RAD51 separation of function mutation disables replication fork maintenance but preserves DSB repair

Homologous recombination (HR) protects replication forks (RFs) and repairs DNA double-strand breaks (DSBs). Within HR, BRCA2 regulates RAD51 via two interaction regions: the BRC repeats to form filaments on single-stranded DNA and exon 27 (Ex27) to stabilize the filament. Here, we identified a RAD51 S181P mutant that selectively disrupted the RAD51-Ex27 association while maintaining interaction with BRC repeat and proficiently forming filaments capable of DNA binding and strand invasion. Interestingly, RAD51 S181P was defective for RF protection/restart but proficient for DSB repair. Our data suggest that Ex27-mediated stabilization of RAD51 filaments is required for the protection of RFs, while it seems dispensable for the repair of DSBs.

Distribution and Failure Patterns of Primary Central Nervous System Lymphoma Related to Hippocampus

PURPOSE/OBJECTIVE(S)

Hippocampus (HC) injury by conventional whole brain radiotherapy (C-WBRT) contributes to the neurocognitive decline in primary central nervous system lymphoma (PCNSL). Hippocampal avoidance (HA-WBRT) could minimize neurocognitive impairment by reducing the radiation dose to HC. However, its feasibility in PCNSL has not been examined regarding the incidence of HC involvement and failures. In this retrospective study, we assessed the risk of hippocampal area involvement at diagnosis and after treatments in PCNSL patients.

MATERIALS/METHODS

We identified 278 immunocompetent PCNSL patients diagnosed between 2000 and 2020. After high dose methotrexate-based induction chemotherapy, patients were observed or given consolidation therapy including RT, cytarabine alone, or autologous stem cell transplantation (ASCT). HC was contoured on T1 MRI image and expanded with a 5mm margin, generating hippocampal avoidance region (HAR). The extent of initial and recurrent lesions was evaluated using pre-induction and post-consolidation T1 contrast-enhanced MRI images. HC failure was defined as recurrence or progression at HAR and those who progressed after induction were excluded. The median follow up was 38.7 months (3.1-239.4).

RESULTS

Of 278 patients diagnosed with PCNSL, 39.9% of them had initial lesions at HAR (Figure 1a). After induction therapy, 212 evaluable patients received following treatments: RT (n = 145, 68.4%) consisting of C-WBRT (n = 114), HA-WBRT (n = 23), and focal RT (n = 8), observation (n = 38, 17.9%), cytarabine only (24, 11.3%), and ASCT (n = 5, 2.4%). Intracranial failures occurred in 47.6% (n = 101) of patients, with 33.7% (n = 34) of them in HAR (Figure 1b). The multivariate analysis identified multifocal disease (HR 3.86, 95% CI 1.15-9.73, p = 0.004) as the only factor associated with the risk of HC failure. Those with unifocal lesion outside HAR showed the lowest HC failure rate, 7.0%, while the highest HC failure rate, 25.4% was observed in the subgroup with multifocal disease within HAR at diagnosis (Figure 2a). In the lowest risk group (unifocal lesion outside HAR, n = 66), C-WBRT was not significantly associated with HC failure (HR 0.57, CI 0.09-3.33, P = .572, Figure 2b) or intracranial failure (HR 0.88, CI 0.40-1.91, P = .748).

CONCLUSION

Our data suggest the HA-WBRT could be explored in patients whose lesion is unifocal and located outside HAR. For patients without initial HAR involvement, hippocampal including WBRT did not significantly change HC failure. Further prospective study will be warranted to assess the feasibility of HA-WBRT in the subgroup with low risk of HC failure.

ZNF212 promotes genomic integrity through direct interaction with TRAIP

TRAIP is a key factor involved in the DNA damage response (DDR), homologous recombination (HR) and DNA interstrand crosslink (ICL) repair. However, the exact functions of TRAIP in these processes in mammalian cells are not fully understood. Here we identify the zinc finger protein 212, ZNF212, as a novel binding partner for TRAIP and find that ZNF212 colocalizes with sites of DNA damage. The recruitment of TRAIP or ZNF212 to sites of DNA damage is mutually interdependent. We show that depletion of ZNF212 causes defects in the DDR and HR-mediated repair in a manner epistatic to TRAIP. In addition, an epistatic analysis of Zfp212, the mouse homolog of human ZNF212, in mouse embryonic stem cells (mESCs), shows that it appears to act upstream of both the Neil3 and Fanconi anemia (FA) pathways of ICLs repair. We find that human ZNF212 interacted directly with NEIL3 and promotes its recruitment to ICL lesions. Collectively, our findings identify ZNF212 as a new factor involved in the DDR, HR-mediated repair and ICL repair though direct interaction with TRAIP.

Cluster Analysis of DSC MRI, Dynamic Contrast-Enhanced MRI, and DWI Parameters Associated with Prognosis in Patients with Glioblastoma after Removal of the Contrast-Enhancing Component: A Preliminary Study

BACKGROUND AND PURPOSE

No report has been published on the use of DSC MR imaging, DCE MR imaging, and DWI parameters in combination to create a prognostic prediction model in glioblastoma patients. The aim of this study was to develop a machine learning-based model to find preoperative multiparametric MR imaging parameters associated with prognosis in patients with glioblastoma. Normalized CBV, volume transfer constant, and ADC of the nonenhancing T2 high-signal-intensity lesions were evaluated using K-means clustering.

MATERIALS AND METHODS

A total of 142 patients with glioblastoma who underwent preoperative MR imaging and total resection were included in this retrospective study. From the normalized CBV, volume transfer constant, and ADC maps, the parametric data were sorted using the K-means clustering method. Patients were divided into training and test sets (ratio, 1:1), and the optimal number of clusters was determined using receiver operating characteristic analysis. Kaplan-Meier survival analysis and log-rank tests were performed to identify potential parametric predictors. A multivariate Cox proportional hazard model was conducted to adjust for clinical predictors.

RESULTS

The nonenhancing T2 high-signal-intensity lesions were divided into 6 clusters. The cluster (class 4) with the relatively low normalized CBV and volume transfer constant value and the lowest ADC values was most associated with predicting glioblastoma prognosis. The optimal cutoff of the class 4 volume fraction of nonenhancing T2 high-signal-intensity lesions predicting 1-year progression-free survival was 9.70%, below which the cutoff was associated with longer progression-free survival. Two Kaplan-Meier curves based on the cutoff value showed a statistically significant difference (P = .037). When we adjusted for all clinical predictors, the cluster with the relatively low normalized CBV and volume transfer constant values and the lowest ADC value was an independent prognostic marker (hazard ratio, 3.04; P = .048). The multivariate Cox proportional hazard model showed a concordance index of 0.699 for progression-free survival.

CONCLUSIONS

Our model showed that nonenhancing T2 high-signal-intensity lesions with the relatively low normalized CBV, low volume transfer constant values, and the lowest ADC values could serve as useful prognostic imaging markers for predicting survival outcomes in patients with glioblastoma.

