MicroRNA-204 Regulates Angiogenesis and Vasculogenic Mimicry in CD44+/CD24- Breast Cancer Stem-like Cells.

Tumors have high requirements in terms of nutrients and oxygen. Angiogenesis is the classical mechanism for vessel formation. Tumoral vascularization has the function of nourishing the cancer cells to support tumor growth. Vasculogenic mimicry, a novel intratumoral microcirculation system, alludes to the ability of cancer cells to organize in three-dimensional (3D) channel-like architectures. It also supplies the tumors with nutrients and oxygen. Both mechanisms operate in a coordinated way; however, their functions in breast cancer stem-like cells and their regulation by microRNAs remain elusive. In the present study, we investigated the functional role of microRNA-204 (miR-204) on angiogenesis and vasculogenic mimicry in breast cancer stem-like cells. Using flow cytometry assays, we found that 86.1% of MDA-MB-231 and 92% of Hs-578t breast cancer cells showed the CD44+/CD24- immunophenotype representative of cancer stem-like cells (CSCs). The MDA-MB-231 subpopulation of CSCs exhibited the ability to form mammospheres, as expected. Interestingly, we found that the restoration of miR-204 expression in CSCs significantly inhibited the number and size of the mammospheres. Moreover, we found that MDA-MB-231 and Hs-578t CSCs efficiently undergo angiogenesis and hypoxia-induced vasculogenic mimicry in vitro. The transfection of precursor miR-204 in both CSCs was able to impair the angiogenesis in the HUVEC cell model, which was observed as a diminution in the number of polygons and sprouting cells. Remarkably, miR-204 mimics also resulted in the inhibition of vasculogenic mimicry formation in MDA-MB-231 and Hs-578t CSCs, with a significant reduction in the number of channel-like structures and branch points. Mechanistically, the effects of miR-204 were associated with a diminution of pro-angiogenic VEGFA and ß-catenin protein levels. In conclusion, our findings indicated that miR-204 abrogates the angiogenesis and vasculogenic mimicry development in breast cancer stem-like cells, suggesting that it could be a potential tool for breast cancer intervention based on microRNA replacement therapies.

Novel Insights into Circular RNAs in Metastasis in Breast Cancer: An Update.

Circular RNAs (circRNAs) are single-stranded closed non-coding RNA molecules that are aberrantly expressed and produce tumor-specific gene signatures in human cancers. They exert biological functions by acting as transcriptional regulators, microRNA sponges, and protein scaffolds, regulating the formation of protein-RNA complexes and, ultimately, regulating gene expression. Triple-negative breast cancer (TNBC) is one of the most aggressive cancers of the mammary gland and has a poor prognosis. Studies of circRNAs in TNBC are limited but have demonstrated these molecules' pivotal roles in cell proliferation, invasion, metastasis, and resistance to chemo/radiotherapy, suggesting that they could be potential prognostic biomarkers and novel therapeutic targets. Here, we reviewed the status of actual knowledge about circRNA biogenesis and functions and summarized novel findings regarding their roles in TNBC development and progression. In addition, we discussed recent data about the importance of exosomes in the transport and export of circRNAs in TNBC. Deep knowledge of circRNA functions in metastasis and therapy responses could be an invaluable guide in the identification of novel therapeutic targets for advancing the treatment of TNBC.

Regulatory Roles of Non-Coding RNAs in Cancer.

For several decades, scientific research in cancer biology has focused mainly on the involvement of protein-coding genes [...].

The Role of Hypoxia in Endometrial Cancer.

Endometrial cancer represents the most frequent neoplasia from the corpus uteri and comprises the 14th leading cause of death in women worldwide. Risk factors that contribute to the disease include early menarche, late menopause, nulliparity, and menopausal hormone use, as well as hypertension and obesity comorbidities. The clinical effectiveness of chemotherapy is variable, suggesting that novel molecular targeted therapies against specific cellular processes associated with the maintenance of cancer cell survival and therapy resistance ameliorate the rates of success in endometrial cancer treatment. In the course of tumor growth, cancer cells must adapt to decreased oxygen availability in the microenvironment by upregulation of hypoxia-inducible factors, which orchestrate the activation of a transcriptional program leading to cell survival. During this adaptative process, the hypoxic cancer cells may acquire invasive and metastatic properties as well as increased cell proliferation and resistance to chemotherapy, enhanced angiogenesis, vasculogenic mimicry, and maintenance of cancer cell stemness, which contribute to more aggressive cancer phenotypes. Several studies have shown that hypoxia-inducible factor 1 alpha (HIF-1α) protein is aberrantly overexpressed in many solid tumors of the breast, prostate, ovarian, bladder, colon, brain, and pancreas. Thus, it has been considered an important therapeutic target. Here, we reviewed the current knowledge of the relevant roles of cellular hypoxia mechanisms and HIF-1α functions in diverse processes associated with endometrial cancer progression. In addition, we also summarize the role of microRNAs in the posttranscriptional regulation of protein-encoding genes involved in the hypoxia response in endometrial cancer. Finally, we pointed out the need for urgent targeted therapies to impair the cellular processes activated by hypoxia in the tumor microenvironment.

