Molecular markers in breast cancer: can we use c-erbB-2, p53, bcl-2 and bax gene expression as prognostic factors?

Contribution of Yeast Studies to the Understanding of BCL-2 Family Intracellular Trafficking

BCL-2 family members are major regulators of apoptotic cell death in mammals. They form an intricate regulatory network that ultimately regulates the release of apoptogenic factors from mitochondria to the cytosol. The ectopic expression of mammalian BCL-2 family members in the yeast Saccharomyces cerevisiae, which lacks BCL-2 homologs, has been long established as a useful addition to the available models to study their function and regulation. In yeast, individual proteins can be studied independently from the whole interaction network, thus providing insight into the molecular mechanisms underlying their function in a living context. Furthermore, one can take advantage of the powerful tools available in yeast to probe intracellular trafficking processes such as mitochondrial sorting and interactions/exchanges between mitochondria and other compartments, such as the endoplasmic reticulum that are largely conserved between yeast and mammals. Yeast molecular genetics thus allows the investigation of the role of these processes on the dynamic equilibrium of BCL-2 family members between mitochondria and extramitochondrial compartments. Here we propose a model of dynamic regulation of BCL-2 family member localization, based on available evidence from ectopic expression in yeast.

Goji berry (Lycium spp.) extracts exhibit antiproliferative activity via modulating cell cycle arrest, cell apoptosis, and the p53 signaling pathway

The phytochemical profiles, antioxidant activity and antiproliferative mechanism of two goji berry varieties were investigated in the present study. In contrast to Lycium barbarum L. (LB), Lycium ruthenicum Murr. (LRM) showed stronger antioxidant activity evaluated by ORAC, PSC and CAA assays, which might be attributed to its higher total phenolics and total flavonoids. However, LB contains greater contents of VE and carotenoids compared to LRM, which may endow LB with other unique functions instead of antioxidant activity. Additionally, high dose LRM showed a stronger capability in terms of cell cycle arrest and cell apoptosis induction of MDA cells with increments of 17.85% cells blocked at the G1 phase and 50.49% cells achieving early apoptosis compared with the control group. Although supplementation with LB increased the number of cells in the G1 phase by 10%, its effect on inducing cell apoptosis was not ideal. Furthermore, both LRM and LB activated the proliferation-related p53 signaling pathway including p53, p21, CDK4, Cyclin E, Bax and Caspase3, but LB failed to downregulate bcl-2 and CDK2 levels, indicating the weaker antiproliferative effect of LB. The present findings indicated LRM and LB as potential candidates for managing the proliferation of cancer cells and improving human health.

Modern approach of breast cancer diagnostics

In the review have been classified literature data concerning modern instrumental, microscopic and molecular (metabolomics, proteomics, genetics and epigenetics) approaches for early breast cancer diagnostics. The analytical performance and perspectives of their application in clinical practice also have been evaluated.

Prognostic significance of p16INK4a/p53 in Tunisian patients with breast carcinoma

Infiltrating ductal carcinoma (IDC) of the breast is a result of genetic alterations that affect the regulation of the cell cycle check-point and apoptosis. The aim of the present study was analysis using immunohistochemical localization of mouse double minute-2 (mdm2), p16INK4a, p53, bax and bcl-2 markers in Tunisian patients with breast IDC and to determine if there was correlation with the major clinico-pathological parameters and with survival of patients. We showed that the expression of p53, p16INK4a, mdm2, bcl-2, and bax was observed in 46.3%, 20.7%, 38%, 50% and 11.9% of cases, respectively. Statistical analysis revealed that positive expression of mdm2 was associated with larger tumors (P=0.013), whereas bax positivity was more prevalent in younger patients and in tumors of smaller size (P=0.008 and P=0.012 respectively). Furthermore, the expression of p16INK4a correlated with advanced grade (P<0.0001), triple negative tumors (ER-/PR-/HER2-, P=0.001) and mdm2 expression (P=0.017). The absence of nuclear p53 accumulation was predictive of good prognosis as well as when it was associated with negative expression of p16INK4a. Our findings suggest that among the biomarkers tested, p16INK4a might have a useful clinical and prognostic significance in infiltrating ductal carcinoma of the breast.

