The crystal structure of the domain-swapped dimer of onconase highlights some catalytic and antitumor activity features of the enzyme

Gotte, Giovanni; Campagnari, Rachele; Loreto, Domenico; Bettin, Ilaria; Calzetti, Federica; Menegazzi, Marta; Merlino, Antonello

doi:10.1016/j.ijbiomac.2021.09.095

Cited by 8 publications

(14 citation statements)

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“…Recent studies revealed that HIF1α can be induced by different signaling pathways, such as PI3K/Akt/mTOR, RAS/RAF/MEK/ERK, JAK/STAT, and NF-κB pathways controlling melanoma tumor growth, metabolism, motility, and apoptosis evasion [70]. Previously, we showed that ONC decreases expression and activity of both NF-κB [17,25] and STAT3 [12] in A375 melanoma cells. In the present study, we registered the ONC ability to lower Akt expression and phosphorylation levels, as well as the total protein expression of the kinases ERK1/2 (Figure 2).…”

Section: Discussionmentioning

confidence: 88%

“…SOX2, whose expression is decreased by ONC (Figure 3), is also involved in the resistance to BRAF inhibitors therapy in a proto-oncogene tyrosine-protein kinase Src (Src)-and STAT3dependent manner [79]. We previously reported a downregulation of STAT3 together with its upstream kinase Src in ONC-treated A375 cells [12]. The restoration of miR-34a in triple-negative breast cancer cell lines inhibited proliferation and invasion by targeting the proto-oncogene Src [80].…”

Section: Discussionmentioning

confidence: 99%

“…Actually, in a A375 subpopulation of cells characterized with acquired resistance to the BRAF-inhibitor dabrafenib, we showed that ONC incubation increases apoptosis, while it decreases colony formation in soft agar, and cell-invasion capability at a higher extent with respect to parental A375 cells [17]. We also registered the ONC ability to hinder expression and activity of nuclear factor-κappa-B (NF-κB) [17,25], as well as of signal transducer and activator of transcription (STAT)-3 [12]. In the present work, we investigate how other intracellular targets are affected by ONC in the A375 cell line that is characterized by the BRAF V600E mutation.…”

Section: Introductionmentioning

confidence: 95%

“…This depends on the presence on the ONC surface of many positive charges, which can better interact with cancer cells that are in turn characterized by more negative charged membranes than normal cells [10]. In addition, the enzyme exhibits high conformational stability [11], very low protease responsiveness [12], and ability to evade the inactivating intracellular ribonuclease inhibitor [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, target therapy with BRAF-inhibitors or MEK-inhibitors does not exclude recurrence of the malignancy and the incoming of therapy resistance [24]. Recently, we reported a significant anti-melanoma activity exerted by low micromolar ONC concentrations in both A375 and MeWo human malignant melanoma cell lines [12,17,25]. In addition, ONC enhanced its antitumor efficacy in cells pre-treated with other drugs.…”

Section: Introductionmentioning

confidence: 99%

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Upregulation of miR-34a-5p, miR-20a-3p and miR-29a-3p by Onconase in A375 Melanoma Cells Correlates with the Downregulation of Specific Onco-Proteins

Tomi

Campagnari

et al. 2022

IJMS

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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.

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