Imaging tumor hypoxia:Blood-borne delivery of imaging agents is fundamentally different in hypoxia subtypes

Dedicated to the memory of Professor Briton Chance on the ccasion of his 100th birthday(July24 th,2013),and remembering mary erciting discussions on the orygenation of breast cancer,ontumor hyporia in general and imaging of the orygenation status of malignant tumors.Hypoxic tissue subvolumes are a hallmark feat ure of solid malignant tumors,relevant for cancertherapy and patient outcome because they increase both the intrinsic aggressiveness of tumor cells and their resist ance to several commonly used anticancer strategies.Pathogenetic mech-anisms leading to hypoxia are diverse,may coexist within the same tumor and are commonlygrouped according to the duration of their ffects.Chronic hypoxia is mainly caused by difusionlimitations resulting from enlarged intercapilary distances and adverse difusion geometriesand--to a lsser extent--by hypoxemia,compromised perfusion or long-lasting microregionalfow stops.Conversely,acute hypoxia preferentilly results from transient disruptions in per.fusion.While each of these features of the tumor microenvironment can contribute to a criticalreduction of oxy gen availability,the delivery of imaging agents(as well as nutrients and anti-cancer agents)may be compromised or remain unaffected,Thus,a critial appraisal of the ffectsof the various mechanisms leading to hypoxia with regard to the blood-bome delivery of imagingagents is necessary to judge their ability to correctly represent the hypoxic phenotype of solidmalignancies.

Bioreductive prodrugs as cancer therapeutics:targeting tumor hypoxia

Hypoxia, a state of low oxygen, is a common feature of solid tumors and is associated with disease progression as well as resistance to radiotherapy and certain chemotherapeutic drugs. Hypoxic regions in tumors, therefore, represent attractive targets for cancer therapy. To date, five distinct classes of bioreactive prodrugs have been developed to target hypoxic cells in solid tumors. These hypoxia-activated prodrugs, including nitro compounds, N-oxides, quinones, and metal complexes, generally share a common mechanism of activation whereby they are reduced by intracellular oxidoreductases in an oxygensensitive manner to form cytotoxins. Several examples including PR-104, TH-302, and EO9 are currently undergoing phase II and phase III clinical evaluation. In this review, we discuss the nature of tumor hypoxia as a therapeutic target, focusing on the development of bioreductive prodrugs. We also describe the current knowledge of how each prodrug class is activated and detail the clinical progress of leading examples.

[(99m)~Tc(CO)_3]^+ labeled histidine derivative containing 4-nitroimidazole:Synthesis,biodistribution as a tumor hypoxia imaging agent

A novel histidine derivative containing 4-nitroimidazole,(S)-2-(4-((4-nitro-1H-imidazol-1-yl) methyl) benzamido)-3-(1H-imidazol-4-yl)propanoic acid (His-NI),was synthesized and labeled with [99mTc(CO)3(H2O)3]+.The tricarbonyl technetium complex,the 99mTc(CO)3-His-NI,showed a 99% yield under mild conditions at a low His-NI ligand concentration of 10-4 molL-1,and its biodistribution in mice bearing S180 tumor had a selective accumulation in tumor (2.01±0.40%ID/g at 1 h postinjection) and a slow clearance.The tumor/muscle ratio was 1.64 at 1 h,3.10 at 4 h,and 3.88 at 24 h,indicating that the 99mTc(CO)3-His-NI has a potential to image tumor hypoxia.

Synthesis of fluorinated CaCO_(3)-based oxygen-supplying nanophotosensitizers to potentiate photodynamic immunotherapy by reversing tumor hypoxia and immunosuppression

