Modulation of Viability, Proliferation, and Stemness by Rosmarinic Acid in Medulloblastoma Cells: Involvement of HDACs and EGFR

Medulloblastoma (MB) is a heterogeneous group of malignant pediatric brain tumors, divided into molecular groups with distinct biological features and prognoses. Currently available therapy often results in poor long-term quality of life for patients, which will be afflicted by neurological, neuropsychiatric, and emotional sequelae. Identifying novel therapeutic agents capable of targeting the tumors without jeopardizing patients' quality of life is imperative. Rosmarinic acid (RA) is a plant-derived compound whose action against a series of diseases including cancer has been investigated, with no side effects reported so far. Previous studies have not examined whether RA has effects in MB. Here, we show RA is cytotoxic against human Daoy (IC50 = 168 μM) and D283 (IC50 = 334 μM) MB cells. Exposure to RA for 48 h reduced histone deacetylase 1 (HDAC1) expression while increasing H3K9 hyperacetylation, reduced epidermal growth factor (EGFR) expression, and inhibited EGFR downstream targets extracellular-regulated kinase (ERK)1/2 and AKT in Daoy cells. These modifications were accompanied by increased expression of CDKN1A/p21, reduced expression of SOX2, and a decrease in proliferative rate. Treatment with RA also reduced cancer stem cell markers expression and neurosphere size. Taken together, our findings indicate that RA can reduce cell proliferation and stemness and induce cell cycle arrest in MB cells. Mechanisms mediating these effects may include targeting HDAC1, EGFR, and ERK signaling, and promoting p21 expression, possibly through an increase in H3K9ac and AKT deactivation. RA should be further investigated as a potential anticancer agent in experimental MB.

Cancer stem cells and chemoresistance in Ewing sarcoma

Resistance to chemotherapy poses a major challenge for cancer treatment. Reactivation of a stem cell program resembling that seen in embryonic development can lead cancer cells to acquire a stem-cell phenotype characterized by expression of stemness genes, pluripotency, high self-renewal ability, and tumor-initiating capability. These cancer stem cells (CSCs) are usually resistant to anticancer drugs and are likely involved in treatment failure in many cancer types. Ewing sarcoma (ES), a pediatric cancer type typically arising by a typical genetic alteration that can affect either bone or soft tissues. Despite advances in treatment, survival prognostic remains poor for patients with refractory or recurrent disease. Here, we review the increasing evidence indicating that ES tumors contain a CSC subpopulation expressing stem cell genes including BM1, OCT3/4, NANOG, and SOX2 that plays a role in resistance to drug treatment, and current experimental strategies that successfully counteract chemoresistance mediated by CSCs in ES.

GGAA microsatellites of NR0B1 promoter region in Ewing's sarcoma patients and healthy individuals from a south Brazilian population

Introduction: The very aggressive soft tissue and bone pediatric tumor Ewing’s sarcoma (ES) is caused in most cases by the chromosomal translocation t(11;22)(q24;q12), which encodes an aberrant chimeric transcription factor (EWS-FLI1) that regulates target genes, including the critical oncogene NR0B1 (Xp21.2), via GGAA microsatellites. Objective: Our objective was to analyze the GGAA microsatellites of NR0B1 promoter region of ES patients and healthy subjects in our population. Methodology: Ten male ES patients and 71 adult healthy males from Rio Grande do Sul state, Brazil, were included in this study. Leukocyte DNA was extracted, amplified by PCR, sequenced by the Sanger method and analyzed by capillary electrophoresis. Total number of GGAA motifs, length of microsatellite in base pairs, number of segments separated by "A" insertions and greatest number of consecutive GGAA motifs were analyzed. Statistical analyses were performed in the SPSS® statistical software and p-value <0,05 was considered significant. Results: A total of 21 different alleles was identified in the 81 subjects, with 24.2 allele [(GGAA)7A(GGAA)7A(GGAA)10 sequence] being the most frequent, but when comparing the data between the two groups, no significant difference was found. Conclusion: We concluded that the studied sample was highly variable in terms microsatellite structure, including the presence of rare alleles, giving us the opportunity to describe our population which is a fundamental step on identifying genetic implications in ES tumorigenesis.

The effect of hospital care volume on overall survival of children with cancer in Southern Brazil

PURPOSE

The purpose of this study was to analyze the effect of hospital care volume on the overall survival of children with cancer in Southern Brazil.

PATIENTS AND METHODS

We performed a retrospective cohort study of 1378 cancer patients aged 0-19 years, diagnosed with cancer between August 1, 2009 and December 31, 2015 in Rio Grande do Sul, who received hospital treatment in institutions affiliated with the Universal Health Care System (Sistema Único de Saúde [SUS]).

RESULTS

Most children and adolescents were male (56.9%) and White (75.8%). The most common types of cancer in our cohort were acute leukemia (40.7%), followed by lymphoma (15.9%) and central nervous system tumors (8.8%). Ninety-five percent of the patients were treated in specialized pediatric oncology centers. The cumulative probability of survival at 5 years for all patients was 73.8% (95% confidence interval [CI] 71.4-76.0%). Survival was significantly higher for patients younger than 4 years of age (P = .012) compared to all other age groups. Patients treated in institutions with a pediatric oncology patient volume of less than 15 patients/year were 41% more likely to die than patients treated in institutions with a volume of 60 patients/year or more (P = .029).

CONCLUSION

Cancer is the leading cause of death by natural causes in all age groups in Brazil, but, even so, childhood tumors are rare. This complexity makes childhood cancer care a challenge. In this study, we reiterate that pediatric cancer patients demonstrate better overall survival when treated in high-volume hospitals.

Expression of neurotrophins and their receptors in primary osteosarcoma

OBJECTIVE

to determine the expression of neurotrophins and their tyrosine-kinase receptors in patients with osteosarcoma (OS) and their correlation with clinical outcomes.

