Elsevier

Acta Biomaterialia

Volume 72, May 2018, Pages 256-265
Acta Biomaterialia

Full length article
Tumor-targeting CuS nanoparticles for multimodal imaging and guided photothermal therapy of lymph node metastasis

https://doi.org/10.1016/j.actbio.2018.03.035Get rights and content

Abstract

Precise diagnosis of lymph node metastasis to guide lymphadenectomy is highly important for gastric cancer therapy in clinics. Though surgical dissection of regional metastatic lymph nodes remains the only way for gastric cancer therapy, the extended dissection may cause unavoidable postoperative risk of complications. It is still lack of effective method enabling the accurate removal of metastatic gastric cancer cells in lymph nodes with minimum injuries to normal tissue. Herein, we report a new fluorescent copper sulfide (CuS) nanoparticle (RGD-CuS-Cy5.5) enabling both non-invasive multimodality imaging and targeting photothermal therapy (PTT) of metastatic gastric cancer cells in lymph nodes. We demonstrate that RGD-CuS-Cy5.5 can easily drain into sentinel lymph nodes (SLN) after injection into primary tumors, and selectively enter into metastatic gastric MNK45 tumor cells via αvβ3 integrin-mediated endocytosis. The resulting strong near-infrared (NIR) fluorescence and computed tomography (CT) contrast in metastatic SLN compared to normal SLN can precisely differentiate SLN metastasis of gastric cancers. Guided by the imaging, localized PTT with RGD-CuS-Cy5.5 is conducted upon irradiation with an 808 nm laser, resulting in complete removal of metastatic gastric tumor cells in SLN without obvious toxicity. Moreover, RGD-CuS-Cy5.5 can also allow for the rapid and non-invasive self-monitoring of PTT efficacy against metastatic SLNs in living mice. This study highlights the potential of using RGD-CuS-Cy5.5 for imaging-guided and targeting PTT of SLN metastasis in vivo, which may be applicable for the metastatic gastric cancer therapy in clinics.

Statement of Significance

RGD-CuS-Cy5.5 nanoparticles possess NIR fluorescence and CT signals for in vivo bimodality imaging of lymph node metastasis. Strong photothermal property under irradiation at 808 nm for efficient PTT. Easy drain into sentinel lymph nodes and selective enter metastatic gastric cancer cells via αvβ3 integrin-mediated endocytosis. Rapid and non-invasive monitoring of therapeutic efficacy against lymph node metastasis.

Introduction

Gastric cancer is one of the most common malignancy with the third leading cause of cancer death worldwide [1], [2]. It is found that gastric cancer has a high incidence of metastasis to lymph nodes when it is discovered, with about 85% of all gastric cancer patients diagnosed with lymph node metastasis in clinics. This makes the five-year survival rate generally less than 10% [3]. Lymph node metastasis has been recognized as one of the most important independent prognostic factors for gastric cancer patients [4]. It is vital to differentiate the metastatic lymph nodes from non-metastatic ones in patients, which can guide the following therapy to stop further metastasis of cancer cells. Until now, surgical dissection to remove both the primary gastric cancer and metastatic lymph nodes is still the only way for gastric cancer therapy in clinics. However, extended dissection of lymph nodes by surgery usually induces the postoperative risk of complications, including lymphorrhea, pancreatic fistula and abdominal abscess, leading to prolonged inflammation, increased death risk, and reduced long-term survival rate [5], [6], [7], [8], [9]. Thus, the development of new therapeutic methods enabling the accurate removal of metastatic gastric cancer cells in lymph nodes with minimum injuries to normal tissue is highly demanded.

