Hypoxia In Solid Tumors Research Articles

In vitro and in vivo characterization of [64Cu][Cu(elesclomol)] as a novel theranostic agent for hypoxic solid tumors

PurposeHypoxic tumors are associated with therapy resistance and poor cancer prognosis, but methods to detect and counter tumor hypoxia remain insufficient. Our purpose was to investigate 64Cu(II)-elesclomol ([64Cu][Cu(ES)]) as a novel theranostic agent for hypoxic tumors, by implementing an improved production method and assessing its therapeutic and diagnostic potential compared to the established Cu-64 radiopharmaceuticals [64Cu]CuCl2 and [diacetyl-bis(N4-methylthiosemicarbazone) [64Cu][Cu(ATSM)].MethodsCu-64 was produced using a biomedical cyclotron at 12 MeV with the reaction 64Ni(p,n)64Cu, followed by synthesis of [64Cu]CuCl2, [64Cu][Cu(ATSM)], and [64Cu][Cu(ES)]. In vitro therapeutic effects were assessed in both normoxic and hypoxic cells (22Rv1 and PC3 prostate cancer cells, and U-87MG glioblastoma cells) using the clonogenic assay and analyzing cellular uptake and internalization. In vivo therapeutic effects were assessed in 22Rv1 xenografts in BALB/cAnN-Foxn1nu/nu/Rj mice receiving a single or multiple doses of radiopharmaceutical, before their feasibility to detect tumor hypoxia was assessed by positron emission tomography (PET) in 22Rv1 and U-87MG xenografts.ResultsIn vitro and in vivo studies demonstrated that [64Cu][Cu(ES)] reduced cell survival and inhibited tumor growth more effectively than [64Cu][Cu(ATSM)] and [64Cu]CuCl2. Hypoxia increased the cellular uptake and internalization of [64Cu][Cu(ES)] and [64Cu][Cu(ATSM)]. [64Cu][Cu(ES)]-PET tumor hypoxia detection was feasible and also revealed an unexpected finding of uptake in the brain.ConclusionTo the best of our knowledge, this is the first time that ES is radiolabeled with [64Cu]CuCl2 to [64Cu][Cu(ES)]. We demonstrated superior therapeutic effects of [64Cu][Cu(ES)] compared to [64Cu][Cu(ATSM)] and [64Cu]CuCl2 and that [64Cu][Cu(ES)]-PET is feasible. [64Cu][Cu(ES)] is a promising theranostic agent for hypoxic solid tumors.

Biodegradable NIR-II Pseudo Conjugate Polymeric Nanoparticles Amplify Photodynamic Immunotherapy via Alleviation of Tumor Hypoxia and Tumor-Associated Macrophage Reprogramming.

Photodynamic therapy (PDT) has achieved great success in cancer treatment. Despite its great promise, the efficacy of photodynamic immunotherapy can be limited by the hypoxia in solid tumors which is closely related to the abnormal tumor vasculature. These abnormal vasculatures are a hallmark of most solid tumors and facilitate immune evasion. Therefore, tumor vascular normalization is developed as a promising strategy to overcome tumor hypoxia, resulting in improved cancer therapy. Here, a NIR-II bio-degradable pseudo-conjugate polymer (PSP)-based photodynamic polymer is designed to deliver a vascular normalization agent, i.e., regorafenib (Reg) in nanoparticles (NP-PDT@Reg). NP-PDT@Reg under 808nm laser irradiation (NP-PDT@Reg + L) can efficiently release Reg to improve the tumor hypoxia via vascular normalization, making more NP-PDT@Reg and oxygen enter the tumors. Moreover, NP-PDT@Reg + L can further result in generation of more reactive oxygen species (ROS) to eradicate tumor cells while inducing immunogenic cell death (ICD) to activate anti-tumor immune responses. In addition, Reg can reprogram TAM from a pro-tumor M2 phenotype to a tumor-killing M1 phenotype as well, thereby reversing the immunosuppressive tumor microenvironment. Taken together, the current study provides an innovative perspective on the development of novel nanomaterials to overcome the limitations in photodynamic immunotherapy.

