Shanshan Ma

Human umbilical cord mesenchymal stem cells inhibit C6 glioma growth via secretion of dickkopf-1 (DKK1)

Mesenchymal stem cells (MSCs) represent a potential therapeutic target for glioma. We determined the molecular mechanism of inhibitory effect of human umbilical cord-derived MSCs (hUC-MSCs) on the growth of C6 glioma cells. We demonstrated that hUC-MSCs inhibited C6 cell growth and modulated the cell cycle to G0/G1 phase. The expression of β-catenin and c-Myc was downregulated in C6 cells by conditioned media from hUC-MSCs, and the levels of secreted DKK1 were positively correlated with concentrations of hUCMSCs-CM. The inhibitory effect of hUC-MSCs on C6 cell proliferation was enhanced as the concentration of DKK1 in hUCMSCs-CM increased. When DKK1 was neutralized by anti-DKK1 antibody, the inhibitory effect of hUC-MSCs on C6 cells was attenuated. Furthermore, we found that conditioned media from hUC-MSCs transfection with siRNA targeting DKK1 mRNA or pEGFPN1-DKK1 plasmid lost or enhanced the abilities to regulate the Wnt signaling in C6 cells. Therefore, hUC-MSCs inhibited C6 glioma cell growth via secreting DKK1, an inhibitor of Wnt pathway, may represent a novel therapeutic strategy for malignant glioma.

Resveratrol promotes hUC-MSCs engraftment and neural repair in a mouse model of Alzheimer’s disease

ABSTRACT Mesenchymal stem cell transplantation is a promising therapeutic approach for Alzheimers disease (AD). However, poor engraftment and limited survival rates are major obstacles for its clinical application. Resveratrol, an activator of silent information regulator 2, homolog 1 (SIRT1), regulates cell destiny and is beneficial for neurodegenerative disorders. The present study is designed to explore whether resveratrol regulates the fate of human umbilical cord‐derived mesenchymal stem cells (hUC‐MSCs) and whether hUC‐MSCs combined with resveratrol would be efficacious in the treatment of neurodegeneration in a mouse model of AD through SIRT1 signaling. Herein, we report that resveratrol facilitates hUC‐MSCs engraftment in the hippocampus of AD mice and resveratrol enhances the therapeutic effects of hUC‐MSCs in this model as demonstrated by improved learning and memory in the Morris water maze, enhanced neurogenesis and alleviated neural apoptosis in the hippocampus of the AD mice. Moreover, hUC‐MSCs and resveratrol jointly regulate expression of hippocampal SIRT1, PCNA, p53, ac‐p53, p21, and p16. These data strongly suggests that hUC‐MSCs transplantation combined with resveratrol may be an effective therapy for AD.

β-Carotene Induces Apoptosis in Human Esophageal Squamous Cell Carcinoma Cell Lines via the Cav-1/AKT/NF-κB Signaling Pathway

β‐carotene, a type of terpenoid, has many metabolic and physiological functions. In particular, β‐carotene has an antitumor effect. However, the efficacy of β‐carotene against esophageal squamous cell carcinoma (ESCC) remains unclear. In our study, β‐carotene inhibited the growth of ESCC cells and downregulated expression of the Caveolin‐1 (Cav‐1) protein. Cav‐1 protein was expressed only in ESCC cells, not in Het‐1A cells. Moreover, β‐carotene triggered apoptosis, induced cell cycle G0⁄G1 phase arrest, and inhibited cell migration. To explore the mechanism involved in these processes, we further examined the effect of β‐carotene on the Cav‐1‐mediated AKT/NF‐κB pathway. The results showed that the level of AKT and NF‐κB phosphorylation was dramatically inhibited, which led to an increase in the Bax/Bcl‐2 ratio. Correspondingly, the activity of Caspase‐3 was also enhanced. These data suggest that β‐carotene has an antiproliferative role in ESCC cells and may be a promising chemotherapeutic agent for use against ESCC cells.

Resveratrol Exerts Dosage-Dependent Effects on the Self-Renewal and Neural Differentiation of hUC-MSCs.