PWWP2B promotes DNA end resection and homologous recombination

Genome instability is one of the leading causes of gastric cancers. However, the mutational landscape of driver genes in gastric cancer is poorly understood. Here, we investigate somatic mutations in 25 Korean gastric adenocarcinoma patients using whole-exome sequencing and show that PWWP2B is one of the most frequently mutated genes. PWWP2B mutation correlates with lower cancer patient survival. We find that PWWP2B has a role in DNA double-strand break repair. As a nuclear protein, PWWP2B moves to sites of DNA damage through its interaction with UHRF1. Depletion of PWWP2B enhances cellular sensitivity to ionizing radiation (IR) and impairs IR-induced foci formation of RAD51. PWWP2B interacts with MRE11 and participates in homologous recombination via promoting DNA end-resection. Taken together, our data show that PWWP2B facilitates the recruitment of DNA repair machinery to sites of DNA damage and promotes HR-mediated DNA double-strand break repair. Impaired PWWP2B function might thus cause genome instability and promote gastric cancer development.

Osimertinib plus platinum-pemetrexed in newly diagnosed epidermal growth factor receptor mutation-positive advanced/metastatic non-small-cell lung cancer: safety run-in results from the FLAURA2 study

Background

The phase III FLAURA2 (NCT04035486) study will evaluate efficacy and safety of first-line osimertinib with platinum–pemetrexed chemotherapy versus osimertinib monotherapy in epidermal growth factor receptor mutation-positive (EGFRm) advanced/metastatic non-small-cell lung cancer (NSCLC). The safety run-in, reported here, assessed the safety and tolerability of osimertinib with chemotherapy prior to the randomized phase III evaluation.

Patients and methods

Patients (≥18 years; Japan: ≥20 years) with EGFRm locally advanced/metastatic NSCLC received oral osimertinib 80 mg once daily (QD), with either intravenous (IV) cisplatin 75 mg/m² or IV carboplatin target area under the curve 5, plus pemetrexed 500 mg/m² every 3 weeks (Q3W) for four cycles. Maintenance was osimertinib 80 mg QD with pemetrexed 500 mg/m² Q3W until progression/discontinuation. The primary objective was to evaluate safety and tolerability of the osimertinib–chemotherapy combination.

Results

Thirty patients (15 per group) received treatment [Asian, 73%; female, 63%; median age (range) 61 (45-84) years]. Adverse events (AEs) were reported by 27 patients (90%): osimertinib–carboplatin–pemetrexed, 100%; osimertinib–cisplatin–pemetrexed, 80%. Most common AEs were constipation (60%) with osimertinib–carboplatin–pemetrexed and nausea (60%) with osimertinib–cisplatin–pemetrexed. In both groups, 20% of patients reported serious AEs. No specific pattern of AEs leading to dose modifications/discontinuations was observed; one patient discontinued all study treatments including osimertinib due to pneumonitis (study-specific discontinuation criterion). Hematologic toxicities were as expected and manageable.

Conclusions

Osimertinib–chemotherapy combination had a manageable safety and tolerability profile in EGFRm advanced/metastatic NSCLC, supporting further assessment in the FLAURA2 randomized phase.

•

FLAURA2 aims to assess efficacy and safety of first-line osimertinib with platinum–pemetrexed in EGFRm advanced NSCLC.

•

In the FLAURA2 safety run-in period, 30 patients received osimertinib and pemetrexed with carboplatin or cisplatin.

•

Most common AEs were constipation and nausea; no AE patterns leading to dose modifications/discontinuations were observed.

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The FLAURA2 safety run-in study showed that the safety profile of this combination was as expected and manageable.

NSMF promotes the replication stress-induced DNA damage response for genome maintenance

Proper activation of DNA repair pathways in response to DNA replication stress is critical for maintaining genomic integrity. Due to the complex nature of the replication fork (RF), problems at the RF require multiple proteins, some of which remain unidentified, for resolution. In this study, we identified the N-methyl-D-aspartate receptor synaptonuclear signaling and neuronal migration factor (NSMF) as a key replication stress response factor that is important for ataxia telangiectasia and Rad3-related protein (ATR) activation. NSMF localizes rapidly to stalled RFs and acts as a scaffold to modulate replication protein A (RPA) complex formation with cell division cycle 5-like (CDC5L) and ATR/ATR-interacting protein (ATRIP). Depletion of NSMF compromised phosphorylation and ubiquitination of RPA2 and the ATR signaling cascade, resulting in genomic instability at RFs under DNA replication stress. Consistently, NSMF knockout mice exhibited increased genomic instability and hypersensitivity to genotoxic stress. NSMF deficiency in human and mouse cells also caused increased chromosomal instability. Collectively, these findings demonstrate that NSMF regulates the ATR pathway and the replication stress response network for genome maintenance and cell survival.

Diagnostic accuracy of the jetting sign and a dilatation ratio of left renal vein in CT urography for detecting anterior nutcracker syndrome

AIM

To investigate the diagnostic value of computed tomography (CT) urography findings of anterior nutcracker syndrome (NCS).

MATERIALS AND METHODS

The study included patients with left renal vein (LRV) compression at the aortomesenteric portion at CT urography who underwent renal venography or cystoscopy. Patients with a renocaval pressure gradient of ≥3 mmHg on renal venography or bloody urine jetting from the left ureteral orifice on cystoscopy were defined as the NCS group; the remaining patients comprised the non-NCS group. CT findings were analysed using the jetting of contrast medium flow from the LRV to the inferior vena cava (jetting sign), aortomesenteric distance, presence of collateral veins, and a dilatation ratio of LRV diameter at the aortomesenteric portion (arterial phase/delayed phases). Clinical findings, including age, gender, and body-mass-index, were also analysed. CT features and clinical findings were compared between the NCS and non-NCS groups. Diagnostic performance of CT parameters was assessed using receiver operating characteristic curve analysis.

RESULTS

A total of 70 patients (21 men, mean age 44.4 ± 17.2 years) with NCS (n=13) and non-NCS (n=57) were included. Younger age (<40 years), presence of the jetting sign, and a lower dilatation ratio of LRV diameter between the arterial and delayed phases (<1.7) were found to be significant independent factors for predicting the NCS group (OR 24.5, 18.9, 19.4, respectively, p<0.05 for all). The combination of the presence of the jetting sign and a dilatation ratio of LRV diameter of <1.7 obtained the highest AUC of 0.88.

CONCLUSION

The jetting sign and the dilatation ratio of LRV diameter between the arterial and delayed phases can both be very useful in the diagnosis of anterior nutcracker syndrome during CT urography.

ATAD5 suppresses centrosome over-duplication by regulating UAF1 and ID1

Centrosomes are the primary microtubule-organizing centers that are important for mitotic spindle assembly. Centrosome amplification is commonly observed in human cancer cells and contributes to genomic instability. However, it is not clear how centrosome duplication is dysregulated in cancer cells. Here, we report that ATAD5, a replisome protein that unloads PCNA from chromatin as a replication factor C-like complex (RLC), plays an important role in regulating centrosome duplication. ATAD5 is present at the centrosome, specifically at the base of the mother and daughter centrioles that undergo duplication. UAF1, which interacts with ATAD5 and regulates PCNA deubiquitination as a complex with ubiquitin-specific protease 1, is also localized at the centrosome. Depletion of ATAD5 or UAF1 increases cells with over-duplicated centrosome whereas ATAD5 overexpression reduces such cells. Consistently, the proportion of cells showing the multipolar mode of chromosome segregation is increased among ATAD5-depleted cells. The localization and function of ATAD5 at the centrosomes do not require other RLC subunits. UAF1 interacts and co-localizes with ID1, a protein that increases centrosome amplification upon overexpression. ATAD5 depletion reduces interactions between UAF1 and ID1 and increases ID1 signal at the centrosome, providing a mechanistic framework for understanding the role of ATAD5 in centrosome duplication.

