Olaparib nanoparticles potentiated radiosensitization effects on lung cancer

Progression in low-intensity ultrasound-induced tumor radiosensitization

BACKGROUND

Radiotherapy (RT) is a widely utilized tumor treatment approach, while a significant obstacle in this treatment modality is the radioresistance exhibited by tumor cells. To enhance the effectiveness of RT, scientists have explored radiosensitization approaches, including the use of radiosensitizers and physical stimuli. Nevertheless, several approaches have exhibited disappointing results including adverse effects and limited efficacy. A safer and more effective method of radiosensitization involves low-intensity ultrasound (LIUS), which selectively targets tumor tissue and enhances the efficacy of radiation therapy.

METHODS

This review summarized the tumor radioresistance reasons and explored LIUS potential radiosensitization mechanisms. Moreover, it covered diverse LIUS application strategies in radiosensitization, including the use of LIUS alone, ultrasound-targeted intravascular microbubble destruction, ultrasound-mediated targeted radiosensitizers delivery, and sonodynamic therapy. Lastly, the review presented the limitations and prospects of employing LIUS-RT combined therapy in clinical settings, emphasizing the need to connect research findings with practical applications.

RESULTS AND CONCLUSION

LIUS employs cost-effective equipment to foster tumor radiosensitization, curtail radiation exposure, and elevate the quality of life for patients. This efficacy is attributed to LIUS's ability to utilize thermal, cavitation, and mechanical effects to overcome tumor cell resistance to RT. Multiple experimental analyses have underscored the effectiveness of LIUS in inducing tumor radiosensitization using diverse strategies. While initial studies have shown promising results, conducting more comprehensive clinical trials is crucial to confirm its safety and effectiveness in real-world situations.

Application of nano-radiosensitizers in non-small cell lung cancer

Radiotherapy stands as a cornerstone in the treatment of numerous malignant tumors, including non-small cell lung cancer. However, the critical challenge of amplifying the tumoricidal effectiveness of radiotherapy while minimizing collateral damage to healthy tissues remains an area of significant research interest. Radiosensitizers, by methods such as amplifying DNA damage and fostering the creation of free radicals, play a pivotal role in enhancing the destructive impact of radiotherapy on tumors. Over recent decades, nano-dimensional radiosensitizers have emerged as a notable advancement. Their mechanisms include cell cycle arrest in the G2/M phase, combating tumor hypoxia, and others, thereby enhancing the efficacy of radiotherapy. This review delves into the evolving landscape of nanomaterials used for radiosensitization in non-small cell lung cancer. It provides insights into the current research progress and critically examines the challenges and future prospects within this burgeoning field.

Combining Olaparib and Ascorbic Acid on Nanoparticles to Enhance the Drug Toxic Effects in Pancreatic Cancer

Introduction

Pancreatic cancer (PC) shows a very poor response to current treatments. Development of drug resistance is one of the causes of the therapy failure, being PARP1 (poly ADP-ribose polymerase 1) a relevant protein in the resistance mechanism. In this work, we have functionalized calcium phosphate-based nanoparticles (NPs) with Olaparib (OLA, a PARP-1 inhibitor) in combination with ascorbic acid (AA), a pro-oxidative agent, to enhance their individual effects.

Methods

Amorphous Calcium Phosphate (ACP) NPs were synthesized through a biomimetic approach and then functionalized with OLA and AA (NP-ACP-OLA-AA). After evaluation of the loading capacity and release kinetic, cytotoxicity, cell migration, immunofluorescence, and gene expression assays were performed using pancreatic tumor cell lines. In vivo studies were carried out on tumors derived from the PANC-1 line in NOD SCID gamma (NSG) mice.

Results

NP-ACP-OLA-AA was loaded with 13%wt of OLA (75% loading efficiency) and 1% of AA, respectively. The resulting dual nanosystem exhibited a gradual release of OLA and AA, being the latter protected from degradation in solution. This ensured the simultaneous availability of OLA and AA for a longer period, at least, during the entire time of in vitro cell experiments (72 hours). In vitro studies indicated that NP-ACP-OLA-AA showed the best cytotoxic effect outperforming that of the free OLA and a higher genotoxicity and apoptosis-mediated cytotoxic effect in human pancreatic ductal adenocarcinoma cell line. Interestingly, the in vivo assays using immunosuppressed mice with PANC-1-induced tumors revealed that NP-ACP-OLA-AA produced a higher tumor volume reduction (59.1%) compared to free OLA (28.3%) and increased the mice survival.

Conclusion

Calcium phosphate NPs, a highly biocompatible and biodegradable system, were an ideal vector for the OLA and AA co-treatment in PC, inducing significant therapeutic benefits relative to free OLA, including cytotoxicity, induction of apoptosis, inhibition of cell migration, tumor growth, and survival.

