Biomarker discovery using a comparative omics approach in a mouse model developing heterogeneous mammary cancer subtypes

Identification of biomarkers for early breast cancer detection in blood is a challenging task, since breast cancer is a heterogeneous disease with a wide range of tumor subtypes. This is envisioned to result in differences in serum protein levels. The p53(R270H/+) WAPCre mouse model is unique in that these mice spontaneously develop both ER- and ER+ tumors, in proportions comparable to humans. Therefore, these mice provide a well-suited model system to identify human relevant biomarkers for early breast cancer detection that are additionally specific for different tumor subtypes. Mammary gland tumors were obtained from p53(R270H/+) WAPCre mice and cellular origin, ER, and HER2 status were characterized. We compared gene expression profiles for tumors with different characteristics versus control tissue, and determined genes differentially expressed across tumor subtypes. By using literature data (Gene Ontology, UniProt, and Human Plasma Proteome), we further identified protein candidate biomarkers for blood-based detection of breast cancer. Functional overrepresentation analysis (using Gene Ontology, MSigDB, BioGPS, Cancer GeneSigDB, and proteomics literature data) showed enrichment for several processes relevant for human breast cancer. Finally, Human Protein Atlas data were used to obtain a prioritized list of 16 potential biomarkers that should facilitate further studies on blood-based breast cancer detection in humans.     

Prognostic evaluation of breast cancer in cytologic specimens

OBJECTIVE: To evaluate prognostic factors in breast cancer using cytologic samples and to determine the correlation between those factors and ploidy. STUDY DESIGN: Two hundred sixteen fine needle aspirates from patients with primary breast cancer were analyzed for expression of estrogen receptors (ERs), progesterone receptors (PRs), Ki-67 antigen, expression of p53 tumor suppressor gene and overexpression of c-erbB-2 using a standard immunochemical method. Not all subjects had all biomarker information because of the study design (c-erbB2 added later). The specimens were analyzed also for ploidy. We used the SAMBA 4000 image analysis system for quantification of the percent of cells stained positively by the different immunocytochemical stains andfor ploidy. RESULTS: A significant correlation wasfound between ER and PR and between Ki-67 and positive p53. Steroid receptor content was not significantly related to p53, Ki-67 or c-erbB2. No correlation was found between c-erbB2 and the other biomarkers. Ploidy had a significant correlation with all the biomarkers used. CONCLUSION: A reliable and rapid evaluation of markers for breast cancer can be achieved by measuring cells stained positively by immunocytochemical stains, as well as ploidy, by means of an image analysis system. ER, PR Ki-67, p53 and c-erbB2 had a significant correlation with ploidy and overall prognostic value in breast cancer.     

非小细胞肺癌组织中VEGF与P53蛋白表达及意义

目的:探讨VEGF和P53在非小细胞肺癌(NSCLC)中的表达及其生物学行为的关系。方法:采用免疫组织化学方法,对病理确诊的62例非小细胞肺癌组织进行VEGF和P53表达的检测。结果:62例非小细胞肺癌VEGF阳性表达率58.1%(36/62),其表达与NSCLC的组织分化程度、生存期有相关性(P<0.05),与组织学类型、有无淋巴结转移、临床病理分期无关。P53阳性表达率46.8%(29,62),表达与肿瘤组织类型、TNM分期、有无淋巴结转移无关(P<0.05)。结论:VEGF和P53可作为评价非小细胞肺癌预后的重要指标。用免疫组化检测出P53蛋白可间接反映P53基因的突变。本组资料检测的结果显示,P53基因阳性表达率46.8% (29/62),表明近一半肺癌病例已失去P53蛋白的抑癌功能,且P53基因的突变可能与非小细胞肺癌的发生有关。P53和VEGF都是潜在的新型肿瘤表型标志物,它们的检测可作为肿瘤病理分级诊断的主要参考依据。同时检测P53和VEGF的表达状态,可通过肿瘤血管形成的生物学行为信息,进一步研究肿瘤血管形成的分子水平调控机制,这有助于抗肿瘤药物的开发研究。     

Cyclooxygenase-2 directly regulates gene expression of P450 Cyp19 aromatase promoter regions pII, pI.3 and pI.7 and estradiol production in human breast tumor cells