Molecular correlates of response to capmatinib in advanced non-small-cell lung cancer: clinical and biomarker results from a phase I trial

BACKGROUND

Dysregulation of receptor tyrosine kinase MET by various mechanisms occurs in 3%-4% of non-small-cell lung cancer (NSCLC) and is associated with unfavorable prognosis. While MET is a validated drug target in lung cancer, the best biomarker strategy for the enrichment of a susceptible patient population still remains to be defined. Towards this end we analyze here primary data from a phase I dose expansion study of the MET inhibitor capmatinib in patients with advanced MET-dysregulated NSCLC.

PATIENTS AND METHODS

Eligible patients [≥18 years; Eastern Cooperative Oncology Group (ECOG) performance status ≤2] with MET-dysregulated advanced NSCLC, defined as either (i) MET status by immunohistochemistry (MET IHC) 2+ or 3+ or H-score ≥150, or MET/centromere ratio ≥2.0 or gene copy number (GCN) ≥5, or (ii) epidermal growth factor receptor wild-type (EGFRwt) and centrally assessed MET IHC 3+, received capmatinib at the recommended dose of 400 mg (tablets) or 600 mg (capsules) b.i.d. The primary objective was to determine safety and tolerability; the key secondary objective was to explore antitumor activity. The exploratory end point was the correlation of clinical activity with different biomarker formats.

RESULTS

Of 55 patients with advanced MET-dysregulated NSCLC, 40/55 (73%) had received two or more prior systemic therapies. All patients discontinued treatment, primarily due to disease progression (69.1%). The median treatment duration was 10.4 weeks. The overall response rate per RECIST was 20% (95% confidence interval, 10.4-33.0). In patients with MET GCN ≥6 (n = 15), the overall response rate by both the investigator and central assessments was 47%. The median progression-free survival per investigator for patients with MET GCN ≥6 was 9.3 months (95% confidence interval, 3.8-11.9). Tumor responses were observed in all four patients with METex14. The most common toxicities were nausea (42%), peripheral edema (33%), and vomiting (31%).

CONCLUSIONS

MET GCN ≥6 and/or METex14 are suited to predict clinical activity of capmatinib in patients with NSCLC (NCT01324479).

Dynamic Contrast-Enhanced MR Imaging of Nonenhancing T2 High-Signal-Intensity Lesions in Baseline and Posttreatment Glioblastoma: Temporal Change and Prognostic Value

BACKGROUND AND PURPOSE

The prognostic value of dynamic contrast-enhanced MR imaging on nonenhancing T2 high-signal-intensity lesions in patients with glioblastoma has not been thoroughly elucidated to date. We evaluated the temporal change and prognostic value for progression-free survival of dynamic contrast-enhanced MR imaging-derived pharmacokinetic parameters on nonenhancing T2 high-signal-intensity lesions in patients with glioblastoma before and after standard treatment, including gross total surgical resection.

MATERIALS AND METHODS

This retrospective study included 33 patients who were newly diagnosed with glioblastoma and treated with gross total surgical resection followed by concurrent chemoradiation therapy and adjuvant chemotherapy with temozolomide in a single institution. All patients underwent dynamic contrast-enhanced MR imaging before surgery as a baseline and after completion of maximal surgical resection and concurrent chemoradiation therapy. On the whole nonenhancing T2 high-signal-intensity lesion, dynamic contrast-enhanced MR imaging-derived pharmacokinetic parameters (volume transfer constant [K ^trans], volume of extravascular extracellular space [v _e]_, and blood plasma volume [v_p ]) were calculated. The Cox proportional hazards regression model analysis was performed to determine the histogram features or percentage changes of pharmacokinetic parameters related to progression-free survival.

RESULTS

Baseline median K ^trans, baseline first quartile K ^trans, and posttreatment median K ^trans were significant independent variables, as determined by univariate analysis (P < .05). By multivariate Cox regression analysis including methylation status of O⁶-methylguanine-DNA methyltransferase, baseline median K ^trans was determined to be the significant independent variable and was negatively related to progression-free survival (hazard ratio = 1.48, P = .003).

CONCLUSIONS

Baseline median K ^trans from nonenhancing T2 high-signal-intensity lesions could be a potential prognostic imaging biomarker in patients undergoing gross total surgical resection followed by standard therapy for glioblastoma.

Prognostic Predictions for Patients with Glioblastoma after Standard Treatment: Application of Contrast Leakage Information from DSC-MRI within Nonenhancing FLAIR High-Signal-Intensity Lesions

BACKGROUND AND PURPOSE

Attempts have been made to quantify the microvascular leakiness of glioblastomas and use it as an imaging biomarker to predict the prognosis of the tumor. The purpose of our study was to evaluate whether the extraction fraction value from DSC-MR imaging within nonenhancing FLAIR hyperintense lesions was a better prognostic imaging biomarker than dynamic contrast-enhanced MR imaging parameters for patients with glioblastoma.

MATERIALS AND METHODS

A total of 102 patients with glioblastoma who received a preoperative dynamic contrast-enhanced MR imaging and DSC-MR imaging were included in this retrospective study. Patients were classified into the progression (n = 87) or nonprogression (n = 15) groups at 24 months after surgery. We extracted the means and 95th percentile values for the contrast leakage information parameters from both modalities within the nonenhancing FLAIR high-signal-intensity lesions.

RESULTS

The extraction fraction 95th percentile value was higher in the progression-free survival group of >24 months than at ≤24 months. The median progression-free survival of the group with an extraction fraction 95th percentile value of >13.32 was 17 months, whereas that of the group of ≤13.32 was 12 months. In addition, it was an independent predictor variable for progression-free survival in the patients regardless of their ages and genetic information.

CONCLUSIONS

The extraction fraction 95th percentile value was the only independent parameter for prognostic prediction in patients with glioblastoma among the contrast leakage information, which has no statistically significant correlations with the DCE-MR imaging parameters.

Final overall survival analysis for the phase II RECORD-3 study of first-line everolimus followed by sunitinib versus first-line sunitinib followed by everolimus in metastatic RCC

Background

RECORD-3 compared everolimus and sunitinib as first-line therapy, and the sequence of everolimus followed by sunitinib at progression compared with the opposite (standard) sequence in patients with metastatic renal cell carcinoma (mRCC). This final overall survival (OS) analysis evaluated mature data for secondary end points.

Patients and methods

Patients received either first-line everolimus followed by second-line sunitinib at progression (n = 238) or first-line sunitinib followed by second-line everolimus (n = 233). Secondary end points were combined first- and second-line progression-free survival (PFS), OS, and safety. The impacts of neutrophil lymphocyte ratio (NLR) and baseline levels of soluble biomarkers on OS were explored.

Results

At final analysis, median duration of exposure was 5.6 months for everolimus and 8.3 months for sunitinib. Median combined PFS was 21.7 months [95% confidence interval (CI) 15.1–26.7] with everolimus-sunitinib and 22.2 months (95% CI 16.0–29.8) with sunitinib-everolimus [hazard ratio (HR)_{EVE-SUN/SUN-EVE}, 1.2; 95% CI 0.9–1.6]. Median OS was 22.4 months (95% CI 18.6–33.3) for everolimus-sunitinib and 29.5 months (95% CI 22.8–33.1) for sunitinib-everolimus (HR_{EVE-SUN/SUN-EVE}, 1.1; 95% CI 0.9–1.4). The rates of grade 3 and 4 adverse events suspected to be related to second-line therapy were 47% with everolimus and 57% with sunitinib. Higher NLR and 12 soluble biomarker levels were identified as prognostic markers for poor OS with the association being largely independent of treatment sequences.

