High-throughput simultaneous screen and counterscreen identifies homoharringtonine as synthetic lethal with von Hippel-Lindau loss in renal cell carcinoma

Renal cell carcinoma (RCC) accounts for 85% of primary renal neoplasms, and is rarely curable when metastatic. Approximately 70% of RCCs are clear-cell type (ccRCC), and in >80% the von Hippel-Lindau (VHL) gene is mutated or silenced. We developed a novel, high-content, screening strategy for the identification of small molecules that are synthetic lethal with genes mutated in cancer. In this strategy, the screen and counterscreen are conducted simultaneously by differentially labeling mutant and reconstituted isogenic tumor cell line pairs with different fluorochromes and using a highly sensitive high-throughput imaging-based platform. This approach minimizes confounding factors from sequential screening, and more accurately replicates the in vivo cancer setting where cancer cells are adjacent to normal cells. A screen of ~12,800 small molecules identified homoharringtonine (HHT), an FDA-approved drug for treating chronic myeloid leukemia, as a VHL-synthetic lethal agent in ccRCC. HHT induced apoptosis in VHL-mutant, but not VHL-reconstituted, ccRCC cells, and inhibited tumor growth in 30% of VHL-mutant patient-derived ccRCC tumorgraft lines tested. Building on a novel screening strategy and utilizing a validated RCC tumorgraft model recapitulating the genetics and drug responsiveness of human RCC, these studies identify HHT as a potential therapeutic agent for a subset of VHL-deficient ccRCCs.     

DRR1调节神经母细胞瘤细胞分化的作用机制

目的:探究肾细胞癌下调蛋白1（down-regulated in renal cell carcinoma 1,DRR1）在神经母细胞瘤细胞分化中的作用以及内在的分子机制。方法:在神经母细胞瘤细胞中敲减或过表达DRR1后,分别考察细胞分化状态的变化、细胞周期的变化以及利用real-time PCR的方法检测其潜在下游因子的表达变化;利用神经母细胞瘤患者数据库,分析在神经母细胞瘤患者样本中DRR1的潜在下游因子的表达与DRR1表达之间的相关性;诱导神经母细胞瘤细胞分化后,利用real-time PCR的方法检测DRR1的潜在下游因子的表达变化。结果:DRR1的表达可促进神经母细胞瘤细胞的分化;敲减DRR1促进神经母细胞瘤细胞的G1/S期的转换,过表达DRR1抑制神经母细胞瘤细胞的G1/S期的转换;DRR1的表达改变影响其潜在下游因子在神经母细胞瘤细胞中的表达;在神经母细胞瘤患者样本中DRR1的表达与其潜在下游因子的表达呈显著相关性;DRR1的潜在下游因子的表达随神经母细胞瘤细胞分化状态的变化而改变。结论:DRR1通过调控下游因子的表达调节神经母细胞瘤细胞的分化。     

Novel chemical library screen identifies naturally occurring plant products that specifically disrupt glioblastoma-endothelial cell interactions

Tumor growth is not solely a consequence of autonomous tumor cell properties. Rather, tumor cells act upon and are acted upon by their microenvironment. It is tumor tissue biology that ultimately determines tumor growth. Thus, we developed a compound library screen for agents that could block essential tumor-promoting effects of the glioblastoma (GBM) perivascular stem cell niche (PVN). We modeled the PVN with three-dimensional primary cultures of human brain microvascular endothelial cells in Matrigel. We previously demonstrated stimulated growth of GBM cells in this PVN model and used this to assay PVN function. We screened the Microsource Spectrum Collection library for drugs that specifically blocked PVN function, without any direct effect on GBM cells themselves. Three candidate PVN-disrupting agents, Iridin, Tigogenin and Triacetylresveratrol (TAR), were identified and evaluated in secondary in vitro screens against a panel of primary GBM isolates as well as in two different in vivo intracranial models. Iridin and TAR significantly inhibited intracranial tumor growth and prolonged survival in these mouse models. Together these data identify Iridin and TAR as drugs with novel GBM tissue disrupting effects and validate the importance of preclinical screens designed to address tumor tissue function rather than the mechanisms of autonomous tumor cell growth.     

