Epigenetic modification regulates both expression of tumor-associated genes and cell cycle progressing in human colon cancer cell lines: Colo-320 and SW1116

The aim of this study is to assess the effects of DNA methylation and historic acetylation, alone or in combination, on the expression of several tumor-associated genes and cell cycle progression in two established human colon cancer cell lines: Colo-320 and SW1116. Treatments with 5-aza-2'-deoxycytidine (5-aza-dC) and trichostatin A, alone or in combination, were applied respectively. The methylation status of the CDKN2A promoter was determined by methyla-tion-specific PCR, and the acetylated status of the histones associated with the p21WAF1 and CDKN2A genes was examined by chromatin immunoprecipitation. The expression of the CDKN2A, p21WAF1, p53, p73, APC, c-myc, c-Ki-ras and survivin genes was detected by real-time RT-PCR and RT-PCR. The cell cycle profile was established by flow cytometry. We found that along with the demethylation of the CDKN2A gene promoter in both cell lines induced by 5-aza-dC alone or in combination with TSA, the expression of both CDKN2A and APC genes increased. The treatment of TSA or sodium butyrate up-regulated the transcription of p21WAF1 significantly by inducing the acetylation of histones H4 and H3, but failed to alter the acetylation level of CDKN2A-associated histones. No changes in transcription of p53, p73, c-myc, c-Ki-ras and survivin genes were observed. In addition, TSA or sodium butyrate was shown to arrest cells at the G1 phase. However, 5-aza-dC was not able to affect the cell cycle progression. In conclusion, regulation by epigenetic modification of the transcription of tumor-associated genes and the cell cycle progression in both human colon cancer cell lines Colo-320 and SW1116 is gene-specific.

Radiosensitivity of human colon cancer cell enhanced by immunoliposomal docetaxel

AIM:To enhance the radiosensitivity of human colon cancer cells by docetaxel. METHODS: Immunoliposomal docetaxel was prepared by coupling monoclonal antibody against carcinoembryonic antigen to cyanuric chloride at the PEG terminus of liposome. LoVo adenocarcinoma cell line was treated with immunoliposomal docetaxel or/and irradiation. MTT colorimetric assay was used to estimate cytotoxicity of immunoliposomal docetaxel and radiotoxicity. Cell cycle redistribution and apoptosis were determined with flow cytometry. Survivin expression in LoVo cells was verified by immunohistochemistry. D801 morphologic analysis system was used to semi-quantify immunohistochemical staining of survivin. RESULTS: Cytotoxicity was induced by immunoliposomal docetaxel alone in a dose-dependent manner. Immunoliposomal docetaxel yielded a cytotoxicity effect at a low dose of 2 nmol/L. With a single dose irradiation, the relative surviving fraction of LoVo cells showed a dose-dependent response, but there were no significant changes as radiation delivered from 4 to 8 Gy. Compared with liposomal docetaxel or single dose irradiation, strongly radiopotentiating effects of immunoliposomal docetaxel on LoVo cells were observed. A low dose of immunoliposomal docetaxel could yield sufficient radiosensitivity. Immunoliposomal docetaxel were achieved both specificity of the conjugated antibody and drug radiosensitization. Combined with radiation, immunoliposomal docetaxel significantly increased the percentage of G2/M cells and induced apoptosis, but significantly decreased the percentage of cells in G2/G1 and S phase by comparison with liposomal docetaxel. Immunohistochemical analysis showed that the brown stained survivin was mainly in cytoplasm of LoVo cells. Semi-quantitative analysis of the survivin immunostaining showed that the expression of survivin in LoVo cells under irradiation with immunoliposomal docetaxel was significantly decreased. CONCLUSION: Immunoliposomal docetaxel is strongly effective for target radiosensitation in LoVo colon carcinoma cells, and may offer the potential to improve local radiotherapy.