Conclusions

Results of this final OS analysis support the sequence of sunitinib followed by everolimus at progression in patients with mRCC. The safety profiles of everolimus and sunitinib were consistent with those previously reported, and there were no unexpected safety signals.

Clinical Trials number

ClinicalTrials.gov identifier, NCT00903175

Vandetanib in pretreated patients with advanced non-small cell lung cancer-harboring RET rearrangement: a phase II clinical trial

Background

Chromosomal rearrangements involving RET, which are found in about 1% of non-small cell lung cancer (NSCLC), define a unique molecular subset. We performed this study to examine the efficacy and safety of vandetanib 300 mg daily in this patient population.

Patients and methods

This study was a multi-center, open-label, phase II clinical trial. Patients were enrolled if they had metastatic or recurrent NSCLC with a RET rearrangement, which was confirmed by fluorescence in situ hybridization, had progressive disease against platinum-based doublet chemotherapy, and had a performance status of 0-2. The primary endpoint was the objective response rate.

Results

A total of 18 patients were enrolled in this study between July 2013 and October 2015. Patients were aged 35-71 years; three had a performance status of 2, and the majority were a heavily pretreated population (≥ two different previous chemotherapy regimens in 72% of the patients). Among the 17 evaluable patients, three had a partial response (objective response rate = 18%) and eight had a stable disease (disease control rate = 65%). Among these patients, the partial response or disease stabilization was durable for more than 6 months in eight patients. Vandetanib also showed a progression-free survival of 4.5 months, and an overall survival of 11.6 months during a median follow-up duration of 14 months. The safety profile was comparable with previous studies of vandetanib. Most vandetanib-related adverse events were mild with prevalent hypertension and rash (in >70% of patients). Grade 3 toxicity included hypertension (n = 3), QT prolongation (2), and elevation of aminotransferases (1), and as a consequence the dose was reduced in four patients. There were no adverse events associated with grade 4 or 5 toxicity.

Conclusion

Vandetanib is moderately active in pretreated patients with advanced NSCLC-harboring RET rearrangements.

Complex chromosomal rearrangements by single catastrophic pathogenesis in NUT midline carcinoma

Background

Nuclear protein in testis (NUT) midline carcinoma (NMC) is a rare aggressive malignancy often occurring in the tissues of midline anatomical structures. Except for the pathognomonic BRD3/4–NUT rearrangement, the comprehensive landscape of genomic alterations in NMCs has been unexplored.

Patients and methods

We investigated three NMC cases, including two newly diagnosed NMC patients in Seoul National University Hospital, and a previously reported cell line (Ty-82). Whole-genome and transcriptome sequencing were carried out for these cases, and findings were validated by multiplex fluorescence in situ hybridization and using individual fluorescence probes.

Results

Here, we present the first integrative analysis of whole-genome sequencing, transcriptome sequencing and cytogenetic characterization of NUT midline carcinomas. By whole-genome sequencing, we identified a remarkably similar pattern of highly complex genomic rearrangements (previously denominated as chromoplexy) involving the BRD3/4–NUT oncogenic rearrangements in two newly diagnosed NMC cases. Transcriptome sequencing revealed that these complex rearrangements were transcribed as very simple BRD3/4–NUT fusion transcripts. In Ty-82 cells, we also identified a complex genomic rearrangement involving the BRD4–NUT rearrangement underlying the simple t(15;19) karyotype. Careful inspections of rearrangement breakpoints indicated that these rearrangements were likely attributable to single catastrophic events. Although the NMC genomes had >3000 somatic point mutations, canonical oncogenes or tumor suppressor genes were rarely affected, indicating that they were largely passenger events. Mutational signature analysis showed predominant molecular clock-like signatures in all three cases (accounting for 54%−75% of all base substitutions), suggesting that NMCs may arise from actively proliferating normal cells.

Conclusion

Taken together, our findings suggest that a single catastrophic event in proliferating normal cells could be sufficient for neoplastic transformation into NMCs.

Analysis and comparison of the cost-effectiveness of statins according to the baseline low-density lipoprotein cholesterol level in Korea

WHAT IS KNOWN AND OBJECTIVE

There are a few Korean studies on the economics of statins based on reduction in low-density lipoprotein cholesterol (LDL-C) data from other countries. This study aimed to analyse and compare the cost-effectiveness of statins according to the baseline LDL-C level in Korea.

METHODS

Between January 2009 and December 2015, the data of patients who were prescribed statins for the first time were extracted from electronic medical records. We performed a cost-effectiveness analysis (CEA) based on the LDL-C reduction rate (CEA-RR) and target achievement rate.

RESULTS AND DISCUSSION

Among high-intensity statins, the CEA-RR value of rosuvastatin (20 mg) was significantly lower than that of atorvastatin (40 mg) at all baseline LDL-C levels, except levels of 160-189 mg/dL. Additionally, at baseline LDL-C levels of 130-159 mg/dL, the CEA-RR value of rosuvastatin (20 mg) was three times lower than that of atorvastatin (40 mg) (9·1 ± 2·5 $/% vs. 31·7 ± 15·0 $/%, P < 0·001). Among moderate-to-low-intensity statins, rosuvastatin (5 mg) showed the lowest CEA-RR value (4·0 ± 0·6 $/%), and the value significantly increased for pitavastatin (2 mg) (8·0 ± 0·6 $/%), atorvastatin (10 mg) (9·5 ± 0·5 $/%), simvastatin (10·8 ± 1·1 $/%) and pravastatin (40 mg) (11·5 ± 0·9 $/%) in order (P < 0·0001). On changing from atorvastatin (10 mg) to atorvastatin (20 mg), the additional yearly cost was 16·0 and additional CEA-RR value was 2·74 $/%. On the other hand, on changing from atorvastatin (10 mg) to rosuvastatin (10 mg), the additional yearly cost was -16·3 and additional CEA-RR value was -1·8 $/%.

WHAT IS NEW AND CONCLUSION

We successfully compared the cost-effectiveness of statins according to the baseline LDL-C level in Korea. It is expected that our findings will help clinical decision-making with regard to statin prescription, and this will help reduce national medical expenditure.

Independent Poor Prognostic Factors for True Progression after Radiation Therapy and Concomitant Temozolomide in Patients with Glioblastoma: Subependymal Enhancement and Low ADC Value

BACKGROUND AND PURPOSE

Subependymal enhancement and DWI have been reported to be useful MR imaging markers for identifying true progression. Our aim was to determine whether the subependymal enhancement pattern and ADC can differentiate true progression from pseudoprogression in patients with glioblastoma multiforme treated with concurrent chemoradiotherapy by using temozolomide.

MATERIALS AND METHODS

Forty-two patients with glioblastoma multiforme with newly developed or enlarged enhancing lesions on the first follow-up MR images obtained within 2 months of concurrent chemoradiotherapy completion were included. Subependymal enhancement was analyzed for the presence, location, and pattern (local or distant relative to enhancing lesions). The mean ADC value and the fifth percentile of the cumulative ADC histogram were determined. A multiple logistic regression analysis was performed to identify independent factors associated with true progression.

