Valproic acid treatment response in vitro is determined by TP53 status in medulloblastoma.

PURPOSE: Histone deacetylate inhibitors (HDACi), as valproic acid (VA), have been reported to enhance efficacy and to prevent drug resistance in some tumors, including medulloblastoma (MB). In the present study, we investigated VA role, combined to cisplatin (CDDP) in cell viability and gene expression of MB cell lines. METHODS: Dose-response curve determined IC50 values for each treatment: (1) VA single, (2) CDDP single, and (3) VA and CDDP combined. Cytotoxicity and flow cytometry evaluated cell viability after exposure to treatments. Quantitative PCR evaluated gene expression levels of AKT, CTNNB1, GLI1, KDM6A, KDM6B, NOTCH2, PTCH1, and TERT, before and after treatment. Besides, we performed next-generation sequencing (NGS) for PTCH1, TERT, and TP53 genes. RESULTS: The most effective treatment to reduce viability was combined for D283MED and ONS-76; and CDDP single for DAOY cells (p < 0.0001). TERT, GLI1, and AKT genes were overexpressed after treatments with VA. D283MED and ONS-76 cells presented variants in TERT and PTCH1, respectively and DAOY cell line presented a TP53 mutation. CONCLUSIONS: MB tumors belonging to SHH molecular subgroup, with TP53MUT, would be the ones that present high risk in relation to VA use during the treatment, while TP53WT MBs can benefit from VA therapy, both SHH and groups 3 and 4. Our study shows a new perspective about VA action in medulloblastoma cells, raising the possibility that VA may act in different patterns. According to the genetic background of MB cell, VA can stimulate cell cycle arrest and apoptosis or induce resistance to treatment via signaling pathways activation.

Investigation of IGF2, Hedgehog and fusion gene expression profiles in pediatric sarcomas.

UNLABELLED: The childhood sarcomas are malignant tumors with high mortality rates. They are divided into two genetic categories: a category without distinct pattern karyotypic changes and the other category showing unique translocations that originate gene rearrangements. This category includes rhabdomyosarcoma (RMS), Ewing's sarcoma (ES) and synovial sarcoma (SS). Diverse studies have related development genes, such as; IGF2, IHH, PTCH1 and GLI1 and sarcomatogenesis. OBJECTIVE: To characterize the RMS, ES and SS rearrangements, we quantify the expression of IGF2 IHH, PTCH1 and GLI1 genes and correlate molecular data with clinical parameters of patients. DESIGN: We analyzed 29 RMS, 10 SS and 60 ES tumor samples by RT-PCR (polymerase chain reaction-reverse transcription) and qPCR (quantitative PCR). RESULTS: Among the samples of ARMS, 50% had rearrangements of PAX3/7-FOXO1, 60% of ES samples were EWS-FLI1 positive and 90% of SS samples were positive for SS18-SSX1/2. In relation to the control reference samples (QPCR Human Reference Total RNA-Stratagene, Human Skeletal Muscle Total RNA-Ambion, Universal RNA Human Normal Tissues-Ambion), RMS samples showed a high IGF2 gene expression (p<0.0001). Moreover, ES samples showed a low IGF2 gene expression (p<0.0001) and high IHH (p<0.0001), PTCH1 (p=0.0173) and GLI1 (p=0.0113) gene expressions. CONCLUSIONS: The molecular characterization of IGF and Hedgehog pathway in these pediatric sarcomas may collaborate to enable a better understanding of the biological behavior of these neoplasms.

Expression profiling using a cDNA array and immunohistochemistry for the extracellular matrix genes FN-1, ITGA-3, ITGB-5, MMP-2, and MMP-9 in colorectal carcinoma progression and dissemination.