The present studies evaluated the direct effects of the presence of human cyclooxygenase-2 (Cox-2) on gene expression of specific promoter regions of the P450 Cyp19 enzyme aromatase enzyme and its product, estradiol, in Cox-2 null estrogen-dependent MCF-7 breast tumor cells and in a stable clone of MCF-7 cells containing transfected Cox-2 cDNA, designated as MCF-7/Cox-2 Clone 10. Clone 10 human breast tumor cells have significantly increased gene expression of total mRNA of the P450 Cyp19 enzyme aromatase, with high levels of gene expression of specific aromatase promoter (p) regions pII, pI.3, and p1.7, with no significant change in mRNA levels of p1.4. Clone 10 human breast tumor cells produced significantly increased amounts of both prostaglandin E2 (PGE2) derived from Cox-2 enzyme activity and estradiol derived from aromatase enzyme activity (p<0.01), compared to MCF-7/vector control cells. The greatest inhibition of PGE2 or estradiol production was observed by the combination of the selective Cox-2 inhibitor celecoxib (25 microM) and the aromatase inhibitor, formestane (10nM) (p<0.01). The greatest anti-proliferative effect in Cox-2 null MCF-7/vector control cells was observed with the combination of 25 microM celecoxib and 10nM formestane but not with 10 microM celecoxib, suggesting that there are Cox-2-independent mechanisms involved in the anti-proliferative effect of this agent at doses greater than 10 microM. Celecoxib (25 microM) also significantly inhibited proliferation of MCF-7/Cox-2 Clone 10 human breast tumor cells, with no further anti-proliferative activity with the addition of 10 nM formestane observed at either 24 or 48 h of treatment. These studies demonstrate that Cox-2 directly regulates gene expression of specific aromatase promoter regions and regulates aromatase enzyme activity. Agents that inhibit Cox-2 or block the biological effects of PGE2 may be useful in significantly limiting aromatase activity and proliferation of human breast tumor cells regardless of the presence of Cox-2. In addition, the unique human breast tumor cell model used in these studies may be a useful tool in identifying the spectrum of activities of agents that block the biological effects of PGE2 and estradiol.     

Comparative expression analysis of four breast cancer subtypes versus matched normal tissue from the same patients

Gene expression studies have been widely used in an effort to identify signatures that can predict clinical progression of cancer. In this study we focused instead on identifying gene expression differences between breast tumors and adjacent normal tissue, and between different subtypes of tumor classified by clinical marker status. We have collected a set of 20 breast cancer tissues, matched with the adjacent pathologically normal tissue from the same patient. The cancer samples representing each subtype of breast cancer identified by estrogen receptor ER(+/-) and Her2(+/-) status and divided into four subgroups (ER+/Her2+, ER+/Her2-, ER-/Her2+, and ER-/Her2-) were hybridized on Affymetrix HG-133 Plus 2.0 microarrays. By comparing cancer samples with their matched normal controls we have identified 3537 overall differentially expressed genes using data analysis methods from Bioconductor. When we looked at the genes in common of the four subgroups, we found 151 regulated genes, some of them encoding known targets for breast cancer treatment. Unique genes in the four subgroups instead suggested gene regulation dependent on the ER/Her2 markers selection. In conclusion, the results indicate that microarray studies using robust analysis of matched tumor and normal samples from the same patients can be used to identify genes differentially expressed in breast cancer tumor subtypes even when small numbers of samples are considered and can further elucidate molecular features of breast cancer.     

Expression of vascular endothelial growth factor and basic fibroblast growth factor receptors in lung cancer

OBJECTIVE: To determine the expression of two angiogenic factors, vascular endothelial growth factor (VEGF) and fibroblast growth factor receptors (FGFR), in non-small cell lung carcinoma (NSCLC) in relation to tumor stage (TN0, TN1, TN2) and in association with the expression of p53 protein, a potential suppressor of tumor angiogenesis. STUDY DESIGN: The immunohistochemical (IHC) expression of VEGF and FGFR was examined in paraffin sections of 56 NSCLC in relation to the presence of lymph node metastases and p53 expression. Nodal status of NSCLC determined: 27 tumors, N0; 16, N1; and 13, N2 stage. Semiquantitative analysis with a score corresponding to IHC staining intensity and percentage of positive cells was used. Statistical analysis was performed with the chi 2 test. RESULTS: A significant association was noted between VEGF and FGFR expression in NSCLC. No relation was found between VEGF, FGFR expression and lymph node metastasis or p53 expression. CONCLUSION: We assume that VEGF and FGFR act in a synergistic manner in NSCLC and that their expression is not related to lymph node metastases. Angiogenesis is a very complex phenomenon and heterogeneous within tumors. Also, it is affected by microenviromental factors.     

