Role of survivin, whose gene is mapped to 17q25, in human neuroblastoma and identification of a novel dominant-negative isoform, survivin-beta/2B

PROCEDURE: We investigated the expression of survivin (SVV) and its isoform (SVV-beta/2B) during different biological properties in neuroblastoma (NBL). RESULTS: High levels of SVV mRNA expression were significantly associated with advanced stages of NBL, diagnosis at over 1 year of age, low levels of TrkA expression, and sporadic tumors. Expression of a novel isoform, SVV-beta/2B, which had an insertion of 23 amino acids within the unique BIR domain was predominant in some favorable NBLs, while it was low and ubiquitous in most normal and malignant tissues. The SVV expression wasdown-regulated during apoptosis induced by retinoic acid (RA) in CHP134 NBL cells, which was inhibited by forced expression of SVV. In contrast, SVV-beta was constantly expressed during apoptosis. Like SVV,SVV-beta was also highly expressed during G(2)/M in a cell cycle-dependent manner, and was associated with but competed against SVV for binding with polymerized tubulin. CONCLUSION: These data suggest that expression of SVV is a poor prognostic indicator in human NBL, and it promotes growth and survival by regulating the levels of both isoforms.     

Association between favorable neuroblastoma and high expression of the novel metalloproteinase gene, nbla3145/XCE, cloned by differential screening of the full-length-enriched oligo-capping neuroblastoma cDNA libraries

BACKGROUND: The biology of neuroblastoma (NBL) is at least partly regulated by neurotrophic factors and their receptors. PROCEDURE: To identify novel NBL-related genes that affect growth, differentiation, and programmed cell death of the tumor, we constructed full-length-enriched cDNA libraries by oligo-capping method. RESULTS: Semi-quantitative and quantitative real-time RT-PCR showed that the nbla3145 gene was significantly highly expressed in favorable subset of NBL. The nucleo-tide sequence of nbla3145 revealed that it was a novel member of metalloproteinase, endothelin-converting enzyme, and was the same gene recently reported as XCE. We also cloned nbla3145beta which was a novel truncated form of nbla3145 (or nbla3145alpha). CONCLUSIONS: Our results suggested that nbla3145/XCE plays an important role in regulating growth and differentiation of NBL.     

高氧对新生大鼠肺caspase-3和p53基因表达及肺细胞凋亡的影响

目的探讨高氧对新生大鼠肺caspase3和p53基因表达及肺细胞凋亡的影响。方法采用SpraqueDawley新生大鼠95%氧气暴露建立高氧肺损伤模型。应用RTPCR技术检测肺组织caspase3mRNA和p53mRNA水平,凝胶电泳条带用成像系统照相分析结果。计算目的基因PCR产物条带与内参照βactin条带光密度值的比值,作为p53基因的相对表达量,结果以x±s标记,而caspase3mRNA表达量则以阳性表达或阴性表达为标记。应用脱氧核糖核酸转移酶介导的细胞凋亡标记技术(TUNEL)原位检测细胞凋亡。光镜下随机计算5个视野中500个肺细胞中的阳性细胞数,结果以x±s标记。结果新生大鼠暴露于95%氧浓度环境中24h后肺组织中p53mRNA表达中度增加(q=3.2305,P>0.05),48h后表达显著增加,与空气对照组相比差异有统计学意义(q=7.2941,P<0.05)。新生鼠高氧处理72h、96h后,肺组织p53mRNA表达又恢复到正常水平。在各空气对照组和各高氧处理组中个别新生鼠肺的caspase3mRNA有微量表达,绝大多数新生鼠肺的caspase3mRNA没有表达,差异无统计学意义。95%氧暴露7天的新生鼠肺细胞凋亡水平明显高于空气暴露组新生鼠肺细胞凋亡水平,两者比较差异有极显著的统计学意义(F=100,P<0.001)。结论在高浓度供氧下,肺组织通过暂时上调p53基因的表达,介导细胞周期停滞,阻止G0/G1期细胞进入S期,抑制细胞分裂、增殖,同时p53促进细胞凋亡,从而导致肺生长发育受阻和肺损伤。新生鼠暴露于95%氧环境中,肺组织caspase3基因基本上不表达,因此推测高氧肺细胞凋亡可能存在不经过caspase3的凋亡途径。     

