Supplementary Table 1 from TWIST-1 Is Overexpressed in Neoplastic Choroid Plexus Epithelial Cells and Promotes Proliferation and Invasion

Choroid plexus carcinomas (CPCs) are rare tumors with dismal outcome. While it has been established that surgery, radiotherapy, and chemotherapy improve survival, the best chemotherapy drugs for treating this disease still need to be identified. Since CPC is too rare to permit a prospective clinical trial, we performed a meta-analysis to evaluate the effects of individual drugs in patients with CPCs. We expanded a pre-existing database and included all cases of choroid plexus tumors, identified in PubMed through the end of 2007, for a total of 906 patients. At first, we restricted the analysis to patients with histologically confirmed CPC (n = 361) and with residual tumor after surgery (n = 130/361 patients), and we compared response and survival between patients who received a particular drug and those who did not. Response to chemotherapy was documented in 43 patients. Of the drugs used in these patients, etoposide was associated with the highest response rate (17/36). Next survival was compared among all CPC. Kaplan-Meier curves and log-rank tests suggested a statistically significant treatment benefit for cyclophosphamide, etoposide, and carboplatin, while the effect of vincristine was found to be marginally significant (P = 0.07, log rank). Of these, only etoposide's effect could be confirmed in a limited Cox multiple regression analysis. In conclusion, etoposide should be included in future standard treatment protocols. However the survival rates are still unsatisfactory, and additional novel drugs should be studied in prospective multicenter studies.

Atypical teratoid/rhabdoid tumors are malignant embryonal tumors characterized by the presence of rhabdoid cells, genetic alterations affecting the SMARCB1 gene (hSNF5/INI1), and a poor prognosis. Whether INI1 plays a role in the pathogenesis of other central nervous system tumors is uncertain. We report on cases of 2 young children with unusual intracranial nonrhabdoid neuroectodermal tumors within and around the third or fourth ventricle that are characterized by cribriform strands and trabeculae and well-defined epithelial membrane antigen-immunopositive surfaces and show INI1 protein loss. Histological and immunohistochemical features did not correspond to established tumor types, including atypical teratoid/rhabdoid tumors, medulloepithelioma, choroid plexus carcinoma, and ependymoma. Fluorescence in situ hybridization analyses failed to identify chromosomal alterations affecting the SMARCB1 locus, but sequencing revealed a homozygous 4-bp duplication in exon 4 (492duplCCTT) in one of the tumors. Both children responded well to conventional adjuvant therapy protocols and are alive and in complete remission longer than 5 years postoperatively. We suggest that cribriform neuroepithelial tumor (CRINET) is a nonrhabdoid ventricular tumor that shows loss of tumoral INI1 protein and has a relatively favorable prognosis.

Aberrant methylation of the MGMT (O6-methylguanine-DNA methyltransferase) DNA-repair gene is a predictive marker for the response to chemotherapy with alkylating agents (e.g., temozolomide) in malignant gliomas. Since temozolomide is considered for the treatment of choroid plexus tumors, MGMT promoter methylation status was retrospectively assessed in 36 choroid plexus tumors using methylation specific PCR, combined bisulfite restriction analysis (COBRA), and clone sequencing. By methylation specific PCR, all samples demonstrated a signal for MGMT methylation. COBRA confirmed >10% methylation of CpGs 17 and 31 in 58% of tumors. Clone sequencing of six cases methylated by COBRA confirmed aberrant methylation including a previously recognized enhancer element. In conclusion, MGMT promoter methylation is frequent in choroid plexus tumors and can be quantified using COBRA. Determination of MGMT promoter methylation status might be useful for the stratification of patients for alkylator-based treatments in future clinical trials.

Abstract The pathogenesis of choroid plexus papillomas, intraventricular papillary neoplasms most often occurring sporadically in children and young adults, remains poorly understood. To identify pathways operative in the development of choroid plexus papillomas, gene expression profiles obtained from laser-microdissected human choroid plexus papilloma cells (n = 7) were compared with that of normal choroid plexus epithelial cells laser microdissected from autopsy tissue (n = 8). On DNA microarray data analysis, 53 probe sets were differentially expressed in choroid plexus papilloma tumor cells (>7-fold). Up-regulation of TWIST1, WIF1, TRPM3, BCLAF1, and AJAP1, as well as down-regulation of IL6ST was confirmed using quantitative reverse transcription-PCR. Knockdown of Twist1 gene expression in the rat choroid plexus epithelial cell line Z310 significantly reduced proliferation as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell invasion in a Matrigel assay, whereas cell migration was not affected. Screening for expressional changes of cancer-related genes upon Twist1 knockdown revealed up-regulation of Cdkn1a, Cflar, and Serpinb2 and down-regulation of Figf. To conclude, using gene expression profiling, several genes differentially expressed in human choroid plexus papillomas could be identified. Among those, TWIST1 is highly expressed in choroid plexus papillomas and promotes proliferation and invasion. [Cancer Res 2009;69(6):2219–23]