Development of multifunctional polymeric nanoparticles co-loaded with ZnPc and Fe2+ ions for synergetic PDT/CDT therapy

Recently photodynamic therapy (PDT)-based combinational therapeutic approaches have been extensively studied to circumvent the hurdle of tissue hypoxia in solid tumors. In this paper, we reported a facile way to prepare multifunctional nanoparticles (NPs) for synergetic PDT/chemodynamic therapy (CDT). Specifically, photosensitizer ZnPc was firstly loaded inside polymeric NPs by a reprecipitation method, followed by surface coating of Fe2+ ions-chelated polydopamine (PDA) shell, which was polymerized via photo-generated 1O2 from the ZnPc-loaded NPs. The resulting ZnPc@PDA-Fe2+ could not only generate 1O2 upon 660-nm photo-irradiation but also produce OH when exposed to H2O2 through the Fenton reaction. Taking advantage of the ZnPc and Fe2+ co-loaded NPs, in vitro combination therapy was performed on Hela cells. As a result, a higher therapeutic effect was achieved compared to single-modality PDT, corresponding to an improved cell inhibitory rate from 59% to 80%. These results demonstrate that our facilely prepared NPs are promising PDT/CDT nanoagents for efficient cancer therapy.

The Efficacy of Nanoparticle Delivery to Hypoxic Solid Tumors by ciRGD Co-Administration Depends on Neuropilin-1 and Neutrophil Levels.

The ability to improve nanoparticle delivery to solid tumors is an actively studied domain, where various mechanisms are looked into. In previous work, the authors have looked into nanoparticle size, tumor vessel normalization, and disintegration, and here it is aimed to continue this work by performing an in-depth mechanistic study on the use of ciRGD peptide co-administration. Using a multiparametric approach, it is observed that ciRGD can improve nanoparticle delivery to the tumor itself, but also to tumor cells specifically better than vessel normalization strategies. The effect depends on the level of tumor perfusion, hypoxia, neutrophil levels, and vessel permeability. This work shows that upon characterizing tumors for these parameters, conditions can be selected that can optimally benefit from ciRGD co-administration as a means to improve NP delivery to solid tumors.

Abstract 3230: Tumor microenvironment modulation by immunotherapy sensitizes solid tumors to radiation

Abstract Radiation therapy (RT) has been prevalently implemented to treat cancer in clinical settings by inducing DNA damage in tumor cells. However, tumor microenvironmental factors such as severe hypoxic conditions and vascular anomalies attenuate the therapeutic efficacy of RT, thus resulting in unsatisfactory outcomes in solid tumors. Recently, Immune checkpoint blockade (ICB) has improved immune recognition to tumor cells and normalized tumor vasculature to diminish hypoxia in solid tumors. Herein, we suggest that RT combined with ICB synergistically alters tumor microenvironments, thus facilitating the recruitment of cytotoxic immune cells into tumors as well as sensitizing radiation effectiveness. RT in combination with ICB not only normalized tumor vasculature to reduce hypoxia, but also increased anti-tumor effects from immune-mediated toxicity and DNA damage-mediated apoptosis in several solid tumor-bearing mouse models to a greater extent than did either monotreatment of RT or ICB. This study will provide mechanistic insight into synergistic effects conferred by RT and ICB as well as a strong preclinical rationale for combining the two therapeutic modalities in human cancers. Citation Format: Minjeong Kang, DaeYong Lee, Yifan Wang, Betty Kim, Wen Jiang. Tumor microenvironment modulation by immunotherapy sensitizes solid tumors to radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3230.

Sononeoperfusion: a new therapeutic effect to enhance tumour blood perfusion using diagnostic ultrasound and microbubbles

BackgroundHypoperfusion or resultant hypoxia in solid tumours is a main reason for therapeutic resistance. Augmenting the blood perfusion of hypovascular tumours might improve both hypoxia and drug delivery. Cavitation is known to result in microstreaming and sonoporation and to enhance drug diffusion into tumours. Here, we report the ability to enhance both tumour blood perfusion and doxorubicin (Dox) delivery using a new sononeoperfusion effect causing a cavitation effect on tumour perfusion in subcutaneous Walker-256 tumours of rats using ultrasound stimulated microbubble (USMB).MethodsTo induce the sononeoperfusion effect, USMB treatment was performed with a modified diagnostic ultrasound (DUS) system and SonoVue® microbubbles. The therapeutic pulse was operated with a peak negative pressure of 0.26 to 0.32 MPa and a pulse repetition frequency (PRF) of 50 Hz to 2 kHz. Contrast-enhanced ultrasound (CEUS) was used for tumour perfusion assessment.ResultsThe USMB treatment of 0.26 MPa and 1 kHz could significantly enhance tumour perfusion with a 20.29% increase in the CEUS peak intensity and a 21.42% increment in the perfusion area for more than 4 hours (P < 0.05). The treatment also increased Dox delivery to tumours by approximately 3.12-fold more than that of the control (P < 0.05). Furthermore, ELISAs showed that vasodilators and inflammatory factors increased 4 hours after treatment (P < 0.05), suggesting that the inflammatory response plays an important role in the sononeoperfusion effect.ConclusionThe USMB-induced sononeoperfusion effect could significantly enhance the blood perfusion of Walker-256 tumours and promote drug delivery. It might be a novel physical method for overcoming the therapeutic resistance of hypoperfused or hypoxic tumours.

