Polarization resolved reflection from ordered vertical silicon nanowire arrays

We measure polarization resolved reflections from ordered vertical silicon nanowire arrays of two different diameters and compare the results to rigorous coupled wave analysis simulations. Ellipsometric analysis based on anisotropic effective-medium approximation is used to fit the experimental data and estimate the diameter and length of the nanowires. In addition, depolarization of light is observed for wavelengths below 400 nm.

Enhancement of bandgap emission of Pt-capped MgZnO films: important role of light extraction versus exciton-plasmon coupling

We present on a systematic study of the contribution of surface plasmon (SP) coupling and light extraction toward emission enhancement of Platinum (Pt) nano-patterns capped MgZnO films. Time resolved Photoluminescence (PL) results indicate that the Pt coating can greatly reduces the non-radiative recombination rate by passivation of surface states, making the decay slow down. Temperature dependence of the integrated photoluminescence intensity reveals that the Pt nano-patterns can offer a large amount of light transfer and scattering, which enormously increase the light extraction efficiency up to 3.8-fold. These results indicate that the increased light extraction efficiency caused by surface modification via Pt coating rather than SP coupling plays a dominant role in increasing bandgap emission of MgZnO film.

miR-21, miR-17 and miR-19a induced by phosphatase of regenerating liver-3 promote the proliferation and metastasis of colon cancer

Background:

Phosphatase of regenerating liver-3 (PRL-3) is an oncogene known to promote tumour metastasis, especially in colorectal cancer (CRC). Here, we demonstrate that the miR-21, miR-17 and miR-19a expressions induced by PRL-3 are involved in the proliferation and metastasis of colon cancer.

Methods:

Microarray analysis and quantitative reverse-transcription polymerase chain reactions (qRT–PCR) were used to investigate the changes in miRNA expression due to the overexpression of PRL-3. Transwell chamber invasion assays, CCK-8 proliferation assays and RNA interference assays were used to explore the effects of PRL-3 on miR-21, miR-17 and miR-19a expression in colon cancer cells. Immunohistochemistry and qRT–PCR were performed in colon cancer tissues to evaluate the expression of PRL-3, signal transducer and activator of transcription 3 (STAT3), miR-21, miR-17 and miR-19a.

Results:

Our study demonstrated that the overexpression of PRL-3 in colon cancer cells induced the expression of miR-21, miR-17 and miR-19a by activating STAT3. Subsequently, these microRNAs contributed to the increased proliferation and invasiveness of the colon cancer cells. Positive correlations between PRL-3 and these microRNAs were also observed in matched primary colon cancer tissues and metastatic lesions.

Conclusion:

miR-21, miR-17 and miR-19a induced by PRL-3 contribute to the proliferation and invasion of colon cancer.

MicroRNA-337 is associated with chondrogenesis through regulating TGFBR2 expression

OBJECTIVE

MicroRNAs (miRNAs) have been implicated in regulating diverse cellular pathways and involved in development and inflammation. This study aimed to examine six miRNAs expression during the cartilage development and identify the key miRNA which is associated with chondrogenesis.

METHODS

The expression of six miRNAs in cartilage tissue during development was screened by real-time quantitative polymerase chain reaction (RT-qPCR). Rat models of bone matrix gelatin induced endochondral ossification, collagen-induced arthritis and pristane-induced arthritis were established to examine whether miR-337 is involved in chondrogenesis. Furthermore, the regulation of transforming growth factor-b type II receptor (TGFBR2) expression by miR-337 was determined with the luciferase reporter gene assay and Western blot. The expression of some specific genes relevant to cartilage tissue was tested by RT-qPCR after miR-337 mimic or inhibitor transfection.

RESULTS

MiR-337 expression was significantly down-regulated and almost disappeared in the maturation phases of endochondral ossification. The results of histology and RT-qPCR from three rat models showed that miR-337 is directly bound up with chondrogenesis. Furthermore, the results from the luciferase reporter gene assay and Western blot indicated that miR-337 regulated TGFBR2 expression. Our study also found that the enhancement of miR-337 may modulate the expression of cartilage-specific genes such as AGC1 in C-28/I2 chondrocytes.

