Dihydroartemisinin-driven TOM70 inhibition leads to mitochondrial destabilization to induce pyroptosis against lung cancer.

Enhancement of malignant cell immunogenicity to relieve immunosuppression of lung cancer microenvironment is essential in lung cancer treatment. In previous study, we have demonstrated that dihydroartemisinin (DHA), a kind of phytopharmaceutical, is effective in inhibiting lung cancer cells and boosting their immunogenicity, while the initial target of DHA's intracellular action is poorly understood. The present in-depth analysis aims to reveal the influence of DHA on the highly expressed TOM70 in the mitochondrial membrane of lung cancer. The affinity of DHA and TOM70 was analyzed by microscale thermophoresis (MST), pronase stability, and thermal stability. The functions and underlying mechanism were investigated using western blots, qRT-PCR, flow cytometry, and rescue experiments. TOM70 inhibition resulted in mtDNA damage and translocation to the cytoplasm from mitochondria due to the disruption of mitochondrial homeostasis. Further ex and in vivo findings also showed that the cGAS/STING/NLRP3 signaling pathway was activated by mtDNA and thereby malignant cells underwent pyroptosis, leading to enhanced immunogenicity of lung cancer cells in the presence of DHA. Nevertheless, DHA-induced mtDNA translocation and cGAS/STING/NLRP3 mobilization were synchronously attenuated when TOM70 was replenished. Finally, DHA was demonstrated to possess potent anti-lung cancer efficacy in vitro and in vivo. Taken together, these data confirm that TOM70 is an important target for DHA to disturb mitochondria homeostasis, which further activates STING and arouses pyroptosis to strengthen immunogenicity against lung cancer thereupon. The present study provides vital clues for phytomedicine-mediated anti-tumor therapy.

Anti-lung cancer synergy of low-dose doxorubicin and PD-L1 blocker co-delivered via mild photothermia-responsive black phosphorus.

We have previously identified a latent interaction mechanism between non-small cell lung cancer cells (NSCLCC) and their associated macrophages (TAM) mediated by mutual paracrine activation of the HMGB1/RAGE/NF-κB signaling. Activation of this mechanism results in TAM stimulation and PD-L1 upregulation in the NSCLCC. In the present work, we found that free DOX at a low concentration that does not cause DNA damage could activate the HMGB1/RAGE/NF-κB/PD-L1 pathway byinducing oxidative stress. It was thus proposed that a combination of low-dose DOX and a PD-L1 blocker delivered in the NSCLC tumor would achieve synergistic TAM stimulation and thereby synergetic anti-tumor potency. To prove this idea, DOX and BMS-202 (a PD-L1 blocker) were loaded to black phosphorus (BP) nanoparticles after dosage titration to yield the BMS-202/DOX@BP composites that rapidly disintegrated and released drug cargo upon mild photothermal heating at 40 °C. In vitro experiments then demonstrated that low-dose DOX and BMS-202 delivered via BMS-202/DOX@BP under mild photothermia displayed enhanced tumor cell toxicity with a potent synergism only in the presence of TAM. This enhanced synergism was due to an anti-tumor M1-like TAM phenotype that was synergistically induced by low dose DOX plus BMS-202 only in the presence of the tumor cells, indicating the damaged tumor cells to be the cardinal contributor to the M1-like TAM stimulation. In vivo, BMS-202/DOX@BP under mild photothermia exhibited targeted delivery to NSCLC graft tumors in mice and synergistic anti-tumor efficacy of delivered DOX and BMS-202. In conclusion, low-dose DOX in combination with a PD-L1 blocker is an effective strategy to turn TAM against their host tumor cells exploiting the HMGB1/RAGE/NF-κB/PD-L1 pathway. The synergetic actions involved highlight the value of TAM and the significance of modulating tumor cell-TAM cross-talk in tumor therapy. Photothermia-responsive BP provides an efficient platform to translate this strategy into targeted, efficacious tumor therapy.

PD-L1 blockade TAM-dependently potentiates mild photothermal therapy against triple-negative breast cancer.