Photodynamic therapy is a noninvasive type of phototherapy with a high capacity to boost specific antitumor immunity by causing immunogenic cell death.However,the photodynamic therapeutic potency toward solid tumors is dampened by tumor hypoxia that negatively impairs the generation of cytotoxic singlet oxygen and promotes the formation of tumor immunosuppression.Herein,fluorinated CaCO_(3)(CaF)nanoparticles are prepared with the addition of dopamine-conjugated perfluorosebacic acid and ferric chloride into a calcium chloride ethanol solution via an ammonium bicarbonate-mediated gas-diffusion process.After being coated with commercial lipids and hexadecylamin conjugated chlorin e6(hCe6)via a templated self-assembly process,the yielded PEGylated nanophotosensitizer(hCe6@CaF-PEG)exhibits an effective loading efficiency to perfluoro-15-crown-5-ether(PFCE),a model perfluorocarbon molecule,and thus oxygen molecules.Upon intravenous administration,the obtained PFCE/hCe6@CaF-PEG can alleviate tumor hypoxia by working as an oxygen nanoshuttle.Together with local light emitting diode light exposure,photodynamic treatment with PFCE/hCe6@CaF-PEG can suppress the growth of primary CT26 tumors and unirradiated distant tumors,particularly when synergized with anti-PD-1(aPD-1)immunotherapy to collectively reverse tumor immunosuppression.This work presents an effective strategy to potentiate photodynamic immunotherapy by concurrently reversing tumor hypoxia and immunosuppression.

Liposomes co-loaded with metformin and chlorin e6 modulate tumor hypoxia during enhanced photodynamic therapy

Though photodynamic therapy （PDT） has been widely used in the non-invasive destruction of solid tumors, the therapeutic efficacy of PDT is often limited by the hypoxic tumor environment. Herein, we report the innovative use of metformin, an oral hypoglycemic agent commonly used in the treatment of type II diabetes, to improve tumor oxygenation, and overcome tumor hypoxia-associated resistance to PDT. In our design, hydrophilic metformin and modified hydrophobic chlorin e6 （HCe6） are co-encapsulated within the inner cavity and outer membrane of liposomes, respectively. Due to the high uptake of liposome nanoparticles by tumors, and the sustained release of metformin, the intravenous administration of metformin （Met）-HCe6-Liposome nanoparticles greatly improves tumor oxygena- tion in several different tumor models, as revealed by in vivo photoacoustic imaging and ex vivo immunofluorescence staining. Systemic administration of Met-HCe6-Liposomes followed by in vivo PDT achieved significantly improved therapeutic effects compared to that of PDT without metformin. Hence, our study represents a new strategy for the improvement of PDT efficacy through the modulation of tumor oxygenation by clinically approved agents.

Phospholipid membrane-decorated deep-penetrated nanocatalase relieve tumor hypoxia to enhance chemo-photodynamic therapy

Hypoxia is a serious impediment to current treatments of many malignant tumors.Catalase,an antioxidant enzyme,is capable of decomposing endogenous hydrogen peroxide(H2O2)into oxygen for tumor reoxygenation,but suffered from in vivo instability and limited delivery to deep interior hypoxic regions in tumor.Herein,a deep-penetrated nanocatalase-loading DiIC18(5,DiD)and soravtansine(Cat@PDS)were provided by coating catalase nanoparticles with PEGylated phospholipids membrane,stimulating the structure and function of erythrocytes to relieve tumor hypoxia for enhanced chemophotodynamic therapy.After intravenous administration,Cat@PDS preferentially accumulated at tumor sites,flexibly penetrated into the interior regions of tumor mass and remarkably relieved the hypoxic status in tumor.Notably,the Cat@PDS+laser treatment produced striking inhibition of tumor growth and resulted in a 97.2%suppression of lung metastasis.Thus,the phospholipids membrane-coated nanocatalase system represents an encouraging nanoplatform to relieve tumor hypoxia and synergize the chemophotodynamic cancer therapy.

Design strategy of optical probes for tumor hypoxia imaging

Clinical manifestations of tumors indicate that malignant phenotypes developing in the hypoxic microenvironment lead to resistance to cancer treatment, rendering chemotherapy, radiotherapy, and photodynamic therapy less sensitive and effective in patients with tumor. Visualizing the oxygen level in the tumor environment has garnered much attention due to its implications in precision tumor therapy. Following the rapid development of biomaterials in nanotechnology, various nanomaterials have been designed to visualize the oxygen levels in tumors. Here, we review recent research on detecting oxygen levels in solid tumors for tumor hypoxia imaging. To monitor the hypoxic level of tumors, two main strategies were investigated: directly detecting oxygen levels in tumors and monitoring the hypoxia-assisted reduced microenvironment. We believe that hypoxia as a tumor-specific microenvironment can be a breakthrough in the clinical treatment of tumors.

