Effects of All-Electron Basis Sets and the Scalar Relativistic Corrections in the Structure and Electronic Properties of Niobium Clusters

Influence of ring modifications on nucleolar stress caused by oxaliplatin-like compounds

Oxaliplatin, a platinum compound in broad clinical use, can induce cell death through a nucleolar stress pathway rather than the canonical DNA damage response studied for other Pt(II) compounds. Previous work has found that the oxaliplatin 1,2-diaminocyclohexane (DACH) ring but not the oxalate leaving group is important to the ability to induce nucleolar stress. Here we study the influence of DACH ring substituents at the 4-position on the ability of DACH-Pt(II) compounds to cause nucleolar stress. We determine that DACH-Pt(II) compounds with 4-position methyl, ethyl, or propyl substituents induce nucleolar stress, but DACH-Pt(II) compounds with 4-isopropyl substituents do not induce nucleolar stress. This effect is independent of whether the substituent is in the axial or equatorial position relatively to the trans diamines of the ligand. These results suggest that spatially sensitive interactions could be involved in the ability of platinum compounds to cause nucleolar stress.

Monofunctional platinum(II) compounds and nucleolar stress: is phenanthriplatin unique?

Platinum anticancer therapeutics are widely used in a variety of chemotherapy regimens. Recent work has revealed that the cytotoxicity of oxaliplatin and phenanthriplatin is through induction of ribosome biogenesis stress pathways, differentiating them from cisplatin and other compounds that mainly work through DNA damage response mechanisms. To probe the structure-activity relationships in phenanthriplatin's ability to cause nucleolar stress, a series of monofunctional platinum(II) compounds differing in ring number, size and orientation was tested by nucleophosmin (NPM1) relocalization assays using A549 cells. Phenanthriplatin was found to be unique among these compounds in inducing NPM1 relocalization. To decipher underlying reasons, computational predictions of steric bulk, platinum(II) compound surface length and hydrophobicity were performed for all compounds. Of the monofunctional platinum(II) compounds tested, phenanthriplatin has the highest calculated hydrophobicity and volume but does not exhibit the largest distance from platinum(II) to the surface. Thus, spatial orientation and/or hydrophobicity caused by the presence of a third aromatic ring may be significant factors in the ability of phenanthriplatin to cause nucleolar stress.