Rational Design of a Robust Antibody-like Small-Molecule Inhibitor Nanoplatform for Enhanced Photoimmunotherapy.

Immune checkpoint blockade of the programmed cell death-ligand 1/programmed cell death-1 (PD-L1/PD-1) pathway via an antibody is a potent strategy for T cell remodeling. Nevertheless, the potency of the antibody is partly compromised by its high price, instability, risk of autoimmune disease, and so forth. Small-molecule inhibitors are interesting alternatives to antibodies. However, tumor-specific delivery of small-molecule inhibitors to the target site for boosting the interruption of the PD-L1/PD-1 pathway is rarely reported. Herein, we designed a tumor-specific delivery nanoplatform that could efficiently deliver the small-molecule inhibitor to the precise target site, greatly enhancing the blocking effect of the PD-L1/PD-1 pathway. Hyaluronic acid (HA) was conjugated with chlorin e6 (Ce6), resulting in a HA-Ce6 conjugate (HC). The nanoplatform was constructed by the HC micelles with the encapsulation of small-molecule inhibitor, BMS 202 (BMS), to form BMS/HC micelles. The target property of HA, combined with the hyaluronidase-induced degradation of HA in the tumor site, enables the as-prepared micelles with tumor-specific delivery of BMS for blocking the PD-L1/PD-1 pathway. With cooperative treatment with the photosensitizer Ce6, the present therapeutic nanoplatform demonstrated excellent photoimmunotherapy for tumor regression in distant tumors and lung metastasis. This strategy of tumor-specific delivery of small-molecule inhibitors provides an effective pathway to strengthen the blocking efficacy of PD-L1/PD-1 on effective photoimmunotherapy.

Task-Specific Design of Immune-Augmented Nanoplatform to Enable High-Efficiency Tumor Immunotherapy.

Potentiating systemic immunity against breast cancer is in the most urgent demand as breast cancer is less sensitive to immune checkpoint blockade. Although phototherapy and some chemotherapy can trigger immunogenic cell death (ICD) for T cell-mediated antitumor immune response, their immunotherapy efficacy is severely restricted by insufficient phototherapeutic capability and severe multidrug resistance (MDR). Inspired by both the hypersensitivity to phototherapy and the key role of MDR for mitochondria, a rationally engineered immunity amplifier via mitochondria-targeted photochemotherapeutic nanoparticles was, for the first time, achieved to fight against low-immunogenic breast cancer without additional immune agents. The newly synthesized task-specific mitochondria-targeted IR780 derivative (T780) was integrated with chemotherapeutic doxorubicin (DOX) to form multifunctional nanoparticles via an assembling strategy along with bovine serum albumin (BSA) as a biomimetic corona (BSA@T780/DOX NPs). The in situ enhancement in both phototherapy and MDR reversal by targeting mitochondria with BSA@T780/DOX NPs boosted highly efficient ICD toward excellent antitumor immune response. The newly developed strategy not only eradicated the primary tumor but also eliminated the bilateral tumors efficiently, as well as preventing metastasis and postsurgical recurrence, demonstrating great interest for fighting against low-immunogenic breast cancer.

Cold to Hot: Rational Design of a Minimalist Multifunctional Photo-immunotherapy Nanoplatform toward Boosting Immunotherapy Capability.

The concept of integrating immunogenic cell death (ICD) with tailoring the immunosuppressive tumor microenvironment (TME) is promising for immunotherapy. Photothermal therapy (PTT) could efficiently induce ICD, while an indoleamine 2,3-dioxygenase (IDO) inhibitor could convert the "cold" TME. Therefore, combination of PTT and the IDO inhibitor is an attractive approach for immunotherapy. Unfortunately, combination of PTT and the IDO inhibitor for tumor therapy is rarely reported. Herein, organic photothermal agent IR820 and IDO inhibitor 1-methyl-tryptophan (1MT) were, for the first time, designed to be an all-rolled-into-one molecule nanoplatform via a molecular engineering strategy. The designed IR820-1MT molecule could self-assemble into nanoparticles with remarkably high dual-therapeutic agent loading (88.8 wt %). Importantly, poor water solubility of 1MT and inadequate targeting and short lifetime of IR820 were all well solved within as-prepared IR820-1MT nanoparticles. The laser-triggered IR820-1MT nanoparticles remarkably enhanced accumulation of cytotoxic T cells, helper T cells, and memory T cells and simultaneously suppressed a proportion of regulatory T cells, resulting in excellent immunotherapy against tumor metastasis and recurrence. Our molecular engineering strategy provides a promising alternative option for design of a robust immunotherapy weapon against tumor metastasis and recurrence.

