Involvement of microRNAs in Androgen Receptor-dependent Breast Cancers

Triple negative breast cancer (TNBC) is a very aggressive tumor subtype characterized by the lack of expression of estrogen receptor 1 (ESR1), due in the most of cases to an increased expression of DNA methyltransferases (DNMTs) and hypermethylation in CpG islands, resulting in gene silencing. Furthermore, in ESR1- negative breast cancers, androgen receptor (AR) is highly expressed and some studies suggest that it can drive tumor progression and might represent a therapeutic target. A correlation between microRNAs, small non-coding RNAs that regulate gene expression, and DNMTs was investigated in a TNBC cell line to restore a normal methylation pattern of ESR1, leading to its re-expression and conferring again sensitivity to selective estrogen receptor modulators (SERMs). miR-148A and miR-29B were found to be involved in the reduction of the expression of DNMT1 and DNMT3A and in a slight increase of ESR1 expression, but not at protein level. Then, we found a down-regulation of AR by miRs-7, -9, -27a, -27b, -29a, -29b, -29c, -127-3p, -127-5p and -376 at 48h post transfection and an up-regulation by miR-15a and miR-16 at every time considered. We concomitantly investigated a possible increase of Tamoxifen, Herceptin and Metformin sensitivity after AR silencing in MDA-MB 453 and T-47D cell lines. Cells seemed more sensitive when silenced for AR only in MDA-MB-453 at 24h post Tamoxifen treatment. Studies on Metformin have basically confirmed an increase of drug sensitivity due to AR silencing in both cell lines. Analysis of Herceptin showed how MDA-MB 453 samples silenced for AR have a slight decrease in the percentage of proliferating cells, demonstrating a possible increase in the response to treatment. These preliminary data provide the basis for further study of the modulation of the expression of AR by microRNAs and it will be interesting to understand the molecular mechanisms underlying these interactions.

Tamoxifen after adjuvant chemotherapy for premenopausal women with lymph node-positive breast cancer: International Breast Cancer Study Group Trial 13-93

PURPOSE: The value of adjuvant tamoxifen after chemotherapy for premenopausal women with breast cancer has not been adequately assessed. PATIENTS AND METHODS: Between 1993 and 1999, International Breast Cancer Study Group Trial 13-93 enrolled 1,246 assessable premenopausal women with axillary node-positive, operable breast cancer. All patients received chemotherapy (cyclophosphamide plus either doxorubicin or epirubicin for four courses followed by immediate or delayed classical cyclophosphamide, methotrexate, and fluorouracil for three courses), which was followed by either tamoxifen (20 mg daily) for 5 years or no further treatment. The primary end point was disease-free survival (DFS). Tumors were classified as estrogen receptor (ER) -positive (n = 735, 59%) if immunohistochemical (IHC) or ligand-binding assays (LBA) were clearly positive. The ER-negative group included all other tumors (n = 511, 41%). A subset of the ER-negative group was defined as ER absent (n = 108, 9%) if IHC staining was none or if the LBA result was 0 fmol/mg cytosol protein. The median follow-up time was 7 years. RESULTS: Tamoxifen improved DFS in the ER-positive cohort (hazard ratio [HR] for tamoxifen v no tamoxifen = 0.59; 95% CI, 0.46 to 0.75; P < .0001) but not in the ER-negative cohort (HR = 1.02; 95% CI, 0.77 to 1.35; P = .89). Tamoxifen had a detrimental effect on patients with ER-absent tumors compared with no tamoxifen in an unplanned exploratory analysis (HR = 2.10; 95% CI, 1.03 to 4.29; P = .04). Patients with ER-positive tumors who achieved chemotherapy-induced amenorrhea had a significantly improved outcome (HR for amenorrhea v no amenorrhea = 0.61; 95% CI, 0.44 to 0.86; P = .004), whether or not they received tamoxifen. CONCLUSION: Tamoxifen after adjuvant chemotherapy significantly improved treatment outcome in premenopausal patients with endocrine-responsive disease, but its use as adjuvant therapy for patients with ER-negative tumors is not recommended.

