High VEGFR3 Expression Reduces Doxorubicin Efficacy in Triple-Negative Breast Cancer

Due to the lack of specific targets, cytotoxic chemotherapy still represents the common standard treatment for triple-negative breast patients. Despite the harmful effect of chemotherapy on tumor cells, there is evidence that treatment could modulate the tumor microenvironment in a way favoring the propagation of the tumor. In addition, the lymphangiogenesis process and its factors could be involved in this counter-therapeutic event. In our study, we have evaluated the expression of the main lymphangiogenic receptor VEGFR3 in two triple-negative breast cancer in vitro models, resistant or not to doxorubicin treatment. The expression of the receptor, at mRNA and protein levels, was higher in doxorubicin-resistant cells than in parental cells. In addition, we confirmed the upregulation of VEGFR3 levels after a short treatment with doxorubicin. Furthermore, VEGFR3 silencing reduced cell proliferation and migration capacities in both cell lines. Interestingly, high VEGFR3 expression was significantly positively correlated with worse survival in patients treated with chemotherapy. Furthermore, we have found that patients with high expression of VEGFR3 present shorter relapse-free survival than patients with low levels of the receptor. In conclusion, elevated VEGFR3 levels correlate with poor survival in patients and with reduced doxorubicin treatment efficacy in vitro. Our results suggest that the levels of this receptor could be a potential marker of meager doxorubicin response. Consequently, our results suggest that the combination of chemotherapy and VEGFR3 blockage could be a potentially useful therapeutic strategy for the treatment of triple-negative breast cancer.

Targeting HER2-AXL heterodimerization to overcome resistance to HER2 blockade in breast cancer

Anti-HER2 therapies have markedly improved prognosis of HER2-positive breast cancer. However, different mechanisms play a role in treatment resistance. Here, we identified AXL overexpression as an essential mechanism of trastuzumab resistance. AXL orchestrates epithelial-to-mesenchymal transition and heterodimerizes with HER2, leading to activation of PI3K/AKT and MAPK pathways in a ligand-independent manner. Genetic depletion and pharmacological inhibition of AXL restored trastuzumab response in vitro and in vivo. AXL inhibitor plus trastuzumab achieved complete regression in trastuzumab-resistant patient-derived xenograft models. Moreover, AXL expression in HER2-positive primary tumors was able to predict prognosis. Data from the PAMELA trial showed a change in AXL expression during neoadjuvant dual HER2 blockade, supporting its role in resistance. Therefore, our study highlights the importance of targeting AXL in combination with anti-HER2 drugs across HER2-amplified breast cancer patients with high AXL expression. Furthermore, it unveils the potential value of AXL as a druggable prognostic biomarker in HER2-positive breast cancer.

MicroRNAs as a clue to overcome breast cancer treatment resistance

Breast cancer is the most frequent cancer in women worldwide. Despite the improvement in diagnosis and treatments, the rates of cancer relapse and resistance to therapies remain higher than desirable. Alterations in microRNAs have been linked to changes in critical processes related to cancer development and progression. Their involvement in resistance or sensitivity to breast cancer treatments has been documented by different in vivo and in vitro experiments. The most significant microRNAs implicated in modulating resistance to breast cancer therapies are summarized in this review. Resistance to therapy has been linked to cellular processes such as cell cycle, apoptosis, epithelial-to-mesenchymal transition, stemness phenotype, or receptor signaling pathways, and the role of microRNAs in their regulation has already been described. The modulation of specific microRNAs may modify treatment response and improve survival rates and cancer patients' quality of life. As a result, a greater understanding of microRNAs, their targets, and the signaling pathways through which they act is needed. This information could be useful to design new therapeutic strategies, to reduce resistance to the available treatments, and to open the door to possible new clinical approaches.

