Correlation between daily life aluminium exposure and breast cancer risk: A systematic review

BACKGROUND

Epidemiological data indicate that the role of environmental factors on breast cancer (BC) incidence remains undetermined. Our daily life exposure to aluminium (Al) is suspected to influence BC development. This review proposes a state of the art on the association between Al and BC risk combined with a critical point of view on the subject.

METHODS

We searched the PubMed database using terms related to Al and BC up to November 18, 2022. Reports were eligible if they were cohort or case-control studies or meta-analyses.

FINDINGS

Six studies focused on the relationship between deodorant and antiperspirant use and BC incidence and didn't produce consistent results. Among 13 studies relating Al content in mammary tissues and BC risk, results are not unanimous to validate higher Al content in tumor tissues compared to healthy ones. We detail parameters that could explain this conclusion: the absence of statistical adjustments on BC risk factors in studies, the confusion between deodorant and antiperspirant terms, the non-assessment of global Al exposure, and the focus on Al in mammary tissues whereas a profile of several metals seems more appropriate. The clinical studies are retrospective. They were carried out on small cohorts and without a long follow-up. On the other hand, studies on cell lines have shown the carcinogenic potential of aluminum. Moreover, studies considered BC as a unique group whereas BC is a heterogeneous disease with multiple tumor subtypes determining the tumor aggressiveness.

CONCLUSION

In light of the precautionary principle and based on the data obtained, it is better to avoid antiperspirants that contain Al. Deodorants without aluminum are not implicated in breast cancer, either clinically or fundamentally.

Preliminary Study of New Gallium-68 Radiolabeled Peptide Targeting NRP-1 to Detect Brain Metastases by Positron Emission Tomography

Due to their very poor prognosis and a fatal outcome, secondary brain tumors are one of the biggest challenges in oncology today. From the point of view of the early diagnosis of these brain micro- and macro-tumors, the sensitivity and specificity of the diagnostic tools constitute an obstacle. Molecular imaging, such as Positron Emission Tomography (PET), is a promising technique but remains limited in the search for cerebral localizations, given the commercially available radiotracers. Indeed, the [18F]FDG PET remains constrained by the physiological fixation of the cerebral cortex, which hinders the visualization of cerebral metastases. Tumor angiogenesis is recognized as a crucial phenomenon in the progression of malignant tumors and is correlated with overexpression of the neuropilin-1 (NRP-1) receptor. Here, we describe the synthesis and the photophysical properties of the new gallium-68 radiolabeled peptide to target NRP-1. The KDKPPR peptide was coupled with gallium-68 anchored into a bifunctional NODAGA chelating agent, as well as Cy5 for fluorescence detection. The Cy5 absorbance spectra did not change, whereas the molar extinction coefficient (ε) decreased drastically. An enhancement of the fluorescence quantum yield (φF) could be observed due to the better water solubility of Cy5. [68Ga]Ga-NODAGA-K(Cy5)DKPPR was radiosynthesized efficiently, presented hydrophilic properties (log D = -1.86), and had high in vitro stability (>120 min). The molecular affinity and the cytotoxicity of this new chelated radiotracer were evaluated in vitro on endothelial cells (HUVEC) and MDA-MB-231 cancer cells (hormone-independent and triple-negative line) and in vivo on a brain model of metastasis in a nude rat using the MDA-MB-231 cell line. No in vitro toxicity has been observed. The in vivo preliminary experiments showed promising results, with a high contrast between the healthy brain and metastatic foci for [68Ga]Ga-NODAGA-K(Cy5)DKPPR.

Interplay between Cellular Uptake, Intracellular Localization and the Cell Death Mechanism in Triphenylamine-Mediated Photoinduced Cell Death

Triphenylamines (TPAs) were previously shown to trigger cell death under prolonged one- or two-photon illumination. Their initial subcellular localization, before prolonged illumination, is exclusively cytoplasmic and they translocate to the nucleus upon photoactivation. However, depending on their structure, they display significant differences in terms of precise initial localization and subsequent photoinduced cell death mechanism. Here, we investigated the structural features of TPAs that influence cell death by studying a series of molecules differing by the number and chemical nature of vinyl branches. All compounds triggered cell death upon one-photon excitation, however to different extents, the nature of the electron acceptor group being determinant for the overall cell death efficiency. Photobleaching susceptibility was also an important parameter for discriminating efficient/inefficient compounds in two-photon experiments. Furthermore, the number of branches, but not their chemical nature, was crucial for determining the cellular uptake mechanism of TPAs and their intracellular fate. The uptake of all TPAs is an active endocytic process but two- and three-branch compounds are taken up via distinct endocytosis pathways, clathrin-dependent or -independent (predominantly caveolae-dependent), respectively. Two-branch TPAs preferentially target mitochondria and photoinduce both apoptosis and a proper necrotic process, whereas three-branch TPAs preferentially target late endosomes and photoinduce apoptosis only.