Re-evaluating adjuvant breast cancer trials: assessing hormone receptor status by immunohistochemical versus extraction assays

BACKGROUND: Tumor levels of steroid hormone receptors, a factor used to select adjuvant treatment for early-stage breast cancer, are currently determined with immunohistochemical assays. These assays have a discordance of 10%-30% with previously used extraction assays. We assessed the concordance and predictive value of hormone receptor status as determined by immunohistochemical and extraction assays on specimens from International Breast Cancer Study Group Trials VIII and IX. These trials predominantly used extraction assays and compared adjuvant chemoendocrine therapy with endocrine therapy alone among pre- and postmenopausal patients with lymph node-negative breast cancer. Trial conclusions were that combination therapy provided a benefit to pre- and postmenopausal patients with estrogen receptor (ER)-negative tumors but not to ER-positive postmenopausal patients. ER-positive premenopausal patients required further study. METHODS: Tumor specimens from 571 premenopausal and 976 postmenopausal patients on which extraction assays had determined ER and progesterone receptor (PgR) levels before randomization from October 1, 1988, through October 1, 1999, were re-evaluated with an immunohistochemical assay in a central pathology laboratory. The endpoint was disease-free survival. Hazard ratios of recurrence or death for treatment comparisons were estimated with Cox proportional hazards regression models, and discriminatory ability was evaluated with the c index. All statistical tests were two-sided. RESULTS: Concordance of hormone receptor status determined by both assays ranged from 74% (kappa = 0.48) for PgR among postmenopausal patients to 88% (kappa = 0.66) for ER in postmenopausal patients. Hazard ratio estimates were similar for the association between disease-free survival and ER status (among all patients) or PgR status (among postmenopausal patients) as determined by the two methods. However, among premenopausal patients treated with endocrine therapy alone, the discriminatory ability of PgR status as determined by immunohistochemical assay was statistically significantly better (c index = 0.60 versus 0.51; P = .003) than that determined by extraction assay, and so immunohistochemically determined PgR status could predict disease-free survival. CONCLUSIONS: Trial conclusions in which ER status (for all patients) or PgR status (for postmenopausal patients) was determined by immunohistochemical assay supported those determined by extraction assays. However, among premenopausal patients, trial conclusions drawn from PgR status differed--immunohistochemically determined PgR status could predict response to endocrine therapy, unlike that determined by the extraction assay.

MEN1 Gene Mutation and Reduced Expression Are Associated With Poor Prognosis in Pulmonary Carcinoids

Context: MEN1 gene alterations have been implicated in lung carcinoids, but their effect on gene expression and disease outcome is unknown. Objective: Our objective was to analyze MEN1 gene and expression anomalies in lung neuroendocrine neoplasms and their correlations with clinicopathologic data and disease outcome. Design: We examined 74 lung neuroendocrine neoplasms including 58 carcinoids and 16 high-grade neuroendocrine carcinomas (HGNECs) for MEN1 mutations (n = 70) and allelic losses (n = 69), promoter hypermethylation (n = 65), and mRNA (n = 74) expression. Results were correlated with disease outcome. Results: MEN1 mutations were found in 7 of 55 (13%) carcinoids and in 1 HGNEC, mostly associated with loss of the second allele. MEN1 decreased expression levels correlated with the presence of mutations (P = .0060) and was also lower in HGNECs than carcinoids (P = .0024). MEN1 methylation was not associated with mRNA expression levels. Patients with carcinoids harboring MEN1 mutation and loss had shorter overall survival (P = .039 and P = .035, respectively) and low MEN1 mRNA levels correlated with distant metastasis (P = .00010) and shorter survival (P = .0071). In multivariate analysis, stage and MEN1 allelic loss were independent predictors of prognosis. Conclusion: Thirteen percent of pulmonary carcinoids harbor MEN1 mutation associated with reduced mRNA expression and poor prognosis. Also in mutation-negative tumors, low MEN1 gene expression correlates with an adverse disease outcome. Hypermethylation was excluded as the underlying mechanism.