p75 mediated apoptosis in neuroblastoma cells is inhibited by expression of TrkA

BACKGROUND: Neurotrophins mediate their effects by binding to members of the Trk family of receptor tyrosine kinases and to the low-affinity nerve growth factor receptor p75. Nerve growth factor (NGF) has been demonstrated to support survival and differentiation of neuroblastoma (NB) cells by activation of the TrkA receptor. The p75 receptor belongs to the tumor necrosis factor (TNF) family of death receptors and has been suggested as a receptor that mediates apoptosis in neuronal and NB cells. PROCEDURE: To investigate the effect of p75 expression in NB, we transfected the p75 cDNA into SH-SY5Y cells, an NB cell line lacking expression of both p75 and TrkA. RESULTS: Cell clones expressing elevated levels of p75 showed a high degree of apoptosis even in 10% serum-supplemented medium. Apoptotic signaling by p75 was ligand-independent and only partly caspase-dependent. The level of apoptosis correlated directly with the expression level of the receptor, indicating that p75 may activate the cell death program directly. However, additional transfection of TrkA into SY5Y-p75 cells resulted in a significantly reduced rate of apoptosis even in the absence of NGF. CONCLUSIONS: Thus, expression of the TrkA receptor itself inhibits p75 mediated apoptosis in NB cells.     

Genetic analysis of p73 localized at chromosome 1p36.3 in primary neuroblastomas

BACKGROUND: Human p73, a novel homolog of p53, has recently been cloned and mapped at chromosome 1p36.3, the locus for putative tumor suppressor gene(s) of neuroblastoma (NBL) and other cancers. p73, like p53, inhibits growth and induces apoptosis in neuroblastoma and osteosarcoma cell lines. PROCEDURE: To test the hypothesis that p73 is a NBL suppressor gene, we examined expression, allelo-typing, and mutation of the p73 gene in primary human neuroblastomas. Loss of heterozygosity (LOH) for p73 was performed in 272 primary NBLs using a CT repeat polymorphic marker, which we found in intron 9 of the p73 gene. RESULTS: p73 LOH was observed in 28 out of 151 (19%) informative cases. The high frequency of p73 LOH was significantly associated with sporadic neuroblastomas (P< 0.001), MYCN amplification (P< 0.001), and advanced stages (P< 0.05). Mutational analyses by PCR-SSCP (single strand conformation polymorphism) revealed two mis-sense mutations in 140 NBLs, one somatic and one germline. CONCLUSION: Thus, the present results have shown that mutation of p73 is infrequent in NBLs, although the p73 locus is frequently lost in advanced stage tumors. These suggest that p73 may not be a tumor suppressor in the classic Knudson manner.     

