Human mesenchymal stem cells overexpressing pigment epithelium-derived factor inhibit hepatocellular carcinoma in nude mice. Oncogene. 2010;29:2784-2794. [PMID: 20190814 DOI: 10.1038/onc.2010.38]

Advances and clinical challenges of mesenchymal stem cell therapy

In recent years, cell therapy has provided desirable properties for promising new drugs. Mesenchymal stem cells are promising candidates for developing genetic engineering and drug delivery strategies due to their inherent properties, including immune regulation, homing ability and tumor tropism. The therapeutic potential of mesenchymal stem cells is being investigated for cancer therapy, inflammatory and fibrotic diseases, among others. Mesenchymal stem cells are attractive cellular carriers for synthetic nanoparticles for drug delivery due to their inherent homing ability. In this review, we comprehensively discuss the various genetic and non-genetic strategies of mesenchymal stem cells and their derivatives in drug delivery, tumor therapy, immune regulation, tissue regeneration and other fields. In addition, we discuss the current limitations of stem cell therapy and the challenges in clinical translation, aiming to identify important development areas and potential future directions.

The Various Roles of PEDF in Cancer

Pigment epithelium-derived factor (PEDF) is a natural immunomodulator, anti-inflammatory, anti-angiogenic, anti-tumour growth and anti-metastasis factor, which can enhance tumour response to PEDF but can also conversely have pro-cancerous effects. Inflammation is a major cause of cancer, and it has been proven that PEDF has anti-inflammatory properties. PEDF's functional activity can be investigated through measuring metastatic and metabolic biomarkers that will be discussed in this review.

What should be the future direction of development in the field of prostate cancer with lung metastasis?

BACKGROUND

Since the start of the 21st century, prostate cancer with lung metastasis (PCLM) has accumulated significant scientific research output. However, a systematic knowledge framework for PCLM is still lacking.

AIM

To reconstruct the global knowledge system in the field of PCLM, sort out hot research directions, and provide reference for the clinical and mechanism research of PCLM.

METHODS

We retrieved 280 high-quality papers from the Web of Science Core Collection and conducted a bibliometric analysis of keywords, publication volume, and citation frequency. Additionally, we selected differentially expressed genes from global high-throughput datasets and performed enrichment analysis and protein-protein interaction analysis to further summarize and explore the mechanisms of PCLM.

RESULTS

PCLM has received extensive attention over the past 22 years, but there is an uneven spatial distribution in PCLM research. In the clinical aspect, the treatment of PCLM is mainly based on chemotherapy and immunotherapy, while diagnosis relies on methods such as prostate-specific membrane antigen positron emission tomography/computed tomography. In the basic research aspect, the focus is on cell adhesion molecules and signal transducer and activator of transcription 3, among others. Traditional treatments, such as chemotherapy, remain the mainstay of PCLM treatment, while novel approaches such as immunotherapy have limited effectiveness in PCLM. This study reveals for the first time that pathways related to coronavirus disease 2019, cytokine-cytokine receptor interaction, and ribosome are closely associated with PCLM.

CONCLUSION

Future research should focus on exploring and enhancing mechanisms such as cytokine-cytokine receptor interaction and ribosome and improve existing mechanisms like cadherin binding and cell adhesion molecules.

Multiple Dimensions of using Mesenchymal Stem Cells for Treating Liver Diseases: From Bench to Beside

Liver diseases impose a huge burden worldwide. Although hepatocyte transplantation has long been considered as a potential strategy for treating liver diseases, its clinical implementation has created some obvious limitations. As an alternative strategy, cell therapy, particularly mesenchymal stem cell (MSC) transplantation, is widely used in treating different liver diseases, including acute liver disease, acute-on-chronic liver failure, hepatitis B/C virus, autoimmune hepatitis, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, alcoholic liver disease, liver fibrosis, liver cirrhosis, and hepatocellular carcinoma. Here, we summarize the status of MSC transplantation in treating liver diseases, focusing on the therapeutic mechanisms, including differentiation into hepatocyte-like cells, immunomodulating function with a variety of immune cells, paracrine effects via the secretion of various cytokines and extracellular vesicles, and facilitation of homing and engraftment. Some improved perspectives and current challenges are also addressed. In summary, MSCs have great potential in the treatment of liver diseases based on their multi-faceted characteristics, and more accurate mechanisms and novel therapeutic strategies stemming from MSCs will facilitate clinical practice.

NANO-SBT-PEDF delivery system: A promising approach against ovarian cancer?

Pigment epithelium-derived factor (PEDF) is a secreted glycoprotein involved in various biological processes. Its expression declines during ovarian carcinogenesis where it could decrease macrophages polarization, inhibit angiogenesis and induce apoptosis. Altogether, PEDF represents an ideal anti-cancer agent against ovarian cancer. We previously proposed the non-viral Sleeping Beauty transposon (SBT) system to stably integrate the PEDF transgene into ovarian cancer cells. Here, we report the development of liposomes and lipid nanoparticles for SBT-PEDF gene therapy. We determined that the SBT-PEDF nanolipid delivery system was the best system to increase the expression of PEDF in ovarian cancer spheroids. We also developed an ex vivo model of ovarian tumors which allowed us to show that nanolipoplexe in combination to paclitaxel exhibits synergistic and effective anti-tumor efficacy on ovarian tumors. These findings demonstrate that lipid nanoparticle for SBT-PEDF gene therapy may be a promising therapeutic approach for ovarian cancer.

Mesenchymal stem cells: A living carrier for active tumor-targeted delivery

The strategy of using mesenchymal stem cells (MSCs) as a living carrier for active delivery of therapeutic agents targeting tumor sites has been attempted in a wide range of studies to validate the feasibility and efficacy for tumor treatment. This approach reveals powerful tumor targeting and tumor penetration. In addition, MSCs have been confirmed to actively participate in immunomodulation of the tumor microenvironment. Thus, MSCs are not inert delivery vehicles but have a strong impact on the fate of tumor cells. In this review, these active properties of MSCs are addressed to highlight the advantages and challenges of using MSCs for tumor-targeted delivery. In addition, some of the latest examples of using MSCs to carry a variety of anti-tumor agents for tumor-targeted therapy are summarized. Recent technologies to improve the performance and safety of this delivery strategy will be introduced. The advances, applications, and challenges summarized in this review will provide a general understanding of this promising strategy for actively delivering drugs to tumor tissues.

Mesenchymal stem cell homing to improve therapeutic efficacy in liver disease

Mesenchymal stem cell (MSC) transplantation, as an alternative strategy to orthotopic liver transplantation, has been evaluated for treating end-stage liver disease. Although the therapeutic mechanism of MSC transplantation remains unclear, accumulating evidence has demonstrated that MSCs can regenerate tissues and self-renew to repair the liver through differentiation into hepatocyte-like cells, immune regulation, and anti-fibrotic mechanisms. Multiple clinical trials have confirmed that MSC transplantation restores liver function and alleviates liver damage. A sufficient number of MSCs must be home to the target tissues after administration for successful application. However, inefficient homing of MSCs after systemic administration is a major limitation in MSC therapy. Here, we review the mechanisms and clinical application status of MSCs in the treatment of liver disease and comprehensively summarize the molecular mechanisms of MSC homing, and various strategies for promoting MSC homing to improve the treatment of liver disease.

