Clinical and cellular pharmacology in relation to solid tumours of childhood

Potential biomarkers: The hypomethylation of cg18949415 and cg22193385 sites in colon adenocarcinoma

Overall cancer hypomethylation had been identified in the past, but it is not clear exactly which hypomethylation site is the more important for the occurrence of cancer. To identify key hypomethylation sites, we studied the effect of hypomethylation in twelve regions on gene expression in colon adenocarcinoma (COAD). The key DNA methylation sites of cg18949415, cg22193385 and important genes of C6orf223, KRT7 were found by constructing a prognostic model, survival analysis and random combination prediction a series of in-depth systematic calculations and analyses, and the results were validated by GEO database, immune microenvironment, drug and functional enrichment analysis. Based on the expression values of C6orf223, KRT7 genes and the DNA methylation values of cg18949415, cg22193385 sites, the least diversity increment algorithm were used to predict COAD and normal sample. The 100 % reliability and 97.12 % correctness of predicting tumor samples were obtained in jackknife test. Moreover, we found that C6orf223 gene, cg18949415 site play a more important role than KRT7 gene, cg22193385 site in COAD. In addition, we investigate the impact of key methylation sites on three-dimensional chromatin structure. Our results will be help for experimental studies and may be an epigenetic biomarker for COAD.

PTC596-Induced BMI-1 Inhibition Fights Neuroblastoma Multidrug Resistance by Inducing Ferroptosis

Neuroblastoma (NB) is a paediatric cancer with noteworthy heterogeneity ranging from spontaneous regression to high-risk forms that are characterised by cancer relapse and the acquisition of drug resistance. The most-used anticancer drugs exert their cytotoxic effect by inducing oxidative stress, and long-term therapy has been demonstrated to cause chemoresistance by enhancing the antioxidant response of NB cells. Taking advantage of an in vitro model of multidrug-resistant (MDR) NB cells, characterised by high levels of glutathione (GSH), the overexpression of the oncoprotein BMI-1, and the presence of a mutant P53 protein, we investigated a new potential strategy to fight chemoresistance. Our results show that PTC596, an inhibitor of BMI-1, exerted a high cytotoxic effect on MDR NB cells, while PRIMA-1MET, a compound able to reactivate mutant P53, had no effect on the viability of MDR cells. Furthermore, both PTC596 and PRIMA-1MET markedly reduced the expression of epithelial-mesenchymal transition proteins and limited the clonogenic potential and the cancer stemness of MDR cells. Of particular interest is the observation that PTC596, alone or in combination with PRIMA-1MET and etoposide, significantly reduced GSH levels, increased peroxide production, stimulated lipid peroxidation, and induced ferroptosis. Therefore, these findings suggest that PTC596, by inhibiting BMI-1 and triggering ferroptosis, could be a promising approach to fight chemoresistance.

Perspectives and Expertise in Establishing a Therapeutic Drug Monitoring Programme for Challenging Childhood Cancer Patient Populations

The utility of Therapeutic Drug Monitoring (TDM) in the setting of childhood cancer is a largely underused tool, despite the common use of cytotoxic chemotherapeutics. While it is encouraging that modern advances in chemotherapy have transformed outcomes for children diagnosed with cancer, this has come at the cost of an elevated risk of life-changing long-term morbidity and late effects. This concern can limit the intensity at which these drugs are used. Widely used chemotherapeutics exhibit marked inter-patient variability in drug exposures following standard dosing, with fine margins between exposures resulting in toxicity and those resulting in potentially suboptimal efficacy, thereby fulfilling criteria widely accepted as fundamental for TDM approaches. Over the past decade in the UK, the paediatric oncology community has increasingly embraced the potential benefits of utilising TDM for particularly challenging patient groups, including infants, anephric patients and those receiving high dose chemotherapy. This has been driven by a desire from paediatric oncologists to have access to clinical pharmacology information to support dosing decisions being made. This provides the potential to modify doses between treatment cycles based on a comprehensive set of clinical information, with individual patient drug exposures being used alongside clinical response and tolerability data to inform dosing for subsequent cycles. The current article provides an overview of recent experiences of conducting TDM in a childhood cancer setting, from the perspectives of the clinicians, scientists and pharmacists implementing TDM-based dosing recommendations. The ongoing programme of work has facilitated investigations into the validity of current approaches to dosing for some of the most challenging childhood cancer patient groups, with TDM approaches now being expanded from well-established cytotoxic drugs through to newer targeted treatments.

In Vitro Assessment of the Role of p53 on Chemotherapy Treatments in Neuroblastoma Cell Lines