Chitosan Thermosensitive Hydrogel Based on DNA Damage Repair Inhibition and Mild Photothermal Therapy for Enhanced Antitumor Treatment

The DNA damage repair of tumor cells limits the effect of photothermal therapy (PTT), and high temperatures induced by PTT can damage adjacent normal tissues. To overcome these limitations, we developed a novel composite hydrogel (OLA-Au-Gel) based on chitosan (CS) and β-glycerophosphate (β-GP), which encapsulated olaparib-liposomes (OLA-lips) and CS-capped gold nanoparticles (CS-AuNPs). OLA-Au-Gel achieved the combination of mild PTT (mPTT) by CS-AuNPs and tumor DNA damage repair inhibition by OLA. The hydrogel showed good biocompatibility, injectability, and photothermal response. Under near-infrared laser irradiation, OLA-Au-Gel inhibited the proliferation of tumor cells, induced the generation of reactive oxygen species in vitro, and effectively inhibited the growth of breast tumors in vivo. OLA-Au-Gel shows a promising application prospect for inhibiting tumor development and improving the antitumor effect. Collectively, we propose a novel strategy for enhanced antitumor therapy based on the combination of mPTT and DNA damage repair inhibition.

Nanotechnology-empowered lung cancer therapy: From EMT role in cancer metastasis to application of nanoengineered structures for modulating growth and metastasis

Lung cancer is one of the leading causes of death in both males and females, and it is the first causes of cancer-related deaths. Chemotherapy, surgery and radiotherapy are conventional treatment of lung cancer and recently, immunotherapy has been also appeared as another therapeutic strategy for lung tumor. However, since previous treatments have not been successful in cancer therapy and improving prognosis and survival rate of lung tumor patients, new studies have focused on gene therapy and targeting underlying molecular pathways involved in lung cancer progression. Nanoparticles have been emerged in treatment of lung cancer that can mediate targeted delivery of drugs and genes. Nanoparticles protect drugs and genes against unexpected interactions in blood circulation and improve their circulation time. Nanoparticles can induce phototherapy in lung cancer ablation and mediating cell death. Nanoparticles can induce photothermal and photodynamic therapy in lung cancer. The nanostructures can impair metastasis of lung cancer and suppress EMT in improving drug sensitivity. Metastasis is one of the drawbacks observed in lung cancer that promotes migration of tumor cells and allows them to establish new colony in secondary site. EMT can occur in lung cancer and promotes tumor invasion. EMT is not certain to lung cancer and it can be observed in other human cancers, but since lung cancer has highest incidence rate, understanding EMT function in lung cancer is beneficial in improving prognosis of patients. EMT induction in lung cancer promotes tumor invasion and it can also lead to drug resistance and radio-resistance. Moreover, non-coding RNAs and pharmacological compounds can regulate EMT in lung cancer and EMT-TFs such as Twist and Slug are important modulators of lung cancer invasion that are discussed in current review.

Novel Implications of Nanoparticle-Enhanced Radiotherapy and Brachytherapy: Z-Effect and Tumor Hypoxia

Radiotherapy and internal radioisotope therapy (brachytherapy) induce tumor cell death through different molecular signaling pathways. However, these therapies in cancer patients are constrained by dose-related adverse effects and local discomfort due to the prolonged exposure to the surrounding tissues. Technological advancements in nanotechnology have resulted in synthesis of high atomic elements such as nanomaterials, which can be used as radiosensitizers due to their photoelectric characteristics. The aim of this review is to elucidate the effects of novel nanomaterials in the field of radiation oncology to ameliorate dose-related toxicity through the application of ideal nanoparticle-based radiosensitizers such as Au (gold), Bi (bismuth), and Lu (Lutetium-177) for enhancing cytotoxic effects of radiotherapy via the high-Z effect. In addition, we discuss the role of nanoparticle-enhanced radiotherapy in alleviating tumor hypoxia through the nanodelivery of genes/drugs and other functional anticancer molecules. The implications of engineered nanoparticles in preclinical and clinical studies still need to be studied in order to explore potential mechanisms for radiosensitization by minimizing tumor hypoxia, operational/logistic complications and by overcoming tumor heterogeneity in radiotherapy/brachytherapy.

PARP targeted Auger emitter therapy with [125I]PARPi-01 for triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) lacks biomarkers for targeted therapy. Auger emitters display the best therapeutic effect, if delivered directly into the nucleus proximal to DNA. The nuclear protein Poly (ADP-ribose)-Polymerase 1 (PARP1) is a suitable target against which few inhibitors (PARPi) are clinically approved for treatment of breast cancer with germline BRCA mutation (BRCA^mut). In this study, a theranostic approach was investigated in a TNBC xenografted mouse model by radiolabelling a close derivative of a PARPi Olaparib (termed PARPi-01) with the Auger emitters ^123/125I.

METHODS

TNBC cell line MDA-MB-231 was subcutaneously implanted in female NOD/SCID mice. At a tumour size of ~ 500mm³, [¹²³I]PARPi-01 was administered intravenously, and SPECT/CT images were obtained at 4 h or 24 h post injection (p.i). A therapy study was performed with [¹²⁵I]PARPi-01 in 4 doses (10 MBq/dose, 10 days apart). Tumour growth was monitored by CT scans longitudinally once per week. Upon reaching study endpoint, tissues were harvested and stained with TUNEL assay for detection of apoptosis induction.