Anti-cancer effect of ethylacetate fraction from Orostachys japonicus on HT-29 human colon cancer cells by induction of apoptosis through caspase-dependent signaling pathway

Objective: To investigate the anti-colon cancer effects of ethylacetate fraction from Orostachys japonicus(0. japonicus) on HT-29 cancer cells. Methods: The viability of HT-29 cells was assayed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium(MTS) method. Apoptosis induction and cell cycle inhibition were confirmed by fluorescein isothiocyanate and propidium iodide staining using flow cytometry.Morphological changes in the nucleus were observed, using a fluorescence microscope with4',6-diamidino-2-phenylindole(DAPI) nuclear staining. The expression levels of the upstream and downstream proteins involved in the anti-cancer mechanism were confirmed by Western blotting. Results: After treating HT-29 cells with different concentrations of ethylacetate fraction from O. japonicus, the viability of cells decreased in a concentration-dependent manner,while apoptosis induction and apoptotic body formation increased. Cell cycle analysis showed that the arrest occurred at the sub-G_1 and S phase. Among the upstream and downstream proteins involved in anti-cancer activity, the level of B cell lymphoma-2 decreased, and the bcl-2-associated x protein increased. The level of pro-caspase-3, pro-caspase-8, and pro-caspase-9 decreased, while the level of cleaved-caspase-3, cleaved-caspase-8, and cleaved-caspase-9 increased. Moreover, the phosphorylation, that is, activation of extracellular signal regulated kinase 1/2, Jun-N-terminal kinase, and p38 increased. Conclusions: Combining the above results, it is thought that the survival of HT-29 cells is suppressed by ethylacetate fraction from0. japonicus through mitochondrial regulation-induced caspase cascade activation, induction of apoptosis and cell cycle arrest.

Expression of T-STAR gene is associated with regulation of telomerase activity in human colon cancer cell line HCT-116

AIM： To investigate the effects on telomerase activity of transfection of human T-STAR gene full-length sense cDNA or partial antisense cDNA into human colon cancer cell line HCT-116.METHODS： mRNA and protein expression levels of T-STAR gene were determined by RT-PCR and western blot, and telomerase activity was measured by PCR- ELISA, after transfection of T-STAR sense or antisense gene into HCT-116 cells with lipofectamine. RESULTS： T-STAR gene expression was enhanced or knocked down both at mRNA and protein levels, and telomerase activity was significantly increased or decreased. CONCLUSION： The T-STAR gene may participate in regulation of telomerase activity in human colon cancer HCT-116 cells in a parallel fashion.

In vivo comparison of transduction efficiency with recombinant adenovirus-mediated p53 in a human colon cancer mouse model by different delivery routes

Objective： To evaluate transduction efficiency with recombinant adenovirus-mediated p53 （rAd/p53） therapy in a human colon cancer mouse model by intra-tumoral injection and intra-arterial delivery. Methods： The tumor pieces of human colon cancer SW480 were implanted in the livers of 45 nude mice. These mice were administrated with rAd/p53 by intratumoral injection and intra-artedal delivery. After 24 h, 48 h and 72 h tAd/p53 administration, 5 mice each group were killed with over anesthesia and their livers were removed. P53 expression and apoptosis of tumor and liver were assessed. Results： P53 expression and apoptosis of intratumoral administration group was higher than tail vein group and control group. Apoptosis and p53 expression of livers in three groups had no significant difference. Conclusion： p53 gene transducUon efficiency and anticancer effect of rAd/p53 is much better by intra-tumoral injection than intra-arterial delivery,

Synergistic anticancer effect of exogenous wild-type p53 gene combined with 5-FU in human colon cancer resistant to 5-FU in vivo