Deciphering the Long Non-Coding RNAs and MicroRNAs Coregulation Networks in Ovarian Cancer Development: An Overview.

Non-coding RNAs are emergent elements from the genome, which do not encode for proteins but have relevant cellular functions impacting almost all the physiological processes occurring in eukaryotic cells. In particular, microRNAs and long non-coding RNAs (lncRNAs) are a new class of small RNAs transcribed from the genome, which modulate the expression of specific genes at transcriptional and posttranscriptional levels, thus adding a new regulatory layer in the flux of genetic information. In cancer cells, the miRNAs and lncRNAs interactions with its target genes and functional pathways are deregulated as a consequence of epigenetic and genetic alterations occurring during tumorigenesis. In this review, we summarize the actual knowledge on the interplay of lncRNAs with its cognate miRNAs and mRNAs pairs, which interact in coregulatory networks with a particular emphasis on the mechanisms underlying its oncogenic behavior in ovarian cancer. Specifically, we reviewed here the evidences unraveling the relevant roles of lncRNAs/miRNAs pairs in altered regulation of cell migration, angiogenesis, therapy resistance, and Warburg effect. Finally, we also discussed its potential clinical implications in ovarian cancer and related endocrine disease therapies.

LncRNAs and microRNAs as Essential Regulators of Stemness in Breast Cancer Stem Cells.

Breast cancer is an aggressive disease with a high incidence in women worldwide. Two decades ago, a controversial hypothesis was proposed that cancer arises from a subpopulation of "tumor initiating cells" or "cancer stem cells-like" (CSC). Today, CSC are defined as small subset of somatic cancer cells within a tumor with self-renewal properties driven by the aberrant expression of genes involved in the maintenance of a stemness-like phenotype. The understanding of the underlying cellular and molecular mechanisms involved in the maintenance of CSC subpopulation are fundamental in the development and persistence of breast cancer. Nowadays, the hypothesis suggests that genetic and epigenetic alterations give rise to breast cancer stem cells (bCSC), which are responsible for self-renewal, tumor growth, chemoresistance, poor prognosis and low survival in patients. However, the prominence of bCSC, as well as the molecular mechanisms that regulates and promotes the malignant phenotypes, are still poorly understood. The role of non-coding RNAs (ncRNAs), such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) acting as oncogenes or tumor suppressor genes has been recently highlighted by a plethora of studies in breast cancer. These ncRNAs positively or negatively impact on different signaling pathways that govern the cancer hallmarks associated with bCSC, making them attractive targets for therapy. In this review, we present a current summary of the studies on the pivotal roles of lncRNAs and microRNAs in the regulation of genes associated to stemness of bCSC.

Lipid­based nanoparticles for the therapeutic delivery of non­coding RNAs in breast cancer (Review).

Breast cancer is the most common type of cancer with the highest morbidity and mortality rates in women worldwide. Recent efforts to improve the current antitumor therapies have led to the development of novel treatment approaches based on the delivery of therapeutic non­coding RNAs (ncRNAs) using nanotechnology. Treatment methods using lipid­based nanoparticles (LBNPs) have greatly improved the delivery efficiency of ncRNAs into tumor cells and tissues. This type of delivery approach has provided significant advantages, such as reduced therapeutic doses, lower cytotoxicity to normal cells and the ability to reverse resistance to chemotherapy. LBNPs have demonstrated the ability to deliver therapeutic ncRNAs, more specifically microRNAs (miRNAs) and small interfering RNAs (siRNAs); this has been reported modulate the expression levels of oncogenes and tumor suppressor genes involved in several biological processes, including cell growth and proliferation, cell death, invasion and metastasis, thus impairing the malignant behavior of tumors. Therefore, ncRNA­based therapies combined with the LBNP delivery strategy, namely nanomiRNAs, may represent a promising antitumor strategy guaranteeing superior biocompatibility, higher biodegradability, lower immunogenicity and decreased toxicity to normal cells compared with other therapeutic approaches. The present review summarized the current knowledge of the application of LBNPs for delivering miRNAs and siRNAs in breast cancer cells and mouse models, in addition to discussing their promising antitumor effects.