Colorectal cancer dissemination depends on extracellular matrix genes related to remodeling and degradation of the matrix structure. This investigation intended to evaluate the association between FN-1, ITGA-3, ITGB-5, MMP-2, and MMP-9 gene and protein expression levels in tumor tissue with clinical and histopathological neoplastic parameters of cancer dissemination. The expression associations between ECM molecules and selected epithelial markers EGFR, VEGF, Bcl2, P53, and KI-67 have also been examined in 114 patients with colorectal cancer who underwent primary tumor resection. Quantitative real-time PCR and immunohistochemistry tissue microarray methods were performed in samples from the primary tumors. The gene expression results showed that the ITGA-3 and ITGB-5 genes were overexpressed in tumors with lymph node and distant metastasis (III/IV-stage tumors compared with I/II tumors). The MMP-2 gene showed significant overexpression in mucinous type tumors, and MMP-9 was overexpressed in villous adenocarcinoma histologic type tumors. The ECM genes MMP9 and ITGA-3 have shown a significant expression correlation with EGFR epithelial marker. The overexpression of the matrix extracellular genes ITGA-3 and ITGB-5 is associated with advanced stage tumors, and the genes MMP-2 and MMP-9 are overexpressed in mucinous and villous adenocarcinoma type tumors, respectively. The epithelial marker EGFR overactivity has been shown to be associated with the ECM genes MMP-9 and ITGA-3 expression.

SHH, WNT, and NOTCH pathways in medulloblastoma: when cancer stem cells maintain self-renewal and differentiation properties.

PURPOSE: Infant medulloblastoma (MB) is a malignant neuroepithelial embryonal tumor of the cerebellum, believed to derive from precursor granule cells with stem or progenitor cells appearance, and caused by a change in expression profile of genes related to the development. This work aims to study the expression profile of these genes in MB tumors, correlating with clinicopathological characteristics. METHODS: We quantified, by qPCR in 40 MB tumor samples, the expression of genes in HH (PTCH1, PTCH2, and GLI1), WNT (APC, CTNNB1, WIF1, and DKK2), and NOTCH pathways (NOTCH2 and HES1), which have a crucial role in development, and genes as MYCC, MYCN, and TERT, correlating this findings to patient's clinicopathological characteristics. RESULTS: Considering the universal RNA as our control sample, and considering the median of gene expression in the control samples as our cutoff, we observed that HES1 gene showed decreased expression compared to control (p = 0.0059), but patients with HES1 overexpression were directly related to a shorter survival (p = 0.0165). Individuals with higher GLI1 gene expression had significant shorter survival (p = 0.0469), and high expression was prevalent in patients up to 5 years old (p = 0.0479). Patients showing high PTCH2 expression were related to worse survival (p = 0.0426), and it was correlated with GLI1 high expression (p = 0.0094). We also observed a concomitant overexpression of WIF1 and DKK2 genes in a subgroup of MB samples (n = 11, p = 0.0118). CONCLUSIONS: Our results suggest the presence of activated developmental signaling pathways in MB, which are important for cell proliferation and maintenance, and that may be targeted for novel therapeutic options.

Tumor dynamics in response to antiangiogenic therapy with oral metronomic topotecan and pazopanib in neuroblastoma xenografts.

Metronomic chemotherapy, combined with targeted antiangiogenic drugs, has demonstrated significant anticancer efficacy in various studies. Though, tumors do acquire resistance. Here, we have investigated the effect of prolonged therapy with oral metronomic topotecan and pazopanib on tumor behavior in a neuroblastoma mouse xenograft model. SK-N-BE(2) xenograft-bearing mice were treated with either of the following regimens (daily, orally): vehicle (control), 150 mg/kg pazopanib, 1.0 mg/kg topotecan, and combination of topotecan and pazopanib. Planned durations of treatment for each regimen were 28, 56, and 80 days or until the end point, after which animals were sacrificed. We found that only combination-treated animals survived until 80 days. Combination halted tumor growth for up to 50 days, after which gradual growth was observed. Unlike single agents, all three durations of combination significantly lowered microvessel densities compared to the control. However, the tumors treated with the combination for 56 and 80 days had higher pericyte coverage compared to control and those treated for 28 days. The proliferative and mitotic indices of combination-treated tumors were higher after 28 days of treatment and comparable after 56 days and 80 days of treatment compared to control. Immunohistochemistry, Western blot, and real-time polymerase chain reaction revealed that combination treatment increased the hypoxia and angiogenic expression. Immunohistochemistry for Glut-1 and hexokinase II expression revealed a metabolic switch toward elevated glycolysis in the combination-treated tumors. We conclude that prolonged combination therapy with metronomic topotecan and pazopanib demonstrates sustained antiangiogenic activity but also incurs resistance potentially mediated by elevated glycolysis.