Neuroblastoma is the most frequent malignant extracranial solid tumor of infancy. The overall objective of this work consists of determining the presence of alterations in the p53/MDM2/p14ARF signaling pathway in neuroblastoma cell lines and deciphering their possible relationship with resistance to known antineoplastic drugs and to differentiation agents. Firstly, we characterized 10 neuroblastoma cell lines for alterations at the p53/MDM2/p14ARF signaling pathway by analysis of TP53 point mutations, MYCN and MDM2 amplification, and p14ARF methylation, homozygous deletions, and expression. Secondly, we chose SK-N-FI (mutated at TP53) and SK-N-Be(2) (wild-type TP53) cell lines, treated them with chemotherapeutic agents (doxorubicin, etoposide, cisplatin, and melphalan) and with two isomers of retinoic acid (RA): (9-cis and all-trans). Finally, we analyzed the distribution of the cell cycle, the induction of apoptosis, and the expression levels of p53, p21, and Bcl-2 in those two cell lines. P14ARF did not present promoter methylation, homozygous deletions, and protein expression in any of the 10 neuroblastoma cell lines. One TP53 point mutation was detected in the SK-N-FI cell line. MYCN amplification was frequent, while most cell lines did not present MDM2 amplification. Treatment of SK-N-FI and SK-N-Be(2) cells with doxorubicin, etoposide, cisplatin, and melphalan increased apoptosis and blocked the cycle in G2/M, while retinoic acid isomers induced apoptosis and decreased the percentage of cells in S phase in TP53 mutated SK-N-FI cells, but not in TP53 wild-type SK-N-Be(2) cells. Treatment with cisplatin, melphalan, or 9-cis RA decreased p53 expression levels in SK-N-FI cells but not in SK-N-Be (2). The expression of p21 was not modified in either of the two cell lines. Bcl-2 levels were reduced only in SK-N-FI cells after treatment with cisplatin. However, treatments with doxorubicin, etoposide, or 9-cis-RA did not modify the levels of this protein in either of the two cell lines. In conclusion, TP53 mutated SK-N-FI cells respond better to the retinoic isomers than TP53 wild-type SK-N-Be(2) cells. Although these are in vitro results, it seems that deciphering the molecular alterations of the p53/MDM2/p14ARF signaling pathway prior to treating patients of neuroblastoma might be useful for standardizing therapies with the aim of improving survival.

Irinotecan Plus Doxorubicin Hydrochloride Liposomes for Relapsed or Refractory Wilms Tumor

Purpose

The prognosis of relapsed or refractory pediatric Wilms tumor (WT) is dismal, and new salvage therapies are needed. This study aimed to evaluate the efficacy of the combination of irinotecan and a doxorubicin hydrochloride liposome regimen for relapsed or refractory pediatric WT.

Patients and Methods

The present study enrolled relapsed or refractory pediatric WT patients who were treated with the AI regimen (doxorubicin hydrochloride liposomes 40 mg/m² per day, day 1, and irinotecan 50 mg/m² per day with 90-min infusion, days 1–5; this regimen was repeated every 3 weeks) at Sun Yat-sen University Cancer Center from July 2018 to September 2020. The response was defined as the best-observed response after at least two cycles according to the Response Evaluation Criteria of Solid Tumors (RECIST 1.1), and toxicity was evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE 4.03).

Results

A total of 16 patients (male:female, 8:8) with a median age of 4.2 years (0.5–11 years) with relapsed or refractory disease were enrolled in this study, including 14 patients with relapsed disease and two patients with refractory disease. These patients received 1–8 courses (median, 3 courses) of the AI regimen. Fourteen patients were assessable for response: two with complete response (CR), five with partial response (PR), two with stable disease (SD), and five with progressive disease (PD). The objective response rate was 50% (two CR, five PR), and the disease control rate was 64% (two CR, five PR, and two SD). Seven out of 14 patients (50%) were alive at the last follow-up, ranging from 2.6 to 32.4 months. The median progression-free survival and median overall survival were 3.5 months (range 0.5–12 months) and 8 months (range 1–28 months), respectively. Sixteen patients were assessable for toxicity, with the most common grade 3 or 4 adverse events being alopecia (62%), leukopenia (40%), abdominal pain (38%), diarrhea (23%), and mucositis (16%), etc. No fatal adverse events have been observed, and modest adverse effects can be administered.

Conclusion

Irinotecan and doxorubicin hydrochloride liposome regimens have positive efficacy on relapsed or refractory pediatric WT with well-tolerated toxicity. A prospective clinical trial is warranted.

Actinomycin D Arrests Cell Cycle of Hepatocellular Carcinoma Cell Lines and Induces p53-Dependent Cell Death: A Study of the Molecular Mechanism Involved in the Protective Effect of IRS-4

Actinomycin D (ActD) is an FDA-approved NCI oncology drug that specifically targets and downregulates stem cell transcription factors, which leads to a depletion of stem cells within the tumor bulk. Recently, our research group demonstrated the importance of IRS-4 in the development of liver cancer. In this study, we evaluated the protective effects of IRS-4 against ActD. For this study, three hepatocellular carcinoma cell lines (HepG2, Huh7, and Chang cells) were used to study the mechanism of actinomycin D. Most assays were carried out in the Hep G2 cell line, due to the high expression of stem cell biomarkers. We found that ActD caused HepG2 cell necroptosis characterized by DNA fragmentation, decreased mitochondrial membrane potential, cytochrome c depletion, and decreased the levels of reduced glutathione. However, we did not observe a clear increase in apoptosis markers such as annexin V presence, caspase 3 activation, or PARP fragmentation. ActD produced an activation of MAP kinases (ERK, p38, and JNK) and AKT. ActD-induced activation of AKT and MAP kinases produced an activation of the Rb-E2F cascade together with a blockage of cell cycle transitions, due to c-jun depletion. ActD led to the inhibition of pCdK1 and pH3 along with DNA fragmentation resulting in cell cycle arrest and the subsequent activation of p53-dependent cell death in the HepG2 cell line. Only JNK and AKT inhibitors were protective against the effects of ActD. N-Acetyl-L-cysteine also had a protective effect as it restored GSH levels. A likely mechanism for this is IRS-4 stimulating GCL-GSH and inhibiting the Brk-CHK1-p53 pathway. The assessment of the IRS-4 in cancer biopsies could be of interest to carry out a personalized treatment with ActD.

