Tumor markers in breast cancer--evaluation of their clinical usefulness.

Breast cancer is the most common neoplasm affecting women in the Western world. Many studies are still conducted with the purpose of finding markers that could be used for early diagnosis and/or serve as possible reliable prognostic or predictive parameters, but with conflicting results. At present, no markers are available for an early diagnosis of breast cancer For surveillance of patients with diagnosed breast cancer the most widely used serum markers are CA 15-3 and CEA which, in combination with other clinical parameters, could have clinical significance. The most useful and clinically important tissue-based markers in breast cancer are estrogen and progesterone receptors, used as a basis for hormonal therapy, and HER-2 receptors, essential in selecting patients for the treatment with Herceptin. New or potentially new markers for breast cancer include BRCA1 and BRCA2 genes for selecting patients at high risk of developing hereditary breast cancer, as well as urokinase plasminogen activator and inhibitor for assessing prognosis in lymph node-negative patients. Results of tumor and patient genetic analyses including their clinical evaluation will enable application of more individualized and personalized approach in diagnosis and therapy of breast cancer patients.

Selective interaction of microcystin congeners with zebrafish (Danio rerio) Oatp1d1 transporter.

Microcystins (MCs) are the most studied cyanotoxins. The uptake of MCs in cells and tissues of mammals and fish species is mostly mediated by organic anion-transporting polypeptides (OATPs in humans and rodents; Oatps in other species), and the Oatp1d1 appears to be a major transporter for MCs in fish. In this study, six MC congeners of varying physicochemical properties (MC-LR, -RR, -YR, -LW, -LF, -LA) were tested by measuring their effect on the uptake of model Oatp1d1 fluorescent substrate Lucifer yellow (LY) in HEK293T cells transiently or stably overexpressing zebrafish Oatp1d1. MC-LW and -LF showed the strongest interaction resulting in an almost complete inhibition of LY transport with IC50 values of 0.21 and 0.26 µM, while congeners -LR, -YR and -LA showed lower inhibitory effects. To discern between Oatp1d1 substrates and inhibitors, results were complemented by Michaelis-Menten kinetics and chemical analytical determinations of MCs uptake, along with molecular docking studies performed using the developed zebrafish Oatp1d1 homology model. Our study showed that Oatp1d1-mediated transport of MCs could be largely dependent on their basic physicochemical properties, with log POW being the most obvious determinant. Finally, apart from determination of the chemical composition of cynobacterial blooms, a reliable risk assessment should take into account the interaction of identified MC congeners with Oatp1d1 as their primary transporter, and herewith we demonstrated that such a comprehensive approach could be based on the use of highly specific in vitro models, accompanied by chemical assessment and in silico molecular docking studies.

Evaluation of cyanobacterial toxicity using different biotests and protein phosphatase inhibition assay.

Cyanobacteria are prolific producers of numerous toxic compounds, among which microcystins (hepatotoxins) are the most frequently found. Cyanobacterial bloom in freshwaters is an increasing problem, and there is still a need for rapid and reliable methods for the detection of toxic cyanobacterial samples. In the present study, the toxicity of crude extracts of 11 cyanobacterial strains from different genera has been assessed on two cell lines (human hepatocellular carcinoma HepG2 and rainbow trout (Oncorhynchus mykiss) liver-derived RTL-W1 cells), crustaceans (Daphnia magna and Artemia salina), and zebrafish (Danio rerio) embryos, as well as by protein phosphatase 1 (PP1) inhibition assay and ELISA test to determine whether the toxicity could be due to the presence of hepatotoxins/microcystins. All the tested strains exhibited toxicity on HepG2 cell line (IC50 from 35 to 702 µg mL-1), including Arthrospira (Spirulina) strains, while toxicity against the RTL-W1 cells was detected only in the positive reference Microcystis PCC 7806 and Nostoc 2S9B. Tested strains expressed higher toxicity to D. magna and zebrafish embryos in comparison to A. salina, whereby Nostoc LC1B and Nostoc S8 belonged to the most toxic strains. The PP1-inhibiting compounds have been detected by PP1 assay only in four strains (Microcystis PCC 7806, Oscillatoria K3, Nostoc LC1B, and Nostoc S8), indicating that their toxic potency can be attributed to these compounds. On the other hand, very low levels of microcystins, as confirmed by ELISA, were insufficient to explain toxicity and different toxic potencies of tested cyanobacteria. Results presented in this study suggested HepG2 cell line as a particularly suitable model for cyanobacterial toxicity assessment. In addition, they highlight terrestrial cyanobacterial strains as potent producers of toxic compounds.

Environmental contaminants modulate transport activity of zebrafish organic anion transporters Oat1 and Oat3.

Organic anion transporters (OATs) are transmembrane proteins which belong to SLC22 subfamily. They are responsible for the uptake of various endo- and xenobiotics into the cells of different organs and tissues. Following our previous work on characterization of zebrafish Oat1 and Oat3, in this study we analyzed interaction of various classes of environmental contaminants with these membrane transporters using the transport activity assay with HEK293 Flp-In cell line stably overexpressing zebrafish Oat1 and Oat3, respectively. Based on the initial screening of a series of 36 environmental contaminants on their ability to interact with zebrafish Oat1 and Oat3, the most potent interactors were selected, their IC50 values calculated and type of interaction determined. Finally, to further confirm the type of interaction and initially evaluate their toxic potential, the cytotoxicity assays were performed. Broad ligand selectivity and similarity of zebrafish Oat1 and Oat3 with mammalian orthologs was confirmed and potent interactors among environmental contaminants identified.

Assessing the clinical significance of tumor markers in common neoplasms.

The term tumor markers include a spectrum of molecules and substances with widely divergent characteristics whose presence in the significant amount can be related to the malignant disease. An ideal tumor marker should have high specificity and sensitivity, which would allow its use in early diagnosis and prognosis of malignant disease, as well as in prediction of therapeutic response and follow-up of the patients. Numerous biochemical entities have emerged as potentially valuable tumor markers so far, but only few markers showed to be of considerable clinical reliability and have been accepted into standard clinical practice. Recent development of genomics and proteomics has enabled the examination of many new potential tumor markers. Scientific studies on discovery, development, and application of tumor markers have been proceeding quite rapidly providing great opportunities for improving the management of cancer patients. This review is focusing on the clinical usefulness of various tumor markers already in clinical practice as well as certain potential markers, giving a brief description of their prognostic and predictive significance in most common malignancies.

Prognostic significance of carbonic anhydrase IX (CA-IX), endoglin (CD105) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in breast cancer patients.

The aim of this study was to examine the prognostic significance of carbonic anhydrase IX (CA-IX), an endogenous marker for tumor hypoxia; endoglin (CD105), a proliferation-associated and hypoxia-inducible glycoprotein and 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative DNA lesion, in breast cancer patients. Immunohistochemical expressions of CA-IX, CD105 and 8-OHdG, analyzed on paraffin-embedded tumor tissues from forty female breast cancer patients, were used to assess their prognostic implication on overall survival (OS) and relapse-free survival (RFS). Patients with high CA-IX expression (above cut-off value) had a higher occurrence of relapse (P = = 0.002). High CA-IX expression was significantly associated with shorter RFS (P < 0.001, hazard ratio (HR) 0.21) and shorter OS (P < 0.001, HR 0.19). Lymph node negative patients with high CA-IX expression had worse RFS (P = 0.031, HR 0.14) and OS (P = 0.005, HR 0.05). Patients with grade I&II tumors and high CA-IX expression showed shorter RFS (P = 0.028, HR 0.28) and OS (P = 0.008, HR 0.20). Worse OS (P = 0.046, HR 0.28) was found in subgroup of patients with grade II tumors and high CA-IX expression. Among all three markers, only high CA-IX expression was strong independent prognostic indicator for shorter OS (HR 4.14, 95% CI 1.28-13.35, P = 0.018) and shorter RFS (HR 3.99, 95% CI 1.38-11.59, P = 0.011). Elevated expression of CA-IX was an independent prognostic factor for decreased RFS and OS and a significant marker for tumor aggressiveness. CD105 had week prognostic value; whereas, 8-OHdG, in this study, did not provide sufficient evidence as a prognostic indicator in breast cancer patients.