Inhibition of nuclear factor kappaB proteins-platinated DNA interactions correlates with cytotoxic effectiveness of the platinum complexes

Elucidating the dual mechanistic action and synergism of platinum complexes bearing valproic acid as leaving ligand on NF-κB and inflammatory pathways in glioma

The valproic acid (VPA), an anti-epileptic drug, has demonstrated anticancer properties alone or in combination regimens in glioma. It has been shown synergistic activity with cisplatin in resistant cancer cells. In the current study, we synthesized Pt(II) complexes bearing VPA as ancillary/leaving ligand. All these complexes were obtained in good yields through simple reproducible synthetic procedures and characterized by multiple analytical techniques in both solution and solid state. In situ release of ancillary ligand (VPA) by these complexes was studied by 1H NMR in solution state that was catalysed by water in time dependent manner. The tumor preferential selective VPA-Pt actively controlling NF-kB signaling, culminating in the attenuation of IL-6 expression and the concomitant activation of p53 and caspase-3 pathways in gliomas. VPA-Pt exhibits potent cytotoxicity in human and mice glioma cancer cell lines, inducing apoptosis as evidenced by inhibition of cell proliferation and migration, disruption of mitochondrial membrane potential, and suppression of colony formation. An inhibitory effect of VPA-Pt4 on glioma was clearly evidenced through in vivo live bioluminescence imaging, histopathological examination, immunofluorescence evaluation, and protein expression analysis demonstrated that VPA-Pt4 significantly triggered apoptosis, with elevated levels of P53, caspase-3, cleaved caspase-3, along with a reduction in IL-6. Our discovery reveals a novel and efficient approach to glioma therapy.

What happened to BBR3464 and where to from here for multinuclear platinum-based anticancer drugs?

The development of the trinuclear platinum(II) complex BBR3464 (also known as triplatin) in the late 1990s was meant to be a revolution in the field of platinum chemotherapy. What made it remarkable was that it defied many of the known structure-activity rules for platinums; it is cationic, has a single labile trans leaving group on each terminal platinum, and it binds DNA in ways different to mononuclear platinum drugs, like cisplatin and oxaliplatin. The flexible, long-range adducts the drug forms with DNA means that it showed activity in cancers not typically sensitive to platinums, and more importantly, BBR3464 demonstrated an ability to overcome acquired resistance to platinum drugs. But while preclinical and phase I testing showed promise, its more severe side effects which greatly limited the deliverable dose when compared with standard platinums, combined with its lack of biostability, led to a lack of activity in phase II trials and its development was halted. But, from its ashes have risen 4th generation complexes which target the phosphate backbone of DNA. These, and the original BBR3464 drug, could potentially be further developed and gain regulatory approval through formulation with macrocycle-based drug delivery vehicles.

Inhibition of NF-κB-Mediated Proinflammatory Transcription by Ru(II) Complexes of Anti-Angiogenic Ligands in Triple-Negative Breast Cancer

Nuclear factor kappa beta (NF-κB) plays a pivotal role in breast cancer, particularly triple-negative breast cancer, by promoting inflammation, proliferation, epithelial-mesenchymal transition, metastasis, and drug resistance. Upregulation of NF-κB boosts vascular endothelial growth factor (VEGF) expression, assisting angiogenesis. The Ru(II) complexes of methyl- and dimethylpyrazolyl-benzimidazole N,N donors inhibit phosphorylation of ser536 in p65 and translocation of the NF-κB heterodimer (p50/p65) to the nucleus, disabling transcription to upregulate inflammatory signaling. The methyl- and dimethylpyrazolyl-benzimidazole inhibit VEGFR2 phosphorylation at Y1175, disrupting downstream signaling through PLC-γ and ERK1/2, ultimately suppressing Ca(II)-signaling. Partial release of the antiangiogenic ligand in a reactive oxygen species-rich environment is possible as per our observation to inhibit both NF-κB and VEGFR2 by the complexes. The complexes are nontoxic to zebrafish embryos up to 50 μM, but the ligands show strong in vivo antiangiogenic activity at 3 μM during embryonic growth in Tg(fli1:GFP) zebrafish but no visible effect on the adult phase.

A novel coordination complex of platinum (PT) induces cell death in colorectal cancer by altering redox balance and modulating MAPK pathway

Background

Colorectal cancer (CRC) is a heterogeneous tumor having various genetic alterations. The current treatment options had limited impact on disease free survival due to therapeutic resistance. Novel anticancer agents are needed to treat CRC specifically metastatic colorectal cancer. A novel coordination complex of platinum, (salicylaldiminato)Pt(II) complex with dimethylpropylene linkage (PT) exhibited potential anti-cancer activity. In this study, we explored the molecular mechanism of PT-induced cell death in colorectal cancer.