Phenotypic and morphological characterization of neuroblastoma cells constitutively expressing B-myb

B-myb gene is expressed in neuroblastoma cells and down-regulated during differentiation. We used B-myb-transfected LAN-5 cells, which constitutively express high level of B-myb, to detect changes at phenotypic and morphological levels in basal and differentiation conditions. Our results demonstrate that the overexpression of B-myb markedly affects the cytoskeletal composition, the pattern of neurotransmitter enzymes and the extracellular matrix expression. In general, B-myb transfected neuroblastoma cells show a broad potentiality without a direction toward a specific neuroectodermal differentiation pathway. On the other hand, we confirm inhibition of the neuronal differentiation upon retinoic acid (RA) treatment of B-myb transfected cells. Furthermore, the ultrastructural analyses are supportive of a change in the metabolism in B-myb transfected cell treated with RA. Our data suggest that B-myb expression is compatible with an early phase of differentiation of neuroectodermal cells, but must be down-regulated for the completion of the differentiative programme.     

Midkine对神经母细胞瘤TNB1细胞生长与分化的影响

目的:通过对中期因子(midkine,MK)在神经母细胞瘤TNB1细胞中的生物学作用进行研究,揭示该因子在肿瘤细胞生长和分化中相关分子机制.方法:1)利用神经母细胞瘤临床患者数据库,明确MK的表达与神经母细胞瘤患者生存率之间的关系.在体外细胞实验中,利用携带MKshRNA载体的慢病毒体外感染神经母细胞瘤TNB1细胞,分...     

Dimethyl sulfoxide-induced differentiation does not alter tumorigenicity of neuroblastoma cells

It has been shown that agents that are known to be scavengers of hydroxyl radicals may induce differentiation and inhibit growth of murine neuroblastoma cells in tissue culture. The present study tests dimethyl sulfoxide as a differentiation agent of the human neuroblastoma cell lines LA-N-1 and murine neuroblastoma NIE-115.Results indicate that DMSO induces morphologic and biochemical differentiation of neuroblastoma cells coupled to growth inhibition and inhibition of collony formation in semi liquid tissue culture systems.DMSO treatment in vitro had no effect on tumorgenicity of NIE-115 cells. In vivo DMSO treatment of athymic nude mice with transplanted LA-N-1 human neuroblastoma tumors has not affected tumor size or animal survival. No diminishing effect of natural killer cell activity could be attributed to DMSO treatment.     

A novel therapeutic combination for neuroblastoma

BACKGROUND:

High‐risk cases of neuroblastoma have poor survival rates, and novel therapies are needed. Vandetanib (ZD6474, Zactima) is an inhibitor of the vascular endothelial growth factor receptor, epidermal growth factor receptor, and rearranged during transfection (RET) tyrosine kinases, which have each been implicated in neuroblastoma pathogenesis. The authors hypothesized that vandetanib combined with 13‐cis‐retinoic acid (CRA), a differentiating agent used in most current neuroblastoma treatment regimens, would be effective against neuroblastoma tumor models.

METHODS:

The authors evaluated the effects of vandetanib with and without CRA on RET phosphorylation and on the proliferation and survival of human neuroblastoma cell lines in vitro. Using a subcutaneous mouse xenograft model of human neuroblastoma, they analyzed tumors treated with CRA, vandetanib, and the combination of vandetanib plus CRA for growth, gross and histologic appearance, vascularity, and apoptosis.

RESULTS:

Vandetanib treatment inhibited RET phosphorylation and resulted in induction of apoptosis in the majority of neuroblastoma cell lines in vitro, whereas CRA treatment induced morphologic differentiation and cell‐cycle arrest. Treatment with vandetanib plus CRA resulted in more significant reduction in neuroblastoma cell viability than either alone. In a mouse xenograft model, the combination of vandetanib with CRA demonstrated significantly more growth inhibition than either alone, via both reduction in tumor vascularity and induction of apoptosis.

CONCLUSIONS:

Vandetanib induces neuroblastoma tumor cell death in vitro and reduces tumor growth and vascularity in vivo. The combination of vandetanib with CRA was more effective in reducing tumor growth than either treatment alone. The antitumor effects of vandetanib plus CRA suggest a novel combination for use in neuroblastoma patients. Cancer 2010. © 2010 American Cancer Society.     

