Gap Junction Intercellular Communication in the Carcinogenesis Hallmarks: Is This a Phenomenon or Epiphenomenon?

If occupational tumors are excluded, cancer causes are largely unknown. Therefore, it appeared useful to work out a theory explaining the complexity of this disease. More than fifty years ago the first demonstration that cells communicate with each other by exchanging ions or small molecules through the participation of connexins (Cxs) forming Gap Junctions (GJs) occurred. Then the involvement of GJ Intercellular Communication (GJIC) in numerous physiological cellular functions, especially in proliferation control, was proven and accounts for the growing attention elicited in the field of carcinogenesis. The aim of the present paper is to verify and discuss the role of Cxs, GJs, and GJIC in cancer hallmarks, pointing on the different involved mechanisms in the context of the multi-step theory of carcinogenesis. Functional GJIC acts both as a tumor suppressor and as a tumor enhancer in the metastatic stage. On the contrary, lost or non-functional GJs allow the uncontrolled proliferation of stem/progenitor initiated cells. Thus, GJIC plays a key role in many biological phenomena or epiphenomena related to cancer. Depending on this complexity, GJIC can be considered a tumor suppressor in controlling cell proliferation or a cancer ally, with possible preventive or therapeutic implications in both cases.

From Genesis to Revelation: The Role of Inflammatory Mediators in Chronic Respiratory Diseases and their Control by Nucleic Acid-based Drugs.

Asthma, chronic obstructive pulmonary disease, cystic fibrosis, and idiopathic pulmonary fibrosis, are among the most common chronic diseases and their prevalence is increasing. Each of these diseases is characterized by the secretion of cytokines and pro-inflammatory molecules which are thought to play a critical role in their pathogenesis. Moreover, immune cells, particularly neutrophils, macrophages and dendritic cells as well structural cells such as epithelial and airway smooth muscle cells are also involved in the pathogenic cycle of these diseases. There is a pressing need for the development of new therapies for these pulmonary diseases, particularly as no existing treatment has been shown to reduce disease progression. HMGB1 (high-mobility group box 1), originally identified as a nuclear non histone protein with DNA-binding domains can be secreted by living and dying cells and it is now regarded as an important endogenous danger signaling molecule. Besides as a signal of tissue injury, HMGB1 is considered a powerful mediator of inflammation and high levels of HMGB1 are found in chronic lung diseases. The role of HMGB1 in respiratory diseases is still elusive nevertheless these studies suggest an involvement of this cytokine in their pathogenesis. Nucleic acid-based drugs (NABDs) are a novel class of pharmaceuticals including antisense oligonucleotides, DNA-zymes, and RNA interference as mediated by small interfering RNA (siRNA), which are used to dampen the expression of disease-causing genes having therapeutic potential for controlling chronic airway diseases. Due to their inherent difficulties, such as for example sensitivity to endonucleases, their delivery in vivo should be assured by vectors. Non-viral lipid- and polymer-based nanosystems have acquired much importance in this context. In this review, we will discuss these emerging tools in gene therapy of chronic lung diseases, particularly the use of siRNA in the down-regulation of critical molecules in the pathogenesis of chronic lung diseases, with particular emphasis on HMGB1 as therapeutic target.

Nanocarriers for respiratory diseases treatment: recent advances and current challenges.

Pulmonary delivery of locally-acting drugs encapsulated in nanocarriers provides several advantages for the treatment of respiratory diseases such as asthma, chronic obstructive pulmonary diseases, cystic fibrosis, tuberculosis and lung cancer. These advantages include, among others, sustained drug delivery to the lungs, reduced therapeutic dose and improved patient compliance. The aim of this review is to give an updated overview on recent advances recorded in the last few years in this field as well as on the major challenges still existing and that remain to be overcome before any clinical application. After an outline on the cellular and extracellular barriers affecting drug delivery to the airways both in physiological and pathological conditions, the significant developments recorded using inhaled polymeric- and lipid-based nanocarriers for drug and gene delivery to the lung are presented. In this discussion, the major challenges existing in the field are evidenced including the understanding of the factors governing the mucus penetration capability of these nanocarriers and the identification of new technologies for delivering drugs to specific regions or cell types of the lungs. In this regard, the recognition of receptor expressed only at lung level may facilitate drug targeting to this organ and it should improve the therapeutic efficacy of nanocarrier-based treatments for respiratory diseases.

Amniotic mesenchymal stem cells: a new source for hepatocyte-like cells and induction of CFTR expression by coculture with cystic fibrosis airway epithelial cells.

Cystic fibrosis (CF) is a monogenic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, with lung and liver manifestations. Because of pitfalls of gene therapy, novel approaches for reconstitution of the airway epithelium and CFTR expression should be explored. In the present study, human amniotic mesenchymal stem cells (hAMSCs) were isolated from term placentas and characterized for expression of phenotypic and pluripotency markers, and for differentiation potential towards mesoderm (osteogenic and adipogenic) lineages. Moreover, hAMSCs were induced to differentiate into hepatocyte-like cells, as demonstrated by mixed function oxidase activity and expression of albumin, alpha1-antitrypsin, and CK19. We also investigated the CFTR expression in hAMSCs upon isolation and in coculture with CF airway epithelial cells. Freshly isolated hAMSCs displayed low levels of CFTR mRNA, which even decreased with culture passages. Following staining with the vital dye CM-DiI, hAMSCs were mixed with CFBE41o- respiratory epithelial cells and seeded onto permeable filters. Flow cytometry demonstrated that 33-50% of hAMSCs acquired a detectable CFTR expression on the apical membrane, a result confirmed by confocal microscopy. Our data show that amniotic MSCs have the potential to differentiate into epithelial cells of organs relevant in CF pathogenesis and may contribute to partial correction of the CF phenotype.