CIP4 and Src in Promoting the Migration and Invasion of Breast Cancers

Cellular invasion represents a critical early step in the metastatic cascade, and many proteins have been identified as part of an “invasive signature.” The non-receptor tyrosine kinase Src is commonly upregulated in breast cancers, often in conjunction with overexpression of EGFR. Signaling from this pathway stimulates cell proliferation, migration, and invasion and frequently involves proteins that regulate the cytoskeleton. My data demonstrates that inhibition of Src, using the small-molecule inhibitor dasatinib, impairs cellular migration and invasion. Furthermore, Src inhibition sensitizes the cells to the effects of the chemotherapeutic doxorubicin resulting in dramatic, synergistic inhibition of proliferation with combination treatments. The Src-targeted protein CIP4 (Cdc42-interacting protein 4) associates with curved plasma membranes to scaffold complexes of Cdc42 and N-WASp. In these experiments, I show that CIP4 overexpression correlates with triple-negative biomarker status, cellular migration, and invasion of (breast cancer cells. Inhibition of CIP4 expression significantly decreases migration and invasion. Furthermore, I demonstrate the novel finding that CIP4 localizes to invadopodia, which are finger-like projections of the actin cytoskeleton that are associated with matrix degradation and cellular invasion. Depletion of CIP4 in invasive cells impairs the formation of invadopodia and the degradation of gelatin. Therefore, CIP4 is a critical component of the invasive phenotype acquired by human breast cancer cells. In this body of work, I propose a model in which CIP4 promotes actin polymerization by stabilizing the active conformation of N-WASp. CIP4 and N-WASp are both phosphorylated by Src, implicating this pathway in Src-dependent cytoskeletal rearragement. This represents a novel role for F-BAR proteins in migration and invasion.

Active immunosurveillance in the tumor microenvironment of colorectal cancer is associated with low frequency tumor budding and improved outcome.

Tumor budding (single tumor cells or small tumor cell clusters) at the invasion front of colorectal cancer (CRC) is an adverse prognostic indicator linked to epithelial-mesenchymal transition. This study characterized the immunogenicity of tumor buds by analyzing the expression of the major histocompatibility complex (MHC) class I in the invasive tumor cell compartment. We hypothesized that maintenance of a functional MHC-I antigen presentation pathway, activation of CD8+ T-cells, and release of antitumoral effector molecules such as cytotoxic granule-associated RNA binding protein (TIA1) in the tumor microenvironment can counter tumor budding and favor prolonged patient outcome. Therefore, a well-characterized multipunch tissue microarray of 220 CRCs was profiled for MHC-I, CD8, and TIA1 by immunohistochemistry. Topographic expression analysis of MHC-I was performed using whole tissue sections (n = 100). Kirsten rat sarcoma viral oncogene homolog (KRAS) and B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations, mismatch repair (MMR) protein expression, and CpG-island methylator phenotype (CIMP) were investigated. Our results demonstrated that membranous MHC-I expression is frequently down-regulated in the process of invasion. Maintained MHC-I at the invasion front strongly predicted low-grade tumor budding (P = 0.0004). Triple-positive MHC-I/CD8/TIA1 in the tumor microenvironment predicted early T-stage (P = 0.0031), absence of lymph node metastasis (P = 0.0348), lymphatic (P = 0.0119) and venous invasion (P = 0.006), and highly favorable 5-year survival (90.9% vs 39.3% in triple-negative patients; P = 0.0032). MHC-I loss was frequent in KRAS-mutated, CD8+ CRC (P = 0.0228). No relationship was observed with CIMP, MMR, or BRAF mutation. In conclusion, tumor buds may evade immune recognition through downregulation of membranous MHC-I. A combined profile of MHC-I/CD8/TIA1 improves the prognostic value of antitumoral effector cells and should be preferred to a single marker approach.

Impact of p53 Status on Radiosensitization of Tumor Cells by MET Inhibition-Associated Checkpoint Abrogation

Signaling via the MET receptor tyrosine kinase has been implicated in crosstalk with cellular responses to DNA damage. Our group previously demonstrated that MET inhibition in tumor cells with deregulated MET activity results in radiosensitization via downregulation of the ATR-CHK1-CDC25 pathway, a major signaling cascade responsible for intra-S and G2/M cell cycle arrest following DNA damage. Here we aimed at studying the potential therapeutic application of ionizing radiation in combination with a MET inhibitor, EMD-1214063, in p53-deficient cancer cells that harbor impaired G1/S checkpoint regulation upon DNA damage. We hypothesized that upon MET inhibition, p53-deficient cells would bypass both G1/S and G2/M checkpoints, promoting premature mitotic entry with substantial DNA lesions and cell death in a greater extent than p53-proficient cells. Our data suggest that p53-deficient cells are more susceptible to EMD-1214063 and combined treatment with irradiation than wildtype p53 lines as inferred from elevated γH2AX expression and increased cytotoxicity. Furthermore, cell cycle distribution profiling indicates constantly lower G1 and higher G2/M population as well as higher expression of a mitotic marker p-histone H3 following the dual treatment in p53 knockdown isogenic variant, compared to the parental counterpart. IMPLICATIONS The concept of MET inhibition-mediated radiosensitization enhanced by p53 deficiency is of high clinical relevance, since p53 is frequently mutated in numerous types of human cancer. The current data point for a therapeutic advantage for an approach combining MET targeting along with DNA damaging agents for MET positive/p53 negative tumors.