A novel retroviral mutagenesis screen identifies prognostic genes in RUNX1 mediated myeloid leukemogenesis

Using a novel retroviral shuttle vector approach we identified genes that collaborate with a patient derived RUNX1 (AML1) mutant. RUNX1 mutations occurs in 40% of myelodysplastic syndromes (MDS). MDS are a group of hematopoietic stem cell disorders that are characterized by dysplasia that often progress to acute myeloid leukemia (AML). Our goal was to identify genes dysregulated by vector-mediated genotoxicity that may collaborate with the RUNX1 mutant (D171N). D171N expressing cells have a survival and engraftment disadvantage and require additional genetic lesions to survive and persist. By dysregulating genes near the integrated vector provirus, the shuttle vector can promote transformation of D171N cells and tag the nearby genes that collaborate with D171N. In our approach, a gammaretroviral shuttle vector that expresses D171N is used to transduce CD105⁺, Sca-1⁺ mouse bone marrow. Mutagenized cells are expanded in liquid culture and vector integration sites from surviving cells are then identified using a retroviral shuttle vector approach. We repeatedly recovered integrated vector proviruses near genes (Itpkb, Ccdc12, and Nbeal2). To assess the prognostic significance of the genes identified we examined differential expression, overall survival, and relapse free survival of AML patients with alteration in the genes identified using The Cancer Genome Atlas (TCGA) AML data set. We found that ITPKB functions as an independent factor for poor prognoses and RUNX1 mutations in conjunction with ITPKB, CCDC12, and NBEAL2 have prognostic potential in AML.     

Unfavorable neuroblastoma prognostic factor NLRR2 inhibits cell differentiation by transcriptional induction through JNK pathway

The novel human gene family encoding neuronal leucine rich repeat (NLRR) proteins were identified as prognostic markers from our previous screening of primary neuroblastoma (NB) cDNA libraries. Of the NLRR gene family members, NLRR1 and NLRR3 are associated with the regulation of cellular proliferation and differentiation, respectively. However, the functional regulation and clinical significance of NLRR2 in NB remain unclear. Here, we evaluated the differential expression of NLRR2, where high expressions of NLRR2 were significantly associated with a poor prognosis of NB (P = 0.0009), in 78 NBs. Enforced expression of NLRR2 in NB cells enhanced cellular proliferation and induced resistance to retinoic acid (RA)‐mediated cell growth inhibition. In contrast, knockdown of NLRR2 exhibited growth inhibition effects and enhanced RA‐induced cell differentiation in NB cells. After RA treatment, NLRR2 expression was increased and correlated with the upregulation of c‐Jun, a member of the activator protein‐1 (AP‐1) family in NB cells. Moreover, the expressions of NLRR2 and c‐Jun were suppressed by treatment with a JNK inhibitor, which ameliorated the promoter activity of the NLRR2 gene while knockdown of c‐Jun reduced NLRR2 expression. We then searched AP‐1 binding consensus in the NLRR2 promoter region and confirmed c‐Jun recruitment at a consensus. Conclusively, NLRR2 must be an inducible gene regulated by the JNK pathway to enhance cell survival and inhibit NB cell differentiation. Therefore, NLRR2 should have an important role in NB aggressiveness and be a potential therapeutic target for the treatment of RA resistant and aggressive NB.     

Synergistic efficacy of a novel combination therapy controls growth of Bcl-x(L) bountiful neuroblastoma cells by increasing differentiation and apoptosis