多重基因转染对神经母细胞瘤SH-SY5Y细胞增殖和免疫原性的影响

目的 观察多重基因转染对神经母细胞瘤SH-SY5Y细胞增殖、凋亡及免疫原性的影响.方法 以空病毒质粒(SH/Ad组)、携带肿瘤抑制基因人野生型p53(wt-p53)的腺病毒质粒(SH/p53组)及携带wt-D53、免疫相关基因B7-1和粒-巨噬细胞集落刺激因子(CM-CSF)基因的腺病毒质粒(SH/BB-102组)转染SH-SY5Y细胞,并以未转染的肿瘤细胞为空白对照(SH组).分别采用免疫印迹法、流式细胞术和酶联免疫吸附法检测p53蛋白、B-1分子和GM-CSF的表达.观察转染前后细胞生长及凋亡情况.用混合淋巴细胞培养法检测瘤苗对T细胞增殖和细胞因子分泌的诱导作用.结果 腺病毒转染SH-SY5Y细胞后,目的基因得到了高效表达.与SH和SH/Ad组相比,SH/p63和SH/BB-102组细胞生长速度减慢,凋亡增加(P<0.05).SH/BB-102组与其他组比较,能够促进T细胞增殖,增加γ干扰素和白细胞介素-2的分泌(P<0.05).结论 wt-p53、E7-1和GM-CSF基因联合转染可以抑制SH-SY5Y细胞的生长、诱导细胞凋亡,并且可以增强肿瘤细胞的免疫原性.     

p53 protein expression does not correlate with EBV status in childhood B non-Hodgkin lymphomas

BACKGROUND: The p53 tumor suppressor gene is affected in a wide range of human cancers, including hematological malignancies. This gene encodes a nuclear phosphoprotein p53, which plays a key role in cell cycle arrest, induction of apoptosis, and DNA repair. Mutations of the p53 gene often lead to the accumulation of the mutated protein in the nucleus of neoplastic cells. However, p53 protein expression is frequently detected in non-Hodgkin lymphomas (NHL) without any correlation with p53 mutations. This discordance suggests the existence of other mechanisms to stabilize the p53 protein, including binding of p53 protein to viral proteins. p53 protein has been shown to bind to proteins encoded by the Epstein-Barr virus (EBV). PROCEDURE: The aim of this study was to analyze p53 expression in childhood B-NHL and correlate its expression in the absence of p53 mutations with EBV in order to investigate a possible involvement of EBV in p53 stabilization. DESIGNS AND METHODS: Tumor specimens from 35 children with B-NHL were analyzed by immunohistochemistry (IHC) with the DO7 monoclonal antibody, which recognizes an epitope at N-terminus of p53 protein and reacts with wild type and mutant proteins. To detect p53 mutations, PCR/SSCP and sequencing were performed. EBV status was determinated using a specific PCR technique. RESULTS: The overall frequency of p53 immunostaining positivity was 45% (16 of 35). p53 mutations were detected in nine patients (25.6%). p53 immunoreactivity was observed in all cases with mutations. Additionally, we identified 7 p53 positive cases among 26 tumors without mutations. EBV DNA was detected in 24 of 35 cases. Four patients with p53 expression dissociated from mutation were EBV positive. No statistically significant association was found between p53 expression and EBV cases despite the exclusion of those patients in which p53 expression was related with p53 mutations (P = 0.28 and 0.54, respectively). CONCLUSIONS: Our results suggested that in childhood B-NHL, the expression of p53 dissociated from mutations could not be related to EBV infection. Further studies with larger patient sets will be necessary to determinate if EBV-encoded protein may play a role for nuclear accumulation of p53 protein.     