The present work was an endeavor to shed light on how mild photothermia possibly synergizes with immune checkpoint inhibition for tumor therapy. We established mild photothermal heating protocols to generate temperatures of 43 °C and 45 °C in both in vitro and in vivo mouse 4T1 triple-negative breast cancer (TNBC) models using polyglycerol-coated carbon nanohorns (CNH-PG) and 808 nm laser irradiation. Next, we found that 1) CNH-PG-mediated mild photothermia (CNH-PG-mPT) significantly increased expression of the immune checkpoint PD-L1 and type-1 macrophage (M1) markers in the TNBC tumors; 2) CNH-PG-mPT had a lower level of anti-tumor efficacy which was markedly potentiated by BMS-1, a PD-L1 blocker. These observations prompted us to explore the synergetic mechanisms of CNH-PG-mPT and BMS-1 in the context of tumor cell-macrophage interactions mediated by PD-L1 since tumor-associated macrophages (TAMs) are a major source of PD-L1 expression in tumors. In vitro, the study then identified two dimensions where BMS-1 potentiated CNH-PG-mPT. First, CNH-PG-mPT induced PD-L1 upregulation in the tumor cells and showed a low level of cytotoxicity which was potentiated by BMS-1. Second, CNH-PG-mPT skewed TAMs towards an M1-like anti-tumor phenotype with upregulated PD-L1, and BMS-1 bolstered the M1-like phenotype. The synergistic effects of BMS-1 and CNH-PG-mPT both on the tumor cells and TAMs were more pronounced when the two cell populations were in co-culture. Further in vivo study confirmed PD-L1 upregulation both in tumor cells and TAMs in the TNBC tumors following treatment of CNH-PG-mPT. Significantly, TAMs depletion largely abolished the anti-TNBC efficacy of CNH-PG-mPT alone and in synergy with BMS-1. Collectively, our findings reveal PD-L1 upregulation to be a key response of TNBC to mild photothermal stress, which plays a pro-survival role in the tumor cells while also acting as a brake on the M1-like activation of the TAMs. Blockade of mPT­induced PD­L1 achieves synergistic anti-TNBC efficacy by taking the intrinsic survival edge off the tumor cells on one hand and taking the brakes off the M1-like TAMs on the other. Our findings reveal a novel way (i.e. mild thermia plus PD-L1 blockade) to modulate the TAMs-tumor cell interaction to instigate a mutiny of the TAMs against their host tumor cells.

A Dihydroartemisinin-Loaded Nanoreactor Motivates Anti-Cancer Immunotherapy by Synergy-Induced Ferroptosis to Activate Cgas/STING for Reprogramming of Macrophage.

Infiltration of tumor-associated macrophages (TAM) characterized by an M2 phenotype is an overriding feature in malignant tumors. Reprogramming TAM is the most cutting-edge strategy for cancer therapy. In the present study, an iron-based metal-organic framework (MOF) nanoreactor loaded with dihydroartemisinin (DHA) is developed, which provides high uptake by TAM and retains their viability, thus effectively addressing the inefficiency of the DHA at low concentrations. Impressively, DHA@MIL-101 can selectively accumulate in tumor tissues and remodel TAM to the M1 phenotype. The results of RNA sequencing further suggest that this nanoreactor may regulate ferroptosis, a DNA damage signaling pathway in TAM. Indeed, the outcomes confirm that DHA@MIL-101 triggers ferroptosis in TAM. In addition, the findings reveal that DNA damage induced by DHA nanoreactors activates the intracellular cGAS sensor, resulting in the binding of STING to IRF3 and thereby up-regulating the immunogenicity. In contrast, blocking ferroptosis impairs DHA@MIL-101-induced activation of STING signaling and phenotypic remodeling. Finally, it is shown that DHA nanoreactors deploy anti-tumor immunotherapy through ferroptosis-mediated TAM reprogramming. Taken together, immune efficacy is achieved through TAM's remodeling by delivering DHA and iron ions into TAM using nanoreactors, providing a novel approach for combining phytopharmaceuticals with nanocarriers to regulate the immune microenvironment.

Tumor Eradication by Boron Neutron Capture Therapy with 10 B-enriched Hexagonal Boron Nitride Nanoparticles Grafted with Poly(Glycerol).

Boron neutron capture therapy (BNCT) has emerged as a treatment modality with high precision and efficacy of intractable tumors. At the core of effective tumor BNCT are 10 B carriers with facile preparation as well as advantageous pharmacokinetic and therapeutic profiles. Herein, the design and preparation of sub-10 nm 10 B-enriched hexagonal boron nitride nanoparticles grafted with poly(glycerol) (h-10 BN-PG), and their application to cancer treatment by BNCT are reported. By virtue of their small particle size and outstanding stealth property, h-10 BN-PG nanoparticles accumulate efficiently in murine CT26 colon tumors with a high intratumor 10 B concentration of 8.8%ID g-1 or 102.1 µg g-1 at 12 h post-injection. Moreover, h-10 BN-PG nanoparticles penetrate into the inside of the tumor parenchyma and then are taken up by the tumor cells. BNCT comprising a single bolus injection of h-10 BN-PG nanoparticles and subsequent one-time neutron irradiation results in significant shrinkage of subcutaneous CT26 tumors. h-10 BN-PG-mediated BNCT not only causes direct DNA damage to the tumor cells, but also triggers pronounced inflammatory immune response in the tumor tissues, which contributes to long-lasting tumor suppression after the neutron irradiation. Thus, the h-10 BN-PG nanoparticles are promising BNCT agents to eradicate tumor through highly efficient 10 B accumulation.

Dihydroartemisinin elicits immunogenic death through ferroptosis-triggered ER stress and DNA damage for lung cancer immunotherapy.

