Exploring the Application of Bifunctional Metal Chelators in Treating Triple-Negative Breast Cancer.

Purpose: In this study, we independently synthesised and labelled a novel bidentate bifunctional chelating agent, 177Lu-3,4-HOPO-Cetuximab, that achieved tight binding between targeting and radioactivity, and evaluated its targeted killing ability of cells in vitro and in vivo. Method: 3,4-HOPO was successfully synthesised through a series of chemical steps using malt phenol as the raw material, which was then coupled with Cetuximab labelled with 177Lu. 177Lu-3,4-HOPO-Cetuximab and 177Lu-DOTA-Cetuximab was tested for its cell viability and cell-binding rate after different times and at different doses by CCK-8 and cell-binding experiments. 177Lu-3,4-HOPO-Cetuximab (~500 µCi) and 177Lu-DOTA-Cetuximab (~500 µCi) were injected into the tail vein of a subcutaneous metastasis mouse model of triple-negative breast cancer with a single injection, and tumour volume growth and body weight changes were regularly monitored for 20 days. The radioactivity distribution in nude mice was analysed after sacrifice, and the treated and untreated tumour tissues were analysed by HE staining. Result: The cell viability of 177Lu-3,4-HOPO-Cetuximab declined exponentially after treatment for 48 h at 50 Bq/mL to 500 kBq/mL, respectively; the cell activity was slowed down from 8 to 96 h at a dose of 500 kBq; while the binding rate of 4T1 cells in 177Lu-3,4-HOPO-Cetuximab from 1 to 24 h, respectively, increased logarithmically, which was similar with 177Lu-DOTA-Cetuximab. After 20 days of treatment, the body weight of nude mice with 177Lu-3,4-HOPO-Cetuximab and 177Lu-DOTA-Cetuximab were hardly changed, while the body weight with physiological saline decreased significantly. The tumour inhibition rate of the 177Lu-3,4-HOPO-Cetuximab and 177Lu-DOTA-Cetuximab were (37.03 ± 11.16)% and (38.7 ± 5.1)%; HE staining showed that tumour cells were affected by the action of 177Lu causing necrosis. Conclusion: The experiments showed that 177Lu-3,4-HOPO-Cetuximab has a certain targeted therapeutic ability for triple-negative breast cancer, and it is expected to become a potential targeted nuclear medicine treatment for triple-negative breast cancer.

Detection of lymph node metastasis with near-infrared upconversion luminescent nanoprobes.

The detection of lymph node metastasis is of great importance for therapy planning and prognosis of cancers, but remains challenging in the clinic. In the current study, we report a tumor-specific imaging probe constructed with NaGdF4:Yb,Tm,Ca@NaLuF4 core@shell upconversion nanoparticles showing distinctive near infrared emission. The following studies revealed that the characteristic Tm dopant emission at 804 nm showed a penetration depth up to 7.7 mm through multi-layered mice skin tissues, substantially greater than emissions at 655 nm and 541 nm typically from the widely used Er dopant, which is apparently favorable for sensitive tumor diagnosis. The cell binding assay further revealed that the anti-HER2 antibodies covalently attached on the particle surface endowed the nanoprobe with excellent binding specificity in targeting HER2-positive cancer cells in vitro, which further enabled the detection of lymph node metastasis of breast cancer in vivo in mice. In addition, the pharmacokinetics of the resulting nanoprobes were intensively studied through both upconversion luminescence imaging and SPECT imaging for comparing with that of the mother particles. The results obtained through both approaches were well consistent and revealed that the surface conjugation of antibodies largely altered the pharmacokinetic behaviors and substantially prolonged the blood half-life of the underlying nanoparticles, which was never reported before.

In vivo biodistribution and toxicology of functionalized nano-graphene oxide in mice after oral and intraperitoneal administration.

Graphene oxide (GO) and its functionalized derivatives have attracted great attention in biomedicine in recent years. A number of groups including ours have studied the in vivo behaviors of functionalized nano-graphene after intravenous injection or inhalation, and uncovered the surface coating & size dependent biodistribution and toxicology profiles for this type of nanomaterials. However, the fate of GO derivatives in animals after oral feeding and intraperitoneal (i.p.) injection, which are two other major drug administration routes, remain unclear. Therefore, in this work, we sought to systematically investigate in vivo biodistribution and potential toxicity of as-made GO and a number of polyethylene glycol (PEG) functionalized GO derivatives with different sizes and surface coatings, after oral and intraperitoneal administration at high doses. It is found that (125)I labeled PEGylated GO derivatives show no obvious tissue uptake via oral administration, indicating the rather limited intestinal adsorption of those nanomaterials. In contrast, high accumulation of PEGyalted GO derivatives, but not as-made GO, in the reticuloendothelial (RES) system including liver and spleen is observed after i.p. injection. Further investigations based on histological examination of organ slices and hematological analysis discover that although GO and PEGylated GO derivatives would retain in the mouse body over a long period of time after i.p. injection, their toxicity to the treated animals is insignificant. Our work is an important fundamental study that offers a deeper understanding of in vivo behaviors and toxicology of functionalized nano-graphene in animals, depending on their different administration routes.

