Deciphering the genotype and phenotype of hairy cell leukemia: clues for diagnosis and treatment

ABSTRACT

Introduction: Hairy cell leukemia (HCL) is a rare, indolent B-cell neoplasm. The classical variant of the disease is characterized by the BRAF V600E mutation, which is present in virtually all cases. How this mutation leads to the signs and symptoms of the disease is currently not known.

Areas covered: This review explores the genetic background of HCL, especially the BRAF V600E driver mutation, but passenger mutations and their effects are also included. The clinical significance of BRAF mutations in other cancer types is discussed, as well as BRAF- induced senescence. An overview of the major forms of treatment of HCL (cytostatic drugs, specific BRAF inhibitors, B cell-specific antibodies) is given. Finally, possible mechanisms of the monocytopenia and hairy morphology so typical of this disease are discussed.

Expert opinion: Although being a rare disease, HCL and its pathogenesis can yield important information about BRAF-related cancer metabolism. Many aspects of the disease are still unclear, but with the right resources, this could change. This can lead to a more efficient and specific treatment, thus leading to decreased morbidity.     

人之衰老肾为其本——试论肾虚衰老说

衰老是人类生命过程的必然规律,肾中精气的盛衰与衰老发生的早迟息息相关,且贯穿于整个衰老的过程,肾虚与衰老的关系早在《黄帝内经》中即有所论述。不仅从古代文献中进行引证,也从肾虚致衰的现代医学理论基础加以证明,认为人体衰老的根本是肾中精气发生了变化,只有补肾固精,扶其根本才能最大限度地延长人类的平均寿命,以至渐臻天年。     

Genetic Complementation of the Immortal Phenotype in Group D Cell Lines by Introduction of Chromosome 7

Human immortal cell lines have been classified into at least four (A–D) genetic complementation groups by cell-cell hybrid analysis, i.e., a hybrid derived from different groups becomes mortal. Recently we have demonstrated that introduction of human chromosome 7 suppresses indefinite division potential in the non-tumorigenic human immortalized fibroblast lines KMST-6 and SUSM-1, both assigned to complementation group D. By extending our microcell-mediated chromosome transfer, we found that chromosome 7 also suppresses division potential in the human hepatoma line HepG2 (again, assigned to group D). Chromosome 7 was thus shown to suppress indefinite growth in the above group D cell lines irrespective of their cell types, or whether they are tumorigenic or not. Since chromosome 7 had no such effect on representative cell lines derived from complementation group A, B or C, these results indicate that the senescence gene(s) commonly mutated in the group D cell lines is located on chromosome 7.     

Alterations in trkB mRNA in the human prefrontal cortex throughout the lifespan

Signalling through tyrosine kinase receptor B (trkB) influences neuronal survival, differentiation and synaptogenesis. trkB exists in a full-length form (trkB(TK+)), which contains a catalytic tyrosine kinase (TK) domain, and a truncated form (trkB(TK-)), which lacks this domain. In the rodent brain, expression of trkB(TK+) decreases and trkBTK- increases during postnatal life. We hypothesized that both forms of trkB receptor mRNA would be present in the human neocortex and that the developmental profile of trkB gene expression in human may be distinct from that in rodent. We detected both trkB(TK+) and trkB(TK-) mRNA in RNA extracted from multiple human brain regions by Northern blot. Using in situ hybridization, we found trkB(TK+) mRNA in all cortical layers, with highest expression in layer IV and intermediate-to-high expression in layers III and V of the human dorsolateral prefrontal cortex. trkB(TK+) mRNA was present in neurons with both pyramidal and nonpyramidal shapes in the dorsolateral prefrontal cortex. trkB(TK+) mRNA levels were significantly increased in layer III in young adults as compared with infants and the elderly. In the elderly, trkB(TK+) mRNA levels were reduced markedly in all cortical layers. Unlike the mRNA encoding the full-length form of trkB, trkB(TK-) mRNA was distributed homogeneously across the grey matter, and trkB(TK-) mRNA levels increased only slightly during postnatal life. The results suggest that neurons in the human dorsolateral prefrontal cortex are responsive to neurotrophins throughout postnatal life and that this responsiveness may be modulated during the human lifespan.     