Triiodothyronine (T3) upregulates the expression of proto-oncogene TGFA independent of MAPK/ERK pathway activation in the human breast adenocarcinoma cell line, MCF7

OBJECTIVE

To verify the physiological action of triiodothyronine T3 on the expression of transforming growth factor α (TGFA) mRNA in MCF7 cells by inhibition of RNA Polymerase II and the MAPK/ERK pathway.

MATERIALS AND METHODS

The cell line was treated with T3 at a physiological dose (10-9M) for 10 minutes, 1 and 4 hour (h) in the presence or absence of the inhibitors, α-amanitin (RNA polymerase II inhibitor) and PD98059 (MAPK/ERK pathway inhibitor). TGFA mRNA expression was analyzed by RT-PCR. For data analysis, we used ANOVA, complemented with the Tukey test and Student t-test, with a minimum significance of 5%.

RESULTS

T3 increases the expression of TGFA mRNA in MCF7 cells in 4 h of treatment. Inhibition of RNA polymerase II modulates the effect of T3 treatment on the expression of TGFA in MCF7 cells. Activation of the MAPK/ERK pathway is not required for T3 to affect the expression of TGFA mRNA.

CONCLUSION

Treatment with a physiological concentration of T3 after RNA polymerase II inhibition altered the expression of TGFA. Inhibition of the MAPK/ERK pathway after T3 treatment does not interfere with the TGFA gene expression in a breast adenocarcinoma cell line.

Glutathione-mediated antioxidant response and aerobic metabolism: two crucial factors involved in determining the multi-drug resistance of high-risk neuroblastoma

Neuroblastoma, a paediatric malignant tumor, is initially sensitive to etoposide, a drug to which many patients develop chemoresistance. In order to investigate the molecular mechanisms responsible for etoposide chemoresistance, HTLA-230, a human MYCN-amplified neuroblastoma cell line, was chronically treated with etoposide at a concentration that in vitro mimics the clinically-used dose. The selected cells (HTLA-Chr) acquire multi-drug resistance (MDR), becoming less sensitive than parental cells to high doses of etoposide or doxorubicin. MDR is due to several mechanisms that together contribute to maintaining non-toxic levels of H₂O₂. In fact, HTLA-Chr cells, while having an efficient aerobic metabolism, are also characterized by an up-regulation of catalase activity and higher levels of reduced glutathione (GSH), a thiol antioxidant compound. The combination of such mechanisms contributes to prevent membrane lipoperoxidation and cell death. Treatment of HTLA-Chr cells with L-Buthionine-sulfoximine, an inhibitor of GSH biosynthesis, markedly reduces their tumorigenic potential that is instead enhanced by the exposure to N-Acetylcysteine, able to promote GSH synthesis.

Collectively, these results demonstrate that GSH and GSH-related responses play a crucial role in the acquisition of MDR and suggest that GSH level monitoring is an efficient strategy to early identify the onset of drug resistance and to control the patient's response to therapy.

Pharmacogenetic variants in TPMT alter cellular responses to cisplatin in inner ear cell lines

Cisplatin is a highly-effective and widely-used chemotherapeutic agent that causes ototoxicity in many patients. Pharmacogenomic studies of key genes controlling drug biotransformation identified variants in thiopurine methyltransferase (TPMT) as predictors of cisplatin-induced ototoxicity, although the mechanistic basis of this interaction has not been reported. Expression constructs of TPMT*3A, *3B and *3C variants were generated and monitored in cultured cells. Cellular TPMT*3A levels were detected at >20-fold lower amounts than the wild type confirming the unstable nature of this variant. The expression of wild type TPMT (TPMT*1) in two murine ear cell lines, HEI-OC1 and UB/OC-1, significantly mitigated their susceptibility to cisplatin toxicity. Cisplatin treatment induced Tlr4 gene expression in HEI-OC1 cells and this response was blunted by the expression of wild type TPMT but not TPMT*3A. In line with the significant mitigation of TPMT*1-expressing cells to cisplatin cytotoxicity, these findings demonstrate a drug-gene interaction between increased TPMT activity and decreased susceptibility to cisplatin-induced toxicity of inner ear cells.

Replacing actinomycin-D with Carboplatin for newly diagnosed rhabdomyosarcoma

BACKGROUND

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the pediatric age group. All patients with RMS regardless of their initial stage or group receive combination chemotherapy as 'standard therapy' consisting of vincristine, actinomycin-D and cyclophosphamide. Actinomycin-D was not readily available in Turkey at one time. Carboplatin was used instead in order to prevent delays in treatment. The aim of this report is to present the results of patients with rhabdomyosarcoma receiving carboplatin or actinomycin-D therapy.

MATERIALS AND METHODS

Twenty four patients with rhabdomyosarcoma treated between December 2000 and June 2011 were included in this retrospective study. The patients were treated according to International Rhabdomyosarcoma Study Group guidelines. Eleven patients were treated with actinomycin-D and 13 with carboplatin (250 mg/m2/dose for 2 days). The two groups were then compared in terms of 2- and 5-year overall survival (OS) and hematological and non-hematological toxicities.

