PROX1 is a predictor of survival for gliomas WHO grade II

Background:

The clinical course of World Health Organisation grade II gliomas remains variable and their time point of transformation into a more malignant phenotype is unpredictable. Identification of biological markers that can predict prognosis in individual patients is of great clinical value. PROX1 is a transcription factor that has a critical role in the development of various organs. PROX1 has been ascribed both oncogenic and tumour suppressive functions in human cancers. We have recently shown that PROX1 may act as a diagnostic marker for high-grade gliomas. The aim of this study was to address the prognostic value of PROX1 in grade II gliomas.

Methods:

A total of 116 samples were evaluated for the presence of PROX1 protein. The number of immunopositive cells was used as a variable in survival analysis, together with established prognostic factors for this patient group.

Results:

Higher PROX1 protein was associated with poor outcome. In the multivariate analysis, PROX1 was identified as an independent factor for survival (P=0.024), together with the presence of mutated isocitrate dehydrogenase 1 R132H protein, and with combined losses of chromosomal arms 1p/19q in oligodendrocytic tumours.

Conclusion:

PROX1 is a novel predictor of survival for grade II gliomas.

Hot spots in dynamic (18)FET-PET delineate malignant tumor parts within suspected WHO grade II gliomas

Molecular imaging studies have recently found inter- and intratumoral heterogeneity in World Health Organization (WHO) grade II gliomas. A correlative analysis with tumor histology, however, is still lacking. For elucidation we conducted the current prospective study. Fifty-five adult patients with an MRI-based suspicion of a WHO grade II glioma were included. [F-18]Fluoroethyltyrosine ((18)FET) uptake kinetic studies were combined with frame-based stereotactic localization techniques and used as a guide for stepwise (1-mm steps) histopathological evaluation throughout the tumor space. In tumors with heterogeneous PET findings, the O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation status and expression of mutated protein isocitrate dehydrogenase variant R132H (IDH1) were determined inside and outside of hot spot volumes. Metabolic imaging revealed 3 subgroups: the homogeneous WHO grade II glioma group (30 patients), the homogeneous malignant glioma group (10 patients), and the heterogeneous group exhibiting both low- and high-grade characteristics at different sites (15 patients). Stepwise evaluation of 373 biopsy samples indicated a strong correlation with analyses of uptake kinetics (p < 0.0001). A homogeneous pattern of uptake kinetics was linked to homogeneous histopathological findings, whereas a heterogeneous pattern was associated with histopathological heterogeneity; hot spots exhibiting malignant glioma characteristics covered 4-44% of the entire tumor volumes. Both MGMT and IDH1 status were identical at different tumor sites and not influenced by heterogeneity. Maps of (18)FET uptake kinetics strongly correlated with histopathology in suspected grade II gliomas. Anaplastic foci can be accurately identified, and this finding has implications for prognostic evaluation and treatment planning.

Peptide mimotopes recognized by antibodies cetuximab and matuzumab induce a functionally equivalent anti-EGFR immune response

Aberrant activation of the epidermal growth factor receptor (EGFR) has been found in human cancers of various origins, and has been implicated in cancer pathogenesis. The therapeutic anti-EGFR antibodies cetuximab and matuzumab inhibit both ligand-induced receptor activation and growth of EGFR-expressing tumor cells. The efficacy of such EGFR-targeted therapies may be further enhanced by induction of functionally equivalent endogenous antibody responses. Here we describe novel peptide sequences selected from random peptide libraries for binding to single-chain antibody fragments of cetuximab or matuzumab. Two of these peptides characterized by KTL and YPLG motifs are recognized equally well by cetuximab and matuzumab, although nonoverlapping epitopes were previously reported for these antibodies. Immunization of experimental animals with synthetic KTL- and YPLG-containing peptides led to induction of antibodies that cross-react with human EGFR, and prevent binding of natural EGFR ligands, ligand-induced receptor activation and tumor cell growth in a manner similar to cetuximab and matuzumab. Our findings show that these peptide mimotopes can induce anti-EGFR antibodies with antitumoral activity, which may have implications for EGFR-specific cancer immunotherapy.

