경화제의 화학적 구조에 따른 UV 경화형 2-EHA/n-BA 점착제의 접착특성

김호겸(Ho-Gyum Kim) 한국고분자학회 2015 폴리머 Vol.39 No.5

2-Ethylhexyl acrylate(2-EHA)와 n-butyl acrylate(n-BA)를 공단량체로 하는 UV 경화형 아크릴 점착제를 제조하고 이 때 두 단량체의 함량비와 경화제의 화학적 구조 및 농도가 최종 접착물성에 미치는 영향을 조사하였다. 경화제 농도가 0.1 wt%일 때 높은 초기접착력과 박리강도를 갖는 것으로 확인되었으며 이 후 농도가 증가할수록 접착물성이 감소하였다. 또한 diethylene glycol dimethacrylate(DEGDMA)와 poly(ethylene glycol)dimethacrylate (PEGDMA)와 같이 분자 내 부피가 큰 메틸기와 상대적으로 긴 에틸렌옥사이드 사슬을 가진 경화제가 첨가되었을때 경화 후에도 점착제의 사슬 유연성이 유지되어 높은 경화제 농도에서 기존의 1,6-hexanediol diacrylate(HDDA)를 첨가한 계에 비해 다소 높은 점착물성을 갖는 것으로 나타났다. 또한 유사한 분자 구조를 가졌으나 분자 내 반복단위의 길이가 다른 DEGDMA와 PEGDMA간의 접착물성의 차이는 미미한 것으로 확인되었다. Pressure sensitive adhesives (PSAs) based with 2-ethylhexyl acrylate (2-EHA), n-butyl acrylate (n-BA) and different crosslinking agents were prepared by UV radiation curing. The effect of chemical structure and amounts of crosslinking agent, and also mixing ratio of co-monomer on adhesion properties of PSAs were presented. The results showed that the improvement of tack and peel strength of PSAs with 0.1 wt% of crosslinking agent was observed without cohesive failure and decreased with a higher concentration of crosslinking agent. A more increase in adhesion properties for PSAs with poly(ethylene glycol)dimethacrylate (PEGDMA) and diethylene glycol dimethacrylate (DEGDMA) was also investigated, which may be due to sustaining the chain flexibility by longer ethylene oxide chain and bulky methyl group in molecular backbone of crosslinking agent during the crosslinking process. It can be also found that the effect of repeating unit chain length on the adhesion properties between DEGDMA and PEGDMA system was insignificant in spite of their similar chemical structure.

Sequence-Dependent Radiosensitization of Histone Deacetylase Inhibitors Trichostatin A and SK-7041

김진호,김일한,신진희,김학재,김인아 대한암학회 2013 Cancer Research and Treatment Vol.45 No.4

Purpose This preclinical study is to determine whether the capacity of histone deacetylase (HDAC) inhibitors to enhance radiation response depends on temporal sequences of HDAC inhibition and irradiation. Materials and Methods The effects of HDAC inhibitors trichostatin A (TSA) and SK-7041 on radiosensitivity in human lung cancer cells were examined using a clonogenic assay, exposing cells to HDAC inhibitors in various sequences of HDAC inhibition and radiation. We performed Western blot of acetylated histone H3 and flow cytometry to analyze cell cycle phase distribution. Results TSA and SK-7041 augmented radiation cell lethality in an exposure time-dependent manner when delivered before irradiation. The impact of TSA and SK-7041 on radiosensitivity rapidly diminished when HDAC inhibition was delayed after irradiation. Radiation induced the acetylation of histone H3 in cells exposed to TSA, while irradiation alone had no effect on the expression of acetylated histone H3 in TSA-naïve cells. Preirradiation exposure to TSA abrogated radiation-induced G2/M-phase arrest. When delivered after irradiation, TSA had no effect on the peak of radiation-induced G2/M-phase arrest. Conclusion TSA and SK-7041 enhances radiosensitivity only when delivered before irradiation. Unless proven otherwise, it seems prudent to apply scheduling including preirradiation HDAC inhibition so that maximal radiosensitization is obtained.

Delphinidin enhances radio-therapeutic effects via autophagy induction and JNK/MAPK pathway activation in non-small cell lung cancer

Seong Hee Kang,Dong-Ho Bak,Byung Yeoup Chung,Hyoung-Woo Bai,Bo Sun Kang 대한생리학회-대한약리학회 2020 The Korean Journal of Physiology & Pharmacology Vol.24 No.5

