G-actin stability may imply its potential usefulness for permanent senescence detection. Along with slight to moderate cytoskeletal alterations, the obtained results suggest transient senescence-like state induction, followed by morphology typical of mitotic catastrophe in part of the A549 cells.

Due to the profile of released mediators (such as cytokines, chemokines, growth factors, etc.), neoplastic cells modulate the activity of immune system, directly affecting its components both locally and peripherally. This is reflected by the limited antineoplastic activity of the immune system (immunosuppressive effect), induction of tolerance to neoplastic antigens, and the promotion of processes associated with the proliferation of neoplastic tissue. Most of these responses are macrophages dependent, since these cells show proangiogenic properties, attenuate the adaptive response (anergization of naïve T lymphocytes, induction of Treg cell formation, polarization of immune response towards Th2, etc.), and support invasion and metastases formation. Tumor-associated macrophages (TAMs), a predominant component of leukocytic infiltrate, “cooperate” with the neoplastic tissue, leading to the intensified proliferation and the immune escape of the latter. This paper characterizes the function of macrophages in the development of neoplastic disease.

BackgroundSenescence in the population of cells is often described as a program of restricted proliferative capacity, which is manifested by broad morphological and biochemical changes including a metabolic shift towards an autophagic-like response and a genotoxic-stress related induction of polyploidy. Concomitantly, the cell cycle progression of a senescent cell is believed to be irreversibly arrested. Recent reports suggest that this phenomenon may have an influence on the therapeutic outcome of anticancer treatment. The aim of this study was to verify the possible involvement of this program in the response to the treatment of the A549 cell population with low doses of etoposide, as well as to describe accompanying cytoskeletal alterations.MethodsAfter treatment with etoposide, selected biochemical and morphological parameters were examined, including: the activity of senescence-associated ß-galactosidase, SAHF formation, cell cycle progression, the induction of p21Cip1/Waf1/Sdi1 and cyclin D1, DNA strand breaks, the disruption of cell membrane asymmetry/integrity and ultrastructural alterations. Vimentin and G-actin cytoskeleton was evaluated both cytometrically and microscopically.Results and conclusionsEtoposide induced a senescence-like phenotype in the population of A549 cells. Morphological alterations were nevertheless not directly coupled with other senescence markers including a stable cell cycle arrest, SAHF formation or p21Cip1/Waf1/Sdi1 induction. Instead, a polyploid, TUNEL-positive fraction of cells visibly grew in number. Also upregulation of cyclin D1 was observed. Here we present preliminary evidence, based on microscopic analyses, that suggest a possible role of vimentin in nuclear alterations accompanying polyploidization-depolyploidization events following genotoxic insults.

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Sulforaphane (SFN) is present in plants belonging to Cruciferae family and was first isolated from broccoli sprouts. Chemotherapeutic and anticarcinogenic properties of sulforaphane were demonstrated, however, the underlying mechanisms are not fully understood. In this study we evaluated the expression of cyclin D1 and p21 protein in SFN-treated A549 cells and correlated these results with the extent of cell death and/or cell cycle alterations, as well as determined a potential contribution of cyclin D1 to cell death. A549 cells were treated with increasing concentrations of SFN (30, 60 and 90 µM) for 24 h. Morphological and ultrastructural changes were observed using light, transmission electron microscope and videomicroscopy. Image-based cytometry was applied to evaluate the effect of SFN on apoptosis and the cell cycle. Cyclin D1 and p21 expression was determined by flow cytometry, RT-qPCR and immunofluorescence. siRNA was used to evaluate the role of cyclin D1 in the process of suforaphane-induced cell death. We found that the percentage of cyclin D1-positive cells decreased after the treatment with SFN, but at the same time mean fluorescence intensity reflecting cyclin D1 content was increased at 30 µM SFN and decreased at 60 and 90 µM SFN. Percentage of p21-positive cells increased following the treatment, with the highest increase at 60 µM SFN, at which concentration mean fluorescence intensity of this protein was also significantly increased. The 30-µM dose of SFN induced an increased G2/M phase population along with a decreased polyploid fraction of cells, which implies a functional G2/M arrest. The major mode of cell death induced by SFN was necrosis and, to a lower degree apoptosis. Transfection with cyclin D1-siRNA resulted in significantly compromised fraction of apoptotic and necrotic cells, which suggests that cyclin D1 is an important determinant of the therapeutic efficiency of SFN in the A549 cells.

Abstract:The actin cytoskeleton plays an important role in many cellular processes, including cell mortality, mitosis, cytokinesis, intracellular transport, endocytosis and secretion but also is involved in gene transcription. The dynamics of the actin cytoskeleton is controlled by different classes of actin-binding proteins (ABPs) which regulate the polymerization of actin filaments. In this report we used siRNA against cofilin-1 (nonmuscle) to demonstrate the effect of cofilin on the nuclear and cytoplasmic actin pools in CHO AA8 cells after exposition to various concentrations of doxorubicin. The immunofluorescence studies showed doxorubicin dose dependent tendency to formation the multinucleated giant cells, but also the increase of fluorescence intensity of cofilin in nuclei of untransfected cells. Induction of cell death with doxorubicin treatment in untransfected cells revealed both mitotic catastrophe (in both lower and higher doxorubicin doses) and apoptosis (mostly in higher doxorubicin doses), whereas among cofilin-1 down-regulated cells we observed only mitotic catastrophe. The results suggest that cofilin has apoptosis-inducing ability and that mitotic catastrophe is independent from F-actin content in cell nucleus. In this point of view we conclude that different mechanisms of chromatin reorganization are involved in these two processes. Moreover, we suppose that apoptosis and mitotic catastrophe are independent from each other.

Mesenchymal stem cells (MSCs) are known to interact with cancer cells through direct cell-to-cell contact and secretion of paracrine factors, although their exact influence on tumor progression in vivo remains unclear. To better understand how fetal and adult stem cells affect tumors, we analyzed viability of human renal (786-0) and bladder (T24) carcinoma cell lines cultured in conditioned media harvested from amniotic fluid-derived stem cells (AFSCs) and adipose-derived stem cells (ASCs). Both media reduced metabolic activity of 786-0 cells, however, decreased viability of T24 cells was noted only after incubation with conditioned medium from ASCs. To test the hypothesis that MSCs-secreted factors might be involved in chemoresistance acquisition, we further analyzed influence of mesenchymal stem cell conditioned media (MSC-CM) on cancer cells sensitivity to ciprofloxacin, that is considered as potential candidate agent for urinary tract cancers treatment. Significantly increased resistance to tested drug indicates that MSCs may protect cancer cells from chemotherapy. J. Cell. Biochem. 118: 1361-1368, 2017. © 2016 Wiley Periodicals, Inc.