The Genetic Germline Background of Single and Multiple Primary Melanomas

Background: Melanoma has a complex molecular background and multiple genes are involved in its development and progression. The advent of next generation sequencing platforms has enabled the evaluation of multiple genes at a time, thus unraveling new insights into the genetics of melanoma. We investigated a set of germline mutations able to discriminate the development of multiple primary melanomas (MPM) vs. single site primary melanomas (SPM) using a targeted next generation sequencing panel. Materials and Methods: A total of 39 patients, 20 with SPM and 19 with MPM, were enrolled in our study. Next generation analysis was carried out using a custom targeted sequencing panel that included 32 genes known to have a role in several carcinogenic pathways, such as those involved in DNA repair, pigmentation, regulation of kinases, cell cycle control and senescence. Results: We found a significant correlation between PIK3CA:p.I391M and MPMs, compared to SPMs, p = 0.031 and a trend for the association between CYP1B1: p.N453S and SPMs, compared to MPMs (p = 0.096). We also found that both subgroups shared a spectrum of 9 alterations in 8 genes (CYP1B1: p.N453S, BAP1: p.C39fs, PIK3CA: p.I391M, CDKAL1: c.1226_1227TG, POLE: p.V1161fs, OCA2: p.R419Q, OCA2: p.R305W, MC1R: p.V60L, MGMT: p.L115F), which suggested that these genes may play a role in melanoma development. Conclusions: In conclusion, despite the small cohort of patients, we found that germline mutations, such as those of PIK3CAand CYP1B1, might contribute to the differential development of SPM and MPM.

Standardization of CTC AR-V7 PCR assay and evaluation of its role in castration resistant prostate cancer progression

BACKGROUND

Castration resistant prostate cancer (CRPC) represents the most aggressive status of this neoplastic disease, also characterized by the absence of biomarkers predictive of clinical outcome. New drugs as abiraterone or enzalutamide, affecting androgen receptor pathway at different levels, inhibit the proliferative advantage of prostate cancer cells with important long term benefits. Despite the advantages of this second-generation androgen deprivation therapy (ADT), resistance mechanisms, primitive or acquired, often develop. The existence of androgen receptor (AR) splice variants (AR-Vs), in particular AR-V7 expression detected in circulating tumor cells (CTCs), represents an example of acquired resistance, as evidenced in preclinical and clinical studies. Recent studies also have suggested the role of AR-V7 as a prognostic biomarker in mCRPC. In this field, hot topics are the methodology used to isolate CTC and the assay for AR-V7 measurement. Our study aims to develop a standardized operating procedure (SOP) to evaluate AR-V7 in CRPC.

METHOD

The application of a realized cell based Reference Sample as Standardized Quality Control tool for CTC-AR-V7 assay has been shown. Then the development, the performance evaluation and contextualization in a clinical setting of this standardized operating procedure (SOP) have been reported to evaluate the prognostic biomarker AR-V7 in metastatic prostate cancer.

RESULTS AND CONCLUSIONS

The standardized procedure has high sensitivity and specificity and enables the detection and quantification of the spliced variant with respect to the full length AR (AR-FL) mRNA in CTC DNA purified from the blood of patients with CRPC. This procedure has been further validated in a consecutive series of patients with mCRPC, confirming its role as prognostic biomarker.

Id proteins at the cross-road of development and cancer

A large body of evidence has been accumulated that demonstrates dominant effects of Id proteins on different aspects of cellular growth. Generally, constitutive expression of Id not only blocks cell differentiation but also drives proliferation. In some settings, it is sufficient to render cells immortal or induce oncogenic transformation. The participation of Id proteins in advanced human malignancy, where they are frequently deregulated, has been dramatically bolstered by the recent discovery that Id exert pivotal contributions to many of the essential alterations that collectively dictate malignant growth. Relentless proliferation associated with self-sufficiency in growth signals and insensitivity to growth inhibitory signals, sustained neoangiogenesis, tissue invasiveness and migration capabilities of tumor cells all share dependency on the unlimited availability of Id proteins. It is remarkable that many of these features recapitulate those physiologically propelled by Id proteins to support normal development. We propose that the participation of Id in multiple fundamental traits of cancer may be the basis for unprecedented therapeutic opportunities.

Distinct mechanisms of cell cycle arrest control the decision between differentiation and senescence in human neuroblastoma cells

Retinoic acid (RA) induces cell cycle arrest and differentiation of human neuroblastoma (NB) cells. Typically, NB cells differentiate along the neuronal lineage, but quiescent, "flat" cell types frequently have been described after treatment with differentiating agents. Two indistinguishable subclones of the cell line SK-N-SH, SK-N-SH-N (SH-N) and SK-N-SH-F (SH-F), display dramatically different responses to RA. In SH-N, RA induces neuronal differentiation, but in SH-F it transforms the small neuroblastic cells into large, flattened, epithelium-like cells. Here we analyze the mechanistic basis for the different effects of RA in the two NB subclones. First, we show that the flattened RA-treated SH-F expresses markers of cells undergoing replicative senescence. Inhibition of DNA synthesis by RA is significantly more rapid in SH-F than in SH-N. SH-F, which expresses basal amounts of p16(INK4A), responds to RA with elevation of p18(INK4C), marked down-regulation of cyclin D1, and swift inhibition of cyclin D-dependent kinases (cdks). Conversely, after addition of RA, SH-N retains cell cycling due to high expression of cyclin D1, the absence of Ink4 inhibitors, and accumulation of p21(Cip1). These changes result in sustained cdk activity. Accordingly, overexpression of p21(Cip1) but not p16(INK4A) induces neuronal differentiation of untreated NB cells. We propose that rapid inhibition of cdks by RA in NB leads to early cell cycle arrest, prevents neuronal differentiation, and results in a senescence-like state.