AIM To investigate the anticancer effect of a recombinant adenovirus-mediated p53(r Ad-p53) combined with 5-fluorouracil(5-FU) in human colon cancer resistant to 5-FU in vivo and the mechanism of r Ad-p53 in reversal of 5-FU resistance.METHODS nude mice bearing human colon cancer SW480/5-FU(5-FU resistant) were randomly assigned to four groups(n = 25 each): control group, 5-FU group, r Ad-p53 group, and r Ad-p53 + 5-FU group. At 24 h, 48 h, 72 h, 120 h and 168 h after treatment, 5 mice were randomly selected from each group and sacrificed using an overdose of anesthetics. The tumors were removed and the protein expressions of p53, protein kinase C(PKC), permeability-glycoprotein(P-gp) and multidrug resistance-associated protein 1(MRP1)(Western blot) and apoptosis(TUNEL) were determined.RESULTS The area ratios of tumor cell apoptosis were larger in the r Ad/p53 + 5-FU group than that in the control, 5-FU and r Ad/p53 groups(P < 0.05), and were larger in the r Ad/p53 group than that of the control group(P < 0.05) and the 5-FU group at more than 48 h(P < 0.05). The p53 expression was higher in the r Ad/p53 and the r Ad/p53 + 5-FU groups than that of the control and 5-FU groups(P < 0.05), and were higher in the r Ad/p53 + 5-FU group than that of the r Ad/p53 group(P < 0.05). Overexpression of PKC, P-gp and MRP1 was observed in the 5-FU and control groups. In the r Ad/p53 + 5-FU group, the expression of P-gp and MRP1 was lower that of the control and 5-FU groups(P < 0.05), and the expression of PKC was lower than that of the control, 5-FU and r Ad/p53 groups at more than 48 h(P < 0.05). In the r Ad/p53 group, the expression of P-gp and MRP1 was lower that of the control and 5-FU groups at more than 48 h(P < 0.05), and the expression of PKC was lower than that of the control and 5-FU groups at more than 120 h(P < 0.05).CONCLUSION5-FU combined with r Ad-p53 has a synergistic anticancer effect in SW480/5-FU(5-FU resistance), which contributes to reversal of 5-FU resistance.

Anti-proliferation effect of zoledronic acid on human colon cancer line SW480

Objective: To investigate the anti-proliferation effect and mechanism of zoledronic acid(ZOL) on human colon cancer line SW480. Methods: SW480 cells were treated with 0, 12.5, 25, 50, 100 and 200 μmo L/L of ZOL for 48 h, and CCK-8 assay was employed to obtain the survival rate of SW480 cells. SW480 cells were treated with 25 μmo L/L of ZOL for 0, 12, 24, 48 and 72 h, and then the survival rate was obtained. SW480 cells of the ZOL group were treated with 25 μmo L/L of ZOL for 48 h, while cells of the Cs A+ZOL group were pretreated with 10 μmo L/L of Cs A for 0.5 h and then treated with 25 μmo L/L of ZOL for 48 h. Then the survival rates of SW480 cells of the control group, ZOL group and Cs A+ZOL group were determined. Flow cytometry was employed to detect the apoptosis rate and the mitochondrial transmembrane potential(△ψm) of the three groups and Western blot was used to detect the expressions of cyt C in the cytosol of the three groups. Results: ZOL inhibited the proliferation of SW480 cells, and the inhibition rate positively correlated with the concentration of ZOL and the action time(P< 0.01). The cell survival rate and the △ψm of the ZOL group were greatly lower than those of the control group, while the apoptosis rate and the expression of cyt C in the cytosol were obviously higher than those of the control group. All the differences showed distinctly statistical significances(P< 0.01). The cell survival rate and the △ψm of the Cs A+ZOL group were all lower than those of the control group, but substantially higher than those of the ZOL group; while the apoptosis rate and the expression of cyt C in the cytosol were higher than those of the control group, but distinctly lower than those of the ZOL group. All the differences were statistically significant(P < 0.01). Conclusions: ZOL can induce the apoptosis in human colon cancer line SW480 and then inhibit the proliferation of SW480 cells directly by opening the mitochondrial permeability transition pore abnormally, decreasing △ψm, and releasing the cyt C into the cytosol. And the effect enhances with the increases of the concentration of ZOL and the action time.

