Lomeguatrib Increases the Radiosensitivity of MGMT Unmethylated Human Glioblastoma Multiforme Cell Lines

Background: Treatment resistance of glioblastoma multiforme to chemo- and radiotherapy remains a challenge yet to overcome. In particular, the O⁶-methylguanine-DNA-methyltransferase (MGMT) promoter unmethylated patients have only little benefit from chemotherapy treatment using temozolomide since MGMT counteracts its therapeutic efficacy. Therefore, new treatment options in radiotherapy need to be developed to inhibit MGMT and increase radiotherapy response. Methods: Lomeguatrib, a highly specific MGMT inhibitor, was used to inactivate MGMT protein in vitro. Radiosensitivity of established human glioblastoma multiforme cell lines in combination with lomeguatrib was investigated using the clonogenic survival assay. Inhibition of MGMT was analyzed using Western Blot. Cell cycle distribution and apoptosis were investigated to determine the effects of lomeguatrib alone as well as in combination with ionizing radiation. Results: Lomeguatrib significantly decreased MGMT protein and reduced radiation-induced G2/M arrest. A radiosensitizing effect of lomeguatrib was observed when administered at 1 µM and increased radioresistance at 20 µM. Conclusion: Low concentrations of lomeguatrib elicit radiosensitization, while high concentrations mediate a radioprotective effect.

A new human adipocyte model with PTEN haploinsufficiency

Few human cell strains are suitable and readily available as in vitro adipocyte models. We used resected lipoma tissue from a patient with germline phosphatase and tensin homolog (PTEN) haploinsufficiency to establish a preadipocyte cell strain termed LipPD1 and aimed to characterize cellular functions and signalling pathway alterations in comparison to the established adipocyte model Simpson-Golabi-Behmel-Syndrome (SGBS) and to primary stromal-vascular fraction cells. We found that both cellular life span and the capacity for adipocyte differentiation as well as adipocyte-specific functions were preserved in LipPD1 and comparable to SGBS adipocytes. Basal and growth factor-stimulated activation of the PI3 K/AKT signalling pathway was increased in LipPD1 preadipocytes, corresponding to reduced PTEN levels in comparison to SGBS cells. Altogether, LipPD1 cells are a novel primary cell model with a defined genetic lesion suitable for the study of adipocyte biology.

The Role of miRNA for the Treatment of MGMT Unmethylated Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common high-grade intracranial tumor in adults. It is characterized by uncontrolled proliferation, diffuse infiltration due to high invasive and migratory capacities, as well as intense resistance to chemo- and radiotherapy. With a five-year survival of less than 3% and an average survival rate of 12 months after diagnosis, GBM has become a focus of current research to urgently develop new therapeutic approaches in order to prolong survival of GBM patients. The methylation status of the promoter region of the O⁶-methylguanine–DNA methyltransferase (MGMT) is nowadays routinely analyzed since a methylated promoter region is beneficial for an effective response to temozolomide-based chemotherapy. Furthermore, several miRNAs were identified regulating MGMT expression, apart from promoter methylation, by degrading MGMT mRNA before protein translation. These miRNAs could be a promising innovative treatment approach to enhance Temozolomide (TMZ) sensitivity in MGMT unmethylated patients and to increase progression-free survival as well as long-term survival. In this review, the relevant miRNAs are systematically reviewed.

Stereotactic irradiation of the resection cavity after surgical resection of brain metastases - when is the right timing?