Neuroblastoma is the most prevalent extracranial solid tumor mainly in pediatric patients. We explored the efficacy of the combination of 2[(3-[2,3-dichlorophenoxy]propyl)amino]ethanol (2,3-DCPE, a small molecule inhibitor of the anti-apoptotic protein Bcl-x(L)) and N-(4-hydroxyphenyl) retinamide (4-HPR, a synthetic retinoid) in inducing differentiation and apoptosis in human malignant neuroblastoma cells. Immunofluorescence confocal microscopy and flow cytometry showed that the highest level of Bcl-x(L) expression occurred in SK-N-DZ cells followed by SH-SY5Y and IMR-32 cells. Combination of 20 μM 2,3-DCPE and 1 μM 4-HPR acted synergistically in decreasing viability of SK-N-DZ and SH-SY5Y cells. In situ methylene blue staining and protein gel blotting showed the efficacy of this combination of drugs in inducing neuronal differentiation morphologically and also biochemically with upregulation of the neuronal markers such as neurofilament protein (NFP) and neuron specific enolase (NSE) and downregulation of the differentiation inhibiting molecules such as N-Myc and Notch-1 in SK-N-DZ and SH-SY5Y cells. Annexin V-FITC/PI staining showed the synergistic action of this combination therapy in increasing apoptosis in both cell lines. Protein gel blotting manifested that combination therapy increased apoptosis with downregulation of the anti-apoptotic proteins Bcl-x(L), Bcl-2 and Mcl-1 and upregulation of the pro-apoptotic proteins Bax, p53, Puma (p53 upregulated modulator of apoptosis), and Noxa, ultimately causing activation of caspase-3. In conclusion, our results appeared highly encouraging in advocating the use of 2,3-DCPE and 4-HPR as a novel combination therapy for increasing both differentiation and apoptosis in human malignant neuroblastoma cells having Bcl-x(L) overexpression.     

全反式维甲酸诱导神经母细胞瘤分化及TrkA剪接异构体表达的研究

目的：通过对NB细胞系SH-SY5Y进行体外实验,研究ATRA对NB细胞的增殖抑制与诱导分化作用,进而探讨TrkA剪接异构体在不同分化程度的SH-SY5Y细胞中的表达情况。方法：将SH-SY5Y细胞取对数生长期细胞培养分组,利用台盼蓝拒染计数活细胞,倒置相差显微镜观察细胞形态学变化。采用SYBR GreenⅠ实时荧光定量PCR方法检测TrkA三种剪接异构体的表达水平。结果：对照组活细胞数随着培养时间延长而增多,实验组中ATRA对SH-SY5Y的生长抑制作用在（0.1-10）μmol/L浓度范围内有剂量依赖关系。不同浓度的ATRA均可诱导SH-SY5Y细胞产生形态学上的变化,对照组细胞分化百分率随时间延长无明显变化,各时间段间比较,差异不显著（F=2.889,P=0.079）。TrkAⅠ/ⅡmRNA表达水平增加与ATRA浓度及作用时间呈正相关。TrkAⅢmRNA表达与ATRA浓度及作用时间呈负相关。结论：在SH-SY5Y细胞中,ATRA对细胞生长抑制作用呈明显的时间和剂量依赖关系;TrkAⅠ/Ⅱ表达与ATRA作用时间、剂量呈正相关;随着ATRA作用浓度及作用时间的增加,TrkAⅢmRNA表达降低。     

Soluble factors derived from neuroblastoma cell lines suppress dendritic cell differentiation and activation

Dendritic cells (DC) play a key role in the initiation of both antitumor immunity and immunological tolerance. It has been demonstrated that exposure to soluble factors produced by tumor cells modulates DC functions and induces tolerogenic DC differentiation. In this study, we investigated the effects of neuroblastoma cell line‐derived soluble factors on DC differentiation. Monocytes isolated from healthy volunteers were incubated with interleukin (IL)‐4 and granulocyte‐macrophage colony‐stimulating factor in the presence of culture supernatants from neuroblastoma cell lines. The culture supernatants from neuroblastoma cell lines, such as NLF and GOTO, partially blocked both downregulation of CD14 and upregulation of CD1a, and dramatically decreased IL‐12 and tumor necrosis factor (TNF)‐α production from mature DC, while no effect of SH‐SY5Y cell supernatant was noted. In addition, IL‐6 and IL‐10 production from monocytes was increased by the supernatants of NLF and GOTO cells at 24 hours after incubation. Furthermore, we evaluated DC functions through stimulation of invariant natural killer T (iNKT) cells. α‐Galactosylceramide‐pulsed DC co‐cultured with supernatants of NLF cells were unable to sufficiently stimulate iNKT cells. The decreased ability of iNKT cells to produce interferon (IFN)‐γ after stimulation with neuroblastoma cell line supernatant‐cultured DC was reversed by addition of IL‐12. CD40 expression and IL‐12 production in NLF‐sup‐treated DC were increased by addition of exogenous IFN‐γ. These results indicate that tolerogenic DC are induced in the neuroblastoma tumor microenvironment and attenuate the antitumor effects of iNKT cells. Interactions between iNKT cells and αGalCer‐pulsed DC have the potential to restore the immunosuppression of tolerogenic DC through IFN‐γ production.     