Clinical Significance of NOTCH1 and NOTCH2 Expression in Gastric Carcinomas: An Immunohistochemical Study.

BACKGROUND NOTCH signaling can exert oncogenic or tumor suppressive functions and can contribute to chemotherapy resistance in cancer. In this study, we aimed to clarify the clinicopathological significance and the prognostic and predictive value of NOTCH1 and NOTCH2 expression in gastric cancer (GC). METHODS NOTCH1 and NOTCH2 expression was determined immunohistochemically in 142 primarily resected GCs using tissue microarrays and in 84 pretherapeutic biopsies from patients treated by neoadjuvant chemotherapy. The results were correlated with survival, response to therapy, and clinico-pathological features. RESULTS Primarily resected patients with NOTCH1-negative tumors demonstrated worse survival. High NOTCH1 expression was associated with early-stage tumors and with significantly increased survival in this subgroup. Higher NOTCH2 expression was associated with early-stage and intestinal-type tumors and with better survival in the subgroup of intestinal-type tumors. In pretherapeutic biopsies, higher NOTCH1 and NOTCH2 expression was more frequent in non-responding patients, but these differences were statistically not significant. CONCLUSION Our findings suggested that, in particular, NOTCH1 expression indicated good prognosis in GC. The close relationship of high NOTCH1 and NOTCH2 expression with early tumor stages may indicate a tumor-suppressive role of NOTCH signaling in GC. The role of NOTCH1 and NOTCH2 in neoadjuvantly treated GC is limited.

Application of cell line based genomic predictors to predict response to targeted therapies in breast cancer

Cancer cell lines can be treated with a drug and the molecular comparison of responders and non-responders may yield potential predictors that could be tested in the clinic. It is a bioinformatics challenge to apply the cell line-derived multivariable response predictors to patients who respond to therapy. Using the gene expression data from 23 breast cancer cell lines, I developed three predictors of dasatinib sensitivity by selecting differentially expressed genes and applying different classification algorithms. The performance of these predictors on independent cell lines with known dasatinib response was tested. The predictor based on weighted voting method has the best overall performance. It correctly predicted dasatinib sensitivity in 11 out of 12 (92%) breast and 17 out of 23 (74%) lung cancer cell lines. These predictors were then applied to the gene expression data from 133 breast cancer patients in an attempt to predict how the patients might respond to dasatinib therapy. Two predictors identified 13 patients in common to be dasatinib sensitive. Sixty two percent of these cases are triple negative (ER-negative, HER2-negative and PR-negative) and 76% are double negative. The result is consistent with the findings from other studies, which identified a target population for dasatinib treatment to be triple negative or basal breast cancer subtype. In conclusion, we think that the cell line-derived dasatinib classifiers can be applied to the human patients. ^

Polycomb repressive complex 2 and induced basal-like breast cancer phenotype mediated by cyclin E/Cdk2

Despite of much success of breast cancer treatment, basal-like breast cancer subtype still presented as a clinical challenge to mammary oncologist for its lack of available targeted therapy owing to their negative expression of targeted molecules, such as PgR, ERα and Her2. These molecules are all critical regulators in mammary gland development. EZH2, a histone methyltransferase, by forming Polycomb Repressive Complex 2(PRC2) can directly suppress a large array of developmental regulators. Overexpression of cyclin E has also been correlated with basal-like (triple-negative) breast cancer and poor prognosis. We found an important functional link between these two molecules. Cyclin E/Cdk2 can enhance PRC2 function by phosphorylating a specific residue of EZH2, threonine 416 and increasing EZH2's ability to complex with SUZ12. This regulation would further recruit whole PRC2 complex to core promoter regions of these developmental regulators. The local enrichment of PRC2 complex would then trimethylate H3K27 around the core promoter regions and suppress the expression of targeted genes, which included PgR, ERα, erbB2 and BRCA1. This widespread gene suppressive effect imposed by highly active PRC2 complex would then transform the lumina) type cell to adopt a basal-like phenotype. This finding suggested deregulated Cdk2 activity owing to cyclin E overexpression may contribute to basal phenotype through enhancing epigenetic silencing effects by regulating PRC2 function. Inhibition of Cdk2 activity in basal-like cancer cells may help release the suppression, reexpress the silenced genes and become responsive to existing anti-hormone or anti-Her2 therapy. From this study, the mechanisms described here provided a rationale to target basal-like breast cancer by new combinational therapy of Cdk2 inhibitors together with Lapatinib, or Aromatin. ^

