P18.06.B ETS-Transcription Factor inhibitors are effective inTERT promoter mutated meningioma cells in vitro

Background

TERT promoter mutations in meningiomas were recently found to be strongly prognostic and associated with malignant progression and risk of recurrence. As result, the mutation in the TERT promoter generates a binding site for E twenty-six (ETS) transcription factors. Consequently, ETS-transcription factor inhibition might represent a novel strategy to impede meningioma growth. In a prior study we could demonstrate effectiveness of the ETS-transcription factor inhibitor YK-4-279 in TERT promoter mutant meningiomas. Recently, TK216 the clinical derivative of YK-4-279 was developed. Therefore, we aimed to clarify whether TK216 might have an increased effect as compared to YK-4-279 in TERT promoter mutated meningioma cells in vitro.

Methods

A meningioma-derived cell line (BTL695) generated from a TERT promoter mutated (C228T) anaplastic meningioma served as cell model for the experiments. BTL695 was characterized by high telomerase activity and TERT mRNA expression as analysed by the TRAP assay and RT-PCR, respectively. Genomic aberrations were verified using Ion Torrent Oncomine Comprehensive Assay v3-based next-generation sequencing (NGS). The sensitivity of BTL695 to YK-4-279 and TK216 was determined using an MTT-based viability assay (EZ4U). To elucidate the effectiveness of TK216 on cell cycle and apoptosis, cells were stained with PI and annexin V, respectively, and measured by flow cytometry. The effect of TK216 on the protein expression of the cleaved poly(ADP-ribose) polymerase-1 (PARP-1), indicative for apoptosis, was investigated by western blot. Additionally, a TK216-resistant cell model (BTL695res) was generated and analysed by NGS.

Results

BTL695 was significantly more sensitive to TK216 as compared to YK-4-279 (p<0.0001) characterized by the distinctly lower IC50 value of TK216 exposed cells (0.7 µM TK216; 1.6 µM YK-4-279). Flow cytometry analysis revealed a TK216 induced G2M cell cycle arrest and increased apoptosis rate, which was additionally verified by the expression of cleaved PARP-1 expression using western blot. Genomic aberrations were found in 18 genes including NF2, CDKN2A/B, ARID1A and PTEN. Interestingly, although the majority of genomic alterations was persistent in the TK216 resistant cell model, a p53 mutation was newly acquired as compared to the parental cell line.

Conclusion

In summary, our results indicate that ETS transcription factor inhibition by TK216 exerts antitumour activity in our TERT promoter mutant meningioma cell model. Additionally, the sensitivity against TK216 is superior to YK-4-279 and therefore TK216 may represent a promising new therapeutic option for patients with aggressive, TERT promoter mutated meningioma.

P10.08.A Lipogenesis inhibition by fatostatin shows effectiveness in glioblastoma models highly expressing fatty acid synthase (FASN)

Background

Glioblastoma (GBM) is the most common and most aggressive primary brain tumour in adults. Despite intensive treatment, the medium overall survival of GBM patients remains below 20 months after diagnosis. Therefore, new tumour specific targets allowing successful therapeutic treatment are needed to distinctly enhance GBM patient overall survival. Reprogramming of lipid metabolism leading to highly upregulated anabolic pathways, like phosphatidylinositol-3-kinase (PI3K)/AKT pathway and subsequently lipogenesis, is a hallmark of cancer cells including glioblastomas to meet increased energy demands for proliferation and cell growth. Accordingly, lipogenesis inhibition might be a promising strategy to impede GBM cell growth. Therefore, it was aim of our study to analyse the effect of the lipogenesis inhibitor fatostatin on downstream targets e.g. fatty acid synthase (FASN) and its impact on cell growth in GBM cells in vitro.

