Aberrant regulation of WNT/β-catenin signaling has a crucial role in the onset and progression of cancers, where the effects are not always predictable depending on tumor context. In melanoma, for example, models of the disease predict differing effects of the WNT/β-catenin pathway on metastatic progression. Understanding the processes that underpin the highly context-dependent nature of WNT/β-catenin signaling in tumors is essential to achieve maximal therapeutic benefit from WNT inhibitory compounds. In this study, we have found that expression of the tumor suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), alters the invasive potential of melanoma cells in response to WNT/β-catenin signaling, correlating with differing metabolic profiles. This alters the bioenergetic potential and mitochondrial activity of melanoma cells, triggered through regulation of pro-survival autophagy. Thus, WNT/β-catenin signaling is a regulator of catabolic processes in cancer cells, which varies depending on the metabolic requirements of tumors.

Monocytes may contribute to tumor progression in part by mediating tumor-induced immunosuppression. Alterations to the monocyte populations and functions in untreated late stage melanoma patients are not fully understood. To characterize these alterations, we compared the frequency, phenotype, and functional capacity of peripheral blood monocytes and other myeloid cells in untreated, newly diagnosed stage IV melanoma patients (n= 18) to those in healthy volunteers. Stage IV untreated melanoma patients exhibited a sizeable decrease in the percentage of monocytes (p<0.0001) that included a drop in the percentage of CD14+CD16− classical monocytes pool (p=0.006). Although there was not a significant difference in the CD14+HLA-DRlow/− monocyte population between the melanoma patients and the healthy volunteers, the HLA-DR levels were considerably lower in the patients’ CD14+CD16+ intermediate (p<0.0001) and CD14lowCD16+ non-classical monocytes populations (p=0.001). Decreased surface expression of CD86 (p=0.0006) and TNFRII (p=0.0001), and increased expression of tissue factor and PD-L1 (p=0.003) were identified on monocytes from melanoma patients. Furthermore, these monocytes had decreased ability to up-regulate CD80 expression and cytokine production following stimulation with agonist of toll-like receptor 3 (TLR3). Peripheral blood dendritic cell subsets were decreased in untreated stage IV melanoma patients. Our study demonstrates that untreated late stage melanoma patients exhibit monocytopenia in addition to phenotypic and functional deficiencies that may negatively affect the patient’s immune function. These findings open new avenues into examining the role of monocyte populations in melanoma development.

After spinal cord injury (SCI), nerve regeneration is severely hampered due to the establishment of a highly inhibitory microenvironment at the injury site, through the contribution of multiple factors. The potential of antisense oligonucleotides (AONs) to modify gene expression at different levels, allowing the regulation of cell survival and cell function, together with the availability of chemically modified nucleic acids with favorable biopharmaceutical properties, make AONs an attractive tool for novel SCI therapy developments. In this work, we explored the potential of locked nucleic acid (LNA)-modified AON gapmers in combination with a fibrin hydrogel bridging material to induce gene silencing in situ at a SCI lesion site. LNA gapmers were effectively developed against two promising gene targets aiming at enhancing axonal regeneration—RhoA and GSK3β. The fibrin-matrix-assisted AON delivery system mediated potent RNA knockdown in vitro in a dorsal root ganglion explant culture system and in vivo at a SCI lesion site, achieving around 75% downregulation 5 days after hydrogel injection. Our results show that local implantation of a AON-gapmer-loaded hydrogel matrix mediated efficient gene silencing in the lesioned spinal cord and is an innovative platform that can potentially combine gene regulation with regenerative permissive substrates aiming at SCI therapeutics and nerve regeneration.