Near Infrared-Activatable Methylene Blue Polypeptide Codelivery of the NO Prodrug via π-π Stacking for Cascade Reactive Oxygen Species Amplification-Mediated Photodynamic Therapy.

The application of photodynamic therapy (PDT) has attracted remarkable interest in cancer treatment because of the advantages of noninvasiveness and spatiotemporal selectivity. However, the PDT efficiency is considerably limited by photosensitizer (PS) quenching and severe hypoxia in solid tumors. Herein, a kind of near infrared (NIR)-activatable methylene blue (MB) peptide nanocarrier was developed for codelivery of nitric oxide (NO) prodrug JSK, expecting a cascade of reactive oxygen species (ROS) amplification-mediated antitumor PDT. In detail, MB was conjugated to water-soluble polyethylene glycol-polylysine (PEG-PLL) through NIR-photocleavable 10-N-carbamoyl bonds, and the subsequent amphiphilic conjugates (mPEG-PLL-MB) self-assembled into nanoparticles (NPs), which allowed JSK codelivery via π-π stacking interactions. MB in quenched state in mPEG-PLL-MB/JSK NPs could be photoactivated by NIR light locoregionally in a controlled manner due to the photocleavage of carbamoyl bonds. Apart from ROS production, assembly disturbance and even disintegration of mPEG-PLL-MB/JSK occurred along with MB activation that subsequently freed JSK, which was further triggered by intracellularly overexpressed glutathione (GSH) and glutathione S-transferase (GST) to sustain the release of NO. NO then served as a hypoxia relief agent through inhibition of cellular respiration to economize O2, cooperating with MB activation and GSH depletion, which synergistically enabled a cascade of ROS amplification to augment PDT for mitochondrial apoptosis-mediated tumor inhibition in vitro and in vivo. Therefore, this pioneering strategy of cascade amplification of ROS addressed the key issues of PS inactivation, hypoxia resistance, and ROS neutralization in a three-pronged approach, which hold great promise in efficient antitumor PDT.

Supramolecular Photosensitizer Enables Oxygen-Independent Generation of Hydroxyl Radicals for Photodynamic Therapy.

The highly oxygen-dependent nature of photodynamic therapy (PDT) limits its therapeutic efficacy against hypoxic solid tumors in clinics, which is an urgent problem to be solved. Herein, we develop an oxygen-independent supramolecular photodynamic agent that produces hydroxyl radical (•OH) by oxidizing water in the presence of intracellularly abundant pyruvic acid under oxygen-free conditions. A fluorene-substituted BODIPY was designed as the electron donor and coassembled with perylene diimide as the electron acceptor to form the quadruple hydrogen-bonded supramolecular photodynamic agent. Detailed mechanism studies reveal that intermolecular electron transfer and charge separation upon light irradiation result in an efficient generation of radical ion pairs. Under oxygen-free conditions, the cationic radicals directly oxidize water to generate highly cytotoxic •OH, and the anionic radicals transfer electrons to pyruvic acid, realizing the catalytic cycle. Thus, this photodynamic agent exhibited superb photocytotoxicity even under severe hypoxic environments and excellent in vivo antitumor efficacy on HeLa-bearing mouse models. This work provides a strategy for constructing oxygen-independent photodynamic agents, which opens up an avenue for effective PDT against hypoxic tumors.

An Ultrasound-Triggered Nanoplatform for Synergistic Sonodynamic-Nitric Oxide Therapy.

