7-ketocholesterol-induced caspase-mediated apoptosis in Saccharomyces cerevisiae

Antifungal and Anti-Biofilm Effects of Caffeic Acid Phenethyl Ester on Different Candida Species

This study investigated the effect of CAPE on planktonic growth, biofilm-forming abilities, mature biofilms, and cell death of C. albicans, C. tropicalis, C. glabrata, and C. parapsilosis strains. Our results showed a strain- and dose-dependent effect of CAPE on Candida, and the MIC values were between 12.5 and 100 µg/mL. Similarly, the MBIC values of CAPE ranging between 50 and 100 µg/mL highlighted the inhibition of the biofilm-forming abilities in a dose-dependent manner, as well. However, CAPE showed a weak to moderate biofilm eradication ability (19-49%) on different Candida strains mature biofilms. Both caspase-dependent and caspase-independent apoptosis after CAPE treatment were observed in certain tested Candida strains. Our study has displayed typical apoptotic hallmarks of CAPE-induced chromatin margination, nuclear blebs, nuclear condensation, plasma membrane detachment, enlarged lysosomes, cytoplasm fragmentation, cell wall distortion, whole-cell shrinkage, and necrosis. In conclusion, CAPE has a concentration and strain-dependent inhibitory activity on viability, biofilm formation ability, and cell death response in the different Candida species.

A Systematic Survey of Characteristic Features of Yeast Cell Death Triggered by External Factors

Cell death in response to distinct stimuli can manifest different morphological traits. It also depends on various cell death signaling pathways, extensively characterized in higher eukaryotes but less so in microorganisms. The study of cell death in yeast, and specifically Saccharomyces cerevisiae, can potentially be productive for understanding cell death, since numerous killing stimuli have been characterized for this organism. Here, we systematized the literature on external treatments that kill yeast, and which contains at least minimal data on cell death mechanisms. Data from 707 papers from the 7000 obtained using keyword searches were used to create a reference table for filtering types of cell death according to commonly assayed parameters. This table provides a resource for orientation within the literature; however, it also highlights that the common view of similarity between non-necrotic death in yeast and apoptosis in mammals has not provided sufficient progress to create a clear classification of cell death types. Differences in experimental setups also prevent direct comparison between different stimuli. Thus, side-by-side comparisons of various cell death-inducing stimuli under comparable conditions using existing and novel markers that can differentiate between types of cell death seem like a promising direction for future studies.

Novel 1,3,4-oxadiazole Targets STAT3 Signaling to Induce Antitumor Effect in Lung Cancer

Lung cancer is the leading type of malignancy in terms of occurrence and mortality in the global context. STAT3 is an oncogenic transcription factor that is persistently activated in many types of human malignancies, including lung cancer. In the present report, new oxadiazole conjugated indazoles were synthesized and examined for their anticancer potential in a panel of cancer cell lines. Among the new compounds, 2-(3-(6-chloro-5-methylpyridin-3-yl)phenyl)-5-(1-methyl-1H-indazol-3-yl)-1,3,4-oxadiazole (CHK9) showed consistently good cytotoxicity towards lung cancer cells with IC50 values ranging between 4.8-5.1 µM. The proapoptotic effect of CHK9 was further demonstrated by Annexin-FITC staining and TUNEL assay. In addition, the effect of CHK9 on the activation of STAT3 in lung cancer cells was examined. CHK9 reduced the phosphorylation of STAT3Y705 in a dose-dependent manner. CHK9 had no effect on the activation and expression of JAK2 and STAT5. It also reduced the STAT3-dependent luciferase reporter gene expression. CHK9 increased the expression of proapoptotic (p53 and Bax) proteins and decreased the expression of the antiapoptotic (Bcl-2, Bcl-xL, BID, and ICAM-1) proteins. CHK9 displayed a significant reduction in the number of tumor nodules in the in vivo lung cancer model with suppression of STAT3 activation in tumor tissues. CHK9 did not show substantial toxicity in the normal murine model. Overall, CHK9 inhibits the growth of lung cancer cells and tumors by interfering with the STAT3 signaling pathway.

Oxidative stress-mediated apoptotic cell death induced by camphor in sod1-deficient Schizosaccharomyces pombe

Camphor is one of the monoterpenes widely used in cosmetics, pharmaceutics and the food industry. In this study, we aimed to assess the oxidative, cytotoxic and apoptotic effects of camphor on the fission yeast (Schizosaccharomyces pombe), which is a promising unicellular model organism in mechanistic toxicology and cell biology. Since Sod1 is the main radical scavenger in the cell, we used sod1 mutants to understand whether camphor-induced ROS accumulation caused higher cytotoxicity and apoptosis. Camphor exposure (0-2000 mg L-1) caused significant cytotoxicity in yeast, particularly in sod1Δ cells. DCFDA (2,7-dichlorodihydrofluorescein diacetate) fluorescence and NBT (p-nitro-blue tetrazolium chloride) reduction increased (at least 2.5-3-fold in sod1Δ cells) in correlation with camphor concentrations (800-1200 mg L-1), showing higher ROS levels and oxidative stress. Moreover, cells, stained with acridine orange/ethidium bromide, showed an apoptotic morphology with nuclear fragmentation and condensation. DAPI (4',6-diamidino-2-phenylindole) staining was used to validate the apoptotic nuclear morphology. Dramatically increased mitochondrial impairment, which was higher in sod1Δ cells than in wild type cells, was shown by rhodamine 123 staining. In conclusion, camphor-induced excessive ROS production, which could not be prevented significantly in sod1 mutants, caused a dramatic increase in mortality rates due to intrinsic apoptosis revealed by mitochondrial impairment and apoptotic nuclear morphology. The potential effects of camphor on apoptotic cell death and the underlying mechanisms were clarified in the unicellular eukaryotic model, S. pombe.