The effects of mitochondria-targeted antioxidants
on human cervical cancer cells in culture

G.S. Shagieva, E.N. Popova, L.V. Domnina, O.Ju. Pletjushkina, V.B. Dugina, V.P. Skulachev
A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University

The disruption of cytoskeleton and intercellular adhesions is an important component of the acquisition of invasive properties in epithelial malignancies. Elevation of the reactive oxygen species (ROS) level plays an important role in the tumor development. It was proposed that changes of ROS level in various cell compartments can differentially affect probability of neoplastic transformation and tumorigenesis. We have studied the effects of new mitochondria-targeted antioxidant SkQ1 [10-(6'-plastoquinonyl) decyltriphenylphosphonium] and its counterparts on tumor cells in culture.
To study SkQ1-dependent reorganization of actin cytoskeleton and adhesion junctions in the SiHa, C33A and HaCaT cells we used immunofluorescent microscopy and Western blot analysis. It was shown that incubation of the SiHa and C33A cells with SkQ1 (40 nM, 4 days) leads to more organized actin cytoskeleton: the microfilament bundles at the cell periphery and at cell-cell contacts were well pronounced. Immunostaining of E-cadherin revealed a formation of prolonged E-cadherin-positive contacts. Morphology of these cells and their islets became almost indistinguishable from normal keratinocytes. Treatment with SkQ1 (40 nM, 7 days) increased the total amount of E-cadherin and ?-catenin in the SiHa and C33A cells. Both proteins play a causal role in the establishment and maintenance of the differentiated epithelial phenotype. Also we have found that SkQ1 inhibited the SiHa cells proliferation.
The morphology of nontransformed keratinocytes HaCaT was not significantly affected by SkQ1. Phenotype reversion (normal epithelial-like morphology restoration) was observed also with other antioxidants N-acetyl-L-cysteine (NAC, 1-5 mM) and Trolox (100 μM).
We suppose that the SkQ1-induced cytoskeleton changes and proliferation inhibition are connected with the ability of SkQ1 to affect differentiation state of neoplastic epithelial cells and, as a result, to modulate pathways whose activity, on one hand, is dependent on expression of some differentiation markers and, on the other hand, can regulate cell cycle progression.

Homo Sapiens Liberatus Workshop, Moscow State University, May 2010