Correction: DCE-MRI-Derived Parameters in Evaluating Abraxane-Induced Early Vascular Response and the Effectiveness of Its Synergistic Interaction with Cisplatin.

[This corrects the article DOI: 10.1371/journal.pone.0162601.].

Regulating autophagy facilitated therapeutic efficacy of the sonic Hedgehog pathway inhibition on lung adenocarcinoma through GLI2 suppression and ROS production.

Lung adenocarcinoma (LUAD), which comprises over 50% of all cases of non-small-cell lung cancer, has a poor prognosis and requires novel therapeutic approaches. The sonic Hedgehog (Shh) pathway, which plays a crucial role in differentiation, proliferation, and survival of cancer cells, is likely to be activated in LUADs, suggesting the Shh pathway as a potential therapeutic target for LUAD treatment. In this study, we reported that vismodegib, an inhibitor of the Shh pathway, only elicited minor antitumor efficacy in A549 and NCI-H1975 LUAD cells as well as in the xenograft tumors, with overexpressed GLI2 and increased autophagic activity. The aberrant autophagy in LUAD cells was further confirmed by the three main stages of autophagic flux, including the formation of autophagosomes, the fusion of autophagosomes with lysosomes, and degradation of autophagosomes in lysosomes. Furthermore, inhibition of autophagy by siRNA against ATG5 or ATG7 rescued the sensitivity of A549 and NCI-H1975 LUAD cells to vismodegib in vitro. Meanwhile, administration of the pharmaceutical inhibitor of autophagy, chloroquine, contributed to the enhanced anti-LUAD efficacy of vismodegib in vivo, probably through overproduction of ROS, acceleration of apoptosis, and suppression of GLI2 in LUAD tissues. In summary, our research revealed that downregulating autophagy facilitated the anti-LUAD efficacy of the Shh pathway suppression, thus highlighting a potential approach for LUAD therapy via simultaneously targeting the Shh signaling and autophagy pathway.

Analysis of Progress and Challenges of EGFR-Targeted Molecular Imaging in Cancer With a Focus on Affibody Molecules.

Epidermal growth factor receptor (EGFR)-targeted cancer therapy requires an accurate estimation of EGFR expression in tumors to identify responsive patients, monitor therapeutic effect, and estimate prognosis. The EGFR molecular imaging is an optimal method for evaluating EGFR expression in vivo accurately and noninvasively. In this review, we discuss the recent advances in EGFR-targeted molecular imaging in cancer, with a special focus on the development of imaging agents, including epidermal growth factor (EGF) ligand, monoclonal antibodies, antibody fragments, Affibody, and small molecules. Each substrate or probe, whether it is an endogenous ligand, antibody, peptide, or small molecule labeled with fluorochrome or radionuclide, has unique advantages and limitations. Antibody-based probes have high affinity but a long metabolic cycle and therefore offer poor imaging quality. Affibody molecules promise to surpass antibody-based probes due to their small size, stable chemical properties, and high affinity to the target. Small-molecule probes are safe, have favorable pharmacokinetics, and show high affinity and specificity, in addition to having an ideal size, but are inadequate for delayed imaging after injection due to their fast clearance.

Irreversible electroporation reverses resistance to immune checkpoint blockade in pancreatic cancer.

Immunotherapy has only limited efficacy against pancreatic ductal adenocarcinoma (PDAC) due to the presence of an immunosuppressive tumor-associated stroma. Here, we demonstrate an effective modulation of that stroma by irreversible electroporation (IRE), a local ablation technique that has received regulatory approval in the United States. IRE induces immunogenic cell death, activates dendritic cells, and alleviates stroma-induced immunosuppression without depleting tumor-restraining collagen. The combination of IRE and anti-programmed cell death protein 1 (anti-PD1) immune checkpoint blockade promotes selective tumor infiltration by CD8+ T cells and significantly prolongs survival in a murine orthotopic PDAC model with a long-term memory immune response. Our results suggest that IRE is a promising approach to potentiate the efficacy of immune checkpoint blockade in PDAC.

19F MRI in orthotopic cancer model via intratracheal administration of ανß3-targeted perfluorocarbon nanoparticles.