Rational Design of IR820- and Ce6-Based Versatile Micelle for Single NIR Laser-Induced Imaging and Dual-Modal Phototherapy.

Phototherapy as a promising cancer diagnostic and therapeutic strategy has aroused extensive attention. However, single-wavelength near-infrared (NIR) light-triggered combinational treatment of photothermal therapy (PTT) and photodynamic therapy (PDT) is still a great challenge. Herein, a multifunctional micelle activated by a single-wavelength laser for simultaneous PTT and PDT as well as fluorescence imaging is developed. Briefly, new indocyanine green (IR820) is conjugated to d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) via the linker 6-aminocaproic acid, and then, chlorin e6 (Ce6) is encapsulated into the micelles formed by TPGS-IR820 conjugates to fabricate TPGS-IR820/Ce6 micelles. As the well-designed TPGS-IR820 conjugate shares a similar peak absorption wavelength with Ce6, this micelle can be applied with a single NIR laser (660 nm). The stable micelles exhibit excellent photothermal conversion efficiency in vitro and in vivo as well as high singlet oxygen generation capacity in tumor cells. After efficient cellular internalization, the as-prepared micelles display outstanding anticancer activity upon single NIR laser irradiation in vitro and in vivo. Furthermore, TPGS-IR820/Ce6 micelles show negligible systemic toxicity. The highly safe and effective TPGS-IR820/Ce6 micelles can offer an innovative strategy to construct single NIR light-induced PTT and PDT combined phototherapy nanoplatforms via suitable modification of organic phototherapeutic agents.

Co-chaperone HSJ1a dually regulates the proteasomal degradation of ataxin-3.

Homo sapiens J domain protein (HSJ1) is a J-domain containing co-chaperone that is known to stimulate ATPase activity of HSP70 chaperone, while it also harbors two ubiquitin (Ub)-interacting motifs (UIMs) that may bind with ubiquitinated substrates and potentially function in protein degradation. We studied the effects of HSJ1a on the protein levels of both normal and the disease--related polyQ-expanded forms of ataxin-3 (Atx3) in cells. The results demonstrate that the N-terminal J-domain and the C-terminal UIM domain of HSJ1a exert opposite functions in regulating the protein level of cellular overexpressed Atx3. This dual regulation is dependent on the binding of the J-domain with HSP70, and the UIM domain with polyUb chains. The J-domain down-regulates the protein level of Atx3 through HSP70 mediated proteasomal degradation, while the UIM domain may alleviate this process via maintaining the ubiquitinated Atx3. We propose that co-chaperone HSJ1a orchestrates the balance of substrates in stressed cells in a Yin-Yang manner.

Arsenic trioxide controls the fate of the PML-RARalpha oncoprotein by directly binding PML.

Arsenic, an ancient drug used in traditional Chinese medicine, has attracted worldwide interest because it shows substantial anticancer activity in patients with acute promyelocytic leukemia (APL). Arsenic trioxide (As2O3) exerts its therapeutic effect by promoting degradation of an oncogenic protein that drives the growth of APL cells, PML-RARalpha (a fusion protein containing sequences from the PML zinc finger protein and retinoic acid receptor alpha). PML and PML-RARalpha degradation is triggered by their SUMOylation, but the mechanism by which As2O3 induces this posttranslational modification is unclear. Here we show that arsenic binds directly to cysteine residues in zinc fingers located within the RBCC domain of PML-RARalpha and PML. Arsenic binding induces PML oligomerization, which increases its interaction with the small ubiquitin-like protein modifier (SUMO)-conjugating enzyme UBC9, resulting in enhanced SUMOylation and degradation. The identification of PML as a direct target of As2O3 provides new insights into the drug's mechanism of action and its specificity for APL.