低剂量率照射下肿瘤细胞抑癌基因表达和细胞凋亡研究进展

低剂量率照射能够增强p53、p21等抑癌基因的表达,并可通过肿瘤细胞G2-M期阻滞和bcl-2等基因的改变引起细胞凋亡,从而达到治疗肿瘤的目的.     

低剂量率照射下肿瘤细胞抑癌基因表达和细胞凋亡研究进展

低剂量率照射能够增强p53、p21等抑癌基因的表达,并可通过肿瘤细胞G2-M期阻滞和bcl-2等基因的改变引起细胞凋亡,从而达到治疗肿瘤的目的.     

冷冻治疗抑制大鼠C6脑胶质瘤增殖的实验研究

目的：研究冷冻治疗对大鼠C6脑胶质瘤的增殖抑制作用及其机制。方法：建立大鼠C6脑胶质瘤模型，冷冻治疗后免疫组化检测CyclinD1蛋白的表达，流式细胞仪检测细胞周期的变化，磁共振检测肿瘤体积变化。结果：与对照组比较，冷冻治疗后CyclinD1蛋白的表达下调，细胞周期出现G1期阻滞，肿瘤体积缩小。结论：冷冻治疗可抑制大鼠C6脑胶质瘤的增殖，其机制与下调CyclinD1蛋白的表达后，肿瘤细胞周期发生G1期阻滞有关。     

低剂量辐射对肿瘤细胞凋亡、细胞周期以及凋亡相关蛋白Bcl-2的影响

目的探讨低剂量辐射对小鼠移植肿瘤细胞的凋亡、细胞周期以及Bcl-2的影响。方法昆明种雄性小鼠左后肢腹股沟皮下接种S180肉瘤细胞,接种后7天γ射线全身照射75mGy,照射后24、48小时分别处死直接测量肿瘤大小变化,取肿瘤组织分别进行流式细胞仪分析凋亡、细胞周期以及免疫组化染色半定量分析凋亡相关蛋白Bcl-2表达的变化。结果与直接荷瘤组相比,低剂量照射组肿瘤生长缓慢(P<0.05),24小时后肿瘤细胞阻滞于G1期,Bcl-2蛋白表达下降,48小时后肿瘤细胞凋亡增加(P<0.001)。结论低剂量辐射可使机体肿瘤细胞阻滞于G1期并通过凋亡相关蛋白表达变化导致肿瘤细胞凋亡增加,明显提高机体抗肿瘤的作用,具有肿瘤治疗和辅助放化疗的实际临床意义。     

低剂量辐射对肿瘤细胞凋亡、细胞周期以及凋亡相关蛋白 Bcl-2的影响(英文)

目的探讨低剂量辐射对小鼠移植肿瘤细胞的凋亡、细胞周期以及 Bcl-2的影响。方法昆明种雄性小鼠左后肢腹股沟皮下接种 S180肉瘤细胞,接种后7天γ射线全身照射75mGy,照射后24、48小时分别处死直接测量肿瘤大小变化,取肿瘤组织分别进行流式细胞仪分析凋亡、细胞周期以及免疫组化染色半定量分析凋亡相关蛋白 Bcl-2表达的变化。结果与直接荷瘤组相比,低剂量照射组肿瘤生长缓慢(P<0.05),24小时后肿瘤细胞阻滞于 G1期,Bcl-2蛋白表达下降,48小时后肿瘤细胞凋亡增加(P<0.001)。结论低剂量辐射可使机体肿瘤细胞阻滞于 G1期并通过凋亡相关蛋白表达变化导致肿瘤细胞凋亡增加,明显提高机体抗肿瘤的作用,具有肿瘤治疗和辅助放化疗的实际临床意义。     

