Xiao-Jiao Du

Tailor-Made Dual pH-Sensitive Polymer–Doxorubicin Nanoparticles for Efficient Anticancer Drug Delivery

Efficient delivery of therapeutics into tumor cells to increase the intracellular drug concentration is a major challenge for cancer therapy due to drug resistance and inefficient cellular uptake. Herein, we have designed a tailor-made dual pH-sensitive polymer-drug conjugate nanoparticulate system to overcome the challenges. The nanoparticle is capable of reversing its surface charge from negative to positive at tumor extracellular pH (∼6.8) to facilitate cell internalization. Subsequently, the significantly increased acidity in subcellular compartments such as the endosome (∼5.0) further promotes doxorubicin release from the endocytosed drug carriers. This dual pH-sensitive nanoparticle has showed enhanced cytotoxicity in drug-resistant cancer stem cells, indicating its great potential for cancer therapy.

Surface charge switchable nanoparticles based on zwitterionic polymer for enhanced drug delivery to tumor.

Two faced nanoparticles: A zwitterionic polymer-based nanoparticle with response to tumor acidity is developed for enhanced drug delivery to tumors. The nanoparticles are neutrally charged at physiological conditions and show prolonged circulation time; after leaking into tumor sites, in the acidic extracellular tumor environment (pH(e) ), nanoparticles are activated and become positively charged and are therefore efficiently taken up by tumor cells, leading to enhanced therapeutic effects in cancer treatment.

Co-delivery of all-trans-retinoic acid and doxorubicin for cancer therapy with synergistic inhibition of cancer stem cells.

Combination treatment through simultaneous delivery of two or more drugs with nanoparticles has been demonstrated to be an elegant and efficient approach for cancer therapy. Herein, we employ a combination therapy for eliminating both the bulk tumor cells and the rare cancer stem cells (CSCs) that have a high self-renewal capacity and play a critical role in cancer treatment failure. All-trans-retinoic acid (ATRA), a powerful differentiation agent of cancer stem cells and the clinically widely used chemotherapy agent doxorubicin (DOX) are simultaneously encapsulated in the same nanoparticle by a single emulsion method. It is demonstrated that ATRA and DOX simultaneous delivery-based therapy can efficiently deliver the drugs to both non-CSCs and CSCs to differentiate and kill the cancer cells. Differentiation of CSCs into non-CSCs can reduce their self-renewal capacity and increase their sensitivity to chemotherapy; with the combined therapy, a significantly improved anti-cancer effect is demonstrated. Administration of this combinational drug delivery system can markedly augment the enrichment of drugs both in tumor tissues and cancer stem cells, prodigiously enhancing the suppression of tumor growth while reduce the incidence of CSC in a synergistic manner.

Combination therapy with epigenetic-targeted and chemotherapeutic drugs delivered by nanoparticles to enhance the chemotherapy response and overcome resistance by breast cancer stem cells

Aberrant DNA hypermethylation is critical in the regulation of renewal and maintenance of cancer stem cells (CSCs), which represent targets for carcinogenic initiation by chemical and environmental agents. The administration of decitabine (DAC), which is a DNA hypermethylation inhibitor, is an attractive approach to enhancing the chemotherapeutic response and overcoming drug resistance by CSCs. In this study, we investigated whether low-dose DAC encapsulated in nanoparticles could be used to sensitize bulk breast cancer cells and CSCs to chemotherapy. In vitro studies revealed that treatment with nanoparticles loaded with low-dose DAC (NPDAC) combined with nanoparticles loaded with doxorubicin (NPDOX) better reduced the proportion of CSCs with high aldehyde dehydrogenase activity (ALDH(hi)) in the mammospheres of MDA-MB-231 cells, and better overcame the drug resistance by ALDH(hi) cells. Subsequently, systemic delivery of NPDAC significantly down-regulated the expression of DNMT1 and DNMT3b in a MB-MDA-231 xenograft murine model and induced increased caspase-9 expression, which contributed to the increased sensitivity of the bulk cancer cells and CSCs to NPDOX treatment. Importantly, the combined treatment of NPDAC and NPDOX resulted in the lowest proportion of ALDH(hi) CSCs and the highest proportion of apoptotic tumor cells, and the best tumor suppressive effects in inhibiting breast cancer growth.