Arginine-peptide complex-based assemblies to combat tumor hypoxia for enhanced photodynamic therapeutic effect

Tumor hypoxia is one of the major factors restricting the photodynamic therapy(PDT)efficacy.To address this problem,we designed an arginine-peptide complex,namely Fluorenylmethoxycarbonyl-Leucine-Leucine-Leucine-Arginine-OH(Fmoc-L_(3)-Arg),which is able to co-assemble with 5,10,15,20-Tetrakis(4-hydroxyphenyl)porphyrin(THPP)into stable nanoparticles(NPs)with uniform and spherical shapes.The THPP/Fomc-L_(3)-Arg NPs were ultra-sensitive to tumorous acidic and oxidative conditions,and could rapidly release photosensitizers in tumor cells.Meanwhile,the co-loaded Fmoc-L_(3)-Arg could efficiently generate nitric oxide(NO),inhibiting mitochondrial cellular respiration and increasing oxygen in tumor cells to support the profound improvement of reactive oxygen species(ROS)yield and PDT efficacy.After intravenous injection,the THPP/Fomc-L_(3)-Arg NPs greatly accumulated at tumor tissue and significantly inhibited tumor growth upon irradiation.In conclusion,such an arginine-peptide complex-based nanoassembly addresses the inevitable problem of hypoxia-induced tumor resistance to PDT.

Hypothetical hypoxia-driven rapid disease progression in hepatocellular carcinoma post transarterial chemoembolization:A case report

BACKGROUND Transarterial chemoembolization(TACE)is widely performed for intermediatestage or unresectable hepatocellular carcinoma(HCC),but approximately half of patients do not respond to TACE treatment.We describe a case of rapidly progressing of HCC after TACE and provide a possible hypothesis for this condition.The finding may contribute to identifying patients who obtain less benefit from TACE,thus avoiding the unnecessary waste of medical resources and treatment during the golden hour window.CASE SUMMARY A 61-year-old woman had been diagnosed with chronic hepatitis B infection and HCC at Barcelona Clinic Liver Cancer stage B,which had been treated by segmental hepatectomy 14 mo ago.The tumor recurred in the two months after surgery.She received an initial TACE and then underwent systemic therapy with lenvatinib 8 mg daily due to an increased level of alpha-fetoprotein(AFP)after the first TACE.However,the tumor continued to progress with an increased level of AFP,and she underwent a second TACE,after which the tumor volume did not obviously decrease on the contrast-enhanced computed tomography image.One month later,she had a third TACE to control the residual HCC tumors.Two weeks after that,the HCC had increased dramatically with tea-colored urine and yellowish skin turgor.Eventually,the patient refused further treatment and went into hospice care.CONCLUSION Intense hypoxia induced by TACE can trigger rapid disease progression in infiltrative HCC patients with a large tumor burden.

Low hypoxia inducible factor-1α(HIF-1α)expression in testicular germ cell tumors--a major reason for enhanced chemosensitivity?

The molecular basis for enhanced chemosensitivity of testicular germ cell tumors （GCT） has been an area of great interest, as it could potentially give us therapeutic leads in other resistant malignancies. Thus far, however, the increased sensitivity of C＆T has been variously attributed to multiple factors -- an inability to detoxify cisplatin, a lack of export pumps, an inability to repair the DNA damage, an intact apoptotic cascade and lack of p53 mutation; but a unifying underlying etiology leading to the aforementioned processes and having a translational implication has so far been elusive. Herein, we offer evidence to support a potential significant role for the previously demonstrated low hypoxia inducible factor-la （HIF-la） expression in mediating the general exquisite chemosensitivity of testicular GCT, through the aforementioned processes. This molecular mechanism based hypothesis could have a significant translational implication in platinum refractory GCT as well as other platinum resistant malignancies.