AIM: To demonstrate the feasibility of intratracheal administration in orthotopic lung cancer model with 19F MRI. MATERIALS & METHODS: αvß3-integrin targeting ability of the perfluorocarbon (PFC) nanoparticles was tested. Orthotopic lung cancer model was established in rabbits under computed tomography guidance. αvß3-targeted PFC nanoparticles were administrated intratracheally or intravenously, and 19F MRI was performed before and up to 24 h after administration. RESULTS: The targeted PFC nanoparticles could bind with αvß3-integrin. PFC concentrations in the tumors of intratracheal group after administration were significantly higher than intravenous group. CONCLUSION: Intratracheal administration of PFC nanoparticles was shown to be feasible and efficacious. 19F MRI with αvß3-targeted PFC nanoparticles provided quantitative assessment of nanoparticles distribution and tumor angiogenesis.

Current Concepts and Perspectives on Connexin43: A Mini Review.

Connexins are a family of gap junction proteins widely distributed in human organs and tissues. Gap junctions are organized systems of intercellular protein channels that allow the exchange of ions, chemical signals, and energy substrates between two adjacent cells. Connexin43 (Cx43) is the most abundant isoform of connexins in the heart which play an important role in myocardium disease. Numerous studies have shown that Cx43 was involved in tumor migration and invasion by mediating gap junctions between tumor cells and normal cells. Changes in the expression and distribution of Cx43 contribute to heart disease and cancer. This review discusses current knowledge on the functional and structural abnormalities in Cx43 associated with heart disease and cancer, aiming to highlight the importance of this connexin as an emerging therapeutic target. Here, the current knowledge on the pharmacology of Gap Junction Channels and Hemichannels were also summarized. Finally, we propose that these knowledges can be exploited to identify new diagnostic and effective therapeutic approaches for ischemic heart disease and cancer.

Folate receptor-targeted 19 F MR molecular imaging and proliferation evaluation of lung cancer.

BACKGROUND: Folate receptors (FRs) hold great potential as important diagnostic and prognostic biological marker for cancer. PURPOSE: To assess the targeted capability of the FR-targeted perfluorocarbon (PFC) nanoparticles and to assess in vivo the relationship between FR expression and tumor proliferation with fluorine-19 (19 F) MR molecular imaging. STUDY TYPE: Prospective animal cancer model. ANIMAL MODEL: H460 (n = 14) and A549 (n = 14) nude mice subcutaneous tumor models. FIELD STRENGTH: 9.4T, 1 H and 19 F RARE sequences. ASSESSMENT: Intracellular uptake of the PFC nanoparticles was tested in H460 and A549 cell lines. 19 F MRI of H460 and A549 subcutaneous tumors was performed following intravenous injection of PFC nanoparticles. The concentration of PFC in tumors were compared. 3'-Deoxy-3'-18 F-fluorothymidine (18 F-FLT) positron emission tomography / computed tomography (PET/CT) imaging, Ki-67, and proliferating cell nuclear antigen (PCNA) staining were performed to confirm tumor proliferation. STATISTICAL TESTS: One-way or two-way analysis of variance. P < 0.05 was considered a significant difference. RESULTS: The diameter of the FR-targeted nanoparticles was 108.8 ± 0.56 nm, and the zeta potential was -58.4 ± 10.8 mV. H460 cells incubated with FR-targeted nanoparticles showed ∼59.87 ± 3.91% nanoparticles-labeled, which is significantly higher than the other groups (P < 0.001). The PFC concentration in H460 tumors after injection with FR-targeted nanoparticles was 4.64 ± 1.21, 8.04 ± 1.38, and 9.16 ± 2.56 mmol/L at 8 hours, 24 hours, and 48 hours, respectively (P < 0.05 compared to others). The ratio of 18 F-FLT uptake for H460 and A549 tumors was 3.32 ± 0.17 and 1.48 ± 0.09 (P < 0.05), and there was more Ki-67 and PCNA in H460 tumor than A549. DATA CONCLUSION: 19 F MRI with FR-targeted PFC nanoparticles can be used in differentiating of FR-positive and FR-negative tumors, and further, in evaluation of the two cancer models proliferation. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1617-1625.

Development of a SPECT Tracer to Image c-Met Expression in a Xenograft Model of Non-Small Cell Lung Cancer.

