Enoxacin with UVA Irradiation Induces Apoptosis in the AsPC1 Human Pancreatic Cancer Cell Line Through ROS Generation

Topoisomerase II inhibitors design: Early studies and new perspectives

The DNA topoisomerase enzymes are widely distributed throughout all spheres of life and are necessary for cell function. Numerous antibacterial and cancer chemotherapeutic drugs target the various topoisomerase enzymes because of their roles in maintaining DNA topology during DNA replication and transcription. Agents derived from natural products, like anthracyclines, epipodophyllotoxins and quinolones, have been widely used to treat a variety of cancers. A very active field of fundamental and clinical research is the selective targeting of topoisomerase II enzymes for cancer treatment. This thematic review summarizes the recent advances in the anticancer activity of the most potent topoisomerase II inhibitors (anthracyclines, epipodophyllotoxins and fluoroquinolones) their modes of action, and structure-activity relationships (SARs) organized chronologically in the last ten years from 2013 to 2023. The review also highlights the mechanism of action and SARs of promising new topoisomerase II inhibitors.

Quinolones as a Potential Drug in Genitourinary Cancer Treatment-A Literature Review

Quinolones, broad-spectrum antibiotics, are frequently prescribed by urologists for many urological disorders. The mechanism of their bactericidal activity is based on the inhibition of topoisomerase II or IV complex with DNA, which consequently leads to cell death. It has been observed that these antibiotics also act against the analogous enzymes present in eukaryotic cells. Due to their higher accumulation in urine and prostate tissue than in serum, these drugs seem to be ideal candidates for application in genitourinary cancer treatment. In this study, an extensive literature review has been performed to collect information about concentrations achievable in urine and prostate tissue together with information about anticancer properties of 15 quinolones. Special attention was paid to the application of cytotoxic properties of quinolones for bladder and prostate cancer cell lines. Data available in the literature showed promising properties of quinolones, especially in the case of urinary bladder cancer treatment. In the case of prostate cancer, due to low concentrations of quinolones achievable in prostate tissue, combination therapy with other chemotherapeutics or another method of drug administration is necessary.

The New Face of a Well-Known Antibiotic: A Review of the Anticancer Activity of Enoxacin and Its Derivatives

Simple Summary

Enoxacin is a second-generation quinolone with promising anticancer activity. In contrast to other members of the quinolone group, it exhibits an extraordinary cytotoxic mechanism of action. Enoxacin enhances RNA interference and promotes microRNA processing, as well as the production of free radicals. Interestingly, apart from its proapoptotic, cell cycle arresting and cytostatic effects, enoxacin manifests a limitation of cancer invasiveness. The underlying mechanisms are the competitive inhibition of vacuolar H⁺-ATPase subunits and c-Jun N-terminal kinase signaling pathway suppression. The newly synthesized enoxacin derivatives have shown a magnified cytotoxic effect with an emphasis on prooxidative, proapoptotic and microRNA interference actions. The mentioned mechanisms seem to contribute to a safer, more selective and more effective anticancer therapy.

Abstract

Enoxacin as a second-generation synthetic quinolone is known for its antibacterial action; however, in recent years there have been studies focusing on its anticancer potential. Interestingly, it turns out that compared to other fluoroquinolones, enoxacin exhibits uncommon cytotoxic properties. Besides its influence on apoptosis, the cell cycle and cell growth, it exhibits a regulatory action on microRNA biogenesis. It was revealed that the molecular targets of the enoxacin-mediated inhibition of osteoclastogenesis are vacuolar H⁺-ATPase subunits and the c-Jun N-terminal kinase signaling pathway, causing a decrease in cell invasiveness. Interestingly, the prooxidative nature of the subjected fluoroquinolone enhanced the cytotoxic effect. Crucial for the anticancer activity were the carboxyl group at the third carbon atom, fluorine at the seventh carbon atom and nitrogen at the eighth position of naphyridine. Modifications of the parent drug improved the induction of oxidative stress, cell cycle arrest and the dysregulation of microRNA. The inhibition of V-ATPase–microfilament binding was also observed. Enoxacin strongly affected various cancer but not normal cells, excluding keratinocytes, which suffered from phototoxicity. It seems to be an underestimated anticancer drug with pleiotropic action. Furthermore, its usage as a safe antibiotic with well-known pharmacokinetics and selectivity will enhance the development of anticancer treatment strategies. This review covers articles published within the years 2000–2021, with a strong focus on the recent years (2016–2021). However, some canonical papers published in twentieth century are also mentioned.

Biological Effects of Quinolones: A Family of Broad-Spectrum Antimicrobial Agents

Broad antibacterial spectrum, high oral bioavailability and excellent tissue penetration combined with safety and few, yet rare, unwanted effects, have made the quinolones class of antimicrobials one of the most used in inpatients and outpatients. Initially discovered during the search for improved chloroquine-derivative molecules with increased anti-malarial activity, today the quinolones, intended as antimicrobials, comprehend four generations that progressively have been extending antimicrobial spectrum and clinical use. The quinolone class of antimicrobials exerts its antimicrobial actions through inhibiting DNA gyrase and Topoisomerase IV that in turn inhibits synthesis of DNA and RNA. Good distribution through different tissues and organs to treat Gram-positive and Gram-negative bacteria have made quinolones a good choice to treat disease in both humans and animals. The extensive use of quinolones, in both human health and in the veterinary field, has induced a rise of resistance and menace with leaving the quinolones family ineffective to treat infections. This review revises the evolution of quinolones structures, biological activity, and the clinical importance of this evolving family. Next, updated information regarding the mechanism of antimicrobial activity is revised. The veterinary use of quinolones in animal productions is also considered for its environmental role in spreading resistance. Finally, considerations for the use of quinolones in human and veterinary medicine are discussed.