• International Journal of Oral Biology
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• 제34권2호
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• pp.61-72
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• 2009

Chios gum mastic (CGM) is a resin produced from the stem and leaves of Pistiacia lentiscus L var chia, a plant which grows only on Chios Island in Greece. CGM has been used for many centuries as a dietary supplement and folk medicine for stomach and duodenal ulcers in many Mediterranean countries and is known also to induce cell cycle arrest and apoptosis in some cancer cells. In this study, we further investigated the induction and mechanisms underlying the apoptotic response to CGM treatment in the SCC25 human tongue squamous cell carcinoma cell line. The viability of SCC25 cells, human normal keratinocytes (HaCaT cells) and human gingival fibroblasts (HGF-1 cells), and the growth inhibition of SCC25 cells were assessed by MTT assay and clonogenic assay, respectively. Staining with Hoechst and hemacolor dyes and TUNEL assays were employed to detect SCC25 cells undergoing apoptosis. SCC25 cells were treated with CGM, and this was followed by western blotting, immunocytochemistry, confocal microscopy, FACScan flow cytometry, MMP activity and proteasome activity analyses. CGM treatment of SCC25 cells was found to result in a time- and dosedependent decrease in cell viability, a dose-dependent inhibition of cell growth, and apoptotic cell death. Interestingly, CGM showed a remarkable level of cytotoxicity in SCC25 cells but not in normal cells. Tested SCC25 cells also showed several lines of apoptotic manifestation. Taken together, our present findings demonstrate that CGM strongly inhibits cell proliferation by modulating the expression of G1 cell cycle-related proteins and induces apoptosis via the proteasome, mitochondria and caspase cascades in SCC25 cells.

• Asian Pacific Journal of Cancer Prevention
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• 제14권4호
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• pp.2325-2331
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• 2013

Objective: To detect effects of plumbagin on proliferation and apoptosis in non-small cell lung cancer cell lines, and investigate the underlying mechanisms. Materials and Methods: Human non-small cell lung cancer cell lines A549, H292 and H460 were treated with various concentrations of plumbagin. Cell proliferation rates was determined using both cell counting kit-8 (CCK-8) and clonogenic assays. Apoptosis was detected by annexin V/propidium iodide double-labeled flow cytometry and TUNEL assay. The levels of reactive oxygen species (ROS) were detected by flow cytometry. Activity of NF-${\kappa}B$ was examined by electrophoretic mobility shift assay (EMSA) and luciferase reporter assay. Western blotting was used to assess the expression of both NF-${\kappa}B$ regulated apoptotic-related gene and activation of p65 and $I{\kappa}B{\kappa}$. Results: Plumbagin dose-dependently inhibited proliferation of the lung cancer cells. The IC50 values of plumbagin in A549, H292, and H460 cells were 10.3 ${\mu}mol/L$, 7.3 ${\mu}mol/L$, and 6.1 ${\mu}mol/L$ for 12 hours, respectively. The compound concentration-dependently induced apoptosis of the three cell lines. Treatment with plumbagin increased the intracellular level of ROS, and inhibited the activation of NK-${\kappa}B$. In addition to inhibition of NF-${\kappa}B$/p65 nuclear translocation, the compound also suppressed the degradation of $I{\kappa}B{\kappa}$. ROS scavenger NAC highly reversed the effect of plumbagin on apoptosis and inactivation of NK-${\kappa}B$ in H460 cell line. Treatment with plumbagin also increased the activity of caspase-9 and caspase-3, downregulated the expression of Bcl-2, upregulated the expression of Bax, Bak, and CytC. Conclusions: Plumbagin inhibits cell growth and induces apoptosis in human lung cancer cells through an NF-${\kappa}B$-regulated mitochondrial-mediated pathway, involving activation of ROS.

