BMC Journals

Genetic testing for BRCA1 and BRCA2 (BRCA1/2) mutations can provide important information for women who are concerned about their breast and ovarian cancer risks and need to make relevant prevention and medical management decisions. However, lifetime risks of breast cancer in individual BRCA1/2 mutation carriers have been confusing to apply in clinical decision-making. Published risk estimates vary significantly and are very dependent on the characteristics of the population under study. Recently, Begg et al. estimated cancer risks in a population-based study of BRCA1/2 mutation carriers. Here, we discuss the clinical decision-making implications of this research in the context of risk factors that may influence risk estimates in BRCA1/2 mutation carriers.

Background: Leifsonia xyli is a xylem-inhabiting bacterial species comprised of two subspecies: L. xyli subsp. xyli (Lxx) and L. xyli subsp. cynodontis (Lxc). Lxx is the causal agent of ratoon stunting disease in sugarcane commercial fields and Lxc colonizes the xylem of several grasses causing either mild or no symptoms of disease. Lxx completely sequenced genome provided insights into its biology and pathogenicity. Since, IS elements are largely reported as an important source of bacterial genome diversification, and nothing is known about their role in chromosome architecture of L. xyli, a comparative analysis of Lxc and Lxx elements was performed. Results: Sample sequencing of Lxc genome and comparative analysis with Lxx complete DNA sequence, revealed a variable number of IS transposable elements acting upon genomic diversity. A detailed characterization of Lxc IS elements and a comparative review with IS elements of Lxx are presented. Each genome showed an unique set of elements although related to same IS families when considering features such as similarity among transposases, inverted and direct repeats; and element size. Most of the Lxc and Lxx IS families assigned were reported maintaining transposition at low levels using translation regulatory mechanisms, which is in agreement with our in silico analysis. Some of the IS elements were found associated with rearrangements and specific regions of each genome. Differences were also found in the effect of IS elements upon insertion, although none of the elements were preferentially associated with gene disruption. A survey of transposases among genomes of Actinobacteria showed no correlation between phylogenetic relatedness and distribution of IS families. By using Southern hybridization, we suggested that diversification of Lxc isolates is also mediated by insertion sequences in probably recent events. Conclusions: Taken together our data indicate that transposable elements are involved in genome diversification of Lxc and Lxx. The IS elements were probably acquired after the divergence of the two subspecies and they are associated with genome organization and gene contents. Besides helping on studies of IS element dynamics in general, these data will contribute to our ongoing comparative analyses aimed at understanding the biological differences of the Lxc and Lxx.

Background: Type 1 fimbriae are the most commonly found fimbrial appendages on the outer membrane of Salmonella enterica serotype Typhimurium. Previous investigations indicate that static broth culture favours S. Typhimurium to produce type 1 fimbriae, while non-fimbriate bacteria are obtained by growth on solid agar media. The phenotypic expression of type 1 fimbriae in S. Typhimurium is the result of the interaction and cooperation of several genes in the fim gene cluster. Other gene products that may also participate in the regulation of type 1 fimbrial expression remain uncharacterized. Results: In the present study, transposon insertion mutagenesis was performed on S. Typhimurium to generate a library to screen for those mutants that would exhibit different type 1 fimbrial phenotypes than the parental strain. Eight-two mutants were obtained from 7239 clones screened using the yeast agglutination test. Forty-four mutants produced type 1 fimbriae on both solid agar and static broth media, while none of the other 38 mutants formed type 1 fimbriae in either culture condition. The flanking sequences of the transposons from 54 mutants were cloned and sequenced. These mutants can be classified according to the functions or putative functions of the open reading frames disrupted by the transposon. Our current results indicate that the genetic determinants such as those involved in the fimbrial biogenesis and regulation, global regulators, transporter proteins, prophage-derived proteins, and enzymes of different functions, to name a few, may play a role in the regulation of type 1 fimbrial expression in response to solid agar and static broth culture conditions. A complementation test revealed that transforming a recombinant plasmid possessing the coding sequence of a NAD(P)H-flavin reductase gene ubiB restored an ubiB mutant to exhibit the type 1 fimbrial phenotype as its parental strain. Conclusions: Genetic determinants other than the fim genes may involve in the regulation of type 1 fimbrial expression in S. Typhimurium. How each gene product may influence type 1 fimbrial expression is an interesting research topic which warrants further investigation.

