Oncogenic KIT-containing exosomes increase gastrointestinal stromal tumor cell invasion

During tumor development, constant interplay occurs between tumor cells and surrounding stromal cells. We report evidence that gastrointestinal stromal tumor (GIST) cells invade the interstitial stroma through the release of the oncogenic protein tyrosine kinase (KIT)-containing exosomes, which triggers the phenotypic conversion of progenitor smooth muscle cells to tumor-promoting cells. These recipient cells display morphologic changes and acquire tumor-associated phenotypes, including enhanced adhesion to extracellular matrix proteins, activation of intracellular pathways downstream of KIT, expression of Interstitial Cell of Cajal–like markers, and release of various matrix metalloproteinases (MMPs), particularly MMP1. This report shows stimulation of MMP1 production by stromal cells via uptake of tumor-derived exosomes, which leads to tumor cell invasion. Exosomes derived from GIST patients but not healthy donors show enhanced MMP1 secretion by smooth muscle cells and tumor cell invasion, whereas selective blocking of exosome-mediated MMP1 secretion decreases tumor invasiveness. Our study indicates that exosome release and subsequent MMP1 induction creates a positive feedback mechanism established between tumor and stromal cells that drives GIST development and offers unique insights for potential therapeutic strategies to block GIST progression and metastatic spread.With the ultimate goal of fulfilling their needs for exogenous supply of growth factors, chemokines, cytokines, and matrix-degrading enzymes, tumor cells communicate with their surrounding stroma using several intercellular communication mechanisms (1, 2). In the last decade, various tumors have been shown to rely on the release of bioactive membrane vesicles known as exosomes (3). Tumor cells of various origins constitutively release these vesicles, which are believed to be important in the processes of malignant transformation and tumor progression. Exosomes share certain common characteristics, including their shape, size, density, and general protein composition (3). Their effects are mediated via transfer of cargo that comprises an array of proteins (4), RNA (5), and mitochondrial DNA (6). Accordingly, their role as mediators in tumor progression has been the focus of several recent studies (7, 8). However, the majority of these studies focused on human malignancies of epithelial origin (i.e., carcinomas), whereas little attention has been given to the tumor microenvironment associated with malignancies of mesenchymal origin (i.e., sarcomas).Sarcomas represent an interesting and unique tumor type in which cancer cells of mesenchymal origin are surrounded by stromal cells of the same origin. The focus of this study is on the most common mesenchymal tumor of the digestive tract, gastrointestinal stromal tumor (GIST) (9). Approximately 75% of GISTs contain oncogenic mutations in the receptor tyrosine kinase c-KIT [normal cellular homolog of the viral oncoprotein v-Kit (v-Kit, Hardy Zuckerman 4 feline sarcoma viral oncogene homolog)] (10, 11), which plays a central role in the pathogenesis of this disease (10, 12). GISTs are believed to arise from the Interstitial Cells of Cajal (ICCs) (13), the pacemaker cells of the gastrointestinal tract, or interstitial mesenchymal precursor stem cells (14). This similarity between GISTs and ICCs is further borne out by the expression of the KIT protein (also called CD117) in nonneoplastic ICC and most GISTs (11). The identification of a fundamental hallmark of the biology of GISTs (i.e., gain-of-function KIT mutations) resulted in the rapid transformation of the treatment paradigm for this tumor type (15, 16). Small molecule tyrosine kinase inhibitors, most notably imatinib mesylate (also known as Gleevec), have been developed and were found to be effective in the treatment of GISTs (16–18). However, the median time to recurrence for patients with metastatic GIST receiving imatinib is only 2 y. Although much is known about the molecular genetic features of GIST, the importance of their interactions with the stromal microenvironment during metastasis has received little attention. Therefore, we investigated the role of exosomes in mediating the complex interplay between tumor and stroma during progression. We report evidence that (i) GIST cells secrete a high number of oncogenic KIT-containing exosomes, (ii) stromal cell uptake of GIST-derived exosomes promotes the generation of ICC-like cells and induce tumor invasiveness, and (iii) circulating exosomes from GIST patients induce matrix metalloproteinase 1 (MMP1) secretion by host stromal cells.     

Four highly oxygenated isopimarane-type diterpenes of Orthosiphon stamineus

Four highly oxygenated isopimarane-type diterpenes, named orthosiphols O, P and Q and nororthosiphonolide A, have been isolated from the aerial parts of Orthosiphon stamineus from Myanmar, together with three known diterpenes, orthosiphols D and E and orthosiphonone A. Their structures were determined on the basis of extensive spectral analysis. All the isolated compounds displayed mild antiproliferative activities against highly liver metastatic colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cell lines.     