RESULTS

Distant subependymal enhancement (ie, extending >1 cm or isolated from the enhancing lesion) was significantly more common in true progression (n = 24) than in pseudoprogression (n = 18) (P = .042). The fifth percentile of the cumulative ADC histogram was significantly lower in true progression than in pseudoprogression (P = .014). Both the distant subependymal enhancement and the fifth percentile of the cumulative ADC histogram were independent factors associated with true progression (P = .041 and P = .033, respectively). Sensitivity and specificity for the diagnosis of true progression were 83% and 67%, respectively, by using both factors.

CONCLUSIONS

Both the distant subependymal enhancement and the fifth percentile of the cumulative ADC histogram were significant independent factors predictive of true progression.

Final results from the large sunitinib global expanded-access trial in metastatic renal cell carcinoma

BACKGROUND

We report final results with extended follow-up from a global, expanded-access trial that pre-regulatory approval provided sunitinib to metastatic renal cell carcinoma (mRCC) patients, ineligible for registration-directed trials.

METHODS

Patients ⩾18 years received oral sunitinib 50 mg per day on a 4-weeks-on-2-weeks-off schedule. Safety was assessed regularly. Tumour measurements were scheduled per local practice.

RESULTS

A total of 4543 patients received sunitinib. Median treatment duration and follow-up were 7.5 and 13.6 months. Objective response rate was 16% (95% confidence interval (CI): 15-17). Median progression-free survival (PFS) and overall survival (OS) were 9.4 months (95% CI: 8.8-10.0) and 18.7 months (95% CI: 17.5-19.5). Median PFS in subgroups of interest: aged ⩾65 years (33%), 10.1 months; Eastern Cooperative Oncology Group performance status ⩾2 (14%), 3.5 months; non-clear cell histology (12%), 6.0 months; and brain metastases (7%), 5.3 months. OS was strongly associated with the International Metastatic Renal-Cell Carcinoma Database Consortium prognostic model (n=4065). The most common grade 3/4 treatment-related adverse events were thrombocytopenia (10%), fatigue (9%), and asthenia, neutropenia, and hand-foot syndrome (each 7%).

CONCLUSION

Final analysis of the sunitinib expanded-access trial provided a good opportunity to evaluate the long-term side effects of a tyrosine kinase inhibitor used worldwide in mRCC. Efficacy and safety findings were consistent with previous results.

RECQL5 and BLM exhibit divergent functions in cells defective for the Fanconi anemia pathway

Fanconi anemia (FA) patients exhibit bone marrow failure, developmental defects and cancer. The FA pathway maintains chromosomal stability in concert with replication fork maintenance and DNA double strand break (DSB) repair pathways including RAD51-mediated homologous recombination (HR). RAD51 is a recombinase that maintains replication forks and repairs DSBs, but also rearranges chromosomes. Two RecQ helicases, RECQL5 and Bloom syndrome mutated (BLM) suppress HR through nonredundant mechanisms. Here we test the impact deletion of RECQL5 and BLM has on mouse embryonic stem (ES) cells deleted for FANCB, a member of the FA core complex. We show that RECQL5, but not BLM, conferred resistance to mitomycin C (MMC, an interstrand crosslinker) and camptothecin (CPT, a type 1 topoisomerase inhibitor) in FANCB-defective cells. RECQL5 suppressed, while BLM caused, breaks and radials in FANCB-deleted cells exposed to CPT or MMC, respectively. RECQL5 protected the nascent replication strand from MRE11-mediated degradation and restarted stressed replication forks in a manner additive to FANCB. By contrast BLM restarted, but did not protect, replication forks in a manner epistatic to FANCB. RECQL5 also lowered RAD51 levels in FANCB-deleted cells at stressed replication sites implicating a rearrangement avoidance mechanism. Thus, RECQL5 and BLM impact FANCB-defective cells differently in response to replication stress with relevance to chemotherapeutic regimes.

Concomitant ALK translocation and EGFR mutation in lung cancer: a comparison of direct sequencing and sensitive assays and the impact on responsiveness to tyrosine kinase inhibitor

BACKGROUND

Epidermal growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) translocation are considered mutually exclusive in nonsmall-cell lung cancer (NSCLC). However, sporadic cases having concomitant EGFR and ALK alterations have been reported. The present study aimed to assess the prevalence of NSCLCs with concomitant EGFR and ALK alterations using mutation detection methods with different sensitivity and to propose an effective diagnostic and therapeutic strategy.

PATIENTS AND METHODS

A total of 1458 cases of lung cancer were screened for EGFR and ALK alterations by direct sequencing and flourescence in situ hybridization (FISH), respectively. For the 91 patients identified as having an ALK translocation, peptide nucleic acid (PNA)-clamping real-time PCR, targeted next-generation sequencing (NGS), and mutant-enriched NGS assays were carried out to detect EGFR mutation.

RESULTS

EGFR mutations and ALK translocations were observed in 42.4% (612/1445) and 6.3% (91/1445) of NSCLCs by direct sequencing and FISH, respectively. Concomitant EGFR and ALK alterations were detected in four cases, which accounted for 4.4% (4/91) of ALK-translocated NSCLCs. Additional analyses for EGFR using PNA real-time PCR and ultra-deep sequencing by NGS, mutant-enriched NGS increased the detection rate of concomitant EGFR and ALK alterations to 8.8% (8/91), 12.1% (11/91), and 15.4% (14/91) of ALK-translocated NSCLCs, respectively. Of the 14 patients, 3 who were treated with gefitinib showed poor response to gefitinib with stable disease in one and progressive disease in two patients. However, eight patients who received ALK inhibitor (crizotinib or ceritinib) showed good response, with response rate of 87.5% (7/8 with partial response) and durable progression-free survival.

CONCLUSIONS

A portion of NSCLC patients have concomitant EGFR and ALK alterations and the frequency of co-alteration detection increases when sensitive detection methods for EGFR mutation are applied. ALK inhibitors appear to be effective for patients with co-alterations.

Deletion of BRCA2 exon 27 causes defects in response to both stalled and collapsed replication forks

BRCA2 is a tumor suppressor that maintains genomic integrity through double strand break (DSB) repair and replication fork protection. The BRC motifs and an exon 27-encoded domain (Ex27) of BRCA2 interact with the recombinase RAD51 to, respectively, facilitate the formation and stability of a RAD51 filament on single strand DNA. The BRC-RAD51 associations enable DSB repair while the Ex27-RAD51 association protects the nascent replication strand from MRE11-mediated degradation. MRE11 is a nuclease that facilitates the generation of 3' overhangs needed for homologous recombination (HR)-mediated DSB repair. Here we report the dynamics of replication fork maintenance in mouse embryonic stem (ES) cells deleted for Ex27 (brca2(lex1/lex2)) after exposure to hydroxyurea (HU) that depletes nucleotides. HU conditions were varied from mild to severe. Mild conditions induce an ATR-response to replication fork stalling while severe conditions induce a DNA-PKCS-response to replication fork collapse and a DSB. These responses were differentiated by replication protein A (RPA) phosphorylation. We found that Ex27 deletion reduced MRE11 localization to stalled, but not collapsed, replication forks and that Ex27-deletion caused a proportionately more severe phenotype with HU dose. Therefore, the BRCA2 exon 27 domain maintains chromosomal integrity at both stalled and collapsed replication forks consistent with involvement in both replication fork maintenance and double strand break repair.