Fighting Hypoxia to Improve PDT

Photodynamic therapy (PDT) has drawn great interest in recent years mainly due to its low side effects and few drug resistances. Nevertheless, one of the issues of PDT is the need for oxygen to induce a photodynamic effect. Tumours often have low oxygen concentrations, related to the abnormal structure of the microvessels leading to an ineffective blood distribution. Moreover, PDT consumes O2. In order to improve the oxygenation of tumour or decrease hypoxia, different strategies are developed and are described in this review: 1) The use of O2 vehicle; 2) the modification of the tumour microenvironment (TME); 3) combining other therapies with PDT; 4) hypoxia-independent PDT; 5) hypoxia-dependent PDT and 6) fractional PDT.

Use of Cyclodextrins in Anticancer Photodynamic Therapy Treatment

Photodynamic therapy (PDT) is mainly used to destroy cancerous cells; it combines the action of three components: a photoactivatable molecule or photosensitizer (PS), the light of an appropriate wavelength, and naturally occurring molecular oxygen. After light excitation of the PS, the excited PS then reacts with molecular oxygen to produce reactive oxygen species (ROS), leading to cellular damage. One of the drawbacks of PSs is their lack of solubility in water and body tissue fluids, thereby causing low bioavailability, drug-delivery efficiency, therapeutic efficacy, and ROS production. To improve the water-solubility and/or drug delivery of PSs, using cyclodextrins (CDs) is an interesting strategy. This review describes the in vitro or/and in vivo use of natural and derived CDs to improve antitumoral PDT efficiency in aqueous media. To achieve these goals, three types of binding modes of PSs with CDs are developed: non-covalent CD⁻PS inclusion complexes, covalent CD⁻PS conjugates, and CD⁻PS nanoassemblies. This review is divided into three parts: (1) non-covalent CD-PS inclusion complexes, covalent CD⁻PS conjugates, and CD⁻PS nanoassemblies, (2) incorporating CD⁻PS systems into hybrid nanoparticles (NPs) using up-converting or other types of NPs, and (3) CDs with fullerenes as PSs.

Titania and silica nanoparticles coupled to Chlorin e6 for anti-cancer photodynamic therapy

In this study, light-sensitive photosensitizers (Chlorin e6, Ce6) were linked to TiO₂ and SiO₂ nanoparticles (NPs) in order to develop new kinds of NP-based drug delivery systems for cancer treatment by PDT. TiO₂ or SiO₂ NPs were modified either by the growth of a polysiloxane layer constituted of two silane reagents ((3-aminopropyl)triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS)) around the core (PEGylated NPs: TiO₂@4Si-Ce6-PEG, SiO₂@4Si-Ce6-PEG) or simply modified by APTES alone (APTES-modified NPs: TiO₂-APTES-Ce6, SiO₂-APTES-Ce6). Ce6 was covalently attached onto the modified TiO₂ and SiO₂ NPs via an amide bond. The absorption profile of the hybridized NPs was extended to the visible region of the light. The physicochemical properties of these NPs were explored by TEM, HR-TEM, XRD, FTIR and zeta potential. The photophysical characteristics including the light absorption, the fluorescence properties and the production reactive oxygen species (¹O₂ and HO) were also addressed. In vitro experiments on glioblastoma U87 cells were performed to evaluate the photodynamic efficiency of the new hybridized NPs. The cells were exposed to different concentrations of NPs and illuminated (λ_exc = 652 nm, fluence rate 10 J/cm²). In contrast to the PEGylated NPs, the APTES-modified nanosystems were found to be more efficient for PDT. An interesting photodynamic effect was observed in the case of TiO₂-APTES-Ce6 NPs. After illumination, the viability of U87 was decreased by 89% when they were exposed to 200 μg/mL of TiO₂-APTES-Ce6 NPs, which corresponds to 0.22 μM of Ce6. The same effect can be obtained with free photosensitizer but using a higher concentration of 10 μM of Ce6.