RESULTS

SPECT/CT images showed rapid hepatobiliary tracer clearance at 4 h post injection (p.i.). Retention in thyroid at 24 h p.i. suggested tracer deiodination in vivo. The tumour and liver uptake were 0.2%ID/g and 2.5%ID/g, respectively. The tumour: blood ratio was 1.3. Endogenous therapy induced a significant delay in tumour growth (doubling time increased from 8.3 to 14.2 days), but no significant survival advantage. Significantly higher apoptosis ratio was observed in [¹²⁵I]PARPi-01 treated tumour tissues. No radiotoxicity was detected in the liver and thyroid.

CONCLUSION

Considering the radio-cytotoxic effect in the tumour tissue and a delay on tumour doubling time, [¹²⁵I]PARPi-01 presents a potential radiotherapeutics for treatment of TNBC. Improvements to overcome the suboptimal pharmacokinetics are necessary for its potential clinical application.

The Current State of the Art in PARP Inhibitor-Based Delivery Nanosystems

Poly (adenosine diphosphate [ADP]–ribose) polymerases inhibitors (PARPi), the first clinically approved drug that exhibits synthetic lethality, are moving to the forefront of cancer treatments. Currently, the oral bioavailability of PARPi is quite low; thus, it is a major challenge to effectively and safely deliver PARPi during clinical cancer therapy. Nanotechnology has greatly advanced the development of drug delivery. Based on the basic characteristics and various forms of nanoparticles, drug delivery systems can prolong the time that drugs circulate, realize the controlled release of drugs, provide drugs with an active targeting ability, and spatiotemporally present combination treatment. Furthermore, nanosystems may not only enhance drug efficiency but also reduce adverse side effects. This review focuses on strategies involving nanoparticle-based delivery for PARPi, including single administration and codelivery with other agents. We believe that nanosystems have great potential in advancing PARPi efficacy for cancer therapy.

Poly-Lactide-Co-Glycolide-Polyethylene Glycol-Ginsenoside Rg3-Ag Exerts a Radio-Sensitization Effect in Non-Small Cell Lung Cancer

Radiotherapy is an effective anti-cancer therapy for patients with non-small cell lung cancer (NSCLC), however, the prognosis is unsatisfactory owing to radio-resistance and toxicity. It is crucial to improve radiotherapy efficacy. Ag nanoparticles (NPs) and ginsenoside Rg3 (Rg3) exerted antitumor and radio-sensitization effects. Therefore, we investigated whether poly-lactide-co-glycolide-polyethylene glycol (PLGA-PEG)-Rg3-Ag will function as a noninvasive, tracing, radiotherapy sensitizer. The morphology of NPs was visualized with transmission electron microscopy (TEM). The drug loading content, encapsulation efficiency, and cumulative drug release of Rg3 was determined by HPLC. Cellular uptake of NPs in A549 and SPCA-1 was measured by immunostaining. The radio-sensitization effect of PLGA-PEG-Rg3-Ag in vitro was determined in A549 by detecting proliferation, colony formation, and apoptosis with CCK-8, clonogenic survival assay, and flow cytometry, while in vivo was determined in nude mice by testing the body weight and tumor volume. PLGA-PEG-Rg3-Ag exerted radio-sensitization effect by reducing cell proliferation and colony formation while enhancing cell apoptosis in A549; reduced tumor volume in nude mice. PLGA-PEG-Rg3-Ag exhibits radio-sensitization effects in NSCLC.

Olaparib@human serum albumin nanoparticles as sustained drug-releasing tumor-targeting nanomedicine to inhibit growth and metastasis in the mouse model of triple-negative breast cancer

Poly(ADP-ribose) polymerase inhibitor olaparib demonstrated therapeutic effectiveness in highly metastatic triple-negative breast cancer (TNBC). However, olaparib offers a weak therapeutic response in wild-type BRCA cancers due to the drug's poor bioavailability. Here, a bioinspired/active-tumor targeted nanoparticles system of human serum albumin with physical entrapment of olaparib was prepared via a low-energy desolvation technique using the crosslinker glutaraldehyde. The developed OLA@HSA NPs were nanosize (∼140 nm), kinetically stable with a low polydispersity (0.3), exhibited olaparib entrapment (EE 76.01 ± 2.53%, DL 6.76 ± 0.22%), and sustained drug release at pH 7.4 with an enhancement of drug release in acidic pH. OLA@HSA NPs decreased the half-maximal inhibitory concentrations (IC₅₀) of olaparib by 1.6, 1.8-fold in 24 h and 2.2, 2.4 folds in 48 h for human (MDA-MB 231) and mouse (4T1) TNBC cells, respectively, mediated by their enhanced time-dependent cellular uptake than free olaparib. The OLA@HSA-OA NPs induced concentration-dependent phosphatidylserine (apoptotic marker) externalization and arrested the cell population in the G2/M phase in both the tested cell lines at a higher level than free olaparib. The NPs formulation increased DNA fragmentation, mitochondrial membrane depolarization, and ROS generation than the free olaparib. The in vivo study conducted using 4T1-Luc tumor-bearing mice demonstrated strong tumor growth inhibitory potential of OLA@HSA NPs by elevating apoptosis ROS generation and reducing the level of the antiproliferative marker, Ki-67. OLA@HSA NPs reduced the occurrence of lung metastasis (formation of metastasis nodules decreased by ∼10 fold). OLA@HSA NPs could be a promising nanomedicine for the TNBC treatment.

