Intratumoral Biosynthesis of Gold Nanoclusters by Pancreatic Cancer to Overcome Delivery Barriers to Radiosensitization.

Nanoparticle delivery to solid tumors is a prime challenge in nanomedicine. Here, we approach this challenge through the lens of biogeochemistry, the field that studies the flow of chemical elements within ecosystems as manipulated by living cellular organisms and their environments. We leverage biogeochemistry concepts related to gold cycling against pancreatic cancer, considering mammalian organisms as drivers for gold nanoparticle biosynthesis. Sequestration of gold nanoparticles within tumors has been demonstrated as an effective strategy to enhance radiotherapy; however, the desmoplasia of pancreatic cancer impedes nanoparticle delivery. Our strategy overcomes this barrier by applying an atomic-scale agent, ionic gold, for intratumoral gold nanoparticle biosynthesis. Our comprehensive studies showed the cancer-specific synthesis of gold nanoparticles from externally delivered gold ions in vitro and in a murine pancreatic cancer model in vivo; a substantial colocalization of gold nanoparticles (GNPs) with cancer cell nuclei in vitro and in vivo; a strong radiosensitization effect by the intracellularly synthesized GNPs; a uniform distribution of in situ synthesized GNPs throughout the tumor volume; a nearly 40-day total suppression of tumor growth in animal models of pancreatic cancer treated with a combination of gold ions and radiation that was also associated with a significantly higher median survival versus radiation alone (235 vs 102 days, respectively).

Dual enhancement in the radiosensitivity of prostate cancer through nanoparticles and chemotherapeutics.

Background: Radiotherapy (RT) is an essential component in the treatment regimens for many cancer patients. However, the dose escalation required to improve curative results is hindered due to the normal tissue toxicity that is induced. The introduction of radiosensitizers to RT treatment is an avenue that is currently being explored to overcome this issue. By introducing radiosensitizers into tumor sites, it is possible to preferentially enhance the local dose deposited. Gold nanoparticles (GNPs) are a potential candidate that have shown great promise in increasing the radiosensitivity of cancer cells through an enhancement in DNA damage. Furthermore, docetaxel (DTX) is a chemotherapeutic agent that arrests cells in the G2/M phase of the cell cycle, the phase most sensitive to radiation damage. We hypothesized that by incorporating DTX to GNP-enhanced radiotherapy treatment, we could further improve the radiosensitization experienced by cancer cells. To assess this strategy, we analyzed the radiotherapeutic effects on monolayer cell cultures in vitro, as well as on a mice prostate xenograft model in vivo while using clinically feasible concentrations for both GNPs and DTX. Results: The introduction of DTX to GNP-enhanced radiotherapy further increased the radiotherapeutic effects experienced by cancer cells. A 38% increase in DNA double-strand breaks was observed with the combination of GNP/DTX vs GNP alone after a dose of 2 Gy was administered. In vivo results displayed significant reduction in tumor growth over a 30-day observation period with the treatment of GNP/DTX/RT when compared to GNP/RT after a single 5 Gy dose was given to mice. The treatment strategy also resulted in 100% mice survival, which was not observed for other treatment conditions. Conclusions: Incorporating DTX to work in unison with GNPs and RT can increase the efficacy of RT treatment. Our study suggests that the treatment strategy could improve tumor control through local dose enhancement. As the concentrations used in this study are clinically feasible, there is potential for this strategy to be translated into clinical settings. Supplementary Information: The online version contains supplementary material available at 10.1186/s12645-023-00228-0.

Next-Generation Boron Drugs and Rational Translational Studies Driving the Revival of BNCT.

BNCT is a high-linear-energy transfer therapy that facilitates tumor-directed radiation delivery while largely sparing adjacent normal tissues through the biological targeting of boron compounds to tumor cells. Tumor-specific accumulation of boron with limited accretion in normal cells is the crux of successful BNCT delivery. Given this, developing novel boronated compounds with high selectivity, ease of delivery, and large boron payloads remains an area of active investigation. Furthermore, there is growing interest in exploring the immunogenic potential of BNCT. In this review, we discuss the basic radiobiological and physical aspects of BNCT, traditional and next-generation boron compounds, as well as translational studies exploring the clinical applicability of BNCT. Additionally, we delve into the immunomodulatory potential of BNCT in the era of novel boron agents and examine innovative avenues for exploiting the immunogenicity of BNCT to improve outcomes in difficult-to-treat malignancies.