Pro-apoptotic Effects of OSNQ on Human Colon Cancer SW480 Cells

[Objectives] The aim was to elucidate the pro-apoptosis mechanism of naphthoquinone derivative 2-octyl sulfoxide-1,4-naphthoquinone(OSNQ) on human colon cancer SW480 cells.[Methods]The cytotoxic effect of OSNQ on colon cancer SW480 cells was detected by MTT colorimetry.The pro-apoptotic effect of OSNQ on human colon cancer SW480 cells was detected by Annexin V-FITC/PI double staining.The changes in expression of apoptosis-related proteins were detected by Western blot.[Results]The results of MTT assay showed that OSNQ had a significant cytotoxic effect on colon cancer SW480 cells.The results of Western blot showed that OSNQ induced the apoptosis in colon cancer SW480 cells through promoting the expression of pro-apoptotic caspase-3 and inhibiting the expression of apoptosis-inhibiting protein Bcl-2.[Conclusions] OSNQ has a significant cytotoxic effect on colon cancer SW480 cells,and it induces the apoptosis of colon cancer SW480 cells by AKT signaling pathway.

Suppression of human colon tumor growth by adenoviral vector-mediated NK4 expression in an athymic mouse model

AIM： To investigate the suppressive effects of adenoviral vector-mediated expression of NK4, an antagonist of hepatocyte growth factor （HGF）, on human colon cancer in an athymic mouse model to explore the possibility of applying NK4 to cancer gene therapy. METHODS： A human colon tumor model was developed by subcutaneous implantation of tumor tissue formed by LS174T cells grown in athymic mice. Fifteen tumorbearing mice were randomized into three groups （n= 5 in each group） at d 3 after tumor implantation and mice were injected intratumorally with phosphate-buffered saline （PBS） or with recombinant adenovirus expressing 13-galactosidase （Ad-LacZ） or NK4 （rvAdCMV/NK4） at a 6-d interval for total 5 injections in each mouse. Tumor sizes were measured during treatment to draw a tumor growth curve. At d 26 after the first treatment, all animals were sacrificed and the tumors were removed to immunohistochemically examine proliferating cell nuclear antigen （PCNA）, microvessel density （represented by CD31）, and apoptotic cells. In a separate experiment, 15 additional athymic mice were employed to develop a tumor metastasis model by intraperitoneal injection （ip） of LS174T cells. These mice were randomized into 3 groups （n = 5 in each group） at d 1 after injection and were treated by ip injection of PBS, or Ad-LacZ, or rvAdCMV/NK4 at a 6-d interval for total two injections in each mouse. All animals were sacrificed at d 14 and the numbers and weights of disseminated tumors within the abdominal cavity were measured. RESULTS： Growth of significantly suppressed human colon tumors were in the athymic mice treatedwith rvAdCMV/NK4 （2537.4± 892.3 mm^3） compared to those treated by either PBS （5175.2 ± 1228.6 mm^3） or Ad-LacZ （5578.8± 1955.7 mm^3） （P 〈 0.05）. The tumor growth inhibition rate was as high as 51%. Immunohistochemical staining revealed a similar PCNA labeling index （75.1% ± 11.2% in PBS group vs 72.8% ± 7.6% in Ad-LacZ group vs 69.3% ± 9.4% in rvAdCMV/ NK4 group） in all groups, but significantly lower microvessel density （10.7 ± 2.4 in rvAdCMV/NK4 group vs 25.6 ± 3.8 in PBS group or 21.3 ± 3.5 in Ad-LacZ group, P 〈 0.05）, and a markedly higher apoptotic index （7.3% ± 2.4% in rvAdCMV/NK4 group vs 2.6 4, 1.1% in PBS group or 2.1% ± 1.5% in Ad-LacZ group, P 〈 0.05） in the rvAdCMV/NK4 group compared to the two control groups. In the tumor metastasis model, the number and weight of disseminated tumors of mice treated with rvAdCMV/NK4 were much lower than those of the control groups （tumor number： 6.2 ± 3.3 in rvAdCMV/ NK4 group vs 22.9 ± 7.6 in PBS group or 19.8 ± 8.5 in Ad-LacZ group, P 〈 0.05; tumor weight： 324 ± 176 mg in rvAdCMV/NK4 group vs 962 ± 382 mg in PBS group or 1116 ± 484 mg in Ad-LacZ group, P 〈 0.05）. CONCLUSION： The recombinant adenovirus, rvAdCMV/ NK4, can attenuate the growth of colon cancer in vivo, probably by suppressing angiogenesis and inducing tumor cell apoptosis, but not by direct suppression of tumor cell proliferation. Moreover, rvAdCMV/NK4 may inhibit peritoneal dissemination of colon cancer cells in a murine tumor metastasis model. These findings indicate that NK4 gene transfer may be an effective tool for the treatment of colon cancer.