Mutations of p53 gene in breast cancer in the Egyptian province of Dakahliya

BACKGROUND

Breast cancer is the most common malignancy among females worldwide. Molecular analysis of p53 is likely to have value in diagnosis, prognosis, and treatment of breast cancer.

OBJECTIVE

To study the frequency and spectrum of p53 gene mutations in breast cancer patients residing Al Dakahliya district in the north of Egypt.

MATERIALS AND METHODS

Thirty patients with cancer breast as well as 10 controls were evaluated for p53 status by flow-cytometry, PCR-SSCP, and sequencing analysis.

RESULTS

P53 mutations were evident in five breast cancer patients (17%) including two missense mutations (A218 T and R279 G) in exon 6, 8; nonsense mutations (S297stop and Y159stop) in exon 8, 5, respectively, and frame shift mutation (M133 fs) in exon 5. p53 mutations were associated with invasive ductal carcinoma, large tumor size, and advanced disease stage

CONCLUSION

p53 gene mutations is potentially responsible for pathogenesis and clinical aggressiveness of breast cancer in our locality.

Molecular markers (c-erbB-2, p53) in breast cancer

The aim of our study was to evaluate the correlation between clinical characteristics, histopatologic features and c-erbB-2 as well as p53 expression in cancer tissues. Breast cancer tissue was obtained from 184 female subjects with primary breast cancer. According to hormonal status patients were divided into two groups - 64 belonged to the premenopausal group and 120 to postmenopausal group. Each patient underwent mammectomy and axillary lymphadenectomy. c-erbB-2 protooncogene was detected in 54% cases, and was correlated with infiltrating type of cancer growth, as well as larger tumor size. The presence of p53 antioncogene was observed only in 33% of cases, mainly in infiltrating duct carcinomas. The incidence of c-erbB-2 and p53 positive cases was higher among subjects, whose ultrasound and mammography revealed malignancy. There was no correlation found between of c-erbB-2 expression and axillary lymph nodes involvement It seems probable, that c-erbB-2 and p53 status of cancer tissue may prove to be useful in assessment of the level of biological aggressiveness in breast carcinomas and hence can be used as a prognostic factor.

Mutations in p53, p53 protein overexpression and breast cancer survival

p53 is an important tumour suppressor gene that encodes p53 protein, a molecule involved in cell cycle regulation and has been inconsistently linked to breast cancer survival. Using archived tumour tissue from a population-based sample of 859 women diagnosed with breast cancer between 1996 and 1997, we determined p53 mutations in exons 5–8 and p53 protein overexpression. We examined the association of p53 mutations with overexpression and selected tumour clinical parameters. We assessed whether either p53 marker was associated with survival through 2002, adjusting for other tumour markers and prognostic factors. The prevalence of protein overexpression in the tumour was 36% (307/859) and of any p53 mutation was 15% (128/859). p53 overexpression was positively associated with the presence of any p53 mutation (odds ratio [OR]= 2.2, 95% confidence interval [CI]= 1.5–3.2), particularly missense mutations (ER = 7.0, 95% CI = 3.6–13.7). Negative oestrogen and progesterone receptor (ER/PR) status was positively associated with both p53 protein overexpression (= 2.6, 95% CI = 1.7–4.0) and p53 mutation (OR = 3.9, 95% CI = 2.4–6.5). Any p53 mutation and missense mutations, but not p53 protein overexpression, were associated with breast cancer-specific mortality (hazard ratio [HR]= 1.7, 95% CI = 1.0–2.8; HR = 2.0, 95% CI = 1.1–3.6, respectively) and all-cause mortality (HR = 1.5, 95% CI = 1.0–2.4; HR = 2.0, 95% CI = 1.2–3.4, respectively); nonsense mutations were associated only with breast cancer-specific mortality (HR = 3.0, 95% CI = 1.1–8.1). These associations however did not remain after adjusting for ER/PR status. Thus, in this population-based cohort of women with breast cancer, although p53 protein overexpression and p53 mutations were associated with each other, neither independently impacted breast cancer-specific or all-causing mortality, after considering ER/PR status.

