The Effect of Seal Oil on Paclitaxel Induced Cytotoxicity and Apoptosis in Breast Carcinoma MCF-7 and MDA-MB-231 Cell Lines

Some studies have suggested that ω-3 polyunsaturated fatty acids (PUFAs) have an inhibitory effect on the growth of cancer cells and therefore have the potential to increase the efficacy of cancer chemotherapeutic drugs. Considering that ω-3 PUFAs are present abundantly in harp seal oil, we investigated the effect of seal oil on the cytotoxicity and apoptosis induced by paclitaxel in 2 breast cancer cell lines, MCF-7 and MDA-MB-231, respectively. Cytotoxicity evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that the concentration of paclitaxel that is required for 50% inhibition of cell growth in the presence of seal oil was significantly lower than that of paclitaxel alone. Apoptosis assessment based on morphological changes and DNA fragmentation results indicated that more cells treated with paclitaxel in combination with seal oil underwent apoptosis than with paclitaxel alone. Western blot analysis showed that the expression of B cell lymphoma-2 (Bcl-2) protein, an apoptosis inhibitory protein, in both cell lines was decreased more significant by paclitaxel in combination with seal oil than by paclitaxel alone. In addition, seal oil alone was found to induce apoptosis in both cell lines tested, which appeared to be due to the increased intracellular lipid peroxides produced. It is therefore concluded that paclitaxel in combination with seal oil demonstrated enhanced cytotoxicity and apoptosis in MCF-7 and MDA-MB-231 cells compared to paclitaxel alone, and the use of seal oil may be beneficial in the treatment of breast cancer.     

Cytotoxic Activity of Piper cubeba Extract in Breast Cancer Cell Lines

This study aimed to evaluate the cytotoxicity of a crude extract of Piper cubeba against normal and breast cancer cell lines. To prepare the extract, P. cubeba seeds were ground, soaked in methanol and dichloromethane and isolated by column chromatography. Fractions were tested for cytotoxicity effects on normal fibroblast (L929), normal breast (MCF-12A) and breast cancer cell lines (MCF-7, MDA-MB-468 and MDA-MB-231). The most effective fraction was selected for DNA fragmentation assay to detect apoptotic activity. The results showed that the methanolic crude extract had a higher cytotoxic activity against MDA-MB-468 and MCF-7 than a dichloromethane crude extract. Then, the methanolic crude extract was separated into six fractions, designated A to F. Fraction C was highly active against breast cancer cell lines with an IC₅₀ value less than 4 μg/mL. Therefore, Fraction C was further separated into seven fractions, CA to CG. The ¹H-NMR profile showed that Fraction CE was long chain hydrocarbons. Moreover, Fraction CE demonstrated the highest activity against MCF-7 cells with an IC₅₀ value of 2.69 ± 0.09 μg/mL and lower cytotoxicity against normal fibroblast L929 cells with an IC₅₀ value of 4.17 ± 0.77 μg/mL. Finally, DNA fragmentation with a ladder pattern characteristic of apoptosis was observed in MCF-7, MDA-MB-468, MDA-MB-231 and L929 cells, but not in MCF-12A cells.     

Involvement of PPARalpha in the growth inhibitory effect of arachidonic acid on breast cancer cells

Epidemiological studies suggest that dietary PUFA may influence breast cancer progression. n-3 PUFA are generally known to exert antitumour effects, whereas reports relative to n-6 PUFA anti-carcinogen effects are controversial. Arachidonic acid (AA; 20:4n-6) and its metabolites have been shown to inhibit the growth of human breast cancer cell lines, even if the downstream mechanisms by which AA may influence carcinogenesis remain unresolved. We explored the molecular basis for AA influence on proliferation, signal transduction and apoptosis in two human breast cancer cell lines, MCF-7 and MDA-MB-231. In both cell lines AA inhibited cell growth in a dose-dependent manner, even if MDA-MB-231 was somewhat more growth-inhibited than MCF-7. AA decreased extracellular signal-regulated protein kinase 1/2 phosphorylation level, and positively modulated PPARgamma and PPARalpha expression, with only a slight effect against PPARbeta/delta. In addition, AA increased Bak (an apoptosis-regulating protein) expression and reduced procaspase-3 and -9 levels only in MDA-MB-231 cells, thus indicating that the growth inhibitory effect can be correlated with apoptosis induction. In both cell lines the use of a specific antagonist made it possible to establish a relationship between AA growth inhibitory effect and PPARalpha involvement. AA decreases cell proliferation most likely by inducing apoptosis in MDA-MB-231 cells, while in the MCF-7 cell line the growth inhibitory activity can be attributed to the inhibition of the signal transduction pathway involved in cell proliferation. In both cases, the results here presented suggest PPARalpha as a possible contributor to the growth inhibitory effect of AA.     

