Onconase (ONC) is an amphibian secretory ribonuclease displaying cytostatic and cytotoxic activities against many mammalian tumors, including melanoma. ONC principally damages tRNA species, but also other non-coding RNAs, although its precise targets are not known. We investigated the ONC ability to modulate the expression of 16 onco-suppressor microRNAs (miRNAs) in the A375 BRAF-mutated melanoma cell line. RT-PCR and immunoblots were used to measure the expression levels of miRNAs and their regulated proteins, respectively. In silico study was carried out to verify the relations between miRNAs and their mRNA targets. A375 cell transfection with miR-20a-3p and miR-34a-5p mimics or inhibitors was performed. The onco-suppressors miR-20a-3p, miR-29a-3p and miR-34a-5p were highly expressed in 48-h ONC-treated A375 cells. The cytostatic effect of ONC in A375 cells was mechanistically explained by the sharp inhibition of cyclins D1 and A2 expression level, as well as by downregulation of retinoblastoma protein and cyclin-dependent-kinase-2 activities. Remarkably, the expression of kinases ERK1/2 and Akt, as well as of the hypoxia inducible factor-1α, was inhibited by ONC. All these proteins control pro-survival pathways. Finally, many crucial proteins involved in migration, invasion and metastatic potential were downregulated by ONC. Results obtained from transfection of miR-20a-3p and miR-34a-5p inhibitors in the presence of ONC show that these miRNAs may participate in the antitumor effects of ONC in the A375 cell line. In conclusion, we identified many intracellular downregulated proteins involved in melanoma cell proliferation, metabolism and progression. All mRNAs coding these proteins may be targets of miR-20a-3p, miR-29a-3p and/or miR-34a-5p, which are in turn upregulated by ONC. Data suggest that several known ONC anti-proliferative and anti-metastatic activities in A375 melanoma cells might depend on the upregulation of onco-suppressor miRNAs. Notably, miRNAs stability depends on the upstream regulation by long-non-coding-RNAs or circular-RNAs that can, in turn, be damaged by ONC ribonucleolytic activity.

The long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been implicated in melanoma. Polymorphisms in MALAT1 may play a vital role in the progress of melanoma by its regulative function. However, potential genetic variants in MALAT1 affecting the risk of melanoma onset have not been explored. In this study, two single nucleotide polymorphisms (rs3200401 and rs619586) in MALAT1 were selected for genotyping of 334 melanoma patients and 291 cancer-free controls in an Italian population. The results showed that MALAT1 rs3200401 and rs619586 were not associated with melanoma risk. A further breakdown analysis by sex stratification also indicated a lack of association between these polymorphisms and melanoma. In addition, we tested 450 bp of the proximal 5´ flanking region of the gene for the presence of polymorphisms that could be associated with melanoma risk and found no variants in 96 melanoma patients. In conclusion, our results suggest that there is no contribution of MALAT1 rs3200401 and rs619586 polymorphisms or polymorphisms in the core promoter that could be associated with the risk of melanoma skin cancer in this specific study setting. Further validation will be required in larger studies involving different settings/larger populations in order to reach conclusive results.

Multiple sclerosis (MS) is a complex immune-mediated disease of the CNS showing remarkable pathological and clinical heterogeneity among cases. In a personalized medicine era, there is an unmet need of biomarkers for MS that could distinct disease subtypes and predict the clinical course at the individual patient level early after onset. MicroRNAs are small non-coding RNAs that regulate the expression of genes at post-transcriptional level by targeting messenger RNA for translational repression or degradation. 1 Altered expression of microRNAs has been observed in a number of pathological conditions, including MS, suggesting a key role in immune system regulation, differentiation of T and B cells, proliferation of monocytes and neutrophils, and expression of cytokines and chemokines. 2 Circulating microRNAs are present in several body fluids, including serum, where they are exceptionally stable, making them potential candidates for clinical application in MS. Levels of various circulating microRNAs were found to be associated to MS diagnosis, clinical subtypes, disease severity, and disability progression. 3-9 Aim of this study was to investigate the association between candidate microRNA expression in serum samples of patients with MS and the disease course.

Hyperforin (HPF), the main component responsible for the antidepressant action of Hypericum perforatum, displays additional beneficial properties including anti-inflammatory, antimicrobic, and antitumor activities. Among its antitumor effects, HPF activity on melanoma is poorly documented. Melanoma, especially BRAF-mutated melanoma, is still a high-mortality tumor type and the currently available therapies do not provide solutions. We investigated HPF’s antimelanoma effectiveness in A375, FO1 and SK-Mel-28 human BRAF-mutated cell lines. Cell viability assays documented that all melanoma cells were affected by low HPF concentrations (EC50% 2–4 µM) in a time-dependent manner. A Br-deoxy-uridine incorporation assay attested a significant reduction of cell proliferation accompanied by decreased expression of cyclin D1 and A2, CDK4 and of the Rb protein phosphorylation, as assessed by immunoblots. In addition, the expression of P21/waf1 and the activated form of P53 were increased in A375 and SK-Mel-28 cells. Furthermore, HPF exerts cytotoxic effects. Apoptosis is induced 24 h after HPF administration, documented by an increase of cleaved-PARP1 and a decrease of both Bcl2 and Bcl-xL expression levels. Autophagy is induced, attested by an augmented LC3B expression and augmentation of the activated form of AMPK. Moreover, HPF lowers GPX4 enzyme expression, suggesting ferroptosis induction. HPF has been reported to activate the TRPC6 Ca++ channel and/or Ca++ and Zn++ release from mitochondria stores, increasing cytosolic Ca++ and Zn++ concentrations. Our data highlighted that HPF affects many cell-signaling pathways, including signaling induced by Ca++, such as FRA1, pcJun and pCREB, the expression or activity of which are increased shortly after treatment. However, the blockage of the TRPC6 Ca++ channel or the use of Ca++ and Zn++ chelators do not hinder HPF cytostatic/cytotoxic activity, suggesting that damages induced in melanoma cells may pass through other pathways. Remarkably, 24 h after HPF treatment, the expression of activated forms of the transcription factors NF-κB P65 subunit and STAT3 are significantly lowered. Several cytosolic (PGM2, LDHA and pPKM2) and mitochondrial (UQCRC1, COX4 and ATP5B) enzymes are downregulated by HPF treatment, suggesting a generalized reduction of vital functions in melanoma cells. In line with these results is the recognized ability of HPF to affect mitochondrial membrane potential by acting as a protonophore. Finally, HPF can hinder both melanoma cell migration and colony formation in soft agar. In conclusion, we provide evidence of the pleiotropic antitumor effects induced by HPF in melanoma cells.

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