Introduction: Breast cancer (BC) diagnostics lack noninvasive methods and procedures for screening and monitoring disease dynamics. Admitted CellSearch® is used for fluid biopsy and capture of circulating tumor cells of only epithelial origin. Here we describe an RNA aptamer (MDA231) for detecting BC cells in clinical samples, including blood. The MDA231 aptamer was originally selected against triple-negative breast cancer cell line MDA-MB-231 using cell-SELEX.Methods: The aptamer structure in solution was predicted using mFold program and molecular dynamic simulations. The affinity and specificity of the evolved aptamers were evaluated by flow cytometry and laser scanning microscopy on clinical tissues from breast cancer patients. CTCs were isolated form the patients’ blood using the developed method of aptamer-based magnetic separation. Breast cancer origin of CTCs was confirmed by cytological, RT-qPCR and Immunocytochemical analyses.Results: MDA231 can specifically recognize breast cancer cells in surgically resected tissues from patients with different molecular subtypes: triple-negative, Luminal A, and Luminal B, but not in benign tumors, lung cancer, glial tumor and healthy epithelial from lungs and breast. This RNA aptamer can identify cancer cells in complex cellular environments, including tumor biopsies (e.g., tumor tissues vs. margins) and clinical blood samples (e.g., circulating tumor cells). Breast cancer origin of the aptamer-based magnetically separated CTCs has been proved by immunocytochemistry and mammaglobin mRNA expression.Discussion: We suggest a simple, minimally-invasive breast cancer diagnostic method based on non-epithelial MDA231 aptamer-specific magnetic isolation of circulating tumor cells. Isolated cells are intact and can be utilized for molecular diagnostics purposes.
Currently, no molecular biological markers do exist for early diagnosis of breast cancer. One of the possible candidates for the marker of early breast cancer is mammaglobin (MGB1) or SCGB2A2 (secretoglobin, family 2A, member 2), characterized by the maximal expression level in early breast cancer. Using the RT-PCR method MGB1 mRNA expression was examined in 57 tumor tissue samples and 57 samples of morphologically non-malignant tissue (MNT) of breast cancer (BC) patients. Specificity and sensitivity of the MGB1 mRNA assay in peripheral blood of BC patients was evaluated by nested PCR. 169 blood samples (from 95 BC patients, 22 from patients with benign breast tumors, 28 from patients with tumors of other localizations, and 24 samples from healthy donors) have been analyzed. MGB1 expression was significantly higher in BC tissue samples compared to MNT (p=0.0019). The maximal expression level was in the samples T1 (p=0.013), stage I BC (p=0.037), GI (p=0.0019). The MGB1 expression positively correlated with expression of estrogen (p = 0,034) and progesterone (p=0.0004) receptors. Sensitivity and specificity of the MGB1 mRNA assay in peripheral blood were 60.6% and 92.3%, respectively. Expression of MGB1 was higher in BC than MNT and it decreased during BC progression. The sensitivity and specificity of the MGB1 mRNA assay may be used as an additional diagnostic method.
e13545 Background: MM-D37K is a synthetic peptide which consists of p16INK4a-specific inhibitor of complex cyclin D- CDK4 and CDK6 and cell penetrating peptide (CPP) – Antp (Penetratin). We investigated in vitro and in vivo cytotoxic, cytostatic and antitumor activity of MM-D37K. The level of cyclin A, Ki67,bax, bcl-2 and pRb phosphorylation was investigated. Full range of Toxicology tests and Pharmacokinetics experiments in mice, rats and rabbits were performed. Methods: Different cell lines (Jurcat, Raji, A549, MCF-7, Hct-116, Ht-29, HEK293) were incubated with 0.1-100 mM MM-D37K for 24-48 hrs. Proliferation (MTT), DNA-content, cell cycle (flow cytometry) and mRNA level of appropriate proteins (RT PCR) were investigated. In vivo experiments were conducted on xenograft model of HCT116, A-549 at concentration 5 and 10 mg/kg of MM-D37K. Toxicology experiments were made under RF Law and included 3 types of animals. LC-MS MMD37K method of detection in plasma was developed. Results: MM-D37K prevented pRb phosphorilation and proliferation activation in all investigated cell lines. Cell cycle was blocked in G1 phase. Cytostatic effect did not depend on p16 mutation or expression. MM-D37K induced apoptosis in 20-82% of investigated cells at 40 mM with lowest level for MCF-7. LD10 for rats was 100 mg/kg and no deaths were registered for rabbits (highest dose was 50 mg/kg). Concentration of MMD-37K in plasma after 2 min and bolus i.v. injection in dose 10 mg/kg was 72.16±5.64 mcg/ml. Concentration decreased in two phases. 1st – t1/2 = 2.39±0.39 min and for 2nd t1/2=2.39±0.39 hr. Antitumor effects in xenograft model were 53% for A-549 and 67% for HCT116. Conclusions: Our results proved cytotoxic, cytostatic and antitumor effects of MM-D37K in investigated cell lines in vitro and in vivo. Toxicological and pharmacokinetics results allow us recommend for I/IIa Phase clinical trial. (Support: MetaMax Ltd., RFFI, Minpromtorg RF.)
The goal of this work is the development of novel peptides with high efficacy of inhibiting activity of CDK6/CyclinD complex. The peptides were derived from primary sequence of P16 protein and its homologues. The interactions between CDK6 and P16/INK4a-derived peptides are studied with molecular dynamics simulation employing umbrella sampling method. The SASA implicit solvent model was used for simulation, which was accelerated using NVIDIA GPUs.
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