Evidence that Myc isoforms transcriptionally repress caveolin-1 gene expression via an INR-dependent mechanism

The c-Myc oncoprotein contributes to oncogenesis by activating and repressing a repertoire of genes involved in cellular proliferation, metabolism, and apoptosis. Increasing evidence suggests that the repressor function of c-Myc is critical for transformation. Therefore, identifying and characterizing Myc-repressed genes is imperative to understanding the mechanisms of Myc-induced tumorigenesis. Here, we employ NIH 3T3 cell lines harboring c-Myc-ER or N-Myc-ER to dissect the relationship between Myc activation and caveolin-1 expression. In this well-established inducible system, treatment with estrogen like molecules, such as tamoxifen, leads to activation of Myc, but in a tightly controlled fashion. Using this approach, we show that Myc activation induces the repression of caveolin-1 expression at the transcriptional level. We also provide two independent lines of evidence suggesting that caveolin-1 is a direct target of Myc: (i) the effect of Myc activation on caveolin-1 expression is independent of new protein synthesis, as revealed through the use of cycloheximide; and (ii) Myc-mediated repression of the caveolin-1 promoter is dependent on an intact INR sequence. Moreover, we show that expression of caveolin-1, via an adenoviral vector approach, can suppress cell transformation that is mediated by Myc activation. In support of these observations, treatment with an adenoviral vector harboring anti-sense caveolin-1 specifically potentiates transformation induced by Myc activation. Taken together, our results indicate that caveolin-1 is a direct target of Myc repression, and they also provide evidence for an additional mechanism by which Myc repression can elicit a malignant phenotype.

Id2 is a retinoblastoma protein target and mediates signalling by Myc oncoproteins

In mammalian cells, Id proteins coordinate proliferation and differentiation. Id2 is a dominant-negative antagonist of basic helix-loop-helix transcription factors and proteins of the retinoblastoma (Rb) family. Here we show that Id2-Rb double knockout embryos survive to term with minimal or no defects in neurogenesis and haematopoiesis, but they die at birth from severe reduction of muscle tissue. In neuroblastoma, an embryonal tumour derived from the neural crest, Id2 is overexpressed in cells carrying extra copies of the N-myc gene. In these cells, Id2 is in molar excess of the active form of Rb. The overexpression of Id2 results from transcriptional activation by oncoproteins of the Myc family. Cell-cycle progression induced by Myc oncoproteins requires inactivation of Rb by Id2. Thus, a dual connection links Id2 and Rb: during normal cell-cycle, Rb prohibits the action of Id2 on its natural targets, but oncogenic activation of the Myc-Id2 transcriptional pathway overrides the tumour-suppressor function of Rb.

Influence of cisplatin and doxorubicin on 125I-meta-iodobenzylguanidine uptake in human neuroblastoma cell lines

The combination of 131I-meta-iodobenzylguanidine (MIBG) with chemotherapy has recently been employed in the treatment of advanced stage neuroblastoma with encouraging results. However, the mechanisms underlying the interaction between these two different modalities of treatment have not yet been explored. In this study, human neuroblastoma cell lines pretreatment with cisplatin and doxorubicin increased cellular 125I-MIBG accumulation in a dose-dependent manner. Cell cycle analysis showed that increased 125I-MIBG accumulation correlated with the drug-induced G2/M phase block. Northern blot analysis demonstrated an increase in gene expression of the noradrenaline transporter induced by doxorubicin, but not by cisplatin treatment. Increased 125I-MIBG accumulation was also observed in murine xenografts of the human neuroblastoma cell line SK-N-DZ or BE(2)M17 treated intraperitoneally (i.p.) with cisplatin or doxorubicin, respectively. These results suggest that the combination of 131I-MIBG and these drugs could selectively increase radiation doses delivered to neuroblastomas.

Diagnostic imaging of primitive neuroectodermal tumour of the chest wall (Askin tumour)

OBJECTIVES

To describe the radiological features of primitive neuroectodermal tumour (PNET) of the chest wall (Askin tumour) at diagnosis and to analyse the radiological changes occurring as a consequence of treatment and during follow-up.

MATERIALS AND METHODS

Nine children with histologically proven PNET were studied. At diagnosis, all patients underwent chest X-ray (CXR), chest CT and bone scintigraphy; three patients also had MR and three had US. During treatment and follow-up, CT was performed in all patients.