The increasing role of pigment epithelium-derived factor in metastasis: from biological importance to a promising target

Pigment epithelium-derived factor (PEDF) is a non-inhibitory member of the serpin (serine protease inhibitor) family and is a well-known potent anti-tumor factor in a variety of cancers. It has been ascertained that PEDF regulates multiple metastatic processes through various plausible mechanisms, including inhibiting angiogenesis, inducing apoptosis, stimulating extracellular matrix (ECM) degradation, and suppressing the epithelial-to-mesenchymal transition (EMT) process. Although PEDF has been recognized as an anti-metastatic marker in most studies, its role remains controversial with conflicting reports of PEDF as a metastatic marker. The emerging insights into the mechanism(s) of PEDF in tumor progression and its therapeutic effects are discussed systematically in this review, aiming to improve our understanding in the context of metastasis and drug development.

Detection of Circulating Serum Protein Biomarkers of Non-Muscle Invasive Bladder Cancer after Protein Corona-Silver Nanoparticles Analysis by SWATH-MS

Because cystoscopy is expensive and invasive, a new method of detecting non-invasive muscular bladder cancer (NMIBC) is needed. This study aims to identify potential serum protein markers for NMIBC to improve diagnosis and to find treatment approaches that avoid disease progression to a life-threatening phenotype (muscle-invasive bladder cancer, MIBC). Here, silver nanoparticles (AgNPs, 9.73 ± 1.70 nm) as a scavenging device together with sequential window acquisition of all theoretical mass spectra (SWATH-MS) were used to quantitatively analyze the blood serum protein alterations in two NMIBC subtypes, T1 and Ta, and they were compared to normal samples (HC). NMIBC’s analysis of serum samples identified three major groups of proteins, the relative content of which is different from the HC content: proteins implicated in the complement and coagulation cascade pathways and apolipoproteins. In conclusion, many biomarker proteins were identified that merit further examination to validate their useful significance and utility within the clinical management of NMIBC patients.

Comparing the Therapeutic Potential of Stem Cells and their Secretory Products in Regenerative Medicine

Cell therapy involves the transplantation of human cells to replace or repair the damaged tissues and modulate the mechanisms underlying disease initiation and progression in the body. Nowadays, many different types of cell-based therapy are developed and used to treat a variety of diseases. In the past decade, cell-free therapy has emerged as a novel approach in regenerative medicine after the discovery that the transplanted cells exerted their therapeutic effect mainly through the secretion of paracrine factors. More and more evidence showed that stem cell-derived secretome, i.e., growth factors, cytokines, and extracellular vesicles, can repair the injured tissues as effectively as the cells. This finding has spurred a new idea to employ secretome in regenerative medicine. Despite that, will cell-free therapy slowly replace cell therapy in the future? Or are these two modes of treatment still needed to address different diseases and conditions? This review provides an indepth discussion about the values of stem cells and secretome in regenerative medicine. In addition, the safety, efficacy, advantages, and disadvantages of using these two modes of treatment in regenerative medicine are also critically reviewed.

Genetically-Modified Stem Cell in Regenerative Medicine and Cancer Therapy; A New Era

Recently, genetic engineering by various strategies to stimulate gene expression in a specific and controllable mode is a speedily growing therapeutic approach. Genetic modification of human stem or progenitor cells, such as embryonic stem cells (ESCs), neural progenitor cells (NPCs), mesenchymal stem/stromal cells (MSCs), and hematopoietic stem cells (HSCs) for direct delivery of specific therapeutic molecules or genes has been evidenced as an opportune plan in the context of regenerative medicine due to their supported viability, proliferative features, and metabolic qualities. On the other hand, a large number of studies have investigated the efficacy of modified stem cells in cancer therapy using cells from various sources, disparate transfection means for gene delivery, different transfected yields, and wide variability of tumor models. Accordingly, cell-based gene therapy holds substantial aptitude for the treatment of human malignancy as it could relieve signs or even cure cancer succeeding expression of therapeutic or suicide transgene products; however, there exist inconsistent results in this regard. Herein, we deliver a brief overview of stem cell potential to use in cancer therapy and regenerative medicine and importantly discuss stem cells based gene delivery competencies to stimulate tissue repair and replacement in concomitant with their potential to use as an anti-cancer therapeutic strategy, focusing on the last two decades in vivo studies.

IL-6 promotes PD-L1 expression in monocytes and macrophages by decreasing protein tyrosine phosphatase receptor type O expression in human hepatocellular carcinoma

Background

We have previously discovered a relationship between the low expression of protein tyrosine phosphatase, receptor type O (PTPRO) in tumor-infiltrating T cells and immunosuppression. The aim of the present study was to investigate the relationship between decreased PTPRO and increased programmed death ligand 1 (PD-L1) in both the peripheral monocytes and tumor-infiltrating macrophages of human hepatocellular carcinoma (HCC).

Methods

The expression and correlation of all the indices were explored in monocytes and tumor-infiltrating macrophages within both human and mice HCC. The mechanic regulations were studied by using both in vitro and in vivo studies.

Results

We found a significant decrease in PTPRO in HCC peripheral monocytes that was associated with increased PD-L1 expression in peripheral monocytes and tumor-associated macrophages (TAMs) in HCC. Monocyte PD-L1 and PTPRO therefore could serve as valuable prognostic indicators for post-surgery patients with HCC and were associated with increased T-cell exhaustion (Tim3+T cells). A depletion of PTPRO promoted PD-L1 secretion in both monocytes and macrophages through the JAK2/STAT1 and JAK2/STAT3/c-MYC pathways. Increased IL-6 expression was associated with activation of JAK2/STAT3/c-MYC and with decreased PTPRO expression through the STAT3/c-MYC/miR-25–3 p axis. Monocytes and TAMs showed significantly increased miR-25–3 p expression, which could target the 3′ untranslated region of PTPRO. The miR-25–3 p expression positively correlated with serum IL-6 levels, but inversely correlated with PTPRO in HCC monocytes. IL-6/STAT3/c-MYC activation enhanced in vitro miR-25–3 p transcription and decreased PTPRO, while further promoting PD-L1 secretion. Adoptive cell transfer of c-MYC/miR-25–3 p–modified monocytes promoted tumor growth by downregulating PTPRO and causing a PD-L1–induced immunosuppression in an orthotopic tumor transplantation model.

Conclusions

Increased serum IL-6 downregulated PTPRO expression in HCC monocytes and macrophages by activating STAT3/c-MYC/miR-25–3 p and by further enhancing PD-L1 expression through JAK2/STAT1 and JAK2/STAT3/c-MYC signaling.

Bone marrow mesenchymal stem cell-mediated ultrasmall gold nanoclusters and hNIS gene synergize radiotherapy for breast cancer

The human sodium iodide symporter (hNIS) can be linked to the downstream of radiation-sensitive early growth response protein1 (Egr1) promoter, and activated by the Egr1 following ¹³¹I treatment. However, the rapid outflow of ¹³¹I restricted the radiotherapy effect. To overcome this barrier, ultrasmall gold nanoclusters (usAuNCs) were used to enhance the radiotherapy efficacy of Egr1-hNIS for its radiation sensitization. In this work, we prepared "cell bomb" BMSCs carrying both GSH@AuNCs and Egr1-hNIS. We found that the "cell bomb" can target TNBC tumor and reach a maximum ¹³¹I concentration 9 h following ¹³¹I injection. Colony formation assay revealed that ¹³¹I, ¹³¹I combined with GSH@AuNCs could independently inhibit 39.5% and 66.4% of cell growth, respectively. Moreover, in vivo¹³¹I therapy further demonstrated that the growth of triple negative breast cancer (TNBC) was controlled by BMSC-Egr1-hNIS + AuNCs group, with relative volume inhibition percentages of 56.16% (compared with the control group) and 36.20% (compared with the BMSC-Egr1-hNIS group), respectively. To summarize, we successfully prepared BMSC-Egr1-hNIS carrying GSH@AuNCs to target TNBC which could synergistically improve the efficacy of hNIS gene therapy.

