In vitro hypoxic cytotoxicity and hypoxic radiosensitization. Efficacy of the novel 2-nitroimidazole N,N,N-tris[2-(2-nitro-1H-imidazol-1-yl)ethyl]amine

A Three-In-One Assembled Nanoparticle Containing Peptide-Radio-Sensitizer Conjugate and TLR7/8 Agonist Can Initiate the Cancer-Immunity Cycle to Trigger Antitumor Immune Response

Radiotherapy (RT) has been shown to cause immunogenic cell death (ICD) of cancer cells, which promote the release of tumor-associated antigens, and trigger the cancer-immunity cycle (CIC). However, ICD induced by RT usually does not occur in hypoxic tumor cells due to their resistance to radiation. Moreover, RT also induces programmed death ligand 1 (PD-L1) upregulation on tumor cells, which has an inhibitory effect on T lymphocytes. Therefore, therapy based on CIC must selectively target the restricted steps of antitumor immunity. Herein, the authors design a versatile three-in-one assembling nanoparticle that can simultaneously execute these obstacles. The amphiphilic peptide drug conjugate NIA-D1, containing the hydrophobic radio-sensitizer 2-(2-nitroimidazol-1-yl) acetic acid (NIA), a peptide substrate of matrix metalloproteinase-2, and a hydrophilic PD-L1 antagonist ^D PPA-1, is constructed and co-assembled with hydrophobic Toll-like receptor (TLR) 7/8 agonist R848 to form nanoparticle NIA-D1@R848. The NIA-D1@R848 nanoparticles combined with RT can trigger the apoptosis of tumor cells and initiate the CIC. In the presence of R848, it promotes the maturation of dendritic cells, which together with protein programmed cell death protein 1 (PD-1) and its ligand PD-L1  blockade to relieve T cell suppression, and amplify the antitumor immune cycle. In conclusion, a functionalized three-in-one nanoparticle NIA-D1@R848 is successfully constructed, which can induce strong systemic antitumor immune response.

Raman spectroscopy detects metabolic signatures of radiation response and hypoxic fluctuations in non-small cell lung cancer

BACKGROUND

Radiation therapy is a standard form of treating non-small cell lung cancer, however, local recurrence is a major issue with this type of treatment. A better understanding of the metabolic response to radiation therapy may provide insight into improved approaches for local tumour control. Cyclic hypoxia is a well-established determinant that influences radiation response, though its impact on other metabolic pathways that control radiosensitivity remains unclear.

METHODS

We used an established Raman spectroscopic (RS) technique in combination with immunofluorescence staining to measure radiation-induced metabolic responses in human non-small cell lung cancer (NSCLC) tumour xenografts. Tumours were established in NOD.CB17-Prkdcscid/J mice, and were exposed to radiation doses of 15 Gy or left untreated. Tumours were harvested at 2 h, 1, 3 and 10 days post irradiation.

RESULTS

We report that xenografted NSCLC tumours demonstrate rapid and stable metabolic changes, following exposure to 15 Gy radiation doses, which can be measured by RS and are dictated by the extent of local tissue oxygenation. In particular, fluctuations in tissue glycogen content were observed as early as 2 h and as late as 10 days post irradiation. Metabolically, this signature was correlated to the extent of tumour regression. Immunofluorescence staining for γ-H2AX, pimonidazole and carbonic anhydrase IX (CAIX) correlated with RS-identified metabolic changes in hypoxia and reoxygenation following radiation exposure.

CONCLUSION

Our results indicate that RS can identify sequential changes in hypoxia and tumour reoxygenation in NSCLC, that play crucial roles in radiosensitivity.

Raman spectroscopy identifies radiation response in human non-small cell lung cancer xenografts

External beam radiation therapy is a standard form of treatment for numerous cancers. Despite this, there are no approved methods to account for patient specific radiation sensitivity. In this report, Raman spectroscopy (RS) was used to identify radiation-induced biochemical changes in human non-small cell lung cancer xenografts. Chemometric analysis revealed unique radiation-related Raman signatures that were specific to nucleic acid, lipid, protein and carbohydrate spectral features. Among these changes was a dramatic shift in the accumulation of glycogen spectral bands for doses of 5 or 15 Gy when compared to unirradiated tumours. When spatial mapping was applied in this analysis there was considerable variability as we found substantial intra- and inter-tumour heterogeneity in the distribution of glycogen and other RS spectral features. Collectively, these data provide unique insight into the biochemical response of tumours, irradiated in vivo, and demonstrate the utility of RS for detecting distinct radiobiological responses in human tumour xenografts.