Defining a genotoxic profile with mouse embryonic stem cells

Many genotoxins are found in the environment from synthetic to natural, yet very few have been studied in depth. This means we fail to understand many molecules that damage DNA, we do not understand the type of damage they cause and the repair pathways required to correct their lesions. It is surprising so little is known about the vast majority of genotoxins since they have potential to cause disease from developmental defects to cancer to degenerative ailments. By contrast, some of these molecules have commercial and medical potential and some can be weaponized. Therefore, we need a systematic method to efficiently generate a genotoxic profile for these agents. A genotoxic profile would include the type of damage the genotoxin causes, the pathways used to repair the damage and the resultant mutations if repair fails. Mouse embryonic stem (ES) cells are well suited for identifying pathways and mutations. Mouse ES cells are genetically tractable and many DNA repair mutant cells are available. ES cells have a high mitotic index and form colonies so experiments can be completed quickly and easily. Furthermore, ES cells have robust DNA repair pathways to minimize genetic mutations at a particularly vulnerable time in life, early development when a mutation in a single cell could ultimately contribute to a large fraction of the individual. After an initial screen, other types of cells and mouse models can be used to complement the analysis. This review discusses the merging field of genotoxic screens in mouse ES cells that can be used to discover and study potential genotoxic activity for chemicals commonly found in our environment.

Multicenter phase II study of sunitinib in patients with non-clear cell renal cell carcinoma

BACKGROUND

Retrospective and molecular biologic data suggest that sunitinib may be effective in patients with non-clear cell renal cell carcinoma (nccRCC).

PATIENTS AND METHODS

Eligibility criteria included advanced nccRCC except for collecting duct carcinoma and sarcomatoid carcinoma without identifiable renal cell carcinoma subtypes. Patients were treated with 50 mg/day oral sunitinib for 4 weeks, followed by 2 weeks of rest. The primary end point was overall response rate (RR).

RESULTS

Thirty-one eligible patients were enrolled. Twenty-four patients (77%) had prior nephrectomy. By Memorial Sloan-Kettering Cancer Center criteria, 8 patients (26%) had poor risk and 14 (45%) had intermediate risk. Twenty-two patients had papillary renal cell carcinoma (RCC), and three had chromophobe RCC. Eleven patients had partial response with a RR of 36% (95% confidence interval (CI) 19% to 52%) and an additional 17 patients (55%) had stable disease. Median duration of response was 12.7 months (95% CI 6.3-19.1 months), and median progression-free survival was 6.4 months (95% CI 4.2-8.6 months). At a median follow-up duration of 18.7 months (95% CI 13.7-23.7 months), 13 patients (42%) had died, resulting in an estimated median survival of 25.6 months (95% CI 8.4-42.9 months). Toxicity profiles were commensurate with prior reports.

CONCLUSIONS

Sunitinib has promising activity in patients with nccRCC (NCT01219751).

The phenotype of FancB-mutant mouse embryonic stem cells

Fanconi anemia (FA) is a rare autosomal recessive disease characterized by bone marrow failure, developmental defects and cancer. There are multiple FA genes that enable the repair of interstrand crosslinks (ICLs) in coordination with a variety of other DNA repair pathways in a way that is poorly understood. Here we present the phenotype of mouse embryonic stem (ES) cells mutated for FancB. We found FancB-mutant cells exhibited reduced cellular proliferation, hypersensitivity to the crosslinking agent mitomycin C (MMC), increased spontaneous and MMC-induced chromosomal abnormalities, reduced spontaneous sister chromatid exchanges (SCEs), reduced gene targeting, reduced MMC-induced Rad51 foci and absent MMC-induced FancD2 foci. Since FancB is on the X chromosome and since ES cells are typically XY, FancB is an excellent target for an epistatic analysis to elucidate FA's role in ICL repair.

High-throughput knock-in coupling gene targeting with the HPRT minigene and Cre-mediated recombination

Single nucleotide polymorphisms (SNPs) may influence protein function possibly contributing to phenotype; yet, for most SNPs their potential influence is unknown. Here, we present a technique in mouse embryonic stem cells that enables high-throughput knock-in (the placement of coding sequences adjacent to a specific endogenous promoter). Our methodology utilizes gene targeting with a combination of two selection cassettes (SAbetageo and the HPRT minigene) along with site-specific recombinases (Cre/loxP and FLP/FRT) to efficiently introduce multiple DNA sequences, including enhanced green fluorescent protein (eGFP), adjacent to the DNA topoisomerase 3beta (Top3beta) promoter. This technology enables rapid and efficient introduction of DNA sequences to a specific location and advances high-throughput analysis of many SNPs with control for expression and genetic background.

HPRT minigene generates chimeric transcripts as a by-product of gene targeting

The HPRT minigene is a selection cassette used for gene targeting in mouse embryonic stem (ES) cells and, it is unique since selection may be applied for its presence and absence. This minigene has two exon clusters separated by a small intron and splicing sequences. We find these exon clusters splice into exons from the target gene forming two different classes of chimeric transcripts. The first class is expressed by the endogenous promoter and includes upstream target gene exons spliced into minigene exons 3-8. The second class is expressed by the minigene's PGK promoter and includes minigene exons 1-2 spliced into downstream target gene exons. These chimeric transcripts may produce chimeric proteins that could influence phenotype. Therefore, we have designed two floxed HPRT minigenes that permit removal of either the 5' half of the minigene or the entire minigene via Cre-mediated recombination.

Embryonic stem cells deficient for Brca2 or Blm exhibit divergent genotoxic profiles that support opposing activities during homologous recombination

The breast cancer susceptibility protein, Brca2 and the RecQ helicase, Blm (Bloom syndrome mutated) are tumor suppressors that maintain genome integrity, at least in part, through homologous recombination (HR). Brca2 facilitates HR by interacting with Rad51 in multiple regions, the BRC motifs encoded by exon 11 and a single domain encoded by exon 27; however, the exact importance of these regions is not fully understood. Blm also interacts with Rad51 and appears to suppress HR in most circumstances; however, its yeast homologue Sgs1 facilitates HR in response to some genotoxins. To better understand the biological importance of these two proteins, we performed a genotoxic screen on mouse embryonic stem (ES) cells impaired for either Brca2 or Blm to establish their genotoxic profiles (a cellular dose-response to a wide range of agents). This is the first side-by-side comparison of these two proteins in an identical genetic background. We compared cells deleted for Brca2 exon 27 to cells reduced for Blm expression and find that the Brca2- and Blm-impaired cells exhibit genotoxic profiles that reflect opposing activities during HR. Cells deleted for Brca2 exon 27 are hypersensitive to gamma-radiation, streptonigrin, mitomycin C and camptothecin and mildly resistant to ICRF-193 which is similar to HR defective cells null for Rad54. By contrast, Blm-impaired cells are hypersensitive to ICRF-193, mildly resistant to camptothecin and mitomycin C and more strongly resistant to hydroxyurea. These divergent profiles support the notion that Brca2 and Blm perform opposing functions during HR in mouse ES cells.

Determination of genes related to gastrointestinal tract origin cancer cells using a cDNA microarray

PURPOSE

We evaluated the genome-wide gene expression profiles of various cancer cell lines to identify the gastrointestinal tract cancer cell-related genes.