Radioresistance of Non-Small Cell Lung Cancers and Therapeutic Perspectives

Survival in unresectable locally advanced stage non-small cell lung cancer (NSCLC) patients remains poor despite chemoradiotherapy. Recently, adjuvant immunotherapy improved survival for these patients but we are still far from curing most of the patients with only a 57% survival remaining at 3 years. This poor survival is due to the resistance to chemoradiotherapy, local relapses, and distant relapses. Several biological mechanisms have been found to be involved in the chemoradioresistance such as cancer stem cells, cancer mutation status, or the immune system. New drugs to overcome this radioresistance in NSCLCs have been investigated such as radiosensitizer treatments or immunotherapies. Different modalities of radiotherapy have also been investigated to improve efficacity such as dose escalation or proton irradiations. In this review, we focused on biological mechanisms such as the cancer stem cells, the cancer mutations, the antitumor immune response in the first part, then we explored some strategies to overcome this radioresistance in stage III NSCLCs with new drugs or radiotherapy modalities.

Nano-Delivery of a Novel Inhibitor of Polynucleotide Kinase/Phosphatase (PNKP) for Targeted Sensitization of Colorectal Cancer to Radiation-Induced DNA Damage

Inhibition of the DNA repair enzyme polynucleotide kinase/phosphatase (PNKP) increases the sensitivity of cancer cells to DNA damage by ionizing radiation (IR). We have developed a novel inhibitor of PNKP, i.e., A83B4C63, as a potential radio-sensitizer for the treatment of solid tumors. Systemic delivery of A83B4C63, however, may sensitize both cancer and normal cells to DNA damaging therapeutics. Preferential delivery of A83B4C63 to solid tumors by nanoparticles (NP) was proposed to reduce potential side effects of this PNKP inhibitor to normal tissue, particularly when combined with DNA damaging therapies. Here, we investigated the radio-sensitizing activity of A83B4C63 encapsulated in NPs (NP/A83) based on methoxy poly(ethylene oxide)-b-poly(α-benzyl carboxylate-ε-caprolactone) (mPEO-b-PBCL) or solubilized with the aid of Cremophor EL: Ethanol (CE/A83) in human HCT116 colorectal cancer (CRC) models. Levels of γ-H2AX were measured and the biodistribution of CE/A83 and NP/A83 administered intravenously was determined in subcutaneous HCT116 CRC xenografts. The radio-sensitization effect of A83B4C63 was measured following fractionated tumor irradiation using an image-guided Small Animal Radiation Research Platform (SARRP), with 24 h pre-administration of CE/A83 and NP/A83 to Luc⁺/HCT116 bearing mice. Therapeutic effects were analyzed by monitoring tumor growth and functional imaging using Positron Emission Tomography (PET) and [¹⁸F]-fluoro-3’-deoxy-3’-L:-fluorothymidine ([¹⁸F]FLT) as a radiotracer for cell proliferation. The results showed an increased persistence of DNA damage in cells treated with a combination of CE/A83 or NP/A83 and IR compared to those only exposed to IR. Significantly higher tumor growth delay in mice treated with a combination of IR and NP/A83 than those treated with IR plus CE/A83 was observed. [¹⁸F]FLT PET displayed significant functional changes for tumor proliferation for the drug-loaded NP. This observation was attributed to the higher A83B4C63 levels in the tumors for NP/A83-treated mice compared to those treated with CE/A83. Overall, the results demonstrated a potential for A83B4C63-loaded NP as a novel radio-sensitizer for the treatment of CRC.

Active Targeted Nanoparticles for Delivery of Poly(ADP-ribose) Polymerase (PARP) Inhibitors: A Preliminary Review

Nanotechnology has revolutionized novel drug delivery strategies through establishing nanoscale drug carriers, such as niosomes, liposomes, nanomicelles, dendrimers, polymeric micelles, and nanoparticles (NPs). Owing to their desirable cancer-targeting efficacy and controlled release, these nanotherapeutic modalities are broadly used in clinics to improve the efficacy of small-molecule inhibitors. Poly(ADP-ribose) polymerase (PARP) family members engage in various intracellular processes, including DNA repair, gene transcription, signal transduction, cell cycle regulation, cell division, and antioxidant response. PARP inhibitors are synthetic small-molecules that have emerged as one of the most successful innovative strategies for targeted therapy in cancer cells harboring mutations in DNA repair genes. Despite these advances, drug resistance and unwanted side effects are two significant drawbacks to using PARP inhibitors in the clinic. Recently, the development of practical nanotechnology-based drug delivery systems has tremendously improved the efficacy of PARP inhibitors. NPs can specifically accumulate in the leaky vasculature of the tumor and cancer cells and release the chemotherapeutic moiety in the tumor microenvironment. On the contrary, NPs are usually unable to permeate across the body's normal organs and tissues; hence the toxicity is zero to none. NPs can modify the release of encapsulated drugs based on the composition of the coating substance. Delivering PARP inhibitors without modulation often leads to the toxic effect; therefore, a delivery vehicle is essential to encapsulate them. Various nanocarriers have been exploited to deliver PARP inhibitors in different cancers. Through this review, we hope to cast light on the most innovative advances in applying PARP inhibitors for therapeutic purposes.

