Serious gastric perforation after second stereotactic body radiotherapy for peripheral lung cancer that recurred after initial stereotactic body radiotherapy: a case report

Background

In recent reports, re-irradiation with stereotactic body radiotherapy for lung tumors in patients previously treated with thoracic radiation therapy resulted in several serious toxicities. Serious non-lung toxicities were observed mostly in patients with central tumors, but we experienced a case of fatal gastric perforation after a second stereotactic body radiotherapy in a patient with a peripheral lung tumor.

Case presentation

An 83-year-old Asian man was diagnosed with T2N0M0 lung cancer in the form of squamous cell carcinoma in the lower lobe of his left lung. He was treated with stereotactic body radiotherapy of 40 Gy in 4 fractions and the tumor decreased in size in partial response. The local tumor recurred 8 months after the first stereotactic body radiotherapy, and he was re-irradiated with a second stereotactic body radiotherapy of 50 Gy in 4 fractions. A Sengstaken–Blakemore tube was inserted below his diaphragm by laparoscopic surgery before the second stereotactic body radiotherapy in order to reduce the stomach dose by keeping his stomach apart from the tumor. Two months after the second stereotactic body radiotherapy, he developed fatal gastric perforation and gastropleural fistula penetrating his diaphragm.

Conclusions

To the best of our knowledge, this is the first report about a gastric perforation after stereotactic body radiotherapy for lung tumors and it warns of serious complication of stereotactic body radiotherapy in not only centrally located but also peripherally located tumors like in this case.

     

Sensitive detection of EGFR mutations using a competitive probe to suppress background in the SMart Amplification Process.

In a previous study, a single nucleotide polymorphism (SNP) diagnostic system named the SMart Amplification Process version 2 (SMAP 2) was reported, which enabled rapid gene diagnostics from crude samples such as whole blood. The asymmetric primer design and use of Taq MutS were reported as innovative background suppression technologies employed by SMAP 2, but Taq MutS is known to display differential affinities for various mismatch combinations, and hence may not be entirely effective for all possible applications. To address this issue we developed another approach using a competitive probe (CP) to enhance background suppression technology instead of Taq MutS. CP is a 3'-end aminated oligonucleotide that competes with 3'-end of a discrimination primer or the self-priming elongation site on intermediate product 2 (IM2) for non-target sequences, such as the alternative allele. The preferred hybridization kinetics for the full-match CP on the non-target sequence results in effective background suppression in SMAP 2 assays. By using a CP, we demonstrated the sensitive detection of EGFR gene mutations in purified genomic DNA from mixed cell populations. The CP approach is another tool enhancing the effectiveness and versatility of SMAP 2 assays, expanding its potential applications, and reinforcing its position as a highly effective technology for molecular diagnostics.     

The lipid raft-anchored adaptor protein Cbp controls the oncogenic potential of c-Src

The tyrosine kinase c-Src is upregulated in various human cancers irrespective of its negative regulator Csk, but the regulatory mechanisms remain unclear. Here, we show that a lipid raft-anchored Csk adaptor, Cbp/PAG, is directly involved in controlling the oncogenicity of c-Src. Using Csk-deficient cells that can be transformed by c-Src overexpression, we found that Cbp expression is markedly downregulated by c-Src activation and re-expression of Cbp efficiently suppresses c-Src transformation as well as tumorigenesis. Cbp-deficient cells are more susceptible to v-Src transformation than their parental cells. Upon phosphorylation, Cbp specifically binds to activated c-Src and sequesters it in lipid rafts, resulting in an efficient suppression of c-Src function independent of Csk. In some human cancer cells and tumors, Cbp is downregulated and the introduction of Cbp significantly suppresses tumorigenesis. These findings indicate a potential role for Cbp as a suppressor of c-Src-mediated tumor progression.     

Prediction of disordered regions in proteins based on the meta approach

MOTIVATION: Intrinsically disordered regions in proteins have no unique stable structures without their partner molecules, thus these regions sometimes prevent high-quality structure determination. Furthermore, proteins with disordered regions are often involved in important biological processes, and the disordered regions are considered to play important roles in molecular interactions. Therefore, identifying disordered regions is important to obtain high-resolution structural information and to understand the functional aspects of these proteins. RESULTS: We developed a new prediction method for disordered regions in proteins based on the meta approach and implemented a web-server for this prediction method named 'metaPrDOS'. The method predicts the disorder tendency of each residue using support vector machines from the prediction results of the seven independent predictors. Evaluation of the meta approach was performed using the CASP7 prediction targets to avoid an overestimation due to the inclusion of proteins used in the training set of some component predictors. As a result, the meta approach achieved higher prediction accuracy than all methods participating in CASP7.     