Rare breast cancer: adenoid cystic carcinoma treated in a cancer reference center between 2001 and 2013

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Metástases cerebrais do cancro de mama : estudo da população das doentes do serviço de oncologia médica do HSM - CHLN

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Systematic proteomic strategies to map the human signaling landscape

Thesis (Ph.D.)--University of Washington, 2016-05

Evaluating the evidence for targeting FOXO3a in breast cancer:a systematic review

Background: Tumour cells show greater dependency on glycolysis so providing a sufficient and rapid energy supply for fast growth. In many breast cancers, estrogen, progesterone and epidermal growth factor receptor-positive cells proliferate in response to growth factors and growth factor antagonists are a mainstay of treatment. However, triple negative breast cancer (TNBC) cells lack receptor expression, are frequently more aggressive and are resistant to growth factor inhibition. Downstream of growth factor receptors, signal transduction proceeds via phosphatidylinositol 3-kinase (PI3k), Akt and FOXO3a inhibition, the latter being partly responsible for coordinated increases in glycolysis and apoptosis resistance. FOXO3a may be an attractive therapeutic target for TNBC. Therefore we have undertaken a systematic review of FOXO3a as a target for breast cancer therapeutics. Methods: Articles from NCBI were retrieved systematically when reporting primary data about FOXO3a expression in breast cancer cells after cytotoxic drug treatment. Results: Increased FOXO3a expression is common following cytotoxic drug treatment and is associated with apoptosis and cell cycle arrest. There is some evidence that metabolic enzyme expression is also altered and that this effect is also elicited in TNBC cells. FOXO3a expression serves as a positive prognostic marker, especially in estrogen (ER) receptor positive cells. Discussion: FOXO3a is upregulated by a number of receptor-dependent and -independent anti-cancer drugs and associates with apoptosis. The identification of microRNA that regulate FOXO3a directly suggest that it offers a tangible therapeutic target that merits wider evaluation.

Function of the PDLIM2 protein in oncogenic Wnt signalling pathways

Aberrant regulation of the Wnt signalling pathway is a recurrent theme in cancer biology. Hyper activation due to oncogenic mutations and paracrine activity has been found in both colon cancer and breast cancer, and continues to evolve as a central mechanism in oncogenesis. PDLIM2, a cytoskeletal PDZ protein, is an IGF-1 regulated gene that is highly expressed in cancer cell lines derived from metastatic tumours. Suppression of PDLIM2 inhibits polarized cell migration, reverses the Epithelial to Mesenchymal transition (EMT) phenotype, suppresses the transcription of β-catenin target genes, and regulates gene expression of key transcription factors in EMT. This thesis investigates the mechanism by which PDLIM2 contributes to the maintenance of Wnt signalling in cancer cells. Here we show that PDLIM2 is a critical regulator of the Wnt pathway by regulating β-catenin at the adherens juctions, as also its transcriptional activity by the interaction of PDLIM2 with TCF4 at the nucleus. Evaluation of PDLIM2 in macrophages and co-culture studies with cancer cells and fibroblasts showed the influence exerted on PDLIM2 by paracrine cues. Thus, PDLIM2 integrates cytoskeleton signalling with gene expression by modulating the Wnt signalling pathway and reconciling microenvironmental cues with signals in epithelial cells. Negative correlation of mRNA and protein levels in the triple negative breast cancer cell BT549 suggests that PDLIM2 is part of a more complex mechanism that involves transcription and posttranslational modifications. GST pulldown studies and subsequent mass spectrometry analysis showed that PDLIM2 interacts with 300 proteins, with a high biological function in protein biosynthesis and Ubiquitin/proteasome pathways, including 13 E3 ligases. Overall, these data suggest that PDLIM2 has two distinct functions depending of its location. Located at the cytoplasm mediates cytoskeletal re-arrangements, whereas at the nucleus PDLIM2 acts as a signal transduction adaptor protein mediating transcription and ubiquitination of key transcription factors in cancer development.