Epigenetic modulation of BRCA1 and BRCA2 gene expression by equol in breast cancer cell lines

S-Equol is a metabolite resulting from the conversion of daidzein, a soya phyto-oestrogen, by the gut microflora. The potential protective effects of equol in breast cancer are still under debate. Consequently, we investigated the effects of equol on DNA methylation of breast cancer susceptibility genes (BRCA1 and BRCA2) and oncosuppressors in breast cancer cell lines (MDA-MB-231 and MCF-7) and in a dystrophic breast cell line (MCF-10a) following exposure to S-equol (2?μm) for 3 weeks. We demonstrated by quantitative analysis of methylated alleles a significant decrease in the methylation of the cytosine phosphate guanine (CpG) islands in the promoters of BRCA1 and BRCA2 after the S-equol treatment in MCF-7 and MDA-MB-231 cells and a trend in MCF-10a cells. We also showed that S-equol increases BRCA1 and BRCA2 protein expression in the nuclei and the cytoplasm in MCF-7, MDA-MB-231 and MCF-10a cell lines by immunohistochemistry. The increase in BRCA1 and BRCA2 proteins was also found after Western blotting in the studied cell lines. In summary, we demonstrated the demethylating effect of S-equol on the CpG islands inside the promoters of BRCA1 and BRCA2 genes, resulting in an increase in the level of expressed oncosuppressors in breast cancer cell lines.     

硒甲基硒代半胱氨酸联合紫杉醇通过内质网应激诱导乳腺癌细胞凋亡的分子机制

目的探讨硒甲基硒代半胱氨酸(Se-MSC)联合紫杉醇通过内质网应激诱导三阴性乳腺癌细胞MDA-MB-231凋亡及其分子机制。方法MTT法检测细胞活力,流式细胞术检测细胞周期;Western blot法检测蛋白表达水平,实时qRT-PCR法检测mRNA的表达水平。SPSS 19.0软件进行统计分析。结果MTT法显示Se-MSC和紫杉醇抑制三阴性乳腺癌细胞MDA-MB-231和人脐静脉内皮细胞HUVEC的增殖;Se-MSC 50μmol/L和紫杉醇10nmol/L作用24h对HUVECs无抑制作用,但对MDA-MB-231细胞具有抑制作用;两种药物联合效果较单独使用增强,Se-MSC联合紫杉醇将MDA-MB-231细胞抑制于G1期(P<0.05)。Se-MSC和紫杉醇联合刺激乳腺癌细胞MDA-MB-231可上调Bax、活化Caspase-9和Caspase-3表达,下调Bcl-2、前体caspase-3表达和Bcl-2/Bax比值(P<0.05),并激活内质网应激,上调GRP78、Caspase-4和CHOP的mRNA表达。结论Se-MSC联合紫杉醇通过抑制MDA-MB-231细胞增殖,上调Bax、Caspase-9和Caspase-3表达,下调Bcl-2、Pro caspase-3并激活内质网应激,可推测Se-MSC联合紫杉醇诱导乳腺癌MDA-MB-231细胞凋亡,但需要进一步验证。     

Equol Enhances Apoptosis-inducing Activity of Genistein by Increasing Bax/Bcl-xL Expression Ratio in MCF-7 Human Breast Cancer Cells