BACKGROUND: The immunosuppressive microenvironment of lung cancer serves as an important endogenous contributor to treatment failure. The present study aimed to demonstrate the promotive effect of DHA on immunogenic cell death (ICD) in lung cancer as well as the mechanism. METHODS: The lewis lung cancer cells (LLC), A549 cells and LLC-bearing mice were applied as the lung cancer model. The apoptosis, ferroptosis assay, western blotting, immunofluorescent staining, qPCR, comet assay, flow cytometry, confocal microscopy, transmission electron microscopy and immunohistochemistry were conducted to analyze the functions and the underlying mechanism. RESULTS: An increased apoptosis rate and immunogenicity were detected in DHA-treated LLC and tumor grafts. Further findings showed DHA caused lipid peroxide (LPO) accumulation, thereby initiating ferroptosis. DHA stimulated cellular endoplasmic reticulum (ER) stress and DNA damage simultaneously. However, the ER stress and DNA damage induced by DHA could be abolished by ferroptosis inhibitors, whose immunogenicity enhancement was synchronously attenuated. In contrast, the addition of exogenous iron ions further improved the immunogenicity induced by DHA accompanied by enhanced ER stress and DNA damage. The enhanced immunogenicity could be abated by ER stress and DNA damage inhibitors as well. Finally, DHA activated immunocytes and exhibited excellent anti-cancer efficacy in LLC-bearing mice. CONCLUSIONS: In summary, the current study demonstrates that DHA triggers ferroptosis, facilitating the ICD of lung cancer thereupon. This work reveals for the first time the effect and underlying mechanism by which DHA induces ICD of cancer cells, providing novel insights into the regulation of the immune microenvironment for cancer immunotherapy by Chinese medicine phytopharmaceuticals.

Laser-triggered intelligent drug delivery and anti-cancer photodynamic therapy using platelets as the vehicle.

In our previous study, target drug delivery and treatment of malignant tumors have been achieved by using platelets as carriers loading nano-chemotherapeutic agents (ND-DOX). However, drug release from ND-DOX-loaded platelets is dependent on negative platelet activation by tumor cells, whose activation is not significant enough for the resulting drug release to take an effective anti-tumor effect. Exploring strategies to proactively manipulate the controlled release of drug-laden platelets is imperative. The present study innovatively revealed that photodynamic action can activate platelets in a spatiotemporally controlled manner. Consequently, based on the previous study, platelets were used to load iron oxide-polyglycerol-doxorubicin-chlorin e6 composites (IO-PG-DOX-Ce6), wherein the laser-triggered drug release ability and anti-tumor capability were demonstrated. The findings suggested that IO-PG-DOX-Ce6 could be stably loaded by platelets in high volume without any decrease in viability. Importantly and interestingly, drug-loaded platelets were significantly activated by laser irradiation, characterized by intracellular ROS accumulation and up-regulation of CD62p. Additionally, scanning electron microscopy (SEM) and hydrated particle size results also showed a significant aggregation response of laser irradiated-drug-loaded platelets. Further transmission electron microscopy (TEM) measurements indicated that the activated platelets released extracellularly their cargo drug after laser exposure, which could be taken up by co-cultured tumor cells. Finally, the co-culture model of drug-loaded platelets and tumor cells proved that laser-triggered delivery system of platelets could effectively damage the DNA and promote apoptosis of tumor cells. Overall, the present study discovers a drug-loaded platelets delivery using photodynamic effect, enabling laser-controlled intelligent drug delivery and anti-tumor therapy, which provides a novel and feasible approach for clinical application of cytopharmaceuticals.

What is the context?1. Platelets were applied to load IO-PG-DOX-Ce6, wherein the laser-triggered drug release and anti-tumor effect were investigated in vitro.2. The findings indicated that IO-PG-DOX-Ce6 could be stably loaded by platelets in high volume without any decrease in viability, which may attribute to the activation of autophagy in platelets.3. IO-PG-DOX-Ce6-loaded platelets could be significantly activated by laser irradiation (690 nm).4. Activated platelets released extracellularly their cargo drug after laser exposure, which could be taken up by co-cultured tumor cells5. The co-culture model of drug-loaded platelets and tumor cells proved that the laser-triggered delivery system of platelets could effectively damage the DNA and promote apoptosis of tumor cells.What is new?1. Platelets could be utilized as the vehicle to load photosensitizer-loaded-nano-drug.2. Photodynamic action can activate platelets in a spatiotemporally controlled manner, which could be a tool to regulate the activation of platelets.3. The laser-triggered activation of drug-loaded platelets allows for target release of cargo.4. The limitation of the current research is that only in vitro experiments were carried out to demonstrate our conclusions.What is impact?The present work provides a novel and feasible approach for the clinical application of cytopharmaceuticals.

Chlorin e6-induced photodynamic effect facilitates immunogenic cell death of lung cancer as a result of oxidative endoplasmic reticulum stress and DNA damage.