• Asian Pacific Journal of Cancer Prevention
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• 제13권4호
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• pp.1289-1295
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• 2012

The use of herbal products as radiosensitizers is a promising approach to increase the efficacy of radiotherapy. However, adverse effects related to the use of herbal medicine on radiotherapy are not well characterized. The present study concerns the impact of Derris scandens Benth extract on the radiosensitivity of Hep-2 laryngeal cancer cells. Pretreatment with D. scandens extract prior to gamma irradiation significantly increased clonogenic survival and decreased the proportion of radiation-induced abnormal nuclei of Hep-2 cells. Furthermore, the extract was found to enhance radiation-induced G2/M phase arrest, induce Akt activation, and increase motility of Hep-2 cells. The study thus indicated that D. scandens extract potentiates radioresistance of Hep-2 cells, further demonstrating the importance of cellular background for the adverse effect of D. scandens extract on radiation response in a laryngeal cancer cell line.

• Biomolecules & Therapeutics
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• 제15권4호
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• pp.230-234
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• 2007

In anti-cancer therapies, radiotherapy and chemotherapy show a superior inhibition effect on cancer cell growth, but those are very toxic to normal tissues and organs. Particularly, drugs for neutropenia, one of chemotherapy agents, which suppress the function of bone marrow, are needed to be controlled in terms of their dosage and therapy period because of their side effect. Phellinus linteus polysaccharide (PL) has been reported to increase the number of splenocytes and bone marrow cells. PL has been shown to decrease the side effects of cyclophosphamide (CYC) treatment to the cancer patients. PL showed no effects in semisolid clonogenic assay, suggesting that PL doesn't contain substantial compounds to substitute for colony stimulating factors (CSFs). On the other hand, PL increased the expression of SCF, IL-3, GM-CSF, TPO genes. These results indicate that PL may promote the growth and proliferation of splenocytes and bone marrow cells through indirect or CSFs-dependent pathway, which may lead to a hematopoiesis.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1439-1448
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• 2022

Background: We investigated the feasibility of in vitro radiosensitivity prediction with gene expression using deep learning. Methods: A microarray gene expression of the National Cancer Institute-60 (NCI-60) panel was acquired from the Gene Expression Omnibus. The clonogenic surviving fractions at an absorbed dose of 2 Gy (SF2) from previous publications were used to measure in vitro radiosensitivity. The radiosensitivity prediction model was based on the convolutional neural network. The 6-fold cross-validation (CV) was applied to train and validate the model. Then, the leave-one-out cross-validation (LOOCV) was applied by using the large-errored samples as a validation set, to determine whether the error was from the high bias of the folded CV. The criteria for correct prediction were defined as an absolute error<0.01 or a relative error<10%. Results: Of the 174 triplicated samples of NCI-60, 171 samples were correctly predicted with the folded CV. Through an additional LOOCV, one more sample was correctly predicted, representing a prediction accuracy of 98.85% (172 out of 174 samples). The average relative error and absolute errors of 172 correctly predicted samples were 1.351±1.875% and 0.00596±0.00638, respectively. Conclusion: We demonstrated the feasibility of a deep learning-based in vitro radiosensitivity prediction using gene expression.

• 대한두경부종양학회지
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• 제22권2호
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• pp.130-136
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• 2006