Restoring anti-tumor functions of T cells via nanoparticle-mediated immune checkpoint modulation.

The core purpose of cancer immunotherapy is the sustained activation and expansion of the tumor specific T cells, especially tumor-infiltrating cytotoxic T lymphocytes (CTLs). Currently, one of the main foci of immunotherapy involving nano-sized carriers is on cancer vaccines and the role of professional antigen presenting cells, such as dendritic cells (DCs) and other phagocytic immune cells. Besides the idea that cancer vaccines promote T cell immune responses, targeting immune inhibitory pathways with nanoparticle delivered regulatory agents such as small interfering RNA (siRNA) to the difficultly-transfected tumor-infiltrating T cells may provide more information on the utility of nanoparticle-mediated cancer immunotherapy. In this study, we constructed nanoparticles to deliver cytotoxic T lymphocyte-associated molecule-4 (CTLA-4)-siRNA (NPsiCTLA-4) and showed the ability of this siRNA delivery system to enter T cells both in vitro and in vivo. Furthermore, T cell activation and proliferation were enhanced after NPsiCTLA-4 treatment in vitro. The ability of direct regulation of T cells of this CTLA-4 delivery system was assessed in a mouse model bearing B16 melanoma. Our results demonstrated that this nanoparticle delivery system was able to deliver CTLA-4-siRNA into both CD4(+) and CD8(+) T cell subsets at tumor sites and significantly increased the percentage of anti-tumor CD8(+) T cells, while it decreased the ratio of inhibitory T regulatory cells (Tregs) among tumor infiltrating lymphocytes (TILs), resulting in augmented activation and anti-tumor immune responses of the tumor-infiltrating T cells. These data support the use of potent nanoparticle-based cancer immunotherapy for melanoma.

Synthetic Lethal Therapy for KRAS Mutant Non-small-cell Lung Carcinoma with Nanoparticle-mediated CDK4 siRNA Delivery

The KRAS mutation is present in ~20% of lung cancers and has not yet been effectively targeted for therapy. This mutation is associated with a poor prognosis in non-small-cell lung carcinomas (NSCLCs) and confers resistance to standard anticancer treatment drugs, including epidermal growth factor receptor tyrosine kinase inhibitors. In this study, we exploited a new therapeutic strategy based on the synthetic lethal interaction between cyclin-dependent kinase 4 (CDK4) downregulation and the KRAS mutation to deliver micellar nanoparticles (MNPs) containing small interfering RNA targeting CDK4 (MNPsiCDK4) for treatment in NSCLCs harboring the oncogenic KRAS mutation. Following MNPsiCDK4 administration, CDK4 expression was decreased, accompanied by inhibited cell proliferation, specifically in KRAS mutant NSCLCs. However, this intervention was harmless to normal KRAS wild-type cells, confirming the proposed mechanism of synthetic lethality. Moreover, systemic delivery of MNPsiCDK4 significantly inhibited tumor growth in an A549 NSCLC xenograft murine model, with depressed expression of CDK4 and mutational KRAS status, suggesting the therapeutic promise of MNPsiCDK4 delivery in KRAS mutant NSCLCs via a synthetic lethal interaction between KRAS and CDK4.

Differential anticancer drug delivery with a nanogel sensitive to bacteria-accumulated tumor artificial environment.

Differential anticancer drug delivery that selectively releases a drug within a tumor represents an ideal cancer therapy strategy. Herein, we report differential drug delivery to the tumor through the fabrication of a special bacteria-accumulated tumor environment that responds to bacteria-sensitive triple-layered nanogel (TLN). We demonstrate that the attenuated bacteria SBY1 selectively accumulated in tumors and were rapidly cleared from normal tissues after intravenous administration, leading to a unique bacteria-accumulated tumor environment. Subsequent administrated doxorubicin-loaded TLN (TLND) was thus selectively degraded in the bacteria-accumulated tumor environment after its accumulation in tumors, triggering differential doxorubicin release and selectively killing tumor cells. This concept can be extended and improved by using other factors secreted by bacteria or materials to fabricate a unique tumor environment for differential drug delivery, showing potential applications in drug delivery.

