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ABSTRACT: Gastric cancer (GC) is the fourth most common cancer worldwide. In spite of the mortality incidence associated with GC, no reliable prognostic biomarkers are currently available for this malignancy. The sulfatases (or SULFs), SULF1 and SULF2, play a critical role in the pathogenesis of a variety of human cancers. We sought to evaluate the potential of SULFs as biomarkers for GC. Thirty pairs of GC and corresponding normal tissues were analysed for the expression and methylation status of SULFs. Furthermore, the functional role of SULF overexpression was investigated in GC cell lines and tumour xenograft animal models. Lastly, we validated the expression of SULF1 protein in a large cohort of 450 GC patients. GC tissues showed conspicuously higher expression of SULF1 (p = 0.0002) and SULF2 (p = 0.001) compared to normal mucosa, which was correlated with its promoter hypomethylation. Furthermore, high expression of SULFs caused marked acceleration in the growth of xenograft tumours in nude mice. The expression of SULF1 protein significantly correlated with higher recurrence rates (p = 0.0002) and worse overall survival (p < 0.0001) in GC patients. Multivariate analysis revealed that SULF1 is an independent prognostic (p = 0.0123) and lymph node metastasis predictive factor (p = 0.0003) in patients with GC. We provide novel evidence that hypomethylation of promoter CpG islands within SULF genes imparts them with oncogenic potential in GC. Moreover, our data suggest that SULF1 may serve as a promising biomarker for patients with GC.
The Journal of Pathology 05/2012; 228(1):88-98. · 6.32 Impact Factor
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ABSTRACT: The prognosis of peritoneal carcinomatosis is regarded as poor because safe, effective therapeutic modalities are lacking. Intraperitoneal chemotherapy is one treatment option, involving the delivery of a high concentration of chemotherapeutic drugs into the abdominal cavity, but the severe side effects associated with such treatment are a major obstacle in clinical application. We evaluated the anti-cancer effects of intraperitoneal delivery of a thermosensitive polymeric hydrogel containing chemotherapeutics in an animal model of carcinomatosis. The progress of peritoneal carcinomatosis, introduced by injecting a luciferase-transfected human gastric cancer cell line (HSC44Luc) into the peritoneal cavity of nude mice, was quantitatively evaluated by in vivo bioluminescence imaging. Three days after intraperitoneal (IP) injection of HSC44Luc cells, treatment solutions were injected into the peritoneal cavity. Mice were categorized into four groups depending on treatment method; these were (1) a control PBS group (n = 5), (2) a hydrogel-only group (n = 5), (3) a paclitaxel solution (30 mg/kg) group (n = 3), and (4) a hydrogel-with-paclitaxel (15 mg/kg) group (n = 5). Quantitative photon counting was performed weekly in each animal. Mice were sacrificed on the 5th or 28th day after treatment, for pathologic evaluation. In vivo bioluminescence imaging showed that photon counts in the hydrogel-with-paclitaxel and paclitaxel solution groups were significantly lower than in the PBS group over the entire experimental period. Although neither group of responding mice showed any peritoneal nodules on the 28th day after treatment, only the paclitaxel solution group exhibited dilated edematous changes in the intestine; these side effects were absent in animals treated with hydrogel-with-paclitaxel group. In conclusion, a thermosensitive hydrogel containing paclitaxel may be a safe and effective treatment option for peritoneal carcinomatosis.
Investigational New Drugs 02/2012; 30(1):1-7. · 3.36 Impact Factor
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ABSTRACT: Manipulation and improper handling of a tumor during surgery may increase the risk of cancer cell dissemination after a curative gastrectomy. This study investigated the effect of improper handling of lymphovascular pedicles of stomach on tumor spillage during surgical procedure.
Thirty-eight gastric cancer patients were enrolled. Three pairs of wash samples were obtained from each patient: (1) intraperitoneal wash samples obtained before (P0) and after gastrectomy (P1), (2) intragastric wash samples obtained before any manipulation (G0) and just before resection of the stomach (G1), and (3) ex vivo wash samples obtained by rinsing resected stomach with the lymphovascular pedicles closed by clips (S0) or with the pedicles open (S1). Cytologic examination was performed from all washes, and real-time reverse transcriptase-polymerase chain reaction analysis for carcinoembryonic antigen was performed from washes P0, P1, S0, and S1.
Cytologic examination detected cancer cells in 34.2% (13 of 38) of G0 samples and in 39.5% (15 of 38) of G1 samples. The rate of conversion from G0-negative to G1-positive increased as T stage increased. Cytologic examination detected cancer cells in 2.6% (1 of 38) of S0 samples and in 13.2% (5 of 38) of S1 samples. The carcinoembryonic antigen mRNA level of the S1 sample was 2-fold greater than that of the S0 sample in 50.0% (7 of 14).
Free cancer cells can be released from gastric lumen or lymphovascular pedicles opened during gastric cancer surgery, especially in advanced-stage disease. Care should be taken to minimize spillage from the gastric lumen and lymphovascular pedicles.
Annals of Surgical Oncology 04/2011; 18(10):2818-25. · 4.17 Impact Factor
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ABSTRACT: Cooperative Communication (CC) is a technology that allows multiple nodes to simultaneously transmit the same data. It can save power and extend transmission coverage. However, prior research work on topology control considers CC only in the aspect of energy saving, not that of coverage extension. We identify the challenges in the development of a centralized topology control scheme, named Cooperative Bridges, which reduces transmission power of nodes as well as increases network connectivity. We observe that CC can bridge (link) disconnected networks. We propose two algorithms that select the most energy efficient neighbor nodes, which assist a source to communicate with a destination node; an optimal method and a greedy heuristic. In addition we consider a distributed version of the proposed topology control scheme. Our findings are substantiated by an extensive simulation study, through which we show that the Cooperative Bridges scheme substantially increases the connectivity while consuming a similar amount of transmission power compared to other existing topology control schemes.