Epigenetic Tumor Response to Hypoxia: An Epimutation Pattern and a Method of Multi Targeted Epigenetic Therapy (MTET)

In most cases, cancer develops as a result of non-inheritable somatic mutations (epimutations), acquired by the individual adult cell, during the evolution of the cell, and propagated into an expanding clone of progeny of the cells by natural selection [1]. The role of microenvironment in selection for such acquired mutations, or epimutations, is a focus of scientific research in carcinogenesis [2]. Here we describe a defective DNA response to hypoxia due to epigenetic aberrancies, in cancer cellular biology [3]. We also summarize a literature review on hypoxia mediated epigenetic responses, and its role in carcinogenesis and metastasis. Further, we review a novel method of treating hypoxic solid tumors with a combination of epigenetic modifiers with both in vitro and in vivo results in human, translating to an improved prognosis and clinical outcome. We propose that this approach both independently and synergistically (with the current standard of care) can provide an improved outcome.

二甲双胍阻断乳腺癌细胞-间质细胞的交互作用:基于抑制肿瘤相关成纤维细胞缺氧诱导因子-1α的表达

目的探讨二甲双胍(Met)对乳腺癌肿瘤-间质细胞交互作用的影响及机制。方法将肿瘤相关成纤维细胞(CAFs)与乳腺癌细胞共培养,运用二甲双胍进行干预,分为对照组和Met干预组,ELISA及RT-qPCR检测Met对CAFs中HIF-1α、p-AMPK、基质衍生因子-1(SDF-1)和白细胞介素-8(IL-8)等因子的表达变化以及Transwell检测肿瘤细胞侵袭能力的变化。运用外源性SDF-1、IL-8干预后,Transwell检测肿瘤细胞侵袭能力的变化。运用缺氧诱导因子-1α(HIF-1α)shRNA或过表达质粒调节CAFs-HIF-1α的表达,以及AMPK-shRNA抑制AMPK的表达,并运用OG和2-OXO调节脯氨酸羟化酶的表达,及运用外源性TGF-β1干预后,Western blot及RT-qPCR检测CAFs中p-AMPK、HIF-1α、SDF-1、IL-8的表达,Transwell检测肿瘤细胞侵袭能力的变化。结果相较于对照组,Met干预组中CAFs的p-AMPK、SDF-1和IL-8的表达水平升高(P<0.05),HIF-1α表达水平下降(P<0.05),AMPK的表达水平差异无统计学意义(P>0.05),Met组中乳腺癌细胞侵袭能力下降(P<0.05)。外源性SDF-1、IL-8干预可降低Met对乳腺癌细胞侵袭的抑制作用,增加乳腺癌细胞的侵袭能力(P<0.05)。过表达HIF-1α及运用脯氨酸羟化酶抑制剂OG提高HIF-1α的表达后,可降低Met对CAFs中HIF-1α、SDF-1及IL-8表达的抑制作用,并可降低Met对乳腺癌细胞侵袭的抑制作用(P<0.05);运用HIF-1α-shRNA及运用脯氨酸羟化酶激活剂2-OXO抑制HIF-1α的表达后,降低乳腺癌细胞的侵袭能力(P<0.05);运用AMPK-shRNA抑制p-AMPK的表达后,可降低Met对CAFs中HIF-1α表达的抑制作用,并可降低Met对乳腺癌细胞侵袭的抑制作用(P<0.05);加入外源性TGF-β1后,可部分降低Met对CAFs中HIF-1α表达的抑制作用,并可部分降低Met对乳腺癌细胞侵袭的抑制作用(P<0.05)。结论Met通过抑制CAFs-HIF-1α的表达进而发挥阻断乳腺癌细胞-间质细胞交互作用。

改善肿瘤缺氧耐药的血红蛋白-紫杉醇脂质体的制备及体外评价

目的制备改善肿瘤缺氧耐药的血红蛋白-紫杉醇脂质体。方法采用薄膜法制备血红蛋白-紫杉醇脂质体,通过纳米粒度仪考察其粒径、Zeta电位、多分散系数,通过高效液相色谱仪检测其包封率,并通过体外细胞实验评价其与肿瘤细胞的相互作用。结果血红蛋白-紫杉醇脂质体的最优制备条件为:磷脂总量为36 mM,DPPC∶DOPE∶胆固醇摩尔比为7∶2∶1,紫杉醇用量为3 mg,水化介质为3 mg·mL^(-1)Hb-PBS溶液,水化温度为室温,水化时间为0.5 h;平均粒径为(189.17±8.22)nm,多分散系数为0.14±0.023,紫杉醇包封率为(58.27±2.55)%,血红蛋白含量为(0.63±0.05)mg·mL^(-1)。体外细胞实验中,血红蛋白-紫杉醇脂质体对肿瘤细胞的杀伤作用约为紫杉醇脂质体的1.5倍、被肿瘤细胞摄取量约为紫杉醇脂质体的1.2倍及ROS生成量约为紫杉醇脂质体的1.8倍。结论制备了血红蛋白-紫杉醇脂质体,通过细胞实验证明其能通过改善缺氧、增加ROS产生促进肿瘤细胞凋亡,有望为肿瘤缺氧导致的耐药抵抗提供安全有效的新方法。