Feasibility of Bone Marrow Mesenchymal Stem Cell-Mediated Synthetic Radiosensitive Promoter-Combined Sodium Iodide Symporter for Radiogenetic Ovarian Cancer Therapy

Ovarian cancer is the most lethal gynecological cancer, most patients relapse within 12-24 months, and eventually die, especially platinum-resistant patients. Gene therapy has been one of the most potential methods for tumor treatment. Bone marrow mesenchymal stem cells (BMSCs) have been used for systemic delivery of therapeutic genes to solid tumors. Sodium iodide symporter (NIS) is an intrinsic membrane glycoprotein and can concentrate ¹³¹I, which is important for radionuclide therapy and nuclear medicine imaging in recent years. However, the rapid iodine efflux has become a bottleneck for NIS-mediated radionuclide gene therapy. Our previous studies found that the early growth response-1 (Egr1) promoter containing CC(A/T)6GG (CArG) elements had an ¹³¹I radiation-positive feedback effect on the NIS gene. Other research showed the synthesized Egr1 promoter containing four CArG elements, E4, was nearly three times as sensitive as the Egr1 promoter. In our study, BMSC-E4-NIS was engineered to express NIS under the control of E4 promoter using lentivirial vectors. After BMSC-E4-NIS implantation, no tumors were seen in BALB/c nude mice and BMSC-E4-NIS did not promote the growth of SKOV3 tumor. BMSCs migrated toward ovarian cancer samples in chemotaxis assays and to ovarian tumors in mice. Using micro-single-photon emission computed tomography/computed tomography (SPECT/CT) imaging, we found that E4 promoter produced a notable increase in ¹²⁵I uptake after ¹³¹I irradiation, the radionuclide uptake is almost three and six times more than Egr1 and cytomegalovirus (CMV) promoters. These studies confirmed the feasibility of using BMSCs as carriers for lentivirus-mediated E4-NIS gene therapy for ovarian cancer. Further research on BMSC-E4-NIS gene therapy for ovarian cancer in vivo will also be carried on, and if successful, this might provide a new adjuvant therapeutical option for platinum-resistant ovarian cancer patients and provide a new method for dynamic evaluation of curative effect.

Genetic modification by overexpression of target gene in mesenchymal stromal cell for treating liver diseases

Different hepatoxic factors cause irreversible liver injury, leading to liver failure, cirrhosis, and cancer in mammals. Liver transplantation is the only effective strategy, which can improve the prognosis of patients with end-stage liver diseases, but it is limited by liver donor shortage, expensive costs, liver graft rejection and dysfunction, and recurring liver failure. Recently, mesenchymal stromal cells (MSCs) isolated from various tissues are regarded as the main stem cell type with therapeutic effects in liver diseases because of their hepatogenic differentiation, anti-inflammatory, immuoregulatory, anti-apoptotic, antifibrotic, and antitumor capacities. To further improve the therapeutic effects of MSCs, multiple studies showed that genetically engineered MSCs have increased regenerative capacities and are able to more effectively inhibit cell death. Moreover, they are able to secrete therapeutic proteins for attenuating liver injury in liver diseases. In this review, we mainly focus on gene overexpression for reprogramming MSCs to increase their therapeutic effects in treating various liver diseases. We described the potential mechanisms of MSCs with gene overexpression in attenuating liver injury, and we recommend further expansion of experiments to discover more gene targets and optimized gene delivery methods for MSC-based regenerative medicine. We also discussed the potential hurdles in genetic engineering MSCs. In conclusion, we highlight that we need to overcome all scientific hurdles before genetically modified MSC therapy can be translated into clinical practices for patients with liver diseases.

Genetic Engineering as a Strategy to Improve the Therapeutic Efficacy of Mesenchymal Stem/Stromal Cells in Regenerative Medicine

Mesenchymal stem/stromal cells (MSCs) have been widely studied in the field of regenerative medicine for applications in the treatment of several disease settings. The therapeutic potential of MSCs has been evaluated in studies in vitro and in vivo, especially based on their anti-inflammatory and pro-regenerative action, through the secretion of soluble mediators. In many cases, however, insufficient engraftment and limited beneficial effects of MSCs indicate the need of approaches to enhance their survival, migration and therapeutic potential. Genetic engineering emerges as a means to induce the expression of different proteins and soluble factors with a wide range of applications, such as growth factors, cytokines, chemokines, transcription factors, enzymes and microRNAs. Distinct strategies have been applied to induce genetic modifications with the goal to enhance the potential of MCSs. This review aims to contribute to the update of the different genetically engineered tools employed for MSCs modification, as well as the factors investigated in different fields in which genetically engineered MSCs have been tested.

Strategies for treating oesophageal diseases with stem cells

There is a wide range of oesophageal diseases, the most general of which are inflammation, injury and tumours, and treatment methods are constantly being developed and updated. With an increasingly comprehensive understanding of stem cells and their characteristics of multilineage differentiation, self-renewal and homing as well as the combination of stem cells with regenerative medicine, tissue engineering and gene therapy, stem cells are playing an important role in the treatment of a variety of diseases. Mesenchymal stem cells have many advantages and are most commonly applied; however, most of these applications have been in experimental studies, with few related clinical trials for comparison. Therefore, the methods, positive significance and limitations of stem cells in the treatment of oesophageal diseases remain incompletely understood. Thus, the purpose of this paper is to review the current literature and summarize the efficacy of stem cells in the treatment of oesophageal diseases, including oesophageal ulceration, acute radiation-induced oesophageal injury, corrosive oesophageal injury, oesophageal stricture formation after endoscopic submucosal dissection and oesophageal reconstruction, as well as gene therapy for oesophageal cancer.

Therapeutic Potential of Pigment Epithelium-derived Factor in Cancer

Pigment epithelium-derived factor (PEDF) is one of the serine protease inhibitors with multifunctional properties, which is produced by various types of organs and tissues. There is an accumulating body of evidence that PEDF plays an important role in the maintenance of tissue homeostasis. Indeed, PEDF not only works as an endogenous inhibitor of angiogenesis, but also suppresses oxidative stress, inflammatory and thrombotic reactions in cell culture systems, animal models, and humans. Furthermore, we, along with others, have found that PEDF inhibits proliferation of, and induces apoptotic cell death in, numerous kinds of tumors. In addition, circulating as well as tumor expression levels of PEDF have been inversely associated with tumor growth and metastasis. These observations suggest that supplementation of PEDF proteins and/or enhancement of endogenous PEDF expression could be a novel therapeutic strategy for the treatment of cancer. Therefore, in this paper, we review the effects of PEDF on diverse types of cancer, and discuss its therapeutic perspectives.

