Dan Shao

Carbon dots as a trackable drug delivery carrier for localized cancer therapy in vivo

Fluorescent carbon dots (CDs) with a size smaller than 10 nm, excellent biocompatibility, and low to no cytotoxicity are considered as a rising star in nanomedicine. In this report, for the first time we demonstrate that green-emitting CDs with a carboxyl-rich surface can be employed as a trackable drug delivery agent for localized cancer treatment in a mouse model. The CDs are conjugated with the cancer drug, Doxorubicin (DOX), via non-covalent bonding, utilizing the native carboxyl groups on CDs and the amine moiety on DOX molecules. The pH difference between cancer and normal cells was successfully exploited as the triggering mechanism for DOX release. Our in vivo study demonstrated that the fluorescent CDs can serve as a targeted drug delivery system for localized therapy, and the stimuli-responsive non-covalent bonding between the nanodot carrier and the drug molecule is sufficiently stable in complex biological systems. Taken together, our work provides a strategy to promote the potential clinical application of CDs in cancer theranostics.

Monitoring HSV-TK/ganciclovir cancer suicide gene therapy using CdTe/CdS core/shell quantum dots

To be able to label a gene and monitor its migration are key important approaches for the clinical application of cancer suicide gene therapy. Photonic nanomaterials are introduced in this work. One of the most promised suicide genes - herpes simplex virus thymidine kinase (HSV-TK) gene - is successfully linked with CdTe/CdS core/shell quantum dots (QDs) via EDC/NHS coupling method. From confocal microscopy it was demonstrated that plasmid TK intracellular trafficking can be effectively and distinctly traced via monitoring the luminescence of the QDs up to 96 h after transfection of QDs-TK conjugates into Hela cells. MTT results show that the QDs-TK conjugates have a high efficient cytotoxicity after adding GCV into Hela cells, whereas the QDs exert no detectable deleterious effects on the cellular processes. The apoptosis induced by QDs-TK conjugates with GCV is distinctly traced partly due to the strong luminescence of the QDs. Our results indicate that photonic nanomaterials, e.g. QDs, provide a tool for monitoring TK gene delivery and anti-cancer activity.

The shape effect of magnetic mesoporous silica nanoparticles on endocytosis, biocompatibility and biodistribution

Although the aspect ratio (AR) play a crucial role in determining biological effects of homogeneous nanomaterials, studies available concerning how the shape contributes to biological effect of heterogeneous nanomaterials is limited. To systematically clarify the shape influence on the endocytosis, biocompatibility and biodistribution of magnetic mesoporous silica nanoparticles (M-MSNPs), three FITC-labeled M-MSNPs with different aspect ratio (AR=1, 2, and 4) were specifically designed and constructed through altering the ratios of CTAB/TEOS in a modified so-gel method. We have demonstrated that long-rod M-MSNP2 possessed higher intracellular internalization amount than the short-rod M-MSNP1 and the sphere-like M-MSNP0 in both cancer cells and normal cells due to the difference in the endocytosis pathways. However, there are no significant shape effects on biocompatibility including cytotoxicity and hemolytic rate. Moreover, biodistribution in HepG2 tumor-bearing mice showed that M-MSNPs administrated intravenously were mainly presented in reticuloendothelial system (RES) organs including liver, spleen and kidney. In particular, sphere-like M-MSNP0 were easily trapped in the liver, while long-rod M-MSP2 exhibited more retention in the spleen. It is worth noting that rod-like M-MSNPs are preferentially accumulated in tumor sites than sphere-like M-MSNPs, indicating an improved drug delivery efficacy in cancer therapy. Our findings may provide useful data for deeply understanding the interaction between the different shapes and biological behavior of M-MSNPs, which is expected to give rise to a new generation of heterogeneous M-MSNPs with significantly enhanced efficacy and safety for the cancer theranostics. STATEMENT OF SIGNIFICANCE In this work, we systematically clarified the shape influence on the endocytosis, biocompatibility and biodistribution of homogeneous nanomaterials. We have demonstrated that rod-like magnetic mesoporous silica nanoparticles (M-MSNPs) were capable of higher intracellular internalization and tumor accumulation than sphere-like M-MSNPs, which was expected to give rise to a new generation of heterogeneous M-MSNPs with significantly enhanced efficacy and safety for the cancer theranostics.

Usnic acid induces apoptosis via an ROS-dependent mitochondrial pathway in human breast cancer cells in vitro and in vivo

Usnic acid (UA), an active dibenzofuran derivative mainly found in lichens, is considered an antineoplastic agent based on its activity against tumor cells. However, the exact molecular mechanism through which UA mediates this activity has yet to be elucidated. Here, we have shown that UA selectively inhibited the viability of human breast cancer MCF-7 cells in a concentration- and time-dependent manner. UA provoked the generation of reactive oxygen species (ROS), which triggered the mitochondrial/caspase apoptotic pathway in MCF-7 cells. N-Acetylcysteine (NAC) blocked the generation of ROS, which reduced the stimulation of apoptotic mechanisms including activation of c-Jun-N-terminal kinase (JNK), loss of mitochondrial membrane potential (MMP), release of cytochrome-c, and activation of the caspase–cascade. Moreover, UA markedly inhibited tumor growth in a dose-dependent manner in MCF-7 tumor-bearing mice without inducing significant toxicity. Taken together, these findings suggested that UA stimulated apoptosis through an ROS-dependent mitochondrial pathway in MCF-7 cells.

