No abstract

Microgravity exerts dramatic effects on cell morphology and functions, by disrupting cytoskeleton and adhesion structures, as well as by interfering with biochemical pathways and gene expression. Impairment of cells behavior has both practical and theoretical significance, given that investigations of mechanisms involved in microgravity-mediated effects may shed light on how biophysical constraints cooperate in shaping complex living systems. By exposing breast cancer MDA-MB-231 cells to simulated microgravity (~0.001 g), we observed the emergence of two morphological phenotypes, characterized by distinct membrane fractal values, surface area, and roundness. Moreover, the two phenotypes display different aggregation profiles and adherent behavior on the substrate. These morphological differences are mirrored by the concomitant dramatic functional changes in cell processes (proliferation and apoptosis) and signaling pathways (ERK, AKT, and Survivin). Furthermore, cytoskeleton undergoes a dramatic reorganization, eventually leading to a very different configuration between the two populations. These findings could be considered adaptive and reversible features, given that, by culturing microgravity-exposed cells into a normal gravity field, cells are enabled to recover their original phenotype. Overall these data outline the fundamental role gravity plays in shaping form and function in living systems.

Compelling evidence demonstrated that melatonin increases p53 activity in cancer cells. p53 undergoes acetylation to be stabilized and activated for driving cells destined for apoptosis/growth inhibition. Over-expression of p300 induces p53 acetylation, leading to cell growth arrest by increasing p21 expression. In turn, p53 activation is mainly regulated in the nucleus by MDM2. MDM2 also acts as E3 ubiquitin ligase, promoting the proteasome-dependent p53 degradation. MDM2 entry into the nucleus is finely tuned by two different modulations: the ribosomal protein L11, acts by sequestering MDM2 in the cytosol, whereas the PI3K-AkT-dependent MDM2 phosphorylation is mandatory for MDM2 translocation across the nuclear membrane. In addition, MDM2-dependent targeting of p53 is regulated in a nonlinear fashion by MDM2/MDMX interplay. Melatonin induces both cell growth inhibition and apoptosis in MCF7 breast cancer cells. We previously reported that this effect is associated with reduced MDM2 levels and increased p53 activity. Herein, we demonstrated that melatonin drastically down-regulates MDM2 gene expression and inhibits MDM2 shuttling into the nucleus, given that melatonin increases L11 and inhibits Akt-PI3K-dependent MDM2 phosphorylation. Melatonin induces a 3-fold increase in both MDMX and p300 levels, decreasing simultaneously Sirt1, a specific inhibitor of p300 activity. Consequently, melatonin-treated cells display significantly higher values of both p53 and acetylated p53. Thus, a 15-fold increase in p21 levels was observed in melatonin-treated cancer cells. Our results provide evidence that melatonin enhances p53 acetylation by modulating the MDM2/MDMX/p300 pathway, disclosing new insights for understanding its anticancer effect.

Melatonin and vitamin D3 inhibit breast cancer cell growth and induce apoptosis, but they have never been combined as a breast cancer treatment. Therefore, we investigated whether their association could lead to an enhanced anticancer activity. In MCF-7 breast cancer cells, melatonin together with vitamin D3, induced a synergistic proliferative inhibition, with an almost complete cell growth arrest at 144 hr. Cell growth blockade is associated to an activation of the TGFβ-1 pathway, leading to increased TGFβ-1, Smad4 and phosphorylated-Smad3 levels. Concomitantly, melatonin and D3, alone or in combination, caused a significant reduction in Akt phosphorylation and MDM2 values, with a consequent increase of p53/MDM2 ratio. These effects were completely suppressed by adding a monoclonal anti-TGFβ-1 antibody to the culture medium. Taken together, these results indicate that cytostatic effects triggered by melatonin and D3 are likely related to a complex TGFβ-1-dependent mechanism, involving down-regulation of both MDM2 and Akt-phosphorylation.

No abstract

Grape seed extract has been proven to exert anticancer effects on different tumors. These effects are mainly ascribed to catechin and procyanidin content. Analytical studies demonstrated that grape seed extract composition is complex and it is likely other components could exert biological activities. Using cell count and flow cytometry assays, we evaluated the cytostatic and apoptotic effects produced by three different grape seed extracts from Italia, Palieri and Red Globe cultivars, on Caco2 and HCT-8 colon cancer cells. These effects were compared to those induced by epigallocatechin and procyanidins, alone or in association, on the same cell lines. All the extracts induced growth inhibition and apoptosis in Caco2 and HCT-8 cells, along the intrinsic apoptotic pathway. On both cell lines, growth inhibition induced by Italia and Palieri grape seed extracts was significantly higher than that it has been recorded with epigallocatechin, procyanidins and their association. In Caco2 cells, the extract from Red Globe cultivar was less effective in inducing growth inhibition than procyanidins alone and in association with epigallocatechin, whereas, in HCT-8 cells, only the association of epigallocatechin and procyanidins triggers a significant proliferation decrease. On both cell lines, apoptosis induced by Italia, Palieri and Red Globe grape seed extracts was considerably higher than has been recorded with epigallocatechin, procyanidins and their association. These data support the hypothesis by which other compounds, present in the grape seed extracts, are likely to enhance the anticancer effects.

No abstract

Cancer begins to be recognized as a highly complex disease, and advanced knowledge of the carcinogenic process claims to be acquired by means of supragenomic strategies. Experimental data evidence that tumor emerges from disruption of tissue architecture, and it is therefore consequential that the tissue level should be considered the proper level of observation for carcinogenic studies. This paradigm shift imposes to move from a reductionistic to a systems biology approach. Indeed, cell phenotypes are emergent modes arising through collective nonlinear interactions among different cellular and microenvironmental components, generally described by a phase space diagram, where stable states (attractors) are embedded into a landscape model. Within this framework cell states and cell transitions are generally conceived as mainly specified by the gene-regulatory network. However, the system's dynamics cannot be reduced to only the integrated functioning of the genome-proteome network, and the cell-stroma interacting system must be taken into consideration in order to give a more reliable picture. As cell form represents the spatial geometric configuration shaped by an integrated set of cellular and environmental cues participating in biological functions control, it is conceivable that fractal-shape parameters could be considered as "omics" descriptors of the cell-stroma system. Within this framework it seems that function follows form, and not the other way around.