Silencing UCHL3 enhances radio-sensitivity of non-small cell lung cancer cells by inhibiting DNA repair

UCHL3 belongs to the UCH family and is involved in multiple biological processes. However, the biological functions and underlying mechanisms of action of UCHL3 in radio-sensitivity of non-small cell lung cancer (NSCLC) remain unknown. Here, we reported that the expression of UCHL3 was significantly up-regulated in NSCLC tissues and cell lines, and associated with poor prognosis of NSCLC patients. The expression of UCHL3 of NSCLC cells was increased after exposure to ionizing radiation (IR). Moreover, we found that knockdown of UCHL3 enhanced the radio-sensitivity of NSCLC cells both in vitro and in vivo. Furthermore, γH2AX foci staining and Western blot analysis showed that knockdown of UCHL3 increased IR-induced DNA damage. Knockdown of UCHL3 in NSCLC cells decreased homologous recombination (HR) repair efficiency and RAD51 foci formation. Collectively, our study revealed that knockdown of UCHL3 enhanced the radio-sensitivity of NSCLC cells and increased IR-induced DNA damage via impairing HR repair.

Olaparib increases the therapeutic index of hemithoracic irradiation compared with hemithoracic irradiation alone in a mouse lung cancer model

Background

The radiosensitising effect of the poly(ADP-ribose) polymerase inhibitor olaparib on tumours has been reported. However, its effect on normal tissues in combination with radiation has not been well studied. Herein, we investigated the therapeutic index of olaparib combined with hemithoracic radiation in a urethane-induced mouse lung cancer model.

Methods

To assess tolerability, A/J mice were treated with olaparib plus whole thorax radiation (13 Gy), body weight changes were monitored and normal tissue effects were assessed by histology. In anti-tumour (intervention) studies, A/J mice were injected with urethane to induce lung tumours, and were then treated with olaparib alone, left thorax radiation alone or the combination of olaparib plus left thorax radiation at 8 weeks (early intervention) or 18 weeks (late intervention) after urethane injection. Anti-tumour efficacy and normal tissue effects were assessed by visual inspection, magnetic resonance imaging and histology.

Results

Enhanced body weight loss and oesophageal toxicity were observed when olaparib was combined with whole thorax but not hemithorax radiation. In both the early and late intervention studies, olaparib increased the anti-tumour effects of hemithoracic irradiation without increasing lung toxicity.

Conclusions

The addition of olaparib increased the therapeutic index of hemithoracic radiation in a mouse model of lung cancer.

Perspectives of nano-carrier drug delivery systems to overcome cancer drug resistance in the clinics

Advanced cancer is still considered an incurable disease because of its metastatic spread to distal organs and progressive gain of chemoresistance. Even though considerable treatment progress and more effective therapies have been achieved over the past years, recurrence in the long-term and undesired side effects are still the main drawbacks of current clinical protocols. Moreover, a majority of chemotherapeutic drugs are highly hydrophobic and need to be diluted in organic solvents, which cause high toxicity, in order to reach effective therapeutic dose. These limitations of conventional cancer therapies prompted the use of nanomedicine, the medical application of nanotechnology, to provide more effective and safer cancer treatment. Potential of nanomedicines to overcome resistance, ameliorate solubility, improve pharmacological profile, and reduce adverse effects of chemotherapeutical drugs is thus highly regarded. Their use in the clinical setting has increased over the last decade. Among the various existing nanosystems, nanoparticles have the ability to transform conventional medicine by reducing the adverse effects and providing a controlled release of therapeutic agents. Also, their small size facilitates the intracellular uptake. Here, we provide a closer review of clinical prospects and mechanisms of action of nanomedicines to overcome drug resistance. The significance of specific targeting towards cancer cells is debated as well.

