Jianlin Yuan

MicroRNA Let-7a Inhibits Proliferation of Human Prostate Cancer Cells In Vitro and In Vivo by Targeting E2F2 and CCND2

Background Previous work has shown reduced expression levels of let-7 in lung tumors. But little is known about the expression or mechanisms of let-7a in prostate cancer. In this study, we used in vitro and in vivo approaches to investigate whether E2F2 and CCND2 are direct targets of let-7a, and if let-7a acts as a tumor suppressor in prostate cancer by down-regulating E2F2 and CCND2. Methodology/Principal Findings Real-time RT-PCR demonstrated that decreased levels of let-7a are present in resected prostate cancer samples and prostate cancer cell lines. Cellular proliferation was inhibited in PC3 cells and LNCaP cells after transfection with let-7a. Cell cycle analysis showed that let-7a induced cell cycle arrest at the G1/S phase. A dual-luciferase reporter assay demonstrated that the 3′UTR of E2F2 and CCND2 were directly bound to let-7a and western blotting analysis further indicated that let-7a down-regulated the expression of E2F2 and CCND2. Our xenograft models of prostate cancer confirmed the capability of let-7a to inhibit prostate tumor development in vivo. Conclusions/Significance These findings help to unravel the anti-proliferative mechanisms of let-7a in prostate cancer. Let-7a may also be novel therapeutic candidate for prostate cancer given its ability to induce cell-cycle arrest and inhibit cell growth, especially in hormone-refractory prostate cancer.

Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

Near-infrared fluorescence (NIRF) imaging is an attractive modality for early cancer detection with high sensitivity and multi-detection capability. Due to convenient modification by conjugating with moieties of interests, NIRF probes are ideal candidates for cancer targeted imaging. Additionally, the combinatory application of NIRF imaging and other imaging modalities that can delineate anatomical structures extends fluorometric determination of biomedical information. Moreover, nanoparticles loaded with NIRF dyes and anticancer agents contribute to the synergistic management of cancer, which integrates the advantage of imaging and therapeutic functions to achieve the ultimate goal of simultaneous diagnosis and treatment. Appropriate probe design with targeting moieties can retain the original properties of NIRF and pharmacokinetics. In recent years, great efforts have been made to develop new NIRF probes with better photostability and strong fluorescence emission, leading to the discovery of numerous novel NIRF probes with fine photophysical properties. Some of these probes exhibit tumoricidal activities upon light radiation, which holds great promise in photothermal therapy, photodynamic therapy, and photoimmunotherapy. This review aims to provide a timely and concise update on emerging NIRF dyes and multifunctional agents. Their potential uses as agents for cancer specific imaging, lymph node mapping, and therapeutics are included. Recent advances of NIRF dyes in clinical use are also summarized.

Inhibition of CD147 expression reduces tumor cell invasion in human prostate cancer cell line via RNA interference.

CD147, also named extracelluar matrix metalloproteinase inducer (EMMPRIN), has been proved to be involved in the invasion and metastasis processes of tumor cells in many types of cancers. To determine the role of CD147 in the invasiveness properties of prostate cancer, we successfully down-regulated CD147 by RNA interference (RNAi) technology, in PC-3 cell line at high level of CD147 expression. PC-3 cells were transfected with a pSilencer 4.1-CMV neo Vector coding for an RNA composed of two identical 19-nucleotide sequence motifs in an inverted orientation, separated by a 9-bp spacer to form a hairpin dsRNA capable of mediating target CD147 inhibition. Gelatin zymography was employed to determine the effect on reducing secretions of MMP-2 and MMP-9 of the transfected cells. Matrigel invasion assay was performed to evaluate the invasion ability of PC-3 cells in vitro. Our results showed that CD147 expression was significantly inhibited by small interfering RNAs (siRNA) transfectants in PC-3 cells at mRNA and protein levels, which resulted in dramatic reduction of invasion ability in tumor cells. Moreover, downregulation of CD147 resulted in reducing secretions of MMP-2, MMP-9. Taken together, CD147 downregulation by RNAi technology decreases the invasive capability of prostate cancer cells, demonstrating that stable expression of siRNA CD147 could potentially be an experimental approach for prostate cancer gene therapy.