Ultrasound (US)-triggered sonodynamic therapy (SDT) has aroused intensive interest as a powerful alternative for cancer treatment in recent years due to its non-invasiveness and deep tissue penetration. However, the therapeutic effect of SDT alone is still limited by intrinsic hypoxia in solid tumors. Combined synergistic therapy strategies are highly desired for improving therapeutic efficiency. Herein, a rationally designed intelligent theranostic nanoplatform is developed for the enhancement of cancer treatment through synergistic SDT and nitric oxide (NO) therapy. This US-triggered nanoplatform is fabricated by integrating a sonosensitizer Rose Bengal (RB) and a NO donor (SNO) into manganese-doped hollow mesoporous silica nanoparticles (MH-SNO@RB). Impressively, the acidic and reducing tumor microenvironment accelerates the sustainable release of Mn ions from the framework, which facilitates the MH-SNO@RB to be used as a contrast agent for magnetic resonance imaging. More importantly, the reactive oxygen species (ROS) generated by RB and NO molecules released from SNO, which are simultaneously triggered by US, can react with each other to yield highly reactive peroxynitrite (ONOO-) ions for effective tumor inhibition both in vitro and in vivo. Furthermore, the nanoplatform demonstrates good hemocompatibility and histocompatibility. This study opens a new strategy for the full utilization of US and intelligent design avenues for high-performance cancer treatment.

Bacteria-targeted delivery of black phosphorus quantum dots facilitates photothermal therapy against hypoxic tumors and complementary low-dose radiotherapy.

Many approaches have been employed to relieve hypoxia in solid tumors to enhance sensitivity to radiotherapy (RT), including O2 delivery or hydrogen peroxide (H2O2) decomposition strategies. To date, however, these modalities have been restricted by poor O2 loading, rapid O2 leakage, and limited endogenous H2O2 levels. To overcome these limitations, we therefore sought to develop an effective approach for the oxygen-independent treatment of hypoxic tumors. In this study, we designed a novel black phosphorus quantum dot (BPQD)/Escherichia coli (E. coli) hybrid system (BE) capable of facilitating the photothermal therapy (PTT) of hypoxic tumors. A simple electrostatic adsorption approach was used to conjugate BPQDs to E. coli. BE is capable of reliably targeting hypoxic tumors and mediating PTT. BPQDs in BE can directly facilitate X-ray-mediated radiosensitization of tumors, thereby achieving significant RT efficacy in response to lower doses of radiation, effectively and specifically damaging hypoxic tumor tissues to suppress the growth of tumors. Our results highlight this BE system as a novel approach to tumor radiosensitization with great potential for clinical application.

A near-infrared light-activatable Ru(ii)-coumarin photosensitizer active under hypoxic conditions.

Photodynamic therapy (PDT) represents a promising approach for cancer treatment. However, the oxygen dependency of PDT to generate reactive oxygen species (ROS) hampers its therapeutic efficacy, especially against hypoxic solid tumors. In addition, some photosensitizers (PSs) have dark toxicity and are only activatable with short wavelengths such as blue or UV-light, which suffer from poor tissue penetration. Herein, we developed a novel hypoxia-active PS with operability in the near-infrared (NIR) region based on the conjugation of a cyclometalated Ru(ii) polypyridyl complex of the type [Ru(C^N)(N^N)2] to a NIR-emitting COUPY dye. The novel Ru(ii)-coumarin conjugate exhibits water-solubility, dark stability in biological media and high photostability along with advantageous luminescent properties that facilitate both bioimaging and phototherapy. Spectroscopic and photobiological studies revealed that this conjugate efficiently generates singlet oxygen and superoxide radical anions, thereby achieving high photoactivity toward cancer cells upon highly-penetrating 740 nm light irradiation even under hypoxic environments (2% O2). The induction of ROS-mediated cancer cell death upon low-energy wavelength irradiation along with the low dark toxicity exerted by this Ru(ii)-coumarin conjugate could circumvent tissue penetration issues while alleviating the hypoxia limitation of PDT. As such, this strategy could pave the way to the development of novel NIR- and hypoxia-active Ru(ii)-based theragnostic PSs fuelled by the conjugation of tunable, low molecular-weight COUPY fluorophores.

In situ hypoxia modulating nano-catalase for amplifying DNA damage in radiation resistive colon tumors.