Vascular endothelial growth factor (VEGF) and other common tissue prognostic indicators in breast cancer: a case-control study

VEGF is a specific mitogen and survival factor for endothelial cells and a key promoter of angiogenesis in physiological and pathological conditions. Nevertheless, VEGF tissue evaluation in cancer patients as a prognostic factor compared to the conventional histological and biological parameters is still controversial. In this case-control study, tissue VEGF was retrospectively determined by immunohistochemistry and related to T, N, ER, PgR, c-erbB-2, p53, MIB-1 and cyclin D1 in 129 breast cancer patients. Seventy-four of these patients had developed distant metastases postoperatively. The remaining 55 patients had remained disease-free >10 years after surgery. In 17 (13%) of the 129 patients (six with distant metastases and eleven disease-free) tissue and plasma VEGF were concomitantly evaluated. In univariate analysis no significant differences in VEGF and tumor size were found between metastatic and disease-free patients, whereas there were significant differences in N, ER, PgR, c-erbB-2, p53, MIB-1 and cyclin D1 (p ranging from 0.001 to 0.0001). In multivariate analysis VEGF showed less significance than N, ER, c-erbB-2, MIB-1 and cyclin D1 (p = 0.012, p = 0.007, p = 0.005, p = 0.005, p = 0.002 and p = 0.001, respectively). VEGF was a significant unfavorable prognostic indicator only in the N+ subset (p = 0.015), while ER (p = 0.05 and p = 0.021) and MIB-1 (p = 0.031 and p = 0.022) were significant in both the N+ and N- subgroups. In multivariate analysis in the 74 metastatic cases VEGF did not show any significance in relation to disease-free interval and overall survival from the time of mastectomy and from the time of relapse, whereas N and PgR did (p ranging from 0.018 to 0.001). In conclusion, tissue VEGF does not seem a suitable candidate to replace conventional histological and other common biological prognostic factors in breast cancer.     

Metabolic Profiles are Principally Different between Cancers of the Liver,Pancreas and Breast

Molecular profiling of primary tumors may facilitate the classification of patients with cancer into more homogenous biological groups to aid clinical management. Metabolomic profiling has been shown to be a powerful tool in characterizing the biological mechanisms underlying a disease but has not been evaluated for its ability to classify cancers by their tissue of origin. Thus, we assessed metabolomic profiling as a novel tool for multiclass cancer characterization. Global metabolic profiling was employed to identify metabolites in paired tumor and non-tumor liver (n=60), breast (n=130) and pancreatic (n=76) tissue specimens. Unsupervised principal component analysis showed that metabolites are principally unique to each tissue and cancer type. Such a difference can also be observed even among early stage cancers, suggesting a significant and unique alteration of global metabolic pathways associated with each cancer type. Our global high-throughput metabolomic profiling study shows that specific biochemical alterations distinguish liver, pancreatic and breast cancer and could be applied as cancer classification tools to differentiate tumors based on tissue of origin.     

Estrogen-independent effects of ER-α36 in ER-negative breast cancer

Estrogen receptor-alpha 36 (ER-α36) is a variant of ER-α that has been found to be expressed in conventional ER (ER-α66)-negative breast cancer cell lines and human breast cancer samples. In this study, we found that, using immunohistochemical study, ER-α36 expression was significantly higher in ER-negative tumors than in ER-positive tumors although the expression was not associated with other clinicopathological characteristics. We then constructed an ER-α36-specific microRNA hairpin vector and established stable ER-α36 knockdown cells, and found that the knockdown cells were more sensitive to paclitaxel; the c-Jun N-terminal kinase pathway appeared to be involved in the mechanism. Downregulation of ER-α36 also resulted in decreased migration and invasion. These changes were estrogen independent. Our findings indicated that target ER-α36 may be a strategy for treating ER-negative breast cancers.     

Age-associated biomarker profiles of human breast cancer

To explore the hypothesis that aging not only increases breast cancer incidence but also alters breast cancer biology, we correlated patient age and diagnosis with tumor histology, stage and biomarkers independently determined from two different tumor archives: an American collection of approximately 800 paraffin-embedded and immunohistochemically analyzed primary breast cancers, and an European collection of approximately 3000 cryobanked primary breast cancers analyzed by ligand-binding and enzyme immunoassay (EIA). The prognostic biomarkers chosen for comparison represented surrogate measures of tumor: (i). proliferation, growth and genetic instability (mitotic and apoptotic indices, Ki-67/MIB-1-positivity, nuclear grade, p53-positivity), (ii). endocrine-dependence (estrogen receptor (ER), progesterone receptors (PR), pS2, Bcl2), (iii). growth factor receptor-dependence (ErbB2, EGFR/ErbB1), and (iv). angiogenic, invasive and proteolytic potential (uPA, PAI-1, Cathepsin D, VEGF). No biomarker reflecting tumor angiogenic, invasive or proteolytic potential showed a significant correlation with patient age at diagnosis. In contrast, significant inverse correlations (|r|>0.1; P< or =0.05) were observed for all measures of tumor growth and genetic instability as well as growth factor receptor overexpression (ErbB2 or EGFR positivity). Only one marker of endocrine-dependence, ER expression, showed a significant positive correlation with patient age at diagnosis. In summary, these findings support the hypothesis that breast cancer biology is significantly affected by patient age. In particular, breast tumors arising in older patients have slower growth rates, are more likely to be ER-positive, and are less likely to be p53-positive, EGFR-positive or ErbB2-positive.     

