FISH和IHC检测HER2基因及蛋白在乳腺癌诊治中的应用

目的对比研究免疫组织化学(IHC)与荧光原位杂交(FISH)方法检测乳腺癌中C-erbB-2蛋白表达和HER2基因扩增,评估两种方法的实际应用价值。方法 IHC和FISH法分别检测58例乳腺癌组织中C-erbB-2蛋白表达和HER2基因扩增状况,并进行一致性分析。结果IHC检测蛋白阳性2+和3+共22例,占总病例的37.9%,58例乳腺癌中FISH检测出HER2基因扩增17例,占29.3%。IHC检测C-erbB-2蛋白3+的12例中11例HER2基因扩增阳性,1例无扩增;C-erbB-2蛋白2+者10例,其中5例可见HER2基因扩增;C-erbB-2蛋白1+者11例HER2基因扩增仅1例。C-erbB-2蛋白阴性病例共25例均未检测到基因扩增。结果显示IHC检测C-erbB-2蛋白与FISH检测HER2基因扩增状态有较高的一致性(k=0.681,P0.01),C-erbB-2蛋白阴性和3+标本与HER2基因扩增阳性率比较差异无统计学意义(P0.05);而C-erbB-2蛋白1+和2+病例与其HER2基因扩增差异具有统计学意义(P0.05)。结果 IHC检测C-erbB-2蛋白强阳性(3+)和阴性(0)与HER2基因扩增有较高的一致性,可作为临床是否应用Herceptin治疗的依据,而C-erbB-2蛋白2+和1+病例必须进一步行HER2基因扩增检测。     

Lower expression of CXCR4 in lymph node metastases than in primary breast cancers: potential regulation by ligand-dependent degradation and HIF-1alpha

Stromal-derived factor-1 (SDF-1) is a unique ligand of the CXC chemokine receptor 4 (CXCR4), which is critically involved in the metastasis of breast cancer. High levels of SDF-1 in the common destination organs of metastasis, such as the lymph nodes, lungs, liver, and bones, attract CXCR4-positive tumor cells. The interaction between SDF-1 and CXCR4 leads to the activation of specific signaling pathways, allowing for homing and metastatic progression. However, regulation of CXCR4 expression at the metastatic organ site is not well-documented. We detected the expression of CXCR4 and hypoxia inducible factor (HIF)-1alpha in breast tumor tissues by immunohistochemical staining and analyzed SDF-1 in primary tumors and lymph nodes using real-time RT-PCR. Compared to the corresponding metastasized tumors in the lymph nodes, primary invasive carcinomas showed more intense staining for CXCR4, particularly on the cellular membrane. Both primary tumors and lymph node metastases exhibited higher levels of CXCR4 expression compared to non-neoplastic breast tissues. Therefore, we hypothesized that the tumor environment in the lymph nodes may cause the reduction of CXCR4 levels in the metastatic tumor cells because of: (1) high SDF-1 levels and (2) lower levels of HIF-1alpha. Our in vitro data demonstrated that high levels of SDF-1 can induce the internalization and degradation of CXCR4 through the lysosome pathway. In addition, lower levels of HIF-1alpha in the lymph node metastases, probably induced by the less hypoxic environment, further lowered CXCR4 levels. These results indicate that ligand-dependent degradation and lower HIF-1alpha levels may be potential causes of lowered levels of CXCR4 in the lymph nodes compared to the primary tumors. Our study suggests that CXCR4 levels in tumor cells are regulated by its microenvironment. These findings may enhance our ability to understand the biological behavior of breast cancers.     

