The involvement of RIPK4 in TNF-α-stimulated IL-6 and IL-8 production by melanoma cells

PURPOSE

The receptor-interacting protein kinase (RIPK4) has an oncogenic function in melanoma, regulates NF-κB and Wnt/β-catenin pathways, and is sensitive to the BRAF inhibitors: vemurafenib and dabrafenib which lead to its decreased level. As its role in melanoma remains not fully understood, we examined the effects of its downregulation on the transcriptomic profile of melanoma.

METHODS

Applying RNA-seq, we revealed global alterations in the transcriptome of WM266.4 cells with RIPK4 silencing. Functional partners of RIPK4 were evaluated using STRING and GeneMANIA databases. Cells with transient knockdown (via siRNA) and stable knockout (via CRISPR/Cas9) of RIPK4 were stimulated with TNF-α. The expression levels of selected proteins were assessed using Western blot, ELISA, and qPCR.

RESULTS

Global analysis of gene expression changes indicates a complex role for RIPK4 in regulating adhesion, migration, proliferation, and inflammatory processes in melanoma cells. Our study highlights potential functional partners of RIPK4 such as BIRC3, TNF-α receptors, and MAP2K6. Data from RIPK4 knockout cells suggest a putative role for RIPK4 in modulating TNF-α-induced production of IL-8 and IL-6 through two distinct signaling pathways-BIRC3/NF-κB and p38/MAPK. Furthermore, increased serum TNF-α levels and the correlation of RIPK4 with NF-κB were revealed in melanoma patients.

CONCLUSION

These data reveal a complex role for RIPK4 in regulating the immune signaling network in melanoma cells and suggest that this kinase may represent an alternative target for melanoma-targeted adjuvant therapy.

Barriers to Treg therapy in Europe: From production to regulation

There has been an increased interest in cell based therapies for a range of medical conditions in the last decade. This explosion in novel therapeutics research has led to the development of legislation specifically focused on cell and gene based therapies. In Europe, the European medicines agency (EMA) designates any medicines for human use which are based on genes, tissues, or cells as advanced therapy medicinal products or advanced therapy medicinal products (ATMPs). In this article we discuss the hurdles to widespread adoption of ATMPs in Europe, with a focus on regulatory T cells (Tregs). There are numerous barriers which must be overcome before mainstream adoption of Treg therapy becomes a reality. The source of the cells, whether to use autologous or allogenic cells, and the methods through which they are isolated and expanded, must all meet strict good manufacturing practice (GMP) standards to allow use of the products in humans. GMP compliance is costly, with the equipment and reagents providing a significant cost barrier and requiring specialized facilities and personnel. Conforming to the regulations set centrally by the EMA is difficult, and the different interpretations of the regulations across the various member states further complicates the regulatory approval process. The end products then require a complex and robust distribution network to ensure timely delivery of potentially life saving treatments to patients. In a European market whose logistics networks have been hammered by COVID and Brexit, ensuring rapid and reliable delivery systems is a more complex task than ever. In this article we will examine the impact of these barriers on the development and adoption of Tregs in Europe, and potential approaches which could facilitate more widespread use of Tregs, instead of its current concentration in a few very specialized centers.

Exposure of Keratinocytes to Candida Albicans in the Context of Atopic Milieu Induces Changes in the Surface Glycosylation Pattern of Small Extracellular Vesicles to Enhance Their Propensity to Interact With Inhibitory Siglec Receptors

Candida albicans (C. albicans) infection is a potential complication in the individuals with atopic dermatitis (AD) and can affect clinical course of the disease. Here, using primary keratinocytes we determined that atopic milieu promotes changes in the interaction of small extracellular vesicles (sEVs) with dendritic cells and that this is further enhanced by the presence of C. albicans. sEV uptake is largely dependent on the expression of glycans on their surface; modelling of the protein interactions indicated that recognition of this pathogen through C. albicans-relevant pattern recognition receptors (PRRs) is linked to several glycosylation enzymes which may in turn affect the expression of sEV glycans. Here, significant changes in the surface glycosylation pattern, as determined by lectin array, could be observed in sEVs upon a combined exposure of keratinocytes to AD cytokines and C. albicans. This included enhanced expression of multiple types of glycans, for which several dendritic cell receptors could be proposed as binding partners. Blocking experiments showed predominant involvement of the inhibitory Siglec-7 and -9 receptors in the sEV-cell interaction and the engagement of sialic acid-containing carbohydrate moieties on the surface of sEVs. This pointed on ST6 β-Galactoside α-2,6-Sialyltransferase 1 (ST6GAL1) and Core 1 β,3-Galactosyltransferase 1 (C1GALT1) as potential enzymes involved in the process of remodelling of the sEV surface glycans upon C. albicans exposure. Our results suggest that, in combination with atopic dermatitis milieu, C. albicans promotes alterations in the glycosylation pattern of keratinocyte-derived sEVs to interact with inhibitory Siglecs on antigen presenting cells. Hence, a strategy aiming at this pathway to enhance antifungal responses and restrict pathogen spread could offer novel therapeutic options for skin candidiasis in AD.

