Human mesenchymal stem/stromal cells (hMSCs) have been shown to support breast cancer cell proliferation and metastasis, partly through their secretome. hMSCs have a remarkable ability to survive for long periods under stress, and their secretome is tumor supportive. In this study, we have characterized the cargo of extracellular vesicular (EV) fraction (that is in the size range of 40-150nm) of serum deprived hMSCs (SD-MSCs). Next Generation Sequencing assays were used to identify small RNA secreted in the EVs, which indicated presence of tumor supportive miRNA. Further assays demonstrated the role of miRNA-21 and 34a as tumor supportive miRNAs. Next, proteomic assays revealed the presence of ≈150 different proteins, most of which are known tumor supportive factors such as PDGFR-β, TIMP-1, and TIMP-2. Lipidomic assays verified presence of bioactive lipids such as sphingomyelin. Furthermore, metabolite assays identified the presence of lactic acid and glutamic acid in EVs. The co-injection xenograft assays using MCF-7 breast cancer cells demonstrated the tumor supportive function of these EVs. To our knowledge this is the first comprehensive -omics based study that characterized the complex cargo of extracellular vesicles secreted by hMSCs and their role in supporting breast cancers.

Stem cells are proposed to continuously secrete trophic factors that potentially serve as mediators of autocrine and paracrine activities, associated with reprogramming of the tumor microenvironment, tissue regeneration, and repair. Hitherto, significant efforts have been made to understand the level of underlying paracrine activities influenced by stem cell secreted trophic factors, as little is known about these interactions. Recent findings, however, elucidate this role by reporting the effects of stem cell derived extracellular vesicles (EVs) that mimic the phenotypes of the cells from which they originate. Exchange of genetic information utilizing persistent bidirectional communication mediated by stem cell-EVs could regulate stemness, self-renewal, and differentiation in stem cells and their subpopulations. This review therefore discusses stem cell-EVs as evolving communication factors in stem cell biology, focusing on how they regulate cell fates by inducing persistent and prolonged genetic reprogramming of resident cells in a paracrine fashion. In addition, we address the role of stem cell-secreted vesicles in shaping the tumor microenvironment and immunomodulation and in their ability to stimulate endogenous repair processes during tissue damage. Collectively, these functions ensure an enormous potential for future therapies.

We observed that microRNAs (miRNAs) that regulate differentiation in a variety of simpler systems also regulate differentiation of human multipotent stromal cells (hMSCs) from bone marrow. Differentiation of hMSCs into osteoblasts and adipocytes was inhibited by using lentiviruses expressing shRNAs to decrease expression of Dicer and Drosha, two enzymes that process early transcripts to miRNA. Expression analysis of miRNAs during hMSC differentiation identified 19 miRNAs that were up-regulated during osteogenic differentiation and 20 during adipogenic differentiation, 11 of which were commonly up-regulated in both osteogenic and adipogenic differentiation. In silico models predicted that five of the up-regulated miRNAs targeted leukemia inhibitory factor (LIF) expression. The prediction was confirmed for two of the miRNAs, hsa-mir 199a and hsa-mir346, in that over-expression of the miRNAs decreased LIF secretion by hMSCs. The results demonstrate that differentiation of hMSCs is regulated by miRNAs and that several of these miRNAs target LIF.hsa-mir199a ͉ hsa-mir346 ͉ stem cells ͉ plasticity H uman multipotent stromal cells (hMSCs) from bone marrow, also known as mesenchymal stem cells, are progenitor cells capable of differentiating into a variety of mature tissues (1). hMSCs can be isolated easily as single cell clones and differentiated into osteoblasts and adipocytes as well as other cellular phenotypes in culture. The cells hold great promise for therapy but the molecular mechanisms that govern the plasticity and differentiation remain unclear. Recently, the existence and function of a class of small, noncoding RNA molecules known as microRNAs (miRNAs) have gained attention as regulatory molecules. These genomically encoded RNAs undergo several modifications before being converted into mature 21-23 base pair transcripts capable of gene silencing. Biogenesis of functional miRNAs involves several enzymes, including Dicer and Drosha. Previous studies demonstrated that decreased expression of Dicer in Drosophila, zebrafish, and mice restricts the differentiation potential of stem cells (2-5). Studies have also demonstrated that specific miRNAs regulate gene expression during germ line development and cellular differentiation (2-6), including playing key roles in hematopoiesis as well as myogenic and neurogenic function (7-11). However, much of the work on miRNAs has focused on simpler organisms with very little data on human miRNAs. In this study we investigated the role of miRNAs in hMSCs, focusing first on the need for miRNA processing enzymes in hMSC differentiation. Then, we identified the key miRNAs that may regulate differentiation of hMSCs. Finally, we demonstrated that two of the miRNAs target leukemia inhibitory factor (LIF), the expression of which decreases as hMSCs differentiate. Results Generation of a Stable Knockdown of Dicer and Drosha in hMSCs.As a first step toward identifying the role of miRNAs in the differentiation of hMSCs, we analyzed the effect of decreasing the expression of key proteins...

The delivery of curcumin, a broad-spectrum anticancer drug, has been explored in the form of liposomal nanoparticles to treat osteosarcoma (OS). Curcumin is water insoluble and an effective delivery route is through encapsulation in cyclodextrins followed by a second encapsulation in liposomes. Liposomal curcumin’s potential was evaluated against cancer models of mesenchymal (OS) and epithelial origin (breast cancer). The resulting 2-Hydroxypropyl-γ-cyclodextrin/curcumin - liposome complex shows promising anticancer potential both in vitro and in vivo against KHOS OS cell line and MCF-7 breast cancer cell line. An interesting aspect is that liposomal curcumin initiates the caspase cascade that leads to apoptotic cell death in vitro in comparison with DMSO-curcumin induced autophagic cell death. In addition, the efficiency of the liposomal curcumin formulation was confirmed in vivo using a xenograft OS model. Curcumin-loaded γ-cyclodextrin liposomes indicate significant potential as delivery vehicles for the treatment of cancers of different tissue origin. From the Clinical Editor Curcumin-loaded γ-cyclodextrin liposomes were demonstrated in vitro to have significant potential as delivery vehicles for the treatment of cancers of mesenchymal and epithelial origin. Differences between mechanisms of cell death were also evaluated.

In recent years, the knowledge about the control of tumor microenvironment has increased and emerged as an important player in tumorigenesis. The role of normal stromal cells in the tumor initiation and progression has brought our vision in to the forefront of cell-to-cell communication. In this review, we focus on the mechanism of communication between stromal and tumor cells, which is based on the exchange of extracellular vesicles (EVs). We describe several, evergrowing, pieces of evidence that EVs transfer messages through their miRNA, lipid, protein and nucleic acid contents. A better understanding of this sophisticated method of communication between normal cancer cells may lead to developing novel approaches for personalized diagnostics and therapeutics.