Purpose: This study aimed to evaluate whether an early beginning of the adjuvant stereotactic radiotherapy after macroscopic complete resection of 1-3 brain metastases is essential or whether longer intervals between surgery and radiotherapy are feasible.Material and methods: Sixty-six patients with 69 resection cavities treated with HFSRT after macroscopic complete resection of 1-3 brain metastases between 2009 and 2016 in our institution were included in this study. Overall survival, local recurrence and locoregional recurrence were evaluated depending on the time interval from surgery to the start of radiation therapy.Results: Patients that started radiotherapy within 21 days from surgery had a significantly decreased OS compared to patients treated after a longer interval from surgery (p < .01). There was no significant difference between patients treated ≥ 34 and 22-33 days from surgery (p = .210). In the univariate analysis, local control was superior for patients starting treatment 22-33 days from surgery compared to a later start (p = .049). This effect did not prevail in a multivariate model. There was no significant difference between patients treated within 21 days and patients treated more than 33 days after surgery (p = .203). Locoregional control was not influenced by RT timing (p = .508).Conclusion: A short delay in the start of radiotherapy does not seem to negatively impact the outcome in patients with resected brain metastases. We even observed an unexpected reduction in OS in patients treated within 21 days from surgery. Further studies are needed to define the optimal timing of postoperative radiotherapy to the resection cavity.

SUN-109 PTEN Regulates Differentiation and Proliferation of Aging Preadipocytes

Background: The tumor suppressor gene phosphatase and tensin homologe (PTEN) is one of the most frequently altered genes in human cancer. It antagonizes the PI3K/AKT/mTOR pathway, which is activated by various factors like IGF-1 or insulin and promotes cell growth and proliferation. Germline PTEN mutations cause the PTEN hamartoma tumor syndrome, characterized by an overgrowth of different soft tissues. This includes the formation of lipomas. To understand these adipose tissue malformations we aim to assess the function of PTEN in the context of preadipocyte proliferation, differentiation and senescence. Methods: We used preadipocytes obtained from healthy individuals and reduced the PTEN levels either transiently by siRNA mediated PTEN knock-down or stably using the CRISPR/Cas9 system. Results: Reduced PTEN levels (0.59 ± 0.03 fold) led to an increased proliferation of the preadipocytes as measured by nuclei counting (1.5 ± 0.2 fold after 7 days) and staining of the proliferation marker Ki-67 (1,09 ± 0.01 fold). Moreover, the adipocyte differentiation capacity of low passage preadipocytes was increased after PTEN knock-down (1.14 ± 0.04 fold lipid accumulation) compared to control transfected cells. Differentiation capacity could even be restored in high passage presenescent cells that had already lost their ability to differentiate (1.41 ± 0.14 fold lipid accumulation). This corresponded with an increase in the adipocyte differentiation marker PPARy, as analyzed via qPCR (1.8 ± 0.4 fold). We not only observed an activation of AKT signaling (enhanced AKT and ribosomal protein S6 phosphorylation) in PTEN knock-down cells, but noticed a decrease of the senescence marker p21 (0.4 ± 0.09 fold) and an increase in the NAD-synthesis enzyme NAMPT (visfatin) (1.28 ± 0.06 fold) suggesting a role of PTEN in regulating cellular lifespan. To address the question, if PTEN plays a role not only in disease but also in normal preadipocyte function, we measured PTEN protein levels in cells of different passages. During long-term culture PTEN levels increased (3.7 ± 0.7 fold after 25 days), resulting in a decreased AKT phosphorylation (0.4 ± 0.3 fold). Levels of NAMPT decreased during long-term culture (0.04 ± 0.02 fold). Conclusion: Considering the observations in normal preadipocytes during cellular aging and the findings in PTEN knock-down cells, our results provide strong evidence that PTEN is involved in regulation of preadipocyte aging.

Multicenter analysis of stereotactic radiotherapy of the resection cavity in patients with brain metastases

Brain metastases show a recurrence rate of about 50% after surgical resection. Adjuvant radiotherapy can prevent progression; however, whole-brain radiotherapy (WBRT) can be associated with significant side effects. Local hypofractionated stereotactic radiotherapy (HFSRT) is a good alternative to provide local control with minimal toxicity. In this multicenter analysis, we evaluated the treatment outcome of local HFSRT after resection brain metastases in 181 patients. Patient's characteristics, treatment data as well as follow-up data were collected and analyzed with special focus on local control, locoregional control and survival. After a median follow-up of 12.6 months (range 0.3-80.2 months), the crude rate for local control was 80.5%; 1- and 2-year local recurrence-free survival rates were 75% and 70% (median not reached). Resection cavity size was a significant predictor for local recurrence (P = 0.033). The median overall survival was 16.0 months. Both graded prognostic assessment score and recursive partitioning analysis were accurate predictors of survival. HFSRT leads to excellent local control and has a high potential to consolidate results after surgery; acute and late toxicity is low. Distant intracerebral metastases occur frequently during follow-up, and therefore, a close patient monitoring needs to be warranted if whole-brain radiotherapy is omitted.

