Impaired Expression of Cytoplasmic Actins Leads to Chromosomal Instability of MDA-MB-231 Basal-Like Mammary Gland Cancer Cell Line.

Vera Dugina,Igor Kireev,Olga Sokova,Svetlana Lavrushkina,Pavel Kopnin,Mariya Novikova,Galina Shagieva

doi:10.3390/molecules26082151

Vera Dugina, Igor Kireev + Show 5 more

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https://doi.org/10.3390/molecules26082151

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Abstract

We have shown previously that two cytoplasmic actin isoforms play different roles in neoplastic cell transformation. Namely, β-cytoplasmic actin acts as a tumor suppressor, whereas γ-cytoplasmic actin enhances malignant features of tumor cells. The distinct participation of each cytoplasmic actin in the cell cycle driving was also observed. The goal of this study was to describe the diverse roles of cytoplasmic actins in the progression of chromosomal instability of MDA-MB-231 basal-like human carcinoma cell line. We performed traditional methods of chromosome visualization, as well as 3D-IF microscopy and western blotting for CENP-A detection/quantification, to investigate chromosome morphology. Downregulation of cytoplasmic actin isoforms alters the phenotype and karyotype of MDA-MB-231 breast cancer cells. Moreover, β-actin depletion leads to the progression of chromosomal instability with endoreduplication and aneuploidy increase. On the contrary, γ-actin downregulation results not only in reduced percentage of mitotic carcinoma cells, but leads to chromosome stability, reduced polyploidy, and aneuploidy.

Highlights

We have shown clear segregation of cytoplasmic actin isoforms in anaphase-telophase of normal mitotic epithelial cells [3,4], and that depletion of each cytoplasmic actin led to impaired proliferation/cell cycle of carcinoma cells [5,6]
It is important to mention that a shift of the amount of one isoform is compensated by reciprocal change of another isoform: β-actin strong depletion was accompanied by γ-actin upregulation; γ-actin downregulation resulted in an increase of β-actin expression in MDA-MB-231 and other cells [5]
We identified the differences of chromosome number and modal class in MDA-MB-231 cells after downregulation of cytoplasmic actin isoforms compared with control cells

Summary

Introduction

Actin and actin-binding proteins regulate the functional state of chromatin and gene expression, and, apparently, they play an important role in the organization of the genome [1]. Previous studies have demonstrated important participation of actin and its regulatory proteins in cell division [2]. We have shown clear segregation of cytoplasmic actin isoforms in anaphase-telophase of normal mitotic epithelial cells [3,4], and that depletion of each cytoplasmic actin led to impaired proliferation/cell cycle of carcinoma cells [5,6]. The distinct roles of β- and γ-actins in the cell cycle were observed: only downregulation of β-actin induced a significant decrease in diploid cell population and accumulation of near-tetraploid cells, which was detected by flow cytometry. There was no effective inhibition of proliferation with a decrease in the expression of β-actin in MDA-MB-231 cells

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