METHODS

we applied immunohistochemistry to biopsy specimens of patients consecutively treated for primary OS at a single institution between 2002 and 2015, analyzing them for expression receptors of tyrosine kinase A and B (TrKA and TrKB), neural growth factor (NGF) and brain derived neurotrophic factor (BDNF). Independently, two pathologists classified the immunohistochemical markers as negative (negative or weak focal) or positive (moderate focal/diffuse or strong focal/diffuse).

RESULTS

we analyzed data from 19 patients (10 females and 9 males), with median age of 12 years (5 to 17.3). Tumors' location were 83.3% in the lower limbs, and 63.2% of patients had metastases at diagnosis. Five-year overall survival was 55.3%. BDNF was positive in 16 patients (84%) and NGF in 14 (73%). TrKA and TrKB presented positive staining in four (21,1%) and eight (42,1%) patients, respectively. Survival analysis showed no significant difference between TrK receptors and neurotrophins.

CONCLUSION

primary OS samples express neurotrophins and TrK receptors by immunohistochemistry. Future studies should explore their role in OS pathogenesis and determine their prognostic significance in larger cohorts.

Gene expression changes associated with chemotherapy resistance in Ewing sarcoma cells

Ewing Sarcoma (ES) is a highly aggressive bone and soft tissue childhood cancer. The development of resistance to chemotherapy is common and remains the main cause of treatment failure. We herein evaluated the expression of genes associated with chemotherapy resistance in ES cell lines. A set of genes (CCAR1, TUBA1A, POLDIP2, SMARCA4 and SMARCB1) was data-mined for resistance against doxorubicin and vincristine, which are the standard drugs used in the treatment of patients with ES. The expression of each gene in SK-ES-1 ES cells was reported before and after exposure to a drug resistance-inducing protocol. There was a significant downregulation of CCAR1 and TUBA1A in doxorubicin-resistant cells, with low expression of TUBA1A in vincristine-resistant cells. By contrast, POLDIP2 was significantly upregulated in cells resistant to either drug, and the expression of the SMARCB1 and SMARCA4 genes was upregulated in doxorubicin-resistant cells. These findings indicate that resistance to specific chemotherapeutic agents was accompanied by differential changes in gene expression in ES tumors.

Epidermal Growth Factor Receptor Regulation of Ewing Sarcoma Cell Function

OBJECTIVE

Ewing sarcoma (ES) is a type of childhood cancer probably arising from stem mesenchymal or neural crest cells. The epidermal growth factor receptor (EGFR) acts as a driver oncogene in many types of solid tumors. However, its involvement in ES remains poorly understood.

METHODS

Human SK-ES-1 and RD-ES ES cells were treated with EGF, the EGFR inhibitor tyrphostin (AG1478), or phosphoinositide 3-kinase (PI3K) or extracellular-regulated kinase (ERK)/mitogen-activated kinase (MAPK) inhibitors. Cell proliferation survival, cycle, and senescence were analyzed. The protein content of possible targets of EGFR manipulation was measured by Western blot.

RESULTS

Cell proliferation and survival were increased by EGF and inhibited by AG1478. The EGFR inhibitor also altered the cell cycle, inducing arrest in G1 and increasing the sub-G1 population, reduced polyploidy and increased the population of senescent cells. In addition, AG1478 reduced the levels of phosphorylated AKT (p-AKT), ERK, p-ERK, cyclin D1, and brain-derived neurotrophic factor (BDNF), while enhancing p53 levels. Cell proliferation was also impaired by inhibitors of PI3K or ERK, alone or combined with AG1478.

CONCLUSIONS

Our findings reveal novel aspects of EGFR regulation of ES cells and provide early evidence for antitumor activities of EGFR inhibitors in ES.

Combined Treatments with a Retinoid Receptor Agonist and Epigenetic Modulators in Human Neuroblastoma Cells

Neuroblastoma (NB) is the most common extracranial solid childhood tumor accounting for around 15% of pediatric cancer deaths and most probably originates from a failure in the development of embryonic neural crest cells. Retinoids can inhibit the proliferation and stimulate differentiation of NB cells. In addition, epigenetic events involving changes in chromatin structure and DNA methylation can mediate the effects of retinoids; hence, the scope of this study is to investigate the use of retinoids and epigenetic drugs in NB cell lines. Here, we demonstrate that the combination of retinoid all trans-retinoic acid (ATRA) with inhibitors of either histone deacetylases (HDACs) or DNA methyltransferase is more effective in impairing the proliferation of human SH-SY5Y and SK-N-BE(2) NB cells than any drug given alone. Treatments also induced differential changes on the messenger RNA (mRNA) expression of retinoid receptor subtypes and reduced the protein content of c-Myc, the neuronal markers NeuN and β-3 tubulin, and the oncoprotein Bmi1. These results suggest that the combination of retinoids with epigenetic modulators is more effective in reducing NB growth than treatment with single drugs.

BDNF/TrkB Signaling as a Potential Novel Target in Pediatric Brain Tumors: Anticancer Activity of Selective TrkB Inhibition in Medulloblastoma Cells

Medulloblastoma (MB) is the most common malignant pediatric brain tumor. Deregulation of brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) signaling has been associated with increased proliferative capabilities, invasiveness, and chemoresistance in several types of cancer. However, the relevance of this pathway in MB remains unknown. Here, we show that the selective TrkB inhibitor N-[2-[[(hexahydro-2-oxo-1H-azepin-3-yl)amino]carbonyl]phenyl]-benzo[b]thiophene-2-carboxamide (ANA-12) markedly reduced the viability and survival of human cell lines representative of different MB molecular subgroups. These findings provide the first evidence supporting further investigation of TrkB inhibition as a potential novel strategy for MB treatment.