Radiolabeled nanomaterial for cancer diagnostics and therapeutics: principles and concepts.

In the last three decades, radiopharmaceuticals have proven their effectiveness for cancer diagnosis and therapy. In parallel, the advances in nanotechnology have fueled a plethora of applications in biology and medicine. A convergence of these disciplines has emerged more recently with the advent of nanotechnology-aided radiopharmaceuticals. Capitalizing on the unique physical and functional properties of nanoparticles, radiolabeled nanomaterials or nano-radiopharmaceuticals have the potential to enhance imaging and therapy of human diseases. This article provides an overview of various radionuclides used in diagnostic, therapeutic, and theranostic applications, radionuclide production through different techniques, conventional radionuclide delivery systems, and advancements in the delivery systems for nanomaterials. The review also provides insights into fundamental concepts necessary to improve currently available radionuclide agents and formulate new nano-radiopharmaceuticals.

Pancreatic tumor microenvironmental acidosis and hypoxia transform gold nanorods into cell-penetrant particles for potent radiosensitization.

Coating nanoparticles with stealth epilayers increases circulation time by evading opsonization, macrophage phagocytosis, and reticuloendothelial sequestration. However, this also reduces internalization by cancer cells upon reaching the tumor. We designed gold nanorods (GNRs) with an epilayer that retains stealth properties in circulation but transforms spontaneously in the acidotic tumor microenvironment to a cell-penetrating particle. We used a customized stoichiometric ratio of l-glutamic acid and l-lysine within an amphiphilic polymer of poly(l-glutamic acid-co-l-lysine), or P(Glu-co-Lys), to effect this transformation in acidotic environments. P(Glu-co-Lys)-GNRs were internalized by cancer cells to facilitate potent in vitro radiosensitization. When administered intravenously in mice, they accumulate in the periphery and core of tumors without any signs of serum biochemical or hematological alterations, normal organ histopathological abnormalities, or overt deterioration in animal health. Furthermore, P(Glu-co-Lys)-GNRs penetrated the tumor microenvironment to accumulate in the hypoxic cores of tumors to potently radiosensitize heterotopic and orthotopic pancreatic cancers in vivo.

Uncloaking cell-impermeant gold nanorods via tumor microenvironmental cathepsin B facilitates cancer cell penetration and potent radiosensitization.

Major impediments to conveyance of intravenously administered drugs to tumors are biofouling, opsonization, and rapid clearance from the circulation by macrophages and reticuloendothelial phagocytes. Cloaking nanoparticles with stealth epilayers partly overcomes these hurdles but it also foils interactions with tumor cells. Here, we describe the synthesis, characterization, and validation of smart gold nanorods (GNRs) that spontaneously transform from inert passengers in the blood stream to active cell-penetrating nanoparticles within tumors to potently sensitize tumors to radiation therapy. Intrinsically cationic and cell-penetrating GNRs were shielded from phagocytosis with a cloaking polyethylene glycol epilayer containing an intervening cleavable peptide. In the absence of an external trigger, this epilayer is clipped off by the tumor microenvironmental protease, cathepsin B, in colorectal cancers to uncloak and expose the free-circulating native unPEGylated GNR that is readily internalized by cancer cells and turn into immovable small clusters of GNRs. Selective uncloaking of GNRs in the tumor reduced off-target toxicity confirmed by hematologic, biochemical, and histopathological analysis of blood, serum, and normal organs, respectively. Subsequent irradiation led to significant tumor growth delay and improved survival of mice. By addressing multiple barriers to efficient transport and cellular internalization of nanoparticles, our results demonstrate that clinically meaningful radiosensitization can be achieved with rationally designed GNRs.