全反式维甲酸提高人结肠癌细胞亚株SW480/M5对奥沙利铂敏感性

目的探讨全反式维甲酸(all-trans retinoic acid,ATRA)提高人结肠癌细胞亚株SW480/M5对奥沙利铂(oxaliplatin,L-OHP)敏感性的可能机制.方法 MTT法筛选ATRA和L-OHP实验浓度.流式细胞仪检测ATRA对肿瘤细胞周期影响.分别用ATRA、L-OHP、ATRA联合L-OHP作用SW480/M5细胞,MTT法检测药物对肿瘤细胞抑制率,流式细胞仪检测肿瘤细胞周期及凋亡率,原子光谱吸收仪检测肿瘤细胞DNA含铂(Pt)量. 结果L-OHP抑制SW480/M5细胞增殖的GI50为58.0mg/L,主要阻滞肿瘤细胞在S和G2/M期.ATRA 8.0μmol/L作用24小时后,G1期细胞减少,S期细胞增多;作用72小时后,S期和G2/M期细胞增加并明显抑制肿瘤细胞增殖.8.0μmol/LATRA作用至48小时后联合L-OHP,两药联合由相加作用转变为协同作用;联合用药后S期和G2/M期细胞明显增多,细胞DNA含Pt量显著增加,呈时效依赖性.相对于单独用药,联合用药并不上调肿瘤细胞凋亡率.结论ATRA通过改变SW480/M5细胞周期和提高细胞DNA含Pt量,明显增加肿瘤细胞对L-OHP敏感性.     

辐射诱发肿瘤细胞增殖抑制和凋亡的相关研究

目的 探讨不同辐射敏感性的肿瘤细胞受照后G2/M期阻滞和凋亡发生的关系。为提高肿瘤放射治疗效果提供理论依据。方法 以人早幼粒白血病细胞株HL-60、人T淋巴细胞性白血病细胞系CEM和人红白血病细胞系K562细胞为对象，采用形态学观察、DNA琼脂糖凝胶电泳和流式细胞仪等方法检测细胞周期的改变和凋亡的发生。结果 辐射敏感的HL-60和CEM细胞受照后首先发生G2/M期阻滞，然后在阻滞退出过程中或之后发生凋亡；辐射耐受的K562细胞受照后只发生G2/M期阻滞，不发生凋亡；照射并加入咖啡因（CAF），抑制3种细胞的G2/M期阻滞，促进凋亡；照射并加入佛波酯（TPA），增加HL-60和CEM细胞的G2/M期阻滞，抑制凋。结论 辐射诱发肿瘤细胞的凋亡与G2/M期阻滞有关，用药物调控G2/M期阻滞可影响辐射所致的凋亡。     

阿糖胞苷及云南霉素的细胞周期阻滞作用研究

目的:阿糖胞苷(cytosinearabi-noside)及其核苷类似物是治疗血液肿瘤的重要药物。研究阿糖胞苷诱导肿瘤细胞的周期阻滞和凋亡,并探讨其相关的机制。方法:本研究使用流式细胞仪检测细胞周期改变及凋亡的诱导;用Westernblot分析肿瘤细胞凋亡和增殖相关蛋白的表达改变。结果:阿糖胞苷诱导KB细胞和HL-60细胞阻滞在G1期,而其胞嘧啶类似物云南霉素将细胞阻滞在G2/M期,但两者最终都诱导细胞凋亡。阿糖胞苷和云南霉素诱导细胞凋亡都伴有c-myc蛋白表达水平下降,阿糖胞苷作用KB细胞后,可观察到p53蛋白和Fas蛋白水平逐渐增高。结论:阿糖胞苷及其胞嘧啶类似物云南霉素诱导不同的细胞周期阻滞。阿糖胞苷诱导细胞凋亡可以通过p53/Fas蛋白依赖和非依赖两条途径来实现。     

ZD1839治疗头颈部肿瘤研究进展

头颈部肿瘤多过度表达表皮生长因子受体（EGFR）。EGFR酪氨酸激酶抑制剂ZD1839可阻断EGFR介导的信号转导途径，进而抑制肿瘤细胞增殖，将肿瘤细胞阻滞在G1期，促进肿瘤细胞凋亡并抑制血管生成，与放化疗联合应用具有协同抗肿瘤作用，可用于头颈部肿瘤的治疗。现综述ZD1839治疗头颈部肿瘤的研究进展。     