全反式维甲酸诱导神经母细胞瘤分化及TrkA剪接异构体表达的研究

目的:通过对NB细胞系SH-SY5Y进行体外实验,研究ATRA对NB细胞的增殖抑制与诱导分化作用,进而探讨TrkA剪接异构体在不同分化程度的SH-SY5Y细胞中的表达情况。方法:将SH-SY5Y细胞取对数生长期细胞培养分组,利用台盼蓝拒染计数活细胞,倒置相差显微镜观察细胞形态学变化。采用SYBR GreenⅠ实时荧光定量PCR方法检测TrkA三种剪接异构体的表达水平。结果:对照组活细胞数随着培养时间延长而增多,实验组中ATRA对SH-SY5Y的生长抑制作用在(0.1-10)μmol/L浓度范围内有剂量依赖关系。不同浓度的ATRA均可诱导SH-SY5Y细胞产生形态学上的变化,对照组细胞分化百分率随时间延长无明显变化,各时间段间比较,差异不显著(F=2.889,P=0.079)。TrkAⅠ/ⅡmRNA表达水平增加与ATRA浓度及作用时间呈正相关。TrkAⅢmRNA表达与ATRA浓度及作用时间呈负相关。结论:在SH-SY5Y细胞中,ATRA对细胞生长抑制作用呈明显的时间和剂量依赖关系;TrkAⅠ/Ⅱ表达与ATRA作用时间、剂量呈正相关;随着ATRA作用浓度及作用时间的增加,TrkAⅢmRNA表达降低。     

MRP1 gene expression level regulates the death and differentiation response of neuroblastoma cells.

We have previously reported a strong correlation between poor prognosis in childhood neuroblastoma (NB) patients and high-level expression of the transmembrane efflux pump, Multidrug Resistance-associated Protein (MRP1), in NB tumour tissue. In this study, we inhibited the endogenous expression of MRP1 in 2 different NB tumour cell lines by stably transfecting an MRP1 antisense expression vector (MRP-AS). Compared with control cells, MRP-AS transfectant cells demonstrated a higher proportion of dead and morphologically apoptotic cells, spontaneous neuritogenesis, and, increased synaptophysin and neurofilament expression. Bcl-2 protein expression was markedly reduced in MRP-AS cells compared to controls. Conversely, we found that the same NB tumour cell line overexpressing the full-length MRP1 cDNA in sense orientation (MRP-S) demonstrated resistance to the neuritogenic effect of the differentiating agent, all-trans-retinoic acid. Taken together, the results suggest that the level of MRP1 expression in NB tumour cells may influence the capacity of NB cells for spontaneous regression in vivo through cell differentiation and death.     

Malignant phenotype correlating with drug resistance in two human neuroblastoma cell lines

Summary The main cause for the failure of chemotherapeutic treatment of advanced cancer probably lies in the emergence of drug resistant clones. In the present study we compared the sensitivity to adriamycin (ADR) and the capacity of ADR uptake in two human neuroblastoma cell lines differing in properties relevant to metastatic potential, the GP₂ and MB, of low- and high-malignancy phenotype, respectively.Examination of the ADR effect onin vitro proliferative capacity of the two cell lines revealed a higher sensitivity of GP₂ as compared to the MB variant.Intracellular ADR accumulation was determined by fluorocytometry, spectrofluorometry and fluorescence microscopy. According to the three methods, the GP₂ line cells, representing a low-malignancy phenotype, had a higher uptake ability than the MB cells, possessing a phenotype of higher aggressiveness.The quantitative determination revealed that over a broad range of ADR concentrations, the GP₂ cells accumulated 2–3.5 folds the amount of cytotoxic agent penetrating the MB cells. The FACS analysis showed that the cell population of each of the variants consisted of two subpopulations varying in their ability to accumulate ADR. In the GP₂ line the high permeability subpopulation represented nearly half of the total cell population, whereas in the MB line this subpopulation represented a minority.The correlation observed between ADR uptake capacity and sensitivity to the cytotoxic agent, as evidenced by its effect on proliferative capacity, suggests that the resistance of the MB cells is due to a P-G-P modification-related mechanism.     