Photothermal therapy (PTT) is an emerging noninvasive and effective therapeutic method that has attracted tremendous attentions in the past decades. PTT involves the use of near-infrared (NIR) light absorbing agents (known as photothermal agents), which can generate heat upon irradiation by an NIR laser, leading to elevated local tumor temperature that can cause irreversible tumor cell death. Compared to the traditional cancer therapies (i.e., surgery, chemotherapy, radiotherapy), PTT has advantages of being spatially and temporally controllable to achieve localized therapy, avoiding unnecessary damage to normal tissues. Moreover, recent evidences have also uncovered that PTT can also stimulate immunological effects to destroy the remaining cancer cells, preventing further metastasis [10], [11], [12], [13]. Those advantages have prompted people to investigate PTT as an alternative method to surgery for the treatment of lymph node metastasis. Many kinds of photothermal nanomaterials, including gold nanoparticles [14], [15], [16], [17], [18], [19], carbon nanotubes, graphene [20], [21], [22], transition metal oxide/sulfide nanoparticles [23], [24], [25], and organic nanoparticles [26], [27], [28], [29], [30] have been developed as PTT agents to combat cancer metastasis in lymph nodes. For instance, semiconductor copper sulfide (CuS) nanoparticles that possess strong NIR absorbance above 800 nm have shown high photothermal properties enabling both photoacoustic imaging and PTT of subcutaneous tumors as well as lymph node metastasis. Moreover, radionuclides such as 64Cu or 131I could be further doped to form radioactive CuS nanoparticles, allowing for positron emission tomography (PET) imaging and combined PTT/radiotherapy of cancers [31], [32], [33], [34], [35], [36], [37]. Despite the encouraging results, the selective entry into tumor cells, especially metastatic tumor cells in lymph nodes, and specific ablation of tumors by these CuS nanoparticles is still limited due to the lack of tumor targeting ability. In addition, they were generally non-fluorescent, which limited their wide applications for rapid and real-time fluorescence imaging and mapping of lymph node metastasis [38], [24], [39], [40], [41], [42].

Herein, we develop a fluorescent CuS nanoparticle (denoted as RGD-CuS-Cy5.5) integrating a tumor targeting ligand cRGD [43], [44], [45], [46], [47] and an NIR organic dye Cy5.5 for combined fluorescence/CT dual modality imaging and selective PTT of gastric cancer metastasis in sentinel lymph nodes (SLN). We show that RGD-CuS-Cy5.5 can readily drain into SLN and selectively enter into MNK45 gastric tumor cells via αvβ3 receptor-mediated endocytosis, offering strong NIR fluorescence at 695 nm and remarkable CT contrast indicative of SLN metastasis. Guided by the imaging, localized PTT of SLN metastasis in gastric tumors bearing mice is then performed to induce efficient tumor cell death, resulting in complete removal of tumors in SLN without obvious toxicity. This study demonstrates the application of gastric cancer targeting CuS nanoparticles for both multimodality mapping and therapy of lymph node metastasis, which may provide an alternative method for the treatment of gastric cancer lymph node metastasis amenable for clinical applications.

Section snippets

General materials and methods

All chemicals and biological reagents were purchased from commercial suppliers and used without further purification. CuCl2·2H2O and thioacetamide were purchased from Aladdin Reagent Corporation (Shanghai, China). SH-PEG2000-COOH was purchased from JenKem Technology Co., Ltd. NH2-cRGD was purchased from GL Biochem Ltd (Shanghai, China). Calcein AM, propidium iodide (PI), Lyso-Tracker Green, and Hoechst 33,342 were obtained from KeyGen Biotech. Co. Ltd. (Nanjing, China).

The fluorescence spectra

Design of fluorescent tumor targeting CuS nanoparticles

Fig. 1a showed the design of tumor targeting CuS nanoparticles (RGD-CuS-Cy5.5), consisting of a polyethylene glycol (PEG2000) functionalized CuS nanoparticle, a tumor targeting ligand cRGD and an NIR fluorophore Cy5.5. CuS nanoparticles were chosen as the PTT agents because of the small size, low systemic toxicity and high photothermal properties at NIR region [33], [34]. Moreover, CuS nanoparticles could also be used as efficient CT imaging contrast agents due to the strong ability to absorb

