E.G. Zenit-Zhuravleva, A.A. Lushnikova, D.A. Ponkratova, I.V. Tsyganova, I.N. Mikhailova,
E.A. Cheremushkin, A.S. Vikhrova, E.M. Treschalina, L.V. Demidov, N.N. Mazurenko
N.N. Blokhin Russian Cancer Research Center, Kashirskoe shosse, 24, Moscow, Russian Federation, 115478

Introduction. The prevalence of human cutaneous melanoma (CM) in the world is constantly rising. Diagnostics and treatment of CM at the early stages allows to increase the 5-year patient survival up to 90%. This problem can be solved with personalized therapy targeted to the key signaling pathways and driver molecules, involving BRAF/NRAS/KRAS and such argyrophilic proteins with chaperone activity as nucleolin/C23 (encoded by NCL gene) and nucleophosmin/B23 (encoded by NPM gene). Objective. Analysis of NCL/NPM gene structure and the most common BRAF/NRAS/KRAS gene mutations in the clinically characterized samples of the metastatic CM and subcutaneous human CM xenograftsas , considered as a model for study of the mechanisms of carcinogenesis and effectiveness of targeted therapy , have been done. Methods. Some changes in NCL/NPM gene structure were determined by PCR for all gene exons and adjacent introns followed by conformation- sensitive electrophoresis and direct sequencing of PCR products. Mutations of BRAF/NRAS/KRAS genes were detected by PCR followed by direct sequencing of PCR products. 30 CM samples of different histological types, 2 human CM xenografts and 30 donor DNA samples (control group) were analyzed. Results. A number of structural alterations for NPM/NCL genes encoding the main argyrophilic proteins nucleophosmin/B23 and nucleolin/ C23 were found. Some of the alterations were revealed in several exons and adjacent introns of NCL/NPM genes. Some combinations of the changes and polymorphic variant in exon 3 of NCL gene were specific for CM and were absent in normal tissue (control group of donors). The complex genetic alterations affecting NCL/NPM, BRAF/NRAS/KRAS genes (and alleged loci), might create genetic instability and molecular heterogeneity of CM that generate tumor aggressiveness and treatment inefficiency. A possible mechanisms for activation of the key signaling pathways, including described oncogenes and proteins have been discussed. Conclusion. A complex genomic alterations in metastatic CM of different histological types were found and characterized. This may be important for mechanisms of CM induction and progression, and for prospective creation of targeted drugs with wide spectrum of the action.
metastatic cutaneous melanoma, nucleolin/C23, nucleophosmin/B23, cellular oncogenes, signaling pathways, targeted therapy