RESULTS

CT demonstrated a solid heterogeneous chest wall mass in all children at diagnosis and six had a rib lesion. Small nodular densities in the extra-pleural fat were identified in three patients at diagnosis. US, performed in three patients, excluded tumour infiltration of the lung or diaphragm, which had been suspected on CT. On MR, the lesions showed high signal intensity in T1-weighted/proton-density images and intermediate/high signal intensity in T2-weighted images compared with muscle. Minimal chest wall involvement was demonstrated in one case by MRI. Extensive necrosis of tumour mass with pseudo-cystic appearance was documented in the five patients who underwent chemotherapy. Macroscopically complete resection was performed in five patients but there was early local recurrence after surgery in two, identified by CT in one and by MR in the other.

CONCLUSIONS

PNET of the chest wall should be considered in a child with a chest wall mass. CT is valuable for evaluating tumour extension at diagnosis, the effects of chemotherapy and assessing tumour recurrence after surgery. However, CT can overestimate pleural, lung or diaphragmatic infiltration, which are better evaluated by US. MR was superior to CT in the evaluation of tumour extension in one of three patients and may be considered complementary to CT, particularly in very large chest wall tumours.

Veno-occlusive disease of the liver in right-sided Wilms' tumours

Veno-occlusive disease of the liver (VOD) is an important complication in children with Wilms' tumour. Although in most patients this complication resolves uneventfully, fatal cases have been reported. Several observations strongly suggest that actinomycin-D is the likeliest cause of VOD in Wilms' tumour, but VOD seems to be rather uncommon in other malignancies treated with chemotherapy including actinomycin-D. The present case of VOD and the review of the literature stress the pathogenetic and clinical implications of VOD in the presence of a Wilms' tumour treated with actinomycin-D, originating in the right kidney. Greater awareness of this 'predisposing factor' may alert paediatricians to the presence of minimal signs of the syndrome.

Cranial irradiation and permeability of blood-brain barrier to cytosine arabinoside in children with acute leukemia

Cranial irradiation (CI) is an effective way to prevent central nervous system (CNS) leukemia in children with acute leukemia (AL). However, it is still unclear whether the antileukemic effect of CI is mediated by alteration of blood-brain barrier (BBB) permeability and consequent increased levels of systemically administered drugs or whether it simply results from a direct cytolytic effect on leukemic cells in the meninges at diagnosis. We evaluated the influence of CI on BBB permeability to 1-beta-D-arabinofuranosylcytosine (ara-C) in 23 children with AL undergoing CI for CNS leukemia prophylaxis. CI was administered at 18 Gy (16 patients) and 24 Gy (7 patients). ara-C levels were measured in cerebrospinal fluid (CSF) and plasma before, during, and after CI. Two doses were evaluated: 75 mg/m2/day (12 patients) and 480 mg/m2/day (11 patients). CSF and plasma ara-C levels were measured when steady state was achieved. CSF:plasma ratios, obtained before, during, and after CI, were compared by an ANOVA model for repeated measures and by Tukey's test. At the 75-mg/m2/day dose, the mean values of ara-C CSF:plasma ratios before, during, and after CI were 0.20, 0.27, and 0.27, respectively. At the 480-mg/m2/day dose, the mean CSF:plasma ratios before, during, and after CI were 0.09, 0.12, and 0.13, respectively. No significant differences were observed when CSF:plasma ratios were compared before and during, during and after, and before and after CI. Our results indicate that CI at the doses used for CNS prophylaxis in AL does not significantly alter the BBB as far as ara-C is concerned.

Optimal use of the 131-I-metaiodobenzylguanidine and cisplatin combination in advanced neuroblastoma

Neuroblastoma (NB), a childhood radiosensitive tumor, is very aggressive and malignant, in its disseminated form, despite very intensive chemotherapy, prognosis continues to be dismal. Owing to its capacity to concentrate in NB lesions, large doses of 131-I-MIBG, have given very encouraging therapeutic results in patients resistant to conventional therapy as well as at diagnosis. We recently reported the first attempt in combination therapy (CO-TH) using 131-I-MIBG and cisplatin. This new form of CO-TH appears very effective in obtaining a rapid and excellent response in relapsed patients. In this report, we describe the results of further experience with CO-TH in disseminated NB. We have attempted to verify to what extent interaction between the effects of the two agents may produce therapeutic benefit, and we have sought the optimization of CO-TH use. Three stage IV NB patients were treated with CO-TH. The following treatment schedule, was planned: day 1, cisplatin 50 mg/m3 i.v. over 6 h; day 2, 131-I-MIBG 100-130 mCi at high specific activity (-1.1 Gbq/mg) i.v. over 6 h followed, a week later, by the same treatment combination. The therapeutic results were encouraging. However, hematological toxicity continued to represent a major limiting factor. In view of the overall effectiveness of CO-TH, at the price of lasting hematological toxicity, it may be indicated as a consolidation regimen some time before conditioning chemotherapy for autologous bone marrow transplantation.