miR-503-5p induces doxorubicin resistance in triple-negative breast cancer

1083

Background: Triple-negative breast cancer (TNBC) is an aggressive breast cancer (BC) subtype comprising approximately 15% of BC. Conventional cytotoxic chemotherapies continue to be the mainstay for treatment of this BC, which lacks targetable markers. In this context, microRNAs have been described to have an important role. The aim of this work was to elucidate the function of miR-503-5p in doxorubicin resistance in TNBC. Methods: miR-503-5p expression was evaluated in the TNBC cell line with acquired resistance to doxorubicin (MDA-MB-231R) and its parental cell line (MDA-MB-231), by qRT-PCR. Studies of gain/loss of function of miR-503-5p were carried out in MDA-MB-231 and MDA-MB-231R cells by transient transfection of mimics and inhibitors. Cells were treated with doxorubicin, and viability was measured by flow cytometry and MTT assay. The role of miR-503-5p was also evaluated in vivo by Chicken Chorioallantoic Membrane (CAM) assay. MDA-MB-231 cells transfected with miR-503-5p mimic or scramble miRNA were inoculated onto the CAM of fertilized chicken eggs. After 48 hours, tumours were treated with doxorubicin or supplemented media for 48 hours and tumour growth was measured. miR-503-5p expression was quantified by qRT-PCR in a retrospective cohort of 74 TNBC patients treated with anthracycline + taxane regimens. Overall survival analysis for miR-503-5p in TNBC patients from METABRIC dataset was evaluated by the KM plotter online tool. Results: miR-503-5p was significantly upregulated in the resistant MDA-MB-231R TNBC cell line when compared to its parental cell line MDA-MB-231 (̃3.5-fold; p< 0.0001). Then, gain/loss function assays showed that upregulation of miR-503-5p in MDA-MB-231 cells increased resistance to doxorubicin ( p< 0.0001) and its downregulation in MDA-MB-231R cells had the opposite effect ( p< 0.0001). Moreover, the role of miR-503-5p was also confirmed in the CAM assay in vivo model, where miR-503-5p overexpression inhibited the effect of doxorubicin. In our cohort of patients, miR-503-5p expression levels in core biopsies sampled before preoperative chemotherapy were associated with residual cancer burden (RCB). miR-503-5p expression was significantly higher in patients with poor response to chemotherapy (RCB II and III; median, 95% CI: 0.00055, 0.00024 - 0.00136) than in patients with good response (RCB 0 and I; median, 95% CI: 0.00018, 0.00011 - 0.00034; p = 0.036). Moreover, we confirmed that TNBC patients with high expression of miR-503-5p had worse overall survival than patients with low expression ( p= 0.016). Conclusions: We identified miR-503-5p as a modulator of doxorubicin resistance in TNBC. Our in vitro findings are supported by the clinical data of TNBC patients and in vivo assays. Hence, the inhibition of miR-503-5p may be a promising strategy to improve chemotherapeutic efficacy. Moreover, the expression levels of miR-503-5p may be used as a biomarker for therapy response in TNBC.

Abstract PS19-20: Identification of a novel two-microRNA signature for recurrence prediction in HER2 positive breast cancer