Bacterial Genotoxin-Coated Nanoparticles for Radiotherapy Sensitization in Prostate Cancer

Prostate cancer (PCa) is one of the most commonly diagnosed cancers in men and usually becomes refractory because of recurrence and metastasis. CD44, a transmembrane glycoprotein, serves as a receptor for hyaluronic acid (HA). It has been found to be abundantly expressed in cancer stem cells (CSCs) that often exhibit a radioresistant phenotype. Cytolethal distending toxin (CDT), produced by Campylobacter jejuni, is a tripartite genotoxin composed of CdtA, CdtB, and CdtC subunits. Among the three, CdtB acts as a type I deoxyribonuclease (DNase I), which creates DNA double-strand breaks (DSBs). Nanoparticles loaded with antitumor drugs and specific ligands that recognize cancerous cell receptors are promising methods to overcome the therapeutic challenges. In this study, HA-decorated nanoparticle-encapsulated CdtB (HA-CdtB-NPs) were prepared and their targeted therapeutic activity in radioresistant PCa cells was evaluated. Our results showed that HA-CdtB-NPs sensitized radioresistant PCa cells by enhancing DSB and causing G2/M cell-cycle arrest, without affecting the normal prostate epithelial cells. HA-CdtB-NPs possess maximum target specificity and delivery efficiency of CdtB into the nucleus and enhance the effect of radiation in radioresistant PCa cells. These findings demonstrate that HA-CdtB-NPs exert target specificity accompanied with radiomimetic activity and can be developed as an effective strategy against radioresistant PCa.

Enhanced Anti-Cancer Effect of Folate-Conjugated Olaparib Nanoparticles Combined with Radiotherapy in Cervical Carcinoma

BACKGROUND

Radiotherapy (RT), one of the main treatments for cervical cancer, has tremendous potential for improvement in the efficacy. Poly (ADP-ribose) polymerase (PARP) is a key enzyme in the repair of DNA strand breaks (DSB). Olaparib (Ola) is a PARP inhibitor that is involved in preventing the release of PARP from RT-induced damaged DNA to potentiate the effect of RT. Although the basic mechanism of Ola's radiosensitization is well known, the radiosensitization mechanism of its nanomedicine is still unclear. In addition, the lack of tumor tissue targeting is a major obstacle for the clinical success of Ola.

MATERIALS AND METHODS

In this study, we developed folate-conjugated active targeting olaparib nanoparticles (ATO) and investigated the anti-tumor effect of ATO combined with radiotherapy (RT) in nude mice using cervical cancer xenograft models. We used folate (FA)-conjugated poly (ε-caprolactone)-poly (ethyleneglycol)-poly (e-caprolactone) (PCEC) copolymer to prepare ATO via emulsification/solvent diffusion. Further, we evaluated ATO particle size, potential, encapsulation efficiency, and in vitro release characteristics, and evaluated the shape of ATO via transmission electron microscopy (TEM). We then performed MTT and cell uptake assays to detect cytotoxicity and targeting uptake in vitro. We investigated the anti-tumor properties of ATO in vivo by apoptosis test, 18 F-FDG PET/CT, and immunohistochemical analysis. Finally, the xenografted tumor in nude mice was subjected to RT and/or ATO treatment.

RESULTS

The results confirmed that ATO in combination with RT significantly inhibited tumor growth and prolonged survival time of tumor-bearing mice. This may be related to the inhibition of tumor proliferation and DNA damage repair and induction of cell apoptosis in vivo.

CONCLUSION

The ATO developed in this study may represent a novel formulation for olaparib delivery and have promising potential for treating tumors with an over-expression of folate receptors.

Mechanisms for Tuning Engineered Nanomaterials to Enhance Radiation Therapy of Cancer

Engineered nanomaterials that produce reactive oxygen species on exposure to X- and gamma-rays used in radiation therapy offer promise of novel cancer treatment strategies. Similar to photodynamic therapy but suitable for large and deep tumors, this new approach where nanomaterials acting as sensitizing agents are combined with clinical radiation can be effective at well-tolerated low radiation doses. Suitably engineered nanomaterials can enhance cancer radiotherapy by increasing the tumor selectivity and decreasing side effects. Additionally, the nanomaterial platform offers therapeutically valuable functionalities, including molecular targeting, drug/gene delivery, and adaptive responses to trigger drug release. The potential of such nanomaterials to be combined with radiotherapy is widely recognized. In order for further breakthroughs to be made, and to facilitate clinical translation, the applicable principles and fundamentals should be articulated. This review focuses on mechanisms underpinning rational nanomaterial design to enhance radiation therapy, the understanding of which will enable novel ways to optimize its therapeutic efficacy. A roadmap for designing nanomaterials with optimized anticancer performance is also shown and the potential clinical significance and future translation are discussed.

Self-assembled dihydroartemisinin nanoparticles as a platform for cervical cancer chemotherapy

Dihydroartemisinin (DHA) is a potent anti-cancer drug that has limited clinical applications due to poor water solubility and low bioavailability. We designed a biodegradable poly(ethylene glycol) methyl ether-poly(ε-caprolactone) (MPEG-PCL) micelle carrier for DHA using the self-assembly method. The DHA/MPEG-PCL nanoparticles were spherical with an average particle size of 30.28 ± 0.27 nm, and released the drug in a sustained manner in aqueous solution. The drug-loaded nanoparticles showed dose-dependent toxicity in HeLa cells by inducing cycle arrest and apoptosis. Furthermore, compared to free DHA, the DHA/MPEG-PCL nanoparticles showed higher therapeutic efficacy and lower toxicity in vivo, and significantly inhibited tumor growth and prolonged the survival of tumor-bearing nude mice. In addition, the tumor tissues of the DHA/MPEG-PCL-treated mice showed a marked decline in the in situ expression of proliferation and angiogenesis markers. Taken together, the self-assembled DHA/MPEG-PCL nanoparticles are a highly promising delivery system for targeted cancer treatment.

