Mesenchymal Stem Cell-Mediated Therapy of Peripheral Artery Disease Is Stimulated by a Lamin A-Progerin Binding Inhibitor

Objective@#Human adipose tissue-derived mesenchymal stem cells (ASCs) have been reported to promote angiogenesis and tissue repair. However, poor survival and engraftment efficiency of transplanted ASCs are the major bottlenecks for therapeutic application. The present study aims to improve the therapeutic efficacy of ASCs for peripheral artery diseases. @*Methods@#Hydrogen peroxide (H2O2) was used to induce apoptotic cell death in ASCs.To measure apoptosis, we used flow cytometry-based apoptosis analysis and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. A murine hindlimb ischemia model was established to measure the ASC-mediated therapeutic angiogenesis and in vivo survival ability of ASCs. @*Results@#We identified that the inhibitor of lamin A-progerin binding, JH4, protects ASCs against H2O2-induced oxidative stress and apoptosis. Co-administration of ASCs with JH4 improved ASC-mediated blood reperfusion recovery and limb salvage compared to that of the control group in a mouse hind limb ischemia model. Immunofluorescence showed that JH4 treatment potentiated ASC-mediated vascular regeneration via reducing ASC apoptosis post transplantation. @*Conclusion@#JH4 exerts anti-apoptotic effects in ASCs in conditions of oxidative stress, and contributes to the repair of ischemic hind limb injury by improving cell survival.

Trib2 regulates the pluripotency of embryonic stem cells and enhances reprogramming efficiency

Embryonic stem (ES) cells are pluripotent cells characterized by self-renewability and differentiation potential. Induced pluripotent stem (iPS) cells are ES cell-equivalent cells derived from somatic cells by the introduction of core reprogramming factors. ES and iPS cells are important sources for understanding basic biology and for generating therapeutic cells for clinical applications. Tribbles homolog 2 (Trib2) functions as a scaffold in signaling pathways. However, the relevance of Trib2 to the pluripotency of ES and iPS cells is unknown. In the present study, we elucidated the importance of Trib2 in maintaining pluripotency in mouse ES cells and in generating iPS cells from somatic cells through the reprogramming process. Trib2 expression decreased as ES cells differentiated, and Trib2 knockdown in ES cells changed their colony morphology while reducing the activity of alkaline phosphatase and the expression of the pluripotency marker genes Oct4, Sox2, Nanog and Klf4. Trib2 directly interacted with Oct4 and elevated Oct4 promoter activity. During the generation of iPS cells, Trib2 knockdown decreased the reprogramming efficiency of mouse embryonic fibroblasts, whereas Trib2 overexpression significantly increased their reprogramming efficiency. In summary, our results suggest that Trib2 is important for maintaining self-renewal in ES cells and for pluripotency induction during the reprogramming process.

Role of TAZ in Lysophosphatidic Acid-Induced Migration and Proliferation of Human Adipose-Derived Mesenchymal Stem Cells

Transcriptional co-activator with a PDZ-binding motif (TAZ) is an important factor in lysophosphatidic acid (LPA)-induced promotion of migration and proliferation of human mesenchymal stem cells (MSCs). The expression of TAZ significantly increased at 6 h after LPA treatment, and TAZ knockdown inhibited the LPA-induced migration and proliferation of MSCs. In addition, embryonic fibroblasts from TAZ knockout mice exhibited the reduction in LPA-induced migration and proliferation. The LPA1 receptor inhibitor Ki16425 blocked LPA responses in MSCs. Although TAZ knockdown or knockout did not reduce LPA-induced phosphorylation of ERK and AKT, the MEK inhibitor U0126 or the ROCK inhibitor Y27632 blocked LPA-induced TAZ expression along with the reduction in the proliferation and migration of MSCs. Our data suggest that TAZ is an important mediator of LPA signaling in MSCs in the downstream of MEK and ROCK signaling.