苦参碱联合顺铂对SH-SY5Y细胞药物敏感性及TrkB表达的影响

目的探讨不同浓度苦参碱对神经母细胞瘤SH-SY5Y细胞存活及凋亡的影响,及苦参碱降低顺铂化疗耐药性的作用及可能机制。方法分别以全反式维甲酸(ATRA)、脑源性神经生长因子(BDNF)、顺铂、苦参碱处理SH-SY5Y细胞,实验分对照组、ATRA诱导的顺铂干预组、顺铂干预组、苦参碱干预组、苦参碱联合顺铂干预组。应用四甲基偶氮蓝比色法检测苦参碱与顺铂对SH-SY5Y细胞存活率的影响,流式细胞仪检测苦参碱与顺铂对SH-SY5Y细胞凋亡率的影响,Western-blot方法检测SH-SY5Y细胞的p-TrkB表达。结果除ATRA诱导的顺铂干预组外,其余各组SH-SY5Y细胞的存活率及凋亡率与对照组比较,差异均有统计学意义(P<0.05);顺铂干预组与ATRA诱导的顺铂干预组比较,SH-SY5Y细胞的存活率及凋亡率差异有统计学意义(P<0.05);相同浓度的苦参碱干预组与苦参碱联合顺铂干预组比较,SH-SY5Y细胞的存活率及凋亡率差异有统计学意义(P<0.05);苦参碱联合顺铂组与顺铂干预组比较,SH-SY5Y细胞的存活率及凋亡率差异有统计学意义(P<0.05)。苦参碱0.5 mg/ml组与顺铂干预组比较,SH-SY5Y细胞的存活率及凋亡率差异无统计学意义(P>0.05)。各组SH-SY5Y细胞间,p-TrkB的表达水平差异无统计学意义(P>0.05)。结论苦参碱可以抑制SH-SY5Y细胞的增殖并诱导凋亡,从而提高顺铂化疗的敏感性,该作用与TrkB/BDNF信号通路(间)无相关性。     

Effects of retinoic acid on proliferation,apoptosis, cytotoxicity,migration, and invasion of neuroblastoma cells

BACKGROUND: Because of the known property of less aggressiveness of differentiated cells compared to immatured cells all attempts are made to elucidate whether differentiation inducers possibly could be applied for neuroblastoma therapy. We are interested in examining the influence of retinoic acid (RA) on proliferation, apoptosis, cytotoxicity, migration, and invasion in dependence of the differentiation of neuroblastoma cells classified into N-type (SK-N-FI, SH-SY5Y), I-type (SK-PN-DW), and S-type (SK-N-LO, SK-N-MC) cells. PROCEDURE: Neuroblastoma cells were exposed to 10(-5) M RA and 200 ng/ml camptothecin (CAM) (control substance for apoptosis). Proliferation, apoptosis, and cytotoxicity were quantified by photometric assays. The influence on migration and invasion of neuroblastoma cells was examined by a scratch-test and by the measurement of the invasion through matrigel coated chamber inserts. RESULTS: In general, RA treatment induced proliferation inhibition predominantly in the cell lines SK-PN-DW (16%, P < 0.05) and SK-N-MC (8%, (P < 0.001), respectively. In the N-type cell lines SK-N-FI (P > 0.05) and SH-SY5Y (P < 0.001) no proliferation inhibition was determined conforming with no detection of apoptosis. CAM confirmed its capability to induce apoptosis in the cell lines SH-SY5Y (43.6%, P < 0.05), SK-PN-DW (54.8%, P > 0.05), and SK-N-MC (28.9%, P < 0.0 01) except for SK-N-FI with only 9.3% (P > 0.05), but after 24 hr of treatment. Minor signs of restricted migration were observed, while RA treatment reduced significantly the invasion rate through Matrigel of SK-N-FI to 13.3% (P < 0.01), SH-SY5Y to 19.2% (P < 0.05), SK-N-MC to 27.8% (P < 0.05), and SK-N-LO to 17.7% (P < 0.01). CONCLUSIONS: It is demonstrated that RA treatment can interfere with cell growth and in invasion by inducing neuronal differentiation in N-type and apoptosis in S-type neuroblastoma cell lines.     

MycN sensitizes neuroblastoma cells for drug-triggered apoptosis

BACKGROUND: Amplification of the MYCN gene is found in a large proportion of neuroblastomas and is associated with a poor prognosis. PROCEDURE: To investigate the effect of ectopic MycN expression on the susceptibility of neuroblastoma cells to cytotoxic drugs, we used a human neuroblastoma cell line with tetracycline-controlled expression of MycN. RESULTS: Neither conditional expression of MycN alone nor low drug concentrations induced apoptosis. However, MycN and cytotoxic drugs cooperated to induce cell death. Apoptosis triggered by MycN and doxorubicin was mediated by cleavage of caspases and involved activation of the CD95 system. MycN overexpression and cytotoxic drugs also synergized to induce p53 and Bax protein expression and to trigger mitochondrial permeability transition and cytochrome c release. CONCLUSION: In that amplification of MYCN is considered an adverse prognostic factor, these findings suggest that dysfunctions in apoptosis pathways may be a mechanism by which MycN-induced apoptosis of neuroblastoma cells is inhibited.     

