Corrigendum: HypoxamiRs Profiling Identify miR-765 as a Regulator of the Early Stages of Vasculogenic Mimicry in SKOV3 Ovarian Cancer Cells.

[This corrects the article DOI: 10.3389/fonc.2019.00381.].

HypoxamiRs Profiling Identify miR-765 as a Regulator of the Early Stages of Vasculogenic Mimicry in SKOV3 Ovarian Cancer Cells

Vasculogenic mimicry (VM) is a novel cancer hallmark in which malignant cells develop matrix-associated 3D tubular networks with a lumen under hypoxia to supply nutrients needed for tumor growth. Recent studies showed that microRNAs (miRNAs) may have a role in VM regulation. In this study, we examined the relevance of hypoxia-regulated miRNAs (hypoxamiRs) in the early stages of VM formation. Data showed that after 48 h hypoxia and 12 h incubation on matrigel SKOV3 ovarian cancer cells undergo the formation of matrix-associated intercellular connections referred hereafter as 3D channels-like structures, which arose previous to the apparition of canonical tubular structures representative of VM. Comprehensive profiling of 754 mature miRNAs at the onset of hypoxia-induced 3D channels-like structures showed that 11 hypoxamiRs were modulated (FC>1.5; p < 0.05) in SKOV3 cells (9 downregulated and 2 upregulated). Bioinformatic analysis of the set of regulated miRNAs showed that they might impact cellular pathways related with tumorigenesis. Moreover, overall survival analysis in a cohort of ovarian cancer patients (n = 485) indicated that low miR-765, miR-193b, miR-148a and high miR-138 levels were associated with worst patients outcome. In particular, miR-765 was severely downregulated after hypoxia (FC < 32.02; p < 0.05), and predicted to target a number of protein-encoding genes involved in angiogenesis and VM. Functional assays showed that ectopic restoration of miR-765 in SKOV3 cells resulted in a significant inhibition of hypoxia-induced 3D channels-like formation that was associated with a reduced number of branch points and patterned tubular-like structures. Mechanistic studies confirmed that miR-765 decreased the levels of VEGFA, AKT1 and SRC-α transducers and exerted a negative regulation of VEGFA by specific binding to its 3'UTR. Finally, overall survival analysis of a cohort of ovarian cancer patients (n = 1435) indicates that high levels of VEGFA, AKT1 and SRC-α and low miR-765 expression were associated with worst patients outcome. In conclusion, here we reported a novel hypoxamiRs signature which constitutes a molecular guide for further clinical and functional studies on the early stages of VM. Our data also suggested that miR-765 coordinates the formation of 3D channels-like structures through modulation of VEGFA/AKT1/SRC-α axis in SKOV3 ovarian cancer cells.

miR­145­5p is associated with pathological complete response to neoadjuvant chemotherapy and impairs cell proliferation by targeting TGFßR2 in breast cancer.

Cancer patients who better benefit from neoadjuvant chemotherapy (NeoCh) are those who achieve a successful pathological complete response (pCR) represented by the absence of residual disease. Unfortunately, no highly sensitive and specific tumor biomarkers for predicting the clinical response to NeoCh have yet been defined. The aim of the present study was to ascertain whether miR­145­5p could discriminate between pCR and no­pCR in triple­negative breast cancer patients that received a cisplatin/doxorubicin­based neoadjuvant treatment. miR­145­5p expression was determined in breast tumors by quantitative RT­PCR. Our data showed that miR­145­5p had a significant low expression (P<0.005) in patients that achieved pCR in comparison to the non­responder group. Kaplan Meier analysis indicated that low levels of miR­145­5p were associated with increased disease­free survival. In addition, receiver operating characteristic (ROC) curve analysis suggested that miR­145­5p is a good predictor of pCR (P<0.003, AUC=0.7899, 95% CI, 0.6382­0.9416). Quantitative RT­PCR expression analysis also revealed that miR­145­5p was downregulated in four breast cancer cell lines relative to normal cells. To study the functions of miR­145­5p, its expression was restored in triple­negative MDA­MB­231 cells and its effects in cell proliferation were evaluated by MTT assays and in apoptosis using Annexin V experiments. Data revealed that ectopic expression of miR­145­5p resulted in a significant inhibition of cell proliferation and also induced apoptosis. Moreover, miR­145­5p led to sensitization of breast cancer cells to cisplatin therapy. In addition, western blot assays indicated that miR­145­5p downregulated the TGFßR2 protein. In conclusion, miR­145­5p could be a potential biomarker of clinical response to NeoCh in triple­negative breast cancer. Functionally miR­145­5p may regulate cell proliferation, at least in part, by targeting TGFßR2.