中药抑制缺氧诱导因子-1α相关信号通路的抗肿瘤作用研究进展

缺氧是实体肿瘤的常见特征,缺氧微环境可引起缺氧诱导因子-1(HIF-1)过表达。HIF-1α是缺氧应答中至关重要的转录调控因子,在各类肿瘤组织中均过表达,其在肿瘤细胞的增殖、侵袭转移、血管生成、糖酵解和免疫中发挥重要作用并参与多种转导通路。因此,HIF-1α作为治疗实体肿瘤的潜在靶点,颇有应用前景。相较于HIF-1α抑制剂存在高毒性、低效性的问题,中药具有多靶点、低毒性、高耐受性等优势,在肿瘤治疗中有广泛的应用前景。

缺氧诱导因子-1α在恶性肿瘤中的研究进展

肿瘤患者死亡的主要原因之一是癌细胞的侵袭和迁移,且迁移能力主要取决于局部肿瘤微环境。缺氧是影响肿瘤微环境的关键条件。在缺氧环境中,缺氧诱导因子-1α(HIF-1α)过表达可加速肿瘤进展,且与患者不良预后有关。HIF-1α通过调节靶基因的表达参与肿瘤发展的关键过程。目前证据表明,HIF-1α可促进大多数肿瘤的发生发展。深入了解HIF-1α诱导肿瘤的机制,寻找有效的转化治疗方法,对于恶性肿瘤的早期诊断、提高治愈率和延长患者生存期至关重要。此外,抑制HIF-1α可能成为未来肿瘤治疗的关键靶点。

血府逐瘀汤对人食管癌ECA-109荷瘤裸鼠肿瘤血管的影响

目的:观察血府逐瘀汤对荷瘤裸鼠肿瘤组织血管的影响。方法:采用人源食管癌细胞ECA-109构建裸鼠食管癌皮下移植瘤模型,造模后将45只裸鼠随机分为对照组和血府逐瘀汤低、高剂量组,各15只。对照组给予0.9%氯化钠溶液灌胃,血府逐瘀汤低、高剂量组分别给予1.2、4.8 g/mL血府逐瘀汤灌胃,各组连续干预14 d后剥离肿瘤组织。计算肿瘤体积及抑瘤率;通过免疫荧光法检测肿瘤血管密度、α-SMA阳性细胞覆盖率、Collegen-Ⅳ覆盖率、CD31阳性率和血管渗漏率;免疫组化法检测肿瘤组织乏氧区域面积。结果:血府逐瘀汤高、低剂量组在抑瘤率、微血管密度、α-SMA阳性细胞覆盖率、Collegen-Ⅳ覆盖率与对照组相比均显著改善(P<0.01,P<0.05),血管渗漏率及肿瘤乏氧区域面积比均低于对照组(P<0.01)。结论:血府逐瘀汤能抑制人源食管癌皮下移植瘤生长,可以改善肿瘤血管的功能和结构及肿瘤组织的乏氧状态,能一定程度促进肿瘤血管正常化。

3D numerical study of tumor blood perfusion and oxygen transport during vascular normalization

The changes of blood perfusion and oxygen transport in tumors during tumor vascular normalization are studied with 3-dimensional mathematical modeling and numerical simulation. The models of tumor angiogenesis and vascular-disrupting are used to simulate ＂un-normalized＂ and ＂normalized＂ vasculatures. A new model combining tumor hemodynamics and oxygen transport is developed. In this model, the intravasculartransvascular-interstitial flow with red blood cell（RBC） delivery is tightly coupled, and the oxygen resource is produced by heterogeneous distribution of hematocrit from the flow simulation. The results show that both tumor blood perfusion and hematocrit in the vessels increase, and the hypoxia microenvironment in the tumor center is greatly improved during vascular normalization. The total oxygen content inside the tumor tissue increases by about 67%, 51%, and 95% for the three approaches of vascular normalization,respectively. The elevation of oxygen concentration in tumors can improve its metabolic environment, and consequently reduce malignancy of tumor cells. It can also enhance radiation and chemotherapeutics to tumors.

