c-Rel is a cell cycle modulator in human melanoma cells

New insights into the Lck-NF-κB signaling pathway

Lck is essential for the development, activity, and proliferation of T cells, which may contribute to pathological progression and development of human diseases, such as autoimmune disorders and cancers when functioning aberrantly. Nuclear factor-κB (NF-κB) was initially discovered as a factor bound to the κ light-chain immunoglobulin enhancer in the nuclei of activated B lymphocytes. Activation of the nuclear factor-κB pathway controls expression of several genes that are related to cell survival, apoptosis, and inflammation. Abnormal expression of Lck and nuclear factor-κB has been found in autoimmune diseases and malignancies, including rheumatoid arthritis, systemic lupus erythematosus, acute T cell lymphocytic leukemia, and human chronic lymphocytic leukemia, etc. Nuclear factor-κB inhibition is effective against autoimmune diseases and malignancies through blocking inflammatory responses, although it may lead to serious adverse reactions that are unexpected and unwanted. Further investigation of the biochemical and functional interactions between nuclear factor-κB and other signaling pathways may be helpful to prevent side-effects. This review aims to clarify the Lck-nuclear factor-κB signaling pathway, and provide a basis for identification of new targets and therapeutic approaches against autoimmune diseases and malignancies.

NF-кB c-Rel modulates pre-fibrotic changes in human fibroblasts

Skin fibrosis is one central hallmark of the heterogeneous autoimmune disease systemic sclerosis. So far, there are hardly any standardized and effective treatment options. Pathogenic mechanisms underlying fibrosis comprise excessive and uncontrolled myofibroblast differentiation, increased extracellular matrix protein (ECM) synthesis and an intensification of the forces exerted by the cytoskeleton. A deeper understanding of fibroblast transformation could help to prevent or reverse fibrosis by specifically interfering with abnormally regulated signaling pathways. The transcription factor NF-κB has been implicated in the progression of fibrotic processes. However, the cellular processes regulated by NF-κB in fibrosis as well as the NF-κB isoforms preferentially involved are still completely unknown. In an in vitro model of fibrosis, we consistently observed the induction of the c-Rel subunit of NF-κB. Functional abrogation of c-Rel by siRNA resulted in diminished cell contractility of dermal fibroblasts in relaxed, but not in stressed 3D collagen matrices. Furthermore, directed migration was reduced after c-Rel silencing and total N-cadherin expression level was diminished, possibly mediating the observed cellular defects. Therefore, NF-кB c-Rel impacts central cellular adhesion markers and processes which negatively regulate fibrotic progression in SSc pathophysiology.

Beta3-Tubulin is Critical for Microtubule Dynamics, Cell Cycle Regulation, and Spontaneous Release of Microvesicles in Human Malignant Melanoma Cells (A375)

Microtubules (MTs), microfilaments, and intermediate filaments, the main constituents of the cytoskeleton, undergo continuous structural changes (metamorphosis), which are central to cellular growth, division, and release of microvesicles (MVs). Altered MTs dynamics, uncontrolled proliferation, and increased production of MVs are hallmarks of carcinogenesis. Class III beta-tubulin (β3-tubulin), one of seven β-tubulin isotypes, is a primary component of MT, which correlates with enhanced neoplastic cell survival, metastasis and resistance to chemotherapy. We studied the effects of β3-tubulin gene silencing on MTs dynamics, cell cycle, and MVs release in human malignant melanoma cells (A375). The knockdown of β3-tubulin induced G2/M cell cycle arrest, impaired MTs dynamics, and reduced spontaneous MVs release. Additional studies are therefore required to elucidate the pathophysiologic and therapeutic role of β3-tubulin in melanoma.