CONCLUSION

We proved that miRNA-337 is associated with chondrogenesis through regulating TGFBR2 expression, and miRNA-337 can also influence cartilage-specific gene expression in chondrocytes. These findings may provide an important clue for further research in the arthritis pathogenesis and suggest a new remedy for arthritis treatment.

WE-E-BRB-08: Establishing Comprehensive Quality Assurance Program for Volumetric Modulated Arc Therapy - Clinical Study Using Control Point Analysis Software

PURPOSE

to validate the clinical effectiveness of Control Point Analysis (CPA) software and establish a comprehensive quality assurance (QA) program for Volumetric Modulated Arc Therapy (VMAT) treatment.

METHODS

The comparison and gamma analysis of ArcCHECK™ measurement and treatment planning system (TPS) is considered one of the common methods for VMAT QA procedure. However, questions like 'how QA discrepancies affect patient treatment^† and ^† what are the sources of discrepancies^† cannot be answered. In this study, 3DVH™ and recently developed CPA software were tested for eight cases, including prostate, brain, head&neck, and TGI 19 phantom cases. All VMAT plans used two arcs, with various settings of couch rotation, collimator rotation, and splitting fields. Each single arc was equally divided into 24 sub-arcs and doses of sub-arcs were exported for CPA analysis. Gamma analyses (3mm/3%) were compared using the ArcCHECK dose, single arc doses, sub-arc doses, and 3DVH patient's dose estimated by Planned Dose Perturbation™ (PDP) algorithm.

RESULTS

ArcCHECK composite dose analyses were consistent with CPA sub-arc analysis for most cases. 3DVH generally showed higher passing rate in dose voxel-by-voxel comparison. Cases with failed QA were further analyzed by CPA for each sub-arc to reveal the sources of dose discrepancies, whether they are mechanical errors (i.e. leaf motion failure) or dosimetric modeling errors (i.e. elongated beam spot size or incorrect dynamic leaf gap). CPA analysis showed values for cases with passed QA to detect small discrepancies caused by failed MLC which was otherwise smeared out in the composite dose comparison.

CONCLUSIONS

CPA analysis expands QA process to a greater level of details without additional work by users. With the additions of CPA analysis and 3DVH™, one can establish a comprehensive VMAT QA program with detailed mapping of composite dose passing rate, the estimated effect of discrepancies on patients, and possible sources of discrepancies.

Vasohibin 2 is transcriptionally activated and promotes angiogenesis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) typically relies on angiogenesis for its malignant behavior, including growth and metastasis. Vasohibin 2 (VASH2) was previously identified as an angiogenic factor, but its role in tumorigenesis is unknown. Using quantitative PCR and western blot analyses, we found that VASH2 is overexpressed in HCC cells and tissues. Using chromatin immunoprecipitation, we detected histone modifications at the putative VASH2 promoter, with increased H3K4 trimethylation and H3 acetylation and decreased H3K27 trimethylation, suggesting that epigenetic mechanisms are responsible for the deregulated VASH2 transcription in HCC. Knockdown of VASH2 via siRNA inhibited the proliferation of the hepatoma cell lines by delaying cell cycle progression and increasing apoptosis. Importantly, we found VASH2 secreted in the culture supernatant, and co-expression of its secretory chaperone small vasohibin-binding protein (SVBP) further enhanced VASH2 secretion. The supernatant from HepG2 cells expressing VASH2 enhanced the proliferation, migration and tube formation of human umbilical vein endothelial cells, and knockdown of VASH2 significantly inhibited these effects. In an in vivo study using a nude mouse model, we found that exogenous VASH2 significantly contributed to tumor growth, microvessel density and hemoglobin concentration in the tumors. Further analyses showed that the VASH2-mediated increase in the transcription of fibroblast growth factor-2, vascular endothelial growth factor and vasohibin 1 may be the mechanism underlying these effects. Taken together, these data indicate that VASH2 is abnormally expressed in HCC cells as a result of histone modifications and that VASH2 contributes to the angiogenesis in HCC via an SVBP-mediated paracrine mechanism. These results indicate a novel and important role for VASH2 in HCC angiogenesis and malignant transformation.

