Phospholipase C-beta2 promotes mitosis and migration of human breast cancer-derived cells

Like most human neoplasm, breast cancer has aberrations in signal transduction elements that can lead to increased proliferative potential, apoptosis inhibition, tissue invasion and metastasis. Due to the high heterogeneity of this tumor, currently, no markers are clearly associated with the insurgence of breast cancer, as well as with its progression from in situ lesion to invasive carcinoma. We have recently demonstrated an altered expression of the beta2 isoform of the phosphoinositide-dependent phospholipase C (PLC) in invasive breast tumors with different histopathological features. In primary breast tumor cells, elevated amounts of this protein are closely correlated with a poor prognosis of patients with mammary carcinoma, suggesting that PLC-beta2 may be involved in the development and worsening of the malignant phenotype. Here we demonstrate that PLC-beta2 may improve some malignant characteristics of tumor cells, like motility and invasion capability, but it fails to induce tumorigenesis in non-transformed breast-derived cells. We also report that, compared with the G(0)/G(1) phases of the cell cycle, the cells in S/G(2)/M phases show high PLC-beta2 expressions that reach the greatest levels during the late mitotic stages. In addition, even if unable to modify the proliferation rate and the expression of cell cycle-related enzymes of malignant cells, PLC-beta2 may promote the G(2)/M progression, a critical event in cancer evolution. Since phosphoinositides, substrates of PLC, are involved in regulating cytoskeleton architecture, PLC-beta2 in breast tumor cells may mediate the modification of cell shape that characterizes cell division, motility and invasion. On the basis of these data, PLC-beta2 may constitute a molecular marker of breast tumor cells able to monitor the progression to invasive cancers and a target for novel therapeutic breast cancer strategies

Vav1: A Key Player in Agonist-Induced Differentiation of Promyelocytes from Acute Myeloid Leukemia (APL)

Acute promyelocytic leukemia (APL) is the M3 subtype of acute myeloid leukemias, characterized by hyperproliferation of progenitors that are committed to terminal differentiation into granulocytes. Despite recent clinical studies using arsenic trioxide, anthracyclines and anti-CD33 monoclonal antibodies, all-trans retinoic acid (ATRA)-based therapy represents, until today, the standard cure of APL patients. Studies on both APL blasts and APL-derived cell lines have elucidated that the treatment with ATRA promotes the completion of their maturation to neutrophils throughout a complex network that includes the degradation of the PML/RAR-alpha fusion protein and the activation of RAR-alpha-mediated gene transcription. Even if the underlying mechanism by which ATRA interacts with its receptor located on specific DNA sequences is well known, the events mediated by the ATRA target genes, able to elicit the integrated signaling networks that promote maturation of tumoral promyelocytes, are currently studied to identify specific targets for new therapies of APL. Stemming from the above reported consideration, the proposed review will focus on the possible role of the multidomain protein Vav1 as a target molecule in treatment of APL. This proposal arises from evidences demonstrating that, in addition to promote the acquisition of a mature phenotype by normal hematopoietic cells, Vav1 is a crucial molecule in the completion of the differentiation program to neutrophils of APL-derived cells induced by ATRA. Indeed, it was demonstrated that the down-modulation of Vav1 prevents, and the Vav1 over-expression potentiates, the ability of ATRA to induce the acquisition of a mature phenotype by tumoral promyelocytes

In triple negative breast tumor cells, PLC-β2 promotes the conversion of CD133high to CD133low phenotype and reduces the CD133-related invasiveness

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The role of the nuclear Akt activation and Akt inhibitors in all-trans-retinoic acid-differentiated HL-60 cells

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CD133 in Breast Cancer Cells: More than a Stem Cell Marker

Initially correlated with hematopoietic precursors, the surface expression of CD133 was also found in epithelial and nonepithelial cells from adult tissues in which it has been associated with a number of biological events. CD133 is expressed in solid tumors as well, including breast cancer, in which most of the studies have been focused on its use as a surface marker for the detection of cells with stem-like properties (i.e., cancer stem cells (CSCs)). Differently with other solid tumors, very limited and in part controversial are the information about the significance of CD133 in breast cancer, the most common malignancy among women in industrialized countries. In this review, we summarize the latest findings about the implication of CD133 in breast tumors, highlighting its role in tumor cells with a triple negative phenotype in which it directly regulates the expression of proteins involved in metastasis and drug resistance. We provide updates about the prognostic role of CD133, underlining its value as an indicator of increased malignancy of both noninvasive and invasive breast tumor cells. The molecular mechanisms at the basis of the regulation of CD133 levels in breast tumors have also been reviewed, highlighting experimental strategies capable to restrain its level that could be taken into account to reduce malignancy and/or to prevent the progression of breast tumors.Initially correlated with hematopoietic precursors, the surface expression of CD133 was also found in epithelial and nonepithelial cells from adult tissues in which it has been associated with a number of biological events. CD133 is expressed in solid tumors as well, including breast cancer, in which most of the studies have been focused on its use as a surface marker for the detection of cells with stem-like properties (i.e., cancer stem cells (CSCs)). Differently with other solid tumors, very limited and in part controversial are the information about the significance of CD133 in breast cancer, the most common malignancy among women in industrialized countries. In this review, we summarize the latest findings about the implication of CD133 in breast tumors, highlighting its role in tumor cells with a triple negative phenotype in which it directly regulates the expression of proteins involved in metastasis and drug resistance. We provide updates about the prognostic role of CD133, underlining its value as an indicator of increased malignancy of both noninvasive and invasive breast tumor cells. The molecular mechanisms at the basis of the regulation of CD133 levels in breast tumors have also been reviewed, highlighting experimental strategies capable to restrain its level that could be taken into account to reduce malignancy and/or to prevent the progression of breast tumors