Background: HER2+ breast cancer (BC) is a heterogeneous disease. Despite the novel targeted therapies against HER2, 20% of patients relapse. In this context, the identification of prognostic and predictor biomarkers is needed.MicroRNAs are involved in BC development and prognosis. We aim at assessing the prognostic significance of two micro-RNAs (named as A and B) in HER2+ BC tissue, to propose signature to predict relapse in this setting of patients.Methods: This study was conducted in a cohort of 46 non-consecutive HER2+ BC patients diagnosed at Hospital Clínico València-INCLIVA. All BC patients received standard treatment for localized disease. RNA was isolated from formalin-fixed paraffin-embedded primary tumor and retro-transcribed to cDNA. MicroRNA expression levels were measured by real-time qPCR and results were normalized according to the expression of housekeeping mir-16 miRNA.Non-parametric Mann-Whitney U test was used to ascertain the statistical significance of differences in miRNA expression levels between disease-free and relapse. Receiver operator characteristics (ROC) curves were constructed and AUC, accuracy, specificity and sensitivity, were calculated as a biomarker performance parameter. The best cutoff value was established based on the highest value obtained in ROC curve analysis according to the maximization of the sum of sensitivity and specificity. Kaplan-Meier curves were plotted for disease-free survival (DFS) based on the best cutoff value. As both microRNA showed high correlation (r=0.85), a genetic signature was developed using Principal Component Analysis (PCA) and extracting the first component. MicroRNA targeted genes were downloaded from miRTarBase (release 7.0). Cytoscape (v3.8.0) and ClueGo (v2.5.6) and were used to perform functional enrichment analysis with the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database. To select significant terms/pathways, p-values were adjusted by the Benjamni-Hochberg method (p&lt;0.05). Results: The expression of both microRNA-A and B was higher in the primary tumor of those patients who relapsed after treatment compared to those free of disease (p= 0.003 and 0.0002, respectively). ROC curves demonstrated that microRNA-A and B might discriminate those HER2+ BC patients who relapse. MicroRNA-A predicts relapse with an AUC 0.740, sensitivity of 0.810, specificity of 0.583 and accuracy of 0.689, and microRNA-B presented an AUC 0.821, sensitivity of 0.810, specificity of 0.750, and accuracy of 0.778. The survival analysis showed that microRNA-A and B strongly predicted shorter DFS (p= 0.014 and 0.0012, respectively).Two-microRNA signature combining (PCA1= 99.4% absorbed variance) microRNA-A and microRNA-B expression levels had high performance in discriminating relapsed from non-relapsed HER2+ BC patients (AUC 0.748, accuracy 0.689, sensitivity 1, specificity 0.417). Signature predicted DFS (p= 0.009). Functional enrichment analysis returned 55 significant pathways. Of these, important pathways related to tumorigenesis and response to treatment were enriched. Interestingly, P53 pathway, apoptosis, and cell cycle were in the top 5 enriched pathways. Conclusions: We demonstrated the value of microRNA A and B as potential prognostic biomarkers. High expression was related to poor prognosis in over cohort of HER2+ BC patients. Both microRNAs were able to strongly discriminate patients who will relapse and predict shorter DFS. Moreover, our signature was able to predict the outcome, suggesting a potential prognostic role at diagnosis. Both microRNAs are related to important biological pathways associated to BC progression. Further investigations to optimize the micro-RNA signature are on-going.

Citation Format: Anna Adam-Artigues, Juan Antonio Carbonell-Asíns, Sheila Zúñiga-Trejos, Santiago Moragón, Maria Teresa Martínez, Cristina Hernando, Eduardo Tormo, Octavio Burgués, Ana Lluch, Begoña Bermejo, Pilar Eroles, Juan Miguel Cejalvo. Identification of a novel two-microRNA signature for recurrence prediction in HER2 positive breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-20.

miRNA Expression Analysis: Cell Lines HCC1500 and HCC1937 as Models for Breast Cancer in Young Women and the miR-23a as a Poor Prognostic Biomarker

PURPOSE

The study of breast cancer nearly always involves patients close to menopause or older. Therefore, young patients are mostly underrepresented. Our aim in this study was to demonstrate biological differences in breast cancer of young people using as a model available cell lines derived from people with breast cancer younger than 35 years.

METHODS

Global miRNA expression was analyzed in breast cancer cells from young (HCC1500, HCC1937) and old patients (MCF-7, MDA-MB-231, HCC1806, and MDA-MB-468). In addition, it was compared with same type of results from patients.

RESULTS

We observed a differential profile for 155 miRNAs between young and older cell lines. We identified a set of 24 miRNA associated with aggressiveness that were regulating pluripotency of stem cell-related pathways. Combining the miRNA expression data from cell lines and breast cancer patients, 132 miRNAs were differently expressed between young and old samples, most of them previously found in cell lines. MiR-23a-downregulation was also associated with poor survival in young patients.

CONCLUSIONS

Our results suggest that HCC1500 and HCC1937 cell lines could be suitable cellular models for breast cancer affecting young women. The miR-23a-downregulation could have a potential role as a poor prognosis biomarker in this age group.

