Gold(I) Complexes Bearing Alkylated 1,3,5-Triaza-7-phosphaadamantane Ligands as Thermoresponsive Anticancer Agents in Human Colon Cells

Abstract

Overheating can affect solubility or lipophilicity, among other properties, of some anticancer drugs. These temperature-dependent changes can improve efficiency and selectivity of the drugs, since they may affect their bioavailability, diffusion through cell membrane or activity. One recent approach to create thermosensitive molecules is the incorporation of fluorine atoms in the chemical structure, since fluor can tune some chemical properties such as binding affinity. Herein we report the anticancer effect of gold derivatives with phosphanes derived from 1,3,5-triaza-7-phosphaadamantane (PTA) with long hydrocarbon chains and the homologous fluorinated chains. Besides, we analysed the influence of temperature in the cytotoxic effect. The studied gold(I) complexes with phosphanes derived from PTA showed antiproliferative effect on human colon carcinoma cells (Caco-2/TC7 cell line), probably by inhibiting cellular TrxR causing a dysfunction in the intracellular redox state. In addition, the cell cycle was altered by the activation of p53, and the complexes produce apoptosis through mitochondrial depolarization and the consequent activation of caspase-3. Furthermore, the results suggest that this cytotoxic effect is enhanced by hyperthermia and the presence of polyfluorinated chains.

Sulfonamide-Derived Dithiocarbamate Gold(I) Complexes Induce the Apoptosis of Colon Cancer Cells by the Activation of Caspase 3 and Redox Imbalance

“…Human epithelial fibroblast cells (NHDF-Ad, Lonza ®® , Porriño, Spain) were kindly provided by Dr. Gracia Mendoza (Aragon Health Research Institute, IIS Aragón, Spain). Caco-2 cells (passages 40–70) and fibroblasts (passages 10–30) were maintained in a humidified atmosphere of 5% CO 2 at 37 °C and grown in medium following the method used by Quero et al [ 59 ]. The Caco-2 cells were sub-cultured in 25 cm 2 plastic flasks at a density of 1.2 × 10 4 cells/cm 2 , while the fibroblasts were sub-cultured on 75 cm 2 plastic flasks at a density of 1 × 10 4 cells/cm 2 .…”

“…After 15 min of incubation at room temperature protected from light, 400 µL annexin binding buffer was added to each sample, and the signal intensity was analyzed within 1 h with Beckman Coulter Gallios (Brea, CA, USA). The data were analyzed with BD FACSDivaTM [ 59 ].…”

“…Once the cells were seeded in 25 cm 2 flasks at a density of 1 × 10 4 cells/cm 2 , they were exposed, after 24 post-sendings, to the drug panel for 48 or 72 h. The cells were fixed according to the previously described methods [ 59 , 60 ] before being stained with 50 μg/mL PI solution. The signal intensity was analysed with a Beckman Coulter Gallios (Brea, CA, USA) equipped with a blue solid diode laser (488 nm) and a red solid diode laser (635 nm), collecting fluorescence with a 620 nm-long pass filter.…”

“…Caco-2 cells were seeded in 75 cm 2 flasks at a density of 1 × 10 4 cells/cm 2 , and the 24-h post-seeding medium was replaced with medium containing the drug panel; it was then incubated for 48 or 72 h. The cells were then washed twice and resuspended in PBS at a concentration of 10 6 cells/mL before incubation with 5 µL of 10 µM 1,1′,3,3,3′-hexamethylindodicarbo-cyanine iodide (DilC1). After 15 min of incubation at 37 °C, 400 µL PBS was added, and the fluorescence was measured by flow cytometry at an excitation wavelength of 633 nm and an emission of 658 nm with a Beckman Coulter Gallios (Brea, CA, USA) equipped with a blue solid diode laser (488 nm) and a red solid diode laser (635 nm) [ 59 ].…”

“…Caco-2 cells were seeded in a 75 cm 2 flask at a density of 1 × 10 4 cells/cm 2 ; 24 h later, they were exposed to the drug panel for 48 or 72 h. Then, the cells were collected and processed as previously described [ 59 , 61 ]. Finally, 50 µL of every sample was incubated with 5 µL anti-active caspase-3 (BD Pharmigen, San Diego, CA, USA, Clone C92-605) and 5 µL p53 antibody (Miltenyi, Auburn, CA, USA, Clone REA609).…”