MicroRNA-143 is Associated With Pathological Complete Response and Regulates Multiple Signaling Proteins in Breast Cancer.

Almost 55% to 80% of patients with breast cancer have an unfavorable pathological complete response to chemotherapy. MicroRNAs are small noncoding RNAs involved in cancer progression; however, their utility as predictors of pathological complete response to neoadjuvant chemotherapy is unclear. Here, we investigated if miR-143 could discriminate between pathological complete response and no-polymerase chain reaction of patients with locally advanced triple negative breast cancer that have received a fluorouracil-cisplatin/paclitaxel-based neoadjuvant treatment. Data showed that miR-143 exhibited a significant low expression ( P < .0006) in patients that achieved pathological complete response in comparison to nonresponder group. Receiver operating characteristic curve analysis suggested that miR-143 could be a good predictor of pathological complete response (area under curve = 0.849, P < .0006). Moreover, Kaplan-Meier analysis indicated that before neoadjuvant therapy low levels of miR-143 were associated to increased disease free survival. To gain insights into cellular functions of miR-143, we firstly showed that miR-143 was severely repressed in breast cancer cell lines and tumors in comparison to normal mammary cells and tissues. Ectopic restoration of miR-143 using RNA mimics inhibited both cell proliferation and migration and sensitized breast cancer cells to cisplatin therapy in vitro. To decipher the signaling networks regulated by miR-143, we used a high-throughput enzyme-linked immunosorbent assay-based phosphorylation antibody array. Phospho-proteomic profiling revealed that miR-143 coordinately reduced the protein levels and phosphorylation status of multiple oncoproteins involved in AKT, WNT/ß-catenin, SAPK/JNK, FAK, and JAK/STAT signaling pathways. Moreover, low miR-143 and high GSK3-ß, RAF1, paxillin, and p21CIP1 expression levels in a large cohort of patients with breast cancer were associated with worst outcome. In summary, miR-143 could be a potential predictor of response to neoadjuvant therapy and it may function as a divergent regulator of diverse signaling networks to suppress cell proliferation and migration in breast cancer.

Regulation Networks Driving Vasculogenic Mimicry in Solid Tumors.

Vasculogenic mimicry (VM) is a mechanism whereby cancer cells form microvascular structures similar to three-dimensional channels to provide nutrients and oxygen to tumors. Unlike angiogenesis, VM is characterized by the development of new patterned three-dimensional vascular-like structures independent of endothelial cells. This phenomenon has been observed in many types of highly aggressive solid tumors. The presence of VM has also been associated with increased resistance to chemotherapy, low survival, and poor prognosis. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are non-coding RNAs that regulate gene expression at the post-transcriptional level through different pathways. In recent years, these tiny RNAs have been shown to be expressed aberrantly in different human malignancies, thus contributing to the hallmarks of cancer. In this context, miRNAs and lncRNAs can be excellent biomarkers for diagnosis, prognosis, and the prediction of response to therapy. In this review, we discuss the role that the tumor microenvironment and the epithelial-mesenchymal transition have in VM. We include an overview of the mechanisms of VM with examples of diverse types of tumors. Finally, we describe the regulation networks of lncRNAs-miRNAs and their clinical impact with the VM. Knowing the key genes that regulate and promote the development of VM in tumors with invasive, aggressive, and therapy-resistant phenotypes will facilitate the discovery of novel biomarker therapeutics against cancer as well as tools in the diagnosis and prognosis of patients.