Estradiol agonists inhibit human Lo Vo colorectal-cancer cell proliferation and migration through p53

AIM: To investigate the effects of 17&#x003b2;-estradiol via estrogen receptors (ER) or direct administration of ER agonists on human colorectal cancer.

Colon Adenocarcinoma Diagnosis in Human Samples by Multicontrast Nonlinear Optical Microscopy of Hematoxylin and Eosin Stained Histological Sections

Combined multimodal nonlinear optical (NLO) microscopies were used to detect and quantify morphological changes associated with stroma and epithelial transformation in colon cancer. Our findings provide complementary information about tissue microstructure, displaying distinctive patterns between normal and malignant human colon. Additionally, we have demonstrated the usefulness of using fixed tissues for the disease diagnostic and prognostic.?The present work provides a framework for using NLO techniques as a clinical diagnostic tool for human colon cancer. NLO metrics could be applied to other disorders, which are characterized by abnormal cell proliferation and collagen assembly.

Approaches that ascertain the role of dietary compounds in colonic cancer cells

Preventive approaches against cancer have not been fully developed and applied.For example,the incidence of some types of cancer,including colon cancer,is highly dependent upon lifestyle,and therefore,amenable to prevention.Among the lifestyle factors,diet strongly affects the incidence of colon cancer; however,there are no definitive dietary recommendations that protect against this malignancy.The association between diet-derived bioactives and development of colonic neoplasms will remain ill defined if we do not take into account:(1) the identity of the metabolites present in the colonic lumen;(2) their concentrations in the colon; and(3) the effect of the colonic contents on the function of individual bioactives.We review two approaches that address these questions:the use of fecal water and in vitro models of the human colon.Compared to treatment with individual diet-derived compounds,the exposure of colon cancer cells to samples from fecal water or human colon simulators mimics closer the in vitro conditions and allows for more reliable studies on the effects of diet on colon cancer development.The rationale and the advantages of these strategies are discussed from the perspective of a specific question on how to analyze the combined effect of two types of bioactives,butyrate and polyphenol metabolites,on colon cancer cells.

SOX4靶向miR-17对结肠癌细胞HCT-116生物学行为的影响

目的探讨性别决定区Y框蛋白4(SOX4)及miR-17在结直肠癌中的表达及对HCT-116细胞生物学行为的作用。方法收集2020年3月至2022年1月在河北北方学院一附院和张家口市第一医院的27例结直肠癌患者组织标本并检测SOX4及miR-17的表达水平,并分析与临床病理特征的关系。利用慢病毒转染技术干预HCT-116细胞的SOX4及miR-17表达。检测各组细胞中SOX4和miR-17的表达及细胞增殖、侵袭、迁移能力、细胞活性变化和相关蛋白表达。结果与正常组织比较,结直肠癌组织中SOX4表达水平升高。SOX4及miR-17在结直肠癌组织中的表达呈正相关(r=0.724,P<0.001),SOX4和miR-17的表达和病理分期、淋巴结转移、肝转移情况相关,差异有统计学意义(P<0.05),而与肿瘤的大小、分化程度无相关(P>0.05)。SOX4模拟组细胞增殖能力、迁移能力及细胞活性显著高于对照组及SOX4抑制剂组(P<0.05)。SOX4抑制剂组与对照组相比迁移及增殖相关蛋白表达差异有统计学意义(P<0.05)。结论SOX4在结直肠癌组织中表达上调,SOX4的表达可促进结肠癌细胞增殖、迁移和侵袭能力,miR-17可能是其下游调控靶点。