Osteosarcoma in patients younger than 12 years old without metastases have similar prognosis as adolescent and young adults

BACKGROUND

Childhood cancer is relatively rare and tends to present specific age distribution, as a prognostic factor for some of these diseases. Information on how young age affects prognosis, response to chemotherapy, and local control options in children versus AYA with osteosarcoma (OST) is minimal.

METHODS

In order to identify the main differences in clinical pathologic features, surgical approaches and survival rates of primary high grade OST of the extremity between children (n = 156; <12 years old) and AYA (n = 397; 12-30 years old), the institutional database with 553 patients treated by BOTG studies over 15 years were reviewed.

RESULTS

There were no differences in metastases at diagnosis, tumor size, and grade of necrosis between the two age groups. The rate of amputation was 30% higher in the children group (P = 0.018). The rate of limb salvage surgery using reconstruction with allograft or autograft was 70% higher in the children group (P = 0.018) while endoprosthesis rate was 40% higher in the AYA group (P = 0.018). The log rank test revealed that survival is similar between the two age groups for non-metastatic patients (P = 0.424 for OS and P = 0.393 for EFS). Metastatic patients of both ages group had higher risk of dying compared to non-metastatic (HR 3.283 95% CI 2.581-4.177; P < 0.001). Children with metastases at diagnosis had less OS time (P = 0.049) and EFS time (P = 0.032) than adolescents.

CONCLUSION

Non-metastatic OST in preadolescent patients does not appear to be significantly different from those seen in AYA patients, but has local control challenges. Children presenting with metastases should be considered an ultra-high-risk group.

Inhibitory activities of trichostatin a in U87 glioblastoma cells and tumorsphere-derived cells

Epigenetic alterations have been increasingly implicated in glioblastoma (GBM) pathogenesis, and epigenetic modulators including histone deacetylase inhibitors (HDACis) have been investigated as candidate therapies. GBMs are proposed to contain a subpopulation of glioblastoma stem cells (GSCs) that sustain tumor progression and therapeutic resistance and can form tumorspheres in culture. Here, we investigate the effects of the HDACi trichostatin A (TSA) in U87 GBM cultures and tumorsphere-derived cells. Using approaches that include a novel method to measure tumorsphere sizes and the area covered by spheres in GBM cultures, as well as a nuclear morphometric analysis, we show that TSA reduced proliferation and colony sizes, led to G2/M arrest, induced alterations in nuclear morphology consistent with cell senescence, and increased the protein content of GFAP, but did not affect migration, in cultured human U87 GBM cells. In cells expanded in tumorsphere assays, TSA reduced sphere formation and induced neuron-like morphological changes. The expression of stemness markers in these cells was detected by reverse transcriptase polymerase chain reaction. These findings indicate that HDACis can inhibit proliferation, survival, and tumorsphere formation, and promote differentiation of U87 GBM cells, providing further evidence for the development of HDACis as potential therapeutics against GBM.

In vitro antitumor effect of sodium butyrate and zoledronic acid combined with traditional chemotherapeutic drugs: a paradigm of synergistic molecular targeting in the treatment of Ewing sarcoma

Histone deacetylase inhibitors and bisphosphonates have a promising future in the treatment of cancer as targeted anticancer drugs, particularly when used together or in combination with other cytotoxic agents. However, the effects of these combined treatments have not yet been systematically evaluated in Ewing sarcoma. The in vitro effects on cellular proliferation, viability and survival were investigated in two Ewing sarcoma cell lines, SK-ES-1 and RD-ES. The cell lines were treated with sodium butyrate, a histone deacetylase inhibitor and zoledronic acid, a bisphosphonate, alone, together or in combination with chemotherapeutic drugs recommended for clinical treatment of Ewing sarcoma. The data demonstrated that the combination of sodium butyrate and zoledronic acid had a synergistic cytotoxic effect at 72 h following treatment, persisting for 10-14 days post-treatment, in both cell lines tested. All combinations between sodium butyrate or zoledronic acid and the traditional antineoplastic drugs (doxorubicin, etoposide and vincristine) demonstrated a synergistic cytotoxic effect at 72 h in SK-ES-1 and RD-ES cells, except for the combinations of sodium butyrate with vincristine and of zoledronic acid with doxorubicin, which showed only an additive effect in RD-ES cell lines as compared to each agent alone. These acute effects observed in both Ewing sarcoma cell lines were confirmed by the clonogenic assay. The present data suggest that combining histone deacetylase inhibitors and bisphosphonates with traditional chemotherapeutic drugs is a promising therapeutic strategy for the treatment of Ewing sarcoma, and provides a basis for further studies in this field.

Fifteen Years' Experience of the Brazilian Osteosarcoma Treatment Group (BOTG): A Contribution from an Emerging Country

PURPOSE

Little information is available regarding the tumor features, prognostic factors, and treatment results in children and adolescents and young adults (AYAs) with osteosarcoma diagnosed in developing countries. We reviewed the results of three observational cohorts of osteosarcoma patients treated in an emerging country.

METHODS

A total of 604 patients below the age of 30 years with high-grade osteosarcoma were prospectively enrolled in the Brazilian Osteosarcoma Treatment Group (BOTG) studies III, IV, and V. Gender, age, time from onset of symptoms to diagnosis, primary tumor site, presence or absence of metastases at diagnosis, tumor size, type of surgery (limb-sparing or amputation), treatment protocol, and histological response were correlated with survival.

RESULTS

The estimated 5-year overall survival and event-free survival (EFS) rates for the 553 eligible patients were 49% and 39% respectively; of the 390 non-metastatic patients included in the total, overall- and event-free survival were 59% and 48% respectively. Metastases at diagnosis, primary tumor site, type of surgery, and histological response were significant predictors of overall survival and EFS in univariate and multivariate analysis, whereas tumor size and treatment protocol lost prognostic significance in multivariate analysis.