维甲酸受体及其信号通路在肾脏疾病中的作用

维甲酸(RA)受体是一组配体依赖的核转录调节因子,广泛分布在各类组织细胞中,其不同亚型之间可形成同源性或异源性二聚体,参与胚胎发育、细胞增殖、分化、凋亡等病理生理过程。在不同细胞或组织中,RA受体的表达与疾病的关系不尽相同。近年研究认为,RA受体与肾脏疾病的发生发展关系密切。文章综述RA受体及其信号通路在肾脏疾病发生发展中的作用。     

A new sensitive and specific combination of CD81/CD56/CD45 monoclonal antibodies for detecting circulating neuroblastoma cells in peripheral blood using flow cytometry

PURPOSE: Intensive chemoradiotherapy followed by peripheral blood stem cell transplantation has been introduced to treat children with advanced neuroblastoma (NBL). Detection of NBL cells in peripheral blood (PB) is important to prevent reinfusion of NBL cells. Several immunologic methods have been proposed for detecting NBL cells in hematologic samples. The development of a sensitive and specific combination of monoclonal antibodies (MoAbs) for detecting small numbers of NBL cells in PB using flow cytometry remains an important challenge. METHODS: Twenty-one clinical samples from NBL tissues or smears containing NBL cells were examined for reactivity against CD81, CD56, and CD9 using an immunocytochemical technique. The expressions of CD81, CD56, CD9, and antihuman disialoganglioside GD2 MoAb (GD2) in five NBL cell lines were assayed by flow cytometry. For the evaluation of sensitivity, five NBL cell lines were added to normal PB and the detection level of the combination of CD81/CD56/CD45 MoAbs was compared with that of CD9/CD56/CD45 MoAbs (reported previously). One hundred thirty-three normal PB samples were examined to determine the sensitivity and specificity of this method. RESULTS: All NBL cell lines showed strong positivity with CD81 and CD56 MoAb. However, CD9 MoAb was weakly positive against the five NBL cell lines. GD2 MoAb reacted strongly with four NBL cell lines, although almost the entire cell population of the SK-N-SH NBL line failed to bind the GD2 MoAb. In vitro experiments using NBL cell lines demonstrated that tumor cells added to normal PB cells could be detected by flow cytometry using CD81/CD56/CD45 MoAbs even at a concentration of 0.005%. Through comparative studies, the combination of CD81/CD56/CD45 MoAbs was found to be more sensitive and specific than that of CD9/CD56/CD45 MoAbs for detecting small numbers of NBL cells using the above cell lines. CONCLUSIONS: Triple-color flow cytometric analysis using CD81/CD56/CD45 MoAbs is useful for detecting NBL cells in PB. Further studies testing this approach using samples of PB with NBL contamination are needed to test this approach in patients.     

Different effects of TrkA expression in neuroblastoma cell lines with or without MYCN amplification