Suppression of the immune microenvironment is an important endogenous contributor to treatment failure in lung cancer. Photodynamic therapy (PDT) is widely used in the treatment of malignant tumors owing to its photo-selectivity and minimal side effects. Some studies have shown the ability of photodynamic action not only to cause photo-cytotoxicity to tumor cells but also to induce immunogenic cell death (ICD). However, the mechanism by which PDT enhances tumor immunogenicity is poorly understood. The present study aimed to explore the immunogenicity effect of PDT on lung cancer and to reveal the underlying mechanism. First, we searched for effective conditions for PDT-induced apoptosis in lung cancer cells. Just as expected, chlorin e6 (Ce6) PDT could enhance the immunogenicity of lung cancer cells alongside the induction of apoptosis, characterized by up-regulation of CRT, HSP90, HMGB1 and MHC-I. Further results showed the generation of ROS by Ce6 PDT under the above conditions, which is an oxidative damaging agent. Simultaneously, PDT induced endoplasmic reticulum (ER) stress in cells, as evidenced by enhanced Tht staining and up-regulated CHOP and GRP78 expression. Moreover, PDT led to DNA damage response (DDR) as well. However, the redox inhibitor NAC abolished the ER stress and DDR caused by PDT. More importantly, NAC also attenuated PDT-induced improvement of immunogenicity in lung cancer. On this basis, the PDT-induced CRT up-regulation was found to be attenuated in response to inhibition of ER stress. In addition, PDT-induced increase in HMGB1 and HSP90 release was blocked by inhibition of DDR. In summary, Ce6 PDT could produce ROS under certain conditions, which leads to ER stress that promotes CRT translocation to the cell membrane, and the resulting DNA damage causes the expression and release of nuclear HMGB1 and HSP90, thereby enhancing the immunogenicity of lung cancer. This current study elucidates the mechanism of PDT in ameliorating the immunogenicity of lung cancer, providing a rationale for PDT in regulating the immune microenvironment for the treatment of malignant tumors.

Targeted photodynamic therapy of glioblastoma mediated by platelets with photo-controlled release property.

Photodynamic therapy (PDT) has recently emerged as a promising, targeted treatment modality for glioblastoma (GBM) which is the most vicious type of brain tumor. Successful GBM-PDT hinges upon light activation of a photosensitizer accumulated in the tumor. However, inadequate tumor accumulation of photosensitizer severely limits the success of PDT of GBM. To tackle this difficulty, we herein propose a drug delivery strategy of "platelets with photo-controlled release property". This strategy exploits platelets as carriers to deliver a photosensitizer which, in the current study, is a nano-composite (BNPD-Ce6) comprised of chlorine e6 (Ce6) loaded to boron nitride nanoparticles with a surface coating of polyglycerol and doxorubicin. To demonstrate the working mechanism and therapeutic advantage of this strategy, we loaded mouse platelets with BNPD-Ce6 to yield the nano-device BNPD-Ce6@Plt. In vitro experiments showed BNPD-Ce6@Plt to have a high loading capacity and efficiency. Laser irradiation (LI) at a wavelength of 808 nm induced ROS generation in BNPD-Ce6@Plt which displayed rapid activation, aggregation, and speedy discharge of BNPD-Ce6 into co-cultured GL261 mouse GBM cells which in turn, after LI, exhibited marked ROS generation, DNA damage, reduced viability, and cell death. In vivo animal experiments, mice that were intravenously injected with BNPD-Ce6@Plt exhibited rapid and extensive BNPD-Ce6 accumulation in both subcutaneous and intra-brain GL261 tumors shortly after LI of the tumors and the tumors displayed massive tissue necrosis after LI for a second time. Finally, a PDT regimen of two intravenous BNPD-Ce6@Plt injections each followed by multiple times of extracranial LI at the tumor site significantly inhibited the growth of intra-brain GL261 tumors and markedly increased the survival of the host animals. No apparent tissue damage was found in vital organs. Our findings make a compelling case for the notion that platelets are efficient carriers that can photo-controllably deliver nano-photosensitizers to achieve highly targeted and efficacious PDT of GBM. This work presents a novel approach to GBM-PDT with great translational potential.

Dihydroartemisinin remodels macrophage into an M1 phenotype via ferroptosis-mediated DNA damage.

Lung cancer recruits tumor-associated macrophages (TAMs) massively, whose predominantly pro-tumor M2 phenotype leads to immunosuppression. Dihydroartemisinin (DHA) has been proven to remodel TAM into an anti-tumor M1 phenotype at certain concentrations in the present study, which was hypothesized to facilitate anti-lung cancer immunotherapy. However, how DHA remodels the TAM phenotype has not yet been uncovered. Our previous work revealed that DHA could trigger ferroptosis in lung cancer cells, which may also be observed in TAM thereupon. Sequentially, in the current study, DHA was found to remodel TAM into the M1 phenotype in vitro and in vivo. Simultaneously, DHA was observed to trigger ferroptosis in TAM and cause the DNA damage response and NF-κB activation. Conversely, the DHA-induced DNA damage response and NF-κB activation in TAM were attenuated after the inhibition of ferroptosis in TAM using an inhibitor of ferroptosis. Importantly, a ferroptosis inhibitor could also abolish the DHA-induced phenotypic remodeling of TAM toward the M1 phenotype. In a nutshell, this work demonstrates that DHA-triggered ferroptosis of TAM results in DNA damage, which could activate downstream NF-κB to remodel TAM into an M1 phenotype, providing a novel strategy for anti-lung cancer immunotherapy. This study offers a novel strategy and theoretical basis for the use of traditional Chinese medicine monomers to regulate the anti-tumor immune response, as well as a new therapeutic target for TAM phenotype remodeling.