CONCLUSION

We report on the outcome of three consecutive studies for the treatment of osteosarcoma carried out in Brazil over 15 years. Although the survival rates presented are below those reported in current literature, it represents the result of a favorable experience gathered from the national collaborative work.

Autologous stem cell transplantation as first line treatment after incomplete excision of pancreatoblastoma

Pancreatoblastoma is a rare tumor and surgery with complete resection is the main treatment approach. Prognosis for patients with residual disease after surgery is usually dismal. A 14-year-old girl with pancreatoblastoma in the pancreatic body and tail was submitted to preoperative chemotherapy. She underwent surgery and the tumor was resected with microscopic margins. Postoperative chemotherapy was followed by high dose chemotherapy and autologous hematopoietic stem cell transplantation. After four years she remains very well with no evidence of disease. This is the first case reported of pancreatoblastoma that was treated with autologous hematopoietic stem cell transplantation as first line treatment without radiotherapy at the site of the microscopic disease.

The histone deacetylase inhibitor sodium butyrate promotes cell death and differentiation and reduces neurosphere formation in human medulloblastoma cells

Increasing evidence suggests that alterations in epigenetic mechanisms regulating chromatin state play a role in the pathogenesis of medulloblastoma (MB), the most common malignant brain tumor of childhood. Histone deacetylase (HDAC) inhibitors, which increase chromatin relaxation, have been shown to display anticancer activities. Here we show that the HDAC inhibitor sodium butyrate (NaB) markedly increases cell death and reduces colony formation in human MB cell lines. In addition, NaB increased the mRNA expression of Gria2, a neuronal differentiation marker, in D283 and DAOY cells and reduced the number of neurospheres in D283 cell cultures. Finally, NaB reduced the viability of D283 cells when combined with etoposide. These data show that NaB displays pronounced inhibitory effects on the survival of human MB cells and suggest that NaB might potentiate the effects of etoposide. In addition, our study suggests that HDAC inhibition might promote the neuronal differentiation of MB cells and provides the first evidence that an HDAC inhibitor might suppress the expansion or survival of MB cancer stem cells.

Prevalence of TP53 p.R337H mutation in children with cancer from a public hospital in southern Brazil

10593

Background: Childhood cancers are a common feature in Li-Fraumeni/Li Fraumeni-Like Syndromes (LFS/LFL), associated with the inheritance of a germline TP53 mutation. Recently, a specific germline mutation in exon 10 of the TP53 gene, p.R337H, has been reported at a high prevalence in Southeastern Brazil. Initial studies on this mutation claimed that the main, if not exclusive, cancer risk in carriers is childhood adrenocortical carcinoma (ADR). However, others recent reports identified p.R377H carriers among LFL families and among a larger spectrum of tumors, such as choroid plexus carcinoma (CPC) and osteosarcoma. The aim of this study was to assess the frequency of the p.R337H mutation in children diagnosed with tumors of the LFS/LFL spectrum: ADR, sarcoma, central nervous system tumors, leukemia, germline cell tumors and Wilm’s tumor) at the Children’s Cancer Institute of Rio Grande do Sul (Brazil) between 1998 and 2011. Methods: Family history (FH) was recorded in pedigrees, and DNA was extracted from peripheral blood and FFPE samples by standard methods. Screening for the p.R337H mutation was performed by allelic discrimination (TaqMan assay) and by TP53 exon 10 sequencing. Results: Analysis of 295 children diagnosed with tumors of the LFS/LFL spectrum identified the p.R337H mutation in 9/11 (81,8%) children with ADR (including a homozygous p.R337H individual) and in 2/2 (100%) children with CPC. All individuals had loss of heterozygosity in the tumor and in all cases the mutant allele occurred on the same founder haplotype. One hundred fourth-six (49,5%) patients had a cancer FH in first or second degree relatives, 47 (16,0%) had a FH of breast cancer and 49 (16,6%) had FH of LFL consistent with Chompret and/or Birch criteria. Conclusions: These results confirm the strong association of p.R337H with ADR and CPC. A FH consistent with LFL syndrome is present in a high proportion of children diagnosed with tumors of the LFS/LFL spectrum in Southern Brazil. Financial support: FIPE-HCPA, CAPES, FAPERGS and Glaxo Smith Kline.

The histone deacetylase inhibitor sodium butyrate in combination with brain-derived neurotrophic factor reduces the viability of DAOY human medulloblastoma cells

PURPOSE

Histone deacetylase inhibitors (HDACis) are a promising class of anticancer agents for the treatment of brain tumors. HDACis can increase the expression of brain-derived neurotrophic factor (BDNF) in brain cells. We have previously shown that BDNF reduces the viability of medulloblastoma cells. The aim of the present study was to examine the effect of the HDACi sodium butyrate (NaB) combined with human recombinant BDNF (hrBDNF), on the viability of human medulloblastoma cell lines.

METHODS

DAOY and ONS76 medulloblastoma cells were treated with NaB, hrBDNF, or NaB combined with hrBDNF. Cell viability was measured with the MTT assay.

RESULTS

NaB combined with hrBDNF significantly reduced the viability of DAOY medulloblastoma cells. In ONS76 cells, NaB alone reduced viability, but the effect was not potentiated by hrBDNF.

CONCLUSION

These findings provide early evidence for a rationale supporting further evaluation of HDACis and BDNF as a new combinatorial approach to inhibit the growth of medulloblastoma.

