Single-Cell Chemistry of Photoactivatable Platinum Anticancer Complexes

Abstract

The Pt(IV) prodrug trans, trans, trans-[Pt(pyridine) 2 (N 3 ) 2 (OH) 2 ] (Pt1) and its coumarin derivative trans, trans, trans-[Pt(pyridine) 2 (N 3 ) 2 (OH)(coumarin-3-carboxylate)] (Pt2) are promising agents for photoactivated chemotherapy. These complexes are inert in the dark but release Pt(II) species and radicals upon visible light irradiation, resulting in photocytotoxicity toward cancer cells. Here, we have used synchrotron techniques to investigate the in-cell behavior of these prodrugs and visualize, for the first time, changes in cellular morphology and Pt localization upon treatment with and without light irradiation. We show that photoactivation of Pt2 induces remarkable cellular damage with extreme alterations to multiple cellular components, including formation of vacuoles, while also significantly increasing the cellular accumulation of Pt species compared to dark conditions. X-ray absorption near-edge structure (XANES) measurements in cells treated with Pt2 indicate only partial reduction of the prodrug upon irradiation, highlighting that phototoxicity in cancer cells may involve not only Pt(II) photoproducts but also photoexcited Pt(IV) species.

A guide into the world of high-resolution 3D imaging: the case of soft X-ray tomography for the life sciences

“…An example is seen in studies that have surveyed the involvement of calcium in biomineralization processes in bone tissues [ 35 , 62 ]. Also, for the first time to our knowledge, a combination of cryoSXT, nanofocused X-ray fluorescence (XRF) and XANES spectroscopy were used to establish the near-native single-cell chemistry of an anti-cancer compound- photoactivatable diazido platinum (IV) complexes [ 48 ].…”

“…At this same beamline, cryoSXT has been paired with synchrotron-based Fourier transform infrared microspectroscopy (SR-μFTIR), albeit, on different microscopes and different sample preparation methods [ 66 ]. Pairing cryoSXT with XANES at non-cryogenic temperatures has also been documented using higher-energy X-rays on samples that have been recovered and freeze-dried after SXT [ 48 ].…”

“…Users can receive training on the use of instruments and software and are expected to collect their own data (remotely or in-person on site) and are highly encouraged to deposit it once published to public archives to allow unfettered access and opportunity for scrutiny to colleagues in the same or related fields [46]. The user base at beamline B24 are predominantly academics investigating areas of interest within the biomedical sciences and who target systems such as: pathogen-host interactions, immunity, cell death, cancer, vaccine and drug development as well as basic cellular biology mechanisms and response to environmental stressors [22,[47][48][49][50][51][52][53][54][55].…”

“…Representative studies aided by SXT include, the discovery of a new cytotoxic membrane-less organelle that killer T-cells deposit on the surface of their targets (Figure 4a), the tracking of F-actin structures in mammalian cells (Figure 4b), the charting of plasmodium egress mechanisms in infected human red blood cells (Figure 4c), SARS-CoV2 intracellular progress and egress in the late stages of infection (Figure 4d), reovirus vesicle escape Localization of reoviruses in multivesicular bodies [22]. (g) The selective cellular uptake and localization of photo-activatable anti-cancer compounds [48]. (h) Distribution trends of Chlamydiae populations in intracellular inclusions in infected human cells in the early stages of infection (Figure 4e,f ), the selective cellular uptake and localization of photo-activatable anti-cancer compounds (Figure 4g), distribution trends of Chlamydiae populations in intracellular inclusions in infected human cells and (Figure 4h), mitochondrial targeting by an organoiridium photosensitiser (Figure 4i) [22,47,[49][50][51][52][53].…”

“…( f ) Localization of reoviruses in multivesicular bodies [ 22 ]. ( g ) The selective cellular uptake and localization of photo-activatable anti-cancer compounds [ 48 ]. ( h ) Distribution trends of Chlamydiae populations in intracellular inclusions in infected human cells [ 53 ].…”