Role of TAZ in Lysophosphatidic Acid-Induced Migration and Proliferation of Human Adipose-Derived Mesenchymal Stem Cells

Transcriptional co-activator with a PDZ-binding motif (TAZ) is an important factor in lysophosphatidic acid (LPA)-induced promotion of migration and proliferation of human mesenchymal stem cells (MSCs). The expression of TAZ significantly increased at 6 h after LPA treatment, and TAZ knockdown inhibited the LPA-induced migration and proliferation of MSCs. In addition, embryonic fibroblasts from TAZ knockout mice exhibited the reduction in LPA-induced migration and proliferation. The LPA1 receptor inhibitor Ki16425 blocked LPA responses in MSCs. Although TAZ knockdown or knockout did not reduce LPA-induced phosphorylation of ERK and AKT, the MEK inhibitor U0126 or the ROCK inhibitor Y27632 blocked LPA-induced TAZ expression along with the reduction in the proliferation and migration of MSCs. Our data suggest that TAZ is an important mediator of LPA signaling in MSCs in the downstream of MEK and ROCK signaling.

Crucial role of HMGA1 in the self-renewal and drug resistance of ovarian cancer stem cells

Cancer stem cells are a subpopulation of cancer cells characterized by self-renewal ability, tumorigenesis and drug resistance. The aim of this study was to investigate the role of HMGA1, a chromatin remodeling factor abundantly expressed in many different cancers, in the regulation of cancer stem cells in ovarian cancer. Spheroid-forming cancer stem cells were isolated from A2780, SKOV3 and PA1 ovarian cancer cells by three-dimensional spheroid culture. Elevated expression of HMGA1 was observed in spheroid cells along with increased expression of stemness-related genes, such as SOX2, KLF4, ALDH, ABCB1 and ABCG2. Furthermore, spheroid A2780 cells, compared with adherent cells, showed higher resistance to chemotherapeutic agents such as paclitaxel and doxorubicin. HMGA1 knockdown in spheroid cells reduced the proliferative advantage and spheroid-forming efficiency of the cells and the expression of stemness-related genes. HMGA1 overexpression in adherent A2780 cells increased cancer stem cell properties, including proliferation, spheroid-forming efficiency and the expression of stemness-related genes. In addition, HMGA1 regulated ABCG2 promoter activity through HMGA1-binding sites. Knockdown of HMGA1 in spheroid cells reduced resistance to chemotherapeutic agents, whereas the overexpression of HMGA1 in adherent ovarian cancer cells increased resistance to chemotherapeutic agents in vitro. Furthermore, HMGA1-overexpressing A2780 cells showed a significant survival advantage after chemotherapeutic agent treatment in a xenograft tumorigenicity assay. Together, our results provide novel insights regarding the critical role of HMGA1 in the regulation of the cancer stem cell characteristics of ovarian cancer cells, thus suggesting that HMGA1 may be an important target in the development of therapeutics for ovarian cancer patients.

Kruppel-like factor 4 mediates lysophosphatidic acid-stimulated migration and proliferation of PC3M prostate cancer cells

Prostate cancer is the most frequently diagnosed malignancy and the second leading cause of cancer mortality among men in the United States. Accumulating evidence suggests that lysophosphatidic acid (LPA) serves as an autocrine/paracrine mediator to affect initiation, progression and metastasis of prostate cancer. In the current study, we demonstrate that LPA stimulates migration and proliferation of highly metastatic human prostate cancer, PC-3M-luc-C6 cells. LPA-induced migration of PC-3M-luc-C6 cells was abrogated by pretreatment of PC-3M-luc-C6 cells with the LPA receptor 1/3 inhibitor Ki16425 or small interfering RNA (siRNA)-mediated silencing of endogenous LPA receptor 1, implicating a key role of the LPA-LPA receptor 1 signaling axis in migration of PC-3M-luc-C6 cells. In addition, LPA treatment resulted in augmented expression levels of Kruppel-like factor 4 (KLF4), and siRNA or short-hairpin RNA (shRNA)-mediated silencing of KLF4 expression resulted in the abolishment of LPA-stimulated migration and proliferation of PC-3M-luc-C6 cells. shRNA-mediated silencing of KLF4 expression resulted in the inhibition of in vivo growth of PC-3M-luc-C6 cells in a xenograft transplantation animal model. Taken together, these results suggest a key role of LPA-induced KLF4 expression in cell migration and proliferation of prostate cancer cells in vitro and in vivo.