Delphinidin is a major anthocyanidin compound found in various vegetables and fruits. It has anti-oxidant, anti-inflammatory, and various other biological activities. In this study we demonstrated the anti-cancer activity of delphinidin, which was related to autophagy, in radiation-exposed non-small cell lung cancer (NSCLC). Radiosensitising effects were assessed in vitro by treating cells with a subcytotoxic dose of delphinidin (5 μM) before exposure to γ-ionising radiation (IR). We found that treatment with delphinidin or IR induced NSCLC cell death in vitro; however the combination of delphinidin pre-treatment and IR was more effective than either agent alone, yielding a radiation enhancement ratio of 1.54 at the 50% lethal dose. Moreover, combined treatment with delphinidin and IR, enhanced apoptotic cell death, suppressed the mTOR pathway, and activated the JNK/MAPK pathway. Delphinidin inhibited the phosphorylation of PI3K, AKT, and mTOR, and increased the expression of autophagy-induced cell death associated-protein in radiation-exposed NSCLC cells. In addition, JNK phosphorylation was upregulated by delphinidin pre-treatment in radiation-exposed NSCLC cells. Collectively, these results show that delphinidin acts as a radiation-sensitizing agent through autophagy induction and JNK/MAPK pathway activation, thus enhancing apoptotic cell death in NSCLC cells.

Caffeic Acid Phenethyl Ester Increases Radiosensitivity of Estrogen Receptor- Positive and -Negative Breast Cancer Cells by Prolonging Radiation-Induced DNA Damage

Nastaran Masoudi Khoram,Bahareh Bigdeli,Alireza Nikoofar,Bahram Goliaei 한국유방암학회 2016 Journal of breast cancer Vol.19 No.1

Purpose: Breast cancer is an important cause of death among women. The development of radioresistance in breast cancer leads to recurrence after radiotherapy. Caffeic acid phenethyl ester (CAPE), a polyphenolic compound of honeybee propolis, is known to have anticancer properties. In this study, we examined whether CAPE enhanced the radiation sensitivity of MDAMB- 231 (estrogen receptor-negative) and T47D (estrogen receptor- positive) cell lines. Methods: The cytotoxic effect of CAPE on MDA-MB-231 and T47D breast cancer cells was evaluated by performing an 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. To assess clonogenic ability, MDAMB- 231 and T47D cells were treated with CAPE (1 μM) for 72 hours before irradiation, and then, a colony assay was performed. A comet assay was used to determine the number of DNA strand breaks at four different times. Results: CAPE decreased the viability of both cell lines in a dose- and time-dependent manner. In the clonogenic assay, pretreatment of cells with CAPE before irradiation significantly reduced the surviving fraction of MDA-MB-231 cells at doses of 6 and 8 Gy. A reduction in the surviving fraction of T47D cells was observed relative to MDA-MB-231 at lower doses of radiation. Additionally, CAPE maintained radiation-induced DNA damage in T47D cells for a longer period than in MDA-MB-231 cells. Conclusion: Our results indicate that CAPE impairs DNA damage repair immediately after irradiation. The induction of radiosensitivity by CAPE in radioresistant breast cancer cells may be caused by prolonged DNA damage.

Tumor Growth Suppression and Enhanced Radioresponse by an Exogenous Epidermal Growth Factor in Mouse Xenograft Models with A431 Cells

임유진,전상록,고재문,우홍균 대한암학회 2015 Cancer Research and Treatment Vol.47 No.4

Purpose The purpose of this study was to evaluate whether an exogenous epidermal growth factor(EGF) could induce anti-tumor and radiosensitizing effects in vivo. Materials and MethodsBALB/c-nu mice that were inoculated with A431 (human squamous cell carcinoma) cellsin the right hind legs were divided into five groups: I (no treatment), II (EGF for 6 days), III(EGF for 20 days), IV (radiotherapy [RT]), and V (RT plus concomitant EGF). EGF was administeredintraperitoneally (5 mg/kg) once a day and the RT dose was 30 Gy in six fractions. Hematoxylin and eosin (H&E) stained sections of tumor, liver, lung, and kidney tissues wereinvestigated. Additionally, tumors were subjected to immunohistochemistry staining withcaspase-3. ResultsEGF for 6 days decreased tumor volume, but it approached the level of the control group atthe end of follow-up (p=0.550). The duration of tumor shrinkage was prolonged in group Vwhile the slope of tumor re-growth phase was steeper in group IV (p=0.034). EGF for 20days decreased tumor volume until the end of the observation period (p < 0.001). Immunohistochemistryrevealed that mice in group V showed stronger intensity than those in groupIV. There were no abnormal histological findings upon H&E staining of the normal organs. ConclusionEGF-induced anti-tumor effect was ascertained in the xenograft mouse models with A431cells. Concomitant use of EGF has the potential role as a radiosensitizer in the design offractionated irradiation.

누드마우스에 이종이식된 인형 구강편평세포암에서 방사선치료와선택적 Cyclooxygenase-2 억제제 병합치료의 효과

김준희,박성윤,김희종,김기범,양훈식,이규석,이호진,지영훈 대한이비인후과학회 2006 대한이비인후과학회지 두경부외과학 Vol.49 No.4