Stem Cell Therapy for Hepatocellular Carcinoma: Future Perspectives

Hepatocellular carcinoma (HCC) is one of the most common types of cancer and results in a high mortality rate worldwide. Unfortunately, most cases of HCC are diagnosed in an advanced stage, resulting in a poor prognosis and ineffective treatment. HCC is often resistant to both radiotherapy and chemotherapy, resulting in a high recurrence rate. Although the use of stem cells is evolving into a potentially effective approach for the treatment of cancer, few studies on stem cell therapy in HCC have been published. The administration of stem cells from bone marrow, adipose tissue, the amnion, and the umbilical cord to experimental animal models of HCC has not yielded consistent responses. However, it is possible to induce the apoptosis of cancer cells, repress angiogenesis, and cause tumor regression by administration of genetically modified stem cells. New alternative approaches to cancer therapy, such as the use of stem cell derivatives, exosomes or stem cell extracts, have been proposed. In this review, we highlight these experimental approaches for the use of stem cells as a vehicle for local drug delivery.

Effects of Extracellular Vesicles Derived from Mesenchymal Stem/Stromal Cells on Liver Diseases

Therapeutic effects of Mesenchymal Stem/Stromal Cells (MSCs) transplantation have been observed in various disease models. However, it is thought that MSCs-mediated effects largely depend on the paracrine manner of secreting cytokines, growth factors, and Extracellular Vesicles (EVs). Similarly, MSCs-derived EVs also showed therapeutic benefits in various liver diseases through alleviating fibrosis, improving regeneration of hepatocytes, and regulating immune activity. This review provides an overview of the MSCs, their EVs, and their therapeutic potential in treating various liver diseases including liver fibrosis, acute and chronic liver injury, and Hepatocellular Carcinoma (HCC). More specifically, the mechanisms by which MSC-EVs induce therapeutic benefits in liver diseases will be covered. In addition, comparisons between MSCs and their EVs were also evaluated as regenerative medicine against liver diseases. While the mechanisms of action and clinical efficacy must continue to be evaluated and verified, MSCs-derived EVs currently show tremendous potential and promise as a regenerative medicine treatment for liver disease in the future.

Malignant ascites: a source of therapeutic protein against ovarian cancer?

Ovarian cancer is the fifth leading cause of cancer-related death in the world. Some ovarian cancer patients present large amount of ascites at the time of diagnosis which may play an active role in tumor development. In earlier studies, we demonstrated that the acellular fraction of ascites can induce apoptosis of ovarian cancer cells. The current study identifies pigment epithelium derived factor (PEDF) as the molecule responsible for the apoptotic effect of ascites and evaluates the Sleeping Beauty transposon (SBT) system as a new tool for PEDF gene therapy against ovarian cancer. We utilize gel filtration, mass spectrometry, affinity column, cell viability assay, tumor development on chick chorioallantoic membrane and molecular biology techniques for these purposes. PEDF was thus identified as the agent responsible for the effects of ascites on ovarian cancer cell viability and tumor growth. Interestingly, the PEDF expression is decreased in ovarian cancer cells compared to healthy ovarian cells. However, the level of PEDF is higher in ascites than in serum of ovarian cancer patients suggesting that cells present in the tumor environment are able to secrete PEDF. We then used the SBT system to stably induce PEDF expression in ovarian cancer cells. The overexpression of PEDF significantly reduced the tumor growth derived from these cells. In conclusion, the results presented here establish that PEDF is a therapeutic target and that PEDF from ascites or SBT could be utilized as a therapeutic strategy for the treatment of ovarian cancer.

The contrary intracellular and extracellular functions of PEDF in HCC development

Pigment epithelium-derived factor (PEDF), a classic angiogenic inhibitor, has been reported to function as a tumor suppression protein and to downregulate in many types of solid tumors. However, the expression level of PEDF and its role in hepatocellular carcinoma (HCC) are contradictory. The present study investigates the expression and different activities of secreted and intracellular PEDF during HCC development, as well as the underlying mechanism of PEDF on HCC lipid disorders. We found that PEDF had no association with patients' prognosis, although PEDF was highly expressed and inhibited angiogenesis in HCC tumor tissues. The animal experiments indicated that full-length PEDF exhibited equalizing effects on tumor growth activation and tumor angiogenesis inhibition in the late stage of HCC progression. Importantly, the pro-tumor activity was mediated by the intracellular PEDF, which causes accumulation of free fatty acids (FFAs) in vivo and in vitro. Based on the correlation analysis of PEDF and lipid metabolic indexes in human HCC tissues, we demonstrated that the intracellular PEDF led to the accumulation of FFA and eventually promoted HCC cell growth by inhibiting the activation of AMPK via ubiquitin-proteasome-mediated degradation, which causes increased de novo fatty acid synthesis and decreased FFA oxidation. Our findings revealed why elevated PEDF did not improve the patients' prognosis as the offsetting intracellular and extracellular activities. This study will lead to a comprehensive understanding of the diverse role of PEDF in HCC and provide a new selective strategy by supplement of extracellular PEDF and downregulation of intracellular PEDF for the prevention and treatment of liver cancer.

Pigment epithelium-derived factor in lipid metabolic disorders

Pigment epithelium-derived factor (PEDF) is a secreted glycoprotein that has anti-angiogenic, anti-proliferative, neurotrophic and immunomodulatory properties. PEDF has recently emerged as a critical metabolic regulatory protein since the discovery of its modulatory activities in the lipolytic pathway by binding to adipose triglyceride lipase (ATGL). Despite being beneficial in maintaining the homeostasis of hepatic lipid accumulation, PEDF has been uncovered an unfavorable role associated with insulin resistance. The molecular events that connect these two apparent distinct observations have been controversial and remained largely unknown. Therefore in this short review, we attempt to summarize the current findings of PEDF regarding its lipid metabolic functions and provide perspectives in identifying PEDF as a potential therapeutic target in lipid disorders.

Multipotent mesenchymal stromal cells play critical roles in hepatocellular carcinoma initiation, progression and therapy

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, with high morbidity, relapse and mortality rates. Multipotent mesenchymal stromal cells (MSCs) can be recruited to and become integral components of the HCC microenvironment and can influence tumor progression. This review discusses MSC migration to liver fibrosis and the HCC microenvironment, MSC involvement in HCC initiation and progression and the widespread application of MSCs in HCC-targeted therapy, thus clarifying the critical roles of MSCs in HCC.

Pigment epithelium-derived factor: a key mediator in bone homeostasis and potential for bone regenerative therapy

Objectives

Pigment epithelium-derived factor (PEDF), a multifunctional endogenous glycoprotein, has a very wide range of biological actions, notably in bone homeostasis. The question has been raised regarding the place of PEDF in the treatment of bone disorders and osteosarcoma, and its potential for tumour growth suppression.

Methods

The PubMed database was used to compile this review.

Key findings

Pigment epithelium-derived factor's actions in osteoid tissues include promoting mesenchymal stem cell commitment to osteoblasts, increasing matrix mineralisation, and promoting osteoblast proliferation. It shows potential to improve therapeutic outcomes in treatment of multiple cancer types and regrowth of bone after trauma or resection in animal studies. PEDF may possibly have a reduced adverse effect profile compared with current osteo-regenerative treatments; however, there is currently very limited evidence regarding the safety or efficacy in human models.

Summary

Pigment epithelium-derived factor is very active within the body, particularly in osseous tissue, and its physiological actions give it potential for treatment of both bone disorders and multiple tumour types. Further research is needed to ascertain the adverse effects and safety profile of PEDF as a therapeutic agent.

