The alterations in SATB1 and nuclear F-actin expression affect apoptotic response of the MCF-7 cells to geldanamycin

Introduction. The function and localization of actin in the nucleus have not yet been fully described. However, actin seems to be a key protein in nuclear processes interacting with chromatin and matrix proteins. The aim of the study was to evaluate the effect of controlled expression of nuclear pool of F-actin and special AT-rich sequence-binding protein 1 (SATB1) on the in vitro induction of active cell death by geldanamycin (GA). Material and methods. The expression of SATB1 was regulated by the transfection of non-aggressive breast cancer MCF-7 cells with siRNA against SATB1 or expression plasmid with cloned cDNA of SATB1. The altered expression of cofilin-1 in these cells was used to regulate the nuclear expression and localization of F-actin. The effect of GA was analyzed in the context of cell death induction and cell cycle alterations. Results. Our studies revealed that the targeted regulation of SATB1 and cofilin-1 expression changed the apoptotic response of the MCF-7 cells to GA. The overexpression of these proteins potentiated GA-induced arrest of the cells in the G1 phase of cell cycle and increased the population of the hypodiploid cells. Conclusion. The alterations in the nuclear expression of SATB1 and F-actin in MCF-7 cells may affect their active cell death in response to GA

The interactions between SATB1 and F-actin are important for mechanisms of active cell death

Introduction. The direct involvement of nuclear actin filaments in gene transcription and remodeling of chromatin is still debatable. However, nuclear localization of F-actin and its interactions with other nuclear matrix proteins have been reported. The aim of the study was to estimate the interactions between nuclear F-actin and one of the matrix proteins, special AT-rich sequence-binding protein 1 (SATB1), during active cell death induced in vitro by geldanamycin (GA). Material and methods. The expression of SATB1 was modified by the transfection of non-aggressive breast cancer MCF-7 cells with siRNA against SATB1 or expression plasmid with cloned cDNA of SATB1. The amount and localization of F-actin were altered by changes of cofilin-1 (CFL1) expression in MCF-7 cells. The association between SATB1 and F-actin during GA-induced cell death was analyzed using confocal and transmission electron microscopy. Results. Our studies revealed the colocalization between nuclear F-actin and SATB1 protein, during GA-induced death of breast cancer MCF-7 cells. The colocalization was enhanced in cells with overexpressed SATB1 and cofilin-1. At the ultrastructural level the SATB1 and F-actin complexes were seen at the border of condensed and decondensed chromatin. The presence of SATB1/F-actin molecular complexes was confirmed by magnetic separation of F-actin and interacting proteins. Conclusion. We suggest that the molecular interactions between SATB1 and F-actin are necessary for active cell death to occur

THE EFFECTS OF ELECTRICAL STIMULATION AND LASER RADIATION ON F ACTIN REORGANIZATION IN A549 AND CHO AA8 CELL LINES

Background: The aim of this report was to determine the effects of electrical stimulation and laser radiation on non-small lung cancer (A549) and Chinese Hamster Ovary cell line (CHO AA8). Furthermore, we also analyzed viability and size of the extracellular spaces in CHO AA8 and A549 cells. Methods: In order to evaluate the cell viability Tali® Image-Based Cytometer was used. The material (non-small lung cancer cell – A549 and Chinese Hamster Ovary – CHO AA8) was evaluated by the light and confocal fluorescence microscope. Results: The data demonstrated that exposure to both electrical stimulation and laser radiation for 3 and 5 minutes showed non statistical differences in the percentage of live cells. The morphological abnormalities and microfilaments reorganization indicated induction non apoptotic type of cell death such as mitotic catastrophe. Moreover, CHO AA8 as non-cancerous cells exhibited lower sensitivity for laser and electrical stimulation in comparison to A549 cell line. Conclusions: Our results confirmed contraindicated the use of these methods, especially due to an increase of the risk of metastasis. Moreover, our study suggests that the laser radiation and electrical stimulation may have limited applications in the cancer patients and that choice of these treatment methods should be used in carefully selected patients

MOESM1 of Paclitaxel and the dietary flavonoid fisetin: a synergistic combination that induces mitotic catastrophe and autophagic cell death in A549 non-small cell lung cancer cells

Additional file 1: Figure S1. The combined effect of fisetin with mitoxantrone (MIT), or methotrexate (MTX), or arsenic trioxide (ATO). (a,b) Logarithmic combination index plot (Fa-log(CI) plot) for FIS and MIT or MTX, respectively. CI values (logarithmic) are plotted as a function of the fractional inhibition (fa) of cell viability/growth by computer simulation (CompuSyn software) from 0.1 to 0.95. In the Fa-log(CI) plot, the synergism is indicated by a negative value (log(CI) < 0), antagonism is indicated by a positive value (log(CI) > 0), and additive effect (denoted by a dashed line) is indicated by 0 (log(CI) = 0). (c) Combination index plot (Fa-CI plot) for FIS and ATO co-treatment. CI values are plotted as a function of the fractional inhibition (fa) of cell viability/growth by computer simulation (CompuSyn software) from 0.1 to 0.95. CI < 1 designates synergism, CI = 1 indicates additivity (denoted by a dashed line), and CI > 1 represents antagonism. In all cases triangles represent CI values derived from the actual experimental points