Gallic acid (3,4,5-trihydroxybenzoic acid), found in many plants either in free-form or part of tannins, is known to possess anti-microbial, antioxidant and cytotoxic properties. NFκB regulates the expression of several genes involved in carcinogenesis. These include anti-apoptotic, cytokines and cell cycle-regulatory genes. It is well established that the transcriptional factor NFκB is deregulated in many forms of cancer. Thus, agents that can suppress NFκB activation have the potential of suppressing carcinogenesis. In the present investigation, gallic acid was isolated from Alchornea glandulosa (Euphorbiaceae) and eight esters were synthesised. These compounds were evaluated against TNF-α-induced NFκB activation with stably transfected 293/NFκB-Luc human embryonic kidney cells. Gallates with IC(50) values in a range of 10-56 µM mediated inhibitory activity higher than gallic acid (IC(50) 76.0 ± 4.9 µM). In addition to inhibiting NFκB activation, gallic acid mediated a modest cytotoxic effect, and some of the gallates affected cell viability at the tested concentrations. Based on these results, suppression of NFκB activation by gallate esters could play a chemopreventive role in carcinogenesis.

Mechanobiologycal and redox processes sinergize to regulate physiological or pathological vascular conditions. More specifically, adaptations to cyclic stretch on vascular smooth muscle cells (VSMC) have been shown to be redox‐regulated. However, mechanisms connecting mechanoadaptation to oxidant generation are still unclear. Previously, we reported that protein disulfide isomerase A1 (PDI), a redox chaperone from endoplasmic reticulum, is targeted to peri/epicellular (pec) space and supports an anti‐constrictive remodeling effect in balloon‐injured arteries by means of cytoskeleton and extracellular matrix architecture organization. We hypothesized that pec PDI acts as a global redox adaptor by connecting oxidant generation with responses to extra‐ or intracellular forces. First, pecPDI inhibition through specific neutralizing antibody (PDI Ab) incubation, prevented stress fiber assembly in response to prolonged exposure to equibiaxial stretch (10–12% at 1 Hz for 24 h). In addition, uniaxial stretch promotes cell repositioning perpendicularly to stretch orientation. Such response was also regulated by pecPDI, as PDI Ab treatment attenuated cell alignment in stretched VSMC at 4h. Through biotinylation experiments followed by western detection, we showed that pecPDI sustains a pro‐oxidant effect on beta1 integrin thiols. To address whether pecPDI organizes intracellular force distribution in such events, we used traction force microscopy, which revealed a significantly decreased net contractile moment in PDGF‐exposed VSMC after pecPDI neutralization (0.70 ±0.08 AU vs control=0.9 ±0.09, p<0.05). Thus, pecPDI involvement in mechanoresponse is not only limited to external forces. The balance between intracellular traction forces and cell adhesion governs cell migration. Indeed, in a model of single VSMC migration, pecPDI impaired migration persistence without affecting total distance or velocity. Since the Rho GTPase RhoA is known to act as a master mechanoregulator, we addressed if downstream pecPDI‐related mechanisms involve RhoA. Neither RhoA expression nor total activity were affected by pecPDI inhibition. However, the polarized distribution of RhoA or caveolin‐3 clusters promoted by cyclic stretch was disrupted by pecPDI inhibition, which promoted a non‐polarized pattern of RhoA/caveolin‐3 cluster colocalization. Moreover, we searched for pecPDI effects on localized RhoA activity using a FRET biosensor. The higher local RhoA activity at cell protrusions compared to perinuclear regions was disrupted by pecPDI neutralization, confirming its regulation of localized RhoA activation. In conclusion, pecPDI acts as a redox organizer able to restrict the noise of cytoskeletal repositioning during mechanoresponses in VSMC. This effect may have several implications, including the role of redox processes and pecPDI on vascular remodeling. Support or Funding Information Supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), CEPID‐Redoxoma grant 2013/07937‐8 and scholarship grant 2013/17115‐5 This abstra...

Contact inhibition is a central feature orchestrating cell proliferation in culture experiments; its loss is associated with malignant transformation and tumorigenesis. We performed a co-culture experiment with human metastatic melanoma cell line (SKMEL- 147) and immortalized keratinocyte cells (HaCaT). After 8 days a spatial pattern was detected, characterized by the formation of clusters of melanoma cells surrounded by keratinocytes constraining their proliferation. In addition, we observed that the proportion of melanoma cells within the total population has increased. To explain our results we propose a spatial stochastic model (following a philosophy of the Widom-Rowlinson model from Statistical Physics and Molecular Chemistry) which considers cell proliferation, death, migration, and cell-to-cell interaction through contact inhibition. Our numerical simulations demonstrate that loss of contact inhibition is a sufficient mechanism, appropriate for an explanation of the increase in the proportion of tumor cells and generation of spatial patterns established in the conducted experiments.