Little is known on pathways involved in the pathogenesis of choroid plexus tumors (CPTs). The finding of overexpression of Wnt inhibitory factor‐1 (Wif‐1) prompted us to investigate the functional role of Wif‐1 as well as nuclear accumulation of beta‐catenin in CPT. In Z310 neoplastic choroid plexus epithelial cells, silencing of Wif1 expression increased proliferative activity not associated with increased canonical Wnt signaling. Nuclear beta‐catenin accumulation was also lacking in a series of 16 CPT. In conclusion, our data show that Wif‐1 inhibits proliferation of neoplastic choroid plexus epithelial cells, but argue against a role of canonical Wnt/wingless signaling in CPT. Pediatr Blood Cancer 2009;53:1152–1155. © 2009 Wiley‐Liss, Inc.

Atypical choroid plexus papilloma (APP) represents a novel intermediate-grade subtype of choroid plexus tumor (CPT), the clinical outcome of which has not been described yet. We present the first analysis of a group of APP patients enrolled in the ongoing CPT-SIOP-2000 study of CPTs. A worldwide registration and a randomized trial for those patients who require chemotherapy started in 2000. For APP, maximal surgical resection was recommended. After surgery, patients who had undergone complete resection were observed, whereas patients with incompletely resected or metastasized APP were treated with six chemotherapy courses (etoposide and vincristine, combined with either carboplatin or cyclophosphamide). Risk-adapted radiotherapy was given only to patients older than 3 years of age. Of the 106 patients with a centrally confirmed CPT histology, 30 had APP, 42 CPP and 34 CPC. APP patients were significantly younger (median = 0.7 years) than patients with CPP or CPC (both medians = 2.3 years). Complete resection was achieved in 68 (64%) patients (79% in CPP, 63% in APP, and 47% in CPC). Metastases were present at diagnosis in 17% of APP patients, 5% of CPP patients, and 21% of CPC patients. All nine APP patients who received postoperative chemotherapy showed an early response after two cycles: two had complete remission, four had partial response, and three had stable disease. In the observation group of 15 patients, one event was seen, and all patients were alive. In the treatment group, one patient with a metastasized tumor and incompletely resected APP died. While APP was defined histologically, median percentages of both the Ki-67/MIB-1 proliferation marker and the p53 tumor suppressor protein increased across the three histological subtypes (from CPP to APP and then CPC), suggesting that the subtypes comprise an ordinal categorization of increasingly severe CPT tumors. This ordering was reiterated by clinical outcome in the 92 patients treated per the study protocol, with 5-year EFS rates of 92% in 39 CPP patients, 83% in 24 APP patients, and 28% in 29 CPC patients. A similar ordering was seen when all 106 patients were evaluated for EFS. APP responded favorably to chemotherapy. The intermediate position of APP between CPP and CPC was supported by the clinical data.

Choroid plexus tumors are intraventricular neoplasms predominantly affecting young children. In contrast to choroid plexus papillomas, choroid plexus carcinomas progress frequently, necessitating the development of adjuvant treatment concepts. Platelet derived growth factor (PDGF) signaling has been shown to support growth in a variety of tumors. The finding of PDGF receptor expression in choroid plexus tumors prompted us to elucidate PDGF receptor activation state using a novel method, in situ proximity ligation assay, on formalin-fixed, paraffin-embedded, archival samples of 19 choroid plexus tumors. As assessed by in situ proximity ligation assay, the proportion of phosphorylated PDGF receptor alpha was low in choroid plexus papillomas and choroid plexus carcinomas, whereas phosphorylated PDGF receptor beta was found to be significantly higher in choroid plexus carcinomas. In the immortalized choroid plexus epithelial cell line Z310 expressing PDGF receptor beta, PDGF-BB exhibited a time- and dose-dependent proliferative response, which was significantly attenuated by imatinib (gleevec). In conclusion, our findings suggest that PDGF receptor beta is functionally involved in the biology of choroid plexus tumors and may represent a molecular target for therapy. In addition, this study demonstrates the feasibility and usefulness of in situ proximity ligation assay for monitoring receptor tyrosine kinase activation in formalin-fixed, paraffin-embedded, archival tissues.