ИСТИНА

Myosin IC isoform A was shown to be tissue- and tumor-specificfor prostate cancer cells. We showed both cytoplasmic andnuclear localization of this isoform and suggested its crucial rolein the formation of tumor phenotype through changes in geneexpression and balance of cell proliferation and cell death. Toanalyze the role of myosin 1C in malignization of prostate cancercells, we used PC3 cell line with initially high expression of myo-sin 1C isoform A for gene knockdown (KD), while LNCaP cell line with an initially low isoform A expression was used forinduced overexpression of myosin 1C isoforms. We described theparameters of cell death using flow cytometry analysis of TMRE,caspase 3/7 detection reagent and annexin V-positive cells andshowed similar dynamics of early and late apoptotic events forcells with downregulated and overexpressed myosin 1C isoforms.Next, we analyzed the cell cycle for PC3 cells with downregulatedpan-myosin 1C and isoform A and LNCaP cells with inducedexpression of isoform A and showed the similar cell cycle distri-bution for cells with downregulated and upregulated expressionof myosin 1C isoforms. Finally, we described proliferation activ-ity for cells with altered expression of myosin 1C isoforms usingflow cytometry analysis of Ki67 expression. Ki-67 staining index(SI) was decreased twice both for PC3 cells with downregulatedpan-myosin 1C and myosin 1C isoform A (SI = 6.7 andSI = 5.9, respectively) compared with control values (11.4 fornon-treated PC3), indicating the decrease in proliferation activityfor cells with diminished expression of myosin 1C isoforms. Bycontrast, we did not find any differences in proliferation activityfor LNCaP cells with induced overexpression of isoform A.Taken together, our data support the role of myosin 1C isoformsin regulation of proliferation, but not cell cycle or cell deathdynamics in prostate cancer cells