Material and Methods

In a cohort of 52 GBM-derived cell lines, FASN mRNA was investigated by qRT-PCR. The impact of fatostatin on cell viability (IC50) was analysed in selected cell lines using cell viability assays (Cell Titer Glo®). To elucidate whether fatostatin exposure affects cell migration, wound healing assays were performed. The effect of fatostatin on cell cycle and apoptosis was analysed by flow cytometry. Additionally, expression of FASN and level of phosphorylated AKT, the active form of AKT serine/threonine kinase, were examined before and after fatostatin treatment with qRT-PCR (mRNA) and Western blot (protein), respectively.

Results

FASN mRNA was found to be expressed at varying levels in our GBM-derived cell line cohort (n=52). Compared to normal astrocytes, FASN mRNA expression was significantly upregulated in GBM cells (p=0.0127). Furthermore, high FASN mRNA expression was significantly associated with higher sensitivity against fatostatin (p=0.0352). Regarding corresponding recurrences, the response to the inhibitor was shown to be persistent. Accordingly, the effectiveness of fatostatin treatment resulted in substantial downregulation of AKT phosphorylation and consequently in the induction of apoptosis and G2/M arrest of the cell cycle. In addition, a significant inhibition of the migration potential by fatostatin treatment was observed.

Conclusion

In summary, FASN expression represents a promising biomarker and therapy target within the lipid metabolism indicated by a significant sensitivity to fatostatin in FASN overexpressing GBM cell lines. Consequently, lipogenesis inhibition by fatostatin might be a promising novel therapeutic option in glioblastoma.

TERT expression is susceptible to BRAF and ETS-factor inhibition in BRAFV600E/TERT promoter double-mutated glioma

The BRAF gene and the TERT promoter are among the most frequently altered genomic loci in low-grade (LGG) and high-grade-glioma (HGG), respectively. The coexistence of BRAF and TERT promoter aberrations characterizes a subset of aggressive glioma. Therefore, we investigated interactions between those alterations in malignant glioma. We analyzed co-occurrence of BRAFV600E and TERT promoter mutations in our clinical data (n = 8) in addition to published datasets (n = 103) and established a BRAFV600E-positive glioma cell panel (n = 9) for in vitro analyses. We investigated altered gene expression, signaling events and TERT promoter activity upon BRAF- and E-twenty-six (ETS)-factor inhibition by qRT-PCR, chromatin immunoprecipitation (ChIP), Western blots and luciferase reporter assays. TERT promoter mutations were significantly enriched in BRAFV600E-mutated HGG as compared to BRAFV600E-mutated LGG. In vitro, BRAFV600E/TERT promoter double-mutant glioma cells showed exceptional sensitivity towards BRAF-targeting agents. Remarkably, BRAF-inhibition attenuated TERT expression and TERT promoter activity exclusively in double-mutant models, while TERT expression was undetectable in BRAFV600E-only cells. Various ETS-factors were broadly expressed, however, only ETS1 expression and phosphorylation were consistently downregulated following BRAF-inhibition. Knock-down experiments and ChIP corroborated the notion of a functional role for ETS1 and, accordingly, all double-mutant tumor cells were highly sensitive towards the ETS-factor inhibitor YK-4-279. In conclusion, our data suggest that concomitant BRAFV600E and TERT promoter mutations synergistically support cancer cell proliferation and immortalization. ETS1 links these two driver alterations functionally and may represent a promising therapeutic target in this aggressive glioma subgroup.

TERT promoter mutations are associated with poor prognosis and cell immortalization in meningioma

Background

Meningiomas are mostly benign tumors tending to progress to higher-grade lesions. Mutations in the telomerase reverse transcriptase (TERT) gene promoter are comparably rare in meningioma, but were recently suggested to predict risk of recurrence and progression. Here we have analyzed a cohort of World Health Organization grades I-III meningiomas regarding the impact of TERT promoter mutations on patient prognosis and in vitro cell propagation feasibility.

Methods

From 110 meningioma patients, 128 tissue samples were analyzed for the TERT promoter mutations C228T and C250T by direct sequencing. Of the 128 samples, 121 were tested for cell propagation in vitro. Telomerase activity, TERT mRNA expression, and telomere lengths were investigated by telomeric repeat amplification protocol assay, reverse transcription PCR, and quantitative PCR, respectively. Impact of the E-twenty-six (ETS) transcription factor inhibitor YK-4-279 on cell viability and TERT promoter activity was analyzed.