Background: In medical malpractice litigations in recent years in Japan, it is notable that the growing number of medical litigation cases includes the issue of a doctor's explanation to the patient as a pivotal point. The objective of this study was to identify factors of physicians' communication skills with patients, as related to their legal liability, and differences in doctors' communication skills with patients by the type of medical facility. Methods: Decisions of medical malpractice litigation cases between 1988 and 2005 in Japan, the pivotal issue of which was a physician's explanation, were analyzed in the study. The content of each decision was summarized using the study variables (information about the patient, doctor, manner of the doctor's explanation, and subsequent litigation), and a database comprising the content of each decision (N = 100) was constructed. In order to evaluate an association between doctors' communication skills with patients and the outcome of the litigation, the analysis was performed based on the outcome of litigation or the type of medical facility. Results: The ratio of acknowledged physician liability by court decision was lower in cases in which the doctor's explanation occurred before treatment or surgery (p = 0.013). The ratio of acknowledged physician liability by court decision was higher in cases of elective or non-urgent treatment (p = 0.046). The ratio of acknowledged physician liability by court decision was higher in clinics than in hospital groups (p = 0.036). Conclusion: These findings are beneficial for the prevention of medical disputes and improvement of patient-physician communication.

Background: The registration of non-fatal and fatal MI events initiated 1985 in the WHO MONICA project has been ongoing in northern Sweden since the end of the WHO project in 1995. The purpose of the present study was to analyze gender differences in first and recurrent events, case fatality and mortality in myocardial infarction (MI) in Northern Sweden during the 20-year period 1985 - 2004. Methods: Diagnosed MI events in subjects aged 25-64 years in the Counties of Norrbotten and Vasterbotten were validated according to the MONICA protocol. The total number of events registered up to January 1, 2005 was 11,763: 9,387 in men and 2,376 in women. Results: The proportion of male/female events has decreased from 5.5:1 to 3:1. For males the reductions were 30% and 70% for first and recurrent MI, respectively, and for women 0% and 40% in the 55-64 year group. For both sexes a 50% reduction in 28-day case fatality was seen in the 25-64 year- group. Mortality was reduced by 69% and 45% in men and women, respectively. Conclusions: First and recurrent events of myocardial infarction was markedly reduced in men over the 20-year observation period, but for women the reduction was seen only for recurrent infarctions. Case fatality, on the other hand, was markedly reduced for both sexes. As a result of the positive effects on incidence and case fatality a substantial reduction was seen in total mortality, most pronounced for men.

Background: GenBank flatfile (GBF) format is one of the most popular sequence file formats because of its detailed sequence features and ease of readability. To use the data in the file by a computer, a parsing process is required and is performed according to a given grammar for the sequence and the description in a GBF. Currently, several parser libraries for the GBF have been developed. However, with the accumulation of DNA sequence information from eukaryotic chromosomes, parsing a eukaryotic genome sequence with these libraries inevitably takes a long time, due to the large GBF file and its correspondingly large genomic nucleotide sequence and related feature information. Thus, there is significant need to develop a parsing program with high speed and efficient use of system memory. Results: We developed a library, GBParsy, which was C language-based and parses GBF files. The parsing speed was maximized by using content-specified functions in place of regular expressions that are flexible but slow. In addition, we optimized an algorithm related to memory usage so that it also increased parsing performance and efficiency of memory usage. GBParsy is at least 5 - 100X faster than current parsers in benchmark tests. Conclusions: GBParsy is estimated to extract annotated information from almost 100 Mb of a GenBank flatfile for chromosomal sequence information within a second. Thus, it should be used for a variety of applications such as on-time visualization of a genome at a web site.

Background: Vertebrate alpha (a)- and beta (b)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the a- and b-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil b-globin gene (w) in the marsupial a-cluster, however, suggested that duplication of the a-b cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous a- and b-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation. Results: The platypus a-globin cluster (chromosome 21) contains embryonic and adult a- globin genes, a b-like w-globin gene, and the GBY globin gene with homology to cytoglobin, arranged as 5'-z-z'-aD-a3-a2-a1-w-GBY-3'. The platypus b-globin cluster (chromosome 2) contains single embryonic and adult globin genes arranged as 5'-e-b-3'. Surprisingly, all of these globin genes were expressed in some adult tissues. Comparison of flanking sequences revealed that all jawed vertebrate a-globin clusters are flanked by MPG-C16orf35 and LUC7L, whereas all bird and mammal b-globin clusters are embedded in olfactory genes. Thus, the mammalian a- and b-globin clusters are orthologous to the bird a- and b-globin clusters respectively. Conclusions: We propose that a- and b-globin clusters evolved from an ancient MPG-C16orf35-a-b-GBY-LUC7L arrangement 410 million years ago. A copy of the original b (represented by w in marsupials and monotremes) was inserted into an array of olfactory genes before the amniote radiation (>315 million years ago), then duplicated and diverged to form orthologous clusters of b-globin genes with different expression profiles in different lineages.

