Isabella dos Santos Guimarães

Metformin synergistically enhances antiproliferative effects of cisplatin and etoposide in NCI-H460 human lung cancer cells.

OBJECTIVE: To test the effectiveness of combining conventional antineoplastic drugs (cisplatin and etoposide) with metformin in the treatment of non-small cell lung cancer in the NCI-H460 cell line, in order to develop new therapeutic options with high efficacy and low toxicity. METHODS: We used the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and calculated the combination index for the drugs studied. RESULTS: We found that the use of metformin as monotherapy reduced the metabolic viability of the cell line studied. Combining metformin with cisplatin or etoposide produced a synergistic effect and was more effective than was the use of cisplatin or etoposide as monotherapy. CONCLUSIONS: Metformin, due to its independent effects on liver kinase B1, had antiproliferative effects on the NCI-H460 cell line. When metformin was combined with cisplatin or etoposide, the cell death rate was even higher.

Comparison of immunohistochemical analysis with estrogen receptor SP1 and 1D5 monoclonal antibodies in breast cancer

In the present study, we aimed to evaluate estrogen receptor ER-alpha status in 61 breast cancer cases using Sp1 and 1D5 monoclonal antibodies. Tissue array platforms were generated containing samples of breast cancer and positive controls that were assayed by immunohistochemistry applying monoclonal primary antibodies anti-ER alpha, SP1 and 1D5. We noted a high concordance rate (96.7%) between the referred antibodies. Moreover, we calculated the Kappa factor (0.921), indicating that 1D5 and SP1 provided overlapping ERα expression results. Indeed, we observed controversial results only in 2 samples studied, which were ER-negative when stained with 1D5 and ER-positive when assessed with SP1. Total concordance of PS was obtained (Pearson and intraclass CF, 0.7351 and 0.6193, respectively). However, concordance between the antibodies seems to be more accurate in higher PS values. An excellent IS correlation between antibodies was observed throughout the population (Spearmans CF, ρ=0.9150). Following the Allred score, 17 out of 42 positive BC samples diverged, with 1D5 always pointing to weaker staining than SP1. When calculating Spearmans CF of Total Score (TS) within the population, an excellent correlation between both the antibodies (ρ=0.9238) was noted. Nonetheless, the results were less concordant among the BC-positive cases (ρ=0.7743). Indeed, 20 samples were differentially classified using the antibodies (only 3 had higher TS with 1D5). Considering the mean TS of all samples or of invasive ductal carcinoma, SP1 provided higher scores than 1D5 (p<0.05). We recommend the use of the anti-ER RMAb SP1 due to the high probability that the BC ERα status can be determined accurately as the reagent provides higher IS. Therefore, the A-score was higher than the MMAb 1D5. Ultimately, higher IS and A-score decrease the possibility of ERα status misinterpretation and, consequently, inappropriate BC treatment that would compromise the patients quality of life and overall survival. We recommend the use of anti-ER RMAb SP1 due to the high probability that the BC ER status can be determined accurately as the reagent provides higher IS, therefore higher A-score, than the MMAb 1D5.

Abstract 2571: Metformin inhibits proliferation and acts synergistically with paclitaxel and doxorubicin in triple negative breast cancer cell lines

Background: Triple-negative breast cancer (TNBC) is a subtype of breast cancer (BC) characterized by its unique molecular profile, aggressive behavior, distinct patterns of metastasis and unavailability of effective target therapy. Indeed, despite good initial response to chemotherapy, even platinum- or anthracyclines-based, TNBC relapse and mortality rates are high even in early-stage disease. Metformin, one of the most commonly used medications for treatment of type 2 diabetes mellitus, has emerged as a potential anticancer agent. This study aimed to evaluate the combination treatment of metformin, at lower concentrations (10uM), with conventional chemotherapeutic agents on TNBC cell lines. We investigated the combination effect of metformin with doxorubicin (DOX), cisplatin (CDDP) and paclitaxel (PTX). Methods: Three TNBC cell lines (MDAMB-231, HCC-70, HCC-1937) and one luminal BC cell line (MCF-7) were used. Cell proliferation was determined by MTT assay. Clonogenic assay was conducted and apoptosis was analyzed by Annexin V-FITC assay. Western immunoblotting was performed to determine the expression of the downstream targets of PI3K, MAPK and AMPK pathways. Findings: Metformin potently inhibited the proliferation of all BC cell lines in a dose-dependent manner. Likewise, metformin caused a significant dose-dependent reduction in clonogenicity of TNBC cell lines (P Citation Format: Isabella S. Guimaraes, Nayara G. Tessarollo, Laura FRL Oliveira, Roger C. Zampier, Ian V. Silva, Cinthya Sternberg, Leticia BA Rangel. Metformin inhibits proliferation and acts synergistically with paclitaxel and doxorubicin in triple negative breast cancer cell lines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2571. doi:10.1158/1538-7445.AM2015-2571