PLCB2 (phospholipase C, beta 2)

Review on PLCB2 (phospholipase C, beta 2), with data on DNA, on the protein encoded, and where the gene is implicated

Vav1 sustains the in vitro differentiation of normal and tumor precursors to insulin producing cells induced by all-trans retinoic acid (ATRA)

All-trans retinoic acid (ATRA) promotes the development and the function of insulin producing cells and induces partial differentiation of pancreatic tumor cells. A number of evidences clearly indicate that the ATRA mediated signaling may have a substantial role in therapeutic approaches based on restoration of functional beta-cells. Among the proteins up-regulated by ATRA, Vav1 is involved in maturation and function of haematopoietic cells and is essential for retinoids induced differentiation of tumor promyelocytes. The presence of Vav1 in solid tissues, including pancreas, is considered ectopic and no role in the differentiation of human epithelial cells has so far been described. We demonstrated here that Vav1 sustains the maturation to beta-cells of the normal precursors human Biliary Tree Stem/progenitor Cells (hBTSCs) induced by a differentiation medium containing ATRA and that, in the mature normal pancreas, insulin-producing cells express variable levels of Vav1. Using pancreatic ductal adenocarcinoma (PDAC)-derived cells, we also revealed that the ATRA induced up-modulation of Vav1 is essential for the retinoid-induced trans-differentiation of neoplastic cells into insulin producing cells. The results of this study identify Vav1 as crucial molecule in ATRA induced maturation of insulin producing cells and suggest this protein as a marker for new strategies ended to restore functional beta-cells

In triple negative breast tumor cells, PLC-β2 promotes the conversion of CD133high to CD133low phenotype and reduces the CD133-related invasiveness

Beyond its possible relationship with stemness of tumor cells, CD133/prominin is a highly glycosylated trans-membrane protein that correlates with tumor size, metastasis and clinical stage of triple negative breast cancers (TNBC), that represent 20% of all breast tumors and have a particularly worse clinical outcome than other tumor subtypes [1]. The correlation between the levels of CD133 expression and the biology of breast tumor cells was studied in CD133low and CD133high cell subpopulations isolated from MDA-MB-231 cells (ER-, PR-, HER2-). High expression of CD133 characterizes a small percentage of cells with larger adhesion area, lower proliferation rate, higher invasion capability and increased expression of proteins involved in metastasis and drug resistance of breast cancers. PLC-b2 expression, that plays a crucial role in malignancy of breast tumor cells [2, 3], inversely correlates with the levels of CD133 and has a role in inducing the CD133high cells to CD133low cells conversion. The forced up-regulation of PLC-b2 counteracts the invasiveness of CD133high MDAMB- 231, suggesting that, in TNBC, the de-regulation of this PLC isozyme is responsible of the switch from an early to a mature tumoral phenotype also by reducing the expression of CD133. These data might contribute to identify unexplored key steps in TNBC malignancy, to be considered for potential therapeutic strategies

Experimental Observation of Surface Charge Inversion in a Biological Nanopore in Presence of Monovalent and Multivalent Cations

Surface CD133 and EpCAM, proliferation and invasiveness in breast derived cell lines. In A, representative cytofluorimetrical evaluation of CD133 and EpCAM surface levels in MCF7 and MDA-MB-468 cells after labelling with a PE-conjugated anti-CD133 antibody or with a FITC-conjugated anti-EpCAM antibody. The staining with isotype matched antibodies (IgG) is used as a control. The expression of each antigen is shown on a biparametric dot plot and the percentage and MFI of positive cells are indicated at the upper right of each panel. In B, MDA-MB-231, MCF7 and MDA-MB-468 cells were subjected to dynamic monitoring of proliferation and invasion through Matrigel using the xCELLigence RTCA system. Cell Index (CI) is reported and error bars indicate ÂąSD. The correspondent Slope analysis, that describes the steepness, incline, gradient, and changing rate of the CI curves over time, is shown on the right. The data were collected from three separate experiments (PDF 364 kb

PLC-βeta2 plays a phenotype dependent role in the malignant potential induced by hypoxia in breast cancer cells

Hypoxia plays a crucial role in malignant progression of solid tumors, including breast cancer, since neoplastic cells adapt to low oxygen availability by modulating the expression of genes involved in survival, proliferation, metabolic reprogramming, stem cell maintenance, EMT, angiogenesis, invasion and metastasis (1). Among the signaling molecules deregulated in breast tumors, the beta2 isoform of the phosphoi- nositide-dependent phospholipase C (PLC-β2) is expressed in the large majority of primary invasive tumors from all histological subtypes in which it strongly correlates with malignancy and with a poor prognosis (2). PLC-β2 is also expressed in breast tumor- derived cells, in which it improves proliferation and motility and sustains invasion capability (3). A decreased PLC-β2 expression is induced by hypoxia in the BT-474 and MCF7 cell lines, that is correlated with the hypoxia-induced modulation of the EMT markers E-cadherin and Vimentin, as well as of the stem cell marker CD133. In contrast, hypoxia induced the increase of PLC-β2 levels in MDA-MB-231 cells, in which it supports the hypoxia-related reorganization of actin cytoskeleton. In all examined cell lines, the prevention of the effects of hypoxia on PLC-β2 also reduced the recovery of HIF-1α, in turn able to exert a phenotype-related role in modulating EMT and expression of CD133 during the cell response to low oxygen. Our data highlighted a peculiar effect of low oxygen availability on PLC-β2 expression in breast tumor cells with different phenotypes and allocate PLC-β2 in the complex and interconnected transcriptional activity induced by hypoxia. Our results also suggest that the forced modulation of PLC-β2 programmed on the basis of the tumor phenotype may prevent malignant progression of breast neoplasia as a consequence of intra-tumoral hypoxia