MicroRNA-33b Suppresses Epithelial-Mesenchymal Transition Repressing the MYC-EZH2 Pathway in HER2+ Breast Carcinoma

Downregulation of miR-33b has been documented in many types of cancers and is being involved in proliferation, migration, and epithelial–mesenchymal transition (EMT). Furthermore, the enhancer of zeste homolog 2-gene (EZH2) is a master regulator of controlling the stem cell differentiation and the cell proliferation processes. We aim to evaluate the implication of miR-33b in the EMT pathway in HER2+ breast cancer (BC) and to analyze the role of EZH2 in this process as well as the interaction between them. miR-33b is downregulated in HER2+ BC cells vs healthy controls, where EZH2 has an opposite expression in vitro and in patients’ samples. The upregulation of miR-33b suppressed proliferation, induced apoptosis, reduced invasion, migration and regulated EMT by an increase of E-cadherin and a decrease of ß-catenin and vimentin. The silencing of EZH2 mimicked the impact of miR-33b overexpression. Furthermore, the inhibition of miR-33b induces cell proliferation, invasion, migration, EMT, and EZH2 expression in non-tumorigenic cells. Importantly, the Kaplan–Meier analysis showed a significant association between high miR-33b expression and better overall survival. These results suggest miR-33b as a suppressive miRNA that could inhibit tumor metastasis and invasion in HER2+ BC partly by impeding EMT through the repression of the MYC–EZH2 loop.

Abstract P6-03-05: AXL-HER2 dimer as mechanism of anti-HER2 acquired resistance in HER2 amplified brest cancer models: A new step towards precision medicine

Background: Breast cancer (BC) is a heterogeneous disease. HER2+ BC represents between 15-20% of cases. Trastuzumab, a monoclonal antibody, has been successfully improved clinical benefits in both localized and advanced setting. Despite this evidence, many patients experience resistance to therapy. The objective of this study is to analyze AXL receptor as a potential mechanism of resistance and its implication as a prognostic factor. Methods: We used three breast cancer cell lines with acquired resistance to Trastuzumab. Resistant models were generated by treating parental cells (AU565, SKR3, BT474) with constant dose of Trastuzumab (15μg/mL) for 6 months. Cell viability was estimated by MTT assay. Proteins were assessed by Western blot and genes by qRT-PCR. AXL was downregulated by siRNA and a selective tyrosine kinase (TK) AXL inhibitor (TP-0903). Proteins interaction was assessed by immunoprecipitation and Duolink®PLA. The prognostic value of AXL was evaluated in primary tumor in a cohort of HER2+ BC patients treated with Trastuzumab plus chemotherapy from our center (n=33). Results: Acquired resistant cell lines (RCLs) maintained HER2 amplification. RCLs were more proliferative than sensitive parental cell lines. There was an important up-regulation of AXL (&gt;2.5 fold-change) and epithelial-mesenchymal transition markers (VIM, CDH2, CTNNB1 and FN1) in RCLs (p&lt;0.05). Sensitivity to Trastuzumab was restored by silencing AXL and by using TP-0903 both able to cause a decrease in cell viability and Trastuzumab IC50 (p&lt;0.05). AXL high expression was ligand independent, as GAS6 was not increased. Heterodimerization between AXL and HER2 was observed among our RCLs. In our cohort, AXL high expression was detected in patients who relapsed and it was associated with worse prognosis with a decrease of disease-free survival (p&lt;0.05). The worse prognostic role of AXL was validated in a public data set (p&lt;0.001). Conclusions: Our results suggest: 1) RCLs were more proliferative and showed mesenchymal-like enriched phenotype; 2) AXL-HER2 dimer was identified as a potential mechanism of secondary resistance to Trastuzumab; 3) genetic and pharmacological AXL inhibition restored sensitivity to Trastuzumab in in vitro models; 4) AXL expression was associated with worse prognosis in our HER2+ trastuzumab-treated BC patients and validated in silico. These results showed AXL as a prognostic factor and a potential therapeutic target in HER2+ patients with resistance to Trastuzumab and AXL overexpression.

Citation Format: Anna Adam-Artigues, Eduardo Tormo, Raimundo Cervera, Federico Rojo, Alejandro Pérez-Fidalgo, Sandra Zazo, Paula González-Alonso, Cristina Hernándo, María Teresa Martínez, Valentina Gambardella, Jesús Poveda, Soraya Simón, Belén Ortega, Santiago Moragón, Ana Rovira, Joan Albanell, Octavio Burgués, Begoña Bermejo, Pilar Eroles, Ana Lluch, Juan Miguel Cejalvo. AXL-HER2 dimer as mechanism of anti-HER2 acquired resistance in HER2 amplified brest cancer models: A new step towards precision medicine [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-03-05.