Abstract 2548: Metformin and everolimus act synergistically with paclitaxel against ovarian cancer

Background: Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy, mostly due to the diagnosis of the disease at advanced stages and to chemoresistance to platinum- and taxane-based standard therapy. EOC comprises a heterogeneous group of diseases classified based on morphologic and molecular-genetic features. High grade serous ovarian cancer is the most prevalent EOC subtype, being followed by the clear cell subtype. Both EOC subtypes are vastly aggressive and frequently acquire the chemoresistant phenotype, thus challenging researchers and clinicians. Notably, hyperactivation of PI3K and MAPK pathways are frequently related to resistance to standard therapies in EOC, thus, metformin (MET) and everolimus (EVE) have emerged as novel therapeutic options against EOC. The present work aimed to investigate the action of MET and EVE, in vitro, in ES-2 (clear cell) and A2780 (serous) cell lines. Methods: Metabolic cell viability (MCV) assays were conducted after the treatment of the cells with MET or EVE in monotherapy and in association with paclitaxel (PAC) by the MTT method. Cell cycle progression was evaluated by flow cytometry/propidium iodide. Apoptosis was analyzed by the annexin V-FITC assay. Western blot was performed to investigate MEK/ERK and PI3K/AKT pathways. Findings: MCV of EOC lineages was reduced by MET and EVE in different concentrations. The combination of MET, at low and safe concentration (10uM), with PAC 100nM reduced the MCV in 56.55% for ES-2, and 71.38% for A2780. Similarly, EVE 0.06 nM and PAC 100 nM decreased the VCM in 66.4% and 73.38% for ES-2 and A2780, respectively. MET 10μm and EVE 0.06nM associated with PAC 12.5nM kept the MCV at levels comparable to PAC 100nM. These findings are of extreme clinical relevance as they reveal that the synergism between MET and EVE with PAC likely maintains the drug citotoxicity at lower concentrations than those associated to its severe and limiting side effects, as neurotoxicity. Annexin-FITC assay was conducted in ES-2 lineage treated with PAC alone and combined with MET or EVE. Low percentage of apoptotic/necrotic cells was observed, which suggests the occurrence of additional processes, such as autophagic cell death. EVE induced ES-2 cell cycle arrest; however, MET, at low concentration, did not cause the same effect. There were no significant cell cycle changes due to the combined treatment of ES-2 with PAC and MET or EVE. Western blot analysis demonstrated that the combination of EVE and PAC increased, whereas MET alone or in combination with PAC decreased the phosphorylation of ERK1/2 and AKT in ES2 cells. Conclusions: Our data suggest that MET or EVE exerts synergistic effect with PAC against EOC, thus opening an avenue to explore novel strategies against this highly lethal disease. Ongoing experiments are sought to elucidate the cellular pathways modulated by MET and EVE alone or in combination with PAC in EOC lineages, as well as the elicited cellular events and mechanisms. Citation Format: Nayara G. Tessarollo, Isabella S. Guimaraes, Taciane Ladislau, Ian Victor Silva, Leticia B. A. Rangel. Metformin and everolimus act synergistically with paclitaxel against ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2548. doi:10.1158/1538-7445.AM2015-2548

Positive crosstalk between EGFR and the TF-PAR2 pathway mediates resistance to cisplatin and poor survival in cervical cancer