Elevated expression of the c-Met receptor plays a crucial role in cancers. In non-small cell lung cancer (NSCLC), aberrant activation of the c-Met signaling pathway contributes to tumorigenesis and cancer progression and may mediate acquired resistance to epidermal growth factor receptor-targeted therapy. c-Met is therefore emerging as a promising therapeutic target for NSCLC, and methods for noninvasive in vivo assessment of c-Met expression would improve NSCLC treatment and diagnosis. Methods: We developed a new c-Met-binding peptide (cMBP) radiotracer, 99mTc-hydrazine nicotinamide (HYNIC)-cMBP, for SPECT imaging. Cell uptake assays were performed on 2 NSCLC cell lines with different c-Met expressions: H1993 (high expression) and H1299 (no expression). In vivo tumor specificity was assessed by SPECT imaging in tumor-bearing mice at 0.5, 1, 2, and 4 h after injection of the probe. Blocking assays, biodistribution, and autoradiography were also conducted to determine probe specificity. Results:99mTc-HYNIC-cMBP was prepared with high efficiency and showed higher uptake in H1993 cells than in H1299 cells. Biodistribution and autoradiography also showed significantly higher percentages of the injected dose for 99mTc-HYNIC-cMBP in H1993 tumors than in H1299 tumors at 0.5 h (4.74 ± 1.43%/g and 1.00 ± 0.37%/g, respectively; P < 0.05). H1993 tumors were clearly visualized at 0.5 h in SPECT images, whereas H1299 tumors were not observed at any time. The specificity of 99mTc-HYNIC-cMBP for c-Met was demonstrated by a competitive block with an excess of nonradiolabeled peptide. Conclusion: For c-Met-targeted SPECT imaging of NSCLC, we developed 99mTc-HYNIC-cMBP, a tracer that specifically binds to c-Met with favorable pharmacokinetics in vitro and in vivo.

A PET imaging approach for determining EGFR mutation status for improved lung cancer patient management.

Tumor heterogeneity and changes in epidermal growth factor receptor (EGFR) mutation status over time challenge the design of effective EGFR tyrosine kinase inhibitor (TKI) treatment strategies for non-small cell lung cancer (NSCLC). Therefore, there is an urgent need to develop techniques for comprehensive tumor EGFR profiling in real time, particularly in lung cancer precision medicine trials. We report a positron emission tomography (PET) tracer, N-(3-chloro-4-fluorophenyl)-7-(2-(2-(2-(2-18F-fluoroethoxy) ethoxy) ethoxy) ethoxy)-6-methoxyquinazolin-4-amine (18F-MPG), with high specificity to activating EGFR mutant kinase. We evaluate the feasibility of using 18F-MPG PET for noninvasive imaging and quantification of EGFR-activating mutation status in preclinical models of NSCLC and in patients with primary and metastatic NSCLC tumors. 18F-MPG PET in NSCLC animal models showed a significant correlation (R2 = 0.9050) between 18F-MPG uptake and activating EGFR mutation status. In clinical studies with NSCLC patients (n = 75), the concordance between the detection of EGFR activation by 18F-MPG PET/computed tomography (CT) and tissue biopsy reached 84.29%. There was a greater response to EGFR-TKIs (81.58% versus 6.06%) and longer median progression-free survival (348 days versus 183 days) in NSCLC patients when 18F-MPG PET/CT SUVmax (maximum standard uptake value) was ≥2.23 versus <2.23. Our study demonstrates that 18F-MPG PET/CT is a powerful method for precise quantification of EGFR-activating mutation status in NSCLC patients, and it is a promising strategy for noninvasively identifying patients sensitive to EGFR-TKIs and for monitoring the efficacy of EGFR-TKI therapy.

Role of piwi-interacting RNA-651 in the carcinogenesis of non-small cell lung cancer.