Reprogramming of mesenchymal stem cells by the synovial sarcoma-associated oncogene SYT-SSX2

Cell identity is determined by its gene expression programs. The ability of a cell to change its identity and produce cell types outside its lineage is achieved by the activity of transcription controllers capable of reprogramming differentiation gene networks. The synovial sarcoma (SS)-associated protein, SYT-SSX2, reprograms myogenic progenitors and human bone marrow-derived mesenchymal stem cells (BMMSCs) by dictating their commitment to a pro-neural lineage. It fulfills this function by directly targeting an extensive array of neural-specific genes as well as genes of developmental pathway mediators. Concomitantly, the ability of both myoblasts and BMMSCs to differentiate into their normal myogenic and adipogenic lineages was compromised. SS is believed to arise in mesenchymal stem cells where formation of the t(X/18) translocation product, SYT-SSX, constitutes the primary event in the cancer. SYT-SSX is therefore believed to initiate tumorigenesis in its target stem cell. The data presented here allow a glimpse at the initial events that likely occur when SYT-SSX2 is first expressed, and its dominant function in subverting the nuclear program of the stem cell, leading to its aberrant differentiation, as a first step toward transformation. In addition, we identified the fibroblast growth factor receptor gene, Fgfr2, as one occupied and upregulated by SYT-SSX2. Knockdown of FGFR2 in both BMMSCs and SS cells abrogated their growth and attenuated their neural phenotype. These results support the notion that the SYT-SSX2 nuclear function and differentiation effects are conserved throughout sarcoma development and are required for its maintenance beyond the initial phase. They also provide the stem cell regulator, FGFR2, as a promising candidate target for future SS therapy.

DNA-PKcs interacts with Aire and regulates the expression of toll-like receptors in RAW264.7 cells

The autoimmune regulator (Aire) is a key mediator of the central tolerance for peripheral tissue self-antigen (PTAs) and is involved in the transcriptional control of many antigens in thymic medullary epithelial cells (mTECs). However, the function of Aire in peripheral lymphoid tissues and haematopoietic cells, particularly in monocytes and macrophages, remains poorly understood. We previously found that the expression of Toll-like receptor (TLR) 1, TLR3 and TLR8 was notably upregulated in pEGFPC1/Aire stably transfected RAW264.7 (GFP-Aire/RAW) cells, while the expressions of other TLRs were not significantly changed. The mechanism by which Aire affects TLR1, TLR3 and TLR8 expression is not clear. Interactions with other proteins, such as DNA-dependent protein kinase (DNA-PK), are crucial for regulating the transcriptional activity of Aire. In this study, we found that Aire and DNA-PK catalytic subunit (DNA-PKcs) were co-located in the nucleus of GFP-Aire/RAW cells, and they interact with each other. Small interfering RNA knock-down of DNA-PKcs in these cells decreased the expression of TLR1, TLR3 and TLR8, but no change was observed in pEGFPC1 stably transfected RAW264.7 (GFP/RAW) cells. We did not observe any change in the expressions of other TLRs after DNA-PKcs knock-down in GFP-Aire/RAW or GFP/RAW cells. A similar observation has been made in pEGFPC1/Aire or pEGFPC1 transiently transfected primary peritoneal macrophages. Using a luciferase activity assay, we found the that the transcriptional activity of TLR1, TLR3 and TLR8 promoters was also decreased after knock-down of DNA-PKcs in GFP-Aire/RAW cells. In conclusion, our results suggest that DNA-PKcs may interact with Aire to promote the expression of TLRs in RAW264.7 cells.