Transient TNF regulates the self-renewing capacity of stem-like label-retaining cells in sphere and skin equivalent models of melanoma

Abstract

Background: It is well established that inflammation promotes cancer, including melanoma, although the exact mechanisms involved are less known. In this study, we tested the hypothesis that inflammatory factors affect the cancer stem cell (CSC) compartment responsible for tumor development and relapse. Results: Using an inducible histone 2B-GFP fusion protein as a tracer of cell divisional history, we determined that tumor necrosis factor (TNF), which is a classical pro-inflammatory cytokine, enlarged the CSC pool of GFP-positive label-retaining cells (LRCs) in tumor-like melanospheres. Although these cells acquired melanoma stem cell markers, including ABCB5 and CD271, and self-renewal ability, they lost their capacity to differentiate, as evidenced by the diminished MelanA expression in melanosphere cells and the loss of pigmentation in a skin equivalent model of human melanoma. The undifferentiated cell phenotype could be reversed by LY294002, which is an inhibitor of the PI3K/AKT signaling pathway, and this reversal was accompanied by a significant reduction in CSC phenotypic markers and functional properties. Importantly, the changes induced by a transient exposure to TNF were long-lasting and observed for many generations after TNF withdrawal.

Nerve Growth Factor and proNGF Simultaneously Promote Symmetric Self-Renewal, Quiescence, and Epithelial to Mesenchymal Transition to Enlarge the Breast Cancer Stem Cell Compartment

“…(B): Tumor latency and metastatic potential of injected cells. Human cells disseminated to mouse lung, liver and brain were detected by reverse transcriptase quantitative polymerase chain reaction using human‐specific β‐microtubulin probes as previously described . Abbreviations: bFGF, basic fibroblast growth factor; EGF, epidermal growth factor; NGF, nerve growth factor.…”

“…The NGF-and proNGF-mediated enlargement of the stem cell compartment appears to be independent of breast cancer molecular subtype or hormone receptor status. This leads us to infer that NGF and proNGF might stimulate the self- Human cells disseminated to mouse lung, liver and brain were detected by reverse transcriptase quantitative polymerase chain reaction using human-specific b-microtubulin probes as previously described [26]. Abbreviations: bFGF, basic fibroblast growth factor; EGF, epidermal growth factor; NGF, nerve growth factor.…”

“…Cells were transfected using Amaxa (Lonza, Basel, Switzerland) according to the manufacturer's instructions. MCF-7, T47D, and BT-20 cell lines were stably transfected with the H2B-GFP (green fluorescent protein) inducible Tet-on plasmid system constructed as described elsewhere [26]. Stably transfected cells were selected with 0.5 mg/ml of blasticidin (Invitrogen) and 400 mg/ml of geneticin (Santa Cruz Biotechnology, Heidelberg, Germany, http://www.scbt.com).…”

“…Also, quiescence is one of the leading factors conferring CSC resistance to conventional therapies [38,39]. To further investigate the mechanisms by which NGF and proNGF could modulate the CSC compartment, we used a genetically modified cellular model expressing a histone 2B-GFP fusion protein upon tetracycline induction [26,40]. In this system, quiescent/slow-cycling cells will be highly GFP-positive after tetracycline induction.…”

Tumor necrosis factor receptor 2-signaling in CD133-expressing cells in renal clear cell carcinoma

“…TNF is secreted by RCC [ 37 , 61 ], and increase stemness properties in RCC in 2D cultures [ 62 ]. TNF targets the quiescent/slow-cycling stem cells and promotes PI3K/AKT-driven expansion in melanoma by preventing their asymmetrical self-renewal [ 63 ]. These data strongly suggest that TNF, present in the tumor microenvironment, may influence the behaviour of CD133 + cells in RCC and potentiate their self-renewal properties.…”