血红蛋白类氧载体在肿瘤治疗领域中的应用进展

大多数实体肿瘤内血流和氧气供氧不足,缺氧微环境会加速肿瘤恶化,影响肿瘤预后。因此,改善肿瘤组织的氧合状态对提高肿瘤治疗敏感性和有效性至关重要。血红蛋白类氧载体(hemoglobin-based oxygen carriers, HBOCs)是一类携释氧纳米粒子,可到达正常红细胞难以通过的障碍性微循环小血管,为缺氧的组织器官输送氧气。已有研究证明,HBOCs作为1种潜在的纳米级高效携/释氧剂应用于肿瘤治疗可以增加组织氧合,在肿瘤治疗领域具有巨大应用前景。本文综述了缺氧在肿瘤中的影响,并重点介绍了血红蛋白类氧载体在肿瘤放疗、化疗、新型动力学治疗和免疫治疗领域的应用进展及可能机制。

厌氧菌介导的肿瘤微环境响应型纳米粒子增强肺癌疗效

目的传统化疗药物不能在肿瘤内部维持高浓度,导致肺癌临床疗效降低,毒副作用严重。本研究的目的是开发一种由厌氧菌介导的新型纳米药物提升肿瘤组织药物浓度并提高治疗效果。方法合成一种可降解聚合物并制备婴儿双歧杆菌抗体修饰的阿霉素纳米粒子(Ab-DOX-s-s-NPS),体外表征其形貌、药物释放行为和细胞摄取能力;建立A549肺癌荷瘤小鼠模型,评价该纳米粒抑制肿瘤生长的效果,并考察其毒副反应。结果透射电镜(transmission electron microscopy,TEM)图像及凝胶电泳蛋白图谱等证实Ab-DOX-s-s-NPS纳米粒子的成功制备,粒径约为85.6±1.4 nm,它能与细菌良好结合;在高谷胱甘肽(glutathione,GSH)环境中能快速释放药物并被肿瘤细胞摄取;通过预植入的双歧杆菌为靶标,该纳米粒子在荷瘤小鼠体内能主动富集到肿瘤缺氧区域,显著抑制肿瘤生长,延长小鼠生存时间;且与游离阿霉素造成的心肌纤维化相比,纳米药物组没有造成显著的心脏毒性和肝肾功能损伤。结论本研究制备的Ab-DOX-s-s-NPS纳米粒子具有还原响应性,能通过双歧杆菌的招募主动靶向富集到肿瘤组织,对肺癌移植瘤具有优异的抗肿瘤效果,有望成为治疗其他恶性实体瘤的候选药物。

Hypoxia and its impact on the tumour microenvironment of gastroesophageal cancers

The malfeasant role of the hypoxic tumour microenvironment(TME)in cancer progression was recognized decades ago but the exact mechanisms that augment the hallmarks of cancer and promote treatment resistance continue to be elucidated.Gastroesophageal cancers(GOCs)represent a major burden of worldwide disease,responsible for the deaths of over 1 million people annually.Disentangling the impact of hypoxia in GOCs enables a better overall understanding of the disease pathogenesis while shining a light on novel therapeutic strategies and facilitating precision treatment approaches with the ultimate goal of improving outcomes for patients with these diseases.This review discusses the underlying principles and processes of the hypoxic response and the effect of hypoxia in promoting the hallmarks of cancer in the context of GOCs.We focus on its bidirectional influence on inflammation and how it drives angiogenesis,innate and adaptive immune evasion,metastasis,and the reprogramming of cellular bioenergetics.The contribution of the hypoxic GOC TME to treatment resistance is examined and a brief overview of the pharmacodynamics of hypoxiatargeted therapeutics is given.The principal methods that are used in measuring hypoxia and how they may enhance prognostication or provide rationale for individually tailored management in the case of tumours with significant hypoxic regions are also discussed.