Anti‐cancer effects of CQBTO, a chloroquine, and benzo(e)triazine oxide conjugate

Abstract

Aim Autophagy is a self‐protective process, and it confers cancer cells resistance against radio‐chemotherapeutics. To induce cancer cell death, a series of compounds of 3‐((4‐((7‐chloroquinolin‐4‐yl)amino)butyl)amino)‐7‐substituted benzo[e][1,2,4]triazine 1‐oxide or CQBTO containing two critical chemical groups were designed and synthesized. One compound, benzo[e][1,2,4]triazine 1‐oxide, yielded free radicals to trigger autophagy, and the other one, chloroquine (CQ), was an inhibitor of autophagy. We hypothesized that the compounds could kill cancer cells effectively by inducing incomplete autophagy. Methods In vitro cultured non‐small cell lung carcinoma cells and primary lung tumors in mice in vivo were used to test the lethal effects of CQBTO on cancer cells and toxicity to normal tissues. Cell viability was examined using the CCK8 assay. Genomic instability was determined with the cytochalasin B‐blocked micronucleus assay. Cell cycle distribution was analyzed by propidium iodide staining and flow cytometry. Western blotting and immunofluorescence were used to detect the induction and localization of LC3, a biomarker for autophagy. Results Compared with CQ, three CQBTO compounds were lethal to lung cancer cells, and CQBTO‐3 was the most effective. The LD50 for CQBTO‐3 was 21 μΜ in A549 cells and 21.5 μΜ in Calu‐1 cells, which was lower than that of CQBTO‐2 or CQBTO‐1. Induction of LC3 foci and an increase in the LC3II/LC3I ratio demonstrated the induction of autophagy by CQBTO‐3 in A549 cells, whereas no obvious micronuclei or cell cycle arrest was observed. No detectable toxicity to normal mice was observed. CQBTO‐3 improved the quality of mouse life, reduced the number and size of existing tumors, and suppressed tumor formation. Conclusion CQBTO‐3 is a potential chemical compound for lung cancer treatment.

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“…All the immunofluorescence assays in this study were performed as previously described [45]. Cells cultured on slides were treated with the compounds and fixed with 4% paraformaldehyde for 10 min at room temperature, permeabilized for 20 min in ethanol at −20°C, washed with PBS for 30 min, and treated with 0.5% Triton for 10 min.…”

Chloroquine against malaria, cancers and viral diseases

“…On the other hand, the clearance and recycling of dysfunctional organelles and proteins provide energy for tumor cells. It maintains cellular homeostasis and confers resistance of cancer cells against chemotherapy and radiotherapy [42] .…”

Recent updates on 1,2,3‐, 1,2,4‐, and 1,3,5‐triazine hybrids (2017–present): The anticancer activity, structure–activity relationships, and mechanisms of action

“…[102] CQBTO-3 (50, LD 50 : 21.0 and 21.5 µM, cell counting kit-8/CCK-8 assay), a benzo[e][1,2,4]triazine-1-oxo-quinoline hybrid, displayed potential activity against A549 and Calu-1 cancer cell lines and induced autophagy. [103] In a mouse lung and SK-BR-3 cancer cell lines, and the SARs illustrated that methyl group at the C-2 position of pyrazole moiety enhanced the activity. [104] In the A549 against MGC-803, PC-3, and EC-109 cancer cell lines.…”

“…[ 102 ] CQBTO‐3 ( 50 , LD 50 : 21.0 and 21.5 µM, cell counting kit‐8/CCK‐8 assay), a benzo[e][1,2,4]triazine‐1‐oxo‐quinoline hybrid, displayed potential activity against A549 and Calu‐1 cancer cell lines and induced autophagy. [ 103 ] In a mouse lung cancer model, CQBTO‐3 could prolong the life of a mouse, and suppress tumor formation without detectable toxicity.…”