Cisplatin-based chemoradiation is the standard treatment for cervical cancer, but chemosensitizing strategies are needed to improve patient survival. EGFR (Epidermal Growth Factor Receptor) is an oncogene overexpressed in cervical cancer that is involved in chemoresistance. Recent studies showed that EGFR upregulates multiple elements of the coagulation cascade, including tissue factor (TF) and the protease-activated receptors (PAR) 1 and 2. Moreover, many G protein-coupled receptors, including PARs, have been implicated in EGFR transactivation. However, the role of coagulation proteins in the progression of cervical cancer has been poorly investigated. Herein we employed cervical cancer cell lines and The Cancer Genome Atlas (TCGA) database to evaluate the role of EGFR, TF and PAR2 in chemoresistance. The SLIGKL-NH2 peptide (PAR2-AP) and coagulation factor VIIa (FVIIa) were used as PAR2 agonists, while cetuximab was used to inhibit EGFR. The more aggressive cell line CASKI showed higher expression levels of EGFR, TF and PAR2 than that of C33A. PAR2 transactivated EGFR, which further upregulated cyclooxygenase-2 (COX2) expression. PAR2-AP decreased cisplatin-induced apoptosis through an EGFR- and COX2-dependent mechanism. Furthermore, treatment of CASKI cells with EGF upregulated TF expression, while treatment with cetuximab decreased the TF protein levels. The RNA-seq data from 309 TCGA samples showed a strong positive correlation between EGFR and TF expression (P = 0.0003). In addition, the increased expression of EGFR, PAR2 or COX2 in cervical cancer patients was significantly correlated with poor overall survival. Taken together, our results suggest that EGFR and COX2 are effectors of the TF/FVIIa/PAR2 signaling pathway, promoting chemoresistance.

Chemosensitizing effects of metformin on cisplatin- and paclitaxel-resistant ovarian cancer cell lines

BACKGROUND Epithelial ovarian cancer (EOC) remains the most lethal gynecologic malignancy. Primary cytoreductive surgery with adjuvant taxane-platinum chemotherapy is the standard treatment to fight ovarian cancer, however, their side effects are severe, and chemoresistance emerges at high rates. Therefore, EOC clinic urges for novel treatment strategies to reverse chemoresistance and to improve the survival rates. Metformin has been shown to act in synergy with certain anti-cancer agents, overcoming chemoresistance in various types of tumors. This paper aims to investigate the use of metformin as a new treatment option for cisplatin- and paclitaxel-resistant ovarian cancer. METHODS The effects of metformin alone or in combination with conventional drugs on resistant EOC cell lines were investigated using the MTT assay for cell proliferation; Flow Cytometry analysis for cell cycle and the mRNA expression was analyzed using the real-time PCR technique. RESULTS We found that metformin exhibited antiproliferative effects in paclitaxel-resistant A2780-PR, and in cisplatin-resistant ACRP cell lines. The combined therapy containing conventional drugs and metformin improved the effect of the treatment in cell proliferation rate, especially in the resistant cells. We found that metformin, in clinical relevant doses, could significantly reduce the mRNA expression of inflammatory cytokines and NF-κB signaling pathway. CONCLUSIONS Taken together, our observations suggest that metformin inhibits the inflammatory pathway induced by paclitaxel and cisplatin treatment. Furthermore, metformin in combination with paclitaxel or cisplatin improved the sensitivity in drug-resistant ovarian cancer cells. Therefore, metformin may be beneficial treatment strategy, particularly in patients with tumors refractory to platinum and taxanes.

Conventional Cancer Treatment

Concurrently with the new discoveries of chemotherapeutic agents, the remarkable scientific and technological development allowed understanding of cell biology of human cancer cells and thereby the emergence of targeted therapy. Although the targeted therapy drugs have had outstanding successes in selected types of cancer, new therapies are not likely to replace cytotoxic agents in the foreseeable future. Rather, clinical trials have demonstrated potent synergy between targeted molecules and traditional cytotoxic agents.