INFOCOM, 2010 Proceedings IEEE; 04/2010
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ABSTRACT: In this paper, we tackle issues on the exposed terminal problem in IEEE 802.11 based wireless networks from a simulative perspective by investigating the internal relationship of node transmission behaviors under various network scenarios. The proposed solution is designed to learn node behaviors according to incoming traffic patterns and to assist wireless nodes make accurate transmission judgment to avoid exposed terminal problems as much as possible. Extensive simulations using ns-2 have been performed to validate the proposed scheme by varying system parameters including carrier sense range and hop counters. Our experimental outcomes show that the proposed solution yields performance gains in terms of aggregate throughput in excess of 10% to 15% compared to the standard.
Ubiquitous and Future Networks, 2009. ICUFN 2009. First International Conference on; 07/2009
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Young-Kook Kim, Jieun Yu,
Tae Su Han,
Seong-Yeon Park,
Bumjin Namkoong,
Dong Hyuk Kim,
Keun Hur,
Moon-Won Yoo,
Hyuk-Joon Lee,
Han-Kwang Yang,
V Narry Kim
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ABSTRACT: microRNAs (miRNAs) play integral roles in diverse processes including tumorigenesis. miRNA gene loci are often found in close conjunction, and such clustered miRNA genes are transcribed from a common promoter to generate polycistronic primary transcript. The primary transcript (pri-miRNA) is then processed by two RNase III proteins to release the mature miRNAs. Although it has been speculated that the miRNAs in the same cluster may play related biological functions, this has not been experimentally addressed. Here we report that the miRNAs in two clusters (miR-106b approximately 93 approximately 25 and miR-222 approximately 221) suppress the Cip/Kip family members of Cdk inhibitors (p57(Kip2), p21(Cip1) and p27(Kip1)). We show that miR-25 targets p57 through the 3'-UTR. Furthermore, miR-106b and miR-93 control p21 while miR-222 and miR-221 regulate both p27 and p57. Ectopic expression of these miRNAs results in activation of Cdk2 and facilitation of G1/S phase transition. Consistent with these results, both clusters are abnormally upregulated in gastric cancer tissues compared to the corresponding normal tissues. Ectopic expression of miR-222 cluster enhanced tumor growth in the mouse xenograft model. Our study demonstrates the functional associations between clustered miRNAs and further implicates that effective cancer treatment may require a combinatorial approach to target multiple oncogenic miRNA clusters.
Nucleic Acids Research 02/2009; 37(5):1672-81. · 8.03 Impact Factor
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MSN 2008, The 4th International Conference on Mobile Ad-hoc and Sensor Networks, Wuhan, China, December 10-12, 2008; 01/2008
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ABSTRACT: Digital multimedia broadcasting (DMB) is one of burgeoning communication technologies, which can provide audio, video, and data services to mobile terminals using broadcasting infrastructures. Data services in terrestrial- digital multimedia broadcasting (T-DMB) inherently have the disadvantage of retransmitting a lot of data unnecessarily for reliability. This paper proposes a novel optimized transmission policy using segment size and repetition number variability, which maximizes the object- level throughput as well as improves reliability. The theoretical modeling and simulation results demonstrate that our policy provides a throughput gain over the conventional protocol.
IEEE Transactions on Consumer Electronics 09/2007; 53(3):877-884. · 0.94 Impact Factor
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ABSTRACT: Vertical handoff will be essential for the next generation heterogeneous wireless networks. We propose an Adaptive Vertical Handoff Decision Scheme called UbiComm to avoid unbeneficial handoffs in the integrated WiBro and WLAN networks. If the mobile node (MN)’s velocity is high and
moving pattern is irregular, more unnecessary handoffs can occur. Therefore, MN’s velocity and moving pattern are the important
factors of our handoff decision scheme. In order to avoid unbeneficial handoff the UbiComm adjusts the dwell time adaptively, and it also predicts the residence time in the target network. In addition, UbiComm’s adaptive dwell timer makes a MN receive service of a better network as long as possible. The simulation results show
that the reduction of unnecessary handoffs proposed in UbiComm improves the MN’s throughput.
09/2006: pages 344-356;
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Ubiquitous Computing Systems, Third International Symposium, UCS 2006, Seoul, Korea, October 11-13, 2006, Proceedings; 01/2006
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ABSTRACT: This paper proposes an adaptive and dynamic localized scheme unique to hierarchical clustering in RFID networks, while reducing the overlapping areas of clusters and consequently reducing collisions among RFID readers. Drew on our LLC scheme that adjusts cluster coverage to minimize energy consumption, low-energy localized clustering for RFID networks (LLCR) addresses RFID reader anti-collision problem in this paper. LLCR is a RFID reader anti-collision algorithm that minimizes collisions by minimizing overlapping areas of clusters that each RFID reader covers. LLCR takes into account each RFID reader's energy state as well as RFID reader collisions. For the energy state factor, we distinguish homogeneous RFID networks from heterogeneous ones according to computing power of each RFID reader. Therefore, we have designed efficient homo-LLCR and hetero-LLCR schemes for each case. Our simulation-based performance evaluation shows that LLCR minimizes energy consumption and overlapping areas of clusters of RFID readers.
Computer Communications and Networks, 2005. ICCCN 2005. Proceedings. 14th International Conference on; 11/2005
