The Activation of PPARγ by (2Z,4E,6E)-2-methoxyocta-2,4,6-trienoic Acid Counteracts the Epithelial–Mesenchymal Transition Process in Skin Carcinogenesis

Cutaneous squamous cell carcinoma (cSCC) is the most common UV-induced keratinocyte-derived cancer, and its progression is characterized by the epithelial–mesenchymal transition (EMT) process. We previously demonstrated that PPARγ activation by 2,4,6-octatrienoic acid (Octa) prevents cutaneous UV damage. We investigated the possible role of the PPARγ activators Octa and the new compound (2Z,4E,6E)-2-methoxyocta-2,4,6-trienoic acid (A02) in targeting keratinocyte-derived skin cancer. Like Octa, A02 exerted a protective effect against UVB-induced oxidative stress and DNA damage in NHKs. In the squamous cell carcinoma A431 cells, A02 inhibited cell proliferation and increased differentiation markers’ expression. Moreover, Octa and even more A02 counteracted the TGF-β1-dependent increase in mesenchymal markers, intracellular ROS, the activation of EMT-related signal transduction pathways, and cells’ migratory capacity. Both compounds, especially A02, counterbalanced the TGF-β1-induced cell membrane lipid remodeling and the release of bioactive lipids involved in EMT. In vivo experiments on a murine model useful to study cell proliferation in adult animals showed the reduction of areas characterized by active cell proliferation in response to A02 topical treatment. In conclusion, targeting PPARγ may be useful for the prevention and treatment of keratinocyte-derived skin cancer.

Reduction of Cell Proliferation by Acute C2H6O Exposure

Endogenous acetaldehyde production from the metabolism of ingested alcohol exposes hematopoietic progenitor cells to increased genotoxic risk. To develop possible therapeutic strategies to prevent or reverse alcohol abuse effects, it would be critical to determine the temporal progression of acute ethanol toxicity on progenitor cell numbers and proliferative status. We followed the variation of the cell proliferation rate in bone marrow and spleen in response to acute ethanol intoxication in the MITO-Luc mouse, in which NF-Y-dependent cell proliferation can be assessed in vivo by non-invasive bioluminescent imaging. One week after ethanol administration, bioluminescent signals in bone marrow and spleen decreased below the level corresponding to physiological proliferation, and they progressively resumed to pre-treatment values in approximately 4 weeks. Boosting acetaldehyde catabolism by administration of an aldehyde dehydrogenase activity activator or administration of polyphenols with antioxidant activity partially restored bone marrow cells' physiological proliferation. These results indicate that in this mouse model, bioluminescent alteration reflects the reduction of the physiological proliferation rate of bone marrow progenitor cells due to the toxic effect of aldehydes generated by alcohol oxidation. In summary, this study presents a novel view of the impact of acute alcohol intake on bone marrow cell proliferation in vivo.

Spinal cord injury causes chronic bone marrow failure

Spinal cord injury (SCI) causes immune dysfunction, increasing the risk of infectious morbidity and mortality. Since bone marrow hematopoiesis is essential for proper immune function, we hypothesize that SCI disrupts bone marrow hematopoiesis. Indeed, SCI causes excessive proliferation of bone marrow hematopoietic stem and progenitor cells (HSPC), but these cells cannot leave the bone marrow, even after challenging the host with a potent inflammatory stimulus. Sequestration of HSPCs in bone marrow after SCI is linked to aberrant chemotactic signaling that can be reversed by post-injury injections of Plerixafor (AMD3100), a small molecule inhibitor of CXCR4. Even though Plerixafor liberates HSPCs and mature immune cells from bone marrow, competitive repopulation assays show that the intrinsic long-term functional capacity of HSPCs is still impaired in SCI mice. Together, our data suggest that SCI causes an acquired bone marrow failure syndrome that may contribute to chronic immune dysfunction.

Transgenic Animal Models to Visualize Cancer-Related Cellular Processes by Bioluminescence Imaging

Preclinical animal models are valuable tools to improve treatments of malignant diseases, being an intermediate step of experimentation between cell culture and human clinical trials. Among different animal models frequently used in cancer research are mouse and, more recently, zebrafish models. Indeed, most of the cellular pathways are highly conserved between human, mouse and zebrafish, thus rendering these models very attractive. Recently, several transgenic reporter mice and zebrafishes have been generated in which the luciferase reporter gene are placed under the control of a promoter whose activity is strictly related to specific cancer cellular processes. Other mouse models have been generated by the cDNA luciferase knockin in the locus of a gene whose expression/activity has increased in cancer. Using BioLuminescence Imaging (BLI), we have now the opportunity to spatiotemporal visualize cell behaviors, among which proliferation, apoptosis, migration and immune responses, in any body district in living animal in a time frame process. We provide here a review of the available models to visualized cancer and cancer-associated events in living animals by BLI and as they have been successful in identifying new stages of early tumor progression, new interactions between different tissues and new therapeutic responsiveness.

Monitoring the Response of Hyperbilirubinemia in the Mouse Brain by In Vivo Bioluminescence Imaging

Increased levels of unconjugated bilirubin are neurotoxic, but the mechanism leading to neurological damage has not been completely elucidated. Innovative strategies of investigation are needed to more precisely define this pathological process. By longitudinal in vivo bioluminescence imaging, we noninvasively visualized the brain response to hyperbilirubinemia in the MITO-Luc mouse, in which light emission is restricted to the regions of active cell proliferation. We assessed that acute hyperbilirubinemia promotes bioluminescence in the brain region, indicating an increment in the cell proliferation rate. Immunohistochemical detection in brain sections of cells positive for both luciferase and the microglial marker allograft inflammatory factor 1 suggests proliferation of microglial cells. In addition, we demonstrated that brain induction of bioluminescence was altered by pharmacological displacement of bilirubin from its albumin binding sites and by modulation of the blood-brain barrier permeability, all pivotal factors in the development of bilirubin-induced neurologic dysfunction. We also determined that treatment with minocycline, an antibiotic with anti-inflammatory and neuroprotective properties, or administration of bevacizumab, an anti-vascular endothelial growth factor antibody, blunts bilirubin-induced bioluminescence. Overall the study supports the use of the MITO-Luc mouse as a valuable tool for the rapid response monitoring of drugs aiming at preventing acute bilirubin-induced neurological dysfunction.

NF-Y in cancer: Impact on cell transformation of a gene essential for proliferation

NF-Y is a ubiquitous heterotrimeric transcription factor with a binding affinity for the CCAAT consensus motif, one of the most common cis-acting element in the promoter and enhancer regions of eukaryote genes in direct (CCAAT) or reverse (ATTGG) orientation. NF-Y consists of three subunits, NF-YA, the regulatory subunit of the trimer, NF-YB, and NF-YC, all required for CCAAT binding. Growing evidence in cells and animal models support the notion that NF-Y, driving transcription of a plethora of cell cycle regulatory genes, is a key player in the regulation of proliferation. Proper control of cellular growth is critical for cancer prevention and uncontrolled proliferation is a hallmark of cancer cells. Indeed, during cell transformation aberrant molecular pathways disrupt mechanisms controlling proliferation and many growth regulatory genes are altered in tumors. Here, we review bioinformatics, molecular and functional evidence indicating the involvement of the cell cycle regulator NF-Y in cancer-associated pathways. This article is part of a Special Issue entitled: Nuclear Factor Y in Development and Disease, edited by Prof. Roberto Mantovani.