GWAS in Breast Cancer

Breast cancer is the most diagnosed cancer in women, and the second cause of cancerrelated deaths among women worldwide. It is expected that more than 240,000 new cases and 40,450 deaths related to the disease will occur in 2016. It is well known that inherited genetic variants are drivers for breast cancer development. There are many mechanisms through which germline genetic variation affects prognosis, such as BRCA1 and BRCA2 genes, which account for approximately 20% of the increased hereditary risks. Therefore, it is evident that the genetic pathways that underlie cancer development are complex in which networks of multiple alleles confer disease susceptibility and risks. Global analyses through genome-wide association studies (GWAS) have revealed several loci across the genome are associated with the breast cancer. This chapter compiles all breast GWAS released since 2007, year of the first article published in this area, and discuss the future directions of this field. Currently, hundreds of genetic markers are linked to breast cancer, and understanding the underlying mechanisms of these variants might lead to the discover of biomarkers and targets for therapy in patients.

Metformin and mTOR Inhibitors: Allies against Ovarian and Breast Cancers

Cancer is one of the leading causes of death worldwide. Every year 8.2 million people die from the disease. In this context, breast and ovarian cancer are the most incidental among women. Elucidation of cell growth pathways and the observation that these pathways are altered in human cancer have encouraged the search for specific inhibitors. The phosphatidylinositol-3cinase (PI3K)/Protein kinase b (AKT)/Mammalian Target of Rapamycin (mTOR) is an important pathway involved in cell growth, tumorigenesis, cell invasion, and resistance to therapies. This pathway is often activated in breast and ovarian cancers and the deregulation of its signaling can contribute to tumor growth, angiogenesis and metastasis. Metformin is one of the most commonly prescribed antidiabetic drugs in the world whose anticancer effects, mediated by reduced mTOR signaling, have become notable. Therefore, this review provides an overview of signaling pathway PI3K/AKT/mTOR in the ovarian and breast cancers as well as for target therapies of mTOR signaling, with an emphasis on its mechanisms, clinical applicability and future perspectives.

Abstract A28: Osteopontin splicing isoforms expression is modulated by partial epithelial mesenchymal transition in ovarian carcinoma cells.

In ovarian carcinoma (OC), invasive cell properties are supported by epithelial mesenchymal transition (EMT). We previously demonstrated that OPNc, one of the glycophosphoprotein osteopontin splicing isoforms (OPN-SI), activates OC progression. However , the involvement of these OPN-SI in EMT in OC cells has not previously been addressed. We aimed to evaluate the expression of OPN-SI in OC cells induced to EMT by TGFβ. ES2 and A2780 OC cell lines were treated with 10ng/ml of TGFβ in order to induce EMT. The expression of OPN-SI and EMT epithelial (E) (Claudin-3, Claudin-4 and E-cadherin) and mesenchymal (M) (slug, vimentin and N-cadherin) markers was tested by quantitative real time PCR. In both cell lines, OPNa is overexpressed in relation to OPNb and OPNc. Upon treatment with TGFβ, in A2780 cells we observed an upregulation of OPNc. Conversely, OPNa and OPNb were downregulated. In ES2 cells, TGFβ also induced OPNc upregulation, but OPNb expression is activated as well, while OPNa expression is inhibited. In order to validate EMT induction by TGFβ, we tested the expression of E and M markers. In A2780 cells, TGFβ induce the downregulation of E-cadherin, but Claudin-3 and Claudin-4 are upregulated. In ES2 cells, Claudin-3 expression is downregulated in this condition. After TGFβ treatment, in A2780 cells all M markers are downregulated, while in ES2 cells, only N-cadherin expression has been inhibited. Our data indicate that the expression of OPN-SI is modulated by EMT induced by TGFβ and that mostly the oncogenic OPNc is upregulated in this condition. Our data evidence that the expression of OPN-SI is modulated by a partial EMT phenotype induced by TGFβ, which is cell-type specific, and that OPN-SI, specially OPNc, could contribute to this key step on tumor progression in OC cells. Citation Format: Ingridy Celestino, Isabella S. Guimaraes, Leticia B. A. Rangel, Etel R. P. Gimba. Osteopontin splicing isoforms expression is modulated by partial epithelial mesenchymal transition in ovarian carcinoma cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A28.