Transformation by inorganic arsenic compounds of normal Syrian hamster embryo cells into a neoplastic state in which they become anchorage-independent and cause tumors in newborn hamsters

Arsenic is a known human carcinogen, but little evidence exists for its carcinogenicity in animals. In order to investigate the ability of inorganic arsenics to transform normal cells into a neoplastic state, mass cultures of normal, diploid Syrian hamster embryo (SHE) cells exposed to various concentrations of sodium arsenite or sodium arsenate for 48 hr were continually passaged and tested for neoplastic transformation, as determined by anchorage-independent growth in semisolid agar and tumorigenicity in newborn hamsters. Twenty-one of 22 (96%) untreated, control cultures senesced by 20 passages. While 1 culture escaped senescence, it did not acquire the ability to either grow in semisolid agar or form tumors in animals. Ten of 14 (71%) cultures exposed to sodium arsenite or sodium arsenate escaped senescence. Nine of the 10 (90%) arsenic-treated immortal cultures acquired the anchorage-independent phenotype. Five of 5 anchorage-independent cultures examined were tumorigenic. Two of 3 morphologically transformed colonies induced by sodium arsenate also acquired the ability to grow in semisolid agar when isolated. Amplification of the c-myc or c-Ha-ras oncogene was detected in 3 of 5 and 4 of 5 tumorigenic cell lines, respectively. Both c-myc and c-Ha-ras were amplified even in a preneoplastic, anchorage-dependent cell line, but neither was amplified in 6 of 9 anchorage-independent cell lines. Overexpression of c-myc and c-Ha-ras mRNA was observed in most of the neoplastically transformed cell lines but not in the preneoplastic cell line. Experiments using the methylation-sensitive restriction endonuclease isoschizomers HpaII and MspI revealed hypomethylation of c-myc and c-Ha-ras in the 5'-CCGG sequence of arsenic-exposed cell lines but not in the parental SHE cells or a spontaneously transformed cell line. Thus, inorganic arsenics induce neoplastic transformation of normal, diploid mammalian cells. Overexpression of oncogenes by DNA hypomethylation may participate in the arsenic-induced neoplastic transformation of mammalian cells.     

Application of the yeast two-hybrid system in molecular gerontology

Most – if not all – proteins are bound to interact with other proteins to exert their function, and thus the identification of the interaction partners of a protein is vital in proteomics. The yeast two-hybrid system is a popular and effective tool for studyingprotein–protein interactions. Although the advantages of the system are manifold, it also has certain drawbacks and limitations. The two-hybrid system has been shown to be extremely useful for placing a protein of unknown function within a functional context, thereby providing information about a putative role of the uncharacterised protein. This concept has also been successfully applied in molecular gerontology. This revised version was published online in July 2006 with corrections to the Cover Date.     

Oncogenic ras induces premature senescence in endothelial cells: role of p21(Cip1/Waf1)

Recent studies have shown that the presence of tumor suppressors such as p53 or p16 account for the lack of transformation in primary cells. To investigate a potential role of active Ras in atherosclerosis, we infected bovine aortic endothelial cells with a replication-deficient, recombinant adenovirus containing the activated H-Ras^61L gene. Ras overexpression led after 72 hours to G1- and G2/M-cell cycle arrest due to induction of p21^Cip1/Waf1. Treatment of Ras-infected endothelial cells with 40 ng/ml TNF-α for 20 hours augmented apoptosis 8-fold in comparison to Ad-Con (control virus with empty expression cassette) infected cells (36.2 % vs. 4.3 %, p < 0.001), while Ras itself did not cause any cell death. Furthermore, more than 58 % of Ras-infected cells stained positive for senescence-associated β-galactosidase activity as opposed to 2 % in control vector-infected cells (p < 0.001), strongly suggesting a senescent phenotype in the Ras-infected population. We found further features of senescence in Ras-transduced endothelial cells, such as growth arrest and the lack of AP-1 serum inducibility. Finally, we evaluated the role of p21^Cip1/Waf1 in this process of senescence. Adenoviral overexpression of p21 led to growth arrest by induction of G1- and G2/M-cell cycle arrest. In addition, p21-overexpressing endothelial cells were highly sensitive for TNF-α induced-apoptosis. Surprisingly, senescence-associated β-galactosidase activity was not apparant in p21-infected endothelial cells, suggesting further signaling events necessary for the senescent morphology of endothelial cells. Our results demonstrate a novel way to render primary endothelial cells senescent by overexpressing oncogenic Ras. Increased sensitivity of senescent endothelial cells for cytotoxic stimuli seemed to be due to Ras-induced upregulation of p21^Cip1/Waf1. Future studies have to investigate a potential role of Ras in human vascular biology. Received: 5 June 2001, Returned for revision: 28 June 2001, Revision received: 6 July 2001, Accepted: 31 July 2001     

