Pd(II) and Pt(II) Trinuclear Chelates with Spermidine: Selective Anticancer Activity towards TNBC-Sensitive and -Resistant to Cisplatin

Vibrational microspectroscopy as a tool to unveil new chemotherapeutic strategies against osteosarcoma

Over the years, osteosarcoma therapy has had a significative improvement with the use of a multidrug regime strategy, increasing the survival rates from less than 20 % to circa 70 %. Different types of development of new antineoplastic agents are critical to achieve irreversible damage to cancer cells, while preserving the integrity of their healthy counterparts. In the present study, complexes with two and three Pd(II) centres linked by the biogenic polyamines: spermine (Pd2SpmCl4) and spermidine (Pd3Spd2Cl6) were tested against non-malignant (osteoblasts, HOb) and cancer (osteosarcoma, MG-63) human cell lines. Either alone or in combination according to the EURAMOS-1 protocol, they were used versus cisplatin as a drug reference. By evaluating the cytotoxic effects of both therapeutic approaches (single and drug combination) in HOb and MG-63 cell lines, the selective anti-tumoral potential is assessed. To understand the different treatments at a molecular level, Synchrotron Radiation Fourier Transform Infrared and Raman microspectroscopies were applied. Principal component analysis and hierarchical cluster analysis are applied to the vibrational data, revealing the major metabolic changes caused by each drug, which were found to rely on DNA, lipids, and proteins, acting as biomarkers of drug-to-cell impact. The main changes were observed for the B-DNA native conformation to either Z-DNA (higher in the presence of polynuclear complexes) or A-DNA (preferably after cisplatin exposure). Additionally, a higher effect upon variation in proteins content was detected in drug combination when compared to single drug administration proving the efficacy of the EURAMOS-1 protocol with the new drugs tested.

Synchrotron nano-FTIR spectroscopy for probing anticancer drugs at subcellular scale

The cellular response to cisplatin was assessed in human osteosarcoma cells, using synchrotron-based (SR) Fourier Transform InfraRed nanospectroscopy (nano-FTIR) at the MIRIAM beamline B22 of Diamond Light Source (UK). This label-free mapping method delivered simultaneous morphological and biochemical information on a subcellular level (i.e. 100 s nanometer or better). Based on specific spectral biomarkers, the main biochemical constituents affected by the drug were identified at distinct locations within the cell´s inner body. Cisplatin was shown to have a noteworthy effect on proteins, mostly within the cytoplasm. A clear drug impact on cellular lipids was also observed. Within current literature on s-SNOM, this nanospectroscopy work represents a first successful application in life sciences providing full fingerprint nano-FTIR spectra across intact human cancer cells.

Pd2Spermine as an Alternative Therapeutics for Cisplatin-Resistant Triple-Negative Breast Cancer

Cisplatin (cDDP) resistance is a matter of concern in triple-negative breast cancer therapeutics. We measured the metabolic response of cDDP-sensitive (S) and -resistant (R) MDA-MB-231 cells to Pd2Spermine(Spm) (a possible alternative to cDDP) compared to cDDP to investigate (i) intrinsic response/resistance mechanisms and (ii) the potential cytotoxic role of Pd2Spm. Cell extracts were analyzed by untargeted nuclear magnetic resonance metabolomics, and cell media were analyzed for particular metabolites. CDDP-exposed S cells experienced enhanced antioxidant protection and small deviations in the tricarboxylic acid cycle (TCA), pyrimidine metabolism, and lipid oxidation (proposed cytotoxicity signature). R cells responded more strongly to cDDP, suggesting a resistance signature of activated TCA cycle, altered AMP/ADP/ATP and adenine/uracil fingerprints, and phospholipid biosynthesis (without significant antioxidant protection). Pd2Spm impacted more markedly on R/S cell metabolisms, inducing similarities to cDDP/S cells (probably reflecting high cytotoxicity) and strong additional effects indicative of amino acid depletion, membrane degradation, energy/nucleotide adaptations, and a possible beneficial intracellular γ-aminobutyrate/glutathione-mediated antioxidant mechanism.

Disclosing a metabolic signature of cisplatin resistance in MDA-MB-231 triple-negative breast cancer cells by NMR metabolomics

This work compared the metabolic profile of a parental MDA-MB-231 cisplatin-sensitive triple negative breast cancer (TNBC) cell line with that of a derived cisplatin-resistant line, to characterize inherent metabolic adaptations to resistance, as a means for marker and new TNBC therapies discovery. Supported by cytotoxic, microscopic and biochemical characterization of both lines, Nuclear Magnetic Resonance (NMR) metabolomics was employed to characterize cell polar extracts for the two cell lines, as a function of time (0, 24 and 48 h), and identify statistically relevant differences both between sensitive and resistant cells and their time course behavior. Biochemical results revealed a slight increase in activation of the NF-κB pathway and a marked decrease of the ERK signaling pathway in resistant cells. This was accompanied by lower glycolytic and glutaminolytic activities, possibly linked to glutamine being required to increase stemness capacity and, hence, higher survival to cisplatin. The TCA cycle dynamics seemed to be time-dependent, with an apparent activation at 48 h preferentially supported by anaplerotic aromatic amino acids, leucine and lysine. A distinct behavior of leucine, compared to the other branched-chain-amino-acids, suggested the importance of the recognized relationship between leucine and in mTOR-mediated autophagy to increase resistance. Suggested markers of MDA-MB-231 TNBC cisplatin-resistance included higher phosphocreatine/creatine ratios, hypotaurine/taurine-mediated antioxidant protective mechanisms, a generalized marked depletion in nucleotides/nucleosides, and a distinctive pattern of choline compounds. Although the putative hypotheses generated here require biological demonstration, they pave the way to the use of metabolites as markers of cisplatin-resistance in TNBC and as guidance to develop therapies.