Identification of Synergistic Drug Combinations to Target KRAS-Driven Chemoradioresistant Cancers Utilizing Tumoroid Models of Colorectal Adenocarcinoma and Recurrent Glioblastoma.

Treatment resistance is observed in all advanced cancers. Colorectal cancer (CRC) presenting as colorectal adenocarcinoma (COAD) is the second leading cause of cancer deaths worldwide. Multimodality treatment includes surgery, chemotherapy, and targeted therapies with selective utilization of immunotherapy and radiation therapy. Despite the early success of anti-epidermal growth factor receptor (anti-EGFR) therapy, treatment resistance is common and often driven by mutations in APC, KRAS, RAF, and PI3K/mTOR and positive feedback between activated KRAS and WNT effectors. Challenges in the direct targeting of WNT regulators and KRAS have caused alternative actionable targets to gain recent attention. Utilizing an unbiased drug screen, we identified combinatorial targeting of DDR1/BCR-ABL signaling axis with small-molecule inhibitors of EGFR-ERBB2 to be potentially cytotoxic against multicellular spheroids obtained from WNT-activated and KRAS-mutant COAD lines (HCT116, DLD1, and SW480) independent of their KRAS mutation type. Based on the data-driven approach using available patient datasets (The Cancer Genome Atlas (TCGA)), we constructed transcriptomic correlations between gene DDR1, with an expression of genes for EGFR, ERBB2-4, mitogen-activated protein kinase (MAPK) pathway intermediates, BCR, and ABL and genes for cancer stem cell reactivation, cell polarity, and adhesion; we identified a positive association of DDR1 with EGFR, ERBB2, BRAF, SOX9, and VANGL2 in Pan-Cancer. The evaluation of the pathway network using the STRING database and Pathway Commons database revealed DDR1 protein to relay its signaling via adaptor proteins (SHC1, GRB2, and SOS1) and BCR axis to contribute to the KRAS-PI3K-AKT signaling cascade, which was confirmed by Western blotting. We further confirmed the cytotoxic potential of our lead combination involving EGFR/ERBB2 inhibitor (lapatinib) with DDR1/BCR-ABL inhibitor (nilotinib) in radioresistant spheroids of HCT116 (COAD) and, in an additional devastating primary cancer model, glioblastoma (GBM). GBMs overexpress DDR1 and share some common genomic features with COAD like EGFR amplification and WNT activation. Moreover, genetic alterations in genes like NF1 make GBMs have an intrinsically high KRAS activity. We show the combination of nilotinib plus lapatinib to exhibit more potent cytotoxic efficacy than either of the drugs administered alone in tumoroids of patient-derived recurrent GBMs. Collectively, our findings suggest that combinatorial targeting of DDR1/BCR-ABL with EGFR-ERBB2 signaling may offer a therapeutic strategy against stem-like KRAS-driven chemoradioresistant tumors of COAD and GBM, widening the window for its applications in mainstream cancer therapeutics.

3JC48-3 (methyl 4'-methyl-5-(7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)-[1,1'-biphenyl]-3-carboxylate): a novel MYC/MAX dimerization inhibitor reduces prostate cancer growth.

The proto-oncogene cellular myelocytomatosis (c-Myc) is a transcription factor that is upregulated in several human cancers. Therapeutic targeting of c-Myc remains a challenge because of a disordered protein tertiary structure. The basic helical structure and zipper protein of c-Myc forms an obligate heterodimer with its partner MYC-associated factor X (MAX) to function as a transcription factor. An attractive strategy is to inhibit MYC/MAX dimerization to decrease c-Myc transcriptional function. Several methods have been described to inhibit MYC/MAX dimerization including small molecular inhibitors and proteomimetics. We studied the effect of a second-generation small molecular inhibitor 3JC48-3 on prostate cancer growth and viability. In our experimental studies, we found 3JC48-3 decreases prostate cancer cells' growth and viability in a dose-dependent fashion in vitro. We confirmed inhibition of MYC/MAX dimerization by 3JC48-3 using immunoprecipitation experiments. We have previously shown that the MYC/MAX heterodimer is a transcriptional repressor of a novel kinase protein kinase D1 (PrKD1). Treatment with 3JC48-3 upregulated PrKD1 expression and phosphorylation of known PrKD1 substrates: the threonine 120 (Thr-120) residue in beta-catenin and the serine 216 (Ser-216) in Cell Division Cycle 25 (CDC25C). The mining of gene expression in human metastatic prostate cancer samples demonstrated an inverse correlation between PrKD1 and c-Myc expression. Normal mice and mice with patient-derived prostate cancer xenografts (PDX) tolerated intraperitoneal injections of 3JC48-3 up to 100 mg/kg body weight without dose-limiting toxicity. Preliminary results in these PDX mouse models suggest that 3JC48-3 may be effective in decreasing the rate of tumor growth. In conclusion, our study demonstrates that 3JC48-3 is a potent MYC/MAX heterodimerization inhibitor that decreases prostate cancer growth and viability associated with upregulation of PrKD1 expression and kinase activity.