盐酸小檗碱对人结肠癌细胞SW480增殖、迁移及侵袭的影响

目的探究盐酸小檗碱对人结肠癌细胞SW480增殖、迁移和侵袭过程的影响及可能的机制。方法将人结肠癌细胞SW480细胞分成实验组、对照组、空白组,用CCK8法测定不同浓度的盐酸小檗碱对SW480细胞增殖的作用,并计算出盐酸小檗碱不同浓度作用下SW480细胞的存活率;通过平板克隆形成、细胞划痕、Transwell等实验,明确盐酸小檗碱对SW480的克隆形成、迁移及侵袭的作用。结果盐酸小檗碱能明显地抑制SW480细胞的增殖,并表现出明显的时间和浓度依赖关系;盐酸小檗碱对SW480细胞的克隆形成、迁移及侵袭过程有显著的抑制作用,差异有统计学意义(P<0.05)。结论盐酸小檗碱对细胞SW480的克隆形成、增殖、侵袭和迁移过程均有明显的抑制作用。

复方葛根汤诱导结肠癌HCT116细胞铁死亡分子机制研究

为探究复方葛根汤对结肠癌HCT116细胞增长作用及其分子机制,通过MTT法检测、克隆形成、形态学分析探讨复方葛根汤对HCT116细胞增长作用,以活性氧试剂盒检测、荧光显微成像及蛋白免疫印迹法探究其分子机制。研究结果显示,与溶媒对照组相比,复方葛根汤能显著抑制HCT116细胞增长能力,并呈浓度和时间依赖性,机制上能显著增加细胞内活性氧,显著上调铁死亡相关蛋白PTGS2、ACSL4蛋白的表达,及明显下调铁死亡相关蛋白GPX4表达,表明复方葛根汤可能通过诱导铁死亡机制抑制HCT116细胞增长。

DADS负调控uPAR/uPA信号抑制人结肠癌SW480细胞侵袭和EMT

目的探讨二烯丙基二硫(DADS)抑制人结肠癌SW480细胞侵袭和上皮间质转化(EMT)的可能机制。方法免疫组化检测结肠癌组织中尿激酶型纤溶酶原激活剂(uPA)受体(uPAR)的表达。基因转染技术构建uPAR过表达细胞。实验分为SW480组、SW480+DADS组、uPAR组、uPAR+DADS组。迁移、侵袭实检测各组细胞迁移与侵袭能力。RT-PCR、Western blotting分别检测相关信号通路分子mRAN及其蛋白的表达。裸鼠实验验证DADS对uPAR过表达SW480细胞移植瘤的影响。结果结肠癌组织中uPAR表达显著高于癌旁正常黏膜组织(P<0.05)。成功构建稳定uPAR过表达SW480细胞。uPAR过表达上调uPA、uPAR表达,而DADS下调uPA、uPAR表达。uPAR过表达增强细胞迁移、侵袭能力,DADS抑制uPAR过表达细胞的迁移、侵袭能力。DADS通过下调Vimentin、基质金属蛋白酶(MMP-9)表达,上调E-cadherin、组织金属蛋白酶抑制物(TIMP)-3表达抑制SW480细胞EMT。裸鼠实验结果显示,DADS可体内抑制uPAR过表达SW480细胞EMT。结论DADS通过负调控uPAR/uPA信号体内外抑制人结肠癌SW480细胞侵袭和EMT。

HPV16型E6癌基因对结肠癌细胞增殖和凋亡的影响

目的探讨人乳头瘤病毒(HPV)16 E6的表达与结肠癌细胞增殖和凋亡之间的关系。方法应用含HPV16 E6癌基因的质粒转染HT29和SW480结肠癌细胞株,通过CCK-8和流式细胞仪检测细胞增殖和凋亡情况,并检测葡萄糖转运蛋白1(GLUT1)的表达。结果转染HPV16 E6癌基因后,HT29和SW480均表现为细胞增殖抑制,细胞凋亡增加,GLUT1蛋白表达水平显著降低。结论HPV16 E6可显著降低GLUT1的表达水平,抑制结肠癌细胞的增殖,促进细胞凋亡。