RESULTS

Age, sex, stage and the mean duration of follow-up were similar in both groups (p>0.05 ). Two- and five-year OS levels were 68.2% in the carboplatin group and 78.0% and 40.0%, respectively, in the actinomycin-D group. There was no statistical difference in the number of febrile episodes (p=0.86 ) and no other hematological and non-hematological adverse effects were recorded in both groups.

CONCLUSIONS

The findings show that carboplatin can be used as an alternative drug in the primary treatment of rhabdomyosarcoma in the event that actinomycin-D is unavailable or not tolerated.

Treatment of Wilms tumor using carboplatin compared to therapy without carboplatin

BACKGROUND

Wilms tumor (WT) is the most common pediatric malignant primary renal tumor. One of the main drugs used in treatment is actinomycin-D. This was not readily available in Turkey at one time. Carboplatin was used in the primary treatment of WT in order to prevent delays in treatment. The aim of this study is to present the results of patients with WT receiving carboplatin or actinomycin-D therapy.

PROCEDURE

Forty-eight consecutive patients with WT treated between July 2005 and December 2011 were included in this retrospective study. The patients were treated according to Turkish Pediatric Oncology Group guidelines. Nineteen patients were treated with actinomycin-D and 29 with carboplatin (500 mg/m(2) /dose). The two groups were then compared in terms of 2- and 4-year overall survival (OS), event-free survival (EFS) and disease-free survival (DFS).

RESULTS

Two- and four-year OS rates in the carboplatin group were 90.0% and 90.0%, compared to 100.0% and 88.0%, respectively, in the non-carboplatin group. Two- and four-year EFS levels in the carboplatin group were 92.0% and 88.0%, respectively, compared to 82.0% and 76.0% in the non-carboplatin group. Two-and four-year DFS levels in the carboplatin group were 92.0% and 86.0%, respectively, compared to 77.0% and 77.0% in the non-carboplatin group.

CONCLUSIONS

The findings show that the carboplatin can be used as an alternative drug in the primary treatment of WT in the event that actinomycin-D is unavailable or not tolerated.

Hepatopathy-Thrombocytopenia Syndrome During Actinomycin D Treatment May Be Related to MDR1 (ABCB1) Gene Polymorphisms

The antitumor agent actinomycin D has been used in the treatment of Wilms tumor for the past 40 years. Actinomycin D-induced hepatopathy-thrombocytopenia syndrome (HTS) is characterized as a rare syndrome. The mechanism underlying HTS may differ with individual multidrug resistance protein-1 (MDR1) genotype. The relationship between actinomycin D-related HTS and MDR1 gene mutations is presented in this case study of a pediatric patient with Wilms tumor. Our findings revealed that the girl had (-)1G>A, 1236C>T, 2677G>T, 3435C>T, and 61A>G MDR1 gene mutations. Understanding the function of genetic variants of MDR1 is an important aim for personalized cancer management.

Enantioselective total syntheses of plectosphaeroic acids B and C

Evolution of the synthetic strategy that culminated in the first total syntheses of the structurally unique plectosphaeroic acids B (2) and C (3) is described. The successful enantioselective route to (+)-2 and (+)-3 proceeds in 6 and 11 steps from the known hexahydro-2H-pyrazinopyrrolo[2,3-b]indole-1,4-dione 39, which in turn is available in enantiomerically pure form by chemical synthesis. The central challenge in this synthesis endeavor was uniting the hexahydro-2H-pyrazinopyrrolo[2,3-b]indole-1,4-dione and cinnabarinic acid fragments of these marine alkaloids. Critical for achieving this successful C-N bond formation was the use of an iodocinnabarinic acid diester in which the amino group was masked with two Boc substituents, a Cu(I) carboxylate complex and the weak base KOAc. The highly congested C-N bond generated in this coupling, in conjunction with the delicate nature of the densely functionalized coupling partners, provided a striking testament to the power of modern copper-mediated amination methods. Two approaches, one stereoselective, for introducing the methylthio substituents of (+)-plectosphaeroic acid B were developed. The epitrisulfide ring of (+)-plectosphaeroic acid C was formed by ring expansion of an epidisulfide precursor.

Cyclodextrin capped gold nanoparticles as a delivery vehicle for a prodrug of cisplatin