Down-regulation of BCRP/ABCG2 in colorectal and cervical cancer

Expression of Breast Cancer Resistance Protein (BCRP/ABCG2) in tumor cells is associated with resistance to multiple chemotherapeutic agents. BCRP also protects against phototoxicity by mediating the efflux of protoporphyrins from cells. However, chemotherapy and photodynamic therapy are effective treatment options for cancer. Furthermore, protoporphyrins are essential, in the form of heme, for the synthesis of nitric oxide, over-production of which is associated with cancer. This raises the question as to whether the expression of this transporter is altered in cancer. To address this question, we investigated the expression of BCRP in colorectal cancer and cervical cancer. Paired normal and cancer tissues from colectomy specimens were used for the analysis of BCRP mRNA by RT-PCR and Northern blot. BCRP was analyzed by immunohistochemistry/immunofluorescence. Similar studies were also done with specimens of normal cervix and cancer cervix. A commercial dot blot was probed to quantify the expression of BCRP in paired normal and cancer cDNA samples from 154 patients with tumors in 19 different tissues. BCRP mRNA was present in normal colorectal tissue and showed a 6-fold decrease in cancer. BCRP was abundant in the normal colon and showed a decrease in colon cancer. The down-regulation of BCRP mRNA and protein was also evident in cervical cancer. There was also a decrease in BCRP mRNA in cancer in 12 of the 19 different tissues collected from 154 patients. These data show that cancer-associated down-regulation of BCRP is likely to be a common phenomenon in several tissues. Decreased expression of BCRP may have a role in tumorigenesis by allowing accumulation of genotoxins and over-production of nitric oxide.     

Role of c-Src and focal adhesion kinase in progression and metastasis of estrogen receptor-positive breast cancer

The non-receptor tyrosine kinases c-Src and focal adhesion kinase (Fak) mediate signal transduction pathways that regulate cell proliferation, survival, invasion, and metastasis. Here, we investigated whether c-Src and Fak are activated during progression of hormone-dependent breast cancer. Maximally active c-Src was overexpressed in a subset of tamoxifen-resistant variants and in metastases of recurrent hormone-treated breast cancer. Active Fak was also frequently observed in these tumors. We also show that estrogen receptor (ER) can bind to Fak and that estrogen can modulate Fak autophosphorylation supporting a cross-talk between these two pathways. Inhibition of c-Src activity blocked proliferation of all tamoxifen-resistant variants, suggesting that inhibitors of c-Src-Fak activity may delay or prevent progression and metastasis of ER-positive tumors. These studies also raise the possibility that fully active forms of c-Src and Fak in breast tumors may be biomarkers to predict tamoxifen resistance and/or risk of recurrence in ER-positive breast cancer.     

Bayesian semiparametric dynamic frailty models for multiple event time data

Many biomedical studies collect data on times of occurrence for a health event that can occur repeatedly, such as infection, hospitalization, recurrence of disease, or tumor onset. To analyze such data, it is necessary to account for within-subject dependency in the multiple event times. Motivated by data from studies of palpable tumors, this article proposes a dynamic frailty model and Bayesian semiparametric approach to inference. The widely used shared frailty proportional hazards model is generalized to allow subject-specific frailties to change dynamically with age while also accommodating nonproportional hazards. Parametric assumptions on the frailty distribution are avoided by using Dirichlet process priors for a shared frailty and for multiplicative innovations on this frailty. By centering the semiparametric model on a conditionally conjugate dynamic gamma model, we facilitate posterior computation and lack-of-fit assessments of the parametric model. Our proposed method is demonstrated using data from a cancer chemoprevention study.     

Role of epigallocatechin gallate (EGCG) in the treatment of breast and prostate cancer

Green tea and its major constituent epigallocatechin gallate (EGCG) have been extensively studied as a potential treatment for a variety of diseases, including cancer. Epidemiological data have suggested that EGCG may provide protective effects against hormone related cancers, namely breast or prostate cancer. Extensive in vitro investigations using both hormone responsive and non-responsive cell lines have shown that EGCG induces apoptosis and alters the expression of cell cycle regulatory proteins that are critical for cell survival and apoptosis. This review will highlight the important in vitro mechanistic actions elicited by EGCG in various breast and prostate cancer cell lines. Additionally, the actions of green tea/EGCG in in vivo models for these cancers as well as in clinical trials will be discussed.     

