A (salicylaldiminato)Pt(II) complex with dimethylpropylene linkage: Synthesis, structural characterization and antineoplastic activity

The platinum coordination complex inhibits cell invasion-migration and epithelial-to-mesenchymal transition by altering the TGF-β-SMAD pathway in colorectal cancer

Introduction: There is a steady increase in colorectal cancer (CRC) incidences worldwide; at diagnosis, about 20 percent of cases show metastases. The transforming growth factor-beta (TGF-β) signaling pathway is one of the critical pathways that influence the expression of cadherins allowing the epithelial-to-mesenchymal transition (EMT), which is involved in the progression of the normal colorectal epithelium to adenoma and metastatic carcinoma. The current study aimed to investigate the impact of a novel coordination complex of platinum (salicylaldiminato) PT(II) complex with dimethyl propylene linkage (PT-complex) on TGF-β and EMT markers involved in the invasion and migration of the human HT-29 and SW620 CRC cell lines. Methods: Functional study and wound healing assay showed PT-complex significantly reduced cell motility and the migration and invasion of CRC cell lines compared to the untreated control. Western blot performed in the presence and absence of TGF-β demonstrated that PT-complex significantly regulated the TGF-β-mediated altered expressions of EMT markers. Results and Discussion: PT-complex attenuated the migration and invasion by upregulating the protein expression of EMT-suppressing factor E-cadherin and suppressing EMT-inducing factors such as N-Cadherin and Vimentin. Moreover, PT-complex significantly suppressed the activation of SMAD3 in both CRC cell lines. Further, the microarray data analysis revealed differential expression of genes related to invasion and migration. In conclusion, besides displaying antiproliferative activity, the PT complex can decrease the metastasis of CRC cell lines by modulating TGF-β-regulated EMT markers. These findings provide new insight into TGF-β/SMAD signaling as the molecular mechanism involved in the antitumoral properties of novel PT-complex.

New Bi-Nuclear Nickel(II) Complex-Based Salen Schiff Base: Synthesis, Crystal Structure, Spectroscopic, Thermal, and Electrical Investigations

In this study, a new bi-nuclear nickel complex [Ni2HL2(EtOH)2](Cl)(EtOH) of a Schiff base ligand, 2-[3-[2-hydroxybenzylideneamino]propyliminomethyl]phenol, was synthesized and characterized using UV/Vis, IR, HRMS, and TGA/DTA analysis. The molecular structure of the obtained complex was corroborated by the single crystal X-ray diffraction technique. It was found in the complex that two molecules of the ligand coordinate with two nickel atoms through azomethine-N and phenoxy-O, resulting in 6-coordinate distorted octahedral geometry, in which two ethanol molecules occupy the axial positions. The dielectric and electrical properties of the obtained samples were studied by impedance spectroscopy at different frequencies (from 1 Hz to 1 MHz) in the temperature range 298–343 K. It is found that the electrical conductivity of the Ni(II) complex is lower than that of the free ligand H2L, suggesting that the complexation traps the charge carriers contained in the ligand.

Structural and Theoretical Investigations, Hirshfeld Surface Analyses, and Cytotoxicity of a Naphthalene-Based Chiral Compound

A novel Schiff base compound derived from the condensation of 2-hydroxy-1-naphthaldehyde with (1S,2S)-(-)-1,2-diphenylethylenediamine in 2:1 M ratio was reported and investigated by elemental analyses, Fourier transform infrared and NMR spectroscopic studies, and single-crystal X-ray crystallography. Hirshfeld surface analyses were also carried out to measure the various intermolecular contacts controlling the supramolecular topology, suggesting the H···O (7.6%) contacts to be the most significant interactions, whereas the H···H (48.9%) and C···H (40.2%) interactions are less-significant. The data obtained from the energy calculations revealed the structure observed experimentally to be the most stable isomer and its energy being lower by 18.0441 kcal/mol than the less stable one. Density functional theory calculations were also carried out to analyze the natural charges, reactivity descriptors, and different intramolecular charge transfer interactions. The in vitro anticancer activity of the compound was evaluated by MTT assays against human colorectal cancer cells, HT-29 and SW620. The results showed that the compound has potential anticancer activity against these cells lines.

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.

Synthesis, Characterization, and In Vitro Cytotoxicity of Platinum(II) Complexes Bearing Chiral Tetradentate Salicylaldimine Ligands

A series of platinum(II) complexes with chiral Schiff base ligands derived from various salicylaldehydes with (R,R′)- and (S,S′)-cyclohexanediamine were synthesized and characterized by ESI-MS, IR, and NMR. Obtained spectra with typical signals were in agreement with suggested molecular formulae of the complexes. Their photophysical properties were studied by UV-visible and emission spectroscopies. The UV-Vis showed the typical band with low energy at visible range 400–500 nm for MLCT, and this band can emit the luminescent band with emission maximum wavelengths at 529–595 nm. The in vitro cytotoxicity of obtained platinum(II) complexes was screened for KB and MCF-7 human cancer cell lines. The results showed that (S)-enantiomers were more active than (R)-enantiomers and the different positions of methoxy group in salicyl ring gave different cytotoxicities.

Transition Metal Complexes of (E)‐2((2‐hydroxybenzylidene) amino‐3‐mercaptopropanoic acid: XRD, Anticancer, Molecular modeling and Molecular Docking Studies

The anticancer studies of a Schiff base; (E)‐2((2‐hydroxybenzylidene)amino‐3‐mercaptopropanoic acid (H2L) (obtained from 2‐hydroxybenzaldehyde and L‐cysteine) and its transition metal complexes have been reported. The evaluation of the growth inhibitory action was studied for the compounds against human colon carcinoma (HCT‐116), human hepatocellular liver carcinoma (HEPG‐2), normal melanocytes (HFB‐4) and human breast carcinoma (MCF‐7) cell lines. The obtained results revealed that the Schiff base and its chelates are active against human hepatocellular liver carcinoma (HEPG‐2) cell lines. The powder X‐ray diffraction analysis for the compounds was carried out through Phillips X′Pert High score software. The density functional theory computation for ligand and Co(II), Ni(II) and Cu(II) metal complexes were made to understand the mode of bonding by GAUSSIAN 03 rev. A.01 programme. The quantitative structure‐activity relationship investigation was performed by using HyperChem Professional 8.0.3 software to understand the biological potency of the ligands. Moreover, a docking analysis using iGEMDOCKv2.1 software was carried out against the kinase enzyme PDB ID:1fvv.