Three new C-14 oxygenated taxanes from the wood of Taxus yunnanensis

Three new C-14 oxygenated taxane-type diterpenes, hongdoushans A-C (1-3), were isolated from the wood of Taxus yunnanensis together with four known diterpenes and two lignans. The absolute stereochemistry of the 2-methylbutyryloxy group attached at C-14 of the taxane skeleton was determined to be S by GC analysis of the methyl ester of 2-methylbutyric acid obtained after alkaline hydrolysis of 1 and 4 followed by treatment with CH(2)N(2). The complete stereostructure of the known compound 2alpha,5alpha,10beta-triacetoxy-14beta-[(S)-2-methylbutyryloxy]-4(20),11-taxadiene (4) was established for the first time. The isolates obtained were evaluated for their antiproliferative activity toward murine colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cell lines.     

Quadranosides I-V, new triterpene glucosides from the seeds of Combretum quadrangulare

Five new triterpene glucosides, quadranosides I-V (1-5), have been isolated from a MeOH extract of the seeds of Combretum quadrangulare, together with 13 known compounds. The structures of compounds 1-5 were elucidated on the basis of spectroscopic analysis. Among the new triterpene glucosides, three compounds (1, 2, 5) showed significant hepatoprotective effects against D-galactosamine (D-GalN)/tumor necrosis factor-alpha (TNF-alpha)-induced cell death in primary cultured mouse hepatocytes.     

DPPH radical scavenging and nitric oxide inhibitory activities of the constituents from the wood of Taxus yunnanensis

The H2O, H2O/MeOH (1 : 1) and MeOH extracts of the wood of Taxus yunnanensis possessed significant DPPH radical scavenging and nitric oxide (NO) inhibitory activities. Chemical investigation of these extracts led us to isolation of nineteen compounds, i. e., five lignans, two simple phenolics, and twelve taxane-type diterpenes. Isotaxiresinol and seco-isolariciresinol, two major lignans of the wood, possessed potent DPPH radical scavenging activities with IC 50 values of 21.7 and 28.9 microM, respectively. Similarly, coniferyl aldehyde, taxusin, 10-deacetyltaxuyunnanine C, hongdoushan A, and 2alpha,5alpha,10beta-triacetoxy-14beta-[( S)-2-methylbutyryloxy]-4(20),11-taxadiene showed potent NO inhibitory activity with IC 50 values of 18.0, 22.1, 28.5, 15.0 and 26.4 microM, respectively, which were either equal or lower than the positive control NG-monomethyl- L-arginine ( L -NMMA) with an IC 50 value of 28.5 microM.     

New spirostanol steroids and steroidal saponins from roots and rhizomes of Dracaena angustifolia and their antiproliferative activity

The MeOH extract of Nam ginseng (roots and rhizomes of Dracaena angustifolia) afforded nine new compounds, including three spirostanol sapogenins, named namogenins A-C (1-3), four spirostanol saponins, named namonins A-D (4-7), a furostanol saponin, named namonin E (8), and a pregnan glycoside, named namonin F (9), along with another eight known steroidal saponins (10-17). Their structures were determined on the basis of spectral analyses and chemical methods. All compounds were tested for their antiproliferative activity against murine colon 26-L5 carcinoma, human HT-1080 fibrosarcoma, and B-16 BL6 melanoma cells. Compounds 4, 5, and 10 showed potent antiproliferative activity against HT-1080 fibrosarcoma cells, having IC(50) values of 0.2, 0.3, and 0.6 microM, respectively, comparable to that of doxorubicin.     

Blepharocalyxins C--E, three new dimeric diarylheptanoids, and related compounds from the seeds of Alpinia blepharocalyx

Three novel diarylheptanoids, blepharocalyxins C--E (5--7), together with four new (1--4) and one known (8) diarylheptanoids bearing a tetrahydropyran ring were isolated from the residual fraction of an EtOH extract of the seeds of Alpinia blepharocalyx. The structures and the stereochemistry at the chiral centers of the new diarylheptanoids were elucidated by spectroscopic techniques including 2D NMR spectroscopy. Blepharocalyxins C--E (5--7) have a novel carbon framework and are dimeric diarylheptanoids consisting of two diarylheptanoid units. Blepharocalyxin D (6) showed potent antiproliferative activity against murine colon 26-L5 carcinoma cells (ED(50), 3.61 microM), while against human HT-1080 fibrosarcoma cells, blepharocalyxin E (7) showed potent activity (ED(50), 9.02 microM).     