Id2 specifically alters regulation of the cell cycle by tumor suppressor proteins

Cells which are highly proliferative typically lack expression of differentiated, lineage-specific characteristics. Id2, a member of the helix-loop-helix (HLH) protein family known to inhibit cell differentiation, binds to the retinoblastoma protein (pRb) and abolishes its growth-suppressing activity. We found that Id2 but not Id1 or Id3 was able to bind in vitro not only pRb but also the related proteins p107 and p130. Also, an association between Id2 and p107 or p130 was observed in vivo in transiently transfected Saos-2 cells. In agreement with these results, expression of Id1 or Id3 did not affect the block of cell cycle progression mediated by pRb. Conversely, expression of Id2 specifically reversed the cell cycle arrest induced by each of the three members of the pRb family. Furthermore, the growth-suppressive activities of cyclin-dependent kinase inhibitors p16 and p21 were efficiently antagonized by high levels of Id2 but not by Id1 Id3. Consistent with the role of p16 as a selective inhibitor of pRb and pRb-related protein kinase activity, p16-imposed cell cycle arrest was completely abolished by Id2. Only a partial reversal of p21-induced growth suppression was observed, which correlated with the presence of a functional pRb. We also documented decreased levels of cyclin D1 protein and mRNA and the loss of cyclin D1-cdk4 complexes in cells constitutively expressing Id2. These data provide evidence for important Id2-mediated alterations in cell cycle components normally involved in the regulatory events of cell cycle progression, and they highlight a specific role for Id2 as an antagonist of multiple tumor suppressor proteins.

Differentiation of neuroblastoma enhances Bcl-2 expression and induces alterations of apoptosis and drug resistance

Recent evidence suggests that resistance to antineoplastic therapy may result from mutations in genes mediating the apoptotic response to DNA damage. To determine the effects of epigenetic changes on tumor responsiveness to cytotoxic agents inducing DNA damage, we examined the chemosensitivity of neuroblastoma (NB) after differentiation by retinoic acid (RA). Differentiation of the cell lines SH-SY5Y and SMS-KCNR by RA abolished the cytotoxic effects of adriamycin (Adr) and cisplatin. Chemoresistance was not the result of decreased proliferation induced by RA because: (a) growth arrest by nutrient deprivation did not affect sensitivity; (b) growth arrested NB cell lines, which did not differentiate, remained chemosensitive; and (c) RA concentrations which promoted differentiation without affecting growth, induced resistance. Apoptosis characterized NB cells responding to Adr, although differentiated SH-SY5Y did not apoptose and were resistant to Adr and cisplatin. Marked induction of bcl-2 in NB cells followed RA-induced differentiation, whereas in cell lines failing to differentiate, bcl-2 was not detected. Our data indicate that NB differentiation induces drug resistance after a loss of the apoptotic response to antineoplastic drugs and suggest that bcl-2 overexpression is an important mechanism of resistance in differentiated tumor cells.

Carboplatin in childhood medulloblastoma/PNET: feasibility of an in vivo sensitivity test in an "up-front" study

Sixteen patients with high risk MB/PNET at diagnosis were included in a pilot study employing carboplatin (CBDCA) as a single drug prior to conventional therapy. The main goal of the study was to identify in a short-term trial a significant response that would predict further response to CBDCA in the single patient. Exploration of CBDCA activity was focused on response after the first course as compared to the response following the second course. A course consisted of CBDCA 600 mg/m2 on days 1 and 2 administered in a 1 h infusion to be repeated 3-4 weeks later. After two cycles we observed 1 CR and 9 PR, that is a 62% response rate. The first course resulted in 5 PR, 5 MR, 5 SD, and 1 PD; after the subsequent course in all responding patients, response persisted or improved whereas in no patient with SD any improvement was observed. The correlation of response to the first course with response to the second course was statistically significant (P = 0.0009). The main toxicity of the single course was hematologic and consisted of rapidly reversible grade 3-4 neutropenia and thrombocytopenia in 94% of patients. Pharmacokinetic studies showed a very limited interpatient variability of both Cmax 57.6 +/- 9.9 micrograms/ml) and AUC (15.3 +/- 1.5 mg/ml.min) of free CBDCA, which eliminates an important variable in the evaluation of response. In conclusion, this "in vivo test" appears effective, reasonably safe, and reproducible in identifying patients likely to benefit from CBCDA: after a period of time as short as 3-4 weeks following the first course, multidrug chemotherapy including CBDCA may be employed in the responding patients, whereas an alternative regimen would be indicated in the non-responding patients.

Release mechanisms of [125I]meta-iodobenzylguanidine in neuroblastoma cells: evidence of a carrier-mediated efflux

[131I]metaiodobenzylguanidine ([131I]MIBG) is selectively taken up and stored by tumours derived from the neural crest, and is used for diagnosis and treatment of neuroblastoma (NB). The antitumoral effect of [131I]MIBG is closely related to the intracellular level of the radiopharmaceutical compound, which is dependent on uptake and storage/release mechanisms. While MIBG uptake is well characterised, storage and release mechanisms are still controversial. In order to better characterise [125I]MIBG release mechanisms, we studied the basal and stimulated efflux of [125I]MIBG in the human NB cell line, SH-SY5Y, preloaded with 0.1 microM [125I]MIBG for 1 h. We found that [125I]MIBG basal efflux is highly temperature-dependent, that [125I]MIBG release, induced by cell depolarisation with high potassium, is mainly calcium-independent, and induced by exchange with cold MIBG or noradrenaline, inversion of the sodium gradient across the cell membrane by veratridine by substitution of sodium chloride with equimolar concentration of lithium chloride. The exposure of NB cells to imipramine, an Uptake-1 inhibitor, also produces a net stimulatory effect on [125I]MIBG release. However, when used in association with other releasing stimuli, such as higher levels of intracellular sodium or external agonists, imipramine abolishes the consequent increase of [125I]MIBG release. Our findings suggest that stimulated [125I]MIBG release is mediated by a carrier, most probably the uptake carrier working in a reverse mode, while a minimal fraction of [125I]MIBG is released by an exocytotic mechanism.