Methods

Colony formation was evaluated using the clonogenic assay. Apoptosis, cell cycle analysis, reactive oxygen species, mitochondrial membrane potential and caspase-3/− 7 were assessed by flow cytometry. Glutathione level was detected by colorimetric assay. PT-induced alteration in pro-apoptotic/ anti-apoptotic proteins and other signaling pathways were investigated using western blotting. P38 downregulation was performed using siRNA.

Results

In the present study, we explored the molecular mechanism of PT-mediated inhibition of cell proliferation in colorectal cancer cells. PT significantly inhibited the colony formation in human colorectal cancer cell lines (HT-29, SW480 and SW620) by inducing apoptosis and necrosis. This platinum complex was shown to significantly increase the reactive oxygen species (ROS) generation, depletion of glutathione and reduced mitochondrial membrane potential in colorectal cancer cells. Exposure to PT resulted in the downregulation of anti-apoptotic proteins (Bcl2, BclxL, XIAP) and alteration in Cyclins expression. Furthermore, PT increased cytochrome c release into cytosol and enhanced PARP cleavage leading to activation of intrinsic apoptotic pathway. Moreover, pre-treatment with ROS scavenger N-acetylcysteine (NAC) attenuated apoptosis suggesting that PT-induced apoptosis was driven by oxidative stress. Additionally, we show that PT-induced apoptosis was mediated by activating p38 MAPK and inhibiting AKT pathways. This was demonstrated by using chemical inhibitor and siRNA against p38 kinase which blocked the cytochrome c release and apoptosis in colorectal cancer cells.

Conclusion

Collectively, our data demonstrates that the platinum complex (PT) exerts its anti-proliferative effect on CRC by ROS-mediated apoptosis and activating p38 MAPK pathway. Thus, our findings reveal a novel mechanism of action for PT on colorectal cancer cells and may have therapeutic implication.

Treatment patterns and outcomes in patients with non-small cell lung cancer receiving biosimilar filgrastim for prophylaxis of chemotherapy-induced/febrile neutropaenia: Results from the MONITOR-GCSF study

Objective

Real‐world evidence data on the use of granulocyte colony‐stimulating factor (G‐CSF) in patients with non‐small cell lung cancer (NSCLC) are limited. MONITOR‐GCSF is a pan‐European, multicentre, prospective, non‐interventional study designed to describe patient characteristics, treatment patterns and clinical outcomes in patients receiving biosimilar filgrastim in the prophylaxis of chemotherapy‐induced neutropaenia (CIN) and febrile neutropaenia (FN).

Methods

In this subanalysis, patient characteristics, treatment patterns, and outcomes are described for 345 patients with stage 3 or 4 NSCLC, receiving up to six chemotherapy cycles. Patients were treated with biosimilar filgrastim as per their treating physician's best judgement.

Results

CIN (any grade) occurred in 13.6% of patients in Cycle 1 and in 36.5% of patients in all cycles. FN occurred in 1.4% of patients in Cycle 1 and in 5.2% of patients in all cycles. Grade 3–4 FN occurred in 1.2% of patients in Cycle 1 and in 3.8% of patients in all cycles.

Conclusion

Results show that in real‐life practice in patients with NSCLC, biosimilar filgrastim has similar effectiveness and safety to the known effectiveness and safety profile of reference filgrastim, supporting the use of biosimilar filgrastim for the real‐world treatment of neutropaenia in patients with NSCLC.

Translesion DNA synthesis across double-base lesions derived from cross-links of an antitumor trinuclear platinum compound: primer extension, conformational and thermodynamic studies

Polynuclear platinum complexes represent a unique structural class of DNA-binding agents of biological significance. They contain at least two platinum coordinating units bridged by a linker, which means that the formation of double-base lesions (cross-links) in DNA is possible. Here, we show that the lead compound, bifunctional [{trans-PtCl(NH₃)₂}₂μ-trans-Pt(NH₃)₂{H₂N(CH₂)₆NH₂}₂]⁴⁺ (Triplatin or BBR3464), forms in DNA specific double-base lesions which affect the biophysical and biochemical properties of DNA in a way fundamentally different compared to the analogous double-base lesions formed by two adducts of monofunctional chlorodiethylenetriamineplatinum(ii) chloride (dienPt). We find concomitantly that translesion DNA synthesis by the model A-family polymerase, the exonuclease deficient Klenow fragment, across the double-base lesions derived from the intrastrand CLs of Triplatin was markedly less extensive than that across the two analogous monofunctional adducts of dienPt. Collectively, these data provide convincing support for the hypothesis that the central noncovalent tetraamine platinum linker of Triplatin, capable of hydrogen-bonding and electrostatic interactions with DNA and bridging the two platinum adducts, represents an important factor responsible for the markedly lowered tolerance of DNA double-base adducts of Triplatin by DNA polymerases.