Molecular imaging of hypoxia in non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is the commonest cancer worldwide but survival remains poor with a high risk of relapse, particularly after nonsurgical treatment. Hypoxia is present in a variety of solid tumours, including NSCLC. It is associated with treatment resistance and a poor prognosis, although when recognised may be amenable to different treatment strategies. Thus, noninvasive assessment of intratumoral hypoxia could be used to stratify patients for modification of subsequent treatment to improve tumour control. Molecular imaging approaches targeting hypoxic cells have shown some early success in the clinical setting. This review evaluates the evidence for hypoxia imaging using PET in NSCLC and explores its potential clinical utility.

Association of genetic variants in VEGF-A with clinical recurrence in prostate cancer patients treated with definitive radiotherapy

BACKGROUND AND PURPOSE

Vascular endothelial growth factor-A (VEGF-A), a key regulator of tumor-induced angiogenesis, is critical for tumor growth and metastasization. The goal of the present study was to evaluate the prognostic value of VEGF single nucleotide polymorphisms (SNPs) and haplotypes for clinical recurrence after definitive radiotherapy for prostate cancer.

PATIENTS AND METHODS

The association of seven VEGF-A polymorphisms and their haplotypes with clinical recurrence (defined as the occurrence of local recurrence and/or distant metastases) in 496 prostate cancer patients treated with definitive radiotherapy were investigated. Genotypes were determined by 5'-nuclease (TaqMan) assays; haplotypes were analyzed using the Haploview program.

RESULTS

Within a median follow-up time of 80 months, 44 patients (9 %) developed clinical recurrences. Haplotype analysis showed two separate blocks of high-linkage disequilibrium, formed by five polymorphisms (- 2578C > A, - 2489C > T, - 1498C > T, - 634G > C, - 7C > T) upstream of the coding sequence (CCCCC, ATTGC, CCCGC, ATTGT) and two polymorphisms (936C > T, 1612G > A) downstream of the coding sequence (CA, CG, TG). Carriers of at least 1 copy of the ATTGC haplotype were at higher risk of recurrence (hazard ratio [HR] 3.83; 95 %CI 1.48-9.90, p = 0.006); for carriers of 2 copies, the HR was 4.85 (95 %CI 1.72-13.6; p = 0.003). In multivariate analysis, patients harboring at least one copy of the ATTGC haplotype remained at increased risk of recurrence (HR 3.63, 95 %CI 1.38-9.55, p = 0.009); in patients carrying 2 copies, the HR was 4.72 (95 %CI 1.64-13.6, p = 0.004).

CONCLUSION

Our findings indicate that the VEGF-A ATTGC haplotype may predict clinical recurrence in prostate cancer patients treated with radiotherapy.

Ionizing radiation, ion transports, and radioresistance of cancer cells

The standard treatment of many tumor entities comprises fractionated radiation therapy which applies ionizing radiation to the tumor-bearing target volume. Ionizing radiation causes double-strand breaks in the DNA backbone that result in cell death if the number of DNA double-strand breaks exceeds the DNA repair capacity of the tumor cell. Ionizing radiation reportedly does not only act on the DNA in the nucleus but also on the plasma membrane. In particular, ionizing radiation-induced modifications of ion channels and transporters have been reported. Importantly, these altered transports seem to contribute to the survival of the irradiated tumor cells. The present review article summarizes our current knowledge on the underlying mechanisms and introduces strategies to radiosensitize tumor cells by targeting plasma membrane ion transports.

Radiosensitization by histone deacetylase inhibition in an osteosarcoma mouse model

BACKGROUND

Osteosarcomas (OS) are highly malignant and radioresistant tumors. Histone deacetylase inhibitors (HDACi) constitute a novel class of anticancer agents. We sought to investigate the effect of combined treatment with suberoylanilide hydroxamic acid (SAHA) and radiotherapy in OS in vivo.

METHODS

Clonogenic survival of human OS cell lines as well as tumor growth delay of OS xenografts were tested after treatment with either vehicle, radiotherapy (XRT), SAHA, or XRT and SAHA. Tumor proliferation, necrosis, microvascular density, apoptosis, and p53/p21 were monitored by immunohistochemistry. The CD95 pathway was performed by flow cytometry, caspase (3/7/8) activity measurements, and functional inhibition of CD95 death signaling.

RESULTS

Combined treatment with SAHA and XRT markedly reduced the surviving fraction of OS cells as compared to XRT alone. Likewise, dual therapy significantly inhibited OS tumor growth in vivo as compared to XRT alone, reflected by reduced tumor proliferation, impaired angiogenesis, and increased apoptosis. Addition of HDACi to XRT led to elevated p53, p21, CD95, and CD95L expression. Inhibition of CD95 signaling reduced HDACi- and XRT-induced apoptosis.

CONCLUSION

Our data show that HDACi increases the radiosensitivity of osteosarcoma cells at least in part via ligand-induced apoptosis. HDACi thus emerge as potentially useful treatment components of OS.