抗癌灵治疗原发性肝癌的实验研究

 目的　观察抗癌灵水煎剂对小鼠移植性肝癌 (H2 2 )的治疗作用。方法　以瘤株 (H2 2 )接种小鼠创作模型 ,设正常对照组、荷瘤模型组及抗癌灵治疗组 ,共 3组 ,观察各组小鼠瘤重和抑瘤率、肿瘤坏死因子(TNF)的体内活性表达、各组H2 2 小鼠生命延长率以及对肝癌细胞增殖周期的影响等指标。结果　用抗癌灵治疗后的H2 2 小鼠其抑瘤率达 61 .2 0 % ,明显高于模型组 (P <0 .0 1 ) ,并能抑制荷瘤肌体TNF水平的异常表达 ,提高H2 2 荷瘤小鼠的生命延长率 ,而且该药还能阻滞肿瘤细胞周期G1期向S期进展 ,从而阻断DNA的合成和复制。结论　抗癌灵对小鼠肝癌 (H2 2 )具有明显的杀伤作用     

Stromal–epithelial interactions modulate cross-talk between prolactin receptor and HER2/Neu in breast cancer

Prolactin (PRL) promotes the proliferation and survival of breast cancer cells in part via the transactivation of human epidermal growth factor receptor 2 (HER2), also known as Neu in rodents. A PRL receptor (PRLR) antagonist, G129R, has been developed, which indirectly inhibits the tyrosine phosphorylation of HER2 (p-HER2) in human breast cancer cell lines. In this study, we investigate the effects of cancer-associated fibroblasts (CAFs) upon this molecular cross-talk using tumor cells and CAFs derived from spontaneous mammary tumors of female MMTV-neu transgenic mice. Tumors were resected and cultured as small tumor chunks (~3 mm3) or were cultured in monolayer. G129R reduced tyrosine phosphorylation of Neu (p-Neu) in a dose-dependent manner (IC50~10 μg/ml) in tumor chunks, but had no effect on primary tumor epithelial cells grown in monolayer. Direct co-culture of mouse or human tumor epithelial cell lines with CAFs restored the epithelial cells' response to G129R, similar to that observed in mouse tumor chunks. The addition of PRL, as expected, induced p-Neu in both the tumor chunk and co-culture models. The inhibitory effect of G129R was absent when CAFs were physically separated from mouse tumor epithelial cells using a transwell system, or when CAFs were replaced with normal fibroblasts in direct co-culture with human or mouse tumor epithelial cells. In vivo, G129R reduced p-Neu levels in primary mammary tumors of mice in a time- and dose-dependent manner. In conclusion, CAFs play a critical role in bridging the cross-talk between PRL and HER2/Neu in both mouse and human models of breast cancer. The inhibitory effects of G129R on p-Neu and on tumor growth are dependent upon interactions of tumor epithelial cells with CAFs.     

UCN-01-mediated G1 arrest in normal but not tumor breast cells is pRb-dependent and p53-independent

In this study we investigated the growth inhibitory effects of UCN-01 in several normal and tumor-derived human breast epithelial cells. We found that while normal mammary epithelial cells w were very sensitive to UCN-01 with an IC(50) of 10nM tumor cells displayed little to no inhibition of growth with any measurable IC(50) at low UCN-01 concentrations (i.e. 0-80 nM). The UCN-01 treated normal cells arrested in G1 phase and displayed decreased expression of most key cell cycle regulators examined, resulting in inhibition of CDK2 activity due to increased binding of p27 to CDK2. Tumor cells on the other hand displayed no change in any cell cycle distribution or expression of cell cycle regulators. Examination of E6- and E7-derived strains of normal cells revealed that pRb and not p53 function is essential for UCN-01-mediated G1 arrest. Lastly, treatment of normal and tumor cells with high doses of UCN-01 (i.e. 300 nM) revealed a necessary role for a functional G1 checkpoint in mediating growth arrest. Normal cells, which have a functional G1 checkpoint, always arrest in G1 even at very high concentrations of UCN-01. Tumor cells on the other hand have a defective G1 checkpoint and only arrest in S phase with high concentrations of UCN-01. The effect of UCN-01 on the cell cycle is thus quite different from staurosporine, a structural analogue of UCN-01, which arrests normal cells in both G1 and G2, while tumor cells arrest only in the G2 phase of the cell cycle. Our results show the different sensitivity to UCN-01 of normal compared to tumor cells is dependent on a functional pRb and a regulated G1 checkpoint.     