BDNF/TrkB content and interaction with gastrin-releasing peptide receptor blockade in colorectal cancer

OBJECTIVE

Neurotrophin and neuropeptide pathways are emerging targets in cancer. Here we show that brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, are present in colorectal cancer and that BDNF levels are increased in tumors compared to nontumor tissue. In addition, we investigate the role of BDNF in influencing the response of colorectal cancer cells to inhibition of gastrin-releasing peptide receptors (GRPR).

METHODS

Fresh-frozen sporadic colorectal adenocarcinoma specimens and adjacent nonneoplastic tissue from 30 patients, as well as paraffin-embedded colorectal cancer samples from 21 patients, were used in this study. Cell proliferation and mRNA and protein levels were examined in HT-29 or SW620 cells treated with a GRPR antagonist, human recombinant BDNF (hrBDNF), a Trk antagonist K252a, or cetuximab.

RESULTS

Expression of BDNF and TrkB was detected in tumor samples and cell lines. BDNF levels were higher in tumor samples compared to nonneoplastic tissue. BDNF expression and secretion were increased by GRPR blockade in HT-29 cells through a mechanism dependent on epidermal growth factor receptors. Treatment with hrBDNF prevented the effect of GRPR blockade on cell proliferation, whereas a Trk inhibitor reduced proliferation.

CONCLUSIONS

BDNF and TrkB are present in colorectal cancer and might contribute to resistance to GRPR antagonists.

Current and emerging molecular targets in glioma

Gliomas are the most common and lethal neurological cancers. Despite research efforts, the prognosis for patients with malignant gliomas remains poor. Advances in the understanding of cellular and molecular alterations in gliomas have led to the emergence of experimental molecularly targeted therapies. This article summarizes recent progress in the development of targeted therapies for glioma, focusing on emerging molecular targets, including neuropeptide and neurotrophin pathways, glutamate receptors, epigenetic mechanisms and glioma stem cell targets. Recent clinical trials of small molecules and antibodies targeted at growth factor pathways and intracellular signaling cascades are also discussed.

Recent therapeutic advances for treating medulloblastoma: focus on new molecular targets

Medulloblastoma is the most common malignant brain tumor in children. This malignant tumor of the cerebellum commonly affects children and is believed to arise from the precursor cells of the external granule layer or neuroepithelial cells from the cerebellar ventricular zone of the developing cerebellum. The standard treatment, consisting of surgery, craniospinal radiotherapy and chemotherapy, still provides a poor overall survival for infants and young children. Furthermore, the dose of radiation that can be safely given without causing extensive neurocognitive and endocrinologic sequelae is limited. Therefore, understanding the oncogenic pathways that lead to medulloblastoma, as well as the identification of specific molecular targets with significant therapeutic implications in order to develop new strategies for therapy, is crucial to improve patient survival without substantially increasing toxicity. In this review, we discuss recent therapeutics for treating medulloblastoma, focusing on new molecular targets, as well as advances in translational studies for the treatment of this malignancy.

Cancer stem cells and the biology of brain tumors

There is now compelling evidence that brain tumors harbor a small population of cells characterized by their ability to undergo self-renewal and initiate tumors, termed cancer stem cells (CSCs). The development of therapeutic strategies targeted towards CSC signaling may improve the treatment of brain tumors such as malignant gliomas and medulloblastomas. Here we review the role of cancer stem cells in glioma and medulloblastoma and some of the signaling mechanisms involved in brain tumor stem cell (BTSC) biology, and discuss how these signaling pathways may represent new stem cell targets for the treatment of brain tumors. In addition, we provide illustrative immunohistochemical data on the presence of BTSCs in human gliomas and medulloblastomas, and show preliminary findings suggesting the involvement of a GPCR, the gastrin-releasing peptide receptor (GRPR), in the expansion of BTSCs in vitro.

Oral vs. intravenous empirical antimicrobial therapy in febrile neutropenic patients receiving childhood cancer chemotherapy

OBJECTIVE

To compare the use of intravenous vs. oral antibiotic therapy.

METHODS

All febrile neutropenic patients younger than 18 years old with low risk of complications and receiving chemotherapy were selected. The study was conducted from 2002 to 2005 at the Pediatric Oncology Unit of Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil. Patients were divided into group A and group B and were randomly assigned to receive oral or intravenous therapy. The empirical antimicrobial treatment used for group A consisted in oral ciprofloxacin plus amoxicillin-clavulanate and intravenous placebo, and group B received cefepime and oral placebo.

RESULTS

A total of 91 consecutive episodes of febrile neutropenia in 58 children were included in the study. For patients of group A, treatment failure rate was 51.2%; the mean length of hospital stay was 8 days (range 2-10 days). For patients treated with intravenous antibiotic therapy, treatment failure rate was 45.8%; the mean length of hospital stay was 7 days (range 3-10 days).

CONCLUSION

There was no difference in the outcome in oral vs. intravenous therapy. There is need of larger randomized trials before oral empirical therapy administered to this population should be considered the new standard of treatment.

Histone deacetylase inhibitors: a new perspective for the treatment of leukemia

Histone deacetylase inhibitors (HDIs) promote or enhance several different anticancer mechanisms and therefore are in evidence as potential antileukemia agents. Studies on leukemia have provided examples for their functional implications in cancer development and progression, as well as their relevance for therapeutic targeting. A number of HDIs have been tested in clinical trials and have been proven safe with significant clinical activity. The use of HDIs in association with other molecules, such as classical chemotherapeutic drugs and DNA demethylating agents, has been implied as a promising treatment alternative for leukemia patients in the future. Here we describe the histone deacetylase inhibitors that have been tested in clinical trials for the treatment of leukemia and lymphoma. We conclude that further clinical trials involving a broader number of HDIs used either alone or in combination with other agents are needed to consolidate the use of these epigenetic modulators on leukemia therapy.

