Infrared microspectroscopy to elucidate the underlying biomolecular mechanisms of FLASH radiotherapy

BACKGROUND

FLASH-radiotherapy (FLASH-RT) is an emerging modality that uses ultra-high dose rates of radiation to enable curative doses to the tumor while preserving normal tissue. The biological studies showed the potential of FLASH-RT to revolutionize radiotherapy cancer treatments. However, the complex biological basis of FLASH-RT is not fully known yet.

AIM

Within this context, our aim is to get deeper insights into the biomolecular mechanisms underlying FLASH-RT through Fourier Transform Infrared Microspectroscopy (FTIRM).

METHODS

C57Bl/6J female mice were whole brain irradiated at 10 Gy with the eRT6-Oriatron system. 10 Gy FLASH-RT was delivered in 1 pulse of 1.8μs and conventional irradiations at 0.1 Gy/s. Brains were sampled and prepared for analysis 24 h post-RT. FTIRM was performed at the MIRAS beamline of ALBA Synchrotron. Infrared raster scanning maps of the whole mice brain sections were collected for each sample condition. Hyperspectral imaging and Principal Component Analysis (PCA) were performed in several regions of the brain.

RESULTS

PCA results evidenced a clear separation between conventional and FLASH irradiations in the 1800-950 cm-1 region, with a significant overlap between FLASH and Control groups. An analysis of the loading plots revealed that most of the variance accounting for the separation between groups was associated to modifications in the protein backbone (Amide I). This protein degradation and/or conformational rearrangement was concomitant with nucleic acid fragmentation/condensation. Cluster separation between FLASH and conventional groups was also present in the 3000-2800 cm-1 region, being correlated with changes in the methylene and methyl group concentrations and in the lipid chain length. Specific vibrational features were detected as a function of the brain region.

CONCLUSION

This work provided new insights into the biomolecular effects involved in FLASH-RT through FTIRM. Our results showed that beyond nucleic acid investigations, one should take into account other dose-rate responsive molecules such as proteins, as they might be key to understand FLASH effect.

Biochemical and biophysical interaction of rare earth elements with biomacromolecules: A comprehensive review

The growing utilization of rare earth elements (REEs) in industrial and technological applications has captured global interest, leading to the development of high-performance technologies in medical diagnosis, agriculture, and other electronic industries. This accelerated utilization has also raised human exposure levels, resulting in both favourable and unfavourable impacts. However, the effects of REEs are dependent on their concentration and molecular species. Therefore, scientific interest has increased in investigating the molecular interactions of REEs with biomolecules. In this current review, particular attention was paid to the molecular mechanism of interactions of Lanthanum (La), Cerium (Ce), and Gadolinium (Gd) with biomolecules, and the biological consequences were broadly interpreted. The review involved gathering and evaluating a vast scientific collection which primarily focused on the impact associated with REEs, ranging from earlier reports to recent discoveries, including studies in human and animal models. Thus, understanding the molecular interactions of each element with biomolecules will be highly beneficial in elucidating the consequences of REEs accumulation in the living organisms.

Investigating the biochemical response of proton minibeam radiation therapy by means of synchrotron-based infrared microspectroscopy

The biology underlying proton minibeam radiation therapy (pMBRT) is not fully understood. Here we aim to elucidate the biological effects of pMBRT using Fourier Transform Infrared Microspectroscopy (FTIRM). In vitro (CTX-TNA2 astrocytes and F98 glioma rat cell lines) and in vivo (healthy and F98-bearing Fischer rats) irradiations were conducted, with conventional proton radiotherapy and pMBRT. FTIRM measurements were performed at ALBA Synchrotron, and multivariate data analysis methods were employed to assess spectral differences between irradiation configurations and doses. For astrocytes, the spectral regions related to proteins and nucleic acids were highly affected by conventional irradiations and the high-dose regions of pMBRT, suggesting important modifications on these biomolecules. For glioma, pMBRT had a great effect on the nucleic acids and carbohydrates. In animals, conventional radiotherapy had a remarkable impact on the proteins and nucleic acids of healthy rats; analysis of tumour regions in glioma-bearing rats suggested major nucleic acid modifications due to pMBRT.