[Spread of methicillin-resistant Staphylococcus aureus. Are our hygienic precautions sufficient?]

A patient was transferred from Pakistan to a Danish orthopaedic ward. In Denmark he was tested MRSA-positive. Two months after he was discharged, similar MRSA strains were found in another patient. The two patients had been on the same ward for one week. All hygienic precautions had been taken. Staff and other patients on the ward at the relevant time all tested MRSA-negative.

A 6-month prospective study of hospital-acquired bacteremia in Copenhagen county

During a 6-month period, 892 positive blood cultures were detected in the Copenhagen County hospitals. 302 (34%) were regarded as contaminations, and of the remaining cases 419 (71%) were community-acquired and 171 (29%) hospital-acquired, giving incidence rates of 6.8/1,000 admissions and 2.8/1,000 admissions, respectively. Both frequency and rate of hospital-acquired bacteremia were lower compared to most other studies. E. coli was more commonly found in community-acquired infections, while coagulase-negative staphylococci were the organisms most often considered as a contaminant. The main causative organisms in hospital-acquired infections were S. aureus (n = 37) and E. coli (n = 34). The proportion of polymicrobial bacteremias in this study was lower compared to most other studies (8%). E. coli from hospital-acquired infections were resistant to ampicillin in 42% of cases, but other Enterobacteriaceae showed higher percentage of resistance to beta-lactam antibiotics. S. aureus was penicillin-resistant in 92% of cases, but no methicillin-resistant strains were isolated. The frequency of antibiotic resistance was low compared to reports from other countries. A total of 136 hospital-acquired cases were followed prospectively. 61% of the patients were male and 46% were > or = 60 years of age. Most patients had predisposing diseases, 90% had foreign body and/or recent surgery performed, and 74 (54%) had an intraveneous catheter. The portal of entry was known in 132 (97%) of the cases, the most common being the urinary tract (42%), followed by an intravenous catheter (30%). The prevalence of urinary tract catheters gave an increased number of cases with E. coli bacteremia. The mortality was 16%.

[Clodronate in treatment of tumor osteopathy. Evaluation in tumor patients with bone metastases or hypercalcemia]

METHOD

In an observational study involving 398 tumor patients with bone metastases or related hypercalcemia, the effect of treatment with clodronate over a period of 12 months was investigated. Bone pain, analgesic requirements, quality of life and laboratory parameters were recorded at monthly intervals.

RESULTS

Some 71.4% of all patients indicated an improvement in quality of life. Bone pain, experienced by 91.4% of the patients at the start of treatment, regressed (from 2.0 +/- 1.2 to 1.3 +/- 1.0). After the 12-month treatment period, 36% of the patients did without analgesics completely (prior to treatment the corresponding figure was 24%). The most common side effects attributed to clodronate were gastrointestinal disorders (10%).

CONCLUSION

Clodronate would appear to be a useful supportive drug in the management of tumor-related bone disease.

Wound infection after cesarean section

A prospective multicenter study of 1,032 cesarean sections was performed to identify risk factors for postoperative wound infection. The overall rate of wound infection was 6.6% (3.8% in elective cases and 7.5% following nonelective operations), with considerable interhospital variation. Obesity was recognized as a patient-related risk factor, while risk factors inherent to the obstetric situation were duration of ruptured membranes prior to operation, fetal and labor monitoring by intrauterine devices, and omission of the use of plastic draping and redisinfection of the skin before closure. Logistic regression analysis was used to estimate the influence of these factors on the probability of wound infection. Certain risk factors associated with and over-represented in nonelective operations would explain the increased infection rates in these, and the observed interhospital variations did not differ from the expected rates when the distribution of other risk factors was considered.