Radiation therapy (RT) is a mainstream clinical approach in cancer treatment. However, the therapeutic efficacy of RT is greatly hindered by the presence of excessive hydrogen peroxide (H2O2) in the hypoxic region of the solid tumor, thus leading to tumor recurrence and metastasis. Herein, a thioketal-linked amphiphilic nano-assembly (MTS) loaded with hydrophobic manganese oxide (HMO) nanoparticles (MTS@HMO) is examined as a promising multi-purpose reactive oxygen species (ROS)-catalytic nanozyme for transforming an RT-resistant hypoxic tumor microenvironment (TME) into an RT-susceptible one by scavenging ROS in the hypoxic core of the solid tumor. After intravenous injection, the MTS@HMO nano-assembly was able to sense and be degraded by the abundant ROS in the hypoxic TME, thereby releasing HMO particles for subsequent scavenging of H2O2. The oxygen generated during peroxide scavenging then relieved the hypoxic TME, thereby resulting in an increased sensitivity of the hypoxic tumor tissue towards RT. Moreover, the in situ hypoxic status was monitored via the T1-enhanced magnetic resonance (MR) imaging of the Mn2+ ions generated by the ROS-mediated degradation of HMO. The in vitro results demonstrated a significant H2O2 elimination and enhanced oxygen generation after the treatment of the MTS@HMO nano-assembly with tumor cells under hypoxic conditions, compared to the control MTS group. In addition, the combination of RT and pre-treatment with MTS@HMO nano-assembly significantly amplified the permanent DNA strand breaks in tumor cells compared to the control RT group. More importantly, the in vivo results proved that the systemic injection of the MTS@HMO nano-assembly prior to RT irradiation enhanced the RT-mediated tumor suppression and down-regulated the hypoxic marker of HIF-1α in the solid tumor compared to the control RT group. Overall, the present work demonstrates the great potential of the versatile ROS-catalytic hypoxia modulating strategy using the MTS@HMO nano-assembly to enhance the RT-induced antitumor efficacy in hypoxic solid tumors.

Low-dose X-ray radiodynamic therapy solely based on gold nanoclusters for efficient treatment of deep hypoxic solid tumors combined with enhanced antitumor immune response.

Background: Radiodynamic therapy (RDT) is an emerging novel anti-cancer treatment based on the generation of cytotoxic reactive oxygen species (ROS) at the lesion site following the interaction between low-dose X-ray and a photosensitizer (PS) drug. For a classical RDT, scintillator nanomaterials loaded with traditional PSs are generally involved to generate singlet oxygen (1O2). However, this scintillator-mediated strategy generally suffers from insufficient energy transfer efficiency and the hypoxic tumor microenvironment, and finally severely impedes the efficacy of RDT. Methods: Gold nanoclusters were irradiated by low dose of X-ray (called RDT) to investigate the production of ROS, killing efficiency of cell level and living body level, antitumor immune mechanism and biosafety. Results: A novel dihydrolipoic acid coated gold nanoclusters (AuNC@DHLA) RDT, without additional scintillator or photosensitizer assisted, has been developed. In contrast to scintillator-mediated strategy, AuNC@DHLA can directly absorb the X-ray and exhibit excellent radiodynamic performance. More importantly, the radiodynamic mechanism of AuNC@DHLA involves electron-transfer mode resulting in O2 -• and HO•, and excess ROS has been generated even under hypoxic conditions. Highly efficient in vivo treatment of solid tumors had been achieved via only single drug administration and low-dose X-ray radiation. Interestingly, enhanced antitumor immune response was involved, which could be effective against tumor recurrence or metastasis. Negligible systemic toxicity was also observed as a consequence of the ultra-small size of AuNC@DHLA and rapid clearance from body after effective treatment. Conclusions: Highly efficient in vivo treatment of solid tumors had been achieved, enhanced antitumor immune response and negligible systemic toxicity were observed. Our developed strategy will further promote the cancer therapeutic efficiency under low dose X-ray radiation and hypoxic conditions, and bring hope for clinical cancer treatment.

Modelling the effects of E/Z photoisomerization of a cyclocurcumin analogue on the properties of cellular lipid membranes.