激活NGF/trkA信号传导通路引起NB细胞良性分化的研究

目的 :观察神经生长因子 (nervegrowthfactor ,NGF)与其高亲和性受体 (trkA)信号传导通路的激活 ,对神经母细胞瘤 (neu roblastoma ,NB)良性分化的影响。方法 :利用脂质体转染法将trkAcDNA重组质粒转染入人神经母细胞瘤SH SY5Y细胞系中 ,应用RT PCR技术鉴定转染后基因的表达 ,比较转染前后SH SY5Y细胞的分化程度及表达trkA的SH SY5Y细胞用NGF处理前后的分化程度。结果 :成功转染trkA基因并在SH SY5Y细胞中稳定表达 ,对照组及空载体组trkAPCR率分别为 0 43± 0 0 73 8和 0 44± 0 0 9,实验组为 2 69± 0 2 2 ,实验组与前两组比较差异有统计学意义 ,P <0 0 1;转染后SH SY5Y细胞的分化程度明显增加 ,用NGF处理后 ,其分化程度进一步增加。分化细胞的百分率实验组 1为 3 7 69± 1 75 ,实验组 2为 2 6 2 8± 1 3 4,对照组 18 43 5± 1 2 5 ,空载体组 17 61± 1 69。实验组 1与对照组及空载体组相比差异有统计学意义 ,P <0 0 1;实验组 2与对照组及空载体组相比差异有统计意义 ,P <0 0 5 ;实验组 2和实验组 1相比差异有统计学意义 ,P <0 0 1。结论 :NGF/trkA信号传导通路的激活能够引起NB细胞的良性分化 ,这一传导通路的激活可能是NB细胞良性逆转的重要因素。     

Merkel cell polyomavirus oncoproteins induce microRNAs that suppress multiple autophagy genes

Viruses can inhibit host autophagy through multiple mechanisms, and evasion of autophagy plays an important role in immune suppression and viral oncogenesis. Merkel cell polyomavirus (MCPyV) T-antigens are expressed and involved in the pathogenesis of a large proportion of Merkel cell carcinoma (MCC). Yet, how MCPyV induces tumorigenesis is not fully understood. Herein, we show that MCPyV T-antigens induce miR-375, miR-30a-3p and miR-30a-5p expressions, which target multiple key genes involved in autophagy, including ATG7, SQSTM1 (p62) and BECN1. In MCC tumors, low expression of ATG7 and p62 are associated with MCPyV-positive tumors. Ectopic expression of MCPyV small T-antigen and truncated large T-antigen (LT), but not the wild-type LT, resulted in autophagy suppression, suggesting the importance of autophagy evasion in MCPyV-mediated tumorigenesis. Torin-1 treatment induced cell death, which was attenuated by autophagy inhibitor, but not pan-caspase inhibitor, suggesting a potential role of autophagy in promoting cell death in MCC. Conceptually, our study shows that MCPyV oncoproteins suppress autophagy to protect cancer cells from cell death, which contribute to a better understanding of MCPyV-mediated tumorigenesis and potential MCC treatment.     

Treatment of advanced neuroblastoma: feasibility and therapeutic potential of a novel approach combining 131-I-MIBG and multiple drug chemotherapy