石蒜碱调控G3BP1/TGF-β/Smad信号通路抑制食管癌细胞增殖

目的:探讨石蒜碱对食管癌细胞增殖的影响,并分析其机制。方法:细胞计数8（cell counting kit-8,CCK-8）法分析细胞增殖抑制率,Western blot法分析GTP酶激活蛋白-Src同源结构域3-结合蛋白1［GTPase activating protein（SH3 domain)binding protein 1,G3BP1］、转化生长因子-β1(transforming growth factor-β1,TGF-β1)、p-Smad2/Smad2、p-Smad3/Smad3水平。敲低或过表达G3BP1,观察其对细胞增殖抑制率以及G3BP1、TGF-β1、p-Smad2/Smad2水平的影响。裸鼠成瘤实验验证石蒜碱对裸鼠体内瘤体的瘤重、瘤体积及G3BP1、TGF-β1、p-Smad2/Smad2水平的影响。结果:2~64 μmol/L石蒜碱抑制ECA109细胞增殖,石蒜碱48 h IC50为（16.21±2.35）μmol/L。4、8、16 μmol/L的石蒜碱能下调G3BP1、TGF-β1、p-Smad2/Smad2、p-Smad3/Smad3的水平。敲低G3BP1的表达能明显提高石蒜碱对ECA109细胞增殖的抑制作用,促进石蒜碱降低G3BP1、TGF-β1、p-Smad2/Smad2水平（P＜0.05）;上调G3BP的表达能明显下调石蒜碱对ECA109细胞增殖的抑制作用,抑制石蒜碱降低G3BP1、TGF-β1、p-Smad2/Smad2水平（P＜0.05）。体内实验显示,与模型对照组比较,25、50、100 mg/kg石蒜碱能降低瘤体体积、瘤体质量,下调瘤体G3BP1、TGF-β1、p-Smad2/Smad2水平（P＜0.05）。结论:石蒜碱能抑制ECA109细胞的增殖,对裸鼠体内ECA109细胞移植瘤抑瘤效果明显,其机制与调控G3BP1/TGF-β/Smad 信号通路有关。     

The apoptosis-inducing effect of gastrin on colorectal cancer cells relates to an increased IEX-1 expression mediating NF-kappa B inhibition