Cytoplasmic localization of BAG-1 in leukoplakia and carcinoma of the tongue: correlation with p53 and c-erbB2 in carcinoma

BACKGROUND: The present study evaluated the clinical significance of BAG-1, an antiapoptotic protein, in leukoplakia and carcinoma of the tongue. METHODS: BAG-1 expression was evaluated by immunohistochemistry in paraffin-embedded tissues of leukoplakia (n=25) and carcinoma of the tongue (n=61). RESULTS: Cytoplasmic expression was predominantly seen in 80% and 70% of patients with leukoplakia and carcinoma, respectively. BAG-1 expression was found to be significantly lower in tobacco users than in non-tobacco users. BAG-1 expression in tobacco-using leukoplakia and carcinoma patients was compared by grouping the carcinoma patients according to lymph node status and disease stage. Carcinoma patients with tumor-positive lymph nodes had significantly lower BAG-1 expression than patients with negative lymph nodes and leukoplakia. Further, a trend towards an inverse correlation was observed with p53 and c-erbB2. In univariate and multivariate survival analysis, patient subgroups with 2+ or 3+ marker positivity (BAG-1 negativity, p53 and c-erbB2 positivity) had a reduced overall survival compared with patient subgroups with 1+ marker positivity or negativity. CONCLUSION: BAG-1 negativity in association with p53 and c-erbB2 positivity identified a subgroup of tongue cancer patients with an aggressive phenotype. Hence, an antiapoptotic protein, BAG-1, was found to be down-regulated in chewing-tobacco-mediated tongue carcinogenesis.     

Role of Activated Rac1/Cdc42 in Mediating Endothelial Cell Proliferation and Tumor Angiogenesis in Breast Cancer

Angiogenesis is a well-established target in anti-cancer therapy. Although vascular endothelial growth factor (VEGF)-mediated angiogenesis apparently requires the Rho GTPases Rac1 and Cdc42, the relevant mechanisms are unclear. Here, we determined that activated Rac1/Cdc42 in MCF-7 breast cancer cells could decrease p53 protein levels and increase VEGF secretion to promote proliferation and tube formation of human umbilical vein endothelial cells (HUVECs). However, these effects are reversed after ubiquitin-proteasome breakage. In exploring potential mechanisms for this relationship, we confirmed that activated Rac1/Cdc42 could enhance p53 protein ubiquitination and weaken p53 protein stability to increase VEGF expression. Furthermore, in a xenograft model using nude mice that stably express active Rac1/Cdc42 protein, active Rac1/Cdc42 decreased p53 levels and increased VEGF expression. Additionally, tumor angiogenesis was inhibited, and p53 protein levels were augmented, by intratumoral injection of the ubiquitin-proteasome inhibitor MG132. Finally in 339 human breast cancer tissues, our analyses indicated that Rac1/Cdc42 expression was related to advanced TNM staging, high proliferation index, ER status, and positive invasive features. In particular, our data suggests that high Rac1/Cdc42 expression is correlated with low wt-p53 and high VEGF expression. We conclude that activated Rac1/Cdc42 is a vascular regulator of tumor angiogenesis and that it may reduce stability of the p53 protein to promote VEGF expression by enhancing p53 protein ubiquitin.     

Immunohistochemical expression of p53 in breast carcinoma is associated with the intron 1 BglII polymorphism of the p53 gene

Breast carcinoma is a public health problem worldwide. It is known that both genetic and environmental factors are important for breast carcinogenesis and that structural and/or functional alterations at p53 gene are commonly observed in breast tumors. In addition, polymorphisms of several genes in either their coding or non-coding sequences have been found related to cancer risk and/or clinicopathological characteristics of tumors. In this study we have evaluated the intron 1 BglII polymorphism of the p53 gene with a PCR-based approach in 117 cases of breast cancer and 102 healthy women and its association with the immunohistochemical expression of p53 in the tumors. The results showed that the presence of the polymorphism (allele 2) is highly associated with the tumor expression of p53 (p<0.0001) and that there is a trend for increased frequency of allele 2 in cases than in controls (p=0.2376). These data suggest that the germ-line variation in the intron 1 of the p53 gene could produce functional or structural changes of the protein that is reflected by its abnormal expression.