Proteomics approaches to understand cell biology and virulence of Entamoeba histolytica protozoan parasite.

Entamoeba histolytica is the primitive eukaryotic parasite responsible of human amoebiasis, a disease characterized by bloody intestinal diarrhea and invasive extraintestinal illness. The knowledge of the complete genome sequence of virulent E. histolytica and related non-pathogenic species allowed the development of novel genome-wide methodological approaches including protein expression profiling and cellular proteomics in the so called post-genomic era. Proteomics studies have greatly increased our understanding of the cell biology of this ancient parasite. This review summarizes the current works concerning proteomics studies on cell biology, life cycle, virulence and pathogenesis, novel therapies, and protein expression regulation mechanisms in E. histolytica parasite. Also, we discuss the use of proteomics data for the development of novel therapies, the identification of potential disease biomarkers and differential diagnosis between species. SIGNIFICANCE: Entamoeba histolytica is the unicellular protozoan parasite responsible of human amoebiasis, a serious disease with worldwide distribution characterized by bloody intestinal diarrhea and invasive extraintestinal illness including peritonitis and liver, pulmonary and brain abscesses. The post-genomic era allowed the development of proteomic studies including protein expression profiling and cellular proteomics. These proteomics studies have greatly increased our understanding on cell biology, life cycle (cyst-trophozoite conversion), virulence, pathogenesis, novel therapies, and protein expression regulation mechanisms in E. histolytica. Importantly, proteomics has revealed the identity of proteins related to novel therapies, and the identification of potential disease biomarkers and proteins with use in diagnosis between species. Hopefully in the coming years, and through the use of more sophisticated omics tools, including deep proteomics, a more complete set of proteins involved in the aforementioned cellular processes can be obtained to understand the biology of this ancient eukaryote.

HOX Transcript Antisense RNA HOTAIR Abrogates Vasculogenic Mimicry by Targeting the AngiomiR-204/FAK Axis in Triple Negative Breast Cancer Cells.

HOX transcript antisense RNA (HOTAIR) is an oncogenic long non-coding RNA frequently overexpressed in cancer. HOTAIR can enhance the malignant behavior of tumors by sponging microRNAs with tumor suppressor functions. Vasculogenic mimicry is a hypoxia-activated process in which tumor cells form three-dimensional (3D) channel-like networks, resembling endothelial blood vessels, to obtain nutrients. However, the role of HOTAIR in vasculogenic mimicry and the underlying mechanisms are unknown in human cancers. In the current study, we investigated the relevance of HOTAIR in hypoxia-induced vasculogenic mimicry in metastatic MDA-MB-231 and invasive Hs-578t triple negative breast cancer cells. Analysis of The Cancer Genome Atlas (TCGA) database using cBioPortal confirmed that HOTAIR was upregulated in clinical breast tumors relative to normal mammary tissues. Our quantitative RT-PCR assays showed a significant increase in HOTAIR levels after 48 h hypoxia relative to normoxia in breast cancer cell lines. Remarkably, knockdown of HOTAIR significantly abolished the hypoxia-induced vasculogenic mimicry which was accompanied by a reduction in the number of 3D channel-like networks and branch points. Likewise, HOTAIR silencing leads to reduced cell migration abilities of cancer cells. Bioinformatic analysis predicted that HOTAIR has a potential binding site for tumor suppressor miR-204. Luciferase reporter assays confirmed that HOTAIR is a competitive endogenous sponge of miR-204. Congruently, forced inhibition of HOTAIR in cells resulted in augmented miR-204 levels in breast cancer cells. Further bioinformatic analysis suggested that miR-204 can bind to the 3' untranslated region of focal adhesion kinase 1 (FAK) transcript involved in cell migration. Western blot and luciferase reporter assays confirmed that FAK is a novel target of miR-204. Finally, silencing of HOTAIR resulted in low levels of cytoplasmic FAK protein and alterations in the organization of cellular cytoskeleton and focal adhesions. In summary, our results showed, for the first time, that HOTAIR mitigates cell migration and vasculogenic mimicry by targeting the miR-204/FAK axis in triple negative breast cancer cells.