Expression patterns and prognostic value of Bag-1 and Bcl-2 in breast cancer

Introduction

Bcl-2 antanogene-1 (Bag-1) binds the anti-apoptotic mediator Bcl-2, and enhances its activity. Bcl-2 and Bag-1 are associated with chemotherapy resistance in cancer cells. Drugs that target Bcl-2 are currently in clinical development. The purpose of the present study was to examine expression patterns of Bag-1 in a large cohort of breast tumors and to assess the association with Bcl-2, estrogen receptor, progesterone receptor and Her2/neu, and other clinical/pathological variables.

Methods

Tissue microarrays containing primary specimens from 638 patients with 10-year follow-up were employed, and the expression of Bag-1, Bcl-2, estrogen receptor, progesterone receptor and Her2/neu was assessed using our automated quantitative analysis method. We used cytokeratin to define pixels as breast cancer (tumor mask) within the array spot, and we measured biomarker expression within the mask using Cy5 conjugated antibodies.

Results

High Bcl-2 expression was associated with improved survival in the entire cohort and in the node-positive subset (P = 0.008 and P = 0.002, respectively). High Bag-1 expression was associated with improved survival in the node-positive subset (P = 0.006). On multivariable analysis, neither Bcl-2 nor Bag-1 retained their independence as prognostic markers. Strong associations were found between Bag-1, Bcl-2, estrogen receptor and progesterone receptor.

Conclusion

Bag-1 and Bcl-2 expression in breast tumors is associated with improved outcome and steroid receptor positivity. Evaluation of Bcl-2 and Bag-1 expression in breast cancer may identify a subset of patients with a favorable prognosis, who might not benefit from chemotherapy or who might benefit from Bcl-2 targeting agents in addition to antihormonal therapy.

Reduced mRNA and protein expression of BCL-2 versus decreased mRNA and increased protein expression of BAX in breast cancer brain metastases: a real-time PCR and immunohistochemical evaluation

OBJECTIVES

Brain metastases are an increasingly common complication in breast cancer patients. Apoptosis regulating genes are promising candidates for further treatment options. We examined the mRNA and protein expression of p53, BCL-2 and BAX in breast cancer brain metastases versus primary tumors.

METHODS

In a two-step approach p53, BCL-2 and BAX mRNA expression in ductal invasive breast cancer brain metastases was examined by: (1) reverse transcription-polymerase chain reaction (RT-PCR) mRNA expression screening (band appearance in relation to an internal standard) and (2) quantitative real-time RT-PCR (CT-values in relation to an internal standard). Protein expression using immunohistochemistry. Results were compared with primary tumors.

RESULTS

We found significantly lower BCL-2 mRNA and protein expression in breast cancer brain metastases versus primary tumors. P53 mRNA and protein expression was also lower in metastases. However, this difference was only significant on mRNA but not on the protein level. BAX expression evaluation revealed was contradictory results: mRNA expression was significantly lower whereas protein expression was significantly higher in metastatic lesions.

DISCUSSION

The mRNA and protein expression of p53 and BCL-2 seems to be reduced in breast cancer brain metastases. BAX mRNA and protein may be regulated differentially in metastatic lesions.