In this work, we explore the use of a quick coupling mechanism for "arming" a cyclodextrin coated gold nanoparticle (AuNP) delivery vehicle, 2, with an adamantane-oxoplatin conjugate that is a prodrug of cisplatin, 3, to produce a cytotoxic nanodrug, 4. The two-part arming system, which utilizes the well-known guest-host interaction between β-cyclodextrin and adamantane, may be useful for rapidly constituting polyfunctional nanodrugs prior to their application in chemotherapy. The 4.7 ± 1.1 nm delivery vehicle, 2, coated with per-6-thio-β-cyclodextrin (βSCD), was characterized using transmission electron microscopy and absorption spectroscopy, and the density of surface-attached βSCD molecules, ∼210 βSCD/AuNP, was determined using thermogravimetric analysis. Because (13)C NMR spectra of βSCD used in the study exhibited disulfide linkages and the observed surface density on the AuNP exceeded that possible for a close-packed mono layer, a fraction of the surface-attached βSCD molecules on the particle were oligomerized through disulfide linkages. Determination of the binding constant, K, for the 3-βCD interaction using (1)H NMR chemical shifts was complicated by the self-association of 3 to form a dimer through its conjugated adamantane residue. With a dimerization constant of K2 = 26.7 M(-1), the value of K for the 3-βCD interaction (1:1 stoichiometry) is 400-800 M(-1), which is lower than the value, K = 1.4 × 10(3) M(-1), measured for the 2-3 interaction using ICP-MS. Optical microscopy showed that when neuroblastoma SK-N-SH cells are treated with the nanodrug, 4 (2+3), clusters of gold nanoparticles are observed in the nuclear regions of living cells within 24 h after exposure, but, at later times when most cells are dying or dead, clustering is no longer observed. Treating the cells with 4 for 72 h gave percent inhibitions that are lower than that of cisplatin, suggesting that the Pt(IV) ions in 4 may be incompletely reduced to cytotoxic Pt(II) species in the cell.

Enantioselective total synthesis of plectosphaeroic acid B

The first total synthesis of a member of the plectosphaeroic acid family of fungal natural products is reported. Key steps include the late-stage formation of the hindered N6-C9" bond and stereoselective introduction of the two methylthio substituents.

A chemical screen identifies the chemotherapeutic drug topotecan as a specific inhibitor of the B-MYB/MYCN axis in neuroblastoma

The transcription factor MycN is the prototypical neuroblastoma oncogene and a potential therapeutic target. However, its strong expression caused by gene amplification in about 30% of neuroblastoma patients is a considerable obstacle to the development of therapeutic approaches aiming at eliminating its tumourigenic activity. We have previously reported that B-Myb is essentially required for transcription of the MYCN amplicon and have also shown that B-MYB and MYCN are engaged in a feed forward loop promoting the survival/proliferation of neuroblastoma cells. We postulated that pharmacological strategies breaking the B-MYB/MYCN axis should result in clinically desirable effects. Thus, we implemented a high throughput chemical screen, using a curated library of ~1500 compounds from the National Cancer Institute, whose endpoint was the identification of small molecules that inhibited B-Myb. At the end of the screening, we found that the compounds pinafide, ellipticine and camptothecin inhibited B-Myb transcriptional activity in luciferase assays. One of the compounds, the topoisomerase-1 inhibitor camptothecin, is of considerable clinical interest since its derivatives topotecan and irinotecan are currently used as first and second line treatment agents for various types of cancer, including neuroblastoma. We found that neuroblastoma cells with amplification of MYCN are more sensitive than MYCN negative cells to camptothecin and topotecan killing. Campothecin and topotecan caused selective down-regulation of B-Myb and MycN expression in neuroblastoma cells. Notably, forced overexpression of B-Myb could antagonize the killing effect of topotecan and camptothecin, demonstrating that the transcription factor is a key target of the drugs. These results suggest that camptothecin and its analogues should be more effective in patients whose tumours feature amplification of MYCN and/or overexpression of B-MYB.

Transcription inhibition as a therapeutic target for cancer

During tumorigenesis the transformed cells lose their normal growth control mechanisms and become dependent on oncogenes' products and pathways for survival. Treatments tailored to block the expression or function of transforming genes have shown efficacy in eliminating neoplastic cells. The mRNAs of many oncogenes, as well as regulators of other key processes such as cell proliferation, angiogenesis, and apoptosis, typically have shorter half-lives. Agents that impede mRNA synthesis are expected to selectively hinder the expression of these genes and, therefore, be detrimental to neoplastic cells that are physiologically dependent on them. In addition to exploiting the tumor cells' dependency on short-lived transcripts, RNA-directed agents also take advantage of the differential sensitivity between transformed and non-transformed cells, as the cytotoxic effects of inhibiting RNA synthesis have not been seen in non-transformed cells. The abrogation of the formation of oncotranscripts provides a new concept in cancer therapeutics and numerous agents have been developed which are able to target transcription. The focus of this review is to give an overview of transcription and the different inhibitory strategies that target various aspects of the transcriptional process.

Characterization of environmental chemicals with potential for DNA damage using isogenic DNA repair-deficient chicken DT40 cell lines

Included among the quantitative high throughput screens (qHTS) conducted in support of the US Tox21 program are those being evaluated for the detection of genotoxic compounds. One such screen is based on the induction of increased cytotoxicity in seven isogenic chicken DT40 cell lines deficient in DNA repair pathways compared to the parental DNA repair-proficient cell line. To characterize the utility of this approach for detecting genotoxic compounds and identifying the type(s) of DNA damage induced, we evaluated nine of 42 compounds identified as positive for differential cytotoxicity in qHTS (actinomycin D, adriamycin, alachlor, benzotrichloride, diglycidyl resorcinol ether, lovastatin, melphalan, trans-1,4-dichloro-2-butene, tris(2,3-epoxypropyl)isocyanurate) and one non-cytotoxic genotoxic compound (2-aminothiamine) for (1) clastogenicity in mutant and wild-type cells; (2) the comparative induction of γH2AX positive foci by melphalan; (3) the extent to which a 72-hr exposure duration increased assay sensitivity or specificity; (4) the use of 10 additional DT40 DNA repair-deficient cell lines to better analyze the type(s) of DNA damage induced; and (5) the involvement of reactive oxygen species in the induction of DNA damage. All compounds but lovastatin and 2-aminothiamine were more clastogenic in at least one DNA repair-deficient cell line than the wild-type cells. The differential responses across the various DNA repair-deficient cell lines provided information on the type(s) of DNA damage induced. The results demonstrate the utility of this DT40 screen for detecting genotoxic compounds, for characterizing the nature of the DNA damage, and potentially for analyzing mechanisms of mutagenesis.