A nanoreactor boosts chemodynamic therapy and ferroptosis for synergistic cancer therapy using molecular amplifier dihydroartemisinin.

BACKGROUND: Chemodynamic therapy (CDT) relying on intracellular iron ions and H2O2 is a promising therapeutic strategy due to its tumor selectivity, which is limited by the not enough metal ions or H2O2 supply of tumor microenvironment. Herein, we presented an efficient CDT strategy based on Chinese herbal monomer-dihydroartemisinin (DHA) as a substitute for the H2O2 and recruiter of iron ions to amplify greatly the reactive oxygen species (ROS) generation for synergetic CDT-ferroptosis therapy. RESULTS: The DHA@MIL-101 nanoreactor was prepared and characterized firstly. This nanoreactor degraded under the acid tumor microenvironment, thereby releasing DHA and iron ions. Subsequent experiments demonstrated DHA@MIL-101 significantly increased intracellular iron ions through collapsed nanoreactor and recruitment effect of DHA, further generating ROS thereupon. Meanwhile, ROS production introduced ferroptosis by depleting glutathione (GSH), inactivating glutathione peroxidase 4 (GPX4), leading to lipid peroxide (LPO) accumulation. Furthermore, DHA also acted as an efficient ferroptosis molecular amplifier by direct inhibiting GPX4. The resulting ROS and LPO caused DNA and mitochondria damage to induce apoptosis of malignant cells. Finally, in vivo outcomes evidenced that DHA@MIL-101 nanoreactor exhibited prominent anti-cancer efficacy with minimal systemic toxicity. CONCLUSION: In summary, DHA@MIL-101 nanoreactor boosts CDT and ferroptosis for synergistic cancer therapy by molecular amplifier DHA. This work provides a novel and effective approach for synergistic CDT-ferroptosis with Chinese herbal monomer-DHA and Nanomedicine.

Platelets are highly efficient and efficacious carriers for tumor-targeted nano-drug delivery.

The present work aims to prove the concept of tumor-targeted drug delivery mediated by platelets. Doxorubicin (DOX) attached to nanodiamonds (ND-DOX) was investigated as the model payload drug of platelets. In vitro experiments first showed that ND-DOX could be loaded in mouse platelets in a dose-dependent manner with a markedly higher efficiency and capacity than free DOX. ND-DOX-loaded platelets (Plt@ND-DOX) maintained viability and ND-DOX could be stably held in the platelets for at least 4 hr. Next, mouse Lewis lung cancer cells were found to activate Plt@ND-DOX and thereby stimulate cargo unloading of Plt@ND-DOX. The unloaded ND-DOX was taken up by co-cultured cancer cells which consequently exhibited loss of viability, proliferation suppression and apoptosis. In vivo, Plt@ND-DOX displayed significantly prolonged blood circulation time over ND-DOX and DOX in mice, and Lewis tumor grafts demonstrated infiltration, activation and cargo unloading of Plt@ND-DOX in the tumor tissue. Consequently, Plt@ND-DOX effectively reversed the growth of Lewis tumor grafts which exhibited significant inhibition of cell proliferation and apoptosis. Importantly, Plt@ND-DOX displayed a markedly higher therapeutic potency than free DOX but without the severe systemic toxicity associated with DOX. Our findings are concrete proof of platelets as efficient and efficacious carriers for tumor-targeted nano-drug delivery with the following features: 1) large loading capacity and high loading efficiency, 2) good tolerance of cargo drug, 3) stable cargo retention and no cargo unloading in the absence of stimulation, 4) prolonged blood circulation time, and 5) excellent tumor distribution and tumor-activated drug unloading leading to high therapeutic potency and few adverse effects. Platelets hold great potential as efficient and efficacious carriers for tumor-targeted nano-drug delivery.

Chlorin e6-Induced Photodynamic Effect Polarizes the Macrophage Into an M1 Phenotype Through Oxidative DNA Damage and Activation of STING.