Etoposide and olaparib polymer-coated nanoparticles within a bioadhesive sprayable hydrogel for post-surgical localised delivery to brain tumours

Glioblastoma is a malignant brain tumour with a median survival of 14.6 months from diagnosis. Despite maximal surgical resection and concurrent chemoradiotherapy, reoccurrence is inevitable. To try combating the disease at a stage of low residual tumour burden immediately post-surgery, we propose a localised drug delivery system comprising of a spray device, bioadhesive hydrogel (pectin) and drug nanocrystals coated with polylactic acid-polyethylene glycol (NCPPs), to be administered directly into brain parenchyma adjacent to the surgical cavity. We have repurposed pectin for use within the brain, showing in vitro and in vivo biocompatibility, bio-adhesion to mammalian brain and gelling at physiological brain calcium concentrations. Etoposide and olaparib NCPPs with high drug loading have shown in vitro stability and drug release over 120 h. Pluronic F127 stabilised NCPPs to ensure successful spraying, as determined by dynamic light scattering and transmission electron microscopy. Successful delivery of Cy5-labelled NCPPs was demonstrated in a large ex vivo mammalian brain, with NCPP present in the tissue surrounding the resection cavity. Our data collectively demonstrates the pre-clinical development of a novel localised delivery device based on a sprayable hydrogel containing therapeutic NCPPs, amenable for translation to intracranial surgical resection models for the treatment of malignant brain tumours.

Co-delivery of paclitaxel and curcumin by biodegradable polymeric nanoparticles for breast cancer chemotherapy

Multi-drug chemotherapy has been one of the most popular strategies for the treatment of malignant tumors, and has achieved desirable therapeutic outcomes. The objective of the present study is to develop biodegradable PCEC nanoparticles (NPs) for the co-delivery of paclitaxel (PTX) and curcumin (CUR), and investigate the antitumor effect of the drug delivery system (DDS: PTX-CUR-NPs) against breast cancer both in vitro and in vivo. The prepared PTX-CUR-NPs had a small size of 27.97 ± 1.87 nm with a low polydispersity index (PDI, 0.197 ± 0.040). The results exhibited slow release of PTX and CUR from the DDS without any burst effect. Further, the PTX-CUR-NPs displayed a dose-dependent cytotoxicity in MCF-7 cells with a higher apoptosis rate (64.29% ± 1.97%) as compared to that of free drugs (PTX + CUR, 34.21% ± 0.81%). The cellular uptake study revealed that the drug loaded PCEC polymeric nanoparticles were more readily uptaken by tumor cells in vitro. To evaluate the in vivo anti-tumor effect, the PTX-CUR-NPs were intravenously administered to BALB/c nude mouse xenografted with MCF-7 cells and the results exhibited significant inhibition of tumor growth with prolonged survival time and reduced side effect when compared with free drugs (PTX + CUR). Moreover, the administration of PTX-CUR-NPs treatment led to lower Ki67 expression (p < 0.05), and enhanced TUNEL positivity (higher apoptosis, p < 0.01) in tumor cells as compared to other treatment groups, suggesting the therapeutic efficacy of the DDS. Altogether, the present study suggests that the DDS PTX-CUR-NPs could be employed for the effective treatment of breast cancers in near future.

Bevacizumab combined with apatinib enhances antitumor and anti-angiogenesis effects in a lung cancer model in vitro and in vivo

Angiogenesis is involved in the proliferation and metastasis of solid tumours; hence, it is an attractive therapeutic target. However, most patients who undergo anti-angiogenic drug treatment do not achieve complete tumour regression, resulting in drug resistance. The objective of this research is to explore the therapeutic effect of combining bevacizumab (Bev), an anti-vascular endothelial growth factor (VEGF)-A antibody, with apatinib (Apa), a VEGR receptor (VEGFR)-2-targeting tyrosine kinase inhibitor, in non-small cell lung cancer (NSCLC). In vitro, we assessed the influence which Bev + Apa treatment exerts upon the proliferation as well as apoptosis of Lewis lung carcinoma (LLC) cells in virtue of the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide as assay as well as Annexin V staining, respectively. For in vivo assessment, we established a tumour-bearing mouse model with LLC cells and investigated the anti-angiogenic and antitumor effects of Bev + Apa by ¹⁸F-FDG PET/CT imaging, immunohistochemistry and TUNEL staining. Bev + Apa treatment significantly inhibited LLC cell growth and proliferation in a larger scale compared to therapy of either of the only agent. Bev + Apa inhibited tumour growth and extended the median survival time of tumour-bearing mice. Mechanistically, Bev + Apa reduced angiogenesis by inhibiting VEGF and VEGFR-2 expression and reducing glucose metabolism in tumour tissues. Thus, Bev and Apa inhibited tumour angiogenesis synergistically, indicating their potential clinical utility for NSCLC treatment.