Whey Acidic Protein/Four-Disulfide Core Domain 21 Regulate Sepsis Pathogenesis in a Mouse Model and a Macrophage Cell Line via the Stat3/Toll-Like Receptor 4 (TLR4) Signaling Pathway

Background

Whey acidic protein/four-disulfide core domain 21 (Wfdc21), also known as Lnc-DC, it has been reported to be correlated with immune response. However, the role of Wfdc21 in the pathogenesis of sepsis is still unknown. In the present study, we aimed to investigate the role of Wfdc21 in the pathogenesis of sepsis.

Material/Methods

The cecal ligation and puncture (CLP)-induced sepsis model was established in Balb/c mice. Animals were euthanized 4, 8, 16, or 24 h after CLP. The glycogen distribution in the kidney and liver was checked by Periodic acid-Schiff (PAS) staining. Changes in the serum interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations were monitored with ELISA, and Wdfc21 expression was determined by qPCR. Mouse macrophage-like RAW264.7 cells were treated with different doses of lipopolysaccharide (LPS) from Escherichia coli to mimic sepsis in vitro. Western blot analysis was performed to confirm whether LPS-induced in vitro sepsis was correlated with the involvement of the Stat3/TLR4 signaling pathway. In addition, RAW 264.7 cells were infected with lentiviruses containing Wfdc21 shRNA to further confirm the role of Wfdc21 in the pathogenesis of sepsis.

Results

We found that Wfdc21 level was elevated in the CLP-induced animal model and LPS-treated RAW264.7 cells. Furthermore, the downregulation of Wfdc21 modulated the concentration of pro-inflammatory factors in LPS-treated macrophages, such as IL-1β and TNF-α, in LPS-treated macrophages. This regulatory effect was mediated through the Stat3/TLR4 signaling pathway, since Wfdc21 can regulate p-Stat3 and TLR4 levels in LPS-treated macrophages.

Conclusions

Wfdc21 plays a critical role in the pathogenesis of sepsis and may provide a therapeutic target for sepsis treatment.

Matrix metalloproteinase-1 facilitates MSC migration via cleavage of IGF-2/IGFBP2 complex

The specific mechanism underlying the tumor tropism of human mesenchymal stem cells (MSCs) for cancer is not well defined. We previously showed that the migration potential of MSCs correlated with the expression and protease activity of matrix metalloproteinase (MMP)‐1. Furthermore, highly tumor‐tropic MSCs expressed higher levels of MMP‐1 and insulin‐like growth factor (IGF)‐2 than poorly migrating MSCs. In this study, we examined the functional roles of IGF‐2 and MMP‐1 in mediating the tumor tropism of MSCs. Exogenous addition of either recombinant IGF‐2 or MMP‐1 could stimulate MSC migration. The correlation between IGF‐2, MMP‐1 expression, and MSC migration suggests that MMP‐1 may play a role in regulating MSC migration via the IGF‐2 signaling cascade. High concentrations of IGF binding proteins (IGFBPs) can inhibit IGF‐stimulated functions by blocking its binding to its receptors and proteolysis of IGFBP is an important mechanism for the regulation of IGF signaling. We thus hypothesized that MMP‐1 acts as an IGFBP2 proteinase, resulting in the cleavage of IGF‐2/IGFBP2 complex and extracellular release of free IGF‐2. Indeed, our results showed that conditioned media from highly migrating MSCs, which expressed high levels of MMP‐1, cleaved the IGF‐2/IGFBP2 complex. Taken together, these results showed that the MMP‐1 secreted by highly tumor‐tropic MSCs cleaved IGF‐2/IGFBP2 complex. Free IGF‐2 released from the complex may facilitate MSC migration toward tumor.

IL-8, GRO and MCP-1 produced by hepatocellular carcinoma microenvironment determine the migratory capacity of human bone marrow-derived mesenchymal stromal cells without affecting tumor aggressiveness

New therapies are needed for advanced hepatocellular carcinoma (HCC) and the use of mesenchymal stromal cells (MSCs) carrying therapeutic genes is a promising strategy. HCC produce cytokines recruiting MSCs to the tumor milieu and modifying its biological properties. Our aim was to study changes generated on human MSCs exposed to conditioned media (CM) derived from human HCC fresh samples and xenografts. All CM shared similar cytokines expression pattern including CXCL1-2-3/GRO, CCL2/MCP-1 and CXCL8/IL-8 being the latter with the highest concentration. Neutralizing and knockdown experiments of CCL2/MCP-1, CXCL8/IL-8, CXCR1 and CXCR2 reduced in vitro MSC migration of ≥20%. Simultaneous CXCR1 and CXCR2 neutralization resulted in 50% of MSC migration inhibition. MSC stimulated with CM (sMSC) from HuH7 or HC-PT-5 showed a 2-fold increase of migration towards the CM compared with unstimulated MSC (usMSC). Gene expression profile of sMSC showed ~500 genes differentially expressed compared with usMSC, being 46 genes related with cell migration and invasion. sMSC increased fibroblasts and endothelial cells chemotaxis. Finally, sMSC with HuH7 CM and then inoculated in HCC tumor bearing-mice did not modify tumor growth. In this work we characterized factors produced by HCC responsible for the changes in MSC chemotactic capacity with would have an impact on therapeutic use of MSCs for human HCC.

Anti‑angiogenesis gene therapy for hepatocellular carcinoma via systemic injection of mesenchymal stem cells engineered to secrete soluble Flt‑1

Anti‑angiogenesis gene therapy has attracted interest as a potential treatment for hepatocellular carcinoma (HCC). Studies have indicated that soluble fms‑like tyrosine kinase‑1 (sFlt‑1) may suppress angiogenesis by sequestering free vascular endothelial growth factor (VEGF) or by forming inactive heterodimers with VEGF receptor‑2. Mesenchymal stem cells (MSCs) have been widely used as prospective delivery vehicles for therapeutic agents, owing to their ability to migrate towards tumor sites. In the present study, a subcutaneous HCC mouse model was used to assess the anti‑angiogenesis effects of lentivirus‑transfected MSCs engineered to secrete sFlt‑1 (LV‑sFlt‑1‑MSCs). LV‑sFlt‑1‑MSCs effectively secreted sFlt‑1, which inhibited tube formation in vitro. MSCs labeled with green fluorescence protein primarily migrated to tumor sites in vivo. An immunohistochemical assay indicated that microvessel density was reduced in mice treated with LV‑sFlt‑1‑MSCs, compared with the control group treated with PBS. Additionally, LV‑sFlt‑1‑MSCs inhibited tumor growth and prolonged survival in an HCC mouse model via systemic injection. Overall, the present study was designed to investigate the potential of LV‑sFlt‑1‑MSCs for anti‑angiogenesis gene therapy in HCC.

The long noncoding RNA lnc-EGFR stimulates T-regulatory cells differentiation thus promoting hepatocellular carcinoma immune evasion

Long noncoding RNAs play a pivotal role in T-helper cell development but little is known about their roles in Treg differentiation and functions during the progression of hepatocellular carcinoma (HCC). Here, we show that lnc-epidermal growth factor receptor (EGFR) upregulation in Tregs correlates positively with the tumour size and expression of EGFR/Foxp3, but negatively with IFN-γ expression in patients and xenografted mouse models. Lnc-EGFR stimulates Treg differentiation, suppresses CTL activity and promotes HCC growth in an EGFR-dependent manner. Mechanistically, lnc-EGFR specifically binds to EGFR and blocks its interaction with and ubiquitination by c-CBL, stabilizing it and augmenting activation of itself and its downstream AP-1/NF-AT1 axis, which in turn elicits EGFR expression. Lnc-EGFR links an immunosuppressive state to cancer by promoting Treg cell differentiation, thus offering a potential therapeutic target for HCC.