The tumor-associated macrophage (TAM) serves as an immunosuppressive agent in the malignant tumor microenvironment, facilitating the development and metastasis of lung cancer. The photodynamic effect destabilizes cellular homeostasis owing to the generation of reactive oxygen species (ROS), resulting in the enhanced pro-inflammatory function of immunocytes. In our previous study, the Ce6-mediated photodynamic effect was found to have kept the viability of macrophages and to remodel them into the M1 phenotype. However, the mechanism remains unrevealed. The present study now explores the mechanism of photodynamic therapy (PDT)-mediated reprogramming of macrophages. As expected, Ce6-mediated PDT was capable of generating reactive oxygen species, which was continuously degraded, causing "low intensity" damage to DNA and thereby triggering subsequent DNA damage response in macrophages. The autophagy was thus observed in Ce6-treated macrophages and was shown to protect cells from being photodynamically apoptotic. More importantly, Ce6 PDT could activate the stimulator of interferon genes (STING) molecule, a sensor of DNA damage, which could activate the downstream nuclear factor kappa-B (NF-κB) upon activation, mediating the polarization of macrophages towards the M1 phenotype thereupon. In addition, inhibition of ROS induced by PDT attenuated the DNA damage, STING activation, and M1-phenotype reprogramming. Furthermore, the silence of the STING weakened Ce6 treatment-mediated M1 remodeling of macrophages as well. Altogether, these findings indicate the Ce6-induced photodynamic effect polarizes macrophages into an M1 phenotype through oxidative DNA damage and subsequent activation of the STING. This work reveals the crucial mechanism by which photodynamic therapy regulates the macrophage phenotype and also provides a novel intervenable signaling target for remodeling macrophages into the M1 phenotype.

Ferroptosis triggered by dihydroartemisinin facilitates chlorin e6 induced photodynamic therapy against lung cancerthrough inhibiting GPX4 and enhancing ROS.

Photodynamic therapy (PDT) is noninvasive, low toxicity, and photo-selective, but may be resisted by malignant cells. A previous study found chlorin e6 (Ce6) mediated PDT showed drug resistance in lung cancer cells (LLC), which may be associated with PDT-induced DNA damage response (DDR). DDR may up-regulate glutathione peroxidase 4 (GPX4), which in turn degrade ROS induced by PDT. However, dihydroartemisinin (DHA) was found to down-regulate GPX4. Accordingly, the DHA was hypothesized to improve the resistance to PDT. The present work explores the mechanism of Ce6 mediated drug resistance and reveals whether DHA can enhance the efficacy of PDT by suppressing GPX4. The in vitro experiments found Ce6 treatment did not inhibit the viability of LLC within 6 h without inducing significant apoptosis, suggesting LLC were resistant to PDT. Further investigation demonstrated PDT could damage DNA and up-regulate GPX4, thus degrading the generated ROS. DHA effectively inhibited the viability of LLC and induced apoptosis. Importantly, DHA displayed a prominent inhibitory effect on the GPX4 expression and thereby triggered ferroptosis. Combining DHA with Ce6 for treatment of LLC resulted in the suppressed GPX4 and elevated ROS. Finally, the findings showed DHA combined with Ce6 exhibited superb anti-lung cancer efficacy. In summary, Ce6 PDT damages DNA, up-regulates GPX4 to degrade ROS, thereby inducing drug resistance. Down-regulation of GPX4 by DHA-triggered ferroptosis significantly enhances the efficacy of PDT. This study provides an outstanding theoretical basis for the regulation of the intratumoral redox system and improving PDT efficacy against lung cancer by herbal monomer DHA.

Harnessing chlorin e6 loaded by functionalized iron oxide nanoparticles linked with glucose for target photodynamic therapy and improving of the immunogenicity of lung cancer.

BACKGROUND: Non-small-cell lung cancer (NSCLC) is the most common malignant lung tumor and is difficult to be eradicated due to its immunosuppressive microenvironment. Chlorin e6 (Ce6)-mediated photodynamic therapy (PDT) could improve immunogenicity while destroying malignant tumor cells. However, the clinic application of Ce6-mediated PDT is limited by Ce6's poor water solubility and insufficient accumulation in lung cancer. To address this issue, Ce6 was loaded onto functionalized iron oxide nanoparticles linked with glucose to improve the distribution of Ce6 in lung cancer. MATERIALS AND RESULTS: The results of transmission electron microscopy (TEM), UV-Vis spectrophotometry, dynamic light scattering and near-infrared (NIR) spectroscopy confirmed the successful preparation of the composites. Confocal and flow cytometry showed IO-PG-GLU-Ce6 significantly enhanced the uptake of Ce6 by lung cancer cells and produced more reactive oxygen species (ROS) under NIR light irradiation. In addition, the detection of cell viability, proliferation and apoptosis indicated IO-PG-GLU-Ce6 achieved stronger photo-toxicity to lung cancer cells. Moreover, IO-PG-GLU-Ce6 treatment effectively damaged the DNA of lung cancer cells and thereby activated STING, up-regulated the expression of IFN-ß, HMGB1 and HSP90, indicating augmented immunogenicity of lung cancer cells. Further results of in vivo, organ imaging and tissue fluorescence sections demonstrated IO-PG-GLU-Ce6 significantly improved the distribution of Ce6 in tumor tissues of lung cancer-bearing mice as well. Finally, the findings of in vivo study and immunohistochemistry confirmed the better efficacy of IO-PG-GLU-Ce6. HE staining results of vital organs suggested that the composites were less toxic. CONCLUSION: In conclusion, Ce6 loaded by functionalized iron oxide nanoparticles linked with glucose exhibited both target photodynamic efficacy and the ability to enhance its immunogenicity in lung cancer. This study provides a promising strategy for augment of the targeting delivery of Ce6 and its mediated photodynamic and immunotherapy.