Anticancer activities of soy isoflavones, such as genistein and equol, a bioactive metabolite of daidzein, have been extensively studied because of possible involvement in the prevention of breast cancer. However, their interactions still remain unclear. We investigated here whether cytotoxic activity of genistein was enhanced by equol, using estrogen receptor positive MCF-7, HER2-positive SK-BR-3, and triple-negative MDA-MB-468 cell lines. Although cytotoxicity of genistein did not significantly differ between three subtypes of breast cancer cells, cytotoxic activities of genistein were significantly enhanced in combination with 50 μM equol in MCF-7 cells, but not in SK-BR-3 and MDA-MB-468 cells. In fluorescence activated cell sorting (FACS) analyses, MCF-7 cells were arrested at the G2/M by genistein but at G1/S by equol. Combination treatment arrested cells at G2/M but abolished equol-induced G1 block, indicating an antagonistic activity of genistein against equol in cell-cycle progression. Although apoptosis was not so evident with genistein alone, the combination made a drastic induction of apoptosis, accompanied by the increase of Bax/Bcl-xL expression ratio, without affecting the activities of Akt and mTOR. Taken together, these data suggest that enhancement of genistein activity by equol would be mainly mediated by augmented induction of apoptosis rather than arrest or delay of the cell cycle.     

Citrus Limonin Lacks the Antichemotherapeutic Effect in Human Models of Breast Cancer

Background/Aims: Chemicals that interfere with reactive oxygen species metabolism can act as potential candidates for the treatment of cancer. Some of the glucosides of citrus limonin inhibit the endogenously generated reactive oxygen species. The aim is to study the interactions of limonin with chemotherapy. Methods: Breast cancer cell lines MCF-7 (p53 wild type) and MDA-MB-231 (p53 mutant) as well as the nontumorigenic epithelial cell line MCF-10 were used to screen the effect of limonin at 1-, 5- and 10-μM concentrations with camptothecin for apoptosis and NF?B, p38 and ERK-MAPK signaling kinase assays. The effect of cyclophosphamide and limonin on MDA MB 231 xenografts was also studied. Results: Our results indicate that limonin did not inhibit camptothecin-induced apoptosis in human breast cancer cells in vitro through noninterference of camptothecin-induced phosphorylation of p38 MAPK and ERK-MAPK. Using an in vivo model of human breast cancer, limonin in combination with cyclophosphamide was not found to inhibit the cyclophosphamide-induced tumor regression through a reduced mitotic index of tumor xenograft cells when compared to treatment with cyclophosphamide alone. Conclusion: Both in vitro and in vivo results suggest that limonin could be beneficial for breast cancer patients undergoing chemotherapy.     

Parkin蛋白抑制三阴性乳腺癌MDA-MB-231细胞的有氧糖酵解和增殖迁移

目的 评估Parkin蛋白对乳腺癌MDA-MB-231细胞有氧糖酵解和生长增殖的影响。方法 首先采用Western blot检测Parkin蛋白在人乳腺上皮细胞MCF-10A和乳腺癌MDA-MB-231细胞中的表达。随后构建高表达Parkin的乳腺癌MDA-MB-231细胞株为实验组,以转染空载体的MDA-MB-231细胞为对照组,分别采用葡萄糖、乳酸和ATP检测试剂盒检测两组细胞葡萄糖摄取量,乳酸和ATP生成量,并通过Western blot检测糖酵解相关蛋白GLUT1、PKM2和LDHA表达水平;运用细胞增殖实验、平板克隆及细胞划痕实验评估细胞的增殖和迁移能力;采用Western blot检测凋亡相关蛋白Bax、Bcl-2和cleaved Caspase-3的表达水平。结果 与MCF-10A细胞相比,MDA-MB-231细胞Parkin蛋白表达水平显著下降（P<0.01）。高表达Parkin可使乳腺癌MDA-MB-231细胞的葡萄糖摄取和乳酸生成下降,ATP水平上升（P<0.05）,其增殖和迁移能力下降（P<0.01）;与对照组相比,Parkin组细胞糖酵解相关蛋...     