Background: PTX is one of the most widely used drug in oncology due to its high efficacy against solid tumors and several hematological cancers. PTX is administered in a formulation containing 1:1 Cremophor EL (polyethoxylated castor oil) and ethanol, often responsible for toxic effects. Its encapsulation in colloidal delivery systems would gain an improved targeting to cancer cells, reducing the dose and frequency of administration. Methods: In this paper PTX was loaded in PLGA NS. The activity of PTX-NS was assessed in vitro against thyroid, breast and bladder cancer cell lines in cultures. Cell growth was evaluated by MTS assay, intracellular NS uptake was performed using coumarin-6 labelled NS and the amount of intracellular PTX was measured by HPLC. Results: NS loaded with 3% PTX (w/w) had a mean size

Background: In the presence of both HIV infection and cervical intraepithelial neoplasia (CIN), the risk of cancer development despite treatment may be greater. We investigated clinical predictors of persistent cytological abnormalities in women who had had a large loop excision of the transformation zone (LLETZ). Methods: Women with high grade squamous intraepithelial lesions or worse (HSIL), less severe abnormalities which persisted and any abnormality in women who are HIV-infected, were referred to the colposcopy clinic. HIV infection was ascertained by self-report. A LLETZ was performed on all patients with HSIL or higher on Papanicolaou (Pap) smear or colposcopy, LSIL or higher in patients who are HIV-infected, where the colposcopy is inadequate, and when there was a discrepancy between colposcopy and cytology by one or more grades. Women with abnormal follow-up smears were compared to those with normal smears. We examined the association between abnormal follow-up smears and demographic and clinical predictors using logistic regression Results: The median time between LLETZ and first follow-up Pap smear was rather short at 122 days. Persistent cytological abnormalities occurred in 49 % of our patients after LLETZ. Predictors of persistence included the presence of disease at both margins and HIV infection. Among the latter, disease at the excision margins and CD4+ cell count were important predictors. In these women, disease at the endocervical margin, both margins, and disease only at the ectocervical margin were associated with increased odds of persistent abnormalities on follow-up cervical smear. Conclusion: We showed extremely high risk of cytological abnormality at follow-up after treatment more so in patients with incomplete excision and in the presence of immunocompromise. It remains uncertain whether recurrent CIN is a surrogate marker for invasive cervical cancer.

Background: Thymidylate synthase, dihydropyrimidine dehydrogenase , thymidine phosphorylase , and orotate phosphoribosyltransferase gene expressions are reported to be valid predictive markers for 5-fluorouracil sensitivity to gastrointestinal cancer. For more reliable predictability, their expressions in cancer cells and stromal cells in the cancerous tissue (cancerous stroma) have been separately investigated using laser capture microdissection. Methods: Thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyltransferase mRNA in cancer cells and cancerous stroma from samples of 47 gastric and 43 colon cancers were separately quantified by reverse transcription polymerase chain reaction after laser capture microdissection . Results: In both gastric and colon cancers, thymidylate synthase and orotate phosphoribosyltransferase mRNA expressions were higher (p

