2Institute of Carcinogenesis, Blokhin National Medical Research Centre of Oncology, Public Health Ministry of Russian Federation, 115478 Moscow, Russia
* To whom correspondence should be addressed.
Received November 15, 2018; Revised February 12, 2019; Accepted February 13, 2019
Actin plays an important role in cellular adhesion, muscle and non-muscle contractility, migration, polarization, mitosis, and meiosis. Investigation of specific mechanisms underlying these processes is essential not only for fundamental research but also for clinical applications, since modulations of actin isoforms are directly or indirectly correlate with severe pathologies. In this review we summarize the isoform-specific functions of actin associated with adhesion structures, motility and division of normal and tumor cells; alterations of the expression and structural organization of actin isoforms in normal and tumor cells. Selective regulation of cytoplasmic β- or γ-actin expression determines functional diversity between isoforms: β-actin plays the predominant role in contraction and intercellular adhesion, and γ-actin is responsible for the cellular plasticity and motility. Similar data were obtained in different epithelial and mesenchymal neoplastic cell cultures, as well as in immunomorphological comparison of normal human tissues with tumor analogues. Reorganization of the actin cytoskeleton and cell–cell contacts is essential for proliferation control and acquisition of invasiveness in epithelial tumors.
KEY WORDS: cytoplasmic actin isoforms, β-actin, γ-actin, neoplastic transformation, tumor cells, cytoskeleton