Results

TERT promoter mutations were found in 5.5% of all samples analyzed and were associated with a significantly upregulated telomerase activity and TERT mRNA expression (P < 0.0001 both). Regarding telomere lengths, no significant difference between the TERT promoter wild-type and mutated subgroups was detected. Patients with TERT promoter mutated tumors exhibited significantly shorter overall survival (P = 0.0006; 53.8 vs 115.6 mo). The presence of TERT promoter mutations but not telomerase activity or TERT mRNA expression predicted indefinite cell growth in vitro. TERT promoter mutated meningioma cells were hypersensitive against the ETS transcription factor inhibitor YK-4-279, inducing a distinct downregulation of TERT promoter activity.

Conclusion

TERT promoter mutations drive meningioma aggressiveness, resulting in reduced patient survival, but might also open novel therapeutic options for progressive disease.

Telomerase activation in posterior fossa group A ependymomas is associated with dismal prognosis and chromosome 1q gain

Background

Ependymomas account for up to 10% of childhood CNS tumors and have a high rate of tumor recurrence despite gross total resection. Recently, classification into molecular ependymoma subgroups has been established, but the mechanisms underlying the aggressiveness of certain subtypes remain widely enigmatic. The aim of this study was to dissect the clinical and biological role of telomerase reactivation, a frequent mechanism of cancer cells to evade cellular senescence, in pediatric ependymoma.

Methods

We determined telomerase enzymatic activity, hTERT mRNA expression, promoter methylation, and the rs2853669 single nucleotide polymorphism located in the hTERT promoter in a well-characterized cohort of pediatric intracranial ependymomas.

Results

In posterior fossa ependymoma group A (PF-EPN-A) tumors, telomerase activity varied and was significantly associated with dismal overall survival, whereas telomerase reactivation was present in all supratentorial RelA fusion-positive (ST-EPN-RELA) ependymomas. In silico analysis of methylation patterns showed that only these two subgroups harbor hypermethylated hTERT promoters suggesting telomerase reactivation via epigenetic mechanisms. Furthermore, chromosome 1q gain, a well-known negative prognostic factor, was strongly associated with telomerase reactivation in PF-EPN-A. Additional in silico analyses of gene expression data confirmed this finding and further showed enrichment of the E-twenty-six factor, Myc, and E2F target genes in 1q gained ependymomas. Additionally, 1q gained tumors showed elevated expression of ETV3, an E-twenty-six factor gene located on chromosome 1q.

Conclusion

Taken together we describe a subgroup-specific impact of telomerase reactivation on disease progression in pediatric ependymoma and provide preliminary evidence for the involved molecular mechanisms.

Impact of surgical timing on the outcome of anterior cruciate ligament reconstruction

PURPOSE

The purpose of the present study is the comparison of acute ACL reconstruction with or without meniscus repair within 48 h after injury and a delayed surgery during the inflammation-free interval. It was hypothesized that acute ACL reconstruction results in inferior patient reported outcomes and higher frequency of range of motion deficits.

METHODS

The effect of acute (within 48 h) and delayed (during the inflammation-free interval) ACL surgery was prospectively studied on 160 consecutive patients with ACL injury between January 2010 and December 2011. Subgroup analyses were performed to evaluate patients with an additional meniscus repair separately from isolated ACL surgeries. During the study period, partial meniscectomies were recorded to evaluate time dependent meniscus reparability. Patient reported outcomes, objective IKDC and manual stability measurements were documented during the 24-month follow-up period. The Pearson Chi-squared test was used to evaluate objective outcome measures. The Mann-Whitney U test was performed to analyse the results of patient reported outcomes. Statistical significance was set at p < 0.05.