Background: Animal and cell culture data suggest a critical role for Munc18c and Syntaxin 4 proteins in insulin mediated glucose transport in skeletal muscle, but no studies have been published in humans. Methods: We investigated the effect of a 12 vs. 48 hr fast on insulin action and skeletal muscle Munc18c and Syntaxin 4 protein in lean and obese subjects. Healthy lean (n=14; age=28.0+/-1.4yr; BMI=22.8+/-0.42kg/m2) and obese subjects (n=11; age=34.6+/-2.3yr; BMI=36.1+/-1.5 kg/m2) were studied twice following a 12 and 48 hr fast. Skeletal muscle biopsies were obtained before a 3 hr 40mU/m2/min hyperinsulinemic-euglycemic clamp with [6,6-2H2]glucose infusion. Results: Glucose rate of disappearance (Rd) during the clamp was lower in obese vs lean subjects after the 12 hr fast (obese: 6.25+/-0.67 vs lean: 9.42+/-1.1 mg/kgFFM/min, p=0.007), and decreased significantly in both groups after the 48 hr fast (obese 3.49+/-0.31 vs lean: 3.91+/-0.42 mg/kgFFM/min, p=0.002). Munc18c content was not significantly different between lean and obese subjects after the 12 hour fast, and decreased after the 48 hr fast in both groups (p=0.013). Syntaxin 4 content was not altered by obesity or fasting duration. There was a strong positive relationship between plasma glucose concentration and Munc18c content in lean and obese subjects during both 12 and 48 hr fasts (R2= 0.447, p=0.0015). Significant negative relationships were also found between Munc18c and FFA (p=0.041), beta-hydroxybutryrate (p=0.039), and skeletal muscle AKT content (p=0.035) in lean and obese subjects. Conclusions: These data indicate Munc18c and Syntaxin 4 are present in human skeletal muscle. Munc18c content was not significantly different between lean and obese subjects, and is therefore unlikely to explain obesity-induced insulin resistance. Munc18c content decreased after prolonged fasting in lean and obese subjects concurrently with reduced insulin action. These data suggest changes in Munc18c content in skeletal muscle are associated with short-term changes in insulin action in humans.

Targeting the estrogen receptor (ER), epidermal growth factor receptor 2 (HER2) as well as vascular endothelial growth factor (VEGF) has impressively improved the therapy of breast cancer patients. New approaches for targeted therapies for induction of apoptosis or inhibition of anti-apoptosis, cell cycle progression, signal transduction and angiogenesis are described. The molecular pathways and their mechanisms for inhibition or repair are discussed in the preclinically and the clinical setting.

Background: The microbiota of an animal's intestinal tract plays important roles in the animal's overall health, productivity and well-being. There is still a scarcity of information on the microbial diversity in the gut of livestock species such as cattle. The primary reason for this lack of data relates to the expense of methods needed to generate such data. Here we have utilized a bacterial tag-encoded FLX 16s rDNA amplicon pyrosequencing (bTEFAP) approach that is able to perform diversity analyses of gastrointestinal populations. bTEFAP is relatively inexpensive in terms of both time and labor due to the implementation of a novel tag priming method and an efficient bioinformatics pipeline. We have evaluated the microbiome from the feces of 20 commercial, lactating dairy cows. Results: Ubiquitous bacteria detected from the cattle feces included Clostridium, Bacteroides, Porpyhyromonas, Ruminococcus, Alistipes, Prevotella, Lachnospira, Enterococcus, Oscillospira, Cytophage, Anaerotruncus, and Acidaminococcus spp. Foodborne pathogenic bacteria were detected in several of the cattle, a total of 4 cows were found to be positive for Salmonella spp (tentative enterica) and 6 cows were positive for Campylobacter spp. (tentative lanienae). Conclusions: Using bTEFAP we have examined the microbiota in the feces of cattle. As these methods continue to mature we will better understand the ecology of the major populations of bacteria the lower intestinal tract. This in turn will allow for a better understanding of ways in which the intestinal microbiome contributes to animal health, productivity and wellbeing.

Background: Human B cells and plasmacytoid dendritic cells (pDC) are the only cells known to express both TLR7 and TLR9. Plasmacytoid dendritic cells are the primary IFN-alpha producing cells in response to TLR7 and TLR9 agonists. The direct effects of TLR7 stimulation on human B cells is less understood. The objective of this study was to compare the effects of TLR7 and TLR9 stimulation on human B cell function. Results: Gene expression and protein production of cytokines, chemokines, various B cell activation markers, and immunoglobulins were evaluated. Purified human CD19 positive B cells (99.9%, containing both naive and memory populations) from peripheral blood were stimulated with a TLR7-selective agonist (852A), TLR7/8 agonist (3M-003), or TLR9 selective agonist CpG ODN (CpG2006). TLR7 and TLR9 agonists similarly modulated the expression of cytokine and chemokine genes (IL-6, MIP1 alpha, MIP1 beta, TNF alpha and LTA), co-stimulatory molecules (CD80, CD40 and CD58), Fc receptors (CD23, CD32), anti-apoptotic genes (BCL2L1), certain transcription factors (MYC, TCFL5), and genes critical for B cell proliferation and differentiation (CD72, IL21R). Both agonists also induced protein expression of the above cytokines and chemokines. Additionally, TLR7 and TLR9 agonists induced the production of IgM and IgG. A TLR8-selective agonist was comparatively ineffective at stimulating purified human B cells. Conclusions: These results demonstrate that despite their molecular differences, the TLR7 and TLR9 agonists induce similar genes and proteins in purified human B cells.

