Repurposing of Anti-Malarial Drug Quinacrine for Cancer Treatment: A Review

Quinacrine (QC), a synthetic drug belonging to the 9-aminoacridine family, has been used extensively to treat malaria and multiple ailments over the past several decades. Following its discovery in the 1920s and extensive use for the treatment of malaria for nearly two decades, numerous studies have explored its antineoplastic potential in both preclinical and clinical settings. Multiple studies spanning over seven decades have examined a wide range of QC anticancer activities across various types of cancers, along with the underlying mechanisms. Many of these mechanisms, including activation of the p53 signaling cascade and simultaneous NF-κB signaling inhibition, have been reported in various studies, bringing QC to a unique polypharmacological category drug possessing the potential to treat a wide variety of diseases, including cancer. This article summarizes most of the research conducted over several decades to uncover new molecular mechanisms activated or inactivated and directly correlate with antineoplastic activity QC.

Protective effects of luteolin against oxidative stress and mitochondrial dysfunction in endothelial cells

BACKGROUND AND AIMS

Luteolin is a common flavonoid that is abundantly present in various edible plants, it is known to exhibit beneficial effects on cardiovascular system. However, the mechanisms which underlie the protective effects of luteolin on endothelial cell damage caused by oxidative stress remains unclear. The purpose of this study is to test the hypothesis which states that luteolin protects against H₂O₂-induced oxidative stress via modulating ROS-mediated P38 MAPK/NF-κB and calcium-evoked mitochondrial apoptotic signalling pathways.

METHODS AND RESULTS

Human umbilical vein endothelial cells (HUVECs) were pretreated with luteolin prior to being stimulated by 600 μM H₂O₂ for another 24 h. The expression of native and phosphorylated-P38, IκB, NF-κB, native eNOS, phosphorylated-eNOS, iNOS and several apoptosis-related proteins were analyzed by Western blot. In addition, intracellular calcium was determined by fura-2 AM and mitochondrial membrane potential was examined by using JC1. Using the data gathered, we found indications that H₂O₂ induced P38 MAPK/NF-κB activation. H₂O₂ downregulated the expression of eNOS and upregulated iNOS, which in turn contribute to an elevated NO generation and protein nitrosylation. However, pretreatment with luteolin markedly reversed all of these alterations dose-dependently. Additionally, an intracellular calcium rise and subsequent mitochondrial membrane potential collapse, P53 phosphorylation, reduced BcL-2/Bax ratio in the mitochondrial membrane, release cytochrome c from mitochondria, leading to the subsequent activation of caspase 3 activation by H₂O₂ were all markedly suppressed in the presence of luteolin.

CONCLUSION

Results from this study may provide the possible molecular mechanisms underlying cardiovascular protective effects of luteolin.

Beyond DNA binding - a review of the potential mechanisms mediating quinacrine's therapeutic activities in parasitic infections, inflammation, and cancers

This is an in-depth review of the history of quinacrine as well as its pharmacokinetic properties and established record of safety as an FDA-approved drug. The potential uses of quinacrine as an anti-cancer agent are discussed with particular attention to its actions on nuclear proteins, the arachidonic acid pathway, and multi-drug resistance, as well as its actions on signaling proteins in the cytoplasm. In particular, quinacrine's role on the NF-κB, p53, and AKT pathways are summarized.

Dihydrotestosterone protects human vascular endothelial cells from H(2)O(2)-induced apoptosis through inhibition of caspase-3, caspase-9 and p38 MAPK

Oxidative stress is proved to be harmful to the vascular endothelial cells which are important in preventing the formation and progression of atheromatous plaque. This study was designed to investigate the protective effect and potential mechanisms of dihydrotestosterone (DHT) against H(2)O(2)-induced apoptosis of human umbilical vein endothelial cells (ECV-304). ECV-304 cells were pretreated with different concentrations of DHT (0.01, 0.1 and 1 microM) for 2h, followed by exposure to 100 microM H(2)O(2) for 18h. 3-(4,5-dimethylthiazol-2yl-)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate cell viability. To detect apoptosis, the cells were assessed by morphologic examination and Annexin V-propidium iodide double staining with flow cytometry. Finally, the expression of caspase-3, caspase-9 and phospho p38 MAPK was assayed by Western blot to investigate the possible molecular mechanisms. We found that H(2)O(2) treatment for 18h significantly decrease the viability of ECV-304 cells characterized by a high percentage of apoptotic cells. DHT could antagonize the apoptosis inducing effect of H(2)O(2) in a dose-dependent manner. Consistently, DHT also significantly inhibit the expression of caspase-3, caspase-9 and phospho p38 MAPK induced by H(2)O(2). In summary, pretreatment with DHT can inhibit apoptosis of ECV-304 cells induced by H(2)O(2). The protective effect of DHT was associated with the inhibition of caspase-3, caspase-9 and phospho p38 MAPK expression.

Upregulation of NF-kappaB upon differentiation of mouse embryonic stem cells

NF-kappaB is a transcriptional regulator involved in many biological processes including proliferation, survival, and differentiation. Recently, we reported that expression and activity of NF-kappaB is comparatively low in undifferentiated human embryonic stem (ES) cells, but increases during differentiation. Here, we found a lower expression of NF-kappaB p65 protein in mouse ES cells when compared with mouse embryonic fibroblast cells. Protein levels of NF-kappaB p65 and relB were clearly enhanced during retinoic acid-induced differentiation. Furthermore, increased DNA binding activity of NF-kappaB in response to TNF-alpha, an agonist of NF-kappaB signaling, was seen in differentiated but not undifferentiated mouse ES cells. Taken together with our previous data in human ES cells, it is likely that NF-kappaB expression and activity of the NF-kappaB signaling pathway is comparatively low in undifferentiated ES cells, but increases during differentiation of ES cells in general.

Effect of dihydrotestosterone on mouse embryonic stem cells exposed to H2O2-induced oxidative stress

Oxidative stresses induced by reactive oxygen species (ROS) have been shown to be involved in several physiological and pathophysiological processes, such as cell proliferation and differentiation. Steroid hormones can protect cells against apoptosis or induce cell proliferation by several mechanisms. Among androgenic hormones, dihydrotestosterone (DHT) is generated by a 5alpha- reduction of testosterone. Unlike testosterone, DHT cannot be aromatized to estradiol, therefore DHT is considered a pure androgenic steroid. This study was conducted to examine the effect of DHT (10(-7) M) on H2O2 (10(-3) M) -induced injuries in mouse embryonic stem (ES) cells. H2O2 induced ROS generation and increased lipid peroxide formation and DNA fragmentation. These effects of H2O2 were inhibited by pretreatment with DHT. H2O2 also increased the phosphorylation of p38 MAPK, SAPK/JNK and nuclear factor kappa B (NF-kappaB), but DHT blocked these effects. Moreover, H2O2 decreased DNA synthesis and the levels of cell cycle regulatory proteins [cyclin D1, cyclin E, cyclin-dependent kinase (CDK) 2, and CDK 4]. These effects of H2O2 were inhibited by pretreatment with DHT. In conclusion, DHT may partially prevent H2O2-induced cell injury through inhibition of ROS and ROS-induced activation of p38 MAPK, SAPK/JNK and NF-kappaB in mouse ES cells.