Cytotoxicity of various types of gold-mesoporous silica nanoparticles in human breast cancer cells.

Recently, gold nanoparticles (AuNPs) have shown promising biological applications due to their unique electronic and optical properties. However, the potential toxicity of AuNPs remains a major hurdle that impedes their use in clinical settings. Mesoporous silica is very suitable for the use as a coating material for AuNPs and might not only reduce the cytotoxicity of cetyltrimethylammonium bromide-coated AuNPs but might also facilitate the loading and delivery of drugs. Herein, three types of rod-like gold-mesoporous silica nanoparticles (termed bare AuNPs, core–shell Au@mSiO2NPs, and Janus Au@mSiO2NPs) were specially designed, and the effects of these AuNPs on cellular uptake, toxic behavior, and mechanism were then systematically studied. Our results indicate that bare AuNPs exerted higher toxicity than the Au@mSiO2NPs and that Janus Au@mSiO2NPs exhibited the lowest toxicity in human breast cancer MCF-7 cells, consistent with the endocytosis capacity of the nanoparticles, which followed the order, bare AuNPs > core–shell Au@mSiO2NPs > Janus Au@mSiO2NPs. More importantly, the AuNPs-induced apoptosis of MCF-7 cells exhibited features that were characteristic of intracellular reactive oxygen species (ROS) generation, activation of c-Jun-N-terminal kinase (JNK) phosphorylation, an enhanced Bax-to-Bcl-2 ratio, and loss of the mitochondrial membrane potential. Simultaneously, cytochrome c was released from mitochondria, and the caspase-3/9 cascade was activated. Moreover, both ROS scavenger (N-acetylcysteine) and JNK inhibitor (SP600125) partly blocked the induction of apoptosis in all AuNPs-treated cells. Taken together, these findings suggest that all AuNPs induce apoptosis through the ROS-/JNK-mediated mitochondrial pathway. Thus, Janus Au@mSiO2NPs exhibit the potential for applications in biomedicine, thus aiding the clinical translation of AuNPs.

Adipose tissue-secreted miR-27a promotes liver cancer by targeting FOXO1 in obese individuals

The current notion that obesity is a major risk factor for the development of and the mortality associated with a subset of liver cancer is well appreciated. However, detailed mechanistic insights underlying this relationship are lacking. Better understanding of the adipose tissue-secreted miRNAs that play a potential role in defining primary liver cancer development and mediating the obesity-cancer communication offers the potential for new insights into tumor growth and interventions to modulate tumor formation and progression. In this study, we clearly demonstrated that miR-27a is more highly upregulated in cancer, plasma, and adipose samples from obese liver cancer cases, and therefore reasoned that miR-27a excreted from adipose tissue leads to liver cancer development. To address this idea, we prepared miR-27a-overexpressing 3T3-L1 adipocytes and cocultured them with HepG2 liver cancer cells. Our results demonstrated that secretory miR-27a promoted liver cancer cell proliferation through the downregulation of the transcription factor FOXO1 and promoted the G1/S cell cycle transition by decreasing the cell cycle inhibitors p21 and p27 and increasing the cell cycle regulator cyclin D1. These findings improve our understanding of the involvement of miR-27a in obesity-liver cancer communication and might provide a novel putative target for obesity-driven primary liver cancer diagnosis and therapy.

Facile Synthesis of Core–shell Magnetic Mesoporous Silica Nanoparticles for pH‐sensitive Anticancer Drug Delivery

The facile synthesis of core–shell magnetic mesoporous silica nanoparticles (Fe3O4@mSiO2 NPs) was reported in aqueous phase using cetyltrimethylammonium bromide as a template under alcohol‐free conditions. Compared to the conventional synthesis method for core–shell Fe3O4@mSiO2 NPs, the approach in this study is rapid (only 5‐min reaction time), cheap (without using organic agents), and environmentally friendly (one‐step synthesis in alcohol‐free medium). Doxorubicin (DOX)‐loaded Fe3O4@mSiO2 NPs exert extraordinarily high specificity for liver cancer cells, which was due to the pH‐sensitive doxorubicin release, as well as higher endocytosis capacity in liver cancer cells rather than normal liver cells. The potential advantages of using such Fe3O4@mSiO2 NPs as the vehicle of anticancer drugs were that the Fe3O4@mSiO2 NPs exhibit good biocompatibility, high loading and protection of the guest molecules, selective killing effect, and efficient cellular uptake. The exciting pH‐dependent release properties of doxorubicin‐loaded Fe3O4@mSiO2 NPs make their use a promising strategy for enhancing efficient therapy toward tumors, while reducing the cytotoxicity of doxorubicin to human normal neutral tissue or cells.

