14 research outputs found
Thioalbamide, a thioamidated peptide from amycolatopsis alba, affects tumor growth and stemness by inducing metabolic dysfunction and oxidative stress
Thioalbamide, a thioamidated peptide biosynthesized by Amycolatopsis alba, is a thioviridamide-like molecule, and is part of a family of natural products representing a focus of biotechnological and pharmaceutical research in recent years due to their potent anti-proliferative and cytotoxic activities on malignant cells. Despite the high antitumor potential observed at nanomolar concentrations, the mechanisms underlying thioalbamide activity are still not known. In this work, the cellular effects induced by thioalbamide treatment on breast cancer cell lines were evaluated for the first time, highlighting the ability of this microbial natural peptide to induce mitochondrial dysfunction, oxidative stress, and apoptotic cell death. Furthermore, we demonstrate that thioalbamide can inhibit the propagation of cancer stem-like cells, which are strongly dependent on mitochondrial function and are responsible for chemotherapy resistance, metastasis, and tumor recurrence
Phytotoxic effect of bioactive compounds isolated from Myrcia tomentosa (Myrtaceae) leaves.
The aim of this study was to assess the phytotoxic potential of leaves of Myrcia tomentosa, as well as to isolate and identify the main bioactive compounds. The results for the coleoptile and phytotoxicity bioassays indicated the ethyl acetate extract for the phytochemistry study, owing to the high activity and the maintenance of the activity at lower
concentrations. This extract was chromatographed and subjected to 1H NMR and 13C NMR. Two major active compounds were isolated from the ethyl acetate extract of leaves of M. tomentosa: avicularin and juglanin. The fractions where these compounds were isolated showed potent inhibition of coleoptile growth. This paper is the first report on the presence of the flavonoids avicularin and juglanin in species of Myrtaceae from Neotropical savanna and provides a basis for future studies on the bioprospecting of M. tomentosa
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A canine mastocytoma with oncogenic c-kit activation by intra-exonic alternative splicing
We report a subcutaneous mastocytoma in a mid-aged Italian greyhound dog with a small 41 bp genomic deletion of the c-kit gene leading to skipping of the authentic 3′-splice junction of intron 10. The shift to an alternative splice junction in exon 11 leads to a mis-spliced in-frame mRNA transcript with a 27 bp deletion of exon 11 coding for 9 amino acids in the juxtamembrane negative regulatory domain of c-kit tyrosine kinase. In the tumor, c-kit was activated as revealed by more pronounced c-kit-regulated signaling by the PI3K/Akt and G-coupled receptor pathways. The same 9 amino acids deletion was reported in several human gastrointestinal stromal tumors (GIST) pointing to a remarkable similarity of c-kit activation by small deletions and aberrant splicing in humans and dogs, independent of exact sequence context, tumor type and location. Interestingly, the alternative splice junction in exon 11 has been conserved in Primates but less in other Orders with increased body temperature such as ruminants. We hypothesize that elevated body temperature has acted as evolutionary pressure to eliminate the alternative splice site at this hotspot. At a molecular level, hyperthermia may increase the frequency of small deletions in the c-kit gene by facilitating base slipping or hindering repair. An RT-qPCR assay was developed to detect c-kit alternative splicing in tumors and cell lines exposed to hyperthermia. The molecular mechanisms of tumorigenesis are discussed.
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