EXPERIMENTAL DESIGN

Gene expression profilings of 27 cancer cell lines and 9 tissues using 7.5K human cDNA microarrays in indirect design with Yonsei reference RNA composed of 11 cancer cell line RNAs were done. The significant genes were selected using significant analysis of microarray in various sets of data. The selected genes were validated using real-time PCR analysis.

RESULTS

After intensity-dependent, within-print-tip normalization by loess method, we observed that expression patterns of cell lines and tissues were substantially different, divided in two discrete clusters. Next, we selected 115 genes that discriminate gastrointestinal cancer cell lines from others using significant analysis of microarray. Among the expression profiles of five gastric cancer cell lines, 66 genes were identified as differentially expressed genes related to metastatic phenotype. YCC-16, which was established from the peripheral blood of one advanced gastric cancer patient, produced a unique gene expression pattern resembling the profiles of lymphoid cell lines. Quantitative real-time reverse transcription-PCR results of selected genes, including PXN, KRT8, and ITGB5, were correlated to microarray data and successfully discriminate the gastrointestinal tract cancer cell lines from hematologic malignant cell lines.

CONCLUSIONS

A gene expression database could serve as a useful source for the further investigation of cancer biology using the cell lines.

Determination of Genes Related to Gastrointestinal Tract Origin Cancer Cells Using a cDNA Microarray

Purpose: We evaluated the genome-wide gene expression profiles of various cancer cell lines to identify the gastrointestinal tract cancer cell–related genes.

Experimental Design: Gene expression profilings of 27 cancer cell lines and 9 tissues using 7.5K human cDNA microarrays in indirect design with Yonsei reference RNA composed of 11 cancer cell line RNAs were done. The significant genes were selected using significant analysis of microarray in various sets of data. The selected genes were validated using real-time PCR analysis.

Results: After intensity-dependent, within-print-tip normalization by loess method, we observed that expression patterns of cell lines and tissues were substantially different, divided in two discrete clusters. Next, we selected 115 genes that discriminate gastrointestinal cancer cell lines from others using significant analysis of microarray. Among the expression profiles of five gastric cancer cell lines, 66 genes were identified as differentially expressed genes related to metastatic phenotype. YCC-16, which was established from the peripheral blood of one advanced gastric cancer patient, produced a unique gene expression pattern resembling the profiles of lymphoid cell lines. Quantitative real-time reverse transcription-PCR results of selected genes, including PXN, KRT8, and ITGB5, were correlated to microarray data and successfully discriminate the gastrointestinal tract cancer cell lines from hematologic malignant cell lines.

Conclusions: A gene expression database could serve as a useful source for the further investigation of cancer biology using the cell lines.

A comparative study of the surgical treatment of axillary osmidrosis by instrument, manual, and combined subcutaneous shaving procedures

Between 1986 and 1996, 128 patients underwent surgery for axillary osmidrosis via en bloc removal of subcutaneous cellular tissue. The patients were followed for 6 months to 7 years (average follow-up, 25 months). The authors propose three categories in which they classified shaving procedures: instrumental shavings (N = 84), manual shavings (N = 96), and combined shaving procedures (N = 76). A modified Inaba's shaver was used in instrument shavings. Combined shaving is mixture of instrument and conventional manual shaving. All patients were asked to complete a questionnaire postoperatively. This follow-up demonstrated that 92.9% of patients who underwent instrument shaving, 95.8% of patients who underwent manual shaving, and 97.4% of patients who underwent combined shaving experienced no odor or occasional, very mild axillary odor postoperatively. Postoperative scar formation was either invisible or excellent in 92.9% of instrument shavings, and 92.1% of patients who underwent the combined procedure reported either a hairless axilla or a marked decrease of axillary hair. The total satisfaction rate in the combined procedure was 94.7%, which is a better result than the instrument (92.9%) and the manual (91.7%) shaving procedures. The wound complication rate per patient with the combined procedure was 13.2%. There was no scar contracture or limitation in arm abduction. The combined subcutaneous shaving procedure using the modified Inaba's shaver has the advantages of rapid and accurate shaving, low incidence of hematoma formation, enhanced wound healing, and easy postoperative care. Therefore, en bloc resection of subcutaneous cellular tissue by combined shaving is a viable option for treatment of axillary osmidrosis.

Endoscopic-assisted correction of the deviated nose

The approach to nasal bone classic corrective rhinoplasty is an almost-blind technique, where the results depends on feeling by the surgeon's hand. To overcome these drawbacks, endoscopic-assisted corrective rhinoplasty and septoplasty were performed for 16 cases of deviated noses between January 1995 and May 1997. The average follow-up period was 18 months. All patients were evaluated by symmetrical nasal pyramid, recurrence of the bony deflection, and septal deviation. The postoperative courses were satisfactory in most cases, with few complications. Compared with 28 cases of classic rhinoplasty, the patient satisfaction rate was high (87.5% in endoscopic-assisted rhinoplasty, 71.4% in classic rhinoplasty), and the complication and revision rate was low (0% in endoscopic-assisted rhinoplasty, 14.3 and 7.1% in classic rhinoplasty). But extra time (about 40 min) and greater expense were required for endoscopic-assisted rhinoplasty. It appeared to us that endoscopic control during corrective rhinoplasty and septoplasty is a big step toward obtaining better results in bony and cartilage resection with extreme precision under monitor control and magnification. This technique is not an open approach but permits one to see more of the nasal skeleton and bony septum, the cause of the deformity, and the immediate effect of the corrective measures used. The use of an endoscope in corrective rhinoplasty for deviated noses provides an expanded field of vision, direct manipulation of lesions, and better aesthetic and functional results.

Potential role of the inactivated X chromosome in ovarian epithelial tumor development

BACKGROUND

Ovarian epithelial tumors can be divided into subcategories often regarded as different stages of neoplastic transformation. Cystadenomas belong to the least aggressive subgroup and are noninvasive and nonmetastatic. Ovarian tumors of low malignant potential (LMP) are intermediate between cystadenomas and carcinomas and show markedly reduced invasive and metastatic abilities. Invasion and metastasis are the hallmarks of carcinomas, which constitute the most aggressive subgroup and can be further subdivided into different grades.

PURPOSE

We performed comparative allelotype analyses of ovarian cystadenomas, LMP tumors, and carcinomas, reasoning that such analyses could provide clues about the molecular determinants of their phenotypic differences. Because we realized that allelic losses involving the X chromosome might be associated with LMP tumor development, we determined whether such losses were interstitial and whether they involved the active or the inactive X chromosome.

METHODS

Frequencies of loss of heterozygosity (LOH) at specific loci in every chromosomal arm were determined in 16 ovarian cystadenomas, 23 ovarian LMP tumors, 15 low-grade ovarian carcinomas, and 35 high-grade ovarian carcinomas by use of either the polymerase chain reaction (PCR) or Southern blot analyses. We took advantage of the fact that DNA methylation is an important mechanism of X-chromosome inactivation to determine whether losses involving the X chromosome were in the active or the inactive copy. We analyzed the methylation status of retained alleles on the X chromosome by determining whether they could be amplified by PCR after digestion with the methylation-sensitive restriction endonuclease Hpa II.