Addressing the puzzling role of amidated gastrin(17) (G17) and the gastrin/CCKB/CCK2 receptor in colorectal carcinogenesis, we analysed potential candidate genes involved in G17-dependent NF-kappaB inhibition and apoptosis. The colorectal carcinoma cell line Colo320 overexpressing the wild-type CCK2 receptor (Colo320wt) underwent G17-induced apoptosis along with suppressed NF-kappaB activation and decreased expression of the antiapoptotic NF-kappaB target genes cIAP1 and cIAP2, whereas G17 was without effect on Colo320 cells expressing a CCK2 receptor bearing a loss of function mutation (Colo320mut). Gene microarray analysis revealed an elevated expression of the stress response gene IEX-1 in G17-treated Colo320wt but not Colo320mut cells. Quantitative real-time PCR and conventional RT-PCR confirmed this G17-dependent increase of IEX-1 expression in Colo320wt cells. If these cells were subjected to IEX-1 knockdown by small interfering RNA transfection, the apoptosis-inducing effect of G17 was abolished. Moreover, tumor necrosis factor alpha (TNFalpha)- or 5-FU-induced apoptosis that is greatly enhanced by G17 treatment in Colo320wt cells was prevented if IEX-1 expression was repressed. Under these conditions of blocked IEX-1 expression, the NF-kappaB activity remained unaffected by G17, in particular in Colo320wt cells co-treated with TNFalpha and also the suppressive effect of G17 on cIAP1 and cIAP2 expression was not observed anymore if IEX-1 expression was blocked. Conversely, IEX-1 overexpression in Colo320mut cells caused an increase of basal and TNFalpha- or 5-FU-induced apoptosis, an effect not further triggered by G17 treatment. Using a xenograft tumor model in severe combined immune deficiency mice, we could show that experimental systemic hypergastrinemia induced by the administration of omeprazole led to enhanced apoptosis as well as to a marked increase of IEX-1 expression in Colo320wt tumors, but not in Colo320mut tumors. These observations indicate that the proapoptotic effect of G17 on human colon cancer cells expressing the wild-type CCK2 receptor is mediated by IEX-1, which modulates NF-kappaB-dependent antiapoptotic protection and thereby exerts tumor-suppressive potential.     

Nuclear morphometry and DNA densitometry of human gliomas by image analysis

In 48 patients with gliomas in whom complete clinical follow-up was obtained, DNA ploidy was evaluated by using formalin-fixed paraffin-embedded tissues and by means of image analysis. The mean DNA indices, determined by averaging DNA indices of all tumor cells in a tumor, were mainly affected by mean DNA indices of the nuclei of SG2M phase tumor cell (including S phase and G2M phase cells) (SG2M DNA indices) and that mean DNA indices correlated with the SG2M phase fraction. The SG2M DNA indices and the percentage of tumor cells with S phase and G2M phase were higher in high grade gliomas including anaplastic glioma and glioblastoma multiforme than in low grade gliomas. Patients with G2M-hypertetraploid tumors demonstrated a shorter time to tumor progression than those with G2M-tetraploid in high grade glioma. Morphometrically, the nuclei of SG2M phase glioma cells were larger and more deformity than those of G0G1 phase (including G0 phase and G1 phase cells) cells. The G2M-hypertetraploid tumors were highly malignant and demonstrated large nuclei, greater nuclear deformity, and a higher proliferative potential. The G2M-tetraploid gliomas demonstrated a shorter time to tumor progression in cases whose the SG2M fraction was large. In contrast, G2M-hypotetraploid gliomas revealed an insignificant trend towards a longer time to tumor progression than those associated with tetraploid and hypertetraploid gliomas. We emphasize herein the prognostic importance of the SG2M phase cell, as well as other proliferation indices.     

A Selective Cyclooxygenase-2 Inhibitor Suppresses Tumor Growth in Nude Mouse Xenografted with Human Head and Neck Squamous Carcinoma Cells

The anti-tumor effect of a selective cyclooxygenase (COX)-2 inhibitor, JTE-522, was examined with the human head and neck squamous cell carcinoma cell line KB. KB cells do not produce prostaglandin (PG)-E2. In vitro , JTE-522 induced an increase of G1 phase-arrested cells, suppression of platelet-derived growth factor (PDGF) production and inhibition of telomerase activity. No cytotoxic effect was detected. In vivo , the growth of the tumor xenografted into nude mice was significantly suppressed by JTE-522. Suppression of angiogenesis at the periphery of the tumor, increase of G1-arrested cells and suppression of telomerase activity were observed, together with an increase of apoptotic cell death in the tumor. Immunological enhancement did not play a role. We concluded that the anti-tumor effect of JTE-522 was caused by anti-angiogenesis action, cell cycle arrest and inhibition of telomerase activity of the tumor cells. These combined effects might induce apoptosis.     

