Comparative Studies of Steroidogenesis Inhibitors (Econazole, Ketoconazole) on Human Breast Cancer MCF-7 Cell Proliferation by Growth Experiments, Thymidine Incorporation and Flow Cytometric DNA Analysis

Sertaconazole induced toxicity in HeLa cells through mitotic arrest and inhibition of microtubule assembly

Econazole, miconazole, and sertaconazole, the structurally related azoles with imidazole moiety, were evaluated for their cytotoxicity and their ability to bind to mammalian tubulin. Our results indicated that sertaconazole and econazole bound to goat brain tubulin with a dissociation constant of 9 and 19 μM respectively, while miconazole did not bind to goat brain tubulin. Econazole, miconazole, and sertaconazole inhibited the proliferation of HeLa cells with an IC₅₀ of 28, 98, and 38 μM respectively with sertaconazole alone inducing a mitotic block in the treated cells. Since sertaconazole bound to goat brain tubulin with higher affinity and blocked the cells at mitosis, we hypothesized that its cytotoxic mechanism might involve inhibition of tubulin and econazole which did not block the cells at mitosis may have additional targets than tubulin. Sertaconazole inhibited the polymerization of tubulin in HeLa cells and the in vitro assembled goat brain tubulin. Competitive tubulin-binding assay using colchicine and computational simulation studies showed that sertaconazole bound closer to the colchicine site and induced the tubulin dimer to adopt a "bent" conformation which is incompetent for the polymerization. Results from RT-PCR analysis of the A549 cells treated with sertaconazole indicated activation of apoptosis. Sertaconazole significantly inhibited the migration of HeLa cells and showed synergistic antiproliferative potential with vinblastine. Collectively, the results suggest that sertaconazole which is already in clinical practice could be useful as a topical chemotherapy agent for the treatment of skin cancers in combination with other systemic anticancer agents.

Econazole Induces p53-Dependent Apoptosis and Decreases Metastasis Ability in Gastric Cancer Cells

Econazole, a potent broad-spectrum antifungal agent and a Ca²⁺ channel antagonist, induces cytotoxicity in leukemia cells and is used for the treatment of skin infections. However, little is known about its cytotoxic effects on solid tumor cells. Here, we investigated the molecular mechanism underlying econazole-induced toxicity in vitro and evaluated its regulatory effect on the metastasis of gastric cancer cells. Using the gastric cancer cell lines AGS and SNU1 expressing wild-type p53 we demonstrated that econazole could significantly reduce cell viability and colony-forming (tumorigenesis) ability. Econazole induced G0/G1 phase arrest, promoted apoptosis, and effectively blocked proliferation- and survival-related signal transduction pathways in gastric cancer cells. In addition, econazole inhibited the secretion of matrix metalloproteinase- 2 (MMP-2) and MMP-9, which degrade the extracellular matrix and basement membrane. Econazole also effectively inhibited the metastasis of gastric cancer cells, as confirmed from cell invasion and wound healing assays. The protein level of p53 was significantly elevated after econazole treatment of AGS and SNU1 cells. However, apoptosis was blocked in econazole-treated cells exposed to a p53-specific small-interfering RNA to eliminate p53 expression. These results provide evidence that econazole could be repurposed to induce gastric cancer cell death and inhibit cancer invasion.

Econazole nitrate inhibits PI3K activity and promotes apoptosis in lung cancer cells

The phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathway plays a pivotal role in many cellular processes, including the proliferation, survival and differentiation of lung cancer cells. Thus, PI3K is a promising therapeutic target for lung cancer treatment. In this study, we applied free and open-source protein-ligand docking software, screened 3167 FDA-approved small molecules, and identified putative PI3Kα inhibitors. Among them, econazole nitrate, an antifungal agent, exhibited the highest activity in decreasing cell viability in pathological types of NSCLC cell lines, including H661 (large cell lung cancer) and A549 (adenocarcinoma). Econazole decreased the protein levels of p-AKT and Bcl-2, but had no effect on the phosphorylation level of ERK. It inhibited cell growth and promote apoptosis in a dose-dependent manner. Furthermore, the combination of econazole and cisplatin exhibited additive and synergistic effects in the H661 and A549 lung cancer cell lines, respectively. Finally, we demonstrated that econazole significantly suppressed A549 tumor growth in nude mice. Our findings suggest that econazole is a new PI3K inhibitor and a potential drug that can be used in lung cancer treatment alone or in combination with cisplatin.

Mitochondrial regulation by c-Myc and hypoxia-inducible factor-1 alpha controls sensitivity to econazole

Econazole is an azole antifungal with anticancer activity that blocks Ca(2+) influx and stimulates endoplasmic reticulum (ER) Ca(2+) release through the generation of mitochondrial reactive oxygen species (ROS), resulting in sustained depletion of ER Ca(2+) stores, protein synthesis inhibition, and cell death. c-Myc, a commonly activated oncogene, also promotes apoptosis in response to growth factor withdrawal and a variety of chemotherapeutic agents. We have investigated the role of c-myc in regulating sensitivity to econazole. Here, we show that c-myc-negative cells are profoundly resistant to econazole. c-Myc-negative rat fibroblasts failed to generate mitochondrial ROS in response to econazole and consequently failed to deplete the ER of Ca(2+). HL60 cells knocked down for c-myc expression also displayed decreased ROS generation and decreased econazole sensitivity. Addition of H(2)O(2) restored sensitivity to econazole in both c-myc-negative rat fibroblasts and c-myc knocked-down HL60 cells, supporting a role for ROS in cell death induction. c-Myc-negative cells and HL60 cells knocked down for c-myc have reduced mitochondrial content compared with c-myc-positive cells. The hypoxia sensor, hypoxia-inducible factor-1alpha (HIF-1alpha), interacts antagonistically with c-myc and also regulates mitochondrial biogenesis. Knockdown of HIF-1alpha in c-myc-negative cells increased mitochondrial content restored ROS generation in response to econazole and increased sensitivity to the drug. Taken together, these results show that c-myc and HIF-1alpha regulate sensitivity to econazole by modulating the ability of the drug to generate mitochondrial ROS.