Piwi-interacting RNAs (piRNAs/piRs) are small non-coding RNAs that can serve important roles in genome stability by silencing transposable genetic elements. piR651, one of these novel piRNAs, regulates a number of biological functions, as well as carcinogenesis. Previous studies have reported that piR651 is overexpressed in human gastric cancer tissues and in several cancer cell lines, including non-small cell lung cancer (NSCLC) cell lines. However, the role of piRNAs in carcinogenesis has not been clearly defined. In the present study, a small interfering RNA inhibitor of piR651 was transfected into the NSCLC A549 and HCC827 cell lines to evaluate the effect of piR651 on cell growth. The association between piR651 expression and apoptosis was evaluated by flow cytometry and western blot analysis. Wound-healing and Transwell migration and invasion assays were used to determine the effect of piR651 on the migration and invasion of NSCLC cell lines. The results revealed that inhibition of piR651 inhibited cell proliferation and significantly increased the apoptotic rate compared with the negative control (NC), as well as altering the expression of apoptosis-associated proteins. There were fewer migrating and invading cells in the piR651-inhibited group than in the NC group in the Transwell assays. Furthermore, in the wound-healing assay, the wound remained wider in the piR651 inhibitor group, suggesting decreased cell migration compared with that in the NC group. The results of the present study demonstrate that piR651 potentially regulates NSCLC tumorigenic behavior by inhibiting cell proliferation, migration and invasion and by inducing apoptosis. Therefore, piR651 is a potential cancer diagnosis marker.

Local Intratracheal Delivery of Perfluorocarbon Nanoparticles to Lung Cancer Demonstrated with Magnetic Resonance Multimodal Imaging.

Eighty percent of lung cancers originate as subtle premalignant changes in the airway mucosal epithelial layer of bronchi and alveoli, which evolve and penetrate deeper into the parenchyma. Liquid-ventilation, with perfluorocarbons (PFC) was first demonstrated in rodents in 1966 then subsequently applied as lipid-encapsulated PFC emulsions to improve pulmonary function in neonatal infants suffering with respiratory distress syndrome in 1996. Subsequently, PFC nanoparticles (NP) were extensively studied as intravenous (IV) vascular-constrained nanotechnologies for diagnostic imaging and targeted drug delivery applications. Methods: This proof-of-concept study compared intratumoral localization of fluorescent paramagnetic (M) PFC NP in the Vx2 rabbit model using proton (1H) and fluorine (19F) magnetic resonance (MR) imaging (3T) following intratracheal (IT) or IV administration. MRI results were corroborated by fluorescence microscopy. Results: Dynamic 1H-MR and 19F-MR images (3T) obtained over 72 h demonstrated marked and progressive accumulation of M-PFC NP within primary lung Vx2 tumors during the first 12 h post IT administration. Marked 1H and 19F MR signal persisted for over 72 h. In contradistinction, IV M-PFC NP produced a modest transient signal during the initial 2 h post-injection that was consistent circumferential blood pool tumor enhancement. Fluorescence microscopy of excised tumors corroborated the MR results and revealed enormous intratumor NP deposition on day 3 after IT but not IV treatment. Rhodamine-phospholipid incorporated into the PFC nanoparticle surfactant was distributed widely within the tumor on day 3, which is consistent with a hemifusion-based contact drug delivery mechanism previously reported. Fluorescence microscopy also revealed similar high concentrations of M-PFC NP given IT for metastatic Vx2 lung tumors. Biodistribution studies in mice revealed that M-PFC NP given IV distributed into the reticuloendothelial organs, whereas, the same dosage given IT was basically not detected beyond the lung itself. PFC NP given IT did not impact rabbit behavior or impair respiratory function. PFC NP effects on cells in culture were negligible and when given IV or IT no changes in rabbit hematology nor serum clinical chemistry parameters were measured. Conclusion: IT delivery of PFC NP offered unique opportunity to locally deliver PFC NP in high concentrations into lung cancers with minimal extratumor systemic exposure.

18F-Fluoromisonidazole in tumor hypoxia imaging.

Hypoxia is a common feature of solid tumors that is closely associated with radiotherapy and chemotherapy resistance, metastasis and tumors prognosis. Thus, it is important to assess hypoxia in tumors for estimating prognosis and selecting appropriate treatment procedures. 18F-Fluoromisonidazole positron emission tomography (18F-FMISO PET) has been widely used to visualize tumor hypoxia in a comprehensive and noninvasive way, both in the clinical and preclinical settings. Here we review the concept, mechanisms and detection methods of tumor hypoxia. Furthermore, we discuss the correlation between 18F-FMISO PET and other detection methods, current applications of 18F-FMISO PET and the development prospects of this imaging technology.