成年大鼠肝细胞的细胞动力学研究

目的:研究成年大鼠肝细胞的细胞增生、衰老与凋亡的动力学过程。方法:应用HE染色、衰老相关-β-半乳糖苷酶组织化学染色、增殖细胞核抗原(PCNA)免疫组织化学方法、末端转移酶dUTP缺口末端标记(TUNEL)原位细胞凋亡检测方法探讨正常大鼠肝细胞的细胞动力学。结果:肝细胞呈现多种方式的无丝分裂像。增殖细胞核抗原阳性细胞散在分布于肝小叶内,成群分布于门管区。衰老细胞散在分布于肝小叶内,以肝小叶周边部较多。凋亡细胞分布于中央静脉周围和门管区周围。结论:成年大鼠肝细胞呈现细胞增殖、生长、衰老和凋亡的细胞动力学过程。     

晶状体上皮细胞端粒酶活性及细胞衰老的实验研究

目的明确晶状体上皮细胞(LEC)是否存在端粒酶活性表达;研究端粒酶活性的变化与LEC衰老的关系,为探讨年龄相关性白内障的发生机制提供理论依据。方法体外培养兔LEC并传代。以端粒重复扩增-免疫酶标(TRAP-ELISA)试剂盒检测细胞端粒酶活性;对各代细胞进行β-半乳糖苷酶组织化学染色检测衰老细胞,计算衰老细胞百分数。结果兔LEC存在端粒酶活性表达,在体外培养、传代过程中端粒酶活性逐渐减弱,至第4代低于检测水平,活体、原代、第1、2、3代的端粒酶活性分别为:0.46±0.046,0.32±0.026,0.25±0.029,0.19±0.019,0.11±0.038;衰老细胞随细胞的传代增加,活体与原代培养的LEC未发现衰老现象,第1~9代衰老细胞百分数(%)分别为:(0.98±0.39)、(4.93±1.35)、(11.08±1.69)、(24.98±3.55)、(33.89±3.74)、(41.17±5.24)、(51.75±8.32)、(73.00±5.98)、(77.00±14.18)。结论LEC存在端粒酶活性表达,端粒酶活性的变化与LEC的衰老有关,可能在年龄相关性白内障发生的病理生理过程中发挥重要作用。     

针刺组方影响SAMP10脑CaN mRNA特异性表达的实验研究*

[目的]了解不同的针刺配穴组方对快速老化小白鼠(SAMP10)脑钙调神经磷酸酶(CaN)mRNA表达的影响.[方法]用α-32P-dCTP标记探针,Northern杂交法进行mRNA表达水平的半定量分析,分别以取穴水沟、内关的醒脑开窍法(针刺泻实组)和取穴肝俞、肾俞的滋补肝肾法(针刺补虚组)干预8月龄SAMP10(模型组).[结果]与正常组比较,模型组CaN mRNA表达水平下降.醒脑开窍法可提高CaN mRNA表达至接近正常水平(P＜0.05),滋补肝肾法有升高其表达的趋势(P＞0.05),提示醒脑开窍法优于滋补肝肾法.[结论]CaN mRNA表达水平低下可能是脑老化的机制之一,针刺能提高CaN mRNA表达水平,并具有组方配穴的特异性,提示醒脑开窍法可能是干预脑老化的潜在策略.