A Parenteral Econazole Formulation Using a Novel Micelle-to-Liposome Transfer Method: In Vitro Characterization and Tumor Growth Delay in a Breast Cancer Xenograft Model

PURPOSE

The aim of the study is to develop modified, branched versions of the Noyes-Whitney and the Weibull equations, including explicitly the solubility/dose parameter, for the analysis of dissolution data, which reach the plateau either at infinite or finite time.

METHODS

The modified Weibull function is applied to the analysis of experimental and literature dissolution data. To demonstrate the usefulness of the mathematical models, two model drugs are used: one highly soluble, metoprolol, and one relatively insoluble, ibuprofen.

RESULTS

The models were fitted successfully to the data performing better compared with their classic versions. The advantages of the use of the models presented are several. They fit better to a large range of datasets, especially for fast dissolution curves that reach complete dissolution at a finite time. Also, the modified Weibull presented can be derived from differential equations, and it has a physical meaning as opposed to the purely empirical character of the original Weibull equation. The exponent of the Weibull equation can be attributed to the heterogeneity of the process and can be explained by fractal kinetics concepts. Also, the solubility/dose ratio is present explicitly as a parameter and allows to obtain estimates of the solubility even when the dissolution data do not reach the solubility level.

CONCLUSION

The use of the developed branched equations gives better fittings and specific physical meaning to the dissolution parameters. Also, the findings underline the fact that even in the simplest, first-order case, the speed of the dissolution process depends on the dose, a fact of great importance in biopharmaceutic classification for regulatory purposes.

Endocrine and intracrine sources of androgens in women: inhibition of breast cancer and other roles of androgens and their precursor dehydroepiandrosterone

Serum androgens as well as their precursors and metabolites decrease from the age of 30-40 yr in women, thus suggesting that a more physiological hormone replacement therapy at menopause should contain an androgenic compound. It is important to consider, however, that most of the androgens in women, especially after menopause, are synthesized in peripheral intracrine tissues from the inactive precursors dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S) of adrenal origin. Much progress in this new area of endocrine physiology called intracrinology has followed the cloning and characterization of most of the enzymes responsible for the transformation of DHEA and DHEA-S into androgens and estrogens in peripheral target tissues, where the locally produced sex steroids are exerting their action in the same cells in which their synthesis takes place without significant diffusion into the circulation, thus seriously limiting the interpretation of serum levels of active sex steroids. The sex steroids made in peripheral tissues are then inactivated locally into more water-soluble compounds that diffuse into the general circulation where they can be measured. In a series of animal models, androgens and DHEA have been found to inhibit breast cancer development and growth and to stimulate bone formation. In clinical studies, DHEA has been found to increase bone mineral density and to stimulate vaginal maturation without affecting the endometrium, while improving well-being and libido with no significant side effects. The advantage of DHEA over other androgenic compounds is that DHEA, at physiological doses, is converted into androgens and/or estrogens only in the specific intracrine target tissues that possess the appropriate physiological enzymatic machinery, thus limiting the action of the sex steroids to those tissues possessing the tissue-specific profile of expression of the genes responsible for their formation, while leaving the other tissues unaffected and thus minimizing the potential side effects observed with androgens or estrogens administered systemically.

Melatonin decreases cell proliferation and transformation in a melatonin receptor-dependent manner

There are conflicting claims for the role of melatonin in oncogenesis. In addition, the mechanism(s) underlying melatonin's effects in oncogenic processes is (are) unknown. In this study, the effects of melatonin exposure on cell proliferation and transformation were assessed in NIH3T3 cells transfected with either the human mt(1) (NIH-mt1) or MT(2) (NIH-MT2) melatonin receptors. The effects of melatonin exposure on proliferation was assessed by direct cell counts and [(3)H]thymidine uptake assays. The effect of chronic melatonin pretreatment on transformation was assessed by focus assays. In both NIH-mt1 and NIH-MT2 cells, melatonin pretreatment decreased cell proliferation and transformation. Control (NIH-neo) cells did not show this effect. However, as revealed by the [(3)H]thymidine uptake assays, an increase in DNA synthesis occurred in NIH-mt1 cells, whereas no increase occurred in the NIH-MT2 or NIH-neo cells. Upon examination of melatonin receptors, a decrease in the function of both mt(1) and MT(2) receptors occurred. These data suggest that perhaps an attenuation of receptor-mediated processes are involved in the anti-proliferative and anti-transformation capabilities of melatonin in NIH3T3 cells. In addition, based on the [(3)H]thymidine assays, receptor mediated signal transduction mechanisms may slow the growth of cells via actions on the cell cycle. The results from this study shed new insight on the putative mechanisms underlying melatonin's effects on cell proliferation and transformation and lends support for a protective role of melatonin in oncogenesis.