RESULTS

For patients who underwent isolated ACL reconstruction, no statistical significant difference was observed at any time point regarding objective and subjective outcome measures. Significantly fewer patients who underwent acute combined ACL reconstruction and meniscus repair had an extension deficit between 3° and 5° at 12 months following surgery (3.7 vs. 22.2 %, p < 0.05). No difference regarding cyclops removal, re-injury of ACL or meniscus was found between the two surgical timing groups. Further, surgical timing did not influence the reparability of the meniscus.

CONCLUSION

An acute ACL reconstruction within 48 h is preferable in highly active patients or competitive athletes.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

[Amputation of the leg in arterial occlusive disease]

The until recently held opinion that above-knee amputations were the method of choice for treating stage IV chronic occlusive arterial disease, is outdated. Determining the appropriate level for amputation in patients with peripheral arterial obstruction is difficult, and requires much experience. Successful fitting of a prosthetic device and subsequent rehabilitation depend not only on the patient's bodily and emotional reserves, but also on the operative technique employed. The more distal the amputation, the better is the prognosis for satisfactory prosthetic function and social reintegration. A total of 280 amputations on 268 patients was performed over a 48-month period. In 181 patients (68%) primary healing occurred without complications. Total mortality was 10%, occurring mainly in the group of above-knee amputees. The majority of local wound complications was found in transmetatarsal resections and below-knee amputations. A total of 42 patients (15%) underwent re-amputation. Only half of the above-knee amputees could be fitted with a prosthesis and rehabilitated, whereas nearly all patients amputated more distally experienced satisfactory outcomes in this respect.

[Percutaneous treatment of benign ureteral stenoses and fistulae]

Forty-six benign ureteric stenoses in 42 patients were cannulated anterogradely and dilated. In 37 cases, balloon dilatation was carried out followed by a temporary insertion of a ureteric stent. Seven long stenoses were treated by continuous stenting, with a double pigtail stent. In two patients surgery had to be performed following percutaneous catheterisation and dilatation. Seven restenoses were due to tumour recurrences and lymph node metastases; apart from this, the success rate of balloon dilatation was 63%. The patients were observed for one to 41 months with an average of 14 months. Uncomplicated traumatic stenoses and fistulae were successfully treated with only one exception. Prognostically unfavourable features were devascularized ureteric segments, advanced scarring and very long stenoses.

TA-stapler resection of congenital splenic cyst. Case report

Splenic cysts are uncommon. Primary (true, epithelial) and secondary (false, non-epithelial) forms may be distinguished, the latter being more usual. Organ-preserving resection of a primary mesothelial splenic cyst, using a TA-stapler, is described and alternative techniques of splenic preservation are discussed.

[The diagnosis of pulmonary sequestration--the value of computed tomography]

The complex of lung sequestration is a rare but well known entity: A segment of lung tissue located almost always in the lung bases is primarily not connected to the bronchial tree and is supplied by a systemic artery. It is very important to demonstrate these vessels to avoid accidental injuries in surgery that may cause severe bleeding. For planning surgery it is important to delineate the extent of the lesion, since it may be larger than can be seen on x-ray film and there may be secondary infectious changes of the surrounding lung tissue. CT has proved very effective in this regard.

Transcranial Doppler sonography: a new approach in the non-invasive diagnosis of intracranial brain artery disease

56 stroke patients were investigated with the new non-invasive method of transcranial Doppler sonography (TCD), operating with a range-gated pulsed 2 MHz Doppler. In 28.6% of the 56 patients TCD provided additional information about the status of the basal cerebral arteries. The results of the TCD investigation were confirmed by angiography in 14 patients. This result indicates that TCD is a valuable non-invasive method of high accuracy for the detection of intracranial brain artery diseases and collateral flow mechanisms.