Managing the Injury Burden in Nepal

Nepal loses about 530,000 disability adjusted life years (DALYs) per year to injury, predominantly due to falls. It takes 30,000 Nepali rupees (NR), or approximately US$430 at 70 rupees per $US saved per DALY to achieve primary prevention and 6000 NR per DALY if we invest in hospitals, versus 1000 NR invested in prehospital care, because simpler less expensive actions performed early have a greater impact on outcome than more complex measures later. A system for prehospital services was planned for medical emergencies at a national level meeting at the Medical University of Nepal to promote healthcare to victims in inaccessible regions by empowered or enlightened citizens. Feasible actions for common emergencies were defined and a tutorial required to help the majority of such victims was created and packaged. The knowledge and attitude component of the tutorial will be delivered through a web site to citizens motivated to learn and help with emergencies. The knowledge will be tested through a net-based Multiple Choice Questions (MCQ) test. Practical training in medical triage skills will be provided to those who qualify for the test at the University or its designated affiliates. A mobile phone-based information system will be created and used to make these enlightened citizens available to the victim at the site/time of the emergency. Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.

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Processing and release of insulin and insulin-like growth factor I by macro- and microvascular endothelial cells

Insulin and insulin-like growth factor I (IGF-I) processing by macro- and microvascular endothelial cells was investigated. Specific binding of insulin and IGF-I on the capillary endothelial cells derived from rat fat pads was 4 +/- 0.5% (+/- SE) and 4.3 +/- 0.3%/mg protein, respectively, in contrast to bovine aortic endothelial cells, which bound 9.3 +/- 0.3% IGF-I/mg protein. Both binding and processing of insulin and IGF-I were time and temperature dependent in macro- and microvascular endothelial cells. After 30 min at 37 C, between 40-50% of the bound IGF-I and insulin were internalized in both capillary and aortic endothelial cells, whereas 20-25% insulin and 15-20% IGF-I internalization were observed at 15 C. Less than 20% internalization was observed for both insulin and IGF-I at 4 C. Cellular inhibitors of hormone processing, such as chloroquine and monensin, enhanced cell-associated insulin at 37 C on the bovine aortic endothelial cells from 4.7% to 10.4 +/- 1% and 9.9 +/- 2% mg protein, respectively, at 60 min. Similarly, chloroquine and monensin increased the amount of [125I]IGF-I associated with aortic endothelial cells from 4.3 +/- 0.2% to 5.5 +/- 0.3% and 6.2 +/- 0.7%/mg protein, respectively. Chloroquine and monensin increased [125I]insulin associated with rat capillary endothelial cells from a control of 2.9 +/- 0.1% to 4.0 +/- 0.2% and 3.8% +/- 0.37%, respectively. No effect of chloroquine and monensin was observed on [125I]IGF-I binding to rat capillary endothelial cells. Leupeptin, a lysosomal protease inhibitor, did not affect insulin or IGF-I binding in either cell type. The internalized insulin and IGF-I were both rapidly released, with 70-80% of both hormones being detected in the medium by 120 min. The released hormones were mostly intact (greater than 80-90%), as assessed by trichloroacetic acid precipitability, gel filtration, and immunoprecipitation. Both insulin and IGF-I induced corresponding down-regulation of their receptors, as shown by a 66 +/- 7% decrease in insulin binding in the capillary endothelial cells and a 72 +/- 1% and 58 +/- 1% decrease in IGF-I binding in the aortic and capillary endothelial cells, respectively. Thus, macro- and microvascular endothelial cells bind and process insulin and IGF-I by degradative and nondegradative pathways. The predominance of the nondegradative pathway for the processing of insulin and IGF-I and the modulation of their receptors by physiological hormone concentrations suggested that endothelial cells may regulate the access of insulin and IGF-I to their target cells.     

Lipoblastoma in head and neck--a rare childhood tumour

Lipoblastoma is an uncommon benign mesenchymal tumour that occurs primarily in children younger than 3 yrs of age. Despite the lesions being benign, great difficulty can be encountered in its management because of its tendency to invade the different fascial planes. A rare case of huge lipoblastoma diagnosed in a 22 months old child, involving various spaces of face and skull base has been reported. This huge tumour was completely and successfully removed through cheek incision without any postoperative complications.