Resveratrol (RES) plays a critical role in the fate of cells and longevity of animals via activation of the sirtuins1 (SIRT1) gene. In the present study, we intend to investigate whether RES could promote the self-renewal and neural-lineage differentiation in human umbilical cord derived MSCs (hUC-MSCs) in vitro at concentrations ranging from 0.1 to 10 μM, and whether it exerts the effects by modulating the SIRT1 signaling. Herein, we demonstrated that RES at the concentrations of 0.1, 1 and 2.5 μM could promote cell viability and proliferation, mitigate senescence and induce expression of SIRT1 and Proliferating Cell Nuclear Antigen (PCNA) while inhibit the expression of p53 and p16. However, the effects were reversed by 5 and 10 μM of RES. Furthermore, RES could promote neural differentiation in a dose-dependent manner as evidenced by morphological changes and expression of neural markers (Nestin, βIII-tubulin and NSE), as well as pro-neural transcription factors Neurogenin (Ngn)1, Ngn2 and Mash1. Taken together, RES exerts a dosage-dependent effect on the self-renewal and neural differentiation of hUC-MSCs via SIRT1 signaling. The current study provides a new strategy to regulate the fate of hUC-MSCs and suggests a more favorable in vitro cell culture conditions for hUC-MSCs-based therapies for some intractable neurological disorders.

β-Carotene synergistically enhances the anti-tumor effect of 5-fluorouracil on esophageal squamous cell carcinoma in vivo and in vitro.

Recently, we reported that β-carotene exhibited anticancer activity against human esophageal squamous cell carcinoma cells in vitro. In the present study, we examined a novel therapeutic strategy by combining β-carotene with 5-fluorouracil (5-FU) in human esophageal cancer in vitro and in vivo, and elucidated the underlying mechanisms. We found that the combination of 5-FU and β-carotene displayed greater growth inhibitory effects than did either compound alone in esophageal squamous cell carcinoma (ESCC) cells. In addition, the combination of 5-FU and β-carotene displayed greater tumor growth inhibition in an Eca109 xenograft mouse model than did a single agent with low systemic toxicity. β-Carotene enhanced 5-FU-induced apoptosis. TUNEL staining revealed that the rate of TUNEL-positive cells was markedly increased in tumor tissues after treatment with 5-FU and β-carotene. Western blotting and immunohistochemistry revealed the down-regulation of Bcl-2 and PCNA and the up-regulation of Bax and caspase-3 in tumor tissues. Further studies demonstrated that the combined administration of 5-FU and β-carotene significantly down-regulated the protein levels of Cav-1, p-AKT, p-NF-κB, p-mTOR and p-p70S6K in Eca109 cells more effectively than did 5-FU alone. These data suggested that the combined therapy of 5-FU and β-carotene exerted synergistic antitumor effects in vivo and in vitro and could constitute a novel therapeutic treatment for ESCC.

Ets2 knockdown inhibits tumorigenesis in esophageal squamous cell carcinoma in vivo and in vitro.

Increased expression of Ets2 is reported upregulated in esophageal squamous cell carcinoma tissue. However, the function of Ets2 in carcinogenesis of ESCC is poorly understood. Here, the rise of Ets2 was confirmed in ESCC cells and Ets2 depletion by RNA interference promotes cell apoptosis, inhibits cell proliferation, attenuates cell invasion and induces cell cycle G0/G1 arrest in vitro. Moreover, in vivo, Xenograft mouse model studies showed Ets2 knockdown inhibits tumor formation and metastasis significantly. Furthermore, Ets2 depletion inactivates the mTOR/p70S6K signaling pathway both in vitro and in vivo. Taken together, these findings strongly suggest that a critical role of Ets2 in human ESCC pathogenesis via the inactivation of the mTOR/p70S6K signaling pathway.

Potential application of an injectable hydrogel scaffold loaded with mesenchymal stem cells for treating traumatic brain injury

In the past few decades, there have been potential applications for stem cell replacement therapy in the treatment of nervous system damage resulting from diseases or traumatic brain injury (TBI). However, the insufficient number of transplanted stem cells and low survival rate caused by a series of negative conditions limit the therapeutic effect. In this contribution, we developed an injectable hydrogel composed of sodium alginate (SA) and hyaluronic acid (HA) as a tissue scaffold to create a more optimal microenvironment for stem cells after implantation. The gelation time of the HA/SA hydrogel exceeded 6 min, which satisfied the requirements for injection performance, and the high ratios of water content and slower degradation speed affirmed that the HA/SA hydrogel is a preferable stem cell scaffold. As a tissue engineering scaffold, the HA/SA hydrogel exhibited appropriately porous structures for stem cell loading and good rheological behavior, which contributed to stem cell differentiation. The in vitro culture experiment proved that the HA/SA scaffold performed well on hUC-MSCs with higher viability ratio and proliferation. Further in vivo tests indicated that the HA/SA scaffold not only protected the injected human umbilical cord mesenchymal stem cells (hUC-MSCs) so that they could maintain a higher survival ratio, but it also contributed to the regeneration of endogenous nerve cells. In summary, this injectable HA/SA hydrogel has the potential to be used for stem cell tissue engineering and support the physiological function recovery of TBI patients.