A new approach in the treatment of stage IV neuroblastoma using a combination of [131I]meta-iodobenzylguanidine (MIBG) and cisplatin

The outlook for disseminated neuroblastoma (NB) continues to be dismal. NB is a radiosensitive tumour. Owing to its high concentration in NB lesions, [131I]meta-iodobenzylguanidine [131I]MIBG has the potential for specifically delivering very large radiation doses to the malignant cells. Encouraging results have been reported with [131I]MIBG used alone in patients resistant to conventional therapy and at diagnosis. We report the first attempt to explore the integration of this new treatment modality with chemotherapy. Among the drugs effective in NB, cisplatin was chosen because of its high degree of activity against NB, its mild haematological toxicity and the known synergism between cisplatin and radiation. 4 patients, 3 with relapsed, heavily pre-treated, progressive stage IV NB, and 1 with stage IV NB at diagnosis, all with a good [131I]MIBG uptake, were investigated with combined therapy (CO-TH). Two complete remissions and one partial remission were observed in these patients 4-6 weeks following only a single course of both cisplatin and [131I]MIBG at "standard" dosage. The only toxicity was haematological, which was significant and relatively long-lasting, but was not associated with any serious infections or bleeding tendency. The general condition of these patients during the entire study period was excellent. The fourth patient, investigated at diagnosis with a modified less intensive treatment, obtained a partial remission with mild haematological toxicity. During the subsequent courses of intensive multidrug chemotherapy, this patient showed haematological toxicity comparable with that experienced by patients treated with an identical drug combination, but without previous treatment with CO-TH. The provisional conclusion of this ongoing study is that this new form of CO-TH appears most effective in obtaining a rapid and excellent response in heavily pretreated relapsed patients with progressive disease, and should be further investigated in earlier stages of the disease.

Clinical pharmacokinetics of carboplatin in children

The present study was undertaken to evaluate in children the plasma pharmacokinetics of free carboplatin given at different doses and schedules and to evaluate the inter- and intrapatient variability and the possible influence of schedule on drug exposure. A total of 35 children (age range, 1-17 years) with malignant tumors were studied. All patients had normal renal function (creatinine clearance corrected for surface body area, above 70 ml min-1 m-2; range, 71-151 ml min-1 m-2) and none had renal involvement by malignancy. Carboplatin was given at the following doses and schedules: 175, 400, 500, and 600 mg/m2 given as as a 1-h infusion; 1,200 mg/m2 divided into equal doses and infused over 1 h on 2 consecutive days; and 875 and 1,200 mg/m2 given as a 5-day continuous infusion. A total of 57 courses were studied. Carboplatin levels in plasma ultrafiltrate (UF) samples were measured both by high-performance liquid chromatography and by atomic absorption spectrophotometry. Following a 1-h infusion, carboplatin free plasma levels decayed biphasically; the disappearance half-lives, total body clearance, and apparent volume of distribution were similar for different doses. In children with normal renal function as defined by creatinemia and blood urea nitrogen (BUN) and creatinine clearance, we found at each dose studied a limited interpatient variability of the peak plasma concentration (Cmax) and the area under the concentration-time curve (AUC) and a linear correlation between the dose and both Cmax (r = 0.95) and AUC (r = 0.97). The mean value +/- SD for the dose-normalized AUC was 13 +/- 2 min m2 l-1 (n = 57).2+ The administration schedule does not seem to influence drug exposure, since prolonged i.v. infusion or bolus administration of 1,200 mg/m2 achieved a similar AUC (13.78 +/- 2.90 and 15.05 +/- 1.44 mg ml-1 min, respectively). In the nine children studied during subsequent courses a limited interpatient variability was observed and no correlation (r = 0.035) was found between AUC and subsequent courses by a multivariate analysis of dose, AUC, and course number. The pharmacokinetic parameters were similar to those previously reported in adults; however, a weak correlation (r = 0.52, P = 0.03) between carboplatin total body clearance and creatinine clearance varying within the normal range was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

The helix-loop-helix protein Id-2 enhances cell proliferation and binds to the retinoblastoma protein