Establishment and cytogenetic characterization of a cell line from a pulmonary metastasis of osteosarcoma.

Osteosarcoma (OS) is the most frequent malignant bone tumour in children and adolescents. In metastatic patients, the most common site of metastasis is the lung. There are relatively few cell lines of metastatic OS reported in the literature and the cytogenetic aspects of OS metastases are still controversial and inconclusive. Here we describe the establishment of a new OS cell line, M-OS, from a pulmonary metastasis of a typical osteoblastic OS of an 11-year-old boy with metastatic OS at diagnosis. M-OS cells have been maintained in culture for over 50 passages for more than 1 year. M-OS was characterized by immunohistochemistry, conventional cytogenetics and fluorescence in situ hybridization (FISH). In order to evaluate in vitro cell modification, the immunohistochemical analysis was performed in three different moments of the cell line: 10th, 30th and 50th passages. The conventional cytogenetic analysis revealed the ploidy of M-OS cell line as near-diploid, with most metaphases hyperdiploid and tetraploid. We found a copy number gain of MDM2 gene as the most frequent alteration in the FISH analysis. The immunohistochemical analysis confirmed that M-OS cell line maintained the osteogenic nature even after all passages for the cell line establishment in vitro.

Investigation of PAX3/7-FKHR fusion genes and IGF2 gene expression in rhabdomyosarcoma tumors.

The purpose of our study was to investigate the prevalence of the PAX3/7-FKHR fusion genes and quantify the IGF2 gene expression in rhabdomyosarcoma (RMS) samples. Soft tissue sarcomas account 5% of childhood cancers and 50% of them are RMS. Morphological evaluation of pediatric RMS has defined two histological subtypes, embryonal (ERMS) and alveolar (ARMS). Chromosomal analyses have demonstrated two translocations associated with ARMS, resulting in the PAX3/7-FKHR rearrangements. Reverse transcriptase-polymerase chain reaction (RT-PCR) is extremely useful in the diagnosis of ARMS positive for these rearrangements. Additionally, several studies have shown a significant involvement of IGF pathway in the pathogenesis of RMS. The presence of PAX3/7-FKHR gene fusions was studied in 25 RMS samples from patients attending the IOP-GRAACC/UNIFESP and three RMS cell lines by RT-PCR. IGF2 gene expression was quantified by qPCR and related with clinic pathological parameters. Of the 25 samples, nine (36%) were ARMS and 16 (64%) were ERMS. PAX3/7-FKHR gene fusions expression was detected in 56% of ARMS tumor samples. IGF2 overexpression was observed in 80% of samples and could indicate an important role of this pathway in RMS biology.

Metronomic oral topotecan with pazopanib is an active antiangiogenic regimen in mouse models of aggressive pediatric solid tumor.