Chlorin e6 mediated photodynamic therapy triggers resistance through ATM-related DNA damage response in lung cancer cells.

OBJECTIVE: Photodynamic therapy (PDT) is a promising strategy for the treatment of malignant tumors due to its high selectivity, limited-toxicity, and non-invasiveness. However, PDT can also induce DNA damage and subsequent repair response, which may reduce the efficacy of PDT. In the present study, we sought to explore the effect of chlorin e6 (Ce6)-mediated PDT on DNA damage and DNA damage response (DDR) in lung cancer cells. In addition, the effect of PDT combined with ATM inhibitor on molecules of DDR and the possibility of improving the efficacy of PDT were further investigated. MATERIALS AND METHODS: In the in vitro study, lewis cells were submitted to Ce6 treatment (2, 4, 8, 16, 32 µg/mL). To determine the concentration of Ce6, uptake and toxicity of Ce6 mediated PDT were detected using flow cytometry (FACS), Confocal microscopy, and CCK-8. In the subsequent research, 8 µg/mL of Ce6 was the treatment condition for inducing PDT. The different post-irradiation placement times were further grouped under this condition (2, 4, 6, 12 h). Cellular reactive oxygen species (ROS), damage of DNA were measured by DCFH-DA probe, comet assay respectively. Then the expression of p-ATM, p53, and γ-H2A.X proteins related to DNA damage response, was detected by WB. The efficacy of Ce6 induced PDT was also demonstrated by Annexin-V/PI staining as well as the expression of PCNA, cleaved-caspase-3. On this basis, ATM inhibitor was applied to treat lewis cells combined with Ce6 (2, 4 h) to investigate whether the efficacy of PDT induced by Ce6 can be improved after the ATM-related DDR was blocked. The cell viability, apoptosis, and expression of associated proteins were assayed. RESULTS: At 2-4 h after PDT treatment, ROS was dramatically elevated in lewis cells, DNA double-strand breaks (DDSB) occurred, as well as up-regulation of DDR proteins γ-H2A.X, p-ATM, and p53. At the same time, lewis cells did not undergo significant apoptosis. After ATM inhibition, the DDR was significantly blocked within 2-4 h after Ce6 induced PDT, along with a pronounced decrease in cell viability followed by a prominent increase of apoptosis. CONCLUSION: Ce6-mediated PDT generates ROS in a short period time, thus inducing DNA damage, ATM-related DDR as well as promoting resistance of lung cancer cells to PDT. Combining ATM inhibitor with PDT could effectively inhibit the DDR induced by PDT, thereby enhancing the efficacy. This study reveals a new resistance mechanism of PDT and proposes an intervention strategy.

Synergy of nanodiamond-doxorubicin conjugates and PD-L1 blockade effectively turns tumor-associated macrophages against tumor cells.

BACKGROUND: Tumor-associated macrophages (TAMs) are the most abundant stromal cells in the tumor microenvironment. Turning the TAMs against their host tumor cells is an intriguing therapeutic strategy particularly attractive for patients with immunologically "cold" tumors. This concept was mechanistically demonstrated on in vitro human and murine lung cancer cells and their corresponding TAM models through combinatorial use of nanodiamond-doxorubicin conjugates (Nano-DOX) and a PD-L1 blocking agent BMS-1. Nano-DOX are an agent previously proved to be able to stimulate tumor cells' immunogenicity and thereby reactivate the TAMs into the anti-tumor M1 phenotype. RESULTS: Nano-DOX were first shown to stimulate the tumor cells and the TAMs to release the cytokine HMGB1 which, regardless of its source, acted through the RAGE/NF-κB pathway to induce PD-L1 in the tumor cells and PD-L1/PD-1 in the TAMs. Interestingly, Nano-DOX also induced NF-κB-dependent RAGE expression in the tumor cells and thus reinforced HMGB1's action thereon. Then, BMS-1 was shown to enhance Nano-DOX-stimulated M1-type activation of TAMs both by blocking Nano-DOX-induced PD-L1 in the TAMs and by blocking tumor cell PD-L1 ligation with TAM PD-1. The TAMs with enhanced M1-type repolarization both killed the tumor cells and suppressed their growth. BMS-1 could also potentiate Nano-DOX's action to suppress tumor cell growth via blocking of Nano-DOX-induced PD-L1 therein. Finally, Nano-DOX and BMS-1 achieved synergistic therapeutic efficacy against in vivo tumor grafts in a TAM-dependent manner. CONCLUSIONS: PD-L1/PD-1 upregulation mediated by autocrine and paracrine activation of the HMGB1/RAGE/NF-κB signaling is a key response of lung cancer cells and their TAMs to stress, which can be induced by Nano-DOX. Blockade of Nano-DOX-induced PD-L1, both in the cancer cells and the TAMs, achieves enhanced activation of TAM-mediated anti-tumor response.

Macrophages mediated delivery of chlorin e6 and treatment of lung cancer by photodynamic reprogramming.