Synchrotron Infrared Microspectroscopy for Stem Cell Research

Stem cells have shown great potential functions for tissue regeneration and repair because of their unlimited self-renewal and differentiation. Stem cells reside in their niches, making them a hotspot for the development and diagnosis of diseases. Complex interactions between niches and stem cells create the balance between differentiation, self-renewal, maturation, and proliferation. However, the multi-facet applications of stem cells have been challenged since the complicated responses of stem cells to biological processes were explored along with the limitations of current systems or methods. Emerging evidence highlights that synchrotron infrared microspectroscopy, known as synchrotron radiation-based Fourier transform infrared microspectroscopy, has been investigated as a potentially attractive technology with its non-invasive and non-biological probes in stem cell research. With their unique vibration bands, the quantitative mapping of the content and distribution of biomolecules can be detected and characterized in cells or tissues. In this review, we focus on the potential applications of synchrotron infrared microspectroscopy for investigating the differentiation and fate determination of stem cells.

Live-Cell Synchrotron-Based FTIR Evaluation of Metabolic Compounds in Brain Glioblastoma Cell Lines after Riluzole Treatment

Glioblastoma multiforme (GBM) is the most aggressive brain tumor, characterized by short median survival and an almost 100% tumor-related mortality. The standard of care treatment for newly diagnosed GBM includes surgical resection followed by concomitant radiochemotherapy. The prevention of disease progression fails due to the poor therapeutic effect caused by the great molecular heterogeneity of this tumor. Previously, we exploited synchrotron radiation-based soft X-ray tomography and hard X-ray fluorescence for elemental microimaging of the shock-frozen GBM cells. The present study focuses instead on the biochemical profiling of live GBM cells and provides new insight into tumor heterogenicity. We studied bio-macromolecular changes by exploring the live-cell synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy in a set of three GBM cell lines, including the patient-derived glioblastoma cell line, before and after riluzole treatment, a medicament with potential anticancer properties. SR-FTIR microspectroscopy shows that GBM live cells of different origins recruit different organic compounds. The riluzole treatment of all GBM cell lines mainly affected carbohydrate metabolism and the DNA structure. Lipid structures and protein secondary conformation are affected as well by the riluzole treatment: cellular proteins assumed cross β-sheet conformation while parallel β-sheet conformation was less represented for all GBM cells. Moreover, we hope that a new live-cell approach for GBM simultaneous treatment and examination can be devised to target cancer cells more specifically, i.e., future therapies can develop more specific treatments according to the specific bio-macromolecular signature of each tumor type.

Synchrotron-Based Fourier-Transform Infrared Micro-Spectroscopy (SR-FTIRM) Fingerprint of the Small Anionic Molecule Cobaltabis(dicarbollide) Uptake in Glioma Stem Cells

The anionic cobaltabis (dicarbollide) [3,3'-Co(1,2-C2B9H11)2]-, [o-COSAN]-, is the most studied icosahedral metallacarborane. The sodium salts of [o-COSAN]- could be an ideal candidate for the anti-cancer treatment Boron Neutron Capture Therapy (BNCT) as it possesses the ability to readily cross biological membranes thereby producing cell cycle arrest in cancer cells. BNCT is a cancer therapy based on the potential of 10B atoms to produce α particles that cross tissues in which the 10B is accumulated without damaging the surrounding healthy tissues, after being irradiated with low energy thermal neutrons. Since Na[o-COSAN] displays a strong and characteristic ν(B-H) frequency in the infrared range 2.600-2.500 cm-1, we studied the uptake of Na[o-COSAN] followed by its interaction with biomolecules and its cellular biodistribution in two different glioma initiating cells (GICs), mesenchymal and proneural respectively, by using Synchrotron Radiation-Fourier Transform Infrared (FTIR) micro-spectroscopy (SR-FTIRM) facilities at the MIRAS Beamline of ALBA synchrotron light source. The spectroscopic data analysis from the bands in the regions of DNA, proteins, and lipids permitted to suggest that after its cellular uptake, Na[o-COSAN] strongly interacts with DNA strings, modifies proteins secondary structure and also leads to lipid saturation. The mapping suggests the nuclear localization of [o-COSAN]-, which according to reported Monte Carlo simulations may result in a more efficient cell-killing effect compared to that in a uniform distribution within the entire cell. In conclusion, we show pieces of evidence that at low doses, [o-COSAN]- translocates GIC cells' membranes and it alters the physiology of the cells, suggesting that Na[o-COSAN] is a promising agent to BNCT for glioblastoma cells.