The use of photosensitive molecules capable of isomerizing under light stimuli, and thus induce perturbation in biological systems, is becoming increasingly popular for potential light-activated chemotherapeutic purposes. We recently show that a cyclocurcumin derivative (CCBu), may be suitable for light-activated chemotherapy and may constitute a valuable alternative to traditional photodynamic therapy, due to its oxygen-independent mechanism of action, which allows the treatment of hypoxic solid tumors. In particular, we have shown that the E/Z photoisomerization of CCBu correlates with strong perturbations of model lipid bilayers. In this work, we perform all-atom classical molecular dynamics for a more complex bilayer, whose composition is, thus, much closer to eukaryotic outer cell membranes. We have evidenced important differences in the interaction pathway between CCBu and the complex lipid bilayer as compared to previous models, concerning both the membrane penetration capacity and the isomerization-induced perturbations. While we confirm that structural perturbations of the lipid membrane are induced by isomerization, we also show how the use of a simplified membrane model can result in an oversimplification of the system and hinder key physical and biological phenomena. Although, CCBu may be considered as a suitable candidate for light-activated chemotherapy, we also underline how the inclusion of bulkier substituents, inducing larger perturbations upon photoisomerization, may enhance its efficiency.

Cleavable collagenase-assistant nanosonosensitizer for tumor penetration and sonodynamic therapy

Sonodynamic therapy (SDT), a combination of low-intensity ultrasound with a sonosensitizer, has been explored as a promising alternative for cancer therapy. However, condensed extracellular matrix (ECM) resulting in poor perfusion and extreme hypoxia in solid tumor potentially compromises effective SDT. Herein, we develop a novel cleavable collagenase-assistant and O2-supplied nanosonosensitizer (FePO2@HC), which is embedded through fusing collagenase (CLG) and human serum albumin (HSA), followed by encapsulating Ferric protoporphyrin (FeP) and dioxygen. As a smart carrier, HSA is stimuli-responsive and collapsed by reduced glutathione (GSH) overexpressed in tumor, resulting to the release of the components in FePO2@HC. The released CLG acting as an artificial scissor, degrades the collagen fibers in tumor, thus, breaking tumor tissue and enhancing FePO2 accumulation in tumor inner with higher than that without CLG. Simultaneously, oxygen molecules are released from FePO2 in hypoxic environment and alleviate the tumor hypoxia. As a sonosensitizer, FeP is subsequently irradiated by ultrosound wave (US) and activates surrounding dioxygen to generate amount of singlet oxygen (1O2). Contributed from the ECM-degradation, such SDT-based nanosystem with increased sonosensitizer permeability and oxygen content highly improved the tumor inhibition efficacy without toxic effects. This study presents a new paradigm for ECM depletion-based strategy of deep-seated penetration, and will expand the nanomedicine application of metalloporphyrin sonosensitizers in SDT.

Development of potent nanosized carbonic anhydrase inhibitor for targeted therapy of hypoxic solid tumors

Overexpression of two carbonic anhydrase (CA) isoforms, CA IX and XII, in several hypoxic solid tumors provides an extracellular hypoxic microenvironment, interferes with extra- and intracellular pH regulation, thus favoring hypoxic tumor cell survival, proliferation and metastasis. In the current study, a selective inhibitor for human CA isoforms IX and XII (isatin-bearing sulfonamide, WEG-104), was incorporated into nanosized spherical niosomes at high encapsulation efficiency to allow for an enhanced and sustained antitumor activity. In vivo, administration of WEG-104 that is either free (10 mg/kg) or loaded into niosomes (5 mg/kg) into a mice model of Ehrlich ascites solid tumor resulted in comparable efficacy in terms of reduction of tumor weight and volume. Administration of WEG-104-loaded niosomes (10 mg/kg) exhibited superior antitumor activity compared to the free drug, evidenced by reduced tumor weight and volume, marked reduction in the activity of CA IX and XII, and suppression of HIF-1α and MMP-2. Moreover, prominent increase of caspase 3 and pronounced decrease in VEGF immune expression were observed in the treated animals. Hence, loading of molecularly designed compounds that targets CAs in hypoxic solid tumors into nanosized delivery systems provided an auspicious strategy for limiting solid tumor progression and malignancy.

Nrf2 and Parkin-Hsc70 regulate the expression and protein stability of p62/SQSTM1 under hypoxia.