BACKGROUND: Expression of the neurotrophin receptor TrkA is associated with a favorable prognosis in neuroblastoma (NB) and promotes growth inhibition and neuronal differentiation. Aggressive, MYCN-amplified NB tumors express little or no TrkA mRNA, suggesting that MYCN overexpression may inhibit TrkA expression. PROCEDURE: To study the interactions of TrkA expression and MYCN amplification in NB, we stably expressed the TrkA receptor in the MYCN single copy cell lines SH-SY5Y and NB69 as well as in the MYCN amplified cell lines CHP134 and IMR5. RESULTS: All four transfected cell lines demonstrated high TrkA expression and similar activation of the TrkA receptor and of mitogen-activated protein kinases as well as induction of immediate-early genes in response to nerve growth factor (NGF). Introduction of TrkA restored NGF responsiveness of SH-SY5Y and NB69 cells, as demonstrated by morphologic differentiation, growth inhibition, and enhanced survival in serum-free medium. However, no morphologic, growth, or survival responses to NGF were detected in MYCN-amplified CHP134 and IMR5 TrkA transfectants. CONCLUSIONS: Thus, transfection of TrkA into MYCN amplified NB cell lines only partly restored the TrkA/NGF signaling pathway, suggesting additional inhibitory effects of MYCN overexpression on TrkA signaling.     

Human polyomavirus BK (BKV) and neuroblastoma: mechanisms of oncogenic action and possible strategy for novel treatment

BACKGROUND: We reported previously that nearly all human neuroblastomas analyzed contain and express genomic DNA sequences deriving from the human polyomavirus BK (BKV) [Flaegstad et al.: Cancer Res 59:1160-1163, 1999]. PROCEDURE: Here we show that the BKV large T antigen is expressed and bound to p53 in neuroblastoma cells and that this interference compromises the tumor suppressor function of p53. RESULTS: Treatment of neuroblastoma cells with large T antigen antisense constructs relocated active p53 to the nucleus. The relocation event was accompanied by enhanced p21(waf1/cip1) expression as well as induced apoptosis. CONCLUSIONS: Continuous antisense oligonucleotide treatment of nude rats with human neuroblastoma xenografts resulted in a significant but incomplete reduction of tumor growth compared to rats treated with saline.     

Caspase-8在TRAIL诱导神经母细胞瘤细胞凋亡中的作用

目的：应用干扰素(IFNγ)诱导神经母细胞瘤（neuroblastoma, NB）细胞caspase 8的表达并观察其是否可以恢复NB细胞对肿瘤坏死因子相关凋亡诱导配体（TRAIL）的敏感性。方法：应用RT PCR方法检测IFNγ作用前后NB细胞caspase-8 mRNA的表达;应用Alamar Blue法及流式细胞术检测IFNγ、TRAIL、IFNγ+TRAIL、IFNγ+caspase-8抑制剂zIETD-FMK+TRAIL对NB细胞生长及凋亡的影响;应用比色法测定NB细胞caspase-8相对活性。结果：对TRAIL敏感的CHP212细胞表达caspase-8,且经IFNγ处理后caspase-8 表达水平逐步增加;对TRAIL不敏感的SY5Y细胞不表达caspase-8,IFNγ作用后其caspase-8 mRNA表达明显增加。IFNγ与TRAIL联用对SY5Y细胞有明显诱导凋亡作用。CHP212细胞caspase-8相对活性随TRAIL作用时间的延长逐步升高;IFNγ与TRAIL联合作用的SY5Y细胞caspase-8相对活性明显高于未加药物处理的对照组、IFNγ组、TRAIL组及抑制剂组。结论：表达caspase-8的NB细胞对TRAIL的诱导凋亡作用敏感,TRAIL诱导NB细胞凋亡过程中伴随caspase-8活性的增加。［中国当代儿科杂志,2010,12(11)：902-907］     

Apoptosis induced by Pseudomonas aeruginosa in antigen presenting cells is diminished by genetic modification with CD40 ligand