Delivery of bortezomib with nanoparticles for basal-like triple-negative breast cancer therapy.

Basal-like triple negative breast cancer (TNBC) has received particular clinical interest due to its high frequency, poor baseline prognosis and lack of effective clinical therapy. Bortezomib, which was the first proteasome inhibitor approved for the treatment of multiple myeloma, has been proven to be worth investigating for this subtype of breast cancer. In our study, the amphiphilic copolymer poly(ethylene glycol)-block-poly(d,l-lactide) (PEG-b-PLA) was utilized as an excellent delivery carrier of bortezomib (BTZ) to overcome its clinical limitations including low water solubility and unstable properties. Bortezomib encapsulated nanoparticles (NPBTZ) can efficiently deliver the drug into both CSCs (cancer stem cells) and non-CSCs, resulting in proliferation inhibition and apoptosis induction. Remarkably, NPBTZ can more effectively affect the stemness of CSCs compared with free BTZ. Administration of this drug delivery system can markedly prolong the bortezomib circulation half-life and augment the enrichment of drugs in tumor tissue, then enhance the suppression of tumor growth, suggesting the therapeutic promise of NPBTZ delivery in basal-like TNBC therapy.

Cationic Lipid-Assisted Polymeric Nanoparticle Mediated GATA2 siRNA Delivery for Synthetic Lethal Therapy of KRAS Mutant Non-Small-Cell Lung Carcinoma

Synthetic lethal interaction provides a conceptual framework for the development of wiser cancer therapeutics. In this study, we exploited a therapeutic strategy based on the interaction between GATA binding protein 2 (GATA2) downregulation and the KRAS mutation status by delivering small interfering RNA targeting GATA2 (siGATA2) with cationic lipid-assisted polymeric nanoparticles for treatment of non-small-cell lung carcinoma (NSCLC) harboring oncogenic KRAS mutations. Nanoparticles carrying siGATA2 (NPsiGATA2) were effectively taken up by NSCLC cells and resulted in targeted gene suppression. NPsiGATA2 selectively inhibited cell proliferation and induced cell apoptosis in KRAS mutant NSCLC cells. However, this intervention was harmless to normal KRAS wild-type NSCLC cells and HL7702 hepatocytes, confirming the advantage of synthetic lethality-based therapy. Moreover, systemic delivery of NPsiGATA2 significantly inhibited tumor growth in the KRAS mutant A549 NSCLC xenograft murine model, suggesting the therapeutic promise of NPsiGATA2 delivery in KRAS mutant NSCLC therapy.

Macrophage-Specific in Vivo Gene Editing Using Cationic Lipid-Assisted Polymeric Nanoparticles

The CRISPR/Cas9 gene editing technology holds promise for the treatment of multiple diseases. However, the inability to perform specific gene editing in targeted tissues and cells, which may cause off-target effects, is one of the critical bottlenecks for therapeutic application of CRISPR/Cas9. Herein, macrophage-specific promoter-driven Cas9 expression plasmids (pM458 and pM330) were constructed and encapsulated in cationic lipid-assisted PEG-b-PLGA nanoparticles (CLAN). The obtained nanoparticles encapsulating the CRISPR/Cas9 plasmids were able to specifically express Cas9 in macrophages as well as their precursor monocytes both in vitro and in vivo. More importantly, after further encoding a guide RNA targeting Ntn1 (sgNtn1) into the plasmid, the resultant CLANpM330/sgNtn1 successfully disrupted the Ntn1 gene in macrophages and their precursor monocytes in vivo, which reduced expression of netrin-1 (encoded by Ntn1) and subsequently improved type 2 diabetes (T2D) symptoms. Meanwhile, the Ntn1 gene was not disrupted in other cells due to specific expression of Cas9 by the CD68 promoter. This strategy provides alternative avenues for specific in vivo gene editing with the CRISPR/Cas9 system.