Flaxseed Lignans Enhance the Cytotoxicity of Chemotherapeutic Agents against Breast Cancer Cell Lines MDA-MB-231 and SKBR3

Systemic cytotoxic chemotherapy remains the mainstay of metastatic breast cancer; however, prognosis and overall survival is unfavorable due to inadequate treatment response and/or unacceptable toxicity. Natural compounds and their active metabolites receive increasing attention as possible adjuvant therapy with cancer chemotherapeutics to improve treatment response, survival rates, and quality of life of breast cancer patients. This study investigated the combination of flaxseed lignans (Secoisolariciresinol and Enterolactone) with classic chemotherapeutic agents (Docetaxel, Doxorubicin, and Carboplatin) with different mechanisms of action to determine whether flaxseed lignans could enhance the cytotoxic effect of such drugs in the metastatic breast cancer cell lines, SKBR3 and MDA-MB-231. The experimental data suggests that flaxseed lignans significantly enhanced the ability of chemotherapeutic agents to cause cytotoxicity in SKBR3 and MDA-MB-231 breast cancer cells. A three compound combination study found that enterolactone and metformin together in combination with relatively low concentrations of chemotherapeutic drugs were able to significantly decrease cancer cell viability, compared to low concentrations of the individual chemotherapeutic drug alone. Our in vitro evaluation suggests a future direction in improving chemotherapeutic efficacy in breast cancer by adjuvant therapy with the flaxseed lignans.     

Effects of retinoic acid isomers on apoptosis and enzymatic antioxidant system in human breast cancer cells

Retinoic acids (RAs) modulate growth, differentiation, and apoptosis in normal, pre-malignant & malignant cells. In the present study, the effects of RA isomers (all-trans RA, 13-cis RA, and 9-cis RA) on the cell signal transduction of human breast cancer cells have been studied. The relationship between RAs and an enzymatic antioxidant system was also determined. Estrogen-receptor (ER) positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells were treated with different doses of each RA isomers, all-trans RA, 13-cis RA, or 9-cis RA. Treatment of RA isomers inhibited cell viability and induced apoptosis of MCF-7 cells as a result of increased caspase activity in cytoplasm and cytochrome C released from mitochondria. All-trans RA was the most effective RA isomer in both cell growth inhibition and induction of apoptosis in MCF-7 cells. However, no significant effect of RA isomers was observed on the cell growth or apoptosis in ER-negative MDA-MB-231 cells. In addition, activities of antioxidant enzymes such as catalase and glutathione peroxidase were decreased effectively after treatment of RA in MCF-7 cells, whereas SOD activity was rarely affected. Thus, the present data suggest that all-trans RA is the most potential inducer of apoptosis and modulator of antioxidant enzymes among RA isomers in MCF-7 human breast cancer cells.     

Anticancer activities of an anthocyanin-rich extract from black rice against breast cancer cells in vitro and in vivo

Anthocyanins widely present in human diet and have a variety of health effects. This study investigates the anticancer effects of an anthocyanin-rich extract from black rice (AEBR) on breast cancer cells in vitro and in vivo. AEBR reduced the viability of breast cancer cell lines MCF-7 (ER(+), HER2/neu(-)), MDA-MB-231 (ER(-), HER2/neu(-)), and MDA-MB-453 (ER(-), HER2/neu(+)) and induced apoptosis in MDA-MB-453 cells via the intrinsic pathway in vitro by activating caspase cascade, cleaving poly (ADP-ribose) polymerase (PARP), depolarizing mitochondrial membrane potential, and releasing cytochrome C. Oral administration of AEBR (100 mg/kg/day) to BALB/c nude mice bearing MDA-MB-453 cell xenografts significantly suppressed tumor growth and angiogenesis by suppressing the expression of angiogenesis factors MMP-9, MMP-2, and uPA in tumor tissue. Altogether, this study suggests the anticancer effects of AEBR against human breast cancer cells in vitro and in vivo by inducing apoptosis and suppressing angiogenesis.     

Wasabi-Derived 6-(Methylsulfinyl)Hexyl Isothiocyanate Induces Apoptosis in Human Breast Cancer by Possible Involvement of the NF-κB Pathways

