Angiogenic role of miR-20a in breast cancer

Abstract

BackgroundAngiogenesis is a key process for tumor progression and a target for treatment. However, the regulation of breast cancer angiogenesis and its relevance for clinical resistance to antiangiogenic drugs is still incompletely understood. Recent developments on the contribution of microRNA to tumor angiogenesis and on the oncogenic effects of miR-17-92, a miRNA cluster, point to their potential role on breast cancer angiogenesis. The aim of this work was to establish the contribution of miR-20a, a member of miR-17-92 cluster, to tumor angiogenesis in patients with invasive breast carcinoma.MethodsTube-formation in vitro assays with conditioned medium from MCF7 and MDA-MB-231 breast cancer cell lines were performed after transfection with miR-20a and anti-miR20a. For clinical validation of the experimental findings, we performed a retrospective analysis of a series of consecutive breast cancer patients (n = 108) treated with neoadjuvant chemotherapy and with a full characterization of their vessel pattern and expression of angiogenic markers in pre-treatment biopsies. Expression of members of the cluster miR-17-92 and of angiogenic markers was determined by RT-qPCR after RNA purification from FFPE samples.ResultsIn vitro angiogenesis assays with endothelial cells and conditioned media from breast cancer cell lines showed that transfection with anti-miR20a in MDA-MB-231 significantly decreased mean mesh size and total mesh area, while transfection with miR-20a in MCF7 cells increased mean mesh size. MiR-20a angiogenic effects were abrogated by treatment with aflibercept, a VEGF trap. These results were supported by clinical data showing that mir-20a expression was higher in tumors with no estrogen receptor or with more extensive nodal involvement (cN2-3). A higher miR-20a expression was associated with higher mean vessel size (p = 0.015) and with an angiogenic pattern consisting in larger vessels, higher VEGFA expression and presence of glomeruloid microvascular proliferations (p<0.001). This association was independent of tumor subtype and VEGFA expression.ConclusionsTransfection of breast cancer cells with miR-20a induces vascular changes in endothelial tube-formation assays. Expression of miR-20a in breast invasive carcinomas is associated with a distinctive angiogenic pattern consisting in large vessels, anomalous glomeruloid microvascular proliferations and high VEGFA expression. Our results suggest a role for miR-20a in the regulation of breast cancer angiogenesis, and raise the possibility of its use as an angiogenic biomarker.

Long non-coding RNA PVT1 interacts with MYC and its downstream molecules to synergistically promote tumorigenesis

“…Thus, PVT1 may upregulate the expression level of VEGF through inhibiting miR-200b. Moreover, PVT1 may increase the expression of VEGF by inhibiting miR-20a [13,112]. Therefore, PVT1 participates in the downstream angiogenesisrelated signaling pathway of c-Myc and can promote tumor angiogenesis ( Fig.…”

A Strong Decrease in TIMP3 Expression Mediated by the Presence of miR-17 and 20a Enables Extracellular Matrix Remodeling in the NSCLC Lesion Surroundings

“…TIMP3 silencing is associated with the intensified ECM remodeling and cancer cell migration (39). Such ECM remodeling in the tumor surrounding tissue can be forced by the rapid growth of the lesion and its rigidity: when the diameter of the tumor increases, it exerts pressure on neighboring tissues and blood vessels (48). Surprisingly we have observed the positive correlation of TIMP3 in NLNT with miR-17 expression (in the entire study cohort and SCC subtype, not detected in AC) as the increase of the miR17 is linked to the angiogenesis, though we hypothesize that TIMP3 expression may be activated by indirect miR action.…”

“…The observed in our study negative correlation of TIMP3 with miR-20a expression (both preoperative and postoperative miR20a in SCC subtype, post miR20a in the entire study cohort), can be explained as epigenetic silencing of the genes controlling the ECM remodeling. The miR-20a action has been previously linked to the induction of vascular changes in invasive breast carcinomas (48) and metastasis in gastric cancer (50). TIMP3 silencing mediated by miR-20a may be treated as a hallmark of substantial ECM deregulation already present in the NLNT.…”

“…TIMP3 silencing mediated by miR-20a may be treated as a hallmark of substantial ECM deregulation already present in the NLNT. Remodeling encourages further growth of the lesion and induces local hypoxia, which in turn can encourage the development of new blood vessels growth (48,57). The observed strong downregulation of TIMP3 and disturbed MMP2/TIMP3 expression ratio can be explained as crucial activities in the ECM remodeling process, enabling creation of a microenvironment conducive to tumor growth (57).…”

Current Advancement of the miR-17-92 Cluster in Gastrointestinal Cancers

“…Interestingly, the miR-17-92 cluster, a key miRNA, has shown oncogenic and tumor suppressive properties. While miR-17-92 functioned as an oncogene in some cancers [110][111][112], overexpression of miR-17-92 has also related with cancer progression and poor outcome in osteosarcoma, breast cancer, esophageal squamous cell carcinoma, chronic lymphocytic leukemia and retinoblastoma [113][114][115][116][117]. Moreover, a tumour suppressive role of the miR-17-92 cluster has been verified in prostate tumor and in GI stromal tumours and in oral squamous carcinoma [118][119][120].…”