RESULTS

High-grade carcinomas contained frequent(>50%) LOH in four autosomal chromosome arms, i.e., 6q, 13q, 17p, and 17q. Except for 13q, these same chromosomal arms showed frequent LOH in low-grade carcinomas. LOH in autosomal chromosomes was comparatively rare in LMP tumors and was absent in cystadenomas. In contrast, half (eight of 16) of LMP tumors informative for a locus in the proximal portion of chromosome Xq showed LOH at that locus. These losses were the result of interstitial deletions in six of the eight cases and involved the inactive copy of the X chromosome exclusively. Similar losses in the X chromosome were not seen in either cystadenomas or low-grade carcinomas.

CONCLUSIONS AND IMPLICATIONS

LOH at multiple loci is associated with the development of ovarian carcinomas but not with the development of cystadenomas and LMP tumors. However, the integrity of a locus in chromosome Xq that possibly escapes X-chromosome inactivation is important for the control of LMP tumor development. The fact that this locus does not appear to be involved in the genesis of low-grade carcinomas suggests that LMP tumors are not precursors of such carcinomas.

Genetic disparity between morphologically benign cysts contiguous to ovarian carcinomas and solitary cystadenomas

BACKGROUND

Ovarian carcinomas occasionally contain large, histologically benign cysts contiguous to the clearly malignant areas (cystadenocarcinomas). The question of whether such cysts are remnants of pre-existing benign tumors (cystadenomas) or constitute integral components of the carcinomas is important in clarifying the role of cystadenomas in ovarian carcinogenesis. It is also important for our general understanding of tumor heterogeneity, a phenomenon thought to result from the gradual accumulation of genetic abnormalities in initially homogeneous tumors. This question is also pertinent to the clinical management of ovarian cystadenomas, which are frequent in women of childbearing age and are usually treated surgically based on the possibility that they may give rise to carcinomas.

PURPOSE

Reasoning that molecular markers of ovarian malignancy would be confined to the histologically malignant portions of cystadenocarcinomas if the morphologically benign portions are in fact pre-existing typical cystadenomas, we sought to verify that mutations in the p53 tumor suppressor gene are markers of malignancy in ovarian tumors and to determine the distribution of such mutations in cystadenocarcinomas.

METHODS

We used immunohistochemical and DNA-sequencing techniques to analyze 46 ovarian carcinomas, 21 ovarian tumors of low malignant potential, and 16 solitary cystadenomas for the presence of p53 mutations. We then used similar techniques to examine the distribution of such mutations in different portions of cystadenocarcinomas. The observed differences in mutation frequencies were analyzed by the two-tailed Fisher's exact test.

RESULTS

Mutations in the p53 gene were present in 24 (52%) of the 46 carcinomas, but they were absent in the 21 tumors of low malignant potential (P < .0001) and the 16 solitary cystadenomas (P = .0002). Six of six cystadenocarcinomas with p53 mutations showed the presence of the same mutations in the adjacent, histologically benign cysts. The mutations were seen not only in cells immediately adjacent to the carcinomas, but also throughout the morphologically benign cysts. Twenty (83%) of the 24 cases showing mutation of one p53 allele also showed loss of genetic heterozygosity, suggesting that the other p53 allele was deleted. Such allelic loss, if present in morphologically malignant portions of cystadenocarcinomas, was also observed in the contiguous cysts.

CONCLUSIONS

Ovarian carcinomas can be distinguished from ovarian cystadenomas and tumors of low malignant potential by p53 mutations. The fact that the mutations were present in histologically benign cysts contiguous to ovarian carcinomas suggests that such cysts are not typical cystadenomas and may carry a genetic predisposition to carcinogenesis that is not present in ordinary cystadenomas.

Alternative splicing of the mRNA encoding baboon glycoprotein receptor GPIIb

The cloning and characterization of cDNAs encoding the cell-surface-specific integrin receptors of baboon platelets has been undertaken to provide species-specific probes. These will be used to investigate the expression and distribution of these receptors among primate species. Clones GPIIb-16 and GPIIb-3, encoding portions of the baboon glycoprotein GPIIb, were isolated from a cDNA library derived from baboon platelet mRNA. GPIIb-3 includes an insert of 43 bp, when compared to GPIIb-16 or human GPIIb. This insert is the result of alternative processing of mRNA. The probable origin of the inserted bases is the 3' end of the intron preceeding exon 28 of the gene. A different product of alternative splicing has been reported in this same region of the human GPIIb sequence, suggesting that this location is susceptible to wobble in the intron-exon junctions. The projected shift in the reading frame of the baboon GPIIb-3 cDNA would give a radically altered C terminus of the deduced amino-acid sequence, and the possibility of a novel functional peptide on the platelet surface.

Loss of heterozygosity on chromosome 13 is common only in the biologically more aggressive subtypes of ovarian epithelial tumors and is associated with normal retinoblastoma gene expression

We examined the frequencies of loss of heterozygosity on chromosome 13 in 77 primary ovarian epithelial tumors subdivided into cystadenomas, tumors of low malignant potential, low grade carcinomas, and high grade carcinomas. Such losses were found in approximately 50% of high grade carcinomas but were not detected in any of the other tumor subtypes (P < 0.0001), suggesting a strong association between these abnormalities and the high grade carcinoma phenotype. The tumors were also examined for abnormalities in expression of the retinoblastoma susceptibility gene (RB). This was assessed by immunohistochemical staining of archival tumor sections with a polyclonal antibody directed against both the phosphorylated and the underphosphorylated forms of the RB protein. Most of the tumors, including those with allelic deletions on chromosome 13, showed normal RB nuclear protein staining patterns. We conclude that loss of RB expression is not a frequent event in primary ovarian carcinomas and that this gene is probably not the target of the frequent allelic deletions on chromosome 13 found in high grade ovarian carcinomas.

Human and baboon integrin beta 5 subunit-encoding mRNAs have alternative polyadenylation sites

A cDNA probe, encoding part of the human integrin polypeptide, GPIIIa (beta 3), was used to screen a cDNA library derived from baboon smooth muscle polyadenylated mRNA. One cross-hybridizing clone, lacking the baboon equivalent of 478 bp of the human sequence, was found to be 98% similar to a human cDNA encoding the beta 5-chain of the receptor for vitronectin, a cell adhesion molecule. The baboon mRNA terminates at 3' position 212 nucleotides upstream from the polyadenylation site of the aligned human mRNA.

Characterization of a cDNA encoding the beta-chain of baboon receptor glycoprotein GPIb

A cDNA probe, encoding part of the baboon integrin polypeptide, GPIIb, was used to screen a cDNA library derived from baboon platelet polyadenylated mRNA. One cross-hybridizing clone was found to be 94% similar to a human cDNA encoding the beta-chain of the receptor for von Willebrand factor, a major component of the platelet-subendothelium attachment mechanism.

Delayed acute measles inclusion body encephalitis in a 9-year-old girl: ultrastructural, immunohistochemical, and in situ hybridization studies

A 9-yr-old girl developed delayed acute measles inclusion body encephalitis, which was different from subacute sclerosing panencephalitis (SSPE) in clinical course. Measles virus was demonstrated by electron microscopy, immunohistochemistry, and in situ hybridization. Contrary to the most previous reports, matrix (M) protein was present in the brain, cerebrospinal fluid, and serum and was demonstrated by Western blot analysis and in situ hybridization. The hybridization was performed by a nonradioactive digoxigenin method.