6-(methylsulfinyl)hexyl isothiocyanate (6-MSITC) is a bioactive ingredient of wasabi (Wasabia japonica), which is a popular spice in Japan. 6-MSITC has been reported to inhibit the proliferation of breast cancer and melanoma cell lines. We inoculated 30 female Balb-nu/nu mice with MDA-MB-231 or -453 cells, and orally administered varying concentrations of 6-MSITC for 12 days following tumor growth. The tumor volumes and tumor weights from mice inoculated with MDA-MB-231 cells, and the tumor volumes of MDA-MB-453 cells were significantly inhibited by 6-MSITC on Days 9 and 11 after drug administration. DNA fragmentation, DNA ladder, and caspase 3/7 activity performed in vitro revealed that 6-MSITC induced apoptosis of MDA-MB-231, MDA-MB-453, and MCF-7 cells. Furthermore, nuclear factor-κB (NF-κB) expression in the nuclei and phosphorylation of inhibitor κBα (IκBα) was downregulated by 6-MSITC in a concentration-dependent manner; however, this activity was not observed in MCF-7 cells. Moreover, this downregulation of phosphorylated IκBα by 6-MSITC in MDA-MB-231 and -453 cells supports its inhibitory effects on NF-κB activity. The expression of phosphorylated AKT (pAKT) reduced by 6-MSITC was confirmed in MDA-MB-231 cells. Thus, we conclude that 6-MITC promotes apoptosis of breast cancer cells by inhibiting NF-kB and therefore releasing its control of the PI3K/AKT pathway.     

Effects of Thymus serpyllum Extract on Cell Proliferation,Apoptosis and Epigenetic Events in Human Breast Cancer Cells

Thymus (T.) serpyllum (wild thyme) is an aromatic medicinal plant due to its several biological properties, including anticancer activity. Breast cancer is one of the most common malignancies and increasing evidence supports that it is not only a genetic but also an epigenetic disease. Epigenetics investigates changes in gene expression caused by mechanisms that do not involve alterations in DNA sequence. DNA methylation and histone acetylation are the most widely studied epigenetic changes in cancer cells. This study evaluated the effects of T. serpyllum on apoptosis and epigenetic events in breast cancer cells. XTT cell viability assay was used to determine cytotoxicity. DNA fragmentation and caspase 3/7 activity assays were used in the assesment of apoptosis. DNA methyltransferase (DNMT) and histone deacetylase (HDAC) activities were evaluated by ELISA and verified by qRT-PCR. T. serpyllum extract induced significant cytotoxicity in breast cancer cells (MCF-7 and MDA-MB-231) but not in normal cells. It also induced apoptosis and inhibited the DNMT and HDAC activities in MDA-MB-231 cells. In the present study, the first preliminary data on the effects of the methanolic extract of T. serpyllum in normal and breast cancer cells were obtained and suggest that T. serpyllum may be a promising candidate in the development of novel therapeutic drugs for breast cancer treatment.     

Vitamin E analog alpha-TEA, methylseleninic acid, and trans-resveratrol in combination synergistically inhibit human breast cancer cell growth

Alpha-tocopherol ether-linked acetic acid analog [2,5,7,8-tetramethyl-2R-(4R, 8R-12-trimethyltridecyl) chroman-6-yloxyacetic acid (alpha-TEA)] is a novel form of vitamin E effective at killing cancer cells but not normal cells. alpha -TEA alone and together with methylseleninic acid (MSA) and trans-resveratrol (t-RES) were investigated for ability to induce apoptosis, DNA synthesis arrest, and cellular differentiation and inhibit colony formation in human MDA-MB-435-F-L breast cancer cells in culture. The 3 agents alone were effective in inhibiting cell growth by each of the 4 different assays, and 3-way combination treatments synergistically inhibited cell proliferation in each assay in comparison to individual treatments. Furthermore, combinations of alpha -TEA, t-RES, and MSA significantly enhanced levels of apoptosis in human breast (MDA-MB-231, MCF7, and T47D) and prostate (LnCaP, PC-3, and DU-145) cancer cell lines as well as in immortalized but nontumorigenic MCF10A cells but not primary cultures of human mammary epithelial cells. Western immunoblotting confirmed the induction of apoptosis in that the 3 agents induced poly(adenosine diphosphate-ribose) polymerase cleavage, with earlier detection and more complete cleavage seen in the combination treatment. Mechanistic studies showed combination treatments to inhibit cell proliferation via downregulation of cyclin D1 and induce apoptosis via activation of caspases 8 and 9 and downregulation of prosurvival proteins FLIP and survivin. In summary, the combination of alpha-TEA, MSA, and t-RES is more effective than single treatments for inhibiting cell proliferation, inducing cellular differentiation, and inducing cell death by apoptosis in human cancer cells in culture.     