Background: Latent autoimmune diabetes in adults [LADA] is a type 1 diabetes that is slowly developing. This means many people are treated as having type 2 diabetes at diagnosis as they are adults who are not immediately insulin dependent. LADA can be distinguished from type 2 diabetes by antibody tests. Patients who are antibody positive have an autoimmune reaction which is similar to that of type 1 diabetes and is not found in type 2 diabetes. We would like to examine the best way of treating LADA in the early phase of the conditions, with tablets (similar to type 2 diabetes) or with insulin (similar to type 1 diabetes). Methods: This is a open parallel group prospective randomised trial. Participants need to have a GAD antibody test results of 101 WHO units or more and a diagnosis of diabetes not requiring insulin at diagnosis. Participants will need to have been diagnosed within 12 months and not treated with insulin at study entry. They will be randomised to receive either insulin (NovoMix 30) or tablets (diet treated followed by metformin followed by glitazone (with or without metformin) followed by insulin). Primary outcome assessment will be for change in HbA1c and change in fasting C-peptide over 24 months. Secondary outcome measures will include Quality of life, GAD antibody levels, adverse events, inflammatory markers, insulin resistance, and markers of the metabolic syndrome.DiscussionThis study seeks the best treatment for early LADA in terms of maintaining glycaemic control and maintaining natural insulin production.

Background: Aromatase, the cytochrome P-450 enzyme (CYP19) responsible for estrogen biosynthesis, is an important target for the treatment of estrogen-dependent breast cancer. In fact, the use of synthetic aromatase inhibitors (AI), which induce suppression of estrogen synthesis, has shown to be an effective alternative to the classical tamoxifen for the treatment of postmenopausal patients with ER-positive breast cancer. New AIs obtained, in our laboratory, by modification of the A and D-rings of the natural substrate of aromatase, compounds 3a and 4a, showed previously to efficiently suppress aromatase activity in placental microsomes. In the present study we have investigated the effects of these compounds on cell proliferation, cell cycle progression and induction of cell death using the estrogen-dependent human breast cancer cell line stably transfected with the aromatase gene, MCF-7 aro cells. Results: The new steroids inhibit hormone-dependent proliferation of MCF-7aro cells in a time and dose-dependent manner, causing cell cycle arrest in G0/G1 phase and inducing cell death with features of apoptosis and autophagic cell death. Conclusions: Our in vitro studies showed that the two steroidal AIs, 3a and 4a, are potent inhibitors of breast cancer cell proliferation. Moreover, it was also shown that the antiproliferative effects of these two steroids on MCF-7aro cells are mediated by disrupting cell cycle progression, through cell cycle arrest in G0/G1 phase and induction of cell death, being the dominant mechanism autophagic cell death. Our results are important for the elucidation of the cellular effects of steroidal AIs on breast cancer.

Self-reactive T cells with a low signalling capacity through the T cell receptor (TCR) have recently been observed in the SKG mouse model of rheumatoid arthritis (RA) and have been linked to a spontaneous mutation in the ZAP-70 signal transduction molecule. Here we hypothesize that similar mechanisms also drive RA, associated with an abnormal innate and adaptive immune response driven by NF-kappaB activation and TNF secretion. Similar to the essential part played by pathogens in SKG mice, we propose that HLA-associated immunity to chronic viral infection is a key factor in the immune dysregulation and joint inflammation that characterize RA.