Regulation of VEGF-mediated angiogenesis by the Akt/PKB substrate Girdin

The serine/threonine protein kinase Akt is involved in a variety of cellular processes including cell proliferation, survival, metabolism and gene expression. It is essential in vascular endothelial growth factor (VEGF)-mediated angiogenesis; however, it is not known how Akt regulates the migration of endothelial cells, a crucial process for vessel sprouting, branching and the formation of networks during angiogenesis. Here we report that Akt-mediated phosphorylation of Girdin, an actin-binding protein, promotes VEGF-dependent migration of endothelial cells and tube formation by these cells. We found that exogenously delivered adenovirus harbouring Girdin short interfering RNA in Matrigel embedded in mice, markedly inhibited VEGF-mediated angiogenesis. Targeted disruption of the Girdin gene in mice impaired vessel remodelling in the retina and angiogenesis from aortic rings, whereas Girdin was dispensable for embryonic vasculogenesis. These findings demonstrate that the Akt/Girdin signalling pathway is essential in VEGF-mediated postneonatal angiogenesis.     

Protein structure databases with new web services for structural biology and biomedical research

The Protein Data Bank Japan (PDBj) curates, edits and distributes protein structural data as a member of the worldwide Protein Data Bank (wwPDB) and currently processes approximately 25-30% of all deposited data in the world. Structural information is enhanced by the addition of biological and biochemical functional data as well as experimental details extracted from the literature and other databases. Several applications have been developed at PDBj for structural biology and biomedical studies: (i) a Java-based molecular graphics viewer, jV; (ii) display of electron density maps for the evaluation of structure quality; (iii) an extensive database of molecular surfaces for functional sites, eF-site, as well as a search service for similar molecular surfaces, eF-seek; (iv) identification of sequence and structural neighbors; (v) a graphical user interface to all known protein folds with links to the above applications, Protein Globe. Recent examples are shown that highlight the utility of these tools in recognizing remote homologies between pairs of protein structures and in assigning putative biochemical functions to newly determined targets from structural genomics projects.     

Sonoporation by Single-Shot Pulsed Ultrasound with Microbubbles Adjacent to Cells

In this article, membrane perforation of endothelial cells with attached microbubbles caused by exposure to single-shot short pulsed ultrasound is described, and the mechanisms of membrane damage and repair are discussed. Real-time optical observations of cell-bubble interaction during sonoporation and successive scanning electron microscope observations of the membrane damage with knowledge of bubble locations revealed production of micron-sized membrane perforations at the bubble locations. High-speed observations of the microbubbles visualized production of liquid microjets during nonuniform contraction of bubbles, indicating that the jets are responsible for cell membrane damage. The resealing process of sonoporated cells visualized using fluorescence microscopy suggested that Ca²⁺-independent and Ca²⁺-triggered resealing mechanisms were involved in the rapid resealing process. In an experimental condition in which almost all cells have one adjacent bubble, 25.4% of the cells were damaged by exposure to single-shot pulsed ultrasound, and 15.9% (∼60% of the damaged cells) were resealed within 5 s. These results demonstrate that single-shot pulsed ultrasound is sufficient to achieve sonoporation when microbubbles are attached to cells.     

Distribution and roles of X-family DNA polymerases in eukaryotes

Four types of DNA polymerase (Pol beta, Pol lambda, Pol mu and TdT) have been identified in eukaryotes as members of the polymerase X-family. Only vertebrates have all four types of enzyme. Plants and fungi have one or two X-family polymerases, while protostomes, such as fruit flies and nematodes, do not appear to have any. It is possible that the well-known metabolic pathways in which these enzymes are involved are restricted to the vertebrate world. The distribution of the DNA polymerases involved in DNA repair across the various biological kingdoms differs from that of the DNA polymerases involved in chromosomal DNA replication. In this review, we focus on the interesting pattern of distribution of the X-family enzymes across biological kingdoms and speculate on their roles.     

Structural basis for the sequence-specific RNA-recognition mechanism of human CUG-BP1 RRM3

The CUG-binding protein 1 (CUG-BP1) is a member of the CUG-BP1 and ETR-like factors (CELF) family or the Bruno-like family and is involved in the control of splicing, translation and mRNA degradation. Several target RNA sequences of CUG-BP1 have been predicted, such as the CUG triplet repeat, the GU-rich sequences and the AU-rich element of nuclear pre-mRNAs and/or cytoplasmic mRNA. CUG-BP1 has three RNA-recognition motifs (RRMs), among which the third RRM (RRM3) can bind to the target RNAs on its own. In this study, we solved the solution structure of the CUG-BP1 RRM3 by hetero-nuclear NMR spectroscopy. The CUG-BP1 RRM3 exhibited a noncanonical RRM fold, with the four-stranded β-sheet surface tightly associated with the N-terminal extension. Furthermore, we determined the solution structure of the CUG-BP1 RRM3 in the complex with (UG)₃ RNA, and discovered that the UGU trinucleotide is specifically recognized through extensive stacking interactions and hydrogen bonds within the pocket formed by the β-sheet surface and the N-terminal extension. This study revealed the unique mechanism that enables the CUG-BP1 RRM3 to discriminate the short RNA segment from other sequences, thus providing the molecular basis for the comprehension of the role of the RRM3s in the CELF/Bruno-like family.