维生素C和紫杉醇联合作用对乳腺癌细胞MCF-7增殖、细胞周期和凋亡的影响

目的研究维生素C(VC)与紫杉醇联合作用,对人乳癌MCF-7细胞增殖、细胞周期及凋亡的影响。方法 MTT法检测细胞增殖,激光共聚焦观察自噬,流式细胞术测定细胞周期分布和凋亡率变化。结果 VC单独作用,可促进MCF-7的增殖;紫杉醇单独作用及与VC联合作用均可抑制MCF-7的生长,并将细胞阻滞在G2期及诱导细胞凋亡;紫杉醇与VC联合作用对细胞增殖的影响,与二者的用药顺序有关,紫杉醇作用24后联合应用VC,可协同抑制MCF-7的增殖,并且,紫杉醇的IC50最低,即MCF-7对紫杉醇的敏感性最高。结论紫杉醇与VC联合作用对人乳腺癌MCF-7细胞增殖的影响,与二者的用药顺序有关,其作用的机制与影响细胞周期分布和诱导细胞凋亡有关。     

Anticancer Activities of an Anthocyanin-Rich Extract From Black Rice Against Breast Cancer Cells In Vitro and In Vivo

Anthocyanins widely present in human diet and have a variety of health effects. This study investigates the anticancer effects of an anthocyanin-rich extract from black rice (AEBR) on breast cancer cells in vitro and in vivo. AEBR reduced the viability of breast cancer cell lines MCF-7 (ER⁺, HER2/neu^?), MDA-MB-231 (ER^?, HER2/neu^?), and MDA-MB-453 (ER^?, HER2/neu⁺) and induced apoptosis in MDA-MB-453 cells via the intrinsic pathway in vitro by activating caspase cascade, cleaving poly (ADP-ribose) polymerase (PARP), depolarizing mitochondrial membrane potential, and releasing cytochrome C. Oral administration of AEBR (100 mg/kg/day) to BALB/c nude mice bearing MDA-MB-453 cell xenografts significantly suppressed tumor growth and angiogenesis by suppressing the expression of angiogenesis factors MMP-9, MMP-2, and uPA in tumor tissue. Altogether, this study suggests the anticancer effects of AEBR against human breast cancer cells in vitro and in vivo by inducing apoptosis and suppressing angiogenesis.     

Dietary Fatty Acids from Leaves of Clerodendrum Volubile Induce Cell Cycle Arrest,Downregulate Matrix Metalloproteinase-9 Expression,and Modulate Redox Status in Human Breast Cancer

The antiproliferative effect of the fatty acid components of Clerodendrum volubile leaves as well as its antioxidant effect on MCF-7 and MDA-MB-231 human breast cancer cell lines were investigated. Fatty acids extracted from C. volubile leaf oil were subjected to gas chromatography mass spectrometry (GCMS) analysis. The cells were cultured and treated with the fatty acids for 48 h, after which the antiproliferation effect was ascertained via MTT assay and cell viability analysis using BD fluorescence activated cells sorting (FACS) Calibur. Cell cycle was analyzed by flow cytometry on FACS Calibur. Western blotting was used in determining expression of proteins in the cell lines. The treated cell lines were assessed for reduced glutathione level, catalase, superoxide dismutase, and lipid peroxidation. The fatty acids significantly inhibited cell proliferation, arrested G0/G1 phase, downregulated the expression of MMP-9, and attenuated oxidative stress in of MCF-7 cell lines but had little or no effect on MDA-MB-231 cell lines. These results indicate the therapeutic potential of the fatty acids components of the leaves of C. volubile on human breast cancer, which may be explored further in drug development.     

