Using Fluorescent Post‐Labeling To Probe the Subcellular Localization of DNA‐Targeted Platinum Anticancer Agents

Abstract

Green around the cells: A post‐labeling method was developed to image a DNA‐targeted platinum drug in cancer cells by confocal fluorescence microscopy. This was done using ligation chemistry between an azide‐functionalized platinum‐acridine anticancer drug and an alkyne‐modified dye, Alexa Fluor 488 (green star, see figure). The platinum‐acridine agent was shown to accumulate in the nucleoli of cancer cells (NCI‐H460).

Redesigning the DNA‐Targeted Chromophore in Platinum–Acridine Anticancer Agents: A Structure–Activity Relationship Study

“…(A post-labeling strategy has recently been devised that facilitates the detection of adducts in the nuclear DNA and subnuclear structures in fixed cells. [8] ) By contrast, the blue fluorescence of benz[ c ]acridine in P1 – B1 , which is relatively weak as a result of self-aggregation, is slightly enhanced in the presence of calf thymus DNA (see the Supporting Information). …”

“…[7] Fluorescent post-labeling in whole lung cancer cells recently revealed high levels of DNA adducts in all phases of the cell cycle, both in the loosely packaged and the condensed chromatin. [8] The cumulative effects of this damage result in cell cycle arrest in late G1/early S phase and efficiently trigger apoptosis in NSCLC models representing a diverse range of genetic backgrounds. [9] Hybrids derived from the general structure in Figure 1 effectively kill cancer cells at low-nanomolar concentrations, which places them among the most cytotoxic platinum-containing anticancer agents described in the literature to date.…”

Chromatin Regulates Genome Targeting with Cisplatin

“…[1,6] Previous efforts towards the synthesis of clickable cisplatin derivatives suitable for cell imaging led to the development of an iminoacridine-Pt complex and af lexible alkyl-azide-containing derivative. [7] With this in mind, we synthesized the cyclic azidoplatinum-containing derivative we named 2-aminomethylpyridine (dichloro) Pt II azide (APPA, Figure 1A and Supporting Information). [8] Thed esign of APPAw as inspired from the structures of cisplatin and picoplatin ( Figure 1A), taking advantage of the aromatic methyl substituent to form arigid five-membered ring with Pt.…”

Preparation and Properties of Clickable Amino Analogues of the Duocarmycins: Factors That Affect the Efficiency of Their Fluorescent Labelling of DNA

“…[26] The precedents described above for fluorescent click labelling of DNA in cells employed either Triton X-100 [11,12] or saponin [13] permeabilisation.…”

“…[10] This could be used to establish the cellular or tissue localisation of aminoCBI adducts and their distribution relative to regions of hypoxia. Some precedents exist for the fluorescent labelling of DNA using clickable compounds in cells: the use of 5-ethynyl-2-deoxyuridine (EdU) to detect DNA synthesis, where the newly incorporated alkyne tag sits within the major groove; [11] a platinum acridine anticancer agent bearing an azide tag which demonstrated mainly nuclear fluorescence after click reaction with a fluorophore alkyne; [12] and, most closely related to the current work, three phenolic CBI alkynes, where subcellular fluorescence distribution was related to the presence or absence of a minor groove-binding side chain. [13] Here we investigate the synthesis and properties of clickable nitro-and aminoCBIs based on 7 and 8, [14] which differ from 5 and 6 only in the choice of the basic side chain substituent (morpholine in place of dimethylamine).…”