Effects of 5G-modulated 3.5 GHz radiofrequency field exposures on HSF1, RAS, ERK, and PML activation in live fibroblasts and keratinocytes cells

The potential health risks of exposure to radiofrequency electromagnetic fields from mobile communications technologies have raised societal concerns. Guidelines have been set to protect the population (e.g. non-specific heating above 1 °C under exposure to radiofrequency fields), but questions remain regarding the potential biological effects of non-thermal exposures. With the advent of the fifth generation (5G) of mobile communication, assessing whether exposure to this new signal induces a cellular stress response is one of the mandatory steps on the roadmap for a safe deployment and health risk evaluation. Using the BRET (Bioluminescence Resonance Energy-Transfer) technique, we assessed whether continuous or intermittent (5 min ON/ 10 min OFF) exposure of live human keratinocytes and fibroblasts cells to 5G 3.5 GHz signals at specific absorption rate (SAR) up to 4 W/kg for 24 h impact basal or chemically-induced activity of Heat Shock Factor (HSF), RAt Sarcoma virus (RAS) and Extracellular signal-Regulated Kinases (ERK) kinases, and Promyelocytic Leukemia Protein (PML), that are all molecular pathways involved in environmental cell-stress responses. The main results are (i), a decrease of the HSF1 basal BRET signal when fibroblasts cells were exposed at the lower SARs tested (0.25 and 1 W/kg), but not at the highest one (4 W/kg), and (ii) a slight decrease of As₂O₃ maximal efficacy to trigger PML SUMOylation when fibroblasts cells, but not keratinocytes, were continuously exposed to the 5G RF-EMF signal. Nevertheless, given the inconsistency of these effects in terms of impacted cell type, effective SAR, exposure mode, and molecular cell stress response, we concluded that our study show no conclusive evidence that molecular effects can arise when skin cells are exposed to the 5G RF-EMF alone or with a chemical stressor.

Is Infantile Hemangioma a Neuroendocrine Tumor?

Infantile hemangioma (IH) is the most common infantile tumor, affecting 5–10% of newborns. Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is currently the first-line treatment for severe IH; however, both its mechanism of action and its main cellular target remain poorly understood. Since betablockers can antagonize the effect of natural ADRB agonists, we postulated that the catecholamine produced in situ in IH may have a role in the propranolol response. By quantifying catecholamines in the IH tissues, we found a higher amount of noradrenaline (NA) in untreated proliferative IHs than in involuted IHs or propranolol-treated IHs. We further found that the first three enzymes of the catecholamine biosynthesis pathway are expressed by IH cells and that their levels are reduced in propranolol-treated tumors. To study the role of NA in the pathophysiology of IH and its response to propranolol, we performed an in vitro angiogenesis assay in which IH-derived endothelial cells, pericytes and/or telocytes were incorporated. The results showed that the total tube formation is sensitive to propranolol only when exogenous NA is added in the three-cell model. We conclude that the IH’s sensitivity to propranolol depends on crosstalk between the endothelial cells, pericytes and telocytes in the context of a high local amount of local NA.

Decreased CCN3 in Systemic Sclerosis Endothelial Cells Contributes to Impaired Angiogenesis

Systemic sclerosis (SSc) is a rare and severe connective tissue disease combining autoimmune and vasculopathy features, ultimately leading to organ fibrosis. Impaired angiogenesis is an often silent and life-threatening complication of the disease. We hypothesize that CCN3, a member of the CCN family of extracellular matrix proteins, which is an antagonist of the profibrotic protein CCN2 as well as a proangiogenic factor, is implicated in SSc pathophysiology. We performed skin biopsies on 26 patients with SSc, both in fibrotic and nonfibrotic areas for 17 patients, and collected 18 healthy control skin specimens for immunohistochemistry and cell culture. Histological analysis of nonfibrotic and fibrotic SSc skin shows a systemic decrease of papillary dermis surface as well as disappearance of capillaries. CCN3 expression is systematically decreased in the dermis of patients with SSc compared with healthy controls, particularly in dermal blood vessels. Moreover, CCN3 is decreased in vitro in endothelial cells from patients with SSc. We show that CCN3 is essential for endothelial cell migration and angiogenesis in vitro. In conclusion, CCN3 may represent a promising therapeutic target for patients with SSc presenting with vascular involvement.

Loss of Epidermal HIF-1α Blocks UVB-Induced Tumorigenesis by Affecting DNA Repair Capacity and Oxidative Stress

HIF-1α is constitutively expressed in mouse and human epidermis. It plays a crucial role in skin physiology, including the response of keratinocytes to UVR. However, little information is available about its role in photocarcinogenesis. Using a multistage model of UVB radiation-induced skin cancer, we show that the knockout of Hif-1α in the epidermis prevents tumorigenesis but at the same time triggers the formation of hyperkeratotic plaques. Our results indicate that the absence of oncogenic transformation in Hif-1α-ablated mice is related to increased DNA repair in keratinocytes, whereas the formation of hyperkeratotic plaques is caused by an increase in the levels of reactive oxygen species. Indeed, impairing the DNA repair machinery by ablating xeroderma pigmentosum C restored the UVB-induced neoplastic transformation of Hif-1α-ablated keratinocytes, whereas the development of hyperkeratotic plaques was blocked by chronic antioxidant treatment. We conclude that HIF-1α plays a procarcinogenic role in UVB-induced tumorigenesis.