Molecular Imaging of IGF-1R in Cancer.

The important role of insulin-like growth factor 1 receptor (IGF-1R) in malignant tumors has been well established. Increased IGF-1R activity promotes cancer cell proliferation, migration, and invasion and is associated with tumor metastasis, treatment resistance, poor prognosis, and shortened survival in patients with cancer. However, while IGF-1R has become a promising target for cancer therapy, IGF-1R-targeted therapy is ineffective in unselected patients. It is therefore essential to evaluate IGF-1R expression before treatment in order to identify responsive patients, monitor therapy efficacy, and estimate prognosis. Insulin-like growth factor 1 receptor molecular imaging is an optimal method for assessing the expression of IGF-1R in vivo accurately and noninvasively. In this review, we will summarize the current status of IGF-1R molecular imaging in cancer, in which 5 major classes of ligands that have been developed for noninvasive IGF-1R molecular imaging will be discussed: natural ligands, monoclonal antibodies, antibody fragments, affibodies, and small molecules. For decades, IGF-1R molecular imaging is studied in full swing and more effort is needed in the future.

Development and Evaluation of 18F-IRS for Molecular Imaging Mutant EGF Receptors in NSCLC.

To prepare and evaluate a new radiotracer 18F-IRS for molecular imaging mutant EGF Receptors in vitro and vivo. Uptake and efflux of 18F-IRS were performed with four NSCLC cell lines including HCC827, H1975, H358 and H520. In vivo tumor targeting and pharmacokinetics of the radiotracers were also evaluated in HCC827, H1975, H358 and H520 tumor-bearing nude mice by PET/CT imaging. Ex vivo biodistribution assays were performed to quantify the accumulation of 18F-IRS in vivo. We also performed 18F-IRS PET/CT imaging of three patients with NSCLC. We labeled this small molecule with QD620 for flow cytometry and confocal imaging analyses. The uptakes of 18F-IRS by HCC827 and HCC827 tumors were significantly higher than those of H358, H1975 and H520, and they were reduced by the addition of 100 µM of gefitinib. Biodistribution experiments showed an accumulation of 18F-IRS in tumors of HCC827 xenografts. Flow cytometry and confocal imaging with QD620-IRS further demonstrated that binding specifically to HCC827 cells. 18F-IRS accumulation was preferential in the tumor, which was NSCLC with responsive EGFR exon 19 deleted. 18F-IRS showed high binding stability and specificity to 19 exon deleted EGFR mutation in vitro and vivo.

Evaluation of 99mTc-HYNIC-MPG as a novel SPECT radiotracer to detect EGFR-activating mutations in NSCLC.

Tyrosine kinase inhibitors (EGFR-TKIs) targeting the epidermal growth factor receptor (EGFR) have been used in non-small cell lung carcinoma (NSCLC) for years with promising results, in particular in patients with activating mutations in the EGFR kinase domain (exon 19 E746-A750 deletion or exon 21 L858R point mutation). However, despite their great success in the clinic, a significant number of patients do not respond to EGFR-TKIs, such as those carrying the L858R/T790M mutation or EGFR wild type. Thus, detecting the EGFR mutation status before EGFR-TKIs therapy is essential to ensure its efficacy. In this study, we report a novel SPECT tracer 99mTc-HYNIC-MPG that binds specifically to activating mutant EGFR and which could therefore be used to noninvasively select patients sensitive to EGFR-TKIs. We evaluated the capacity of 99mTc-HYNIC-MPG in detecting EGFR-activating mutations both in vitro and in vivo using four human NSCLC cell lines (PC9, H1975, H358 and H520). 99mTc-HYNIC-MPG had significantly higher accumulation in PC9 tumor cells when compared to H1975, H358 and H520 tumors cells, which may be due to the activating mutations (exon 19 deletion) in EGFR tyrosine kinase domain in PC9 cells. Thus, 99mTc-HYNIC-MPG SPECT imaging may be used to identify NSCLC tumors with a potential high response rate to EGFR-TKIs.

Analysis of progress and challenges for various patterns of c-MET-targeted molecular imaging: a systematic review.