Novel therapeutic strategies in multiple myeloma: role of the heat shock protein inhibitors

Despite advances in understanding the molecular pathogenesis of multiple myeloma and promising new therapies, almost all patients eventually relapse with resistant disease. There is therefore a strong rationale for combining novel therapies that target intrinsic molecular pathways mediating multiple myeloma cell resistance. One such protein family is the heat shock proteins (HSP), especially the HSP90 family. Heat shock protein inhibitors have been identified as promising cancer treatments as, while they only inhibit a single biologic function, the chaperone-protein association, their effect is widespread as it results in the destruction of numerous client proteins. This article reviews the preclinical and clinical data, which support the testing of HSP90 inhibitors as cancer drugs and update the reader on the current status of the ongoing clinical trials of HSP90 inhibitors in multiple myeloma.

Structure and antibacterial activity of the silver(I) complex of 2-aminophenoxazine-3-one

The crystal structure and antibacterial activity of the first metal complex of 2-aminophenoxazine-3-one is reported. We describe the silver(i) complex of this important biological molecule and show that the binding mode is through the phenoxazine ring nitrogen. A new synthetic route to 2-aminophenoxazine-3-one is also reported.

Transcription inhibition of heat shock proteins: a strategy for combination of 17-allylamino-17-demethoxygeldanamycin and actinomycin d

The heat shock protein (HSP) 90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) is currently in clinical trials because of its unique mechanism of action and antitumor activity. However, 17-AAG triggers the transcription and elevation of antiapoptotic HSP90, HSP70, and HSP27, which lead to chemoresistance in tumor cells. We hypothesized that inhibiting HSP90, HSP70, and HSP27 transcription may enhance 17-AAG-induced cell death in multiple myeloma cell lines. Actinomycin D (Act D), a clinically used agent and transcription inhibitor, was combined with 17-AAG. The concentrations for 17-AAG and Act D were selected based on the target actions and plasma levels during therapy. Inducible and constitutive HSP27, HSP70, and HSP90 mRNA and protein levels were measured by real-time reverse transcription-PCR and immunoblot assays. Compared with no treatment, Act D alone decreased HSP mRNA levels in MM.1S and RPMI-8226 cell lines. Combining Act D with 17-AAG did not attenuate 17-AAG-mediated increases in transcript levels of inducible HSP70; however, constitutive HSP mRNA levels were decreased. In contrast to its effect on mRNA levels, Act D was able to abrogate 17-AAG-mediated increases in all HSP protein levels. The cytotoxicity of combined Act D and 17-AAG was assessed. Treatment with Act D alone caused <40% cell death, whereas the combination of 17-AAG and Act D resulted in an increase of cell death in both multiple myeloma cell lines. In conclusion, these results indicate that 17-AAG-mediated induction of HSP70 and HSP27 expression can be attenuated by Act D and therefore can potentially improve the clinical treatment of multiple myeloma.

Validated assay for the simultaneous quantification of total vincristine and actinomycin-D concentrations in human EDTA plasma and of vincristine concentrations in human plasma ultrafiltrate by high-performance liquid chromatography coupled with tandem mass spectrometry

A sensitive, specific and efficient high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) assay for the simultaneous determination of total vincristine and actinomycin-D concentrations in human plasma and an assay for the determination of unbound vincristine are presented. Electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and heated electrospray ionization (H-ESI) were tested as ionization interfaces. For reasons of robustness ESI was chosen followed by tandem mass spectrometry (ESI-MS/MS). For the plasma assay a 30 microL aliquot was protein precipitated with acetonitrile/methanol (50:50, v/v) containing the internal standard vinorelbine and 10 microL volumes were injected onto the HPLC system. To determine unbound vincristine, ultrafiltrate was produced from plasma using 30 kDa centrifugal filter units. The plasma ultrafiltrate was mixed with methanol (50:50, v/v), internal standard vinorelbine was added and 20 microL aliquots were injected onto the HPLC system. Separation was achieved on a 50x2.1 mm i.d. Xbridge C18 column using 1 mM ammonium acetate/acetonitrile (30:70, v/v) adjusted to pH 10.5 with ammonia, run in a gradient with methanol at a flow rate of 0.4 mL/min. HPLC run time was 6 min. The assay quantifies in plasma vincristine from 0.25 to 100 ng/mL and actinomycin-D from 0.5 to 250 ng/mL using plasma sample volumes of only 30 microL. Vincristine in plasma ultrafiltrate can be quantified from 1 to 100 ng/mL. Validation results demonstrate that vincristine and actinomycin-D can be accurately and precisely quantified in human plasma and plasma ultrafiltrate with the presented methods. The assays are now in use to support clinical pharmacological studies in children treated with vincristine and actinomycin-D.