Selective inhibition of liver cancer growth realized by the intrinsic toxicity of a quantum dot-lipid complex

Using the intrinsic toxicity of nanomaterials for anticancer therapy is an emerging concept. In this work, we discovered that CdTe/CdS quantum dots, when coated with lipids (QD-LC) instead of popular liposomes, polymers, or dendrimers, demonstrated extraordinarily high specificity for cancer cells, which was due to the difference in the macropinocytosis uptake pathways of QD-LC between the cancer cells and the normal cells. QD-LC-induced HepG2 cell apoptosis was concomitant with the activation of the JNK/caspase-3 signaling pathway. Moreover, QD-LC treatment resulted in a delay in the latent period for microtumor formation of mouse hepatocarcinoma H22 cells and inhibited tumor growth, with a reduction of 53.2% in tumor volume without toxicity in major organs after intratumoral administrations to tumor-bearing mice. Our results demonstrate that QD-LC could be a very promising theranostic agent against liver cancer.

MiR-27a promotes hepatocellular carcinoma cell proliferation through suppression of its target gene peroxisome proliferator-activated receptor γ.

Background: MicroRNAs (miRNAs) function as essential posttranscriptional modulators of gene expression, and are involved in a wide range of physiologic and pathologic states, including cancer. Numerous miRNAs are deregulated in hepatocellular carcinoma (HCC). This study aimed to investigate the role of miR-27a in the development of HCC. Methods: The expression of MiR-27a was measured by quantitative real-time polymerase chain reaction (qRT-PCR). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to examine changes in the viability of HepG2, Bel-7402, Bel-7404 hepatoma cell lines associated with up-regulation or down-regulation of miR-27a. A dual-luciferase activity assay was used to verify a target gene of miR-27a. Immunohistochemistry, qRT-PCR, Western blotting analysis, and cell cycle and apoptosis flow cytometric assays were used to elucidate the mechanism by which miR-27a modulates liver cancer cell proliferation. Results: The expression of miR-27a was significantly increased in HCC tissues and HepG2, Bel-7402, Bel-7404 hepatoma cell lines (P < 0.05). We also found that the down-regulation of miR-27a in HepG2 cells dramatically inhibited proliferation, blocked the G1 to S cell cycle transition and induced apoptosis (P < 0.05). In addition, miR-27a directly targeted the 3’-untranslated region of peroxisome proliferator-activated receptor &ggr; (PPAR-&ggr;), and ectopic miR-27a expression suppressed PPAR-&ggr; expression on the mRNA and protein levels. The rosiglitazone-induced overexpression of PPAR-&ggr; attenuated the effect of miR-27a in HCC cells. Conclusions: Our findings suggested that miRNA-27a promoted HCC cell proliferation by regulating PPAR-&ggr; expression. MiR-27a may provide a potential therapeutic strategy for HCC treatment.

Inhibitory effect of celecoxib in lung carcinoma by regulation of cyclooxygenase-2/cytosolic phospholipase A2 and peroxisome proliferator-activated receptor gamma

Celecoxib is a potent nonsteroid anti-inflammatory drug (NSAID) that has demonstrated great promise in cancer chemoprevention and treatment. The goal of this study was to determine the inhibitory effect and mechanism of celecoxib on Lewis lung carcinoma. The effect of celecoxib on viability of Lewis lung carcinoma cells was assessed with methyl thiazolyl tetrazolium (MTT) assay. Apoptosis and the mitochondrial membrane potential were detected by flow cytometric assay. The protein expression of cytosolic phospholipase A2 (cPLA2), cyclooxygenase-2 (COX-2), and peroxisome proliferator-activated receptor gamma (PPARγ) were determined by Western blot analysis. The concentrations of arachidonic acid (AA) and prostaglandin E2 (PGE2) in culture supernatants were measured by the methods of RP-HPLC and PGE2-specific ELISA, respectively. Celecoxib inhibited the proliferation of Lewis lung carcinoma and induced apoptosis in a dose-dependent manner by breakdown of mitochondrial membrane potential. The protein expressions of cPLA2 and PPARγ were upregulated, but COX-2 protein expression was downregulated in the Lewis lung carcinoma cells exposed to celecoxib. The amount of AA was increased and PGE2 was decreased in the culture supernatant, respectively. The ratio of AA to PGE2 was increased in a dose-dependent manner. The major findings in this study are that celecoxib could inhibit the viability of Lewis lung carcinoma cells by interference of the AA pathway and upregulation of PPARγ simultaneously, which are novel and important since the molecular mechanisms of celecoxib underlying the anti-neoplastic effects remain unclear.