Systemic administration of doxorubicin impairs aversively motivated memory in rats

There is growing clinical evidence of cognitive impairment in cancer patients treated with chemotherapy, especially in women treated with drug combinations for breast cancer. Clinical studies have a difficult task of defining which drugs individually are responsible for the cognitive changes and published papers evaluating single agents in experimental models are scanty. In the present study we have investigated the effect of single escalating doses of doxorubicin (DOX) on memory for inhibitory avoidance conditioning (IA) in rats. The doses used were comparable to those applied in the clinic. When given systemically before training, higher doses of DOX impaired IA memory retention measured 24h and 7days, but not 3h after training. DOX did not affect IA retention when given either before or after training in a multiple-trial IA training protocol. Control experiments showed that DOX produced a decrease in exploratory behavior assessed by the number of rearings performed during exploration of an open field. The results indicate that a single systemic administration of DOX might impair long-term aversive learning.

Oral health and dental anomalies in patients treated for leukemia in childhood and adolescence

BACKGROUND

This study was conducted to evaluate oral health and dental anomalies in children treated for acute lymphoblastic leukemia (ALL) and to compare results with those of a group of healthy children matched for sex and age.

PROCEDURE

Fifty-six children treated for ALL and 56 healthy controls were examined for dental anomalies, and data on decayed, missing, and filled teeth (DMFT) score, visible plaque (VPI), and gingival bleeding (GBI) indices, and saliva flow were collected. Mean age of all children treated for ALL was 5.3 +/- 2.6 years at diagnosis and 11.8 +/- 4.2 at evaluation. Thirty-two were males.

RESULTS

Forty-five treated children (80.4%) had at least one dental anomaly, and patients treated with chemotherapy, radiotherapy, and bone marrow transplantation had the greatest mean number of dental anomalies (15.37 +/- 15.03). Patients younger than 5 years at beginning of treatment were also more affected (P = 0.031). Children treated for ALL had a DMFT score of 1.9 +/- 4.0, GBI of 26.5%, VPI of 72.0%, and mean saliva flow of 0.19 ml/min; healthy children had a DMFT score of 1.52 +/- 3.5, GBI of 11.1%, VPI of 53.8%, and mean saliva flow of 0.27 ml/min.

CONCLUSION

The treatment of ALL causes a significant increase in the number of dental anomalies. Their GBI and VPI were also elevated. Changes in salivary glands during treatment did not affect saliva flow permanently. Follow-up of these patients by an oral health team is recommended.

Gastrin-releasing peptide receptors regulate proliferation of C6 Glioma cells through a phosphatidylinositol 3-kinase-dependent mechanism

Gastrin-releasing peptide (GRP) has been proposed as a major growth factor in brain tumors, and GRP receptor (GRPR) antagonists show antiproliferative effects in experimental gliomas. However, the underlying molecular events downstream of GRPR activation remain poorly understood. In the present study, we examined the role of the GRPR in regulating proliferation of glioma cells in vitro and its possible interaction with the phosphatidylinositol 3-kinase (PI3K) signaling pathway. Expression of GRPR mRNA and protein in C6, U-87MG, and U-373MG glioma cells was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Proliferation of C6 and U-87MG, but not U-373MG cells was significantly inhibited by the GRPR antagonist RC-3095, whereas the GRPR agonist bombesin (BB) significantly enhanced proliferation of C6 cells. The BB-induced stimulatory effect on cell proliferation was prevented by either RC-3095 or the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Our results provide the first evidence that the GRPR regulates proliferation of C6 glioma cells and suggest that PI3K is required for GRPR-mediated stimulation of glioma growth.

Stimulation of proliferation of U138-MG glioblastoma cells by gastrin-releasing peptide in combination with agents that enhance cAMP signaling

Increasing evidence indicates that gastrin-releasing peptide (GRP) acts as an autocrine growth factor for brain tumors. However, it remains unclear whether the cAMP/protein kinase A (PKA) signaling pathway plays a role in mediating the mitogenic effects of GRP. We show here that GRP combined with agents that stimulate the cAMP/PKA pathway promotes proliferation of human gliobastoma cells. Treatment with GRP combined with the adenylyl cyclase activator forskolin, the cAMP analog 8-Br-cAMP or the phosphodiesterase type IV inhibitor rolipram increased proliferation of U138-MG cells in vitro measured by MTT assay. None of the compounds had an effect when given alone. GRP receptor (GRPR) mRNA and protein expression in U138-MG cells was detected by reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. The results suggest that GRP and the GRPR interact with the cAMP/PKA signaling pathway in stimulating cancer cell proliferation.

Sodium butyrate enhances the cytotoxic effect of antineoplastic drugs in human lymphoblastic T-cells

Sodium butyrate (NaB), a potent histone deacetylase inhibitor, induces cell cycle arrest and apoptosis in malignant cells. We investigated the effects on cellular proliferation in vitro when combining NaB with antineoplastic drugs commonly used to treat leukemias. Our results demonstrate that NaB increases the cytotoxic effects of cytarabine and etoposide, but not of bleomycin, doxorubicin, vincristine or methotrexate. These data suggest that NaB is a promising adjuvant therapeutic agent for the treatment of lymphoblastic leukemias, and provides a basis for further studies in this field.

Infection by Rhodotorula sp. in children receiving treatment for malignant diseases

Rhodotorula sp. are commensal yeasts that may cause opportunistic infections. There have been only a few case reports of Rhodotorula fungemia in children with cancer, and in all of them the patients had a central venous catheter inserted. The authors report three nonfatal cases of fungemia by Rhodotorula in patients with post-chemotherapy neutropenia. Two of three patients required catheter removal, and a response was achieved with systemic antifungal therapy. Aggressive therapy may be required for selected high-risk patients.