Introduction : The sensitivity of tumor cells to radiotherapy is a critical determinant of local control and potential cure in advanced head and neck squamous cell carcinoma(HNSCC). The emergence of radioresistant tumor cells is an obstacle to cancer therapy. Most radioresistant cells have a higher proportion of cells in the Sphase of the cell cycle and a lower apoptotic fraction than radiosensitive cells. HSV replication is increased in cells that have higher S-phase fractions. NV1066 is an oncolytic herpes simplex virus type-1 mutant. We hypothesized that NV1066 replication and cytotoxicity are increased in radioresistant cells. The purpose of this study is to evaluate the antitumor efficacy of NV1066 to treat radioresistant HNSCC. Methods : Radioresistant cells were selected by treating five HNSCC cell lines with repeated conventional fractionated doses of radiation(2Gy/day), using a Cs-137 irradiator, up to a cumulative dose of 70Gy. Clonogenic cell survival and S-phase fractions were compared between radioresistant and parental radiosensitive cells. The two cell populations were then treated with NV1066 to examine viral replication, by the viral plaque assay and viral cytotoxicity. Results : Fractionated irradiation resulted in the selection of radioresistant cells. Radioresistant cells had a higher S-phase fraction(42.9%) compared to parental cells(26.2%). NV1066 replication in radioresistant cells was 7.4 times higher than in parental cells(p<0.01). Treatment with NV1066 resulted in increased cytotoxicity of 24.5% in radioresistant cells compared to parental cells(p<0.05). Conclusion : NV1066 showed increased viral replication and cytotoxicity in radioresistant HNSCC cell lines. These findings suggest a potential clinical application for this oncolytic viral therapy as treatment for radioresistant head and neck cancers.

• Radiation Oncology Journal
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• 제30권2호
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• pp.78-87
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• 2012

Purpose: Troglitazone (TRO) is a peroxisome proliferator-activated receptor ${\gamma}$ ($PPAR{\gamma}$) agonist. TRO has antiproliferative activity on many kinds of cancer cells via G1 arrest. TRO also increases $Cu^{2+}/Zn^{2+}$-superoxide dismutase (CuZnSOD) and catalase. Cell cycle, and SOD and catalase may affect on radiation sensitivity. We investigated the effect of TRO on radiation sensitivity in cancer cells in vitro. Materials and Methods: Three human cervix cancer cell lines (HeLa, Me180, and SiHa) were used. The protein expressions of SOD and catalase, and catalase activities were measured at 2-10 ${\mu}M$ of TRO for 24 hours. Cell cycle was evaluated with flow cytometry. Reactive oxygen species (ROS) was measured using 2',7'-dichlorofluorescin diacetate. Cell survival by radiation was measured with clonogenic assay. Results: By 5 ${\mu}M$ TRO for 24 hours, the mRNA, protein expression and activity of catalase were increased in all three cell lines. G0-G1 phase cells were increased in HeLa and Me180 by 5 ${\mu}M$ TRO for 24 hours, but those were not increased in SiHa. By pretreatment with 5 ${\mu}M$ TRO radiation sensitivity was increased in HeLa and Me180, but it was decreased in SiHa. In Me180, with 2 ${\mu}M$ TRO which increased catalase but not increased G0-G1 cells, radiosensitization was not observed. ROS produced by radiation was decreased with TRO. Conclusion: TRO increases radiation sensitivity through G0-G1 arrest or decreases radiation sensitivity through catalase-mediated ROS scavenging according to TRO dose or cell types. The change of radiation sensitivity by combined with TRO is not dependent on the PPAR ${\gamma}$ expression level.

• Asian Pacific Journal of Cancer Prevention
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• 제16권8호
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• pp.3301-3306
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• 2015

Nucleolin (C23) is an important anti-apoptotic protein that is ubiquitously expressed in exponentially growing eukaryotic cells. In order to understand the impact of C23 in radiation therapy, we attempted to investigate the relationship of C23 expression with the radiosensitivity of human non-small cell lung cancer (NSCLC) cells. We investigated the role of C23 in activating the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), which is a critical protein for DNA double-strand breaks (DSBs) repair. As a result, we found that the expression of C23 was negatively correlated with the radiosensitivity of NSCLC cell lines. In vitro clonogenic survival assays revealed that C23 knockdown increased the radiosensitivity of a human lung adenocarcinoma cell line, potentially through the promotion of radiation-induced apoptosis and adjusting the cell cycle to a more radiosensitive stage. Immunofluorescence data revealed an increasing quantity of ${gamma}$-H2AX foci and decreasing radiation-induced DNA damage repair following knockdown of C23. To further clarify the mechanism of C23 in DNA DSBs repair, we detected the expression of DNA-PKcs and C23 proteins in NSCLC cell lines. C23 might participate in DNA DSBs repair for the reason that the expression of DNA-PKcs decreased at 30, 60, 120 and 360 minutes after irradiation in C23 knockdown cells. Especially, the activity of DNA-PKcs phosphorylation sites at the S2056 and T2609 was significantly suppressed. Therefore we concluded that C23 knockdown can inhibit DNA-PKcs phosphorylation activity at the S2056 and T2609 sites, thus reducing the radiation damage repair and increasing the radiosensitivity of NSCLC cells. Taken together, the inhibition of C23 expression was shown to increase the radiosensitivity of NSCLC cells, as implied by the relevance to the notably decreased DNA-PKcs phosphorylation activity at the S2056 and T2609 clusters. Further research on targeted C23 treatment may promote effectiveness of radiotherapy and provide new targets for NSCLC patients.