Study of the intracellular nanoparticle-based radiosensitization mechanisms in F98 glioma cells treated with charged particle therapy through synchrotron-based infrared microspectroscopy

The use of nanoparticles (NP) as dose enhancers in radiotherapy (RT) is a growing research field. Recently, the use of NP has been extended to charged particle therapy in order to improve the performance in radioresistant tumors. However, the biological mechanisms underlying the synergistic effects involved in NP-RT approaches are not clearly understood. Here, we used the capabilities of synchrotron-based Fourier Transform Infrared Microspectroscopy (SR-FTIRM) as a bio-analytical tool to elucidate the NP-induced cellular damage at the molecular level and at a single-cell scale. F98 glioma cells doped with AuNP and GdNP were irradiated using several types of medical ion beams (proton, helium, carbon and oxygen). Differences in cell composition were analyzed in the nucleic acids, protein and lipid spectral regions using multivariate methods (Principal Component Analysis, PCA). Several NP-induced cellular modifications were detected, such as conformational changes in secondary protein structures, intensity variations in the lipid CHx stretching bands, as well as complex DNA rearrangements following charged particle therapy irradiations. These spectral features seem to be correlated with the already shown enhancement both in the DNA damage response and in the reactive oxygen species (ROS) production by the NP, which causes cell damage in the form of protein, lipid, and/or DNA oxidations. Vibrational features were NP-dependent due to the NP heterogeneous radiosensitization capability. Our results provided new insights into the molecular changes in response to NP-based RT treatments using ion beams, and highlighted the relevance of SR-FTIRM as a useful and precise technique for assessing cell response to innovative radiotherapy approaches.

Molecular complexes of calf thymus DNA with various bioactive compounds: Formation and characterization

The interaction between biomacromolecules and ligands has attracted great interest because of their biological properties. Calf thymus DNA (ctDNA) can interact with bioactive compounds to form complexes. Here, ctDNA-ligand complexes were studied using fluorescence, absorption, and infrared spectroscopy, circular dichroism, ABTS assay and competitive displacement. The binding constants of bioactive compounds at the intercalative site of ctDNA ranked in order kaempferol > apigenin > quercetin > curcumin > riboflavin, while the binding constants at minor groove sites ranked quercetin > kaempferol > naringenin ~ apigenin > hesperetin > curcumin ~ resveratrol ~ riboflavin > caffeic acid. CtDNA maintained stable B-form with an enhancement of base stacking and a decrease of right-handed helicity in the presence of these bioactive compounds, except for hesperetin and caffeic acid. Bioactive compounds preferentially bound to guanine bases and tended to transfer into a more hydrophobic environment upon complexation with ctDNA. The DNA complexation did not affect the ABTS·⁺ scavenging capacity of quercetin, kaempferol, resveratrol and apigenin but increased the ones of naringenin, caffeic acid, curcumin, hesperetin and riboflavin. The data gathered here should be useful to understand the binding modes of DNA with ligands for their potential application in pharmaceutical and food industries.

Fourier transform infrared and Raman-based biochemical profiling of different grades of pure foetal-type hepatoblastoma

