Valbona Luga,1,2,5 Liang Zhang,1,5 Alicia M. Viloria-Petit,3 Abiodun A. Ogunjimi,1 Mohammad R. Inanlou,1 Elaine Chiu,1 Marguerite Buchanan,4 Abdel Nasser Hosein,4 Mark Basik,4 and Jeffrey L. Wrana1,2,*

Cell

Communication between cancer cells and the associated stroma plays a key role in driving tumor progression, but how stromal cues might act to specifically promote cancer metastasis is less clear. Here,，the authors revealed that fibroblast-secreted exosomes play a key role in promoting breast cancer cell (BCC) motility and metastasis by mobilizing autocrine Wnt-PCP signaling in tumor cells. Firstly, they discovered that conditioned media from mouse fibroblast L cells, potently stimulated the protrusive activity and motility of human breast adenocarcinoma MDA-MB-231, SUM-159PT, MDA-MB-468, and T-47D cells, mouse carcinoma EMT-6 by examined three-dimensional (3D) Matrigel cultures. then , they used siRNA to downregulate expression of the core PCP pathway components, including Fzd6, Dvl1, Pk1, and Vangl1. Strikingly, interference with Dvl1, Fzd6, and Vangl1 inhibited active-conditioned medium (ACM)-induced cell protrusions and motility. Through colocalization, they demonstrate that in ACM-stimulated BCCs, Fzd-Dvl and Vangl-Pk are asymmetrically distributed with respect to cellular protrusions, in a manner analogous to planar-polarized epithelial cells, Because genetic studies in developmental models show that Wnt ligands, including Wnt5a and Wnt11, are key regulators of the PCP signaling pathway, so they knocked down Porcupine expression in MDA-MB-231 cells  and observed potent inhibition of ACM-induced protrusive activity and motility. Furthermore, knockdown of Wnt11, but not Wnt5a, also interfered with ACM activity, next by immunofluorescence, they demonstrated that ACM stimulates autocrine Wnt11 association with Fzd6 and activation of PCP signaling during BCC protrusive activity and motility.

To identify the L cells secrete factor, they fractionated ACM by size exclusion chromatography.Further purification by ion-exchange, chromatography yielded a final active fraction,Analysis using David bioinformatics tools followed by manual annotation revealed that the active fraction was highly enriched in proteins associated with vesicles ,in particular exosome components such as the tetraspanin CD81 and its partners Igsf8 and Ptgfrn,In the end, they proved that CD81-positive exosomes promote BCC motility and metastasis.

Di Liu1, Qian Lu1,2, Xing Wang1, Jun Wang3, Ning Lu4, Zefei Jiang5, Xiaopeng Hao5, Jianbin Li5,6, Jing Liu1, Pengbo Cao1, Guilin Peng1

Cell Research

Macrophages have been suggested to contribute to constructing a cancer stem cell (CSC) niche. However, whether and how macrophages regulate the activity of CSCs through juxtacrine signaling are poorly understood. Here the authors report LSECtin, a transmembrane protein highly expressed on tumor-associated macrophages (TAMs), enhances stemness of breast cancer cells (BCCs).in this paper, they first determined whether LSECtin is expressed on macrophages inhuman breast tumor tissues, theyfound LSECtin was expressed in 31/ 42 specimens,Moreover, flow cytometric analysis revealedLSECtin surface expression by macrophages in 10/10 breast cancer specimens examined,they next characterized LSECtin expression in mouse models, where LSECtin+ cells co-expressed the murine macrophage marker F4/80 in the human xenograft tumors, the major populations of myeloid cells including TAMs, monocytes (Mo) and tumor-associated neutrophils (TAN) were identified. RT-PCR revealed higher Lsectin expression in TAMs than in other subpopulations,then ,they next examined the mechanism by which macrophage expressed LSECtin promotes tumor growth, they found that the CD90+ CSCs were significantly reduced in human xenograft tumors in hosts with systemic LSECtin knockout or macrophage specific LSECtin knockout. The authorsspeculated that protein(s) that interact with LSECtin are present on the surfaces of BCCs. To identify the membrane interaction proteins through expression cloning, they transduced a commercial human cDNA library into HEK293 cells that were negative for LSECtin binding. and identified as BTN3A3, a B7-related butyrophilin family member with unclear functions.then they examined BTN3A3 protein expression using the Human Protein Atlas database.25 The total 11 breast cancer samples contained BTN3A3-positive tumor cells.Further, to determine whether LSECtin drives stemness through interaction with BTN3A3 in vitro, they generated BTN3A3 agonists, exhibited great ability to block sphere formation induced by recombinant LSECtin.They next explored the signal transduction mechanisms that might be responsible for the LSECtin-BTN3A3 axis,and found that LSECtin recombinant protein promoted phosphorylation of STAT3 but not other STATs in control cells but not in BTN3A3-KD cells, they first verified the association of BTN3A3expression and stemness in vivo, and found knockdown of BTN3A3 in tumor cells markedly reduced tumor incidence and growth in mice with admixture of WT-TAMs, there was no similar effect in mice with admixture of KO-TAMs.

In the end,The researchers analyzed the expression of BTN3A3 in breast cancer clinical samples and found that the expression of BTN3A3 was significantly higher in breast cancer than in other breast cancers, and was positively correlated with poor prognosis.