CXC chemokine receptor 4 (CXCR4) targeted gold nanoparticles potently enhance radiotherapy outcomes in breast cancer.

CXC chemokine receptor 4 (CXCR4) is overexpressed on most breast cancer cell surfaces including triple negative breast cancer (TNBC) which lacks traditional receptor overexpression. We targeted gold nanoparticles (GNPs) to this receptor via conjugation to anti-CXCR4 antibody (cGNPs). Irradiation of cells treated with cGNPs compared to PEGylated GNPs (pGNPs) resulted in more prominent radiosensitization of MDA-MB-231 cells with abundant CXCR4 overexpression than HTB-123 cells with moderate and MCF-7 cells with minimal CXCR4 overexpression. Overexpression of CXCR4 facilitated improved cellular internalization of cGNPs and irradiation of internalized cGNPs resulted in more unrepaired DNA double strand breaks and increased the production of oxygen free radicals compared to irradiation with non-internalized pGNPs. In a murine TNBC xenograft model, CXCR4 targeting potently increased tumor regrowth delay following radiation compared to radiation in the presence of pGNPs or vehicle alone. CXCR4 targeted GNPs enhance the efficacy of TNBC radiotherapy by increasing oxidative stress and DNA damage.

Stability of MRI contrast agents in high-energy radiation of a 1.5T MR-Linac.

BACKGROUND: Gadolinium-based contrast is often used when acquiring MR images for radiation therapy planning for better target delineation. In some situations, patients may still have residual MRI contrast agents in their tissue while being treated with high-energy radiation. This is especially true when MRI contrast agents are administered during adaptive treatment replanning for patients treated on MR-Linac systems. PURPOSE: The purpose of this study was to analyze the molecular stability of MRI contrast agents when exposed to high energy photons and the associated secondary electrons in a 1.5T MR-Linac system. This was the first step in assessing the safety of administering MRI contrast agents throughout the course of treatment. MATERIALS AND METHODS: Two common MRI contrast agents were irradiated with 7 MV photons to clinical dose levels. The irradiated samples were analyzed using liquid chromatography-high resolution mass spectrometry to detect degradation products or conformational alterations created by irradiation with high energy photons and associated secondary electrons. RESULTS: No significant change in chemical composition or displacement of gadolinium ions from their chelates was discovered in samples irradiated with 7 MV photons at relevant clinical doses in a 1.5T MR-Linac. Additionally, no significant correlation between concentrations of irradiated MRI contrast agents and radiation dose was observed. CONCLUSION: The chemical composition stability of the irradiated contrast agents is promising for future use throughout the course of patient treatment. However, in vivo studies are needed to confirm that unexpected metabolites are not created in biological milieus.

Synthesis and characterization of gadolinium-decorated [60]fullerene for tumor imaging and radiation sensitization.