Conclusions

In conclusion, we have reported the development of fluorescent RGD-CuS-Cy5.5 nanoparticles for multimodal fluorescence/CT imaging and targeting PTT of SLN metastasis of gastric tumor cells in living mice. We have demonstrated that RGD-CuS-Cy5.5 possessed strong NIR absorbance as well as high NIR fluorescence and X-ray attenuate property, offering a remarkable photothermal property for effective PTT and bimodal fluorescence/CT signals for in vivo mapping of SLN metastasis. Moreover, the covalent

Acknowledgements

We would like to acknowledge Prof. Yin Ding for her help with MRI acquirement. Financial supports from the National Natural Science Foundation of China (81671751, 81371516, 81501441, 81601463, 21632008, 21775071), Foundation of National Health and Family Planning Commission of China (W201306), Social Development Foundation of Jiangsu Province (BE2015605), the Natural Science Foundation of Jiangsu Province (BK20150109, BK20150567, BK20171118), Jiangsu Province Health and Family Planning

References (58)

  • F.L. Greene et al.

    The staging of cancer: a retrospective and prospective appraisal

    Ca-Cancer J. Clin.

    (2008)
  • G.B. Doglietto et al.

    Lymphadenectomy for gastric cancer: still a matter of debate?

    Ann. Ital. Chir.

    (2012)
  • G.H. Sakorafas et al.

    Sentinel lymph node biopsy in breast cancer: what a physician should know, a decade after its introduction in clinical practice

    Eur. J. Cancer Care

    (2007)
  • M. Sasako et al.

    D2 lymphadenectomy alone or with para-aortic nodal dissection for gastric cancer

    New Engl. J. Med.

    (2008)
  • T. Kubota et al.

    Prognostic significance of complications after curative surgery for gastric cancer

    Ann. Surg. Oncol.

    (2014)
  • V. Shanmugam et al.

    Near-infrared light-responsive nanomaterials in cancer therapeutics

    Chem. Soc. Rev.

    (2014)
  • L.L. Zou et al.

    Current approaches of photothermal therapy in treating cancer metastasis with nanotherapeutics

    Theranostics

    (2016)
  • L. Cheng et al.

    Functional nanomaterials for phototherapies of cancer

    Chem. Rev.

    (2014)
  • M.C. Daniel et al.

    Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology

    Chem. Rev.

    (2004)
  • J.Y. Chen et al.

    Immuno gold nanocages with tailored optical properties for targeted photothermal destruction of cancer cells

    Nano Lett.

    (2007)
  • L. Tong et al.

    Gold nanorods as contrast agents for biological imaging: optical properties, surface conjugation and photothermal effects

    Photochem. Photobiol.

    (2009)
  • M. Samim et al.

    Synthesis and characterization of gold nanorods and their application for photothermal cell damage

    Int. J. Nanomed.

    (2011)
  • M. Chen et al.

    Core-Shell pd@au nanoplates as theranostic agents for in vivo photoacoustic imaging, CT imaging, and photothermal therapy

    Adv. Mater.

    (2014)
  • S.B. Lee et al.

    Combined positron emission tomography and cerenkov luminescence imaging of sentinel lymph nodes using pegylated radionuclide-embedded gold nanoparticles

    Small

    (2016)
  • K. Yang et al.

    Graphene in mice: ultrahigh in vivo tumor uptake and efficient photothermal therapy

    Nano Lett.

    (2010)
  • K. Yang et al.

    Nano-graphene in biomedicine: theranostic applications

    Chem. Soc. Rev.

    (2013)
  • D. Bitounis et al.

    Prospects and challenges of graphene in biomedical applications

    Adv. Mater.

    (2013)
  • Q. Tian et al.

    Hydrophilic flower-like cus superstructures as an efficient 980 nm laser-driven photothermal agent for ablation of cancer cells

    Adv. Mater.

    (2011)
  • Q.W. Tian et al.

    Sub-10 nm Fe3O4@Cu2-xS core-shell nanoparticles for dual-modal imaging and photothermal therapy

    J. Am. Chem. Soc.

    (2013)
  • Cited by (102)

    • Nanotherapies from an oncologist doctor's view

      2023, Smart Materials in Medicine
    View all citing articles on Scopus
    View full text