Outcome of pediatric recurrent and refractory malignant solid tumors following ifosfamide/carboplatin/etoposide (ICE): A phase II study in a pediatric oncology centre in Brazil

BACKGROUND

Therapeutic trials using ifosfamide,carboplatin, and etoposide (ICE) regimen have suggested many patients with refractory/relapsed solid tumors may be rendered free of disease using this combination. The aim of this study was to assess the feasibility, response and toxicity of this regimen in a Brazilian Pediatric Oncology Centre.

PROCEDURE

ICE, consisting of ifosfamide 3 g/m(2)/day x3 plus Mesna, etoposide 160 mg/m(2)/day x3, and carboplatin 400 mg/m(2)/day x2 was given at 21-28 days intervals. G-CSF was used for patients with hematological recovery greater than 4 weeks.

RESULTS

Twenty-one patients younger than 18 years of age treated with this regimen were studied between July 1996 and November 2000. A total of 93 courses of ICE were administered. Leucopenia/neutropenia grades 3/4 were the most frequent severe adverse effects (82%). Grade 3/4 thrombocytopenia occurred in 73% of cycles, and anemia was common (61%). The most common grade 3/4 non-hematologic toxicities were fever and proved infection occurring in 25% and 14% of the courses, respectively. Two patients developed renal tubular damage. Other less common grade 3/4 non-hematologic toxicities included nausea and vomiting, hepatotoxicity, and stomatitis. The overall response rate (complete response/partial response) was 53%. The median progression-free interval was 15.3 months, with a median survival of 24.2 months.

CONCLUSIONS

Although ICE was associated with severe myelosuppression it produced objective response in about half of the cases. The most important non-hematological toxicity was severe renal tubular damage. This regimen should only be used whenever hematological and infectious supportive care is available.

[Clinical and epidemiological analysis of bone marrow transplantation in a pediatric oncology unit]

OBJECTIVE

To describe the demographics and the most important acute clinical complications in patients undergoing bone marrow transplantation in the Pediatric Oncology Unit at Hospital de Clínicas de Porto Alegre, Brazil.

MATERIAL AND METHODS

A retrospective analysis was performed including 41 patients treated between August 1997 and June 2002. Twenty patients received allogeneic transplants (AG) and 21 received autologous transplants (AT).

RESULTS

The mean age of AG patients was 8.9 +/- 5.4 years. Twelve patients were male. Stem cell sources were: bone marrow in 12 patients; peripheral blood in five; and unrelated cord blood in three. The diseases were acute lymphoid leukemia in seven patients; acute myeloid leukemia in four; chronic myeloid leukemia in two; myelodysplastic syndrome in two; Burkitt's lymphoma in one; severe combined immunodeficiency in one; Chediaki-Higashi syndrome in one; Fanconi anemia in one; and aplastic anemia in one. One patient developed grade II acute graft-versus-host-disease (GVHD), and three patients had grade IV GVHD. Three patients developed chronic GVHD. In all of them, the cell source was peripheral blood. Survival in this group was 70.0 +/- 10.3%. The main cause of death was GVHD in three patients and sepsis in another three. All deaths occurred before day 100. One of the patients who received unrelated cord blood is alive 3.5 years after the transplantation. In AG patients, mean age was 8.7 +/- 4.3 years. Eleven patients were male. The stem cell sources were: peripheral blood in 16; bone marrow in three; and peripheral blood + bone marrow in two. The diseases were: Wilms' tumor in five patients; Ewing's sarcoma family tumors in four; neuroblastoma in three; Hodgkin's disease in three; non-Hodgkin's lymphoma in one; rhabdomyosarcoma in two; neuroectodermic tumor of the central nervous system in two; acute myeloid leukemia in one. Survival in this group was 59.4 +/- 11.7%. Five patients died due to tumor relapse, two patients due to sepsis and one patient died in remission 20 months after bone marrow transplantation due to infection. In the whole group, the most common toxicities were vomiting, mucositis, diarrhea and abdominal pain. Infections were recorded in 58.5% of the patients. In 46.9%, at least one pathogen was isolated in the blood culture. The time required for neutrophil and platelet engraftment was correlated to the number of hematopoietic stem cell infused.

CONCLUSION

The overall survival in our patients is similar to that reported in the literature. We did not find differences between AT and AG patients regarding acute toxicities and infections.

High-dose chemotherapy and autologous peripheral blood stem cell rescue in a patient with pleuropulmonary blastoma

Pleuropulmonary blastoma (PPB) is a rare and aggressive malignant tumor of the lung. Approximately 80 cases of PPB have been published, and in only three cases high-dose chemotherapy with autologous hematopoietic stem cell transplantation (HSCT) was applied. A 5-year-old girl presenting with cough, fever, and shortness of breath was referred to the authors in March 1999. A computed tomography scan of the chest showed a tumor mass in the left hemithorax. The lesion was biopsied and the histopathologic report suggested the diagnosis of PPB. The patient received chemotherapy comprising vincristine, actinomycin D, and cyclophosphamide with only a minor response, and treatment was switched to ifosfamide, carboplatin, and etoposide, which produced a partial response. Tumor resection was performed, but margins were positive for PPB. Due to the high risk of recurrence, the authors elected to administrate high-dose chemotherapy using melphalan, etoposide, and carboplatin, followed by autologous HSCT. The patient achieved complete hematologic recovery, and reimaging after HSCT showed no evidence of disease. She relapsed 4 months later and died about 9 months after the completion of high-dose therapy. The role of high-dose chemotherapy and autologous HSCT is likely to be limited in PPB.