The influence of surface chemistry and size of nanoscale graphene oxide on photothermal therapy of cancer using ultra-low laser power.

Photothermal therapy as a physical treatment approach to destruct cancer has emerged as an alternative of currently used cancer therapies. Previously we have shown that polyethylene glycol (PEG) functionalized nano-graphene oxide (nGO-PEG) with strong optical absorption in the near-infrared (NIR) region was a powerful photothermal agent for in vivo cancer treatment. In this work, by using ultra-small reduced graphene oxide (nRGO) with non-covalent PEG coating, we study how sizes and surface chemistry affect the in vivo behaviors of graphene, and remarkably improve the performance of graphene-based in vivo photothermal cancer treatment. Owing to the enhanced NIR absorbance and highly efficient tumor passive targeting of nRGO-PEG, excellent in vivo treatment efficacy with 100% of tumor elimination is observed after intravenous injection of nRGO-PEG and the followed 808 nm laser irradiation, the power density (0.15 W/cm(2), 5 min) of which is an order of magnitude lower than that usually applied for in vivo tumor ablation using many other nanomaterials. All mice after treatment survive over a period of 100 days without a single death or any obvious sign of side effect. Our results highlight that both surface chemistry and sizes are critical to the in vivo performance of graphene, and show the promise of using optimized nano-graphene for ultra-effective photothermal treatment, which may potentially be combined with other therapeutic approaches to assist our fight against cancer.

In vivo NIR fluorescence imaging, biodistribution, and toxicology of photoluminescent carbon dots produced from carbon nanotubes and graphite.

Oxidization of carbon nanotubes by a mixed acid has been utilized as a standard method to functionalize carbon nanomaterials for years. Here, the products obtained from carbon nanotubes and graphite after a mixed-acid treatment are carefully studied. Nearly identical carbon dot (Cdot) products with diameters of 3-4 nm are produced using this approach from a variety of carbon starting materials, including single-walled carbon nanotubes, multiwalled carbon nanotubes, and graphite. These Cdots exhibit strong yellow fluorescence under UV irradiation and shifted emission peaks as the excitation wavelength is changed. In vivo fluorescence imaging with Cdots is then demonstrated in mouse experiments, by using varied excitation wavelengths including some in the near-infrared (NIR) region. Furthermore, in vivo biodistribution and toxicology of those Cdots in mice over different periods of time are studied; no noticeable signs of toxicity for Cdots to the treated animals are discovered. This work provides a facile method to synthesize Cdots as safe non-heavy-metal-containing fluorescent nanoprobes, promising for applications in biomedical imaging.

In vivo pharmacokinetics, long-term biodistribution, and toxicology of PEGylated graphene in mice.

Graphene has emerged as interesting nanomaterials with promising applications in a range of fields including biomedicine. In this work, for the first time we study the long-term in vivo biodistribution of (125)I-labeled nanographene sheets (NGS) functionalized with polyethylene glycol (PEG) and systematically examine the potential toxicity of graphene over time. Our results show that PEGylated NGS mainly accumulate in the reticuloendothelial system (RES) including liver and spleen after intravenous administration and can be gradually cleared, likely by both renal and fecal excretion. PEGylated NGS do not cause appreciable toxicity at our tested dose (20 mg/kg) to the treated mice in a period of 3 months as evidenced by blood biochemistry, hematological analysis, and histological examinations. Our work greatly encourages further studies of graphene for biomedical applications.

Increase of doxorubicin sensitivity for folate receptor positive cells when given as the prodrug N-(phenylacetyl) doxorubicin in combination with folate-conjugated PGA.

Folate receptor (FR) has been proposed as a promising target for tumor drug targeting. The aim of this study was to increase the chemo-sensitivity of FR-positive cells to doxorubicin by folate-directed enzyme prodrug therapy (FDEPT). Folate conjugated penicillin-G amidase was prepared and its ability to hydrolyze N-(phenylacetyl) doxorubicin was measured by HPLC. Fluorescence and confocal image analysis revealed that Folate-PGA can be specifically delivered into FR-positive HeLa and SKOV3 tumor cells. In vitro cytotoxity assays, IC50 was reduced with N-(phenylacetyl) doxorubicin versus doxorubicin for HeLa (3.1-fold reduction; p<0.001) and SKOV3 (3.3-fold reduction; p<0.001) when Folate-PGA was specifically bound to the cells. Complete activation was confirmed in HeLa and SKOV3 cells pretreated with free folic acid (1 mM), where the combination of N-(phenylacetyl) doxorubicin with Folate-PGA did not show any significant cell toxicity to the IC50 of doxorubicin. Pharmacokinetic clearance and biodistribution studies in vivo showed that 125I-Folate-PGA was cleared from blood within 24 h and had significantly higher tumor uptake compared to 125I-PGA (p<0.05). These results demonstrate that the FDEPT approach may be a potential promising strategy to improve chemotherapy-resistant cancers therapeutic ratio and warranted future studies.