Classification of DNA histogram perturbed with 5-FU and its clinical application

Analysis of cell kinetics may be beneficial for evaluation of the therapeutic effect of anticancer agents. Therefore, using flow cytometry, the authors could classify perturbations of DNA histogram of cultured colon cancer cells treated with 5-FU into 4 types. Perturbation of DNA histogram of cancer cells treated with 5-FU of different concentrations was closely associated with the degree of cell damage indicated by the growth curve. Then, tumor samples before and after injection of 5-FU were collected from 9 preoperative patients with colon cancer and classified into the above 4 types. The results show that 2 cases were classified into type I (S/G1 ratio: 1.5 greater than, G1.G2M comparison: G1 greater than G2M) and another two into type IV (CV ratio: 1.5 less than or equal to, S/G1 ratio: 1.5 less than or equal to, G1.G2M comparison: G1 greater than G2M). However, 5 cases could not be classified (not evaluated) because of the absence of stemline and the presence of heterogeneity in tumor samples. The authors consider that the classification of perturbation of DNA histogram is a useful method to evaluate the degree of cell damage with 5-FU, if tumor samples are appropriately selected and analysis is made with careful attention.     

Carcinoembryonic antigen‐related cell adhesion molecule 1 negatively regulates granulocyte colony‐stimulating factor production by breast tumor‐associated macrophages that mediate tumor angiogenesis

Carcinoembryonic antigen‐related cell adhesion molecule 1 (CEACAM1), a cell adhesion molecule expressed on epithelial cells and activated immune cells, is downregulated in many cancers and plays a role in inhibition of inflammation in part by inhibition of granulocyte colony‐stimulating factor (G‐CSF) production by myeloid cells. As macrophages are associated with a poor prognosis in breast cancer, but play important roles in normal breast, we hypothesized that CEACAM1 downregulation would lead to tumor promotion under inflammatory conditions. Cocultures of proinflammatory M1 macrophages with CEACAM1 negative MCF7 breast cells produced high levels of G‐CSF (10 ng/mL) compared to CEACAM1‐transfected MCF7/4S cells (1 ng/mL) or anti‐inflammatory M2 macrophage cocultures (0.5 or 0.1 ng/mL, MCF7 or MCF7/4S, respectively). The expression of CEACAM1 on M1s was much greater than for M2s and was observed only in cocultures with either MCF7 or MCF7/4S cells. When M1 macrophages were mixed with MCF7 cells and implanted in murine mammary fat pads of nonobese diabetic/severe combined immunodeficient mice, tumor size and blood vessel density were significantly greater than MCF7 or MCF7/4S only tumors which were hardly detected after 8 weeks of growth. In contrast, M1 cells had a much reduced effect on MCF7/4S tumor growth and blood vessel density, indicating that the tumor inhibitory effect of CEACAM1 is most likely related to its anti‐inflammatory action on inflammatory macrophages. These results support our previous finding that CEACAM1 inhibits both G‐CSF production by myeloid cells and G‐CSF‐stimulated tumor angiogenesis.     

A selective cyclooxygenase-2 inhibitor suppresses tumor growth in nude mouse xenografted with human head and neck squamous carcinoma cells.

The anti-tumor effect of a selective cyclooxygenase (COX)-2 inhibitor, JTE-522, was examined with the human head and neck squamous cell carcinoma cell line KB. KB cells do not produce prostaglandin (PG)-E2. In vitro, JTE-522 induced an increase of G1 phase-arrested cells, suppression of platelet-derived growth factor (PDGF) production and inhibition of telomerase activity. No cytotoxic effect was detected. In vivo, the growth of the tumor xenografted into nude mice was significantly suppressed by JTE-522. Suppression of angiogenesis at the periphery of the tumor, increase of G1-arrested cells and suppression of telomerase activity were observed, together with an increase of apoptotic cell death in the tumor. Immunological enhancement did not play a role. We concluded that the anti-tumor effect of JTE-522 was caused by anti-angiogenesis action, cell cycle arrest and inhibition of telomerase activity of the tumor cells. These combined effects might induce apoptosis.