August 2009) | doi:10.1038/nature08240
Gain-of-function of mutated C-CBL tumour suppressor in myeloid neoplasms
Masashi Sanada1,5,19, Takahiro Suzuki7,19, Lee-Yung Shih8,19, Makoto Otsu9, Motohiro Kato1,2, Satoshi Yamazaki6, Azusa Tamura1, Hiroaki Honda11, Mamiko Sakata-Yanagimoto12, Keiki Kumano3, Hideaki Oda13, Tetsuya Yamagata14, Junko Takita1,2,3, Noriko Gotoh10, Kumi Nakazaki1,4, Norihiko Kawamata15, Masafumi Onodera16, Masaharu Nobuyoshi7, Yasuhide Hayashi17, Hiroshi Harada18, Mineo Kurokawa3,4, Shigeru Chiba12, Hiraku Mori18, Keiya Ozawa7, Mitsuhiro Omine18, Hisamaru Hirai3,4, Hiromitsu Nakauchi6,9, H. Phillip Koeffler15 & Seishi Ogawa1,5
Acquired uniparental disomy (aUPD) is a common feature of cancer genomes, leading to loss of heterozygosity. aUPD is associated not only with loss-of-function mutations of tumour suppressor genes1, but also with gain-of-function mutations of proto-oncogenes2. Here we show unique gain-of-function mutations of the C-CBL (also known as CBL) tumour suppressor that are tightly associated with aUPD of the 11q arm in myeloid neoplasms showing myeloproliferative features. The C-CBL proto-oncogene, a cellular homologue of v-Cbl, encodes an E3 ubiquitin ligase and negatively regulates signal transduction of tyrosine kinases3, 4, 5, 6. Homozygous C-CBL mutations were found in most 11q-aUPD-positive myeloid malignancies. Although the C-CBL mutations were oncogenic in NIH3T3 cells, c-Cbl was shown to functionally and genetically act as a tumour suppressor. C-CBL mutants did not have E3 ubiquitin ligase activity, but inhibited that of wild-type C-CBL and CBL-B (also known as CBLB), leading to prolonged activation of tyrosine kinases after cytokine stimulation. c-Cbl-/- haematopoietic stem/progenitor cells (HSPCs) showed enhanced sensitivity to a variety of cytokines compared to c-Cbl+/+ HSPCs, and transduction of C-CBL mutants into c-Cbl-/- HSPCs further augmented their sensitivities to a broader spectrum of cytokines, including stem-cell factor (SCF, also known as KITLG), thrombopoietin (TPO, also known as THPO), IL3 and FLT3 ligand (FLT3LG), indicating the presence of a gain-of-function that could not be attributed to a simple loss-of-function. The gain-of-function effects of C-CBL mutants on cytokine sensitivity of HSPCs largely disappeared in a c-Cbl+/+ background or by co-transduction of wild-type C-CBL, which suggests the pathogenic importance of loss of wild-type C-CBL alleles found in most cases of C-CBL-mutated myeloid neoplasms. Our findings provide a new insight into a role of gain-of-function mutations of a tumour suppressor associated with aUPD in the pathogenesis of some myeloid cancer subsets.