Recurrent melanotic neuroectodermal tumor of infancy: a proposal for treatment protocol with surgery and adjuvant chemotherapy

The case of a 4-month-old male infant treated with combined surgery and chemotherapy for an aggressive recurrent melanotic neuroectodermal tumor of infancy (MNTI) on the top of the alveolar process of the mandible with a long-term follow-up is presented. Initial treatment comprised conservative local excision and curettage of the mandible. After several local recurrences and because radical surgical excision would give gross functional and aesthetic mutilation, finally complete, long-lasting remission was achieved with adjuvant chemotherapy, according to a neuroblastoma protocol (10-year follow-up). The reason for this protocol was because molecular genetic studies of this tumor showed loss of heterozygosity of chromosome 1p and gain of chromosome 7q analogue to neuroblastomas. A combination of surgery and chemotherapy should be the preferred treatment in case of a recurrence MNTI because optimal functional and aesthetic outcome.

Zbtb4 represses transcription of P21CIP1 and controls the cellular response to p53 activation

In response to stimuli that activate p53, cells can undergo either apoptosis or cell cycle arrest, depending on the precise pattern of p53 target genes that is activated. We show here that Zbtb4, a transcriptional repressor protein, associates with the Sin3/histone deacetylase co-repressor and represses expression of P21CIP1 as part of a heterodimeric complex with Miz1. In vivo, expression of ZBTB4 is downregulated in advanced stages of multiple human tumours. In cell culture, depletion of ZBTB4 promotes cell cycle arrest in response to activation of p53 and suppresses apoptosis through regulation of P21CIP1, thereby promoting long-term cell survival. Our data suggest that Zbtb4 is a critical determinant of the cellular response to p53 activation and reinforce the notion that p21Cip1 can provide an essential survival signal in cells with activated p53.

VEGF and BMP expression in mouse osteosarcoma cells

Osteosarcoma is the most common primary bone malignancy. Despite improvements in therapy, approximately 30% of patients experience pulmonary metastasis. Expression of several growth factors, including VEGF and BMPs, has been implicated in tumor progression and metastatic potential. We hypothesized increased metastatic potential of mouse osteosarcoma cells positively correlates with the expression of VEGF and BMPs. We studied the expression patterns of these growth factors in two murine osteosarcoma cell lines with varying degrees of metastatic potential: K7M2 (highly metastatic) and K12 (minimally metastatic). Expression of VEGF and BMP2 were higher in the metastatic K7M2 cell line. We also investigated the effects of the BMP antagonist noggin on osteosarcoma growth characteristics in vitro. We noted decreased motility, altered morphology, and increased cell death in the highly metastatic K7M2 cell line. Less metastatic K12 cells showed substantial cell death without clear alteration of motility or morphology. These data suggest BMP2 expression may be an important factor in osteosarcoma metastasis and noggin administration theoretically could block its actions. Inhibition of BMPs and VEGF should be investigated further as a possible strategy for decreasing the incidence of pulmonary metastases in osteosarcoma.

Topoisomerase IIalpha in Wilms' tumour: gene alterations and immunoexpression

BACKGROUND

Topoisomerase IIalpha (topoIIalpha) is an essential enzyme gene in regulating DNA structure and cell proliferation and is encoded by the TOP2A. Using cDNA microarray analysis, TOP2A has been reported to be one of the top genes overexpressed in Wilms' tumour.

AIM

To evaluate the role of TopoIIalpha in Wilms' tumorigenesis and its prognostic value.

METHODS

TOP2A gene copy numbers were determined using the fluorescence in situ hybridisation technique, and protein expression levels of TopoIIalpha by immunostaining in 39 samples of primary and 18 samples of metastatic Wilms' tumour.

RESULTS

TOP2A gene amplification was detected only in anaplastic Wilms' tumours, and none of the Wilms' tumours showed deletion of the TOP2A gene. TopoIIalpha protein overexpression was detected in 97% of Wilms' tumours, and correlated strongly with proliferation, as measured by Ki-67 (r = 0.85). The high TopoIIalpha expression was associated with the presence of vascular invasion, prominent apoptosis, metastases and adverse clinical outcomes (p<0.05).

CONCLUSIONS

Our findings suggest that TopoIIalpha overexpression in Wilms' tumours is caused by a change at the transcription level, except for anaplastic Wilms' tumours, in which gene amplification was present. High levels of TopoIIalpha protein are correlated with tumour aggressiveness. The assessment of TopoIIalpha expression in Wilms' tumour may have prognostic value.

A transcription inhibitor, actinomycin D, enhances HIV-1 replication through an interleukin-6-dependent pathway

We previously demonstrated that Actinomycin D (ActD) enhanced HIV-1 replication in the MT-2 cell, a human T-cell leukemia virus type-1-infected cell line. The MT-2 cell is known to produce multiple cytokines spontaneously. In this study, we investigated the impact of ActD on the cytokine production from MT-2 cells and HIV-1 replication in a latently infected cell line, U1. MT-2 cells were pulse-treated with 0 or 200 nM of ActD, and culture supernatants were collected 3 days after incubation. Supernatants from untreated cells (Sup0) induced HIV-1 replication by 150-fold in U1 cells. Culture supernatants from ActD-treated cells (Sup200) enhanced HIV-1 replication by 1200-fold. A combination of a sequential chromatographic approach and mass spectrometric analysis identified that the HIV-inducing factors in Sup200 were interleukin (IL)-6 and tumor necrosis factor (TNF)-beta. Quantitative analysis revealed that ActD treatment increased the concentration of IL-6 in Sup200 by 600% compared with that in Sup0 but decreased the amount of TNFbeta in Sup200 by 85%. Northern blot analysis showed that ActD treatment increased IL-6 transcripts; however, no change was seen in TNFbeta transcripts. These results suggest that ActD induces replication of HIV-1 through modulation of cytokine production.