Biliary endoprostheses in tumors at the hepatic duct bifurcation

In 51 patients with tumors at the hepatic duct bifurcation, endoprostheses were transhepatically inserted into the bile ducts. Patients with Bismuth-3-tumors (i.e. bilateral biliary obstruction) were treated by insertion of 2 or more endoprostheses. Long-term success presumed drainage of all obstructed ducts, because cholangitis has been a common problem secondary to undrained segments. Furthermore the debris and the high viscosity of infected bile increased the risk for obstruction of the endoprostheses, which was observed in 6%. The mean time of survival was 7 months with a maximum of 26 months. In our experience endoprostheses can be used successfully in unresectable Klatskin tumours, which increases the comfort for the patients in their last months of life.

Intraarterial fibrinolysis: long-term results

Intraarterial fibrinolytic therapy was performed in 136 patients suffering from arteriosclerotic thrombosis of the iliac and femoropopliteal arteries. The initial success rate was 78%. Despite anticoagulation therapy, early recurrent thrombosis was observed in 10% of the patients. The 2-year cumulative patency rate after recanalization was 81%. These results are competitive with those of reconstructive vascular surgery. Therefore, intraarterial fibrinolysis has become a viable alternative to surgery in treating segmental peripheral occlusions more than 4 cm in length that are less than 6-9 months in duration.

Biliary drainage endoprostheses: experience with 201 placements

Two hundred one biliary endoprostheses were inserted transhepatically with a two-step procedure in 162 patients. Teflon endoprostheses were inserted in the initial 95 patients and polyethylene in seven others. Because in vitro experiments and clinical experience have revealed a lower incrustation rate with Percuflex and polyurethane, endoprostheses made of these materials were used in the last 60 patients. The mortality rate directly related to the procedure was 3.7%, and postprocedural complications occurred in 9% of the patients. Delayed complications included cholangitis in 20%, obstruction in 6%, and dislocation in 3% of the cases. The mean survival time of all 162 patients was 20 weeks. It is concluded that endoprostheses offer effective palliative treatment of obstructive jaundice caused by malignancy.

Fibrinolysis in chronic arteriosclerotic occlusions: intrathrombotic injections of streptokinase. Work in progress

Forty-seven patients with chronic arteriosclerotic occlusions of iliac and femoropopliteal arteries were treated by intrathrombotic fibrinolysis. The occlusions were 10-65 cm (mean, 22 cm) long and 6 weeks to 2 years (mean, 4.5 months) old. By means of consistent intrathrombotic injections of 2,500 units of streptokinase every 5 minutes, the thrombi were recanalized within 1-7 hours (mean, 2.5 hours). The primary recanalization rate was 75% (35/47), the patency rate after 2 weeks, 68%. In 29 patients (62%), a residual stenosis had to be dilated by balloon angioplasty. Because of the low total dose of streptokinase (mean, 70,000 units), the thrombin time was elevated up to twice the normal value in only one patient. Bleeding that required transfusions was observed in only two patients (4%). Advantages of intrathrombotic fibrinolysis include higher recanalization rate, lower total dose of streptokinase, fewer bleeding complications, and shorter therapy time than previously reported with other treatments.

[Reduction of the rate of cerebral angiography complications by a standardized study method]

The complications from cerebral angiography encountered in 1034 patients between 1977 and 1982 are described. A standardised technique of cerebral transfemoral catheter angiography is outlined, which helps to reduce the number of complications. The role of the disease for which the examination is done, and the effect of the new contrast media on the risk of the examination, are discussed. Patients with a compromised blood-brain barrier and manifest reduction in cerebral blood flow run a greater risk than patients with other abnormalities. Low osmolar contrast media are better tolerated subjectively. Theoretically, their use would be expected to lead to a reduction in complications but, so far, it has not been possible to confirm this.

[Bureau-Barrière-Thomas-Syndrome. A rare hereditary palmoplantar keratoderma with associated symptoms (author's transl)]

Report on a 17-year-old patient with a rare hereditary palmoplantar keratoderma with associated symptoms (Bureau-Barrière-Thomas-Syndrome). All marks of this disease were present except the X-ray findings. The presented case has to be accepted as a minor variation of the syndrome. The delimination of this disease versus pachydermoperiostosis is significant.