Polymethoxylated flavones induce Ca(2+)-mediated apoptosis in breast cancer cells

Flavonoids, polyphenolic phytochemicals which include flavones and isoflavones, are present in the common human diet. It has been suggested that these compounds may exert anticancer activity; however, the mechanisms involved remain unknown. We have recently shown (Sergeev, 2004, Biochem Biophys Res Commun 321: 462-467) that isoflavones can activate the novel apoptotic pathway mediated by cellular Ca(2+). Here, we report that polymethoxyflavones (PMFs) derived from sweet orange (Citrus sinensis L.) inhibit growth of human breast cancer cells via Ca(2+)-dependent apoptotic mechanism. The treatment of MCF-7 breast cancer cells with 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone (5-OH-HxMF) and 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (3'-OH-TtMF) induced a sustained increase in concentration of intracellular Ca(2+) ([Ca(2+)](i)) resulting from both depletion of the endoplasmic reticulum Ca(2+) stores and Ca(2+) influx from the extracellular space. This increase in [Ca(2+)](i) was associated with the activation of the Ca(2+)-dependent apoptotic proteases, mu-calpain and caspase-12, as evaluated with the calpain and caspase-12 peptide substrates and antibodies to active (cleaved) forms of the enzymes. Corresponding non-hydroxylated PMFs, 3,5,6,7,8,3',4'-heptamethoxyflavone (HpMF) and 5,6,7,3',4'-pentamethoxyflavone (PtMF), were dramatically less active in inducing Ca(2+)-mediated apoptosis. Our results strongly suggest that the cellular Ca(2+) modulating activity of flavonoids underlies their apoptotic mechanism and that hydroxylation of PMFs is critical for their ability to induce an increase in [Ca(2+)](i) and, thus, activate Ca(2+)-dependent apoptotic proteases.     

Flavonoid-drug interactions: effects of flavonoids on ABC transporters

Flavonoids are present in fruits, vegetables and beverages derived from plants (tea, red wine), and in many dietary supplements or herbal remedies including Ginkgo Biloba, Soy Isoflavones, and Milk Thistle. Flavonoids have been described as health-promoting, disease-preventing dietary supplements, and a high intake of flavonoids has been associated with a reduced risk of cancer, cardiovascular diseases, osteoporosis and other age-related degenerative diseases. Due to an increased public interest in alternative medicine and disease prevention, the use of herbal preparations containing high doses of flavonoids for health maintenance has become very popular, raising the potential for interactions with conventional drug therapies. This review will summarize the current literature regarding the interactions of flavonoids with ATP-binding cassette (ABC) efflux transporters, mainly P-glycoprotein, MRP1, MRP2 and BCRP and discuss the potential consequences for flavonoid-drug transport interactions.     

Differentiation of serum levels of trace elements in normal and malignant breast patients

The objective of this study was to determine which elements in serum best differentiated breast cancer in a case-control study. Concentrations of 13 elements in serum of 68 breast tumor patients (25 malignant and 43 benign) and 26 healthy controls were measured. Logistic regression with different variable-selection procedures was used to determine a possible configuration of elements. Sensitivity and specificity of the model were calculated to obtain the optimal cutoff point for discriminating malignant breast cancers vs other individuals (including benign breast disease and normal ones). A combination of Cd, Mn, and Fe was found to have a specificity and sensitivity of 100% using forward-type logistic regression, when the cutoff value of the combination score was 52.71. Using stepwise-type logistic regression, a combination of Cr and Mn had a sensitivity of 100% and a specificity of 97.1% when the combination score of 17.4 was chosen as the cutoff. Similar analysis could be implemented to compare the malignant and control groups. Specificity and sensitivity were 100% for Mn (forward and stepwise type) with a cutoff point of 6.40. For the backward regression, specificity was 84.6% and sensitivity was 100% for Zn, with a cutoff point of 869.1. In conclusion, there was a significant difference in concentrations of all 13 elements in serum between breast cancer patients and controls. A combination among Cd, Mn, Fe, Cr, and Zn might be important to determine a differentiating reference for breast cancers if a long-term followed-up study is to be conducted.