PURPOSE: The excellent contrast of high atomic number (Z) elements compared to soft tissues has advanced their use as contrast agents for computed tomographic imaging and as potential radiation sensitizers. We evaluated whether gadolinium (Gd) could serve as such a theranostic agent for high-resolution magnetic resonance imaging (MRI) due to its paramagnetic properties and radiosensitization due to its high Z. MATERIALS AND METHODS: To improve the relaxivity of Gd, we coupled it to [60]fullerene, an elemental carbon allotropic nanoparticle that seamlessly traverses physiological barriers . By adding serinol, an aliphatic alcohol derived from amino acid serine, we turned [60]fullerene, which is otherwise insoluble in water, into a highly water-soluble derivative and decorated it externally with a payload of chelated gadolinium ions. RESULTS: When [60]fullerene was functionalized in this manner with two gadolinium ions (Gd2C60), it displayed considerably higher T1 relaxivity at 4.7 T than the commercially used MRI contrast agent, Magnevist, (18.2 mM-1s-1 vs. 4.7 mM-1s-1). Attempts to increase this even further via decoration of [60]fullerene with 12 gadolinium ions was unsuccessful due to a poor water solubility. However, the current formulation of Gd2C60 did not result in any appreciable radiosensitization. CONCLUSION: Our results show a successful generation of a novel contrast agent via decoration of fullerene with two chelated Gd ions. Though this formulation was not successful in generating radiosensitization, other chemical modifications can be further explored to increase radiosensitization potential.

Author Correction: A recellularized human colon model identifies cancer driver genes.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Boron-Nanoparticle-Loaded Folic-Acid-Functionalized Liposomes to Achieve Optimum Boron Concentration for Boron Neutron Capture Therapy of Cancer.

In this study, we have synthesized and characterized a pure boron nanoparticle containing asolectin phospholipid-based liposome construct prepared using a water-in-oil emulsion method, as a novel alternative agent for BNCT, which contain poly(maleic anhydride-alt-1-octadecene) (PMAO) and polyethylene glycol (PEG) on the surface, and Cy5 near infrared (NIR) fluorescent dye and boron nanoparticles in the core (3PCB). A tumor-specific targeting ligand, folic acid (FA), was conjugated to PEG to produce a folate-functionalized liposome (FA-3PCB) for improved targeted delivery and accumulation of boron in cancer cells. The liposomes showed an average diameter of 100-120 nm and zeta potential of -38.0±1.5 mV. Cellular uptake monitored by fluorescence microscopy confirmed the targeting capability of FA-conjugated liposomes. Accumulation of FA-conjugated liposomes in C6-brain tumor cells was much higher than that of non-FA conjugated liposomes under the same conditions. ICP-MS (Inductively Coupled Plasma Mass Spectrometry) quantification confirmed that boron accumulated in cancer cells to sufficient intracellular concentration for therapeutic benefit from BNCT. These liposomes show blood-brain barrier (BBB) crossing ability, low cytotoxicity, and excellent stability under physiological conditions. Thus, these liposomes are a promising new boron carrier for BNCT.

Gold-Small Interfering RNA as Optically Responsive Nanostructures for Cancer Theranostics.

Small interfering RNA (siRNA), with its highly sequence-specific ability to modulate target gene expression, is seen as a promising therapeutic approach in cancer therapy. However, the major impediments to widespread clinical utilization are the optimal and durable targeting of target genes and safe and effective delivery of siRNA to the site of interest in the tumor niche. In this review, we will discuss gold nanocarriers with varied geometries and architecture as siRNA delivery vehicles for targeted cancer treatment. In addition, the gold nanostructures provide optical imaging functionalities as well as the ability to optically track delivery of siRNA to the cancer site, thus enabling true theranostics.

Biotransport kinetics and intratumoral biodistribution of malonodiserinolamide-derivatized [60]fullerene in a murine model of breast adenocarcinoma.