Persistent colonization with Pseudomonas aeruginosa (PA) is a hallmark of the lung disease associated with cystic fibrosis (CF). Based on the concept that PA is not cleared from the lung by the host response in individuals with CF, we analyzed the capacity of PA to induce cell death in human alveolar macrophages (AM) and murine dendritic cells (DC), antigen presenting cells that play a central role in the initiation of pulmonary host defenses against pathogens, and evaluated if genetic modification can lead to protection against PA induced cell death. AM and DC were susceptible to cell death induced by the laboratory PA isolates PAO1, PAK and PA103, as well as a mucoid derivative of PAO1 and PA isolates derived from sputum of individuals with CF. Apoptosis, analyzed by TUNEL assay, was detectable in AM and DC as early as 3 h after infection with PA. In contrast, the same strains and doses of PA had little effect on the lung epithelial cell line A549 and primary cultures of human bronchial epithelial cells in vitro. Pretreatment of DC with the caspase inhibitors VAD-fmk and YVAD-cmk reduced PA induced cell death (p < 0.05). Finally, genetic modification of DC to express CD40L using an adenovirus vector decreased the susceptibility of DC to cell death induced by PAO1 compared with DC infected with a control Ad vector (p < 0.01). The data demonstrate that DC and AM are susceptible to apoptosis induced by PA and that this response can be partially reversed by genetic modification with CD40L, a CD4+ T cell molecule that plays a central role in activating antigen presenting cells. These observations suggest a potential mechanism contributing to the persistence of PA in CF and suggest that genetic manipulation of antigen presenting cells with anti-apoptotic genes may be able to strengthen host defenses in CF.     

胚胎期骨髓间充质干细胞移植对先天性脊柱裂大鼠脊髓NGF和BDNF的表达及细胞凋亡的影响

目的 研究胚胎期骨髓间充质干细胞(bone marrow mesenchymal stem cell,BMSC)移植对显性脊柱裂胎鼠脊髓组织中神经生长因子(nerve growth factor,NGF)和脑源性神经营养因子(brain derived neurotrophic factor,BDNF)的表达及细胞凋亡的影响.方法 建立全反式维甲酸致畸的显性脊柱裂大鼠模型,妊娠16d通过胎仔外科与显微注射相结合的方法将BMSC移植入胎鼠脊髓缺损部位,待胎鼠成活至妊娠21 d取脊髓,免疫荧光染色检测移植BMSC后脊髓缺损部位NGF和BDNF的表达,同时TUNEL染色法检测细胞凋亡的变化.结果 显性脊柱裂胎鼠BMSC移植后脊髓内BDNF、NGF的表达增强,而且BMSC移植区表达升高最显著,TUNEL染色显示BMSC移植组细胞凋亡明显减少.结论 胚胎期BMSC移植后改变脊柱裂病变区微环境,可能通过上调神经营养因子的表达,抑制细胞凋亡,从而促进脊柱裂神经损伤的修复.     

p53 expression in biopsies from children with Langerhans cell histiocytosis

PURPOSE: Langerhans cell histiocytosis (LCH) is a rare pediatric and adult disease causing skin rashes, osteolytic bone lesions, tumorous growth in various organs, and in some patients, organ dysfunction. The cause of the disease is obscure, and it is not yet understood why some patients develop single-system lesions only without relapse, whereas others develop fatal multiorgan disease. The expression of p53 tumor suppressor gene product detected immunohistochemically can be used as a guideline to alterations in DNA repair control and apoptosis. The authors have chosen to analyze p53 expression in biopsies from children with LCH and correlate it with clinical manifestation and outcome in a broad range of organs. PATIENTS AND METHODS: The study was performed on 50 specimens from 32 children (19 boys and 13 girls), median age 3 1/4 years, range 5 months to 12 1/3 years with a definite diagnosis of LCH based on CD1a positivity. The slides were stained with p53 antibody and semiquantitatively evaluated using a grading system from 1 to 5 as an estimate for 0% to 20%, 20% to 40%, 40% to 60%, 60% to 80%, and 80% to 100% p53-positive for pathologic Langerhans cells (pLC), respectively. RESULTS: The p53 protein was expressed in various degrees in pLC in all lesions. The degree of p53 expression could not be correlated to either clinical manifestation or outcome. CONCLUSIONS: An increased expression of p53 in pLC indicates an altered DNA repair control with or without abnormal control of apoptosis.