Cooperative multi-targeting of signaling networks by angiomiR-204 inhibits vasculogenic mimicry in breast cancer cells.

RNA-based multi-target therapies focused in the blocking of signaling pathways represent an attractive approach in cancer. Here, we uncovered a miR-204 cooperative targeting of multiple signaling transducers involved in vasculogenic mimicry (VM). Our data showed that invasive triple negative MDA-MB-231 and Hs-578T breast cancer cells, but not poorly invasive MCF-7 cells, efficiently undergoes matrix-associated VM under hypoxia. Ectopic restoration of miR-204 in MDA-MB-231 cells leads to a potent inhibition of VM and reduction of number of branch points and patterned 3D channels. Further analysis of activation state of multiple signaling pathways using Phosphorylation Antibody Arrays revealed that miR-204 reduced the expression and phosphorylation levels of 13 proteins involved in PI3K/AKT, RAF1/MAPK, VEGF, and FAK/SRC signaling. In agreement with phospho-proteomic profiling, VM was impaired following pharmacological administration of PI3K and SRC inhibitors. Mechanistic studies confirmed that miR-204 exerts a negative post-transcriptional regulation of PI3K-α and c-SRC proto-oncogenes. Moreover, overall survival analysis of a large cohort of breast cancer patients indicates that low miR-204 and high FAK/SRC levels were associated with worst outcomes. In conclusion, our study provides novel lines of evidence indicating that miR-204 may exerts a fine-tuning regulation of the synergistic transduction of PI3K/AKT/FAK mediators critical in VM formation.

let-7d-3p is associated with apoptosis and response to neoadjuvant chemotherapy in ovarian cancer.

Altered expression of microRNAs contributes to the heterogeneous biological behavior of human malignancies and it may correlate with the clinical pathological features of patients. The let-7 microRNA family is frequently downregulated in human cancers and its aberrant expression may be a useful marker for prediction of the clinical response to therapy in patients. In the present study, we analyzed the expression of three members of the let-7 family (let-7a-3p, let-7d-3p and let-7f), which remains largely uncharacterized in ovarian cancer tissues. We also investigated the function of let-7d-3p in the apoptosis and sensitization to chemotherapy in ovarian cancer cells. Our data from stem-loop quantitative RT-PCR showed that expression of let-7a-3p and let-7d-3p, but not let-7f, was significantly (P<0.04) upregulated in ovarian tumors relative to that noted in normal ovarian tissues. Markedly, an increased expression of let­7d-3p (also known as let-7d-3*) was associated with positive response to carboplatin/paclitaxel treatment in ovarian cancer patients. To investigate the biological relevance of let­7d-3p, we knocked down its expression in SKOV-3 ovarian cancer cell line using antagomiRs. Loss of function analysis showed that inhibition of let-7d-3p significantly (P<0.05) impaired cell proliferation and activated apoptosis. In contrast, scratch/wound healing and Transwell chamber assays showed that migration and invasion abilities were not affected in the let-7d-3p-deficient SKOV-3 cancer cells. Notably, Annexin V assays showed a significant (P<0.05) increase in cell death of cancer cells treated with the let-7d-3p inhibitor plus carboplatin indicating a synergistic effect of the drug with antagomiR therapy. Gene ontology classification of predicted targets of let-7d-3p identified a number of genes involved in cellular pathways associated with therapy resistance such as ABC transporters, HIF-1, RAS and ErbB signaling. In summary, our findings showed that inhibition of let-7d-3 activates apoptosis and that its upregulation is associated with a positive response of ovarian cancer patients to carboplatin/paclitaxel chemotherapy.

Silencing the cleavage factor CFIm25 as a new strategy to control Entamoeba histolytica parasite.