Combination of Withaferin-A and CAPE Provides Superior Anticancer Potency: Bioinformatics and Experimental Evidence to Their Molecular Targets and Mechanism of Action

We have earlier reported anticancer activity in Withaferin A (Wi-A), a withanolide derived from Ashwagandha (Withania somnifera) and caffeic acid phenethyl ester (CAPE), an active compound from New Zealand honeybee propolis. Whereas Wi-A was cytotoxic to both cancer and normal cells, CAPE has been shown to cause selective death of cancer cells. In the present study, we investigated the efficacy of Wi-A, CAPE, and their combination to ovarian and cervical cancer cells. Both Wi-A and CAPE were seen to activate tumor suppressor protein p53 by downregulation of mortalin and abrogation of its interactions with p53. Downregulation of mortalin translated to compromised mitochondria integrity and function that affected poly ADP-ribose polymerase1 (PARP1); a key regulator of DNA repair and protein-target for Olaparib, drugs clinically used for treatment of breast, ovarian and cervical cancers)-mediated DNA repair yielding growth arrest or apoptosis. Furthermore, we also compared the docking capability of Wi-A and CAPE to PARP1 and found that both of these could bind to the catalytic domain of PARP1, similar to Olaparib. We provide experimental evidences that (i) Wi-A and CAPE cause inactivation of PARP1-mediated DNA repair leading to accumulation of DNA damage and activation of apoptosis signaling by multiple ways, and (ii) a combination of Wi-A and CAPE offers selective toxicity and better potency to cancer cells.

Fluzoparib increases radiation sensitivity of non-small cell lung cancer (NSCLC) cells without BRCA1/2 mutation, a novel PARP1 inhibitor undergoing clinical trials

PROPOSE

Poly (ADP-ribose) polymerase 1 inhibitors were originally investigated as anti-cancer therapeutics with BRCA1/2 genes mutation. Here, we investigate the effectiveness of a novel PARP1 inhibitor fluzoparib, for enhancing the radiation sensitivity of NSCLC cells lacking BRCA1/2 mutation.

METHODS

We used MTS assays, western blotting, colony formation assays, immunofluorescence staining, and flow cytometry to evaluate the radiosensitization of NSCLC cells to fluzoparib and explore the underlying mechanisms in vitro. Through BRCA1 and RAD50 genes knockdown, we established dysfunctional homologous recombination (HR) DNA repair pathway models in NSCLC cells. We next investigated the radiosensitization effect of fluzoparib in vivo using human NSCLC xenograft models in mice. The expression of PARP1 and BRCA1 in human NSCLC tumor samples was measured by immunohistochemistry. Furthermore, we sequenced HR-related gene mutations and analyzed their frequencies in advanced NSCLC.

RESULTS

In vitro experiments in NSCLC cell lines along with in vivo experiments using an NSCLC xenograft mouse model demonstrated the radiosensitization effect of fluzoparib. The underlying mechanisms involved increased apoptosis, cell-cycle arrest, enhanced irradiation-induced DNA damage, and delayed DNA-damage repair. Immunohistochemical staining showed no correlation between the expression of PARP1 and BRCA1. Moreover, our sequencing results revealed high mutation frequencies for the BRCA1/2, CHEK2, ATR, and RAD50 genes.

CONCLUSION

The potential therapeutic value of fluzoparib for increasing the radiation sensitivity of NSCLC is well confirmed. Moreover, our findings of high mutation frequencies among HR genes suggest that PARP1 inhibition may be an effective treatment strategy for advanced non-small cell lung cancer patients.

Poly-ADP-ribose polymerases (PARPs) as a therapeutic target in the treatment of selected cancers

Introduction: The implementation of poly-ADP-ribose polymerase (PARP) inhibitors for therapy has created potential treatments for a wide spectrum of malignancies involving DNA damage repair gene abnormalities. PARPs are a group of enzymes that are responsible for detecting and repairing DNA damage and therefore play a key role in maintaining cell function and integrity. PARP inhibitors are drugs that target DNA repair deficiencies. Inhibiting PARP activity in cancer cells causes cell death. Areas covered: This review summarizes the role of PARP inhibitors in the treatment of cancer. We performed a systematic literature search in February 2019 in the electronic databases PubMed and EMBASE. Our search terms were the following: PARP, PARP inhibitors, PARPi, Poly ADP ribose polymerase, cancer treatment. We discuss PARP inhibitors currently being investigated in cancer clinical trials, their safety profiles, clinical resistance, combined therapeutic approaches and future challenges. Expert Opinion: The future could bring novel PARP inhibitors with greater DNA trapping potential, better safety profiles and improved combined therapies involving hormonal, chemo-, radio- or immunotherapies. Progress may afford wider indications for PARP inhibitors in the treatment of cancer and the utilization for cancer prevention in high-risk mutation carriers. Research efforts should focus on identifying novel drugs that target DNA repair deficiencies.