miR-145-dependent targeting of Junctional Adhesion Molecule A and modulation of fascin expression are associated with reduced breast cancer cell motility and invasiveness

Abstract

Micro RNAs are small non-coding RNAs, which regulate fundamental cellular and developmental processes at the transcriptional and translational level. In breast cancer, miR-145 expression is downregulated compared with healthy control tissue. As several predicted targets of miR-145 potentially regulate cell motility, we aimed at investigating a potential role for miR-145 in breast cancer cell motility and invasiveness. Assisted by Affymetrix array technology, we demonstrate that overexpression of miR-145 in MDA-MB-231, MCF-7, MDA-MB-468 and SK-BR-3 breast cancer cells and in Ishikawa endometrial carcinoma cells leads to a downregulation of the cell-cell adhesion protein JAM-A and of the actin bundling protein fascin. Moreover, podocalyxin and Serpin E1 mRNA levels were downregulated, and gamma-actin, transgelin and MYL9 were upregulated upon miR-145 overexpression. These miR-145-dependent expression changes drastically decreased cancer cell motility, as revealed by time-lapse video microscopy, scratch wound closure assays and matrigel invasion assays. Immunofluorescence microscopy demonstrated restructuring of the actin cytoskeleton and a change in cell morphology by miR-145 overexpression, resulting in a more cortical actin distribution, and reduced actin stress fiber and filopodia formation. Nuclear rotation was observed in 10% of the pre-miR-145 transfected MDA-MB-231 cells, accompanied by a reduction of perinuclear actin. Luciferase activation assays confirmed direct miR-145-dependent regulation of the 3 0 UTR of JAM-A, whereas siRNA-mediated knockdown of JAM-A expression resulted in decreased motility and invasiveness of MDA-MB-231 and MCF-7 breast cancer cells. Our data identify JAM-A and fascin as novel targets of miR-145, firmly establishing a role for miR-145 in modulating breast cancer cell motility. Our data provide a rationale for future miR-145-targeted approaches of antimetastatic cancer therapy.

Junctional adhesion molecule-A is co-expressed with HER2 in breast tumors and acts as a novel regulator of HER2 protein degradation and signaling

“…We and others have recently linked high breast epithelial expression of JAM-A with aggressive disease and poor outcome in breast cancer patients (Gotte et al, 2010;McSherry et al, 2011;McSherry et al, 2009;Murakami et al, 2011). We independently verified these findings on a small breast cancer TMA of 48 tumor and ER-negativity (p<0.001).…”

“…Furthermore the pharmacological reduction of JAM-A signaling may have benefit in reducing metastatic risk, since we (McSherry et al, 2011;McSherry et al, 2009) and others (Gotte et al, 2010) have shown that JAM-A knockdown or functional antagonism decreases breast cancer cell migration, an early event in metastasis.…”

“…We (McSherry et al, 2009) and others (Murakami et al, 2011) recently identified a significant association between JAM-A over-expression and poor prognosis of breast cancer patients. Furthermore JAM-A has been demonstrated to be a target of the microRNA miR-145, which is downregulated in breast cancer and whose over-expression decreases motility and invasive behavior in breast cancer cells (Gotte et al, 2010).…”

Low miR-145 silenced by DNA methylation promotes NSCLC cell proliferation, migration and invasion by targeting mucin 1

“…3 Emerging evidence has shown that miRNAs are involved in cancer initiation and progression. 4 MiR-145 has been reported as an important tumor suppressor gene in ovarian carcinoma, 5,6,7 malignant pleural mesothelioma, 8 breast cancer, 9 pancreatic cancer, 10,11 liposarcoma, 12 colorectal cancer, 13,14,15,16 neuroblastoma, 17 breast cancer, 18,19,20,21 esophageal cancer, 22 bladder cancer, 23,24 urothelial cancer, 25 prostate cancer, 26,27 gastric cancer, 28 and head and neck cancer, 29 and other types. MiR-145 was also implicated in the progression of NSCLC; 30,31,32 however, its exact mechanism is not well established.…”

Brain infiltration by cancer cells: different roads to the same target?

“…[22,29] In breast cancer, miR-145 suppress breast cancer cell line invasion and metastasis by targeting mucin-1, a glycoprotein that can help tumor cells to escape immunosurveillance; [30] in addition, miR-145-dependent regulation of 3'UTR of the JAM-A and fascin decreased motility and invasiveness of MDA-MB-231, MCF-7 and other breast cancer cells. [31] miRNA analysis could also be intrumental for prognostic purposes: in a retrospective study on 256 melanoma patients, divided into three cohorts, four miRNAs (miR-150-5p, miR15b-5p, miR-16-5p and miR-374b-3p) were identified as a prognostic signature that, in combination with stage, was able to distinguish primary melanomas that metastasized to the brain from non-brain metastatic primary tumors. [32] Although at the present time the biological significance of these miRNAs disregulation may be difficult to understand, nevertheless the notion, togheter with classical staging parameters, could be of great importance to clinicians to set specific therapeutic strategies.…”