Hydroxytyrosol protects against oxidative DNA damage in human breast cells

Over recent years, several studies have related olive oil ingestion to a low incidence of several diseases, including breast cancer. Hydroxytyrosol and tyrosol are two of the major phenols present in virgin olive oils. Despite the fact that they have been linked to cancer prevention, there is no evidence that clarifies their effect in human breast tumor and non-tumor cells. In the present work, we present hydroxytyrosol and tyrosol's effects in human breast cell lines. Our results show that hydroxytyrosol acts as a more efficient free radical scavenger than tyrosol, but both fail to affect cell proliferation rates, cell cycle profile or cell apoptosis in human mammary epithelial cells (MCF10A) or breast cancer cells (MDA-MB-231 and MCF7). We found that hydroxytyrosol decreases the intracellular reactive oxygen species (ROS) level in MCF10A cells but not in MCF7 or MDA-MB-231 cells while very high amounts of tyrosol is needed to decrease the ROS level in MCF10A cells. Interestingly, hydroxytyrosol prevents oxidative DNA damage in the three breast cell lines. Therefore, our data suggest that simple phenol hydroxytyrosol could contribute to a lower incidence of breast cancer in populations that consume virgin olive oil due to its antioxidant activity and its protection against oxidative DNA damage in mammary cells.     

Omega-3 polyunsaturated fatty acids and ionizing radiation: combined cytotoxicity on human colorectal adenocarcinoma cells

OBJECTIVE: This study evaluated whether omega-3 polyunsaturated fatty acids (PUFAs) could enhance the radiosensitivity of three different human colorectal adenocarcinoma cell lines. To understand the underlying mechanisms, the effects of omega-3 PUFAs on the cell growth, survival, and apoptosis were evaluated alone or in combination with an antioxidant (vitamin E) and compared with the effects of omega-6 PUFAs. METHODS: LS174T, CO112, and Caco-2 cell survival was assessed by clonogenic assay after a 3-d pretreatment with omega-3/omega-6 PUFAs and/or vitamin E before a single X-ray exposure to 4 Gy. Cell growth and viability were measured by double fluorescence-activated cell sorter analyses using propidium iodide and fluorescein isothiocyanate-conjugated annexin V. Student's t test or multivariable linear regression analyses were used for comparison. RESULTS: Preincubation with 30 to 100 mumol/L of omega-3 PUFAs induced a dose-dependent additive decrease in cell survival after irradiation (P < 0.05). Evaluation of the underlying mechanisms indicated that omega-3 PUFAs mainly decreased the cell number via apoptosis induction. Moreover, formation of lipid peroxidation products and modulation of cyclooxygenase II activity seemed to be involved, because coincubation with 10 mumol/L vitamin E abolished the effect of 50 mumol/L of omega-3 PUFAs (P < 0.05), whereas omega-6 PUFAs could partly mimic omega-3 PUFA effects. CONCLUSION: These observations suggest that omega-3 PUFAs may be potential candidates as nutritional adjuvants to enhance the efficacy of human colorectal cancer radiotherapy.     

灭活细胞周期检测点激酶增强乳腺癌细胞放疗敏感性

目的:乳腺癌是严重威胁妇女健康的重要疾病,放疗常常作为乳腺癌综合治疗的重要手段。研究表明,临床上产生放疗抵抗的主要原因是由于放疗激活细胞周期检测点信号传导通路引起细胞自我修复而逃避凋亡,因而目前通过抑制细胞周期检测点信号通路增强肿瘤放、化疗敏感性,已成为国际上抗肿瘤治疗的一个重要方向和研究热点。Chk1和Chk2是细胞周期检测点中最重要的丝氨酸/苏氨酸激酶,本研究通过反义封闭Chk1和/或Chk2基因,阻断细胞周期检测点信号传导通路,研究对乳腺癌MDA-MB-231细胞放疗后细胞周期和凋亡的影响,从而评价Chk1和Chk2基因作为肿瘤治疗靶点的有效性。方法:Western-Blot法检测转染Chk1和Chk2正、反义寡核苷酸后,细胞内Chk1和Chk2蛋白表达情况;流式细胞仪AnnexinV-PI法和SubG1法检测单转染或联合转染Chk1/2反义寡核苷酸对放疗后MDA-MB-231细胞凋亡和细胞周期的影响。结果:反义封闭Chk1或Chk2基因可解除G2/M期阻滞,增强放疗后凋亡敏感性,而同时反义封闭Chk1和Chk2基因具有协同作用。结论:阻断细胞周期检测点信号通路的关键激酶Chk1和Chk2可显著增强放疗后凋亡敏感性。