Long non‑coding RNA regulates hair follicle stem cell proliferation and differentiation through PI3K/AKT signal pathway

Long non-coding RNAs (lncRNAs) are defined as non-coding transcripts (>200 nucleotides) that serve important roles in the proliferation and differentiation of stem cells. Hair follicle stem cells (HFTs) have multidirectional differentiation potential and are able to differentiate into skin, hair follicles and sebaceous glands, serving a role in skin wound healing. The aim of the present study was to analyze the regulatory role of lncRNA AK015322 (IncRNA5322) in HFTs and the potential mechanism of IncRNA5322‑mediated differentiation of HFTs. The results demonstrated that lncRNA5322 transfection promoted proliferation and differentiation in HFTs. It was identified that lncRNA5322 transfection upregulated the expression and phosphorylation of phosphoinositide 3‑kinase (PI3K) and protein kinase B (AKT) in HFTs. It was also observed that lncRNA5322 transfection upregulated microRNA (miR)‑21 and miR‑21 agonist (agomir‑21) eliminated lncRNA5322‑induced expression and phosphorylation of PI3K and AKT. The present study also demonstrated that agomir‑21 blocked IncRNA5322‑induced expression and phosphorylation of PI3K and AKT in HFTs. The results indicated that agomir‑21 transfection also suppressed the IncRNA5322‑induced proliferation and differentiation of HFTs. In conclusion, the results of the present study suggest that lncRNA5322 is able to promote the proliferation and differentiation of HFTs by targeting the miR‑21‑mediated PI3K‑AKT signaling pathway in HFTs.

BANCR contributes to the growth and invasion of melanoma by functioning as a competing endogenous RNA to upregulate Notch2 expression by sponging miR-204

BRAF-activated non-coding RNA (BANCR) is a long non-coding RNA (lncRNA) that contributes to the initiation and development of many solid tumors, including melanoma. However, the BANCR functions and downstream mechanisms are largely unknown. In this study, we aim to investigate how BANCR participates in the proliferation and migration of malignant melanoma and elucidate the underlying mechanism in this process. We found that the expression of the BANCR was low in melanocytic nevus and human melanocytes but high in melanoma tissues and cell lines. Knockdown of BANCR inhibited melanoma cell proliferation and invasion, and induced cell apoptosis. The decreased expression of relative marker proteins further demonstrated the inhibitory effect of BANCR siRNA in cell growth and migration. Then, we detected downregulation of microRNA-204 (miR‑204), a suppressor of melanoma growth, in melanoma tissues and cell lines. We identified that miR‑204 was a direct target of BANCR and neurogenic locus notch homolog protein 2 (Notch2) was a direct target of miR‑204. BANCR may promote melanoma cell growth through inhibition of miR‑204, leading to the activation of Notch2 pathway. By tumorigenicity assay in BALB/c nude mice, we further demonstrated that BANCR knockdown inhibited tumor growth in vivo. Our results suggest the BANCR/miR‑204/Notch2 axis mediates melanoma cell proliferation and tumor progression.

Overexpression of FOXQ1 enhances anti-senescence and migration effects of human umbilical cord mesenchymal stem cells in vitro and in vivo

Mesenchymal stem cells (MSCs) are unique precursor cells characterized by active self-renewal and differentiation potential. These cells offer the advantages of ease of isolation and limited ethical issues as a resource and represent a promising cell therapy for neurodegenerative diseases. However, replicative senescence during cell culture as well as low efficiency of cell migration and differentiation after transplantation are major obstacles. In our previous study, we found that FOXQ1 binds directly to the SIRT1 promoter to regulate cellular senescence and also promotes cell proliferation and migration in many tumor cell lines. Currently, little is known about the effects of FOXQ1 on normal somatic cells. Therefore, we examine the effects of FOXQ1 on senescence and migration of MSCs. Lentiviral vector-mediated overexpression of FOXQ1 in human umbilical cord mesenchymal stem cells (hUC-MSCs) resulted in enhanced cell proliferation and viability. Furthermore, the expression of proteins and markers positively associated with senescence (p16, p21, p53) was reduced, whereas expression of proteins negatively associated with senescence (SIRT1, PCNA) was promoted. Following transplantation of hUC-MSCs overexpressing FOXQ1 in an animal model of Alzheimer’s disease (APPV717I transgenic mice) resulted in amelioration of the effects of Alzheimer’s disease (AD) on cognitive function and pathological senescence accompanied the increased numbers of hUC-MSCs in the AD brain. In conclusion, FOXQ1 overexpression promotes anti-senescence and migration of hUC-MSCs in vitro and in vivo. These findings also suggest that this strategy may contribute to optimization of the efficiency of stem cell therapy.