Decreased levels of baseline and drug-induced tubulin polymerisation are hallmarks of resistance to taxanes in ovarian cancer cells and are associated with epithelial-to-mesenchymal transition

Background:

ABCB1 expression is uncommon in ovarian cancers in the clinical setting so we investigated non-MDR mechanisms of resistance to taxanes.

Methods:

We established eight taxane-resistant variants from the human ovarian carcinoma cell lines A2780/1A9, ES-2, MES-OV and OVCAR-3 by selection with paclitaxel or docetaxel, with counter-selection by the transport inhibitor valspodar.

Results:

Non-MDR taxane resistance was associated with reduced intracellular taxane content compared to parental controls, and cross-resistance to other microtubule stabilising drugs. Collateral sensitivity to depolymerising agents (vinca alkaloids and colchicine) was observed with increased intracellular vinblastine. These variants exhibited marked decreases in basal tubulin polymer and in tubulin polymerisation in response to taxane exposure. TUBB3 content was increased in 6 of the 8 variants. We profiled gene expression of the parental lines and resistant variants, and identified a transcriptomic signature with two highly significant networks built around FN1 and CDKN1A that are associated with cell adhesion, cell-to-cell signalling, and cell cycle regulation. miR-200 family members miR-200b and miR-200c were downregulated in resistant cells, associated with epithelial to mesenchymal transition (EMT), with increased VIM, FN1, MMP2 and/or MMP9.

Conclusions:

These alterations may serve as biomarkers for predicting taxane effectiveness in ovarian cancer and should be considered as therapeutic targets.

Relationships between genetic polymorphisms and anticancer drug cytotoxicity vis-à-vis the NCI-60 panel

INTRODUCTION

The National Cancer Institute (NCI)-60 panel consists of 60 human tumor cell lines initially established for screening thousands of molecules for antiproliferative activity. It has been powerful for deciphering the relationships between anticancer drug cytotoxicity and cell molecular characteristics. We tested its potential interest for establishing relationships between the polymorphism of genes involved in drug metabolism and transport or in DNA repair, and drug cytotoxicity extracted from NCI databases.

METHODS

Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques, three frequent single nucleotide polymorphisms (SNPs) were analyzed: Lys751Gln in the Xeroderma pigmentosum complementation group D (XPD, ERCC2) gene, Asp1104His in the Xeroderma pigmentosum complementation group G (XPG, ERCC5) gene and Ile105Val in the glutathione S-transferase P1 (GSTP1) gene.

RESULTS

The allelic frequencies of the variants were 33% for ERCC2, 23% for ERCC5 and 39% for GSTP1. The ERCC2 polymorphism appeared to be a strong determinant of the in vitro cytotoxicity of most anticancer agents, with lower half maximal inhibitory concentration (IC50) values in variant homozygous lines than in common homozygous or heterozygous cell lines. Unexpectedly, the cytotoxicity of taxanes appeared markedly dependent upon the ERCC2 genotype, with threefold lower mean IC50 values in variant homozygous cell lines. The ERCC5 genotype appeared to be important only for taxanes, with fourfold higher IC50 values in variant homozygous cell lines. The GSTP1 polymorphism was related to the cytotoxicity of several drug classes, especially topoisomerase inhibitors, antimetabolites and N7 alkylating agents.

CONCLUSION

The NCI-60 panel is capable of providing clues and tracks for the establishment of clinically useful relationships between a given genotype and the cytotoxicity of an anticancer agent.

Identification of gene polymorphisms of human DNA topoisomerase I in the National Cancer Institute panel of human tumour cell lines

Topoisomerase 1 (Top1), a nuclear enzyme involved in DNA relaxation, is the target of several anticancer drugs. TOP1 mutations occur in camptothecin-resistant tumour cell lines. We explored, in the NCI panel of 60 human tumour cell lines, whether polymorphic variations in the TOP1 gene could explain differences in drug sensitivity. The 21 exons of the gene were fully studied as well as five intronic domains that had previously been shown to harbour single nucleotide polymorphisms (SNPs) or mutations. PCR products covering the whole exonic sequences or the relevant intronic domains were subjected to denaturing high-performance liquid chromatography. Nucleotide variations were then determined by sequencing. Discrimination between intronic common and variant homozygous samples was performed using a restriction fragment length polymorphism technique. Only one exonic mutation was detected, at the heterozygous state; it occurs in exon 19 of a colon cancer cell line (HCT-15) and consists of a G>A transition at position 75, resulting in a Met675Ile change. The intronic sequences studied harboured the SNPs expected with allelic frequencies between 20 and 40%. Three major haplotypes, generating 92% of the 10 genotypes encountered, were defined as containing none of the intronic SNPs, or three of them, or all of them. No significant relationship was evidenced between Top1 expression and the TOP1 polymorphisms studied. However, when comparing the cytotoxicity of 138 drugs as a function of the genotypes, several drug groups, namely Top1 inhibitors, antifolates and taxanes, had significantly different IC₅₀s as a function of the distribution of the intronic SNPs of the TOP1 gene.