Histone deacetylase inhibition decreases proliferation and potentiates the effect of ionizing radiation in atypical teratoid/rhabdoid tumor cells

Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant central nervous system neoplasm that primarily occurs in children less than 3 years of age. Because of poor outcomes with intense and toxic multimodality treatment, new therapies are urgently needed. Histone deacetylase inhibitors (HDIs) have been evaluated as novel agents for multiple malignancies and have been shown to function as radiosensitizers. They act as epigenetic modifiers and lead to re-expression of inappropriately repressed genes, proteins, and cellular functions. Because of the underlying chromatin remodeling gene mutation in ATRT, HDIs are ideal candidates for therapeutic evaluation. To evaluate the role of HDIs against ATRT in vitro, we assessed the effect of drug treatment on proliferation, apoptosis, and gene expression. In addition, we examined HDI pretreatment as a radiosensitization strategy for ATRT. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium with phenazine methosulfate electron coupling reagent (MTS) and clonogenic assays demonstrated that HDI treatment significantly reduces the proliferative capacity of BT-12 and BT-16 ATRT cells. In addition, the HDI SNDX-275 was able to induce apoptosis in both cell lines and induced p21(Waf1/Cip1) protein expression as measured by Western blot. Evaluation of differential gene expression by microarray and pathway analysis after HDI treatment demonstrated alterations of several key ATRT cellular functions. Finally, we showed that HDI pretreatment effectively potentiates the effect of ionizing radiation on ATRT cells as measured by clonogenic assay. Our findings suggest that the addition of HDIs to ATRT therapy may prove to be beneficial, especially when administered in combination with current treatment modalities, such as radiation.     

WEE1 kinase inhibitor MK-1775 sensitizes oral tongue squamous cell carcinoma cells to radiation irrespective of TP53 status

Objective

Oral tongue squamous cell carcinoma (OTSCC) frequently harbors non-functional p53 and depends on G2/M checkpoint mediated by WEE1. WEE1 suppression has been identified as a promising anti-tumor strategy. This study investigated the capacity of WEE1 kinase inhibitor (MK-1775) and its underlying mechanisms in enhancing radiation responses of OTSCC cells in vitro.

Materials and methods

WEE1 kinase expression and its downstream target (CDK1) were investigated in OTSCC versus normal oral tissue. A synergistic combination of MK-1775 with radiation on OTSCC cell lines with different p53 statuses was assessed by viability assay. The radio-sensitizing effects of MK-1775 on apoptosis, cell cycle, DNA damage, and mitotic entry were also determined.

Results

Irradiation enhanced CDK1 expression in all tested cell lines, though the effect was far more pronounced in p53 mutated cell lines. MK-1775 exhibited inhibitory effects against the survival of all cell lines and enhanced their response to the radiation. These effects were strongly elicited by induction of apoptosis and lethal mitosis, but less likely by abrogation of radiation-induced G2 arrest.

Conclusion

These results demonstrate the efficacy of MK-1775 in enhancing the radiation effect on OTSCC in vitro associated with a significant apoptotic death rate, identifying WEE1 inhibitor as a potent radiosensitizer in OTSCC irrespective of p53 mutational status.     

叶酸修饰埃洛石纳米管负载姜黄素对乳腺癌细胞及移植瘤的放射增敏作用

目的:探究叶酸修饰埃洛石纳米管负载姜黄素（HNTs-PEG-FA/Cur）对乳腺癌MCF-7细胞及4T1荷瘤鼠的靶向放射增敏作用。方法:用化学改性和物理吸附的方法合成纳米放疗增敏药物HNTs-PEG-FA/Cur,采用透射电子显微镜、傅里叶红外光谱仪和X射线光电子能谱仪进行形貌和化学组分表征,MTT法检测不同浓度纳米药物对人乳腺癌MCF-7细胞活性的影响,流式细胞术、活/死细胞荧光染色和克隆形成实验评估HNTs-PEG-FA/Cur联合放疗对MCF-7细胞的促凋亡作用和放射增敏作用。最后,通过建立乳腺癌4T1细胞小鼠移植瘤模型,评估联合治疗对小鼠肿瘤体积生长的抑制效果。结果:成功将姜黄素负载于叶酸修饰的HNTs管腔内。所制备的HNTs-PEG-FA/Cur在等效姜黄素浓度为5 μmol/L时对MCF-7细胞无明显毒性,并能有效增强X射线诱导的细胞凋亡和杀伤作用（增敏比为1.25）。体内抑瘤实验结果显示HNTs-PEG-FA/Cur联合放疗对小鼠肿瘤生长抑制率（56.75%）>单独射线组（24.16%）>单独药物组（6.67%）。结论:HNTs-PEG-FA作为姜黄素的新型纳米药物载体,能有效提高姜黄素生物利用度并且对乳腺癌具有靶向放射增敏潜力。     

鼻咽清颗粒对鼻咽癌细胞裸鼠移植瘤的放疗增敏作用及机制研究

目的 体内考察鼻咽清颗粒对人鼻咽癌细胞（CNE-2）裸鼠种植瘤的放疗增敏作用并对其可能机制进行初步探索。方法 建立CNE-2细胞的裸鼠种植瘤模型,取荷瘤成功裸鼠30只,随机分成5组,分别为模型组,鼻咽清颗粒低、高剂量（生药剂量5.2、10.4 g/kg）组,放疗组,鼻咽清颗粒（生药剂量5.2 g/kg）+放疗组,每天2次ig给药;放疗照射剂量为4 GY,隔日1次,连续2周。给药期间每5天测量肿瘤体积,至给药30 d处死,取瘤组织,称质量并计算抑瘤率;免疫组化检测P53、Bcl-2蛋白表达。结果 与模型组比较,各治疗组均对移植瘤体积、质量发挥显著抑制作用（P<0.05、0.01）;鼻咽清颗粒+放疗组瘤体积、质量均显著低于放疗组（P<0.05、0.01）。免疫组化结果提示,与模型组比较,各治疗组移植瘤组织中P53、Bcl-2蛋白表达阳性细胞率均显著降低（P<0.05、0.01）;与放疗组比较,鼻咽清颗粒+放疗组P53、Bcl-2蛋白表达阳性细胞率显著降低（P<0.01）。结论 鼻咽清颗粒抑制鼻咽癌的生长且具有放疗增敏作用,可能与同时抑制突变性P53和Bcl-2蛋白表达相关。     