Solid tumors often contain regions with very low oxygen concentrations or hypoxia resulting from altered metabolism, uncontrolled proliferation, and abnormal tumor blood vessels. Hypoxia leads to resistance to both radio- and chemotherapy and a predisposition to tumor metastases. Under hypoxia, sequestosome 1 (SQSTM1/p62), a multifunctional stress-inducible protein involved in various cellular processes, such as autophagy, is down-regulated. The hypoxic depletion of p62 is mediated by autophagic degradation. We herein demonstrated that hypoxia down-regulated p62 in the hepatoma cell line Hep3B at the transcriptional and post-translational levels. At the transcriptional level, hypoxia down-regulated p62 mRNA by inhibiting nuclear factor erythroid 2-related factor 2 (Nrf2). The overexpression of Nrf2 and knockdown of Siah2, a negative regulator of Nrf2 under hypoxia, diminished the effects of hypoxia on p62 mRNA. At the post-translational level, the proteasome inhibitor MG132, but not the lysosomal inhibitors ammonium chloride and bafilomycin, prevented the hypoxic depletion of p62, suggesting the involvement of the proteasome pathway. Under hypoxia, the expression of the E3 ubiquitin ligase Parkin was up-regulated in a hypoxia-inducible factor 1α-dependent manner. Parkin ubiquitinated p62 and led to its proteasomal degradation, ensuring low levels of p62 under hypoxia. We demonstrated that the effects of Parkin on p62 required heat shock cognate 71kDa protein (Hsc70). We also showed that the overexpression of Nrf2 and knockdown of Parkin or Hsc70 induced the accumulation of p62 and reduced the viability of cells under hypoxia. We concluded that a decrease in p62, which involves regulation at the transcriptional and post-translational levels, is critical for cell survival under hypoxia. The present results show the potential of targeting Nrf2/Parkin-Hsc70-p62 as a novel strategy to eradicate hypoxic solid tumors.

CuS-131I-PEG Nanotheranostics-Induced "Multiple Mild-Hyperthermia" Strategy to Overcome Radio-Resistance in Lung Cancer Brachytherapy.

Brachytherapy is one mainstay treatment for lung cancer. However, a great challenge in brachytherapy is radio-resistance, which is caused by severe hypoxia in solid tumors. In this research, we have developed a PEGylated 131I-labeled CuS nanotheranostics (CuS-131I-PEG)-induced "multiple mild-hyperthermia" strategy to reverse hypoxia-associated radio-resistance. Specifically, after being injected with CuS-131I-PEG nanotheranostics, tumors were irradiated by NIR laser to mildly increase tumor temperature (39~40 °C). This mild hyperthermia can improve oxygen levels and reduce expression of hypoxia-induced factor-1α (HIF-1α) inside tumors, which brings about alleviation of tumor hypoxia and reversion of hypoxia-induced radio-resistance. During the entire treatment, tumors are treated by photothermal brachytherapy three times, and meanwhile mild hyperthermia stimulation is conducted before each treatment of photothermal brachytherapy, which is defined as a "multiple mild-hyperthermia" strategy. Based on this strategy, tumors have been completely inhibited. Overall, our research presents a simple and effective "multiple mild-hyperthermia" strategy for reversing radio-resistance of lung cancer, achieving the combined photothermal brachytherapy.

Photoactivatable metal organic framework for synergistic ferroptosis and photodynamic therapy using 450 nm laser

Photodynamic therapy (PDT) is an appealing treatment modality by producing reactive oxygen species (ROS) with photosensitizers (PSs) to induce cell apoptosis, but still suffering poor efficacy in treating hypoxic solid tumor. Herein, we have developed a nanocarrier (naming HAFeR) by encapsulating PSs and RSL3 in metal organic framework (MOF) for synergistic ferroptosis and PDT. HAFeR nanocarriers selectively recognized CD44 overexpressed on tumor cell surface, and were subsequently internalized via receptor mediated endocytosis. After transferring inside acidic lysosomes, nanocarriers were decomposed to release the payloads, including porphyrin sensitizers, Fe2+, Fe3+ and RSL3. Under 450 nm laser irradiation, the porphyrin produced more massive ROS to induce drastic cell apoptosis than 630 nm laser due to higher photon energy and stronger absorption. Meanwhile, exogenous iron ions catalyzed the conversion of H2O2 into O2 to alleviate tumor hypoxia via Fenton reaction, and also promoted RSL3 to downregulate GPX4 to induce lipid peroxidation (LPO), finally boosting ROS production for ferroptosis. By combining apoptosis and ferroptosis, HAFeR showed potent toxicity to tumor cells and efficiently eradicated the tumor in MB49 tumor-bearing nude mice under 450 nm laser, providing a potential strategy combining laser ablation and PDT within one system for future intraluminal and superficial tumor treatment.

Photoinduced Carbene for Effective Photodynamic Therapy Against Hypoxic Cancer Cells

Photoinduced Carbene for Effective Photodynamic Therapy Against Hypoxic Cancer Cells