Browsing by Author "Chang, Kai-Ping"

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Characterization of Copy Number Variations in Oral Cavity Squamous Cell Carcinoma Reveals a Novel Role for MLLT3 in Cell Invasiveness
(1970-01-01)
Wang, Chun-, I
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Kao, Huang-Kai
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Chen, Ting-Wen
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Huang, Yenlin
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Cheng, Hsing-Wen
Background DNA copy number variations (CNVs) are a hallmark of cancer, and the current study aimed to demonstrate the profile of the CNVs for oral cavity squamous cell carcinoma (OSCC) and elucidate the clinicopathological associations and molecular mechanisms of a potential marker derived from CNVs, mixed-lineage leukemia translocated to chromosome 3 protein (MLLT3), in OSCC carcinogenesis. Materials and Methods CNVs in 37 OSCC tissue specimens were analyzed using a high-resolution microarray, the OncoScan array. Gene expression was analyzed by real-time polymerase chain reaction in 127 OSCC and normal tissue samples. Cell function assays included cell cycle, migration, invasion and chromatin immunoprecipitation assays. Results We found a novel copy number amplified region, chromosome 9p, encompassing MLLT3 via the comparison of our data set with six other OSCC genome-wide CNV data sets. MLLT3 overexpression was associated with poorer overall survival in patients with OSCC (p = .048). MLLT3 knockdown reduced cell migration and invasion. The reduced invasion ability in MLLT3-knockdown cells was rescued with double knockdown of MLLT3 and CBP/p300-interacting transactivator with ED rich carboxy-terminal domain 4 (CITED4; 21.0% vs. 61.5%). Knockdown of MLLT3 impaired disruptor of telomeric silencing-1-like (Dot1L)-associated hypermethylation in the promoter of the tumor suppressor, CITED4 (p < .001), and hence dysregulated HIF-1 alpha-mediated genes (TWIST, MMP1, MMP2, VIM, and CDH1) in OSCC cells. Conclusion We identified unique CNVs in tumors of Taiwanese patients with OSCC. Notably, MLLT3 overexpression is related to the poorer prognosis of patients with OSCC and is required for Dot1L-mediated transcriptional repression of CITED4, leading to dysregulation of HIF-1 alpha-mediated genes. Implications for Practice This article reports unique copy number variations in oral cavity squamous cell carcinoma (OSCC) tumors of Taiwanese patients. Notably, MLLT3 overexpression is related to the poorer prognosis of patients with OSCC and is required for Dot1L-mediated transcriptional repression of CITED4, leading to dysregulation of HIF-1 alpha-mediated genes.
Discovering pattern-aware routes from trajectories
(2015-06-01)
Wei, Ling-Yin
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Chang, Kai-Ping
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Peng, Wen-Chih
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交大名義發表
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National Chiao Tung University
With the prevalence of GPS-equipped devices and navigation services, users can record and share their driving movements via trajectories. These trajectories reveal users\' driving behaviors for planning routes. In this paper, we propose a novel pattern-aware route discovery framework that considers users\' preferred routes. The proposed framework is comprised of two components: pattern-aware road map generation and route planning. In the first component, we mine significant road segments from historical trajectories, and generate a pattern-aware road map. We design a route score function that strikes a balance between user preference degrees and the length of the route. For the second component, given a source, a destination, and a user pre-defined value k, we intend to derive the top-k routes that consist of road segments from the source to the destination in the pattern-aware road map. To support on-line route planning in most navigation services, we propose a constrained breadth-first-search (CBFS) algorithm. We evaluate the performance of our framework using real trajectory data, and compare our framework with an existing approach in terms of effectiveness and efficiency. The experimental results demonstrate the effectiveness and efficiency of our proposed framework.
Growth characteristics of Fe-doped GaN epilayers on SiC (001) substrates and their effects on high breakdown voltage devices
(2020-11-15)
Chang, Kai-Ping
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Lin, Po-Jung
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Horng, Ray-Hua
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Wuu, Dong-Sing
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電子工程學系及電子研究所
The growth characteristics of Fe-doped GaN epitaxial layers on semi-insulating SiC (001) substrates were studied using metalorganic chemical vapor deposition for high breakdown voltage device applications. A smooth Fe-doped GaN epilayer surface can be realized by changing the ferrocene flow, while higher Fe concentrations in the GaN epilayer affect the surface morphology. To reduce the Fe trapping carrier and the sheet resistances of the two-dimension electron gas generated from the interface of AlGaN and GaN, the thickness ratio of Fe-doped and undoped GaN bi-epilayers was also optimized. AlGaN/GaN high electron mobility transistors with the optimum doping concentration of Fe-doped GaN and suitable thickness of undoped GaN have been successfully developed. The achieved breakdown voltage of the Fe-doped GaN epitaxial layer can be as high as 2457 V, which is attributed to the Fe-doped GaN epitaxial layer with higher resistance, which can sustain the high breakdown voltage. The details of the correlation between the surface morphology, Fe concentration, and thickness of Fe-doped GaN epitaxial layers used for high breakdown voltage devices will be also discussed in this paper.