Ejc Supplements最新文献

The efficiency of endocrine therapy for tumors is limited by the development of hormone resistance and progression of tumor cells to hormone-independent phenotype. Among these tumors – breast cancers, for which hormone therapy is one of the most common and effective methods of treatment, but only in cases, when the tumors retain their hormonal dependence. The mechanism of hormonal independence was found to be based on the fundamental properties of cancer cell including both downregulation of specific hormone receptors, and affecting of intracellular signalling, particularly – estrogen-independent growth signaling pathways. However, the role of the intercellular interactions in the progression of hormonal resistance is still unclear.

We hypothesize, that the formation of the clone of the hormone-resistant cells in the tumor, and the subsequent common growth of the hormone-resistant and sensitive cells may lead to spread the hormonal resistance to the sensitive cells – as a result of the secretion of the specific factors acting in the paracrine manner or via the direct cell–cell contacts. Here, using the estrogen-dependent breast cancer cells MCF-7 and the resistant subline MCF-7/T developed by long-term cultivation of MCF-7 cells in the presence of antiestrogen tamoxifen, we investigated the possible changes in the hormonal sensitivity of these cells caused by the co-cultivation in vitro. For this purpose MCF-7/T cells were transfected with the plasmid containing the gene of the green fluorescent protein (GFP), and GFP-positive hormone-resistant subline MCF-7/T/GFP+ was developed. The GFP expression should allow to distinguish the resistant and parental cells during co-cultivation.

To study the influence of the co-cultivation on the cell sensitivity to tamoxifen the parent MCF-7 cells (GFP-negative) were co-cultivate with the resistant MCF-7/T/GFP+/cells for 10 days, then the cells were treated with tamoxifen and the efficiency of growth inhibitory tamoxifen action was determined. We found, that the co -cultivation of the parent and resistant cells lead to increase in the resistance of the parent cell to tamoxifen, indicating the important role of the contacts, direct or indirect, between hormone sensitive and resistant cells in the development of hormone resistance.

In general, we evaluate the established results as the first evidence of the possible involvement of the cell–cell underrelations in the realization of the hormonal response, and suppose that the next investigations will give a new insights in the molecular mechanisms of this effects and its role in the formation of the hormone-resistant phenotype of the tumors.

Discovery of new pharmacologically active small molecules is an important and rapidly expanding area of modern molecular pharmacology. Given a limited number of proteins that are druggable, it is important to identify as many chemical effectors as possible to define the best regimen of anti-cancer therapy in each particular case. An E3 ubiquitin ligase, Mdm2, which mediates ubiquitin-dependent degradation of the critical tumor suppressor p53, is a promising target for small molecule inhibitors. Using a hybrid approach which combines the rational design of small molecules selected from the virtual library and the high-content screening using cancer cell lines we discovered several new inhibitors of the p53-Mdm2 interaction. These compounds were able to activate and stabilize the p53 protein causing massive apoptosis preferably in p53-positive cells at rates higher than the well-known inhibitor of Mdm2, Nutlin-3. The molecular mechanisms of their action will be discussed.

As another example of rational design of potential anti-cancer drugs, we will talk about artificial nano-Matrix-Imprinted -Polymers (MIPs) that recognize the structure of peptides and other biological molecules and thus dubbed as “plastic antibodies”. We have generated such nanoparticles against the surface region of the oncogenic receptor, EGFR, which is overexpressed in many forms of solid tumors. Selection of the linear epitope for creating “plastic antibodies” against the receptor was performed by analysis of a three-dimensional structure of the protein. The obtained “plastic antibodies” were specific against the epitope of EGFR. These plastic antibodies when loaded with a genotoxic drug, doxorubicin, were able to specifically induce cell death of breast cancer cell lines that overexpress the EGFR receptor. Experiments in vivo using xenografts of breast cancer cell lines pre-incubated with these plastic antibodies in nude mice showed that they have a pronounced therapeutic effect. Furthermore, since the commercial drug, Cetuximab, recognizes an epitope of EGFR, different from the one recognized by our plastic antibodies, it is likely that the latter may increase the efficacy of the commercial monoclonal antibody. Collectively, we demonstrate that the rationally designed small molecules can be potent and specific drugs for anti-cancer therapy.

Combined analyses of molecular data, such as DNA copy-number alteration, mRNA and protein expression, point to biological functions and molecular pathways being deregulated in multiple cancers. Genomic, metabolomic and clinical data from a variety of solid cancers and model systems are emerging and can be used to identify novel patient subgroups for tailored therapy and monitoring. The first solid tumor to be profiled by expression arrays was carcinoma of the breast. The most reproducible classification by mRNA expression is based on the biological entities referred to as the intrinsic subtypes; Luminal A, Luminal B, Basal-like, HER2 enriched, and the Normal-like groups. In the past decade a number of molecular studies to classify breast cancer have added one or two additional molecular levels, most frequently DNA copy number, and gene sequencing. However, few of the studies have integrated more than two levels of information from the same patients. We have in our lab collected several layers of high throughput molecular data, TP53 mutation status and high throughput paired end sequencing on a dataset of 110 patients. This dataset was clustered according to each molecular level studied using an unbiased, unsupervised clustering, and survival KM plots for each patient subgroup was created. While some samples always cluster together at any molecular level, others cluster in different groups according to each particular molecular endpoint. Therefore, we used an integrated approach to understand breast cancer heterogeneity by modeling mRNA, copy number alterations, microRNAs, and methylation in a pathway context utilizing the pathway recognition algorithm using data integration on genomic models (PARADIGM). We show that massive interleukin signaling profiles are observed in invasive cancers and are absent or weakly expressed in healthy tissue but already prominent in ductal carcinoma in situ, together with ECM and cell-cell adhesion regulating pathways. A good correlation was observed between methylation and mRNA expression based classification (p = 2.29 × 10⁻⁶). Using PARADIGM based on mRNA and miRNA expression, CNAs, and methylation five new clusters with survival differences were revealed. Given the increasing importance of immune constitution for the success of chemotherapy and targeted treatment, this additional information may prove useful in the clinic in the future.