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Katayoon Pakravan

Bio: Katayoon Pakravan is an academic researcher from Tarbiat Modares University. The author has contributed to research in topics: Endothelial stem cell & Microvesicles. The author has an hindex of 6, co-authored 12 publications receiving 226 citations.

Papers
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Journal ArticleDOI
TL;DR: The findings suggest that exosomal transfer of miR-100 may be a novel mechanism underlying the paracrine effects of MSC-derived exosomes and may provide a means by which these vesicles can modulate vascular responses within the microenvironment of breast cancer cells.
Abstract: Human mesenchymal stem cells (MSCs) have been shown to be involved in the formation and modulation of tumor stroma and in interacting with tumor cells, partly through their secretome. Exosomes are nano-sized intraluminal multi-vesicular bodies secreted by most types of cells and have been found to mediate intercellular communication through the transfer of genetic information via coding and non-coding RNAs to recipient cells. Since exosomes are considered as protective and enriched sources of shuttle microRNAs (miRNAs), we hypothesized that exosomal transfer of miRNAs from MSCs may affect tumor cell behavior, particularly angiogenesis. Exosomes derived from MSCs were isolated and characterized by scanning electron microscopy analyses, dynamic light scattering measurements, and Western blotting. Fold changes in miR-100 expression levels were calculated in exosomes and their corresponding donor cells by qRT-PCR. The effects of exosomal transfer of miR-100 from MSCs were assessed by qRT-PCR and Western blotting of the mTOR/HIF-1α/VEGF signaling axis in breast cancer cells. The quantification of secreted VEGF protein was determined by enzyme-linked immunosorbent assay. The putative paracrine effects of MSC-derived exosomes on tumor angiogenesis were explored by in vitro angiogenesis assays including endothelial cell proliferation, migration and tube formation assays. We found that MSC-derived exosomes induce a significant and dose-dependent decrease in the expression and secretion of vascular endothelial growth factor (VEGF) through modulating the mTOR/HIF-1α signaling axis in breast cancer-derived cells. We also found that miR-100 is enriched in MSC-derived exosomes and that its transfer to breast cancer-derived cells is associated with the down-regulation of VEGF in a time-dependent manner. The putative role of exosomal miR-100 transfer in regulating VEGF expression was substantiated by the ability of anti-miR-100 to rescue the inhibitory effects of MSC-derived exosomes on the expression of VEGF in breast cancer-derived cells. In addition, we found that down-regulation of VEGF mediated by MSC-derived exosomes can affect the vascular behavior of endothelial cells in vitro. Overall, our findings suggest that exosomal transfer of miR-100 may be a novel mechanism underlying the paracrine effects of MSC-derived exosomes and may provide a means by which these vesicles can modulate vascular responses within the microenvironment of breast cancer cells.

227 citations

Journal ArticleDOI
TL;DR: A growing body of evidence indicates that the selective targeting of LSCs represents a promising approach to improve disease outcome, and the CSC hypothesis has added a new dimension to the area of anticancer research, thereby paving the way for shaping a new trend in cancer therapy.
Abstract: Background Cancer stem cells (CSCs), also known as tumor-initiating cells (TICs), are characterized by high self-renewal and multi-lineage differentiation capacities. CSCs are thought to play indispensable roles in the initiation, progression and metastasis of many types of cancer. Leukemias are thought to be initiated and maintained by a specific sub-type of CSC, the leukemia stem cell (LSC). An important feature of LSCs is their resistance to standard therapy, which may lead to relapse. Increasing efforts are aimed at developing novel therapeutic strategies that selectively target LSCs, while sparing their normal counterparts and, thus, minimizing adverse treatment-associated side-effects. These LSC targeting therapies aim to eradicate LSCs through affecting mechanisms that control their survival, self-renewal, differentiation, proliferation and cell cycle progression. Some LSC targeting therapies have already been proven successful in pre-clinical studies and they are now being tested in clinical studies, mainly in combination with conventional treatment regimens.

25 citations

Journal ArticleDOI
TL;DR: It is confirmed that serum-derived miRNAs have a strong potential to be a diagnostic biomarker for patients with CRC, and were significantly up-regulated in CRC patients, while miR-143 and mi-145 showed a significant down-regulation.

25 citations

Journal Article
TL;DR: The current literature on administration of exosomes released by mesenchymal stem cells in regenerative medicine is summarized and how they could help to improve tissue regeneration following injury is suggested.
Abstract: Mesenchymal stem cells have emerged as promising therapeutic candidates in regenerative medicine. The mechanisms underlying mesenchymal stem cells regenerative properties were initially attributed to their engraftment in injured tissues and their subsequent transdifferentiation to repair and replace damaged cells. However, studies in animal models and patients indicated that the low number of transplanted mesenchymal stem cells localize to the target tissue and transdifferentiate to appropriate cell lineage. Instead the regenerative potential of mesenchymal stem cells has been found - at least in part - to be mediated via their paracrine actions. Recently, a secreted group of vesicles, called "exosome" has been identified as major mediator of mesenchymal stem cells therapeutic efficacy. In this review, we will summarize the current literature on administration of exosomes released by mesenchymal stem cells in regenerative medicine and suggest how they could help to improve tissue regeneration following injury.

23 citations

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the potential clinical significance of a signature of four circulating serum-derived miRNAs in colorectal cancer patients and demonstrated that extracellular vesicles (EVs) containing miR-221-3p could facilitate endothelial cell angiogenesis.