Influence of expression of EGFR and PTEN on outcome in patients with primary glioblastoma treated with standard radiochemotherapy and cetuximab: Interim analysis from the GERT-Protocol

2050

Background: The epidermal growth factor receptor (EGFR) is commonly amplified, overexpressed, and mutated in glioblastoma (GBM). Anti-EGFR treatments have shown to be associated with EGFR deletion mutant variant III (EGFRvIII) expression in presence of PTEN expression, suggesting a prognostic role of EGFRvIII expression. We determined molecular biomarkers and correlated these with outcome in the GERT trial. Methods: To date, 39 patients were treated within the GERT protocol (Combs SE et al., 2006) evaluating radiochemotherapy (RCHT) with temozolomide (TMZ) and weekly CTX. Pretreatment paraffin-embedded tumor tissue of 32 patients was available for molecular analysis. Twenty-three patients were male, 9 were female. Median age was 49 years. We analyzed amplification of EGFR, expression of EGFR, EGFRvIII, the tumor-suppressor PTEN and O(6)-methylguanine DNA methyltransferase (MGMT) gene promoter methylation. Results: Median follow-up was 12 months. Overall survival (OS) at 12 and 24 months was 89% and 42%. Progression-free survival (PFS) was 76% and 45% at 6 and 12 months, respectively. MGMT promoter hypermethylation was detected in 16/32 tumours. Methylated MGMT did not impact PFS or OS (p = 0.48 and p = 0.08). Data on EGFR copy number of 31/32 tumors showed EGFR gene amplification in 11 tumors. EGFR protein expression was found in 23/32 patients. EGFR-amplification did not impact PFS or OS (p = 0.56, p = 0.3). Patients with EGFR expression showed longer PFS (p = 0.05), but unaltered OS (p = 0.06). EGFRvIII was seen in 5/32 patients, only in tumors with EGFR amplification. Expression of EGFRvIII did not influence PFS (p = 0.26) or OS (p = 0.09). Reduced PTEN (22/32) did not influence PFS or OS (p = 0.27, p = 0.85). Outcome was not associated with coexpression of EGFRvIII and PTEN (n = 5); coexpression of EGFR and PTEN (n = 13) significantly influenced PFS (p = 0.005), but not OS (p = 0.10). Conclusions: Expression of EGFR, and coexpression of EGFR/PTEN is associated with significant increase in PFS after RCHT with TMZ and CTX. EGFR-amplification, reduction of PTEN expression and expression of EGFRvIII did not impact PFS nor OS. Randomized data in the primary treatment of GBM might help identify patients for anti-EGFR therapies.

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An over-the-scope clip (OTSC) system for closure of iatrogenic colon perforations: results of an experimental survival study in pigs

BACKGROUND AND STUDY AIM

Perforation of the colon is a relatively rare complication of flexible endoscopy of the lower gastrointestinal tract. It has a reported incidence from between 0.2 % in diagnostic procedures to 0.5 % - 3 % in therapeutic procedures. Given the growing number of colonoscopies, the absolute number of iatrogenic perforations is not unimportant. The treatment of choice is most often surgical repair, since reliable and simple endoscopic techniques for perforation closure are currently unavailable. We aimed to evaluate our novel over-the-scope clip (OTSC) system for closure of iatrogenic perforations.

MATERIAL AND METHODS

We have developed a nitinol clip that will capture perforations of 10 - 15 mm, compressing the lesions until healing. The OTSC was studied in a prospective experimental trial in pigs (50 - 60 kg, n=10) for the closure of an iatrogenic perforation of approximately 5 --10 mm on the serosal side, that was created by repeated endoscopic biopsy. The follow-up period was 12 weeks. Follow-up colonoscopy was performed at 4 and 12 weeks. Successful, tight closure of the lesion with absence of peritonitis in the postoperative course was the primary endpoint of the study.

