The activation of Src kinase in cells is strictly controlled by intramolecular inhibitory interactions mediated by SH3 and SH2 domains. They impose structural constraints on the kinase domain holding it in a catalytically non-permissive state. The transition between inactive and active conformation is known to be largely regulated by the phosphorylation state of key tyrosines 416 and 527. Here, we identified that phosphorylation of tyrosine 90 reduces binding affinity of the SH3 domain to its interacting partners, opens the Src structure, and renders Src catalytically active. This is accompanied by an increased affinity to the plasma membrane, decreased membrane motility, and slower diffusion from focal adhesions. Phosphorylation of tyrosine 90 controlling SH3-medited intramolecular inhibitory interaction, analogical to tyrosine 527 regulating SH2-C-terminus bond, enables SH3 and SH2 domains to serve as cooperative but independent regulatory elements. This mechanism allows Src to adopt several distinct conformations of varying catalytic activities and interacting properties, enabling it to operate not as a simple switch but as a tunable regulator functioning as a signalling hub in a variety of cellular processes.

• Klíčová slova
• SH3 domain, Src, biochemistry, cell biology, cell transformation, chemical biology, invasiveness, mouse, phosphorylation, protein structure,
• MeSH
• fosforylace MeSH
• skupina kinas odvozených od src-genu * metabolismus   MeSH
• src homologní domény * MeSH
• tyrosin metabolismus   MeSH
• tyrosinkinasy metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• skupina kinas odvozených od src-genu * MeSH
• tyrosin MeSH
• tyrosinkinasy MeSH

Despite remarkable progress in cancer-drug discovery, the delivery of novel, safe, and sustainably effective products to the clinic has stalled. Using Src as a model, we examine key steps in drug development. The preclinical evidence on the relationship between Src and solid cancer is in sharp contrast with the modest anticancer effect noted in conventional clinical trials. Here, we consider Src inhibitors as an example of a promising drug class directed to invasion and metastasis and identify roadblocks in translation. We question the assumption that a drug-induced tumor shrinkage in preclinical and clinical studies predicts a successful outcome. Our analysis indicates that the key areas requiring attention are related, and include preclinical models (in vitro and mouse models), meaningful clinical trial end points, and an appreciation of the role of metastasis in morbidity and mortality. Current regulations do not reflect the natural history of the disease, and may be unrelated to the key complications: local invasion, metastasis, and the development of resistance. Alignment of preclinical and clinical studies and regulations based on mechanistic trial end points and platforms may help in overcoming these roadblocks. Viewed kaleidoscopically, most elements necessary and sufficient for a novel translational paradigm are in place.

• Klíčová slova
• Src inhibitors, cancer, drug resistance, metastasis, paradigms, translation,
• Publikační typ
• časopisecké články MeSH

We have examined the chicken TP53 tumor suppressor gene in v-src-transformed chicken tumor cells by reverse transcriptase-polymerase chain reaction and deoxyribonucleic acid (DNA) sequencing. Initially, we have detected frequent deletions of variable length in both DNA-binding and oligomerization domains of the TP53 in late as well as early in vitro passages of the chicken tumor cell line PR9692. This tumor cell line shows an immortal phenotype and acquires a metastatic potential that is unique in our experimental model of v-src-induced tumors in congenic chickens. Deletions in TP53 were also detected in an early passage of parallel in vivo subculture of the original v-src-induced tumor. In this case, tumor cells underwent replicative senescence later in tissue culture. Our results suggest that extensive deletions are efficient mechanisms of TP53 inactivation, occurring as early events during the immortalization of v-src-transformed chicken cells. Tumor cells with altered TP53 might, however, still be susceptible to growth control mechanisms, leading to withdrawal from the mitotic cycle in the early stage of the tumor lifeline.

• MeSH
• geny p53 * MeSH
• geny src * MeSH
• kur domácí genetika   MeSH
• metastázy nádorů MeSH
• molekulární sekvence - údaje MeSH
• nádorová transformace buněk * MeSH
• nádorové buněčné linie MeSH
• sekvence nukleotidů MeSH
• sekvenční seřazení MeSH
• transformované buněčné linie MeSH
• umlčování genů MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH