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

Abstract

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.

Keywords: ROS; apoptosis; cytochromec; mitochondrial pathway; α-tocopheryl succinate.

Fig. 1

Apoptosis in human epidermoid carcinoma A431cells: a – on hematoxilin and eosin-stained slides, b – phase contrast, c – immunocytochemical revealing of caspase-3 with anti-caspase-3 antibodies in the cell shown in “b”.

Fig. 2

α-TS induces apoptosis in A431 cells in a dose- and time-depending manner.

Fig. 3

Mitochondria in A431 cells stained with MitoTracker Orange: a – control; b – control with vehicle; c, d – 40 µM α-TS, 48 h.

Fig. 4

Immunocytochemical staining of A431 cells with anti-cytochrome c antibodies: a, b – contol; c–f – 40 µM α-TS, 48 h.

Fig. 5

Ultrastructure of mitochondria in A431 cells: 
a – control; b – control with vehicle; c–e – 40 µM α-TS, 48 h.

Fig. 6

Live-imaging of A431 cells stained with DCFH-DA:a, с – control; b, d – 40 μM α-TS.

Fig. 7

Live-imaging of A431 cells stained with DCFH-DA: percentage of peroxide-positive cells in the control and after the incubation with 40 µM α-TS.