Photodynamic therapy (PDT) is an emerging anti-tumor strategy.Photosensitizer chlorin e6 (Ce6) can induce photodynamic effect to selectively damage lung cancer cells.In order to further improve its tumor targeting ability, macrophages can be applied as carrier to deliver Ce6 to lung cancer.Tumor associated macrophages (TAM) are important immunocytes in lung cancer immune microenvironment. TAM play crucial role in tumor promotion due to the Immunosuppressive property, reprogramming phenotype of TAM therefore has become a promising strategy.Based on this, in the present study, we suppose that TAM can be used as carrier to deliver Ce6 to lung cancer and be reprogrammed to M1 phenotype by photodynamic action to mediate anti-lung cancer efficacy.The results showed TAM could load with Ce6 and keep viability in the absence of near infrared irradiation (NIR).Moreover, Its viability decreased little within 10 h after NIR.Ce6-loaded TAM could deliver Ce6 to lung cancer cells and retain some drugs in TAM per se.After NIR, phagocytosis of macrophages was enhanced. The expressions of GBP5, iNOS and MHC-II was up-regulated, which indicated TAM were polarized to M1 phenotype.Finally, the study also found the reprogrammed macrophages could inhibit the proliferation and promote the apoptosis of lung cancer cells.These results suggested that macrophages could deliver Ce6 to lung cancer and exhibit anti-lung cancer effect through photodynamic reprogramming.This study provides a novel approach for combining photodynamic action with anti-tumor immunotherapy.

Efficient Delivery of Chlorin e6 by Polyglycerol-Coated Iron Oxide Nanoparticles with Conjugated Doxorubicin for Enhanced Photodynamic Therapy of Melanoma.

Chlorin e6 (Ce6) is a promising photosensitizer for tumor photodynamic therapy (PDT). However, the efficacy of Ce6 PDT is limited by Ce6's poor water solubility, rapid blood clearance, and inadequate accumulation in the tumor tissue. This problem is tackled in this work, wherein functionalized superparamagnetic iron oxide nanoparticles (IO-NPs) were used as carriers to deliver Ce6 to melanoma. The IO-NPs were coated with polyglycerol (PG) to afford good aqueous solubility. The chemotherapeutic agent doxorubicin (DOX) was attached to the PG coating via the hydrazone bond to afford affinity to the cell membrane and thereby promote the cell uptake. The hydrophobic nature of DOX also induced the aggregation of IO-NPs to form nanoclusters. Ce6 was then loaded onto the IO nanoclusters through physical adsorption and coordination with surface iron atoms, yielding the final composites IO-PG-DOX-Ce6. In vitro experiments showed that IO-PG-DOX-Ce6 markedly increased Ce6 uptake in mouse melanoma cells, leading to much-enhanced photocytotoxicity characterized by intensified reactive oxygen species production, loss of viability, DNA damage, and stimulation of tumor cell immunogenicity. In vivo experiments corroborated the in vitro findings and demonstrated prolonged blood clearance of IO-PG-DOX-Ce6. Importantly, IO-PG-DOX-Ce6 markedly increased the Ce6 distribution and retention in mouse subcutaneous melanoma grafts and significantly improved the efficacy of Ce6-mediated PDT. No apparent vital organ damage was observed at the same time. In conclusion, the IO-PG-DOX NPs provide a simple and safe delivery platform for efficient tumor enrichment of Ce6, thereby enhancing antimelanoma PDT.

Conjugation with nanodiamonds via hydrazone bond fundamentally alters intracellular distribution and activity of doxorubicin.

Doxorubicin (DOX) has been widely incorporated in various delivery forms for tareted treatment of malignant tumors such as triple-negative breast cancer (TNBC), with numerous studies reporting higher therapeutic efficacy and lower toxicity at the same time. However, little attention has been paid to whether DOX in a delivery form acts with the same actions and processes as in free form at the cellular level. This question was investigated in the present study wherein DOX conjugated with polyglycerol-coated nanodiamonds through the pH-sensitive hydrazone bond (Nano-DOX) was compared with DOX in free form on the 4T1 mouse TNBC model. We first found Nano-DOX to have a distinct intracellular distribution profile from DOX. Internalized Nano-DOX mainly stayed in the lysosomes slowly releasing DOX into the cytoplasm and then the nucleus whereas DOX displayed both nuclear and lysosomal distribution after cell uptake. Next, Nano-DOX was shown to induce endoplasmic reticulum (ER) stress without substantial DNA damage while DOX caused massive DNA damage as well as ER stress. Consequently, Nano-DOX only caused minimal activation of pro-inflammatory signaling mediated by MAPK/ERK, NF-κB and STAT3 as seen in response to DOX-inflicted DNA damage. Consistently, DOX-induced activities of ABC transporters, CXCL-1, GM-CSF and IL-6, which are tumor protective events downstream to the pro-inflammatory signaling, were also minimal in Nano-DOX-treated cancer cells. These findings are compelling proof that a chemotherapy in nano form can have distinct intracellular pharmacokinetics from its free from, which can result in altered cellular effects of the drug. Implications of these findings are discussed with an emphasis on nano-drug design, tumor pharmacology and chemoresistance.