Chloroacridine derivatives as potential anticancer agents which may act as tricarboxylic acid cycle enzyme inhibitors

PURPOSE

This paper concerns the cytotoxicity of 9-chloro-1-nitroacridine (1a) and 9-chloro-4-methyl-1-nitroacridine (1b) against two biologically different melanoma forms: melanotic and amelanotic. Melanomas are tumors characterized by high heterogeneity and poor susceptibility to chemotherapies. Among new analogs synthesized by us, compound 1b exhibited the highest anticancer potency. Because of that, in this study, we analyzed the mechanism of action for 1a and its 4-methylated derivative, 1b, against a pair of biological melanoma forms, with regard to proliferation, cell death mechanism and energetic state.

METHODS

Cytotoxicity was evaluated by XTT assay. Cell death was estimated by plasma membrane structure changes (phosphatidylserine externalization), caspase activation, and ROS presence. The energetic state of cells was estimated based on NAD and ATP levels, and the activity of tricarboxylic acid cycle enzymes (pyruvate dehydrogenase complex, aconitase, isocitrate dehydrogenase).

RESULTS

The chloroacridines affect biological forms of melanoma in different ways. Amelanotic (Ab) melanoma (with inhibited melanogenesis and higher malignancy) was particularly sensitive to the action of the chloroacridines. The Ab melanoma cells died through apoptosis and through death without caspase activation. Diminished activity of TAC enzymes was noticed among Ab melanoma cells together with ATP/NAD depletion, especially in the case of 1b.

CONCLUSION

Our data show that the biological forms of the tumors responded to 1a and its 4-methylated analog in different ways. 1a and 1b could be inducers of regulated melanoma cell death, especially the amelanotic form. Although the mechanism of the cell death is not fully understood, 1b may act by interfering with the TAC enzymes and blocking specific pathways leading to tumor growth. This could encourage further investigation of its anticancer activity, especially against the amelanotic form of melanoma.

A vector-enzymatic DNA fragment amplification-expression technology for construction of artificial, concatemeric DNA, RNA and proteins for novel biomaterials, biomedical and industrial applications

A DNA fragment amplification/expression technology for the production of new generation biomaterials for scientific, industrial and biomedical applications is described. The technology enables the formation of artificial Open Reading Frames (ORFs) encoding concatemeric RNAs and proteins. It recruits the Type IIS SapI restriction endonuclease (REase) for an assembling of DNA fragments in an ordered head-to-tail-orientation. The technology employs a vector-enzymatic system, dedicated to the expression of newly formed, concatemeric ORFs from strong promoters. Four vector series were constructed to suit specialised needs. As a proof of concept, a model amplification of a 7-amino acid (aa) epitope from the S protein of HBV virus was performed, resulting in 500 copies of the epitope-coding DNA segment, consecutively linked and expressed in Escherichia coli (E. coli). Furthermore, a peptide with potential pro-regenerative properties (derived from an angiopoietin-related growth factor) was designed. Its aa sequence was back-translated, codon usage optimized and synthesized as a continuous ORF 10-mer. The 10-mer was cloned into the amplification vector, enabling the N-terminal fusion and multiplication of the encoded protein with MalE signal sequence. The obtained genes were expressed, and the proteins were purified. Conclusively, we show that the proteins are neither cytotoxic nor immunogenic and they have a very low allergic potential.

Novel therapeutic compound acridine-retrotuftsin action on biological forms of melanoma and neuroblastoma

PURPOSE

As a continuation of our search for anticancer agents, we have synthesized a new acridine-retrotuftsin analog HClx9-[Arg(NO₂)-Pro-Lys-Thr-OCH₃]-1-nitroacridine (named ART) and have evaluated its activity against melanoma and neuroblastoma lines. Both tumors develop from cells (melanocytes, neurons) of neuroectodermal origin, and both are tumors with high heterogeneity and unsatisfactory susceptibility to chemotherapies. Thus, we analyzed the action of ART on pairs of biological forms of melanoma (amelanotic and melanotic) and neuroblastoma (dopaminergic and cholinergic) with regard to proliferation, mechanism of cell death, and effect on the activity of tricarboxylic acid cycle (TAC) enzymes.

METHODS

The cytotoxicity of ART was evaluated by XTT and trypan blue tests. Cell death was estimated by plasma membrane structure changes (phosphatidylserine and calreticulin externalization), caspase activation, presence of ROS (reactive oxygen species), activity of tricarboxylic acid cycle enzymes (pyruvate dehydrogenase complex, aconitase, and isocitrate dehydrogenase), NAD level, and ATP level.

RESULTS

ART influences the biological forms of melanoma and neuroblastoma in different ways. Amelanotic (Ab) melanoma (with the inhibited melanogenesis, higher malignancy) and SHSY5Y neuroblastoma (with cholinergic DC cells) were especially sensitive to ART action. The Ab melanoma cells died through apoptosis, while, with SH-SY5Y-DC neuroblastoma, the number of cells decreased but not as a result of apoptosis. With Ab melanoma and SH-SY5Y-DC cells, a diminished activity of TAC enzymes was noticed, along with ATP/NAD depletion.

CONCLUSION

Our data show that the biological forms of certain tumors responded in different ways to the action of ART. As a combination of retrotuftsin and acridine, the compound can be an inducer of apoptotic cell death of melanoma, especially the amelanotic form. Although the mechanism of the interrelationships between energy metabolism and cell death is not fully understood, interference of ART with TAC enzymes could encourage the further investigation of its anticancer action.