PURPOSE: Low dose metronomic (LDM) chemotherapy, combined with VEGF signaling pathway inhibitors, is a highly effective strategy to coordinately inhibit angiogenesis and tumor growth in many adult preclinical cancer models. We have tested the efficacies of daily oral LDM topotecan alone and in combination with pazopanib, a VEGF receptor inhibitor, in three pediatric extracranial solid tumor mouse models. EXPERIMENTAL DESIGN: In vitro dose-response study of topotecan and pazopanib was conducted on several neuroblastoma, osteosarcoma, and rhabdomyosarcoma cell lines. In vivo antitumor efficacies of the LDM topotecan and pazopanib as single agents and in combination were tested on 4 subcutaneous xenograft models and on 2 neuroblastoma metastatic models. Circulating angiogenic factors such as circulating endothelial cells (CEC), circulating endothelial pro genitor cells (CEP), and microvessel densities were used as surrogate biomarker markers of antiangiogenic activity. RESULTS: In vitro, topotecan caused a dose-dependent decrease in viabilities of all cell lines, while pazopanib did not. In vivo, combination of topotecan + pazopanib (TP + PZ) showed significant antitumor activity and significant enhancement in survival compared with the respective single agents in all models. Reductions in viable CEP and/or CEC levels and tumor microvessel density were correlated with tumor response and therefore confirmed the antiangiogenic activity of the regimens. Pharmacokinetic studies of both drugs did not reveal any drug-drug interaction. CONCLUSION: Metronomic administration of TP + PZ showed a statistically significant antitumor activity compared with respective single agents in pediatric tumor mouse models and represent a valid option as a maintenance therapy in aggressive pediatric solid tumors.

Insights on PRAME and osteosarcoma by means of gene expression profiling.

BACKGROUND: Osteosarcoma (OS) is the most frequent bone tumor in children and adolescents. Tumor antigens are encoded by genes that are expressed in many types of solid tumors but are silent in normal tissues, with the exception of placenta and male germ-line cells. It has been proposed that antigen tumors are potential tumor markers. OBJECTIVES: The premise of this study is that the identification of novel OS-associated transcripts will lead to a better understanding of the events involved in OS pathogenesis and biology. METHODS: We analyzed the expression of a panel of seven tumor antigens in OS samples to identify possible tumor markers. After selecting the tumor antigen expressed in most samples of the panel, gene expression profiling was used to identify osteosarcoma-associated molecular alterations. A microarray was employed because of its ability to accurately produce comprehensive expression profiles. RESULTS: PRAME was identified as the tumor antigen expressed in most OS samples; it was detected in 68% of the cases. Microarray results showed differences in expression for genes functioning in cell signaling and adhesion as well as extracellular matrix-related genes, implying that such tumors could indeed differ in regard to distinct patterns of tumorigenesis. CONCLUSIONS: The hypothesis inferred in this study was gathered mostly from available data concerning other kinds of tumors. There is circumstantial evidence that PRAME expression might be related to distinct patterns of tumorigenesis. Further investigation is needed to validate the differential expression of genes belonging to tumorigenesis-related pathways in PRAME-positive and PRAME-negative tumors.

Bone deposition, bone resorption, and osteosarcoma.

Bone deposition and bone resorption are ongoing dynamic processes, constituting bone remodeling. Some bone tumors, such as osteosarcoma (OS), stimulate focal bone deposition. OS is the most common primary bone tumor in children and young adults. A complex network of genes regulates bone remodeling and alterations in its expression levels can influence the genesis and progression of bone diseases, including OS. We hypothesized that the expression profiles of bone remodeling regulator genes would be correlated with OS biology and clinical features. We used real-time PCR to evaluate the mRNA levels of the tartrate-resistant acid phosphatase (ACP5), colony stimulating factor-1 (CSF1R), bone morphogenetic protein 7 (BMP7), collagen, type XI, alpha 2 (COL11A2), and protein tyrosine phosphatases zeta 1 (PTPRZ1) genes, in 30 OS tumor samples and correlated with clinical and histological data. All genes analyzed, except CSF1R, were differentially expressed when compared with normal bone expression profiles. In our results, OS patients with high levels of COL11A2 mRNA showed worse overall (p = 0.041) and event free survival (p = 0.037). Also, a trend for better overall survival was observed in patients with samples showing higher expression of BMP7 (p = 0.067). COL11A2 overexpression and BMP7 underexpression could collaborate to OS tumor growth, through its central role in bone remodeling process.