RESULTS

Nine animals had an uneventful clinical course. At termination of the study, macroscopic and microscopic examination of the clipping sites in the bowel wall showed normal tissue healing. One animal died 1 day postoperatively for reasons unrelated to the procedure.

CONCLUSIONS

In this experimental study the OTSC clip system was found to be a simple and secure closure method for iatrogenic colon perforations, and thus might be an alternative to surgical repair.

Vacuolar protein sorting: two different functional states of the AAA-ATPase Vps4p

The vacuolar protein sorting (Vps) pathway, in which Vps4 class I AAA-ATPases play a central role, regulates growth factor receptors, immune response, and developmental signaling, and participates in tumor suppression, apoptosis, and retrovirus budding. We present the first atomic structure of the nucleotide-free yeast His(6)DeltaNVps4p dimer and its AMPPNP (5'-adenylyl-beta,gamma-imidodiphosphate)-bound tetradecamer, derived from a cryo electron microscopy map. Vps4p dimers form two distinct heptameric rings and accommodate AAA cassettes in a head-to-head--not in a head-to-tail-fashion as in class II AAA-ATPases. Our model suggests a mechanism for disassembling ESCRT (endosomal sorting complex required for transport) complexes by movements of substrate-binding domains located at the periphery of the tetradecamer during ATP hydrolysis in one ring, followed by translocation through the central pore and ATP hydrolysis in the second ring.

Frequent loss of expression of the pro-apoptotic protein Bim in renal cell carcinoma: evidence for contribution to apoptosis resistance

Renal cell carcinoma (RCC) is resistant to chemotherapy, and this resistance is mirrored by a high apoptosis resistance of many RCC lines in vitro. Here, we report the loss of the pro-apoptotic BH3-only protein Bim in a large part of clinical RCC cases and provide evidence for a functional relevance of this loss. Immunohistochemistry of clear cell renal cell carcinoma cases and corresponding normal kidney showed strong Bim reactivity in renal tubules of all cases but loss of Bim in 35 of 45 RCC samples. Out of nine RCC cell lines investigated, six showed strongly diminished or undetectable levels of Bim protein by western blotting. Four RCC lines of varying apoptosis sensitivity were analysed further. Bcl-2, Bcl-x(L), Mcl-1, Bax and Bak expression did not correlate with apoptosis sensitivity. All cell lines underwent apoptosis upon forced expression of Bax and Bim, suggesting an upstream difference. In all four lines, adriamycin induced p53 but not its targets Puma or Noxa. However, apoptosis sensitivity correlated with levels of Bim protein. Bim siRNA reduced apoptosis sensitivity in a susceptible cell line. Furthermore, inhibition of histone deacetylation restored Bim expression in cell lines. These data suggest that Bim has a function as a tumor suppressor in RCC.

Regulation of a transmembrane protein gene family by the small RNA-binding proteins TbUBP1 and TbUBP2

The loci Tb927.3.4070, 927.3.4080, Tb927.3.4090, 927.3.4100 and 927.3.4110 of Trypanosoma brucei encode five similar proteins with 13-14 transmembrane domains. Corresponding mRNAs are more abundant in bloodstream-form trypanosomes than in procyclics. The 4070, 4090 and 4110 genes have almost identical 3'-intergenic regions and the predicted proteins share a short C-terminal extension; a reporter mRNA with the 4110 3'-untranslated region was more abundant in bloodstream forms than procyclic forms. The 3'-untranslated regions for 4080 and 4100 are different, and that of 4080 gave procyclic-specific reporter expression. TbUBP1 and 2 are proteins with low-specificity RNA-binding activity. Over-expression of TbUBP2 in bloodstream forms increased the overall abundance of mRNA encoding the transmembrane proteins, whereas TbUBP1 and 2 RNA interference decreased it. RNAi targeting TbUBP1 and 2 in bloodstream forms decreased mRNA with a 4110 3'-untranslated region, but increased it for 4080. Thus TbUBP and TbUBP2 may accentuate developmental regulation of the Tb927.3.4070-927.3.4110 mRNAs.