The miRNA-449 family mediates doxorubicin resistance in triple-negative breast cancer by regulating cell cycle factors

The mechanisms of chemotherapy resistance in triple negative breast cancer remain unclear, and so, new molecules which might mediate this resistance could optimize treatment response. Here we analyzed the involvement of the miRNA-449 family in the response to doxorubicin. The cell viability, cell-cycle phases, and the expression of in silico target genes and proteins of sensitive/resistant triple negative breast cancer cell lines were evaluated in response to doxorubicin treatment and after gain/loss of miRNAs-449 function achieved by transient transfection. Triple negative breast cancer patients were selected for ex vivo experiments and to evaluate gene and miRNAs expression changes after treatment, as well as survival analysis by Kaplan-Meier. Doxorubicin treatment upregulated miRNAs-449 and DNA-damage responder factors E2F1 and E2F3 in triple negative breast cancer sensitive breast cancer cells, while expression remained unaltered in resistant ones. In vitro overexpression of miRNAs-449 sensitized cells to the treatment and significantly reduced the resistance to doxorubicin. These changes showed also a strong effect on cell cycle regulation. Finally, elevated levels of miRNA-449a associated significantly with better survival in chemotherapy-treated triple negative breast cancer patients. These results reveal for the first time the involvement of the miRNA-449 family in doxorubicin resistance and their predictive and prognostic value in triple negative breast cancer patients.

MicroRNAs in Breast Cancer: One More Turn in Regulation

MicroRNAs (miRNAs) are small non-coding RNA molecules that critically regulate the expression of genes. MiRNAs are involved in physiological cellular processes; however, their deregulation has been associated with several pathologies, including cancer. In human breast cancer, differently expressed levels of miRNAs have been identified from those in normal breast tissues. Moreover, several miRNAs have been correlated with pathological phenotype, cancer subtype and therapy response in breast cancer. The resistance to therapy is increasingly a problem in patient management, and miRNAs are emerging as novel therapeutic targets and potential predictive biomarkers for treatment. This review provides an overview of the current situation of miRNAs in breast cancer, focusing on their involvement in resistance and the circulating miRNA. The mechanisms of therapeutic resistance regulated by miRNAs, such as the regulation of receptors, the modification of enzymes of drug metabolism, the inhibition of cell cycle control or pro-apoptotic proteins, the alteration of histone activity and the regulation of DNA repair machinery among others, are discussed for breast cancer clinical subtypes. Additionally, in this review, we summarize the recent knowledge that has established miRNA detection in peripheral body fluids as a suitable biomarker. We review the detection of miRNA in liquid biopsies and its implications for the diagnosis and monitoring of breast cancer. This new generation of cancer biomarkers may lead to a significant improvement in patient management.

The role of miR-26a and miR-30b in HER2+ breast cancer trastuzumab resistance and regulation of the CCNE2 gene

A subset of HER2+ breast cancer patients manifest clinical resistance to trastuzumab. Recently, miR-26a and miR-30b have been identified as trastuzumab response regulators, and their target gene CCNE2 seems to play an important role in resistance to trastuzumab therapy. Cell viability was evaluated in trastuzumab treated HER2+ BT474 wt (sensitive), BT474r (acquired resistance), HCC1954 (innate resistance), and MDA-MB-231 (HER2−) cell lines, and the expression of miR-26a, miR-30b, and their target genes was measured. BT474 wt cell viability decreased by 60% and miR-26a and miR-30b were significantly overexpressed (~3-fold, p = 0.003 and p = 0.002, respectively) after trastuzumab treatment, but no differences were observed in resistant and control cell lines. Overexpression of miR-30b sensitized BT474r cells to trastuzumab (p = 0.01) and CCNE2, was significantly overexpressed after trastuzumab treatment in BT474r cells (p = 0.032), but no significant changes were observed in sensitive cell line. When CCNE2 was silenced BT474r cell sensitivity to trastuzumab increased (p = 0.03). Thus, the molecular mechanism of trastuzumab action in BT474 cell line may be regulated by miR-26a and miR-30b and CCNE2 overexpression might play an important role in acquired trastuzumab resistance in HER2+ breast cancer given that resistance was diminished when CCNE2 was silenced.