The role of long noncoding RNAs in regulating T-cell differentiation within the tumour microenvironment is unclear. Here the authors identify a lncRNA that, through direct interactions with EGFR, promotes T-regulatory cell differentiation within the microenvironment of hepatocellular carcinoma, thus promoting tumour growth via immune suppression.

Human mesenchymal stem cells preferentially migrate toward highly oncogenic human hepatocellular carcinoma cells with activated EpCAM signaling

The epithelial cell adhesion molecule (EpCAM) is a type I transmembrane glycoprotein that is regarded as one of the markers for tumor initiating cells (TIC) in human hepatocellular carcinoma (HCC). Much work has been directed towards targeting these TICs as a mean of placing these master regulators of cell proliferation and drug resistance under control. Human bone marrow-derived mesenchymal stem cells are known to exhibit an innate property of tumor tropism. However, the possible relationship between MSC and TIC is not well understood. In this study, we show that MSC migration to HCC can be effectively inhibited by TACE and γ-secretase inhibitors that stop the activation of EpCAM signaling event. Silencing of EpCAM expression through siRNA and antibody approaches also resulted in impaired MSC migration. By contrast, increase levels of EpICD proteins in HCC cells and HCC mouse xenografts resulted in enhanced MSC migration. Taken together, these findings show that MSC is drawn to the more oncogenic population of HCC, and could potentially serve as a cell-based carrier of therapeutic genes to target EpICD-enriched hepatic tumor cells.

Co-culture of hepatoma cells with hepatocytic precursor (stem-like) cells inhibits tumor cell growth and invasion by downregulating Akt/NF-κB expression

Hepatocytic stem cells (HSCs) have inhibitory effects on hepatocarcinoma cells. The present study investigated the effects of HSC activity in hepatocarcinoma cells in vitro. A Transwell co-culture system of hepatocytic precursor (stem-like) WB-F344 cells and hepatoma CBRH-7919 cells was used to assess HSC activity in metastasized hepatoma cells in vitro. Nude mouse xenografts were used to assess HSC activity in vivo. Co-culture of hepatoma CBRH-7919 cells with WB-F344 cells suppressed the growth and colony formation, tumor cell migration and invasion capacity of CBRH-7919 cells. The nude mouse xenograft assay demonstrated that the xenograft size of CBRH-7919 cells following co-culture with WB-F344 cells was significantly smaller compared with that of control cells. Furthermore, the expression levels of the epithelial markers E-cadherin and β-catenin were downregulated, while the mesenchymal markers α-SMA and vimentin were upregulated. Co-culture of CBRH-7919 cells with WB-F344 cells downregulated NF-κB and phospho-Akt expression. In conclusion, hepatocytic precursor (stem-like) WB-F344 cells inhibited the growth, colony formation and invasion capacity of metastasized hepatoma CBRH-7919 cells in vitro and in vivo by downregulating Akt/NF-κB signaling.

Engineered Mesenchymal Stem Cells as an Anti-Cancer Trojan Horse

Cell-based gene therapy holds a great promise for the treatment of human malignancy. Among different cells, mesenchymal stem cells (MSCs) are emerging as valuable anti-cancer agents that have the potential to be used to treat a number of different cancer types. They have inherent migratory properties, which allow them to serve as vehicles for delivering effective therapy to isolated tumors and metastases. MSCs have been engineered to express anti-proliferative, pro-apoptotic, and anti-angiogenic agents that specifically target different cancers. Another field of interest is to modify MSCs with the cytokines that activate pro-tumorigenic immunity or to use them as carriers for the traditional chemical compounds that possess the properties of anti-cancer drugs. Although there is still controversy about the exact function of MSCs in the tumor settings, the encouraging results from the preclinical studies of MSC-based gene therapy for a large number of tumors support the initiation of clinical trials.

Promising Nanocarriers for PEDF Gene Targeting Delivery to Cervical Cancer Cells Mediated by the Over-expressing FRα

Cervical cancer presents extremely low PEDF expression which is associated with tumor progression and poor prognosis. In this study, folate receptor α (FRα)-targeted nano-liposomes (FLP) were designed to enhance the anti-tumor effect by targeting delivery of exogenous PEDF gene to cervical cancer cells. The targeting molecule F-PEG-Chol was firstly synthesized by a novel simpler method. FLP encapsulating PEDF gene (FLP/PEDF) with a typical lipid-membrane structure were prepared by a film dispersion method. The transfection experiment found FLP could effectively transfect human cervical cancer cells (HeLa cells). FLP/PEDF significantly inhibited the growth of HeLa cells and human umbilical vein endothelial cells (HUVEC cells) and suppressed adhension, invasion and migration of HeLa cells in vitro. In the abdominal metastatic tumor model of cervical cancer, FLP/PEDF administered by intraperitoneal injection exhibited a superior anti-tumor effect probably due to the up-regulated PEDF. FLP/PEDF could not only sharply reduce the microvessel density but also dramatically inhibit proliferation and markedly induce apoptosis of tumor cells in vivo. Moreover, the preliminary safety investigation revealed that FLP/PEDF had no obvious toxicity. These results clearly showed that FLP were desired carriers for PEDF gene and FLP/PEDF might represent a potential novel strategy for gene therapy of cervical cancer.

Umbilical cord-derived mesenchymal stem cells inhibit growth and promote apoptosis of HepG2 cells

Hepatocellular carcinoma is the fifth most common type of cancer worldwide and remains difficult to treat. The aim of this study was to investigate the effects of mesenchymal stem cells (MSCs) derived from the umbilical cord (UC‑MSCs) on HepG2 hepatocellular carcinoma cells. UC‑MSCs were co‑cultured with HepG2 cells and biomarkers of UC‑MSCs were analyzed by flow cytometry. mRNA and protein expression of genes were determined by reverse transcription‑polymerase chain reaction and flow cytometry, respectively. Passage three and seven UC‑MSCs expressed CD29, CD44, CD90 and CD105, whereas CD34 and CD45 were absent on these cells. Co‑culture with UC‑MSCs inhibited proliferation and promoted apoptosis of HepG2 cells in a time‑dependent manner. The initial seeding density of UC‑MSCs also influenced the proliferation and apoptosis of HepG2 cells, with an increased number of UC‑MSCs causing enhanced proliferation inhibition and cell apoptosis. Co‑culture with UC‑MSCs downregulated mRNA and protein expression of α‑fetoprotein (AFP), Bcl‑2 and Survivin in HepG2 cells. Thus, UC‑MSCs may inhibit growth and promote apoptosis of HepG2 cells through downregulation of AFP, Bcl‑2 and Survivin. US-MSCs may be used as a novel therapy for treating hepatocellular carcinoma in the future.