Cell growth and differentiation are usually antagonistic. Proteins of the basic helix-loop-helix (bHLH) family bind DNA and play important roles in the differentiation of specific cell types. Id proteins heterodimerize with bHLH transcription factors, blocking their activation of lineage-specific gene expression and thereby inhibiting cellular differentiation. To examine the effect of Id-2 on cell proliferation, we overexpressed Id-2 in the human osteosarcoma cell line U2OS. Id-2 expression in U2OS reduced the serum requirement for growth and stimulated cellular proliferation by shortening the doubling time and increasing the percentage of cells in S phase. We demonstrated that Id-2 expression was able to reverse the inhibition of cellular proliferation and the block in cell cycle progression mediated by the product of the retinoblastoma tumor suppressor gene pRB. This effect was not associated with changes in the state of pRb phosphorylation in transfected cells. In vitro, unphosphorylated pRb from cell lysates specifically bound Id-2 but was not able to bind a mutated form of Id-2 lacking the HLH domain that also did not antagonize the growth arrest by pRb. In vitro-synthesized pRb containing mutations within the E1A/large T-binding pocket did not bind Id-2. However, wild-type pRb was able to bind to a region of Id-2 corresponding to only the HLH domain. In vivo, a physical association between Id-2 and pRb was seen in cross-linked extracts from SAOS-2 cells transfected with Id-2 and pRb. Our data identify a role for Id-2 in the regulation of cellular proliferation and suggest that the interaction between Id-2 and pRB is a molecular pathway over which synchronous changes in growth and differentiation are mediated in vivo.

Uptake and storage of m-iodobenzylguanidine are frequent neuronal functions of human neuroblastoma cell lines

The mechanisms of the uptake and release of m-iodobenzylguanidine (MIGB) have been studied in 5 neuroblastoma (NB) cell lines and in 4 clonal NB sublines with a homogeneous phenotype. A specific uptake system for MIBG was found in 8 of 9 NB cell lines or subpopulations. The uptake was characterized by temperature dependency, high affinity, saturability, sodium dependency, and imipramine sensitivity. The majority of NB cell lines that possessed a specific uptake system for MIBG were also able to efficiently store the incorporated drug. However, 3 NB cell lines were identified without the ability to retain high levels of MIBG, despite the presence of a specific uptake system. We also report that a clonal subline, SH-EP1, which has a nonneuroblastic phenotype, failed both MIBG uptake and retention. Conversely, the parental cell line, SK-N-SH, and the neuroblastic subline SH-SY5Y possessed both a specific uptake system and the ability to store MIBG. In addition, the induction of neuronal differentiation with retinoic acid increased the velocity of uptake and the storage efficiency for MIBG in the clonal subline SH-SY5Y. We conclude that MIBG uptake and storage should be considered to be frequent but independent neuronal functions of human NB cells.

Critical observations on neuroblastoma treatment with 131-I-metaiodobenzylguanidine at diagnosis

Results of treatment with 131-I-Metaiodobenzylguanidine (131-I-MIBG) in patients with resistant neuroblastoma appear encouraging if one considers that most of the patients had far advanced, intensively pre-treated disease. To further explore the potential role of this new drug in untreated patients, we treated 3 children with stage III neuroblastoma. All three of our cases received 131-I-MIBG at relatively low dose with the complete disappearance of the tumor mass in case 1, whereas in cases 2 and 3 CT scan showed a significant reduction of the tumor mass and, interestingly enough, no evidence of 131-I-MIBG uptake of a tracer dose in the remaining tumor. Particularly, in case 2, the persistence and subsequent progression of part of the tumor mass without 131-I-MIBG uptake after a therapeutic dose of 131-I-MIBG, which apparently destroyed the 131-I-MIBG-positive cell population, clearly suggest heterogeneity at diagnosis, with a dual neuroblastoma cell population, one with 131-I-MIBG uptake and the other without. Besides the biological implications of the 131-I-MIBG uptake heterogeneity in neuroblastoma at diagnosis, our findings suggest that in stage III neuroblastoma patients even a relatively small dose of 131-I-MIBG administered at diagnosis is sufficient to destroy either the primary tumor completely (case 1) or the part of the tumor (case 2 and 3) which shows 131-I-MIBG uptake, without any significant hematologic toxicity. Furthermore, a single course of 131-I-MIBG at the dosage employed does not appear to jeopardize the subsequent use of chemotherapy. In conclusion, if our data are confirmed by further investigation, 131-I-MIBG may be included as a front line drug shortly followed by chemotherapy in future treatment strategies of advanced neuroblastoma without or with minimal bone marrow infiltration.

Cerebrospinal fluid pharmacokinetics of carboplatin in children with brain tumors

The pharmacokinetics of carboplatin in cerebrospinal fluid (CSF) and plasma was studied in five children with brain tumors (four medulloblastomas and one ependimoblastoma) who underwent preirradiation treatment with carboplatin. Carboplatin pharmacokinetics was studied following the administration of 600 mg/m2 as a 1-h infusion. Four children were treated a few weeks after surgery, whereas one child with an unresectable tumor was treated prior to surgery. All patients had a ventricular-peritoneal CSF shunt connected to a subcutaneous reservoir. Total platinum and free carboplatin were measured. The mean AUC values for free carboplatin in CSF and plasma were 2.29 +/- 1.20 and 8.18 +/- 1.27 mg ml-1 min, respectively. The mean ratio of CSF AUC to plasma AUC was 0.28 (range, 0.17-0.46). Both plasma peak levels and AUC values showed limited interpatient variability. On the other hand, carboplatin levels in CSF showed substantial interpatient variability, with a greater than 5-fold difference in peak levels and a 3-fold difference in AUC values being recorded. The interpatient difference in CSF pharmacokinetics may have been related at least in part to the different anatomical alterations induced by the surgical procedures or by the presence of a large tumor mass. In the four evaluable patients exhibiting macroscopic residual tumor, we observed one complete remission (CR) and two partial remissions (PR) following two cycles that consisted of two doses of 600 mg/m2 carboplatin given on 2 consecutive days (total dose, 1200 mg/m2) and were separated by a 1-month interval. These results may give some indication as to the optimal dose and schedule for carboplatin administration in the treatment of primitive neuroectodermic tumors (PNET).

