Lucia Bialesova

Proteomic analysis of changes in the protein composition of MCF-7 human breast cancer cells induced by all-trans retinoic acid, 9-cis retinoic acid, and their combination.

Retinoic acid (all-trans and 9-cis) isomers represent important therapeutic agents for many types of cancers, including human breast cancer. Changes in protein composition of the MCF-7 human breast cancer cells were induced by all-trans retinoic acid, 9-cis retinoic acid, and their combination and subsequently proteomic strategies based on bottom-up method were applied. Proposed approach was used for the analysis of proteins extracted from MCF-7 human breast cancer cell line utilizing a commercially manufactured kit RIPA and separated on two dimensional (2D) sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) after treatment with both retinoic acid isomers. We found significant differences in occurrence of proteins probably affecting the cell migration process in tumour cells. Heat shock protein 27, ribonucleoprotein SmD3, and cofilin-1 were significantly upregulated after treatment with combination of individual retinoic acid isomers. On the other hand, AP-5 complex subunit beta-1 shows the different response. Thus, the results might help to find the answer to important medical questions on (i) the identification of signaling pathways affected by retinoic acid isomers or (ii) how the observed proteomic pattern might reflect the effectiveness of retinoic acids treatment.

Agonistic effect of selected isoflavones on arylhydrocarbon receptor in a novel AZ-AhR transgenic gene reporter human cell line.

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that controls the expression of a diverse set of genes. Structurally diverse compounds bind to AhR and act as AhR agonists. Well characterised family of natural AhR ligands are isoflavones, which are compounds found predominantly in soy beans or red clover. In this study we have examined agonistic effect of selected isoflavones (genistein, daidzein, biochanin A, formononetin and equol) on AhR in the novel transgenic gene reporter human cell line AZ-AhR, a stably transfected AhR-responsive cell line allowing rapid and sensitive assessment of AhR transcriptional activity. We demonstrated that biochanin A, formononetin and genistein at concentration 10(-4) mol/l exerted agonistic effects on AhR with fold activation of 309- fold, 108-fold and 27-fold, which is about 84.8%, 29.6% and 7.4%, respectively, of the value attained by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Daidzein and equol did not show any significant effects on AhR.

Nuclear receptors - target molecules for isoflavones in cancer chemoprevention

Breast cancer is the most occurring type of cancer among women. In Slovakia, there are yearly diagnosed about 1900 new cases of this disease. Breast cancer treatment is very expensive, psychic stressful and in some cases ineffective. Therefore, it is essential to search for new and/or alternative methods for breast cancer treatment, since nuclear receptors are considered to be a central goal for maximizing treatment opportunities in breast cancer. Among natural ligands for estrogen receptors (ERα and ERβ), which are member of nuclear receptors superfamily, belongs also isoflavones. These natural compounds have similar structure to main female hormon-17β estradiol. A rich source of isoflavones is soy and its products. Three aglycones form of isoflavones (genistein, daidzein, glycitein) are predominantly found in soybean and red clover. Among other important isoflavones belongs also biochanin A and formononetin.

Expression mRNA pattern of retinoic acid and retinoid X nuclear receptor subtypes in thyroid carcinomas

Retinoid receptors (RARs) upon a proper ligand binding act as all-trans retinoic acid-inducible transcription factors interacting as heterodimers with retinoid X receptors (rexinoid receptors, RXRs). The objective of this study was to evaluate all retinoid/ rexinoid nuclear receptor subtypes (RARalpha, RARbeta, RARgamma, RXRalpha, RXRbeta, RXRgamma) expression pattern in thyroid tumour tissue of patients with different types of thyroid cancer in order to compare it with that of the intact thyroid tissue of the corresponding patient. The expression of the retinoid/rexinoid nuclear receptor subtypes has been analyzed by the semiquantitative RT-PCR technique. Papillary thyroid carcinoma (PTC) patients expressed RXRgamma when compared to non-neoplastic thyroid tissues of the corresponding patients that were lacking to express RXRgamma or its expression was very low. Moreover, we have found significantly increased expression of RARalpha and RARgamma in overall group of PTC patients. This increase was detected in cases with positive lymph node metastasis (LNM), but not with negative LNM. On the other hand, RARbeta was significantly reduced in the subgroup of classic variant (CV) of papillary carcinoma. Expression of RXRgamma in the patient with anaplastic carcinoma was found to be lower than that of patients with papillary carcinoma. Follicular adenoma or malignant lymphoma, and also nonmalignant follicular nodules were expressing all RAR and RXR subtypes. On the other hand, hyperplastic nodule was found to express all RAR or RXR subtypes, except RARgamma. In conclusion, the data on the differences in RAR and RXR subtype mRNA expression patterns in various thyroid carcinomas might thus enhance therapeutical potentialities, and thus they may find exploitation in clinical oncology, predominantly, in the differential diagnostics of human thyroid neoplasms.