Identification of an anticancer compound against HT-29 cells from Phellinus linteus grown on germinated brown rice

Objective:To isolate and identify the anticancer compound against proliferation of human colon cancer cells from ethyl acetate(EtOAc)extract ol Phellinus linteus grown on germinated brown rice(PB).Methods:EtOAc extract of PB was partitioned with n-hexane,EtOAc,and water-saturated n-butanol.Anticancer compound of n-hexane layer was isolated and identified by HPLC and NMR,respectively.Cytotoxicity against HT-29 cells was tested by SRB assay.Results:The n-hexane layer obtained after solvent fractionation of PB EtOAc extracts showed a potent anticancer activity against the HT-29 cell line.Atractylenolide I,a eudesmane-type sesquiterpene lactone,a major anticancer substance of PB,was isolated from the n-hexane layer by silica gel column chromatography and preparative-HPLC.This structure was elucidated by one-and two-dimensional NMR spectroscopic data.Atractylenolide I has not been reported in mushrooms or rice as of yet.The isolated compound dose-dependently inhibited the growth of HT-29 human colon cancer cells.Conclusions:Atractylenolide I might contribute to the anticancer effect of PB.

Epigenetic field defects in progression to cancer

A field defect is a field of pre-malignant tissue in which a new cancer is likely to arise. Field defects often appear to be histologically normal under the microscope. Recent research indicates that cells within a field defect characteristically have an increased frequency of epigenetic alterations and these may be fundamentally important as underlying factors in progression to cancer. However, understanding of epigenetic field defects is at an early stage, and the work of Katsurano et al published this year, is a key contribution to this field. One question examined by Katsurano et al was how early could the formation of an epigenetic field defect be de-tected in a mouse colitis model of tumorigenesis. They highlighted a number of measurable epigenetic altera-tions, detected very early in normal appearing tissue undergoing histologically invisible tumorigenesis. They also documented the increasing presence of the epigenetic alterations at successive times during progression to cancer. In this commentary, we offer a perspective on the changes they observed within a broader sequence of epigenetic events that occur in progressionto cancer. In particular, we highlight the likely central role of epigenetic deficiencies in DNA repair gene expression that arise during progression to cancer.

滋阴补脾方对人结肠癌裸鼠移植瘤的抑制作用机制研究

目的:探讨滋阴补脾方对人结肠癌裸鼠移植瘤的抑制作用机制。方法:4周龄BALB/c雌性裸鼠20只,制备人结肠癌裸鼠模型,按照随机数字表法分随机分为4组,每组5只。对照组注射等量生理盐水,化疗药物组腹腔注射氟尿嘧啶,中成药组灌胃中药汤剂10 mL,联合用药组:每只裸鼠腹腔注射氟尿嘧啶联合灌胃中药汤剂。1次/d,均连续应用4 d,至第14天处死动物收集标本。测量各组肿瘤重量、肿瘤体积和体积抑瘤率;采用蛋白质印迹法测定CD113、CD116和P53蛋白表达。结果:与对照组比较,化疗药物组、中成药组和联合用药组肿瘤重量、肿瘤体积、CD113和CD116表达明显降低,肿瘤体积抑瘤率和P53表达明显升高(P<0.05);化疗药物组和联合用药组肿瘤重量、肿瘤体积、CD113和CD116表达低于中成药组,肿瘤体积抑瘤率和P53表达高于中成药组(P<0.05);联合用药组肿瘤重量、肿瘤体积、CD113和CD116表达低于化疗药物组,肿瘤体积抑瘤率和P53表达高于化疗药物组(P<0.05)。结论:滋阴补脾法可抑制人结肠癌HT29裸鼠移植瘤生长,认为其机制可能与下调CD113和CD116表达及上调P53表达有关。