Biology of metaiodobenzylguanidine interactions with human neuroblastoma cells

[131I]Metaiodobenzylguanidine (131I-MIBG) is selectively taken up and stored by tumors derived from the neural crest and is utilized in the diagnosis and treatment of neuroblastoma (NB). Variable MIBG uptake has been observed, although the underlying mechanisms are not known. We have studied the uptake kinetics of 125I-MIBG and uptake characteristics of NB cell clones with different phenotypes (SH-SY5Y and SH-EP1, the neuroblastic and the substrate-adherent sublines of SK-N-SH respectively, BE(2)-M17 and LA-N-1n with neuroblastic phenotype). We have been able to correlate the MIBG uptake with the neuroblastic phenotype: a specific uptake system satisfying all the characteristics of the neuronal uptake-1 (temperature dependency, sodium dependency, high affinity, saturability and imipramine sensitivity) was observed in all the neuroblastic sublines. In contrast, MIBG accumulation was a passive diffusion phenomenon in the substrate-adherent clone SH-EP1. In addition, terminal neuronal differentiation induced in SH-SY5Y by retinoic acid caused a marked increase of the uptake and retention of MIBG. Our findings may be pertinent to an understanding of the variability of the MIBG uptake in vivo.

[131I]metaiodobenzylguanidine in neuroblastoma patients at diagnosis

Treatment of resistant neuroblastoma with high dosage [131I]metaiodobenzylguanidine (131I-MIBG) appears effective since encouraging results have been obtained so far even in patients with very advanced, intensively pre-treated disease. We have already reported a stage III NB patient treated at diagnosis, who is at present in complete remission with a 4-year follow-up. To further explore the potential role of this new drug in untreated patients, we administered radionuclide to two children with stage III neuroblastoma. Both cases received 131I-MIBG at relatively low doses, and showed a significant reduction of the tumor mass and, interestingly enough, no evidence of 131I-MIBG uptake of a tracer dose in the remaining tumor. Particularly in case 1, the permanence and subsequent progression of the part of the tumor mass without 131I-MIBG uptake, after therapeutic doses of 131I-MIBG which apparently destroyed the 131I-MIBG-positive cell population, clearly suggest heterogeneity at diagnosis, with a dual neuroblastoma cell population, one with 131I-MIBG uptake and the other without. Aside from the biological implications of the heterogeneous MIBG uptake in neuroblastoma at diagnosis, our findings suggest that in stage III neuroblastoma patients even a relatively small dose of 131I-MIBG administered at diagnosis is sufficient to either completely destroy the primary tumor, as reported by our group, or to destroy that part of the tumor which shows 131I-MIBG uptake (as in the present cases), without any significant hematologic toxicity. Furthermore, a single course of 131I-MIBG at the dosage employed here does not appear to jeopardize the subsequent use of chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Cranial irradiation and cerebrospinal fluid levels of 6-mercaptopurine in children with acute leukemia

We measured 6-mercaptopurine levels in the cerebrospinal fluid and plasma of 15 children undergoing treatment for acute leukemia. Plasma and cerebrospinal fluid samples obtained by lumbar puncture were collected before, during, and after cranial irradiation in order to evaluate a possible change in blood-brain barrier permeability to orally administered 6-mercaptopurine. Considerable interpatient variability has been observed in both plasma and cerebrospinal fluid 6-mercaptopurine levels. No statistical differences in the 6-mercaptopurine cerebrospinal fluid levels under the three different conditions could be detected. Our data suggest that cranial irradiation does not significantly influence the cerebrospinal fluid levels.

The diagnostic and therapeutic utility of radioiodinated metaiodobenzylguanidine (MIBG). 5 years of experience

The authors' experience of more than 5 years in the diagnostic and therapeutic use of radioiodinated MIBG in neural crest tumors is reported. 123I/131I-MIBG scintigraphy was performed in 158 patients: 75 suspected (24 proven) pheochromocytomas (pheos), 43 neuroblastomas (NB), 20 medullary thyroid carcinomas (MTC), 6 ganglioneuromas, 5 carcinoids and 1 insulinoma. Eight cases of tumors not originating from the neural crest were also investigated. The diagnostic sensitivity of the method was above 90% both in pheos and NB (primary tumors and bone metastases). The examination was less effective in localizing MTC (sensitivity = 64.4% in primary or residual/recurrent tumors). The scintigraphic outcome was negative in ganglioneuromas, carcinoids and insulinoma. Specificity was very high (greater than 95%), and no false positive results were found in tumors not deriving from the neural crest. 131I-MIBG treatment was administered to four patients with malignant pheo, nine with NB and four with MTC. Therapy resulted in a complete response in one pheo, two NB and one MTC treated after surgery or at diagnosis (one NB); it gave partial response and prolonged remission in five advanced cases (one pheo, two NB and two MTC); it resulted in temporary stabilization of the disease in one pheo and two NBs; it was ineffective in four cases.