Biological and clinical observations suggest that initial marked reduction of resistant clones may be critical in any attempt to improve long-term results in advanced neuroblastoma (NB). The aim of this pilot study is to determine short-term toxicity and efficacy of a new therapeutic model based on the simultaneous use of multiple drug chemotherapy and specific irradiation using 131-I-MIBG. The study population consisted of 21 patients, from 1 to 8 years of age with good 131-I-MIBG uptake. 16 extensively pre-treated patients with refractory or relapsed disease were divided into 2 groups. In Group 1 (9 patients) the basic chemotherapy regimen consisted in cisplatin at the dose of 20 mg/m(2) i.v. per day infused over 2 h, for 4 consecutive days; on day 4 Cy 2 g/m(2) i.v. was administered over 2 h followed by Mesna. Group 2 (7 patients) was treated with basic chemotherapeutic regimen plus VP16 and Vincristine. VP16 at the dose of 50 mg/m(2) i.v. per day was administered as a 24 h infusion on days 1-3; Vincristine 1.5 mg/m(2) i.v. was administered on days 1 and 6. On day 10 a single dose of 131-I-MIBG (200 mCi) with a high specific activity (>1.1 GBq/mg) was administered to both Groups by i.v. infusion over 4-6 hours. A further 5 patients were treated at diagnosis: 2 with the same regimen as Group 1 and 3 with the same as Group 2. The severity of toxicity was graded according to World Health Organization (WHO) criteria. Assessment of tumour response was monitored 4-6 weeks after the beginning of combined therapy (CO-TH). Response was defined according to INSS (International Neuroblastoma Staging System) criteria. No extra-medullary toxicity was observed in any patient. Haematological toxicity was the only toxicity observed and seemed mainly related to chemotherapy. Myelosuppression was mild in the 5 patients treated at diagnosis. No serious infections or significant bleeding problems were observed. In the 16 resistant patients, 12 PR, 1 mixed response and 3 SD were obtained. In the 5 patients treated at diagnosis 2 PR, 1 CR and 2 VGPR were observed. No alteration in 131-I-MIBG uptake was observed after the chemotherapy preceding radio-metabolic treatment. The therapeutic results of this pilot regimen of CO-TH resulted in a high percentage of major response after only a single course in both resistant patients and patients treated at diagnosis. Because of the minimal toxicity observed in patients studied at diagnosis so far, there is room for gradual intensification of the treatment. It is to be hoped that this suggested novel approach may represent an important route of investigation to improve final outcome in patients with advanced NB.     

MYCN amplification in neuroblastoma: A paradigm for the clinical use of an oncogene

Increase of the dosage of cellular oncogenes by DNA amplification is a frequent genetic alteration of cancer cells. The presence of amplified cellular oncogenes is usually signalled by conspicuous chromosomal abnormalities, “double minutes” (DMs) or “homogeneously staining chromsomal regions” (HSRs). Some human cancers carry a specific amplified oncogene at high incidence. In neuroblastomas the amplification of MYCN has been found associated with aggressively growing cancers and is an indicator for poor prognosis. MYCN amplification is of predictive value for identifying neuroblastoma patiens that require specific therapeutic regimens and for identifying patients that will not benefit from chemotherapy. This has been a lecture presented on a Tempus-course (S-JEP 11198–96) “Harmonization of Ph. D. degree to EU standards”     

The synthetic retinoid RO 13-6307 induces neuroblastoma differentiation in vitro and inhibits neuroblastoma tumour growth in vivo

Retinoids modulate cell proliferation, differentiation and apoptosis in a variety of tumour cells including leukaemia and neuroblastoma, a childhood tumour of the sympathetic nervous system. 13-cis retinoic acid is in clinical use against minimal residual disease in neuroblastoma, where the effect seems to depend on dose, scheduling and tumour mass. Novel retinoids are searched for, to improve potency and lower toxicity. We investigated the effect of the synthetic retinoid Ro 13-6307 on neuroblastoma growth in vitro on SK-N-BE(2) and SH-SY5Y cells. Furthermore, effects on tumour growth and the toxicity profile were investigated in a rat xenograft model. Effects of Ro 13-6307 were compared to 13-cis RA (retinoic acid) in vitro and in vivo. Neuroblastoma cells treated with 1 microM Ro 13-6307 exhibited neuronal differentiation, decreased proliferation and accumulation of cells in G1 phase in at least the same magnitude as 5 microM 13-cis RA. No apoptosis was detected in vitro. Treatment of nude rats with neuroblastoma using Ro 13-6307, 0.12 mg p.o. daily, decreased neuroblastoma growth in vivo, in terms of tumour volume during treatment and tumour weight at sacrifice (p < 0.05). In contrast, Ro 13-6307, 0.08 mg p.o. daily, resulted in no significant reduction in tumour growth. All rats treated with Ro 13-6307 gained less weight than control rats, but they exhibited no other signs of toxicity. The toxicity profile of Ro 13-6307 was similar to what we found with 13-cis RA. Our preclinical results suggest that Ro 13-6307 may be a candidate retinoid for clinical oral therapy of neuroblastoma in children.