The First Population-Level Description of Women Diagnosed With Invasive Breast Cancer in Costa Rica From 2008 to 2012: A Cross-Sectional Study.

INTRODUCTION: Breast cancer is the leading cause of cancer-related deaths among women worldwide. In Costa Rica, it ranks first in incidence and fourth in terms of mortality. However, there is a lack of comprehensive information on treatment patterns and outcomes for breast cancer patients in Costa Rica. METHODS: This study utilized data from the National Tumor Registry, which was merged with the Costa Rica Social Security Fund (CCSS) to ensure comprehensive access to clinical information. The study is prospective and focused on patients diagnosed with breast cancer between January 2008 and December 2012. This combined dataset allowed for a more comprehensive analysis of patient characteristics, treatment patterns, and outcomes related to breast cancer in Costa Rica. RESULTS: Among the 4775 patients diagnosed during this period, 3160 met the inclusion criteria for our study. The average age at diagnosis was 59.1 years, with 32.5% of patients being over the age of 65. Most of the patients (55.4%) identified themselves as homemakers, while 46.5% underwent core needle biopsy for diagnosis. Approximately 60% of women were diagnosed with early-stage disease (IA, IIA, and IIB), while 1.7% had metastatic disease, mainly affecting the bone. The mean interval between diagnosis and surgery was 72 days. Most patients (88.7%) received surgery as their initial treatment, and over half (54.4%) received some form of adjuvant therapy. Additionally, 85.6% of patients completed their prescribed treatment. CONCLUSION: This study provides a comprehensive and detailed description of the characteristics and treatment patterns among breast cancer patients in Costa Rica. The findings contribute to our understanding of the disease in this population and can serve as a foundation for further research and improvement in breast cancer management and care.

Correction: UDP-glucose 6-dehydrogenase regulates hyaluronic acid production and promotes breast cancer progression.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

UDP-glucose 6-dehydrogenase regulates hyaluronic acid production and promotes breast cancer progression.

An improved understanding of the biochemical alterations that accompany tumor progression and metastasis is necessary to inform the next generation of diagnostic tools and targeted therapies. Metabolic reprogramming is known to occur during the epithelial-mesenchymal transition (EMT), a process that promotes metastasis. Here, we identify metabolic enzymes involved in extracellular matrix remodeling that are upregulated during EMT and are highly expressed in patients with aggressive mesenchymal-like breast cancer. Activation of EMT significantly increases production of hyaluronic acid, which is enabled by the reprogramming of glucose metabolism. Using genetic and pharmacological approaches, we show that depletion of the hyaluronic acid precursor UDP-glucuronic acid is sufficient to inhibit several mesenchymal-like properties including cellular invasion and colony formation in vitro, as well as tumor growth and metastasis in vivo. We found that depletion of UDP-glucuronic acid altered the expression of PPAR-gamma target genes and increased PPAR-gamma DNA-binding activity. Taken together, our findings indicate that the disruption of EMT-induced metabolic reprogramming affects hyaluronic acid production, as well as associated extracellular matrix remodeling and represents pharmacologically actionable target for the inhibition of aggressive mesenchymal-like breast cancer progression.

The Epithelial to Mesenchymal Transition Promotes Glutamine Independence by Suppressing GLS2 Expression.

Identifying bioenergetics that facilitate the epithelial to mesenchymal transition (EMT) in breast cancer cells may uncover targets to treat incurable metastatic disease. Metastasis is the number one cause of cancer-related deaths; therefore, it is urgent to identify new treatment strategies to prevent the initiation of metastasis. To characterize the bioenergetics of EMT, we compared metabolic activities and gene expression in cells induced to differentiate into the mesenchymal state with their epithelial counterparts. We found that levels of GLS2, which encodes a glutaminase, are inversely associated with EMT. GLS2 down-regulation was correlated with reduced mitochondrial activity and glutamine independence even in low-glucose conditions. Restoration of GLS2 expression in GLS2-negative breast cancer cells rescued mitochondrial activity, enhanced glutamine utilization, and inhibited stem-cell properties. Additionally, inhibition of expression of the transcription factor FOXC2, a critical regulator of EMT in GLS2-negative cells, restored GLS2 expression and glutamine utilization. Furthermore, in breast cancer patients, high GLS2 expression is associated with improved survival. These findings suggest that epithelial cancer cells rely on glutamine and that cells induced to undergo EMT become glutamine independent. Moreover, the inhibition of EMT leads to a GLS2-directed metabolic shift in mesenchymal cancer cells, which may make these cells susceptible to chemotherapies.

GSK3ß regulates epithelial-mesenchymal transition and cancer stem cell properties in triple-negative breast cancer.

BACKGROUND: Triple-negative breast cancers (TNBCs), which lack receptors for estrogen, progesterone, and amplification of epidermal growth factor receptor 2, are highly aggressive. Consequently, patients diagnosed with TNBCs have reduced overall and disease-free survival rates compared to patients with other subtypes of breast cancer. TNBCs are characterized by the presence of cancer cells with mesenchymal properties, indicating that the epithelial to mesenchymal transition (EMT) plays a major role in the progression of this disease. The EMT program has also been implicated in chemoresistance, tumor recurrence, and induction of cancer stem cell (CSC) properties. Currently, there are no targeted therapies for TNBC, and hence, it is critical to identify the novel targets to treat TNBC. METHODS: A library of compounds was screened for their ability to inhibit EMT in cells with mesenchymal phenotype as assessed using the previously described Z-cad reporters. Of the several drugs tested, GSK3ß inhibitors were identified as EMT inhibitors. The effects of GSK3ß inhibitors on the properties of TNBC cells with a mesenchymal phenotype were assessed using qRT-PCR, flow cytometry, western blot, mammosphere, and migration and cell viability assays. Publicly available datasets also were analyzed to examine if the expression of GSK3ß correlates with the overall survival of breast cancer patients. RESULTS: We identified a GSK3ß inhibitor, BIO, in a drug screen as one of the most potent inhibitors of EMT. BIO and two other GSK3ß inhibitors, TWS119 and LiCl, also decreased the expression of mesenchymal markers in several different cell lines with a mesenchymal phenotype. Further, inhibition of GSK3ß reduced EMT-related migratory properties of cells with mesenchymal properties. To determine if GSK3ß inhibitors target mesenchymal-like cells by affecting the CSC population, we employed mammosphere assays and profiled the stem cell-related cell surface marker CD44+/24- in cells after exposure to GSK3ß inhibitors. We found that GSK3ß inhibitors indeed decreased the CSC properties of cell types with mesenchymal properties. We treated cells with epithelial and mesenchymal properties with GSK3ß inhibitors and found that GSK3ß inhibitors selectively kill cells with mesenchymal attributes while sparing cells with epithelial properties. We analyzed patient data to identify genes predictive of poor clinical outcome that could serve as novel therapeutic targets for TNBC. The Wnt signaling pathway is critical to EMT, but among the various factors known to be involved in Wnt signaling, only the higher expression of GSK3ß correlated with poorer overall patient survival. CONCLUSIONS: Taken together, our data demonstrate that GSK3ß is a potential target for TNBCs and suggest that GSK3ß inhibitors could serve as selective inhibitors of EMT and CSC properties for the treatment of a subset of aggressive TNBC. GSK3ß inhibitors should be tested for use in combination with standard-of-care drugs in preclinical TNBC models.

Distinguishing mechanisms underlying EMT tristability.

BACKGROUND: The Epithelial-Mesenchymal Transition (EMT) endows epithelial-looking cells with enhanced migratory ability during embryonic development and tissue repair. EMT can also be co-opted by cancer cells to acquire metastatic potential and drug-resistance. Recent research has argued that epithelial (E) cells can undergo either a partial EMT to attain a hybrid epithelial/mesenchymal (E/M) phenotype that typically displays collective migration, or a complete EMT to adopt a mesenchymal (M) phenotype that shows individual migration. The core EMT regulatory network - miR-34/SNAIL/miR-200/ZEB1 - has been identified by various studies, but how this network regulates the transitions among the E, E/M, and M phenotypes remains controversial. Two major mathematical models - ternary chimera switch (TCS) and cascading bistable switches (CBS) - that both focus on the miR-34/SNAIL/miR-200/ZEB1 network, have been proposed to elucidate the EMT dynamics, but a detailed analysis of how well either or both of these two models can capture recent experimental observations about EMT dynamics remains to be done. RESULTS: Here, via an integrated experimental and theoretical approach, we first show that both these two models can be used to understand the two-step transition of EMT - E→E/M→M, the different responses of SNAIL and ZEB1 to exogenous TGF-ß and the irreversibility of complete EMT. Next, we present new experimental results that tend to discriminate between these two models. We show that ZEB1 is present at intermediate levels in the hybrid E/M H1975 cells, and that in HMLE cells, overexpression of SNAIL is not sufficient to initiate EMT in the absence of ZEB1 and FOXC2. CONCLUSIONS: These experimental results argue in favor of the TCS model proposing that miR-200/ZEB1 behaves as a three-way decision-making switch enabling transitions among the E, hybrid E/M and M phenotypes.

EMT-induced metabolite signature identifies poor clinical outcome.

Metabolic reprogramming is a hallmark of cancer. Epithelial-mesenchymal transition (EMT) induces cancer stem cell (CSC) characteristics and promotes tumor invasiveness; however relatively little is known about the metabolic reprogramming in EMT. Here we show that breast epithelial cells undergo metabolic reprogramming following EMT. Relative to control, cell lines expressing EMT transcription factors show ≥1.5-fold accumulation of glutamine, glutamate, beta-alanine and glycylleucine as well as ≥1.5-fold reduction of phosphoenolpyruvate, urate, and deoxycarnitine. Moreover, these metabolic alterations were found to be predictive of overall survival (hazard ratio = 2.3 (95% confidence interval: 1.31-4.2), logrank p-value = 0.03) and define breast cancer molecular subtypes. EMT-associated metabolites are primarily composed of anapleurotic precursors, suggesting that cells undergoing EMT have a shift in energy production. In summary, we describe a unique panel of metabolites associated with EMT and demonstrate that these metabolites have the potential for predicting clinical and biological characteristics associated with patient survival.

RivR is a negative regulator of virulence factor expression in group A Streptococcus.

The bacterial pathogen group A Streptococcus (GAS) causes human diseases ranging from self-limiting pharyngitis (also known as strep throat) to severely invasive necrotizing fasciitis (also known as the flesh-eating syndrome). To control virulence factor expression, GAS utilizes both protein- and RNA-based mechanisms of regulation. Here we report that the transcription factor RivR (RofA-like protein IV) negatively regulates the abundance of mRNAs encoding the hyaluronic acid capsule biosynthesis proteins (hasABC; ∼7-fold) and the protein G-related α(2)-macroglobulin-binding protein (grab; ∼29-fold). Our data differ significantly from those of a previous study of the RivR regulon. Given that grab and hasABC are also negatively regulated by the two-component system CovR/S (control of virulence), we tested whether RivR functions through CovR/S. A comparison of riv and cov single and double mutant strains showed that RivR requires CovR activity for grab and hasABC regulation. Analysis of the upstream region of rivR identified a novel promoter the deletion of which reduced rivR mRNA abundance by 70%. A rivR mutant strain had a reduced ability to adhere to human keratinocytes relative to that of the parental and complemented strains, a phenotype that was abolished upon GAS pretreatment with hyaluronidase, highlighting the importance of capsule regulation by RivR during colonization. The rivR mutant strain was also attenuated for virulence in a murine model of bacteremia infection. Thus, we identify RivR as an important regulator of GAS virulence and provide new insight into the regulatory networks controlling virulence factor production in this pathogen.

The small regulatory RNA FasX controls pilus expression and adherence in the human bacterial pathogen group A Streptococcus.

Bacterial pathogens use cell surface-associated adhesion molecules to promote host attachment and colonization, and the ability to modulate adhesion expression is critical to pathogen success. Here, we show that the human-specific pathogen the group A Streptococcus (GAS) uses a small regulatory RNA (sRNA) to regulate the expression of adhesive pili. The fibronectin/fibrinogen-binding/haemolytic-activity/streptokinase-regulator-X (FasX) sRNA, previously shown to positively regulate expression of the secreted virulence factor streptokinase (SKA), negatively regulates the production of pili on the GAS cell surface. FasX base pairs to the extreme 5' end of mRNA from the pilus biosynthesis operon, and this RNA:RNA interaction reduces the stability of the mRNA, while also inhibiting translation of at least the first gene in the pilus biosynthesis operon (cpa, which encodes a minor pilin protein). The negative regulation of pilus expression by FasX reduces the ability of GAS to adhere to human keratinocytes. Our findings cement FasX sRNA as an important regulator of virulence factor production in GAS and identify that FasX uses at least three distinct mechanisms, positive (ska mRNA) and negative (pilus operon mRNA) regulation of mRNA stability, and negative regulation of mRNA translation (cpa mRNA), to post-transcriptionally regulate target mRNAs during infection.

The group A Streptococcus small regulatory RNA FasX enhances streptokinase activity by increasing the stability of the ska mRNA transcript.

Small RNA molecules play key regulatory roles in many bacterial species. However, little mechanistic data exists for the action of small regulatory RNAs in the human pathogen group A Streptococcus (GAS). Here, we analysed the relationship between a putative GAS sRNA and production of the secreted virulence factor streptokinase (SKA). SKA promotes GAS dissemination by activating conversion of host plasminogen into the fibrin-degrading protease plasmin. Homologues of the putative sRNA-encoding gene fibronectin/fibrinogen-binding/haemolytic-activity/streptokinase-regulator-X (fasX) were identified in four different pyogenic streptococcal species. However, despite 79% fasX nucleotide identity, a fasX allele from the animal pathogen Streptococcus zooepidemicus failed to complement a GAS fasX mutant. Using a series of precisely constructed fasX alleles we discovered that FasX is a bona-fide sRNA that post-transcriptionally regulates SKA production in GAS. By base-pairing to the 5' end of ska mRNA, FasX enhances ska transcript stability, resulting in a ∼10-fold increase in SKA activity. Our data provide new insights into the mechanisms used by small regulatory RNAs to activate target mRNAs, and enhances our understanding of the regulation of a key GAS virulence factor.

CovS simultaneously activates and inhibits the CovR-mediated repression of distinct subsets of group A Streptococcus virulence factor-encoding genes.

To colonize and cause disease at distinct anatomical sites, bacterial pathogens must tailor gene expression in a microenvironment-specific manner. The molecular mechanisms that control the ability of the human bacterial pathogen group A Streptococcus (GAS) to transition between infection sites have yet to be fully elucidated. A key regulator of GAS virulence gene expression is the CovR-CovS two-component regulatory system (also known as CsrR-CsrS). covR and covS mutant strains arise spontaneously during invasive infections and, in in vivo models of infection, rapidly become dominant. Here, we compared wild-type GAS with covR, covS, and covRS isogenic mutant strains to investigate the heterogeneity in the types of natural mutations that occur in covR and covS and the phenotypic consequences of covR or covS mutation. We found that the response regulator CovR retains some regulatory function in the absence of CovS and that CovS modulates CovR to significantly enhance repression of one group of genes (e.g., the speA, hasA, and ska genes) while it reduces repression of a second group of genes (e.g., the speB, grab, and spd3 genes). We also found that different in vivo-induced covR mutations can lead to strikingly different transcriptomes. While covS mutant strains show increased virulence in several invasive models of infection, we determined that these mutants are significantly outcompeted by wild-type GAS during growth in human saliva, an ex vivo model of upper respiratory tract infection. We propose that CovS-mediated regulation of CovR activity plays an important role in the ability of GAS to cycle between pharyngeal and invasive infections.