Identification of Predictive Gene Markers for Multipotent Stromal Cell Proliferation

Multipotent stromal cells (MSCs) are known for their distinctive ability to differentiate into different cell lineages, such as adipocytes, chondrocytes, and osteocytes. They can be isolated from numerous tissue sources, including bone marrow, adipose tissue, skeletal muscle, and others. Because of their differentiation potential and secretion of growth factors, MSCs are believed to have an inherent quality of regeneration and immune suppression. Cellular expansion is necessary to obtain sufficient numbers for use; however, MSCs exhibit a reduced capacity for proliferation and differentiation after several rounds of passaging. In this study, gene markers of MSC proliferation were identified and evaluated for their ability to predict proliferative quality. Microarray data of human bone marrow-derived MSCs were correlated with two proliferation assays. A collection of 24 genes were observed to significantly correlate with both proliferation assays (|r| >0.70) for eight MSC lines at multiple passages. These 24 identified genes were then confirmed using an additional set of MSCs from eight new donors using reverse transcription quantitative polymerase chain reaction (RT-qPCR). The proliferative potential of the second set of MSCs was measured for each donor/passage for confluency fraction, fraction of EdU+ cells, and population doubling time. The second set of MSCs exhibited a greater proliferative potential at passage 4 in comparison to passage 8, which was distinguishable by 15 genes; however, only seven of the genes (BIRC5, CCNA2, CDC20, CDK1, PBK, PLK1, and SPC25) demonstrated significant correlation with MSC proliferation regardless of passage. Our analyses revealed that correlation between gene expression and proliferation was consistently reduced with the inclusion of non-MSC cell lines; therefore, this set of seven genes may be more strongly associated with MSC proliferative quality. Our results pave the way to determine the quality of an MSC population for a particular cellular therapy in lieu of an extended in vitro or in vivo assay.

Chemokine CCL15 Mediates Migration of Human Bone Marrow-Derived Mesenchymal Stem Cells Toward Hepatocellular Carcinoma

Mesenchymal stem cells (MSCs) possess the ability to migrate toward tumor sites and are regarded as promising gene delivery vehicles for cancer therapeutics. However, the factors that mediate this tropism have yet to be completely elucidated. In this study, through cytokine array analysis, chemokine CCL15 was found to be the most abundant protein differentially expressed in hepatocellular carcinoma (HCC) cell lines compared with a normal liver cell line. Serum CCL15 levels in HCC patients determined by enzyme linked immunosorbent assay were shown to be profoundly elevated compared with healthy controls. Immunohistochemical analysis indicated that CCL15 expression was much stronger in HCC tumor tissues than in adjacent nontumor tissues. Transwell migration assay suggested that CCL15 may be involved in chemotaxis of human MSCs (hMSCs) toward HCC in vitro and that this chemotactic effect of CCL15 is mediated via CCR1 receptors on hMSCs. Orthotopic animal models of HCC were established to investigate the role of CCL15 in hMSCs migration toward HCC in vivo. Both histological and flow cytometric analysis showed that significantly fewer hMSCs localized within 97H-CCL15-shRNA xenografts compared with 97H-green fluorescent protein xenografts after intravenous delivery. Finally, the possible effects of hMSCs on HCC tumor growth were also evaluated. Coculture experiments showed that hMSCs had no apparent effect on the proliferation of HCC cells in vitro In addition, systemic administration of hMSCs did not affect HCC tumor progression in vivo. Our data in this study help to elucidate the mechanism underlying the homing capacity of hMSCs toward HCC.

Effect of targeted ovarian cancer therapy using amniotic fluid mesenchymal stem cells transfected with enhanced green fluorescent protein-human interleukin-2 in vivo

The aim of the present study was to investigate the effect of using amniotic fluid mesenchymal stem cells (AF-MSCs) in targeted ovarian cancer therapy in vivo. AF-MSCs were isolated from human second trimester AF and a plasmid, enhanced green fluorescent protein-human interleukin-2 (pEGFP-hIL-2) was formed. The plasmid was stably transfected into the AF-MSCs and the cells were intravenously injected into ovarian cancer nude mice models. Following stable transfection of the vector, tumor formation, and the expression and activity of hIL-2 were investigated, and microscopic pathological examinations of the tumor were performed. It was found that AF-MSCs exhibited high motility during migration in vivo, and the vector, pEGFP-hIL-2 can be stably transfected into AF-MSCs. Following stable transfection, this type of stem cell is able to successfully transport the therapeutic gene, IL-2, migrate to the ovarian cancer tumor site to secrete the functional IL-2 and treat the tumor. Thus, AF-MSCs may serve as transporters for therapeutic genes targeting ovarian tumor sites and, therefore, be involved in the treatment of tumors.

Irradiation-induced localization of IL-12-expressing mesenchymal stem cells to enhance the curative effect in murine metastatic hepatoma

Irradiation in conjunction with gene therapy is considered for efficient cancer treatment. Mesenchymal stem cells (MSCs), due to their irradiation-promotable tumor tropism, are ideal delivery vehicles for gene therapy. In this study, we investigated whether treatment with radiation and interleukin (IL)-12-expressing MSCs (MSCs/IL-12) exerts improved antitumor effects on murine metastatic hepatoma. HCa-I and Hepa 1-6 cells were utilized to generate heterotopic murine hepatoma models. Tumor-bearing mice were treated with irradiation or MSCs/IL-12 alone, or a combination. Monocyte chemoattractant protein-1 (MCP-1/CCL2) expression was assessed in irradiated hepatoma tissues to confirm a chemotactic effect. Combination treatment strategies were established and their therapeutic efficacies were evaluated by monitoring tumor growth, metastasis and survival rate. IL-12 expression was assessed and the apoptotic activity and immunological alterations in the tumor microenvironment were examined. MCP-1/CCL2 expression and localization of MSCs/IL-12 increased in the irradiated murine hepatoma cells. The antitumor effects, including suppression of pulmonary metastasis and survival rate improvements, were increased by the combination treatment with irradiation and MSCs/IL-12. IL-12 expression was increased in tumor cells, causing proliferation of cluster of differentiation 8(+) T-lymphocytes and natural killer cells. The apoptotic activity increased, indicating that the cytotoxicity of immune cells was involved in the antitumor effect of the combined treatment. Treatment with irradiation and MSCs/IL-12 showed effectiveness in treating murine metastatic hepatoma. IL-12-induced proliferation of immune cells played an important role in apoptosis of tumor cells. Our results suggest that treatment with irradiation and MSCs/IL-12 may be a useful strategy for enhancing antitumor activity in metastatic hepatoma.

Paracrine factors of human fetal MSCs inhibit liver cancer growth through reduced activation of IGF-1R/PI3K/Akt signaling

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death in the world. The multikinase inhibitor sorafenib only demonstrated marginal improvement in overall survival for advanced disease prompted the search for alternative treatment options. Human mesenchymal stem cells (MSCs) have the ability to home to tumor cells. However, its functional roles on the tumor microenvironment remain controversial. Herein, we showed that conditioned media derived from human fetal MSC (CM-hfMSCs) expressed high level of the insulin growth factor binding proteins IGFBPs and can sequester free insulin-like growth factors (IGFs) to inhibit HCC cell proliferation. The inhibitory effect of IGFBPs on IGF signaling was further evident from the reduction of activated IGF-1R and PI3K/Akt, leading eventually to the induction of cell cycle arrest. We also demonstrated that CM-hfMSCs could enhance the therapeutic efficacy of sorafenib and sunitinib. To the best of our knowledge, this is the first report to show that CM-hfMSCs has a tumor-specific, antiproliferative effect that is not observed with normal human hepatocyte cells and patient-derived matched normal tissues. Our results thus suggest that CM-hfMSCs can provide a useful tool to design alternative/adjuvant treatment strategies for HCC, especially in related function to potentiate the effects of chemotherapeutic drugs.