Steroids and receptors in canine mammary cancer

The aims of this study were to investigate the serum and tissue content of androgens and estrogens in canine inflammatory mammary carcinomas (IMC) as well as in non-inflammatory malignant mammary tumors (MMT), and assessed the immunoexpression of estrogen and androgen receptors using immunohistochemistry. Profiles for the androgens dehydroepiandrosterone (DHEA), androstenedione (A4), and testosterone (T), and for the estrogens 17beta estradiol (E2) and estrone-sulphate (SO4E1) were measured both in tissue homogenates and in serum of MMT and IMC by EIA techniques in 42 non-inflammatory malignant mammary tumors (MMT) and in 14 inflammatory mammary carcinomas (IMC), prospectively collected from 56 female dogs. Androgen receptor (AR) and estrogen receptor alpha (ERalpha) and beta (ERbeta) expression was studied using immunohistochemistry (strepavidin-biotin-peroxidase method) in samples of 32 MMT and 14 IMC, and counted by a computer image analyzer. IMC serum and tissue levels of androgens were significantly higher than MMT levels. Tissue content of estrogens was also significantly higher in IMC than in MMT. Serum values of SO4E1 were significantly higher in IMC, but serum levels of E2 were significantly lower in IMC compared to MMT cases. Medium-high androgen receptor intensity was observed in 64.28% of IMC and 40.62% of MMT. No important differences were found between ERalpha expression in IMC (100% negative) and MMT (90% negative). ERbeta and AR were intensely expressed in highly malignant inflammatory mammary carcinoma cells. To our knowledge, this is the first report relative to AR immunohistochemistry in canine mammary cancer and to estrogens or androgens in serum of dogs with benign or malignant mammary tumors.

The role of p53 mutations as a prognostic factor and therapeutic target in inflammatory breast cancer

Inflammatory breast cancer is a rare but lethal form of locally advanced breast cancer. Despite improvements in survival with the advent of multidisciplinary treatment regimens, 5-year survival rates remain disappointing, at approximately 30%. Numerous molecular markers have been investigated for their potential as useful prognostic and predictive markers of treatment response that would impact on the management of inflammatory breast cancer. This review discusses the current status of p53 mutations both as a prognostic marker and as a potential target for directed therapies.

TIP30 regulates apoptosis-related genes in its apoptotic signal transduction pathway

AIM: To investigate the role of TIP30 in apoptotic signal pathway in hepatoblastoma cells and to provide a basis for TIP30 as a gene therapy candidate in the regression of hepatoblastoma cells.

METHODS: Apoptosis of human hepatoblastoma cell lines HepG2 (p53 wild), Hep3B (p53 null) and PLC/RPF/5 (p53 mutant) infected with Ad-TIP30 (bearing a wild type human Tip30 gene) were analyzed and p53, Bax and Bcl-xl expression levels were compared among these cells. MTT assay, DNA fragmentation, in situ 3’ end labeling of DNA, annexin-V FITC staining were used to detect cell death and apoptosis in cells at various time intervals subsequent to infection, and to determine whether TIP30 had an effect on the expression levels of some apoptosis-related gene products such as Bax, p53 and Bcl-xl. A similar time course experiment was performed by Western blotting.

RESULTS: In MTT assay, the viability of HepG2 cells decreased significantly from 99.7% to 10% and displayed more massive cell death within 5-8 d than Hep3B and PLC/RPF/5 cells, with their viability decreased from 97.8% to 44.3% and 98.1% to 50.4%, respectively. In annexin-V FITC assay, the percentage of apoptosis cells in HepG2 cells was two to three-fold higher than that in control cells (infected with Ad-GFP), two-fold higher than that in Hep3B cells and 1.4-fold higher than that in PLC/RPF/5 cells 36 h after infection, respectively. Moreover, in HepG2 cells, the p53 began to increase 6-8 h after infection, reaching a maximum level between 8 and 12 h after infection and then dropped. Bax showed a similar increase in the cells as p53 reached the maximum at 8-12 h and subsequently decreased. Interestingly, Bcl-xl protein levels were down regulated during 24 to 36 h after Ad-TIP30 infection. In contrast, ectopic expression of TIP30 in Hep3B and PLC/RPF/5 cells had no effect on the regulation of Bax expression, but had an effect on Bcl-xl levels. In comparison with HepG2 cells, these data suggested that up-regulation of p53 levels by TIP30 might be a pre-requisite for Bax and Bax/Bcl-xl ratio increase. We hypothesized that TIP30 might regulate Bax gene partly through p53, which sensitizes cells to apoptosis by involving a p53 apoptosis signal transduction pathway.

CONCLUSION: TIP30 plays an important role in predisposing hepatoblastoma cells to apoptosis through regulating expression levels of these genes. Ad-TIP30 carrying exogenous TIP30-anti-tumor genes may be regarded as a potential candidate for the treatment of hepatocellular carcinoma.