783 ISSN 1068-1620, Russian Journal of Bioorganic Chemistry, 2019, Vol. 45, No. 6, pp. 783–792. © Pleiades Publishing, Ltd., 2019. Tumor Specific Peptides Selected for Targeted Delivery of Therapeutic Agents to Glioma Human Cells A. A. Voitova a , M. D. Dmitrieva a , M. A. Dymova a, 1 , N. S. Vasileva a , A. A. Nushtaeva a , V. A. Richter a , and E. V. Kuligina a a Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk, 630090 Russia Received June 24, 2019; revised July 25, 2019; accepted July 26, 2019 Abstract—Brain tumors are among the most intractable types of malignant neoplasms. Despite advances in the treatment of cancer, in particular, the development of new approaches in surgery, radiotherapy and che- motherapy, the incidence remains high with a low 5-year survival rate. Targeted therapy (TT) may be a solu- tion to the problem of low efficacy of the applied cancer treatment methods. TT is based on the use of drugs that specifically affect specific types of tumors, which allows one to increase the effectiveness of treatment and minimize toxic effects on healthy tissues of the body. The combination of the unique properties of cancer cells allows one to find specific ligands that interact directly with the tumor, and to conduct TT for malignant tumors. Phage display technology is one of the promising approaches to the search for tissue- and/or organ- specific molecules [1]. Combinatorial phage peptide libraries make it possible to obtain highly specific pep- tides, including for various types of tumors. Currently, such tumor-targeting peptides are considered as means of targeted delivery of therapeutic genes, cytokines, imaging agents, pro-apoptotic peptides, and cytotoxic drugs. The purpose of this work was to obtain from the phage peptide library of bacteriophages exposing pep- tides, which ensure the accumulation of phage particles in human glioblastoma cells U-87 MG, and to assess the specificity of the selected peptides for cells of the primary cultures of human gliomas. During the research, the following tasks were solved: (1) Tumor-targeting peptides were selected using human glioblastoma cells U-87 MG in vitro and on a U-87 MG tumor in a xenograft model in vivo; amino acid sequences of selected peptides (SWTFGVQFALQH (26), HPSSGSA (92), PVSNKMS (83)) were determined; (2) primary cul- tures of human gliomas AS2, MG1, MG2, MG3, MG4 cells were obtained and characterized; (3) specificity of the binding of bacteriophages exposing selected tumor-targeting peptides to cells of primary cultures of human gliomas was evaluated using immunocytochemical analysis. The specific binding of selected tumor- targeting peptides with cells of the primary cultures AS2, MG1 was shown. Keywords: phage display, tumor-specific peptides, astrocytoma, glioblastoma, immunocytochemical analysis DOI: 10.1134/S1068162019060384 INTRODUCTION Based on estimates from the World Health Organization (WHO), cancer is the second leading cause of death before age 70 years in developed coun- tries [2]. Brain tumors are among the most intractable types of cancer [3]. Glioblastoma multiforme accounts for approximately 70% of malignant gliomas; anaplastic astrocytoma is a rare type of brain tumor (15%); the remaining cases represent less aggressive gliomas. Despite advances in the treatment of cancer, in particular, the development of new approaches in surgery, radiotherapy and chemotherapy, the inci- dence remains high with a low 5-year survival rate. This occurs due to infiltrative growth into the normal brain and location in the eloquent areas of the brain, which makes total surgical resection of these tumors extremely difficult. The creation of drugs targeting the cells of glioblastoma is one of the most challenging in modern neurooncology. Active research into the molecular profile of tumor cells facilitates and drives the development of targeted therapy (TT). The primary cultures of tumor cells directly from patient-derived tumor tissue have been increasingly frequently used in cancer research as an in vitro model of tumor. Primary cultures most precisely reproduce the molecular and genetic profile of the tumor, as well as the in vivo physiology of tumor cells, and hence they can predict the tumor response to therapy and facilitate selection of combined treatment for a particular patient [4]. Currently, short peptides hold promise as tumor-specific agents [5]. Such pep- Abbreviations: ТТ, targeted therapy; WHO, World health orga- nization; PFU, plaque forming unit; PBS, phosphate buffer saline; BSA, bovine serum albumin; PBST, phosphate buffer saline with Tween 20; IPTG, isopropyl β-D-1-thiogalactopyra- noside; PEG, polyethylene glycol; ssDNA, single-strand deoxy- ribonucleic acid; DMEM/RPMI, culture medium (Dulbecco’s Modified Eagle Media/Roswell Park Memorial Institute); FBS, fetal bovine serum. 1 Corresponding author: phone: +7 (913) 476-40-12; e-mail: maya.a.rot@gmail.com.