The Antitumor Effect of Metformin Is Mediated by miR-26a in Breast Cancer

Metformin, a drug approved for diabetes type II treatment, has been associated with a reduction in the incidence of breast cancer and metastasis and increased survival in diabetic breast cancer patients. High levels of miR-26a expression have been proposed as one of the possible mechanisms for this effect; likewise, this miRNA has also been associated with survival/apoptosis processes in breast cancer. Our aim was to evaluate if miR-26a and some of its targets could mediate the effect of metformin in breast cancer. The viability of MDA-MB-231, MDA-MB-468, and MCF-7 breast cancer cell lines was evaluated with an MTT assay after ectopic overexpression and/or downregulation of miR-26a. Similarly, the expression levels of the miR-26a targets CASP3, CCNE2, ABL2, APAF1, XIAP, BCL-2, PTEN, p53, E2F3, CDC25A, BCL2L1, MCL-1, EZH2, and MTDH were assessed by quantitative polymerase chain reaction (PCR). The effect of metformin treatment on breast cancer cell viability and miR-26a, BCL-2, PTEN, MCL-1, EZH2, and MTDH modulation were evaluated. Wound healing experiments were performed to analyze the effect of miR-26a and metformin treatment on cell migration. MiR-26a overexpression resulted in a reduction in cell viability that was partially recovered by inhibiting it. E2F3, MCL-1, EZH2, MTDH, and PTEN were downregulated by miR-26a and the PTEN (phosphatase and tensin homolog) protein was also reduced after miR-26a overexpression. Metformin treatment reduced breast cancer cell viability, increased miR-26a expression, and led to a reduction in BCL-2, EZH2, and PTEN expression. miR-26a inhibition partly prevents the metformin viability effect and the PTEN and EZH2 expression reduction. Our results indicate that metformin effectively reduces breast cancer cell viability and suggests that the effects of the drug are mediated by an increase in miR-26a expression and a reduction of its targets, PTEN and EHZ2 Thus, the use of metformin in breast cancer treatment constitutes a promising potential breast cancer therapy.

MicroRNA Profile in Response to Doxorubicin Treatment in Breast Cancer

Chemotherapy treatment is the standard in triple negative breast cancers, a cancer subgroup which lacks a specific target. The mechanisms leading to the response, as well as any markers that allow the differentiation between responder and non-responder groups prior to treatment are unknown. In parallel, miRNAs can act as oncogenes or tumor suppressors and there is evidence of their involvement in promoting resistance to anticancer drugs. Therefore we hypothesized that changes in miRNA expression after doxorubicin treatment may also be relevant in treatment response.

OBJECTIVE

To study miRNAs that are differentially expressed in response to doxorubicin treatment.

METHODS

One luminal-A and two triple negative, breast cancer cell lines were exposed to doxorubicin. Microarray analysis was performed to identify the common and differentially modified miRNAs. Genes and pathways that are theoretically regulated by these miRNAs were analyzed.

RESULTS

Thirteen miRNAs common to all three lines were modified, in addition to 25 that were specific to triple negative cell lines, and 69 that changed only in the luminal-A cell line. This altered expression pattern seemed to be more strongly related to the breast cancer subgroup than to the treatment. The analysis of target genes revealed that cancer related pathways were the most affected by these miRNAs, moreover many of them had been previously related to chemotherapy resistance; thus suggesting follow-up studies. Additionally, through functional assays, we showed that miR-548c-3p is implicated in doxorubicin-treated MCF-7 cell viability, suggesting a role for this miRNA in resistance.