BACKGROUND: Mesenchymal-epithelial transition factor also named c-MET is a receptor tyrosine kinase for the hepatocyte growth factor that plays a pivotal role in tumorigenesis. c-MET-targeted therapies have been tested in preclinical models and patients, with significant benefits for cancer treatment. In recent years, many studies have shown that the expression level and activation status of c-MET are closely correlated to c-MET-targeted therapy response and clinical prognosis, thus highlighting the importance of evaluating the c-MET status during and prior to targeted therapy. Molecular imaging allows the monitoring of abnormal alterations of c-MET in real time and in vivo. RESULTS: In this review, we initially summarize the recent advances in c-MET-targeted molecular imaging, with a special focus on the development of imaging agents ranging in size from monoclonal antibody to small molecule. The aim of this review is to report the preclinical results and clinical application of all molecular imaging studies completed until now for in vivo detection of c-MET in cancer, in order to be beneficial to development of molecular probe and the combination of molecular imaging technologies for in vivo evaluation of c-MET. Various molecular probe targeted to c-MET possesses distinctive advantages and disadvantages. For example, antibody-based probes have high binding affinity but with long metabolic cycle as well as remarkable immunogenicity. CONCLUSIONS: Although studies for c-MET-targeted molecular imaging have made many important advances, most of imaging agents specifically target to extracellular area of c-MET receptor; however, it is difficult to reflect entirely activation of c-MET. Therefore, small molecule probes based on tyrosine kinase inhibitors, which could target to intracellular area of c-MET without any immunogenicity, should be paid more attention.

NDV-D90 suppresses growth of gastric cancer and cancer-related vascularization.

Recent reports suggest promises on using oncolytic Newcastle disease viruses (NDV) to treat different cancers, while the effects of a NDV-D90 strain on gastric cancer remain unknown. Here we showed that NDV-D90 induced gastric cancer cell apoptosis in a dose-dependent manner in 3 gastric cancer cell lines BGC-823, SGC-7901 and MKN-28. Pronounced reduction in cell invasion was detected in NDV-D90-treated BGC-823 and SGC-7901 cells, but not in MKN-28 cells. The increases in cell apoptosis and reduction in cell growth in NDV-D90-treated gastric cancer cells seemingly resulted from augmentation of p38 signaling and suppression of ERK1/2 and Akt signaling. In vivo, orthotopic injection of NDV-D90 impaired tumor growth and induced intratumoral necrosis. Tumor cells that had been pre-treated with NDV-D90 showed defect in development of implanted tumor. Moreover, NDV-D90 appeared to reduce gastric tumor vascularization, possibly through suppression of vascular endothelial growth factor A and Matrix Metallopeptidase 2. Together, our data suggest that NDV-D90 may have potential anti-cancer effects on gastric cancer.

Revisit 18F-fluorodeoxyglucose oncology positron emission tomography: "systems molecular imaging" of glucose metabolism.

18F-fluorodeoxyglucose (18F-FDG) positron emission tomography has become an important tool for detection, staging and management of many types of cancer. Oncology application of 18F-FDG bases on the knowledge that increase in glucose demand and utilization is a fundamental features of cancer. Pasteur effect, Warburg effect and reverse Warburg effect have been used to explain glucose metabolism in cancer. 18F-FDG accumulation in cancer is reportedly microenvironment-dependent, 18F-FDG avidly accumulates in poorly proliferating and hypoxic cancer cells, but low in well perfused (and proliferating) cancer cells. Cancer is a heterogeneous and complex "organ" containing multiple components, therefore, cancer needs to be investigated from systems biology point of view, we proposed the concept of "systems molecular imaging" for much better understanding systems biology of cancer.This article revisits 18F-FDG uptake mechanisms, its oncology applications and the role of 18F-FDG PET for "systems molecular imaging".

Contrast agents in dynamic contrast-enhanced magnetic resonance imaging.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive method to assess angiogenesis, which is widely used in clinical applications including diagnosis, monitoring therapy response and prognosis estimation in cancer patients. Contrast agents play a crucial role in DCE-MRI and should be carefully selected in order to improve accuracy in DCE-MRI examination. Over the past decades, there was much progress in the development of optimal contrast agents in DCE-MRI. In this review, we describe the recent research advances in this field and discuss properties of contrast agents, as well as their advantages and disadvantages. Finally, we discuss the research perspectives for improving this promising imaging method.