冬凌草甲素对肝癌HepG2细胞株体外放射增敏作用

目的观察冬凌草甲素对肝癌细胞株体外的放射增敏作用。方法对肝癌细胞系（HepG2）进行克隆形成实验。照射前用1.804、3.608、5.412、7.216、18.040μmol/L冬凌草甲素处理HepG2细胞6～72h,然后分别给予0、1、2、3、4、5、6Gy的^60Co照射,观察细胞存活率,计算放射增敏比（SER）。并运用常规照射剂量2Gy时的放射增敏比（SERSF2）作为评价指标。结果冬凌草甲素可提高HepG2细胞的放射敏感性,并呈时间、浓度依赖关系。照射前用1.804μmol/L冬凌草甲素处理HepG2细胞6～72h,在6、12和24h未观察到放射增敏作用,放射增敏作用仅在48和72h出现。当高浓度冬凌草甲素（18.040μmol/L）处理HepG2细胞6、12和24h,各时间点均可见放射增敏效应。结论冬凌草甲素可能是一种肝癌放射增敏剂。     

石上柏联合放疗治疗鼻咽癌临床观察

目的 观察中药石上柏对晚期鼻咽癌的放射增敏作用。方法 选择180例鼻咽癌患者随机分为A、B、C三组：A组患者仅接受单纯放疗；B组从放疗第1天开始，每日用石上柏30g煎水50ml口服，至放疗结束；C组在疗程的后半段开始服用石上柏。结果 B组或C组鼻咽原发灶的完全缓解率（CR）高于A组（P〈0．05）；B组或C组颈淋巴结CR率高于A组（P〈0．05）。B、C组的急性放射反应较A组轻，但差异无统计学意义。结论 石上柏可能对晚期鼻咽癌有一定的放射增敏作用，并且不会增加正常组织的急性放射反应。     

Anginex synergizes with radiation therapy to inhibit tumor growth by radiosensitizing endothelial cells

We have demonstrated that the designed peptide anginex displays potent antiangiogenic activity. The aim of our study was to investigate the effect of anginex on established tumor vasculature as an adjuvant to radiation therapy of solid tumors. In the MA148 human ovarian carcinoma athymic mouse model, anginex (10 mg/kg) in combination with a suboptimal dose of radiation (5 Gy once weekly for 4 weeks) caused tumors to regress to an impalpable state. In the more aggressive SCK murine mammary carcinoma model, combination of anginex and a single radiation dose of 25 Gy synergistically increased the delay in tumor growth compared to the tumor growth delay caused by either treatment alone. Immunohistochemical analysis also demonstrated significantly enhanced effects of combined treatment on tumor microvessel density and tumor or endothelial cell proliferation and viability. In assessing physiologic effects of anginex, we observed a reduction in tumor perfusion and tumor oxygenation in SCK tumors after 5-7 daily treatments with anginex with no reduction in blood pressure. To test anginex as a radiosensitizer, additional studies using SCK tumors were performed. Three daily i.p. injections of anginex were able to enhance the effect of 2 radiation doses of 10 Gy, resulting in 50% complete responses, whereas the known antiangiogenic agent angiostatin did not enhance the radiation response of SCK tumors. Mechanistically, it appears that anginex functions as an endothelial cell-specific radiosensitizer because anginex showed no effect on in vitro radiosensitivity of SCK or MA148 tumor cells, whereas anginex significantly enhanced the in vitro radiosensitivity of 2 endothelial cell types. This work supports the idea that the combination of the antiangiogenic agent anginex and radiation may lead to improved clinical outcome in treating cancer patients.     

二甲双胍在恶性肿瘤放疗中的应用研究进展

二甲双胍(C4H11N5)是治疗2型糖尿病的主要药物.有研究显示,二甲双胍可以抑制肿瘤生长,改善恶性肿瘤患者的预后.近年越来越多的研究发现,二甲双胍可以改善肿瘤细胞的放疗敏感性.然而,二甲双胍增强恶性肿瘤放疗敏感性的具体机制尚未完全阐明.本研究将对有关二甲双胍联合放疗应用的最新发现进行综述,并着重介绍其在不同肿瘤中的疗...     

丁胱亚磺酰亚胺对Acc—2移植瘤放射增敏的实验研究

目的在体内研究放射增敏剂丁胱亚磺酰亚胺（ｂｕｔｈｉｏｎｉｎｅｓｕｌｆｏｘｉｍｉｎｅ,ＢＳＯ）对Ａｃｃ－２移植瘤的放射增敏作用。方法以Ａｃｃ－２移植瘤为模型,实验设对照组、ＢＳＯ组、单放组和ＢＳＯ＋放射组。ＢＳＯ药物剂量为５ｍｍｏｌ／ｋｇ,放射剂量为１０Ｇｙ。结果各组与对照组比较,ＢＳＯ组抑瘤率为８．５％、单放组为１２．６％,ＢＳＯ＋放射组为４５．３７％。结论ＢＳＯ对Ａｃｃ－２移植瘤有放射增敏作用。