Adaptive Induction of Growth Differentiation Factor 15 Attenuates Endothelial Cell Apoptosis in Response to High Glucose Stimulus

Growth differentiation factor 15 (GDF15), a direct target gene of p53, is a multifunctional member of the TGF-β/BMP superfamily. GDF15 can be induced and is implicated as a key secretory cytokine in response to multiple cellular stimuli. Accumulating evidence indicates that GDF15 is associated with the development and prognosis of diabetes mellitus, while whether GDF15 can be induced by high glucose is unknown. In the present study, we revealed that high glucose could induce GDF15 expression and secretion in cultured human umbilical vein endothelial cells in a ROS- and p53-dependent manner. Inhibition of high glucose-induced GDF15 expression by siRNA demonstrated that adaptively induced GDF15 played a protective role against high glucose-induced human umbilical vein endothelial cell apoptosis via maintaining the active state of PI3K/Akt/eNOS pathway and attenuating NF-κB/JNK pathway activation. The protective effects of GDF15 were probably achieved by inhibiting ROS overproduction in high glucose-treated human umbilical vein endothelial cells in a negative feedback manner. Our results suggest that high glucose can promote GDF15 expression and secretion in human umbilical vein endothelial cells, which in turn attenuates high glucose-induced endothelial cell apoptosis.

Suppression of invasion and metastasis of prostate cancer cells by overexpression of NDRG2 gene

N-myc downstream regulated gene 2 (NDRG2) is involved in invasion and metastasis of cancer, furthermore it is frequently down-regulated in prostate cancer. Herein we evaluated the effect of NDRG2 overexpression on invasiveness and bone destruction in prostate cancer. The human prostate cancer cell line PC-3 and DU145 were infected with Ad-NDRG2 or Ad-LacZ. Overexpression of NDRG2 not only inhibited the growth of the cells, but also suppressed invasiveness of the cells in an in vitro assay. PC-3 cells infected with Ad-NDRG2 or Ad-LacZ were injected into the tibias of nude mice. Four weeks later, we found the mice injected with PC-3 cells overexpressing NDRG2 had smaller tumors and less bone destruction. These results demonstrate that NDRG2 overexpression can inhibit tumor growth and invasion, furthermore, it can decrease bone destruction caused by prostate cancer bone metastasis.

IR-780 Dye for Near-Infrared Fluorescence Imaging in Prostate Cancer

Background The aim of this study was to investigate near-infrared fluorescence (NIRF) imaging as a novel imaging modality that allows for early detection of cancer and real-time monitoring to acquire related information. IR-780 iodide, a lipophilic dye, accumulates selectively in breast cancer cells and drug-resistant human lung cancer cells, with a peak emission at 780 nm that can be easily detected by the NIRF imaging system. The application of IR-780 for prostate cancer imaging was thoroughly investigated to further expand its clinical value. Material/Methods The impact of IR-780 on the survival of prostate cancer cells PC-3 and LNCaP as well as normal prostate epithelial cells RWPE-1 was determined. Duration of IR-780 dye staining was optimized in PC-3 cells. The involvement of specific OATP1B3 inhibitor in the selective accumulation of IR-780 was investigated. IR-780 for prostate cancer imaging was carried out in athymic nude mouse models and, acute toxicity of IR-780 was evaluated. Results IR-780 incubation resulted in a dose-dependent inhibition to cell proliferation. Mean fluorescence intensity of prostate cancer cells peaked at 20-min IR-780 incubation. Specific uptake of IR-780 dye in prostate cancer cells was mainly through the function of OATP1B3. We also demonstrated that NIRF dye effectively identified the subcutaneous prostate cancer xenografts, subsequently confirmed by histological examination. There was no significant impact on the physical activity, weight, and tissue histology of BABL/C mice with 10-fold imaging dose of 1-month IR-780 dye administration. Conclusions NIRF imaging using IR-780 dye is a feasible and practicable method for prostate cancer detection, with potential tumor-killing ability, although more investigations are needed before clinical translation.

Protective effects of mesenchymal stem cells with CXCR4 up-regulation in a rat renal transplantation model.

The homing of mesenchymal stem cells to injured tissue, which is important for the correction of conditions such as ischemia-reperfusion injury (IRI) and immunolesions, has been performed previously, but with poor efficiency. Substantial improvements in engraftment are required to derive clinical benefits from MSC transplantation. Chemokines are the most important factors that control cellular migration. Stromal derived factor-1 (SDF-1) is up-regulated during tissue/organ ischemia damage, and its cognate receptor, chemokine receptor 4 (CXCR4), is involved in stem cell migration. The aim of our study was to investigate CXCR4 expression in MSCs and to validate both its role in mediating migration to transplanted kidneys and its immunoregulatory effects in renal protection. Specifically, the present study was designed to investigate the short-term tissue homing of MSCs carrying genetically modified CXCR4 in a rat renal transplantation model. We tested the hypothesis that MSCs with CXCR4 over-expression can more efficiently regulate immunological reactions. Lentiviral vectors were used to over-express CXCR4 or to introduce a short hairpin ribonucleic acid (shRNA) construct targeting endogenous CXCR4 in rat MSCs. MSCs were labeled with enhanced green fluorescent protein (eGFP). After cell sorting, recipient kidneys were regionally perfused; recipient animals were injected with transduced MSCs, native MSCs, or PBS via tail vein following renal transplantation; and the effects of MSC injection were observed.

