Potent in vitro antiproliferative properties for a triplatinum cluster toward triple negative breast cancer cells

Personalized treatment in metastatic triple-negative breast cancer: The outlook in 2020

Compared with other breast cancer subtypes, patients with triple-negative breast cancer (TNBC), and irrespective to their disease stage, were always recognized to have the worst overall survival data. Although this does not seem different at the present time, yet the last few years have witnessed many breakthrough genomic and molecular findings, that could dramatically improve our understanding of the biological complexity of TNBC. Based on genomic analyses, it was consistently evident that TNBC comprises a heterogeneous group of cancers, which have numerous diverse molecular aberrations. This-in return-has provided a platform for a new generation of clinical trials using many innovative therapies, directed against such novel targets. At the present time, two PARP inhibitors and one anti-PD-L1 monoclonal antibody (in combination with chemotherapy) have been approved in certain subpopulations of metastatic TNBC (mTNBC) patients, which have finally brought this disease into the era of personalized medicine. In the current review, we will explore the genomic landscape of TNBC, through which many actionable targets were graduated. We will also discuss the results of the key-practice changing-clinical studies, and some upcoming personalized treatment options for patients with mTNBC, that may be clinically adopted in the near future.

Bioconjugation of Cyclometalated Gold(III) Lipoic Acid Fragments to Linear and Cyclic Breast Cancer Targeting Peptides

Cell-targeting peptides (CTPs) are increasingly used in the field of cancer research due to their high affinity and specificity to cell or tissue targets. In the search for novel metal-based drug candidates, our research group is particularly focused on bioconjugates by utilizing peptides to increase the selectivity of cytotoxic organometallic compounds. Motivated by the relatively high cytotoxic activity of gold complexes, such as Auranofin (approved to treat rheumatoid arthritis), for the treatment of various diseases, we anticipated that gold peptide bioconjugates would present interesting candidates for novel breast cancer therapies. For this, we investigate the use of the natural compound lipoic acid (Lpa) as a bioconjugation handle to link Au complexes in the oxidation state +III to peptides using the dithiol moiety. Using this strategy, we have synthesized Au(III) complex bioconjugates linked to the linear LTVSPWY peptide and two cyclic DfKRG and KTTHWGFTLG tumor-targeting peptides. Solid-phase peptide synthesis (SPPS) was used to prepare the peptides, with lipoic acid introduced N-terminally as a conjugation handle. After peptide cleavage, the metal complex was introduced in solution by first reducing the internal disulfide bond, followed by reaction with Au(ppy)Cl₂ (1, ppy: 2-phenyl-pyridine), to yield the Au(III)-Lpa-peptide bioconjugates. The new bioconjugates were successfully synthesized, purified by semi-preparative HPLC, and characterized by ESI-MS. Au(III)-peptide bioconjugates were tested as cytotoxic agents against two different human breast cancer cell lines (MCF-7 and MDA-MB-231) and normal human fibroblasts cells (GM5657T) and compared to cisplatin, the parent Au(III) dichloride complex, and metal-free peptides. These in vitro data show that the Au(III)-peptide bioconjugate 5, possessing the cyclic integrin-targeting RGD-derived peptide sequence in the structure, exhibits improved activity compared to the parent gold(III) compound Au(ppy)Cl₂ (1) as well as to cisplatin or the metal-free peptide. Moreover, the excellent targeting properties of 5 are supported by the fact that a Au(III)-peptide conjugate with the exact same peptide sequence, but a linear rather than the cyclic form of 5 exhibits 10 times lower cytotoxic activity.

ESI-MS studies of the reactions of novel platinum(II) complexes containing O,O'-chelated acetylacetonate and sulfur ligands with selected model proteins

A group of mixed-ligand Pt(II) complexes bearing acetylacetonate and sulphur ligands were recently developed in the University of Lecce as a new class of prospective anticancer agents that manifested promising pharma-cological properties in preliminary in vitro and in vivo tests. Though modelled on the basis of cisplatin, these Pt(II) complexes turned out to exhibit a profoundly distinct mode of action as they were found to act mainly on non-genomic targets rather than on DNA. Accordingly, we have explored here their reactions with two representative model proteins through an established ESI-MS procedure with the aim to describe their general interaction mechanism with protein targets. A pronounced reactivity with the tested proteins was indeed documented; the nature of the resulting metallodrug-protein interactions could be characterised in depth in the various cases. Preferential binding to protein targets compared to DNA is supported by independent ICP-OES measurements. The implications of these findings are discussed.

In Vitro Screening for Cytotoxic Activity of Herbal Extracts

Experimental studies have shown that a variety of chemopreventive plant components affect tumor initiation, promotion, and progression and the main difference, between botanical medicines and synthetic drugs, resides in the presence of complex metabolite mixtures shown by botanical medicine which in turn exert their action on different levels and via different mechanisms. In the present study, we performed an in vitro screening of ethanol extracts from commercial plants in order to investigate potential antitumor activity against human tumor cell lines. Experimental results obtained through a variety of methods and techniques indicated that extracts of I. verum, G. glabra, R. Frangula, and L. usitatissimum present significant reduction in in vitro tumor cell proliferation, suggesting these extracts as possible chemotherapeutical adjuvants for different cancer treatments.