20 citations


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01 Nov 2013
TL;DR: In this article, a review of the interactions between EMT-inducing transcription factors and epigenetic modulators during cancer progression and the therapeutic implications of exploiting this intricate regulatory process is presented.
Abstract: Epithelial-mesenchymal transitions (EMTs) are a key requirement for cancer cells to metastasize and colonize in a new environment. Epithelial-mesenchymal plasticity is mediated by master transcription factors and is also subject to complex epigenetic regulation. This Review outlines our current understanding of the interactions between EMT-inducing transcription factors and epigenetic modulators during cancer progression and the therapeutic implications of exploiting this intricate regulatory process. During the course of malignant cancer progression, neoplastic cells undergo dynamic and reversible transitions between multiple phenotypic states, the extremes of which are defined by the expression of epithelial and mesenchymal phenotypes. This plasticity is enabled by underlying shifts in epigenetic regulation. A small cohort of pleiotropically acting transcription factors is widely recognized to effect these shifts by controlling the expression of a constituency of key target genes. These master regulators depend on complex epigenetic regulatory mechanisms, notably the induction of changes in the modifications of chromatin-associated histones, in order to achieve the widespread changes in gene expression observed during epithelial-mesenchymal transitions (EMTs). These associations indicate that an understanding of the functional interactions between such EMT-inducing transcription factors and the modulators of chromatin configuration will provide crucial insights into the fundamental mechanisms underlying cancer progression and may, in the longer term, generate new diagnostic and therapeutic modalities for treating high-grade malignancies.

797 citations

Journal ArticleDOI
TL;DR: The role of exosome contents in cancer, focusing on proteins and noncoding RNA; the interaction between exosomes and tumor microenvironment; the mechanisms that epithelial-mesenchymal transition, invasion and migration of tumor affected by exosomers; and tumor suppression strategies based on exosomal components are summarized.
Abstract: Exosomes are extracellular vesicles secreted by most eukaryotic cells and participate in intercellular communication. The components of exosomes, including proteins, DNA, mRNA, microRNA, long noncoding RNA, circular RNA, etc., which play a crucial role in regulating tumor growth, metastasis, and angiogenesis in the process of cancer development, and can be used as a prognostic marker and/or grading basis for tumor patients. Hereby, we mainly summarized as followed: the role of exosome contents in cancer, focusing on proteins and noncoding RNA; the interaction between exosomes and tumor microenvironment; the mechanisms that epithelial-mesenchymal transition, invasion and migration of tumor affected by exosomes; and tumor suppression strategies based on exosomes. Finally, the application potential of exosomes in clinical tumor diagnosis and therapy is prospected, which providing theoretical supports for using exosomes to serve precise tumor treatment in the clinic.

475 citations

26 Feb 2009
TL;DR: The EMT process may facilitate the generation of cancer cells with the mesenchymal traits needed for dissemination as well as the self-renewal properties needed for initiation of secondary tumors.
Abstract: During cancer progression, some cells within the primary tumor may reactivate a latent embryonic program known as epithelial-to-mesenchymal transition (EMT). Through EMT, transformed epithelial cells can acquire the mesenchymal traits that seem to facilitate metastasis. Indeed, there is accumulating evidence that EMT and mesenchymal-related gene expression are associated with aggressive breast cancer subtypes and poor clinical outcome in breast cancer patients. More recently, the EMT program was shown to endow normal and transformed mammary epithelial cells with stem cell properties, including the ability to self-renew and efficiently initiate tumors. This link between EMT and stem cells may have numerous implications in the progression of breast tumors. The EMT process may facilitate the generation of cancer cells with the mesenchymal traits needed for dissemination as well as the self-renewal properties needed for initiation of secondary tumors. Breast cancer stem cells are resistant to many conventional cancer therapies, which can promote tumor relapse. Therefore, the generation of cancer stem cells by EMT may promote the development of refractory and resistant breast tumors. The purpose of this review is to summarize the findings related to EMT and stem cells in cancer progression and therapy resistance.

330 citations

Journal ArticleDOI
TL;DR: MSCIPFP-derived exosomes protect articular cartilage from damage and ameliorate gait abnormality in OA mice by maintaining cartilage homeostasis, the mechanism of which may be related to miR100-5p-regulated inhibition of mTOR-autophagy pathway.

297 citations

Journal ArticleDOI
TL;DR: This review summarizes the recent progress of particular mechanisms underlying the tissue regenerative properties and immunomodulatory effects of MSCs and focused on discussing the functional roles of paracrine activities, direct cell–cell contact, mitochondrial transfer, and extracellular vesicles related to MSC-mediated effects on immune cell responses, cell survival, and regeneration.
Abstract: Mesenchymal stem cells (MSCs) have been extensively investigated for the treatment of various diseases. The therapeutic potential of MSCs is attributed to complex cellular and molecular mechanisms of action including differentiation into multiple cell lineages and regulation of immune responses via immunomodulation. The plasticity of MSCs in immunomodulation allow these cells to exert different immune effects depending on different diseases. Understanding the biology of MSCs and their role in treatment is critical to determine their potential for various therapeutic applications and for the development of MSC-based regenerative medicine. This review summarizes the recent progress of particular mechanisms underlying the tissue regenerative properties and immunomodulatory effects of MSCs. We focused on discussing the functional roles of paracrine activities, direct cell–cell contact, mitochondrial transfer, and extracellular vesicles related to MSC-mediated effects on immune cell responses, cell survival, and regeneration. This will provide an overview of the current research on the rapid development of MSC-based therapies.

271 citations