BCL2 gene polymorphisms and splicing variants in chronic myeloid leukemia

Recent data suggest that constitutional genetic variation in the antiapoptotic BCL2 gene could be associated with the susceptibility to develop chronic myeloid leukemia (CML) and the clinical outcome in several hematological malignancies. The present study examines whether BCL2 single nucleotide polymorphisms (SNPs) predispose to CML or may potentially influence the disease characteristics at diagnosis. Notably, no association was observed between the four candidate BCL2 SNPs and the risk of developing CML. Instead, the 4777C>A (rs2279115) and the 5735A>G (rs1801018) SNPs were significantly associated with the disease risk profile as determined by the Sokal score. We found that such polymorphisms correlated with the expression of BCL2 alternative splicing transcripts (BCL2-α, BCL2-β) in healthy donors, but not in CML patients, although the relative levels of BCL2 mRNA splicing variants were shown to change during the clinical course of CML. Our findings suggest that BCL2 polymorphisms could influence the clinical features of CML patients at diagnosis. However, the pathogenic mechanisms involved in such association remain to be ascertained.

MicroRNA profile in very young women with breast cancer

Background

Breast cancer is rarely diagnosed in very young women (35years old or younger), and it often presents with distinct clinical-pathological features related to a more aggressive phenotype and worse prognosis when diagnosed at this early age. A pending question is whether breast cancer in very young women arises from the deregulation of different underlying mechanisms, something that will make this disease an entity differentiated from breast cancer diagnosed in older patients.

Methods

We performed a comprehensive study of miRNA expression using miRNA Affymetrix2.0 array on paraffin-embedded tumour tissue of 42 breast cancer patients 35 years old or younger, 17 patients between 45 and 65 years old and 29 older than 65 years. Data were statistically analyzed by t-test and a hierarchical clustering via average linkage method was conducted. Results were validated by qRT-PCR. Putative targeted pathways were obtained using DIANA miRPath online software.

Results

The results show a differential and unique miRNA expression profile of 121 miRNAs (p-value <0.05), 96 of those with a FDR-value <0.05. Hierarchical clustering grouped the samples according to their age, but not by subtype nor by tumour characteristics. We were able to validate by qRT-PCR differences in the expression of 6 miRNAs: miR-1228*, miR-3196, miR-1275, miR-92b, miR-139 and miR-1207. Moreover, all of the miRNAs maintained the expression trend. The validated miRNAs pointed out pathways related to cell motility, invasion and proliferation.

Conclusions

The study suggests that breast cancer in very young women appears as a distinct molecular signature. To our knowledge, this is the first time that a validated microRNA profile, distinctive to breast cancer in very young women, has been presented. The miRNA signature may be relevant to open an important field of research in order to elucidate the underlying mechanism in this particular disease, which in a more clinical setting, could potentially help to identify therapeutic targets in this particular set of patients.

Thirteen miRNAs involved in the response of breast cancer cells to doxorubicin

e12019

Background: Mature microRNAs (miRNAs) are a class of naturally occurring, small non-coding RNA molecules, about 21–25 nucleotides. Growing evidence shows that miRNAs exhibit a variety of regulatory functions related to cell growth, development, and differentiation, and are associated with a wide variety of human diseases. Several miRNAs have been linked to cancer; since expression analysis studies have revealed perturbed miRNA expression in tumors compared to normal tissues. As a consequence, human miRNAs are likely to be highly useful as biomarkers, especially for future cancer diagnostics, and are emerging as targets for disease intervention. Since doxorubicin (DOX) has been used for a long time in breast cancer treatment, and resistance mechanisms are not clear understood, the aim of this work was to find a miRNA expression profile that could explain the regulation in different breast cancer cell lines under DOX treatment. Methods: Three breast cancer cell lines (MDA-MB-231, MDA-MB-468, and MCF-7) were cultured in normal conditions and also treated with DOX. Total RNA containing small non-coding RNA was isolated and its expression profile was performed by using GeneChip miRNA 2.0 array. Real time PCR validation was carried out to confirm the results. Results: Principal Component Analysis (PCA) of the small non-coding RNA profiles showed different expression patterns between normal conditions and DOX treatment in each cell line separately. Taken together in a Heat Map, miRNA expression profiles of MDA-MB-231 and MDA-MB-468 cell lines were closer in both normal and DOX treatment conditions, while miRNA expression profile of MCF-7 cell line showed strong differences. Total of 13 common miRNAs between the three cell lines were found to be significantly affected by DOX treatment. PCR validation confirmed the results obtained. Conclusions: We conclude that 13 common miRNAs are responsables of changes compared to treatment with DOX in breast cancer cell lines MDA-MB-231, MDA-MB-468 and MCF-7. This miRNAs are mainly related with cellular processes such as cell differentiation, vascularisation, apoptosis and cell proliferation and also involved in other cellular processes, such as cell migration.