Pyruvate kinase M2 affects liver cancer cell behavior through up-regulation of HIF-1α and Bcl-xL in culture

Cancer cells consume large amounts of glucose to produce lactate, even in the presence of ample oxygen. This phenomenon is known as the Warburg effect. The pyruvate kinase promotes aerobic glycolysis, and the pyruvate kinase M2 isoform (PKM2) is highly expressed in many cancer cells. Although the Warburg effect is a hallmark of cancer, the mechanism by which PKM2 contributes to the Warburg effect, and its role in tumor growth remain to be defined. We proposed that PKM2 activates transcription of hypoxia inducible factor-1α (HIF-1α) by phosphorylating STAT3 (signal transducer and activator of transcription 3) at Y705 (tyrosine 705) as a plausible mechanism for liver cancer cell proliferation. In the current study, we observed that PKM2 was over-expressed in hepatocellular carcinoma (HCC) tissues compared to adjacent normal tissues. The experiments further indicate that nuclear PKM2 is an active protein kinase in cultured cells. Knockdown of PKM2 affected the levels of HIF-1α and Bcl-xL (B-cell lymphoma-extra large), suggesting that PKM2 plays an important role in promoting cell proliferation. In conclusion, the current findings demonstrate that PKM2 is an active protein kinase, and promotes liver cancer cell proliferation by up-regulating HIF-1α and Bcl-xL expression.

Transplantation of ATP7B-transduced bone marrow mesenchymal stem cells decreases copper overload in rats

BACKGROUND

Recent studies have demonstrated that transplantation of ATP7B-transduced hepatocytes ameliorates disease progression in LEC (Long-Evans Cinnamon) rats, a model of Wilson's disease (WD). However, the inability of transplanted cells to proliferate in a normal liver hampers long-term treatment. In the current study, we investigated whether transplantation of ATP7B-transduced bone marrow mesenchymal stem cells (BM-MSCs) could decrease copper overload in LEC rats.

MATERIALS AND METHODS

The livers of LEC rats were preconditioned with radiation (RT) and/or ischemia-reperfusion (IRP) before portal vein infusion of ATP7B-transduced MSCs (MSCsATP7B). The volumes of MSCsATP7B or saline injected as controls were identical. The expression of ATP7B was analyzed by real-time quantitative polymerase chain reaction (RT-PCR) at 4, 12 and 24 weeks post-transplantation. MSCATP7B repopulation, liver copper concentrations, serum ceruloplasmin levels, and alanine transaminase (ALT) and aspartate transaminase (AST) levels were also analyzed at each time-point post-transplantation.

RESULTS

IRP-plus-RT preconditioning was the most effective strategy for enhancing the engraftment and repopulation of transplanted MSCsATP7B. This strategy resulted in higher ATP7B expression and serum ceruloplasmin, and lower copper concentration in this doubly preconditioned group compared with the saline control group, the IRP group, and the RT group at all three time-points post-transplantation (p<0.05 for all). Moreover, 24 weeks post-transplantation, the levels of ALT and AST in the IRP group, the RT group, and the IRP-plus-RT group were all significantly decreased compared to those of the saline group (p<0.05 compared with the IRP group and RT group, p<0.01 compared with IRP-plus-RT group); ALT and AST levels were significantly lower in the IRP-plus-RT group compared to either the IRP group or the RT group (p<0.01 and p<0.05. respectively).

CONCLUSIONS

These results demonstrate that transplantation of MSCsATP7B into IRP-plus-RT preconditioned LEC rats decreased copper overload and was associated with an increase in MSC engraftment and repopulation.

IFN-γ-secreting-mesenchymal stem cells exert an antitumor effect in vivo via the TRAIL pathway

Mesenchymal stem cells (MSCs) can exhibit either prooncogenic or antitumor properties depending on the context. Based on our previous study, we hypothesized that MSCs engineered to deliver IFN-γ would kill cancer cells through persistent activation of the TRAIL pathway. Human bone-marrow (BM-) derived MSCs were isolated, amplified, and transduced with a lentiviral vector encoding the IFN-γ gene under the control of the EF1α promoter. The IFN-γ-modified MSCs effectively secreted functional IFN-γ, which led to long-term expression of TRAIL. More importantly, the IFN-γ-modified MSCs selectively induced apoptosis in lung tumor cells through caspase-3 activation within the target cells. The percentage of activated-caspase-3-positive tumor cells in IFN-γ-modified MSCs cocultures was significantly higher than in control MSCs cocultures. Treatment with anti-TRAIL antibody dramatically suppressed the caspase-3 activation observed in H460 cells. After injection into nude mice, the IFN-γ-modified MSCs inhibited the growth and progression of lung carcinoma compared with control cells. Collectively, our results provide a new strategy for tumor therapy that utilizes IFN-γ-modified MSCs.

Increased migration of human mesenchymal stromal cells by autocrine motility factor (AMF) resulted in enhanced recruitment towards hepatocellular carcinoma

Background and Aims

Several reports described the migration of human mesenchymal stromal cells (MSCs) towards tumor-released factors. Autocrine motility factor (AMF) is produced by several tumors including hepatocellular carcinoma (HCC). The aim of this study was to analyze AMF involvement on MSC migration towards human HCC.

Methods

Production of AMF by HCC tumors was evaluated by western analysis. The effects of AMF on MSCs from different sources (bone marrow, adipose tissue and perivascular cells from umbilical cord) were analyzed using in vitro migration assay; metalloproteinase 2 (MMP2) activity and expression of critical genes were studied by zymography and qRT-PCR, respectively. To assess AMF involvement on the in vivo MSC migration, noninvasive fluorescence imaging was performed. To test the effect of AMF-primed MSCs on tumor development, in vitro proliferation and spheroids growth and in vivo tumor volume were evaluated.

Results

AMF produced by HCC was found to induce migration of different MSCs in vitro and to enhance their MMP2 activity. Stimulation of MSCs with recombinant AMF (rAMF) also induced the in vitro adhesion to endothelial cells in coincidence with changes in the expression levels of MMP3, AMF receptor, caveolin-1, and -2 and GDI-2. Importantly, stimulation of MSCs with rAMF increased the in vivo migration of MSCs towards experimental HCC tumors. AMF-priming of MSCs did not induce a pro-tumorigenic effect on HCC cells neither in vivo nor in vitro.

Conclusion

AMF plays a role in MSC recruitment towards HCC. However, its ability to increase MSC migration to HCC for therapeutic purposes merits further evaluation.

The therapeutic potential of bone marrow-derived mesenchymal stromal cells on hepatocellular carcinoma

Mesenchymal stromal cells (MSCs) are more often obtained from adult and extraembryonic tissues, with the latter sources being likely better from a therapeutic perspective. MSCs show tropism towards inflamed or tumourigenic sites. Mechanisms involved in MSC recruitment into tumours are comprehensively analysed, including chemoattractant signalling axes, endothelial adhesion and transmigration. In addition, signals derived from hepatocellular carcinoma (HCC) tumour microenvironment and their influence in MSC tropism and tumour recruitment are dissected, as well as the present controversy regarding their influence on tumour growth and/or metastasis. Finally, evidences available on the use of MSCs and other selected progenitor/stem cells as vehicles of antitumourigenic genes are discussed. A better knowledge of the mechanisms involved in progenitor/stem cell recruitment to HCC tumours is proposed in order to enhance their tumour targeting which may result in improvements in cell-based gene therapy strategies.