131I-metaiodobenzylguanidine in the treatment of neuroblastoma at diagnosis

Radioactive metaiodobenzylguanidine (131I-MIBG) is taken up specifically by neuroblastoma cells and appears to represent a new treatment modality in patients with advanced neuroblastoma. Taking into account the fact that all patients so far treated were heavily pretreated and resistant to chemotherapy, the results obtained appear encouraging. In order to explore further the potential role of this new drug in untreated patients, we treated with 131I-MIBG a child with stage III neuroblastoma at diagnosis. We observed the complete disappearance of a large abdominal tumor mass after a relatively low dosage of 131I-MIBG, with minimal hematologic toxicity. No further treatment was given and, at present, the patient is alive with no evidence of disease 18 months from diagnosis. This child represents, to our knowledge, the only case of neuroblastoma thus far treated at diagnosis and the excellent response obtained suggests the need for further investigations of this therapy in untreated patients.

Treatment of neuroblastoma with 131I-metaiodobenzylguanidine

Seven patients with neuroblastoma (six children and one adult) were treated with therapeutic doses of high specific activity 131I-metaiodobenzylguanidine (131I-MIBG). Six patients were in stage IV and unresponsive to conventional treatment. One patient, in stage III, was treated at diagnosis, an approach never previously reported. Single doses of 131I-MIBG varying from 70 to 184 mCi split into two parts were administered by slow i.v. infusion (4 to 8 hours) at 2- to 4-day intervals. The following results were obtained in the six evaluable patients: two patients showed transient stabilization of the disease; three had an objective response, with shrinking of the primary tumor and/or regression of the metastatic lesions. Of these three patients, two suffered relapses at 2 and 7 months, respectively, from the first course of MIBG. The third patient, in whom the residual disease almost completely disappeared following MIBG therapy, is still alive in complete remission after autologous bone marrow transplantation with a follow-up of 14 months. The single patient treated at diagnosis showed a dramatic response to a relatively low dosage of MIBG, with histologically proved disappearance of the tumor mass. Our data indicate that MIBG may be useful in the treatment of neuroblastoma unresponsive to conventional chemotherapy. The complete response observed in the patient treated at diagnosis suggests that the full potentiality of MIBG therapy should be explored in untreated patients.

[Possibility of using 131I-meta-iodobenzylguanidine in the diagnosis of neuroendocrine tumors differing from pheochromocytomas]

The results obtained using 131I-MIBG to diagnose different neuroendocrine tumors in 17 patients are discussed. In 8 of the neuroblastomas studied the examination gave a wide spectrum of scintigraphic results according to the various stages of evolution of the tumors, thus supplying additional useful information for metabolic treatment. Contradictory data were obtained in 5 cases of medullary cancer of the thyroid. The overall results were unexpectedly negative for 2 carcinoid tumors and, as expected, negative for 2 ganglioneuromas. These data confirm that 131I-MIBG is a non invasive, reliable and easy-to-perform technique which is no longer limited to the diagnosis of pheochromocytomas, but can also be used for the diagnosis of other tumors derived from neural crest cells.

Influence of food intake on bioavailability of oral 6-mercaptopurine in children with acute lymphoblastic leukemia

Plasma levels of 6-mercaptopurine (6-MP) were measured after oral administration in 17 children with acute lymphoblastic leukemia (ALL). In the fasting state or after a breakfast consisting of 250 ml milk and 50 g biscuits, 6-MP was administered at a dose of 75 mg/m2. In patients studied in a fasting state, the mean time to plasma peak (tmax) level was 1.2 h, whereas in patient studied after breakfast the mean tmax was 2.3 h. This difference is statistically significant (p less than 0.001). Moreover, the 6-MP peak plasma concentration (cmax) and the areas under the plasma concentration time curves (AUC) were significantly reduced when the drug was administered after breakfast. The mean Cmax +/- SD were 0.98 +/- 0.54 microM and 0.63 +/- 0.48 microM, respectively (p less than 0.05). The mean 6-MP AUC +/- SD in patients studied in a fasting state and after breakfast were 143 +/- 69 microM min and 105 +/- 68 microM, respectively (p less than 0.01). These results indicated that 6-MP should be taken in a fasting state to optimize drug absorption in children undergoing chemotherapy for ALL.

Prognostic relevance of clinical pharmacology of antileukemic drugs

Response to treatment is the most important prognostic factor in children undergoing treatment for acute lymphoblastic leukemia. Factors that interfere with the pharmacokinetic determinants of anti-leukemic compounds may cause a decreased activity of one or more of the drugs included in the treatment protocol. Noncompliance with the prescribed treatment, individual pharmacokinetic differences, interference with oral drug absorption, and different guidelines for dose reduction related to toxicity are some of the factors responsible for a decreased or variable antileukemic activity which may influence treatment results.