Use of amifostine in the therapy of osteosarcoma in children and adolescents

Amifostine protects normal tissue from the cytotoxic damage induced by radiation and chemotherapy. In this study, 39 consecutive newly diagnosed children with osteosarcoma were assessed; 20 received amifostine and 19 did not. The chemotherapy regimen included an induction phase of three cycles of cisplatin (100 mg/m2), carboplatin (500 mg/m2), and doxorubicin (60 mg/m2), followed by surgery. Alternating cycles of cisplatin/ifosfamide (9 mg/m2), ifosfamide/doxorubicin, carboplatin/doxorubicin, and ifosfamide/carboplatin were administered every 3 weeks to complete 26 weeks of treatment. Amifostine was administered 15 minutes before the infusions of cisplatin and carboplatin in a total of 193 infusions. Side effects during infusions and renal, hearing, and bone marrow toxicities were evaluated and compared between the two groups. Hypotension was observed in 28 (14.5%) infusions. No patient required discontinuation of therapy. Fewer than two episodes of vomiting occurred in 130 (71%) infusions and two to five episodes occurred in 51 (28%) infusions, and no patient had grade 4 toxicity. There was no difference between the two groups regarding renal toxicity (creatinine clearance). Neutropenia and leukopenia were significantly less frequent in the amifostine group. No difference was observed in platelet and hearing toxicities. Amifostine was well tolerated in doses of 740 mg/m2 in children and adolescents, and myelotoxicity was less severe in the amifostine group. This was a pilot study for further evaluation in a larger randomized trial.

[Bone marrow transplantation and cord blood transplantation in children]

OBJECTIVE: To review the indications, main steps and complications of bone marrow transplantation in children. SOURCES: Medline-based literature review. SUMMARY OF THE FINDINGS: We comment about the indications of autologous, allogeneic and syngeneic bone marrow transplantation, donor selections, harvest and infusion of the hematopoietic progenitor cells that will reconstitute the hematopoietic and immune systems. We describe the different conditioning regimens and the new sources of cells, such as cord blood. We also describe the most common events after the procedure, including infections, graft versus host disease, and cardiovascular, pulmonary, hepatic, genitourinary, and gastrointestinal complications. The late effects and their impact on quality of life are also discussed. CONCLUSIONS: Bone marrow transplantation does not confer an absolutely normal life span to all the patients; however, it represents the only chance of cure for children with certain neoplastic or immunological diseases. By knowing the steps of the procedure, pediatricians can be a source of information on bone marrow transplantation to the patients and their families.

Protein kinase C-mediated in vitro invasion of human glioma cells through extracellular-signal-regulated kinase and ornithine decarboxylase

We investigated the involvement of protein kinase C (PKC) in the in vitro invasiveness of the A-172, U-87 and U-373 human glioma cell lines, as well as the role of ornithine decarboxylase (ODC) and/or extracellular-signal-regulated kinase (ERK) in the actions of PKC. Thus, cells were treated under serum-free conditions with the PKC activator phorbol 12-myristate 13-acetate (PMA), or with the PKC inhibitors bisindolylmaleimide I (GF 109203X) or calphostin C in the absence or presence of the ODC inhibitor D,L-alpha-difluoromethylornithine (DFMO), and/or the mitogen-activated protein kinase/extracellular-signal-regulated kinase inhibitor 2'-amino-3'-methoxyflavone (PD 098059). Subsequently, cells were assessed for membrane-type 1 matrix metalloproteinase (MT1-MMP) mRNA contents, 72-kD latent, and 59/62-kD activated matrix metalloproteinase 2 (MMP-2) in conditioned media, as well as invasiveness. For these purposes, we used Northern blot analysis, gelatine zymography, and an in vitro filter invasion assay, respectively. Data were related to those found with untreated cells. PKC activity was 2- to 3-fold stimulated by PMA (100 nM for 30 min), and about 2-fold inhibited by calphostin C (40 nM for 2 h) or GF 109203X (5 microM for 20 min). This was accompanied by a similar increase or decrease, respectively, in MT1-MMP mRNA expression, 59/62-kD MMP-2 activity, and in vitro invasion. Inhibition of ODC activity (about 2-fold by 24 h DFMO 5 mM), ERK activation (almost completely by 20 min PD 098059 50 microM), or both these enzymes simultaneously led to a reduction by about half in levels of MT1-MMP mRNA, 59/62-kD MMP-2 activity, and invasion in untreated as well as PMA-stimulated cells. The use of these compounds did not significantly alter the inhibitory effects of GF 109203X or calphostin C. Modulation of PKC and/or ERK activity resulted in corresponding changes in ERK and/or ODC activities, but interference with ODC affected neither ERK nor PKC. Our data suggest a regulatory role for PKC, in co-operation with ERK and ODC, in glioma cell invasion, by modulation of MT1-MMP mRNA expression and MMP-2 activation.

Vanilmandelic acid and homovanillic acid levels in patients with neural crest tumor: 24-hour urine collection versus random sample

Neuroblastoma is the most common solid tumor in childhood and is the most frequent neural crest tumor (NCT). More than 90% of the patients excrete high levels of vanilmandelic acid (VMA) and homovanillic acid (HVA) in the urine. Original biochemical methods for measuring these two metabolites of catecholamines employed a collection of urine for 24 hours to avoid errors related to circadian cycle variations. More recently, attempts have been made to replace the 24-hour collections by random samples (RSs). This has practical advantages particularly for young children. The objective of this study is to assess whether urinary VMA related to urinary creatinine levels can be determined reliably by the method of Pisano et al. from RSs in patients with NCT. The determination of the consumption of VMA in urine stored for prolonged periods of time was also studied. We found a good correlation between the values of metabolites of catecholamines in RSs compared with 24-hour urine collections. There was consumption of VMA in urine samples after storage. We conclude that determination of VMA in RSs of urine by Pisano's method may identify NCT production of catecholamines and that the consumption of these catecholamines is an important factor to consider in the interpretation of values obtained with stored urine specimens.