Background: Functional Bowel Disorders (FBD) are chronic disorders that are difficult to treat and manage. Many patients and doctors are dissatisfied with the level of improvement in symptoms that can be achieved with standard medical care which may lead them to seek alternatives for care. There are currently no data on the types of Complementary and Alternative Medicine (CAM) used for FBDs other than Irritable Bowel Syndrome (IBS), or on the economic costs of CAM treatments. The aim of this study is to determine prevalence, types and costs of CAM in IBS, functional diarrhea, functional constipation, and functional abdominal pain. Methods: 1012 Patients with FBD were recruited through a health care maintenance organization and followed for 6 months. Questionnaires were used to ascertain: Utilization and expenditures on CAM, symptom severity (IBS-SS), quality of life (IBS-QoL), psychological distress (BSI) and perceived treatment effectiveness. Costs for conventional medical care were extracted from administrative claims. Results: CAM was used by 35% of patients, at a median yearly cost of $200. The most common CAM types were ginger, massage therapy and yoga. CAM use was associated with female gender, higher education, and anxiety. Satisfaction with physician care and perceived effectiveness of prescription mediation were not associated with CAM use. Physician referral to a CAM provider was uncommon but the majority of patients receiving this recommendation followed their physician's advice. Conclusions: CAM is used by one-third of FBG patients. CAM use does not seem to be driven by dissatisfaction with conventional care. Physicians should discuss CAM use and effectiveness with their patients and refer patients if appropriate.

Background: The vinka-alkaloyd vinorelbine is a potentially valuable treatment in patients with HER2-positive, trastuzumab-resistant advanced breast cancer. We sought to document the clinical activity of vinorelbine-based salvage treatments in this clinical setting. Methods: We analyzed a cohort of 424 consecutive women receiving trastuzumab-based therapy for HER2-positive advanced breast cancer. Of these, 299 were identified as progressing during the initial trastuzumab-based treatment, and 77 received vinorelbine-based therapy as first salvage treatment. Central review of pathological specimens revealed that 70 patients had HER2-amplification detected by FISH. For these patients we determined overall response rate (ORR = complete-CR + partial-PR) and clinical benefit (CB = CR+PR+Stable disease lasting at least 6 months), time to progression (TTP) and overall survival (OS) from the initiation of vinorelbine-based salvage therapy. Results: In 60 patients who were evaluable for tumor response, ORR and CB rates were 28% (95% C.I. 18%-41%) and 50% (95% C.I. 38%-62%), respectively. Median follow-up from the initiation of salvage therapy was 15 months (range 1-63 months). Median TTP and OS were 7.1 months (95% C.I. 6.6-7.7 months) and 21 months (95% C.I. 14.3-27.7 months), respectively. No differences in clinical outcomes were observed according to whether vinorelbine was administered as a single agent or in combination with other cytostatics, or whether trastuzumab was stopped or continued beyond disease progression. Conclusions: Our findings suggests that vinorelbine-based combinations are active and should be further evaluated in studies conducted in trastuzumab-resistant patients, including those evaluating newer HER2-targeting agents.

Background: Conjugated linoleic acid (CLA), a naturally occurring fatty acid found in ruminant products such as milk and beef, has been shown to possess anti-cancer activities in in vivo animal models and in vitro cell culture systems. In human breast cancer, the overall duration of estrogen exposure is the most important risk factor for developing estrogen-responsive breast cancer. Accordingly, it has been suggested that estrogen exposure reduces apoptosis through the up-regulation of the anti-apoptosis protein, Bcl-2. Bcl-2, an anti-apoptotic protein, regulates apoptosis and plays a crucial role in the development and growth regulation of normal and cancerous cells. Our research interest is to examine the effects of CLA on the induction of apoptosis in human breast tissues. Methods: The localization of Bcl-2 in both normal and cancerous human breast tissues was determined by immunohistochemical staining and the Bcl-2 protein expression was tested by western blot analysis. Co-culture of epithelial cells and stromal cells was carried out in the presence or absence of CLA to evaluate apoptosis in the context of a cell-cell interaction. Results: The results showed that both normal and cancerous breast tissues were positive for Bcl-2 staining, which was higher overall in mammary ducts but very low in the surrounding stromal compartment. Interestingly, by quantifying the western blot data, basal Bcl-2 protein levels were higher in normal breast epithelial cells than in cancerous epithelial cells. Furthermore, treatment with 17 beta-estradiol (E2) stimulated growth, decreased apoptosis and up-regulated Bcl-2 expression in estrogen responsive breast epithelial cells; however, these carcinogenic effects were diminished by either CLA or 4-Hydroxytamoxifen (Tam) and were suppressed further by the combination of CLA and Tam. In both one cell type cultured and co-culture systems, CLA decreased cell proliferation in ER alpha transfected MDA-MB-231 cells but not in the wild type MDA-MB-231 cells. Conclusions: These data, therefore, demonstrate that ER alpha plays important roles in CLA induced apoptosis in human breast tissues.