The biomolecular events resulting from the progression of hepatoblastoma remain to be elucidated. Fourier-transform infrared (FTIR) and Raman spectroscopies are capable of noninvasively and accurately capturing the biochemical properties of biological tissue from its pathological status. Our aim was to probe critial biomolecular changes of liver accompanying the progression of pure foetal hepatoblastoma (PFH) by FTIR and Raman spectroscopies. Herein, biochemical alterations were both evident in the FTIR spectra (regions of 3100-2800 cm^-1 and 1800-900 cm^-1 ) and the Raman spectra (region of 1800-400 cm^-1 ) among normal, borderline and malignant liver tissues. Compared with normal tissues, the ratios of protein-to-lipid, α-helix-to-β-sheet, RNA-to-DNA, CH3 methyl-to-CH2 methylene, glucose-to-phospholipids, and unsaturated-to-saturated lipids intensities were significantly higher in malignant tissues, while the ratios of RNA-to-Amide II, DNA-to-Amide II, glycogen-to-cholesterol and Amide I-to-Amide II intensities were remarkably lower. These biochemical alterations in the transition from normal to malignant have profound implications not only for cyto-pathological classification but also for molecular understanding of PFH progression. The successive changes of the spectral characteristics have been shown to be consistent with the development of PFH, indicating that FTIR and Raman spectroscopies are excellent tools to interrogate the biochemical features of different grades of PFH.

4-Nonylphenol effects on rat testis and sertoli cells determined by spectrochemical techniques coupled with chemometric analysis

Herein, vibrational spectroscopy has been applied for qualitative identification of biomolecular alterations that occur in cells and tissues following chemical treatment. Towards this end, we combined attenuated total reflection Fourier-transform infrared (ATR-FTIR) and Raman spectroscopy to assess testicular toxicology after 4-nonylphenol (NP) exposure, an estrogenic endocrine disruptor affecting testicular function in rats and other species. Rats aged 21, 35 or 50 days received NP at intra-peritoneal doses of 0, 25, 50 or 100 mg/kg for 20 consecutive days. Primary Sertoli cells (SCs) were treated with NP at various concentrations (0, 2.5, 5, 10 or 20 μM) for 12 h. Post-exposure, testicular cells, interstitial tissue and SCs were interrogated respectively using spectrochemical techniques coupled with multivariate analysis. Distinct biomolecular segregation between the NP-exposed samples vs. control were observed based on infrared (IR) spectral regions of 3200-2800 cm^-1 and 1800-900 cm^-1, and the Raman spectral region of 1800-900 cm^-1. For in vivo experiments, the main wavenumbers responsible for segregation varied significantly among the three age classes. The main IR and Raman band differences between NP-exposed and control groups were observed for Amide (proteins), lipids and DNA/RNA. An interesting finding was that the peptide aggregation level, Amide Ӏ-to-Amide II ratio, and phosphate-to-carbohydrate ratio were considerably reduced in ex vivo NP-exposed testicular cells or SCs in vitro. This study demonstrates that ATR-FTIR and Raman spectroscopy techniques can be applied towards analysing NP-induced testicular biomolecular alterations.

A synchrotron-based infrared microspectroscopy study on the cellular response induced by gold nanoparticles combined with X-ray irradiations on F98 and U87-MG glioma cell lines

Synchrotron-based infrared microspectroscopy is a powerful tool for nanoparticle-based treatment response at single cell-level.

Synchrotron-based infrared microspectroscopy study on the radiosensitization effects of Gd nanoparticles at megavoltage radiation energies

Synchrotron-based infrared microspectroscopy is a powerful technique for disentangling biochemical effects in nanoparticle-based radiotherapy approaches.

Metal-based NanoEnhancers for Future Radiotherapy: Radiosensitizing and Synergistic Effects on Tumor Cells

Radiotherapy is one of the major therapeutic strategies for cancer treatment. In the past decade, there has been growing interest in using high Z (atomic number) elements (materials) as radiosensitizers. New strategies in nanomedicine could help to improve cancer diagnosis and therapy at cellular and molecular levels. Metal-based nanoparticles usually exhibit chemical inertness in cellular and subcellular systems and may play a role in radiosensitization and synergistic cell-killing effects for radiation therapy. This review summarizes the efficacy of metal-based NanoEnhancers against cancers in both in vitro and in vivo systems for a range of ionizing radiations including gamma-rays, X-rays, and charged particles. The potential of translating preclinical studies on metal-based nanoparticles-enhanced radiation therapy into clinical practice is also discussed using examples of several metal-based NanoEnhancers (such as CYT-6091, AGuIX, and NBTXR3). Also, a few general examples of theranostic multimetallic nanocomposites are presented, and the related biological mechanisms are discussed.