Jasmonic Acid Induces Endoplasmic Reticulum Stress with Different Outcome in Cultured Normal and Tumor Epidermal Cells.

Plant hormones produce cytotoxic effect on human cells and can trigger the processes unrelated to cell death, e.g., biosynthetic system stress. The goal of this study was to investigate activation of the endoplasmic reticulum (ER) stress by jasmonic acid (JA) and to distinguish between the responses of cultured immortalized non-tumorigenic HaCaT cells and epidermoid carcinoma A431 cells to this plant hormone. JA was used in the concentration of 2 mM, as it suppressed cell proliferation in both cell lines. We analyzed expression of genes associated with the activation of ER stress (GRP78, ATF4, CHOP), the structure of the ER and Golgi complex, and synthetic processes in the HaCaT and A431 cell lines. JA induced expression of genes responsible for the activation of ER stress and caused hypertrophic changes in the Golgi complex in both cell lines. However, the patterns of gene expression in the HaCaT and A431 cells were different, and higher levels of involucrin synthesis were observed in A431 but not in HaCaT cells, suggesting that JA activated differentiation of the tumor A431 cells only. Therefore, JA induced ER stress in both cell lines, but the consequences of ER stress were different for the epidermal immortalized non-tumorigenic and tumor cells.

[EFFECTS OF DIFFERENT CLASSES OF PLANT HORMONES ON MAMMALIAN CELLS].

Plant hormones are signal molecules of different chemical structure, secreted by plant cells and acting at low concentrations as regulators of plant growth and differentiation. Certain plant hormones are similar to animal hormones or can be produced by animal cells. A number of studies show that the effect of biologically active components of plant origin including plant/phytohormones is much wider than was previously thought, but so far there are no objective criteria for assessing the influence of phytohormones on the physiological state of animal cells. Presented in the survey data show that plant hormones, which have different effects on plant growth and development (jasmonic, abscisic and gibberellic acids), are not neutral to the cells of animal origin, and animal cells response to them may be either positive or negative.

Specific organization of Golgi apparatus in plant cells.

Microtubules, actin filaments, and Golgi apparatus are connected both directly and indirectly, but it is manifested differently depending on the cell organization and specialization, and these connections are considered in many original studies and reviews. In this review we would like to discuss what underlies differences in the structural organization of the Golgi apparatus in animal and plant cells: specific features of the microtubule cytoskeleton organization, the use of different cytoskeleton components for Golgi apparatus movement and maintenance of its integrity, or specific features of synthetic and secretory processes. We suppose that a dispersed state of the Golgi apparatus in higher plant cells cannot be explained only by specific features of the microtubule system organization and by the absence of centrosome as an active center of their organization because the Golgi apparatus is organized similarly in the cells of other organisms that possess the centrosome and centrosomal microtubules. One of the key factors determining the Golgi apparatus state in plant cells is the functional uniformity or functional specialization of stacks. The functional specialization does not suggest the joining of the stacks to form a ribbon; therefore, the disperse state of the Golgi apparatus needs to be supported, but it also can exist "by default". We believe that the dispersed state of the Golgi apparatus in plants is supported, on one hand, by dynamic connections of the Golgi apparatus stacks with the actin filament system and, on the other hand, with the endoplasmic reticulum exit sites distributed throughout the endoplasmic reticulum.

Mitochondrial Pathway of α-Tocopheryl Succinate-Induced Apoptosis in Human Epidermoid Carcinoma A431 Cells.

Vitamin E derivatives are known to act as agents exhibiting cytotoxity against tumor cells. The effect of vitamin E succinate on human epidermoid carcinoma cell line A431 was investigated in this study using live imaging, immunocytochemistry, and transmission electron microscopy. α-Tocopheryl succinate-induced apoptotic cell death in A431 cells was shown to be both dose- and time-dependent. The hyperproduction of reactive oxygen species, changes in size, shape and ultrastructural characteristics of mitochondria followed by the release of cytochromecfrom mitochondria to cytosol were observed. These results suggest that α-tocopheryl succinate induces apoptosis that occurs via the mitochondrial pathway. Mitochondria are shown to be crucial targets in α-tocopheryl succinate-induced caspase-dependent cell death in human carcinoma A431 cells.