In last decades the role of non-canonical DNA structures as switching on/off mechanism of gene transcription has been extensively investigated. In particular, downregulation of gene expression by induction of G-quadruplex DNA structures at promotorial level is an attractive anticancer strategy. In humans, two guanine-rich sequences (h_kit1 and h_kit2) were identified in the promotorial region of the proto-oncogene KIT. Their stabilization into G-quadruplex structures can find applications in the treatment of leukemias, mastocytosis, gastrointestinal stromal tumor, lung carcinomas, which are often associated to c-kit mis-regulation. Here we screeneed libraries of G-quadruplex binders to identify novel hits highly selective for the G-quadruplexes of KIT promoter. To provide the biological rationale for the molecular and cellular mechanisms of action of this novel therapeutic approach, a full characterization of target selectivity, DNA complex formation and cellular effects has been performed. To ultimately provide the required knowledge to convert the identified hits into new species-specific targeted drugs, we searched for a robust translational model too. Interestingly, the most common skin cancer in domestic dog, mast cell tumor, is also linked to a mutation and/or to an over-expression of c-kit. Moreover, a general conserved promotorial sequence between the two species has been confirmed, thus supporting dog as an excellent animal model. In particular, the conformational features of the canine kit1 sequence are substantially shared with the human one. Conversely, two isoforms of the kit2 sequences were identified and, in comparison with the human counterpart, both of them showed an altered distribution among several folded conformations. Here we compared our results on human and canine cells, in order to provide a more comprehensive description of the physiological pathways supported by c-kit mis-regulation in carcinogenesis and to highlight the similarities/differences between the two species.

G-rich sequences within proto-oncogene KIT promoter region as targets for anticancer therapy.

SISSI, CLAUDIA;DA ROS, SILVIA;ZORZAN, ELEONORA;PALUMBO, MANLIO;GIANTIN, MERY;DACASTO, MAURO
2015

Abstract

In last decades the role of non-canonical DNA structures as switching on/off mechanism of gene transcription has been extensively investigated. In particular, downregulation of gene expression by induction of G-quadruplex DNA structures at promotorial level is an attractive anticancer strategy. In humans, two guanine-rich sequences (h_kit1 and h_kit2) were identified in the promotorial region of the proto-oncogene KIT. Their stabilization into G-quadruplex structures can find applications in the treatment of leukemias, mastocytosis, gastrointestinal stromal tumor, lung carcinomas, which are often associated to c-kit mis-regulation. Here we screeneed libraries of G-quadruplex binders to identify novel hits highly selective for the G-quadruplexes of KIT promoter. To provide the biological rationale for the molecular and cellular mechanisms of action of this novel therapeutic approach, a full characterization of target selectivity, DNA complex formation and cellular effects has been performed. To ultimately provide the required knowledge to convert the identified hits into new species-specific targeted drugs, we searched for a robust translational model too. Interestingly, the most common skin cancer in domestic dog, mast cell tumor, is also linked to a mutation and/or to an over-expression of c-kit. Moreover, a general conserved promotorial sequence between the two species has been confirmed, thus supporting dog as an excellent animal model. In particular, the conformational features of the canine kit1 sequence are substantially shared with the human one. Conversely, two isoforms of the kit2 sequences were identified and, in comparison with the human counterpart, both of them showed an altered distribution among several folded conformations. Here we compared our results on human and canine cells, in order to provide a more comprehensive description of the physiological pathways supported by c-kit mis-regulation in carcinogenesis and to highlight the similarities/differences between the two species.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11577/3171546
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