Cyclophosphamide disposition in an anephric child

Although limited data are available about cyclophosphamide disposition in patients with renal insufficiency, nothing has been reported in anephric patients. We characterized cyclophosphamide pharmacokinetics in an anephric child with bilateral Wilms tumor, both on (day 1) and off (day 2) hemodialysis. The median cyclophosphamide clearance on and off hemodialysis was 5.34 and 3.82 L/hr*m(2), respectively, demonstrating elimination of cyclophosphamide in this anephric child. The off hemodialysis clearance was similar to that in children with normal renal function. Hydroxycyclophosphamide (HCY) AUC was 20.6 and 8.77 microM*hr on and off hemodialysis. Carboxyethylphosphoramide mustard (CEPM) AUC obtained on hemodialysis (i.e., 194 microM*hr) was similar to that in children with normal renal function, although an elevated CEPM AUC was observed when hemodialysis was not received (i.e., 383 microM*hr). With the recent findings that clinical outcomes are related to CEPM AUC, further data are needed regarding the pharmacokinetics of cyclophosphamide and relevant metabolites in anephric children.

Role of heat treatment in childhood cancers: distinct resistance profiles of solid tumor cell lines towards combined thermochemotherapy

BACKGROUND

Since information on the efficacy of hyperthermia in combination with chemotherapy on pediatric tumors is limited, we performed a systematic analysis on the synergistic effects of a combined application of heat and chemotherapy on 20 tumor cell lines derived from patients with neuroblastomas, Ewing tumors, germ cell tumors (GCT), and osteosarcomas.

METHODS

Cisplatin (cDDP), a cross-linking agent, and etoposide (VP-16), a topoisomerase II inhibitor, were examined either alone or in combination with heat (42 degrees C, 43 degrees C) by using the XTT-assay 1.

RESULTS

Our data demonstrate that heat stress at 43 degrees C for 1 hr, but not at 42 degrees C, leads to a notable cytotoxic effect on the different tumor cells. The comparison of mean survival fractions reveals values between 62% for neuroblastoma cells and 76% for Ewing tumor cells. Analyzing the sensitivity to chemotherapy alone, our results show that cDDP (5 microg/ml) reduces cell growth to 47% in Ewing tumor cells, to 61% in neuroblastoma cells, to 75% in GCT cells, and to 76% in osteosarcoma cells. Treatment with VP-16 (10 microg/ml) decreases cell survival to mean values between 58% (neuroblastomas) and 77% (osteosarcomas). Simultaneous application of heat and chemotherapy enhances synergistically cDDP cytotoxicity in all tumor types tested, whereas the efficacy of VP-16 is only slightly influenced by additional application of hyperthermia. The cytotoxicity of cDDP (5 microg/ml) can be increased by a factor of between 1.5 and 2.5 at 42 degrees C and from 2.6 to 14.0 at 43 degrees C. Furthermore, the results show that the sensitivity to heat (43 degrees C) as well as the sensitivity to chemotherapy and combined thermochemotherapy varies considerably between cell lines of the same tumor group.

CONCLUSIONS

Simultaneous application of hyperthermia synergistically enhances the cytotoxicity of the alkylating agent cDDP, but not of the topoisomerase II inhibitor VP-16, in a defined spectrum of cell lines from different pediatric tumor entities.

A glyphosate-based pesticide impinges on transcription

Widely spread chemicals used for human benefits may exert adverse effects on health or the environment, the identification of which are a major challenge. The early development of the sea urchin constitutes an appropriate model for the identification of undesirable cellular and molecular targets of pollutants. The widespread glyphosate-based pesticide affected sea urchin development by impeding the hatching process at millimolar range concentration of glyphosate. Glyphosate, the active herbicide ingredient of Roundup, by itself delayed hatching as judged from the comparable effect of different commercial glyphosate-based pesticides and from the effect of pure glyphosate addition to a threshold concentration of Roundup. The surfactant polyoxyethylene amine (POEA), the major component of commercial Roundup, was found to be highly toxic to the embryos when tested alone and therefore could contribute to the inhibition of hatching. Hatching, a landmark of early development, is a transcription-dependent process. Correlatively, the herbicide inhibited the global transcription, which follows fertilization at the 16-cell stage. Transcription inhibition was dose-dependent in the millimolar glyphosate range concentration. A 1257-bp fragment of the hatching enzyme transcript from Sphaerechinus granularis was cloned and sequenced; its transcription was delayed by 2 h in the pesticide-treated embryos. Because transcription is a fundamental basic biological process, the pesticide may be of health concern by inhalation near herbicide spraying at a concentration 25 times the adverse transcription concentration in the sprayed microdroplets.