Proton MR Spectroscopy and Diffusion MR Imaging Monitoring to Predict Tumor Response to Interstitial Photodynamic Therapy for Glioblastoma

Despite recent progress in conventional therapeutic approaches, the vast majority of glioblastoma recur locally, indicating that a more aggressive local therapy is required. Interstitial photodynamic therapy (iPDT) appears as a very promising and complementary approach to conventional therapies. However, an optimal fractionation scheme for iPDT remains the indispensable requirement. To achieve that major goal, we suggested following iPDT tumor response by a non-invasive imaging monitoring. Nude rats bearing intracranial glioblastoma U87MG xenografts were treated by iPDT, just after intravenous injection of AGuIX® nanoparticles, encapsulating PDT and imaging agents. Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) allowed us an original longitudinal follow-up of post-treatment effects to discriminate early predictive markers. We successfully used conventional MRI, T2 star (T2*), Diffusion Weighted Imaging (DWI) and MRS to extract relevant profiles on tissue cytoarchitectural alterations, local vascular disruption and metabolic information on brain tumor biology, achieving earlier assessment of tumor response. From one day post-iPDT, DWI and MRS allowed us to identify promising markers such as the Apparent Diffusion Coefficient (ADC) values, lipids, choline and myoInositol levels that led us to distinguish iPDT responders from non-responders. All these responses give us warning signs well before the tumor escapes and that the growth would be appreciated.

Indocyanine green: photosensitizer or chromophore? Still a debate

Indocyanine green (ICG) is a water-soluble anionic tricarbocyanine dye developed during the Second World War that was first approved for clinical use in humans in 1956. The main features of ICG that make it suitable for bioimaging applications are its near infrared absorption and its fluorescence. Although ICG is mainly used for its fluorescence emission properties, it has also been hypothesized that it can serve as a photosensitizer for photodynamic therapy applications, eliciting cytotoxic effects both in vitro and in vivo when used in combination with light at wavelengths in the region of 800-830 nm. Moreover, ICG can be used for hyperthermia of enhanced-photocoagulation of blood vessels treatment. In this paper we have gathered all the available data concerning the use of ICG for different treatments.

Ultrasmall Nanoplatforms as Calcium-Responsive Contrast Agents for Magnetic Resonance Imaging

The preparation of ultrasmall and rigid platforms (USRPs) that are covalently coupled to macrocycle-based, calcium-responsive/smart contrast agents (SCAs), and the initial in vitro and in vivo validation of the resulting nanosized probes (SCA-USRPs) by means of magnetic resonance imaging (MRI) is reported. The synthetic procedure is robust, allowing preparation of the SCA-USRPs on a multigram scale. The resulting platforms display the desired MRI activity—i.e., longitudinal relaxivity increases almost twice at 7 T magnetic field strength upon saturation with Ca(2+). Cell viability is probed with the MTT assay using HEK-293 cells, which show good tolerance for lower contrast agent concentrations over longer periods of time. On intravenous administration of SCA-USRPs in living mice, MRI studies indicate their rapid accumulation in the renal pelvis and parenchyma. Importantly, the MRI signal increases in both kidney compartments when CaCl2 is also administrated. Laser-induced breakdown spectroscopy experiments confirm accumulation of SCA-USRPs in the renal cortex. To the best of our knowledge, these are the first studies which demonstrate calcium-sensitive MRI signal changes in vivo. Continuing contrast agent and MRI protocol optimizations should lead to wider application of these responsive probes and development of superior functional methods for monitoring calcium-dependent physiological and pathological processes in a dynamic manner.

Microwave-assisted synthesis of zinc 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin and zinc 5-(4-carboxyphenyl)-10,15,20-triphenylchlorin

The microwave-assisted synthesis of zinc 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin and zinc 5-(4-carboxyphenyl)-10,15,20-triphenylchlrorin are described and compared to classic conditions of synthesis in terms of time of reaction and yields obtained. The new experimental protocols are easy to implement required small amounts of reagents and solvents and lead to short reaction times. All compounds have been characterized by 1 H NMR, MS and spectroscopic techniques.