• Radiation Oncology Journal
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• 제38권2호
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• pp.99-108
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• 2020

Purpose: The probability of recurrence of cancer after adjuvant or definitive radiotherapy in patients with human papillomavirus-negative (HPV(-)) head and neck squamous cell carcinoma (HNSCC) varies for each patient. This study aimed to identify and validate radiation sensitivity signature (RSS) of patients with HPV(-) HNSCC to predict the recurrence of cancer after radiotherapy. Materials and Methods: Clonogenic survival assays were performed to assess radiosensitivity in 14 HNSCC cell lines. We identified genes closely correlated with radiosensitivity and validated them in The Cancer Genome Atlas (TCGA) cohort. The validated RSS were analyzed by ingenuity pathway analysis (IPA) to identify canonical pathways, upstream regulators, diseases and functions, and gene networks related to radiosensitive genes in HPV(-) HNSCC. Results: The survival fraction of 14 HNSCC cell lines after exposure to 2 Gy of radiation ranged from 48% to 72%. Six genes were positively correlated and 35 genes were negatively correlated with radioresistance, respectively. RSS was validated in the HPV(-) TCGA HNSCC cohort (n = 203), and recurrence-free survival (RFS) rate was found to be significantly lower in the radioresistant group than in the radiosensitive group (p = 0.035). Cell death and survival, cell-to-cell signaling, and cellular movement were significantly enriched in RSS, and RSSs were highly correlated with each other. Conclusion: We derived a HPV(-) HNSCC-specific RSS and validated it in an independent cohort. The outcome of adjuvant or definitive radiotherapy in HPV(-) patients with HNSCC can be predicted by analyzing their RSS, which might help in establishing a personalized therapeutic plan.

• Journal of Radiation Protection and Research
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• 제44권1호
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• pp.15-25
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• 2019

Background: Psammaplin A (PsA) is a radiosensitizer whereas its clinical application is hampered by poor bioavailability. This study aimed to synthesize novel radiosensitizers using PsA as the lead compound. Materials and Methods: Eight homodimeric disulfides were synthesized from corresponding acid and cystamine dihydrochloride in N-hydroxysuccinimide and dicyclohexylcarbodiimide coupling conditions. One monomeric thiol analog was obtained by reduction of homodimeric disulfide with dithiothreitol. Clonogenic assay was used to measure cell survival after irradiation and drug treatment in human lung cancer (A549) and glioblastoma (U373MG) cells. Results and Discussion: Using the PsA backbone, nine compounds were synthesized. Eight compounds showed variable cytotoxicity with 50% inhibitory concentrations ranging $16.14{\mu}M$ to $150.10{\mu}M$ (A549), and $13.25{\mu}M$ to $50.15{\mu}M$ (U373MG). Four and six compounds radiosensitized A549 and U373MG cells, respectively. Two compounds that radiosensitized both cell lines were tested for its inhibitory effects on DNMT1. One of them was shown to significantly inhibit DNMT1 activity. Conclusion: Novel compounds with radiosensitizing activity were synthesized. These compounds have a great potential to serve as a basis for the development of future radiosensitizers. Further investigation is warranted for their clinical application.