α-linolenic acid inhibits human renal cell carcinoma cell proliferation through PPAR-γ activation and COX-2 inhibition

ω-3 fatty acids have potential anticancer effects, and consuming food rich in ω-3 fatty acids reduces the human renal cell carcinoma (RCC) risk. However, the direct effect of ω-3 fatty acids on RCC in vitro is unknown. In the present study, the effects of α-linolenic acid (ALA), an ω-3 fatty acid, were observed on cell proliferation in the RCC cell line OS-RC-2. The activity and gene expression levels of peroxisome proliferator-activated receptor-γ (PPAR-γ) and cyclooxygenase-2 (COX-2) in the OS-RC-2 cells were measured by ELISA and real-time RT-PCR, respectively, following ALA treatment. ALA (20–80 μM) dose-dependently suppressed the proliferation of the OS-RC-2 cells. PPAR-γ activity and gene expression were significantly increased by ALA at 20 and 40 μM. COX-2 activity and gene expression levels were significantly decreased by ALA from 20 μM. Use of purely the PPAR-γ agonist, rosiglitazone, decreased the proliferation of the OS-RC-2 cells, while ALA induced further suppression of cell proliferation in the presence of rosiglitazone. The COX-2 inhibitor N-(3-Pyridyl)indomethacinamide induced further suppression of cell proliferation in the presence of rosiglitazone. N-(3-Pyridyl)indomethacinamide also suppressed the proliferation of the OS-RC-2 cells. In the presence of N-(3-Pyridyl)indomethacinamide, ALA and rosiglitazone further inhibited OS-RC-2 cell proliferation. In conclusion, ALA inhibits the cell proliferation of the OS-RC-2 human RCC cell line. PPAR-γ activation and COX-2 inhibition serve as two signaling pathways for the inhibitory effects of ALA on RCC cell proliferation.

Inhibition of N-myc downstream-regulated gene 2 in prostatic carcinoma

To study the expression of N-myc Downstream Regulated Gene-2 (NDRG2) in prostatic carcinoma (PCA) tissue and in different PCA cell lines, and to investigate its clinical and pathological implications, 144 PCA and benign prostatic hyperplasia (BPH) tissue sections were analyzed retrospectively with immunohistochemistry (S-P method). The expression levels of NDRG2 and c-Myc in prostate cell lines were detected through Western blot. The effects of adenovirus-mediated NDRG2 on PC3 cells and PC3 nude mouse xenografts was observed through cell growth curves, tumor growth curves, flow cytometry (FCM), transmission electron microscopy (TEM) and TUNEL staining. The NDRG2 gene was highly expressed in BPH tissues, but not in carcinomatous ones (χ2=25.98, p < 0.001). Furthermore, positive expression of NDRG2 was negatively correlated with the Gleason score（r=－0.445, p 0.05). The expression of the NDRG2 genes was low in the three PCA cell lines. PC3 cells infected by pAD-cmv-NDRG2 showed inhibition of proliferation both in vitro and vivo. To sum up, NDRG2 may be involved in the carcinogenesis and progression of PCA. Moreover, adenovirus-mediated NDRG2 can suppress the proliferation of PC3 cells significantly both in vitro and in vivo. These results indicate that NDRG2 may become a new target gene for PCA diagnosis and therapy.

Near‑infrared fluorescence imaging of prostate cancer using heptamethine carbocyanine dyes

Near-infrared fluorescence (NIRF) imaging is an attractive novel modality for the detection of cancer. A previous study defined two organic polymethine cyanine dyes as ideal NIRF probes, IR-783 and its derivative MHI-148, which have excellent optical characteristics, superior biocompatibility and cancer targeting abilities. To investigate the feasibility of NIRF dye-mediated prostate cancer imaging, dye uptake and subcellular co-localization were investigated in PC-3, DU-145 and LNCaP human prostate cancer cells and RWPE-1 normal prostate epithelial cells. Different organic anion transporting peptide (OATP) inhibitors were utilized to explore the potential role of the OATP subtype, including the nonspecific OATP inhibitor bromosulfophthalein, the OATP1 inhibitor 17β-estradiol, the selective OATP1B1 inhibitor rifampicin and the selective OATP1B3 inhibitor cholecystokinin octapeptide. NIRF dyes were also used for the simulated detection of circulating tumor cells and the rapid detection of prostate cancer in human prostate cancer tissues and prostate cancer xenografts in mouse models. The results revealed that the cancer-specific uptake of these organic dyes in prostate cancer cells occurred primarily via OATP1B3. A strong NIRF signal was detected in prostate cancer tissues, but not in normal tissues that were stained with IR-783. Prostate cancer cells were recognized with particular NIR fluorescence in isolated mononuclear cell mixtures. The results of the present study demonstrated that NIRF dye-mediated imaging is a feasible and practicable method for prostate cancer detection, although further investigative studies are required before clinical translation.