The single-nucleotide polymorphisms +936 C/T VEGF and -710 C/T VEGFR1 are associated with breast cancer protection in a Spanish population

Vascular endothelial growth factor (VEGF) is a potent regulator of angiogenesis and thereby involved in the development and progression of solid tumours. The association between polymorphisms of angiogenesis pathway genes and risk of breast cancer (BC) has been widely studied, but the results are not conclusive. This information is especially limited in Spanish women, so we decided to conduct a case-control study. Here, we selected four commonly studied polymorphisms in VEGF, rs3025039 (known as +936 C/T), rs1109324, rs154765 and rs833052, one polymorphism at the promoter of the VEGFR1 (-710 C/T) and another in the FGF2, rs1449683, gene to explore their association with BC susceptibility. Genotyping was performed by TaqMan SNP assays and polymerase chain reaction-restriction fragment length polymorphis (PCR-RFLP) on 453 patients and 461 controls in a population from Valencia (Spain). We observed that women carriers of +936 CT + TT VEGF genotypes have a protective effect concerning this disease (p = 0.014; OR 0.67, 95% CI 0.48-0.92) in the global group of patients. The haplotype TGAC of VEGF (rs3025039, rs1109324, rs154764 and rs833052) shows a reduction of the risk to develop BC (p = 3e-04; OR 0.48, 95% CI 0.32-0.72). Furthermore, we found that carriers of -710 CT + TT VEGFR1 genotypes have also a protective effect (p = 0.039; OR 0.55, 95% CI 0.31-0.98). When we stratified by groups of ages these associations were maintained. Our data report for the first time the association of the polymorphism -710 C/T VEGFR1 with BC. Additional experiments focused on VEGF-A, VEGFR1 and sVEGFR1 gene expression demonstrated that carriers of T allele at -710 C/T VEGFR1 genotype have higher levels of sVEGFR1/VEGF-A than the C/C genotype carriers. This was consistent with the hypothesis that this polymorphism may act as low penetrance risk factor. The data provided suggest that +936 C/T VEGF and -710 C/T VEGFR1 genotypes are likely important genetic markers of susceptibility to BC.

Fibrinolysis and lipoprotein(a) in women with coronary artery disease. Influence of hormone replacement therapy

BACKGROUND AND OBJECTIVES

The incidence of coronary artery disease (CAD) is higher in post-menopausal than in pre-menopausal women. Epidemiological studies suggest that hormone replacement therapy (HRT) decreases the risk of cardiovascular disease in post-menopausal women. HRT could modify the cardiovascular risk via several mechanisms, including modifications in the fibrinolytic system and lipoprotein (a) levels. Our study was aimed at investigating some of these modifications.

DESIGN AND METHODS

In the cross-sectional part of the study we evaluated several components of the fibrinolytic system, coagulation inhibitors and lipid profile in premenopausal (n=15) and post-menopausal women (n=64) with CAD and compared these parameters with those of healthy pre-menopausal (n=31) and post-menopausal women (n=88). The prospective part of the study analyzed the effect of HRT with transdermal estrogen with or without progestogen in post-menopausal women with CAD.

RESULTS

Pre- and postmenopausal women with CAD showed significant lower fibrinolytic activity and higher plasminogen activator inhibitor type 1 (PAI-1) levels than their control groups. Lp(a) levels were higher in premenopausal women with CAD than in healthy premenopausal women. In post-menopausal women with CAD, HRT induced a significant decrease in PAI-1 and Lp(a) levels. No significant differences were observed in any parameter studied between the groups treated with transdermal estrogen with and without progestogen.

INTERPRETATION AND CONCLUSIONS

CAD is associated with a decrease in fibrinolytic activity, possibly due to an increase in PAI-1 levels. An increase in fibrinolytic activity and a decrease in PAI-1 and Lp(a) levels were observed in CAD women receiving transdermal HRT and these changes may have a favorable impact on the risk of new cardiovascular events in post-menopausal CAD women.