The 25 kDa subunit of the Clevage Factor Im (CFIm25) is an essential factor for messenger RNA polyadenylation in human cells. Therefore, here we investigated whether the homologous protein of Entamoeba histolytica, the protozoan responsible for human amoebiasis, might be considered as a biochemical target for parasite control. Trophozoites were cultured with bacterial double-stranded RNA molecules targeting the EhCFIm25 gene, and inhibition of mRNA and protein expression was confirmed by RT-PCR and Western blot assays, respectively. EhCFIm25 silencing was associated with a significant acceleration of cell proliferation and cell death. Moreover, trophozoites appeared as larger and multinucleated cells. These morphological changes were accompanied by a reduced mobility, and erythrophagocytosis was significantly diminished. Lastly, the knockdown of EhCFIm25 affected the poly(A) site selection in two reporter genes and revealed that EhCFIm25 stimulates the utilization of downstream poly(A) sites in E. histolytica mRNA. Overall, our data confirm that targeting the polyadenylation process represents an interesting strategy for controlling parasites, including E. histolytica. To our best knowledge, the present study is the first to have revealed the relevance of the cleavage factor CFIm25 as a biochemical target in parasites.

A microRNA signature associated with pathological complete response to novel neoadjuvant therapy regimen in triple-negative breast cancer.

Neoadjuvant chemotherapy aims to improve the outcome of breast cancer patients, but only few would benefit from this treatment. Pathological complete response has been proposed as a surrogate marker for the prediction of long-term clinical benefits; however, 50%-85% patients have an unfavorable pathological complete response to chemotherapy. MicroRNAs are known biomarkers of breast cancer progression; nevertheless, their potential to identify patients with pathological complete response remains poorly understood. Here, we investigated whether a microRNA profile could be associated with pathological complete response in triple-negative breast cancer patients receiving 5-fluorouracil, adriamycin, cyclophosphamide-cisplatin/paclitaxel as a novel neoadjuvant chemotherapy. In the discovery cohort, the expression of 754 microRNAs was examined in tumors from 10 triple-negative breast cancer patients who achieved pathological complete response and 8 without pathological complete response using TaqMan Low-Density Arrays. Unsupervised hierarchical cluster analysis identified 11 microRNAs with significant differences between responder and no-responder patients (fold change ≥ 1.5; p < 0.05). The differential expression of miR-30a, miR-9-3p, miR-770, and miR-143-5p was validated in an independent group of 17 patients with or without pathological complete response. Moreover, Kaplan-Meier analysis showed that expression of these four microRNAs was associated with an increased disease-free survival. Gene ontology classification of predicted microRNA targets indicated that numerous genes are involved in pathways related to chemoresistance, such as vascular endothelial growth factor, focal adhesion kinase, WNT, ERbB, phosphoinositide 3-kinase, and AKT signaling. In summary, we identified a novel microRNA expression signature associated with pathological complete response in breast cancer. We propose that the four validated microRNAs could be used as molecular biomarkers of clinical response in triple-negative breast cancer patients with pathological complete response to neoadjuvant therapy.

MicroRNAs driving invasion and metastasis in ovarian cancer: Opportunities for translational medicine (Review).

Epithelial ovarian cancer is the fifth most frequent cause of cancer death in women. In spite of the advantages in early detection and treatment options, overall survival rates have improved only slightly in the last decades. Therefore, alternative therapeutic approaches need to overcome resistance and improve the patient survival and outcome. MicroRNAs are evolutionary conserved small non-coding RNAs that function as negative regulators of gene expression by inhibiting translation or inducing degradation of messenger RNAs. In cancer, microRNAs are aberrantly expressed thus representing potential prognostic biomarkers and novel therapeutic targets. The knowledge of novel and unexpected functions of microRNAs is rapidly evolving and the advance in the elucidation of potential clinical applications deserves attention. Recently, a specific set of microRNAs dubbed as metastamiRs have been shown to initiate invasion and metastasis in diverse types of cancer. We reviewed the current status of microRNAs in development and progression of ovarian cancer with a special emphasis on tumor cells invasion and metastasis. Also, we show an update of microRNA functions in oncogenic pathways and discuss the current scenario for potential applications in clinical and translational research in ovarian cancer.