Chronometric Administration of Cyclophosphamide and a Double-Stranded DNA-Mix at Interstrand Crosslinks Repair Timing, Called "Karanahan" Therapy, Is Highly Efficient in a Weakly Immunogenic Lewis Carcinoma Model

Background and Aims: A new technology based on the chronometric administration of cyclophosphamide and complex composite double-stranded DNA-based compound, which is scheduled in strict dependence on interstrand crosslinks repair timing, and named “Karanahan”, has been developed. Being applied, this technology results in the eradication of tumor-initiating stem cells and full-scale apoptosis of committed tumor cells. In the present study, the efficacy of this novel approach has been estimated in the model of Lewis carcinoma.

Methods: To determine the basic indicative parameters for the approach, the duration of DNA repair in tumor cells, as well as their distribution along the cell cycle, have been assessed. Injections were done into one or both tumors in femoral region of the engrafted mice in accordance with the developed regimen. Four series of experiments were carried out at different periods of time. The content of poorly differentiated CD34⁺/TAMRA+ cells in the bone marrow and peripheral blood has been determined. Immunostaining followed by the flow cytometry was used to analyze the subpopulations of immune cells.

Results: The high antitumor efficacy of the new technology against the developed experimental Lewis carcinoma was shown. It was found that the therapy efficacy depended on the number of tumor growth sites, seasonal and annual peculiarities. In some experiments, a long-term remission has been reached in 70% of animals with a single tumor and in 60% with two tumors. In mice with two developed grafts, mobilization capabilities of both poorly differentiated hematopoietic cells of the host and tumor stem-like cells decrease significantly. Being applied, this new technology was shown to activate a specific immune response. There is an increase in the number of NK cell populations in the blood, tumor, and spleen, killer T cells and T helper cells in the tumor and spleen, CD11b+Ly-6C+ and CD11b+Ly-6G+ cells in the tumor. A population of mature dendritic cells is found in the tumor.

Conclusion: The performed experiments indicate the efficacy of the Karanahan approach against incurable Lewis carcinoma. Thus, the discussed therapy is a new approach for treating experimental neoplasms, which has a potential as a personalized anti-tumor therapeutic approach in humans.

Cancer Stem Cells: Emergent Nature of Tumor Emergency

A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of "generalized cellular stress," which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of "committed" tumor cells.

Evaluation of a strategy for tumor-initiating stem cell eradication in primary human glioblastoma cultures as a model

Primary cultures of human glioblastoma were obtained from the surgical material of patients K. (female, 61 years, Ds: relapse of glioblastoma) and Zh. (female, 60 years, Ds: relapse of glioblastoma). The effectiveness of a new therapeutic approach aimed at destroying the cancer cell community was evaluated on the primary cell lines of human glioblastoma culture by employing a new strategy of tumor-initiating stem cell synchronization and a domestic strategy of their eradication "3+1". The key elements of the strategy were the following indicator results: (1) evaluation of the presence of tumor-initiating stem cells in a population of cells from analyzed cultures by their ability to internalize double-stranded labeled DNA (TAMRA+ cells); (2) determination of the reference time points of the repair cycle of DNA interstrand cross-links induced by cross-linking cytostatic mitomycin C; (3) evaluation of cell cycle synchronization; (4) determination of the time (day after therapy initiation) when TAMRA+ cells were synchronously present in phase G1/S of the cell cycle, sensitive to the therapy; and (5) establishment of the TAMRA+ (tumor-initiating stem cells) eradication schedule. The cultures were treated with cross-linking cytostatic mitomycin C and a compositional DNA preparation. After the treatments, cell division slows down, and the cultures degrade. The K cell line completely degraded within 30 days of observation. The cell number of the Zh culture fell to nearly one-third of the starting value by day 15 of observation. On day 15, this indicator constituted 1/7.45 for mitomycin C and 1/10.28 for mitomycin C + DNA with reference to the control. The main target of the mitomycin C + DNA regimen was TAMRA+ tumor-initiating stem cells of the glioblastoma cell populations. The action of mitomycin C alone or in the combination with DNA demonstrated effective elimination of TAMRA+ tumor-initiating stem cells and the whole primary cultures of human glioblastomas.