[60]Fullerene is a highly versatile nanoparticle (NP) platform for drug delivery to sites of pathology owing to its small size and both ease and versatility of chemical functionalization, facilitating multisite drug conjugation, drug targeting, and modulation of its physicochemical properties. The prominent and well-characterized role of the enhanced permeation and retention (EPR) effect in facilitating NP delivery to tumors motivated us to explore vascular transport kinetics of a water-soluble [60]fullerene derivatives using intravital microscopy in an immune competent murine model of breast adenocarcinoma. Herein, we present a novel local and global image analysis of vascular transport kinetics at the level of individual tumor blood vessels on the micron scale and across whole images, respectively. Similar to larger nanomaterials, [60]fullerenes displayed rapid extravasation from tumor vasculature, distinct from that in normal microvasculature. Temporal heterogeneity in fullerene delivery to tumors was observed, demonstrating the issue of nonuniform delivery beyond spatial dimensions. Trends in local region analysis of fullerene biokinetics by fluorescence quantification were in agreement with global image analysis. Further analysis of intratumoral vascular clearance rates suggested a possible enhanced penetration and retention effect of the fullerene compared to a 70 kDa vascular tracer. Overall, this study demonstrates the feasibility of tracking and quantifying the delivery kinetics and intratumoral biodistribution of fullerene-based drug delivery platforms, consistent with the EPR effect on short timescales and passive transport to tumors.

The effects of non-invasive radiofrequency electric field hyperthermia on biotransport and biodistribution of fluorescent [60]fullerene derivative in a murine orthotopic model of breast adenocarcinoma.

The aim of this study is to understand the combined and differential biokinetic effects of radiofrequency (RF) electric-field hyperthermia as an adjunctive therapy to [60]fullerene nanoparticle-based drug delivery systems in targeting the micro-vasculature and micro-environments of breast cancer tumors. Intravital microscopy (IVM) is an ideal tool to provide the spatial and temporal resolution needed for quantification in this investigation. The water-soluble and fluorescent [60]fullerene derivative (C60-serPF) was designed to be an amphiphilic nanostructure, which is able to cross several biological membranes and accumulate in tumor tissues by passing through abnormally leaky tumor blood vessels. To elucidate the coupled effects of the highly permeable, but heterogeneous tumor vasculature, with the permeabilizing effects of mild (40-42°C) hyperthermia produced by a local RF field, we controlled variables across tumor and non-tumor mammary gland microvasculature with and without application of RF hyperthermia in each condition. We notice that tumor tissue is characterized by more intense drug extravasation than in contralateral mammary fat pad tissue, which is consistent with enhanced permeability and retention (EPR) effects. The analysis of a permeability parameter (Papp), C60-serPF velocity, and the time of compound influx into the intra- and extra-vascular space suggest that mild RF hyperthermia can improve nanoparticle delivery into tumor tissue.

The influence of cell and nanoparticle properties on heating and cell death in a radiofrequency field.

The use of non-invasive radiofrequency (RF) energy to induce mild thermal and non-thermal effects in cancer tissue is under study as an adjuvant to chemo, radio or immuno therapy. This study examines cell specific sensitivities to RF exposure and the potential of nanoparticles to elevate heating rates or enhance biological effects. Increases in the heating rate of water in an RF field operating at 13.56MHz (0.004-0.028°C/s) were positively correlated with concentration of hybrid nanoparticles (1-10mg/ml) consisting of water soluble malonodiserinolamide [60]fullerene (C60-ser) conjugated to the surface of mesoporous silica nanoparticles (SiO2-C60). The heating rate of highly conductive cell culture media (0.024°C/s) was similar to that of the highest concentration of nanoparticles in water, with no significant increase due to addition of nanoparticles at relevant doses (<100µg/ml). With respect to cell viability, anionic (SiO2 and SiO2-C60) or neutral (C60) nanoparticles did not influence RF-induced cell death, however, cationic nanoparticles (4-100µg/ml) caused dose-dependent increases in RF-induced cell death (24-42% compared to RF only). The effect of cell type, size and immortalization on sensitivity of cells to RF fields was examined in endothelial (HUVEC and HMVEC), fibroblast (primary dermal and L939) and cancer cells (HeLa and 4T1). While the state of cellular immortalization itself did not consistently influence the rate of RF-induced cell death compared to normal cell counter parts, cell size (ranging from 7 to 30µm) negatively correlated with cell sensitivity to RF (21-97% cell death following 6min irradiation). In summary, while nanoparticles do not alter the heating rate of biologically-relevant solutions, they can increase RF-induced cell death based on intrinsic cytotoxicity; and cells with smaller radii, and thereby greater surface membrane, are more susceptible to cell damage in an RF field than larger cells. STATEMENT OF SIGNIFICANCE: The ability of nanoparticles to either direct heating or increase susceptibility of cancer cells to radiofrequency (RF) energy remains controversial, as is the impact of cell attributes on susceptibility of cells to RF-induced cell death. This manuscript examines the impact of nanoparticle charge, size, and cellular localization on RF-induced cell death and the influence of nanoparticles on the heating rates of water and biologically-relevant media. Susceptibility of immortalized or primary cells to RF energy and the impact of cell size are also examined. The ability to selectively modulate RF heating rates in specific biological locations or in specific cell populations would enhance the therapeutic potential of RF therapy.

A recellularized human colon model identifies cancer driver genes.

Refined cancer models are needed to bridge the gaps between cell line, animal and clinical research. Here we describe the engineering of an organotypic colon cancer model by recellularization of a native human matrix that contains cell-populated mucosa and an intact muscularis mucosa layer. This ex vivo system recapitulates the pathophysiological progression from APC-mutant neoplasia to submucosal invasive tumor. We used it to perform a Sleeping Beauty transposon mutagenesis screen to identify genes that cooperate with mutant APC in driving invasive neoplasia. We identified 38 candidate invasion-driver genes, 17 of which, including TCF7L2, TWIST2, MSH2, DCC, EPHB1 and EPHB2 have been previously implicated in colorectal cancer progression. Six invasion-driver genes that have not, to our knowledge, been previously described were validated in vitro using cell proliferation, migration and invasion assays and ex vivo using recellularized human colon. These results demonstrate the utility of our organoid model for studying cancer biology.

Surfactant-free Gd(3+)-ion-containing carbon nanotube MRI contrast agents for stem cell labeling.

There is an ever increasing interest in developing new stem cell therapies. However, imaging and tracking stem cells in vivo after transplantation remains a serious challenge. In this work, we report new, functionalized and high-performance Gd(3+)-ion-containing ultra-short carbon nanotube (US-tube) MRI contrast agent (CA) materials which are highly-water-dispersible (ca. 35 mg ml(-1)) without the need of a surfactant. The new materials have extremely high T1-weighted relaxivities of 90 (mM s)(-1) per Gd(3+) ion at 1.5 T at room temperature and have been used to safely label porcine bone-marrow-derived mesenchymal stem cells for MR imaging. The labeled cells display excellent image contrast in phantom imaging experiments, and TEM images of the labeled cells, in general, reveal small clusters of the CA material located within the cytoplasm with 10(9) Gd(3+) ions per cell.

Selective oxidative degradation of organic pollutants by singlet oxygen-mediated photosensitization: tin porphyrin versus C60 aminofullerene systems.

This study evaluates the potential application of tin porphyrin- and C(60) aminofullerene-derivatized silica (SnP/silica and aminoC(60)/silica) as (1)O(2) generating systems for photochemical degradation of organic pollutants. Photosensitized (1)O(2) production with SnP/silica, which was faster than with aminoC(60)/silica, effectively oxidized a variety of pharmaceuticals. Significant degradation of pharmaceuticals in the presence of the 400-nm UV cutoff filter corroborated visible light activation of both photosensitizers. Whereas the efficacy of aminoC(60)/silica for (1)O(2) production drastically decreased under irradiation with λ > 550 nm, Q-band absorption caused negligible loss of the photosensitizing activity of SnP/silica in the long wavelength region. Faster destruction of phenolates by SnP/silica and aminoC(60)/silica under alkaline pH conditions further implicated (1)O(2) involvement in the oxidative degradation. Direct charge transfer mediated by SnP, which was inferred from nanosecond laser flash photolysis, induced significant degradation of neutral phenols under high power light irradiation. Self-sensitized destruction caused gradual activity loss of SnP/silica in reuse tests unlike aminoC(60)/silica. The kinetic comparison of SnP/silica and TiO(2) photocatalyst in real wastewater effluents showed that photosensitized singlet oxygenation of pharmaceuticals was still efficiently achieved in the presence of background organic matters, while significant interference was observed for photocatalyzed oxidation involving non-selective OH radical.